送粉位置对等离子喷涂YSZ粒子熔化状态的影响

研究了等离子喷枪采用3个送粉位置时距离喷嘴90mm处YSZ粒子的熔化状态(包括粒子温度及速度、粒子粒度分布、粒子撞击基体后的扁平形貌),其中送粉位置1和2为枪外送粉,送粉孔轴线距离喷嘴端面分别为9mm和3.5mm,送粉位置3为枪内送粉,送粉孔轴线距离喷嘴端面5mm。结果表明,送粉位置沿等离子射流逆流方向移动时(分别对应送粉位置1、2和3),粒子熔化效果明显增强,粒子扁平化程度提高;涂层中未熔颗粒和孔隙百分比由33.25%减小至10.13%,涂层结合强度由16.25MPa增加至37.25MPa,涂层表面剥落20%时经历的热震次数由35次增加至130次;采用送粉位置3时,喷涂功率33.60kW,低于其他送粉位置的电弧功率(46.75kW),实现了低功率制备高性能YSZ涂层。

Effect of Powder Injection Positions on the Melting State of Plasma Sprayed YSZ Particles

This paper analyzed different melting states of yttriastabilized(YSZ) zirconia particles sprayed at 3 different powder injection positions. Powder injecting position 1 and 2 were located outside the nozzle. However, position 3 was located inside the nozzle. Particles states including particles average temperature, fly velocity, size distribution and splats patterns were measured at the distance of 90 mm from the nozzle exit. The results show that when the powder injection position removed along the downstream of a plasma jet (from position 1 to position 3), the particle heating effect was enhanced. The particle flattening degree increased and deposited coating became denser with fewer amounts of unmelted particles and pores. The average adhesion strength of YSZ coatings increased from 16.25 MPa to 37.25 MPa. Bend performance and thermal shock resistance of the coatings also increased. At powder injection position 3, high performance coatings were obtained with less power consumption of 33.60 kW in comparison with other positions of 46.75 kW.