喷涂工艺参数对硅灰石涂层结构的影响

Effect of spray parameters on microstructure of plasma sprayed wollastonite coatings

采用等离子喷涂方法,在不同喷涂距离、主气流量和喷涂功率下制备硅灰石涂层.使用扫描电镜观察了涂层的微观形貌,研究了喷涂工艺参数对涂层结构的影响.结果表明,在较大主气流量下,随着喷涂距离增加,涂层粒子扁平化程度降低,涂层内孔隙逐渐增多;在较小主气流量下,涂层粒子扁平化程度随喷涂距离增加呈现先增加后减小的趋势.主气流量增加,涂层致密,粒子扁平充分.喷涂功率增加,粒子熔化好,涂层致密;但随喷涂功率进一步增加,涂层中出现较多的圆形孔隙.喷涂工艺参数对涂层结构的影响主要通过影响熔融粒子的温度和速度所致.

Wollastonite coating was prepared by plasma spraying at different spraying distances, primary gas flow rates and plasma power. The microstructure of the coating lager was examined by scanning electron microscope (SEM). The results show that the three spraying parameters affect the microstructure of wollastonite coatings greatly. Flatten degree of molten powder decreased and the number of pores increased with the increment of spraying distance at larger flow rate of primary gas. However, flatten degree of molten powder firstly increased and then decreased with the spraying distance at the lower flow rate of primary gas. The microstructure of coatings is denser with larger gas flow rate. Flatten degree increased with plasma power up to 36 kW. Further increase of plasma power results in more round pores appearing in coatings. Effect of spray parameters on the microstructure of wollastonite coatings mainly resulted from the influence on velocity and temperature of the molten droplets.