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 and Interfaces)
- 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
Electro-Coloring Mechanism of Aluminum Anodic Oxides in Tin-Based Electrolytes
Coatings 2024, 14(5), 616; https://doi.org/10.3390/coatings14050616 (registering DOI) - 13 May 2024
Abstract
A method for accurately determining the chemical composition of deposits at the bottom of pores during the electrocoloring (e-coloring) of aluminum anodic oxide (AAO) layers in tin-based solutions is developed. The aluminum samples were AC e-colored after DC sulfuric anodization. Free-standing, tin e-colored
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A method for accurately determining the chemical composition of deposits at the bottom of pores during the electrocoloring (e-coloring) of aluminum anodic oxide (AAO) layers in tin-based solutions is developed. The aluminum samples were AC e-colored after DC sulfuric anodization. Free-standing, tin e-colored aluminum oxide film was obtained by selective dissolution of the metallic aluminum from the AAO in copper chloride solution to access the deposit directly at the bottom of the pore. This allowed us to conduct XPS analysis directly on the deposits at pore bottoms without any interference from the base material or insulating barrier layer. The results revealed the presence of a mixture of tin oxide and metal in the deposits, which were richer in oxide content. Furthermore, a cyclic voltammetry experiment mimicking real polarization conditions during AC conditions was optimized and used to gain a deeper understanding of the electrochemical reactions that occur during AC electrocoloring. The comparison of CV results in tin-free and tin-containing electrolytes indicated that the tin deposited during a cathodic cycle is oxidized in the anodic cycle. The formation of tin-based deposits radically changed the CV behavior. The XPS and cyclic voltammetry results consistently show that the deposits formed during e-coloring comprised a mixture of metallic and oxidic tin species richer in oxide content.
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(This article belongs to the Section Surface Characterization, Deposition and Modification)
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Effect of Electrolytic Plasma Polishing on Surface Properties of Titanium Alloy
by
Dongliang Yang, Huanwu Sun, Gangqiang Ji, Yuxia Xiang and Juan Wang
Coatings 2024, 14(5), 615; https://doi.org/10.3390/coatings14050615 (registering DOI) - 13 May 2024
Abstract
Electrolytic plasma polishing (EPPo) is an advanced metal surface finishing technology with high quality and environmental protection that has broad application prospects in the biomedical field. However, the effect of EPPo on surface properties such as corrosion resistance and the wettability of biomedical
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Electrolytic plasma polishing (EPPo) is an advanced metal surface finishing technology with high quality and environmental protection that has broad application prospects in the biomedical field. However, the effect of EPPo on surface properties such as corrosion resistance and the wettability of biomedical titanium alloys remains to be investigated. This paper investigated the changes in surface roughness, surface morphology, microstructure, and chemical composition of Ti6Al4V alloy by EPPo and their effects on surface corrosion resistance, wettability, and residual stress. The results showed that Ra decreased from 0.3899 to 0.0577 μm after EPPo. The surface crystallinity was improved, and the average grain size increased from 251 nm to more than 800 nm. The oxidation behavior of EPPo leads to an increase in surface oxygen content and the formation of TiO2 and Al2O3 oxide layers. EPPo can significantly improve the corrosion resistance and wettability of titanium alloy in simulated body fluid and eliminate the residual stress on the sample surface. The surface properties are enhanced not only by the reduction in surface roughness but also by the formation of a denser oxide film on the surface, changes in the microstructure, an increase in surface free energy, and the annealing effect developed during EPPo. This study can provide guidance and references for applying EPPo to biomedical titanium alloy parts.
