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Materials, Volume 16, Issue 1 (January-1 2023) – 463 articles

Cover Story (view full-size image): This review outlines the main materials used for metal implant manufacturing and some general coating techniques. It focuses on recent trends in the design and performance of biomedical coatings for metallic implants used for orthopedic and dental applications. The ways to improve the bioactive coating performance by incorporating bioactive moieties, such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner, have also been addressed. The influence of the bioactive films on the in vitro behavior of cells cultured on coated implants and in vitro/in vivo performance of the implant systems is underlined. View this paper
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20 pages, 6473 KiB  
Article
Fatigue Life Improvement of Weld Beads with Overlap Defects Using Ultrasonic Peening
by Seung-Hyon Song, Chang-Soon Lee, Tae-Hwan Lim, Auezhan Amanov and In-Sik Cho
Materials 2023, 16(1), 463; https://doi.org/10.3390/ma16010463 - 3 Jan 2023
Cited by 3 | Viewed by 4400
Abstract
Welding defects are common during the production of large welded structures. However, few studies have explored methods of compensating for clear welding defects without resorting to re-welding. Here, an ultrasonic peening method to compensate for the deteriorated mechanical properties of overlap weld defects [...] Read more.
Welding defects are common during the production of large welded structures. However, few studies have explored methods of compensating for clear welding defects without resorting to re-welding. Here, an ultrasonic peening method to compensate for the deteriorated mechanical properties of overlap weld defects without repair welding was studied. We experimentally investigated changes in the mechanical properties of defective welds before and after ultrasonic peening. The weld specimen with an overlap defect contained a large cavity-type defect inside the weld bead, which significantly reduced the fatigue life. When the surface of the defective test piece was peened, the fatigue life of the weld plate was restored, resulting in an equivalent or higher number of cycles to failure, compared to a specimen with a normal weld. The recovery of mechanical properties was attributed to the effect of surface work hardening by ultrasonic peening and the change in stress distribution. Thus, ultrasonic peening could compensate for the deterioration of mechanical properties such as tensile strength, fatigue life, and elongation due to overlap defects, without resorting to repair welding. Full article
(This article belongs to the Special Issue Damage and Mechanical Properties of Materials)
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Figure 1

Figure 1
<p>Weld specifications. Schematics of (<b>a</b>) cut plate for forming butt welds and (<b>b</b>) cross-section of normal weld (<b>top</b>) and overlap weld (<b>bottom</b>); Photographs of (<b>c</b>) normal welded plate and (<b>d</b>) welded plate with overlap defect.</p> Full article ">Figure 2
<p>Ultrasonic peening device. (<b>a</b>) Diagram of an ultrasonic peening device; (<b>b</b>) Photograph of a three-tip ultrasonic peening device.</p> Full article ">Figure 3
<p>Schematic of the tensile and fatigue test specimen obtained from the welded plates.</p> Full article ">Figure 4
<p>Measurement positions on weld specimens. (<b>a</b>) Microhardness measurement positions; (<b>b</b>) Residual stress measurement positions.</p> Full article ">Figure 5
<p>Photographs of overlap-defect weld after ultrasonic peening. (<b>a</b>) Peening surface of the overlap weld; (<b>b</b>) Close-up image of the peening area.</p> Full article ">Figure 6
<p>Microstructures of overlap-defect specimen without peening. (<b>a</b>) Center of the bead; (<b>b</b>) Heat-affected zone (HAZ); (<b>c</b>) Upper part of HAZ. (<b>b</b>) Low- and (<b>a</b>,<b>c</b>) high-magnification.</p> Full article ">Figure 7
<p>Microstructure of peened overlap-defect specimen. (<b>a</b>) Low-magnification optical image of the HAZ; (<b>b</b>) High-magnification optical image of the HAZ; (<b>c</b>) Scanning electron microscopy (SEM) image of the HAZ; (<b>d</b>) SEM image of the weld bead.</p> Full article ">Figure 8
<p>Stress–strain curves of welded specimens with a normal weld, overlap defect, and overlap defect after peening.</p> Full article ">Figure 9
<p>SEM images of the fracture surface of the normal welded specimen. (<b>a</b>) Low-magnification image; (<b>b</b>) High-magnification image; (<b>c</b>) High-magnification image of final fracture area. SEM images of the fracture surface of the overlap-defect welded specimens. (<b>d</b>) Low-magnification image; (<b>e</b>) Fatigue striation region; (<b>f</b>) High-magnification image of fatigue striations.</p> Full article ">Figure 10
<p>Photographs of the fatigue-fractured overlap-defect specimens. (<b>a</b>) Without peening; (<b>b</b>) With peening. SEM images of the fracture surface of the peened overlap-defect specimen. (<b>c</b>) Overall fracture surface; (<b>d</b>) Compressed surface; (<b>e</b>) Fatigue striations; (<b>f</b>) Progress of crack growth; (<b>g</b>) Ductile–brittle surface; (<b>h</b>) High-magnification image of the final fracture region.</p> Full article ">Figure 10 Cont.
<p>Photographs of the fatigue-fractured overlap-defect specimens. (<b>a</b>) Without peening; (<b>b</b>) With peening. SEM images of the fracture surface of the peened overlap-defect specimen. (<b>c</b>) Overall fracture surface; (<b>d</b>) Compressed surface; (<b>e</b>) Fatigue striations; (<b>f</b>) Progress of crack growth; (<b>g</b>) Ductile–brittle surface; (<b>h</b>) High-magnification image of the final fracture region.</p> Full article ">Figure 11
<p>X-ray diffraction patterns of the normal welded specimen.</p> Full article ">Figure 12
<p>Schematic of residual stress generation at overlap defects. (<b>a</b>) Expansion force generated by the defect inside the bead; (<b>b</b>) Residual stress in the overlap-defect specimen; (<b>c</b>) Residual stress on the peened surface of the overlap-defect specimen.</p> Full article ">Figure 13
<p>Residual stress diagrams of the overlap-defect specimen. (<b>a</b>) Heat-affected zone; (<b>b</b>) Upper region of the bead; (<b>c</b>) Middle region of the bead.</p> Full article ">Figure 14
<p>Residual stress diagrams of the peened overlap-defect specimen. (<b>a</b>) Heat-affected zone; (<b>b</b>) Upper region of the bead; (<b>c</b>) Middle region of the bead.</p> Full article ">Figure 14 Cont.
<p>Residual stress diagrams of the peened overlap-defect specimen. (<b>a</b>) Heat-affected zone; (<b>b</b>) Upper region of the bead; (<b>c</b>) Middle region of the bead.</p> Full article ">
19 pages, 2859 KiB  
Article
Adsorption–Desorption Behavior of Hydrogen Sulfide Capture on a Modified Activated Carbon Surface
by Nurul Noramelya Zulkefli, Adam Mohd Izhan Noor Azam, Mohd Shahbudin Masdar and Wan Nor Roslam Wan Isahak
Materials 2023, 16(1), 462; https://doi.org/10.3390/ma16010462 - 3 Jan 2023
Cited by 9 | Viewed by 2943
Abstract
Metal-based adsorbents with varying active phase loadings were synthesized to capture hydrogen sulfide (H2S) from a biogas mimic system. The adsorption–desorption cycles were implemented to ascertain the H2S captured. All prepared adsorbents were evaluated by nitrogen adsorption, Brunauer–Emmett–Teller surface [...] Read more.
Metal-based adsorbents with varying active phase loadings were synthesized to capture hydrogen sulfide (H2S) from a biogas mimic system. The adsorption–desorption cycles were implemented to ascertain the H2S captured. All prepared adsorbents were evaluated by nitrogen adsorption, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy–energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. From the results, modified adsorbents, dual chemical mixture (DCM) and a core–shell (CS) had the highest H2S adsorption performance with a range of 0.92–1.80 mg H2S/g. After several cycles of heat/N2 regeneration, the total H2S adsorption capacity of the DCM adsorbent decreased by 62.1%, whereas the CS adsorbent decreased by only 25%. Meanwhile, the proposed behavioral model for H2S adsorption–desorption was validated effectively using various analyses throughout the three cycles of adsorption–desorption samples. Moreover, as in this case, the ZnAc2/ZnO/CAC_OS adsorbents show outstanding performances with 30 cycles of adsorption–desorption compared to only 12 cycles of ZnAc2/ZnO/CAC_DCM. Thus, this research paper will provide fresh insights into adsorption–desorption behavior through the best adsorbents’ development and the adsorbents’ capability at the highest number of adsorption–desorption cycles. Full article
(This article belongs to the Special Issue Recent Progress in Advanced Adsorption Materials)
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Figure 1
<p>Impregnation step behavior of ZnAc<sub>2</sub>/ZnO/CAC_DCM.</p> Full article ">Figure 2
<p>Impregnation step behavior of ZnAc<sub>2</sub>/ZnO/CAC_OS.</p> Full article ">Figure 3
<p>SEM mapping images of (<b>a</b>) ZnAc<sub>2</sub>/ZnO/CAC_DCM (F) and (<b>b</b>) ZnAc<sub>2</sub>/ZnO/CAC_OS (F) at 2.5K× magnification.</p> Full article ">Figure 4
<p>N<sub>2</sub> adsorption–desorption isotherms of ZnAc<sub>2</sub>/ZnO/CAC_DCM in three H<sub>2</sub>S adsorption–desorption cycles.</p> Full article ">Figure 5
<p>N<sub>2</sub> adsorption–desorption isotherms of ZnAc<sub>2</sub>/ZnO/CAC_OS adsorbents through three H<sub>2</sub>S adsorption–desorption cycles.</p> Full article ">Figure 6
<p>FTIR spectra of ZnAc<sub>2</sub>/ZnO/CAC_DCM through three H<sub>2</sub>S adsorption–desorption cycles.</p> Full article ">Figure 7
<p>FTIR spectra of ZnAc<sub>2</sub>/ZnO/CAC_OS through three H<sub>2</sub>S adsorption–desorption cycles.</p> Full article ">Figure 8
<p>Adsorption–desorption profiles of raw CAC, ZnAc<sub>2</sub>/ZnO/CAC_DCM, and ZnAc<sub>2</sub>/ZnO/CAC_OS in three cycles.</p> Full article ">Figure 9
<p>Maximum H<sub>2</sub>S adsorption–desorption profiles of ZnAc<sub>2</sub>/ZnO/CAC_DCM, ZnAc<sub>2</sub>/ZnO/CAC_OS, and raw CAC.</p> Full article ">
14 pages, 4604 KiB  
Article
Towards Room Temperature Phase Transition of W-Doped VO2 Thin Films Deposited by Pulsed Laser Deposition: Thermochromic, Surface, and Structural Analysis
by Yannick Bleu, Florent Bourquard, Vincent Barnier, Anne-Sophie Loir, Florence Garrelie and Christophe Donnet
Materials 2023, 16(1), 461; https://doi.org/10.3390/ma16010461 - 3 Jan 2023
Cited by 12 | Viewed by 3905
Abstract
Vanadium dioxide (VO2) with an insulator-to-metal (IMT) transition (∼68 °C) is considered a very attractive thermochromic material for smart window applications. Indeed, tailoring and understanding the thermochromic and surface properties at lower temperatures can enable room-temperature applications. The effect of W [...] Read more.
Vanadium dioxide (VO2) with an insulator-to-metal (IMT) transition (∼68 °C) is considered a very attractive thermochromic material for smart window applications. Indeed, tailoring and understanding the thermochromic and surface properties at lower temperatures can enable room-temperature applications. The effect of W doping on the thermochromic, surface, and nanostructure properties of VO2 thin film was investigated in the present proof. W-doped VO2 thin films with different W contents were deposited by pulsed laser deposition (PLD) using V/W (+O2) and V2O5/W multilayers. Rapid thermal annealing at 400–450 °C under oxygen flow was performed to crystallize the as-deposited films. The thermochromic, surface chemistry, structural, and morphological properties of the thin films obtained were investigated. The results showed that the V5+ was more surface sensitive and W distribution was homogeneous in all samples. Moreover, the V2O5 acted as a W diffusion barrier during the annealing stage, whereas the V+O2 environment favored W surface diffusion. The phase transition temperature gradually decreased with increasing W content with a high efficiency of −26 °C per at. % W. For the highest doping concentration of 1.7 at. %, VO2 showed room-temperature transition (26 °C) with high luminous transmittance (62%), indicating great potential for optical applications. Full article
(This article belongs to the Special Issue Structural, Morphological, and Optical Properties of Functional Thin Films)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>a</b>) Hysteresis loops derived from the temperature-dependent transmittance of the undoped and W-doped (A, B, and C) thin films at a wavelength of 1500 nm. (<b>b</b>) The correlation between the phase transition temperature T<sub>t</sub> and W concentration.</p> Full article ">Figure 2
<p>(<b>a</b>) Phase transition temperature (red) and hysteresis width (blue) for undoped and W-doped VO<sub>2</sub> thin films. (<b>b</b>) The corresponding luminous transmittance (T<sub>lum</sub>, orange) and the solar modulation ability (ΔT<sub>sol</sub>, in green) values.</p> Full article ">Figure 3
<p>V 2p and W 4d core-level XPS spectra of (<b>a</b>) W-doped VO<sub>X</sub> as-deposited thin films, and (<b>b</b>) W-doped VO<sub>2</sub> thin films after rapid thermal annealing.</p> Full article ">Figure 4
<p>(<b>a</b>) Fitted ARXPS spectra of V 3p, W 4f, and O 2s core-levels for sample C after thermal annealing, at detection angles of 23° and 68°. (<b>b</b>) Quantification of W based on O 2s, W 4f, and V 3p peaks of the different samples before and after rapid thermal annealing.</p> Full article ">Figure 5
<p>The proportion of W<sup>6+</sup> based on V 3p, W 4f, and O 2s as a function of the ARXPS detection angle for all the samples (<b>a</b>) before thermal annealing and (<b>b</b>) after thermal annealing.</p> Full article ">Figure 6
<p>Fitted ARXPS spectra of V 2p and O 1s core-levels for sample C at detection angles of 23° and 68°, respectively, (<b>a</b>) before thermal annealing and (<b>b</b>) after thermal annealing. The concentration of the V<sup>5+</sup> oxidation state of vanadium was obtained from the fitted spectra of the V 2p electrons as a function of the angle of detection in all the samples, (<b>c</b>) before thermal annealing and (<b>d</b>) after thermal annealing.</p> Full article ">Figure 7
<p>Raman spectra of undoped and W-doped VO<sub>2</sub> (samples A, B, and C) thin films.</p> Full article ">Figure 8
<p>Top-view SEM micrographs of the obtained thin films after rapid thermal annealing (<b>a</b>) VO<sub>2</sub> thin film obtained from V+O<sub>2</sub>. (<b>b</b>) W-doped VO<sub>2</sub> (1.7 at. % W, sample C). (<b>c</b>) VO<sub>2</sub> thin film obtained from V<sub>2</sub>O<sub>5</sub>. (<b>d</b>) W-doped VO<sub>2</sub> thin film (0.7 at. % W, sample B). The inserts correspond to the AFM images.</p> Full article ">
16 pages, 7472 KiB  
Article
The Effect of Non-Measured Points on the Accuracy of the Surface Topography Assessment of Elements 3D Printed Using Selected Additive Technologies
by Paweł Zmarzły, Tomasz Kozior and Damian Gogolewski
Materials 2023, 16(1), 460; https://doi.org/10.3390/ma16010460 - 3 Jan 2023
Cited by 6 | Viewed by 2175
Abstract
The paper presents the results of research aimed at evaluating the surface topography including the analysis of the number of unmeasured points of the samples 3D printed using four additive technologies (i.e., PolyJet Matrix, fused deposition modeling, selective laser sintering, and selective laser [...] Read more.
