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Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications
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Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Corrosion, Wear and Erosion".

Deadline for manuscript submissions: 31 March 2025 | Viewed by 16437

Special Issue Editors

Dr. Lei Guo

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Guest Editor
School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
Interests: thermal barrier coatings; high-temperature corrosion
Special Issues, Collections and Topics in MDPI journals
Dr. Jianwei Dai

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Guest Editor
AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
Interests: thermal barrier coatings; electron beam physical vapor deposition
Dr. Mohammad Reza Loghman-Estarki

E-Mail Website
Guest Editor
Department of Materials Engineering, Malek Ashtar University of Technology, Tehran, Iran
Interests: thermal barrier coating; polymeric thin film; ceramic matrix composite (CMC) coating; anticorrosion coating

Special Issue Information

Dear Colleagues,

We would like to invite you to submit your research to this Special Issue, "Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications". As one of the key technologies for aero-engines, protective coatings have been applied to hot-section components of combustors, high-pressure turbine (HPT) blades, and HPT nozzles for decades. Coatings enable the aero-engines to operate at higher temperatures; therefore, efficiency can be improved, emissions can be reduced, and thrust can be increased. On the other hand, the higher operating temperature leads to some unavoidable limitations for coatings’ use, including accelerated sintering, phase transformation, corrosion resulting from environmental deposits (CMAS) and molten salt, etc. These cause the premature failure of coatings. In the interest of improving the performance of coatings and elongating their lifetime, we face a practical requirement for alternative coating materials to be developed, with progress required in coating fabrication science and technologies, coating design strategies, corrosion protective methods, and failure mechanisms.

This Special Issue will present the latest designs and developments in protective coatings applied for aero-engines through original research papers and review articles from leading scientists and engineers across the world.

In particular, the topics of interest include, but are not limited to, the following:

  • Novel material candidates for protective coating applications at high temperatures;
  • Fabrication science of protective coatings using APS, EB-PVD, SPS, and PS-PVD technologies;
  • Corrosion behavior of protective coatings in the presence of CMAS and/or molten salts;
  • Corrosion protective methods and corrosion resistance mechanisms of protective coatings;
  •  Thermal cycling performance and failure analysis of protective coatings;
  • Long-life designs for protective coatings.

Dr. Lei Guo
Dr. Jianwei Dai
Dr. Mohammad Reza Loghman-Estarki
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • protective coatings (TBCs)
  • materials design
  • coatings preparation
  • corrosion mechanisms and protection
  • thermal cycling
  • long lifetime

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  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (13 papers)

