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Volume 14
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Coatings, Volume 14, Issue 9 (September 2024) – 152 articles

Cover Story (view full-size image): This study explores the development of β-cyclodextrin-modified cotton fabric for use in the medical and hospital sectors. The modification enhances the fabric’s photodynamic antibacterial properties when treated with methylene blue. Forming inclusion complexes between cyclodextrin and methylene blue enhances the antibacterial activity of the fabric upon light activation. This innovation represents a promising developemnt in the field textile-based medical solutions, advancing infection control and enhancing hygiene standards in healthcare. View this paper
 
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14 pages, 4692 KiB  
Article
Experimental Study of Surface Microtexture Formed by Laser-Induced Cavitation Bubble on 7050 Aluminum Alloy
by Bin Li, Byung-Won Min, Yingxian Ma, Rui Zhou, Hai Gu and Yupeng Cao
Coatings 2024, 14(9), 1230; https://doi.org/10.3390/coatings14091230 - 23 Sep 2024
Viewed by 516
Abstract
In order to study the feasibility of forming microtexture at the surface of 7050 aluminum alloy by laser-induced cavitation bubble, and how the density of microtexture influences its tribological properties, the evolution of the cavitation bubble was captured by a high-speed camera, and [...] Read more.
In order to study the feasibility of forming microtexture at the surface of 7050 aluminum alloy by laser-induced cavitation bubble, and how the density of microtexture influences its tribological properties, the evolution of the cavitation bubble was captured by a high-speed camera, and the underwater acoustic signal of evolution was collected by a fiber optic hydrophone system. This combined approach was used to study the effect of the cavitation bubble on 7050 aluminum alloy. The surface morphology of the microtexture was analyzed by a confocal microscope, and the tribological properties of the microtexture were analyzed by a friction testing machine. Then the feasibility of the preparation process was verified and the optimal density was obtained. The study shows that the microtexture on the surface of a sample is formed by the combined results of the plasma shock wave and the collapse shock wave. When the density of microtexture is less than or equal to 19.63%, the diameters of the micropits range from 478 μm to 578 μm, and the depths of the micropits range from 13.56 μm to 18.25 μm. This shows that the laser-induced cavitation bubble is able to form repeatable microtexture. The friction coefficient of the sample with microtexture is lower than that of the untextured sample, with an average friction coefficient of 0.16. This indicates that the microtexture formed by laser-induced cavitation bubble has a good lubrication effect. The sample with a density of 19.63% is uniform and smooth, having the minimum friction coefficient, with an average friction coefficient of 0.14. This paper provides a new approach for microtexture processing of metal materials. Full article
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13 pages, 5008 KiB  
Article
Biomimetic Layered Hydrogel Coating for Enhanced Lubrication and Load-Bearing Capacity
by Xuxu Hu, Yu Zhao, Shuai Cheng, Jinming Zhen, Zhengfeng Jia and Ran Zhang
Coatings 2024, 14(9), 1229; https://doi.org/10.3390/coatings14091229 - 23 Sep 2024
Viewed by 425
Abstract
Biomimetic hydrogel lubrication coatings with high wettability and low friction show great promise in tissue engineering, wound dressing, drug delivery, and intelligent sensing. Inspired by the hierarchical structure of natural cartilage, a layered hydrogel coating was constructed to functionalize rigid polyetheretherketone (PEEK). The [...] Read more.
Biomimetic hydrogel lubrication coatings with high wettability and low friction show great promise in tissue engineering, wound dressing, drug delivery, and intelligent sensing. Inspired by the hierarchical structure of natural cartilage, a layered hydrogel coating was constructed to functionalize rigid polyetheretherketone (PEEK). The layered hydrogel coating features a structural design comprising a top soft layer and a middle robust layer. The porous structure of the top soft hydrogel layer stores water molecules, providing surface lubrication, while the dense structure of the middle robust hydrogel layer offers load-bearing capacity. These synergistic effects of the gradient hydrogel layer endow the PEEK substrate with an ultra-low coefficient of friction (COF~0.010 at 5 N load), good load-bearing capacity (COF~0.031 at 10 N load), and excellent wear resistance (COF < 0.05 at 5 N load after 20,000 sliding cycles). This study introduces a novel design paradigm for robust hydrogel coatings with exceptional lubricity, displaying the potential application in cartilage replacement materials. Full article
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15 pages, 4976 KiB  
Perspective
Low-Carbon Embodied, Self-Cleaning, and Air-Purifying Building Envelope Components Using TiO2 Photocatalysis, 3D Printing, and Recycling
by Aníbal Maury-Ramírez, Mario Rinke and Johan Blom
Coatings 2024, 14(9), 1228; https://doi.org/10.3390/coatings14091228 - 23 Sep 2024
Viewed by 1669
Abstract
This perspective article describes the past, present, and future directions on TiO2 photocatalysis, 3D concrete printing, and recycling for developing innovative building envelope components from façade skins. Using a methodology consisting of three phases, first the historical evolution of TiO2 photocatalysis, [...] Read more.
This perspective article describes the past, present, and future directions on TiO2 photocatalysis, 3D concrete printing, and recycling for developing innovative building envelope components from façade skins. Using a methodology consisting of three phases, first the historical evolution of TiO2 photocatalysis, 3D concrete printing, and recycling policies was investigated. Second, the rationale and positioning with regard to the state of the art were developed. Third, the cementitious mix design assessment for 3D printing of the building envelope components, evaluation of the photocatalytic activity, evaluation of the self-cleaning and air-purifying properties, and environmental and health assessment of the building envelope components were identified and discussed as major issues in developing innovative building envelope components that have the potential to mitigate urban air pollution, reduce building maintenance activities, and reduce building embedded carbon while, for example, recycling significant amounts of construction and demolition waste. Full article
(This article belongs to the Special Issue Advanced Technology in Environmental Remediation and Resource Utilization, 2nd Edition)
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25 pages, 12100 KiB  
Review
Research Progress of Marine Anti-Fouling Coatings
by Shaoqian Wu, Shuo Wu, Shilong Xing, Tianshu Wang, Jiabin Hou, Yuantao Zhao and Wenge Li
Coatings 2024, 14(9), 1227; https://doi.org/10.3390/coatings14091227 - 23 Sep 2024
Viewed by 798
Abstract
The extended immersion of ships in seawater frequently results in biofouling, a condition characterized by the accumulation of marine organisms such as barnacles and algae. To combat this issue, the application of anti-fouling coatings to the hull surfaces of vessels has emerged as [...] Read more.
