Study on the oxidisation behaviour of particles during thermal spray process

Abstract

Atomised metallic particles at high-temperature are oxidised easily in thermal spray process, resulting in the generation of defects such as low purity of sprayed metal and reduction in adhesive strength of deposited coating. In this investigation, argon and compressed air were employed as atomisation gas to spray 1Cr18Ni9Ti stainless steel wire by arc spraying. The result indicated that the best atomising effect of spraying particles can be achieved when argon atomising gas was employed. Their particle size were in the range of 20–40 μm, which were about half as large as those using compressed air as atomisation gas. Oxygen content of atomising particles were as follows: 16.66% using argon atomising gas, 25.34% using compressed air and 42.48% using oxygen atomising gas. The presence of Cr diffusion in the coating deposited using argon atomising gas led to a dense interface which determined the adhesive strength of 12.5 MPa.