Journal Description
Coatings
Coatings
is an international, peer-reviewed, open access journal on coatings and surface engineering published monthly online by MDPI. The Korean Tribology Society (KTS) is affiliated with Coatings and its members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Materials Science, Coatings & Films) / CiteScore - Q2 (Surfaces, Coatings and Films)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 13.8 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Sections: published in 14 topical sections.
- Testimonials: See what our editors and authors say about Coatings.
Impact Factor:
3.4 (2022);
5-Year Impact Factor:
3.4 (2022)
Latest Articles
Hardness and Wettability Characteristics of Electrolytically Produced Copper Composite Coatings Reinforced with Layered Double Oxide (Fe/Al LDO) Nanoparticles
Coatings 2024, 14(6), 740; https://doi.org/10.3390/coatings14060740 - 11 Jun 2024
Abstract
The lab-made ferrite-aluminium layered double oxide (Fe/Al LDO) nanoparticles were used as reinforcement in the production of copper matrix composite coatings via the electrodeposition route in this study. The Cu coatings electrodeposited galvanostatically without and with low concentrations of Fe/Al LDO nanoparticles were
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The lab-made ferrite-aluminium layered double oxide (Fe/Al LDO) nanoparticles were used as reinforcement in the production of copper matrix composite coatings via the electrodeposition route in this study. The Cu coatings electrodeposited galvanostatically without and with low concentrations of Fe/Al LDO nanoparticles were characterized by SEM (morphology), AFM (topography and roughness), XRD (phase composition and texture), Vickers microindentation (hardness), and the static sessile drop method (wettability). All Cu coatings were fine-grained and microcrystalline with a (220) preferred orientation, with a tendency to increase the grain size, the roughness, and this degree of the preferred orientation with increasing the coating thickness. The cross-section analysis of coatings electrodeposited with Fe/Al LDO nanoparticles showed their uniform distribution throughout the coating. Hardness analysis of Cu coatings performed by application of the Chicot-Lesage (C-L) composite hardness model showed that Fe/Al LDO nanoparticles added to the electrolyte caused a change of the composite system from “soft film on hard cathode” into “hard film on soft cathode” type, confirming the successful incorporation of the nanoparticles in the coatings. The increase in roughness had a crucial effect on the wettability of the coatings, causing a change from hydrophilic reinforcement-free coatings to hydrophobic coatings obtained with incorporated Fe/Al LDO nanoparticles.
Full article
(This article belongs to the Special Issue Advances in Electrodeposited Composite Coatings: Diversity, Applications and Challenges)
Open AccessArticle
Preparation of Fe3O4/NiO Nanomaterials by Electrodeposition and Their Adsorption Performance for Fluoride Ions
by
Hongbin Zhang, Zhiping Li, Chunyang Ma, Hongxin He, Lixin Wei and Fafeng Xia
Coatings 2024, 14(6), 739; https://doi.org/10.3390/coatings14060739 - 11 Jun 2024
Abstract
The high concentration of fluoride ions in industrial wastewater poses a threat to both human safety and the ecological environment. In this paper, three types of magnetic NiO nanomaterial (MNN) with nickel–iron ratios of 3:1, 2:1, and 1:2 were successfully prepared using the
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The high concentration of fluoride ions in industrial wastewater poses a threat to both human safety and the ecological environment. In this paper, three types of magnetic NiO nanomaterial (MNN) with nickel–iron ratios of 3:1, 2:1, and 1:2 were successfully prepared using the electrodeposition technique to eliminate fluoride ions (F−) from industrial wastewater. The surface morphology, phase composition, and chemical structure of the nanomaterials were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results demonstrate the MNN material’s exceptional adsorption capabilities for fluoride ions (F−) at a nickel–iron ratio of 3:1, with a maximum adsorption capacity of up to 58.3 mg/g. The adsorption process of fluoride on the MNN material was further examined using Langmuir and pseudo-second-order kinetic models, revealing predominantly monolayer adsorption and chemisorption characteristics. When the amount of FeSO4•9H2O added is minimal, only the distinctive peaks of NiO are visible in the product’s spectrum. However, as the Ni/Fe ratio decreases, characteristic peaks of Fe3O4 crystals begin to appear and gradually intensify, indicating an increase in Fe3O4 content within the MNN material. Additionally, the pH level significantly affects the adsorption of fluoride ions (F−) onto the MNN material, with the highest adsorption capacity observed at pH 7.
Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
Open AccessArticle
Thickness Distribution Measurement for Spin-Coated and Inkjet-Printed Transparent Organic Layers Using a UV Light Extinction Image Method
by
Jun Ho Yu, Hyung Tae Kim, Dal Won Lee, Gyu-Young Yun, Seong Woo Lee, Jong Hwan Kong and Jun Young Hwang
Coatings 2024, 14(6), 738; https://doi.org/10.3390/coatings14060738 - 11 Jun 2024
Abstract
Organic thin layers are highlighted as crucial components of flexible and printed electronic products due to their ability to provide mechanical flexibility in various applications, such as flexible displays and wearable electronics. The thickness and uniformity of these layers are crucial factors that
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Organic thin layers are highlighted as crucial components of flexible and printed electronic products due to their ability to provide mechanical flexibility in various applications, such as flexible displays and wearable electronics. The thickness and uniformity of these layers are crucial factors that influence surface planarization, mechanical stress relief, and the enhancement of optical performance. Therefore, accurate measurement of their thickness distribution is essential. In this study, the two-dimensional thickness distributions of spin-coated and inkjet-printed organic microlayers on glass substrates were measured using a light extinction image method. Using a 300 nm wavelength light source and a camera, images with an area of 4872 × 3640 μm2 and an XY resolution of 3.5 μm were obtained through single measurements. The precision of the measured thickness could be enhanced to several nanometers through pixel binning and image overlaying. Using this light extinction measurement system, we measured and analyzed the thickness distribution of the center and edge of the spin-coated and inkjet-printed organic layers with thicknesses of several micrometers.
