Journal Description
Coatings
Coatings
is an international, peer-reviewed, open access journal on coatings and surface engineering published monthly online by MDPI. The Korean Tribology Society (KTS) is affiliated with Coatings and its members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Materials Science, Coatings & Films) / CiteScore - Q2 (Surfaces, Coatings and Films and Surfaces and Interfaces and Materials Chemistry)
- 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
UV-Curable Silicone-Modified Polyurethane Acrylates for Food Freshness Monitoring
Coatings 2024, 14(6), 728; https://doi.org/10.3390/coatings14060728 (registering DOI) - 6 Jun 2024
Abstract
Intelligent materials for monitoring the condition of the packaged food or its surroundings are highly desired to ensure food safety. In this paper, UV-curable silicone-modified materials for monitoring the freshness of high-protein food such as shrimp and pork were prepared from polyurethane acrylates
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Intelligent materials for monitoring the condition of the packaged food or its surroundings are highly desired to ensure food safety. In this paper, UV-curable silicone-modified materials for monitoring the freshness of high-protein food such as shrimp and pork were prepared from polyurethane acrylates with covalent-grafted neutral red groups and thiol silicone resin. The UV-curable materials exhibited visible pH-sensitive performance and long-term color stability because their color did not change when they were immersed in aqueous solutions with different pH values for 20 min, and the color remained even when they were immersed for over 5 h. The distinctive color variation in the UV coatings makes them suitable as potential pH-sensitive sensors. These pH-sensitive intelligent materials can be applied to monitor the freshness of high-protein food such as shrimp and pork. Additionally, the thermal stability and adhesive properties of the UV-curable materials were also studied. A conclusion can be drawn that the covalent bonding of neutral red groups onto a silicone-modified polymer matrix is an ideal strategy for developing pH-sensitive intelligent materials with good pH stability for monitoring the freshness of high-protein food.
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(This article belongs to the Special Issue Advanced Polymeric Materials and Coatings: Synthesis, Properties and Applications)
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Open AccessArticle
A Comparative Study on the Wear Behavior of Quenched-and-Partitioned Steel (Q&P) and Martensite Steel (Q&T)
by
Jian Zheng, Wei Li and Jie Li
Coatings 2024, 14(6), 727; https://doi.org/10.3390/coatings14060727 (registering DOI) - 6 Jun 2024
Abstract
The wear resistance of quenched-and-partitioned steel (Q&P) compared to martensite steel (Q&T) remains unclear. In this research, the wear resistance of Q&P steel and Q&T steel was researched by the means of the abrasive wear (AW) and impact abrasive wear (IAW) tests. The
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The wear resistance of quenched-and-partitioned steel (Q&P) compared to martensite steel (Q&T) remains unclear. In this research, the wear resistance of Q&P steel and Q&T steel was researched by the means of the abrasive wear (AW) and impact abrasive wear (IAW) tests. The results show that abrasive ploughing was the main reason causing the material loss of Q&P and Q&T steel, while Q&T steel was subjected to severe fatigue spalling in the impact abrasive wear tests. Under the abrasive wear test, Q&T steel has better wear resistance due to its higher initial hardness. Under the impact abrasive wear test, Q&P steel has better wear resistance. This is because the formation of the deformed layer, which consists of finer grains and newly formed martensite in the worn subsurface, increased the hardness of the Q&P steel, causing the hardness of the worn subsurface in Q&P steel to be higher than that of Q&T steel. Furthermore, Q&P steel has better resistance to cracks that nucleate and propagate compared to Q&T steel. As a result, less material loss was caused by fatigue spalling in Q&P steel under the impact abrasive wear tests.