The paper presents the results of research aimed at evaluating the surface topography including the analysis of the number of unmeasured points of the samples 3D printed using four additive technologies (i.e., PolyJet Matrix, fused deposition modeling, selective laser sintering, and selective laser melting). The samples were made in three variants of location on the printing platform of 3D printers. Measurements of the samples’ surface topography were carried out using a Talysurf CCI Lite optical profilometer and a Talysurf PGI 1230 contact profilometer. The percentage of non-measured points for each sample and the parameters of the surface topography were determined. Then, the non-measured points were complemented and the topography parameters for the corrected surface were recalculated. In addition, to perform comparative measurements, each surface was measured using a contact profilometer Talysurf PGI 1230. Preliminary results of the research showed that the measurement of the surface topography of the samples made using selective laser sintering technology with the Taysurf CCI optical measuring system is very unreliable, as the number of non-measured points for the analyzed samples was higher than 98%. The highest accuracy of optical measurement was obtained for PJM technology and three variants of location on the printing platform of the 3D printer. Full article
(This article belongs to the Special Issue Recent Trends in Roughness Measurement and Data Analysis of Machined Surfaces)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Location of the samples on the 3D printing platform.</p> Full article ">Figure 2
<p>The 3D printers used to 3D print the samples. (<b>a</b>) Connex 350, (<b>b</b>) 3D Dimension 1200es, (<b>c</b>) Formiga P100, (<b>d</b>) Concept laser M2.</p> Full article ">Figure 3
<p>Surface topography of the element 3D printed using SLS technology (Pd = 0°). (<b>a</b>) Talysurf CCI—without after filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 4
<p>Surface topography of the element 3D printed using SLS technology (Pd = 45°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 5
<p>Surface topography of the element 3D printed using SLS technology (Pd = 90°).(<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 6
<p>Surface topography of the element 3D printed using FDM technology (Pd = 0°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 7
<p>Surface topography of the element 3D printed using FDM technology (Pd = 45°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 8
<p>Surface topography of the element 3D printed using FDM technology (Pd = 90°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 9
<p>Surface topography of the element 3D printed using PJM technology (Pd = 0°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 10
<p>Surface topography of the element 3D printed using PJM technology (Pd = 45°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 11
<p>Surface topography of the element 3D printed using PJM technology (Pd = 90°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 12
<p>Surface topography of the element 3D printed using SLM technology (Pd = 0°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 13
<p>Surface topography of the element 3D printed using SLM technology (Pd = 45°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">Figure 14
<p>Surface topography of the element 3D printed using SLM technology (Pd = 90°). (<b>a</b>) Talysurf CCI—without filling non-measured points, (<b>b</b>) Talysurf CCI—after filling non-measured points, (<b>c</b>) Talysurf PGI 1230.</p> Full article ">
12 pages, 1550 KiB  
Article
Effect of Blend Composition on Barrier Properties of Insulating Mats Produced from Local Wool and Waste Bast Fibres
by Anna Kicińska-Jakubowska, Jan Broda, Małgorzata Zimniewska, Marcin Bączek and Jerzy Mańkowski
Materials 2023, 16(1), 459; https://doi.org/10.3390/ma16010459 - 3 Jan 2023
Cited by 6 | Viewed by 1896
Abstract
This paper concerns the management of natural waste fibres. The aim of this research was the production of multifunctional acoustic and thermal insulation materials from natural protein and lignocellulosic fibre wastes, according to a circular bioeconomy. For the manufacture of the materials, local [...] Read more.
This paper concerns the management of natural waste fibres. The aim of this research was the production of multifunctional acoustic and thermal insulation materials from natural protein and lignocellulosic fibre wastes, according to a circular bioeconomy. For the manufacture of the materials, local mountain sheep wool and a mixture of bast fibre waste generated by string production were used. Insulating materials in the form of mats produced by the needle-punching technique with different fibre contents were obtained. The basic parameters of the mats, i.e., the thickness, surface weight and air permeability were determined. To assess barrier properties, sound absorption and noise reduction coefficients, as well as thermal resistance and thermal conductivity, were measured. It was shown that the mats exhibit barrier properties in terms of thermal and acoustic insulation related to the composition of the mat. It was found that mats with a higher content of the bast fibres possess a greater ability to absorb sounds, while mats with higher wool contents exhibit better thermal insulation properties. The produced mats can serve as a good alternative to commonly used acoustic and thermal insulating materials. The production of the described materials allows for a reduction in the amount of natural fibre waste and achieves the goal of “zero waste” according to the European Green Deal strategy. Full article
(This article belongs to the Special Issue Advances in Multifunctional Textiles: Materials, Technologies and Production Processes)
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<p>Photographs of the manufactured mats.</p> Full article ">Figure 2
<p>Sound absorption coefficient, α.</p> Full article ">Figure 3
<p>Noise reduction coefficient, NRC.</p> Full article ">
16 pages, 2536 KiB  
Article
Simplified Modelling of the Edge Crush Resistance of Multi-Layered Corrugated Board: Experimental and Computational Study
by Tomasz Garbowski, Anna Knitter-Piątkowska and Piotr Winiarski
Materials 2023, 16(1), 458; https://doi.org/10.3390/ma16010458 - 3 Jan 2023
Cited by 3 | Viewed by 2376
Abstract
The edge crush test is the most popular laboratory test in the corrugated packaging industry. It measures the edge crush resistance of a sample in the cross-fiber direction (CD), also known as the ECT index. This parameter is widely used for the specification [...] Read more.
The edge crush test is the most popular laboratory test in the corrugated packaging industry. It measures the edge crush resistance of a sample in the cross-fiber direction (CD), also known as the ECT index. This parameter is widely used for the specification of the board by its producers. It is also utilized in most analytical formulas describing the load capacity of the packaging. On the other hand, the ECT value can be estimated from both analytical and numerical models based on the basic parameters of each constituent paper. Knowing the compressive strength in CD (commonly known as SCT) and the elastic properties of the individual layers, the sample geometry (i.e., the period and height of the corrugated layer), as well as the boundary conditions, the ECT value can be calculated. This is very useful as new boards can be virtually analyzed before being manufactured. In this work, both detailed numerical models based on finite elements (FE) methods and very simple analytical (engineering) models were used for the ECT calculations. All presented models were validated with experimental data. The surprising consistency and high precision of the results obtained with the simplest approach was additionally analyzed in the study. Full article
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<p>Paper tensile stiffness test: (<b>a</b>) laboratory device; (<b>b</b>) samples cut in the directions: MD, CD and 45 degrees.</p> Full article ">Figure 2
<p>Laboratory testing machines: (<b>a</b>) short-span compression tester; (<b>b</b>) edge crush tester.</p> Full article ">Figure 3
<p>Model of BC-790 five-layered corrugated board: (<b>a</b>) without imperfections; (<b>b</b>) with imperfections (scale ×10).</p> Full article ">Figure 4
<p>Cross-section of three-layer corrugated cardboard.</p> Full article ">Figure 5
<p>Cross-section of five-layer corrugated cardboard.</p> Full article ">Figure 6
<p>Absolute estimation error obtained using five different models.</p> Full article ">
9 pages, 811 KiB  
Article
Influence of Thickness of Opaque Porcelain and Alloy Color on the Final Color of Porcelain-Fused-to-Metal Restorations
by Alessandro Vichi, Gabriele Corciolani, Michele Carrabba, Alvaro Munoz and Chris Louca
Materials 2023, 16(1), 457; https://doi.org/10.3390/ma16010457 - 3 Jan 2023
Cited by 2 | Viewed by 2116
Abstract
Despite the advent of metal-free solutions, porcelain-fused-to-metal restorations (PFM) are still widely used. Particularly for the latest ceramic systems, scarce information is present in the scientific literature about the ideal opaque layer thickness and the alloy color impact to achieve the desired final [...] Read more.
Despite the advent of metal-free solutions, porcelain-fused-to-metal restorations (PFM) are still widely used. Particularly for the latest ceramic systems, scarce information is present in the scientific literature about the ideal opaque layer thickness and the alloy color impact to achieve the desired final color of PFM restorations. This study aimed to evaluate the influence of opaque thickness variation layered on different metal alloys on the final color of PFM restorations. Opaque porcelain of one metal–ceramic system (VITA VM13) was layered in four different thicknesses (0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm) on three differently colored dental alloys: a gold–platinum alloy (yellowish), a gold–palladium alloy (light grayish), and a nickel–chromium alloy (dark grayish). The veneering porcelain layered over the opaque was kept constant (Base Dentine 0.45 mm, Transpa Dentine 0.50 mm, and Enamel 0.20 mm). Sixty specimens were fabricated, five samples for each combination of alloy/opaque thickness. The color difference (ΔE) between specimen and reference was measured using a clinical spectrophotometer. The two-way ANOVA revealed that the thickness of both the opaque (p < 0.001) and the metal alloy (p < 0.001) significantly influenced the ΔE values. Gray-colored alloys covered by a 0.10 mm thick opaque layer enabled the closest color match, whereas this occurred for yellow-color alloys covered by a 0.15 mm thick opaque layer. In contrast, the samples covered by a 0.25 mm thick opaque layer obtained the worst ΔE. Full article
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<p>Specimen configuration (dimensions in mm).</p> Full article ">Figure 2
<p>The clinical spectrophotometer VITA Easyshade fixed on a stand for color measurement.</p> Full article ">
22 pages, 11399 KiB  
Article
Fatigue Reliability Characterisation of Effective Strain Damage Model Using Extreme Value Distribution for Road Load Conditions
by Lennie Abdullah, Salvinder Singh Karam Singh, Shahrum Abdullah, Ahmad Kamal Ariffin and Syifa Syuhaidah Meor Zainal
Materials 2023, 16(1), 456; https://doi.org/10.3390/ma16010456 - 3 Jan 2023
Cited by 1 | Viewed by 2410
Abstract
The aim of this paper is to characterise the fatigue reliability for various random strain loads under extreme value distribution while considering the cycle sequence effect condition in fatigue life prediction. The established strain–life models, i.e., Morrow and Smith–Watson–Topper, considered a mean stress [...] Read more.
The aim of this paper is to characterise the fatigue reliability for various random strain loads under extreme value distribution while considering the cycle sequence effect condition in fatigue life prediction. The established strain–life models, i.e., Morrow and Smith–Watson–Topper, considered a mean stress effect and strain amplitude; nevertheless, it excluded the load sequence effect, which involves the fatigue crack closure that is subjected to overload or underload. A FESEM-EDX analysis is conducted to characterise the failure features that occurred on the leaf spring. A finite element is simulated to determine the critical region in order to obtain the strain load behaviour. In addition, the strain signal is captured experimentally at 500 Hz for 100 s under operating conditions for three different road loads based on the critical location obtained from the finite element analysis. The fatigue life correlation shows that the Pearson correlation coefficients are greater than 0.9, which indicates the effective strain damage model is linearly correlated with the strain–life models. The fatigue life data are modelled using extreme value distribution by considering the random strain loads as extreme data. The reliability rate for the fatigue life is reported to be more than 0.59 within the hazard rate range of 9.6 × 10−8 to 1.2 × 10−7 based on the mean cycle to the failure point. Hence, the effective strain damage model is proposed for a fatigue reliability assessment under extreme conditions with higher reliability and provides fatigue life prediction when subjected to cycle sequence effects. Full article
(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)
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<p>Process flow for fatigue-based reliability under random road load conditions.</p> Full article ">Figure 2
<p>Fracture identification in FESEM-EDX test for (<b>a</b>) Failure leaf spring; (<b>b</b>) Sample for FESEM-EDX; (<b>c</b>) Iridium Sputter Coater machine; (<b>d</b>) FESEM-EDX machine.</p> Full article ">Figure 3
<p>FE model of a leaf spring.</p> Full article ">Figure 4
<p>Experimental setup for strain load data collection for various road conditions.</p> Full article ">Figure 5
<p>Fractography of the leaf spring: (<b>a</b>) Crack region; (<b>b</b>) Fatigue crack initiation at region A; (<b>c</b>) Fatigue crack propagation at region B; (<b>d</b>) Sudden fracture at region C.</p> Full article ">Figure 6
<p>Critical region at maximum load.</p> Full article ">Figure 7
<p>Von Mises stress mapping under maximum load.</p> Full article ">Figure 8
<p>Time history road load obtained from experimental and PDF of: (<b>a</b>) Highway Day 1; (<b>b</b>) Highway Day 2; (<b>c</b>) Highway Day 3.</p> Full article ">Figure 9
<p>Time history road load obtained from experimental and PDF of: (<b>a</b>) Rural Day 1; (<b>b</b>) Rural Day 2; (<b>c</b>) Rural Day 3.</p> Full article ">Figure 10
<p>Time history road load obtained from experimental and PDF of: (<b>a</b>) Campus Day 1; (<b>b</b>) Campus Day 2; (<b>c</b>) Campus Day 3.</p> Full article ">Figure 11
<p>Rainflow cycle matrix for: (<b>a</b>) Highway D1; (<b>b</b>) Highway D2; (<b>c</b>) Highway D3.</p> Full article ">Figure 12
<p>Rainflow cycle matrix for: (<b>a</b>) Rural D1; (<b>b</b>) Rural D2; (<b>c</b>) Rural D3.</p> Full article ">Figure 12 Cont.
<p>Rainflow cycle matrix for: (<b>a</b>) Rural D1; (<b>b</b>) Rural D2; (<b>c</b>) Rural D3.</p> Full article ">Figure 13
<p>Rainflow cycle matrix for: (<b>a</b>) Campus D1; (<b>b</b>) Campus D2; (<b>c</b>) Campus D3.</p> Full article ">Figure 13 Cont.
<p>Rainflow cycle matrix for: (<b>a</b>) Campus D1; (<b>b</b>) Campus D2; (<b>c</b>) Campus D3.</p> Full article ">Figure 14
<p>Pearson correlation for: (<b>a</b>) ESD and Coffin–Manson; (<b>b</b>) ESD and Morrow; (<b>c</b>) ESD and SWT.</p> Full article ">Figure 14 Cont.
<p>Pearson correlation for: (<b>a</b>) ESD and Coffin–Manson; (<b>b</b>) ESD and Morrow; (<b>c</b>) ESD and SWT.</p> Full article ">Figure 15
<p>Fatigue life correlations for: (<b>a</b>) ESD versus Coffin–Manson; (<b>b</b>) ESD versus Morrow; (<b>c</b>) ESD versus SWT.</p> Full article ">Figure 15 Cont.
<p>Fatigue life correlations for: (<b>a</b>) ESD versus Coffin–Manson; (<b>b</b>) ESD versus Morrow; (<b>c</b>) ESD versus SWT.</p> Full article ">Figure 16
<p>McTF for various strain–life models.</p> Full article ">Figure 17
<p>PDF plot for various strain–life models.</p> Full article ">Figure 18
<p>CDF plot for various strain–life models.</p> Full article ">Figure 19
<p>Reliability for various strain–life models.</p> Full article ">Figure 20
<p>Hazard rate for various strain–life models.</p> Full article ">
12 pages, 3006 KiB  
Article
One-Step Synthesis of Sulfur-Doped Nanoporous Carbons from Lignin with Ultra-High Surface Area, Sulfur Content and CO2 Adsorption Capacity
by Dipendu Saha, Gerassimos Orkoulas and Dean Bates
Materials 2023, 16(1), 455; https://doi.org/10.3390/ma16010455 - 3 Jan 2023
Cited by 6 | Viewed by 2228
Abstract
Lignin is the second-most available biopolymer in nature. In this work, lignin was employed as the carbon precursor for the one-step synthesis of sulfur-doped nanoporous carbons. Sulfur-doped nanoporous carbons have several applications in scientific and technological sectors. In order to synthesize sulfur-doped nanoporous [...] Read more.
Lignin is the second-most available biopolymer in nature. In this work, lignin was employed as the carbon precursor for the one-step synthesis of sulfur-doped nanoporous carbons. Sulfur-doped nanoporous carbons have several applications in scientific and technological sectors. In order to synthesize sulfur-doped nanoporous carbons from lignin, sodium thiosulfate was employed as a sulfurizing agent and potassium hydroxide as the activating agent to create porosity. The resultant carbons were characterized by pore textural properties, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The nanoporous carbons possess BET surface areas of 741–3626 m2/g and a total pore volume of 0.5–1.74 cm3/g. The BET surface area of the carbon was one of the highest that was reported for any carbon-based materials. The sulfur contents of the carbons are 1–12.6 at.%, and the key functionalities include S=C, S-C=O, and SOx. The adsorption isotherms of three gases, CO2, CH4, and N2, were measured at 298 K, with pressure up to 1 bar. In all the carbons, the adsorbed amount was highest for CO2, followed by CH4 and N2. The equilibrium uptake capacity for CO2 was as high as ~11 mmol/g at 298 K and 760 torr, which is likely the highest among all the porous carbon-based materials reported so far. Ideally adsorbed solution theory (IAST) was employed to calculate the selectivity for CO2/N2, CO2/CH4, and CH4/N2, and some of the carbons reported a very high selectivity value. The overall results suggest that these carbons can potentially be used for gas separation purposes. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)
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<p>Schematic of one-step synthesis of sulfur-doped nanoporous carbon from lignin.</p> Full article ">Figure 2
<p>N<sub>2</sub> adsorption–desorption isotherms at 77 K (<b>a</b>); NLDFT-based pore size distribution (<b>b</b>).</p> Full article ">Figure 3
<p>X-ray photoelectron spectroscopy (XPS) analysis; peak deconvolution results of C-1s (<b>a</b>), S-2p (<b>b</b>), and O-1s (<b>c</b>) of LS-3; and C-1s (<b>d</b>), S-2p (<b>e</b>), and O-1s (<b>f</b>) of LS-5.</p> Full article ">Figure 4
<p>Representative Scanning Electron Imaging (SEM) results of LS-3 (<b>a</b>–<b>d</b>).</p> Full article ">Figure 5
<p>X-ray diffraction (XRD) results.</p> Full article ">Figure 6
<p>Adsorption isotherms of CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub> for LS-1 (<b>a</b>), LS-2 (<b>b</b>), LS-3 (<b>c</b>), LS-4 (<b>d</b>), and LS-5 (<b>e</b>).</p> Full article ">Figure 7
<p>Cyclability of working capacity of CO<sub>2</sub> adsorption in LS-5.</p> Full article ">Figure 8
<p>IAST-based selectivity for CO<sub>2</sub>/N<sub>2</sub> (<b>a</b>), CO<sub>2</sub>/CH<sub>4</sub> (<b>b</b>), and (<b>c</b>) CH<sub>4</sub>/N<sub>2</sub>.</p> Full article ">
10 pages, 1934 KiB  
Article
Structural, Magnetic and Vibrational Properties of Van Der Waals Ferromagnet CrBr3 at High Pressure
by Olga Lis, Denis Kozlenko, Sergey Kichanov, Evgenii Lukin, Ivan Zel and Boris Savenko
Materials 2023, 16(1), 454; https://doi.org/10.3390/ma16010454 - 3 Jan 2023
Cited by 5 | Viewed by 2345
Abstract
The crystal and magnetic structures of van der Waals layered ferromagnet CrBr3 were studied using X-ray powder diffraction and neutron powder diffraction at pressures up to 23 GPa at ambient temperature and up to 2.8 GPa in the temperature range 6–300 [...] Read more.