Full article
(This article belongs to the Special Issue Printed Functional Thin Films for Electronic, Optoelectronic and Sensing Applications)
Open AccessArticle
Revealing the Microstructure Evolution and Mechanical Properties of Al2O3-Reinforced FCC-CoCrFeMnNi Matrix Composites Fabricated via Gas Atomization and Spark Plasma Sintering
by
Pan Dai, Runjie Chen, Xian Luo, Lin Yang, Lei Wen, Tao Tu, Chen Wang, Wenwen Zhao and Xianghong Lv
Coatings 2024, 14(6), 737; https://doi.org/10.3390/coatings14060737 - 9 Jun 2024
Abstract
In the present work, novel Al2O3 particles were used to reinforce heterogeneous CoCrFeMnNi high-entropy alloy (HEA) matrix composites with nano- (5.0 wt.%) and nano- + micro- (5.0 wt.% + 10.0 wt.%) specimens. Al2O3 particles were fabricated via
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In the present work, novel Al2O3 particles were used to reinforce heterogeneous CoCrFeMnNi high-entropy alloy (HEA) matrix composites with nano- (5.0 wt.%) and nano- + micro- (5.0 wt.% + 10.0 wt.%) specimens. Al2O3 particles were fabricated via gas atomization and spark plasma sintering. The microstructure evolution and properties, i.e., density, hardness, and room temperature compression, were systematically investigated. The results indicate that the concentration of the Cr element in the pure CoCrFeMnNi HEA and the HEA matrix composite can be effectively reduced by using a gas-atomized HEA powder as the matrix. The formation of an impurity phase can also be inhibited, while the distribution uniformity of matrix elements can be improved. The composites prepared via gas-atomized powders formed a network microstructure composed of continuous Al2O3-rich regions and isolated Al2O3-poor regions, exhibiting good plasticity and improved density. The relative densities of the pure HEA, nano- (5.0 wt.%), and nano- + micro- (5.0 wt.% + 10.0 wt.%) composites were 98.9%, 97%, and 94.1%, respectively. The results demonstrate a significant improvement in the relative densities compared to the values (97.2%, 95.7%, and 93.8%) of the composites prepared via mechanical alloying. In addition, compared to the compressive fracture strains of nano- (5.0 wt.%) and nano- + micro- (5.0 wt.% + 10.0 wt.%) composites based on the mechanically alloyed HEA powder, the values of the nano- (5.0 wt.%) and nano- + micro- (5.0 wt.% + 10.0 wt.%) specimens prepared via gas atomization and spark plasma sintering increased by 80% and 67%, respectively.
Full article
(This article belongs to the Special Issue Structural, Mechanical and Tribological Properties of Hard Coatings)
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Open AccessArticle
Extending the Shelf-Life of Nectarines through Fish Gelatin/Cellulose Nanocrystals/Cinnamon Essential Oil-Based Edible Coatings
by
Reza Akbari, Javad Tarighi, Mahsa Sadat Razavi, Mohammad Tahmasebi, Daniele Carullo and Stefano Farris
Coatings 2024, 14(6), 736; https://doi.org/10.3390/coatings14060736 - 8 Jun 2024
Abstract
The effect of bacterial cellulose nanocrystal–fish gelatin/cinnamon essential oil (BCNCs–FGelA/CEO) nanocoatings containing different concentrations of essential oil (1.2, 1.8, and 2.4 mL/L) on reducing the ripening and aging processes of ‘Red Gold’ nectarine fruit during cold storage (60 days, 4 °C)
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The effect of bacterial cellulose nanocrystal–fish gelatin/cinnamon essential oil (BCNCs–FGelA/CEO) nanocoatings containing different concentrations of essential oil (1.2, 1.8, and 2.4 mL/L) on reducing the ripening and aging processes of ‘Red Gold’ nectarine fruit during cold storage (60 days, 4 °C) was studied. As a general trend, the application of the coating delayed the ripening process, and increasing the concentration of essential oil was effective in improving the coating efficacy. After 60 days, the lowest values of weight loss (6.93%), peroxidase and polyphenol oxidase activity (11.49 and 0.48 abs min−1 g−1, respectively), soluble solid content (14.56%), and pH (4.17) were detected for samples covered with the BCNCs–FGelA coatings containing the highest tested CEO concentration, whereas the maximum values of the same parameters (20.68%, 18.74 and 0.76 abs min−1 g−1, 17.93%, and 4.39, respectively) were found in the uncoated samples. In addition, increasing the concentration of the essential oil resulted in a better preservation of the firmness, ascorbic acid, and total acidity of the samples. Finally, the respiration rate and ethylene production of coated samples were lower than those detected in uncoated samples, though some differences arose depending on the amount of CEO loaded in the coatings. This study showed the capability of BCNCs–FGelA/CEO coatings to increase the cold storage period and preserve the quality of ‘Red Gold’ nectarine fruit, thereby reducing losses and increasing economic efficiency in the fruit industry.
