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Volume 14
Issue 8
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Coatings, Volume 14, Issue 8 (August 2024) – 105 articles

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11 pages, 2877 KiB  
Article
Defect Control of Donor Doping on Dielectric Ceramics to Improve the Colossal Permittivity and Temperature Stability
by Wei Wang, Tingting Fan, Songxiang Hu, Jinli Zhang, Xuefeng Zou, Ying Yang, Zhanming Dou, Lin Zhou, Jun Hu, Jing Wang and Shenglin Jiang
Coatings 2024, 14(8), 1024; https://doi.org/10.3390/coatings14081024 - 12 Aug 2024
Abstract
As the demand for miniaturization of electronic devices increases, ceramics with an ABO3 structure require further improvement of the dielectric constant with high permittivity. In the present work, Ba1−1.5xBixTiO3 (BB100xT, x = 0.0025, 0.005, [...] Read more.
As the demand for miniaturization of electronic devices increases, ceramics with an ABO3 structure require further improvement of the dielectric constant with high permittivity. In the present work, Ba1−1.5xBixTiO3 (BB100xT, x = 0.0025, 0.005, 0.0075, 0.01) ceramics were prepared via a solid-state reaction process. The effect of Bi doping on dielectric properties of lead-free relaxor ferroelectric BaTiO3-based ceramics was studied. The results showed that both colossal permittivity (37,174) and a temperature stability of TCC ≤ ±15% (−27–141 °C) were achieved in BB100xT ceramics at x = 0.5%. The A-site donor doping produces A-site vacancies, a larger space for Ti4+, and fluctuation of the component, which is partially responsible for the high permittivity and responsible for the temperature stability. Meanwhile, the contribution of defect dipoles, and IBLC and SBLC effects to polarization leads to the colossal permittivity. The formation of a liquid phase during sintering promotes mass transfer when the doping content is higher than 0.5%. This work benefits the exploration of novel multilayer ceramic capacitors with colossal permittivity and temperature stability via defect engineering. Full article
(This article belongs to the Special Issue High-Performance Dielectric Ceramic for Energy Storage Capacitors)
14 pages, 2968 KiB  
Article
Effect of Sulfuric Acid Immersion on Electrical Insulation and Surface Composition of Amorphous Carbon Films
by Kazuya Kanasugi, Eito Ichijo, Masanori Hiratsuka and Kenji Hirakuri
Coatings 2024, 14(8), 1023; https://doi.org/10.3390/coatings14081023 - 12 Aug 2024
Abstract
Sulfuric acid is a concern for contacts within electronic devices, and the application of amorphous carbon films as thin electrical insulating coatings for small coils requires full investigation of its effects. Five types of amorphous carbon films were fabricated on Si substrates under [...] Read more.
Sulfuric acid is a concern for contacts within electronic devices, and the application of amorphous carbon films as thin electrical insulating coatings for small coils requires full investigation of its effects. Five types of amorphous carbon films were fabricated on Si substrates under different deposition conditions using vacuum coating systems. Based on their optical constants (ISO 23216:2021(E)), the films were classified into three types: hydrogenated amorphous carbon (a-C:H), polymer-like carbon (PLC), and graphite-like carbon (GLC). The structure, surface composition, and electrical insulation properties of the films were evaluated before and after immersion in sulfuric acid. Although the PLC and a-C:H showed progression of surface oxidation due to sulfuric acid immersion, none showed obvious changes in their structure or DC dielectric breakdown field strength due to sulfuric acid immersion, proving their stability. Furthermore, the PLC and a-C:H, which had a relatively low extinction coefficient, exhibited excellent insulation properties. Our results suggest that amorphous carbon films can be useful as thin insulating films for small coils that may come in contact with sulfuric acid. Our study offers a valuable tool for general users in the industry to facilitate selection of electrical insulating amorphous carbon films based on optical constants, such as extinction coefficients. Full article
(This article belongs to the Special Issue Thin Films and Coatings for Energy Storage and Conversion)
14 pages, 7863 KiB  
Article
Analysis of Decorative Paintings in the Dragon and Tiger Hall of Yuzhen Palace: Culture, Materials, and Technology
by Yuhua Zhu, Guodong Qi, Yingmei Guo and Dongmin Wang
Coatings 2024, 14(8), 1022; https://doi.org/10.3390/coatings14081022 - 12 Aug 2024
Abstract
Yuzhen Palace in Wudang Mountain, established in the 10th year of the Yongle reign of the Ming dynasty (1412 AD), is a significant heritage site within the ancient architectural complex of Wudang Mountain, recognized as a UNESCO World Heritage Site. Despite being entirely [...] Read more.
Yuzhen Palace in Wudang Mountain, established in the 10th year of the Yongle reign of the Ming dynasty (1412 AD), is a significant heritage site within the ancient architectural complex of Wudang Mountain, recognized as a UNESCO World Heritage Site. Despite being entirely relocated, the original paintings on the wooden beams of the Dragon and Tiger Hall exhibit clear characteristics of early Ming dynasty style, potentially being the only surviving wooden painted structures from the Ming dynasty in Wudang Mountain. To protect these valuable cultural relics and provide accurate information regarding the construction period of the paintings, this study sampled the paintings from the central and western sections of the front eaves in the Dragon and Tiger Hall. Using optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, and infrared spectroscopy, the study analyzed the stylistic features, material composition, and craftsmanship of the paintings. The results indicate that the paintings are typical official Xuanzi paintings from the early Ming dynasty, consistent with the style of the Golden Roof in Taihe Palace, Wudang Mountain. The pigments used are all natural minerals: azurite (2CuCO3·Cu(OH)2) for blue, malachite (CuCO3·Cu(OH)2) for green, and vermilion (HgS) and hematite (Fe2O3) for red, reflecting typical early Ming dynasty characteristics. The craftsmanship shows that the paintings were applied directly onto the wooden components without a ground layer, using ink lines to outline the images, and a thin ground layer made of tung oil mixed with lime was applied under the oil coating. This study provides scientific material analysis and data support for the subsequent protection and restoration of the Yuzhen Palace architectural complex, ensuring the preservation of these historically and artistically significant relics for future generations. Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
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<p>Aerial view of the entire Yuzhen Palace.</p> Full article ">Figure 2
<p>Painting retained after the restoration of the Dragon and Tiger Hall.</p> Full article ">Figure 3
<p>Composition styles of paintings in the Dragon and Tiger Hall.</p> Full article ">Figure 4
<p>Distribution of painted components in the Dragon and Tiger Hall.</p> Full article ">Figure 5
<p>Schematic diagram of sampling locations.</p> Full article ">Figure 6
<p>Schematic diagram of sampling locations.</p> Full article ">Figure 7
<p>Schematic diagram of oil-painted sample.</p> Full article ">Figure 8
<p>The cross-sectional microscopic images of pigment and oil-painted samples (100×).</p> Full article ">Figure 9
<p>The Raman spectra of blue and green pigments: (<b>a</b>) pigment no. 2; (<b>b</b>) pigment no. 4.</p> Full article ">Figure 10
<p>The Raman spectra of red pigments: (<b>a</b>) pigment no. 6; (<b>b</b>) pigment no. 7.</p> Full article ">Figure 11
<p>The Raman spectra of black pigments.</p> Full article ">Figure 12
<p>The surface texture and particle distribution of the pigments: (<b>a</b>) pigment no. 2; (<b>b</b>) pigment no. 4; (<b>c</b>) pigment no. 6; (<b>d</b>) pigment no. 7; (<b>e</b>) pigment no. 3.</p> Full article ">Figure 13
<p>Infrared spectra of no. 7 ground layer and oil-painted layer: (<b>a</b>) no. 7 ground layer; (<b>b</b>) no. 7 oil-painted layer.</p> Full article ">
11 pages, 5665 KiB  
Article
Electrophoretically Deposited TiB2 Coatings in NaF-AlF3 Melt for Corrosion Resistance in Liquid Zinc
by Tao Jiang, Junjie Xu, Chuntao Ge, Jie Pang, Jun Zhang, Geir Martin Haarberg and Saijun Xiao
Coatings 2024, 14(8), 1021; https://doi.org/10.3390/coatings14081021 - 12 Aug 2024
Abstract
Molten salt electrophoretic deposition is a novel method for preparing coatings of transition metal borides such as TiB2, which has emerged in recent years. To broaden the applications of transition metal boride coatings prepared by this method, this paper investigates the [...] Read more.
Molten salt electrophoretic deposition is a novel method for preparing coatings of transition metal borides such as TiB2, which has emerged in recent years. To broaden the applications of transition metal boride coatings prepared by this method, this paper investigates the corrosion resistance of TiB2 coatings, produced through molten salt electrophoretic deposition, to liquid zinc. By applying a cell voltage of 1.2 V (corresponding to an electric field of 0.6 V/cm) for 1 h in molten NaF-AlF3, the nanoscale TiB2 particles migrated to the cathode and were deposited on the graphite substrate, forming a smooth and dense TiB2 coating with a thickness of 43 μm. Subsequently, after subjecting the TiB2-coated graphite to corrosion resistance tested in molten zinc for 120 h of continuous immersion, no cracks were observed on the surface or within the coating. The produced TiB2 coating demonstrated excellent corrosion resistance. These research results suggest that the fully dense TiB2 coating on the graphite substrate, produced through molten salt electrophoretic deposition, exhibits excellent corrosion resistance to liquid zinc. Full article
(This article belongs to the Special Issue Advanced Anticorrosion Coatings and Coating Testing)
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<p>A schematic diagram for the preparation of nanoscale TiB<sub>2</sub> (<b>a</b>), the XRD result (<b>b</b>), and SEM images (<b>c</b>–<b>e</b>) of recovered TiB<sub>2</sub>-containing NaF-AlF<sub>3</sub> solid salts. Elemental EDS-mapping analysis for F, Ti, Na, O, and Al (<b>f</b>–<b>j</b>) corresponding to (<b>c</b>).</p> Full article ">Figure 2
<p><b>A</b> schematic diagram of the MS-EPD process (<b>a</b>), XRD patterns obtained by EPD (<b>b</b>), a cross-sectional SEM image of the TiB<sub>2</sub> coating (<b>c</b>), and a high-magnification SEM image of the TiB<sub>2</sub> coating (<b>d</b>).</p> Full article ">Figure 3
<p>A scratch test for the bonding strength between the TiB<sub>2</sub> coating and the graphite substrate.</p> Full article ">Figure 4
<p>(<b>a</b>,<b>b</b>) Cross-sectional, low-magnification SEM image with line scan analysis. (<b>c</b>,<b>d</b>) Cross-sectional, high-magnification SEM image with corresponding elemental EDS mapping for Ti, C, and F.</p> Full article ">Figure 5
<p>Cross-sectional morphology and EDS linear scan analysis results of graphite with TiB<sub>2</sub> coating after immersion in molten zinc for various durations: 12 h (<b>a</b>–<b>c</b>); 24 h (<b>d</b>–<b>f</b>); 72 h (<b>g</b>–<b>i</b>).</p> Full article ">Figure 6
<p>The corrosion resistance results of the TiB<sub>2</sub> coating in molten zinc (96 h). (<b>a</b>) A low-magnification, cross-sectional SEM image; (<b>b</b>) a high-magnification SEM image at the corner; (<b>c</b>) a high-magnification SEM image on the flat surface; (<b>d</b>) a line scan analysis figure.</p> Full article ">Figure 7
<p>The corrosion resistance results of the TiB<sub>2</sub> coating in molten zinc (120 h). (<b>a</b>) A low-magnification, cross-sectional SEM image; (<b>b</b>) a high-magnification, cross-sectional SEM image; (<b>c</b>,<b>d</b>) cross-sectional mapping and line scan analysis images.</p> Full article ">
15 pages, 8772 KiB  
Article
Numerical Investigation of the Effects of Process Parameters on Temperature Distribution and Cladding-Layer Height in Laser Cladding
by Chenyun Deng, Yingxia Zhu and Wei Chen
Coatings 2024, 14(8), 1020; https://doi.org/10.3390/coatings14081020 - 12 Aug 2024
Abstract
To delve into the effects of process parameters on temperature distribution and cladding-layer height in laser cladding, as well as the interaction between these two aspects, a thermal–fluid coupling numerical model was established considering process parameters (i.e., laser power and scanning velocity), the [...] Read more.
To delve into the effects of process parameters on temperature distribution and cladding-layer height in laser cladding, as well as the interaction between these two aspects, a thermal–fluid coupling numerical model was established considering process parameters (i.e., laser power and scanning velocity), the Marangoni effect, molten pool dynamics, and solid–liquid transition. The numerical findings indicate that the Marangoni effect is the main factor for the growth of the cladding layer. The cladding-layer height increasingly influences heat-transfer efficiency as it develops. Higher laser power or lower scanning velocity, or a combination of both, can lead to higher cladding temperatures and greater cladding-layer height. Under the combination of laser power of 1750 W and scanning velocity of 4 mm/s, the numerical simulation predicts a cladding-layer height of 1.12 mm, which closely aligns with the experimentally determined height of 1.11 mm. Additionally, the comprehensive error being below 5% demonstrates the model’s considerable instructional value for practical applications. Full article
(This article belongs to the Section Laser Coatings)
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<p>The thermophysical properties of powder and substrate: (<b>a</b>) specific heat capacity, (<b>b</b>) viscosity, (<b>c</b>) thermal conductivity, (<b>d</b>) density.</p> Full article ">Figure 2
<p>The schematic illustration of laser cladding.</p> Full article ">Figure 3
<p>Temperature distribution and flow field on surface of cladding layer.</p> Full article ">Figure 4
<p>The temperature maximum of substrate with different process parameters: (<b>a</b>) 3D distribution, (<b>b</b>) contour plot.</p> Full article ">Figure 5
<p>The temperature maximum of cladding layer with different process parameters: (<b>a</b>) 3D distribution, (<b>b</b>) contour plot.</p> Full article ">Figure 6
<p>The evolution of cladding layer from starting position with the process parameter combination of laser power of 1750 W and scanning velocity of 4 mm/s.</p> Full article ">Figure 7
<p>Constant cladding-layer height with different process parameters: (<b>a</b>) 3D distribution, (<b>b</b>) contour plot.</p> Full article ">Figure 8
<p>The horizontal distance from the starting point of constant cladding-layer height to the boundary of specimen with different process parameters: (<b>a</b>) 3D distribution, (<b>b</b>) contour plot.</p> Full article ">Figure 9
<p>The temperature difference between cladding layer and substrate on initial position, arriving at constant cladding-layer height with different process parameters: (<b>a</b>) 3D distribution, (<b>b</b>) contour plot.</p> Full article ">Figure 10
<p>Laser-cladding-related equipment: (<b>a</b>) Reci FMC 4000 CW fiber laser, (<b>b</b>) KUKA six-degree-of-freedom robot system and processing table.</p> Full article ">Figure 11
<p>Macro and micro testing (1750 W/4 mm/s): (<b>a</b>) specimen and position of height measurement after processing, (<b>b</b>) macroscopic cross-section, (<b>c</b>) micrograph of the cross-section.</p> Full article ">Figure 12
<p>Comparison of cladding-layer heights between simulations and experiments under five sets of process parameters.</p> Full article ">
14 pages, 3585 KiB  
Article
Effects of ALD Deposition Cycles of Al2O3 on the Morphology and Performance of FTO-Based Dye-Sensitized Solar Cells
by Elizabeth Adzo Addae, Wojciech Sitek, Marek Szindler, Mateusz Fijalkowski and Krzysztof Matus
Coatings 2024, 14(8), 1019; https://doi.org/10.3390/coatings14081019 - 11 Aug 2024
Viewed by 234
Abstract
In dye-sensitized solar cells (DSSCs), materials classified as Transparent Conducting Oxides (TCOs) have the capacity to conduct electricity and transmit light at the same time. Their exceptional blend of optical transparency and electrical conductivity makes them popular choices for transparent electrodes in DSSCs. [...] Read more.
