Microstructure and wear resistance of in situ synthesized Mo-Si-B coatings through laser cladding

Abstract

In this study, Mo-Si-B alloy coatings were in situ laser cladded on pure Mo substrate using cost-effective blended Mo, Si, and B₄C powders. Mo-Si-B coatings with minimized solidification defects exhibit a dendritic morphology that consists of coarse α-Mo dendrite cores and fine-grained interdendritic Mo₃Si-Mo₅SiB₂ eutectics, with a small amount of carbides. Compared to the pure Mo substrate, the Mo-Si-B coatings exhibit higher microhardness due to the nanohardness of interdendritic eutectics ~2.4 times greater than the α-Mo phase and showcase superior wear resistance, reducing the coefficient of friction by 72.4% and the wear rate by 39.8%. The enhanced wear resistance of Mo-Si-B coatings is attributed to the presence of hard intermetallic compounds and the formation of a self-lubricating oxidation film.