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Coatings
Volume 9
Issue 6
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Coatings, Volume 9, Issue 6 (June 2019) – 64 articles

Cover Story (view full-size image): Force-spinning is a versatile and low-cost alternative to electrospinning. PHBV is a microbial polymer with benign degradation products and can provide a suitable substrate to guide tissue regeneration, although it is limited in application by poor cellular adhesion properties. To produce extracellular matrix (ECM) mimicking fibre membranes from force-spun PHBV, we have grafted collagen molecules, with bio-functional motifs incorporated onto the fibres, enhancing the biological properties without degradation of key physical characteristics. The production rate and cytocompatibility of Collagen Functionalised Force-Spun PHBV Membranes are assessed to demonstrate that this is a quick and scalable production method for ECM-like membranes. View this paper.
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25 pages, 3716 KiB  
Review
A Brief Overview on the Anticorrosion Performances of Sol-Gel Zeolite Coatings
by Luigi Calabrese and Edoardo Proverbio
Coatings 2019, 9(6), 409; https://doi.org/10.3390/coatings9060409 - 24 Jun 2019
Cited by 28 | Viewed by 6521
Abstract
Research activity concerning nanoporous zeolites has grown considerably in recent decades. The structural porosity of zeolites provides versatile functional properties such as molecular selectivity, ion and molecule storage capacity, high surface area, and pore volume which combined with excellent thermal and chemical stability [...] Read more.
Research activity concerning nanoporous zeolites has grown considerably in recent decades. The structural porosity of zeolites provides versatile functional properties such as molecular selectivity, ion and molecule storage capacity, high surface area, and pore volume which combined with excellent thermal and chemical stability can extend its application fields in several industrial sectors. In such a context, anti-corrosion zeolite coatings are an emerging technology able to offer a reliable high performing and environmental friendly alternative to conventional chromate-based protective coatings. In this article, a focused overview on anti-corrosion performances of sol-gel composite zeolite coatings is provided. The topic of this review is addressed to assess the barrier and self-healing properties of composite zeolite coating. Based on results available in the literature, a property–structure relationship of this class of composites is proposed summarizing, furthermore, the competing anti-corrosion active and passive protective mechanisms involved during coating degradation. Eventually, a brief summary and a future trend evaluation is also reported. Full article
(This article belongs to the Special Issue Recent Developments on Functional Coatings for Industrial Applications)
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Figure 1

Figure 1
<p>Scheme of the structure of zeolite Y.</p> Full article ">Figure 2
<p>Scheme of a dip-coating process.</p> Full article ">Figure 3
<p>SEM image of composite zeolite coating with (<b>a</b>) 26.9 wt % of zeolite filler (Reprinted with permission from [<a href="#B77-coatings-09-00409" class="html-bibr">77</a>]. © 2013 Elsevier); and (<b>b</b>) 70 wt % of zeolite filler (Reprinted with permission from [<a href="#B81-coatings-09-00409" class="html-bibr">81</a>]. © 2014 Springer Nature).</p> Full article ">Figure 4
<p>Variation of impedance modulus at 0.1 Hz and zeolite filler content (wt %). Marker size is scaled to coating thickness.</p> Full article ">Figure 5
<p>Scheme of corrosion protection on defected area on zeolite-based coatings [<a href="#B84-coatings-09-00409" class="html-bibr">84</a>]. Reprinted with permission from [<a href="#B84-coatings-09-00409" class="html-bibr">84</a>]. © 2017 Taylor &amp; Francis.</p> Full article ">Figure 6
<p>Scheme of the self-healing process on Ce-doped zeolite coatings [<a href="#B66-coatings-09-00409" class="html-bibr">66</a>]. Reprinted with permission from [<a href="#B66-coatings-09-00409" class="html-bibr">66</a>]. © 2016 Elsevier.</p> Full article ">Figure 7
<p>Schematic illustration for the self-healing mechanism of composite coating doped with benzotriazole activated zeolite nanoparticles [<a href="#B74-coatings-09-00409" class="html-bibr">74</a>]. Reprinted with permission from [<a href="#B74-coatings-09-00409" class="html-bibr">74</a>]. © 2019 Elsevier.</p> Full article ">Figure 8
<p>Scheme of the self-healing process of double doped zeolite on AA2024 metal substrate.</p> Full article ">
15 pages, 3514 KiB  
Article
Custom-Made Chemically Modified Graphene Oxide to Improve the Anti-Scratch Resistance of Urethane-Acrylate Transparent Coatings
by Daniel Domene-López, Rubén Sarabia-Riquelme, Juan C. García-Quesada and Ignacio Martin-Gullon
Coatings 2019, 9(6), 408; https://doi.org/10.3390/coatings9060408 - 24 Jun 2019
Cited by 7 | Viewed by 4927
Abstract
In this work, a thermoset ultraviolet (UV)-cured polyurethane-acrylate resin was doped with different chemically-modified graphene obtained from a commercial graphene oxide (GO): as-received GO, chemically reduced GO (rGO), GO functionalized with vinyltriethoxysilane (VTES) (GOvtes), and GO functionalized with VTES and subsequently reduced with [...] Read more.
In this work, a thermoset ultraviolet (UV)-cured polyurethane-acrylate resin was doped with different chemically-modified graphene obtained from a commercial graphene oxide (GO): as-received GO, chemically reduced GO (rGO), GO functionalized with vinyltriethoxysilane (VTES) (GOvtes), and GO functionalized with VTES and subsequently reduced with a chemical agent (rGOvtes). Modified graphene was introduced in the oligomer component via solvent-assisted process using acetone, which was recovered after completion of the process. Results indicate that the GO-doped oligomers produce cured coatings with improved anti-scratch resistance (above the resistance of conventional coatings), without surface defects and high transparency. The anti-scratch resistance was measured with atomic force microscopy (AFM). Additionally, results are presented in terms of Wolf–Wilburn scale, a straightforward method widely accepted and employed in the coating industry. Full article
(This article belongs to the Special Issue Graphene-Based Composite Films)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>FTIR spectra of the different graphene derivatives used. From bottom to top: Graphene oxide (GO), reduced Graphene oxide (rGO), Graphene oxide functionalized with VTES (GOvtes) and Graphene oxide functionalized with VTES and reduced (rGOvtes).</p> Full article ">Figure 2
<p>Elemental analysis determined through XPS.</p> Full article ">Figure 3
<p>(<b>a</b>) C1s, (<b>b</b>) O1s and (<b>c</b>) N1s spectra of the different graphene derivatives. From the bottom to the top: GO, rGO, GOvtes, and rGOvtes.</p> Full article ">Figure 3 Cont.
<p>(<b>a</b>) C1s, (<b>b</b>) O1s and (<b>c</b>) N1s spectra of the different graphene derivatives. From the bottom to the top: GO, rGO, GOvtes, and rGOvtes.</p> Full article ">Figure 4
<p>(<b>a</b>) Optical picture of a coating containing 1 wt.% of GO showing transparency (allowing the text behind it to be read) and (<b>b</b>) transmittance results for all coatings prepared.</p> Full article ">Figure 5
<p>TEM images of coatings with 1 wt.% of GO (<b>a</b>) and rGOvtes (<b>b</b>).</p> Full article ">Figure 6
<p>AFM images of the surfaces of a 1 wt.% GO-cured coating before (<b>a</b>) and after performing the grooves to determine the anti-scratch resistance of the sample (<b>b</b>).</p> Full article ">Figure 6 Cont.
<p>AFM images of the surfaces of a 1 wt.% GO-cured coating before (<b>a</b>) and after performing the grooves to determine the anti-scratch resistance of the sample (<b>b</b>).</p> Full article ">Figure 7
<p>Anti-scratch resistance of the different cured coatings with graphene derivatives.</p> Full article ">
11 pages, 5789 KiB  
Article
TiBCN-Ceramic-Reinforced Ti-Based Coating by Laser Cladding: Analysis of Processing Conditions and Coating Properties
by Yuxin Li, Pengfei Zhang, Peikang Bai, Keqiang Su and Hongwen Su
Coatings 2019, 9(6), 407; https://doi.org/10.3390/coatings9060407 - 24 Jun 2019
Cited by 7 | Viewed by 3087
Abstract
In this paper, TiBCN-ceramic-reinforced Ti-based coating was fabricated on a Ti6Al4V substrate surface by laser cladding. The correlations between the main processing parameters and the geometrical characteristics of single clad tracks were predicted by linear regression analysis. On this basis, the microstructure, microhardness, [...] Read more.
In this paper, TiBCN-ceramic-reinforced Ti-based coating was fabricated on a Ti6Al4V substrate surface by laser cladding. The correlations between the main processing parameters and the geometrical characteristics of single clad tracks were predicted by linear regression analysis. On this basis, the microstructure, microhardness, corrosion resistance, and wear resistance of the coating and the substrate were investigated. The results showed that the clad height, clad width, clad depth, and dilution rate depended mainly on the laser power, the powder feeding rate, and the scanning speed. TiBCN-ceramic-reinforced Ti-based coating was mainly composed of directional dendritic TiBCN phases, equiaxed TiN phases, needle-like Al3Ti phases, and Ti phases. The microhardness gradually increased from the bottom to the top of the coating. The highest microhardness of coating was 1025 HV, which was three times higher than that of the Ti6Al4V substrate (350 HV). Furthermore, the coating exhibited excellent corrosion resistance and wear resistance. The corrosion potential (Ecorr) reached −1.258 V, and the corrosion density (Icorr) was 4.035 × 10−5 A/cm2, which was one order lower than that of the Ti6Al4V substrate (1.172 × 10−4 A/cm2). The coating wear mass loss was 4.35 mg, which was about two-third of the wear mass loss of the Ti6Al4V substrate (6.71 mg). Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Figure 1
<p>Schematic representation of geometrical characteristics in a single cladding.</p> Full article ">Figure 2
<p>The effect of the main processing parameter on the clad height (<span class="html-italic">h</span>).</p> Full article ">Figure 3
<p>(<b>a</b>) The relationship between clad height and the two processing parameters (scanning speed (<span class="html-italic">S</span>) and powder feeding rate (<span class="html-italic">F</span>)). (<b>b</b>) Residuals.</p> Full article ">Figure 4
<p>The effect of the main processing parameter on the clad width (<span class="html-italic">w</span>).</p> Full article ">Figure 5
<p>(<b>a</b>) The relationship between clad width and the three processing parameters (laser power (<span class="html-italic">P</span>), <span class="html-italic">S</span>, and <span class="html-italic">F</span>). (<b>b</b>) Residuals.</p> Full article ">Figure 6
<p>The effect of the main processing parameter on the clad depth (<span class="html-italic">b</span>).</p> Full article ">Figure 7
<p>(<b>a</b>) The relationship between clad depth and the two processing parameters (<span class="html-italic">P</span> and <span class="html-italic">S</span>). (<b>b</b>) Residuals.</p> Full article ">Figure 8
<p>The effect of the main processing parameter on the dilution rate.</p> Full article ">Figure 9
<p>(<b>a</b>) The relationship between the dilution rate and the three processing parameters (<span class="html-italic">P</span>, <span class="html-italic">S</span>, and <span class="html-italic">F</span>). (<b>b</b>) Residuals.</p> Full article ">Figure 10
<p>The XRD pattern of Ti/TiBCN coating.</p> Full article ">Figure 11
<p>SEM image of transverse cross-section of TiBCN-ceramic-reinforced Ti-based coating. (<b>a</b>) Cross-sectional macromorphology of the coating; (<b>b</b>) the interface region; (<b>c</b>) top of coating; and (<b>d</b>) the magnified image of the quadrangle in (<b>c</b>).</p> Full article ">Figure 12
<p>Bright-field TEM images of (<b>a</b>) reinforced particles and (<b>b</b>) selected area electron diffraction patterns.</p> Full article ">Figure 13
<p>The microhardness profile from the top of the coating to the substrate.</p> Full article ">Figure 14
<p>The potentiodynamic polarization curves for the coating and substrate.</p> Full article ">Figure 15
<p>The wear mass loss of the composite coating and substrate.</p> Full article ">Figure 16
<p>The worn surface morphologies of the composite coating and substrate: (<b>a</b>) composite coating; (<b>b</b>) substrate.</p> Full article ">
15 pages, 7377 KiB  
Article
Phase Evolution and Microstructure Analysis of CoCrFeNiMo High-Entropy Alloy for Electro-Spark-Deposited Coatings for Geothermal Environment
by Sigrun N. Karlsdottir, Laura E. Geambazu, Ioana Csaki, Andri I. Thorhallsson, Radu Stefanoiu, Fridrik Magnus and Cosmin Cotrut
Coatings 2019, 9(6), 406; https://doi.org/10.3390/coatings9060406 - 21 Jun 2019
Cited by 28 | Viewed by 5248
Abstract
In this work, a CoCrFeNiMo high-entropy alloy (HEA) material was prepared by the vacuum arc melting (VAM) method and used for electro-spark deposition (ESD). The purpose of this study was to investigate the phase evolution and microstructure of the CoCrFeNiMo HEA as as-cast [...] Read more.
In this work, a CoCrFeNiMo high-entropy alloy (HEA) material was prepared by the vacuum arc melting (VAM) method and used for electro-spark deposition (ESD). The purpose of this study was to investigate the phase evolution and microstructure of the CoCrFeNiMo HEA as as-cast and electro-spark-deposited (ESD) coating to assess its suitability for corrosvie environments encountered in geothermal energy production. The composition, morphology, and structure of the bulk material and the coating were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The hardness of the bulk material was measured to access the mechanical properties when preselecting the composition to be pursued for the ESD coating technique. For the same purpose, electrochemical corrosion tests were performed in a 3.5 wt.% NaCl solution on the bulk material. The results showed the VAM CoCrFeNiMo HEA material had high hardness (593 HV) and low corrosion rates (0.0072 mm/year), which is promising for the high wear and corrosion resistance needed in the harsh geothermal environment. The results from the phase evolution, chemical composition, and microstructural analysis showed an adherent and dense coating with the ESD technique, but with some variance in the distribution of elements in the coating. The crystal structure of the as-cast electrode CoCrFeNiMo material was identified as face centered cubic with XRD, but additional BCC and potentially σ phase was formed for the CoCrFeNiMo coating. Full article
(This article belongs to the Special Issue Coatings for Harsh Environments)
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Figure 1
<p>(<b>a</b>) Scanning electron microscopy (SEM) image showing the microstructure of the as-cast CoCrFeNiMo material revealing segregated compounds within the bulk and a table with energy-dispersive spectroscopy (EDS) analyses of areas highlighted with white boxes in image (<b>a</b>); and (<b>b</b>) SEM image of the compound at higher magnification.</p> Full article ">Figure 2
<p>Scanning electron microscopy (SEM) image and EDS maps of the as-cast CoCrFeNiMo bulk material.</p> Full article ">Figure 3
<p>The X-ray diffraction (XRD) pattern for the as-cast CoCrFeNiMo material.</p> Full article ">Figure 4
<p>(<b>a</b>) Open circuit potential variation and (<b>b</b>) potentiodynamic polarization curve for the bulk CoCrFeNiMo alloy tested electrochemically in 3.5% NaCl solution.</p> Full article ">Figure 5
<p>(<b>a</b>,<b>b</b>) SEM images of the surface of the CoCrFeNiMo coating; (<b>b</b>) includes a table with results from EDS analysis of the area identified with a white box in the SEM image.</p> Full article ">Figure 6
<p>Surface view of the deposited CoCrFeNiMo coating; SEM images at (<b>a</b>) lower magnification and (<b>b</b>) higher magnification.</p> Full article ">Figure 6 Cont.
<p>Surface view of the deposited CoCrFeNiMo coating; SEM images at (<b>a</b>) lower magnification and (<b>b</b>) higher magnification.</p> Full article ">Figure 7
<p>EDS elemental maps generated of the area shown in <a href="#coatings-09-00406-f006" class="html-fig">Figure 6</a>.</p> Full article ">Figure 8
<p>Back scattered electron (BSE) image of the cross-section of the CoCrFeNiMo coating and results from EDS analysis of the areas labelled in the BSE image.</p> Full article ">Figure 9
<p>XRD pattern for CoCrFeNiMo ESD coating (bottom graph) and as-cast material (top graph) for comparison.</p> Full article ">
10 pages, 3724 KiB  
Article
Corrosion Resistance Test of Electroplated Gold and Palladium Using Fast Electrochemical Analysis
by Walter Giurlani, Patrick Marcantelli, Francesco Benelli, Daniele Bottacci, Filippo Gambinossi, Maurizio Passaponti, Antonio De Luca, Emanuele Salvietti and Massimo Innocenti
Coatings 2019, 9(6), 405; https://doi.org/10.3390/coatings9060405 - 21 Jun 2019
Cited by 11 | Viewed by 5035
Abstract
Noble metal coatings are commonly employed to improve corrosion resistance of metals in the electronic and jewellery industry. The corrosion resistance of electroplated goods is currently determinate with long, destructive and almost subjective interpretation corrosion tests in artificial atmosphere. In this study we [...] Read more.