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(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)
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Open AccessArticle
Effect of Heat Treatment on Microstructure and Mechanical Properties of Titanium Alloy Fabricated by Laser–Arc Hybrid Additive Manufacturing
by
Yuhang Chen, Juan Fu, Lilong Zhou, Yong Zhao, Feiyun Wang, Guoqiang Chen and Yonghui Qin
Coatings 2024, 14(5), 614; https://doi.org/10.3390/coatings14050614 (registering DOI) - 13 May 2024
Abstract
The tailored thermal heat-treatment process for Ti-6Al-4V alloy manufactured by laser–arc hybrid additive manufacturing can achieve desired microstructures and excellent mechanical properties for components. The effects of different heat treatment regimens on the microstructure and mechanical properties of Ti-6Al-4V alloy manufactured by laser–arc
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The tailored thermal heat-treatment process for Ti-6Al-4V alloy manufactured by laser–arc hybrid additive manufacturing can achieve desired microstructures and excellent mechanical properties for components. The effects of different heat treatment regimens on the microstructure and mechanical properties of Ti-6Al-4V alloy manufactured by laser–arc hybrid additive manufacturing are investigated in this study. Utilizing optical microscopy and scanning electron microscopy, we analyze the variations in microstructure with changes in heat-treatment parameters and explore the reasons for the changes in mechanical properties under different solutions’ treatment temperatures and cooling rates. The microstructure of Ti-6Al-4V alloy fabricated via laser–arc hybrid additive manufacturing was primarily composed of Widmanstätten α plate structures and a small amount of acicular martensite α′ within columnar β grains that grew outward from the substrate along the deposition direction. Following solution treatment and aging heat treatment, the microstructure transitioned to a typical high-performance net basket structure with significantly reduced α plate thickness, leading to noticeable enhancements in sample ductility and toughness. Specifically, when the solution treatment and aging treatment regimen was set at 950 °C for 1 h, followed by air cooling, and then aging at 540 °C for 6 h with subsequent air cooling, the average grain size decreased by a factor of two compared to the as-deposited samples, while the impact toughness increased by 66.7%.
Full article
(This article belongs to the Special Issue Application of Laser Processing Technology in Automobile Manufacturing)
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Open AccessArticle
Optimizing Nickel Electroplating in Low-Ni Environments for Efficient Source Production in Small Plating Baths
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Gujin Kang, Jongbum Kim, Jin Kim, Jinjoo Kim, Jintae Hong and Sangwook Kim
Coatings 2024, 14(5), 613; https://doi.org/10.3390/coatings14050613 (registering DOI) - 12 May 2024
Abstract
Electroplating nickel-63, a radioactive isotope used in betavoltaic batteries and random number generators, requires precise control due to its limited availability and the generation of radioactive waste. To minimize waste and ensure effective plating, small plating baths are employed, optimizing the process within
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Electroplating nickel-63, a radioactive isotope used in betavoltaic batteries and random number generators, requires precise control due to its limited availability and the generation of radioactive waste. To minimize waste and ensure effective plating, small plating baths are employed, optimizing the process within constrained conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized to determine the optimal plating conditions and limiting conditions for nickel electroplating in a small plating bath. This study focuses on the use of low-concentration nickel solutions and small plating equipment, in contrast to the common industrial practice of using high concentrations of nickel. Here, it is important to optimize the plating parameters, especially the nickel concentration, current density, and bath temperature. An average thickness of 1.8 μm was found when plating with a nickel concentration of 0.06 M, a current density of 5 mA/cm2, and a solution temperature of 40 °C, while ideal conditions were found to achieve the theoretical maximum energy and 90% release rate when plating with nickel-63 instead of Ni.
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(This article belongs to the Section Surface Characterization, Deposition and Modification)
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Open AccessArticle
A Strategy of Candle Soot-Based Photothermal Icephobic Superhydrophobic Surface
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Chenlu Qian, Lu Wang, Qiang Li and Xuemei Chen
Coatings 2024, 14(5), 612; https://doi.org/10.3390/coatings14050612 (registering DOI) - 12 May 2024
Abstract
Anti-icing/de-icing is of fundamental importance in practical applications such as power transmission, wind turbines, and aerofoils. Despite recent efforts in developing engineering surfaces to delay ice accumulation or reduce ice adhesion, it remains challenging to design robust photothermal icephobic surfaces in a durable,
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Anti-icing/de-icing is of fundamental importance in practical applications such as power transmission, wind turbines, and aerofoils. Despite recent efforts in developing engineering surfaces to delay ice accumulation or reduce ice adhesion, it remains challenging to design robust photothermal icephobic surfaces in a durable, low-cost, easy-fabrication manner. Here, we report an intelligent candle soot-based photothermal surface (PDMS/CS60@PDMS/Al) that can utilize sunlight illumination to achieve the multi-abilities of anti-icing, de-icing, and self-cleaning. Our method lies in the construction of hierarchical micro/nanostructures by depositing photothermal candle soot nanoparticles, which endow the surface with superior superhydrophobicity and excellent photothermal performance. The underlying mechanism is exploited by establishing the heat transfer model between the droplets and the cooled surface. We believe that the smart PDMS/CS60@PDMS/Al developed in this work could provide a feasible strategy to design intelligent engineering surfaces for enhanced anti-icing/de-icing.
