Effect of Al2O3-SiO2 film at the interface on the microstructure formation and oxidation resistance of MoSi2 coating on Nb-Si based alloy via slurry sintering method

Hao Jiang, Yanqiang Qiao, Xiping Guo, Xiao Ma, Xi Nan

科研成果: 期刊稿件文章同行评审

2 引用 (Scopus)

摘要

This study aims to improve the coating density by introducing Al2O3-SiO2 film as a diffusion barrier (DB) at the interface during the sintering process. The influence of the thickness of DB at the interface on the density, phase constituent and interface structure of the coating was studied. The results showed that the Al2O3-SiO2 film can effectively reduce the inward diffusion of Si, facilitating the densification of MoSi2 coating. Increasing the thickness of the DB correspondingly improves the diffusion blocking effect. Compared with the MoSi2 coating without DB, the area porosity of the coating with a 5 μm thick DB decreased from 26.8 % to 15.8 %. The oxide DB is discontinuously distributed at the interface. However, although the density of the coatings was markedly increased, severe cracking occurred when the diffusion barrier was excessively thick. The microstructure of coating without DB and coatings with 3 and 5 μm thick DB is generally similar, with the inter-diffusion zone (IDZ) consisting of Mo5Si3, Nb4Fe3Si5, and (Nb,X)5Si3 three layers. In contrast, the IDZ of coatings with 10 and 15 μm thick DB is comprised of a single (Nb,X)5Si3 layer. In comparison to the MoSi₂ coating without DB, the coating with a 5 μm thick DB exhibited a markedly enhanced oxidation resistance. The pores in the coating can be quickly filled by the as-formed SiO2. The weight gain of coating with a 5 μm thick DB is about 9.4 mg/cm² after oxidation at 1250 °C for 100 h, and about 10.1 mg/cm² after oxidation at 1350 °C for 50 h.

源语言英语
文章编号177720
期刊Journal of Alloys and Compounds
1010
DOI
出版状态已出版 - 5 1月 2025

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