Noble metal coatings are commonly employed to improve corrosion resistance of metals in the electronic and jewellery industry. The corrosion resistance of electroplated goods is currently determinate with long, destructive and almost subjective interpretation corrosion tests in artificial atmosphere. In this study we present the application of electrochemical analysis to obtain fast and numerical information of the antiaging coating. We performed open circuit potential (OCP) and corrosion current measurement; we employed also the electrochemical impedance spectroscopy (EIS), commonly applied to organic or passivated metal with high-impedance, to find the best option for noble low-impedance coating analysis. For comparison, traditional standardized tests (damp heat ISO 17228, salt spray ISO 9227 and sulphur dioxide ISO 4524) were also performed. Full article
(This article belongs to the Special Issue Selected Papers from the 1st Coatings and Interfaces Web Conference (CIWC-1))
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Figure 1
<p>Atomic force microscopy (AFM) images of the electroplated substrates used for the determination of their roughness: (<b>a</b>) bronze; (<b>b</b>) copper. The roughness of the substrate must be very low in respect to the film thickness to ensure complete coverage.</p> Full article ">Figure 2
<p>(<b>a</b>) Open circuit potential (OCP) measurement over 16 h of copper (black), bronze (red), palladium (blue) and gold (green). (<b>b</b>) Polarization curves recorded between −0.25 and +1.3 V respect to the OCP after 16 h copper (black), bronze (red), palladium (blue) and gold (green). The measurement was performed also after the measurement of the OCP for 1 h in the case of bronze (pink).</p> Full article ">Figure 3
<p>Pictures of all the samples taken before and after the chemical corrosion tests. The three top images in each cell correspond to the before, while the after is on the bottom, the performed tests from left to right are: dump heat, salt spray and sulphur dioxide.</p> Full article ">Figure 4
<p>Cumulative charge plot (<b>a</b>) and OCP variation (<b>b</b>) during the electrochemical stress of 30 min repeated 12 times. Au +20 mV (black), Au +100 mV (red), Pd +20 mV (blue), Pd +100 mV (green); (1) samples (solid line), (2) samples (dash line), (3) samples (dot line).</p> Full article ">Figure 5
<p>Equivalent circuit used to fit the electrochemical impedance spectroscopy (EIS) data.</p> Full article ">Figure 6
<p>Comparison after the +20 mV stress (black), +100 mV stress (red) and salt spray test (blue) of the calculated Δ<span class="html-italic">Z</span>% value for the gold (<b>a</b>) and the palladium (<b>b</b>) samples.</p> Full article ">
8 pages, 1858 KiB  
Article
Double-Sided Anti-Reflection Nanostructures on Optical Convex Lenses for Imaging Applications
by Hyuk Jae Jang, Yeong Jae Kim, Young Jin Yoo, Gil Ju Lee, Min Seok Kim, Ki Soo Chang and Young Min Song
Coatings 2019, 9(6), 404; https://doi.org/10.3390/coatings9060404 - 21 Jun 2019
Cited by 15 | Viewed by 7208
Abstract
Anti-reflection coatings (ARCs) from the cornea nipple array of the moth-eye remarkably suppress the Fresnel reflection at the interface in broadband wavelength ranges. ARCs on flat glass have been studied to enhance the optical transmittance. However, little research on the implementation of ARCs [...] Read more.
Anti-reflection coatings (ARCs) from the cornea nipple array of the moth-eye remarkably suppress the Fresnel reflection at the interface in broadband wavelength ranges. ARCs on flat glass have been studied to enhance the optical transmittance. However, little research on the implementation of ARCs on curved optical lenses, which are the core element in imaging devices, has been reported. Here, we report double-sided, bio-inspired ARCs on bi-convex lenses with high uniformity. We theoretically optimize the nanostructure geometry, such as the height, period, and morphology, since an anti-reflection property results from the gradually changed effective refractive index by the geometry of nanostructures. In an experiment, the transmittance of an ARCs lens increases up to 10% for a broadband spectrum without distortion in spot size and focal length. Moreover, we demonstrate ~30% improved transmittance of an imaging system composed of three bi-convex lenses, in series with double-sided ARCs (DARCs). Full article
(This article belongs to the Special Issue Semiconductor Thin Films)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>a</b>) Schematic illustration showing the antireflection coatings on both sides of the bi-convex lens, and scanning electron microscope (SEM) image of fabricated SiO<sub>2</sub> nanostructures on the BK7 lens. Scale bar is 300 nm. (<b>b</b>) Photographic images of SF11 and BK7 lens with bare and DARCs, respectively. Scale bar is 15 mm. (<b>c</b>) Measured transmittance spectra of optical lenses in <a href="#coatings-09-00404-f001" class="html-fig">Figure 1</a>b. (<b>d</b>) Schematic illustration of designed optical system, including three double-convex lenses: two BK7 lenses and one SF11 lens. The image at the bottom-right is the surface light source with a mask for the object. (<b>e</b>) Optical images at the image plane, in <a href="#coatings-09-00404-f001" class="html-fig">Figure 1</a>d, with three bare optical lenses and three DARCs lenses, respectively. (<b>f</b>) Comparison of measured intensity spectra of dashed line in <a href="#coatings-09-00404-f001" class="html-fig">Figure 1</a>e.</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic illustration of rod, truncated cone, and cone-shaped nanostructures in terms of cone ratio. (<b>b</b>) Calculated transmittance profile of SF11 flat glass with SiO<sub>2</sub> DARCs in a wavelength range from 400 to 1600 nm as a function of the period, <span class="html-italic">p</span> (top), height, <span class="html-italic">h</span> (middle), and FF (bottom). (<b>c</b>) Calculated average transmittance spectrum of SF11 with DARCs lens as a function of the cone ratio. The dashed line represents the average transmittance of the SF11 bare lens. (<b>d</b>) Calculated average transmittance as a function of angle of incidence. (<b>e</b>) Bar profiles of the diffraction efficiency of DARCs lens with a period of 200 (left) and 500 nm (right) at a wavelength of 400 nm. (<b>f</b>) Electric field distribution of the period at 200 and 500 nm. The dashed line displays the structure outline.</p> Full article ">Figure 3
<p>(<b>a</b>) Schematic illustration of fabrication process steps. (<b>b</b>) SEM images (1500 nm × 1300 nm) showing a top view in terms of position from center to edge of BK7 lens and SF11 lens. Scale bar is 500 nm. (<b>c</b>) Comparison of the filling fraction in terms of position from the center to the right edge.</p> Full article ">Figure 4
<p>(<b>a</b>) Schematic illustration of optical setup for estimating the imaging characteristics of a single lens. (<b>b</b>) Beam profile (50 × 50 pixels; 83.5 μm × 83.5 μm) of a single SF11 bare lens and SF11 DARCs lens using various laser diodes with wavelengths of 520, 635, and 980 nm. (<b>c</b>) Plot of normalized peak intensity and power enhancement ratio of a SF11 bare lens and DARCs lens as a function of the relative displacement of the lenses. Dashed line shows unchanged focal length. (<b>d</b>) Comparison of full width at half maximum (FWHM) in <a href="#coatings-09-00404-f004" class="html-fig">Figure 4</a>b in terms of <span class="html-italic">x</span> and <span class="html-italic">y</span> directions.</p> Full article ">
10 pages, 1321 KiB  
Article
The Antibacterial Properties and Safety of a Nanoparticle-Coated Parquet Floor
by Chong Jia, Yang Zhang, Juqing Cui and Lu Gan
Coatings 2019, 9(6), 403; https://doi.org/10.3390/coatings9060403 - 21 Jun 2019
Cited by 11 | Viewed by 4263
Abstract
Floor antibacterial technology prevents the human body from cross-infection with bacterial diseases. The most commonly used approach to endow daily-used floors with antibacterial properties is to apply a thin film of antibacterial agents on the parquet floor surface. In the present study, five [...] Read more.
Floor antibacterial technology prevents the human body from cross-infection with bacterial diseases. The most commonly used approach to endow daily-used floors with antibacterial properties is to apply a thin film of antibacterial agents on the parquet floor surface. In the present study, five commercial antibacterial nanoparticles were first dispersed in melamine resin solution, and then applied on a floor. Afterwards, the antibacterial properties of the nanoparticle-coated floor were investigated, in which Escherichia coli was used as the target bacteria. The impact of the nanoparticle dispersing agents on the ultimate antibacterial properties of the floor were also investigated. The results showed that silver nanoparticle-loaded hydroxyl zirconium sodium phosphate (Ag-HZDP) was most suitable as the antibacterial agent of a melamine coating for parquet flooring. With the help of sodium hexametaphosphate, the antibacterial agent was able to disperse well in the melamine resin solution and was also able to disperse well on the floor surface. When the loading amount of Ag-HZDP was 1 wt % or higher, the prepared antibacterial floor was able kill almost all the bacteria cultivated on its surface. Moreover, the prepared antibacterial floor had a lower toxicity compared with a pristine cedar substrate. The present study provides an effective way to provide daily-used parquet floors with excellent antibacterial properties. Full article
(This article belongs to the Special Issue Recent Developments in Antibacterial and/or Antifouling Surfaces)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Effect of different quantities of antibacterial agents on the color of the coatings.</p> Full article ">Figure 2
<p>Antibacterial ratio of different antibacterial agents loaded with melamine resin coatings.</p> Full article ">Figure 3
<p>Antibacterial ratio of Ag-HZDP-melamine resin solution-coated cedar parquet floor, with and without Na<sub>6</sub>P<sub>6</sub>O<sub>18</sub>.</p> Full article ">Figure 4
<p>SEM image of cedar parquet floor (<b>a</b>) without coating, (<b>b</b>) with pure melamine resin solution, (<b>c</b>) with Ag-HZDP-loaded melamine resin solution, and (<b>d</b>) magnified cedar parquet floor with Ag-HZDP-loaded melamine resin solution.</p> Full article ">Scheme 1
<p>Illustration of subsidence value of the antibacterial nanoparticles in melamine resin solution.</p> Full article ">
11 pages, 4766 KiB  
Article
HA Coating on Ti6Al7Nb Alloy Using an Electrophoretic Deposition Method and Surface Properties Examination of the Resulting Coatings
by İbrahim Aydın, Ali İhsan Bahçepınar, Mustafa Kırman and Mustafa Ali Çipiloğlu
Coatings 2019, 9(6), 402; https://doi.org/10.3390/coatings9060402 - 21 Jun 2019
Cited by 15 | Viewed by 3710
Abstract
Ti and its alloys, which are commonly used in biomedical applications, are often preferred due to their proximity to the mechanical properties of bone. In order to increase the biocompatibility and bioactivities of these materials, biomaterials based on ceramic are used in coating [...] Read more.
Ti and its alloys, which are commonly used in biomedical applications, are often preferred due to their proximity to the mechanical properties of bone. In order to increase the biocompatibility and bioactivities of these materials, biomaterials based on ceramic are used in coating operations. In this study, by using an electrophoretic deposition method, instead of on the Ti6Al4V alloy which is commonly used in the literature, a hydroxyapatite (HA) coating operation was applied on the surface of the Ti6Al7Nb alloy, and the surface properties of the coatings were examined. Ti6Al7Nb is a new-generation implant on which there have not been many studies. The voltage values which were used in the coating operation were 50, 100, 150 and 200 V, and the time parameter was stabilized at 1 min. In our method, when preparing the solution, HA, ethanol, and polyvinyl alcohol (PVA) were used. At the end of the study, by using an electron microscope (SEM) the microstructures of the coatings were examined; elemental analyses (EDS) of the coating surfaces were performed; and by using an X-radiation diffraction (XRD) method, the phases which the coatings contained and the concentration of these phases were determined, and the coating thickness, roughness, and hardness values were also determined. Also, by conducting a Scratch test, the strength of the surface combination was examined. At the end of the study, in each parameter, a successful HA coating was seen. By comparing parameters with each other, the ideal voltage value in this coating was determined. It was determined that the most suitable coating was obtained at 100 V voltage and 1 min deposition time. Full article
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Figure 1

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<p>TiAl7Nb alloys: (<b>a</b>) pre-coating and (<b>b</b>) post-coating images.</p> Full article ">Figure 2
<p>Optical microscope image of the Ti6Al7Nb alloy surface prior to coating.</p> Full article ">Figure 3
<p>SEM images of hydroxyapatite (HA)-coated Ti6Al7Nb alloys (5000×): (<b>a</b>) 50 V/60 s, (<b>b</b>) 100 V/60 s, (<b>c</b>) 150 V/60 s, (<b>d</b>) 200 V/60 s.</p> Full article ">Figure 4
<p>The EDS results of HA-coated Ti6Al7Nb alloys: (<b>a</b>) 50 V/60 s, (<b>b</b>) 100 V/60 s, (<b>c</b>) 150 V/60 s, (<b>d</b>) 200 V/60 s.</p> Full article ">Figure 4 Cont.
<p>The EDS results of HA-coated Ti6Al7Nb alloys: (<b>a</b>) 50 V/60 s, (<b>b</b>) 100 V/60 s, (<b>c</b>) 150 V/60 s, (<b>d</b>) 200 V/60 s.</p> Full article ">Figure 5
<p>XRD analysis results.</p> Full article ">Figure 6
<p>The friction force which occurred under the loads applied during Scratch testing of the coatings formed at 50 V and a 1 min period, and the variation of the friction coefficients.</p> Full article ">Figure 7
<p>The friction force which occurred under the loads applied during Scratch testing of the coatings formed at 100 V and a 1 min period, and the variation of the friction coefficients.</p> Full article ">Figure 8
<p>The friction force which occurred under the loads applied during Scratch testing of the coatings formed at 150 V and a 1 min period, and the variation of the friction coefficients.</p> Full article ">Figure 9
<p>The friction force which occurred under the loads applied during Scratch testing of the coatings formed at 200 V and a 1 min period, and the variation of the friction coefficients.</p> Full article ">
9 pages, 1483 KiB  
Article
The Relationship between Solid Content and Particle Size Ratio of Waterborne Polyurethane
by Jinghui Hou, Yifei Ma, Zihan Zhang, Xuanhe Yang, Muhua Huang and Chunpeng Chai
Coatings 2019, 9(6), 401; https://doi.org/10.3390/coatings9060401 - 21 Jun 2019
Cited by 14 | Viewed by 4178
Abstract
A series of high solid content carboxylic acid/sulfonic acid waterborne polyurethanes was prepared by the emulsion dispersion method. The particle size and solid content were measured. By changing the particle size of the large particles to achieve different particle size ratios, high solid [...] Read more.
A series of high solid content carboxylic acid/sulfonic acid waterborne polyurethanes was prepared by the emulsion dispersion method. The particle size and solid content were measured. By changing the particle size of the large particles to achieve different particle size ratios, high solid content waterborne polyurethanes were obtained at specific particle size ratios. When the particle size ratio was >7, 4–5 or 2–3, the aqueous polyurethane could reach a higher solid content (more than 56%). This indicated that solid content is related to particle size distribution in high solid content waterborne polyurethane. Moreover, the corresponding three-dimensional stacked models (simple cubic accumulation, face-centered cubic accumulation, cubic close packing and hexagonal closest packing) were established. Full article
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Graphical abstract
Full article ">Figure 1
<p>The scheme of the formation of WPU-L and WPU-Hap/Hdp.</p> Full article ">Figure 2
<p>FTIR spectra of WPU-L<sub>1</sub>.</p> Full article ">Figure 3
<p>The particle size of the WPU-L, WPU-Hap, and WPU-Hdp emulsions.</p> Full article ">Figure 4
<p>The polydispersity index (PDI) of the WPU-L, WPU-Hap, and WPU-Hdp emulsions.</p> Full article ">Figure 5
<p>Solid content scatter plot of high solid emulsions.</p> Full article ">Figure 6
<p>Three-dimensional stacked models: (<b>a</b>) simple cubic accumulation; (<b>b</b>) face-centered cubic accumulation; (<b>c</b>) cubic close packing; and (<b>d</b>) hexagonal closest packing.</p> Full article ">Figure 7
<p>Simulation curve of the particle size ratio–solid content.</p> Full article ">
31 pages, 7304 KiB  
Review
Nanocrystalline Cermet Coatings for Erosion–Corrosion Protection
by Abhishek Tiwari, Saravanan Seman, Gaurav Singh and Rengaswamy Jayaganthan
Coatings 2019, 9(6), 400; https://doi.org/10.3390/coatings9060400 - 20 Jun 2019
Cited by 15 | Viewed by 7252
Abstract
The processing techniques, microstructural characteristics, and erosion corrosion behaviour of Cr3C2–NiCr and tungsten carbide (WC)-based cermet coatings are reviewed in this work. Conventional and nanocrystalline Cr3C2–NiCr and WC-based cermet coatings are generally synthesized using thermal [...] Read more.
