等离子弧处理纳米氧化锆粉末结构演变研究

本文采用大气等离子喷涂—纯净水捕获技术,研究了纳米氧化锆(YSZ)粉末在等离子焰流熔化过程中颗粒状态演变历程。研究表明,纳米氧化锆团聚粉在等离子喷涂过程中因纳米晶的长大和熔化而呈现出明显的致密化收缩趋势,同时由于粉末颗粒在等离子焰流区停留时间和受热程度不同,通过熔融急冷与内部气体膨胀的双重作用,粉末外观分别经历了"微裂纹型"、"熔融针状气孔型"以及"密实球壳型"等不同阶段形貌。粉末内部结构的演变则进一步揭示了在高温高速等离子焰流中纳米团聚颗粒因内外巨大温差和不同熔融状态下的热量传导效果,产生了不同热应力程度下的径向内外收缩效应,从而表现出粉末内部弥散"微裂纹孔隙"、"均匀球形孔隙"以及空心结构等阶段性结构变化。上述演变过程可为纳米氧化锆涂层的制备应用和性能改进提供必要的数据参考。

The Study of Structural Evolution of Nano-Zirconia Particle in Plasma Spraying

In this paper, Nanostructured yttria-stabilized zirconia （YSZ） particles were collected in the water and the structural evolution of nano-zirconia particle in plasma spraying were studied. The results showed that, trend of shrinkage of nano-zirconia reunion powder were appeared significantly because of nano-zirconia particle grew up and melted. The residence time and degree of heat subjected of the powder in plasma flame flow zone was different, it was affected by the role of ＂melt-quenched＂ and gas expansion, the appearance of powder experienced the different stages of morphology including the type of＂ microcrack＂, ＂melt acicular the stomata ＂ and ＂dense spherical shell ＂. The evolution of the internal structure of the powder revealed that nano-zirconia particle was radial shrinkage due to the huge temperature difference between inside and outside of the powder and the effect of heat conduction in Plasma Spraying. The morphology inside of the powder experienced the different stages of morphology including ＂micro cracks pore＂, ＂uniform spherical pores ＂, and ＂hollow structure＂. The evolution process can provide the necessary data referencefor for the application of nano-zirconia coating and improvements of the performance.