In dye-sensitized solar cells (DSSCs), materials classified as Transparent Conducting Oxides (TCOs) have the capacity to conduct electricity and transmit light at the same time. Their exceptional blend of optical transparency and electrical conductivity makes them popular choices for transparent electrodes in DSSCs. Fluorine Tin Oxide (FTO) was utilized in this experiment. The optical and electrical characteristics of TCOs may be negatively impacted by their frequent exposure to hostile environments and potential for deterioration. TCOs are coated with passivating layers to increase their performance, stability, and defense against environmental elements including oxygen, moisture, and chemical pollutants. Because of its superior dielectric qualities, strong chemical stability, and suitability with TCO materials, aluminum oxide (Al2O3) was utilized as a passivating layer for the FTO. In this research work, Al2O3 was deposited via atomic layer deposition (ALD) to form thin mesoporous layers as a passivator in the photoanode (working electrode). The work focuses on finding an appropriate thickness of Al2O3 for optimum performance of the dye-sensitized solar cells. The solar simulation and sheet resistance analysis clearly showed 200 cycles of Al2O3 to exhibit an efficiency of 4.31%, which was the most efficient performance. The surface morphology and topography of all samples were discussed and analyzed. Full article
(This article belongs to the Special Issue Advances in Nanomaterials and Coatings for Solar Cells)
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<p>(<b>a</b>) Illustration of the complete procedure for fabricating the dye-sensitized solar cells; (<b>b</b>) illustration of the components of the FTO-Al<sub>2</sub>O<sub>3</sub> dye dye-sensitized solar cells.</p> Full article ">Figure 2
<p>Surface morphology analysis: (<b>a</b>) pure FTO on glass 2 × 2; (<b>b</b>) FTO-Al<sub>2</sub>O<sub>3</sub> on glass 100 cycles 2 × 2; (<b>c</b>) FTO-Al<sub>2</sub>O<sub>3</sub> on glass 200 cycles 2 × 2; (<b>d</b>) FTO-Al<sub>2</sub>O<sub>3</sub> on glass 300 cycles 2 × 2.</p> Full article ">Figure 3
<p>(<b>a</b>) 3D topography of pure FTO; (<b>b</b>) 3D topography of FTO-Al<sub>2</sub>O<sub>3</sub> (100 cycles); (<b>c</b>) 3D topography of FTO-Al<sub>2</sub>O<sub>3</sub> (200 cycles); (<b>d</b>) 3D topography of FTO-Al<sub>2</sub>O<sub>3</sub> (300 cycles).</p> Full article ">Figure 4
<p>SEM images of (<b>a</b>) pure FTO (25× 1000×); (<b>b</b>) pure FTO (50× 1000×); (<b>c</b>) pure FTO (100× 1000×); (<b>d</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 100 cycles (25× 1000×); (<b>e</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 100 cycles (60× 1000×); (<b>f</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 100 cycles (150× 1000×); (<b>g</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 200 cycles (25× 1000×); (<b>h</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 200 cycles (50× 1000×); (<b>i</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 200 cycles (100× 1000×); (<b>j</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 300 cycles (25× 1000×); (<b>k</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 300 cycles (50× 1000×); (<b>l</b>) FTO-Al<sub>2</sub>O<sub>3</sub> 300 cycles (150× 1000×).</p> Full article ">Figure 5
<p>(<b>a</b>) Element count in pure FTO; (<b>b</b>) element count in FTO-Al<sub>2</sub>O<sub>3</sub> 300 cycles.</p> Full article ">Figure 6
<p>Transmittance graph of pure FTO, FTO-Al<sub>2</sub>O<sub>3</sub> 100 cycles, FTO-Al<sub>2</sub>O<sub>3</sub> 200 cycles and FTO-Al<sub>2</sub>O<sub>3</sub> 300 cycles.</p> Full article ">Figure 7
<p>Solar simulation of pure FTO, FTO-Al<sub>2</sub>O<sub>3</sub> 100 cycles FTO-Al<sub>2</sub>O<sub>3</sub> 200 cycles, and FTO-Al<sub>2</sub>O<sub>3</sub> 300 cycles dye-sensitized solar cells.</p> Full article ">
16 pages, 5250 KiB  
Article
The Evaluation of the Cytotoxicity and Corrosion Processes of Porous Structures Manufactured Using Binder Jetting Technology from Stainless Steel 316L with Diamond-like Carbon Coating
by Dorota Laskowska, Katarzyna Mitura, Błażej Bałasz, Piotr Wilczek, Aneta Samotus, Witold Kaczorowski, Jacek Grabarczyk, Lucie Svobodová, Totka Bakalova and Stanisław Mitura
Coatings 2024, 14(8), 1018; https://doi.org/10.3390/coatings14081018 - 11 Aug 2024
Viewed by 222
Abstract
With the growing interest in additive manufacturing technology, assessing the biocompatibility of manufactured elements for medical and veterinary applications has become crucial. This study aimed to investigate the corrosion properties and cytotoxicity of porous structures designed to enhance the osseointegration potential of implant [...] Read more.
With the growing interest in additive manufacturing technology, assessing the biocompatibility of manufactured elements for medical and veterinary applications has become crucial. This study aimed to investigate the corrosion properties and cytotoxicity of porous structures designed to enhance the osseointegration potential of implant surfaces. The structures were fabricated using BJ technology from 316L stainless steel powder, and their surfaces were modified with a DLC coating. The studies carried out on porous metal samples with and without DLC coatings demonstrated low cytotoxicity. However, no significant differences were found between the uncoated and DLC-coated samples, likely due to variations in the thickness of the coating on the porous samples and the occurrence of mechanical damage. Full article
(This article belongs to the Collection Feature Paper Collection in 'Surface Coatings for Biomedicine and Bioengineering')
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<p>Types of carbon nanoparticles with their characterizations and applications, used with permission of the authors of [<a href="#B45-coatings-14-01018" class="html-bibr">45</a>].</p> Full article ">Figure 2
<p>CAD models and geometrical dimension of tested substrates to (<b>A</b>,<b>B</b>) electrochemical corrosion tests and (<b>C</b>) cytotoxicity tests.</p> Full article ">Figure 3
<p>SEM images of tested substrates: (<b>A</b>) flat substrate with as-built surface without DLC coating; (<b>B</b>) substrate with porous structure without DLC coating; (<b>C</b>) flat substrate with as-built surface with DLC coating; and (<b>D</b>) substrate with porous structure with DLC coating.</p> Full article ">Figure 4
<p>SEM images of (<b>A</b>) cross-section of porous structure with DLC coating; and (<b>B</b>) DLC coating deposited on porous structure with thickness variation marked by blue arrows, based on Laskowska et al. [<a href="#B48-coatings-14-01018" class="html-bibr">48</a>].</p> Full article ">Figure 5
<p>OPC potential for tested substrates manufactured using binder jetting technology from stainless steel 316L powder (<b>A</b>) without DLC coating and (<b>B</b>) with DLC coating.</p> Full article ">Figure 6
<p>Potentiodynamic polarization curves for the tested substrates manufactured using binder jetting technology from stainless steel 316L powder (<b>A</b>) without DLC coating and (<b>B</b>) with DLC coating.</p> Full article ">Figure 7
<p>Cell viability in the presence of metal tested samples without and with DLC coating.</p> Full article ">Figure 8
<p>Assessment of metabolic activity in the presence of metal tested samples without and with DLC coating.</p> Full article ">Figure 9
<p>Assessment of metabolic activity in the presence of metal tested samples without and with DLC coating.</p> Full article ">Figure 10
<p>The fluorescence microscope shows the fibroblast line, clone L929 (green fluorescence) in (<b>A</b>) the negative control—fresh culture medium without additives; (<b>B</b>) the positive control—fresh culture medium with sodium cyanide added at a concentration of 1.25 mg/mL; (<b>C</b>) the reference samples—extract from unmodified discs or unmodified discs; and (<b>D</b>) test samples—extract from DLC discs or DLC discs.</p> Full article ">
17 pages, 13049 KiB  
Article
Effect of Trace Elements on the Thermal Stability and Electrical Conductivity of Pure Copper
by Haitao Liu, Jincan Dong, Shijun Liang, Weiqiang Li and Yong Liu
Coatings 2024, 14(8), 1017; https://doi.org/10.3390/coatings14081017 - 10 Aug 2024
Viewed by 246
Abstract
Abstract: The impact of introducing trace transition elements on the thermal stability and conductivity of pure copper was examined through metallographic microscopy (OM), transmission electron microscopy (TEM), and electrical conductivity measurements; the interaction between trace transition element and trace impurity element S in [...] Read more.
Abstract: The impact of introducing trace transition elements on the thermal stability and conductivity of pure copper was examined through metallographic microscopy (OM), transmission electron microscopy (TEM), and electrical conductivity measurements; the interaction between trace transition element and trace impurity element S in the matrix was analyzed. The results show that the addition of trace Ti and trace Cr, Ni, and Ag elements significantly enhances the thermal stability of the pure copper grain size. After high-temperature treatment at 900 °C/30 min, the grain sizes of Cu, Cu-Ti-S, and Cu-Cr-Ni-Ag-S were measured and found to be 200.24 μm, 83.83 μm, and 31.08 μm, respectively, thus establishing a thermal stability ranking of Cu-Cr-Ni-Ag-S > Cu-Ti-S > Cu. Furthermore, the conductivities of pure copper remain high even after the addition of trace transition elements, with recorded values for Cu, Cu-Ti-S, and Cu-Cr-Ni-Ag-S of 100.7% IACS, 100.2% IACS, and 98.5% IACS, respectively. The enhancement of thermal stability is primarily attributed to the pinning effect of the TiS and CrS phases, as well as the solid solution dragging of Ni and Ag elements. Trace Ti and Cr elements can react with S impurities to form a hexagonal-structure TiS phase and monoclinic-structure CrS phase, which are non-coherent with the matrix. Notably, the CrS phase is smaller than the TiS phase. In addition, the precipitation of these compounds also reduces the scattering of free electrons by solute atoms, thereby minimizing their impact on the alloy’s conductivity. Full article
(This article belongs to the Special Issue Surface Modification of Advanced Transition Metal-Based Materials for Electrochemical Energy Storage)
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<p>Experimental process.</p> Full article ">Figure 2
<p>Effect of trace elements on the cold-rolled conductivity of 4N pure copper.</p> Full article ">Figure 3
<p>Effect of trace transition group elements on the conductivity of pure copper at different temperatures.</p> Full article ">Figure 4
<p>Optical micrographs of pure copper with trace element 4N added in a cold-rolled state: (<b>a</b>) optical micrograph of 4Ncu; (<b>b</b>) 4N Cu-Ti-S optical micrograph; and (<b>c</b>) 4N Cu-Cr-Ni-Ag-S optical micrograph.</p> Full article ">Figure 5
<p>Optical micrograph and average grain size of 4N pure copper with different trace elements added after high-temperature treatment in a cold-rolled state: (<b>a</b>) 4Ncu optical micrograph; (<b>b</b>) 4N Cu-Ti-S optical micrographs; (<b>c</b>) 4N Cu-Cr-Ni-Ag-S optical micrograph; and (<b>d</b>) average grain size.</p> Full article ">Figure 6
<p>Recrystallization temperature curves of 4N pure copper with different trace elements added.</p> Full article ">Figure 7
<p>Optical micrographs of 4N Cu pure copper at different annealing temperatures: (<b>a</b>) optical micrograph at 30 °C/1 h; (<b>b</b>) optical micrograph at 160 °C/1 h; (<b>c</b>) optical micrograph at 190 °C/1 h; and (<b>d</b>) optical micrograph at 280 °C/1 h.</p> Full article ">Figure 8
<p>Optical micrographs of 4Ncu-Ti-S at different annealing temperatures: (<b>a</b>) optical micrograph at 30 °C/1 h; (<b>b</b>) optical micrograph at 160 °C/1 h; (<b>c</b>) optical micrograph at 190 °C/1 h; and (<b>d</b>) optical micrograph at 280 °C/1 h.</p> Full article ">Figure 9
<p>Optical micrographs of 4Ncu-Cr-Ni-Ag-S at different annealing temperatures: (<b>a</b>) optical micrograph at 30 °C/1 h; (<b>b</b>) optical micrograph at 160 °C/1 h; (<b>c</b>) optical micrograph at 190 °C/1 h; and (<b>d</b>) optical micrograph at 280 °C/1 h.</p> Full article ">Figure 10
<p>Dislocation and precipitated phase analysis of cold-rolled-state 4N Cu-Ti-S: (<b>a</b>) dislocation wall; (<b>b</b>) dislocation cells; (<b>c</b>) HAADF-STEM images at the grain boundary; and (<b>d</b>) HAADF-STEM images within the grains.</p> Full article ">Figure 11
<p>Precipitated phase analysis of cold-rolled 4N Cu-Ti-S at the grain boundary: (<b>a</b>) BF-TEM image; (<b>b</b>) EDS surface scan of titanium; (<b>c</b>) EDS surface scan of sulfur elements; (<b>d</b>) EDS spot scanning of precipitated phase; (<b>e</b>) SAD image of precipitated phase; and (<b>f</b>) TEM high-resolution morphology of the interface between the TiS phase and Cu matrix.</p> Full article ">Figure 12
<p>Precipitated phase analysis of cold-rolled 4N Cu-Ti-S within the grain boundary: (<b>a</b>) BF-TEM image; (<b>b</b>) EDS surface scan of titanium; (<b>c</b>) EDS surface scan of sulfur elements; (<b>d</b>) EDS spot scanning of precipitated phase; (<b>e</b>) SAD image of precipitated phase; and (<b>f</b>) TEM high-resolution morphology of the interface between the TiS phase and Cu matrix.</p> Full article ">Figure 13
<p>Dislocation and precipitated phase analysis of cold-rolled-state 4N Cu-Cr-Ni-Ag-S: (<b>a</b>) dislocation wall; (<b>b</b>) dislocation cells; (<b>c</b>) HAADF-STEM images at the grain boundary; and (<b>d</b>) HAADF-STEM images within the grain boundary.</p> Full article ">Figure 14
<p>Precipitated phase analysis of cold-rolled 4N Cu-Cr-Ni-Ag-S at the grain boundary: (<b>a</b>) BF-TEM image; (<b>b</b>) EDS surface scan of copper elements; (<b>c</b>) EDS surface scan of chromium elements; (<b>d</b>) EDS surface scan of nickel elements; (<b>e</b>) EDS surface scan of silver elements; (<b>f</b>) EDS surface scan of sulfur elements; (<b>g</b>) EDS spot scanning of precipitated phase; (<b>h</b>) SAD image of precipitated phase; and (<b>i</b>) TEM high-resolution morphology of the interface between the CrS phase and Cu matrix.</p> Full article ">Figure 15
<p>Precipitated phase analysis of cold-rolled 4N Cu-Cr-Ni-Ag-S within the grain boundary: (<b>a</b>) BF-TEM image; (<b>b</b>) EDS surface scan of copper elements; (<b>c</b>) EDS surface scan of chromium elements; (<b>d</b>) EDS surface scan of nickel elements; (<b>e</b>) EDS surface scan of silver elements; (<b>f</b>) EDS surface scan of sulfur elements; (<b>g</b>) EDS spot scanning of precipitated phase; (<b>h</b>) SAD image of precipitated phase; and (<b>i</b>) TEM high-resolution morphology of the interface between the CrS phase and Cu matrix.</p> Full article ">Figure 16
<p>Schematic diagram of the mechanism of action of trace alloying elements on the thermal stability of pure copper.</p> Full article ">
18 pages, 9616 KiB  
Article
Endurance to Multiple Factors of Water-Based Electrically Conductive Paints with Metallic Microparticles
by Alina Ruxandra Caramitu, Romeo Cristian Ciobanu, Mihaela Aradoaei, Magdalena Valentina Lungu, Nicoleta Oana Nicula and Eduard Marius Lungulescu
Coatings 2024, 14(8), 1016; https://doi.org/10.3390/coatings14081016 - 10 Aug 2024
Viewed by 180
Abstract
The paper describes the innovative adaptation of some specific environmental tests from general organic coatings towards newly developed water-based composite paints with metallic particles (Al and Fe), with a high content of metal (10% and respectively 20%) for electromagnetic shielding applications. Electrical conductivity [...] Read more.