The processing techniques, microstructural characteristics, and erosion corrosion behaviour of Cr3C2–NiCr and tungsten carbide (WC)-based cermet coatings are reviewed in this work. Conventional and nanocrystalline Cr3C2–NiCr and WC-based cermet coatings are generally synthesized using thermal spray technique. The wear, erosion, and corrosion protection ability of conventional and nanocermet coatings are compared based on available literature. In Cr3C2–NiCr coatings, the corrosion resistance is offered by NiCr metal matrix while the wear resistance is provided by the carbide ceramic phase, making it suitable for erosion–corrosion protection. The nanocrystalline cermet coatings exhibits better erosion–corrosion resistance as compared to the conventional coatings. The nanocrystalline coatings reduces the erosion–corrosion rate significantly compared to conventional coatings. It is attributed to the presence of the protective NiCr metallic binder that allows easier and faster re-passivation when the coating is subjected to wear and the fine-grain structure with homogeneous distribution of the skeleton network of hard carbide phases. In addition, corrosion-accelerated erosion dominates the reaction mechanism of erosion–corrosion and, therefore, higher hardness, strength, and better wear resistance of nanocermet coating along with its faster repassivation kinetics accounts for improved corrosion resistance as compared to conventional coatings. Full article
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<p>SEM micrographs of the coatings (<b>a</b>) WC-12Co, (<b>b</b>) WC-10Co-4Cr, and (<b>c</b>) Cr<sub>3</sub>C<sub>2</sub>–NiCr and XRD patterns of (<b>d</b>) initial feedstock powders and (<b>e</b>) as sprayed coatings. In the inset, SEM images of feedstock powders are shown [<a href="#B41-coatings-09-00400" class="html-bibr">41</a>]. Reprinted with permission from ref [<a href="#B41-coatings-09-00400" class="html-bibr">41</a>]. © 2017 Elsevier.</p> Full article ">Figure 2
<p>Comparison between thermal spraying of conventional and nanostructured powders [<a href="#B42-coatings-09-00400" class="html-bibr">42</a>]. Reprinted with permission from ref [<a href="#B42-coatings-09-00400" class="html-bibr">42</a>]. © 1995 Elsevier.</p> Full article ">Figure 3
<p>Typical schematic of the bimodal microstructure of thermal spray coatings formed by fully molten and semi-molten nanostructured agglomerated particles [<a href="#B64-coatings-09-00400" class="html-bibr">64</a>]. Reprinted with permission from ref [<a href="#B64-coatings-09-00400" class="html-bibr">64</a>]. © 2007 Springer Nature.</p> Full article ">Figure 4
<p>SEM micrographs of (<b>a</b>) chromium powders, (<b>b</b>) carbon powders, (<b>c</b>) Cr<sub>3</sub>C<sub>2</sub> mixture milled for 2 h, (<b>d</b>) Cr<sub>3</sub>C<sub>2</sub> mixture milled for 6 h, and (<b>e</b>) Cr<sub>3</sub>C<sub>2</sub> mixture milled for 10 h [<a href="#B70-coatings-09-00400" class="html-bibr">70</a>]. Reprinted with permission from ref [<a href="#B70-coatings-09-00400" class="html-bibr">70</a>]. © 2012 Elsevier.</p> Full article ">Figure 5
<p>Sketch of the apparatus used for tribo-corrosion tests [<a href="#B6-coatings-09-00400" class="html-bibr">6</a>]. Reprinted with permission from ref. [<a href="#B6-coatings-09-00400" class="html-bibr">6</a>]. © 2004 Elsevier.</p> Full article ">Figure 6
<p>Volume loss of the high-velocity oxy-fuel (HVOF) coatings under the different tribo-corrosion conditions [<a href="#B6-coatings-09-00400" class="html-bibr">6</a>]. Reprinted with permission from ref [<a href="#B6-coatings-09-00400" class="html-bibr">6</a>]. © 2004 Elsevier.</p> Full article ">Figure 7
<p>Potentiodynamic polarization curves for C10 (Cr<sub>3</sub>C<sub>2</sub>–NiCr-coated sample), CHC (hard chromium coating), and steel substrate after 20 h immersion in 3.4% NaCl at 25 °C [<a href="#B102-coatings-09-00400" class="html-bibr">102</a>]. Reprinted with permission from ref [<a href="#B102-coatings-09-00400" class="html-bibr">102</a>]. © 2006 Elsevier.</p> Full article ">Figure 8
<p>Time dependence of corrosion potential (<b>a</b>) and Potentiodynamic polarization curves (<b>b</b>) for WC–17Co coated and uncoated steel exposed to fluid flow sand particles in 3.5 wt. % NaCl + 1000 ppm (~0.001 wt. %) NaHCO<sub>3</sub> solution [<a href="#B114-coatings-09-00400" class="html-bibr">114</a>]. Reprinted with permission from ref [<a href="#B114-coatings-09-00400" class="html-bibr">114</a>]. © 2011 Elsevier.</p> Full article ">Figure 9
<p>Electrochemical impedance spectroscopy (EIS) of near-nanocrystalline WC–17Co, microcrystalline WC–17Co coatings, and uncoated steel exposed to fluid flow (sand particles in 3.5 wt. % NaCl with 1000 ppm (~0.001 wt. %) NaHCO<sub>3</sub> solution): (<b>a</b>) Nyquist diagrams and (<b>b</b>) Bode plots [<a href="#B114-coatings-09-00400" class="html-bibr">114</a>]. Reprinted with permission from ref [<a href="#B114-coatings-09-00400" class="html-bibr">114</a>]. © 2011 Elsevier.</p> Full article ">
12 pages, 4176 KiB  
Article
Preparation and Anticorrosive Property of Soluble Aniline Tetramer
by Yongbo Ding, Jia Liang, Gaofeng Liu, Wenting Ni and Liang Shen
Coatings 2019, 9(6), 399; https://doi.org/10.3390/coatings9060399 - 20 Jun 2019
Cited by 18 | Viewed by 4075
Abstract
Soluble aniline tetramer (AT) was successfully prepared by chemical oxidation method. Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-vis) were used to characterize its structure. The redox behavior of AT was identified through the electrochemical cyclic voltammetry studies. Then, the epoxy coating [...] Read more.
Soluble aniline tetramer (AT) was successfully prepared by chemical oxidation method. Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-vis) were used to characterize its structure. The redox behavior of AT was identified through the electrochemical cyclic voltammetry studies. Then, the epoxy coating was prepared by using AT as inhibitor. Its anticorrosive property was evaluated by salt solution resistance test, polarization curve, and electrochemical impedance spectroscopy (EIS). Salt solution resistance test, polarization curves, and EIS measurements indicate that the obtained epoxy anticorrosive coating, containing 1.0% AT, exhibits remarkably enhanced corrosion protection properties on Q235 steel electrodes as compared to pure epoxy anticorrosive coating without AT. The significantly improved anticorrosion performance may be owing to the redox behavior of the AT, adsorption and inhibition effect of AT on Q235 steel surface, as well as synergistic curing effect by AT and polyamide. Full article
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<p>Synthesis (<b>a</b>) and photograph (<b>b</b>) of aniline tetramer.</p> Full article ">Figure 2
<p>FTIR spectra of aniline tetramer.</p> Full article ">Figure 3
<p>UV-vis spectra of aniline tetramer measured in dimethyl sulfoxide (DMSO).</p> Full article ">Figure 4
<p>Solubility experiments of aniline tetramer in different solvents.</p> Full article ">Figure 5
<p>SEM photos of aniline tetramer under different magnification: (<b>a</b>) scale bar: 1000 nm; (<b>b</b>) scale bar: 500 nm.</p> Full article ">Figure 6
<p>Cyclic voltammogram of AT in 1 M HCl solution (aniline tetramer modified glass carbon electrode used as work electrode).</p> Full article ">Figure 7
<p>Corrosion behavior of epoxy coatings containing different content of AT after 3.5% NaCl solution immersion for different times(1: 0.0% AT, 2: 0.1% AT, 3: 0.5% AT, 4: 1.0% AT).</p> Full article ">Figure 8
<p>The polarization curves of bare (<b>a</b>), pure epoxy-coated (<b>b</b>), and epoxy coating with 1.0%AT-coated (<b>c</b>) Q235 steel electrodes after immersion in 3.5% NaCl for 24 h.</p> Full article ">Figure 9
<p>The Nyquist (<b>a</b>) and bode plots (<b>b</b>) of epoxy coating with 0.0% and 1.0% AT immersed in 3.5% NaCl solution after 24 h. (a) The Nyquist diagrams of epoxy coating with 0.0% and 1.0% AT immersed in 3.5% NaCl solution after 24 h; (b) The bode plots of epoxy coating with 0.0% and 1.0% AT immersed in 3.5% NaCl solution after 24 h.</p> Full article ">Figure 10
<p>The equivalent circuit (R(QR)(QR)) (<b>a</b>) used to fit the EIS data and the fitted Nyquist data (<b>b</b>) from the equivalent circuit with or without AT.</p> Full article ">Figure 11
<p>The dynamic thermomechanical analysis (DMA) curves of epoxy coating with 0.0% and 1.0% AT.</p> Full article ">
10 pages, 5475 KiB  
Article
Preparation of Superhydrophobic Steel Surfaces with Chemical Stability and Corrosion
by Chongwei Du, Xiaoyan He, Feng Tian, Xiuqin Bai and Chengqing Yuan
Coatings 2019, 9(6), 398; https://doi.org/10.3390/coatings9060398 - 20 Jun 2019
Cited by 39 | Viewed by 4090
Abstract
Corrosion seriously limits the long-term application of Q235 carbon steel. Herein, a simple fabrication method was used to fabricate superhydrophobic surfaces on Q235 carbon steel for anticorrosion application. The combination of structure and the grafted low-surface-energy material contributed to the formation of superhydrophobic [...] Read more.
Corrosion seriously limits the long-term application of Q235 carbon steel. Herein, a simple fabrication method was used to fabricate superhydrophobic surfaces on Q235 carbon steel for anticorrosion application. The combination of structure and the grafted low-surface-energy material contributed to the formation of superhydrophobic steel surfaces, which exhibited a water contact angle of 161.6° and a contact angle hysteresis of 0.8°. Meanwhile, the as-prepared superhydrophobic surface showed repellent toward different solutions with pH ranging from 1 to 14, presenting excellent chemical stability. Moreover, the acid corrosive liquid (HCl solution with pH of 1) maintained sphere-like shape on the as-prepared superhydrophobic surface at room temperature, indicating superior corrosion resistance. This work provides a simple method to fabricate superhydrophobic steel surfaces with chemical stability and corrosion resistance. Full article
(This article belongs to the Special Issue Superhydrophobic Coatings for Corrosion and Tribology)
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<p>SEM images of polished Q235 carbon steel surface (<b>a</b>), structured Q235 carbon steel surface (<b>b</b>) and structured surface after modification of PFTEOS (<b>c</b>). (-2 is the high magnification image of -1, respectively).</p> Full article ">Figure 2
<p>EDS of polished Q235 carbon steel surface (<b>a</b>), structured Q235 carbon steel surface (<b>b</b>), and structured surface after modification of PFTEOS (<b>c</b>).</p> Full article ">Figure 3
<p>XPS spectra detected from structured Q235 carbon steel surface: the XPS survey spectra (<b>a-1</b>), O 1<span class="html-italic">s</span> spectra (<b>a-2</b>) and C 1<span class="html-italic">s</span> spectra (<b>a-3</b>) and structured surface after modification of PFTEOS: the XPS survey spectra (<b>b-1</b>), O 1<span class="html-italic">s</span> spectra (<b>b-2</b>), C 1<span class="html-italic">s</span> spectra (<b>b-3</b>), F 1<span class="html-italic">s</span> spectra (<b>b-4</b>) and Si 2<span class="html-italic">p</span> spectra (<b>b-5</b>). All spectra were corrected to the polluted C 1<span class="html-italic">s</span> spectra.</p> Full article ">Figure 4
<p>Contact angle of water on the polished Q235 carbon steel surface (<b>a</b>), polished steel surface after modification of PFTEOS (<b>b</b>), microstructured steel surface (<b>c</b>), and structured steel surface after modification of PFTEOS (<b>d</b>).</p> Full article ">Figure 5
<p>Bounce phenomenon of superhydrophobic Q235 carbon steel surface (5 μL).</p> Full article ">Figure 6
<p>Comparison of different pH environments contact angle of structured Q235 carbon steel and superhydrophobic Q235 carbon steel.</p> Full article ">Figure 7
<p>Nyquist plots (<b>a</b>) and Potentiodynamic polarization curves (<b>b</b>) of untreated Q235 carbon steel samples, structured Q235 carbon steel samples, and superhydrophobic Q235 carbon steel samples.</p> Full article ">Figure 8
<p>Sequential images of a highly corrosive liquid droplet (pH = 1 HCl + CuSO<sub>4</sub>) on the surfaces of untreated Q235 carbon steel (<b>a</b>), structured Q235 carbon steel (<b>b</b>), superhydrophobic Q235 carbon steel (<b>c</b>).</p> Full article ">
10 pages, 5299 KiB  
Article
Surface Properties of Pine Scrimber Panels with Varying Density
by Jinguang Wei, Qiuqin Lin, Yahui Zhang, Wenji Yu, Chung-Yun Hse and Todd Shupe
Coatings 2019, 9(6), 397; https://doi.org/10.3390/coatings9060397 - 20 Jun 2019
Cited by 6 | Viewed by 3279
Abstract
Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because [...] Read more.
Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because the water contact angles were less than 90°. The panels with a density of 1.20 g/cm3 had the largest angle change rate (k = 0.212). As the panel density increased, the instantaneous contact angle of each test liquid (i.e., water, formamide, and diiodomethane) on the panels decreased, and so did surface free energy. Panels with higher density showed lower surface roughness. Surface roughness across the wood grain was greater than that along the grain. SEM observations showed the high-density panels had a smoother surface with fewer irregular grooves in comparison with the low-density panels. X-ray photoelectron spectroscopy (XPS) analysis indicated that more unoxygenated groups appeared on the surface of high-density panels. Full article
(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)
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<p>Contact angles of water as a function of time for scrimbers with various densities.</p> Full article ">Figure 2
<p>Contact angles of three liquids at one second on the scrimber surfaces.</p> Full article ">Figure 3
<p>Schematic of (<b>a</b>) scrimber preparation and (<b>b</b>) surface roughness measurement.</p> Full article ">Figure 4
<p>Surface roughness of scrimbers at different densities.</p> Full article ">Figure 5
<p>Surface micrographs of the sanded scrimbers with various densities: (<b>a</b>) 0.80, (<b>b</b>) 1.01, (<b>c</b>) 1.20 and (<b>d</b>) 1.39 g/cm<sup>3</sup>.</p> Full article ">Figure 6
<p>X-ray photoelectron spectroscopy (XPS) spectra of scrimbers with densities of (<b>a</b>) 0.80, (<b>b</b>) 1.01, (<b>c</b>) 1.20 and (<b>d</b>) 1.39 g/cm<sup>3</sup>.</p> Full article ">Figure 7
<p>C1<span class="html-italic">s</span> spectra of scrimbers with varying density: (<b>a</b>) 0.80, (<b>b</b>) 1.01, (<b>c</b>) 1.20 and (<b>d</b>) 1.39 g/cm<sup>3</sup>.</p> Full article ">
17 pages, 6032 KiB  
Article
Evaluation of the Corrosion Resistance and Cytocompatibility of a Bioactive Micro-Arc Oxidation Coating on AZ31 Mg Alloy
by Shun-Yi Jian, Mei-Ling Ho, Bing-Ci Shih, Yue-Jun Wang, Li-Wen Weng, Min-Wen Wang and Chun-Chieh Tseng
Coatings 2019, 9(6), 396; https://doi.org/10.3390/coatings9060396 - 20 Jun 2019
Cited by 20 | Viewed by 4121
Abstract
Magnesium alloys have recently been attracting attention as a degradable biomaterial. They have advantages including non-toxicity, biocompatibility, and biodegradability. To develop magnesium alloys into biodegradable medical materials, previous research has quantitatively analyzed magnesium alloy corrosion by focusing on the overall changes in the [...] Read more.
