喷涂工艺对超音速等离子喷涂BaTiO_3涂层性能的影响

Effect of spraying process on performance of supersonic plasma spraying BaTiO_3 coating

等离子喷涂陶瓷涂层与基体间的结合强度往往较小,限制了其应用。本文采用4因素3水平正交试验,通过在线监测BaTiO3喷涂粒子的温度及飞行速度,对喷涂电流,喷涂电压,喷涂距离和主气流量等4个参数进行优化设计,结果表明:喷涂距离对BaTiO3涂层的结合强度影响较大,其次为喷涂电流,主气流量及喷涂电压。喷涂电压和主气流量对喷涂粒子飞行速度的影响较大。利用Spray Watch-2i对不同喷涂距离的粒子特性进行分析,进一步验证了喷涂距离是影响涂层最终性能的关键因素。优化的工艺参数为喷涂距离100 mm、喷涂电流450A、氩气流量3.2 m3/h、电压140 V;采用该优化工艺,涂层的结合强度为57 MPa,显微硬度为747.13HV0.1,孔隙率为0.3%,纳米压痕仪测得的涂层的表面硬度为12.21 GPa,弹性模量为189.25 GPa,具有较好的力学性能。

The low bonding strength between the plasma sprayed ceramic coating and the substrate often limits its application. In the present paper, four parameters including spray current, spray voltage, spraying distance, and main gas flow were optimized by online monitoring of the temperature and flight speed of the BaTiO3 spray particles, based on the four factors and three levels orthogonal tests. The results show that the effect of spraying distance on the bonding strength of the BaTiO3 coating is the greatest, followed by spraying current, main gas flow, and spray voltage, respectively. The spray voltage and primary gas flow rate have great impact on the spraying velocity of spray particles. Spray Watch-2i was used to analyze the particle characteristics under different spraying distances, to further validate that spraying distance is a key factor affecting the final properties of the spraying coating. The optimized process parameters are that the spray distance is 100 mm, the spray current is 450 A, the argon flows is 3.2 m3/h, and the voltage is 140 V. By using the optimized process, the bonding strength of the BaTiO3 coating is 57 MPa;the microhardness is 747.13HV0.1;the porosity is 0.3%. The nanoindentor was used to measure the mechanical properties. The surface hardness and elastic modulus of the coating are 12.21 GPa and 189.25 GPa, respectively, showing good mechanical properties.