The paper describes the innovative adaptation of some specific environmental tests from general organic coatings towards newly developed water-based composite paints with metallic particles (Al and Fe), with a high content of metal (10% and respectively 20%) for electromagnetic shielding applications. Electrical conductivity is the most affected dielectric parameter under both by UV radiation and thermal exposure. The paints with 20% metallic powder are more sensitive to environmental factors, and the influence of metal type could also be emphasized in relation to the dielectric feature evolution vs. exposure time. The action of mold significantly decreases the dielectric features of paints, but the weathering aging effect is much more enhanced if the samples are cumulatively submitted to thermal aging and respectively UV exposure, along with the action of mold. The potential application of the study is related mainly to the development of new autonomous electric cars, which need special conditions of electromagnetic shielding, under the circumstances that the conductive paint layers are normally very sensitive to environmental factors, affecting the equipment performance and security. Full article
(This article belongs to the Special Issue Dielectric Materials for Energy Storage, Energy Harvesting and Electrocaloric Applications)
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<p>SEM micrographs for (<b>a</b>) Al powder 800 nm and for (<b>b</b>) Fe powder 790 nm [<a href="#B19-coatings-14-01016" class="html-bibr">19</a>].</p> Full article ">Figure 2
<p>ATR/FTIR spectra recorded before metallic powder addition [<a href="#B20-coatings-14-01016" class="html-bibr">20</a>].</p> Full article ">Figure 3
<p>Comparative ATR/FTIR spectra recorded on metal powders [<a href="#B20-coatings-14-01016" class="html-bibr">20</a>].</p> Full article ">Figure 4
<p>Comparative ATR/FTIR spectra recorded on paints with different metal fillers [<a href="#B20-coatings-14-01016" class="html-bibr">20</a>].</p> Full article ">Figure 5
<p>Particle size distribution histogram (MSD) of Al particles by volume.</p> Full article ">Figure 6
<p>Particle size distribution histogram (MSD) of Fe particles by volume.</p> Full article ">Figure 7
<p>Roughness analysis for M1 and M2.</p> Full article ">Figure 8
<p>Roughness analysis for M3 and M4.</p> Full article ">Figure 9
<p>Resistance to the action of (<b>a</b>) water, (<b>b</b>) isopropyl alcohol.</p> Full article ">Figure 10
<p>Tg(Delta) variation vs. time at UV radiation exposure.</p> Full article ">Figure 11
<p>Lifetime evaluation results for UV radiation exposure.</p> Full article ">Figure 12
<p>Tg(Delta) variation vs. time at thermal exposure.</p> Full article ">Figure 13
<p>Lifetime evaluation results for thermal exposure.</p> Full article ">Figure 14
<p>Molds occurrence on M2, after 7 days of exposure [<a href="#B30-coatings-14-01016" class="html-bibr">30</a>].</p> Full article ">Figure 15
<p>Mold occurrence on M3, after 7 days and, respectively, 28 days of exposure [<a href="#B30-coatings-14-01016" class="html-bibr">30</a>].</p> Full article ">Figure 16
<p>Tg(delta) variation at combined action of molds, dry heat, and UV radiation.</p> Full article ">
13 pages, 5513 KiB  
Article
The Influence of Rust Layers on Calcareous Deposits’ Performance and Protection Current Density in the Cathodic Protection Process
by Wei Zhang, Xinran Wang, Haojie Li, Zhifeng Lin and Zhiwei Chen
Coatings 2024, 14(8), 1015; https://doi.org/10.3390/coatings14081015 - 10 Aug 2024
Viewed by 250
Abstract
Calcareous deposits are a consequential outcome of cathodic protection in marine environments, exerting significant influence on the cathodic protection process and current density prerequisites. This study investigates the process of calcium deposition and its impact on the cathodic protection current density of carbon [...] Read more.
Calcareous deposits are a consequential outcome of cathodic protection in marine environments, exerting significant influence on the cathodic protection process and current density prerequisites. This study investigates the process of calcium deposition and its impact on the cathodic protection current density of carbon steel under the influence of a rust layer in different corrosion periods. This was investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results demonstrate that the formation processes of calcareous deposits vary after exposure to the corrosive environment for 0, 7, and 30 days. While a longer corrosion period leads to thicker rust layers on the metal surface and a higher initial cathodic protection current, the presence of these rust layers facilitates the deposition of calcium and magnesium ions, resulting in a rapid decrease in cathodic protection current density after a certain period. Meanwhile, long-term cathodic protection facilitates the thickening and densification of the oxide layer, thereby enhancing its protective efficacy, effectively reducing the corrosion rate of the metal surface and stabilizing the cathodic protection current density at a lower level. This study provides theoretical data and experimental evidence to support the maintenance of corroded marine engineering equipment. Full article
(This article belongs to the Special Issue Corrosion Resistance, Mechanical Properties and Characterization of Metallic Materials and Coatings, 2nd Edition)
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<p>Variation of (<b>a</b>) cathodic protection current density and (<b>b</b>) ratio of current density to initial current density with time in different corrosion states.</p> Full article ">Figure 2
<p>Photograph of samples immersed in corrosion solution for 0 days, (<b>a</b>) 7 days, (<b>b</b>) and 30 days (<b>c</b>) before cathodic protection experiment.</p> Full article ">Figure 3
<p>Photograph of samples immersed in corrosion solution for 0 days, (<b>a</b>) 7 days, (<b>b</b>) and 30 days (<b>c</b>) after 90 days of the cathodic protection experiment.</p> Full article ">Figure 4
<p>The cross-sectional SEM images of the specimens after 90 days of cathodic protection with 0 days of corrosion, (<b>a</b>,<b>b</b>) 7 days, (<b>c</b>,<b>d</b>) and 30 days (<b>e</b>,<b>f</b>), and the corresponding distribution maps of Ca and Mg elements in the cross-sections (<b>b</b>,<b>d</b>,<b>f</b>).</p> Full article ">Figure 5
<p>The Nyquist plots of the specimens after 90 days of cathodic protection with 0 days of corrosion, (<b>a</b>) 7 days, (<b>b</b>) and 30 days (<b>c</b>).</p> Full article ">Figure 6
<p>The equivalent circuit diagram for AC impedance fitting, (<b>a</b>) one time constant, (<b>b</b>) two time constants, (<b>c</b>) applied diffusion tail.</p> Full article ">Figure 7
<p>The variation of the resistance R<sub>f</sub> of the calcium deposition layer with time under different rusting conditions.</p> Full article ">Figure 8
<p>The variation of the resistance R<sub>ct</sub> of the calcium deposition layer with time under different rusting conditions.</p> Full article ">
19 pages, 6025 KiB  
Article
Modeling of Plasma Nitriding of Austenitic Stainless Steel through a Mask
by Paulius Andriūnas, Reda Čerapaitė-Trušinskienė and Arvaidas Galdikas
Coatings 2024, 14(8), 1014; https://doi.org/10.3390/coatings14081014 - 9 Aug 2024
Viewed by 226
Abstract
In this work, 2D simulations of stainless steel nitriding through a mask were performed with two configurations: with and without lateral adsorption under the mask, depending on the strength of the mask adhesion. The stress-induced diffusion and trapping–detrapping process are included as the [...] Read more.
In this work, 2D simulations of stainless steel nitriding through a mask were performed with two configurations: with and without lateral adsorption under the mask, depending on the strength of the mask adhesion. The stress-induced diffusion and trapping–detrapping process are included as the main mechanisms of nitrogen mass transport. The main focus is on the analysis of the swelling process, which affects the expansion of the material. The surface concentration profiles and topographical profiles along the surface are calculated and compared with experimentally registered ones taken from the literature, and they show a good agreement. This allows for estimation of the values of model parameters. Because nitriding processes takes place in vertical and horizontal directions, the anisotropic aspect of nitriding are analyzed. It is shown that the adherence of the mask significantly influences the topographical profile and the anisotropy of nitriding, because in the case of a weakly adhered mask, a lateral adsorption process takes place under the mask. The influence of swelling and anisotropy in the case of pattern nitriding in small dimensions is discussed. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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<p>The schematic presentation of nitriding through a mask in two simulated cases: with (<b>a</b>) and without (<b>b</b>) undermask adsorption.</p> Full article ">Figure 2
<p>Surface topographic profiles (orange) and nitrogen surface concentration profiles (blue) at D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s. Curves (M) are calculated results of the proposed model and E are the experimental results from ref. [<a href="#B34-coatings-14-01014" class="html-bibr">34</a>]. “Mask” and “No Mask” indicate undermask and maskless regions, respectively (see <a href="#coatings-14-01014-f001" class="html-fig">Figure 1</a>).</p> Full article ">Figure 3
<p>Two-dimensional concentration profiles of nitrogen, with undermask adsorption calculated at different diffusion coefficients: (<b>a</b>) D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s; (<b>b</b>) D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s; (<b>c</b>) D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s. Red vertical line shows the position of the mask edge.</p> Full article ">Figure 4
<p>Profiles of average overall nitrogen concentration through all layers (solid lines) and surface topographic profiles (dash lines) at different diffusion coefficients: D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 5
<p>Profiles of nitrogen concentration in parallel to the surface at different diffusion coefficients: D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 6
<p>Profiles of total (Sum), trapped (Trap), and diffusing (Dif) nitrogen surface concentrations in parallel to the surface in the case with undermask adsorption at D = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 7
<p>Depth profiles of nitrogen concentration of entire depth (solid line) and its composition (dash and dotted lines) at different diffusion coefficients: (blue) D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, (green) D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, (red) D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, compared to experimental results from ref. [<a href="#B35-coatings-14-01014" class="html-bibr">35</a>].</p> Full article ">Figure 8
<p>The dependencies of nitriding depth y<sub>N</sub>, width x<sub>N</sub>, and aspect ratio 2x<sub>N</sub>/y<sub>N</sub> on nitriding time in the case with undermask adsorption, calculated at: D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 9
<p>Two-dimensional concentration profiles of nitrogen without undermask adsorption, calculated at different diffusion coefficients: (<b>a</b>) D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s; (<b>b</b>) D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s; (<b>c</b>) D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s. Red vertical line shows the position of the mask edge.</p> Full article ">Figure 10
<p>Profiles of nitrogen average overall concentration through all layers (solid lines) and surface topographic profiles (dash lines) at different diffusion coefficients: D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 11
<p>Profiles of nitrogen concentration parallel to surface, calculated with different diffusion coefficients: D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 12
<p>Profiles of total (Sum), trapped (Trap), and diffusing (Dif) nitrogen surface concentrations in parallel to surface in the case without undermask adsorption at D = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 13
<p>Depth profiles with (w) and without (n) undermask adsorption in the edge region of the mask at D = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">Figure 14
<p>The dependencies of nitriding depth y<sub>N</sub>, width x<sub>N</sub>, and aspect ratio 2x<sub>N</sub>/y<sub>N</sub> on nitriding time in the case without undermask adsorption, calculated at: D<sub>1</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>2</sub> = <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>15</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s, D<sub>3</sub> = <math display="inline"><semantics> <mrow> <mn>1.7</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>16</mn> </mrow> </msup> </mrow> </semantics></math> m<sup>2</sup>/s.</p> Full article ">
20 pages, 8282 KiB  
Article
Effect of Microcapsules of Chitosan-Coated Toddalia asiatica (L.) Lam Extracts on the Surface Coating Properties of Poplar Wood
by Ye Zhu, Ying Wang and Xiaoxing Yan
Coatings 2024, 14(8), 1013; https://doi.org/10.3390/coatings14081013 - 9 Aug 2024
Viewed by 341
Abstract
Using chitosan as the shell material and Toddalia asiatica (L.) Lam extract as the core material, microcapsules of chitosan-coated Toddalia asiatica (L.) Lam extracts were prepared. The microcapsules were added to waterborne topcoats to investigate the effects of different content and MToddalia [...] Read more.
Using chitosan as the shell material and Toddalia asiatica (L.) Lam extract as the core material, microcapsules of chitosan-coated Toddalia asiatica (L.) Lam extracts were prepared. The microcapsules were added to waterborne topcoats to investigate the effects of different content and MToddalia asiatica(L.) Lam extracts:Mchitosan (MT:MC) on the performance of waterborne coatings on poplar surfaces. Under different MT:MC of microcapsules, the content of microcapsules in the coating was negatively correlated with the glossiness, reflectivity, and adhesion of the coating. The addition of microcapsules reduced the liquid resistance of the coating to citric acid and improved the ethanol and cleaning agent resistance of the coating. The hardness, impact resistance, and roughness of the coatings increased gradually with the increase in microcapsule content. The content of microcapsules was positively correlated with the Escherichia coli and Staphylococcus aureus antibacterial performance of coatings, and the coatings had a slightly higher antibacterial rate against Staphylococcus aureus than Escherichia coli overall. The poplar surface coating with 5.0% microcapsules and MT:MC of 4.0:1 was excellent: the gloss was 5.30 GU, the light loss rate was 62.22%, the color difference ΔE was 22.93, the hardness was HB, the impact resistance was grade 3, the adhesion was grade 2, the roughness was 2.022 µm, the resistance to ethanol and cleaning agent was grade 2, and the resistances to Escherichia coli and Staphylococcus aureus were 74.21% and 82.01%, respectively. The results of the study provide a technical reference for the application of antibacterial waterborne coatings on wood surfaces. Full article
(This article belongs to the Section Functional Polymer Coatings and Films)
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<p>Microscopic diagram of microcapsules with different M<sub>T</sub>:M<sub>C</sub>: (<b>A</b>) Sample 1#, (<b>B</b>) Sample 2#, (<b>C</b>) Sample 3#.</p> Full article ">Figure 2
<p>SEM images of microcapsules with different M<sub>T</sub>:M<sub>C</sub>: (<b>A</b>) Sample 1#, (<b>B</b>) Sample 2#, (<b>C</b>) Sample 3#.</p> Full article ">Figure 3
<p>Particle size distribution: (<b>A</b>) 1#, (<b>B</b>) 2#, (<b>C</b>) 3#.</p> Full article ">Figure 4
<p>Infrared spectra of core materials, shell materials, and microcapsules.</p> Full article ">Figure 5
<p>Effects of microcapsules with different M<sub>T</sub>:M<sub>C</sub> and different content on glossiness and light loss rate of poplar surface coatings: (<b>A</b>) glossiness, (<b>B</b>) light loss rate.</p> Full article ">Figure 6
<p>The trend graphs of chromaticity and color difference about surface coatings on poplar wood: (<b>A</b>) <span class="html-italic">L</span> value, (<b>B</b>) <span class="html-italic">a</span> value, (<b>C</b>) <span class="html-italic">b</span> value, (<b>D</b>) Δ<span class="html-italic">E</span> value.</p> Full article ">Figure 7
<p>Effects of microcapsules with different M<sub>T</sub>:M<sub>C</sub> on the reflectivity of poplar surface coating: (<b>A</b>) 1# microcapsule, (<b>B</b>) 2# microcapsule, (<b>C</b>) 3# microcapsule.</p> Full article ">Figure 8
<p>Effect of microcapsules with different M<sub>T</sub>:M<sub>C</sub> and different contents on antibacterial rate of coating: (<b>A</b>) <span class="html-italic">Escherichia coli</span>, (<b>B</b>) <span class="html-italic">Staphylococcus aureus</span>.</p> Full article ">Figure 9
<p>SEM images of wood surface coatings prepared by adding 5.0% microcapsules with different M<sub>T</sub>:M<sub>C</sub>: (<b>A</b>) coatings without microcapsules, coatings with (<b>B</b>) 1#, (<b>C</b>) 2#, (<b>D</b>) 3# microcapsules.</p> Full article ">Figure 10
<p>Infrared spectra of different M<sub>T</sub>:M<sub>C</sub> microcapsule coatings on poplar wood with 5.0% content.</p> Full article ">Figure 11
<p>View of coated poplar wood: (<b>A</b>) with microcapsules, (<b>B</b>) without microcapsules.</p> Full article ">Figure 12
<p>Antimicrobial principle of wood surface coatings.</p> Full article ">
18 pages, 33769 KiB  
Article
Effects of Compound Use of Two UV Coating Microcapsules on the Physicochemical, Optical, Mechanical, and Self-Healing Performance of Coatings on Fiberboard Surfaces
by Yuming Zou, Yongxin Xia and Xiaoxing Yan
Coatings 2024, 14(8), 1012; https://doi.org/10.3390/coatings14081012 - 9 Aug 2024
Viewed by 355
Abstract
Ultraviolet (UV) coatings are widely used because of their good performance. However, the self-healing performance of UV coatings can be further improved. Microcapsule technology can be used to solve this problem. To investigate the effects of the compound use of two UV coating [...] Read more.
