Abstract:In order to improve the surface quality of continuous annealing furnace roller, CoCrAlTaY-30%Al2O3 coating was prepared by air plasma spraying, and the effect of spraying process parameters on microstructure,phase composition and mechanical properties of coating were researched. The results showed that there were two typical structures of Al2O3 and alloy phase existing in the coating, but the dispersion was uniform. The coating was mainly composed of Co alloy, α-Al2O3 and γ-Al2O3 phases, and the spraying power, spraying distance and main gas flow had no significant influence on the microstructure and phase composition in the coating. With the increase of spraying power, the melting effect of powder particles becomes better and the porosity decreases. At 40 kW spraying power, the hardness of coating is the highest, and the bonding strength reaches 68 MPa. Within the range of 80~140mm spraying distance, most of the powder has melted, and a small number of unmelted particles exist. However, the porosity of the coating gradually increases, and the maximum bonding strength of the coating is 78.6MPa at the spraying distance of 120 mm. When the main gas flow is 40 L/min, the coating has the lowest porosity and the highest bonding strength. The optimal process parameter for plasma-sprayed CoCrAlTaY-Al2O3 coating was 40 kW spraying power, 120 mm spraying distance and 40 L/min main gas flow. In that case, the porosity of the coating is 3.689%, and HV0.3 664.9, adhesive strength 78.6 MPa.