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Research

Jump to: Review, Other

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 804
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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10 pages, 4408 KiB  
Article
Optimization of Lost Foam Coating Performance: Effects of Blade Shape, Stirring Speed, and Drying Temperature on Viscosity, Coating Weight, and Surface Morphology
by Guojin Sun, Zhenggui Li and Qi Wang
Coatings 2024, 14(9), 1106; https://doi.org/10.3390/coatings14091106 - 2 Sep 2024
Viewed by 628
Abstract
The current investigation focuses on the viscosity, coating weight, and surface characteristics of lost foam casting coatings, examining the effects of blade shape, stirring speed, and stirring time. A systematic analysis was conducted to determine how different stirring speeds and durations influenced coating [...] Read more.
The current investigation focuses on the viscosity, coating weight, and surface characteristics of lost foam casting coatings, examining the effects of blade shape, stirring speed, and stirring time. A systematic analysis was conducted to determine how different stirring speeds and durations influenced coating weight and viscosity. The results indicate that the blade shape has a considerable impact on the uniformity and efficacy of the coating, with some designs being far more effective in reaching the optimal viscosity and coating weight through uniformly distributed mixing. Results were consistently obtained when stirring at 800–1200 rpm. It was demonstrated that while stirring speed significantly impacts coating deposition, it has small effect on viscosity. A stirring time of 30 min was found optimal for stabilizing coating weight and viscosity without significant variations. Drying at room temperature produced smoother surfaces with fewer cracks, whereas higher drying temperatures (50 °C) were associated with increased surface roughness and cracking. Crack analysis after drying revealed that coatings mixed with the tri-blade had the lowest tendency to crack, demonstrating its superior capability for even and thorough mixing. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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18 pages, 4992 KiB  
Article
Aging Behaviors of Organic Electrophoretic Coating on Magnesium Alloy
by Xiaoxue Wang, Guohui Wang, Yuan Jing, Kai Zheng, Rongqiao Wang, Xiuchun Liu, Kai Gao, Jingli Sun, Yong Yuan and Fandi Meng
Coatings 2024, 14(8), 952; https://doi.org/10.3390/coatings14080952 - 31 Jul 2024
Viewed by 770
Abstract
VW63Z magnesium alloy, known for its high strength-to-weight ratio and excellent mechanical properties, is a promising candidate for applications in the automotive industries. Among the anti-corrosion technologies for VW63Z alloys, organic electrophoretic coatings have gained significant attention due to their ability to provide [...] Read more.
VW63Z magnesium alloy, known for its high strength-to-weight ratio and excellent mechanical properties, is a promising candidate for applications in the automotive industries. Among the anti-corrosion technologies for VW63Z alloys, organic electrophoretic coatings have gained significant attention due to their ability to provide a uniform and controlled coating thickness, high coating adhesion, and excellent corrosion protection properties. In this work, to investigate the aging behaviors of an organic electrophoretic coating for magnesium alloys, water absorption kinetics curves of the coatings after immersion in 3.5 wt.% NaCl at 20 °C and 40 °C were measured, and parameters such as the saturated water absorption and saturation time of the free film coatings were fitted to determine the densification evolution of the organic coatings. A tensile test was used to test the tensile strength of the organic coating during service to determine the evolution of the strength and toughness of the organic coating. The evolution of wet adhesion of organic coatings with service time was tested by ASTM D4541-02. The impedance spectra of the organic coatings under the above conditions were detected by EIS, and finally, the failure behavior of the organic coatings under immersion was analyzed. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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18 pages, 4576 KiB  
Article
Evaluation of Slurry-Eroded Rubber Surface Using Gloss Measurement
by Wichain Chailad and Liu Yang
Coatings 2024, 14(7), 915; https://doi.org/10.3390/coatings14070915 - 22 Jul 2024
Viewed by 860
Abstract
Slurry erosion testing is essential for evaluating the durability of materials under erosive conditions. This study examines the slurry erosion behaviours of chloroprene rubber (CR) under varying impact conditions to assess its durability. Traditional mass loss methods and qualitative techniques, including microscopy, SEM, [...] Read more.
Slurry erosion testing is essential for evaluating the durability of materials under erosive conditions. This study examines the slurry erosion behaviours of chloroprene rubber (CR) under varying impact conditions to assess its durability. Traditional mass loss methods and qualitative techniques, including microscopy, SEM, and AFM, were employed to analyse eroded CR samples. Results indicate that cumulative material loss in CR increases linearly with sand impingement after approximately 60 kg of sand and correlates with an impact energy of about 30 kJ. The highest erosion rate was found at an impact angle of 15°. Erosion mechanisms vary with impact angle, affecting surface topography from cutting and ploughing at lower angles to deformation and crater formation at higher angles. Despite their efficacy, these methods are time-intensive and costly. This paper presents a novel approach utilising gloss measurement for continuous, non-destructive monitoring of eroded rubber surfaces. Gloss measurements are 24 times faster than traditional mass loss methods. Correlating gloss values with cumulative material loss, steady-state erosion, and impact energy offers significant time savings and an enhanced understanding of the erosion process. Experimental results demonstrate the effectiveness of gloss measurement as a reliable tool in slurry erosion testing of rubbers. The quantitative output from gloss measurements could support proactive maintenance strategies to extend service life and optimise operational efficiency in industrial applications, particularly in the mining industry. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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23 pages, 15975 KiB  
Article
Anodizing of AA2024 Aluminum–Copper Alloy in Citric-Sulfuric Acid Solution: Effect of Current Density on Corrosion Resistance
by Jose Cabral-Miramontes, Noe Cabral-Miramontes, Demetrio Nieves-Mendoza, Maria Lara-Banda, Erick Maldonado-Bandala, Javier Olguín-Coca, Luis Daimir Lopez-Leon, Francisco Estupiñan-Lopez, F. Almeraya Calderon and Citlalli Gaona Tiburcio
Coatings 2024, 14(7), 816; https://doi.org/10.3390/coatings14070816 - 30 Jun 2024