Magnesium alloys have recently been attracting attention as a degradable biomaterial. They have advantages including non-toxicity, biocompatibility, and biodegradability. To develop magnesium alloys into biodegradable medical materials, previous research has quantitatively analyzed magnesium alloy corrosion by focusing on the overall changes in the alloy. Therefore, the objective of this study is to develop a bioactive material by applying a ceramic oxide coating (magnesia) on AZ31 magnesium alloy through micro-arc oxidation (MAO) process. This MAO process is conducted under pulsed bipolar constant current conditions in a Si- and P-containing electrolyte and the optimal processing parameters in corrosion protection are obtained by the Taguchi method to design a coating with good anti-corrosion performance. The negative duty cycle and treatment time are two deciding factors of the coating’s capability in corrosion protection. Microstructure characterizations are investigated by means of SEM and XRD. The simulation body-fluid solution is utilized for testing the corrosion resistance with the potentiodynamic polarization and the electrochemical impedance test data. Finally, an in vivo testing shows that the MAO-coated AZ31 has good cytocompatibility and anticorrosive properties. Full article
(This article belongs to the Special Issue Plasma Electrolytic Oxidation (PEO) Coatings)
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Graphical abstract
Full article ">Figure 1
<p>Effect of factors on corrosion current density (<span class="html-italic">I</span><sub>corr</sub>) of the coatings.</p> Full article ">Figure 2
<p>SEM-images of the surface (<b>a</b>–<b>c</b>) and cross-section (<b>d</b>–<b>f</b>) of the MAO coatings produced at negative duty cycle of 10% (<b>a</b>,<b>d</b>), 20% (<b>b</b>,<b>e</b>), and 30% (<b>c</b>,<b>f</b>), respectively, for 30 min.</p> Full article ">Figure 3
<p>XRD patterns of oxide coatings formed at negative duty cycle of 10%, 20%, and 30%, respectively, for 30 min.</p> Full article ">Figure 4
<p>Potentiodynamic polarization curve of the MAO coating on the substrate surface formed at negative duty cycle of 10%, 20%, and 30%, respectively, for 30 min in the SBF.</p> Full article ">Figure 5
<p>SEM-images of the surface (<b>a</b>–<b>c</b>) and cross-section (<b>d</b>–<b>f</b>) of the MAO coatings produced at negative duty cycle of 20% for treatment times of 20 min (<b>a</b>,<b>d</b>), 30 min (<b>b</b>,<b>e</b>), and 40 min (<b>c</b>,<b>f</b>).</p> Full article ">Figure 6
<p>XRD patterns of oxide coatings formed at negative duty cycle of 20% for treatment times of 20, 30, and 40 min.</p> Full article ">Figure 7
<p>Potentiodynamic polarization curve of the MAO coating on the substrate surface formed at negative duty cycle of 20% for treatment times of 20, 30, and 40 min in the SBF.</p> Full article ">Figure 8
<p>Corrosion current density of the bare and MAO-coated AZ31 Mg alloy immersed in SBF solution for different times.</p> Full article ">Figure 9
<p>Impedance spectra of bare and MAO-coated AZ31 Mg alloy in the SBF after immersion of 7 days.</p> Full article ">Figure 10
<p>The surgery image of the implantation of the magnesium bone-screw in the femora of a mature rabbit.</p> Full article ">Figure 11
<p>The µCT reconstructed images showing the degradation processes of AZ31 bone-screw (<b>A</b>–<b>C</b>) and MAO coating (<b>D</b>–<b>F</b>) after implantation of 4, 8, and 12 weeks.</p> Full article ">Figure 12
<p>Pathological photographs of the screw/bone interfaces after AZ31 substrate (<b>A</b>–<b>C</b>) and the MAO coating (<b>D</b>–<b>F</b>) implanted in a mature rabbit for 4, 8, and 12 weeks.</p> Full article ">
14 pages, 9311 KiB  
Article
Investigations on Forming Ether Coated Iron Nanoparticle Materials by First-Principle Calculations and Molecular Dynamic Simulations
by Junlei Sun, Shixuan Hui, Pingan Liu, Ruochen Sun and Mengjun Wang
Coatings 2019, 9(6), 395; https://doi.org/10.3390/coatings9060395 - 19 Jun 2019
Cited by 5 | Viewed by 2949
Abstract
The mechanism of coating effects between ether molecules and iron (Fe) nanoparticles was generally estimated using first-principle calculations and molecular dynamic (MD) simulations coupling with Fe (110) crystal layers and sphere models. In the present work, the optimized adsorption site and its energy [...] Read more.
The mechanism of coating effects between ether molecules and iron (Fe) nanoparticles was generally estimated using first-principle calculations and molecular dynamic (MD) simulations coupling with Fe (110) crystal layers and sphere models. In the present work, the optimized adsorption site and its energy were confirmed. The single sphere model in MD simulations was studied for typical adsorption behaviors, and the double sphere model was built to be more focused on the gap impact between two particles. In those obtained results, it is demonstrated that ether molecules were prone to be adsorbed on the long bridge site of the Fe (110) crystal while comparing with other potential sites. Although the coating was not completely uniform at early stages, the formation of ether layer ended up being equilibrated finally. Accompanied with charge transfer, those coated ether molecules exerted much binding force on the shell Fe atoms. Additionally, when free ether molecules were close to the gap between two nanoparticles, they were found to come under double adsorption effects. Although this effect might not be sufficient to keep them adsorbed, the movement of these ether molecules were hindered to some extent. Full article
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<p>Plot of temperature changes for annealing Fe nanoparticle.</p> Full article ">Figure 2
<p>Top view of Fe (110) supercell and four different adsorption sites.</p> Full article ">Figure 3
<p>The chemical configuration of ether molecule with its labelled atoms.</p> Full article ">Figure 4
<p>Snapshot of an ether molecule adsorbed on a long bridge site of Fe (110) supercell.</p> Full article ">Figure 5
<p>Snapshots of single sphere model at (<b>a</b>) 0 ps, (<b>b</b>) 8 ps, (<b>c</b>) 16 ps and (<b>d</b>) 24 ps.</p> Full article ">Figure 6
<p>Decrease of potential energy as a function of time for single sphere model.</p> Full article ">Figure 7
<p>The number of ether molecules adsorbed on single sphere model.</p> Full article ">Figure 8
<p>Snapshot of Fe nanoparticle colored by multiple of electron charge at 1 ns.</p> Full article ">Figure 9
<p>Radial displacement distribution of Fe nanoparticle at 200 ps.</p> Full article ">Figure 10
<p>Plot of maximum displacements of Fe nanoparticle as a function of time.</p> Full article ">Figure 11
<p>The quantity of desorbed ether molecules in 10 filtering cycles and the final configuration.</p> Full article ">Figure 12
<p>Snapshots of double sphere model at (<b>a</b>) 0 ps, (<b>b</b>) 2 ps, (<b>c</b>) 4 ps, (<b>d</b>) 6 ps, (<b>e</b>) 8 ps, and (<b>f</b>) 15 ps.</p> Full article ">Figure 13
<p>The number of ether molecules adsorbed on double sphere model.</p> Full article ">Figure 14
<p>Decrease of potential energy as a function of time for double sphere model.</p> Full article ">Figure 15
<p>Adsorption curves and snapshot of different regions of double sphere model.</p> Full article ">Figure 16
<p>Displacement distribution of sliced double sphere model (unit: Å).</p> Full article ">Figure 17
<p>Kinetic energy distribution of sliced double sphere model (unit: kcal/mole).</p> Full article ">
15 pages, 3062 KiB  
Article
Surface Functionalization of Bioactive Glasses with Polyphenols from Padina pavonica Algae and In Situ Reduction of Silver Ions: Physico-Chemical Characterization and Biological Response
by Asmaa Sayed Abdelgeliel, Sara Ferraris, Andrea Cochis, Sara Vitalini, Marcello Iriti, Hiba Mohammed, Ajay Kumar, Martina Cazzola, Wesam M. Salem, Enrica Verné, Silvia Spriano and Lia Rimondini
Coatings 2019, 9(6), 394; https://doi.org/10.3390/coatings9060394 - 19 Jun 2019
Cited by 22 | Viewed by 4391
Abstract
Bioactive glasses (BGs) are attractive materials for bone replacement due to their tailorable chemical composition that is able to promote bone healing and repair. Accordingly, many attempts have been introduced to further improve BGs’ biological behavior and to protect them from bacterial infection, [...] Read more.
Bioactive glasses (BGs) are attractive materials for bone replacement due to their tailorable chemical composition that is able to promote bone healing and repair. Accordingly, many attempts have been introduced to further improve BGs’ biological behavior and to protect them from bacterial infection, which is nowadays the primary reason for implant failure. Polyphenols from natural products have been proposed as a novel source of antibacterial agents, whereas silver is a well-known antibacterial agent largely employed due to its broad-ranged activity. Based on these premises, the surface of a bioactive glass (CEL2) was functionalized with polyphenols extracted from the Egyptian algae Padina pavonica and enriched with silver nanoparticles (AgNPs) using an in situ reduction technique only using algae extract. We analyzed the composite’s morphological and physical-chemical characteristics using FE-SEM, EDS, XPS and Folin–Ciocalteau; all analyses confirmed that both algae polyphenols and AgNPs were successfully loaded together onto the CEL2 surface. Antibacterial analysis revealed that the presence of polyphenols and AgNPs significantly reduced the metabolic activity (>50%) of Staphylococcus aureus biofilm in comparison with bare CEL2 controls. Finally, we verified the composite’s cytocompatibility with human osteoblasts progenitors that were selected as representative cells for bone healing advancement. Full article
(This article belongs to the Special Issue Surfaces Modification and Analysis for Innovative Biomaterials)
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<p>High resolution XPS spectra of (<b>a</b>,<b>c</b>) carbon (C-region) and (<b>b</b>,<b>d</b>) oxygen (O-region) for bare (CEL2) and <span class="html-italic">P. pavonica</span> extract grafted (CEL2 + pad (1 mg/mL) CEL2 specimens.</p> Full article ">Figure 2
<p>High resolution XPS spectrum of the Ag region for CEL2 + pad (1 mg/mL) +Ag.</p> Full article ">Figure 3
<p>FE-SEM observations of CEL2 + pad (1 mg/mL) + Ag. (<b>a</b>) Low magnification overview of surface; (<b>b</b>–<b>d</b>) Ag precipitates as dendrimeric nanoflowers and holes on the glass surface due to reaction in the functionalization media (higher magnification).</p> Full article ">Figure 4
<p>EDS analyses on CEL2 + pad (1 mg/mL) + Ag.</p> Full article ">Figure 5
<p>Specimens’ antibacterial activity in direct contact with <span class="html-italic">S. aureus</span> biofilm for (<b>a</b>) 24, (<b>b</b>) 48, and (<b>c</b>) 72 h. The doping with algae extract only (CEL2 + pad) was not effective at decreasing bacteria viability (<span class="html-italic">p</span> &gt; 0.05) in comparison with untreated controls (CEL2). The introduction of silver in combination with extract (CEL2 + pad + Ag) produced a decrease in bacteria metabolism that was significant after 24 and 48 h of cultivation (c, <span class="html-italic">p</span> &lt; 0.05, indicated by the §) in comparison to both CEL2 and CEL2 + pad. The effect decreased after 72 h, probably due to saturation. Bars represent means and standard deviations; data are expressed as RFU.</p> Full article ">Figure 6
<p>Specimens’ cytocompatibility in direct contact with hFOB cells for (<b>a</b>) 24, (<b>b</b>) 48, and (<b>c</b>) 72 h. The doping with algae extract only (CEL2 + pad) did not introduce any toxic effect, as results were comparable (<span class="html-italic">p</span> &gt; 0.05) with untreated controls (CEL2). The introduction of silver in combination with extract (CEL2 + pad + Ag) produced a decrease of cells metabolism that was significant after 72 h of cultivation (c, <span class="html-italic">p</span> &lt; 0.05 indicated by the §) in comparison with both CEL2 and CEL2 + pad. (<b>d</b>) Accordingly, cells metabolism decreased during the 72 h. (Bars represent means and standard deviations; data are expressed as RFU.</p> Full article ">
11 pages, 6063 KiB  
Article
Tunable Perfect Narrow-Band Absorber Based on a Metal-Dielectric-Metal Structure
by Qiang Li, Zizheng Li, Xiangjun Xiang, Tongtong Wang, Haigui Yang, Xiaoyi Wang, Yan Gong and Jinsong Gao
Coatings 2019, 9(6), 393; https://doi.org/10.3390/coatings9060393 - 18 Jun 2019
Cited by 23 | Viewed by 4718
Abstract
In this paper, a metal-dielectric-metal structure based on a Fabry–Perot cavity was proposed, which can provide near 100% perfect narrow-band absorption. The lossy ultrathin silver film was used as the top layer spaced by a lossless silicon oxide layer from the bottom silver [...] Read more.
In this paper, a metal-dielectric-metal structure based on a Fabry–Perot cavity was proposed, which can provide near 100% perfect narrow-band absorption. The lossy ultrathin silver film was used as the top layer spaced by a lossless silicon oxide layer from the bottom silver mirror. We demonstrated a narrow bandwidth of 20 nm with 99.37% maximum absorption and the absorption peaks can be tuned by altering the thickness of the middle SiO2 layer. In addition, we established a deep understanding of the physics mechanism, which provides a new perspective in designing such a narrow-band perfect absorber. The proposed absorber can be easily fabricated by the mature thin film technology independent of any nano structure, which make it an appropriate candidate for photodetectors, sensing, and spectroscopy. Full article
(This article belongs to the Special Issue Thin Films for Energy Harvesting, Conversion, and Storage)
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<p>(<b>a</b>) Schematic diagram of the MDM structure perfect absorber. The thickness of the three layers are <span class="html-italic">t</span>, <span class="html-italic">d</span>, and <span class="html-italic">h</span>, respectively; (<b>b</b>) The relationship between the absorption and the SiO<sub>2</sub> thickness <span class="html-italic">d</span> by FDTD simulation when the thickness of the top Ag layer is 30 nm; (<b>c</b>) Simulated absorption spectra extracted from <a href="#coatings-09-00393-f001" class="html-fig">Figure 1</a>b when <span class="html-italic">d</span> is 600 nm; (<b>d</b>) Electric field distribution in the SiO<sub>2</sub> cavity at the absorption peaks from <span class="html-italic">m</span> = 1 to <span class="html-italic">m</span> = 6.</p> Full article ">Figure 2
<p>(<b>a</b>,<b>b</b>) The calculated reflection and absorption of five SiO<sub>2</sub> thickness <span class="html-italic">d</span> (90, 110, 130, 160, and 180 nm) by the TMM algorithm. (<b>c</b>) The relationship of resonance wavelength and the SiO<sub>2</sub> thickness <span class="html-italic">d</span> calculated by the TMM algorithm; (<b>d</b>) The five colorful solid lines represent the simulated absorption spectra by the FDTD algorithm when the thickness of the SiO<sub>2</sub> <span class="html-italic">d</span> are 90, 110, 130, 160, and 180 nm, respectively.</p> Full article ">Figure 3
<p>The simulated absorption by the FDTD algorithm. (<b>a</b>) The absorption curves when a single Ag layer coated on the glass substrate with varying thickness from 0–70 nm; (<b>b</b>) The absorption curves taken from <a href="#coatings-09-00393-f003" class="html-fig">Figure 3</a>a when the thickness of the top Ag layer is 10, 30 and 50 nm; (<b>c</b>) The absorption as a function of wavelength of the MDM structure with a top Ag thickness from 0–70 nm when the middle SiO<sub>2</sub> thickness is fixed at 130 nm; (<b>d</b>) The absorption curves taken from <a href="#coatings-09-00393-f003" class="html-fig">Figure 3</a>c when the thickness of the top Ag layer is 10, 30 and 50 nm.</p> Full article ">Figure 4
<p>(<b>a</b>,<b>b</b>) Simulated E-field intensity distributions by the FDTD algorithm at the resonance wavelength of 534 nm and non-resonance wavelength of 700 nm, respectively. The three layers of the MDM absorber consist of a 30 nm top Ag layer, a 130 nm middle SiO<sub>2</sub> layer, and a 100 nm bottom Ag layer. (<b>c</b>) Simulated E-field distributions as a function of wavelength in the visible region.</p> Full article ">Figure 5
<p>(<b>a</b>) Simulated energy distribution at the 534 nm resonance wavelength when the middle SiO<sub>2</sub> layer is 130 nm; and (<b>b</b>) the Ohmic loss calculated by Equation (1) at the resonance wavelength and non-resonance wavelength.</p> Full article ">Figure 6
<p>The optical constant of (<b>a</b>) Ag and (<b>b</b>) SiO<sub>2</sub> from the results measured by a spectroscopic ellipsometer.</p> Full article ">Figure 7
<p>Simulated and experimental absorption for the 100 nm bottom Ag layer, 600 nm middle SiO<sub>2</sub> layer, and 30 nm top Ag layer.</p> Full article ">Figure 8
<p>(<b>a</b>) Five samples with different SiO<sub>2</sub> thickness: 90, 110, 130, 160, and 180 nm, from left to right; (<b>b</b>) SEM image of the structure showing the Ag and SiO<sub>2</sub> layers; (<b>c</b>) Simulated and experimental reflection and absorption of five samples; The solid lines are the FDTD simulation results, while the dotted lines are the experimental results.</p> Full article ">
21 pages, 8614 KiB  
Article
Machining GX2CrNiMoN26-7-4 DSS Alloy: Wear Analysis of TiAlN and TiCN/Al2O3/TiN Coated Carbide Tools Behavior in Rough End Milling Operations
by Francisco José Gomes Silva, Rui Pedro Martinho, Carlos Martins, Hernâni Lopes and Ronny Miguel Gouveia
Coatings 2019, 9(6), 392; https://doi.org/10.3390/coatings9060392 - 17 Jun 2019
Cited by 28 | Viewed by 5047
Abstract
In the last decade, it has been common to observe a competition between coatings achieved via physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques on cutting tools used in machining processes. The tool’s substrate material can immediately condition the coating process [...] Read more.