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(This article belongs to the Special Issue Advanced Surface Technology and Application)
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Open AccessArticle
Automated Crack Detection in 2D Hexagonal Boron Nitride Coatings Using Machine Learning
by
Md Hasan-Ur Rahman, Bichar Dip Shrestha Gurung, Bharat K. Jasthi, Etienne Z. Gnimpieba and Venkataramana Gadhamshetty
Coatings 2024, 14(6), 726; https://doi.org/10.3390/coatings14060726 - 6 Jun 2024
Abstract
Characterizing defects in 2D materials, such as cracks in chemical vapor deposited (CVD)-grown hexagonal boron nitride (hBN), is essential for evaluating material quality and reliability. Traditional characterization methods are often time-consuming and subjective and can be hindered by the limited optical contrast of
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Characterizing defects in 2D materials, such as cracks in chemical vapor deposited (CVD)-grown hexagonal boron nitride (hBN), is essential for evaluating material quality and reliability. Traditional characterization methods are often time-consuming and subjective and can be hindered by the limited optical contrast of hBN. To address this, we utilized a YOLOv8n deep learning model for automated crack detection in transferred CVD-grown hBN films, using MATLAB’s Image Labeler and Supervisely for meticulous annotation and training. The model demonstrates promising crack-detection capabilities, accurately identifying cracks of varying sizes and complexities, with loss curve analysis revealing progressive learning. However, a trade-off between precision and recall highlights the need for further refinement, particularly in distinguishing fine cracks from multilayer hBN regions. This study demonstrates the potential of ML-based approaches to streamline 2D material characterization and accelerate their integration into advanced devices.
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(This article belongs to the Special Issue Advances in Nanostructured Thin Films and Coatings, 2nd Edition)
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Open AccessArticle
Development of pH Indicator Composite Films Based on Anthocyanins and Neutral Red for Monitoring Minced Meat and Fish in Modified Gas Atmosphere (MAP)
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Marwa Faisal, Tomas Jacobson, Lene Meineret, Peter Vorup, Heloisa N. Bordallo, Jacob Judas Kain Kirkensgaard, Peter Ulvskov and Andreas Blennow
Coatings 2024, 14(6), 725; https://doi.org/10.3390/coatings14060725 - 6 Jun 2024
Abstract
Fresh meat and fish are widely consumed foods with short and very short shelf lives, respectively. Efficient supply chains and the judicious use of food packaging are the most effective means of extending shelf life and thus reducing food waste and improving food
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Fresh meat and fish are widely consumed foods with short and very short shelf lives, respectively. Efficient supply chains and the judicious use of food packaging are the most effective means of extending shelf life and thus reducing food waste and improving food safety. Food packaging that allows for the use of a modified atmosphere (MAP) is effective in extending the period where the food is both palatable and safe. However, monitoring the state of aging and the onset of spoilage of the product poses challenges. Microbial counts, pH measurements, and sensory evaluations are all informative but destructive and are therefore only useful for monitoring quality via sampling. More attractive would be a technology that can follow the progress of ageing in an individual product while leaving the food packaging intact. Here, we present a pH indicator to be placed inside each package that may be read by the naked eye. It is a colorimetric indicator with a matrix made of pure amylose (AM; 99% linear α-glucans) and cellulose nanofibers (CNFs). Suitable mechanical properties of films cast of the two polysaccharides were achieved via the optimization of the blending ratio. The films were loaded with either of two pH indicators: anthocyanin extracts from red cabbage (RCA) and the synthetic dye neutral red (NR). Mechanical, thermal, permeability, microstructural, and physical properties were tested for all composite films. Films with 35% CNF (35AC-RCA) and (35AC-NR) were selected for further study. Minced meat was packaged under MAP conditions (70% O2 + 30% CO2), while minced fish was packaged under MAP (70% N2 + 30% CO2) and stored at 5 °C for 20 days. Microbial growth, pH, and sensory scores of the minced meat systems differentiated between fresh (0–6 days) and medium-fresh (7–10 days), and minced fish between fresh (0–10 days) and medium-fresh (11–20 days). The total color difference showed that the RCA indicator was able to differentiate between fresh (red) and medium-fresh (pink-red) minced meat, while for minced fish, this indicator discriminated between three stages: fresh (red), medium-fresh (pink-red), and spoiled (pink-blue). The NR indicator failed to discriminate the freshness of either meat or fish under the effect of MAP. Pearson correlation statistical models showed a correlation between color change of the indicator, pH, content of gases, and gas content. In summary, RCA immobilized in an AM + 35% CNF nanocomposite film can monitor the freshness of packaged minced meat/fish under the effect of MAP via color change that may be evaluated with the naked eye.