Ultraviolet (UV) coatings are widely used because of their good performance. However, the self-healing performance of UV coatings can be further improved. Microcapsule technology can be used to solve this problem. To investigate the effects of the compound use of two UV coating microcapsules on coatings of a fiberboard surface, three kinds of UV primer microcapsules (1#, 2#, and 3# microcapsules) with different contents were added to a UV primer, and a UV top coating was prepared with UV top coating microcapsules at a consistent ratio. The UV coating was used to coat the fiberboard surface by way of a two-primer and two-top coating method. The results show that as the content of the UV primer microcapsules was increased, the self-healing rates of all three groups of coatings increased and later decreased. The color difference ΔE of coatings with the content of the UV primer microcapsules at 4.0% and top coating microcapsules at 6.0% was 3.59, the gloss was 1.33 GU, the reflectance was 21.17%, the adhesion grade was 2, the hardness was 2H, the impact resistance grade was 5, the roughness was 1.085 μm, and the self-healing rate was 30.21%. Compared with the self-healing rate of the blank control group, the increase in the self-healing rate was 10.07%, and the improvement rate was 50.00%. The comprehensive performance of the coating was better. The results provide a technical reference for the application of the UV coating microcapsules in the UV coating on fiberboard surfaces. Incorporating the self-healing UV coating microcapsules into the UV coatings and applying the UV coating microcapsules on the fiberboard surfaces supports the microcapsule technology of self-healing UV coatings, lays the foundation for extending the service life of furniture while improving the furniture’s quality, and promotes the sustainable development of the coating industry. Full article
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<p>The surface morphologies of fiberboards with different contents of 1# microcapsules: (<b>A</b>) 0%, (<b>B</b>) 2.0%, (<b>C</b>) 4.0%, (<b>D</b>) 6.0%, (<b>E</b>) 8.0%, and (<b>F</b>) 10.0%.</p> Full article ">Figure 2
<p>The surface morphologies of fiberboards with different contents of 2# microcapsules: (<b>A</b>) 0%, (<b>B</b>) 2.0%, (<b>C</b>) 4.0%, (<b>D</b>) 6.0%, (<b>E</b>) 8.0%, and (<b>F</b>) 10.0%.</p> Full article ">Figure 3
<p>The surface morphologies of fiberboards with different contents of 3# microcapsules: (<b>A</b>) 0%, (<b>B</b>) 2.0%, (<b>C</b>) 4.0%, (<b>D</b>) 6.0%, (<b>E</b>) 8.0%, and (<b>F</b>) 10.0%.</p> Full article ">Figure 4
<p>SEM images of samples: (<b>A</b>) blank control sample, (<b>B</b>) 2.0% of 1# microcapsules, (<b>C</b>) 2.0% of 2# microcapsules, and (<b>D</b>) 2.0% of 3# microcapsules.</p> Full article ">Figure 5
<p>SEM images of the longitudinal section of samples: (<b>A</b>) uncoated fiberboard and (<b>B</b>) 2.0% of 1# microcapsules.</p> Full article ">Figure 6
<p>Infrared spectrum of coating on fiberboard surface.</p> Full article ">Figure 7
<p>Gloss trend of samples at a 60° incidence angle.</p> Full article ">Figure 8
<p>Reflectance of samples with different contents of microcapsules: (<b>A</b>) 1# microcapsules, (<b>B</b>) 2# microcapsules, and (<b>C</b>) 3# microcapsules.</p> Full article ">Figure 9
<p>Cracks on the samples before and after 1 week of self-healing with different contents of 1# microcapsules. Before self-healing: (<b>A</b>) 0%, (<b>B</b>) 2.0%, (<b>C</b>) 4.0%, (<b>G</b>) 6.0%, (<b>H</b>) 8.0%, and (<b>I</b>) 10.0%, and after self-healing: (<b>D</b>) 0%, (<b>E</b>) 2.0%, (<b>F</b>) 4.0%, (<b>J</b>) 6.0%, (<b>K</b>) 8.0%, and (<b>L</b>) 10.0%.</p> Full article ">Figure 10
<p>Cracks on the samples before and after 1 week of self-healing with different contents of 2# microcapsules. Before self-healing: (<b>A</b>) 0%, (<b>B</b>) 2.0%, (<b>C</b>) 4.0%, (<b>G</b>) 6.0%, (<b>H</b>) 8.0%, and (<b>I</b>) 10.0%, and after self-healing: (<b>D</b>) 0%, (<b>E</b>) 2.0%, (<b>F</b>) 4.0%, (<b>J</b>) 6.0%, (<b>K</b>) 8.0%, and (<b>L</b>) 10.0%.</p> Full article ">Figure 11
<p>Cracks on the samples before and after 1 week of self-healing with different contents of 3# microcapsules. Before self-healing: (<b>A</b>) 0%, (<b>B</b>) 2.0%, (<b>C</b>) 4.0%, (<b>G</b>) 6.0%, (<b>H</b>) 8.0%, and (<b>I</b>) 10.0% and after self-healing: (<b>D</b>) 0%, (<b>E</b>) 2.0%, (<b>F</b>) 4.0%, (<b>J</b>) 6.0%, (<b>K</b>) 8.0%, and (<b>L</b>) 10.0%.</p> Full article ">
21 pages, 6772 KiB  
Article
The Effects of Urea–Formaldehyde Resin-Coated Toddalia asiatica (L.) Lam Extract Microcapsules on the Properties of Surface Coatings for Poplar Wood
by Ye Zhu, Ying Wang and Xiaoxing Yan
Coatings 2024, 14(8), 1011; https://doi.org/10.3390/coatings14081011 - 9 Aug 2024
Viewed by 325
Abstract
Urea–formaldehyde resin was used as a wall material and Toddalia asiatica (L.) Lam extract was used as a core material to prepare urea–formaldehyde resin-coated Toddalia asiatica (L.) Lam extract microcapsules (UFRCTEMs). The effects of UFRCTEM content and the mass ratio of core-to-wall material [...] Read more.
Urea–formaldehyde resin was used as a wall material and Toddalia asiatica (L.) Lam extract was used as a core material to prepare urea–formaldehyde resin-coated Toddalia asiatica (L.) Lam extract microcapsules (UFRCTEMs). The effects of UFRCTEM content and the mass ratio of core-to-wall material (Mcore:Mwall) on the performance of waterborne coatings on poplar surfaces were investigated by adding microcapsules to the waterborne topcoat. Under different Mcore:Mwall of microcapsules, as the content of microcapsules increased, the glossiness and adhesion of the coatings gradually decreased, and the color difference value of the coatings gradually increased. The cold liquid resistance, hardness, and impact resistance of the coatings were all improved, and the roughness of the coatings increased. The antibacterial rates of the coatings against Escherichia coli and Staphylococcus aureus were both on the rise, and the antibacterial rate against Staphylococcus aureus was slightly higher than that against Escherichia coli. When the microcapsule content was 7.0% and the Mcore:Mwall was 0.8:1, the surface coating performance on poplar wood was excellent. The glossiness was 3.43 GU, light loss was 75.55%, color difference ΔE was 3.23, hardness was 2H, impact resistance level was 3, adhesion level was 1, and roughness was 3.759 µm. The cold liquid resistance was excellent, and resistance grades to citric acid, ethanol, and cleaning agents were all 1. The antibacterial rates against Escherichia coli and Staphylococcus aureus were 68.59% and 75.27%, respectively. Full article
(This article belongs to the Special Issue Surface Properties and Surface Treatments of Wood and Wood-Based Composites)
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<p>SEM images of UFRCTEMs with different M<sub>core</sub>:M<sub>wall</sub>. Under low magnification: (<b>A</b>) 0.6:1, (<b>B</b>) 0.8:1%, and (<b>C</b>) 1.2:1. Under high magnification: (<b>D</b>) 0.6:1, (<b>E</b>) 0.8:1, and (<b>F</b>) 1.2:1.</p> Full article ">Figure 2
<p>Infrared spectra of core materials, wall materials, and UFRCTEMs.</p> Full article ">Figure 3
<p>The effects of UFRCTEMs with different M<sub>core</sub>:M<sub>wall</sub> on glossiness and light loss rate of poplar surface coatings: (<b>A</b>) glossiness and (<b>B</b>) light loss rate.</p> Full article ">Figure 4
<p>The effects of UFRCTEMs with different M<sub>core</sub>:M<sub>wall</sub> on chromaticity and color difference of the poplar surface coatings: (<b>A</b>) <span class="html-italic">L</span> value, (<b>B</b>) <span class="html-italic">a</span> value, (<b>C</b>) <span class="html-italic">b</span> value, and (<b>D</b>) Δ<span class="html-italic">E</span>.</p> Full article ">Figure 5
<p>The effects of UFRCTEMs with different M<sub>core</sub>:M<sub>wall</sub> on the reflectivity of the poplar surface coating: (<b>A</b>) 0.6:1, (<b>B</b>) 0.8:1, and (<b>C</b>) 1.2:1.</p> Full article ">Figure 6
<p>Impact resistance test results of coatings (the red circle) with different contents of the #1 microcapsule type: (<b>A</b>) 0%, (<b>B</b>) 1%, (<b>C</b>) 3%, (<b>D</b>) 5%, (<b>E</b>) 7%, and (<b>F</b>) 9%.</p> Full article ">Figure 7
<p>Impact resistance test results of coatings (the red circle) with different contents of the #2 microcapsule type: (<b>A</b>) 1%, (<b>B</b>) 3%, (<b>C</b>) 5%, (<b>D</b>) 7%, and (<b>E</b>) 9%.</p> Full article ">Figure 8
<p>Impact resistance test results of coatings (the red circle) with different contents of the #3 microcapsule type: (<b>A</b>) 1%, (<b>B</b>) 3%, (<b>C</b>) 5%, (<b>D</b>) 7%, and (<b>E</b>) 9%.</p> Full article ">Figure 9
<p>The effects of UFRCTEMs with different M<sub>core</sub>:M<sub>wall</sub> on the antibacterial rate of coatings: (<b>A</b>) antibacterial rate of <span class="html-italic">Escherichia coli</span>, (<b>B</b>) antibacterial rate of <span class="html-italic">Staphylococcus aureus</span>.</p> Full article ">Figure 10
<p>Colony recovery of coatings with different contents of the #2 microcapsule type after the antibacterial test against <span class="html-italic">Escherichia coli</span>: (<b>A</b>) 1%, (<b>B</b>) 3%, (<b>C</b>) 5%, (<b>D</b>) 7%, and (<b>E</b>) 9%.</p> Full article ">Figure 11
<p>Colony recovery of coatings with different contents of the #3 microcapsule type after the antibacterial test against <span class="html-italic">Escherichia coli</span>: (<b>A</b>) 1%, (<b>B</b>) 3%, (<b>C</b>) 5%, (<b>D</b>) 7%, and (<b>E</b>) 9%.</p> Full article ">Figure 12
<p>SEM images of wood surface coatings prepared by adding 7.0% UFRCTEMs with different M<sub>core</sub>:M<sub>wall</sub>: (<b>A</b>) without UFRCTEMs, (<b>B</b>) 0.6:1, (<b>C</b>) 0.8:1, and (<b>D</b>) 1.2:1.</p> Full article ">Figure 13
<p>Infrared spectra of UFRCTEM coatings with different M<sub>core</sub>:M<sub>wall</sub> on a wood surface.</p> Full article ">Figure 14
<p>SEM of the interface between the wood and the coating: (<b>A</b>) with UFRCTEM; (<b>B</b>) without UFRCTEM.</p> Full article ">
17 pages, 9458 KiB  
Article
Surface Roughness and Its Effect on Adhesion and Tribological Performance of Magnetron Sputtered Nitride Coatings
by Pal Terek, Lazar Kovačević, Vladimir Terek, Zoran Bobić, Aleksandar Miletić, Branko Škorić, Miha Čekada and Aljaž Drnovšek
Coatings 2024, 14(8), 1010; https://doi.org/10.3390/coatings14081010 - 9 Aug 2024
Viewed by 249
Abstract
Reports of the influence of surface roughness on the adhesion and tribological performance of contemporary nitride coatings with different layer designs are still scarce in the literature. Therefore, in this study, we evaluated the behavior of a single-layer TiAlN, a bilayer TiAlN/CNx [...] Read more.
Reports of the influence of surface roughness on the adhesion and tribological performance of contemporary nitride coatings with different layer designs are still scarce in the literature. Therefore, in this study, we evaluated the behavior of a single-layer TiAlN, a bilayer TiAlN/CNx, and a nanolayer AlTiN/TiN coating. Coatings were deposited in an industrial magnetron sputtering unit on the substrates of EN 100Cr6 steel, prepared to four degrees of surface roughness (Sa = 10–550 nm). The coatings’ adhesion was determined by scratch tests performed perpendicular and parallel to the machining marks. Dry reciprocating sliding tests in air were employed to evaluate the coatings’ tribological behavior against an Al2O3 ball. Before and after the tests, coating properties were characterized by 3D profilometry, confocal microscopy, and energy dispersive spectroscopy. Deposition of all coatings significantly altered the surface topography and increased the roughness of the samples. No general rule could be established for the effect of surface roughness on tribological behavior and adhesion of different hard coatings. For very fine surface finishes the adhesion and tribological performance of TiAlN and TiAlN/CNx coatings was independent of the surface roughness. For the roughest surfaces, a decrease in adhesion and an increase in the wear rate were observed. The AlTiN/TiN coating exhibited the largest sensitivity of adhesion to roughness and scratching direction. The coefficient of friction and wear rate increased when AlTiN/TiN roughness exceeded Sa ≈ 100 nm. Full article
(This article belongs to the Special Issue State-of-the-Art PVD Hard Coatings and Their Applications)
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<p>Schematic presentation of the coatings’ layer design.</p> Full article ">Figure 2
<p>Mechanical characteristics of investigated coatings obtained under different indentation loads on polished samples, (<b>a</b>) hardness (H) (error bars represent ± standard deviation), (<b>b</b>) modulus of elasticity (E), and elastic deformation energy to total deformation energy ratio (n<sub>IT</sub>).</p> Full article ">Figure 3
<p>Representative surface topographies of the samples with different surface roughness before and after the coating deposition, shown for the nl-AlTiN/TiN coating.</p> Full article ">Figure 4
<p>Surface roughness of substrates and coated samples before and after the coating deposition. The inclined lines in the diagram indicate the ideal replication of the substrate surface roughness after the coating deposition.</p> Full article ">Figure 5
<p>Representative scratch tracks of polished samples.</p> Full article ">Figure 6
<p>Average values of critical forces of TiAlN, TiAlN/CN<sub>x</sub>, and nl-AlTiN/TiN coatings deposited on substrates with different roughness, tested in two directions relative to machining marks; error bars represent ± standard deviation.</p> Full article ">Figure 7
<p>3D topography images of the wear tracks obtained after 2000 cycles on different coatings with different surface roughness; inserts in the images are the CFM images of the Al<sub>2</sub>O<sub>3</sub> counter-ball from the corresponding tribological test.</p> Full article ">Figure 8
<p>Wear rate (K) and average friction coefficients (COF) of different coatings prepared to different degrees of surface roughness.</p> Full article ">
27 pages, 9947 KiB  
Article
Use of 2D Sulfide and Oxide Compounds as Functional Semiconducting Pigments in Protective Organic Coatings Containing Zinc Dust
by Miroslav Kohl, Karolína Boštíková, Stanislav Slang, Eva Schmidová and Andréa Kalendová
Coatings 2024, 14(8), 1009; https://doi.org/10.3390/coatings14081009 - 8 Aug 2024
Viewed by 335
Abstract
Within this study, the influence of particles of different types, natures, and sizes on the mechanical and corrosion resistance of pigmented systems containing spherical zinc was studied. For this study, prominent representatives from the group of transition metal dichalcogenides (MoS2, WS [...] Read more.