The extended immersion of ships in seawater frequently results in biofouling, a condition characterized by the accumulation of marine organisms such as barnacles and algae. To combat this issue, the application of anti-fouling coatings to the hull surfaces of vessels has emerged as one of the most effective strategies. In response to the increasing global emphasis on environmental sustainability, there is a growing demand for anti-fouling coatings that not only demonstrate superior anti-fouling efficacy but also adhere to stringent environmental standards. The traditional use of organotin-based self-polishing anti-fouling coatings, known for their high toxicity, has been prohibited due to environmental concerns. Consequently, there is a progressive shift toward the development and application of environmentally friendly anti-fouling coatings. This paper reviews the toxicity and application limitations associated with conventional anti-fouling coatings. It provides a comprehensive overview of recent advancements in the field, including the development of novel self-polishing anti-fouling coatings, low surface energy coatings, biomimetic coatings, and nanostructured coatings, each leveraging distinct anti-fouling mechanisms. The paper evaluates the composition and performance of these emerging coatings and identifies key technical challenges that remain unresolved. It also proposes a multi-faceted approach to addressing these challenges, suggesting potential solutions for enhancing the effectiveness and environmental compatibility of anti-fouling technologies. The paper forecasts future research directions and development trajectories for marine anti-fouling coatings, emphasizing the need for continued innovation to achieve both environmental sustainability and superior anti-fouling performance. Full article
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11 pages, 6709 KiB  
Article
An Improved Model for Prediction of Critical Velocity of Cold-Spray by First-Principles Calculations
by Chengsong Zhang, Haoting Zhan, Xiaolong Zhou and Ninshu Ma
Coatings 2024, 14(9), 1226; https://doi.org/10.3390/coatings14091226 - 23 Sep 2024
Viewed by 432
Abstract
The first-principles calculation was applied to predict the critical velocity of Cu/Al cold-spray bonding for the first time. The bonding mechanism of cold-spray was clarified by analyzing the energy variation and atomic interaction during the cold-spray impact process. Our results showed that the [...] Read more.
The first-principles calculation was applied to predict the critical velocity of Cu/Al cold-spray bonding for the first time. The bonding mechanism of cold-spray was clarified by analyzing the energy variation and atomic interaction during the cold-spray impact process. Our results showed that the shear deformation played a key role in the cold-spray bonding. The atomic interaction determined the effective absorption of impact kinetic energy and finally determined the successful bonding of the cold-spray. The heterogeneous atoms absorbed the impact kinetic energy by interatomic attraction to achieve cold-spray bonding, while the homogeneous atoms absorbed the impact kinetic energy by the deformation of interface layers. An excellent agreement between the predicted critical velocity and the experimental one could be obtained, especially for the heterogeneous material cold-spray. Our present method proved to be a simple and highly efficient computing method in critical velocity prediction. Most importantly, the critical velocity for cold-spray could be predicted without using any empirical or experimental parameters. Full article
(This article belongs to the Special Issue Coating Technologies Involving Surface Adsorption and Diffusion)
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11 pages, 2512 KiB  
Article
A Fully Connected Network (FCN) Trained on a Custom Library of Raman Spectra for Simultaneous Identification and Quantification of Components in Multi-Component Mixtures
by Jiangsan Zhao and Krzysztof Kusnierek
Coatings 2024, 14(9), 1225; https://doi.org/10.3390/coatings14091225 - 23 Sep 2024
Viewed by 460
Abstract
Raman spectroscopy provides detailed information about the molecular composition of a sample. The classical identification of components in a multi-component sample typically involves comparing the preprocessed spectrum with a known reference stored in a database using various spectral matching or machine-learning techniques or [...] Read more.
Raman spectroscopy provides detailed information about the molecular composition of a sample. The classical identification of components in a multi-component sample typically involves comparing the preprocessed spectrum with a known reference stored in a database using various spectral matching or machine-learning techniques or relies on universal models based on a two-step analysis including first, the component identification, and then the decomposition of the mixed signal. However, although large databases and universal models cover a wide range of target materials, they may be not optimized to the variability required in a specific application. In this study, we propose a single-step method using deep learning (DL) modeling to decompose a simulated mixture of real measurements of Raman scattering into relevant individual components regardless of noise, baseline and the number of components involved and quantify their ratios. We hypothesize that training a custom DL model for applications with a fixed set of expected components may yield better results than applying a universal quantification model. To test this hypothesis, we simulated 12,000 Raman spectra by assigning random ratios to each component spectrum within a library containing 13 measured spectra of organic solvent samples. One of the DL methods, a fully connected network (FCN), was designed to work on the raw spectra directly and output the contribution of each component of the library to the input spectrum in form of a component ratio. The developed model was evaluated on 3600 testing spectra, which were simulated similarly to the training dataset. The average component identification accuracy of the FCN was 99.7%, which was significantly higher than that of the universal custom trained DeepRaman model, which was 83.1%. The average mean absolute error for component ratio quantification was 0.000562, over one order of magnitude smaller than that of a well-established non-negative elastic net (NN-EN), which was 0.00677. The predicted non-zero ratio values were further used for component identification. Under the assumption that the components of a mixture are from a fixed library, the proposed method preprocesses and decomposes the raw data in a single step, quantifying every component in a multicomponent mixture, accurately. Notably, the single-step FCN approach has not been implemented in the previously reported DL studies. Full article
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13 pages, 8918 KiB  
Article
Effect of SiC Contents on Wear Resistance Performance of Electro-Codeposited Ni-SiC Composite Coatings
by Shaoqing Wang, Faqin Xie and Xiangqing Wu
Coatings 2024, 14(9), 1224; https://doi.org/10.3390/coatings14091224 - 23 Sep 2024
Viewed by 470
Abstract
This paper focuses on the wear resistance performance of Ni-SiC composite coatings with various contents of SiC particles. The coatings were characterized via a scanning electron microscope (SEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM), and the wear behaviors of different coatings [...] Read more.
This paper focuses on the wear resistance performance of Ni-SiC composite coatings with various contents of SiC particles. The coatings were characterized via a scanning electron microscope (SEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM), and the wear behaviors of different coatings were tested. The results show that SiC particle incorporation results in a nanocrystalline metal matrix and nanotwins in nickel nanograins. The microhardness and wear resistance Ni-SiC composite coatings increased with the increasing SiC content. Microhardness was improved due to the grain-refinement strengthening effect and the presence of a nanotwin structure. The dominant wear mechanism was described in two stages: the first stage involves the interaction of SiC particles/the counter ball, and the second stage involves the formation of the oxide film its breaking up into wear debris. A higher SiC content increased the duration of the first stage and slowed down the rate of breaking up into debris, thereby decreasing the wear rate. Full article
(This article belongs to the Section Tribology)
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12 pages, 9204 KiB  
Article
Efficient and Controllable Preparation of Super-Hydrophobic Alumina-Based Ceramics Coating on Aviation Al-Li Alloy Surface for Corrosion Resistance and Anti-Icing Behavior
by Ben Li and Xuewu Li
Coatings 2024, 14(9), 1223; https://doi.org/10.3390/coatings14091223 - 22 Sep 2024
Viewed by 723
Abstract
Al-Li alloys have been widely applied in aircraft structural component and shell material. However, Al-Li alloys are prone to corrosion failure, which leads to a considerable safety risk in the aerospace field and greatly limits their industrial application. Herein, a simple, low-cost, and [...] Read more.