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(This article belongs to the Special Issue Novel Advances in Food Contact Materials)
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Open AccessArticle
The Effect of Deposition Temperature on TiN Thin Films for the Electrode Layer of 3D Capacitors Prepared by Atomic Layer Deposition
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Xingyu Chen, Jing Zhang, Lingshan Gao, Faqiang Zhang, Mingsheng Ma and Zhifu Liu
Coatings 2024, 14(6), 724; https://doi.org/10.3390/coatings14060724 - 5 Jun 2024
Abstract
The TiN thin film is considered a promising electrode layer for 3D capacitors. In this study, TiN thin films were prepared on Si substrates using atomic layer deposition (ALD) at various temperatures from 375 °C to 475 °C. The crystallization behavior, microstructure, and
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The TiN thin film is considered a promising electrode layer for 3D capacitors. In this study, TiN thin films were prepared on Si substrates using atomic layer deposition (ALD) at various temperatures from 375 °C to 475 °C. The crystallization behavior, microstructure, and conductance properties of those TiN thin films were investigated. The resistivity of TiN thin films deposited on Si wafers can reach as low as 128 μΩ·cm. TiN thin films showed lower resistivity and worse uniformity with the deposition temperature increasing. In addition, the aging of TiN thin films may weaken the device performance. Optimized deposition parameters were found and full-coverage deposition of thin films on the wall of deep holes with an aspect ratio of approximately 14 has been successfully achieved. The results would be a good reference for the development of 3D capacitors and other microelectronics components.
Full article
(This article belongs to the Special Issue Thin-Film Synthesis, Characterization and Properties)
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Open AccessArticle
Optimum Design of Coaxial Hydraulic Sealing Systems Made from Polytetrafluoroethylene and Its Compounds
by
Andrea Deaconescu and Tudor Deaconescu
Coatings 2024, 14(6), 723; https://doi.org/10.3390/coatings14060723 - 5 Jun 2024
Abstract
Fluidic actuation systems are optimizable as to energy consumption by reducing the friction in the hydraulic cylinders. Polymeric materials with special antifriction properties and good resistance to hydraulic fluids can be deployed to enhance the performance of hydraulic cylinders. Small friction forces can
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Fluidic actuation systems are optimizable as to energy consumption by reducing the friction in the hydraulic cylinders. Polymeric materials with special antifriction properties and good resistance to hydraulic fluids can be deployed to enhance the performance of hydraulic cylinders. Small friction forces can also be ensured by facilitating the hydrodynamic separation of the elements of the friction tribosystem, namely the seal and sealed-off surface, respectively. The study presented in this paper analyzed the hydrodynamic separation phenomenon in hydraulic cylinders with coaxial sealing systems of the pistons. The process underlying the forming of the fluid film between the seal and its contact surface was considered and the formula for calculating film thickness was deduced. This paper presents graphs that describe the variation of the fluid film thickness versus the dimensional and material characteristics of the sealing systems. The study yielded recommendations as to the most adequate polymeric material to be used and the optimum dimensional characteristics of the seal.
Full article
(This article belongs to the Special Issue Friction, Wear, Lubrication and Mechanics of Surfaces and Interfaces)
Open AccessArticle
In Situ Thermal Interactions of Cu-Based Anti-Corrosion Coatings on Steel Implemented by Surface Alloying
by
Huda Hanif Khan, Tong Wang, Lihong Su, Huijun Li, Qiang Zhu, Ana Yang, Zigang Li, Wei Wang and Hongtao Zhu
Coatings 2024, 14(6), 722; https://doi.org/10.3390/coatings14060722 - 5 Jun 2024
Abstract
Incorporating expensive alloying elements into bulk steel for corrosion protection is undesirable, considering that only the surfaces are exposed to aggressive environments. Therefore, this work focused on developing and optimizing a new surface functioning technology through in situ observation of thermal interactions between
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Incorporating expensive alloying elements into bulk steel for corrosion protection is undesirable, considering that only the surfaces are exposed to aggressive environments. Therefore, this work focused on developing and optimizing a new surface functioning technology through in situ observation of thermal interactions between the metallic powders at elevated temperatures. The study revealed that the Cu-Ni powder mixture, with 12.5 wt% Ni, began to melt at 1099.5 °C and was fully melted at 1175 °C, significantly different from the Cu-Ni solid solution and bulk Cu or Ni. As a result of high-temperature reactions, copper penetration of up to 35 µm for pure copper and 55 µm for copper-chromium composite coatings occurred due to liquid metal corrosion. In contrast, the copper-nickel composite coating exhibited a cupronickel solution microstructure with FeNi dendrites and a nickel-rich transition layer. This cupronickel coating, with a chemical composition of 89.3 wt% Cu, 6.2 wt% Ni, and 4.5 wt% Fe, demonstrated uniform thickness, superior surface morphology, and continuous coverage on the steel substrate. Furthermore, the Ni-rich transition layer played a vital role in preventing copper penetration along the grain boundary of the steel matrix while forming a chemical binding between the coating and the substrate. The practicality of the coating was further confirmed through the hot-rolling procedure and subsequent electrochemical corrosion tests, which resulted in a 44% improvement in corrosion resistance.
