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我们之前对热喷涂金属粒子的扁平化转变行为进行了系统研究,并提出了形成机制假设:由于超快速冷却而优先在熔滴底部形成的冷却晶体结构决定着圆饼状熔滴的形成。为了验证这一机制是否适用其他材料,选取了几种具有不同热性能的陶瓷材料来进行对比。采用等离子喷涂技术分别将Al_2O_3、Y_2O_3和YSZ喷涂到AISI304不锈钢基体上,对圆饼状熔滴百分比随基体温度变化规律进行了研究,并对熔滴的横截面形貌也进行了观察。结果表明,在Al_2O_3和Y_2O_3熔滴底部均存在独特的非晶和冷晶结构,说明这些材料中圆饼状熔滴形成机制与金属中的相似。另一方面,在YSZ熔滴中却只有柱状晶结构,故圆饼状颗粒的形成机制假设只是适用于部分材料。
We have systematically studied the flat transition behavior of the thermal sprayed metal particles and proposed the formation mechanism hypothesis that the cooling crystal structure preferentially formed at the bottom of the droplet determines the formation of a round droplet due to the ultra-rapid cooling. In order to verify whether other mechanisms are suitable for this mechanism, several ceramic materials with different thermal properties were selected for comparison. Al 2 O 3, Y 2 O 3 and YSZ were sprayed onto the AISI 304 stainless steel substrate by plasma spray technique. The variation of percentage of drop shape of the pie cake with the substrate temperature was also studied. The cross-sectional morphology of the droplet was also observed. The results show that there are unique amorphous and cold-crystalline structures at the bottom of Al 2 O 3 and Y 2 O 3 droplet, which indicates that the formation mechanism of the round cake droplet in these materials is similar to that of metal. On the other hand, there is only a columnar crystal structure in the YSZ droplet, so the formation mechanism of the round cake particles is only applicable to some materials.