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(This article belongs to the Topic Advances in Functional Thin Films)
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Effect of Scanning Electron Beam Pretreatment on Gas Carburization of 22CrMoH Gear Steel
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Wei Jiang, Jing-Jing Qu, Fei Liu, Gao Yue, Lei Zhou, Yu-Cheng Luo and Hui-Wang Ning
Coatings 2024, 14(5), 611; https://doi.org/10.3390/coatings14050611 (registering DOI) - 11 May 2024
Abstract
22CrMoH was selected for the gear steel material in this work, and the temperature field change in the scanning electron beam was analyzed to determine the optimal scanning parameters and explored the effect of scanning electron beam pretreatment (Abbreviated as: SEBP) on gas-carburizing
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22CrMoH was selected for the gear steel material in this work, and the temperature field change in the scanning electron beam was analyzed to determine the optimal scanning parameters and explored the effect of scanning electron beam pretreatment (Abbreviated as: SEBP) on gas-carburizing (GC) efficiency and organizational properties of gear steel. The results showed that the scanning electron beam caused the material to form a thermally deformed layer 110 μm thick, and it promoted the adsorption of carbon atoms on the surface and their inward diffusion. Under the same gas-carburizing conditions, the carburizing efficiency was improved, and the thickness of the carburized layer increased from 0.78 to 1.09 mm. Furthermore, the hardness of the GC specimens with the SEBP increased from 615 to 638 HV0.05 at 0.1 mm of the sample surface, whereas the hardness of the cross-sectional region decreased gradually, indicating that the scanning electron beam enhanced the adhesion between the carburized layer and matrix zone. A comparative analysis of the microstructures of the GC specimens with and without the SEBP showed that the carbide particles in the surface layer of the samples become smaller and that of volume fraction of residual austenite reduced in size. In terms of the mechanical properties, the surface friction coefficient decreased from 0.87 to 0.46 μ and the GC specimen with the SEBP had a higher cross-sectional hardness gradient. Its friction coefficient was reduced from approximately 0.8 to almost 0.45 μ, and the wear amount of the specimens with SEBP was 47.7% of that of the matrix specimens.
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(This article belongs to the Section Surface Characterization, Deposition and Modification)
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Open AccessArticle
Study on the Influence of Particle Size Distribution on the Separation of Pyrite from Coal Gangue by Jigging
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Xinkai Hou, Zhentong Xi, Xiangfeng Wang and Wenjuan Ji
Coatings 2024, 14(5), 610; https://doi.org/10.3390/coatings14050610 (registering DOI) - 11 May 2024
Abstract
The presence of pyrite poses a significant impediment to the comprehensive utilization of coal gangue, which is a prevalent solid waste in industrial production. However, the current efficacy of jig separation for pyrite in fine-grade coal gangue remains unsatisfactory. To investigate the influence
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The presence of pyrite poses a significant impediment to the comprehensive utilization of coal gangue, which is a prevalent solid waste in industrial production. However, the current efficacy of jig separation for pyrite in fine-grade coal gangue remains unsatisfactory. To investigate the influence of particle size distribution on the jig separation of pyrite in fine-grade coal gangue, the raw material was crushed to less than 2 mm using a jaw crusher and subsequently sieved to obtain its particle size distribution curve. Upon fitting the curve, it was observed that it tends towards the Rosin-Rammler (RRSB) and Fuller distributions. Leveraging these two-parameter distribution curves, adjustments were made to determine the mass within each particle size range before conducting thorough mixing followed by jig separation. The results indicate that for fine-grade gangue particles smaller than 2 mm, the RRSB distribution with a uniformity coefficient of n = 0.85 exhibits the most effective separation, although it is comparable to the separation achieved using the size distribution of raw ore. On the other hand, employing the Fuller distribution with modulus of distribution q = 1.5 yields superior separation performance. In comparison to the raw ore, the concentrate shows an increase in sulfur (S) and iron (Fe) content by factors of 3.4 and 2.4, respectively. Furthermore, compared to the RRSB distribution, there is an increase in S and Fe content by 1.91% and 2.30%, respectively; the contents of S and Fe in tailings is 0.71% and 2.72%, which can be directly used as raw materials for coating materials. Therefore, for fine-grade coal gangue particles, jigging under the Fuller distribution demonstrates better effectiveness than under the RRSB distribution.