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(This article belongs to the Special Issue Surface Science of Degradation and Surface Protection)
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Open AccessArticle
Performance of Ferronickel Slag Powder Soil Cement under Freshwater Curing Conditions
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Lin Liu, Sanshan Chen, Feng Chen, Liang He and Weizhen Chen
Coatings 2024, 14(6), 721; https://doi.org/10.3390/coatings14060721 - 5 Jun 2024
Abstract
Ferronickel slag is the solid waste slag produced by smelting nickel–iron alloy. After grinding ferronickel slag into powder, it has potential chemical activity. It can partially replace cement and reduce the amount of cement, and is conducive to environmental protection. The mechanical properties
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Ferronickel slag is the solid waste slag produced by smelting nickel–iron alloy. After grinding ferronickel slag into powder, it has potential chemical activity. It can partially replace cement and reduce the amount of cement, and is conducive to environmental protection. The mechanical properties of soil cement were investigated through the compressive strength test and inter-split tensile test of ferronickel slag powder soil cement with different dosages. To further study the mechanism of ferronickel slag powder’s action on soil cement microscopically, the microstructure of soil cement was analyzed by using a scanning electron microscope and nuclear magnetic resonance equipment. The results of the study show that the incorporation of ferronickel slag powder can enhance the compressive and tensile strength of soil cement. The best performance enhancement of ferronickel slag powder was achieved when it was doped with 45% of its mass. The hydration products of soil cement increased with the increase in the doping amount, but the excessive doping of ferronickel slag powder would lead to a weakening of the hydration reaction and a decrease in the strength of the soil cement. At the same time, ferronickel slag powder plays the role of filling the void of soil cement. With the increase in ferronickel slag powder, the large pores inside the soil cement are reduced and the structure is denser.
Full article
(This article belongs to the Special Issue Recent Progress in Reinforced Concrete and Building Materials)
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Open AccessArticle
Microstructure Evolution in Magnetron-Sputtered WC/SiC Multilayers with Varied WC Layer Thicknesses
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Tongzhou Li, Zhe Zhang, Zile Wang, Li Jiang, Runze Qi, Qiushi Huang, Zhong Zhang and Zhanshan Wang
Coatings 2024, 14(6), 720; https://doi.org/10.3390/coatings14060720 - 5 Jun 2024
Abstract
Owing to the superior quality of the interface, WC/SiC multilayers have been considered promising candidates for X-ray Laue lenses in nano-focusing facilities and supermirrors in X-ray telescopes. To investigate the microstructure evolution in WC/SiC multilayers, a set of periodic multilayers was prepared with
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Owing to the superior quality of the interface, WC/SiC multilayers have been considered promising candidates for X-ray Laue lenses in nano-focusing facilities and supermirrors in X-ray telescopes. To investigate the microstructure evolution in WC/SiC multilayers, a set of periodic multilayers was prepared with varied WC layer thicknesses ranging from 1.0 nm to 10.0 nm while keeping the thickness of the SiC layer constant at 3.0 nm. These samples were characterized using various analytical techniques, including GIXR, AFM, and XRD. An aperiodic WC/SiC multilayer sample was analyzed by TEM, EDX, and SAED to further study the chemical and structural changes while the thickness of the WC layer increased. The results indicate that the WC layer of the WC/SiC multilayer changes from amorphous to crystalline with increasing layer thickness. The crystalline state of the WC layer change as the thickness increases. Meanwhile, the carbon atoms migrate noticeably to the interface as the WC layer becomes thicker, which smoothens the interfacial defects caused by the crystalline state transition. This migration of carbon is one of the key factors contributing to the smooth interface in WC/SiC multilayers.
Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
Open AccessArticle
Cutting Performance of a Longitudinal and Torsional Ultrasonic Vibration Tool in Milling of Inconel 718
by
Hang Zhang, Guosheng Su, Yan Xia, Peirong Zhang, Binxun Li, Yujing Sun, Jin Du and Bin Fang
Coatings 2024, 14(6), 719; https://doi.org/10.3390/coatings14060719 - 5 Jun 2024
Abstract
Inconel 718 has excellent thermal and chemical properties and is widely used in the manufacture of aerospace parts; however, there are some problems in the machining of Inconel 718, such as a large milling force, serious tool wear, and poor surface quality. In
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Inconel 718 has excellent thermal and chemical properties and is widely used in the manufacture of aerospace parts; however, there are some problems in the machining of Inconel 718, such as a large milling force, serious tool wear, and poor surface quality. In this research, a type of longitudinal–torsional ultrasonic milling (LTUM) tool is designed based on theoretical computations and FEM simulation analysis. To verify the design rationality of the developed LTUM tool, milling experiments are performed. It is verified that the LTUM tool can realize an elliptical vibration path at the tool tip. The resonance frequency of the tool is 21.32 kHz, the longitudinal amplitude is 6.8 µm, and the torsional amplitude is 1.4 µm. In the milling of Inconel 718, the experimental data of LTUM are compared with those of conventional milling (CM). The comparative experiments show that the LTUM tool can effectively lessen the milling force and tool wear in the milling of Inconel 718, improve the surface quality, inhibit the generation of burrs, and improve the chip breaking ability. The application potential of the LTUM tool in high-performance milling of Inconel 718 parts is proven.
Full article
(This article belongs to the Special Issue Enhancing Machining Processes With Advanced Tool, Coating Materials and Cutting Technology)
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Open AccessArticle
Preparation of ZnO Ultrasonic Transducer by Radio-Frequency Sputtering and Its Application in Bolt Preload Detection
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Yi Xu, Yanghui Jiang, Kai Tan, Wenrui Yang, Jie Lv, Daijun Deng, Dengguo Zheng, Changsheng Li, Jun Zhang and Bing Yang
Coatings 2024, 14(6), 718; https://doi.org/10.3390/coatings14060718 - 5 Jun 2024
Abstract
Accurate detection of the preload force of tower crane bolts is of great significance for the stable and safe operation of the equipment. The method of contact ultrasonic detection of bolt preload has always been the focus of attention, which can realize rapid
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Accurate detection of the preload force of tower crane bolts is of great significance for the stable and safe operation of the equipment. The method of contact ultrasonic detection of bolt preload has always been the focus of attention, which can realize rapid in situ detection without damaging the parts. In order to improve the accuracy and convenience of ultrasonic measurement of bolt preload and meet the urgent needs of the actual industrial site for high-precision measurement of bolt preload, we propose to prepare ZnO piezoelectric coatings as functional layers for ultrasonic transducers using magnetron sputtering and deposit them directly on bolts. The growth behavior of the ZnO coatings is investigated by varying the sputtering power, sputtering gas pressure and target substrate distance, and the morphology, structure, and properties are characterized and analyzed. The ZnO piezoelectric coatings with high c-axis optimal growth orientation and excitation of ultrasonic longitudinal waves were finally obtained and verified to be effective and stable when applied to the bolts.
Full article
(This article belongs to the Section Surface Engineering for Energy Harvesting, Conversion, and Storage)
Open AccessArticle
Preparation and Thermal Conductivity of Alumina/Graphene/Waterborne Polyurethane Composite
by
Xiang Zhang, Min Zhang, Dong Han, Chen Ma and Xiaolei Su
Coatings 2024, 14(6), 717; https://doi.org/10.3390/coatings14060717 - 5 Jun 2024
Abstract
In this paper, a series of alumina/waterborne polyurethane composites was prepared, and the effects of different amounts of alumina on the thermal conductivity and insulation properties of the composites were studied. In addition, alumina/graphene/waterborne polyurethane composites were prepared by co-doping graphene and alumina
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In this paper, a series of alumina/waterborne polyurethane composites was prepared, and the effects of different amounts of alumina on the thermal conductivity and insulation properties of the composites were studied. In addition, alumina/graphene/waterborne polyurethane composites were prepared by co-doping graphene and alumina into waterborne polyurethane to improve the heat conduction path. The synergistic effect between different fillers formed a denser heat conduction network. The added amount of alumina is 60 wt%. When the amount of graphene added is 2 wt%, the thermal conductivity of the composite can reach 1.049 W/(m·K), which is twice that of the alumina-filled composite, which is obviously better than that of the single-filler filling. Compared with the system only adding alumina, it seeks to improve thermal conductivity while maintaining good insulation. The results show that it is an effective way to improve the thermal conductivity and insulation properties of materials when different fillers are compounded.