In the last decade, it has been common to observe a competition between coatings achieved via physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques on cutting tools used in machining processes. The tool’s substrate material can immediately condition the coating process selection. However, there are also materials capabe of adapting to any of the coating processes. Hence, the capabilities demonstrated by a given coating when created with one technique or another are usually different due to the intrinsic characteristics of each coating process, such as temperature and stress levels. In this work, to study the machining behavior of a super duplex stainless steel, PVD- and CVD-coated tungsten carbide inserts with different coatings were used in order to identify the wear mechanisms that affect each of the coatings and the workpiece’s surface quality, evaluated through different roughness parameters. The vibration level produced throughout the various tests was also registered in an attempt to associate the type of coating or insert failure with the level of vibrations generated in the CNC (Computer Numeric Control) machining spindle. This allowed us to conclude that the tools coated with TiAlN via PVD showed better wear behavior, as well as creating workpiece surfaces with less roughness. Thus, it was clear that this coating presents strong advantages in the machining of the super duplex stainless steel chosen for this work, being an innovative work due to the combination of materials used and the approach in terms of vibration analysis applied to milling. Full article
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<p>(<b>a</b>) Top view of the WC PH7930 micro-grain sintered microstructure (1500×); (<b>b</b>) AlTiN coating + substrate microstructure in cross-section view (1500×) (Courtesy of Palbit).</p> Full article ">Figure 2
<p>(<b>a</b>) Top view of the WC PH5740 micro-grain sintered microstructure (1500×); (<b>b</b>) Al<sub>2</sub>O<sub>3</sub> coating + substrate microstructure in cross-section view (1500×) (Courtesy of Palbit).</p> Full article ">Figure 3
<p>(<b>a</b>) Machining strategy used in all tests; (<b>b</b>) tool holder (<a href="http://www.taegutec.com" target="_blank">www.taegutec.com</a>).</p> Full article ">Figure 4
<p>Image obtained from the video by a high-speed camera, during the experimental tests.</p> Full article ">Figure 5
<p>(<b>a</b>) and (<b>c</b>) flank wear (VB) of PVD PH7930-S1 and PH7930-S2 cutting inserts, respectively; (<b>b</b>) and (<b>d</b>) rake face/land wear (KB) of PVD PH7930-S1 and PH7930-S2 cutting inserts, respectively.</p> Full article ">Figure 6
<p>Vibrations amplitude on PVD coated inserts for the group of tests of (<b>a</b>) PH7930-S1 and (<b>b</b>) PH7930-S2 cutting inserts.</p> Full article ">Figure 7
<p>(<b>a</b>) and (<b>c</b>) Flank wear (VB) of PVD PH7930-L1 and PH7930-L2 cutting inserts, respectively; (<b>b</b>) and (<b>d</b>) rake face/land wear (KB) of PVD PH7930-L1 and PH7930-L2 cutting inserts, respectively.</p> Full article ">Figure 8
<p>EDS spectrum of the Zone 1 pointed out in the SEM image of <a href="#coatings-09-00392-f007" class="html-fig">Figure 7</a>a.</p> Full article ">Figure 9
<p>Vibrations amplitude on PVD AlTiN coated inserts for the group of tests corresponding to (<b>a</b>) PH7930-L1 and (<b>b</b>) PH7930-L2 cutting tests.</p> Full article ">Figure 10
<p>(<b>a</b>,<b>c</b>) flank wear (VB) of CVD TiN/TiCN/Al<sub>2</sub>O<sub>3</sub> PH5740-S1 and PH5740-S2 cutting inserts, respectively; (<b>b</b>,<b>d</b>) crater wear (KB) of CVD TiN/TiCN/Al<sub>2</sub>O<sub>3</sub> PH5740-S1 and PH5740-S2 cutting inserts, respectively.</p> Full article ">Figure 10 Cont.
<p>(<b>a</b>,<b>c</b>) flank wear (VB) of CVD TiN/TiCN/Al<sub>2</sub>O<sub>3</sub> PH5740-S1 and PH5740-S2 cutting inserts, respectively; (<b>b</b>,<b>d</b>) crater wear (KB) of CVD TiN/TiCN/Al<sub>2</sub>O<sub>3</sub> PH5740-S1 and PH5740-S2 cutting inserts, respectively.</p> Full article ">Figure 11
<p>Vibrations amplitude corresponding to CVD TiN/TiCN/Al<sub>2</sub>O<sub>3</sub> coated inserts for two of the machining tests (<b>a</b>) PH5740-S1 and (<b>b</b>) PH5740-S2 cutting inserts.</p> Full article ">Figure 12
<p>(<b>a</b>) and (<b>c</b>) flank wear (VB) of CVD PH5740-L1 and PH5740-L2 cutting inserts, respectively; (<b>b</b>) and (<b>d</b>) crater wear (KB) of CVD PH5740-L1 and PH5740-L2 cutting inserts, respectively.</p> Full article ">Figure 12 Cont.
<p>(<b>a</b>) and (<b>c</b>) flank wear (VB) of CVD PH5740-L1 and PH5740-L2 cutting inserts, respectively; (<b>b</b>) and (<b>d</b>) crater wear (KB) of CVD PH5740-L1 and PH5740-L2 cutting inserts, respectively.</p> Full article ">Figure 13
<p>Vibrations amplitude on CVD coated inserts for (<b>a</b>) PH5740-L1 and (<b>b</b>) PH5740-L2 cutting inserts tests.</p> Full article ">Figure 14
<p>Chip obtained during the milling trials ((<b>a</b>) and <b>b</b>)).</p> Full article ">Figure 15
<p>SEM images of small fragments retained in the chips. (<b>a</b>) SEM image of the hard fragment of the tool coating encased in the chip; (<b>b</b>) EDS confirmation of the fragment chemical composition.</p> Full article ">
19 pages, 12062 KiB  
Article
Numerical Simulation of Thermal Evolution and Solidification Behavior of Laser Cladding AlSiTiNi Composite Coatings
by Chonggui Li, Chuanming Liu, Shuai Li, Zhe Zhang, Ming Zeng, Feifei Wang, Jinqian Wang and Yajun Guo
Coatings 2019, 9(6), 391; https://doi.org/10.3390/coatings9060391 - 17 Jun 2019
Cited by 24 | Viewed by 3867
Abstract
In order to better understand how a high energy input and a fast cooling rate affect the geometric morphology and microstructure of laser cladding aluminum composite coatings, a three-dimensional (3D) transient finite element model (FEM) has been established to study the temperature field [...] Read more.
In order to better understand how a high energy input and a fast cooling rate affect the geometric morphology and microstructure of laser cladding aluminum composite coatings, a three-dimensional (3D) transient finite element model (FEM) has been established to study the temperature field evolution during laser cladding of AlSiTiNi coatings on a 304 stainless steel substrate. In this model, a planar Gauss heat source and a temperature selection judgment mechanism are used to simulate the melting and solidification process as well as the geometric morphology of the laser cladding coatings. The differences in physical characteristics of the cladding materials before and after melting are considered. The results of thermal simulations, including temperature history, temperature gradient, and solidification rate, of the laser cladding coatings are investigated. Corresponding experiments, conducted using an IPG-YLS-5000 fiber laser, are used to verify the simulation results. The experimental observations agree well with the theoretical predictions, which indicates that the established model is valid. Full article
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<p>Material properties of the AlSiTiNi in the powder state and in the solid state: (<b>a</b>) density; (<b>b</b>) thermal conductivity; and (<b>c</b>) specific heat.</p> Full article ">Figure 1 Cont.
<p>Material properties of the AlSiTiNi in the powder state and in the solid state: (<b>a</b>) density; (<b>b</b>) thermal conductivity; and (<b>c</b>) specific heat.</p> Full article ">Figure 2
<p>Material properties of the 304 stainless steel: (<b>a</b>) density; (<b>b</b>) thermal conductivity; and (<b>c</b>) specific heat.</p> Full article ">Figure 3
<p>Laser processing system for laser cladding: (<b>a</b>) experimental equipment; (<b>b</b>) schematic illustration of the laser cladding process.</p> Full article ">Figure 4
<p>Schematic illustration of the planar Gauss heat source model.</p> Full article ">Figure 5
<p>The mesh of the finite element (FE) model: (<b>a</b>) overall view of the model; (<b>b</b>) cross-sectional view of the model.</p> Full article ">Figure 6
<p>A schematic illustration of the laser cladding process: (<b>a</b>) initial stage of laser cladding; (<b>b</b>) the molten pool formation and temperature transfer stage; (<b>c</b>) the molten pool solidification and coating formation stage; and (<b>d</b>) the laser cladding process in the numerical simulation.</p> Full article ">Figure 6 Cont.
<p>A schematic illustration of the laser cladding process: (<b>a</b>) initial stage of laser cladding; (<b>b</b>) the molten pool formation and temperature transfer stage; (<b>c</b>) the molten pool solidification and coating formation stage; and (<b>d</b>) the laser cladding process in the numerical simulation.</p> Full article ">Figure 7
<p>The temperature distribution of the laser overlapping process at a laser power of 1500 W and a scanning speed of 0.01 m/s: (<b>a</b>) 0 s; (<b>b</b>) 0.1 s; (<b>c</b>) 1.5 s; (<b>d</b>) 3 s; (<b>e</b>) 6 s; and (<b>f</b>) 56 s.</p> Full article ">Figure 7 Cont.
<p>The temperature distribution of the laser overlapping process at a laser power of 1500 W and a scanning speed of 0.01 m/s: (<b>a</b>) 0 s; (<b>b</b>) 0.1 s; (<b>c</b>) 1.5 s; (<b>d</b>) 3 s; (<b>e</b>) 6 s; and (<b>f</b>) 56 s.</p> Full article ">Figure 8
<p>Time-history temperature curves of the multi-track laser cladding process at a laser power of 1500 W and a scanning speed of 0.01 m/s.</p> Full article ">Figure 9
<p>Diagram of the change in width of the cladding layer during the multi-track laser cladding process: (<b>a</b>) the overall morphology of multi-track laser cladding; (<b>b</b>) the rear of the first cladding layer; (<b>c</b>) the front of the first cladding layer; (<b>d</b>) the rear of the second cladding layer; and (<b>e</b>) the front of the second cladding layer.</p> Full article ">Figure 10
<p>The temperature field distribution of single-track laser cladding at a laser power of 1500 W: (<b>a</b>) 0.005 m/s, 3 s; (<b>b</b>) 0.01 m/s, 1.5 s; and (<b>c</b>) 0.015 m/s, 1 s.</p> Full article ">Figure 11
<p>The surface temperature monitoring point of the molten pool at different scanning speeds: (<b>a</b>) 0.005 m/s, 1500 W, 3 s; (<b>b</b>) 0.01 m/s, 1500 W, 1.5 s; (<b>c</b>) 0.015 m/s, 1500 W, 1 s; and (<b>d</b>) the experimental result.</p> Full article ">Figure 12
<p>Time-history temperature curves of the monitoring point in the width direction of the molten pool: (<b>a</b>) 0.005 m/s, 1500 W, 6 s; (<b>b</b>) 0.01 m/s, 1500 W, 3 s; and (<b>c</b>) 0.015 m/s, 1500 W, 2 s.</p> Full article ">Figure 13
<p>A comparison of the cross-sections between (<b>a</b>) the simulation result and the location of the monitoring points and (<b>b</b>) the experimental result. Reprinted with permission from [<a href="#B14-coatings-09-00391" class="html-bibr">14</a>]; Copyright 2018 Elsevier.</p> Full article ">Figure 14
<p>The time-history curves of the monitoring point in the depth direction of the molten pool: (<b>a</b>) 0.005 m/s, 1500 W; (<b>b</b>) 0.01 m/s, 1500 W.</p> Full article ">Figure 15
<p>A schematic illustration of the molten pool boundary.</p> Full article ">Figure 16
<p>The distribution of <span class="html-italic">G</span>, <span class="html-italic">R</span>, and <span class="html-italic">G</span>/<span class="html-italic">R</span>: (<b>a</b>) <span class="html-italic">G</span> (0.005 m/s); (<b>b</b>) <span class="html-italic">G</span> (0.01 m/s); (<b>c</b>) <span class="html-italic">R</span> (0.005 m/s); (<b>d</b>) <span class="html-italic">R</span> (0.01 m/s); (<b>e</b>) <span class="html-italic">G</span>/<span class="html-italic">R</span> (0.005 m/s); and (<b>f</b>) <span class="html-italic">G</span>/<span class="html-italic">R</span> (0.01 m/s).</p> Full article ">
9 pages, 31674 KiB  
Article
First Principles Study of Gas Molecules Adsorption on Monolayered β-SnSe
by Tianhan Liu, Hongbo Qin, Daoguo Yang and Guoqi Zhang
Coatings 2019, 9(6), 390; https://doi.org/10.3390/coatings9060390 - 17 Jun 2019
Cited by 12 | Viewed by 3701
Abstract
For the purpose of exploring the application of two-dimensional (2D) material in the field of gas sensors, the adsorption properties of gas molecules, CO, CO2, CH2O, O2, NO2, and SO2 on the surface of [...] Read more.
For the purpose of exploring the application of two-dimensional (2D) material in the field of gas sensors, the adsorption properties of gas molecules, CO, CO2, CH2O, O2, NO2, and SO2 on the surface of monolayered tin selenium in β phase (β-SnSe) has been researched by first principles calculation based on density functional theory (DFT). The results indicate that β-SnSe sheet presents weak physisorption for CO and CO2 molecules with small adsorption energy and charge transfers, which show that a β-SnSe sheet is not suitable for sensing CO and CO2. The adsorption behavior of CH2O molecules adsorbed on a β-SnSe monolayer is stronger than that of CO and CO2, revealing that the β-SnSe layer can be applied to detect CH2O as physical sensor. Additionally, O2, NO2, and SO2 are chemically adsorbed on a β-SnSe monolayer with moderate adsorption energy and considerable charge transfers. All related calculations reveal that β-SnSe has a potential application in detecting and catalyzing O2, NO2, and SO2 molecules. Full article
(This article belongs to the Special Issue Multiscale Modeling of Emerging Two-Dimensional (2D) Materials and Devices)
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<p>(<b>a</b>) Structure and initial adsorption sites of the Sn atom’s side of the β-SnSe monolayer are presented in the picture; (<b>b</b>) structure and initial adsorption sites of the Se atom’s side of the β-SnSe monolayer are presented in the picture, and (<b>c</b>) the band structure of the β-SnSe monolayer is shown in the picture.</p> Full article ">Figure 2
<p>The most stable sites of optimized configurations of the adsorbate molecules: (<b>a</b>) CO, (<b>b</b>) CO<sub>2</sub>, (<b>c</b>) CH<sub>2</sub>O, (<b>d</b>) O<sub>2</sub>, (<b>e</b>) NO<sub>2</sub>, and (<b>f</b>) SO<sub>2</sub> adsorbed on a β-SnSe monolayer. The most stable sites are exhibited.</p> Full article ">Figure 3
<p>Total DOSs of the (<b>a</b>) CO, (<b>b</b>) CO<sub>2</sub>, (<b>c</b>) CH<sub>2</sub>O, (<b>d</b>) O<sub>2</sub>, (<b>e</b>) NO<sub>2</sub> and (<b>f</b>) SO<sub>2</sub> on SnSe (black curve), the projected DOS of SnSe (red curve), and the adsorbate molecules (blue curve) for CO, CO<sub>2</sub>, CH<sub>2</sub>O, O<sub>2</sub>, NO<sub>2</sub>, SO<sub>2</sub> on SnSe monolayer. The <span class="html-italic">E</span><sub>f</sub> is set to zero, as illustrated by the black dotted line.</p> Full article ">Figure 4
<p>Band structures of the monolayered β-SnSe with the adsorbate molecules: (<b>a</b>) CO, (<b>b</b>) CO<sub>2</sub>, (<b>c</b>) CH<sub>2</sub>O, (<b>d</b>) O<sub>2</sub>, (<b>e</b>) NO<sub>2</sub>, and (<b>f</b>) SO<sub>2</sub>, respectively. The <span class="html-italic">E</span><sub>f</sub> is set to zero, as presented via the blue dotted line.</p> Full article ">Figure 5
<p>The slice of charge densities for the β-SnSe monolayer with the adsorbate molecules: (<b>a</b>) CO, (<b>b</b>) CO<sub>2</sub>, (<b>c</b>) CH<sub>2</sub>O, (<b>d</b>) O<sub>2</sub>, (<b>e</b>) NO<sub>2</sub>, and (<b>f</b>) SO<sub>2</sub>, respectively. The value of electron densities ranges between 0 and 1.00 e/Å<sup>3</sup>.</p> Full article ">
17 pages, 5224 KiB  
Article
In Vitro Activity Assays of Sputtered HAp Coatings with SiC Addition in Various Simulated Biological Fluids
by Alina Vlădescu, Anca Pârâu, Iulian Pană, Cosmin M. Cotruț, Lidia R. Constantin, Viorel Braic and Diana M. Vrânceanu
Coatings 2019, 9(6), 389; https://doi.org/10.3390/coatings9060389 - 15 Jun 2019
Cited by 22 | Viewed by 4308
Abstract
Considering the requirements of medical implantable devices, it is pointed out that biomaterials should play a more sophisticated, longer-term role in the customization and optimization of the material–tissue interface in order to ensure the best long-term clinical outcomes. The aim of this contribution [...] Read more.