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(This article belongs to the Section Ceramic Coatings and Engineering Technology)
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Optimized Functionalization of Graphene Oxide for Enhanced Mechanical Properties in Epoxy Resin Composites
by
Xin Li, Bing Yu, Jie Chen, Dongxia Huo, Jun Liu and Ding Nan
Coatings 2024, 14(5), 609; https://doi.org/10.3390/coatings14050609 (registering DOI) - 11 May 2024
Abstract
Epoxy resins have widespread applications across various industries, such as anticorrosive coatings, owing to their exceptional attributes. However, there is a constant demand for enhancements to their mechanical characteristics to cater to the requirements of unique and specialized conditions. In this work, graphene
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Epoxy resins have widespread applications across various industries, such as anticorrosive coatings, owing to their exceptional attributes. However, there is a constant demand for enhancements to their mechanical characteristics to cater to the requirements of unique and specialized conditions. In this work, graphene oxide modified by 4,4′-Oxydianiline (MGO) was prepared using a covalent grafting reaction. The MGO in epoxy resin composites exhibited a rougher morphology and thin layers with a superior tensile strength (38 MPa), elastic modulus (358 MPa), flexural strength (85 MPa), flexural modulus (957 MPa), and hardness (62 HD). The results indicated that the mechanical properties of epoxy resin are significantly improved by MGO and the improved mechanical properties of epoxy resin composites are due to the strong interfacial bonding between MGO and epoxy.
Full article
(This article belongs to the Special Issue Enhanced Mechanical Properties of Metals by Surface Treatments)
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Open AccessReview
Development of Si-Based Anodes for All-Solid-State Li-Ion Batteries
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Xuyang Zhao, Yunpeng Rong, Yi Duan, Yanlong Wu, Deyu He, Xiaopeng Qi and Jiantao Wang
Coatings 2024, 14(5), 608; https://doi.org/10.3390/coatings14050608 (registering DOI) - 11 May 2024
Abstract
All-solid-state Li-ion batteries (ASSBs) promise higher safety and energy density than conventional liquid electrolyte-based Li-ion batteries (LIBs). Silicon (Si) is considered one of the most promising anode materials due to its high specific capacity (3590 mAh g−1) but suffers from poor
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All-solid-state Li-ion batteries (ASSBs) promise higher safety and energy density than conventional liquid electrolyte-based Li-ion batteries (LIBs). Silicon (Si) is considered one of the most promising anode materials due to its high specific capacity (3590 mAh g−1) but suffers from poor cycling performance because of large volumetric effects leading to particle pulverization, unstable solid electrolyte interphase (SEI), and electric disconnection. In ASSBs, additional issues such as poor solid–solid contacts and interfacial side reactions between Si and solid-state electrolytes (SSEs) are also hindering their practical application. This review first outlines the prospects and recent research achievements of Si-based anodes with special focuses on various Si structures and composite materials, then analyzes the issues of electrochemical–mechanical effects, and finally summarizes key factors and promising strategies for further improving Si-based anodes for high-performance ASSBs.
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(This article belongs to the Section Surface Engineering for Energy Harvesting, Conversion, and Storage)
Open AccessReview
Recent Progress in Electromagnetic Wave Absorption Coatings: From Design Principles to Applications
by
Yang Jin, Haojie Yu, Yun Wang, Li Wang and Bohua Nan
Coatings 2024, 14(5), 607; https://doi.org/10.3390/coatings14050607 (registering DOI) - 11 May 2024
Abstract
It is essential to develop electromagnetic (EM) wave-absorbing materials with exceptional versatility to address a variety of applications, including anti-radar stealth, EM radiation protection, and EM interference shielding. EM wave absorption coatings, mainly composed of matrices and EM absorbers, have excellent practical performance.
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It is essential to develop electromagnetic (EM) wave-absorbing materials with exceptional versatility to address a variety of applications, including anti-radar stealth, EM radiation protection, and EM interference shielding. EM wave absorption coatings, mainly composed of matrices and EM absorbers, have excellent practical performance. Researchers have been developing advanced EM absorption coating with properties like thin, light, broadband, and anti-aging. This review summarizes the recent progress in EM absorption coatings, including the design principles, feedstocks, manufacturing techniques, performance evaluation methods, and applications. Finally, the current challenges and future research directions are discussed.