Full article
(This article belongs to the Section Functional Polymer Coatings and Films)
Open AccessArticle
Tribological and Mechanical Behavior of Automotive Crankshaft Steel Superficially Modified Using the Boriding Hardening Process
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Enrique Hernández-Sánchez, Diego Hernández-Domínguez, Raúl Tadeo-Rosas, Yesenia Sánchez-Fuentes, Luz Alejandra Linares-Duarte, Carlos Orozco-Álvarez, José Guadalupe Miranda-Hernández and Rafael Carrera-Espinoza
Coatings 2024, 14(6), 716; https://doi.org/10.3390/coatings14060716 - 5 Jun 2024
Abstract
One of the primary challenges in the automotive industry is the wear of engine components, such as the crankshaft and camshaft, which is the most pronounced during the engine’s startup phase, when the amount of lubricant fluid is at its lowest. This study
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One of the primary challenges in the automotive industry is the wear of engine components, such as the crankshaft and camshaft, which is the most pronounced during the engine’s startup phase, when the amount of lubricant fluid is at its lowest. This study aims to enhance the surface wear resistance of automotive crankshaft steel by applying a boriding thermochemical process. This process forms a hard surface layer on the steel, improving its mechanical properties and bolstering its wear resistance, especially under dry conditions. Boride layers were achieved using the powder-pack boriding process in a conventional furnace, with meticulous treatment times of 2, 4, and 6 h at a constant temperature of 950 °C. The nature of the layers was analyzed using X-ray diffraction, and their tribological behavior was evaluated using the pin-on-disk test. The growth of the layers was directly proportional to the treatment time and was estimated at 145 µm and 48 µm for the 6 and 2 h of treatment, respectively. The surface hardness increased from 320 HV for the non-treated steel to 2034 HV for the sample exposed to 950 °C for 6 h. The results indicate a significant reduction in the coefficient of friction from 0.43 for the non-treated steel to 0.12 for the samples exposed to 950 °C for 6 h, suggesting potential wear protection during the engine starting period.
Full article
(This article belongs to the Special Issue Surface Treatment on Metals and Their Alloys)
Open AccessArticle
Analyzing the Debinding Step of Ti64 Parts Fabricated by 3D Printing Extrusion
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Ana Silvia González-Pedraza, Didier Bouvard, Jean-Michel Missiaen, Luis Olmos, Héctor Javier Vergara-Hernández, Jose Lemus-Ruiz and Julio César Villalobos
Coatings 2024, 14(6), 715; https://doi.org/10.3390/coatings14060715 - 5 Jun 2024
Abstract
The aim of this work is to analyze the effect of the heating rate used during the debinding step on the consolidation of parts fabricated by additive manufacturing using the 3D printing extrusion of Ti64 samples. The cylindrical samples print by extruding MIM
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The aim of this work is to analyze the effect of the heating rate used during the debinding step on the consolidation of parts fabricated by additive manufacturing using the 3D printing extrusion of Ti64 samples. The cylindrical samples print by extruding MIM pellets of Ti64 mixed with a binder. Dilatometry tests follow the densification of the samples by using three different heating rates during the heating stage. All the samples then undergo the same thermal cycle of sintering. SEM and XRD analyze the microstructure. Microhardness and compression tests evaluate the mechanical properties of the sintered samples. We analyze the corrosion behavior under Hank’s solution. The results indicated that the heating rate used during the debinding step affects the densification by reducing this as the heating rate increases. After sintering, a lower relative density is reached, resulting in decreased mechanical properties and corrosion resistance. The Young’s modulus and yield strength correspond well with those of the Ti64 samples prepared by other techniques with similar porosities. Despite the remaining porosity, the parts fabricated by SLM had worse corrosion behavior than ours. The main conclusion is that the isothermal step during debinding is not necessary to ensure complete binder elimination, which will reduce the process time and thus, the fabrication costs of parts by this technique.