Within this study, the influence of particles of different types, natures, and sizes on the mechanical and corrosion resistance of pigmented systems containing spherical zinc was studied. For this study, prominent representatives from the group of transition metal dichalcogenides (MoS2, WS2), layered transition metal oxides (MoO3, WO3), and other semiconductor materials (ZnS and ZnO) were used. The layered ultra-thin structure of these particles was predisposed to provide enhanced mechanical and anti-corrosion performance. The mechanical properties of the studied coatings were tested using standardized mechanical tests, while the anti-corrosion performance of these coatings was studied using standardized cyclic corrosion tests and the linear polarization electrochemical technique. The results of the experimental techniques bring completely original knowledge about the action of these pigments in paint systems pigmented with zinc. The results of experimental techniques have shown enhancement and an increase in both mechanical and anti-corrosion performance when using these special types of inorganic pigments. In particular, with organic coatings pigmented with MoO3, there was an increase in mechanical resistance mainly due to its morphology and layered structure. In addition, a significant enhancement of the anti-corrosion efficiency was noted for this type of organic coating due to the enhancement of individual types of action mechanisms typical and proven for zinc-pigmented systems. These original findings can be used in the search for possibilities to reduce the zinc content in zinc-pigmented organic coatings. This partial replacement of zinc particles leads not only to a reduction in the zinc content in the system but also to a significant strengthening of the mechanical resistance and an increase in the corrosion efficiency of the system. Full article
(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>The FTIR spectrum of binder, which was used for the preparation of organic coating containing inorganic pigments.</p> Full article ">Figure 2
<p>Scanning electron micrographs of the studied inorganic pigments: (<b>a1</b>) WS<sub>2</sub>, 500 µm; (<b>a2</b>) WS<sub>2</sub>, 5 µm; (<b>b1</b>) WO<sub>3</sub><span class="html-italic">,</span> 500 µm; (<b>b2</b>) WO<sub>3</sub><span class="html-italic">,</span> 5 µm; (<b>c1</b>) ZnS, 500 µm; (<b>c2</b>) ZnS, 5 µm; (<b>d1</b>) ZnO, 500 µm; (<b>d2</b>) ZnO, 5 µm; (<b>e1</b>) MoS<sub>2</sub>, 500 µm; (<b>e2</b>) MoS<sub>2</sub>, 5 µm; (<b>f1</b>) MoO<sub>3</sub> 500 µm; (<b>f2</b>) MoO<sub>3</sub> 5 µm; (<b>g1</b>) ZnS/BaSO<sub>4</sub>, 500 µm; (<b>g2</b>) ZnS/BaSO<sub>4</sub> 5 µm; (<b>h1</b>) Zn 500 µm; (<b>h2</b>) Zn 5 µm.</p> Full article ">Figure 3
<p>Micrographs of transverse fractures of selected organic coatings: (<b>a1</b>) SEM, (<b>a2</b>) Zn-BSE, and (<b>a3</b>) O-BSE of zinc-pigmented organic coating; (<b>b1</b>) SEM, (<b>b2</b>) Zn-BSE, (<b>b3</b>) Mo-BSE and (<b>b4</b>) O-BSE of zinc-pigmented organic coating pigmented with MoO<sub>3</sub> at PVC = 10% together with elemental mapping below.</p> Full article ">Figure 4
<p>Microphotograph of the surface of a zinc-pigmented coating: (<b>a1</b>) SEM, (<b>a2</b>) Zn-BSE, (<b>a3</b>) Mo-BSE and (<b>a4</b>) O-BSE of film containing MoO<sub>3</sub> pigment at PVC = 10% at the cohesive fracture point after the pull-off test; (<b>b1</b>) SEM, (<b>b2</b>) Zn-BSE, (<b>b3</b>) Mo-BSE and (<b>b4</b>) O-BSE of detail film containing MoO<sub>3</sub> together with elemental mapping below.</p> Full article ">Figure 5
<p>SEM-BSE scans of a zinc-pigmented coating film containing MoO<sub>3</sub> pigment at PVC = 10% at the cohesive fracture point after the pull-off test—topography scan (<b>left</b>) and BSE scans with elemental contrast (<b>right</b>).</p> Full article ">Figure 6
<p>Organic coating after 960 h of exposure in an atmosphere containing salt electrolyte: (<b>a</b>) with MoS<sub>2</sub> at PVC = 10%; (<b>b</b>) with MoO<sub>3</sub> at PVC = 10%; (<b>c</b>) with ZnO at PVC = 10%; (<b>d</b>) with Zn at PVC/CPVC = 0.6 and steel panel after removing the organic coating; (<b>e</b>) with MoS<sub>2</sub> at PVC = 10%; (<b>f</b>) with MoO<sub>3</sub> at PVC = 10%; (<b>g</b>) with ZnO at PVC = 10%; and (<b>h</b>) with Zn at PVC/CPVC = 0.6.</p> Full article ">Figure 7
<p>Photographs of test sections of individual organic coatings after 480 h of exposure in an atmosphere containing a salt electrolyte: (<b>a</b>) organic coatings with MoO<sub>3</sub> (at PVC = 10%); (<b>b</b>) organic coatings with MoS<sub>2</sub> (at PVC = 10%); (<b>c</b>) organic coatings with WO<sub>3</sub> (at PVC = 10%); (<b>d</b>) organic coatings with WS<sub>2</sub> (at PVC = 10%); (<b>e</b>) organic coatings with ZnO (at PVC = 10%); (<b>f</b>) organic coatings with ZnS (at PVC = 10%); (<b>g</b>) organic coatings with ZnS/BaSO<sub>4</sub> (at PVC = 10%); (<b>h</b>) zinc-pigmented organic coating (PVC/CPVC = 0.6).</p> Full article ">Figure 8
<p>Results of scanning electron micrographs and energy-dispersive X-ray analysis of the organic coating in areas far from the test cut: (<b>a</b>) organic coatings with WO<sub>3</sub> (at PVC = 10%); (<b>b</b>) organic coatings with MoO<sub>3</sub> (at PVC = 10%); (<b>c</b>) zinc-pigmented organic coating (PVC/CPVC = 0.6).</p> Full article ">Figure 9
<p>Results of scanning electron micrographs of the organic coating containing WO<sub>3</sub> at PVC = 10% in areas far from the test cut.</p> Full article ">Figure 10
<p>Results of scanning electron micrographs and energy-dispersive X-ray analysis of the organic coating in the test cut: (<b>a</b>) organic coatings with WO<sub>3</sub> (at PVC = 10%); (<b>b</b>) organic coatings with MoO<sub>3</sub> (at PVC = 10%); (<b>c</b>) zinc-pigmented organic coating (PVC/CPVC = 0.6).</p> Full article ">Figure 11
<p>Results of powder X-ray diffraction analysis of corrosion products taken from test sections of selected organic coatings: (<b>a</b>) zinc-pigmented organic coating (PVC/CPVC = 0.6); (<b>b</b>) organic coatings with MoO<sub>3</sub> (at PVC = 10%).</p> Full article ">Figure 12
<p>Organic coating after 960 h of exposure in an atmosphere containing SO<sub>2</sub>: (<b>a</b>) with MoS<sub>2</sub> at PVC = 10%; (<b>b</b>) with MoO<sub>3</sub> at PVC = 10%; (<b>c</b>) with ZnO at PVC = 10%; (<b>d</b>) with Zn at PVC/CPVC = 0.6 and steel panel after removing the organic coating; (<b>e</b>) with MoS<sub>2</sub> at PVC = 10%; (<b>f</b>) with MoO<sub>3</sub> at PVC = 10%; (<b>g</b>) with ZnO at PVC = 10%; and (<b>h</b>) with Zn at PVC/CPVC = 0.6.</p> Full article ">Figure 13
<p>Tafel plots of studied organic coatings containing coating with MoO<sub>3</sub> at PVC = 10% (green line), coating with MoO<sub>3</sub> at PVC = 5% (red line), and coating with MoO<sub>3</sub> at PVC = 3% (black line).</p> Full article ">
23 pages, 9776 KiB  
Article
Study on the Attack of Concrete by External Sulfate under Electric Fields
by Huanqin Liu, Nuoqi Shi, Kaizhao Han, Xu Fu and Yuexin Fang
Coatings 2024, 14(8), 1008; https://doi.org/10.3390/coatings14081008 - 8 Aug 2024
Viewed by 386
Abstract
The research on and application of electric fields to promote the rapid infiltration of ions into cement concrete have been widely explored. Still, there are few studies on the migration of sulfate ions using electric fields. In this paper, a new test method [...] Read more.
The research on and application of electric fields to promote the rapid infiltration of ions into cement concrete have been widely explored. Still, there are few studies on the migration of sulfate ions using electric fields. In this paper, a new test method is designed using the principle of electric fields, that is, to accelerate the attack of sulfate into concrete under the action of the electric field, to test the resistance of concrete to sulfate attack. By testing different water–cement ratios, different pulse frequencies, different ages, and different soaking environments, the influence of the electric field on the sulfate resistance of concrete was analyzed. The results show that the compressive strength of concrete in a sulfate attack environment is smaller than that of conventional attack and water immersion environment when the water–cement ratio is 0.3, 0.4, and 0.5 under the action of the electric field and increases with the increase of water in the water–cement ratio. Compared with a 14 day test, the compressive strength of concrete in a sulfate attack environment decreased by 1.9%, 8.6%, and 2.9%, respectively, at 28 days, which was faster than that of conventional attack and water immersion. The compressive strength of the concrete in the sulfate attack environment during the full immersion test and the semi-immersion test is smaller than that of the conventional attack and water immersion, and the semi-immersion test method is more obvious than the full immersion test method. The microscopic morphology of the test group, the water group, and the solution group were compared. From the microscopic morphology comparison, it can be seen that the electric field accelerates the diffusion of sulfate ions into the cement concrete and accelerates the reaction of sulfate ions with the relevant components in the cement concrete. Given the demand for concrete to resist sulfate attack under the action of the electric field, developing new and efficient protective materials is an important research direction. At present, the market lacks protective materials specifically for such an attack environment. This paper provides the theoretical basis and technical support for improving the effectiveness of concrete surface protection technology and engineering practices. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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<p>Grain size distribution curve of coarse aggregate.</p> Full article ">Figure 2
<p>Experimental mold.</p> Full article ">Figure 3
<p>Electrode plates.</p> Full article ">Figure 4
<p>Electric field electro-osmotic device.</p> Full article ">Figure 5
<p>Schematic diagram of sulfate attack resistance test device for concrete.</p> Full article ">Figure 6
<p>Electric field waveform diagram.</p> Full article ">Figure 7
<p>The specimen was soaked in water.</p> Full article ">Figure 8
<p>The specimen was soaked in a sodium sulfate solution.</p> Full article ">Figure 9
<p>Fourteen days in the experimental group specimens.</p> Full article ">Figure 10
<p>Full immersion 14 day compressive strength.</p> Full article ">Figure 11
<p>Attack resistance coefficient of full immersion for 14 days.</p> Full article ">Figure 12
<p>Full immersion 28 day compressive strength.</p> Full article ">Figure 13
<p>Attack resistance coefficient of full immersion for 28 days.</p> Full article ">Figure 14
<p>Semi-immersed 28 day compressive strength.</p> Full article ">Figure 15
<p>Semi-immersed 28 day attack resistance coefficient.</p> Full article ">Figure 16
<p>Compressive strength of different pulse frequencies with water–cement ratio of 0.4.</p> Full article ">Figure 17
<p>Attack resistance coefficient of different pulse frequencies with water–cement ratio of 0.4.</p> Full article ">Figure 18
<p>Compressive strength of full immersion resistance with water–cement ratio of 0.3.</p> Full article ">Figure 19
<p>Attack resistance coefficient of full immersion resistance with water–cement ratio of 0.3.</p> Full article ">Figure 20
<p>Compressive strength of full immersion resistance with water cement ratio of 0.4.</p> Full article ">Figure 21
<p>Attack resistance coefficient of full immersion resistance with water cement ratio of 0.4.</p> Full article ">Figure 22
<p>Compressive strength of full immersion resistance with water–cement ratio of 0.5.</p> Full article ">Figure 23
<p>Attack resistance coefficient of full immersion resistance with water–cement ratio of 0.5.</p> Full article ">Figure 24
<p>Compressive strength of different immersion methods with water–cement ratio of 0.3.</p> Full article ">Figure 25
<p>Attack resistance coefficient of different immersion methods with water–cement ratio of 0.3.</p> Full article ">Figure 26
<p>Compressive strength of different immersion methods with water–cement ratio of 0.4.</p> Full article ">Figure 27
<p>Attack resistance coefficient of different immersion methods with water–cement ratio of 0.4.</p> Full article ">Figure 28
<p>Compressive strength of different immersion methods with water–cement ratio of 0.5.</p> Full article ">Figure 29
<p>Attack resistance coefficient of different immersion methods with water–cement ratio of 0.5.</p> Full article ">Figure 30
<p>Morphology of Shimizu group at 14 days.</p> Full article ">Figure 31
<p>Morphology of solution group at 14 days.</p> Full article ">Figure 32
<p>Morphology of test group at 14 days.</p> Full article ">
23 pages, 41220 KiB  
Article
Surface Coating with Foliar Fertilizers
by Yojana J. P. Carreón, Angel A. Pereyra Zarate, Alondra E. Pérez Sánchez, Orlando Díaz-Hernández and Jorge González-Gutiérrez
Coatings 2024, 14(8), 1007; https://doi.org/10.3390/coatings14081007 - 8 Aug 2024
Viewed by 395
Abstract
Foliar fertilization, an effective agricultural practice, involves the application of nutrients directly through droplets on plant leaves. The mechanisms of mass transport and deposition that arise from the drying of a drop determine the distribution of mass on a surface. Understanding these processes [...] Read more.
Foliar fertilization, an effective agricultural practice, involves the application of nutrients directly through droplets on plant leaves. The mechanisms of mass transport and deposition that arise from the drying of a drop determine the distribution of mass on a surface. Understanding these processes is crucial for optimizing foliar fertilization, ensuring even nutrient distribution, and improving crop yields and quality. This study experimentally investigates deposit formation from the evaporation of fertilizer droplets in various configurations: sessile, vertical, and pendant. We explored the effects of initial droplet volume, vapor pressure, and sorbitol presence on the final deposit morphology. The results reveal distinctive morphological patterns. Sessile drops exhibit two types of deposits—central crystal accumulation with fibrous structures or entirely fibrous structures. In contrast, vertical drops display two zones—fibrous structures at the bottom and small aggregates at the top. On the other hand, pendant drops predominantly feature intertwined crystals with peripheral fibrous structures. We found that high vapor pressures (RH = 60%) inhibit deposit formation within 72 h. Furthermore, the study measures relative evaporation time, showing that sessile droplets exhibit the longest evaporation times, followed by vertical and pendant droplets. Texture analysis, based on GLCM entropy, reveals that deposits generated under low vapor pressure (RH = 20%) show no significant differences in their entropy values, regardless of the droplet configuration and its initial volume. However, at intermediate vapor pressure (RH = 40%), entropy values vary significantly with droplet volume and configuration, being higher in sessile drops and lower in vertical ones. Additionally, we investigated the impact of sorbitol on the coating of sessile fertilizer droplets. We find that configurational entropy decreases exponentially with sorbitol concentration, inducing a morphological transition from fibrous structures to dispersed small aggregates. These findings highlight the complexity of pattern formation in fertilizer deposits and their potential implications for optimizing surface coating processes. Full article
(This article belongs to the Special Issue Recent Advances in Surface Functionalisation)
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<p>Three drying configurations: (<b>a</b>) sessile droplets (on a horizontal surface), (<b>b</b>) vertical droplets (on an inclined surface), and (<b>c</b>) pendant droplets (suspended downward).</p> Full article ">Figure 2
<p>Morphological patterns of dried fertilizer droplets under three different configurations: sessile, vertical, and pendant. Each configuration was observed at two relative humidities: 20% (<b>top row</b>) and 40% (<b>bottom row</b>). For the sessile configuration at 20% HR, two distinct patterns are depicted, with the left image showing elongated crystalline structures and the right image showing a more fibrous pattern. At 40% HR, the sessile droplets exhibit intricate and varied crystalline structures. In the vertical configuration at 20% HR, the droplets show small crystal clusters in the upper region and denser fibrous patterns in the lower region, whereas, at 40% HR, a more dispersed cluster pattern in the upper region and denser crystalline region in the lower region are observed. The pendant configuration at 20% HR shows a combination of large crystals and amorphous structures, while at 40% HR, more elongated crystal patterns and coarse amorphous crystalline structures are present. Scale bars indicate 1 mm.</p> Full article ">Figure 3
<p>Magnified views of the peripheral (<b>a</b>) and central (<b>b</b>) regions of dried fertilizer droplets under sessile, vertical, and pendant configurations at two relative humidity levels: 20% and 40%. The peripheral regions (<b>a</b>) display significant variations in crystalline and fibrous structures, influenced by the drying conditions and humidity levels. In the central regions (<b>b</b>), distinct patterns emerge, reflecting the interplay of evaporation dynamics and solute distribution across different configurations and humidity levels. Scale bars indicate 0.5 mm.</p> Full article ">Figure 4
<p>Pattern formation and drying process of sessile fertilizer droplets at 20% (<b>a</b>) and 40% (<b>b</b>) relative humidity. (<b>I</b>) Sequence of optical images showing the evolution of droplet patterns over time. Initial stages exhibit a smooth appearance (<span class="html-italic">t</span> = 1260–1980 s for 20% RH and <span class="html-italic">t</span> = 2130–2790 s for 40% RH), followed by the onset of crystallization (<span class="html-italic">t</span> = 2040–2100 s for 20% RH and <span class="html-italic">t</span> = 5580–7230 s for 40% RH), and culminating in complex, fibrous structures (<span class="html-italic">t</span> = 11,657 s for 20% RH and <span class="html-italic">t</span> = 45,680 s for 40% RH). (<b>II</b>) Side view images illustrating the lateral drying process, showing changes in droplet profile from a high and symmetrical shape to an extended, thin profile (<span class="html-italic">t</span> = 30–2340 s for 20% RH and <span class="html-italic">t</span> = 60–28,500 s for 40% RH). (<b>III</b>) Normalized height profiles (<math display="inline"><semantics> <mrow> <mi>h</mi> <mo>/</mo> <msub> <mi>h</mi> <mn>0</mn> </msub> <mrow> <mo>)</mo> </mrow> </mrow> </semantics></math> versus normalized radius (<math display="inline"><semantics> <mrow> <mi>r</mi> <mo>/</mo> <msub> <mi>r</mi> <mn>0</mn> </msub> <mrow> <mo>)</mo> </mrow> </mrow> </semantics></math> during the drying process, indicating the progressive flattening and extension of the droplet profile, and reflecting uniform and controlled evaporation dynamics. Scale bars indicate 1 mm.</p> Full article ">Figure 5