Full article
(This article belongs to the Special Issue Functional Coatings in Postharvest Fruit and Vegetables)
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Open AccessArticle
In Situ Synthesis and Tribological Characterization of TiC–Diamond Composites: Effect of the Counterface Material on Wear Rate and Mechanism
by
Yuqi Chen, Jin Li, Liang Li, Ming Han and Junbao He
Coatings 2024, 14(6), 735; https://doi.org/10.3390/coatings14060735 - 8 Jun 2024
Abstract
TiC bonded diamond composites were prepared from a mixture of Ti, graphite, and diamond powders as raw materials, with Si as sintering additives, through high-temperature and high-pressure (HTHP) technology. The reaction between Ti and graphite under 4.5–5 GPa pressure and 1.7–2.3 kW output
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TiC bonded diamond composites were prepared from a mixture of Ti, graphite, and diamond powders as raw materials, with Si as sintering additives, through high-temperature and high-pressure (HTHP) technology. The reaction between Ti and graphite under 4.5–5 GPa pressure and 1.7–2.3 kW output power can produce TiC as the main phase. The diamond particles are surrounded by TiC, and the interface is firmly bonded. The coefficient of friction (COF) of TiC–diamond composites with POM and PP balls decreases with increasing load for a specific friction velocity. However, the COF of TiC–diamond composites with agate, Cu and Al balls increases with the rising load because of the enhanced adhesive wear effect. The COF of PP, Cu and Al balls slightly increases with the increase in friction velocity at a certain load. SEM results show that the surface of agate balls has rough, pear-shaped grooves and shallow scratches. The scratches on the surface of POM balls are wrinkled. The PP balls have pear-shaped groove scratches on their wear surfaces. The wear mechanism of TiC–diamond composites with Cu ball pairs is primarily adhesive wear. The abrasion of TiC–diamond composites with Cu ball pairs remains almost unchanged as the load increases. However, the depth and width of the pear-shaped grooves on the wear surface of TiC–diamond composites are significantly increased. This phenomenon may be attributed to the high rotational speed, which helps to remove the residual abrasive debris from the friction grooves. As a result, there is a decrease in both the depth and width of the pear-shaped grooves, leading to a smoother overall surface. The wear mechanism of TiC–diamond composites with Al ball pairs is abrasive wear, which increases with an increasing load. When the load is constant, as the speed increases, the wear morphology of TiC–diamond composites with Al ball pairs transitions from rough to smooth and then back to rough again. This phenomenon may be attributed to the wear mechanism at low speeds being groove wear and adhesive wear. As the speed increases, the wear particles are more easily removed from the wear track, leading to a reduction in abrasiveness. As the speed increases, the wear surface becomes roughened by a combination of grooves and dispersed wear debris. This can be attributed to the increased dynamic interaction between surfaces caused by higher speed, resulting in a combination of abrasive and adhesive wear. In addition, Cu and Al ball wear debris appeared as irregular particles that permeated and adhered to the surface of the TiC phase among the diamond particles. The results suggest that TiC–diamond composites are a very promising friction material.
Full article
(This article belongs to the Section Tribology)
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Open AccessArticle
Experimental Study on the Process of Submerged Arc Welding for Nickel-Based WC Flux-Cored Wire on Descaling Roll
by
Chang Li, Lei Feng, Xing Han, Fenghua Luo and Han Sun
Coatings 2024, 14(6), 734; https://doi.org/10.3390/coatings14060734 - 8 Jun 2024
Abstract
Descaling roll is a key component used to remove iron oxide on billet surface in hot rolling production lines, and its surface properties have a significant effect on the quality of hot rolling products. The descaling roll is in bad service condition and
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Descaling roll is a key component used to remove iron oxide on billet surface in hot rolling production lines, and its surface properties have a significant effect on the quality of hot rolling products. The descaling roll is in bad service condition and subjected to the dynamic impact caused by high-pressure water erosion and high temperature billet descaling process for a long time. Under the action of high temperature, strong wear, multi-cycle heat, force, flow and multi-field strong coupling, the surface is prone to wear and corrosion failure, which affects the continuous rolling production. Submerged arc welding provides an effective way to repair and strengthen the descaling roll surface. The content of WC hard phase has a significant effect on welding quality. At the same time, direct submerged arc welding of Ni based WC wire on the descaling roll surface is easy to cause cracks, and a gradient synergistic strengthening effect can be formed by setting the transition bottom layer in welding. At present, there is a lack of experiments related to the preparation of flux-cored wire with different contents and the overlaying for the bottom submerged arc welding. Relevant studies are urgently needed to further reveal the welding process mechanism to provide significant theoretical support for the preparation of wire materials and the improvement of welding quality. In this paper, 30% and 60% WC flux-cored wires were prepared by employing Ni-Cr-B-Si alloy powder as the base powder, and submerged arc welding tests were conducted on the descaling roll, preparing three welding layers, namely 70% NiCrBSi + 30% WC without the bottom layer, 70% NiCrBSi + 30% WC with the bottom layer, and 40% NiCrBSi + 60% WC with the bottom layer. The properties of the welding layer were evaluated by SEM, XRD, EDS, hardness, friction and wear, corrosion and impact experiments. The results show that the WC hard phase added in the filler metal has dissolved and formed a new phase with other elements in the melting pool. The surfacing layer mainly contains Fe-Ni, Cr-C, Fe3Si, Ni3C and other phases. The surfacing layer prepared by a different amount of WC flux-cored wire and the surfacing layer with or without the bottom layer have great differences in microstructure and properties. This study lays a significant theoretical foundation for optimizing the submerged arc welding process and preparing welding materials for the descaling roll and has significant practical significance and application value.
