Self-Bonding Effect Development for Plasma Spraying of Stainless Steel Coating Through Using Mo-Clad Stainless Steel Powders

The limited inter-lamellar bonding in the conventional thermal-sprayed 304SS coating usually leads to much lower corrosion and wear resistance than their bulk counterparts. In this study, Mo-clad stainless steel 304SS-17Mo powders prepared by mechanical alloying were used for plasma spraying to generate ultra-high-tempertature droplets to deposit the coatings with enhanced inter-lamellar bonding. The temperature at the interface between the molten splats and the stainless steel was calculated by numerical simulation, and the surface temperature of in-flight particles was measured by a commercial thermal spray particle diagnostic system. The microstructures of the coatings after etching were characterized to reveal inter-lamellar bonding. The adhesive and cohesive strengthes of the coatings were estimated by tensile and scratch tests. The measurement of the in-flight particle temperature reveals the possibility of creating a self-bonding effect, which is confirmed by microstructure examination, high adhesion over 66 MPa, and cohesion of 221 MPa.