The crystal and magnetic structures of van der Waals layered ferromagnet CrBr3 were studied using X-ray powder diffraction and neutron powder diffraction at pressures up to 23 GPa at ambient temperature and up to 2.8 GPa in the temperature range 6–300 K, respectively. The vibration spectra of CrBr3 were studied using Raman spectroscopy at pressures up to 23 GPa at ambient temperature. The anomalous pressure behavior of structural parameters and vibrational modes was observed, associated with a gradual isostructural phase transition in the pressure range 2.5–7 GPa. The Curie temperature TC reduced rapidly with a pressure coefficient dTC/dP=−4.1(4) K/GPa. A full suppression of the ferromagnetic state was expected at PC~8.4 GPa, where onset of the antiferromagnetic spin arrangement or magnetically disordered state may take place. Anomalies in Raman spectra at P~15 GPa point to another possible phase transformation in CrBr3, which may be related to the proximity of metallization of this van der Waals ferromagnet. Full article
(This article belongs to the Special Issue Feature Papers in Materials Physics)
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<p>(<b>a</b>) X-ray diffraction patterns of CrBr<sub>3</sub> obtained at selected pressures and ambient temperature, and refined by the Rietveld method. Experimental points and calculated profiles are shown. The tick below marks the calculated positions of the structural peaks of phase of rhombohedral phase of CrBr<sub>3</sub>. The asterisks (*) indicate additional diffraction peaks from the rhenium gasket; (<b>b</b>) Schematically representation of rhombohedral crystal structure of CrBr<sub>3</sub>. The unit cell (<b>left</b>) and top view (<b>right</b>) are shown. The orientation of the crystallography axes is presented; (<b>c</b>) The lattice parameters of CrBr<sub>3</sub> as a function of pressure. The phase transition pressure <span class="html-italic">P<sub>tr</sub></span> is labeled. The solid lines are linear fit of experimental data; (<b>d</b>) The pressure dependence of unit cell volume of the ambient and high-pressure phases of CrBr<sub>3</sub>, fitted by the third order Birch-Murnaghan equation of state (1). The red circles represent the obtained values for unit-cell volume from ND data (see below).</p> Full article ">Figure 2
<p>Neutron diffraction patterns of CrBr<sub>3</sub> measured at selected pressures and temperatures and refined by the Rietveld method. The experimental points and calculated profiles are shown. Ticks below represent calculated positions of the nuclear peaks of the rhombohedral phase of CrBr<sub>3</sub>. The magnetic contribution into nuclear peaks is labeled as “N+FM”. Inset: the pressure evolution of the characteristic peak with additional magnetic contribution.</p> Full article ">Figure 3
<p>(<b>a</b>) The temperature dependences of the unit-cell volume obtained from neutron diffraction and normalized to the ambient temperature values; (<b>b</b>) The temperature dependences of the ordered Cr<sup>3+</sup> magnetic moments at selected pressures. The solid lines represent fitting by function described by Equation (2); (<b>c</b>) Curie temperature as a function of pressure and its linear extrapolation.</p> Full article ">Figure 4
<p>The Raman spectra of CrBr<sub>3</sub> measured at selected pressures and room temperature.</p> Full article ">Figure 5
<p>Pressure dependences of selected Raman shift for CrBr<sub>3</sub>. Solid lines are linear fits to the observed frequencies.</p> Full article ">
17 pages, 5497 KiB  
Article
Impact Resistance of a Fiber Metal Laminate Skin Bio-Inspired Composite Sandwich Panel with a Rubber and Foam Dual Core
by Wenping Zhang, Ruonan Li, Quanzhan Yang, Ying Fu and Xiangqing Kong
Materials 2023, 16(1), 453; https://doi.org/10.3390/ma16010453 - 3 Jan 2023
Cited by 8 | Viewed by 2351
Abstract
This paper reports the development of a novel bio-inspired composite sandwich panel (BCSP) with fiber metal laminate (FML) face sheets and a dual core to improve the low-velocity impact behavior based on the woodpecker’s head layout as a design template. The dynamic response [...] Read more.
This paper reports the development of a novel bio-inspired composite sandwich panel (BCSP) with fiber metal laminate (FML) face sheets and a dual core to improve the low-velocity impact behavior based on the woodpecker’s head layout as a design template. The dynamic response of BCSP under impact load is simulated and analyzed by ABAQUS/Explicit software and compared with that of the composite sandwich panel (CSP) with a single foam core. The impact behavior of BCSP affected by these parameters, i.e., a different face sheet thickness, rubber core thickness and foam core height, was also reported. The results show that BCSP has superior impact resistance compared to CSP, with a lower damage area and smaller deformation, while carrying a higher impact load. Concurrently, BCSP is not highly restricted to any particular region when dealing with stress distributions. Compared to CSP, the bottom skin maximum stress value of BCSP is significantly reduced by 2.4–6.3 times at all considered impact energy levels. It is also found that the impact efficiency index of BCSP is 4.86 times higher than that of CSP under the same impact energy, indicating that the former can resist the impact load more effectively than the latter in terms of overall performance. Furthermore, the impact resistance of the BCSP improved with the increase in face sheet thickness and rubber core thickness. Additionally, the height of the foam core has a notable effect on the energy absorption, while it does not play a significant role in impact load. From an economic viewpoint, the height of the foam core retrofitted with 20 mm is reasonable. The results acquired from the current investigation can provide certain theoretical reference to the use of the bio-inspired composite sandwich panel in the engineering protection field. Full article
(This article belongs to the Special Issue Metal and Polymer Composites for Functional and Structural Applications)
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<p>(<b>a</b>) Woodpecker head configuration [<a href="#B39-materials-16-00453" class="html-bibr">39</a>]; (<b>b</b>) BCSP.</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic of the geometric configurations of the BCSP. (<b>b</b>) Finite element model of the BCSP.</p> Full article ">Figure 3
<p>Mesh convergence analysis.</p> Full article ">Figure 4
<p>Flowchart for the numerical process of the VUMAT subroutine under ABAQUS.</p> Full article ">Figure 5
<p>Comparison of CSP’s simulated and experimental impact energy absorption with different foam core thicknesses [<a href="#B25-materials-16-00453" class="html-bibr">25</a>].</p> Full article ">Figure 6
<p>Failure state of the CSP subjected to impact from the experiment and numerical modelling.</p> Full article ">Figure 7
<p>Failure morphologies of the BCSP with different impact energies.</p> Full article ">Figure 8
<p>Comparison of the damage area between the BCSP and CSP under different impact energies.</p> Full article ">Figure 9
<p>Maximum stresses at the bottom face sheets of the CSP and BCSP under different energies.</p> Full article ">Figure 10
<p>Impact load–time curves of the BCSP.</p> Full article ">Figure 11
<p>Absorbed energy–time curves of the BCSP.</p> Full article ">Figure 12
<p>Peak load and impact energy absorption with different face sheet thicknesses.</p> Full article ">Figure 13
<p>Peak load and impact energy absorption with different rubber core thicknesses.</p> Full article ">Figure 14
<p>Peak load and impact energy absorption with different foam core heights.</p> Full article ">
16 pages, 8207 KiB  
Article
Durability Performance and Corrosion Mechanism of New Basalt Fiber Concrete under Organic Water Environment
by Jun Wei, Zhenshan Wang, Weidong Sun and Runan Yang
Materials 2023, 16(1), 452; https://doi.org/10.3390/ma16010452 - 3 Jan 2023
Cited by 5 | Viewed by 2054
Abstract
Under corrosive environments, concrete material properties can deteriorate significantly, which can seriously affect structural safety. Therefore, it has important engineering applications to improve the durability performance at a lower economic cost. This paper proposes a new, highly durable concrete using inexpensive construction materials [...] Read more.
Under corrosive environments, concrete material properties can deteriorate significantly, which can seriously affect structural safety. Therefore, it has important engineering applications to improve the durability performance at a lower economic cost. This paper proposes a new, highly durable concrete using inexpensive construction materials such as basalt fiber, sodium methyl silicate, and inorganic aluminum salt waterproofing agent. With the massive application of sewage treatment projects, the problem of concrete durability degradation is becoming more and more serious. In this paper, five types of concrete are developed for the sewage environment, and the apparent morphology and fine structure of the specimens after corrosion in sewage were analyzed. The density, water absorption, and compressive strength were measured to investigate the deterioration pattern of concrete properties. It was found that ordinary concrete was subject to significant corrosion, generating large deposits of algae on the surface and accompanied by sanding. The new concrete showed superior corrosion resistance compared to conventional concrete. Among other factors, the inorganic aluminum salt waterproofing agent effect was the most prominent. The study found that the strength of ordinary concrete decreased by about 15% in the test environment, while the new concrete had a slight increase. Comprehensive evaluation showed that the combination of basalt fiber and inorganic aluminum salt waterproofing agent had the best effect. Its use is recommended. Full article
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<p>Concrete corrosion phenotypes.</p> Full article ">Figure 1 Cont.
<p>Concrete corrosion phenotypes.</p> Full article ">Figure 2
<p>Compressed concrete damage.</p> Full article ">Figure 2 Cont.
<p>Compressed concrete damage.</p> Full article ">Figure 3
<p>Concrete pore structure changes after corrosion.</p> Full article ">Figure 4
<p>Microscopic morphology of concrete after corrosion.</p> Full article ">Figure 5
<p>X-ray diffraction of hydration products of concrete with different fitting ratios.</p> Full article ">Figure 6
<p>Concrete density variation.</p> Full article ">Figure 7
<p>Concrete water absorption rate change.</p> Full article ">Figure 8
<p>Load-displacement curve.</p> Full article ">Figure 8 Cont.
<p>Load-displacement curve.</p> Full article ">Figure 9
<p>Spatial distribution of compressive strength.</p> Full article ">Figure 10
<p>Concrete damage mode.</p> Full article ">Figure 11
<p>Sodium methyl silicate action model.</p> Full article ">Figure 12
<p>Inorganic aluminum salt waterproofing agent role model.</p> Full article ">
12 pages, 5075 KiB  
Article
Optimization of Single-Point Incremental Forming of Polymer Sheets through FEM
by Antonio Formisano, Luca Boccarusso and Massimo Durante
Materials 2023, 16(1), 451; https://doi.org/10.3390/ma16010451 - 3 Jan 2023
Cited by 10 | Viewed by 2932
Abstract
Incremental sheet forming represents a relatively new process appointed to form sheets of pure metals, alloys, polymers, and composites for the manufacture of components in fields where customized production in a short time and at a low cost is required. Its most common [...] Read more.
Incremental sheet forming represents a relatively new process appointed to form sheets of pure metals, alloys, polymers, and composites for the manufacture of components in fields where customized production in a short time and at a low cost is required. Its most common variant, named single-point incremental forming, is a flexible process using very simple tooling; the sheet is clamped along the edges and a hemispherical-headed tool follows a required path, to deform the sheet locally. In so doing, better formability is reached without any dedicated dies and for low-forming forces, which represent some of the attractive features of this process. Nevertheless, and with special reference to thermoplastic sheets, incremental formed parts suffer from peculiar defects like twisting and wrinkling. In this numerical work, analyses were conducted through a commercial finite element code by varying the toolpath strategy of the incremental forming of polycarbonate sheets. The investigation of some features like the forming forces, the deformation states, the energy levels, and the forming time was carried out, to determine the toolpath strategy able to optimize the incremental forming process of polymer sheets. The results of the numerical analyses highlight a reduction of the forming forces when using toolpaths alternating diagonal up and vertical down steps and, presumably, a reduced risk of failures and defects. Furthermore, these toolpath strategies solutions also have a positive impact on the environment in terms of energy and do not significantly increase the manufacturing time. Full article
(This article belongs to the Special Issue Advanced Incremental Sheet Forming of Hard-to-Work Materials)
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<p>Geometrical features of the equipment and of the cone frustum.</p> Full article ">Figure 2
<p>Features and details of the spiral path.</p> Full article ">Figure 3
<p>Toolpath strategies.</p> Full article ">Figure 4
<p>Trends of the forming forces vs. time for (<b>a</b>) <span class="html-italic">ref_tp</span> and (<b>b</b>) <span class="html-italic">hr</span>1.5<span class="html-italic">_tp</span>.</p> Full article ">Figure 5
<p>Trends of (<b>a</b>) <span class="html-italic">F<sub>Z</sub></span> and (<b>b</b>) <span class="html-italic">F<sub>XY</sub></span> vs. time by varying the toolpath strategy.</p> Full article ">Figure 6
<p>Forming time vs. the toolpath strategy.</p> Full article ">Figure 7
<p>Total, sliding and internal energy vs. the toolpath strategy.</p> Full article ">Figure 8
<p>Max shear strain distribution for (<b>a</b>) <span class="html-italic">ref_tp</span> and (<b>b</b>) <span class="html-italic">hr</span>1.5<span class="html-italic">_tp</span> strategy.</p> Full article ">
15 pages, 3226 KiB  
Article
Fast-Setting Calcium Silicate-Based Pulp Capping Cements—Integrated Antibacterial, Irritation and Cytocompatibility Assessment
by Gabriel Kato, Pedro Sousa Gomes, Karin Hermana Neppelenbroek, Cláudia Rodrigues, Maria Helena Fernandes and Liliana Grenho
Materials 2023, 16(1), 450; https://doi.org/10.3390/ma16010450 - 3 Jan 2023
Cited by 6 | Viewed by 3147
Abstract
Calcium silicate-based cements (CSCs) are endodontic materials widely used in vital pulp-capping approaches. Concerning the clinical application, the reduced set time and pre-mixed formulations are relevant characteristics during the operative management of pulpal exposure, aiming to optimise the work time and improve cross-infection/asepsis [...] Read more.