Full article
(This article belongs to the Special Issue Surface Modification, Repairing and Forming of Metallic Materials by Additive Manufacturing)
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Open AccessArticle
The Corrosion Resistance of Tartaric-Sulfuric Acid Anodic Films on the 2024 Al Alloy Sealed Using Different Methods
by
Chao Wang, Shineng Sun, Yunhe Ling, Haifeng Tan and Chunlin He
Coatings 2024, 14(6), 733; https://doi.org/10.3390/coatings14060733 - 8 Jun 2024
Abstract
Tartaric-sulfuric acid anodic (TSA) films were prepared on the surface of the 2024 Al alloy. These films were sealed with cerium salts at 25 °C and 65 °C, hot water, and dichromate. The morphology and corrosion resistance of the anodic films were investigated
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Tartaric-sulfuric acid anodic (TSA) films were prepared on the surface of the 2024 Al alloy. These films were sealed with cerium salts at 25 °C and 65 °C, hot water, and dichromate. The morphology and corrosion resistance of the anodic films were investigated using a field emission scanning electron microscope/energy-dispersive spectrometer, an electrochemical workstation, an acidic spot test, and an immersion test. The results indicated that the surface of the TSA film sealed with cerium salt at 65 °C had a slightly lower cerium content compared to the TSA film sealed at 25 °C. It was found that increasing the sealing temperature of cerium salt could enhance the corrosion resistance of the TSA film. After immersion in a 3.5 wt.% NaCl solution for 336 h, no obvious corrosion pits were observed on the surface of the TSA film sealed at 65 °C, whereas many larger corrosion pits appeared on the surface of the TSA film sealed at 25 °C. The improved corrosion resistance of the TSA film sealed at 65 °C could be attributed to the synergistic effect of cerium oxide deposition and the hydration reaction. The corrosion resistance of the TSA film sealed at 65 °C was significantly better than that of the film sealed with hot water, but it was still lower than that of the TSA film sealed with dichromate.
Full article
(This article belongs to the Special Issue Advanced Corrosion Protection through Coatings and Surface Rebuilding)
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Open AccessArticle
The Influence of Bias Voltage and Gas Pressure on Edge Covering during the Arc-PVD Deposition of Hard Coatings
by
Otmar Zimmer, Tim Krülle and Thomas Litterst
Coatings 2024, 14(6), 732; https://doi.org/10.3390/coatings14060732 - 7 Jun 2024
Abstract
The edge area is especially essential for cutting tools, since this is the contact zone between the work piece and the tool. Hard coatings (PVD or CVD coatings) can protect the edge against wear and they are commonly used. The geometries of the
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The edge area is especially essential for cutting tools, since this is the contact zone between the work piece and the tool. Hard coatings (PVD or CVD coatings) can protect the edge against wear and they are commonly used. The geometries of the cutting edges change during the coating process, with the edge radius increasing. Therefore, the film thickness is limited and the initial radius of the uncoated tool must be smaller than the target radius of the coated edge. A new coating process based on vacuum arc PVD was developed to overcome this limitation. The film growth at the edges can be properly controlled by means of selected coating materials and process conditions. Thus, it is possible to grow edges sharper than the initial edge geometry. Different substrates were coated with different coating systems. Parameters such as the bias voltage, coating pressure, and initial radius were varied within this work. It was found that the application of a bias voltage is crucial for the generation of sharp edges. It was also found that the edge sharpening caused by coatings works best on samples with an initial radius of around 15 µm.
Full article
(This article belongs to the Special Issue Advanced Coating Technology by Physical Vapor Deposition and Applications)
Open AccessArticle
Design of Debondable PU Coating for Degradation on Demand
by
David De Smet and Myriam Vanneste
Coatings 2024, 14(6), 731; https://doi.org/10.3390/coatings14060731 - 7 Jun 2024
Abstract
Polyurethane (PU) coatings are applied on technical textiles for their superior properties. Up to now, PU-coated textiles are not recycled at end of life. Landfilling is still the most occurring way of processing PU waste. Next to looking to sustainable routes for processing
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Polyurethane (PU) coatings are applied on technical textiles for their superior properties. Up to now, PU-coated textiles are not recycled at end of life. Landfilling is still the most occurring way of processing PU waste. Next to looking to sustainable routes for processing PU waste, there is the drive towards bio-based polymers. With this regard, a bio-based trigger degradable PU coating specifically designed for textiles was developed. The PU was characterized via FT-IR, TGA, and DSC. The performance of the coating was assessed by examining the mechanical properties and the resistance to hydrostatic pressure initially and after washing. The developed bio-based PU coatings had a high tensile strength, were waterproof, and had excellent wash fastness at 40 °C. The coating could be easily debonded from the textile by immersion in a tetra-n-butylammoniumfluoride solution. FT-IR and microscopic analysis indicated that the coating was completely removed and that the polyester fabric was not degraded.