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(This article belongs to the Special Issue Dielectric Materials for Energy Storage, Energy Harvesting and Electrocaloric Applications)
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Al2O3 Coatings for Protection of Stainless Steel 316L against Corrosion in Zn-Al and Zn-Al-Mg
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Giovanni Paolo Alparone, David Penney, James Sullivan, James Edy and Christopher Mills
Coatings 2024, 14(5), 606; https://doi.org/10.3390/coatings14050606 (registering DOI) - 11 May 2024
Abstract
The production and quality of automotive-grade galvanised steel are affected by the limited service life of the pot roll bearings used in continuous galvanising lines. The journal bearings are subjected to severe degradation as they react with the molten Zn bath, and coatings
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The production and quality of automotive-grade galvanised steel are affected by the limited service life of the pot roll bearings used in continuous galvanising lines. The journal bearings are subjected to severe degradation as they react with the molten Zn bath, and coatings can provide corrosion protection to the bearing materials. This research investigates the performance of Al2O3 coatings applied via the HVOF thermal spray process to stainless steel 316L substrates. Immersion tests were conducted in baths of different compositions, namely GI (Zn-0.3 wt.% Al) and ZMA (Zn-1.5 wt.% Al-1.5 wt.% Mg). Material characterisation after testing showed evidence of coating degradation after 1 week, as the coating tended to crack and detach from the substrate, allowing the molten Zn to attack the underlying steel. The coefficient of thermal expansion of Al2O3 and steel was measured, and a difference of 13 × 10−6 K−1 was found, leading to the development of cracks in the coatings. Zn penetration through cracks was determined to be the main failure mechanism of the Al2O3 coatings, which otherwise remained inert to Zn-Al. Conversely, the coatings immersed in Zn-Al-Mg reacted with the Mg in the molten metal bath, showing that changing bath composition affected the performance of the coatings in molten Zn alloy.
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(This article belongs to the Topic Corrosion and Protection of Metallic Materials, 2nd Edition)
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Open AccessArticle
The Scratch Resistance of a Plasma-Assisted DUPLEX-Treated 17-4 Precipitation-Hardened Stainless Steel Additively Manufactured by Laser Powder Bed Fusion
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Arturo Gómez-Ortega, Julián Andrés Pinilla-Bedoya, Carolina Ortega-Portilla, Christian Félix-Martínez, Guillermo César Mondragón-Rodríguez, Diego Germán Espinosa-Arbeláez, James Pérez-Barrera, Juan Manuel González-Carmona and Edgar Adrián Franco Urquiza
Coatings 2024, 14(5), 605; https://doi.org/10.3390/coatings14050605 (registering DOI) - 11 May 2024
Abstract
Additive manufacturing (AM) or 3D printing of metals is gaining popularity due to its flexibility when fabricating parts with highly complex designs, as well as when simplifying manufacturing steps and optimizing process times. In this investigation, 17-4 PH stainless steel was additively manufactured
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Additive manufacturing (AM) or 3D printing of metals is gaining popularity due to its flexibility when fabricating parts with highly complex designs, as well as when simplifying manufacturing steps and optimizing process times. In this investigation, 17-4 PH stainless steel was additively manufactured using Laser Powder Bed Fusion (L-PBF), followed by functionalization through a DUPLEX treatment. This treatment involved a plasma-assisted nitriding process, followed by the deposition of an arc-PVD c-Al0.7Cr0.3N hard coating. The microstructural modifications resulting from plasma nitriding (such as the formation of Fe2,3N and Fe4N and the αN or expanded martensite phases) and the surface improvements with the c-Al0.7Cr0.3N coating on the 3D-printed 17-4 PH steel are evaluated in comparison to conventionally manufactured 17-4 PH steel. These microstructural characteristics are correlated with the mechanical response of the treated surfaces. As a result of the plasma nitriding process, the hardness of the 3D-printed 17-4 PH SS increased by approximately 260%. The wear, measured through dynamic and static scratch testing, was reduced by approximately 31%. This improvement was attributed to the modification of adhesive failure mechanisms, leading to a reduction in wear volume, improved coating adhesion, and enhanced scratch resistance.
Full article
(This article belongs to the Topic Additive Manufacturing of Architected Metallic Materials)
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Open AccessArticle
The Effect of Applying UV LED-Cured Varnish to Metalized Printing Elements during Cold Foil Lamination
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Igor Majnarić, Marko Morić, Dean Valdec and Katja Milković
Coatings 2024, 14(5), 604; https://doi.org/10.3390/coatings14050604 (registering DOI) - 10 May 2024
Abstract
The coating process involves applying a thin material layer to a surface to engender it with specific desirable properties or enhance its performance. In the production of print media (labels, packaging, printed textiles, and promotional materials), the standard functions of the coating process
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The coating process involves applying a thin material layer to a surface to engender it with specific desirable properties or enhance its performance. In the production of print media (labels, packaging, printed textiles, and promotional materials), the standard functions of the coating process include visual decoration, which involves the addition of appealing colors, textures, and patterns. A pertinent issue in the printing industry is that at present, the predominant coating process uses printing and coating technologies (gravure, flexo, letterset, letterpress, screen printing, inkjet, and electrophotography) and lamination (i.e., attaching decorative layers of materials, such as films or fabrics). In this paper, we present a new method for testing the efficiency with which different-sized metalized printing elements (using gold foil) may be applied to paper substrates; to do so, we gradually vary the amount UV-cured inkjet varnish (or adhesive) that is applied. To test the effectiveness of this method in producing metallic visual effects, we utilize seven different thicknesses of UV-cured varnish with the aid of modular piezo inkjet heads (KM1024 iLHE-30) and three different printing speeds. Our research shows that to achieve optimal production of cold metalized foil, a 21 µm layer should be deposited, and the substrate should move at a speed of 0.30 m/s.