Calcium silicate-based cements (CSCs) are endodontic materials widely used in vital pulp-capping approaches. Concerning the clinical application, the reduced set time and pre-mixed formulations are relevant characteristics during the operative management of pulpal exposure, aiming to optimise the work time and improve cross-infection/asepsis control. Additionally, clinical success seems to be greatly dependent on the biological performance of the materials that directly contact the living pulp. As such, this work approaches an integrative biological characterisation (i.e., antibacterial, irritation, and cytocompatibility assays) of three fast-setting CSCs—BiodentineTM, TotalFill® BC RRM™ Fast Putty, and Theracal LC®. These cements, after setting for 24 h, presented the expected topography and elemental composition (assessed by scanning electron microscopy, coupled with EDS analysis), in accordance with the information of the manufacturer. The set cements displayed a significant and similar antibiofilm activity against S. mutans, in a direct contact assay. Twenty-four-hour eluates were not irritant in the standardised CAM assay, but elicited distinct dose- and time-dependent cytotoxicity profiles on fibroblastic cells—i.e., Biodentine was devoid of toxicity, TotalFill presented a slight dose-dependent initial toxicity that was easily overcome, and Theracal LC was deleterious at high concentrations. When compared to long-setting ProRoot MTA cement, which highlighted the pursued integrative approach, Biodentine presented a similar profile, but TotalFill and Theracal LC displayed a poorer performance regarding antibiofilm activity/cytocompatibility features, and Theracal LC suggested eventual safety concerns. Full article
(This article belongs to the Special Issue Advance in Biomaterials for Tissue Engineering)
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<p>Back-scattered scanning electron micrographs of the calcium silicate-based cements (CSCs) showing microstructural components (scale bar 10 µm) and respective elemental composition evaluated by EDS, for the view area and for the pointed zones in the images.</p> Full article ">Figure 2
<p>(<b>A</b>) Viable counts of the sessile <span class="html-italic">S. mutans</span> population after a 24 h direct incubation with the set CSCs, expressed as mean Log<sub>10</sub> CFU/mL. (<b>B</b>) SEM images of <span class="html-italic">S. mutans</span> morphology on the surface of the materials (scale bar 2 µm). * Statistically significant difference from the control, <span class="html-italic">p</span> ≤ 0.05.</p> Full article ">Figure 3
<p><span class="html-italic">In vivo</span> HET-CAM irritation assay. (<b>A</b>) Representative images of CAM and the negative and positive controls after exposures of 300 s. (<b>B</b>) Representative CAM images after exposure to the undiluted cement extracts for periods up to 300 s. Microscopic images were taken at 10× magnification.</p> Full article ">Figure 4
<p>(<b>A</b>) Live/dead assay fluorescence images of L929 fibroblasts exposed to 100%, 25%, and 10% cement extracts for 24 h; live cells (green) and dead cells (red) (scale bar 200 μm). (<b>B</b>) Metabolic activity measured in the same cultures, expressed at percentage of control, set at 100% (dotted line); the “cut-off” value of 70% of the control is also shown (dashed line). * Statistically significant difference from the control, <span class="html-italic">p</span> ≤ 0.05.</p> Full article ">Figure 5
<p>Cell proliferation of L929 fibroblasts exposed to undiluted (100%) and diluted (50%, 25%, 15%, 10%, and 1%) cement extracts for 24, 48, and 72 h. Results are expressed as percentage of control, set at 100% (dotted line); the “cut-off” value of 70% of the control is also shown (dashed line). * Statistically significant difference from the control, <span class="html-italic">p</span> ≤ 0.05.</p> Full article ">
17 pages, 9893 KiB  
Article
Correlations between Microstructure and Residual Stress of Nanoscale Depth Profiles for TSV-Cu/TiW/SiO2/Si Interfaces after Different Thermal Loading
by Min Zhang, Fangzhou Chen, Fei Qin, Si Chen and Yanwei Dai
Materials 2023, 16(1), 449; https://doi.org/10.3390/ma16010449 - 3 Jan 2023
Cited by 3 | Viewed by 2320
Abstract
In this paper, the residual stresses with a nanoscale depth resolution at TSV-Cu/TiW/SiO2/Si interfaces under different thermal loadings are characterized using the ion-beam layer removal (ILR) method. Moreover, the correlations of residual stress, microstructure, and the failure modes of the interfaces [...] Read more.
In this paper, the residual stresses with a nanoscale depth resolution at TSV-Cu/TiW/SiO2/Si interfaces under different thermal loadings are characterized using the ion-beam layer removal (ILR) method. Moreover, the correlations of residual stress, microstructure, and the failure modes of the interfaces are discussed. The residual stresses at the interfaces of TSV-Cu/TiW, TiW/SiO2, and SiO2/Si are in the form of small compressive stress at room temperature, then turn into high-tensile stress after thermal cycling or annealing. In addition, the maximum residual stress inside the TSV-Cu is 478.54 MPa at room temperature, then decreases to 216.75 MPa and 90.45 MPa, respectively, after thermal cycling and annealing. The microstructural analysis indicates that thermal cycling causes an increase in the dislocation density and a decrease in the grain diameter of TSV-Cu. Thus, residual stress accumulates constantly in the TSV-Cu/TiW interface, resulting in the cracking of the interface. Furthermore, annealing leads to the cracking of more interfaces, relieving the residual stress as well as increasing the grain diameter of TSV-Cu. Besides this, the applicability of the ILR method is verified by finite element modeling (FEM). The influence of the geometric errors of the micro-cantilever beam and the damage to the materials introduced by the focused ion beam (FIB) in the experimental results are discussed. Full article
(This article belongs to the Topic Advances in Microelectronics and Semiconductor Engineering)
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<p>Schematic diagram of the TSV sample: (<b>a</b>) the TSV-Cu array; (<b>b</b>) cross-section of TSV-Cu; (<b>c</b>) polished axial cross-section of TSV-Cu.</p> Full article ">Figure 2
<p>Schematic diagram of the micro cantilever beam sample: (<b>a</b>) SEM image of the micro cantilever beam for the Cu/TiW/SiO<sub>2</sub>/Si-interconnected structure; (<b>b</b>) SEM image of the removed sublayers.</p> Full article ">Figure 3
<p>The deflection of samples, (<b>a</b>) as-fabricated; (<b>b</b>) thermal cycling; (<b>c</b>) annealing.</p> Full article ">Figure 4
<p>Failure modes of TSV-Cu/TiW/SiO<sub>2</sub>/Si interfaces: (<b>a</b>) as fabricated; (<b>b</b>) thermal cycling; (<b>c</b>) annealing.</p> Full article ">Figure 5
<p>The residual stress distributions of each sublayer in the three samples under different thermal loading conditions: (<b>a</b>) as fabricated; (<b>b</b>) thermal cycling; (<b>c</b>) annealing.</p> Full article ">Figure 6
<p>The residual stress at interfaces and inner materials: (<b>a</b>) residual stress at interfaces; (<b>b</b>) residual stress in inner materials.</p> Full article ">Figure 7
<p>EBSD images of TSV-Cu under the different thermal loading conditions: (<b>a</b>) as fabricated; (<b>b</b>) thermal cycling; (<b>c</b>) annealing.</p> Full article ">Figure 8
<p>The distribution of TSV-Cu grain size according to distance from the TSV-Cu/TiW interface.</p> Full article ">Figure 9
<p>The local misorientation distribution of TSV-Cu under different thermal loading conditions.</p> Full article ">Figure 10
<p>Formation mechanism of the residual stress during the deposition process.</p> Full article ">Figure 11
<p>FE model and deflection contour: (<b>a</b>) FE model of the micro cantilever beam; (<b>b</b>) deflection contour after removing the last sublayer.</p> Full article ">Figure 12
<p>The comparison of the measured deflection and simulated deflection.</p> Full article ">Figure 13
<p>The SEM images and FE models of the micro cantilever beam with three kinds of machine errors: (<b>a</b>) rounded area; (<b>b</b>) shifts in the ILR area.</p> Full article ">Figure 14
<p>The deflection comparisons between the reference model and the three cases with a geometric error.</p> Full article ">Figure 15
<p>Incidence trajectories of Ga<sup>+</sup> in various materials with different energies: (<b>a</b>) Cu; (<b>b</b>) TiW; (<b>c</b>) SiO<sub>2</sub>; (<b>d</b>) Si.</p> Full article ">Figure 16
<p>The maximum transverse deviations of Ga<sup>+</sup> in various materials with different energies.</p> Full article ">
19 pages, 3565 KiB  
Article
Synthesis and Structure–Activity Relationship of 2,6-Disubstituted Thiosemicarbazone Derivatives of Pyridine as Potential Antituberculosis Agents
by Dagmara Ziembicka, Katarzyna Gobis, Małgorzata Szczesio, Andrzej Olczak, Ewa Augustynowicz-Kopeć, Agnieszka Głogowska, Izabela Korona-Głowniak and Krzysztof Bojanowski
Materials 2023, 16(1), 448; https://doi.org/10.3390/ma16010448 - 3 Jan 2023
Cited by 6 | Viewed by 1926
Abstract
In this study, six new 2,6-disubstituted thiosemicarbazone derivatives of pyridine were synthesized (4–9), and their tuberculostatic activity was evaluated. All of them showed two- to eightfold higher activity (minimum inhibitory concentration (MIC) 0.5–4 µg/mL) against the resistant strain compared [...] Read more.
In this study, six new 2,6-disubstituted thiosemicarbazone derivatives of pyridine were synthesized (4–9), and their tuberculostatic activity was evaluated. All of them showed two- to eightfold higher activity (minimum inhibitory concentration (MIC) 0.5–4 µg/mL) against the resistant strain compared with the reference drug. Compounds 5 and 7, which contained the most basic substituents—pyrrolidine and piperidine—in their structure, strongly inhibited the growth of the standard strain (MIC 2 µg/mL). Furthermore, the same derivatives exhibited activity comparable to that of the reference drugs against some types of Gram-positive bacteria (MIC 0.49 µg/mL) and showed no cytotoxicity (IC50 > 50 µg/mL) in HaCaT cells. The zwitterionic structure of each compound was determined using X-ray crystallography. Absorption, distribution, metabolism, and excretion analyses showed that all compounds are good drug candidates. Thus, compounds 5 and 7 were identified as leading structures for further research on antituberculosis drugs with extended effects. Full article
(This article belongs to the Special Issue Organic Compounds and Nanoparticles Studies for Applications in Cancer and Tuberculosis Therapeutics)
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<p>Structures of 2,4-disubstituted thiosemicarbazone derivatives of pyridine DMK-15 and MKG-1b.</p> Full article ">Figure 2
<p>Synthesis of 2,6-disubstituted thiosemicarbazone derivatives of pyridine <b>4</b>–<b>9</b>.</p> Full article ">Figure 3
<p>The molecular structures of compounds <b>4</b>–<b>9</b> showing the atom-labeling schemes. Displacement ellipsoids are drawn at the 50% probability level, and H atoms are shown as small spheres of arbitrary radii. Drawings were prepared with Mercury software.</p> Full article ">Figure 4
<p>Intermolecular hydrogen bonds in <b>4</b>–<b>9</b>.</p> Full article ">Figure 4 Cont.
<p>Intermolecular hydrogen bonds in <b>4</b>–<b>9</b>.</p> Full article ">Figure 4 Cont.
<p>Intermolecular hydrogen bonds in <b>4</b>–<b>9</b>.</p> Full article ">Figure 5
<p>Bioavailability radar for <b>4</b>–<b>9</b>.</p> Full article ">Figure 5 Cont.
<p>Bioavailability radar for <b>4</b>–<b>9</b>.</p> Full article ">Figure 6
<p>BOILED-Egg diagram for all compounds (lipophilicity (WLOGP) and polarity (tPSA), human intestinal absorption (white area), and blood–brain barrier permeation (yellow area).</p> Full article ">
22 pages, 6736 KiB  
Article
Hybrid Data-Driven Deep Learning Framework for Material Mechanical Properties Prediction with the Focus on Dual-Phase Steel Microstructures
by Ali Cheloee Darabi, Shima Rastgordani, Mohammadreza Khoshbin, Vinzenz Guski and Siegfried Schmauder
Materials 2023, 16(1), 447; https://doi.org/10.3390/ma16010447 - 3 Jan 2023
Cited by 5 | Viewed by 3151
Abstract
A comprehensive approach to understand the mechanical behavior of materials involves costly and time-consuming experiments. Recent advances in machine learning and in the field of computational material science could significantly reduce the need for experiments by enabling the prediction of a material’s mechanical [...] Read more.
A comprehensive approach to understand the mechanical behavior of materials involves costly and time-consuming experiments. Recent advances in machine learning and in the field of computational material science could significantly reduce the need for experiments by enabling the prediction of a material’s mechanical behavior. In this paper, a reliable data pipeline consisting of experimentally validated phase field simulations and finite element analysis was created to generate a dataset of dual-phase steel microstructures and mechanical behaviors under different heat treatment conditions. Afterwards, a deep learning-based method was presented, which was the hybridization of two well-known transfer-learning approaches, ResNet50 and VGG16. Hyper parameter optimization (HPO) and fine-tuning were also implemented to train and boost both methods for the hybrid network. By fusing the hybrid model and the feature extractor, the dual-phase steels’ yield stress, ultimate stress, and fracture strain under new treatment conditions were predicted with an error of less than 1%. Full article
(This article belongs to the Special Issue Behavior of Metallic and Composite Structures (Third Volume))
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<p>Workflow of the microstructure data generation with different heat treatment conditions.</p> Full article ">Figure 2
<p>Schematic view of the step-quenching heat treatment process routine.</p> Full article ">Figure 3
<p>Progression of the results of the PF simulation: (<b>a</b>) initial state, (<b>b</b>) 15 s, (<b>c</b>) 1 min, (<b>d</b>) 10 min, and (<b>e</b>) after quenching; and (<b>f</b>) SEM image of a sample undergoing the same heat treatment.</p> Full article ">Figure 4
<p>Flow curves of the ferrite and martensite phases used in micromechanical FEA [<a href="#B2-materials-16-00447" class="html-bibr">2</a>].</p> Full article ">Figure 5
<p>General framework of the hybrid model.</p> Full article ">Figure 6
<p>(<b>a</b>) ResNet50 model vs. (<b>b</b>) ResNet classic model.</p> Full article ">Figure 7
<p>(<b>a</b>) Decision stumps in Adaboost based on the boosting method; (<b>b</b>) decision trees in RF with the bagging method.</p> Full article ">Figure 8
<p>Loss and validation loss diagram for two approaches, ResNet50 and VGG16.</p> Full article ">Figure 9
<p>Performance of the proposed hybrid model while using the RF regressor for the training set (left diagrams) and test set (right figures).</p> Full article ">Figure 10
<p>Dataset parity plot while using the Adaboost regressor for training (right figures) and testing (left figures) datasets for three mechanical properties: yield stress (Y), ultimate stress (U), fracture strain (F).</p> Full article ">Figure 11
<p>Performance of the proposed hybrid model while using the Adaboost regressor.</p> Full article ">Figure 12
<p>Scatter diagram of training and testing microstructure images while using the RF regressor for training (right figures) and testing (left figures) datasets for three mechanical properties: yield stress (Y), ultimate stress (U), fracture strain (F).</p> Full article ">
11 pages, 5594 KiB  
Article
A Comparison of Low-Temperature Deformation Behavior and Fracture in Low-Carbon Steel Specimens Obtained by Electron Beam Additive Manufacturing and Conventional Casting and Normalization
by Elena Astafurova, Kseniya Reunova, Evgenii Melnikov, Marina Panchenko, Sergey Astafurov, Andrey Luchin, Elena Zagibalova and Evgenii Kolubaev
Materials 2023, 16(1), 446; https://doi.org/10.3390/ma16010446 - 3 Jan 2023
Cited by 1 | Viewed by 1565
Abstract
In the present work, the microstructure, phase composition, and temperature dependence of the mechanical properties and fracture micromechanisms of low-carbon steel produced by conventional casting and electron beam additive manufacturing have been studied. Regardless of the manufacturing method, the phase composition of steel [...] Read more.
In the present work, the microstructure, phase composition, and temperature dependence of the mechanical properties and fracture micromechanisms of low-carbon steel produced by conventional casting and electron beam additive manufacturing have been studied. Regardless of the manufacturing method, the phase composition of steel consists of ferrite with an insignificant fraction of carbides (pearlite grains in both types of steel and single coarse precipitates in the additively fabricated one). It was shown that the studied steels are characterized by a strong temperature dependence on yield strength and ultimate tensile strength. At T = 77 K, both types of steel are characterized by high strength properties, which decrease with increasing test temperatures up to 300 K. In addition, all deformation curves are characterized by the presence of a yield drop and yield plateau over the entire temperature range under study (77 K–300 K). A decrease in test temperature from 300 K to 77 K leads to a change in the fracture micromechanism of the steels from a dimple fracture to a cleavage one. Despite the similar deformation behavior and strength properties, the additively fabricated steel possesses lower elongation to failure at 77 K due to an insignificant fraction of coarse precipitates, which assists the nucleation of brittle cracks. Full article
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<p>A scheme of specimen orientation relative to the building direction of the billet.</p> Full article ">Figure 2
<p>SEM images of the microstructure of the low-carbon steel: (<b>a</b>,<b>c</b>) cast and (<b>b</b>,<b>d</b>) EBAM. Yellow circles in (<b>b</b>) show the coarse carbide particles.</p> Full article ">Figure 3
<p>XRD patterns obtained for low-carbon steel in the cast state and after the EBAM process.</p> Full article ">Figure 4
<p>Tensile “engineering stress vs. engineering strain” diagrams for the low-carbon steel: (<b>a</b>) steel in the cast state and (<b>b</b>) steel after the EBAM process.</p> Full article ">Figure 5
<p>Temperature dependences of the mechanical properties of the low-carbon steel in the cast state and after the EBAM process: (<b>a</b>) the yield strength (YS), (<b>b</b>) the ultimate tensile strength (UTS), and (<b>c</b>) the elongation to failure (El).</p> Full article ">Figure 6
<p>SEM images of the lateral surfaces of the low-carbon steel: (<b>a</b>) cast and (<b>b</b>) EBAM. Specimens were tensile tested to failure at 300 K.</p> Full article ">Figure 7
<p>SEM images of the lateral surfaces of the low-carbon steel: (<b>a</b>) cast and (<b>b</b>) EBAM. Specimens were tensile tested to failure at 77 K.</p> Full article ">Figure 8
<p>SEM images of fracture surfaces of the low-carbon steel: (<b>a</b>) cast and (<b>b</b>) EBAM. Specimens were tensile tested to failure at 300 K.</p> Full article ">Figure 9
<p>SEM images of fracture surfaces of the low-carbon steel: (<b>a</b>) cast and (<b>b</b>) EBAM. Specimens were tensile tested to failure at 77 K.</p> Full article ">
18 pages, 13690 KiB  
Article
Microstructure Evolution, Constitutive Modelling, and Superplastic Forming of Experimental 6XXX-Type Alloys Processed with Different Thermomechanical Treatments
by Andrey G. Mochugovskiy, Ahmed O. Mosleh, Anton D. Kotov, Andrey V. Khokhlov, Ludmila Yu. Kaplanskaya and Anastasia V. Mikhaylovskaya
Materials 2023, 16(1), 445; https://doi.org/10.3390/ma16010445 - 3 Jan 2023
Cited by 14 | Viewed by 2206
Abstract
This study focused on the microstructural analysis, superplasticity, modeling of superplastic deformation behavior, and superplastic forming tests of the Al-Mg-Si-Cu-based alloy modified with Fe, Ni, Sc, and Zr. The effect of the thermomechanical treatment with various proportions of hot/cold rolling degrees on the [...] Read more.
