喷涂工艺参数对等离子喷涂CoCrAlTaY-Al2O3涂层的微观组织结构和力学性能的影响

Influence of Spraying Process Parameters on Microstructure and Mechanical Properties of Plasma-sprayed CoCrAlTaY-Al2O3 Coating

为提高连续退火炉高温炉辊的表面质量,采用大气等离子喷涂技术制备了CoCrAlTaY-30%Al2O3涂层,研究了喷涂工艺参数对涂层微观组织结构、相组成和力学性能的影响。结果表明:等离子喷涂CoCrAlTaY-Al2O3涂层中两种典型组织Al2O3相和合金相交互存在并分散较均匀,涂层主要由Co合金、α-Al2O3、γ-Al2O3物相组成;喷涂功率、喷涂距离和主气流量均对涂层的微观组织和物相无明显影响;随着喷涂功率的提高,粉末粒子的熔化效果变好、孔隙率降低,在40 kW喷涂功率下,涂层的硬度最高,此时结合强度达到68 MPa;在80~140 mm喷涂距离范围内,粉末大部分已熔化,有少量的未熔颗粒存在,在喷涂距离为120 mm时涂层表面光滑致密,孔隙率较低,结合强度最大为78.6 MPa;主气流量为40L/min时,涂层的孔隙率最小而结合强度最大。等离子喷涂CoCrAlTaY-Al2O3涂层的最优工艺参数为喷涂功率40 kW、喷涂距离120 mm、主气流量40 L/min,得到的涂层孔隙率为3.689%、硬度为HV0.3664.9、拉伸强度78.6 MPa。

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 andγ-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 78.6 MPa 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 HV0.3664.9,adhesive strength 78.6 MPa.