Viewed by 1392
Abstract
Al–Cu alloys are widely used as a structural material in the manufacture of commercial aircraft due to their high mechanical properties such as hardness, strength, low density, and tolerance to fatigue damage and corrosion. One of the main problems of these Al–Cu alloy [...] Read more.
Al–Cu alloys are widely used as a structural material in the manufacture of commercial aircraft due to their high mechanical properties such as hardness, strength, low density, and tolerance to fatigue damage and corrosion. One of the main problems of these Al–Cu alloy systems is their low corrosion resistance. The purpose of this study is to analyze the influence of anodizing parameters on aluminum–copper alloy (AA 2024) using a bath of citric-sulfuric acid with different anodizing current densities on the thickness, microhardness, and corrosion resistance of the anodized layer. Hard anodizing is performed on AA 2024 Al–Cu alloy in mixtures of solutions composed of citric and sulfuric acid at different concentrations for 60 min and using current densities (i) of 0.03, 0.045, and 0.06 A/cm2. Scanning electron microscopy (SEM) was used to analyze the surface morphology and thickness of the anodized layer. The mechanical properties of the hard anodized material are evaluated using the Vickers hardness test. The electrochemical techniques use cyclic potentiodynamic polarization curves (CPPC) according to ASTM-G6 and electrochemical impedance spectroscopy (EIS) according to ASTM-G61 and ASTM-G106, respectively, in the electrolyte of NaCl at 3.5 wt. % as a simulation of the marine atmosphere. The results indicate that corrosion resistance anodizing in citric-sulfuric acid solutions with a current density of 0.06 A/cm2 is the best with a corrosion current density (jcorr) of 1.29 × 10−8 A/cm2. It is possible to produce hard anodizing with citric and sulfuric acid solutions that exhibit mechanical properties and corrosion resistance similar or superior to conventional sulfuric acid anodizing. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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11 pages, 11337 KiB  
Article
The Effects of Induction Plasma Spheroidization on the Properties of Yttrium-Stabilized Zirconia Powders and the Performance of Corresponding Thermal Barrier Coatings for Gas Turbine Engine Applications
by Haoran Peng, Yueguang Yu, Jianxin Dong, Tianjie Shi, Kang Yuan, Zheng Yan and Botian Bai
Coatings 2024, 14(5), 627; https://doi.org/10.3390/coatings14050627 - 16 May 2024
Viewed by 1016
Abstract
To modify the structure of thermal barrier coatings and improve their high-temperature resistance, induction plasma spheroidization (IPS) technology was applied to regulate the structure of YSZ powders in this study. The surface morphology, particle size distribution, phase composition, and internal microstructure of the [...] Read more.
To modify the structure of thermal barrier coatings and improve their high-temperature resistance, induction plasma spheroidization (IPS) technology was applied to regulate the structure of YSZ powders in this study. The surface morphology, particle size distribution, phase composition, and internal microstructure of the conventional agglomerated and spheroidized powders were characterized using scanning electron microscopy and focused ion beam analysis methods. The results showed that the microstructure of the powders presented uneven evolution in the induction plasma stream. Due to the existence of the temperature gradient along the radial direction of the powders, the IPS powders consisted of outer dense shells and internal porous cores. The mechanical property of such shell–core structure was analyzed by using the finite elemental simulation method. In addition, coatings were prepared using the IPS powders and the agglomerated powders. The IPS coating showed improved water-cooling thermal cycling resistance compared to the conventional coating. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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11 pages, 4858 KiB  
Article
Preparation and Corrosion Resistance of OMMT/EP Composite Coatings in Sulfur-Containing Sodium Aluminate Solution
by Jun Xu, Dongyu Li, Hanli Wang and Bianli Quan
Coatings 2024, 14(5), 546; https://doi.org/10.3390/coatings14050546 - 27 Apr 2024
Viewed by 1020
Abstract
Organic montmorillonite (OMMT) was prepared from Na-montmorillonite (MMT) by Hexadecylamine (HDA) modification. The composite material has good smoothness, acidity, and salt resistance. OMMT was characterized using small-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and a video optical contact angle measuring [...] Read more.
Organic montmorillonite (OMMT) was prepared from Na-montmorillonite (MMT) by Hexadecylamine (HDA) modification. The composite material has good smoothness, acidity, and salt resistance. OMMT was characterized using small-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and a video optical contact angle measuring instrument. The results showed that the layer spacing was enlarged from 1.44 nm to 2.87 nm after the modification, and the hydrophobicity performance was greatly improved. The organic modification of MMT was successful. The surface morphology, roughness, and anticorrosion properties of the organic montmorillonite/epoxy (OMMT/EP) composite coating were investigated and compared with those of the epoxy (EP) coating. The OMMT/EP composite coating had a flatter surface than the EP coating. The roughness was reduced from 65.5 nm to 10.3 nm. The electrochemical impedance spectroscopy showed that the composite coating’s thickness positively affected its anticorrosion performance, the corrosion current density (Icorr) decreased with the increase in thickness, and its maximum impedance was much larger than that of EP coating. The protection efficiency of the OMMT/EP composite coating was 77.90%, which is a significant improvement over the EP’s 31.27%. In addition, the corrosion resistance of the composite coating gradually decreased with increasing immersion time, but the change was insignificant. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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13 pages, 4176 KiB  
Article
Influence of Anodic Oxidation on the Organizational Structure and Corrosion Resistance of Oxide Film on AZ31B Magnesium Alloy
by Yuxin Kang, Shufang Yan, Zhanlin Li, Zhigang Wang, Ao Yang, Wen Ma, Weidong Chen and Yinhui Qu
Coatings 2024, 14(3), 271; https://doi.org/10.3390/coatings14030271 - 23 Feb 2024
Cited by 1 | Viewed by 1918
Abstract
Magnesium alloys, notably AZ31B, hold promise for lightweight structural applications in the aerospace, automotive, and biomedical sectors due to their excellent strength-to-weight ratios. The broad adoption of these alloys, however, is hindered by their inherent susceptibility to corrosion, reducing durability and functional integrity [...] Read more.