This study focused on the microstructural analysis, superplasticity, modeling of superplastic deformation behavior, and superplastic forming tests of the Al-Mg-Si-Cu-based alloy modified with Fe, Ni, Sc, and Zr. The effect of the thermomechanical treatment with various proportions of hot/cold rolling degrees on the secondary particle distribution and deformation behavior was studied. The increase in hot rolling degree increased the homogeneity of the particle distribution in the aluminum-based solid solution that improved superplastic properties, providing an elongation of ~470–500% at increased strain rates of (0.5–1) × 10−2 s−1. A constitutive model based on Arrhenius and Beckofen equations was used to describe and predict the superplastic flow behavior of the alloy studied. Model complex-shaped parts were processed by superplastic forming at two strain rates. The proposed strain rate of 1 × 10−2 s−1 provided a low thickness variation and a high quality of the experimental parts. The residual cavitation after superplastic forming was also large at the low strain rate of 2 × 10−3 s−1 and significantly smaller at 1 × 10−2 s−1. Coarse Al9FeNi particles did not stimulate the cavitation process and were effective to provide the superplasticity of alloys studied at high strain rates, whereas cavities were predominately observed near coarse Mg2Si particles, which act as nucleation places for cavities during superplastic deformation and forming. Full article
(This article belongs to the Special Issue Mechanical Performance and Microstructural Characterization of Light Alloys)
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<p>SEM images (backscattered electrons) of the samples annealed at (<b>a</b>) 350 °C for 8 h and (<b>b</b>) 350 °C for 8 h and a second step at 480 °C for 3 h.</p> Full article ">Figure 2
<p>TEM images for the samples (<b>a</b>–<b>c</b>) after one-stage annealing at 350 °C for 8 h and (<b>d</b>–<b>i</b>) for two-step annealing with the first stage at 350 °C for 8 h and the subsequent second stage at 480 °C for 3 h; (<b>a</b>,<b>d</b>,<b>g</b>) bright fields, (<b>b</b>,<b>e</b>) dark fields, (<b>c</b>,<b>f</b>) SAEDs, (<b>h</b>,<b>i</b>) high resolution with corresponding FFT.</p> Full article ">Figure 3
<p>SEM images of the samples thermomechanically treated in (<b>a</b>) 1HR, (<b>b</b>) 2HR, (<b>c</b>) CR50, and (<b>d</b>) CR80 regimes.</p> Full article ">Figure 4
<p>Dependencies of stress and m-value on the strain obtained with a constant strain rate test and a test with a periodically stepped strain rate 20% above the nominal of 2 × 10<sup>−3</sup> s<sup>−1</sup>, 5 × 10<sup>−3</sup> s<sup>−1</sup>, and 1 × 10<sup>−2</sup> s<sup>−1</sup> for (<b>a</b>) 1HR, (<b>b</b>) 2HR, (<b>c</b>) CR50, and (<b>d</b>) CR80 regimes for a temperature of 480 °C.</p> Full article ">Figure 5
<p>Stress-strain dependencies with constant strain rates in a range of 2 × 10<sup>−3</sup> to 2 × 10<sup>−2</sup> s<sup>−1</sup> and temperatures of (<b>a</b>) 440 °C; (<b>b</b>) 460 °C; (<b>c</b>) 480 °C; (<b>d</b>) 500 °C for samples processed with the 2HR regime.</p> Full article ">Figure 6
<p>The stress-strain dependency of the experimental data and approximated data by Equation (8) (group A) for different strain rates at temperatures of (<b>a</b>) 440, (<b>b</b>) 460, (<b>c</b>) 480, and (<b>d</b>) 500 °C.</p> Full article ">Figure 7
<p>(<b>a</b>) The stress-strain dependency of the experimental data and predicted data by Equation (8) of the unmodeled data (group B), (<b>b</b>) the correlation between experimental data and the fitted flow stress of group A, and (<b>c</b>) the correlation between experimental data and expected the flow stress of group B.</p> Full article ">Figure 8
<p>EBSD-IPF maps and misorientation angle distribution histograms corresponding to (<b>a</b>) 1HR, (<b>b</b>) 2HR, (<b>c</b>) CR50, and (<b>d</b>) CR80 regimes after 200% superplastic deformation at 480 °C and a 1 × 10<sup>−2</sup> s<sup>−1</sup> strain rate.</p> Full article ">Figure 9
<p>The microstructure and corresponding EDS-maps for samples after the 200% superplastic deformation at 480 °C with a strain rate of 1 × 10<sup>−2</sup> s<sup>−1</sup>: (<b>a</b>) HR2 and (<b>b</b>) CR80 processing models.</p> Full article ">Figure 10
<p>The median cross section and thickness of the part obtained by: (<b>a</b>,<b>c</b>) SPF and (<b>b</b>,<b>d</b>) FES by DEFORM 3D at different strain rates, (<b>a</b>,<b>b</b>) 2 × 10<sup>−3</sup> s<sup>−1</sup>, and (<b>c</b>,<b>d</b>) 1 × 10<sup>−2</sup> s<sup>−1</sup>.</p> Full article ">Figure 11
<p>The microstructure in the cross section of the part obtained by SPF with strain rates of (<b>a</b>–<b>d</b>) 2 × 10<sup>−3</sup> s<sup>−1</sup> and (<b>e</b>–<b>h</b>) 1 × 10<sup>−2</sup> s<sup>−1</sup>.</p> Full article ">
20 pages, 4964 KiB  
Review
A Review of Cu–Ni–Sn Alloys: Processing, Microstructure, Properties, and Developing Trends
by Lang Guo, Pengcheng Zuo, Zequn Zhang, Qianwen Zhang, Mengya Zhao, Xinyu Hou, Junsheng Wu and Bowei Zhang
Materials 2023, 16(1), 444; https://doi.org/10.3390/ma16010444 - 3 Jan 2023
Cited by 13 | Viewed by 3981
Abstract
Cu–Ni–Sn alloys have been widely used in the aerospace industry, the electronics industry, and other fields due to their excellent electrical and thermal conductivity, high strength, corrosion and wear resistance, etc., which make Cu–15Ni–8Sn alloys the perfect alternative to Cu–Be alloys. This paper [...] Read more.
Cu–Ni–Sn alloys have been widely used in the aerospace industry, the electronics industry, and other fields due to their excellent electrical and thermal conductivity, high strength, corrosion and wear resistance, etc., which make Cu–15Ni–8Sn alloys the perfect alternative to Cu–Be alloys. This paper begins with how Cu–Ni–Sn alloys are prepared. Then, the microstructural features, especially the precipitation order of each phase, are described. In addition, the influence of alloying elements, such as Si, Ti, and Nb, on its microstructure and properties is discussed. Finally, the effects of plastic deformation and heat treatment on Cu–Ni–Sn alloys are discussed. This review is able to provide insight into the development of novel Cu–Ni–Sn alloys with a high performance. Full article
(This article belongs to the Special Issue Feature Papers in "Metals and Alloys" Section)
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<p>Application of Cu–Ni–Sn alloys.</p> Full article ">Figure 2
<p>Cu–Ni–Sn ternary phase diagram (Ni fixed at 15 wt%) [<a href="#B12-materials-16-00444" class="html-bibr">12</a>].</p> Full article ">Figure 3
<p>TTT diagram of the alloy Cu–15Ni–8Sn [<a href="#B12-materials-16-00444" class="html-bibr">12</a>].</p> Full article ">Figure 4
<p>Bright-field (BF) TEM image of a quenched Cu–15Ni–8Sn sample [<a href="#B12-materials-16-00444" class="html-bibr">12</a>].</p> Full article ">Figure 5
<p>LPBF principle [<a href="#B27-materials-16-00444" class="html-bibr">27</a>].</p> Full article ">Figure 6
<p>Structure of the extruded Cu–9Ni–2.5Sn–xSi alloy as shown by an optical microscope: (<b>a</b>) x = 0; (<b>b</b>) x= 0.5 [<a href="#B31-materials-16-00444" class="html-bibr">31</a>].</p> Full article ">Figure 7
<p>TEM image of Ni<sub>16</sub>Si<sub>7</sub>Ti<sub>6</sub> particles and the dislocation boundary [<a href="#B35-materials-16-00444" class="html-bibr">35</a>].</p> Full article ">Figure 8
<p>STEM image of a cold-rolled alloy Cu–15Ni–8Sn–xFe: (<b>a</b>) x = 0; (<b>b</b>) x = 0.5 [<a href="#B29-materials-16-00444" class="html-bibr">29</a>].</p> Full article ">Figure 9
<p>TEM bright-field image of the alloy Cu–15Ni–8Sn–xP: (<b>a</b>) x = 0; (<b>b</b>) x = 0.2 [<a href="#B37-materials-16-00444" class="html-bibr">37</a>].</p> Full article ">Figure 10
<p>SEM image of discontinuous precipitation at grain boundary of Cu-15Ni-8Sn-xV alloy (<b>a</b>) x = 0; (<b>b</b>) x = 0.4; (<b>c</b>) x = 1.0 [<a href="#B38-materials-16-00444" class="html-bibr">38</a>].</p> Full article ">Figure 11
<p>Aging hardening curves of alloys with different Co contents treated by 773 K isothermal aging [<a href="#B40-materials-16-00444" class="html-bibr">40</a>].</p> Full article ">Figure 12
<p>The variations in yield strength versus aging time after aging treatment at 400 °C [<a href="#B45-materials-16-00444" class="html-bibr">45</a>].</p> Full article ">Figure 13
<p>SEM images of the precipitated strengthening phase from γ grains in the aged Cu–Ni–Sn alloy [<a href="#B51-materials-16-00444" class="html-bibr">51</a>].</p> Full article ">Figure 14
<p>Electron backscatter diffraction image of LPBF [<a href="#B55-materials-16-00444" class="html-bibr">55</a>].</p> Full article ">
24 pages, 13135 KiB  
Article
Effect of Scanning Strategy on Thermal Stresses and Strains during Electron Beam Melting of Inconel 625: Experiment and Simulation
by Xiaoyu Zhao, Yuan Wei, Rami Mansour, Sasan Dadbakhsh and Amir Rashid
Materials 2023, 16(1), 443; https://doi.org/10.3390/ma16010443 - 3 Jan 2023
Cited by 3 | Viewed by 2039
Abstract
This paper develops a hybrid experimental/simulation method for the first time to assess the thermal stresses generated during electron beam melting (EBM) at high temperatures. The bending and rupture of trusses supporting Inconel 625 alloy panels at ~1050 °C are experimentally measured for [...] Read more.
This paper develops a hybrid experimental/simulation method for the first time to assess the thermal stresses generated during electron beam melting (EBM) at high temperatures. The bending and rupture of trusses supporting Inconel 625 alloy panels at ~1050 °C are experimentally measured for various scanning strategies. The generated thermal stresses and strains are thereafter simulated using the Finite-Element Method (FEM). It is shown that the thermal stresses on the trusses may reach the material UTS without causing failure. Failure is only reached after the part experiences a certain magnitude of plastic strain (~0.33 ± 0.01 here). As the most influential factor, the plastic strain increases with the scanning length. In addition, it is shown that continuous scanning is necessary since the interrupted chessboard strategy induces cracking at the overlapping regions. Therefore, the associated thermal deformation is to be minimized using a proper layer rotation according to the part length. Although this is similar to the literature reported for selective laser melting (SLM), the effect of scanning pattern is found to differ, as no significant difference in thermal stresses/strains is observed between bidirectional and unidirectional patterns from EBM. Full article
(This article belongs to the Special Issue 3D Printing: Materials, Properties, and Applications)
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<p>A flowchart of the experimental and simulation works applied in this research.</p> Full article ">Figure 2
<p>(<b>a</b>) Printing layout, (<b>b</b>) size and (<b>c</b>) the Arcam EBM system used for this study and visual condition of the deflection testing parts after EBM.</p> Full article ">Figure 3
<p>Schematic of the default scanning strategy with a starting angle of 0° and a rotation angle of ~72°: with (<b>a</b>) bidirectional and (<b>b</b>) unidirectional scanning.</p> Full article ">Figure 4
<p>Schematic of the unidirectional chessboard printing. As shown, the chessboard printing was achieved by dividing the entire slice into several (10 for this work) islands, where each island was melted one after another.</p> Full article ">Figure 5
<p>Three-dimensional scanned unidirectional S0R180 part, showing the typical bending of the supporting trusses.</p> Full article ">Figure 6
<p>(<b>a</b>) The specimen drawing for high temperature tensile testing (unit: millimeter), and (<b>b</b>) the high temperature tensile testing set-up.</p> Full article ">Figure 7
<p>The deformation of the top panel for bidirectional S0R90 part, in (<b>a</b>) <span class="html-italic">x</span>-axis and (<b>b</b>) <span class="html-italic">y</span>-axis. As seen, large distortions could be observed along <span class="html-italic">x</span>-axis while there is no significant distortion along the <span class="html-italic">y</span>-axis.</p> Full article ">Figure 8
<p>A typical example, experimentally realizing the top panel deformation from bidirectional S0R90 part: (<b>a</b>) 3D scanned result of the selected points. (<b>b</b>) Summary of the designed positions, the displacement of the selected points along <span class="html-italic">x</span>- and <span class="html-italic">z</span>-axis. (<b>c</b>) Displacement functions realized from (<b>b</b>), ∆X(X) and ∆Z(X), applied to the FE-model to describe the final deformed model.</p> Full article ">Figure 9
<p>(<b>a</b>) The tensile property of the as-built EBM IN625 samples at 1050 °C. (<b>b</b>) Fracture surface of the samples tested without shielding gas. Large lack of fusion defects and intergranular cracks can be observed in the inserts.</p> Full article ">Figure 10
<p>Density of parts made using different scanning strategies. Note: the scale bar starts from 97%, and all the samples showed over 99% density.</p> Full article ">Figure 11
<p>The defects formed at the overlapping region of the 10I:0/90R0 part.</p> Full article ">Figure 12
<p>The experimentally measured bending angle and maximum shear strain (derived from maximum bending angle) of trusses supporting panels with long scans. These parts started with a 0° scan angle for their first layer and hence were subjected to a 100 mm long scanning length. * The unidirectional S0R0 and S0R180 panels were only 1.15 mm (instead of 2 mm) thick due to the process failure after excessive bending.</p> Full article ">Figure 13
<p>Stress simulated bending and rupturing of the trusses supporting (<b>a</b>) bidirectional and (<b>b</b>) unidirectional S0R90 panel as well as (<b>c</b>) bidirectional and (<b>d</b>) unidirectional S0R180 panel. Note that the unidirectional S0R180 part only had a panel thickness of 1.15 mm (instead of 2 mm) due to the process failure after excessive bending. For better visualization, see also the video provided in the <a href="#app1-materials-16-00443" class="html-app">supplementary data</a>.</p> Full article ">Figure 14
<p>The equivalent plastic strain and von Mises stresses on each truss of the parts made with long scans. Note that the unidirectional S0R0 and S0R180 parts only had a panel thickness of 1.15 mm (instead of 2 mm) due to stopping the process after excessive bending. * The unidirectional S0R0 and S0R180 panels were only 1.15 mm (instead of 2 mm) thick due to the process failure after excessive bending.</p> Full article ">Figure 15
<p>The bending angle and maximum shear strain (derived from maximum bending angle) for the supporting truss of the parts made with short-Y scans. Note that the bending of the trusses from two sides of the central supporting block are not symmetric.</p> Full article ">Figure 16
<p>Stress simulated bending of the trusses for (<b>a</b>) bidirectional and (<b>b</b>) unidirectional S90R0 parts. Note that left side bent less compared to the right side of the parts.</p> Full article ">Figure 17
<p>The equivalent plastic strain and von Mises stresses on each truss of the parts made with short-Y scans.</p> Full article ">Figure 18
<p>The bending angle and maximum shear strain (derived from maximum bending angle) of the chessboard printing.</p> Full article ">Figure 19
<p>Simulated bending of the trusses for 10I:S0/90R0 parts: (<b>a</b>) bidirectional scanning pattern and (<b>b</b>) unidirectional scanning pattern.</p> Full article ">Figure 20
<p>The equivalent plastic strain and von Mises stresses on each truss of chessboard scanned parts.</p> Full article ">Figure 21
<p>Comparison of fracture strains from experiments and simulations. For clarity, the total number of ruptured trusses have also been added for each case.</p> Full article ">Figure 22
<p>Typical bending progress of a truss until complete rupture via progress of von Mises stresses. The graph is taken from the unidirectional S0R72 part.</p> Full article ">Figure 23
<p>Schematic postulation for unsymmetrical bending of the trusses, supporting panels with short-Y scans.</p> Full article ">Figure 24
<p>Schematic of the chessboard scanning strategy.</p> Full article ">
17 pages, 8774 KiB  
Article
Study of Transition Areas in Press-Hardened Steels in a Combined Tool for Hot and Cold Forming
by Filip Votava, Hana Jirková, Ludmila Kučerová and Štěpán Jeníček
Materials 2023, 16(1), 442; https://doi.org/10.3390/ma16010442 - 3 Jan 2023
Cited by 3 | Viewed by 2417
Abstract
Press-hardening, also known as hot stamping, is a manufacturing process for producing car body parts that must meet the high demands of their mechanical properties and safety parameters. Moreover, these components often require different mechanical properties in different parts of the component. This [...] Read more.