Al-Li alloys have been widely applied in aircraft structural component and shell material. However, Al-Li alloys are prone to corrosion failure, which leads to a considerable safety risk in the aerospace field and greatly limits their industrial application. Herein, a simple, low-cost, and large-scale air-spraying technique is developed for the preparation of an alumina-based ceramics coating with enhanced corrosion resistance and anti-icing behavior. The results show that the static contact angle of the as-prepared coating is 157.2 ± 0.4°, and the rolling angle is only 9.8°, suggesting a super-hydrophobic surface. Meanwhile, the electrochemical corrosion potential of the coating is 70 mV higher than that of the substrate, and the corrosion current density of the coating also decreases by 1 order of magnitude, indicating a significantly improved corrosion resistance. In addition, the fabricated super-hydrophobic coating also shows excellent anti-pollution and anti-icing characteristics. This work provides positive guidance for expanding the application of hydrophobic coating in the aerospace industry, especially in some complex corrosion, icing, and pollution environments. Full article
(This article belongs to the Special Issue Research Progress and Application of Super-hydrophobic Anti-icing Surface)
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11 pages, 11973 KiB  
Article
The Lacquer Craft of the Corridor Coffin (徼道棺) from Tomb No. 2 of Tushan in Eastern Han Dynasty, Xuzhou
by Zongmin Li, Xiaojun Li, Jinyong Yu, Yihua Sun, Jianjun Geng and Xing Zhao
Coatings 2024, 14(9), 1222; https://doi.org/10.3390/coatings14091222 - 22 Sep 2024
Viewed by 486
Abstract
Tomb No. 2 of Tushan in Xuzhou is the tomb of King Chu of the Eastern Han Dynasty, and it was an important archaeological discovery in China. The unique placement and crafting techniques of a lacquer coffin that was unearthed from the burial [...] Read more.
Tomb No. 2 of Tushan in Xuzhou is the tomb of King Chu of the Eastern Han Dynasty, and it was an important archaeological discovery in China. The unique placement and crafting techniques of a lacquer coffin that was unearthed from the burial corridor are of significant importance in the study of tombs. In order to characterise the sample’s microstructure, elemental composition, and structural composition, as well as to study the crafting techniques of the coffin in the corridor, a range of analytical techniques were employed, including ultra-depth microscopy, scanning electron microscopy with SEM-EDS, Raman spectroscopy, FTIR, and XRD. The results indicate that the cross-sectional structure of the fragments comprises a pigment layer and a lacquer ash layer, with the latter being further divided into tile ash and bone ash layers. No lacquer film layer was observed. The primary colouring agent in the pigment layer was HgS, which contained a minor quantity of organic binder. The primary component of the tile ash layer was quartz, while the osseous ash layer comprised particles and collagen derived from mammalian bones. The lacquer crafting technique employed in the construction of the coffin was relatively simple and inconsistent with the assumption of it having a noble status. The findings of this research offer experimental data for the identification, preservation, and technical restoration of the corridor coffin in the future. Full article
(This article belongs to the Special Issue Research and Conservation of Ancient Lacquer)
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13 pages, 6392 KiB  
Article
A New Process of Chemical Plating Ni-P Electromagnetic Induction Heating Activation on the Surface of Aluminium Alloy Base Material
by Jin Gao, Kaifang Cui, Siqi Li, Liang Zhong, Jingxiong Dai, Zhigang Yang and Rongming Qiang
Coatings 2024, 14(9), 1221; https://doi.org/10.3390/coatings14091221 - 22 Sep 2024
Viewed by 715
Abstract
Nowadays, there are many surface treatment methods for aluminium alloys; the most commonly used of these is the chemical dip galvanizing process, which is complicated due to its use of large quantities of corrosive drugs. In order to simplify the process, this paper [...] Read more.
Nowadays, there are many surface treatment methods for aluminium alloys; the most commonly used of these is the chemical dip galvanizing process, which is complicated due to its use of large quantities of corrosive drugs. In order to simplify the process, this paper proposes a new electromagnetic induction heating activation method instead of the zinc dipping process. The method works as follows: The substrate is first degreased and then activated. The activation process starts by soaking the degreased substrate in an activation solution, taking it out after ten minutes, and placing it into an induction heating unit. The activation solution is sprayed onto the surface of the substrate while heating, using the energy generated by high temperatures to complete the activation reaction. The surface of the activated substrate forms a nanoscale film of nickel, which is finally utilised as a catalytic centre for ENP (an advanced surface treatment process that deposits a very uniform layer). The optimisation of important parameters of the non-destructive activation process was determined using the L9 Taguchi method. The main parameters ranged from 0.15 L/min to 0.25 L/min for spray rate, 200 °C to 400 °C for heat treatment temperature, and 1:4, 1:5, and 1:6 for Ni2+ and H2PO4− ion concentration ratios. The above data were derived from a single variable and were analysed using Minitab 20 software. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy spectrometry (EDS), and ultrasonic experiments were used to characterize and analyse the surface morphology, composition, and bond strength of the coatings. The results show that the nanoscale nickel particles can completely cover the surface of the substrate, forming a layer of nano-film. After activation and ultrasonic cleaning for 30 s at an ultrasonic frequency of 40 KHz and a power of 80 W, the surface nano-film was not destroyed, which proves that it had a high bonding strength. After the application of the plating, the plated surface had a compact microstructure, and the continuity was good. Therefore, compared with the currently commonly used zinc dipping process, this process has the advantages of being a low-cost, simple operation, and non-destructive and environmentally friendly activation process for the substrate. Full article
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37 pages, 14338 KiB  
Article
Archaeological Excavation, Protection, and Display Engineering Design Practice: A Case Study in the Ruins of the Imperial City of the Minyue Kingdom
by Shihui Zhou, Lei Zhang, Yile Chen, Liang Zheng, Nengzhong Lei and Jiali Zhang
Coatings 2024, 14(9), 1220; https://doi.org/10.3390/coatings14091220 - 21 Sep 2024
Viewed by 683
Abstract
The Han Dynasty Ruins in Chengcun Village of Wuyishan City, also known as the Ruins of the Imperial City of the Minyue Kingdom, are located on the hilly slope southwest of Chengcun Village, Xingtian Town, Wuyishan City, Fujian Province, China. These are ruins [...] Read more.
The Han Dynasty Ruins in Chengcun Village of Wuyishan City, also known as the Ruins of the Imperial City of the Minyue Kingdom, are located on the hilly slope southwest of Chengcun Village, Xingtian Town, Wuyishan City, Fujian Province, China. These are ruins of a Han Dynasty city. Wuyi Mountain’s World Cultural and Natural Heritage Committee declared it a World Heritage Site in 1999. It is also the only imperial city site from the Han Dynasty that has been declared a World Heritage Site in China, and it is the most well-preserved large-scale imperial city site from the Middle Ages on the Pacific Rim. This study used comprehensive archaeological techniques, including archaeological excavation work, site information recording, erosion situation analysis, and geological surveys, to design and implement protective engineering projects in response to existing problems. In this study, the researchers conducted a geological survey of the study area to analyze the topography, rock and soil distribution characteristics, groundwater storage conditions, and geotechnical engineering conditions. At the same time, they explored the preservation status of the site, including the preservation status of the East Gate and the East City Wall, and they analyzed the causes of damage. Finally, the investigation and analysis results guided the design of a site display project, which included safeguarding against collapse and erosion, treating trees and shrubs, and designing the exhibition project for the East Gate. This study provides some practical reference for the excavation and archaeological work of the royal city in the surrounding areas. At the same time, in terms of the technical process of the project, it is also hoped to provide ideas for international ancient city excavation, display, and protection projects. Full article
(This article belongs to the Special Issue Advanced Technology in Surface Characterization and Conservation for Architectural and Archaeological Heritage)
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17 pages, 12728 KiB  
Article
Effect of an Ultrasonic Vibration on the Microstructure and Properties of Al Alloy/Steel Laser Welding-Brazing Joints
by Chao Zhang, Daozhong Du, Ziqian Wu, Yubo Sun, Xiaoyang Wang, Weimin Long and Juan Pu
Coatings 2024, 14(9), 1219; https://doi.org/10.3390/coatings14091219 - 21 Sep 2024
Viewed by 612
Abstract
This study analyzes the influence of different ultrasonic amplitudes on the microstructure composition, microhardness, tensile strength, and corrosion resistance of Al alloy/steel laser welding-brazing joints assisted by ultrasonic vibration. The application of ultrasonic vibration did not change the microstructure composition of the joints [...] Read more.