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(This article belongs to the Special Issue Recent Advances in Surface Functionalisation)
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Exploring the Impact of Spray Process Parameters on Graphite Coatings: Morphology, Thickness, and Tribological Properties
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Adedoyin Abe, Josue A. Goss and Min Zou
Coatings 2024, 14(6), 714; https://doi.org/10.3390/coatings14060714 - 5 Jun 2024
Abstract
This study explores, through a full factorial experimental design, the effects of graphite concentration and spray flow rate on the morphology, thickness, and tribological performance of graphite coatings for potential tribological applications. Coatings were applied to rough substrates using varying concentrations and flow
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This study explores, through a full factorial experimental design, the effects of graphite concentration and spray flow rate on the morphology, thickness, and tribological performance of graphite coatings for potential tribological applications. Coatings were applied to rough substrates using varying concentrations and flow rates, followed by analysis of their morphological characteristics, roughness, thickness, coefficient of friction (COF), and wear behavior. The results revealed distinct differences in the coating morphology based on flow rate, with low-flow-rate coatings exhibiting a porous structure and higher roughness, while high-flow-rate coatings displayed denser structures with lower roughness. A COF as low as 0.09 was achieved, which represented an 86% reduction compared to uncoated steel. COF and wear track measurements showed that thickness was influential in determining friction and the extent of wear. Flow rate dictated the coating structure, quantity of transfer film on the ball, and the extent of graphite compaction in the wear track to provide a protective layer. SEM and elemental analysis further revealed that graphite coatings provided effective protection against wear, with graphite remaining embedded in the innermost crevices of the wear track. Low flow rates may be preferable for applications requiring higher roughness and porosity, while high flow rates offer advantages in achieving denser coatings and better wear resistance. Overall, this study highlights the importance of optimizing graphite concentration and spray flow rate to tailor coating morphology, thickness, and tribological performance for practical applications.
Full article
(This article belongs to the Special Issue Friction, Wear, Lubrication and Mechanics of Surfaces and Interfaces)
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Open AccessArticle
Dispersed CeO2 Nanorods with Low-Speed Mixing for Mechanical Properties Promotion of PTA Steel Coatings
by
Jun-Yu Yue, Peng-Cheng Jiao, Yi Sui, Fei Lu, Rui-Ying Zhang, Wei-Dong Chen and Li-Sha Zhao
Coatings 2024, 14(6), 713; https://doi.org/10.3390/coatings14060713 - 5 Jun 2024
Abstract
The plasma-transferred arc technology has been observed to induce preferential grain orientation in multiple directions, leading to nonuniform grain growth within the alloy coating material. The addition of nano-oxides can act as heterogeneous nucleation sites, reducing the preferred orientation of grains. In this
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The plasma-transferred arc technology has been observed to induce preferential grain orientation in multiple directions, leading to nonuniform grain growth within the alloy coating material. The addition of nano-oxides can act as heterogeneous nucleation sites, reducing the preferred orientation of grains. In this study, a low-speed mixing method was employed to coat highly dispersed CeO2 nanorods (CNRs) onto the surface of 14Cr2NiSiVMn alloy powder particles. The aim was to analyze the influence of dispersed CNRs on grain growth orientation in different directions and the refinement and heterogeneous nucleation effect of CNR additives. The addition of 0.5 wt.% CNRs resulted in the refinement of dendritic grains along both the perpendicular and parallel directions to the coating cladding direction, leading to the formation of more uniform equiaxed crystals. The combination of Ce with Si and V elements formed submicron particles, which promoted grain nucleation and reduced defects in the coating. Consequently, the mechanical performance of the sample significantly improved. In the deposition direction, there was a notable improvement in microhardness (20.4%), tensile strength (97.6%), and elongation (59.0%). In the perpendicular deposition direction, the tensile strength increased by 88.1%, and the elongation increased by 33.9%. Additionally, the weight loss due to wear decreased by 44.2%, and the relative wear resistance improved by 79.3%.
Full article
(This article belongs to the Section Plasma Coatings, Surfaces & Interfaces)
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Open AccessRetraction
RETRACTED: Syah et al. The Effect of Structural Phase Transitions on Electronic and Optical Properties of CsPbI3 Pure Inorganic Perovskites. Coatings 2021, 11, 1173
by
Rahmad Syah, Afshin Davarpanah, Mahyuddin K. M. Nasution, Qamar Wali, Dadan Ramdan, Munirah D. Albaqami, Mohamed Ouladsmane and Saja Mohammed Noori
Coatings 2024, 14(6), 712; https://doi.org/10.3390/coatings14060712 - 5 Jun 2024
Abstract
The Coatings Editorial Office retracts the article entitled “The Effect of Structural Phase Transitions on Electronic and Optical Properties of CsPbI3 Pure Inorganic Perovskites” [...]