<p>Pattern formation and drying process of vertical fertilizer droplets at 20% (<b>a</b>) and 40% (<b>b</b>) relative humidity. (<b>I</b>) Sequence of optical images showing the evolution of droplet patterns over time. Initial stages exhibit a uniform appearance (<span class="html-italic">t</span> = 1620–2040 s for 20% RH and <span class="html-italic">t</span> = 420–3360 s for 40% RH), followed by nucleation and aggregation of solute particles (<span class="html-italic">t</span> = 2580–4500 s for 20% RH and <span class="html-italic">t</span> = 4320–7530 s for 40% RH), and culminating in complex, fibrous structures (<span class="html-italic">t</span> = 6180–17,340 s for 20% RH and <span class="html-italic">t</span> = 8370–63,255 s for 40% RH). (<b>II</b>) Side view images illustrating the lateral drying process, showing changes in droplet profile from a high and asymmetric shape to an extended, thin profile (<span class="html-italic">t</span> = 210–2520 s for 20% RH and <span class="html-italic">t</span> = 90–5760 s for 40% RH). (<b>III</b>) Normalized height profiles (<math display="inline"><semantics> <mrow> <mi>h</mi> <mo>/</mo> <msub> <mi>h</mi> <mn>0</mn> </msub> <mrow> <mo>)</mo> </mrow> </mrow> </semantics></math> versus normalized radius (<math display="inline"><semantics> <mrow> <mi>r</mi> <mo>/</mo> <msub> <mi>r</mi> <mn>0</mn> </msub> <mrow> <mo>)</mo> </mrow> </mrow> </semantics></math> during the drying process, indicating the progressive flattening and extension of the droplet profile, reflecting uniform and controlled evaporation dynamics. Scale bars indicate 1 mm. The red arrow indicates the direction of the gravitational force.</p> Full article ">Figure 6
<p>Pattern formation and drying process of pendant fertilizer droplets at 20% (<b>a</b>) and 40% (<b>b</b>) relative humidity. (<b>I</b>) Sequence of optical images showing the evolution of droplet patterns over time. Early stages exhibit a nearly circular shape and homogeneous solute distribution (<span class="html-italic">t</span> = 1470–2040 s for 20% RH and <span class="html-italic">t</span> = 1800–2940 s for 40% RH), followed by nucleation and aggregate formation (<span class="html-italic">t</span> = 2160–4500 s for 20% RH and <span class="html-italic">t</span> = 5400–7320 s for 40% RH), and culminating in complex crystalline structures (<span class="html-italic">t</span> = 7140–8754 s for 20% RH and <span class="html-italic">t</span> = 9480–19,037 s for 40% RH). (<b>II</b>) Side view images illustrating the lateral drying process, showing changes in droplet profile from hemispherical to extended thin deposits (<span class="html-italic">t</span> = 420–2250 s for 20% RH and <span class="html-italic">t</span> = 90–20,250 s for 40% RH). (<b>III</b>) Normalized height profiles (<math display="inline"><semantics> <mrow> <mi>h</mi> <mo>/</mo> <msub> <mi>h</mi> <mn>0</mn> </msub> <mrow> <mo>)</mo> </mrow> </mrow> </semantics></math> versus normalized radius (<math display="inline"><semantics> <mrow> <mi>r</mi> <mo>/</mo> <msub> <mi>r</mi> <mn>0</mn> </msub> </mrow> </semantics></math>) during the drying process, indicating progressive flattening and extension of the droplet profile, reflecting uniform and controlled evaporation dynamics. Scale bars indicate 1 mm.</p> Full article ">Figure 7
<p>Relative evaporation times of fertilizer droplets in sessile, vertical, and pendant configurations. Sessile droplets show the longest evaporation times due to the extensive contact area with the substrate, while vertical droplets have intermediate evaporation times influenced by gravity. Pendant droplets exhibit the shortest evaporation times due to the downward gravitational pull and reduced contact area. Error bars represent the variability in measurements.</p> Full article ">Figure 8
<p>Effect of initial droplet volume on drying patterns of fertilizer droplets at 20% relative humidity (RH) across three configurations: sessile, vertical, and pendant. Droplets with volumes of 3 μL, 6 μL, 9 μL, 12 μL, and 15 μL exhibit consistent morphological characteristics within each configuration. In the sessile configuration, patterns include both elongated crystalline structures and fibrous regions. The vertical configuration shows a gradient of crystal density influenced by gravity, with the shape factor <math display="inline"><semantics> <mi>γ</mi> </semantics></math> increasing from 1 (3 μL) to 1.2 (15 μL). The pendant configuration reveals uniform fibrous structures across different volumes, indicating robust drying dynamics. Scale bars indicate 1 mm.</p> Full article ">Figure 9
<p>Fertilizer deposits generated in sessile, vertical, and pendant configurations at an intermediate vapor pressure (RH = 40%). Sessile droplets exhibit regions of elongated crystals surrounded by amorphous aggregates, with the crystalline region’s size increasing with initial drop volume. Vertical droplets display a separation between high-mass-concentration regions with intricate hydrated crystalline structures at the bottom and low-concentration regions with small dispersed aggregates at the top. Pendant droplets predominantly form fibrous structures with aggregates that may or may not be hydrated, regardless of the initial droplet volume. Scale bars indicate 1 mm.</p> Full article ">Figure 10
<p>Entropy values of dried fertilizer droplets over a range of initial drop volumes (3 μL to 15 μL) in three configurations (sessile, vertical, and pendant) at 20% relative humidity (RH). Regardless of the initial droplet volume and configuration, the entropy values remain relatively constant, suggesting consistent heterogeneity in the mass distribution of the deposits. The error bars are the standard deviation with n = 20.</p> Full article ">Figure 11
<p>Entropy values of dried fertilizer droplets over a range of initial drop volumes (3 μL to 15 μL) in three configurations (sessile, vertical, and pendant) at 40% relative humidity (RH). The entropy values indicate significant differences in the heterogeneity of the deposits for low initial droplet volumes (3–6 μL) across different configurations. For higher initial droplet volumes (9–15 μL), sessile and pendant droplets show similar entropy values, while vertical droplets exhibit significantly lower entropy values. The error bars are the standard deviation with n = 20.</p> Full article ">Figure 12
<p>Deposit patterns (<b>a</b>) and corresponding three-dimensional representations (<b>b</b>) of sessile fertilizer droplets with varying concentrations of sorbitol (0.01%, 0.1%, 10%, 20%, and 40%) with V = 3 μL, RH = 20%, and T = 25 °C. At low concentrations (0.01–0.1%), sorbitol inhibits aggregate formation within the central region, allowing fibrous structures to dominate. At higher concentrations (10–40%), small dispersed aggregates emerge, with their size decreasing as sorbitol concentration increases. The color scale bar represents height in micrometers (μm).</p> Full article ">Figure 13
<p>Entropy values of fertilizer deposits with varying sorbitol concentrations, quantified using GLCM entropy-based texture analysis. The entropy decreases exponentially with increasing sorbitol concentration, with the maximum entropy observed at <math display="inline"><semantics> <msub> <mi>ϕ</mi> <mi>s</mi> </msub> </semantics></math> = 0.01% and the minimum at <math display="inline"><semantics> <msub> <mi>ϕ</mi> <mi>s</mi> </msub> </semantics></math> = 40%. This inverse relationship indicates that higher sorbitol concentrations lead to more uniform and less heterogeneous mass distributions in the fertilizer deposits. The error bars are the standard deviation with n = 20.</p> Full article ">Figure 14
<p>Deposits of dried fertilizer droplets on Coffea Arabica leaves under three different configurations: sessile, vertical, and pendant. Observations for each configuration were carried out under two different relative humidity conditions: 20% (displayed in the top row) and 40% (shown in the bottom row). Scale bars indicate 1 mm.</p> Full article ">
10 pages, 3986 KiB  
Article
Structure, Mechanical Properties and Water Vapor Corrosion Resistance of AlCrNbSiTiN High-Entropy Nitride Coatings Deposited by RF Magnetron Sputtering
by Xuanzheng Wang, Jie Liu, Yingfan Liu, Wentao Li, Yanming Chen and Bing Yang
Coatings 2024, 14(8), 1006; https://doi.org/10.3390/coatings14081006 - 8 Aug 2024
Viewed by 318
Abstract
High-entropy nitride AlCrNbSiTiN coatings were deposited by RF magnetron sputtering at different bias voltages. The structure, mechanical properties and water vapor corrosion resistance of the coatings were systematically studied. The coatings exhibit a face-centered cubic (FCC) structure, while achieving a hardness up to [...] Read more.
High-entropy nitride AlCrNbSiTiN coatings were deposited by RF magnetron sputtering at different bias voltages. The structure, mechanical properties and water vapor corrosion resistance of the coatings were systematically studied. The coatings exhibit a face-centered cubic (FCC) structure, while achieving a hardness up to 35.8 GPa. The main wear mechanisms of the coatings are adhesive wear and oxidation wear. After 200 h of water vapor corrosion, the content of O in the coatings is 4.30 at.%. Full article
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<p>The surface, AFM and three-dimensional morphology of the AlCrNbSiTiN coatings with different bias voltages.</p> Full article ">Figure 2
<p>The cross-section morphology of the AlCrNbSiTiN coatings with different bias voltages.</p> Full article ">Figure 3
<p>The chemical composition as a function of bias voltage for AlCrNbSiTiN coatings.</p> Full article ">Figure 4
<p>XRD patterns of AlCrNbSiTiN coatings deposited at different bias voltages.</p> Full article ">Figure 5
<p>Variation of the hardness and elastic modulus (<b>a</b>) and the H/E and H<sup>3</sup>/E<sup>2</sup> values (<b>b</b>) for the AlCrNbSiTiN coatings as a function of bias voltage.</p> Full article ">Figure 6
<p>The wear scar morphology and EDS results of the AlCrNbSiTiN coatings.</p> Full article ">Figure 7
<p>Surface morphology of AlCrNbSiTiN coatings after water vapor corrosion.</p> Full article ">Figure 8
<p>Variation of elemental proportions after water vapor corrosion of AlCrNbSiTiN coatings. (<b>a</b>) 50 V, (<b>b</b>) 100 V, (<b>c</b>) 150 V, (<b>d</b>) 200 V.</p> Full article ">
9 pages, 1993 KiB  
Article
Ultra-Structural Surface Characteristics of Dental Silane Monolayers
by Xiaotian Liu, Winnie Wing-Yee Shum and James Kit-Hon Tsoi
Coatings 2024, 14(8), 1005; https://doi.org/10.3390/coatings14081005 - 8 Aug 2024
Viewed by 275
Abstract
This study aims to study the formation quality of the film of dental silanes. Two dental silanes, 3-methacryloxyproyltrimethoxysilane (MPS) and 3-acryloyloxypropyltrimethoxysilane (ACPS), were deposited on the silica glass-equivalent model surface (i.e., n-type silicon(100) wafer) by varying the deposition time (5 h and 22 [...] Read more.
This study aims to study the formation quality of the film of dental silanes. Two dental silanes, 3-methacryloxyproyltrimethoxysilane (MPS) and 3-acryloyloxypropyltrimethoxysilane (ACPS), were deposited on the silica glass-equivalent model surface (i.e., n-type silicon(100) wafer) by varying the deposition time (5 h and 22 h). The film quality was then evaluated by ellipsometry, surface contact angle (CA) and surface free energy (SFE), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) in survey and high-resolution modes on Si2p, O1s and C1s. Ellipsometry confirmed that both silanes at the two different deposition times would produce 0.85–1.22 nm thick self-assembled monolayer on the silicon wafer surface. While the water CA of silanized surfaces (60.7–71.5°) was larger than the surface without silane (29.6°), the SFE values of all silanes (40.0–44.5 mN/m) were slightly less than that of the wafer surface (46.3 mN/m). AFM revealed that the MPS with 22 h silanization yielded a significantly higher roughness (0.597 μm) than other groups (0.254–0.297 μm). High-resolution XPS on C1s identified a prominent peak at 288.5 eV, which corresponds to methacrylate O-C*=O, i.e., the silane monolayer is extended fully in the vertical direction, while others are in defect states. This study proves that different dental silanes under various dipping times yield different chemical qualities of the film even if they look thin physically. Full article
(This article belongs to the Special Issue Surface Properties of Dental Materials and Instruments, 2nd Edition)
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<p>Structures of (<b>a</b>) 3-methacryloxypropyltrimethoxysilane (MPS) and (<b>b</b>) 3-acryloyloxypropyltrimethoxysilane (ACPS).</p> Full article ">Figure 2
<p>Simulated results of (<b>left</b>) MPS and (<b>right</b>) ACPS after energy minimization (ChemOffice 2007).</p> Full article ">Figure 3
<p>D Topographical AFM images of MPS-treated (<b>a</b>,<b>b</b>) and ACPS-treated (<b>c</b>,<b>d</b>) silica surfaces with dipping times of (<b>a</b>,<b>c</b>) 5 h and (<b>b</b>,<b>d</b>) 22 h. Image size is 1 μm × 1 μm; * denotes the significant difference (<span class="html-italic">p</span> &lt; 0.05) in average roughness (Sa).</p> Full article ">Figure 4
<p>XPS survey (<b>a</b>) and high-resolution scan spectra of (<b>b</b>) Si2p, (<b>c</b>) O1s and (<b>d</b>) C1s of all groups. For the deconvolution results of high-resolution XPS, please check <a href="#app1-coatings-14-01005" class="html-app">Supplementary Materials Figure S1</a>.</p> Full article ">Figure 5
<p>Illustration of the M22 silane monolayer (<b>left</b>) and other groups (<b>right</b>).</p> Full article ">
15 pages, 4222 KiB  
Article
New Sustainable Intumescent Coating Based on Polyphenols Obtained from Wood Industry Waste
by Luis F. Montoya, Julio Flores, Jesús Ramírez, David Rojas, Ángelo Oñate, Katherina Fernández, Andrés F. Jaramillo, Cristian Miranda and Manuel F. Melendrez
Coatings 2024, 14(8), 1004; https://doi.org/10.3390/coatings14081004 - 8 Aug 2024
Viewed by 267
Abstract
The global proliferation of Pinus radiata, known for its rapid growth and wood density, has led to an environmental challenge—significant waste production, especially bark, without a clear valorization route. This waste poses ecological concerns, and despite the crucial role of forest resources [...] Read more.
The global proliferation of Pinus radiata, known for its rapid growth and wood density, has led to an environmental challenge—significant waste production, especially bark, without a clear valorization route. This waste poses ecological concerns, and despite the crucial role of forest resources in structural applications, their limited fire resistance requires the use of coatings. However, traditional coatings lack an eco-friendly footprint. Addressing this challenge, this study aims to develop an intumescent coating with tannins extracted from waste bark, offering a sustainable alternative. This not only repurposes waste on a global scale but also aligns with the imperative for environmentally friendly materials, contributing to sustainable practices in the construction and wood treatment industry. This study achieved an eco-friendly FRR15 (fire resistance ratio 15) fire resistance classification with a 15% equivalence of low-molecular-weight tannins, presenting a sustainable alternative to commercial products. Characterization showed low-molecular-weight tannins comparable to conventional charring agents, with high hydroxyl content and oil absorption, while high-molecular-weight tannins exhibited lower viability. A reference coating achieved FRR30 fire resistance, aligning with commercial strength. The mechanical properties of tannin-based coatings matched commercial standards, with increased abrasion resistance and adhesion and decreased flexibility. Intumescent coatings with higher tannin content significantly reduced wood substrate charring and mass loss in flame response assessments. Full article
(This article belongs to the Section Functional Polymer Coatings and Films)
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<p>Adherence test on substrate under different conditions: (<b>a</b>) reference coating; (<b>b</b>) 5% addit.; (<b>c</b>) 10% addit.; (<b>d</b>) 15% eq; (<b>e</b>) 35% eq. (<b>f</b>) 65% eq. (<b>g</b>) 90% eq; (<b>h</b>) Firewall 200; (<b>i</b>) Ak 7000.</p> Full article ">Figure 2
<p>Flexibility test on substrate under different conditions: (<b>a</b>) reference coating; (<b>b</b>) 5% addit.; (<b>c</b>) 10% addit.; (<b>d</b>) 15% eq; (<b>e</b>) 35% eq. (<b>f</b>) 65% eq. (<b>g</b>) 90% eq; (<b>h</b>) Firewall 200; (<b>i</b>) Ak 7000.</p> Full article ">Figure 3
<p>Abrasion test on substrate under different conditions: (<b>a</b>) reference coating; (<b>b</b>) 5% added.; (<b>c</b>) 10% addit.; (<b>d</b>) 15% eq; (<b>e</b>) 35% eq. (<b>f</b>) 65% eq. (<b>g</b>) 90% eq; (<b>h</b>) Firewall 200; (<b>i</b>) Ak 7000.</p> Full article ">Figure 4
<p>Mechanical test results on the analyzed coatings: (<b>a</b>) ball impact test; (<b>b</b>) abrasion test; (<b>c</b>) flexural test.</p> Full article ">Figure 5
<p>Temperature–time curve of substrate with intumescent coating subjected to 700 °C in a muffle furnace.</p> Full article ">Figure 6
<p>Substrate mass loss after exposure to fire.</p> Full article ">Figure 7
<p>Intumescence height in muffle furnace test on substrate under different conditions: (<b>a</b>) without coating; (<b>b</b>) reference coating; (<b>c</b>) Firewall 200; (<b>d</b>) Ak 7000; (<b>e</b>) 5% additive; (<b>f</b>) 10% additive; (<b>g</b>) 15% eq; (<b>h</b>) 35% eq.; (<b>i</b>) 65% eq.; (<b>j</b>) 90% eq.</p> Full article ">Figure 8
<p>Intumescence height in inclined tunnel test on substrate under different conditions: (<b>a</b>) without coating; (<b>b</b>) reference coating; (<b>c</b>) Firewall 200; (<b>d</b>) Ak 7000; (<b>e</b>) 5% addit.; (<b>f</b>) 10% addit.; (<b>g</b>) 15% eq; (<b>h</b>) 35% eq.; (<b>i</b>) 65% eq.; (<b>j</b>) 90% eq.</p> Full article ">
20 pages, 5733 KiB  
Article
Optimization of Preparation Process for Chitosan-Coated Pomelo Peel Flavonoid Microcapsules and Its Effect on Waterborne Paint Film Properties
by Jinzhe Deng, Tingting Ding and Xiaoxing Yan
Coatings 2024, 14(8), 1003; https://doi.org/10.3390/coatings14081003 - 8 Aug 2024
Viewed by 335
Abstract
In order to prepare chitosan-coated pomelo peel flavonoid microcapsules with antibacterial properties, chitosan was used as the wall material for the purpose of coating the core material, pomelo peel flavonoids. The pH of the microcapsule crosslinking reaction was 7.5, the mass ratio of [...] Read more.