This study analyzes the influence of different ultrasonic amplitudes on the microstructure composition, microhardness, tensile strength, and corrosion resistance of Al alloy/steel laser welding-brazing joints assisted by ultrasonic vibration. The application of ultrasonic vibration did not change the microstructure composition of the joints but refined them. The joints were all composed of θ-Fe(Al, Si)3 and τ5-Al7.2Fe1.8Si formed at the interface reaction zone, as well as an α-Al solid solution and Al-Si eutectic phase generated in the weld seam zone. Meanwhile, the thickness of the IMCs at the interface decreased with an increase in the ultrasonic amplitude. When the ultrasonic amplitude was 8 μm, the IMCs thickness was a minimum of 1.62 μm. In this condition, the reduction of the IMCs thickness and the refined grain of joints made the microhardness and tensile strength reach the maximum. The fracture of joints with ultrasonic amplitudes of 0 and 4.8 μm began at the weld seam and extended to the interface reaction zone at the steel side, while the fracture of joints was located in the heat-affected zone (HAZ) of the Al alloy side when the ultrasonic amplitude was 8.0 and 11.2 μm. The fracture mode of the former presented a typical mixed fracture with cleavage steps and tearing edges, and that of the latter showed ductile fracture with uniform and fine ductile dimples. The corrosion resistance of the joints was improved by adding ultrasonic vibration. When the ultrasonic amplitude was 8 μm, its corrosion resistance was optimum; it was ascribed to a dense oxide film formed on the surface of the metal under the action of ultrasonic vibration. Full article
(This article belongs to the Special Issue Tribology and Mechanical Characteristics of Films)
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15 pages, 1965 KiB  
Article
Structural Design and Mechanical Properties Analysis of Laminated SiAlON Ceramic Tool Materials
by Wenhao Wu, Guangchun Xiao, Yanjun Jia, Hui Chen, Jingjie Zhang, Mingdong Yi, Zhaoqiang Chen and Chonghai Xu
Coatings 2024, 14(9), 1218; https://doi.org/10.3390/coatings14091218 - 21 Sep 2024
Viewed by 550
Abstract
Based on finite element simulation analysis, laminated ceramic tool materials with different structures were designed and the effect of laminated structure on tool state was investigated. Residual stresses in ceramic tool materials increase with the number of layers and layer–thickness ratio. Based on [...] Read more.
Based on finite element simulation analysis, laminated ceramic tool materials with different structures were designed and the effect of laminated structure on tool state was investigated. Residual stresses in ceramic tool materials increase with the number of layers and layer–thickness ratio. Based on the simulation results, SiAlON-SiC-SiCw/SiAlON-Al2O3 ceramic tool materials (SCWAs) were prepared using the spark plasma sintering process, and the influence of residual stress on the mechanical properties and microstructure of laminated ceramic tool materials was studied. The mechanical properties of ceramic materials were significantly improved under the effect of residual stresses. The fracture toughness of SCWA4 with 7 layers and a layer–thickness ratio of 6 was 6.02 ± 0.19 MPa·m1/2, and the front and side flexural strengths were 602 ± 19 MPa and 595 ± 17 MPa, 36.3% and 39.0% higher than homogeneous SiAlON ceramics, respectively. Full article
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15 pages, 3209 KiB  
Article
The Effect of Anodization and Thermal Treatment on Mixed-Oxide Layer Formation on Ti–Zr Alloy
by Ioana-Alina Ciobotaru, Fidan Bahtiar Ismail, Roxana Budei, Anca Cojocaru and Danut-Ionel Vaireanu
Coatings 2024, 14(9), 1217; https://doi.org/10.3390/coatings14091217 - 20 Sep 2024
Viewed by 520
Abstract
The anodization or thermal treatments applied to alloys of titanium and zirconium have a substantiated effect on the mixed-oxide layer formation compared to the naturally occurring one. A Ti–Zr 50%/50% alloy was chosen for a comparative study. Controlled, thermally treated, and anodized samples [...] Read more.
The anodization or thermal treatments applied to alloys of titanium and zirconium have a substantiated effect on the mixed-oxide layer formation compared to the naturally occurring one. A Ti–Zr 50%/50% alloy was chosen for a comparative study. Controlled, thermally treated, and anodized samples obtained with controlled procedures were analyzed in terms of morphological and compositional analysis (using SEM and EDX analysis) as well as for the determination of hardness variations. Substantial differences were observed depending on the applied functionalization method (compact of structured mixed-oxide nanotubes when the samples are subjected to the anodization procedure); there was an increase of more than six folds in the mixed-oxide layer hardness and D Shore scale, when subjected to thermal treatment, and hence, this lead to the conclusion that one may control the morphology, composition and/or the hardness of the mixed-oxide layer by applying one or another or a combination of functionalization methods. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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12 pages, 2359 KiB  
Article
Polyacetylene Prepared by Chemical Dehydration of Poly(Vinyl Alcohol)
by Gianfranco Carotenuto and Luigi Nicolais
Coatings 2024, 14(9), 1216; https://doi.org/10.3390/coatings14091216 - 20 Sep 2024
Viewed by 335
Abstract
Recently, polyacetylene (PA) has been receiving renewed scientific attention due to its electrical properties, potentially useful for energy applications (e.g., fabrication of electrodes for rechargeable batteries and supercapacitors), and unique functional characteristics (e.g., gas trap, oxygen scavenger, EMI shielding, etc.). This chemical compound [...] Read more.
Recently, polyacetylene (PA) has been receiving renewed scientific attention due to its electrical properties, potentially useful for energy applications (e.g., fabrication of electrodes for rechargeable batteries and supercapacitors), and unique functional characteristics (e.g., gas trap, oxygen scavenger, EMI shielding, etc.). This chemical compound can be obtained in the form of polyacetylene–PVOH copolymers simply through the chemical dehydration of poly(vinyl alcohol) (PVOH), which is a very common type of polymer, widely used in packaging and other technological areas. This very inexpensive chemical reaction for the large-scale synthesis of PA/polyvinylenes is investigated by reacting PVOH with sulfuric acid at room temperature. In this process, PVOH, shaped in the form of a film, is dipped in sulfuric acid (i.e., H2SO4 at 95%–97%) and, after complete chemical dehydration, it is mechanically removed from the liquid phase by using a nylon sieve. The reduction process leads to a substantial PVOH film conversion into PA, as demonstrated by infrared spectroscopy (ATR mode). Indeed, the ATR spectrum of the reaction product includes all the characteristic absorption bands of PA. The reaction product is also characterized through the use of UV–Vis spectroscopy in order to evidence the presence in the structure of conjugated carbon–carbon double bonds of various lengths. Differential scanning calorimetry (DSC) and thermogravimetric analysis are used to investigate the PA solid-state cis–trans isomerization and thermal stability in air and nitrogen, respectively. XRD is used to verify the polymer amorphous nature. Full article
(This article belongs to the Special Issue Advanced Functional Nanostructured Films and Coatings for Energy Applications, 2nd Edition)
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13 pages, 4196 KiB  
Article
Performance and Evaluation of Slow-Release Fertilizer Encapsulated by Waterless Synthesized GO Sheets
by Hsuhui Cheng, Yishi He, Yuxing Xian and Xiangying Hao
Coatings 2024, 14(9), 1215; https://doi.org/10.3390/coatings14091215 - 20 Sep 2024
Viewed by 376
Abstract
Slow-release fertilizer was developed by encapsulating NPK compound pellets with graphene oxide (GO) sheets employing a waterless synthesis technique. As-prepared GO sheets were characterized by XRD, Raman, XPS, FTIR, SEM, and EDS. The XRD patterns of the GO sheets indicate that the peak [...] Read more.