Full article
(This article belongs to the Special Issue Surface Modification and Coating Techniques for Polymers)
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Study of the Performance of Laser Melting Wear-Resistant Coatings on TC4 Titanium Alloy Surfaces
by
Gaosheng Wang, Jingang Liu, Jianhua Yang, Sisi Liu, Lei Bu and Jianwen Chen
Coatings 2024, 14(6), 730; https://doi.org/10.3390/coatings14060730 - 7 Jun 2024
Abstract
To improve the wear resistance of TC4 titanium alloy, two types of wear-resistant coatings were applied to the surface using laser melting: Ni60 + 50% WC and d22 powder priming. The phase composition and microstructure of the coatings were characterized by X-ray diffractometry
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To improve the wear resistance of TC4 titanium alloy, two types of wear-resistant coatings were applied to the surface using laser melting: Ni60 + 50% WC and d22 powder priming. The phase composition and microstructure of the coatings were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy spectroscopy (EDS). The mechanical properties of the coating were tested using an HV-1000 micro-Vickers hardness tester, an HRS-2M high-speed reciprocating friction and wear tester, and a WDW-100D electronic universal testing machine. The results show that Ni60 + 50% WC composite coating and d22 priming + (Ni60 + 50% WC) composite coating mainly consist of W2C, TiC, Ni17W3, Ni3Ti, and TixW1−x phases. Compared to the TC4 substrate, the microhardness of both coatings is significantly higher, approximately 2.8 times the microhardness of the substrate. In frictional wear experiments, the average friction factors of the two coatings and the TC4 substrate are 0.476, 0.55, and 0.865, respectively, and the wear of the two coatings is only 0.0559–0.0769 that of the TC4 substrate, with a significant increase in wear resistance, nearly 17 times higher than that of the substrate. The coating shows flaking, shallow abrasion marks, and granular debris, dominated by adhesive wear and fatigue wear, while the TC4 substrate shows more furrows on the surface, dominated by abrasive wear. The shear bond strengths of the Ni60 + 50% WC composite coating and the d22 powder primed + (Ni60 + 50% WC) composite coating were 188.19 MPa and 49.11 MPa, respectively. Conclusion: both coatings significantly improve the hardness and wear resistance of the TC4 titanium alloy substrate surface, with the Ni60 + 50% WC composite coating performing better in hardness, wear resistance, and bond strength.
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(This article belongs to the Special Issue Advanced Surface Technology and Application)
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Open AccessArticle
Experimental Study on Preparation of Tungsten-Carbide-Particle-Reinforced Nickel-Based Alloy Plasma Surfacing Layer on Descaling Roller Surface
by
Lei Feng, Chang Li, Xing Han, Fenghua Luo and Han Sun
Coatings 2024, 14(6), 729; https://doi.org/10.3390/coatings14060729 - 6 Jun 2024
Abstract
The descaling roller is a significant component in steel rolling production. Under harsh service conditions, the descaling roller is subjected to the dynamic impact caused by high-pressure water erosion and a high-temperature billet descaling process for a long time. Under the harsh conditions
[...] Read more.
The descaling roller is a significant component in steel rolling production. Under harsh service conditions, the descaling roller is subjected to the dynamic impact caused by high-pressure water erosion and a high-temperature billet descaling process for a long time. Under the harsh conditions of high temperature, strong wear, multi-cycle heat, force, flow, and multi-field strong coupling, the roller surface is prone to wear and corrosion failure, which affects the production cost and efficiency. Through plasma surfacing technology, a high-performance coating can be applied on the conventional metal surface to effectively improve its surface properties. It is important to carry out experimental research on the surface plasma surfacing of the descaling roller to prolong product life, improve product quality, and save cost. At present, the research on the 42CrMo scaler matrix plasma surfacing of nickel-based alloys with different WC contents is still lacking. In this paper, 70%NiCrBSi+30%WC powder and 40%NiCrBSi+60%WC powder were used as surfacing materials; plasma surfacing experiments were carried out on the 42CrMo matrix; and SEM, XRD, microhardness, friction and wear, and corrosion tests were carried out on the surfacing layer to evaluate the feasibility of preparing an ultra-high-hardness WC-particle-reinforced nickel-based alloy plasma surfacing layer on the descaling roller surface and to explore the WC hard phase dissolution behavior and complex secondary phase formation mechanism. The results show that γ(Fe/Ni), Fe-Ni, FeSi, Fe3C, and M7C3 are the main phases in the Ni/WC plasma surfacing layer. The diffusion and precipitation of elements occur in the molten pool, and complex secondary phases are formed in the surfacing layer. Compared with the 70%NiCrBSi+30%WC surfacing layer, the WC deposition phenomenon of the 40%NiCrBSi+60%WC surfacing layer has been significantly improved and has better hardness, wear resistance, and corrosion resistance. Based on the welding test, the correlation law between powder formulation, welding structure, and surfacing layer properties was revealed in this study, which lays a theoretical foundation for the preparation of high-performance coating on the descaling roller surface and has significant engineering application value and practical significance.
