Role of Ambient Pressure on Splat Formation and Coating Adhesion Strength during Thermal Spraying Process

Abstract

Cu powders were thermally sprayed onto AISI304 substrate surface under various ambient pressures, the splat shape on the substrate had a transitional changing tendency from a splash splat to a disk one with decreasing the ambient pressure. Millimeter-sized molten Cu droplets were deposited on AISI304 substrate surface by free-falling experiment, the heat transfer from splat to substrate was enhanced with the decrease of ambient pressure, which can be attributed to the good contact at splat-substrate interface. The shear adhesion strength of coating fabricated on blasted AISI304 substrate corresponded quite well to that of the splat shape. Therefore, control of thermal spray process through observation on individual splat behavior is meaningful.