基于曲面响应法的大气等离子喷涂La2Ce2O7涂层粒子特性与微观结构研究

Study on particle characteristics and microstructure of LaCeO coating by atmospheric plasma spraying based on the response surface method

根据Box-Behnken曲面响应法,利用Design Expert软件设计了大气等离子喷涂三个工艺参数(电流I、氩气流量、氢气流量)的三水平回归分析试验,通过SprayWatch-2i系统在线测试La2Ce2O7粒子飞行速度及表面温度,经统计分析得到粒子温度和速度的回归模型。采用扫描电镜表征涂层微观结构,并利用Image-Pro-Plus图像分析软件计算未熔颗粒面积分数和孔隙率。结果表明,La2Ce2O7粒子速度符合线性模型,电流、氩气流量是影响粒子速度的主要因素,而氢气流量对粒子速度的影响不显著。粒子速度随氩气流量和电流增大而线性增长。当氩气流量为120 L·min-1,电流为600 A,氢气流量为10 L·min-1时,粒子速度达到最大。粒子温度符合二次模型,氩气流量、电流以及两者之间的相互作用是影响粒子温度的最主要因素。当氩气流量为74.22 L·min-1,电流为543.96 A,氢气流量为10 L·min-1时,粒子温度达到最大。粒子熔化状态提高,涂层未熔颗粒下降。

Based on the Box-Behnken response surface method, the regression experiments for the three factors of atmospheric plasma spraying(arc current, argon flow rate, and hydrogen flow rate) were designed by Design Expert software. The velocity and temperature of La2Ce2O7 particles were monitored by SprayWatch-2i on-line diagnosis system. By the statistic analysis, the regression models of particle temperature and velocity were established. Scanning electron microscope(SEM) was used to characterize the coating microstructure. The area fraction of non-molten particles and porosity were calculated by Image-Pro-Plus software. The results show that, the La2Ce2O7 particle velocity is well fitted by the linearity regression model. The current and argon flow rate are the main parameters influencing the particle velocity. The particle velocity increases linearly with the increase of argon flow rate and current. The maximum velocity of particles can be obtained at the argon flow rate of 120 L·min-1, the current of 600 A, and the hydrogen flow rate of 10 L·min-1. However, the particle temperature conforms to the quadratic regression model, which is strongly influenced by the argon flow rate, the current, and the interaction between the current and argon flow rate. The maximum velocity of particles can be reached at the argon flow rate of 74.22 L·min-1, the current of 543.96 A, and the hydrogen flow rate of 10 L·min-1. The melting state of the particles increases and the non-molten particles decrease in the La2Ce2O7 coating.