Full article
(This article belongs to the Special Issue Surface Modification, Repairing and Forming of Metallic Materials by Additive Manufacturing)
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Open AccessArticle
UV-Curable Silicone-Modified Polyurethane Acrylates for Food Freshness Monitoring
by
Na He, Hongyu Zhu, Nana Sun, Shaoqing Shi, Libo Xie, Jie Miao, Guoqiao Lai, Meijiang Li and Xiongfa Yang
Coatings 2024, 14(6), 728; https://doi.org/10.3390/coatings14060728 - 6 Jun 2024
Abstract
Intelligent materials for monitoring the condition of the packaged food or its surroundings are highly desired to ensure food safety. In this paper, UV-curable silicone-modified materials for monitoring the freshness of high-protein food such as shrimp and pork were prepared from polyurethane acrylates
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Intelligent materials for monitoring the condition of the packaged food or its surroundings are highly desired to ensure food safety. In this paper, UV-curable silicone-modified materials for monitoring the freshness of high-protein food such as shrimp and pork were prepared from polyurethane acrylates with covalent-grafted neutral red groups and thiol silicone resin. The UV-curable materials exhibited visible pH-sensitive performance and long-term color stability because their color did not change when they were immersed in aqueous solutions with different pH values for 20 min, and the color remained even when they were immersed for over 5 h. The distinctive color variation in the UV coatings makes them suitable as potential pH-sensitive sensors. These pH-sensitive intelligent materials can be applied to monitor the freshness of high-protein food such as shrimp and pork. Additionally, the thermal stability and adhesive properties of the UV-curable materials were also studied. A conclusion can be drawn that the covalent bonding of neutral red groups onto a silicone-modified polymer matrix is an ideal strategy for developing pH-sensitive intelligent materials with good pH stability for monitoring the freshness of high-protein food.
Full article
(This article belongs to the Special Issue Advanced Polymeric Materials and Coatings: Synthesis, Properties and Applications)
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Open AccessArticle
A Comparative Study on the Wear Behavior of Quenched-and-Partitioned Steel (Q&P) and Martensite Steel (Q&T)
by
Jian Zheng, Wei Li and Jie Li
Coatings 2024, 14(6), 727; https://doi.org/10.3390/coatings14060727 - 6 Jun 2024
Abstract
The wear resistance of quenched-and-partitioned steel (Q&P) compared to martensite steel (Q&T) remains unclear. In this research, the wear resistance of Q&P steel and Q&T steel was researched by the means of the abrasive wear (AW) and impact abrasive wear (IAW) tests. The
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The wear resistance of quenched-and-partitioned steel (Q&P) compared to martensite steel (Q&T) remains unclear. In this research, the wear resistance of Q&P steel and Q&T steel was researched by the means of the abrasive wear (AW) and impact abrasive wear (IAW) tests. The results show that abrasive ploughing was the main reason causing the material loss of Q&P and Q&T steel, while Q&T steel was subjected to severe fatigue spalling in the impact abrasive wear tests. Under the abrasive wear test, Q&T steel has better wear resistance due to its higher initial hardness. Under the impact abrasive wear test, Q&P steel has better wear resistance. This is because the formation of the deformed layer, which consists of finer grains and newly formed martensite in the worn subsurface, increased the hardness of the Q&P steel, causing the hardness of the worn subsurface in Q&P steel to be higher than that of Q&T steel. Furthermore, Q&P steel has better resistance to cracks that nucleate and propagate compared to Q&T steel. As a result, less material loss was caused by fatigue spalling in Q&P steel under the impact abrasive wear tests.
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(This article belongs to the Special Issue Advanced Surface Technology and Application)
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Automated Crack Detection in 2D Hexagonal Boron Nitride Coatings Using Machine Learning
by
Md Hasan-Ur Rahman, Bichar Dip Shrestha Gurung, Bharat K. Jasthi, Etienne Z. Gnimpieba and Venkataramana Gadhamshetty
Coatings 2024, 14(6), 726; https://doi.org/10.3390/coatings14060726 - 6 Jun 2024
Abstract
Characterizing defects in 2D materials, such as cracks in chemical vapor deposited (CVD)-grown hexagonal boron nitride (hBN), is essential for evaluating material quality and reliability. Traditional characterization methods are often time-consuming and subjective and can be hindered by the limited optical contrast of
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Characterizing defects in 2D materials, such as cracks in chemical vapor deposited (CVD)-grown hexagonal boron nitride (hBN), is essential for evaluating material quality and reliability. Traditional characterization methods are often time-consuming and subjective and can be hindered by the limited optical contrast of hBN. To address this, we utilized a YOLOv8n deep learning model for automated crack detection in transferred CVD-grown hBN films, using MATLAB’s Image Labeler and Supervisely for meticulous annotation and training. The model demonstrates promising crack-detection capabilities, accurately identifying cracks of varying sizes and complexities, with loss curve analysis revealing progressive learning. However, a trade-off between precision and recall highlights the need for further refinement, particularly in distinguishing fine cracks from multilayer hBN regions. This study demonstrates the potential of ML-based approaches to streamline 2D material characterization and accelerate their integration into advanced devices.