Considering the requirements of medical implantable devices, it is pointed out that biomaterials should play a more sophisticated, longer-term role in the customization and optimization of the material–tissue interface in order to ensure the best long-term clinical outcomes. The aim of this contribution was to assess the performance of silicon carbide–hydroxyapatite in various simulated biological fluids (Dulbecco’s modified Eagle’s medium (DMEM), simulated body fluid (SBF), and phosphate buffer solution (PBS)) through immersion assays for 21 days at 37 ± 0.5 °C and to evaluate the electrochemical behavior. The coatings were prepared on Ti6Al4V alloy substrates by magnetron sputtering method using two cathodes made of hydroxyapatite and silicon carbide (SiC). After immersion assays the coating’s surface was analyzed in terms of morphology, chemical and phase composition, and chemical bonds. According to the electrochemical behavior in the media investigated at 37 ± 0.5 °C, SiC addition inhibits the dissolution of the hydroxyapatite in DMEM acellular media. Furthermore, after adding SiC, the slow degradation of hydroxyapatite in PBS and SBF media as well as biomineralization in DMEM were observed. Full article
(This article belongs to the Special Issue Surface Modification of Medical Implants)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Schematic illustration of the experimental setup and analysis.</p> Full article ">Figure 2
<p>2D, 3D SEM images and energy dispersive spectrometry (EDS) mapping of the coated surfaces after immersion in all three acellular media.</p> Full article ">Figure 3
<p>Apatite mass evolution of the coatings exposed to DMEM, SBF, and PBS.</p> Full article ">Figure 4
<p>X-ray diffraction (XRD) patterns of the coatings before immersion in acellular media (the substrate is an Si wafer; Si identification is based on the ICDD#04-002-0118 standard).</p> Full article ">Figure 5
<p>XRD diffraction patterns of coated surfaces after immersion in DMEM, SBF, and PBS (Ti6Al4V alloy is the substrate).</p> Full article ">Figure 6
<p>FTIR spectra of HAp and HAp + SiC before immersion in acellular media.</p> Full article ">Figure 7
<p>FTIR spectra of the coated surfaces after immersion in DMEM, SBF, and PBS.</p> Full article ">Figure 8
<p>Tafel plots of the coated samples in DMEM, SBF, and PBS acellular media at 37 ± 0.5 °C.</p> Full article ">Figure 9
<p>SEM images, element distribution, and Ca/P ratio of the HAp + SiC coatings after in vitro electrochemical measurements in DMEM, SBF, and PBS.</p> Full article ">
9 pages, 2658 KiB  
Article
Rectifying Characteristics of Thermally Treated Mo/SiC Schottky Contact
by Jeongsoo Hong, Ki Hyun Kim and Kyung Hwan Kim
Coatings 2019, 9(6), 388; https://doi.org/10.3390/coatings9060388 - 15 Jun 2019
Cited by 7 | Viewed by 4121
Abstract
The rectifying characteristics of a Mo/SiC Schottky contact fabricated by facing targets sputtering system were investigated through current–voltage measurement. The Schottky diode parameters were extracted from the forward current–voltage characteristic curve by the Cheung and Cheung method and the Norde method. The as-deposited [...] Read more.
The rectifying characteristics of a Mo/SiC Schottky contact fabricated by facing targets sputtering system were investigated through current–voltage measurement. The Schottky diode parameters were extracted from the forward current–voltage characteristic curve by the Cheung and Cheung method and the Norde method. The as-deposited Mo/SiC Schottky contacts possessed Schottky barrier heights of 1.17 and 1.22 eV, respectively. The Schottky barrier heights of the diodes were decreased to 1.01 and 0.91 eV after annealing at 400 °C for 30 min. The ideality factor was increased from 1.14 and 1.08 to 1.51 and 1.41, respectively. This implies the presence of non-ideal behaviors due to a current transport mechanism other than ideal thermionic emission, and the non-ideal behaviors increased as a result of excessive thermal annealing. In contrast, only a negligible change was observed in the crystallographic characteristics. This result suggests that the reason for the deviation from the ideal rectifying characteristics of the Mo/SiC Schottky contact through the annealing process was the variation in the current transport mechanism, including recombination, tunneling, and/or minority carrier injection. Full article
(This article belongs to the Special Issue Advances in Functional Materials and Devices for Semiconductor and Energy Applications)
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<p>Schematic of the facing targets sputtering system.</p> Full article ">Figure 2
<p>Structure of as-fabricated Mo/SiC Schottky diode.</p> Full article ">Figure 3
<p>Typical forward and reverse <span class="html-italic">J–V</span> characteristic curves of Mo/SiC Schottky contacts with various annealing conditions: (<b>a</b>) <span class="html-italic">J–V</span> characteristic curves; (<b>b</b>) change of forward voltage by annealing temperature and time (current density = 10<sup>−8</sup> A/cm<sup>2</sup>).</p> Full article ">Figure 4
<p>Plots calculated by the Cheung and Cheung method equation for Mo/SiC Schottky contacts: (<b>a</b>) d<span class="html-italic">V</span>/d(ln <span class="html-italic">J</span>) vs. <span class="html-italic">J</span>; (<b>b</b>) <span class="html-italic">H</span>(<span class="html-italic">J</span>) vs. <span class="html-italic">J</span>.</p> Full article ">Figure 5
<p>Norde plots of the Mo/SiC Schottky contacts with various annealing conditions: (<b>a</b>) 0–2.0 V; and (<b>b</b>) 0–0.75 V.</p> Full article ">Figure 6
<p>Summarized plot of the parameters of prepared Schottky diodes using the Cheung and Cheung method and the Norde method: (<b>a</b>) barrier height; (<b>b</b>) Series resistance; and (<b>c</b>) ideality factor.</p> Full article ">Figure 7
<p>XRD patterns of the Mo/SiC Schottky contact.</p> Full article ">
11 pages, 2728 KiB  
Communication
Modifying Plasmonic-Field Enhancement and Resonance Characteristics of Spherical Nanoparticles on Metallic Film: Effects of Faceting Spherical Nanoparticle Morphology
by Vasanthan Devaraj, Hyuk Jeong, Chuntae Kim, Jong-Min Lee and Jin-Woo Oh
Coatings 2019, 9(6), 387; https://doi.org/10.3390/coatings9060387 - 15 Jun 2019
Cited by 16 | Viewed by 6153
Abstract
A three-dimensional finite-difference time-domain study of the plasmonic structure of nanoparticles on metallic film (NPOM) is presented in this work. An introduction to nanoparticle (NP) faceting in the NPOM structure produced a variety of complex transverse cavity modes, which were labeled S11 [...] Read more.
A three-dimensional finite-difference time-domain study of the plasmonic structure of nanoparticles on metallic film (NPOM) is presented in this work. An introduction to nanoparticle (NP) faceting in the NPOM structure produced a variety of complex transverse cavity modes, which were labeled S11 to S13. We observed that the dominant S11 mode resonance could be tuned to the desired wavelength within a broadband range of ~800 nm, with a maximum resonance up to ~1.42 µm, as a function of NP facet width. Despite being tuned at the broad spectral range, the S11 mode demonstrated minimal decrease in its near field enhancement characteristics, which can be advantageous for surface-enhanced spectroscopy applications and device fabrication perspectives. The identification of mode order was interpreted using cross-sectional electric field profiles and three-dimensional surface charge mapping. We realized larger local field enhancement in the order of ~109, even for smaller NP diameters of 50 nm, as function of the NP faceting effect. The number of radial modes were dependent upon the combination of NP diameter and faceting length. We hope that, by exploring the sub-wavelength complex optical properties of the plasmonic structures of NPOM, a variety of exciting applications will be revealed in the fields of sensors, non-linear optics, device engineering/processing, broadband tunable plasmonic devices, near-infrared plasmonics, and surface-enhanced spectroscopy. Full article
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<p>(<b>a</b>) Schematic illustration of NP on a metallic mirror (NPOM) structure. Gold was employed as metal, and the dielectric layer was inserted between NP and the metallic film. Faceting parameter influence on NP morphology is shown in (<b>b</b>), and an example cross-section view is shown in (<b>c</b>). NP diameter changes (%) from a perfect sphere to a hemisphere as a function of the facet “<span class="html-italic">f</span>” parameter is shown in (<b>d</b>).</p> Full article ">Figure 2
<p>(<b>a</b>) Broadband |<span class="html-italic">E</span>/<span class="html-italic">E</span><sub>0</sub>|<sup>4</sup> results for sphere diameter <span class="html-italic">D</span>% modification from 100% to 50% for NP <span class="html-italic">D</span> = 100 nm in NPOM plasmonic nanostructure. Resonance wavelengths (<b>b</b>) and near field intensities (<b>c</b>) for S<sub>11</sub>, S<sub>12</sub>, S<sub>12′</sub> and S<sub>13</sub> modes extracted from <a href="#coatings-09-00387-f002" class="html-fig">Figure 2</a>a. (<b>d</b>) Schematic illustration of NP facet contact shape with a dielectric layer concerning sphere diameter % explaining the reason for the resonance red-shift. The inset figure displays the similarity of the metal–insulator–metal structure.</p> Full article ">Figure 3
<p>Electric field amplitude and 3D surface charge distribution profiles taken from NPOM plasmonic structure with sphere “<span class="html-italic">D</span>” 80% for S<sub>11</sub> (λ = 1171 nm), S<sub>12</sub> (λ = 739 nm), S<sub>12′</sub> (λ = 649 nm) and S<sub>13</sub> (λ = 589 nm) modes. Cross-sectional XZ (<b>a</b>–<b>d</b>) electric field amplitude profiles and related 3D surface charge distributions from NP standalone view (<b>e</b>–<b>h</b>).</p> Full article ">Figure 4
<p>(<b>a</b>–<b>c</b>) Broadband |<span class="html-italic">E</span>/<span class="html-italic">E</span><sub>0</sub>|<sup>4</sup> spectrum for different NP diameters ranging from 50 to 90 nm as function of 100%, 80%, or 50% sphere diameter percentage in NPOM plasmonic structure. (<b>d</b>) Extracted maximum near field enhancement for S<sub>11</sub> mode for different sphere <span class="html-italic">D</span>% from figures (<b>a</b>–<b>c</b>). 3D surface charge distributions for S<sub>11</sub>, S<sub>12</sub>, and S<sub>12′</sub> modes taken from hemispherical NPs with <span class="html-italic">D</span> = 50 nm (<b>e</b>–<b>g</b>).</p> Full article ">Figure 5
<p>Extracted resonance wavelengths for S11 mode (<b>a</b>), S12 mode (<b>b</b>), and S13 mode (<b>c</b>) obtained from broadband |<span class="html-italic">E</span>/<span class="html-italic">E</span><sub>0</sub>|<sup>4</sup> spectrum of <a href="#coatings-09-00387-f004" class="html-fig">Figure 4</a>a–c.</p> Full article ">
51 pages, 6518 KiB  
Review
Pulsed Laser Deposited Films for Microbatteries
by Christian M. Julien and Alain Mauger
Coatings 2019, 9(6), 386; https://doi.org/10.3390/coatings9060386 - 14 Jun 2019
Cited by 45 | Viewed by 7167
Abstract
This review article presents a survey of the literature on pulsed laser deposited thin film materials used in devices for energy storage and conversion, i.e., lithium microbatteries, supercapacitors, and electrochromic displays. Three classes of materials are considered: Positive electrode materials (cathodes), solid electrolytes, [...] Read more.
This review article presents a survey of the literature on pulsed laser deposited thin film materials used in devices for energy storage and conversion, i.e., lithium microbatteries, supercapacitors, and electrochromic displays. Three classes of materials are considered: Positive electrode materials (cathodes), solid electrolytes, and negative electrode materials (anodes). The growth conditions and electrochemical properties are presented for each material and state-of-the-art of lithium microbatteries are also reported. Full article
(This article belongs to the Special Issue Current Research in Pulsed Laser Deposition)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Design principles for lithium microbatteries composed of a lithium film (Li), fast-ion conductor (FIC), mixed ionic-electronic conductor (MIC), current collector(s) (CC), silicon substrate (Si), glass substrate (Sub), and buffer layer (Buf). (<b>a</b>) four-layer design on a conducting substrate and (<b>b</b>) six-layer stack incorporating two metallic current collectors (Reproduced with permission from [<a href="#B25-coatings-09-00386" class="html-bibr">25</a>]. Copyright 2000 Springer).</p> Full article ">Figure 2
<p>The relationship between impurity inclusions and growth conditions of PLD-grown LCO films established from spectroscopic Raman data (Reproduced with permission from [<a href="#B51-coatings-09-00386" class="html-bibr">51</a>]. Copyright 2017 AIP Publishing).</p> Full article ">Figure 3
<p>Schematic representation of the fast-laser ablation growth according to the Li/Co ratio variation of the plume for a stoichiometric (<b>a</b>) and Li-enriched target (<b>b</b>). (Reproduced with permission from [<a href="#B62-coatings-09-00386" class="html-bibr">62</a>]. Copyright 2012 IOP Publishing).</p> Full article ">Figure 4
<p>Electrochemical features of PLD-grown LCO thin films: specific discharge capacity and discharge mid-voltage vs. substrate temperature.</p> Full article ">Figure 5
<p>(<b>a</b>) SEM image cross-section of a Li/amorphous Li<sub>3</sub>PO<sub>4</sub>/LCO thin-film microbatteries. (<b>b</b>) Discharge curves for various current densities in the voltage range of 3.0 to 4.5 V vs. Li<sup>+</sup>/Li. (Reproduced with permission from [<a href="#B88-coatings-09-00386" class="html-bibr">88</a>]. Copyright 2014 Elsevier).</p> Full article ">Figure 6
<p>Phase diagram of microstructure development in PLD LiNi<sub>0.8</sub>Co<sub>0.2</sub>O<sub>2</sub> films as a function of the growth temperature. (Reproduced with permission from [<a href="#B100-coatings-09-00386" class="html-bibr">100</a>]. Copyright 2006 American Chemical Society).</p> Full article ">Figure 7
<p>The specific capacity of LiNi<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>O<sub>2</sub> thin films deposited onto Ni foil, Si wafer, and ITO-coated glass as a function of the substrate temperature.</p> Full article ">Figure 8
<p>(<b>a</b>) SEM images of LiMn<sub>2</sub>O<sub>4</sub> films deposited at <span class="html-italic">T</span><sub>s</sub> = 300 °C and <span class="html-italic">T</span><sub>s</sub> = 600 °C. (<b>b</b>) The grain size of PLD thin films as a function of <span class="html-italic">T</span><sub>s</sub>. (Reproduced with permission from [<a href="#B133-coatings-09-00386" class="html-bibr">133</a>]. Copyright 2007 Springer).</p> Full article ">Figure 9
<p>(<b>a</b>) Surface morphology and (<b>b</b>) cross-sectional picture of PLD-grown LMO thin film deposited on an Si(001) substrate covered by a 0.2 µm SiO<sub>2</sub> layer at 575 °C under a 13 Pa oxygen partial pressure. (Reproduced with permission from [<a href="#B135-coatings-09-00386" class="html-bibr">135</a>]. Copyright 2008 Elsevier).</p> Full article ">Figure 10
<p>Cyclic voltammogram recorded at a 0.5 mV·s<sup>−1</sup> scan rate of a Li/Li<sub>3</sub>PO<sub>4</sub>/LiCoMnO<sub>4</sub> thin film battery. The LiCoMnO<sub>4</sub> film cathode was grown under <span class="html-italic">P</span><sub>O₂</sub> = 100 Pa. (Reproduced with permission from [<a href="#B171-coatings-09-00386" class="html-bibr">171</a>]. Copyright 2014 Elsevier).</p> Full article ">Figure 11
<p>Variation of the grain size in V<sub>2</sub>O<sub>5</sub> thin films as a function of the substrate temperature. (Reproduced with permission from [<a href="#B205-coatings-09-00386" class="html-bibr">205</a>]. Copyright 2005 American Chemical Society).</p> Full article ">Figure 12
<p><span class="html-italic">P</span><sub>O₂</sub> vs. 1000/<span class="html-italic">T</span><sub>s</sub> phase diagram for films of vanadium oxides laser-pulse deposited on silicon substrates. (Reproduced with permission from [<a href="#B213-coatings-09-00386" class="html-bibr">213</a>]. Copyright 2015 AIP Publishing).</p> Full article ">Figure 13
<p>Discharge profiles vs. lithium uptake for Li//V<sub>6</sub>O<sub>13</sub> thin-film microbatteries. Active cathode films were grown with: (<b>a</b>) <span class="html-italic">T</span><sub>s</sub> = 250 °C, as-deposited; (<b>b</b>) <span class="html-italic">T</span><sub>s</sub> = 250 °C, annealed at 300 °C in Ar; (<b>c</b>) <span class="html-italic">T</span><sub>s</sub> = 25 °C, annealed at 300 °C in Ar.</p> Full article ">Figure 14
<p>Temperature of the in-plane ionic for conductivity epitaxial Li<sub>0.33</sub>La<sub>0.56</sub>TiO<sub>3</sub> solid electrolyte thin films (36-nm tick) deposited on NdGaO<sub>3</sub>(110) by PLD at <span class="html-italic">T</span><sub>s</sub> higher than 900 °C under <span class="html-italic">P</span><sub>O₂</sub> = 5 Pa. (Reproduced with permission from [<a href="#B272-coatings-09-00386" class="html-bibr">272</a>]. Copyright 2012 Elsevier).</p> Full article ">Figure 15
<p>SEM cross-sectional images of solid-state thin film lithium batteries, (<b>a</b>) SnO/LVSO/LCO and (<b>b</b>) SnO/LVSO/LMO. (Reproduced with permission from [<a href="#B121-coatings-09-00386" class="html-bibr">121</a>]. Copyright 2006 Elsevier).</p> Full article ">Figure 16
<p>(<b>a</b>) SEM cross-section image of LTO film (410 nm thick) heat treated at 800 °C. (<b>b</b>) Charge–discharge profiles recorded at 20 µA cm<sup>−2</sup> (i.e., ~1.15 C) current density in the voltage range of 1 to 2 V vs. Li<sup>+</sup>/Li of PLD films heated at various temperatures. (Reproduced with permission from [<a href="#B308-coatings-09-00386" class="html-bibr">308</a>]. Copyright 2009 Elsevier).</p> Full article ">Figure 17
<p>Ragone plot (normalized by the active cell area) for lithium thin-film microbatteries fabricated with crystalline LiCoO<sub>2</sub> (black lines), crystalline LiMn<sub>2</sub>O<sub>4</sub> (blue lines), and nanocrystalline Li<span class="html-italic"><sub>x</sub></span>Mn<sub>2−<span class="html-italic">y</span></sub>O<sub>4</sub> (red lines) cathode materials with different thicknesses (in µm).</p> Full article ">
11 pages, 19664 KiB  
Article
Improvement of the Sphericity and the Thickness Uniformity of the Polystyrene (PS) Shell Microsphere during Curing Process
by Xiaotian Han, Hua Zhou, Yifei Zhu, Liangyu Wu, Feng Yao and Cheng Yu
Coatings 2019, 9(6), 385; https://doi.org/10.3390/coatings9060385 - 14 Jun 2019
Cited by 4 | Viewed by 2852
Abstract
To improve the quality of dispersed polystyrene (PS) compound droplets, a new random rotating curing system is designed. In addition, the qualities of the curing products of the PS compound droplets of this new system are compared with those of the traditional curing [...] Read more.