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Open AccessArticle
Effects of Dynamic Flow Rates on the In Vitro Bio-Corrosion Behavior of Zn-Cu Alloy
by
Xin Zhang, Lu Zhang, Linyuan Han, Jing Bai, Zhihai Huang, Chao Guo, Feng Xue, Paul K. Chu and Chenglin Chu
Coatings 2024, 14(6), 711; https://doi.org/10.3390/coatings14060711 - 5 Jun 2024
Abstract
In the complicated real physiological environment in vivo, body fluids and blood are constantly replenished and move dynamically, and therefore, the dynamic impacts of bodily fluids and blood need to be considered in the evaluation of biodegradable materials. However, little research has
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In the complicated real physiological environment in vivo, body fluids and blood are constantly replenished and move dynamically, and therefore, the dynamic impacts of bodily fluids and blood need to be considered in the evaluation of biodegradable materials. However, little research has been conducted on the impact of dynamic flowing circumstances on the corrosion characteristics of zinc-based alloys, particularly at high flow rates. The effects of various flow rates on the bio-corrosion behavior of the Zn-Cu alloy are thoroughly explored in this study. A model is developed using finite element analysis to investigate the impacts of flow rates and fluid-induced shear stress. The results reveal that the corrosion process of the Zn-Cu alloy is significantly accelerated by a higher flow rate, and a large fluid-induced shear stress caused by the boundary effect is found to promote corrosion. Furthermore, the empirical power function between the average flare rates in Hank’s solution and the corrosion rates of the Zn-Cu alloy is established by numerical simulation. The results provide insightful theoretical and experimental guidance to improve and evaluate the efficacy and lifespan of biomedical zinc-based alloy implants.
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(This article belongs to the Section Corrosion, Wear and Erosion)
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Open AccessReview
Research Progress of Superhydrophobic Coatings in the Protection of Earthen Sites
by
Yisi Liu, Qian Li, Ruiting Zhou and Renaguli Yusufu
Coatings 2024, 14(6), 710; https://doi.org/10.3390/coatings14060710 - 5 Jun 2024
Abstract
As an important part of human cultural heritage, earthen sites are subject to damage caused by a variety of environmental factors, such as cracking, weathering, and flooding. Due to the low mechanical strength of earthen site materials, especially in humid environments, they are
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As an important part of human cultural heritage, earthen sites are subject to damage caused by a variety of environmental factors, such as cracking, weathering, and flooding. Due to the low mechanical strength of earthen site materials, especially in humid environments, they are susceptible to hazards like moisture penetration, freeze–thaw cycles, and biological invasion. Superhydrophobic coatings show promising potential in the protection of earthen sites, with key properties that include waterproof performance, breathability, robustness, and transparency. By exploring various material systems and preparation methods, the current state of research on the protection of building materials with superhydrophobic materials has been demonstrated, highlighting advantages in the corrosion resistance, self-cleaning, frost prevention, anti-scaling, and other aspects. At the same time, it also points out the challenges faced in the practical application of earthen site protection and the prospects for future research. These include enhancing the bonding strength between the coating and soil particles, improving durability and breathability, and developing large-scale, low-cost, and efficient coating construction techniques.
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(This article belongs to the Special Issue New Trends in Conservation and Restoration of Cultural Heritage)
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Open AccessRetraction
RETRACTED: Al-Kahtani et al. Influence of Different Rotations of Organic Formamidinium Molecule on Electronic and Optical Properties of FAPbBr3 Perovskite. Coatings 2021, 11, 1341
by
Abdullah A. Al-Kahtani, Sobia Tabassum, Indah Raya, Ibrahim Hammoud Khlewee, Supat Chupradit, Afshin Davarpanah, Marischa Elveny and Shafaqat Ali
Coatings 2024, 14(6), 709; https://doi.org/10.3390/coatings14060709 - 5 Jun 2024
Abstract
The Coatings Editorial Office retracts the article entitled “Influence of Different Rotations of Organic Formamidinium Molecule on Electronic and Optical Properties of FAPbBr3 Perovskite” [...]
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