Press-hardening, also known as hot stamping, is a manufacturing process for producing car body parts that must meet the high demands of their mechanical properties and safety parameters. Moreover, these components often require different mechanical properties in different parts of the component. This work presents the press-hardening process in a special combined tool where one half of the tool is heated and the other half is cooled. The cooled part has been 3D printed due to the complexity of the internal cooling channels. The aim of this work is to investigate the variation of the microstructures in the sheet metal and the mechanical properties in relation to the cooling process in the tool and to determine the transition area where these properties cross over. Two steels were chosen for the experiment. The most commonly used steel 22MnB5, and an experimental high-strength steel with 0.2% C alloyed with manganese and aluminium. A temperature of 425 °C was set in the heated part of the tool, and different holding times in the tool were tested. In the heated part of the tool, a bainitic structure with a fraction of ferrite and retained austenite was formed, while in the quenched part of the tool, a martensitic transformation was promoted due to rapid cooling. In addition to microscopic analyses, mechanical tests and hardness measurements were also performed. Full article
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<p>(<b>a</b>) Mechanical properties of 22MnB5 and (<b>b</b>) CCT diagram [<a href="#B3-materials-16-00442" class="html-bibr">3</a>].</p> Full article ">Figure 2
<p>CAD assembly of the combined tool.</p> Full article ">Figure 3
<p>Cut view of the cooling channels in the female part of the tool.</p> Full article ">Figure 4
<p>Workplace with the combined tool including all the accessories.</p> Full article ">Figure 5
<p>Heating curves for both parts of the sheet and the final shape of the omega profile.</p> Full article ">Figure 6
<p>Microstructures of 22MnB5 after hot stamping seen under an optical microscope: (<b>a</b>) 10s_C, (<b>b</b>) 10s_T, (<b>c</b>) 10s_H, (<b>d</b>) 140s_C, (<b>e</b>) 140s_T, (<b>f</b>) 140s_H, (<b>g</b>) 900s_C, (<b>h</b>) 900s_T, (<b>i</b>) 900s_H.</p> Full article ">Figure 7
<p>Microstructures of 22MnB5 after hot stamping under a scanning electron microscope: (<b>a</b>) 10s_C, (<b>b</b>) 10s_H, (<b>c</b>) 70s_C, (<b>d</b>) 70s_H.</p> Full article ">Figure 8
<p>Position of mini tensile specimens on the omega profile product from cooled and heated part.</p> Full article ">Figure 9
<p>Mechanical properties of 22MnB5 steel (cooled (C) and heated (H) part).</p> Full article ">Figure 10
<p>Microstructures of 20MnAl after hot stamping under an optical microscope: (<b>a</b>) 10s_C, (<b>b</b>) 10s_T, (<b>c</b>) 10s_H, (<b>d</b>) 140s_C, (<b>e</b>) 140s_T, (<b>f</b>) 140s_H, (<b>g</b>) 900s_C, (<b>h</b>) 900s_T, (<b>i</b>) 900s_H.</p> Full article ">Figure 11
<p>Microstructures of 20MnAl after hot stamping under a scanning electron microscope: (<b>a</b>) 10s_C, (<b>b</b>) 10s_H, (<b>c</b>) 900s_C, (<b>d</b>) 900s_H.</p> Full article ">Figure 12
<p>Mechanical properties for 20MnAl steel (cooled (C) and heated (H) part).</p> Full article ">Figure 13
<p>Hardness profile through the transition area of 20MnAl steel samples: 10s_T and 900s_T.</p> Full article ">Figure 14
<p>TTT diagram for 22MnB5 steel calculated in JMatPro software (version 12.1).</p> Full article ">Figure 15
<p>TTT diagram for 20MnAl steel calculated in JMatPro software.</p> Full article ">
26 pages, 2506 KiB  
Article
ACTAS: A New Framework for Mechanical and Frictional Characterization in Axisymmetric Compression Test
by Soheil Solhjoo
Materials 2023, 16(1), 441; https://doi.org/10.3390/ma16010441 - 3 Jan 2023
Cited by 3 | Viewed by 1835
Abstract
There are two common methods to interpret the results of an Axisymmetric Compression Test (ACT): the Cylindrical Profile Model (CPM) and the Avitzur model; however, both of the two and all other models available in the literature ignore the unavoidable foldover phenomenon, which [...] Read more.
There are two common methods to interpret the results of an Axisymmetric Compression Test (ACT): the Cylindrical Profile Model (CPM) and the Avitzur model; however, both of the two and all other models available in the literature ignore the unavoidable foldover phenomenon, which breaks the models to provide reliable friction-free flow stress curves. Here, a novel numerical framework (called ACTAS) is presented that incorporates the foldover. ACTAS can be used to both simulate and analyze ACT. Ten finite element models are used to benchmark ACTAS. The results show the reliability of the proposed method in estimating the average and pointwise stress-strain curves and friction factors. Moreover, a new solution is provided by coupling the CPM and the Avitzur model (called A-CPM), to obtain reliable average flow curves even after the onset of foldover. Full article
(This article belongs to the Section Mechanics of Materials)
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<p>The schematic of the sample geometry in axisymmetric compression test (left) before and (right) after the deformation. <math display="inline"><semantics> <msub> <mi>R</mi> <mn>0</mn> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>H</mi> <mn>0</mn> </msub> </semantics></math> are the sample’s initial radius and height, respectively. By deforming the sample with a constant velocity of <math display="inline"><semantics> <mrow> <mo>−</mo> <mi>U</mi> <mo>/</mo> <mn>2</mn> </mrow> </semantics></math> parallel to the <span class="html-italic">z</span> axis, three characteristic radii can be identified: the mid-plane (<math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">M</mi> </msub> </semantics></math>), top-plane (<math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> </semantics></math>) and slip (<math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">S</mi> </msub> </semantics></math>) radii with foldover being <math display="inline"><semantics> <mrow> <mi>F</mi> <mo>=</mo> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> <mo>−</mo> <msub> <mi>R</mi> <mi mathvariant="normal">S</mi> </msub> </mrow> </semantics></math>. (<math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">S</mi> </msub> </semantics></math> is the result of the expansion of <math display="inline"><semantics> <msub> <mi>R</mi> <mn>0</mn> </msub> </semantics></math>, and <span class="html-italic">F</span> is the contribution of the side surface foldover, resulting in a larger top-plane radius <math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> </semantics></math>). In a flow-based model, any point <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>(</mo> <mi>r</mi> <mo>,</mo> <mi>z</mi> <mo>)</mo> </mrow> </semantics></math> moves based on the radial and axial components of the velocity field (<math display="inline"><semantics> <mrow> <msub> <mi>U</mi> <mi>r</mi> </msub> <mo>,</mo> <msub> <mi>U</mi> <mi>z</mi> </msub> </mrow> </semantics></math>).</p> Full article ">Figure 2
<p>The ratio of Equation (<a href="#FD4-materials-16-00441" class="html-disp-formula">4</a>) (A-CPM) to Equation (<a href="#FD2-materials-16-00441" class="html-disp-formula">2</a>) (Avitzur model) for a wide range of <math display="inline"><semantics> <msub> <mi>b</mi> <mi mathvariant="normal">A</mi> </msub> </semantics></math> and <math display="inline"><semantics> <mrow> <mover> <mi>R</mi> <mo>¯</mo> </mover> <mo>/</mo> <mi>H</mi> </mrow> </semantics></math>.</p> Full article ">Figure 3
<p>The percentage volume change error as a function of numbers of simulation steps and grids. With an arbitrarily small threshold of <math display="inline"><semantics> <mrow> <mi>δ</mi> <msub> <mrow> <mo>(</mo> <mi>V</mi> <mo>)</mo> </mrow> <mi>max</mi> </msub> <mo>=</mo> <mn>0.02</mn> <mo>%</mo> </mrow> </semantics></math>, the features for the forthcoming tests of the current study are selected.</p> Full article ">Figure 4
<p>Discretized sample of Case 1 with a grid of 50 at the (<b>a</b>) initial and (<b>b</b>) final stage of the ACT.</p> Full article ">Figure 5
<p>The results of Case 1. (<b>a</b>) The variation of deformation load (left <span class="html-italic">y</span>-axis), mid-plane, and top-plane radii (right <span class="html-italic">y</span>-axis) as functions of displacement <span class="html-italic">d</span>. (<b>b</b>) The values of <math display="inline"><semantics> <msub> <mi>b</mi> <mi mathvariant="normal">L</mi> </msub> </semantics></math> obtained from the minimization process (<math display="inline"><semantics> <msub> <mi>b</mi> <mrow> <mi mathvariant="normal">L</mi> <mo>(</mo> <mi>min</mi> <mo>)</mo> </mrow> </msub> </semantics></math>) and the kinematics estimation (<math display="inline"><semantics> <msub> <mi>b</mi> <mrow> <mi mathvariant="normal">L</mi> <mo>(</mo> <mi mathvariant="normal">K</mi> <mo>)</mo> </mrow> </msub> </semantics></math>) from Equation (<a href="#FD20-materials-16-00441" class="html-disp-formula">20</a>).</p> Full article ">Figure 6
<p>The correlation between the assigned (<math display="inline"><semantics> <msub> <mi>m</mi> <mi mathvariant="normal">A</mi> </msub> </semantics></math>) and estimated (<math display="inline"><semantics> <msub> <mi>m</mi> <mi mathvariant="normal">E</mi> </msub> </semantics></math>) values of the friction factor in Case 1. The continuous black line represents a perfect correlation.</p> Full article ">Figure 7
<p>The correlation between the assigned and estimated values of the material parameters (<b>a</b>) <span class="html-italic">k</span> and (<b>b</b>) <span class="html-italic">n</span> in Case 1.</p> Full article ">Figure 8
<p>The schematic of the newly proposed model that divides the sample into two zones, with zone 1 for <math display="inline"><semantics> <mrow> <mn>0</mn> <mo>≤</mo> <mi>r</mi> <mo>≤</mo> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> </mrow> </semantics></math> and zone 2 for <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> <mo>&lt;</mo> <mi>r</mi> <mo>≤</mo> <mi>R</mi> <mrow> <mo>(</mo> <mi>z</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>. The border of zones 1 and 2 is at <math display="inline"><semantics> <mrow> <mi>r</mi> <mo>=</mo> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 9
<p>Discretized sample of Case 2 with a grid of 50 at the final stage of the ACT.</p> Full article ">Figure 10
<p>The results of Case 2. (<b>a</b>) The deformation load (left <span class="html-italic">y</span>-axis) and the sample’s geometry (right <span class="html-italic">y</span>-axis) as functions of displacement <span class="html-italic">d</span>. (<b>b</b>) The values of <math display="inline"><semantics> <msub> <mi>b</mi> <mi mathvariant="sans-serif">λ</mi> </msub> </semantics></math> obtained from the minimization process (<math display="inline"><semantics> <mrow> <msub> <mi>b</mi> <mi mathvariant="sans-serif">λ</mi> </msub> <mrow> <mo>(</mo> <mi>min</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>) and the kinematics estimation (<math display="inline"><semantics> <mrow> <msub> <mi>b</mi> <mi mathvariant="sans-serif">λ</mi> </msub> <mrow> <mo>(</mo> <mi mathvariant="normal">K</mi> <mo>)</mo> </mrow> </mrow> </semantics></math>) from Equation (<a href="#FD28-materials-16-00441" class="html-disp-formula">28</a>) for two values of <math display="inline"><semantics> <msub> <mi>R</mi> <mo>□</mo> </msub> </semantics></math>: <math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">S</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> </semantics></math>. The zoomed-in inset shows that the <math display="inline"><semantics> <mrow> <msub> <mi>b</mi> <mi mathvariant="sans-serif">λ</mi> </msub> <mrow> <mo>(</mo> <mi mathvariant="normal">K</mi> <mo>)</mo> </mrow> <mrow> <mo>(</mo> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> <mo>)</mo> </mrow> </mrow> </semantics></math> underestimates the barreling parameter from the onset of the foldover phenomenon.</p> Full article ">Figure 11
<p>The correlation between <math display="inline"><semantics> <msub> <mi>m</mi> <mi mathvariant="normal">A</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>m</mi> <mi mathvariant="normal">E</mi> </msub> </semantics></math> in Case 2.</p> Full article ">Figure 12
<p>The correlation between the assigned and estimated values of the material parameters (<b>a</b>) <span class="html-italic">k</span> and (<b>b</b>) <span class="html-italic">n</span> for Case 2.</p> Full article ">Figure 13
<p>The percent error of (<b>a</b>) deformation load, and profile’s (<b>b</b>) <math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">M</mi> </msub> </semantics></math>, (<b>c</b>) <math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">T</mi> </msub> </semantics></math>, and (<b>d</b>) <math display="inline"><semantics> <msub> <mi>R</mi> <mi mathvariant="normal">S</mi> </msub> </semantics></math> obtained from comparing ACTS and FE models. The symbols are to be read from the legend in the subplot (<b>d</b>) that refers to the corresponding sample number in <a href="#materials-16-00441-t001" class="html-table">Table 1</a>.</p> Full article ">Figure 14
<p>The correlation between the assigned (<math display="inline"><semantics> <msub> <mi>m</mi> <mi>FEM</mi> </msub> </semantics></math>) and estimated (<math display="inline"><semantics> <msub> <mi>m</mi> <mi>ACTA</mi> </msub> </semantics></math>) friction factors. The symbols point to different samples to be read using the legend of <a href="#materials-16-00441-f013" class="html-fig">Figure 13</a>d.</p> Full article ">Figure 15
<p>The correlation between the assigned and estimated values of the material parameters (<b>a</b>) <span class="html-italic">k</span> and (<b>b</b>) <span class="html-italic">n</span> for the samples investigated in the benchmark.</p> Full article ">Figure 16
<p>The stress analysis of the ten reference samples (see <a href="#materials-16-00441-t001" class="html-table">Table 1</a>). (<b>a</b>) average flow curves obtained from A-CPM (Equation (<a href="#FD4-materials-16-00441" class="html-disp-formula">4</a>)) and ACTA (according to the algorithm developed for Case 2) in comparison with the assigned Hollomon models. (<b>b</b>) the correlation between the estimated average stresses (A-CPM and ACTA) and the assigned values. (Sample #5 is randomly selected for further detailed discussions in this section. For that, its flow curve is identified in the subset (<b>a</b>)).</p> Full article ">Figure 17
<p>Comparison of the von Mises stress distributions in a randomly selected sample (#5) for (<b>a</b>) FEM and the proposed (<b>b</b>) ACTS and (<b>c</b>) ACTA models. (The presented solutions for ACTA are essentially the solutions of ACTS using the parameters identified from the ACTA analyses of the FE virtual experiments). The values are in the units of MPa.</p> Full article ">Figure 18
<p>Comparison of the effective strain distributions in a randomly selected sample (#5) for (<b>a</b>) FEM, (<b>b</b>) ACTS, and (<b>c</b>) ACTA models.</p> Full article ">Figure 19
<p>The stress-strain curves at the center of the samples (<b>a</b>) 1, (<b>b</b>) 2, (<b>c</b>) 3, (<b>d</b>) 4, (<b>e</b>) 5, (<b>f</b>) 6, (<b>g</b>) 7, (<b>h</b>) 8, (<b>i</b>) 9, and (<b>j</b>) 10. The data are obtained from different models of FEM, ACTS, and ACTA. The results of A-CPM, which are uniform throughout the sample, are added for comparison. Note that the ranges for both stress and strain vary for different samples, and <math display="inline"><semantics> <mrow> <mo movablelimits="true" form="prefix">max</mo> <mfenced separators="" open="(" close=")"> <msub> <mover> <mi>ε</mi> <mo>¯</mo> </mover> <mrow> <mi mathvariant="normal">A</mi> <mo>-</mo> <mi>CPM</mi> </mrow> </msub> </mfenced> <mo>=</mo> <mn>0.47</mn> </mrow> </semantics></math> for all samples.</p> Full article ">Figure A1
<p>The assigned stress-strain curve for sample #6 and those obtained from A-CPM using the estimates of <math display="inline"><semantics> <msub> <mi>b</mi> <mi mathvariant="normal">A</mi> </msub> </semantics></math> that are developed with a static method for the (<b>a</b>) forward and (<b>b</b>) backward Euler kinematics. (The formulation of <math display="inline"><semantics> <msub> <mi>b</mi> <mi>EN</mi> </msub> </semantics></math> and <math display="inline"><semantics> <msub> <mi>b</mi> <mi mathvariant="normal">S</mi> </msub> </semantics></math> is the same for the forward Euler kinematics in the static method).</p> Full article ">Figure A2
<p>The assigned and A-CPM estimates of the flow stress curve of sample #6. Various estimtes of <math display="inline"><semantics> <msub> <mi>b</mi> <mi mathvariant="normal">A</mi> </msub> </semantics></math> used in A-CPM are developed with a dynamic method for the (<b>a</b>) forward and (<b>b</b>) backward Euler kinematics.</p> Full article ">
19 pages, 7374 KiB  
Article
Large-Scale Model Test on Water Pressure Resistance of Lining Structure of Water-Rich Tunnel
by Mingli Huang, Meng Huang and Ze Yang
Materials 2023, 16(1), 440; https://doi.org/10.3390/ma16010440 - 3 Jan 2023
Cited by 1 | Viewed by 2081
Abstract
In order to solve the problem of testing the water pressure resistance of lining structures of water-rich tunnels and the difficulty of implementing the existing model tests, a large-scale model test method was proposed relying on the New Yuanliangshan Tunnel threatened by high [...] Read more.
