Effect of Processing Parameters on Microstructure and Mechanical Properties of Zirconia/Alumina Composite Coatings by Gas Tunnel Type Plasma Spraying

Plasma power and substrate traverse number during deposition play an important role in the plasma spray coating process and affect the final properties of the coatings. Zirconia, alumina, zirconia/alumina composite coatings on stainless substrate were prepared by a gas tunnel type plasma spray system to investigate the effects of these parameters on the coating. The results indicated that those parameters such as alumina mixing ratio, plasma power and traverse number over the substrate did affect the hardness, porosity and wear resistance of composite coatings. The Vickers hardness of the coating becomes large with an increase in alumina mixing ratio, the porosity decreased from 33.7 to 7.65%. The lowest porosity and the highest hardness of composite coatings were obtained at a substrate traverse number, N=20 times with a spraying distance, L=40 mm. The adhesive strength of the composite coating decreased with an increase in alumina mixing ratio and at the same time, wear weight of the coating also decreased