Enhanced oxidation resistance of high-entropy alloy bond coats via low-temperature spray processing and vacuum heat treatment

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, COATINGS & FILMS

Surface & Coatings Technology Pub Date : 2025-09-05 DOI:10.1016/j.surfcoat.2025.132655

Hossein. Shahbazi , Rogerio.S. Lima , Pantcho. Stoyanov , Christian. Moreau

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Abstract

The drive for higher efficiency in thermal barrier coating (TBC) systems has highlighted the limitations of conventional MCrAlX bond coats, which are prone to oxidation and degradation. In this study, two high-entropy alloy (HEA) bond coats, FeCoNiCrAl and FeCoNiCrAlYHf, were investigated as next-generation alternatives and compared with the conventional NiCoCrAlYHfSi bond coat. Coatings were deposited by high-velocity oxy-fuel (HVOF) and high-velocity air-fuel (HVAF) spraying to examine the effect of spray temperature and process kinetics on microstructure and performance. Isothermal oxidation tests at 1150 °C for 200 h, conducted before and after vacuum heat treatment (VHT, 1050 °C for 4 h), were used to evaluate thermally grown oxide (TGO) evolution. HEA bond coats exhibited dense, continuous alumina scales, with only minor Cr₂O₃ formation observed under specific HVOF conditions, in contrast to NiCoCrAlYHfSi, which developed thicker TGOs containing spinel phases. HVAF-sprayed HEAs achieved porosity as low as 0.1–0.2 %, compared to 2.8–4.2 % for the benchmark. VHT reduced TGO growth by ~40 %, promoting stable α-Al₂O₃ formation. These findings highlight the superior oxidation resistance of HEA bond coats and the benefits of combining low-temperature spraying with VHT for advanced TBC applications.

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通过低温喷涂和真空热处理提高高熵合金结合层的抗氧化性

对热障涂层（TBC）系统更高效率的追求凸显了传统MCrAlX粘结涂层的局限性，这些涂层容易氧化和降解。在这项研究中，研究了两种高熵合金（HEA）结合涂层，FeCoNiCrAl和FeCoNiCrAlYHf，作为下一代替代品，并与传统的NiCoCrAlYHfSi结合涂层进行了比较。采用高速纯氧燃料（HVOF）和高速空气燃料（HVAF）喷涂方法沉积涂层，考察喷涂温度和工艺动力学对涂层组织和性能的影响。在真空热处理（VHT, 1050°C, 4 h）前后，在1150°C， 200 h下进行等温氧化试验，以评估热生长氧化物（TGO）的演变。HEA键结层表现出致密、连续的氧化铝鳞片，在特定的HVOF条件下只观察到少量的Cr₂O₃形成，而NiCoCrAlYHfSi则形成了更厚的含尖晶石相的tgo。hvac喷涂的HEAs的孔隙率低至0.1 - 0.2%，而基准的孔隙率为2.8 - 4.2%。VHT降低了TGO的生长~ 40%，促进了α-Al₂O₃的稳定生成。这些发现突出了HEA结合涂层优越的抗氧化性，以及低温喷涂与VHT相结合在高级TBC应用中的优势。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Surface & Coatings Technology 工程技术-材料科学：膜

CiteScore

10.00

自引率

11.10%

发文量

921

审稿时长

19 days

期刊介绍： Surface and Coatings Technology is an international archival journal publishing scientific papers on significant developments in surface and interface engineering to modify and improve the surface properties of materials for protection in demanding contact conditions or aggressive environments, or for enhanced functional performance. Contributions range from original scientific articles concerned with fundamental and applied aspects of research or direct applications of metallic, inorganic, organic and composite coatings, to invited reviews of current technology in specific areas. Papers submitted to this journal are expected to be in line with the following aspects in processes, and properties/performance: A. Processes: Physical and chemical vapour deposition techniques, thermal and plasma spraying, surface modification by directed energy techniques such as ion, electron and laser beams, thermo-chemical treatment, wet chemical and electrochemical processes such as plating, sol-gel coating, anodization, plasma electrolytic oxidation, etc., but excluding painting. B. Properties/performance: friction performance, wear resistance (e.g., abrasion, erosion, fretting, etc), corrosion and oxidation resistance, thermal protection, diffusion resistance, hydrophilicity/hydrophobicity, and properties relevant to smart materials behaviour and enhanced multifunctional performance for environmental, energy and medical applications, but excluding device aspects.