Slow-release fertilizer was developed by encapsulating NPK compound pellets with graphene oxide (GO) sheets employing a waterless synthesis technique. As-prepared GO sheets were characterized by XRD, Raman, XPS, FTIR, SEM, and EDS. The XRD patterns of the GO sheets indicate that the peak for the GO is observed at 2θ = 9.3°, and the peak (002) for graphite vanished. Moreover, a higher intensity ratio of the Raman ID/IG of the GO sheets than that of pristine graphite confirms the oxidation of the graphite. The FTIR and XPS analyses provided information on electronic structure, chemical structure, and oxygen-bonding neighbors. The SEM images indicated the GO sheet, whereby its morphology resembles a thin curtain or corrugated shape. The EDS spectrum of coated GO-F pellets revealed the distribution of C, O, N, P, and K elements in the synthesized materials. Afterwards, GO shell formation on fertilizer pellets greatly improved the slow-release characteristics of fertilizer, thus providing plants with their requisite nutrients and reducing environmental pollution. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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37 pages, 2592 KiB  
Review
Recent Applications and Future Trends of Nanostructured Thin Films-Based Gas Sensors Produced by Magnetron Sputtering
by Pedro Catalão Moura and Susana Sério
Coatings 2024, 14(9), 1214; https://doi.org/10.3390/coatings14091214 - 20 Sep 2024
Viewed by 786
Abstract
The field of gas sensors has been developing for the last year due to the necessity of characterizing compounds and, in particular, volatile organic compounds whose detection can be of special interest in a vast range of applications that extend from clinical evaluation [...] Read more.
The field of gas sensors has been developing for the last year due to the necessity of characterizing compounds and, in particular, volatile organic compounds whose detection can be of special interest in a vast range of applications that extend from clinical evaluation to environmental monitoring. Among all the potential techniques to develop sensors, magnetron sputtering has emerged as one of the most suitable methodologies for the production of large-scale uniform coatings, with high packing density and strong adhesion to the substrate at relatively low substrate temperatures. Furthermore, it presents elevated deposition rates, allows the growth of thin films with high purity, permits a precise control of film thickness, enables the simple manufacturing of sensors with low power consumption and, consequently, low costs involved in the production. This work reviewed all the current applications of gas sensors developed through magnetron sputtering in the field of VOCs assessment by gathering the most relevant scientific works published. A total of 10 compounds were considered for this work. Additionally, 13 other compounds were identified as promising targets and classified as future trends in this field. Overall, this work summarizes the state-of-the-art in the field of gas sensors developed by magnetron sputtering technology, allowing the scientific community to take a step forward in this field and explore new research areas. Full article
(This article belongs to the Special Issue Advanced Nanostructured Coatings Deposited by Magnetron Sputtering)
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15 pages, 3651 KiB  
Article
Experimental Analysis of Noise Characteristics on Different Types of Pavements inside and outside Highway Tunnels
by Wanyan Ren, Yi Zhang, Minmin Yuan and Jun Li
Coatings 2024, 14(9), 1213; https://doi.org/10.3390/coatings14091213 - 20 Sep 2024
Viewed by 473
Abstract
Aiming to reduce noise pollution and optimize the acoustic quality in highway tunnels, the noise characteristics on different types of pavements were analyzed and compared in this research, based on the on-site noise measurement in two tunnels with the free fields as a [...] Read more.
Aiming to reduce noise pollution and optimize the acoustic quality in highway tunnels, the noise characteristics on different types of pavements were analyzed and compared in this research, based on the on-site noise measurement in two tunnels with the free fields as a control group. Specifically, the noise characteristics include two aspects: various noise and noise time attenuation performance. Various noise includes on-board sound intensity (OBSI) noise and cabin noise. The noise time attenuation performance uses the indicator of reverberation time. Three types of pavements were measured, including dense-graded asphalt concrete (DAC) and single-layered and double-layered porous asphalt (PA) pavement. The results showed that, for the same type of pavement, compared with the free fields, the difference in OBSI noise in tunnels was within a range of less than 1 dBA; the cabin noise increased by 3.4 dBA~6.6 dBA. The noise level in tunnels was greater than that outside tunnels, and the longer tunnel exhibited higher traffic noise and worse noise time attenuation performances. For the same tunnel, PA pavement could reduce the cabin noise by 3.8 dBA~6.7 dBA. PA pavement also exhibited shorter reverberation time. The application of PA pavement could effectively improve the acoustic quality in the tunnel. This research contributes to noise pollution abatement and the improvement of the comfort and safety of drivers in tunnels. Full article
(This article belongs to the Special Issue Novel Cleaner Materials for Pavements)
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16 pages, 6344 KiB  
Article
Mechanical Performance Assessment of a Hot-Mix Asphalt Modified with Biochar Obtained from Pine Wood Shavings
by Saieth Baudilio Chaves-Pabón, Hugo Alexander Rondón-Quintana and Juan Gabriel Bastidas-Martínez
Coatings 2024, 14(9), 1212; https://doi.org/10.3390/coatings14091212 - 20 Sep 2024
Viewed by 403
Abstract
Diverse types of waste are generated during the sawmilling process. One of them is pine wood shavings (PWSs). This waste can be transformed by pyrolysis into biochar (BC) to produce a sustainable material that can serve as an asphalt binder modifier. In this [...] Read more.