To improve the quality of dispersed polystyrene (PS) compound droplets, a new random rotating curing system is designed. In addition, the qualities of the curing products of the PS compound droplets of this new system are compared with those of the traditional curing system with a constant rotating speed, so as to verify the effectiveness of the new system on the quality improvement of the PS compound droplets. The effect of the liquid level, rotation rate and the density difference on the curing process is also analyzed to reveal the mechanism of the curing process in a rotating flow field. The results indicate that, in the new rotating curing system, the disturbance of the fluid increases the deformation recovery ability of the compound droplets. Furthermore, the vortex with different directions in the external flow fields, make the compound droplets spin in many directions, which improves the spheroidization and concentricity of the compound droplets. Compared with using the traditional rotating curing system, when utilizing the random rotating curing system, the sensitivity of the microspheres’ quality to the density mismatch between the phases is smaller, and the sphericity and the thickness uniformity of the polystyrene (PS) microsphere increase by 10.2% and 4.5%, respectively. In addition, there is an optimal rotation rate for the random rotating curing device, which can optimize the survival rate and quality of the hollow microspheres. Full article
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<p>Schematic diagram of the preparation system.</p> Full article ">Figure 2
<p>Schematic diagram of the curing system. (<b>a</b>) In the traditional curing system, the container rotates in one direction around the center shaft. The lengths of the container are <span class="html-italic">D</span> and <span class="html-italic">L</span>, respectively, and the liquid level is <span class="html-italic">H</span>; (<b>b</b>) In the random rotating curing system, the rotation of the container is controlled by the four axis ball grinding apparatus ①, ②, ③ and ④.</p> Full article ">Figure 3
<p>Diagrammatic sketch of the switch combination of the rotating shaft: ω+ and ω- mean the forward rotation and backward rotation. (<b>a</b>) theoretical random rotation; (<b>b</b>) practical random rotation.</p> Full article ">Figure 4
<p>Simulation diagram of the motion trajectories. (<b>a</b>) Combination 1; (<b>b</b>) Total combination.</p> Full article ">Figure 5
<p>Schematic of the measurement of the wall thickness and the sphericity of the PS microsphere by X-ray in one direction: (<b>a</b>) original X-ray image, (<b>b</b>) binary image, and (<b>c</b>) fitted inner and outer profiles of (<b>b</b>).</p> Full article ">Figure 6
<p>The effects of the rotation rate and liquid level on the quality of the hollow microspheres. (<b>a</b>) Uniformity of wall thickness; (<b>b</b>) Sphericity.</p> Full article ">Figure 7
<p>Schematic diagram of the three curing modes. (<b>a</b>) Mode 1; (<b>b</b>) Mode 2; (<b>c</b>) Mode 3.</p> Full article ">Figure 8
<p>Effect of the curing modes on the sphericity. (<b>a</b>) Δ<span class="html-italic">ρ</span> = 0.0068 g/cm<sup>3</sup>; (<b>b</b>) Δ<span class="html-italic">ρ</span> = 0.0044 g/cm<sup>3</sup>; (<b>c</b>) Δ<span class="html-italic">ρ</span> = 0.0004 g/cm<sup>3</sup>.</p> Full article ">Figure 9
<p>Effect of the curing modes on the thickness uniformity. (<b>a</b>) Δ<span class="html-italic">ρ</span> = 0.0068 g/cm<sup>3</sup>; (<b>b</b>) Δ<span class="html-italic">ρ</span> = 0.0044 g/cm<sup>3</sup>; (<b>c</b>) Δ<span class="html-italic">ρ</span> = 0.0004 g/cm<sup>3</sup>.</p> Full article ">Figure 10
<p>Hollow microspheres cured by different curing modes. (<b>a</b>) Mode 1; (<b>b</b>) Mode 2; (<b>c</b>) Mode 3.</p> Full article ">Figure 11
<p>Merit factor of the microsphere for different modes.</p> Full article ">Figure 12
<p>The effect of the rotation rate on the survival rate of the microspheres.</p> Full article ">Figure 13
<p>Effect of the rotation rate on the sphericity and thickness uniformity of the microspheres. (<b>a</b>) sphericity; (<b>b</b>) uniformity of wall thickness.</p> Full article ">Figure 14
<p>Effect of the rotation rate on the comprehensive quality factor of the microspheres.</p> Full article ">
22 pages, 3939 KiB  
Review
Crumb Rubber Modifier in Road Asphalt Pavements: State of the Art and Statistics
by Sara Bressi, Nicholas Fiorentini, Jiandong Huang and Massimo Losa
Coatings 2019, 9(6), 384; https://doi.org/10.3390/coatings9060384 - 13 Jun 2019
Cited by 128 | Viewed by 11086
Abstract
Tire rubber recycling for civil engineering applications and products is developing faster, achieving increasingly higher levels of maturation. The improvements in the material circle, where crumb rubber, generated as a by-product of the tire rubber making process, becomes the resource used for the [...] Read more.
Tire rubber recycling for civil engineering applications and products is developing faster, achieving increasingly higher levels of maturation. The improvements in the material circle, where crumb rubber, generated as a by-product of the tire rubber making process, becomes the resource used for the construction of road asphalt pavement, is absolutely necessary for increasing the sustainability of the entire supply chain. The paper reports the results of an accurate data analysis derived from an extensive literature review of existing processes, technologies, and materials within construction of infrastructure. The current position, the direction, and rate of progress of the scientific efforts towards the reuse and recycling of tire rubber worldwide have been shown. Furthermore, an in-depth analysis of a set of important properties of Crumb Rubber Modified Asphalt has been carried out—fabrication parameters, standard properties, high and low-temperature performance, and rheological properties. Statistics over a sample of selected publications have been presented to understand the main processes adopted, rubber particle size, temperatures, and possible further modifications of crumb rubber modified binder. Full article
(This article belongs to the Collection Pavement Surface Coatings)
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<p>Principal materials, processes, technologies, and products for the use of reclaimed rubber in road materials. Note: Greenbook (2006) proposes three types of production processes: (i) wet process; (ii) dry process; (iii) terminal blend process.</p> Full article ">Figure 2
<p>Number of publications per year on the use of crumb rubber in engineering construction.</p> Full article ">Figure 3
<p>Color-scale map representing the scientific interest as the number of publications from the 1970s up until 2017 for each Country.</p> Full article ">Figure 4
<p>Percentage of publications funded per country.</p> Full article ">Figure 5
<p>Most common types and percentages of (<b>a</b>) rubber content, (<b>b</b>) maximum size, (<b>c</b>) base bitumen penetration, (<b>d</b>) mixing time, (<b>e</b>) temperature, and (<b>f</b>) shear mix.</p> Full article ">Figure 5 Cont.
<p>Most common types and percentages of (<b>a</b>) rubber content, (<b>b</b>) maximum size, (<b>c</b>) base bitumen penetration, (<b>d</b>) mixing time, (<b>e</b>) temperature, and (<b>f</b>) shear mix.</p> Full article ">Figure 6
<p>(<b>a</b>) Probability density function and (<b>b</b>) cumulative distribution function of the rubber particle size.</p> Full article ">Figure 7
<p>(<b>a</b>) Low and (<b>b</b>) high temperature PG of the bitumen base used for CR modification.</p> Full article ">Figure 8
<p>(<b>a</b>) Number of publications where the results report a higher value for the analyzed characteristic of different CRM binders compared to the traditional binder, and (<b>b</b>) number of publications reporting a lower value for the considered characteristics for CRM binders compared to the traditional binder. Note that in <a href="#coatings-09-00384-f008" class="html-fig">Figure 8</a>b, the viscosity is not present because in all the results of the papers analyzed, the addition of the rubber always increases the viscosity of the binder.</p> Full article ">Figure 9
<p>(<b>a</b>) Number of publications where the results report a higher value of the analyzed characteristic of AR compared to other technologies (AR+WMA, Traditional, CR+SBS, CR + SBS + sulfur), and (<b>b</b>) number of the publications reporting a lower value of the considered characteristics for AR binder compared to the other technologies (TB, traditional, CRM+RAP, RAP, CR + SBS + sulfur).</p> Full article ">Figure 10
<p>Number of publications where the results report a higher value of the analyzed characteristic of CRM binders (AR, TB, CR + SBS and AR + WMA) compared to the traditional binder.</p> Full article ">Figure 11
<p>Comparison of rheological properties: (<b>a</b>) the number of studies reporting a higher value of the complex modulus for each CRM binder compared to traditional binder; and (<b>b</b>) the number of studies reporting a lower value of the phase angle for each CRM binder compared to the traditional binder.</p> Full article ">
14 pages, 8182 KiB  
Article
Degradation Behaviour of Mg0.6Ca and Mg0.6Ca2Ag Alloys with Bioactive Plasma Electrolytic Oxidation Coatings
by Lara Moreno, Marta Mohedano, Beatriz Mingo, Raul Arrabal and Endzhe Matykina
Coatings 2019, 9(6), 383; https://doi.org/10.3390/coatings9060383 - 13 Jun 2019
Cited by 15 | Viewed by 4507
Abstract
Bioactive Plasma Electrolytic Oxidation (PEO) coatings enriched in Ca, P and F were developed on Mg0.6Ca and Mg0.6Ca2Ag alloys with the aim to impede their fast degradation rate. Different characterization techniques (SEM, TEM, EDX, SKPFM, XRD) were used to analyze the surface characteristics [...] Read more.
Bioactive Plasma Electrolytic Oxidation (PEO) coatings enriched in Ca, P and F were developed on Mg0.6Ca and Mg0.6Ca2Ag alloys with the aim to impede their fast degradation rate. Different characterization techniques (SEM, TEM, EDX, SKPFM, XRD) were used to analyze the surface characteristics and chemical composition of the bulk and/or coated materials. The corrosion behaviour was evaluated using hydrogen evolution measurements in Simulated Body Fluid (SBF) at 37 °C for up to 60 days of immersion. PEO-coated Mg0.6Ca showed a 2–3-fold improved corrosion resistance compared with the bulk alloy, which was more relevant to the initial 4 weeks of the degradation process. In the case of the Mg0.6Ag2Ag alloy, the obtained corrosion rates were very high for both non-coated and PEO-coated specimens, which would compromise their application as resorbable implants. The amount of F− ions released from PEO-coated Mg0.6Ca during 24 h of immersion in 0.9% NaCl was also measured due to the importance of F− in antibacterial processes, yielding 33.7 μg/cm2, which is well within the daily recommended limit of F− consumption. Full article
(This article belongs to the Special Issue Plasma Electrolytic Oxidation (PEO) Coatings)
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<p>Backscattered electron micrographs of the studied alloys: (<b>a</b>,<b>b</b>) Mg0.6Ca and (<b>c</b>,<b>d</b>) Mg0.6Ca2Ag.</p> Full article ">Figure 2
<p>Transmission electron micrographs of the Mg0.6Ca alloy with locations of EDS analysis: (<b>a</b>) Mg0.6Ca 0.5 μm and (<b>b</b>) Mg0.6Ca 0.5 nm.</p> Full article ">Figure 3
<p>Transmission electron micrographs of the Mg0.6Ca2Ag alloy with locations of EDS analysis. (<b>a</b>) Mg0.6Ca2Ag 0.5 μm and (<b>b</b>) Mg0.6Ca2Ag 50 nm.</p> Full article ">Figure 4
<p>SEM backscattered images (<b>a</b>,<b>d</b>), surface potential maps (<b>b</b>,<b>e</b>) and potential profile (<b>c</b>,<b>f</b>) in selected areas of the Mg0.6Ca alloy.</p> Full article ">Figure 5
<p>SEM backscattered image (<b>a</b>), surface potential maps (<b>b</b>) and potential profile (<b>c</b>) in selected areas of the Mg0.6Ca2Ag alloy.</p> Full article ">Figure 6
<p>Backscattered electron micrographs of coating surface morphologies and cross-sections after corrosion of Mg0.6Ca/PEO (<b>a</b>,<b>c</b>,<b>e</b>) and PEO-Mg0.6Ca2Ag (<b>b</b>,<b>d</b>,<b>f</b>).</p> Full article ">Figure 7
<p>XDR patterns from bulk material and PEO coatings.</p> Full article ">Figure 8
<p>(<b>a</b>) Hydrogen volume and (<b>b</b>) hydrogen evolution rate of Mg0.6Ca and Mg0.6Ca/PEO after 60 days of immersion in m-SBF.</p> Full article ">Figure 9
<p>Hydrogen volume for Mg0.6Ca2Ag and Mg0.6Ca2Ag/PEO after 4 days of immersion in m-SBF.</p> Full article ">Figure 10
<p>3D macrograph of (<b>a</b>) Mg0.6Ca, (<b>b</b>) Mg0.6Ca/PEO after 60 days, (<b>c</b>) Mg0.6Ca2Ag and (<b>d</b>) Mg0.6Ca2Ag/PEO after 4 days of immersion in m-SBF.</p> Full article ">Figure 11
<p>Cross-section before corrosion (<b>a</b>) Mg0.6Ca, (<b>b</b>) Mg0.6Ca/PEO after 60 days and (<b>c</b>) Mg0.6Ca2Ag and (<b>d</b>) Mg0.6Ca2Ag/PEO after 4 days of immersion in SBF.</p> Full article ">Figure 12
<p>Schematic diagram of corrosion attack at the grain boundary and loss of grains (labeled with letters).</p> Full article ">Figure 13
<p>Fluoride ions released of PEO coating for 120 min.</p> Full article ">
15 pages, 5038 KiB  
Article
Plasmonic Nanoparticles and Island Films for Solar Energy Harvesting: A Comparative Study of Cu, Al, Ag and Au Performance
by Ivana Fabijanić, Vesna Janicki, Josep Ferré-Borrull, Matej Bubaš, Vesna Blažek Bregović, Lluis F. Marsal and Jordi Sancho-Parramon
Coatings 2019, 9(6), 382; https://doi.org/10.3390/coatings9060382 - 13 Jun 2019
Cited by 17 | Viewed by 4746
Abstract
Alternative materials that can potentially replace Au and Ag in plasmonics and broaden its application potential have been actively investigated over the last decade. Cu and Al have been usually overlooked as plasmonic material candidates because they are prone to oxidisation. In this [...] Read more.
