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 July 2024 | Viewed by 5003

Special Issue Editors


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Guest Editor
AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
Interests: thermal barrier coatings; electron beam physical vapor deposition

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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

Published Papers (6 papers)

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Research

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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
Viewed by 861
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
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0 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 - 09 Dec 2023
Viewed by 679
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
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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 556
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
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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 707
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
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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 - 01 Mar 2024
Viewed by 1143
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
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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 687
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
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