喷涂参数对内送粉等离子喷枪制备YSZ涂层微观结构和性能的影响

为了进一步提高大气等离子喷涂YSZ热障涂层性能并降低其成产成本,开发了内送粉等离子喷枪.本文采用Spray Watch 2i在线监测系统测量了YSZ粉末粒子温度和飞行速度,采用实验室手段表征了涂层的微观结构、结合强度、弯曲性能和抗热震性能.研究结果表明,内送粉方式下喷涂距离对涂层微观结构和性能的影响规律与外送粉相似,而电流和主气流量表现出了独特的作用效果：随电流的增大,涂层综合性能先增加后降低,高电流下制备的涂层结合强度较低;在30～50 L/min范围内,增大主气流量可显著提高涂层结合强度.与外送粉最优参数制备YSZ涂层相比,内送粉时的功率消耗大幅降低,但粒子熔化效果明显增强,相同送粉速率下粉末沉积效率略有增加,涂层热循环寿命有所提高.

Effect of Spray Parameters on Microstructure and Properties of YSZ Coatings Sprayed by Plasma Spray Torch in Internal Feedstock Mode

Employing internal feedstock mode is an effective method to improve atmospheric plasma sprayed ceramic coatings quality and obtain high powder deposition efficiency. For this purpose, a plasma spray torch in internal feedstock mode was researched and developed. In this paper, a parametric study was conducted to determine the effect of internal feedstock plasma spray process parameters, including arc power, spray distance, and primary gas flow rate, on the final microstructure and properties of coatings sprayed from nano-agglomerated yttia-stabilized zirconia powders. The results show that in internal feedstock mode, effect of spray distance on coating performance is similar to external feedstock mode, but arc power and primary gas flow rate have a novel influence on coating microstructure and properties. With the increase of arc power, coating integrity performance increases firstly and then decreases. Surprisingly, coating adhesion strength is very low at a high power level.With the increment of primary gas flow rate, coating adhesion strength increases gradually, because high gas flow can improve the rigidity of plasma jet, reducing the bad effect of cold carrier gas on plasma jet. Compared with YSZ coatings sprayed by external feedstock mode, internal feedstock mode sprayed coatings, in which particles were melted well with low power consumption, have better performance and higher powder deposition efficiency, which is about 56.12% at the powder feeding rate of 24.71 g.