Alternative materials that can potentially replace Au and Ag in plasmonics and broaden its application potential have been actively investigated over the last decade. Cu and Al have been usually overlooked as plasmonic material candidates because they are prone to oxidisation. In this work the plasmonic performance of Cu and Al is investigated using numerical simulations of different nanostructures (spheres, cubes, rods and particle dimers) and taking into account the presence of oxidisation. It is shown that geometry can play a dominant role over material properties and the performance of Cu and Al becomes comparable to that of Ag and Au for systems of non-spherical particles and strong electromagnetic coupling among particles. This observation is experimentally confirmed by the fabrication and characterisation of Cu and Al metal island films. Optical characterisation of the samples reveals a comparable performance of these metals to that obtained for Ag and Au and suggests that Cu and Al metal island films can offer an efficient low-cost platform for solar energy harvesting, as shown in water vapour generation proof of concept experiments. Full article
(This article belongs to the Special Issue Progress in the Characterization of Metal, Dielectric and Semiconducting Optical Thin Films and Coatings)
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Figure 1

Figure 1
<p>Real (left) and imaginary (right) parts of the dielectric function of Ag, Au, Cu (Reference [<a href="#B18-coatings-09-00382" class="html-bibr">18</a>]) and Al (Reference [<a href="#B6-coatings-09-00382" class="html-bibr">6</a>]) as function of photon energy.</p> Full article ">Figure 2
<p>Absolute value of normalized polarizability (<math display="inline"><semantics> <mrow> <mi>α</mi> <mo>/</mo> <mfenced separators="" open="(" close=")"> <mn>4</mn> <mi>π</mi> <msub> <mi>ϵ</mi> <mn>0</mn> </msub> <msup> <mi>a</mi> <mn>3</mn> </msup> </mfenced> </mrow> </semantics></math>, Equation (<a href="#FD1-coatings-09-00382" class="html-disp-formula">1</a>) for Ag, Au, Al and Cu single particles in the electrostatic dipole limit as function of photon energy and <math display="inline"><semantics> <msub> <mi>ϵ</mi> <mi>h</mi> </msub> </semantics></math>.</p> Full article ">Figure 3
<p>Extinction efficiency for Ag, Au, Al and Cu particles with radius <span class="html-italic">a</span> = 100 nm embedded in water (<math display="inline"><semantics> <msub> <mi>ϵ</mi> <mi>h</mi> </msub> </semantics></math> = 1.77) calculated according Mie theory.</p> Full article ">Figure 4
<p>Extinction efficiency for Ag, Au, Al and Cu semi-cubes with varying shape parameter (<span class="html-italic">S</span>) and constant length of (<span class="html-italic">L</span> = 25 nm) embedded in water (<math display="inline"><semantics> <msub> <mi>ϵ</mi> <mi>h</mi> </msub> </semantics></math> = 1.77).</p> Full article ">Figure 5
<p>Extinction efficiency for Ag, Au, Al and Cu nanocube with side length <span class="html-italic">L</span> = 20 (left) and 200 (right) nm embedded in water (<math display="inline"><semantics> <msub> <mi>ϵ</mi> <mi>h</mi> </msub> </semantics></math> = 1.77).</p> Full article ">Figure 6
<p>Extinction efficiency for Ag, Au, Al and Cu nanorods with varying aspect ratio (<math display="inline"><semantics> <mrow> <mi>A</mi> <mi>R</mi> </mrow> </semantics></math>) and constant hemispherical cap radius (<span class="html-italic">a</span> = 25 nm) embedded in water (<math display="inline"><semantics> <msub> <mi>ϵ</mi> <mi>h</mi> </msub> </semantics></math> = 1.77).</p> Full article ">Figure 7
<p>Scattering efficiency for Ag, Au, Al and Cu dimers (left to right) with radius <span class="html-italic">a</span> = 25 nm embedded in water and varying particle separation. Excitation polarisation is parallel to the dimer axis.</p> Full article ">Figure 8
<p>Electric field intensity enhancement (logarithmic scale) for Ag, Au, Al and Cu dimers (left to right) with radius <span class="html-italic">a</span> = 25 nm embedded in water and interparticle separation of 1 nm. Excitation polarisation is parallel to the dimer axis and the near field map corresponds to the plane defined by the polarisation and propagation directions. Calculations are done at the resonance photon energy.</p> Full article ">Figure 9
<p>Average field enhancement over Cu particle surface with radius <span class="html-italic">a</span> = 25 nm in water assuming different Cu<math display="inline"><semantics> <msub> <mrow/> <mn>2</mn> </msub> </semantics></math>O shell thickness. Left: single particle. Right: particle dimer separated by 2 nm and excited by a plane wave polarized in the dimer axis direction. Note the different ranges for the average field enhancement axis.</p> Full article ">Figure 10
<p>Real (left) and imaginary (right) of the effective dielectric function of fabricated metal island films of 5 nm mass thickness made of Ag, Au, Al and Cu as determined from ellipsometry measurements.</p> Full article ">Figure 11
<p>Left: Normal incidence transmittance of Al<math display="inline"><semantics> <msub> <mrow/> <mn>2</mn> </msub> </semantics></math>O<math display="inline"><semantics> <msub> <mrow/> <mn>3</mn> </msub> </semantics></math> before and after the deposition of 9 nm mass thickness Au and 8 nm mass thickness Cu metal island films. Right: Scanning electron microscopy picture of the Au-coated Al<math display="inline"><semantics> <msub> <mrow/> <mn>2</mn> </msub> </semantics></math>O<math display="inline"><semantics> <msub> <mrow/> <mn>3</mn> </msub> </semantics></math> template.</p> Full article ">
15 pages, 9052 KiB  
Article
Relevance of the Preparation of the Target for PLD on the Magnetic Properties of Films of Iron-Doped Indium Oxide
by Hasan B. Albargi, Marzook S. Alshammari, Kadi Y. Museery, Steve M. Heald, Feng-Xian Jiang, Ahmad M. A. Saeedi, A. Mark Fox and Gillian A. Gehring
Coatings 2019, 9(6), 381; https://doi.org/10.3390/coatings9060381 - 13 Jun 2019
Cited by 4 | Viewed by 3928
Abstract
This paper concerns the importance of the preparation of the targets that may be used for pulsed laser deposition of iron-doped indium oxide films. Targets with a fixed concentration of iron are fabricated from indium oxide and iron metal or one of the [...] Read more.
This paper concerns the importance of the preparation of the targets that may be used for pulsed laser deposition of iron-doped indium oxide films. Targets with a fixed concentration of iron are fabricated from indium oxide and iron metal or one of the oxides of iron, FeO, Fe3O4 and Fe2O3. Films from each target were ablated onto sapphire substrates at the same temperature under different oxygen pressures such that the thickness of the films was kept approximately constant. The films were studied using X-ray diffraction, X-ray absorption (both XANES and EXAFS), optical absorption and magnetic circular dichroism. The magnetic properties were measured with a SQUID magnetometer. At the lowest oxygen pressure, there was evidence that some of the iron ions in the films were in the state Fe2+, rather than Fe3+, and there was also a little metallic iron; these properties were accompanied by a substantial magnetisation. As the amount of the oxygen was increased, the number of defect phases and the saturation magnetisation was reduced and the band gap increased. In each case, we found that the amount of the oxygen that had been included in the target from the precursor added to the effect of adding oxygen in the deposition chamber. It was concluded that the amount of oxygen in the target due to the precursor was an important consideration but not a defining factor in the quality of the films. Full article
(This article belongs to the Special Issue Current Research in Pulsed Laser Deposition)
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Figure 1

Figure 1
<p>XRD data of the Fe-doped In<sub>2</sub>O<sub>3</sub> thin films grown from different oxide precursors at (<b>a</b>) base pressure of 2 × 10<sup>−5</sup> Torr and (<b>b</b>) 2 × 10<sup>−3</sup> Torr. The insets demonstrate the effect of the precursor on the position of the (222) peak.</p> Full article ">Figure 2
<p>K-edge X-ray absorption near edge structure (XANES) spectra of reference compounds of metallic Fe, FeO, Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>2</sub>O<sub>3</sub> and the Fe-doped In<sub>2</sub>O<sub>3</sub> films grown from different precursors at (<b>a</b>) at base pressure of 2 × 10<sup>−5</sup> Torr; where an arrow at 7117 eV indicates an additional absorption and (<b>b</b>) higher partial oxygen pressure of 2 × 10<sup>−3</sup> Torr.</p> Full article ">Figure 3
<p>X-ray absorption fine structure (EXAFS) Fourier transform of Fe<sub>2</sub>O<sub>3</sub> and substitutional Fe<sub>2</sub>O<sub>3</sub>-doped In<sub>2</sub>O<sub>3</sub> deposited at base pressure as reference compounds and the Fe-doped In<sub>2</sub>O<sub>3</sub> films grown from different precursors at (<b>a</b>) base pressure of 2 × 10<sup>−5</sup> Torr and (<b>b</b>) O<sub>2</sub> pressure of 2 × 10<sup>−3</sup> Torr.</p> Full article ">Figure 4
<p>(<b>a</b>) and (<b>b</b>) are respectively the magnetic hysteresis loops measurements at 5 and 300 K for the Fe-doped In<sub>2</sub>O<sub>3</sub> films from different oxide precursors at a base pressure of 2 × 10<sup>−5</sup> Torr, (<b>c</b>) shows the room temperature data for films that were made with Fe metal in the precursor. The diamagnetic and paramagnetic terms have been subtracted from all the data shown here.</p> Full article ">Figure 5
<p>Field cooled (FC) and zero field cooled (ZFC) magnetisation curves of the Fe-doped In<sub>2</sub>O<sub>3</sub> from Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>2</sub>O<sub>3</sub> precursors in (<b>a</b>) and from FeO precursor in (<b>b</b>) where all samples were grown at a base pressure of 2 × 10<sup>−5</sup> Torr.</p> Full article ">Figure 6
<p>Absorption data of Fe-doped In<sub>2</sub>O<sub>3</sub> samples grown from FeO, Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>2</sub>O<sub>3</sub> precursors deposited at a base pressure of 2 × 10<sup>−5</sup> Torr and the two higher oxygen pressures of 2 × 10<sup>−4</sup> Torr and 2 × 10<sup>−3</sup> Torr.</p> Full article ">Figure 7
<p>Magnetic circular dichroism (MCD) spectral shapes of the Fe-doped In<sub>2</sub>O<sub>3</sub> samples deposited from different precursors at (<b>a</b>) base pressure and (<b>b</b>) at 2 × 10<sup>−4</sup> Torr shown with black, red and green symbols for FeO, Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>2</sub>O<sub>3</sub>, respectively and at 2 × 10<sup>−3</sup> Torr with blue, turquoise and pink symbols for FeO, Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>2</sub>O<sub>3</sub>, respectively.</p> Full article ">Figure 8
<p>The dependence of (<b>a</b>) the band gap and (<b>b</b>) the saturation magnetisation on the oxygen pressure.</p> Full article ">
15 pages, 4677 KiB  
Article
The Corrosion Inhibition of AA6082 Aluminium Alloy by Certain Azoles in Chloride Solution: Electrochemistry and Surface Analysis
by Klodian Xhanari and Matjaž Finšgar
Coatings 2019, 9(6), 380; https://doi.org/10.3390/coatings9060380 - 13 Jun 2019
Cited by 23 | Viewed by 4375
Abstract
The corrosion inhibition effect of five azole compounds on the corrosion of an AA6082 aluminium alloy in 5 wt.% NaCl solution at 25 and 50 °C was investigated using weight loss and electrochemical measurements. Only 2-mercaptobenzothiazole (MBT) showed a corrosion inhibition effect at [...] Read more.
The corrosion inhibition effect of five azole compounds on the corrosion of an AA6082 aluminium alloy in 5 wt.% NaCl solution at 25 and 50 °C was investigated using weight loss and electrochemical measurements. Only 2-mercaptobenzothiazole (MBT) showed a corrosion inhibition effect at both temperatures and was further studied in detail, including with the addition of potassium iodide as a possible intensifier. Surface analysis of the MBT surface layer was performed by means of attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry techniques. The hydrophobicity of the MBT surface layer was also investigated. Full article
(This article belongs to the Special Issue Anticorrosion Protection of Nonmetallic and Metallic Coatings)
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Figure 1
<p>Structures of the five azole compounds used in this study.</p> Full article ">Figure 2
<p>The Nyquist plots of the AA6082 aluminium alloy samples immersed at 50 °C in 5 wt.% NaCl solution containing different concentrations of five azole compounds.</p> Full article ">Figure 3
<p>The influence of the immersion time on the open circuit potential values of the AA6082 aluminium alloy samples immersed in 5 wt.% NaCl solution with and without 0.3 mM MBT or a combination of 0.3 mM MBT and 0.1 wt.% KI at 25 °C. The discontinuous parts of the curves indicate the moments when the EIS measurements were performed.</p> Full article ">Figure 4
<p>The measured electrochemical impedance spectroscopy (EIS) spectra (dotted) and the respective fitting (in continuous lines) for the AA6082 aluminium alloy samples immersed for 1–10 h, at 25 °C, in (<b>a</b>–<b>c</b>) 5 wt.% NaCl solution, (<b>d</b>–<b>f</b>) 5 wt.% NaCl solution containing 0.3 mM MBT, and (<b>g</b>–<b>i</b>) 5 wt.% NaCl solution containing 0.3 mM MBT with the addition of 0.1 wt.% KI.</p> Full article ">Figure 4 Cont.
<p>The measured electrochemical impedance spectroscopy (EIS) spectra (dotted) and the respective fitting (in continuous lines) for the AA6082 aluminium alloy samples immersed for 1–10 h, at 25 °C, in (<b>a</b>–<b>c</b>) 5 wt.% NaCl solution, (<b>d</b>–<b>f</b>) 5 wt.% NaCl solution containing 0.3 mM MBT, and (<b>g</b>–<b>i</b>) 5 wt.% NaCl solution containing 0.3 mM MBT with the addition of 0.1 wt.% KI.</p> Full article ">Figure 5
<p>The <span class="html-italic">R</span><sub>Ω</sub>(<span class="html-italic">Q</span><sub>1</sub>(<span class="html-italic">R</span><sub>1</sub>(<span class="html-italic">Q</span><sub>2</sub>(<span class="html-italic">R</span><sub>2</sub>))) equivalent electrical circuit (EEC) model used to fit the EIS response of the AA6082 aluminium alloy samples immersed in 5 wt.% NaCl solution with and without 0.3 mM MBT or a combination of 0.3 mM MBT and 0.1 wt.% KI.</p> Full article ">Figure 6
<p>The variation of <span class="html-italic">R</span><sub>p</sub> values with increasing immersion time for the AA6082 aluminium alloy samples immersed for 1–10 h at 25 °C in 5 wt.% NaCl solution with or without 0.3 mM MBT or 0.3 mM MBT and the addition of either 0.1 or 1.0 wt.% KI.</p> Full article ">Figure 7
<p>Potentiodynamic curves for the AA6082 aluminium alloy samples after 11 h of immersion at 25 °C in 5 wt.% NaCl solution containing 0.3 mM MBT or a combination of 0.3 mM MBT and 0.1 wt.% KI.</p> Full article ">Figure 8
<p>ATR-FTIR spectra of the AA6082 aluminium alloy samples immersed for 31 days in 5 wt.% NaCl solution with the addition of 0.3 mM MBT or a combination of 0.3 mM MBT and 0.1 wt.% KI. The ATR-FTIR spectra of the pure solid MBT is given also for comparison.</p> Full article ">Figure 9
<p>High-resolution (<b>a</b>) S 2<span class="html-italic">p</span> XPS spectra and (<b>b</b>) time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements for the MBT adsorbed on AA6082 aluminium alloy.</p> Full article ">
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