The Plasma Spraying of Stellite 31-YSZ

The purpose of the research presented in this article was to study the effect of plasma spraying parameters on the microstructure of coatings made of Stellite 31 doped with YSZ (ZrO2 + Y2O3) ceramic particles. Spraying processes realized by atmospheric plasma spraying (APS) method were performed at 5 different process parameters - standard (I = 500 A, Ar/H2 flow: 66/8 NLPM) and changed current (300 and 700 A) and hydrogen flow (70/4 and 62/12 NLPM). A thickness of 226 μm was obtained for the coating produced with standard spraying parameters and a porosity of 8.45 vol.%. Increasing the current intensity resulted in an increase in coating thickness to more than 250 μm. The lowest porosity was obtained for the coating produced with reduced hydrogen content (5.3 vol.%). The post-coating microstructure had a characteristic lamellar structure consisting of overlapping flattened layers with some pore and oxide content. The main type of porosity observed was interlamellar porosity. The coatings consisted of two main phases; a matrix rich in cobalt, chromium, nickel and tungsten, and a ceramic phase composed of zirconium, yttrium and oxygen (YSZ).