In order to solve the problem of testing the water pressure resistance of lining structures of water-rich tunnels and the difficulty of implementing the existing model tests, a large-scale model test method was proposed relying on the New Yuanliangshan Tunnel threatened by high pressure and rich water. This method creatively transformed the external water pressure of the lining structure into internal water pressure, and the conversion coefficient of water resistance of lining under different sizes and loading modes was obtained by numerical calculation. Results showed that the ultimate water pressure resistance of the lining structure under an external uniformly distributed water pressure and local water pressure was 1.44 and 0.67 times of that obtained from the large-scale model tests, respectively. By conducting the large-scale model tests and combining with the conversion coefficient, the water pressure resistance of the actual tunnel lining could be obtained. Research indicated that water pressure resistance of K2.0 (bearing water pressure of 2.0 MPa) type lining at the transition section of karst caves and K3.0 (bearing water pressure of 3.0 MPa) type lining at the section of karst caves of the New Yuanliangshan Tunnel was 3.33 MPa and not less than 4.36 MPa, respectively, and the high reliability of the large-scale model tests was verified by numerical calculation, implying that the model test method could be extended to similar tunnel projects. Full article
(This article belongs to the Special Issue Novel Civil Engineering Materials Integrated with Structures)
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<p>Location map of the New Yuanliangshan Tunnel.</p> Full article ">Figure 2
<p>Structural drawing of secondary lining in the transition section of karst cave (unit: cm): (<b>a</b>) K2.0 type lining; (<b>b</b>) Type II construction joint (circumferential).</p> Full article ">Figure 3
<p>Structural drawing of secondary lining in the section of karst cave (unit: cm): (<b>a</b>) K3.0 type lining; (<b>b</b>) type III construction joint (circumferential).</p> Full article ">Figure 4
<p>Schematic diagram of numerical calculation model (unit: cm): (<b>a</b>) I: lining bearing external uniform water pressure; (<b>b</b>) II: lining bearing external local water pressure; (<b>c</b>) III: lining bearing internal uniform water pressure; (<b>d</b>) IV: large-scale test model bearing internal uniform water pressure.</p> Full article ">Figure 5
<p>Numerical calculation results under condition I: (<b>a</b>) calculation model; (<b>b</b>) damage diagram of the model (step: 91–6).</p> Full article ">Figure 6
<p>Numerical calculation results under condition II: (<b>a</b>) calculation model; (<b>b</b>) damage diagram of the model (step: 42–5).</p> Full article ">Figure 7
<p>Numerical calculation results under condition III: (<b>a</b>) calculation model; (<b>b</b>) damage diagram of the model (step: 30–5).</p> Full article ">Figure 8
<p>Numerical calculation results under condition IV: (<b>a</b>) calculation model; (<b>b</b>) damage diagram of the model (step: 63–14).</p> Full article ">Figure 9
<p>Water pressure resistance and safety factor under different working conditions.</p> Full article ">Figure 10
<p>Large scale test models: (<b>a</b>) specimen 1; (<b>b</b>) specimen 2.</p> Full article ">Figure 11
<p>Schematic diagram and dimensions of the model for testing water pressure of lining in the transition section of karst cave (unit: cm): (<b>a</b>) elevation view of model; (<b>b</b>) vertical view of model.</p> Full article ">Figure 12
<p>Schematic diagram and dimensions of the model for testing water pressure of lining in the section of karst cave (unit: cm): (<b>a</b>) elevation view of model; (<b>b</b>) vertical view of model.</p> Full article ">Figure 13
<p>Schematic diagram of pressure pump station.</p> Full article ">Figure 14
<p>Pressure pump used on site.</p> Full article ">Figure 15
<p>Schematic diagram of numerical calculation model.</p> Full article ">Figure 16
<p>Loading process of model test: (<b>a</b>) test model before loading; (<b>b</b>) test model after loading.</p> Full article ">Figure 17
<p>Water seepage path inside the test model.</p> Full article ">Figure 18
<p>Loading process of model test: (<b>a</b>) test model before loading; (<b>b</b>) test model after loading (no leakage).</p> Full article ">Figure 19
<p>Histogram of water pressure resistance of lining structure obtained by model test and numerical calculation.</p> Full article ">
13 pages, 14655 KiB  
Article
Effect of Zirconium Diboride and Titanium Diboride on the Structure and Properties of 316L Steel-Based Composites
by Iwona Sulima, Paweł Hyjek, Marcin Podsiadło and Sonia Boczkal
Materials 2023, 16(1), 439; https://doi.org/10.3390/ma16010439 - 3 Jan 2023
Cited by 1 | Viewed by 1738
Abstract
The effect of zirconium diboride (ZrB2) and titanium diboride (TiB2) on the microstructure as well as the physical, mechanical, and tribological properties of composites based on 316 L steel is presented. Each reinforcing phase was added to the base [...] Read more.
The effect of zirconium diboride (ZrB2) and titanium diboride (TiB2) on the microstructure as well as the physical, mechanical, and tribological properties of composites based on 316 L steel is presented. Each reinforcing phase was added to the base alloy in the amount of 5 wt% and 10 wt%. The composites were fabricated by the SPS process (Spark Plasma Sintering). The results show that the weight fraction of the reinforcing phase affects the physical, mechanical, and tribological properties of the sintered composites. The sintered materials were characterized by a very high level of density. The addition of TiB2 has proved to be effective in increasing the hardness and compressive strength of the composites. The hardness of the composites with the addition of 10% TiB2 increased by 100% compared to the hardness of sintered 316L steel. It was found that introducing ZrB2 to the steel matrix significantly improved the wear resistance of the composites. The results showed that compared to 316L steel with the wear rate of 519 × 10−6 mm3/Nm, the wear rate of the composites containing 10% ZrB2 decreased more than twice, i.e., to 243 × 10−6 mm3/Nm. Full article
(This article belongs to the Section Advanced Composites)
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<p>SEM images of raw materials. (<b>a</b>) 316L austenitic stainless steel, (<b>b</b>) diboride zirconium, and (<b>c</b>) diboride titanium.</p> Full article ">Figure 2
<p>Actual (<b>a</b>) temperature–time, (<b>b</b>) displacement–time, and (<b>c</b>) pressure–time curves registered during the SPS process.</p> Full article ">Figure 3
<p>The SEM micrograph of the composites with: (<b>a</b>) 5% ZrB<sub>2</sub>, (<b>b</b>) 10% ZrB<sub>2,</sub> (<b>c</b>) 5% TiB<sub>2</sub>, and (<b>d</b>) 10% TiB<sub>2</sub>.</p> Full article ">Figure 4
<p>The SEM image of steel+10% ZrB<sub>2</sub> composite with WDS analysis.</p> Full article ">Figure 5
<p>The SEM image of steel+10% TiB<sub>2</sub> composite with WDS analysis.</p> Full article ">Figure 6
<p>The EBSD maps of the steel+5% ZrB<sub>2</sub> composite.</p> Full article ">Figure 7
<p>The EBSD maps of the analysis of the steel + 5% TiB<sub>2</sub> composite.</p> Full article ">Figure 8
<p>The results of the Young’s modulus measurements.</p> Full article ">Figure 9
<p>Vickers hardness of sintered composites.</p> Full article ">Figure 10
<p>Compressive stress–strain curves for sintered materials.</p> Full article ">Figure 11
<p>Variations in (<b>a</b>) the coefficient of friction and (<b>b</b>) the specific wear rate as a function of the content of ceramic compositions.</p> Full article ">Figure 12
<p>(<b>a</b>) Depth of scar as a function of the test duration and SEM micrograph of the worn surface of: (<b>b</b>) steel and composites with (<b>c</b>) 5% ZrB<sub>2</sub>, (<b>d</b>) 10% ZrB<sub>2</sub>, (<b>e</b>) 5% TiB<sub>2</sub>, and (<b>f</b>) 10% TiB<sub>2</sub>.</p> Full article ">Figure 13
<p>(<b>a,b</b>) SEM micrograph of the wear surface of the Al<sub>2</sub>O<sub>3</sub> ball after the tribological test.</p> Full article ">
11 pages, 3480 KiB  
Article
Quasi-2D SnO2 Thin Films for Gas Sensors: Chemoresistive Response and Temperature Effect on Adsorption of Analytes
by Alexander A. Petrunin and Olga E. Glukhova
Materials 2023, 16(1), 438; https://doi.org/10.3390/ma16010438 - 3 Jan 2023
Cited by 4 | Viewed by 1751
Abstract
We performed in silico calculations of electrical conductivity of quasi-2D SnO2 thin films with a (110) surface–prospect material for sensitive element of gas sensors. Electronic structure, charge transfer and chemoresistive response of quasi-2D SnO2 thin films during adsorption of alcohol molecules [...] Read more.
We performed in silico calculations of electrical conductivity of quasi-2D SnO2 thin films with a (110) surface–prospect material for sensitive element of gas sensors. Electronic structure, charge transfer and chemoresistive response of quasi-2D SnO2 thin films during adsorption of alcohol molecules (ethanol, methanol, isopropanol and butanol) and ketones (acetone, cyclopentanone and cyclohexanone) were calculated. It was found that the electrical conductivity of quasi-2D SnO2 thin films decreases within 4–15% during adsorption of analytes. The influence of temperature on the concentration of analytes on the surface of quasi-2D SnO2 thin films was explored in dependence analyte’s type. Full article
(This article belongs to the Special Issue Recent Progresses in Thermoelectric Materials)
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<p>The atomic structure (<b>a</b>) and the DOS plot (<b>b</b>) of the SnO<sub>2</sub> 3D crystal and quasi-2D film (in the blue box—unit cell of the film, yellow—marked tin atoms, red—oxygen). The fragment of a 5 × 5 × 1 unit cells film quasi 2D film (<b>c</b>).</p> Full article ">Figure 2
<p>The supercells of quasi-2D SnO<sub>2</sub> films with landed alcohols and ketones (<b>a</b>) and their electronic characteristics: the DOS plots (<b>b</b>,<b>c</b>) and the electron transmission functions (<b>d</b>,<b>e</b>) (black arrows indicate the positions of the Fermi level after planting of various analytes).</p> Full article ">Figure 3
<p>The diagrams of the Fermi energy (<b>a</b>), the alcohol–surface binding energy (<b>b</b>), the values of the charge transfer from the alcohol to the surface (<b>c</b>) and the magnitude of the chemoresistive response S of the quasi-2D SnO<sub>2</sub> thin films during adsorption of alcohols (<b>d</b>).</p> Full article ">Figure 4
<p>The diagrams of the Fermi energy (<b>a</b>), the ketone–surface binding energy (<b>b</b>), the values of the charge transfer from the ketone to the surface (<b>c</b>) and the magnitude of the chemoresistive response S of the SnO<sub>2</sub> film during adsorption of ketones (<b>d</b>).</p> Full article ">Figure 5
<p>Energy profiles of physical adsorption of the ketone (<b>a</b>) and alcohol (<b>b</b>) molecules on the surface of the SnO<sub>2</sub> film and the density of adsorbed analytes per unit area (<b>c</b>).</p> Full article ">
21 pages, 9022 KiB  
Article
Near-Infrared (NIR) Silver Sulfide (Ag2S) Semiconductor Photocatalyst Film for Degradation of Methylene Blue Solution
by Zahrah Ramadlan Mubarokah, Norsuria Mahmed, Mohd Natashah Norizan, Ili Salwani Mohamad, Mohd Mustafa Al Bakri Abdullah, Katarzyna Błoch, Marcin Nabiałek, Madalina Simona Baltatu, Andrei Victor Sandu and Petrica Vizureanu
Materials 2023, 16(1), 437; https://doi.org/10.3390/ma16010437 - 3 Jan 2023
Cited by 4 | Viewed by 2621
Abstract
A silver sulfide (Ag2S) semiconductor photocatalyst film has been successfully synthesized using a solution casting method. To produce the photocatalyst films, two types of Ag2S powder were used: a commercialized and synthesized powder. For the commercialized powder (CF/comAg2 [...] Read more.