Magnesium alloys, notably AZ31B, hold promise for lightweight structural applications in the aerospace, automotive, and biomedical sectors due to their excellent strength-to-weight ratios. The broad adoption of these alloys, however, is hindered by their inherent susceptibility to corrosion, reducing durability and functional integrity in corrosive environments. This study explores anodic oxidation as a viable surface treatment to improve the corrosion resistance of the AZ31B magnesium alloy. Focusing on the impact of oxidation voltage on the oxide film’s structural and electrochemical properties, we aim to optimize these characteristics to enhance the alloy’s utility and lifespan significantly. Through detailed analysis of surface and cross-sectional morphologies, film thickness, phase composition, and corrosion resistance, we identify an optimal oxidation voltage of 17.5 V that notably improves the oxide film’s density and corrosion resistance. Through this research, we contribute to the ongoing efforts to overcome the corrosion vulnerability of magnesium alloys, thereby unlocking their full potential in contributing to more sustainable and efficient technological advancements. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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12 pages, 20976 KiB  
Article
Failure Mechanism of Thermal Barrier Coatings on Nozzle Guide Vanes Fabricated from Nickel-Based Single-Crystal Superalloy under Gas Thermal Shock Conditions
by Yufeng Wang, Qiangang Fu, Chenxi Yang, Hui Peng and Hua Zhang
Coatings 2023, 13(12), 2062; https://doi.org/10.3390/coatings13122062 - 9 Dec 2023
Viewed by 1110
Abstract
The objective of this study was to investigate the early failure behavior of thermal barrier coatings on single-crystal nozzle guide vanes under gas thermal shock conditions. The microstructure and mechanical properties of the thermal barrier coating before and after the gas thermal shock [...] Read more.
The objective of this study was to investigate the early failure behavior of thermal barrier coatings on single-crystal nozzle guide vanes under gas thermal shock conditions. The microstructure and mechanical properties of the thermal barrier coating before and after the gas thermal shock tests were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and microhardness testing. The results indicate the presence of a mixed layer containing Ni, Cr, Al, Zr, and O at the base of the ceramic layer, and reveal failure behavior in the thermal barrier coating. The analysis suggests that the incomplete formation of the thermal growth oxide layer between the ceramic layer and the bonding layer, before the deposition of the YSZ ceramic layer, led to the easy diffusion of elements from the bonding layer into the root of the ceramic layer during the gas thermal shock process, resulting in the formation of a mixed layer. In the test environment, significant thermal stress was generated in the mixed layer, leading to transverse cracks and ultimately causing early failure of the thermal barrier coating. Consequently, the “incomplete initial TGO layer” model is proposed. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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12 pages, 28491 KiB  
Article
Simulating the Effect of Depositing an 8YSZ Buffer Layer in P92/Al2O3 on the Thermal Cycles Endurance and Fracture Toughness of the System
by Kezhi Huang, Yu Liu, Weijing Wang, Qinghe Yu, Jing Mi, Lei Hao, Hao Liu, Baolong Yuan, Wei Xiao, Xiaotao Chen, Ziqiang Dong and Ping Wang
Coatings 2023, 13(12), 1999; https://doi.org/10.3390/coatings13121999 - 24 Nov 2023
Viewed by 860
Abstract
The effect of depositing 8YSZ between serving as an intermediate layer of the P92/Al2O3 was analyzed via finite element analysis. The result shows that depositing an 8YSZ buffer coat beneath the Al2O3 will dramatically decrease the maximum [...] Read more.
The effect of depositing 8YSZ between serving as an intermediate layer of the P92/Al2O3 was analyzed via finite element analysis. The result shows that depositing an 8YSZ buffer coat beneath the Al2O3 will dramatically decrease the maximum principal stress in the coating system in thermal shock. The stress intensity factor, KI, and J-integral are also decreased which indicates the crack propagation resistance is improved. Inserting a 100 nm 8YSZ buffer layer could reduce the KI and J-integral by 2 orders of magnitude. Thus, cracks are less likely to initiate and propagate. Moreover, coating an 8YSZ layer between the P92/Al2O3 can significantly change the stress distribution pattern in the Al2O3 coating. The 8YSZ with a proper coefficient of thermal expansion between that of the Al2O3 and P92 and good deformability is an ideal buffer layer to improve the thermal cycle endurance and prolong the service life of the Al2O3 coating. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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10 pages, 11055 KiB  
Article
Impact of Temperature on the Tensile Properties of Hypereutectic High-Entropy Alloys
by Wei Jiang, Shuaishuai Wu, Xuehui Yan, Haochen Qiu, Shengli Guo, Baohong Zhu and Hanjun Zhang
Coatings 2023, 13(11), 1836; https://doi.org/10.3390/coatings13111836 - 27 Oct 2023
Cited by 1 | Viewed by 1089
Abstract
Eutectic high-entropy alloys (EHEAs) can achieve a balance of high strength and ductility. It has been found that the mechanical properties of hypoeutectic high-entropy alloys are superior to those of EHEAs. In this work, hypereutectic Al1.1CoCrFeNi2.1 alloy was prepared, and [...] Read more.
Eutectic high-entropy alloys (EHEAs) can achieve a balance of high strength and ductility. It has been found that the mechanical properties of hypoeutectic high-entropy alloys are superior to those of EHEAs. In this work, hypereutectic Al1.1CoCrFeNi2.1 alloy was prepared, and the mechanical properties in a wide temperature range were studied. The presence of both soft ordered L12 and hard BCC (B2) phases results in a combination of ductile and brittle fracture modes. The Al1.1CoCrFeNi2.1 hypereutectic high-entropy alloy contains more primary soft L12 phases, which ensure excellent ductility. Moreover, the Orowan by-passing mechanism caused by the B2 precipitates increases in the strength of the alloy for low-temperature tensile tests (−100 °C and 23 ± 2 °C). The −100 °C test exhibits a dimple morphology and demonstrates the highest ultimate tensile strength of 1231 MPa, along with an excellent elongation of 44%. At high tensile temperatures (650 °C, 750 °C, and 850 °C), the dislocation cutting mechanism and dynamic recrystallization increase the plasticity. However, the presence of a large number of cracks near the spherical primary L12 phase significantly reduces the ductility and strength. The results show that the hypereutectic Al1.1CoCrFeNi2.1 exhibits superior plasticity and strength properties at low temperatures. The findings of the article provide a new approach to enhancing the comprehensive mechanical properties of hypereutectic alloys. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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Review