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(This article belongs to the Special Issue Advances in Nanostructured Thin Films and Coatings, 2nd Edition)
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Open AccessArticle
Development of pH Indicator Composite Films Based on Anthocyanins and Neutral Red for Monitoring Minced Meat and Fish in Modified Gas Atmosphere (MAP)
by
Marwa Faisal, Tomas Jacobson, Lene Meineret, Peter Vorup, Heloisa N. Bordallo, Jacob Judas Kain Kirkensgaard, Peter Ulvskov and Andreas Blennow
Coatings 2024, 14(6), 725; https://doi.org/10.3390/coatings14060725 - 6 Jun 2024
Abstract
Fresh meat and fish are widely consumed foods with short and very short shelf lives, respectively. Efficient supply chains and the judicious use of food packaging are the most effective means of extending shelf life and thus reducing food waste and improving food
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Fresh meat and fish are widely consumed foods with short and very short shelf lives, respectively. Efficient supply chains and the judicious use of food packaging are the most effective means of extending shelf life and thus reducing food waste and improving food safety. Food packaging that allows for the use of a modified atmosphere (MAP) is effective in extending the period where the food is both palatable and safe. However, monitoring the state of aging and the onset of spoilage of the product poses challenges. Microbial counts, pH measurements, and sensory evaluations are all informative but destructive and are therefore only useful for monitoring quality via sampling. More attractive would be a technology that can follow the progress of ageing in an individual product while leaving the food packaging intact. Here, we present a pH indicator to be placed inside each package that may be read by the naked eye. It is a colorimetric indicator with a matrix made of pure amylose (AM; 99% linear α-glucans) and cellulose nanofibers (CNFs). Suitable mechanical properties of films cast of the two polysaccharides were achieved via the optimization of the blending ratio. The films were loaded with either of two pH indicators: anthocyanin extracts from red cabbage (RCA) and the synthetic dye neutral red (NR). Mechanical, thermal, permeability, microstructural, and physical properties were tested for all composite films. Films with 35% CNF (35AC-RCA) and (35AC-NR) were selected for further study. Minced meat was packaged under MAP conditions (70% O2 + 30% CO2), while minced fish was packaged under MAP (70% N2 + 30% CO2) and stored at 5 °C for 20 days. Microbial growth, pH, and sensory scores of the minced meat systems differentiated between fresh (0–6 days) and medium-fresh (7–10 days), and minced fish between fresh (0–10 days) and medium-fresh (11–20 days). The total color difference showed that the RCA indicator was able to differentiate between fresh (red) and medium-fresh (pink-red) minced meat, while for minced fish, this indicator discriminated between three stages: fresh (red), medium-fresh (pink-red), and spoiled (pink-blue). The NR indicator failed to discriminate the freshness of either meat or fish under the effect of MAP. Pearson correlation statistical models showed a correlation between color change of the indicator, pH, content of gases, and gas content. In summary, RCA immobilized in an AM + 35% CNF nanocomposite film can monitor the freshness of packaged minced meat/fish under the effect of MAP via color change that may be evaluated with the naked eye.
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(This article belongs to the Special Issue Novel Advances in Food Contact Materials)
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The Effect of Deposition Temperature on TiN Thin Films for the Electrode Layer of 3D Capacitors Prepared by Atomic Layer Deposition
by
Xingyu Chen, Jing Zhang, Lingshan Gao, Faqiang Zhang, Mingsheng Ma and Zhifu Liu
Coatings 2024, 14(6), 724; https://doi.org/10.3390/coatings14060724 - 5 Jun 2024
Abstract
The TiN thin film is considered a promising electrode layer for 3D capacitors. In this study, TiN thin films were prepared on Si substrates using atomic layer deposition (ALD) at various temperatures from 375 °C to 475 °C. The crystallization behavior, microstructure, and
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The TiN thin film is considered a promising electrode layer for 3D capacitors. In this study, TiN thin films were prepared on Si substrates using atomic layer deposition (ALD) at various temperatures from 375 °C to 475 °C. The crystallization behavior, microstructure, and conductance properties of those TiN thin films were investigated. The resistivity of TiN thin films deposited on Si wafers can reach as low as 128 μΩ·cm. TiN thin films showed lower resistivity and worse uniformity with the deposition temperature increasing. In addition, the aging of TiN thin films may weaken the device performance. Optimized deposition parameters were found and full-coverage deposition of thin films on the wall of deep holes with an aspect ratio of approximately 14 has been successfully achieved. The results would be a good reference for the development of 3D capacitors and other microelectronics components.