In order to prepare chitosan-coated pomelo peel flavonoid microcapsules with antibacterial properties, chitosan was used as the wall material for the purpose of coating the core material, pomelo peel flavonoids. The pH of the microcapsule crosslinking reaction was 7.5, the mass ratio of the microcapsule core material to the wall material was 1:1, and the concentration of the emulsifier was 1%. The microcapsules obtained under these preparation conditions exhibited superior performance, morphology, and dispersion. Additionally, the yield and coating rates were recorded at 22% and 50%, respectively. To prepare the paint film, the microcapsules were added into the coatings at varying concentrations of 0%, 3.0%, 6.0%, 9.0%, 12.0%, and 15.0%. The antibacterial efficacy of the paint film for both bacteria was progressively enhanced with the incorporation of microcapsules. The antibacterial efficacy against Staphylococcus aureus was observed to be higher than that against Escherichia coli. As the content of microcapsules increased, the color difference in the paint film increased, the gloss loss rate increased, and the light transmission rate reduced. The tensile property and elongation at break reduced, and the roughness increased. At a microcapsule content of 6.0%, the paint film exhibited superior overall performance, with an antibacterial efficacy against Escherichia coli and Staphylococcus aureus of 46.3% and 56.7%, respectively. The color difference was 38.58. The gloss loss rate was 41.0%, the light transmission rate was 90.4%, and the paint film exhibited a large elastic region, with an elongation at break of 21.5% and a roughness of 1.46 μm. Full article
(This article belongs to the Special Issue Polymer Thin Films: From Fundamentals to Applications (Second Edition))
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<p>Macroscopic morphology: (<b>A</b>) pomelo peel flavonoids for core material, (<b>B</b>) chitosan for wall material, and (<b>C</b>) microcapsules (sample 7).</p> Full article ">Figure 2
<p>OM images of the microcapsules: (<b>A</b>–<b>D</b>) samples 1–4.</p> Full article ">Figure 3
<p>SEM images of one-factor microcapsules: (<b>A</b>–<b>E</b>) samples 5–9.</p> Full article ">Figure 4
<p>Particle size distribution: (<b>A</b>–<b>D</b>) sample 6–9.</p> Full article ">Figure 5
<p>FTIR images of chitosan, pomelo peel flavonoids, and microcapsule sample 7.</p> Full article ">Figure 6
<p>Macroscopic morphology of the paint films with different contents of microcapsules: (<b>A</b>) without microcapsules, (<b>B</b>) with 3.0% microcapsules, (<b>C</b>) with 6.0% microcapsules, (<b>D</b>) with 9.0% microcapsules, (<b>E</b>) with 12.0% microcapsules, and (<b>F</b>) with 15.0% microcapsules.</p> Full article ">Figure 7
<p>SEM images of paint films with different microcapsule contents: (<b>A</b>) with 3.0% microcapsules, (<b>B</b>) with 6.0% microcapsules, (<b>C</b>) with 9.0% microcapsules, and (<b>D</b>) with 12.0% microcapsules.</p> Full article ">Figure 8
<p>FTIR image of the paint films with and without microcapsules.</p> Full article ">Figure 9
<p>The antibacterial rate of paint films with different microcapsule contents.</p> Full article ">Figure 10
<p>Visible light transmittance.</p> Full article ">Figure 11
<p>The tensile properties.</p> Full article ">
10 pages, 4386 KiB  
Article
Preparation of Dense TiAl Intermetallics by Cold Spraying the Precursor–Hot Isostatic Pressing
by Jiayan Ma, Xin Chu, Yingchun Xie, Jizhan Li, Min Liu and Jiwu Huang
Coatings 2024, 14(8), 999; https://doi.org/10.3390/coatings14080999 - 7 Aug 2024
Viewed by 301
Abstract
In this study, based on the element powder metallurgy method, a new hybrid method is proposed, which firstly prepares TiAl-based deposit precursors by the cold spraying of mixed Ti and Al powders and then combines this with hot isostatic pressing to achieve the [...] Read more.
In this study, based on the element powder metallurgy method, a new hybrid method is proposed, which firstly prepares TiAl-based deposit precursors by the cold spraying of mixed Ti and Al powders and then combines this with hot isostatic pressing to achieve the preparation of TiAl-based alloys. This paper explores the effects of deposition parameters on deposition efficiency and coating composition and investigates the evolution of the microstructure and properties of TiAl-based alloys by different hot isostatic pressing parameters. The results show that the prepared TiAl deposits are dense and free of microstructural defects; a high deposition efficiency (75%) and small deviation of coating composition (3 at %) are obtained under the spraying parameters of 5 MPa, 500 °C. The TiAl-based alloy with a dense microstructure can be prepared by controlling the parameters such as temperature, pressure, and heating rate of subsequent hot isostatic pressing. Full article
(This article belongs to the Special Issue Advanced Cold Spraying Technology II)
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<p>SEM surface morphology of the powder materials: (<b>a</b>) Al; (<b>b</b>) Ti.</p> Full article ">Figure 2
<p>SEM-BSE diagram of cold sprayed TiAl coatings prepared at different gas temperatures: 400 °C: (<b>a</b>) Ti-43Al, (<b>b</b>) Ti-48Al, (<b>c</b>) Ti-53Al; 450 °C: (<b>d</b>) Ti-43Al, (<b>e</b>) Ti-48Al, (<b>f</b>) Ti-53Al; 500 °C: (<b>g</b>) Ti-43Al, (<b>h</b>) Ti-48Al, (<b>i</b>) Ti-53Al.</p> Full article ">Figure 3
<p>EDS energy spectrum of Ti-48Al coating prepared at 500 °C: (<b>a</b>) BSE diagram; (<b>b</b>) Ti Kα1; (<b>c</b>) Al Kα1.</p> Full article ">Figure 4
<p>Deposition efficiency of mixed powder at different gas temperatures.</p> Full article ">Figure 5
<p>The comparison of Al content between the original powder and the mixed deposit at different gas temperatures.</p> Full article ">Figure 6
<p>Microstructure of Ti-48Al preform before and after hot isostatic pressing: (<b>a</b>) process 1; (<b>b</b>) process 2.</p> Full article ">Figure 7
<p>XRD patterns of Ti-48Al preform before and after hot isostatic pressing: (a) as-sprayed; (b) process 1; (c) process 2.</p> Full article ">Figure 8
<p>Macro-morphology of Ti-48Al preform before and after hot isostatic pressing: process 1: (<b>a</b>) before HIP, (<b>b</b>) after HIP; process 2: (<b>c</b>) before HIP, (<b>d</b>) after HIP.</p> Full article ">Figure 8 Cont.
<p>Macro-morphology of Ti-48Al preform before and after hot isostatic pressing: process 1: (<b>a</b>) before HIP, (<b>b</b>) after HIP; process 2: (<b>c</b>) before HIP, (<b>d</b>) after HIP.</p> Full article ">
16 pages, 4859 KiB  
Article
Organic Semiconductor Devices Fabricated with Recycled Tetra Pak®-Based Electrodes and para-Quinone Methides
by María Elena Sánchez Vergara, Eva Alejandra Santillán Esquivel, Ricardo Ballinas-Indilí, Octavio Lozada-Flores, René Miranda-Ruvalcaba and Cecilio Álvarez-Toledano
Coatings 2024, 14(8), 998; https://doi.org/10.3390/coatings14080998 - 7 Aug 2024
Viewed by 316
Abstract
This work presents the synthesis of para-quinone methides (p-QMs), which were deposited as films using the high vacuum sublimation technique after being chemically characterized. The p-QMs films were characterized morphologically and structurally using scanning electron microscopy, atomic force microscopy, [...] Read more.
This work presents the synthesis of para-quinone methides (p-QMs), which were deposited as films using the high vacuum sublimation technique after being chemically characterized. The p-QMs films were characterized morphologically and structurally using scanning electron microscopy, atomic force microscopy, and X-ray diffraction. In addition, their optical behavior was studied by means of ultraviolet–visible spectroscopy, and the optical gaps obtained were in the range of 2.21–2.71 eV for indirect transitions, indicating the semiconductor behavior of the p-QMs. The above was verified through the manufacture and evaluation of the electrical behavior of rigid semiconductor devices, in which fluorine-doped tin oxide-coated glass slides (FTO) were used as an anode and substrate. Finally, as an original, ecological, and low-cost application, the FTO was replaced by substrates and anodes made from recycled Tetra Pak®, generating flexible semiconductor devices. Although the electrical current transported depends on the type of p-QMs, the substituent in its structure, and the morphology, the kinds of substrate and anode also influence the type of electrical behavior of the device. This current–voltage study demonstrates that p-QM2 with 4-Cl-Ph as a radical, p-QM3 with 4-Et2N-Ph as a radical, and p-QM6 with 5-(1,3-benzodioxol) as a radical can be used in optoelectronics as semiconductor films. Full article
(This article belongs to the Special Issue Advanced Thin Films Technologies for Optics, Electronics, and Sensing)
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<p><span class="html-italic">p</span>-QMs and their resonance structures.</p> Full article ">Figure 2
<p>Structure of <span class="html-italic">p</span>-QM compounds.</p> Full article ">Figure 3
<p>IR spectra for a thin film of the <span class="html-italic">p</span>-QM compounds.</p> Full article ">Figure 4
<p>Diffractograms of the <span class="html-italic">p</span>-QM films.</p> Full article ">Figure 5
<p>SEM images of the target <span class="html-italic">p</span>-QM films on glass substrate at 1000×.</p> Full article ">Figure 6
<p>SEM images of <span class="html-italic">p</span>-QM films on TP substrate at 1000×.</p> Full article ">Figure 7
<p>Three-dimensional AFM images of <span class="html-italic">p</span>-QM films at 10 × 10 μm.</p> Full article ">Figure 8
<p>(<b>a</b>) Absorbance and (<b>b</b>) % transmittance spectra of the <span class="html-italic">p</span>-QM films.</p> Full article ">Figure 9
<p>The photon energy dependence of α<sup>1/2</sup> for <span class="html-italic">p</span>-QM films.</p> Full article ">Figure 10
<p>Scheme of semiconductor devices on (<b>a</b>) FTO and (<b>b</b>) TP.</p> Full article ">Figure 11
<p>I–V curves for glass/FTO/<span class="html-italic">p</span>-QM/Ag devices.</p> Full article ">Figure 12
<p>I–V curves for TP/<span class="html-italic">p</span>-QM/Ag devices.</p> Full article ">Scheme 1
<p><span class="html-italic">p</span>-QM general reaction <b>1a</b>–<b>e</b>.</p> Full article ">
15 pages, 6197 KiB  
Article
Study on the Performance and Mechanism of Morpholine Salt Volatile Corrosion Inhibitors on Carbon Steel
by Xiong Zhao, Junying Zhang, Lu Ma, Wubin Wang and Mingxing Zhang
Coatings 2024, 14(8), 997; https://doi.org/10.3390/coatings14080997 - 7 Aug 2024
Viewed by 373
Abstract
A series of morpholine salt volatile corrosion inhibitors (VCIs) were synthesized via solid-phase chemical reactions. The corrosion inhibition performance was assessed using evaporation weight loss, VCI capability, and corrosion weight loss tests. The corrosion inhibition mechanisms of the morpholine salt VCIs for carbon [...] Read more.
A series of morpholine salt volatile corrosion inhibitors (VCIs) were synthesized via solid-phase chemical reactions. The corrosion inhibition performance was assessed using evaporation weight loss, VCI capability, and corrosion weight loss tests. The corrosion inhibition mechanisms of the morpholine salt VCIs for carbon steel in atmospheric conditions were explored through electrochemical testing under thin film electrolytes, X-ray photoelectron spectroscopy (XPS), and computational simulations. Morpholine carbonate exhibited higher volatility. Corrosion weight loss tests showed an >85% reduction for steel treated with morpholine benzoate or morpholine carbonate. The inhibitors’ inhibition mechanism, elucidated through X-ray photoelectron spectroscopy (XPS) and computational simulations, revealed that morpholine carbonate and benzoate form protective layers via physical and chemical adsorption on the steel surface, coordinating with iron atoms through nitrogen and oxygen atoms. Quantum chemical calculations demonstrated that morpholine carbonate had stronger adsorption energy and electron transfer capabilities, indicating superior corrosion inhibition performance over morpholine benzoate. Full article
(This article belongs to the Special Issue Investigation on Structure and Corrosion Resistance of Steels/Alloys)
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<p>Diagram of experimental device for VCIs.</p> Full article ">Figure 2
<p>Diagram of corrosion weight loss experiment device.</p> Full article ">Figure 3
<p>Diagram of electrochemical test experimental device.</p> Full article ">Figure 4
<p>Macroscopic pictures of 20# steel surface after gas phase corrosion inhibition test (<b>a</b>) before corrosion test, (<b>b</b>) blank, or with (<b>c</b>) morpholine formate, (<b>d</b>) morpholine acetate, (<b>e</b>) morpholine propionate, (<b>f</b>) morpholine benzoate, or (<b>g</b>) morpholine carbonate applied.</p> Full article ">Figure 5
<p>Corrosion rate and inhibition efficiency of several morpholine salt volatile corrosion inhibitors in 3.5% NaCl solution.</p> Full article ">Figure 6
<p>Corrosion morphology of 20# steel added with 10 g/L of several morpholine salt volatile corrosion inhibitors in 3.5% NaCl solution (<b>a</b>) blank, or with (<b>b</b>) morpholine formate, (<b>c</b>) morpholine acetate, (<b>d</b>) morpholine propionate, (<b>e</b>) morpholine benzoate, or (<b>f</b>) morpholine carbonate applied.</p> Full article ">Figure 7
<p>Impedance spectrum of morpholine salt volatile corrosion inhibitors in 3.5% NaCl thin liquid film (<b>a</b>) Nyquist; (<b>b</b>) Phase angle; (<b>c</b>) Impedance modulus.</p> Full article ">Figure 8
<p>Fitting circuit diagram of adding volatile corrosion inhibitor impedance spectrum.</p> Full article ">Figure 9
<p>XPS full spectrum of 20# steel samples before and after covering with (<b>a</b>) morpholine benzoate and (<b>b</b>) morpholine carbonate inhibitors.</p> Full article ">Figure 10
<p>XPS Spectra of 20# steel samples after adding morpholine benzoate VCI at (<b>a</b>) N1s peak; (<b>b</b>) O1s peak; (<b>c</b>) C1s peak; and (<b>d</b>) Fe2p peak; and morpholine carbonate VCI at (<b>e</b>) N1s peak; (<b>f</b>) O1s peak; (<b>g</b>) C1s peak; and (<b>h</b>) Fe2p peak.</p> Full article ">Figure 11
<p>Optimization of molecular geometry of two morpholine salt volatile corrosion inhibitors, (<b>a</b>) morpholine benzoate and (<b>b</b>) morpholine carbonate.</p> Full article ">Figure 12
<p>Adsorption model of two morpholine salt volatile corrosion inhibitors, (<b>a</b>) morpholine benzoate and (<b>b</b>) morpholine carbonate, on Fe substrate surface. White ball: H; Grey ball: C; Red ball: O; Blue ball: N; Purple ball: Fe.</p> Full article ">Figure 13
<p>Inhibition mechanism diagram of morpholine benzoate volatile corrosion inhibitor and morpholine carbonate volatile corrosion inhibitor.</p> Full article ">
10 pages, 5124 KiB  
Article
Thick Columnar-Structured Thermal Barrier Coatings Using the Suspension Plasma Spray Process
by Dianying Chen and Christopher Dambra
Coatings 2024, 14(8), 996; https://doi.org/10.3390/coatings14080996 - 7 Aug 2024
Viewed by 376
Abstract
Higher operating temperatures for gas turbine engines require highly durable thermal barrier coatings (TBCs) with improved insulation properties. A suspension plasma spray process (SPS) had been developed for the deposition of columnar-structured TBCs. SPS columnar TBCs are normally achieved at a short standoff [...] Read more.