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(This article belongs to the Topic Advances in Functional Thin Films)
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Open AccessArticle
Effect of Co Contents on Microstructure and Cavitation Erosion Resistance of NiTiAlCrCoxN Films
by
Hongjuan Yan, Fangying Cheng, Lina Si, Ye Yang, Zhaoliang Dou and Fengbin Liu
Coatings 2024, 14(5), 603; https://doi.org/10.3390/coatings14050603 (registering DOI) - 10 May 2024
Abstract
In order to investigate the effect of Co contents on the structure and cavitation erosion property, NiTiAlCrCoxN films were prepared by the magnetron sputtering system. The X-ray diffractometer (XRD), the scanning electron microscope (SEM) and the energy dispersive spectrometer (EDS) were
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In order to investigate the effect of Co contents on the structure and cavitation erosion property, NiTiAlCrCoxN films were prepared by the magnetron sputtering system. The X-ray diffractometer (XRD), the scanning electron microscope (SEM) and the energy dispersive spectrometer (EDS) were used to characterize the structure and morphology of the films. The nanoindenter and the scratch tester were used to analyze the mechanical properties of the films. Cavitation erosion experiments were carried out by the ultrasonic vibration cavitation machine. The results show that NiTiAlCrCoxN films with different Co contents have a simple face-centered cubic (FCC) structure and show a preferred orientation on the (200) crystal plane. The diffraction angle on the (200) crystal plane decreases and the interplanar spacing increases with the increase in Co content in NiTiAlCrCoxN films. NiTiAlCrCoxN films exhibit a typical columnar crystalline structure. With the increase in Co content, the nanohardness of the films increases and the elastic modulus of the films decreases, while the mass loss of cavitation erosion monotonously increases except for the film with a 1.2 Co molar ratio. The NiTiAlCrCo1.4N film has a minimum hardness of 13.264 GPa, a maximum elastic modulus of 253.22 GPa and a minimum mass loss of 0.72 mg in the cavitation erosion experiment. The NiTiAlCrCo1.4N film exhibits the best cavitation corrosion resistance because the addition of the Co element enhances the solid solution strengthening effect and the NiTiAlCrCox1.4N film with the biggest elastic modulus has better elasticity to reduce the micro jet impact.
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(This article belongs to the Special Issue Investigation on Corrosion Behaviour of Metallic Materials)
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Open AccessArticle
Mechanical Properties and Microstructural Evolution of 6082 Aluminum Alloy with Different Heat Treatment Methods
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Erli Xia, Tuo Ye, Sawei Qiu, Jie Liu, Jiahao Luo, Longtao Sun and Yuanzhi Wu
Coatings 2024, 14(5), 602; https://doi.org/10.3390/coatings14050602 (registering DOI) - 10 May 2024
Abstract
The influence of solid solution treatment (SST), artificial aging treatment (AAT), and deep cryogenic-aging treatment (DCAT) on the mechanical properties and microstructure evolution of 6082 aluminum alloy was investigated. The tensile test was performed to obtain the true stress–strain curves through an electronic
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The influence of solid solution treatment (SST), artificial aging treatment (AAT), and deep cryogenic-aging treatment (DCAT) on the mechanical properties and microstructure evolution of 6082 aluminum alloy was investigated. The tensile test was performed to obtain the true stress–strain curves through an electronic universal testing machine. The results show that the yield strengths of the SST specimens in all three directions are the lowest, of less than 200 MPa. In addition, the maximum elongation of the SST specimen is over 16% and the value of in-plane anisotropy (IPA) is 5.40%. For the AAT specimen, the yield strengths of the AAT alloy in three directions have distinct improvements, which are beyond 340 MPa. However, the maximum elongation and the IPA were evidently reduced. The yield strength and elongation of the DCAT alloy exhibit a slight enhancement compared with those in the AAT condition, and the corresponding IPA is 0.61%. The studied alloy specimens in all conditions exhibit ductile fracture. The DCAT alloy has the highest density of precipitates with the smallest size. Therefore, the dislocation pinning effect of the DCAT specimens are the strongest, which exhibit the highest yield strength accordingly. In addition, the uniformly distributed precipitates in the matrix with a large ratio of long and short axes can suppress the anisotropy caused by elongated grains.