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21 pages, 9015 KiB  
Review
Thermal Sprayed Protective Coatings for Bipolar Plates of Hydrogen Fuel Cells and Water Electrolysis Cells
by Tao Liu, Youkun Tao, Yanli Wang, Mingfeng Wu, Jin Zhang, Yang Yu, Xingfu Wang and Jing Shao
Coatings 2024, 14(3), 307; https://doi.org/10.3390/coatings14030307 - 1 Mar 2024
Cited by 2 | Viewed by 2983
Abstract
As one core component in hydrogen fuel cells and water electrolysis cells, bipolar plates (BPs) perform multiple important functions, such as separating the fuel and oxidant flow, providing mechanical support, conducting electricity and heat, connecting the cell units into a stack, etc. On [...] Read more.
As one core component in hydrogen fuel cells and water electrolysis cells, bipolar plates (BPs) perform multiple important functions, such as separating the fuel and oxidant flow, providing mechanical support, conducting electricity and heat, connecting the cell units into a stack, etc. On the path toward commercialization, the manufacturing costs of bipolar plates have to be substantially reduced by adopting low-cost and easy-to-process metallic materials (e.g., stainless steel, aluminum or copper). However, these materials are susceptible to electrochemical corrosion under harsh operating conditions, resulting in long-term performance degradation. By means of advanced thermal spraying technologies, protective coatings can be prepared on bipolar plates so as to inhibit oxidation and corrosion. This paper reviews several typical thermal spraying technologies, including atmospheric plasma spraying (APS), vacuum plasma spraying (VPS) and high-velocity oxygen fuel (HVOF) spraying for preparing coatings of bipolar plates, particularly emphasizing the effect of spraying processes on coating effectiveness. The performance of coatings relies not only on the materials as selected or designed but also on the composition and microstructure practically obtained in the spraying process. The temperature and velocity of in-flight particles have a significant impact on coating quality; therefore, precise control over these factors is demanded. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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Other