Diverse types of waste are generated during the sawmilling process. One of them is pine wood shavings (PWSs). This waste can be transformed by pyrolysis into biochar (BC) to produce a sustainable material that can serve as an asphalt binder modifier. In this study, a BC produced with PWS as biomass (BC-PWS) was used to modify the properties of an asphalt cement (AC). This type of BC has not been investigated as a modifier of ACs and asphalt mixtures. Three BC-PWS contents were used for this purpose (BC/AC = 5, 10, and 15% by weight). Conventional characterization tests such as penetration, softening point, and rotational viscosity were performed on the unmodified and modified ACs. Rheological properties were also evaluated at high and intermediate temperatures, and observations were made with a scanning electron microscope (SEM). The modified BC/AC = 10% binder was chosen to manufacture a hot-mix asphalt (HMA). Marshall, indirect tensile strength—ITS, Cantabro, resilient modulus (RM), permanent deformation, and fatigue resistance (under stress-controlled mode) tests were performed on the HMA. The Tensile Strength Ratio (TSR) parameter was determined from ITS tests. BC-PWS is a promising material as an AC modifier from the technical-environmental point of view, which tends to enhance the evaluated properties of AC and HMA (monotonic load, rutting, fatigue, moisture damage, and raveling resistance), without resorting to increases in asphalt content or increases in mixing and compaction temperatures. Full article
(This article belongs to the Special Issue Surface Treatment and Mechanical Properties of Sustainable Pavement Materials)
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13 pages, 11023 KiB  
Article
Antibacterial Activity of Superhydrophobic-SiO2 Coatings to Inhibit the Growth of Escherichia coli and Staphylococcus aureus
by Betania Sánchez-Santamaria, Delfino Cornejo-Monroy, Imelda Olivas-Armendáriz, José Saúl Arias-Cerón, Alfredo Villanueva-Montellano, Elsa Ordoñez-Casanova, José Omar Dávalos-Ramírez, Erwin Adán Martínez-Gómez and Jesús Manuel Jaquez-Muñoz
Coatings 2024, 14(9), 1211; https://doi.org/10.3390/coatings14091211 - 20 Sep 2024
Viewed by 767
Abstract
The emergence of superhydrophobic antibacterial materials represents a promising approach to maintaining surface cleanliness and hygiene by effectively preventing bacterial adhesion. This research outlines the synthesis of a superhydrophobic coating with anti-adhesion and bacteriostatic properties, utilizing silica nanoparticles (SiO2 NPs) modified with [...] Read more.
The emergence of superhydrophobic antibacterial materials represents a promising approach to maintaining surface cleanliness and hygiene by effectively preventing bacterial adhesion. This research outlines the synthesis of a superhydrophobic coating with anti-adhesion and bacteriostatic properties, utilizing silica nanoparticles (SiO2 NPs) modified with 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (PFDTES). Transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy were conducted to analyze the coating’s morphology and surface characteristics. The coating was applied to glass substrates using the spray coating method, and the number of layers was varied to evaluate its antibacterial and bacteriostatic properties. These properties were measured using turbidimetry and inhibition halo techniques. Additionally, the durability of the coatings was assessed by exposing them to outdoor conditions for 35 days. This study aimed to evaluate the antibacterial and bacteriostatic capacities of the superhydrophobic coating, along with its resistance to outdoor weathering. The results indicate that a superhydrophobic coating with a contact angle ≥ 150° and a sliding angle ≤ 10° was successfully synthesized using SiO2 NPs smaller than 10 nm, modified with PFDTES. The coating demonstrated an ability to inhibit bacterial growth by preventing the adhesion of bacteria such as Escherichia coli and Staphylococcus aureus. Furthermore, the number of coating layers significantly influenced its bacteriostatic efficacy. The coating also exhibited strong durability under outdoor conditions. These findings highlight the potential application of superhydrophobic coatings for the prevention of bacterial adhesion and growth in environments where such contamination poses risks. Full article
(This article belongs to the Special Issue Synthesis and Applications of Bioactive Coatings)
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14 pages, 7984 KiB  
Article
The Synergistic Effect of Cross-Linked and Electrostatic Self-Assembly Si/MXene Composites Anode for Highly Efficient Lithium-Ion Battery
by Songjia Kong, Chenguang Liu, Jiawei Ren, Tianchang Wang, Xianwei Geng, Yudan Yuan, Chun Zhao, Cezhou Zhao and Li Yang
Coatings 2024, 14(9), 1210; https://doi.org/10.3390/coatings14091210 - 19 Sep 2024
Viewed by 671
Abstract
Silicon is a promising anode material for high-performance lithium-ion batteries (LIBs), but its rapid capacity degradation has significantly hindered its large-scale application. In this study, we propose an in situ self-assembly polymerization method to fabricate a stable silicon-based anode by leveraging electrostatic self-assembly [...] Read more.
Silicon is a promising anode material for high-performance lithium-ion batteries (LIBs), but its rapid capacity degradation has significantly hindered its large-scale application. In this study, we propose an in situ self-assembly polymerization method to fabricate a stable silicon-based anode by leveraging electrostatic self-assembly technology, in situ esterification, and amidation reactions. The incorporation of a cross-linked polymer, combined with the synergistic effects of electrostatic interactions between negatively charged MXene and positively charged silane-coupling-agent-modified silicon, offers a novel strategy for enhancing the electrochemical performance of LIBs. Notably, annealed electrodes with a 65 wt% nmSi-NH2/MXene ratio demonstrate outstanding electrochemical performance, achieving a capacity of 929.5 mAh g⁻¹ at a current density of 1 A g⁻¹ after 100 charge/discharge cycles. These findings suggest that the integration of cross-linked polymers and electrostatic self-assembly can significantly improve the intercalation and overall electrochemical performance of silicon anodes in lithium-ion batteries. Full article
(This article belongs to the Special Issue Advanced Polymer and Thin Film for Sustainable Energy Harvesting)
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39 pages, 9178 KiB  
Article
Research on the Wear State Detection and Identification Method of Huller Rollers Based on Point Cloud Data
by Zhaoyun Wu, Tao Jin, Xiaoxia Liu, Zhongwei Zhang, Binbin Zhao, Yehao Zhang and Xuewu He
Coatings 2024, 14(9), 1209; https://doi.org/10.3390/coatings14091209 - 19 Sep 2024
Viewed by 445
Abstract
Throughout the huller shelling process, the rubber rollers progressively deteriorate. The velocity of the rubber rollers decreases as the distance between the rollers rises. These modifications significantly influence the rate at which rice hulling occurs. Hence, the implementation of real-time online detection is [...] Read more.
Throughout the huller shelling process, the rubber rollers progressively deteriorate. The velocity of the rubber rollers decreases as the distance between the rollers rises. These modifications significantly influence the rate at which rice hulling occurs. Hence, the implementation of real-time online detection is crucial for maintaining the operational efficiency of the huller. Currently, the prevailing inspection methods include manual inspection, 2D vision inspection, deep learning methods, and machine vision methods. Nevertheless, these conventional techniques lack the ability to provide detailed information about the faulty components, making it challenging to conduct comprehensive defect identification in three dimensions. To address this issue, point cloud technology has been incorporated into the overall detection of the working condition of the huller. Specifically, the Random Sample Consensus segmentation algorithm and the adaptive boundary extraction algorithm have been developed to identify abnormal wear on the rubber rollers by analyzing the point cloud data on their surface. A solution technique has been developed for the huller to compensate for the speed of the rubber rollers and calculate the mean values of their radii. Additionally, a numerical simulation algorithm is proposed to address the dynamic change in the roller spacing detection. The results show that point cloud data can be utilized to achieve real-time and precise correction of anomalous wear patterns on the surface of rubber rollers. Full article
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18 pages, 8538 KiB  
Article
Design and Application of Driving Resistance Test Device for Aircraft Tire and Soil Pavement
by Zihan Wang, Xiaolei Chong, Lei Liang, Zhenglei Chen and Chaojia Liu
Coatings 2024, 14(9), 1208; https://doi.org/10.3390/coatings14091208 - 19 Sep 2024
Viewed by 481
Abstract
In view of the lack of soil bins for studying the surface interaction between aircraft wheels and soil, this study designed an indoor test bench for aircraft wheels and soil, including a soil container, loading vehicle, and intelligent measurement and control system, to [...] Read more.