Full article
(This article belongs to the Special Issue Microstructure, Mechanical and Tribological Properties of Alloys)
Open AccessReview
Studies on the Quality of Joints and Phenomena Therein for Welded Automotive Components Made of Aluminum Alloy—A Review
by
Bogdan Derbiszewski, Andrzej Obraniak, Adam Rylski, Krzysztof Siczek and Marek Wozniak
Coatings 2024, 14(5), 601; https://doi.org/10.3390/coatings14050601 (registering DOI) - 10 May 2024
Abstract
To fulfill the need to limit automotive emissions, reducing vehicle weight is widely recommended and achieved in many ways, both by the construction of individual elements of the vehicle and by the selection of light materials, including Al alloys. Connecting these elements with
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To fulfill the need to limit automotive emissions, reducing vehicle weight is widely recommended and achieved in many ways, both by the construction of individual elements of the vehicle and by the selection of light materials, including Al alloys. Connecting these elements with each other and with elements made of iron alloys can be realized, inter alia, by welding or stir welding. However, the quality of the welds obtained varies widely and depends on many design, operational, and environmental factors. The present study focused on a review of various welding techniques used to join both similar and dissimilar Al alloys utilized in the automotive industry, the effect of various process parameters on weld quality, and the phenomena observed in such welds. The research methodology was based on the analysis of the content of articles from main databases. Apart from capturing the current state of the art, this review evaluates reaching the possible highest joint quality and welding process disadvantages such as porosity, poor surface quality, a tendency toward hot cracking, and low ductility for the Al alloys applied in the automotive industry.
Full article
(This article belongs to the Special Issue Advances in Processing and Characterization of Metal-Based Nanocomposites Materials towards Development of Functional Applications)
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Open AccessArticle
Controlling the Polymer Ink’s Rheological Properties to Form Single and Stable Droplet
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Zhonghui Du, Lu Zhang, Yushuang Du, Xiaoqing Wei, Xiang Du, Xinyan Lin, Jiajun Liu, Yani Huang, Yan Xue, Ning Zhao and Hongbo Liu
Coatings 2024, 14(5), 600; https://doi.org/10.3390/coatings14050600 (registering DOI) - 10 May 2024
Abstract
The formation of single and stable ink droplets is crucial for producing high-quality functional films in drop-on-demand (DOD) inkjet printing. The stability and singularity of droplet formation are significantly influenced by filament breakup behavior, governed by the rheological parameters of the ink formula.
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The formation of single and stable ink droplets is crucial for producing high-quality functional films in drop-on-demand (DOD) inkjet printing. The stability and singularity of droplet formation are significantly influenced by filament breakup behavior, governed by the rheological parameters of the ink formula. This study explores the droplet formation behavior of Poly3-hexylthiophene (P3HT) ink across various Weber numbers (We) and assesses the impact of the Z value on the formation of single ink droplets. Observations reveal that as the We number increases, droplet morphology transitions from single to double, and eventually to sputtered droplets. Results demonstrate that stable, single droplets form when the We number ≤ 13 and 12 < Z < 34, with a pulse duration of approximately 340 μs. When the We number exceeds 13, the molecular chains of P3HT stretch due to high hydrodynamic forces, resulting in the formation of unwanted satellite droplets.
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(This article belongs to the Special Issue New Functional Coatings and Thin Films for Sensor and Green Energy Technologies)
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Open AccessArticle
Radio-Frequency Conductivity Evaluation Method Based on Surface/Interface Scattering of Metallic Coatings
by
Chongxiao Guo, Ping Wu, Yue Liu and Tongxiang Fan
Coatings 2024, 14(5), 599; https://doi.org/10.3390/coatings14050599 - 10 May 2024
Abstract
Developing non-destructive evaluation methods for the radio frequency (RF) conductivity of conductive coatings can accelerate the performance evaluation and development of wireless communication devices. By using a split-resonator cavity to compare 800 nm copper/graphite and 1000 nm copper/graphite, we found that the RF
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Developing non-destructive evaluation methods for the radio frequency (RF) conductivity of conductive coatings can accelerate the performance evaluation and development of wireless communication devices. By using a split-resonator cavity to compare 800 nm copper/graphite and 1000 nm copper/graphite, we found that the RF conductivity increased by 45.5% and 82.7%, respectively, from 15 GHz to 40 GHz (pure copper was −7.2%), indicating that the bulk materials analysis method is not suitable for coating materials. Combined with electromagnetic wave theory, we believe that the critical factor lies in the additional losses of the electromagnetic waves at the copper/graphite interface and substrate. Based on the skin depth theory, the concept of triple skin depth is proposed to calculate the power loss of copper/graphite at different frequencies, considering rough (including the power loss of the rough surface, copper coatings, copper/graphite interface, and graphite) compared with smooth pure copper . Combined with the relationship between RF conductivity and electromagnetic wave power loss, the conductivity of copper coatings at different frequencies is obtained by analyzing the measured . Compared with the roughness model, the calculation error decreased from 30% to below 7%. Our study provides a theoretical basis for the regulation of the RF conductivity of metal coatings at different frequencies.