A silver sulfide (Ag2S) semiconductor photocatalyst film has been successfully synthesized using a solution casting method. To produce the photocatalyst films, two types of Ag2S powder were used: a commercialized and synthesized powder. For the commercialized powder (CF/comAg2S), the Ag2S underwent a rarefaction process to reduce its crystallite size from 52 nm to 10 nm, followed by incorporation into microcrystalline cellulose using a solution casting method under the presence of an alkaline/urea solution. A similar process was applied to the synthesized Ag2S powder (CF/syntAg2S), resulting from the co-precipitation process of silver nitrate (AgNO3) and thiourea. The prepared photocatalyst films and their photocatalytic efficiency were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy (UV-Vis). The results showed that the incorporation of the Ag2S powder into the cellulose films could reduce the peak intensity of the oxygen-containing functional group, which indicated the formation of a composite film. The study of the crystal structure confirmed that all of the as-prepared samples featured a monoclinic acanthite Ag2S structure with space group P21/C. It was found that the degradation rate of the methylene blue dye reached 100% within 2 h under sunlight exposure when using CF/comAg2S and 98.6% for the CF/syntAg2S photocatalyst film, and only 48.1% for the bare Ag2S powder. For the non-exposure sunlight samples, the degradation rate of only 33–35% indicated the importance of the semiconductor near-infrared (NIR) Ag2S photocatalyst used. Full article
(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)
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<p>Schematic illustration of sequence process to synthesize the samples.</p> Full article ">Figure 2
<p>Illustrated scheme of the rarefaction process of commercial semiconductor Ag<sub>2</sub>S.</p> Full article ">Figure 3
<p>Prepared cellulose films: (<b>a</b>) CF/comAg<sub>2</sub>S1, (<b>b</b>) CF/comAg<sub>2</sub>S2, (<b>c</b>) CF/comAg<sub>2</sub>S3, (<b>d</b>) CF/syntAg<sub>2</sub>S1, (<b>e</b>) CF/syntAg<sub>2</sub>S2, and (<b>f</b>) CF/syntAg<sub>2</sub>S3.</p> Full article ">Figure 4
<p>X-ray diffraction spectrum of synthesized Ag<sub>2</sub>S.</p> Full article ">Figure 5
<p>X-ray diffraction spectra of: (<b>a</b>) database of Ag<sub>2</sub>S (ICDD No. 00-009-0422), (<b>b</b>) database of cellulose (ICDD No. 00-050-2241), (<b>c</b>) CF/syntAg<sub>2</sub>S1, (<b>d</b>) CF/syntAg<sub>2</sub>S2, and (<b>e</b>) CF/syntAg<sub>2</sub>S3.</p> Full article ">Figure 6
<p>ATR—FTIR spectra of: (<b>a</b>,<b>g</b>) cellulose, (<b>b</b>) CF/comAg<sub>2</sub>S1, (<b>c</b>) CF/comAg<sub>2</sub>S2, (<b>d</b>) CF/comAg<sub>2</sub>S3, (<b>e</b>,<b>f</b>) inset CF/comAg<sub>2</sub>S graph, (<b>h</b>) CF/syntAg<sub>2</sub>S1, (<b>i</b>) CF/syntAg<sub>2</sub>S2, (<b>j</b>) CF/syntAg<sub>2</sub>S3, and (<b>k</b>,<b>l</b>) inset CF/syntAg<sub>2</sub>S graph.</p> Full article ">Figure 7
<p>Predicted mechanism reaction between methylene blue and cellulose.</p> Full article ">Figure 8
<p>(<b>a</b>) Degradation ratio of MB with Ag<sub>2</sub>S commercial as a catalyst; (<b>b</b>) The concentration of MB after photocatalytic activity using CF/comAg<sub>2</sub>S samples; (<b>c</b>) Degradation ratio of MB with synthesized Ag<sub>2</sub>S as a catalyst; (<b>d</b>) The concentration of MB after photocatalytic activity employing CF/syntAg<sub>2</sub>S samples.</p> Full article ">
14 pages, 8536 KiB  
Article
The Effect of B4C Powder on Properties of the WAAM 2319 Al Alloy
by Xueping Song, Jinke Niu, Jiankang Huang, Ding Fan, Shurong Yu, Yuanjun Ma and Xiaoquan Yu
Materials 2023, 16(1), 436; https://doi.org/10.3390/ma16010436 - 3 Jan 2023
Cited by 5 | Viewed by 2188
Abstract
With ER2319 and B4C powder as feedstocks and additives, respectively, a wire arc additive manufacturing (WAAM) system based on double-pulse melting electrode inert gas shielded welding (DP-MIG) was used to fabricate single-pass multilayer 2319 aluminum alloy. The results showed that, compared [...] Read more.
With ER2319 and B4C powder as feedstocks and additives, respectively, a wire arc additive manufacturing (WAAM) system based on double-pulse melting electrode inert gas shielded welding (DP-MIG) was used to fabricate single-pass multilayer 2319 aluminum alloy. The results showed that, compared with additive manufacturing component without B4C, the addition of which can effectively reduce the grain size (from 43 μm to 25 μm) of the tissue in the deposited layer area and improve its mechanical properties (from 231 MPa to 286 MPa). Meanwhile, the mechanical properties are better in the transverse than in the longitudinal direction. Moreover, the strengthening mechanism of B4C on the mechanical properties of aluminum alloy additive manufacturing mainly includes dispersion strengthening from fine and uniform B4C granular reinforcing phases and fine grain strengthening from the grain refinement of B4C. These findings shed light on the B4C induced grain refinement mechanism and improvement of WAAM 2319 Al alloy. Full article
(This article belongs to the Special Issue Additive Manufacturing (AM) of Metal Alloys: Microstructure and Mechanical Performance)
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<p>DP-MIG aluminum alloy powder feeding additive manufacturing. (<b>a</b>) schematic diagram of the DP-MIG-WAAM process, (<b>b</b>) structure of experimental equipment.</p> Full article ">Figure 2
<p>Specimen preparation (<b>a</b>) schematic diagram of specimen preparation, (<b>b</b>) specimen preparation dimensions.</p> Full article ">Figure 3
<p>Forming of aluminum alloy additive manufacturing under different melting rates. (<b>a</b>) 120 mm/min, (<b>b</b>) 130 mm/min, (<b>c</b>) 140 mm/min, (<b>d</b>) 150 mm/min.</p> Full article ">Figure 4
<p>Microstructure of B<sub>4</sub>C particle with different deposition rates. (<b>a</b>) 120 mm/min, (<b>b</b>) 130 mm/min, (<b>c</b>) 140 mm/min, (<b>d</b>) 150 mm/min, (<b>e</b>) 140 mm/min-B<sub>4</sub>C.</p> Full article ">Figure 5
<p>XRD analysis of different deposition rates (<b>a</b>) 120 mm/min, (<b>b</b>) 130 mm/min, (<b>c</b>) 140 mm/min, (<b>d</b>) 140 mm/min-B<sub>4</sub>C.</p> Full article ">Figure 6
<p>Macroscopic morphology and energy spectrum analysis of B<sub>4</sub>C powders. (<b>a</b>) 50 μm (<b>b</b>) 60 μm (<b>c</b>) 70 μm.</p> Full article ">Figure 7
<p>Microstructure and EDS composition analysis of B<sub>4</sub>C-free powdered aluminum alloy deposited parts (<b>a</b>) SEM analysis, (<b>b</b>–<b>e</b>) EDS analysis.</p> Full article ">Figure 8
<p>Microstructure and EDS composition analysis of deposited aluminum alloy parts with B<sub>4</sub>C powder. (<b>a</b>) SEM analysis, (<b>b</b>–<b>e</b>) EDS analysis.</p> Full article ">Figure 9
<p>Microhardness values at different deposition rates with B<sub>4</sub>C powder.</p> Full article ">Figure 10
<p>Stress–strain curves for aluminum alloys in the deposited state (<b>a</b>) transverse direction, (<b>b</b>) longitudinal direction.</p> Full article ">Figure 11
<p>Variation of specimen layer width at different melting rates (<b>a</b>) number of specimen layers and width between layers, (<b>b</b>) deposition rate and average width and height.</p> Full article ">Figure 12
<p>Sidewall morphology and its roughness at different deposition rates.</p> Full article ">Figure 13
<p>Effect of different deposition rates and addition of B<sub>4</sub>C particle on grain size.</p> Full article ">Figure 14
<p>Fracture profile of deposited aluminum alloy tensile specimens in transverse direction (<b>a</b>,<b>b</b>) 140 mm/min, (<b>c</b>,<b>d</b>) 140 mm/min-B<sub>4</sub>C.</p> Full article ">Figure 15
<p>Fracture profile of deposited aluminum alloy tensile specimens in longitudinal direction. (<b>a</b>,<b>b</b>) 140 mm/min, (<b>c</b>,<b>d</b>) 140 mm/min-B<sub>4</sub>C.</p> Full article ">
19 pages, 13628 KiB  
Article
Gas Atomization of Duplex Stainless Steel Powder for Laser Powder Bed Fusion
by Chengsong Cui, Felix Stern, Nils Ellendt, Volker Uhlenwinkel, Matthias Steinbacher, Jochen Tenkamp, Frank Walther and Rainer Fechte-Heinen
Materials 2023, 16(1), 435; https://doi.org/10.3390/ma16010435 - 3 Jan 2023
Cited by 5 | Viewed by 2438
Abstract
Duplex stainless steel powders for laser additive manufacturing have not been developed extensively. In this study, the melts of a super duplex stainless steel X2CrNiMoCuWN25-7-4 (AISI F55, 1.4501) were atomized with different process gases (Ar or N2) at different atomization gas [...] Read more.
Duplex stainless steel powders for laser additive manufacturing have not been developed extensively. In this study, the melts of a super duplex stainless steel X2CrNiMoCuWN25-7-4 (AISI F55, 1.4501) were atomized with different process gases (Ar or N2) at different atomization gas temperatures. The process gas N2 in the melting chamber leads to a higher nitrogen dissolution in the steel and a higher nitrogen content of the atomized powders. The argon-atomized powders have more gas porosity inside the particles than the nitrogen-atomized powders. In addition, the higher the atomization gas temperature, the finer the powder particles. The duplex stainless steel powders showed good processability during PBF-LB/M (Laser powder bed fusion). The gas entrapment in the powder particles, regardless of the gas chemistry and the gas content, appears to have a negligible effect on the porosity of the as-built parts. Full article
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<p>(<b>a</b>) Calculated nitrogen solubility in the melt of the super duplex stainless steel X2CrNiMoCuWN25-7-4 at different melt temperatures and nitrogen partial pressures, and (<b>b</b>) measured nitrogen and oxygen content of the atomized powders.</p> Full article ">Figure 2
<p>Particle size distributions of the X2CrNiMoCuWN25-7-4 powder atomized with different process gases and gas temperatures. (<b>a</b>) Powder fraction &lt; 200 µm; (<b>b</b>) powder fraction 20–63 µm.</p> Full article ">Figure 3
<p>Shape factors of the X2CrNiMoCuWN25-7-4 powder atomized with different process gases (powder fraction 20–63 µm). (<b>a</b>) Circularity; (<b>b</b>) aspect ratio.</p> Full article ">Figure 4
<p>SEM images of gas atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, at low magnification).</p> Full article ">Figure 5
<p>SEM images of gas atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, at high magnification).</p> Full article ">Figure 6
<p>Light micrograph of gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, polished sections).</p> Full article ">Figure 7
<p>XRM images of gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 1.56 µm).</p> Full article ">Figure 7 Cont.
<p>XRM images of gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 1.56 µm).</p> Full article ">Figure 8
<p>3D-View of porosity of gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 1.56 µm). Top left: N<sub>2</sub>/N<sub>2</sub>-RT; Top right: N<sub>2</sub>/N<sub>2</sub>-330 °C; Bottom left: Ar/Ar-RT; Bottom right: Ar/Ar-330 °C.</p> Full article ">Figure 9
<p>Top view of porosity of gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 1.56 µm). Top left: N<sub>2</sub>/N<sub>2</sub>-RT; Top right: N<sub>2</sub>/N<sub>2</sub>-330 °C; Bottom left: Ar/Ar-RT; Bottom right: Ar/Ar-330 °C.</p> Full article ">Figure 10
<p>Pore density distribution of nitrogen and argon gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 1.56 µm) based on XRM measurements.</p> Full article ">Figure 11
<p>Shape of porosity of gas-atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 1.56 µm) (<b>a</b>) under N<sub>2</sub>/N<sub>2</sub> at RT; (<b>b</b>) under N<sub>2</sub>/N<sub>2</sub> at 330 °C; (<b>c</b>) Ar/Ar at RT; and (<b>d</b>) under Ar/Ar at 330 °C.</p> Full article ">Figure 12
<p>Stereo microscopy of the cubic samples (4 × 4 × 5 mm<sup>3</sup>) built with the various atomized X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm). The laser power was 250 W for all the samples, and the laser scan speed was varied from 600 mm/s to 1000 mm/s. The building direction is upward. The vertical sections of the samples were ground and polished for optical metallography.</p> Full article ">Figure 13
<p>µCT Images of the cylindrical samples (Ø4 × 6 mm<sup>3</sup>) built with the different X2CrNiMoCuWN25-7-4 powders (particle size 20–63 µm, voxel size 7.99 µm) atomized with (<b>a</b>) N<sub>2</sub>/N<sub>2</sub> at RT; (<b>b</b>) N<sub>2</sub>/N<sub>2</sub> at 330 °C; and (<b>c</b>) Ar/Ar at 330 °C. The laser power was 250 W, and the laser scan speed was 800 mm/s. The building direction is upward.</p> Full article ">
17 pages, 5144 KiB  
Article
Design of Real-Time Extremum-Seeking Controller-Based Modelling for Optimizing MRR in Low Power EDM
by Mohamed Rabik Mohamed Ismail, Muthuramalingam Thangaraj, Panagiotis Karmiris-Obratański, Emmanouil Papazoglou and Nikolaos Karkalos
Materials 2023, 16(1), 434; https://doi.org/10.3390/ma16010434 - 3 Jan 2023
Cited by 10 | Viewed by 1679
Abstract
Electric discharge machining (EDM) is one of the non-conventional machining processes that supports machining for high-strength and wear-resistant materials. It is a challenging task to select the process parameters in real-time to maximize the material removal rate since real-time process trials are expensive [...] Read more.
Electric discharge machining (EDM) is one of the non-conventional machining processes that supports machining for high-strength and wear-resistant materials. It is a challenging task to select the process parameters in real-time to maximize the material removal rate since real-time process trials are expensive and the EDM process is stochastic. For the ease of finding process parameters, a modelling of the EDM process is proposed. Due to the non-linear relationship between the material removal rate (MRR) and discharge time, a model-free adaptive extremum-seeking controller (ESC) is proposed in the feedback path of the EDM process for finding an optimal value of the discharge time at which the maximum material removal rate can be achieved. The results of the model show a performance that is closer to the actual process by choosing steel workpieces and copper electrodes. The proposed model offers a lower error rate when compared with actual experimental process data. When compared to manual searching for an optimal point, extreme seeking online searching performed better as per the experimental results. It was observed that the experimental validation also proved that the ESC can produce a large MRR by tracking the extremum control. The present study has been limited to only the MRR, but it is also possible to implement such algorithms for more than one response parameter optimization in future studies. In such cases the performance measures of the process could be further enhanced, which could be used for a real-time complex die- and mold-making process using EDM. Full article
(This article belongs to the Special Issue Advanced Machining Technology for Modern Engineering Materials)
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<p>Functional block diagram of the proposed system.</p> Full article ">Figure 2
<p>Proposed low-power EDM with ESC controller in feedback path.</p> Full article ">Figure 3
<p>Gap voltage and current waveforms during the EDM process (<b>a</b>,<b>b</b>). For the spark frequency (F<sub>s</sub>) = 17.24 KHz, and (<b>c</b>,<b>d</b>) for the spark frequency (F<sub>s</sub>) = 100 KHz.</p> Full article ">Figure 4
<p>The model circuit and current path (solid lines) in the (<b>a</b>) ignition phase, (<b>b</b>) discharge phase and (<b>c</b>) recovery phase.</p> Full article ">Figure 5
<p>Non-linear <span class="html-italic">MRR</span> and spark frequency against the discharge time.</p> Full article ">Figure 6
<p>Methodology of extremum-seeking control for the EDM process. (<b>a</b>) Extremum-seeking control structure in a closed loop. (<b>b</b>) A detailed schematic of the proposed extremum-seeking control for the EDM process. (<b>c</b>) A detailed schematic of the proposed extremum-seeking control for the EDM process.</p> Full article ">Figure 7
<p><span class="html-italic">Q</span><sub>2</sub> and <span class="html-italic">Q</span><sub>3</sub> MOSFETS ON/OFF condition.</p> Full article ">Figure 8
<p>Material removal rate (<span class="html-italic">MRR</span>) comparison of the actual process and simulated modelling.</p> Full article ">Figure 9
<p>Optimal perturb frequency <math display="inline"><semantics> <mi>ω</mi> </semantics></math> searching for fast settling with a gap current of 8.5 A and (<b>a</b>) <span class="html-italic">ω</span> = 50 rad/s, (<b>b</b>) <span class="html-italic">ω</span> = 100 rad/s, (<b>c</b>) <span class="html-italic">ω</span> = 250 rad/s, and (<b>d</b>) <span class="html-italic">ω</span> = 500 rad/s.</p> Full article ">Figure 10
<p>Comparison of discrete manual searching (<b>left</b>) and extremum-seeking optimal searching (<b>right</b>) for gap currents (<b>a</b>) 8.5 A, (<b>b</b>) 12.5 A, (<b>c</b>) 25 A, (<b>d</b>) 36 A, and (<b>e</b>) 50 A.</p> Full article ">Figure 11
<p><span class="html-italic">MRR</span> comparison of manual and ESC searching.</p> Full article ">Figure 12
<p>(<b>a</b>) EDM arrangement and (<b>b</b>) machine surface using SEM.</p> Full article ">
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