In view of the lack of soil bins for studying the surface interaction between aircraft wheels and soil, this study designed an indoor test bench for aircraft wheels and soil, including a soil container, loading vehicle, and intelligent measurement and control system, to test key parameters such as tire speed and wheel frictional resistance. The test system is capable of achieving speed regulation ranging from 0 to 30 km/h. The vertical load adjustment range with an adjustment interval of 10 kg spans from 90 to 140 kg. The soil type, compaction degree, and other conditions can be modified as per requirements to vary multiple test conditions, thereby enabling us to explore their influence on the driving resistance of the wheels. Moreover, the test data can be collected and processed in real time. A performance test of a wheel–soil table was carried out. The results show that the wheel–soil table test system is stable and reliable and can determine the relationship between the tire and soil, and the structural design of the test system meets the use requirements. In addition, it achieves the target test speed, data acquisition frequency, and stability. In terms of functionality and operational difficulty, the data acquisition of the entire test process is automated, and the test system achieves better informationization than previous methods. The overall operation of the wheel–soil platform is stable and powerful; thus, the model test platform design goal is achieved, and the testing requirements are met. Full article
(This article belongs to the Special Issue Surface Engineering Processes for Reducing Friction and Wear)
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12 pages, 30181 KiB  
Article
Enhanced Fracture Toughness of WC-CoCr Thermally Sprayed Coatings by the Addition of NiCrFeSiBC and Mo and Its Influence on Sliding Wear Behavior
by José de Jesús Ibarra, Marco Aurelio González, Eduardo Rodríguez, Gabriel Israel Vásquez, Ariosto Medina, José Bernal, Claudio Aguilar and Eduardo Enrique Velez
Coatings 2024, 14(9), 1207; https://doi.org/10.3390/coatings14091207 - 19 Sep 2024
Viewed by 477
Abstract
Wear is a major issue in industry, particularly with metal components. Therefore, it is crucial to investigate methods that offer increased resistance to this phenomenon. In this research, three coating systems (pure WC-CoCr and WC-CoCr/NiCrFeSiBC+Mo, 88:12 and 83:17 wt.%) were thermally sprayed on [...] Read more.
Wear is a major issue in industry, particularly with metal components. Therefore, it is crucial to investigate methods that offer increased resistance to this phenomenon. In this research, three coating systems (pure WC-CoCr and WC-CoCr/NiCrFeSiBC+Mo, 88:12 and 83:17 wt.%) were thermally sprayed on an AISI 1018 steel substrate through the High-Velocity Oxygen Fuel (HVOF) process. The coatings were characterized using a field emission scanning electron microscope (FESEM) equipped with the energy dispersive spectroscope (EDS) and X-ray diffractometry (XRD). An analysis of the wear rate for ball-on-flat linear reciprocating sliding tribological tests for the coatings was also carried out. The coating microstructure presents well-dispersed NiCrFeSiBC splats. The WC-CoCr/NiCrFeSiBC+Mo, 88:12, system has the highest wear resistance, decreasing by 30.2% at high loads compared to commercial WC-CoCr CERMETs, and also exhibits the highest fracture toughness. Analysis of wear tracks shows that the material removal at all charges occurred mainly by an abrasive wear mechanism. Full article
(This article belongs to the Special Issue Characterization and Manufacturing of Nano-Composites and Nano-Composite Coatings)
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14 pages, 21261 KiB  
Article
Investigating the Relationship between Building Orientation and Surface Properties of Stainless Steel Prepared via Selective Laser Melting
by Tao Fang, Huanghuang Jin, Feng Huang, Yuan Chu, Xiaofan Zheng and Song Yu
Coatings 2024, 14(9), 1206; https://doi.org/10.3390/coatings14091206 - 19 Sep 2024
Viewed by 450
Abstract
In our investigation of the influence rules and mechanisms of the building orientation on the surface properties of 316L stainless steel created via selective laser melting, we used X-ray diffractometry, scanning electron microscopy, and electron backscatter diffraction to investigate the phases, microstructures, and [...] Read more.
In our investigation of the influence rules and mechanisms of the building orientation on the surface properties of 316L stainless steel created via selective laser melting, we used X-ray diffractometry, scanning electron microscopy, and electron backscatter diffraction to investigate the phases, microstructures, and textures of specimens. In addition, we employed a digital microhardness tester, friction, and wear-testing apparatus, along with an electrochemical workstation, to examine variations in the surface properties. The results indicated that the surface phase compositions of the specimens with different building orientations were similar; however, they displayed anisotropic behavior in grain size, orientation, and texture. Notably, the surface densification of the specimens at 0°, 30°, 45°, and 60° initially decreased before subsequently increasing. In contrast, the surface roughness showed a pattern of first increasing and then declining. Moreover, the microhardness, wear resistance, and corrosion resistance decreased with an increasing inclination angle. Full article
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18 pages, 12467 KiB  
Article
Aluminum Foil Surface Etching and Anodization Processes for Polymer 3D-Printing Applications
by Yunki Jung, Han Su Kim, Young-Pyo Jeon, Jin-Yong Hong and Jea Uk Lee
Coatings 2024, 14(9), 1205; https://doi.org/10.3390/coatings14091205 - 19 Sep 2024
Viewed by 572
Abstract
Extrusion-based polymer three-dimensional (3D) printing, specifically fused deposition modeling (FDM), has been garnering increasing interest from industry, as well as from the research and academic communities, due to its low cost, high speed, and process simplicity. However, bed adhesion failure remains an obstacle [...] Read more.
Extrusion-based polymer three-dimensional (3D) printing, specifically fused deposition modeling (FDM), has been garnering increasing interest from industry, as well as from the research and academic communities, due to its low cost, high speed, and process simplicity. However, bed adhesion failure remains an obstacle to diversifying the materials and expanding the industrial applications of the FDM 3D-printing process. Therefore, this study focused on an investigation of the surface treatment methods for aluminum (Al) foil and their applications to 3D printer beds to enhance the bed adhesion of a 3D-printed polymer filament. Two methods of etching with sodium hydroxide and anodization with phosphoric acid were individually used for the surface treatment of the Al foil beds and then compared with an untreated foil. The etching process removed the oxide layer from the Al foil and increased its surface roughness, while the anodizing process enhanced the amount of hydroxide functional groups and contributed to the formation of nano-holes. As a result, the surface-anodized aluminum foil exhibited a higher affinity and bonding strength with the 3D-printed polymers compared with the etched and pristine foils. Through the increase in the success rate in 3D printing with various polymers, it became evident that utilizing surface-treated Al foil as a 3D printer bed presents an economical solution to addressing bed adhesion failure. Full article
(This article belongs to the Special Issue Corrosion/Wear Mechanisms and Protective Methods)
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9 pages, 3131 KiB  
Article
Improved-Performance Amorphous Ga2O3 Photodetectors Fabricated by Capacitive Coupled Plasma-Assistant Magnetron Sputtering
by Yiming Liu, Chong Peng, Chang Liu, Cong Yu, Jiarui Guo, Yiyang Chang and Yi Zhao
Coatings 2024, 14(9), 1204; https://doi.org/10.3390/coatings14091204 - 19 Sep 2024
Viewed by 410
Abstract
Ga2O3 has received increasing interest for its potential in various applications relating to solar-blind photodetectors. However, attaining a balanced performance with Ga2O3-based photodetectors presents a challenge due to the intrinsic conductive mechanism of Ga2O [...] Read more.
