Formation mechanism and oxidation performance for a novel Mo(Si,Al)2 coating prepared using a modified pack cementation strategy

IF 5.3 2区材料科学 Q1 MATERIALS SCIENCE, COATINGS & FILMS

Surface & Coatings Technology Pub Date : 2024-11-19 DOI:10.1016/j.surfcoat.2024.131574

Chong Zhang, Jinchao Yang, Rui Lin, Chao Shen, Lian Zuo, Zhiyu Hu, Chuming He

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引用次数: 0

Abstract

Using a modified Si-Al deposition strategy in the process of halide-activated pack cementation, conventional and novel Mo(Si,Al)₂ coatings are fabricated on molybdenum substrate to assess their distinct formation mechanism and oxidation performance. The results show that the conventional coatings are composed of an inner layer containing pure C11b MoSi₂ and an outer layer containing C11b MoSi₂ with a little Al. By contrast, the new coating is composed of pure C22 Al₈Mo₃ as the inner layer and C40 Mo(Si,Al)₂ as the outer layer (unexpectedly low Al percentage of 13 at.%). Notably, the two kinds of coatings have different microstructures and formation characteristics. The former's synthesis pathway includes the sequential formation of C22 Al₈Mo₃, C40 Mo(Si,Al)₂, and C11b MoSi₂, accompanied by a reduction in the proportion of solidified Al in Mo(Si,Al)₂. The latter's synthesis path includes the transformation from C11b MoSi₂ to C40 Mo(Si,Al)₂, and the Al content is always maintained at the highest level with the coating growth. Meanwhile, the phase transition between Al₈Mo₃ and Mo(Si,Al)₂ is an irreversible process and neither coating forms the C54 structure of Mo(Si,Al)₂ due to the low temperature. Besides, the different oxidation mechanisms are elucidated on basic of the two deposition procedures and corresponding to oxidation performance. Hence, the newly developed Mo(Si,Al)₂ coating of first silicon and then aluminum in the process of pack-cementation can be effectively used to fabricate a protective α-Al₂O₃ barrier layer at a temperature of 1300 °C.

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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.