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(This article belongs to the Special Issue Nanocomposite Thin Film and Multilayers: Properties and Performance)
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Open AccessArticle
Friction and Wear of Hard Yet Tough TiN Coatings Deposited Using High-Power Impulse Magnetron Sputtering
by
Qian Zhou, Yixiang Ou, Feiqiang Li, Changyu Ou, Wenbin Xue, Bin Liao, Qingsong Hua, Yunfei Xu, Jidong Cao and Guanshu Qu
Coatings 2024, 14(5), 598; https://doi.org/10.3390/coatings14050598 - 10 May 2024
Abstract
The friction and wear response of hard coatings is complex, which largely depends on a good combination of hardness and toughness, and their service life is difficult to predict. Hence, in this work, hard yet tough TiN coatings were deposited using high-power impulse
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The friction and wear response of hard coatings is complex, which largely depends on a good combination of hardness and toughness, and their service life is difficult to predict. Hence, in this work, hard yet tough TiN coatings were deposited using high-power impulse magnetron sputtering at 5–10 kW. With increasing sputtering power, the coatings showed a transition in crystal texture from (200) to (111), along with a refinement in microstructure, leading to an improvement in hardness (H) of 29.8–31.2 GPa and an effective Young’s modulus (E*) of 310–365 GPa. The hard yet tough TiN coatings deposited at 6.5 kW exhibited the highest H/E* and H3/E*2 ratios of 0.097 and 0.29, respectively, as well as the highest fracture toughness of 2.1 MPa·m1/2 and elastic recovery of 42.5%. Accordingly, the coatings possessed an enhanced adhesion and cohesion, in terms of micro-scratch critical load (LC3 = 19.67 N) and HF Rockwell HF1 level. The friction and wear response of hard yet tough TiN coatings under the normal load of 1–10 N were investigated to explore their durability and predict their critical load up to failure. Wear mechanisms changed from oxidative to severe abrasive wear, with load increasing from 1 to 10 N. At 2–5 N, a combination of oxidative and abrasive wear was observed. The coatings maintained their integrity up to the critical load of 9.4 N before failure event, with a maximum wear track depth of 1.8 μm, indicating their durability under the loading conditions.
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(This article belongs to the Section Corrosion, Wear and Erosion)
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Open AccessReview
Development and Application of Intelligent Coating Technology: A Review
by
Xiaoyi Chen, Bingbing Zheng, Shujing Zhou, Chengyang Shi, Yiwei Liang and Lina Hu
Coatings 2024, 14(5), 597; https://doi.org/10.3390/coatings14050597 - 9 May 2024
Abstract
Coating technology, as a part of surface engineering, has shown remarkable potential in future industrial applications. With the continuous development and improvement of coating technology, coatings have gradually become an indispensable part of industrial manufacturing, possessing various excellent properties and characteristics, such as
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Coating technology, as a part of surface engineering, has shown remarkable potential in future industrial applications. With the continuous development and improvement of coating technology, coatings have gradually become an indispensable part of industrial manufacturing, possessing various excellent properties and characteristics, such as superhydrophobicity and self-cleaning, enhanced biological antibacterial properties, and improved corrosion resistance. Intelligent coatings are not only rigid barriers between substrates and the environment but also coatings designed to respond to the environment and improve coating life or achieve certain special functions through this response. Biomimetics is a discipline that studies the structure, function, and behavior of living organisms and applies them to engineering design. Combining bionics with intelligent coating materials can not only improve the performance and functionality of intelligent coatings but also create more intelligent coating materials. This paper includes advanced superhydrophobic intelligent coatings, anticorrosion intelligent coatings, biological antibacterial intelligent coatings, and other intelligent coatings with specific functions. We also provide a detailed overview of the preparation methods and technologies of various representative intelligent coatings, as well as their properties and applications, which will offer some valuable references for the development direction of future intelligent coatings.
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(This article belongs to the Special Issue Review Papers Collection for Smart Coatings)
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