Higher operating temperatures for gas turbine engines require highly durable thermal barrier coatings (TBCs) with improved insulation properties. A suspension plasma spray process (SPS) had been developed for the deposition of columnar-structured TBCs. SPS columnar TBCs are normally achieved at a short standoff distance (50.0 mm–75.0 mm), which is not practical when coating complex-shaped engine hardware since the plasma torch may collide with the components being sprayed. Therefore, it is critical to develop SPS columnar TBCs at longer standoff distances. In this work, a commercially available pressure-based suspension delivery system was used to deliver the suspension to the plasma jet, and a high-enthalpy TriplexPro-210 plasma torch was used for the SPS coating deposition. Suspension injection pressure was optimized to maximize the number of droplets injected into the hot plasma core and achieving the best particle-melting states and deposition efficiency. The highest deposition efficiency of 51% was achieved at 0.34 MPa injection pressure with a suspension flow rate of 31.0 g/min. With the optimized process parameters, 1000 μm thick columnar-structured SPS 8 wt% Y2O3-stabilized ZrO2 (8YSZ) TBCs were successfully developed at a standoff distance of 100.0 mm. The SPS TBCs have a columnar width between 100 μm and 300 μm with a porosity of ~22%. Furnace cycling tests at 1125 °C showed the SPS columnar TBCs had an average life of 1012 cycles, which is ~2.5 times that of reference air-plasma-sprayed dense vertically cracked TBCs with the same coating thickness. The superior durability of the SPS columnar TBCs can be attributed to the high-strain-tolerant microstructure. SEM cross-section characterization indicated the failure of the SPS TBCs occurred at the ceramic top coat and thermally grown oxide (TGO) interface. Full article
(This article belongs to the Special Issue Functional Coatings and Surface Science for Precision Engineering)
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<p>Photos of LSF-400 suspension feeding system (<b>a</b>,<b>b</b>) and TriplexPro-210 suspension plasma spray (<b>c</b>).</p> Full article ">Figure 2
<p>Effect of injection pressure on the coating deposition efficiency.</p> Full article ">Figure 3
<p>Typical microstructures of deposits from the fixed-scan experiment: (<b>a</b>) powdery deposits at the band edge; (<b>b</b>) dark deposits at the band center; (<b>c</b>) white deposits at the intermediate band edge.</p> Full article ">Figure 4
<p>Top views and cross-sections of SPS 8YSZ coatings at low and high magnifications. (<b>a</b>,<b>b</b>) surface morphologies; (<b>c</b>,<b>d</b>) cross-sections.</p> Full article ">Figure 5
<p>Thermal cycle life of SPS TBCs and APS DVC TBCs.</p> Full article ">Figure 6
<p>Photo (<b>a</b>) and SEM microstructures (<b>b</b>,<b>c</b>) of failed SPS TBCs after 1002 cycles.</p> Full article ">Figure 7
<p>Coating coverage rate of SPS TBCs and APS DVC TBCs.</p> Full article ">
15 pages, 4662 KiB  
Article
Tribological Properties of CrN/DLC and CrN Coatings under Different Testing Conditions
by Shuling Zhang, Xiangdong Yang, Tenglong Huang, Feng Guo, Longjie Dai, Yi Liu and Bo Zhang
Coatings 2024, 14(8), 1002; https://doi.org/10.3390/coatings14081002 - 7 Aug 2024
Viewed by 305
Abstract
CrN and diamond-like carbon (DLC) coatings are deposited on the surface of 431 stainless steel by the direct current magnetron sputtering technique. The surface morphology, micro-structure, hardness, friction, and wear properties of CrN, CrN/DLC and multi-layer composite DLC coatings are investigated by scanning [...] Read more.
CrN and diamond-like carbon (DLC) coatings are deposited on the surface of 431 stainless steel by the direct current magnetron sputtering technique. The surface morphology, micro-structure, hardness, friction, and wear properties of CrN, CrN/DLC and multi-layer composite DLC coatings are investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, nanoindentation tester, scratch tester, and friction and wear tester. The results show that the surface of the single CrN coating is very rough for the columnar crystal structure with preferred orientation. When it serves as inner transition layers to form the composite DLC coatings, the surface gets much smoother, with reduced defects. The friction and wear results indicate that the composite DLC coatings exhibit lower coefficients of friction, and better wear and corrosion resistance in dry friction, deionized water, and seawater. In the dry wear and friction process, the single CrN coating is easily worn out, and severe friction oxidation and furrow wear both appear with a friction coefficient of 0.48. But the friction coefficient of a CrN coating in seawater is reduced to 0.16, and friction oxidation and wear loss are further reduced with water lubrication. The CrN/DLC coating has excellent tribological performance in three test concoctions and has the lowest friction coefficient of 0.08 in seawater, which is related to the higher sp3 bond content, density (1.907 g/cm3) and high degree of amorphization, contributing to high hardness and a self-lubrication effect. However, due to the limited thickness of CrN/DLC (1.14 µm), it easily peels off and fails during friction and wear in different testing conditions. In multi-layer composite DLC coatings, there are more sp2 bonds with decreased amorphization, high enough thickness (4.02 µm), and increased bonding strength for the formation of different carbides and nitrides of chromium as transition layers, which gives rise to the further decreased average friction coefficient and the lowest wear loss. Therefore, the CrN coating alone has good wear resistance, and, as with the inner transition layer with a DLC coating, it can effectively improve the overall thickness and the bonding strength of the multi-layer films by optimizing the chemical compounds of DLC coatings. These results provide experimental support and reference for the design and selection of surface coatings for 431 stainless steels in different working conditions. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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<p>Deposition time and composition of different coatings.</p> Full article ">Figure 2
<p>Surface and cross-sectional morphology of different coatings: (<b>a</b>) CrN; (<b>b</b>) CrN/DLC; (<b>c</b>) Multi-layer DLC.</p> Full article ">Figure 3
<p>X-ray diffraction pattern of coatings.</p> Full article ">Figure 4
<p>Raman spectrum of coatings: (<b>a</b>) CrN/DLC; (<b>b</b>) Multi-layer DLC.</p> Full article ">Figure 5
<p>XPS diagram of multi-layer coating: (<b>a</b>) Total spectrum of elements; (<b>b</b>) C 1<span class="html-italic">s</span>; (<b>c</b>) Cr 2<span class="html-italic">p</span>; (<b>d</b>) N 1<span class="html-italic">s.</span></p> Full article ">Figure 6
<p>Scratches and bonding force of multi-layer DLC coating.</p> Full article ">Figure 7
<p>Indentation depth–load curve of multi-layer DLC coating.</p> Full article ">Figure 8
<p>Friction coefficient curves of coatings and substrate under different testing conditions: (<b>a</b>) Dry friction; (<b>b</b>) Deionized water; (<b>c</b>) Seawater.</p> Full article ">Figure 9
<p>Wear morphology and the corresponding EDS elemental analysis of coatings after dry friction: (<b>a</b>) CrN; (<b>b</b>) CrN/DLC; (<b>c</b>) Multi-layer DLC.</p> Full article ">Figure 10
<p>Wear morphology and the corresponding EDS elemental analysis of coatings after wear in deionized water: (<b>a</b>) CrN; (<b>b</b>) CrN/DLC; (<b>c</b>) Multi-layer DLC.</p> Full article ">Figure 11
<p>Wear morphology and the corresponding EDS elemental analysis of coatings after wear in seawater: (<b>a</b>) CrN; (<b>b</b>) CrN/DLC; (<b>c</b>) Multi-layer DLC.</p> Full article ">
16 pages, 9003 KiB  
Article
SiM-YOLO: A Wood Surface Defect Detection Method Based on the Improved YOLOv8
by Honglei Xi, Rijun Wang, Fulong Liang, Yesheng Chen, Guanghao Zhang and Bo Wang
Coatings 2024, 14(8), 1001; https://doi.org/10.3390/coatings14081001 - 7 Aug 2024
Viewed by 447
Abstract
Wood surface defect detection is a challenging task due to the complexity and variability of defect types. To address these challenges, this paper introduces a novel deep learning approach named SiM-YOLO, which is built upon the YOLOv8 object detection framework. A fine-grained convolutional [...] Read more.
Wood surface defect detection is a challenging task due to the complexity and variability of defect types. To address these challenges, this paper introduces a novel deep learning approach named SiM-YOLO, which is built upon the YOLOv8 object detection framework. A fine-grained convolutional structure, SPD-Conv, is introduced with the aim of preserving detailed defect information during the feature extraction process, thus enabling the model to capture the subtle variations and complex details of wood surface defects. In the feature fusion stage, a SiAFF-PANet-based wood defect feature fusion module is designed to improve the model’s ability to focus on local contextual information and enhance defect localization. For classification and regression tasks, the multi-attention detection head (MADH) is employed to capture cross-channel information and the accurate spatial localization of defects. In addition, MPDIoU is employed to optimize the loss function of the model to reduce the leakage of detection due to defect overlap. The experimental results show that SiM-YOLO achieves superior performance compared to the state-of-the-art YOLO algorithm, with a 9.3% improvement in mAP over YOLOX and a 4.3% improvement in mAP over YOLOv8. The Grad-CAM visualization further illustrates that SiM-YOLO provides more accurate defect localization and effectively reduces misdetection and omission issues. This study highlights the effectiveness of SiM-YOLO for wood surface defect detection and offers valuable insights for future research and practical applications in quality control. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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<p>Structure of SiM-YOLO.</p> Full article ">Figure 2
<p>Convolution downsampling module.</p> Full article ">Figure 3
<p>Structure of SPD-Conv (scale = 2).</p> Full article ">Figure 4
<p>Structure of multi-scale channel attention module. (<b>a</b>) MS-CAM; (<b>b</b>) SMS-CAM.</p> Full article ">Figure 5
<p>Structure of SiAFF.</p> Full article ">Figure 6
<p>Structure of MADH.</p> Full article ">Figure 7
<p>Structure of CA and CCA. (<b>a</b>) CA, (<b>b</b>) CCA.</p> Full article ">Figure 8
<p>Pine surface defect types in the dataset. (<b>a</b>) Live_Knot; (<b>b</b>) Marrow (Pith); (<b>c</b>) Resin (Resin pocket); (<b>d</b>) Dead_Knot; (<b>e</b>) Knot_with_crack; (<b>f</b>) Knot_missing; and (<b>g</b>) Crack.</p> Full article ">Figure 9
<p>Precision–recall (P-R) curves. (<b>a</b>) YOLOv7; (<b>b</b>) YOLOv8; and (<b>c</b>) SiM-YOLO.</p> Full article ">Figure 10
<p>Portion of visualization results.</p> Full article ">Figure 11
<p>Grad-CAM images of portion of experimental results. (<b>a</b>) Original image of Pine surface defect; (<b>b</b>) YOLOv7; (<b>c</b>) YOLOv8; and (<b>d</b>) SiM-YOLO.</p> Full article ">
24 pages, 4185 KiB  
Article
A Study on the Visual and Tactile Perception of Oriented Strand Board Combined with Consumer-Preference Analysis
by Yanfeng Miao, Xuefei Gao, Tianming Miao and Wei Xu
Coatings 2024, 14(8), 1000; https://doi.org/10.3390/coatings14081000 - 7 Aug 2024
Viewed by 327
Abstract
This study on oriented strand board (OSB) wood doors with veneer as the door leaf aimed to investigate consumers’ preference for visual–tactile elements of OSB. First, we utilized the questionnaire and interview methods to extract specific elements as experimental variables for this study. [...] Read more.
This study on oriented strand board (OSB) wood doors with veneer as the door leaf aimed to investigate consumers’ preference for visual–tactile elements of OSB. First, we utilized the questionnaire and interview methods to extract specific elements as experimental variables for this study. Then, through subjective evaluation experiments and eye-movement experiments, as well as correlation analyses of the experimental results, we explored the relationship between the slice size, gloss, and color of oriented strand boards and consumers’ visual preferences and summarized the eye-movement indexes that can represent consumers’ aesthetic evaluation of the visual elements of oriented strand boards. Unidirectional haptic experiments analyzed the relationships between the slice size, gloss, and roughness of the oriented strand boards and consumers’ haptic preferences. The results showed that, visually, chip size and surface gloss had little effect on people’s subjective aesthetic evaluations of oriented strand-board wood doors. At the same time, the quantitative mean pupil diameter could represent consumers’ aesthetic evaluations of oriented strand boards. Regarding haptics, the size of the wood chips on the surface of the oriented strand-board specimens did not significantly correlate with participants’ haptic preferences. All participants’ tactile preferences for the unpainted specimens were positively correlated with the fineness of sanding. The visual and tactile effects presented on the surface of an object are essential factors that influence the perception of a material. Oriented strand board (OSB) has excellent advantages in providing a healthy and environmentally friendly living environment, so exploring the visual and tactile perception of OSB from the consumer’s point of view plays a vital role in promoting the use of OSB. The visual–tactile experimental results and the conclusions drawn from the analysis in this study can enable OSB to provide more opinions and potential information from consumers for the design of OSB wooden doors under the premise of conforming to the actual production and meeting the quality standards so that the designed and produced OSB wooden doors can satisfy the users’ preferences based on safety and stability. Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
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<p>Fifteen colors of a door made of oriented strand board.</p> Full article ">Figure 2
<p>Six high-gloss colors for oriented particleboard wood doors.</p> Full article ">Figure 3
<p>Eye movement-experiment flowchart.</p> Full article ">Figure 4
<p>PCCS color-distribution map.</p> Full article ">Figure 5
<p>PCCS experimental color score distribution.</p> Full article ">Figure 6
<p>Stacking of first-gaze durations.</p> Full article ">Figure 7
<p>Stacking of average gaze durations.</p> Full article ">Figure 8
<p>Stacking of the weighting on gazing time.</p> Full article ">Figure 9
<p>Stacking of the weighting on attention counts.</p> Full article ">Figure 10
<p>Glossiness line graph.</p> Full article ">Figure 11
<p>Comparison graph of the size of abrasive grains.</p> Full article ">Figure 12
<p>Plot of 60° gloss against preference.</p> Full article ">Figure 13
<p>Plot of sandpaper type against tactile preference.</p> Full article ">
8 pages, 4119 KiB  
Review
Zirconia Implants: A Brief Review and Surface Analysis of a Lost Implant
by Eduardo Borie, Eduardo Rosas, Raphael Freitas de Souza and Fernando José Dias
Coatings 2024, 14(8), 995; https://doi.org/10.3390/coatings14080995 - 6 Aug 2024
Viewed by 360
Abstract
Zirconia implants have emerged as a valuable alternative for clinical scenarios where aesthetic demands are high, as well as in cases of hypersensitivity to titanium or for patients who refuse metallic objects in their bodies due to personal reasons. However, these implants have [...] Read more.
Zirconia implants have emerged as a valuable alternative for clinical scenarios where aesthetic demands are high, as well as in cases of hypersensitivity to titanium or for patients who refuse metallic objects in their bodies due to personal reasons. However, these implants have undergone various changes in geometry, manufacturing techniques, and surface modifications since the introduction of the first zirconia implants. The present study aims to review the current evidence on zirconia implants, considering the changes they have undergone in recent years. Additionally, it aims to analyze the three-dimensional surface characteristics of a failed zirconia implant using scanning electron microscopy and elemental analysis with energy-dispersive X-ray spectrometry (EDX). A zirconia implant lost three weeks after placement was immediately assessed using VP-SEM equipment and chemically analyzed by EDX using a 410-M detector connected to the microscope. Sparse material depositions were found on all parts of the implant, with a notable concentration in the thread grooves. The elements identified in the sample included zirconium, oxygen, carbon, calcium, and phosphorus. This report demonstrates that the surface of zirconia implants can accumulate elements early in the process of bone matrix neoformation, which is consistent with the initial stage of osseointegration. Full article
(This article belongs to the Special Issue Surface Properties of Implants and Biomedical Devices)
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<p>(<b>A</b>) Zirconia implant removed from the patient before EDX analysis. (<b>B</b>) Panoramic view of the Zr implant structure (Mag.: ×11).</p> Full article ">Figure 2
<p>Analysis of the structure of the Zr implant under the variable pressure scanning electron microscope. (<b>A</b>) Arrows showing material deposition of implant surface (Mag.: ×11). (<b>B</b>) Presence of material deposition (dark) on the implant structure (clear) with different morphological characteristics (Mag.: ×50). (<b>C</b>) Material in the form of crystals embedded in the structure of the implant (Mag.: ×500). (<b>D</b>) Deposition of more voluminous material suggestive of organic material (Mag.: ×500).</p> Full article ">Figure 3
<p>EDX spectra of the implant regions at 25 kV.</p> Full article ">
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