Ga2O3 has received increasing interest for its potential in various applications relating to solar-blind photodetectors. However, attaining a balanced performance with Ga2O3-based photodetectors presents a challenge due to the intrinsic conductive mechanism of Ga2O3 films. In this work, we fabricated amorphous Ga2O3 (a-Ga2O3) metal–semiconductor–metal photodetectors through capacitive coupled plasma assisted magnetron sputtering at room temperature. Substantial enhancement in the responsivity is attained by regulating the capacitance-coupled plasma power during the deposition of a-Ga2O3. The proposed plasma energy generated by capacitive coupled plasma (CCP) effectively improved the disorder of amorphous Ga2O3 films. The results of X-ray photoelectron spectroscopy (XPS) and current-voltage tests demonstrate that the additional plasma introduced during the sputtering effectively adjust the concentration of oxygen vacancy effectively, exhibiting a trade-off effect on the performance of a-Ga2O3 photodetectors. The best overall performance of a-Ga2O3 photodetectors exhibits a high responsivity of 30.59 A/W, a low dark current of 4.18 × 10−11, and a decay time of 0.12 s. Our results demonstrate that the introduction of capacitive coupled plasma during deposition could be a potential approach for modifying the performance of photodetectors. Full article
(This article belongs to the Collection Feature Paper Collection in Thin Films)
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17 pages, 8396 KiB  
Article
A New Process for Efficient Non-Destructive Metal-Activated Composite Plating of Ni-P-Al2O3 on Titanium Base and Its Performance Research
by Kaifang Cui, Jin Gao, Siqi Li, Xue Leng, Liang Zhong and Rongming Qiang
Coatings 2024, 14(9), 1203; https://doi.org/10.3390/coatings14091203 - 19 Sep 2024
Viewed by 532
Abstract
A new high efficient and non-destructive mental activation process of electroless composite plating was proposed. The process utilized electromagnetic induction equipment to heat the titanium alloy substrate and used its energy to complete the activation process, which could successfully attach the nickel nanoparticles [...] Read more.
A new high efficient and non-destructive mental activation process of electroless composite plating was proposed. The process utilized electromagnetic induction equipment to heat the titanium alloy substrate and used its energy to complete the activation process, which could successfully attach the nickel nanoparticles firmly to the surface of the titanium alloy; at the same time, the process pre-activated Al2O3 nanoparticles and added the activated nanoparticles to the plating solution. In the process of plating, the activated titanium substrate was used as the catalytic center of electroless nickel plating (ENP) for electroless composite plating. The new activation process avoided complicated traditional processes such as acid etching and zinc dipping. Such traditional processes require huge doses of chemicals, including various strong acids, so improper waste liquid treatment will cause harm to the environment. The important parameters of the process were optimized by orthogonal experiments. A scanning electron microscope (SEM), an X-ray photoelectron spectroscopy (XPS), an energy dispersive spectrometer (EDS), thermal shock experiments and friction and wear experiments were used to characterize and analyze the surface morphology, composition, binding force and friction coefficient of the coating, and analyze the coating quality by measuring the plating rate and the thickness of the coating. The results showed that the rate of electroless composite plating increased with the increase in Al2O3 nanoparticle concentration. When the concentration of Al2O3 nanoparticles reached 1.5 g/L, the ENP rate decreased with the increase in Al2O3 nanoparticle concentration. The adhesion of the sample was evaluated by the scratch test, which showed that the binding grade of the sample was 0, and the Vickers hardness was 688.5 HV. Results showed that the coating produced by this new process has excellent performance. Therefore, the process is an environmentally friendly and fast activation composite plating process. Full article
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19 pages, 1725 KiB  
Article
Shelf-Life Extension and Quality Changes of Fresh-Cut Apple via Sago and Soy-Oil-Based Edible Coatings
by Manmin Zhang, Di Xiao, Congfei Zhu, Kaiser Younis and Owais Yousuf
Coatings 2024, 14(9), 1202; https://doi.org/10.3390/coatings14091202 - 18 Sep 2024
Viewed by 573
Abstract
In-demand fresh-cut fruits are highly perishable and require shelf stability. Starch, such as sago, is a naturally available polysaccharide with good gas barrier properties. The study aimed to develop an edible coating and examine the effect of its application on the quality parameters [...] Read more.
In-demand fresh-cut fruits are highly perishable and require shelf stability. Starch, such as sago, is a naturally available polysaccharide with good gas barrier properties. The study aimed to develop an edible coating and examine the effect of its application on the quality parameters of fresh-cut apples. The coating solution was prepared with sago and soy oil in concentrations of 3, 4, and 5% and 0, 0.25, and 0.50%, respectively. Lecithin (0.50%) was used as an emulsifier and glycerol (1.5%) as a plasticizer. Coated fresh-cut apples were evaluated for physicochemical properties (TSS, pH, non-enzymatic browning index, moisture content, weight loss, headspace gas, and color attributes) during a 12-day shelf-life study at 4 °C. Sensory analysis was also performed to assess consumer acceptability, and microbial analysis to investigate its inhibiting effect against yeast and mold. Compared to the control, developed coatings reduced browning, respiration rate, moisture, weight loss, and microbial load in fresh-cut apples. The study indicates that the blend of 5% sago and 0.5% soy oil produced the best coatings which were most effective for retaining the original quality attributes and in extending the shelf life of apple slices for 12 days in storage at 4 °C. Full article
(This article belongs to the Section Coatings for Food Technology and System)
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15 pages, 3961 KiB  
Article
Forming Epoxy Coatings on Laser-Engraved Surface of Aluminum Alloy to Reinforce the Bonding Joint with a Carbon Fiber Composite
by Hongping Zhu, Jinheng Zhang, Fei Cheng, Jiangzhou Li, Bo Wu and Zhijie Zhao
Coatings 2024, 14(9), 1201; https://doi.org/10.3390/coatings14091201 - 18 Sep 2024
Viewed by 415
Abstract
This study designed laser engraving and resin pre-coating (RPC) treatments on an aluminum alloy (AA) surface to construct through-the-thickness “epoxy pins” for improving the bonding strength with carbon fiber reinforced polymer (CFRP). A laser engraving treatment was used to create a pitted structure [...] Read more.
This study designed laser engraving and resin pre-coating (RPC) treatments on an aluminum alloy (AA) surface to construct through-the-thickness “epoxy pins” for improving the bonding strength with carbon fiber reinforced polymer (CFRP). A laser engraving treatment was used to create a pitted structure on the AA surface; higher wettability was acquired and greater vertical spaces were formed to impregnate epoxy resin, resulting in stronger mechanical interlocking. The RPC technique was further used to guide high-viscosity epoxy resin into pits to form the epoxy coatings and to minimize defects between the resin and the substrate. The bonding strength of the specimen treated with both laser engraving with a unit dimension of 0.3 mm and RPC increased up to 227.1% in comparison with that of the base. The failure modes of the hybrid composites changed from the debonding failure of the AA surface to the delamination-dominated failure of the laminated CFRP composites. It was confirmed that laser engraving is a feasible and effective method when combined with RPC for treating AAs to improve the bonding strength of AA-CFRP composites, which provides a reference for preparing high-performance hybrid composites with metals. Full article
(This article belongs to the Special Issue Advanced Additive Manufacturing and Surface Modifications of Metallic Materials)
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