Characterization of plasma-sprayed Y2O3 coating and investigation of its visual aspect change

►The visual aspect of the plasma-sprayed Y2O3 coating was investigated. ►Overheating of Y2O3 particles in oxygen deficient plasma jet core resulted in black spot at the coating. ►Re-oxidation of reduced particle caused the whitening of coating. ►A spray coating condition proper for reducing the black spots at the coating was proposed.