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(This article belongs to the Special Issue Thin-Film Synthesis, Characterization and Properties)
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Optimum Design of Coaxial Hydraulic Sealing Systems Made from Polytetrafluoroethylene and Its Compounds
by
Andrea Deaconescu and Tudor Deaconescu
Coatings 2024, 14(6), 723; https://doi.org/10.3390/coatings14060723 - 5 Jun 2024
Abstract
Fluidic actuation systems are optimizable as to energy consumption by reducing the friction in the hydraulic cylinders. Polymeric materials with special antifriction properties and good resistance to hydraulic fluids can be deployed to enhance the performance of hydraulic cylinders. Small friction forces can
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Fluidic actuation systems are optimizable as to energy consumption by reducing the friction in the hydraulic cylinders. Polymeric materials with special antifriction properties and good resistance to hydraulic fluids can be deployed to enhance the performance of hydraulic cylinders. Small friction forces can also be ensured by facilitating the hydrodynamic separation of the elements of the friction tribosystem, namely the seal and sealed-off surface, respectively. The study presented in this paper analyzed the hydrodynamic separation phenomenon in hydraulic cylinders with coaxial sealing systems of the pistons. The process underlying the forming of the fluid film between the seal and its contact surface was considered and the formula for calculating film thickness was deduced. This paper presents graphs that describe the variation of the fluid film thickness versus the dimensional and material characteristics of the sealing systems. The study yielded recommendations as to the most adequate polymeric material to be used and the optimum dimensional characteristics of the seal.
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(This article belongs to the Special Issue Friction, Wear, Lubrication and Mechanics of Surfaces and Interfaces)
Open AccessArticle
In Situ Thermal Interactions of Cu-Based Anti-Corrosion Coatings on Steel Implemented by Surface Alloying
by
Huda Hanif Khan, Tong Wang, Lihong Su, Huijun Li, Qiang Zhu, Ana Yang, Zigang Li, Wei Wang and Hongtao Zhu
Coatings 2024, 14(6), 722; https://doi.org/10.3390/coatings14060722 - 5 Jun 2024
Abstract
Incorporating expensive alloying elements into bulk steel for corrosion protection is undesirable, considering that only the surfaces are exposed to aggressive environments. Therefore, this work focused on developing and optimizing a new surface functioning technology through in situ observation of thermal interactions between
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Incorporating expensive alloying elements into bulk steel for corrosion protection is undesirable, considering that only the surfaces are exposed to aggressive environments. Therefore, this work focused on developing and optimizing a new surface functioning technology through in situ observation of thermal interactions between the metallic powders at elevated temperatures. The study revealed that the Cu-Ni powder mixture, with 12.5 wt% Ni, began to melt at 1099.5 °C and was fully melted at 1175 °C, significantly different from the Cu-Ni solid solution and bulk Cu or Ni. As a result of high-temperature reactions, copper penetration of up to 35 µm for pure copper and 55 µm for copper-chromium composite coatings occurred due to liquid metal corrosion. In contrast, the copper-nickel composite coating exhibited a cupronickel solution microstructure with FeNi dendrites and a nickel-rich transition layer. This cupronickel coating, with a chemical composition of 89.3 wt% Cu, 6.2 wt% Ni, and 4.5 wt% Fe, demonstrated uniform thickness, superior surface morphology, and continuous coverage on the steel substrate. Furthermore, the Ni-rich transition layer played a vital role in preventing copper penetration along the grain boundary of the steel matrix while forming a chemical binding between the coating and the substrate. The practicality of the coating was further confirmed through the hot-rolling procedure and subsequent electrochemical corrosion tests, which resulted in a 44% improvement in corrosion resistance.
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(This article belongs to the Special Issue Surface Science of Degradation and Surface Protection)
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Performance of Ferronickel Slag Powder Soil Cement under Freshwater Curing Conditions
by
Lin Liu, Sanshan Chen, Feng Chen, Liang He and Weizhen Chen
Coatings 2024, 14(6), 721; https://doi.org/10.3390/coatings14060721 - 5 Jun 2024
Abstract
Ferronickel slag is the solid waste slag produced by smelting nickel–iron alloy. After grinding ferronickel slag into powder, it has potential chemical activity. It can partially replace cement and reduce the amount of cement, and is conducive to environmental protection. The mechanical properties
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Ferronickel slag is the solid waste slag produced by smelting nickel–iron alloy. After grinding ferronickel slag into powder, it has potential chemical activity. It can partially replace cement and reduce the amount of cement, and is conducive to environmental protection. The mechanical properties of soil cement were investigated through the compressive strength test and inter-split tensile test of ferronickel slag powder soil cement with different dosages. To further study the mechanism of ferronickel slag powder’s action on soil cement microscopically, the microstructure of soil cement was analyzed by using a scanning electron microscope and nuclear magnetic resonance equipment. The results of the study show that the incorporation of ferronickel slag powder can enhance the compressive and tensile strength of soil cement. The best performance enhancement of ferronickel slag powder was achieved when it was doped with 45% of its mass. The hydration products of soil cement increased with the increase in the doping amount, but the excessive doping of ferronickel slag powder would lead to a weakening of the hydration reaction and a decrease in the strength of the soil cement. At the same time, ferronickel slag powder plays the role of filling the void of soil cement. With the increase in ferronickel slag powder, the large pores inside the soil cement are reduced and the structure is denser.
Full article
(This article belongs to the Special Issue Recent Progress in Reinforced Concrete and Building Materials)
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