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14 pages, 4329 KiB  
Essay
Simulation and Experimental Investigation of Multi-Step Shot Peening for Surface Crack Repair in Aluminum Alloys
by Jiahao Zhu, Kai Liao and Jun Hu
Coatings 2023, 13(11), 1969; https://doi.org/10.3390/coatings13111969 - 20 Nov 2023
Viewed by 1093
Abstract
This study explores the impact of shot peening residual compressive stress on repairing surface cracks in the 7075-T651 aluminum alloy. Two models were developed for crack repair via shot peening and fatigue test finite element modeling. A multi-step numerical simulation introduced shot peening-induced [...] Read more.
This study explores the impact of shot peening residual compressive stress on repairing surface cracks in the 7075-T651 aluminum alloy. Two models were developed for crack repair via shot peening and fatigue test finite element modeling. A multi-step numerical simulation introduced shot peening-induced residual stress into the fatigue test model, and subsequent simulations analyzed the crack repair mechanism. The research results indicate that increasing pressure and projectile size improve repair effectiveness, but higher pressure causes material damage, and larger projectiles decrease fatigue life. Crack repair effectiveness decreased with higher loading levels, more significantly at higher loads. Experimental and simulation results matched well, validating the simulation model for shot peen repair processes and offering optimization possibilities. Full article
(This article belongs to the Special Issue Advances in Protective Coatings: Materials, Fabrication, Corrosion and Applications)
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