Mo-alloyed stainless steel coating with improved cavitation erosion resistance by plasma spraying a specially designed core-shell-structured powder

Abstract

Plasma spray coatings are widely used to protect materials from cavitation erosion. However, the limited interlamellar bonding and porous structure of plasma spray coatings limit the potential of utilization of the coating materials for cavitation protection. In the present study, to improve the resistance of cavitation erosion for plasma spray coatings, molybdenum (Mo)-alloyed stainless steel coating with enhanced interlamellar bonding was deposited by spraying a specially designed core-shell-structured Mo-clad-304SS powder through shrouded plasma spray. The post-spray diffusion heat treatment was then also performed to further enhance the lamellar interface bonding of the coating. Owing to the high susceptibility to cohesion of the coating, cavitation erosion test was performed on the surface of resultant coatings to evaluate the quality of the interlamellar bonding within the coating. Results show that the cavitation erosion resistance of the 304SS-17Mo alloy coating with enhanced interlamellar bonding was significantly improved by 100% compared with that of conventional 304SS coating. After diffusion heat treatment, the cavitation erosion resistance of 304SS-17Mo alloy coating was further improved to as high as that of 304SS bulk due to the newly formed hard phases.