等离子喷涂中纳米团聚体粉末温度场数值模拟

摘要

在纳米粒子排布方式理想化假设及热物性参数换算基础上,对纳米团聚体Al2O3-13%TiO2粉末等离子喷涂过程中的温度场进行数值模拟,分析粉末直径、喷涂距离及喷嘴出口处等离子焰流温度对粉末熔化状态的影响,并通过试验研究粉末在喷涂过程中的熔化特性.结果表明,要想获得适当且比较均匀的熔化状态,粉末粒度大小范围不宜分布过宽,同时要有合适的喷涂距离以及喷嘴出口温度.在等离子喷涂过程中,粉末中温度低于1 840℃的区域纳米粒子将得到保留,温度介于1 840~2 045℃的区域TiO纳米粒子将选择性熔化,而温度高于2%A numerical simulation model for analyzing the temperauture field of the nanostructured agglomerated Al2O3-13%TiO2 powders during plasma spraying process was established based on the ideal assumption of the nanoparticles stacking structure and conversion of the feedstock thermal physical parameters.The effects of the feedstock diameter,spray distance and temperatuer of jet nozzle outlet on melting process of powders were studied.Meanwhile,experiment of plasma spraying using nanostructured agglomerated powders was carried out.The results showed that the size distribution of the powders should not be too broad and a suitable spray distance,as well as temperatue of jet nozzle exit was necessary to gain a proper and uniform molten state of the feedstock.During plasma spraying,the region less than 1 840 ℃ where nanoparticles were retained,and the region between 1 840 ℃ and 2 045 ℃ where TiO2 nanoparticles were selective melted and the region more than 2 045 ℃ where nanoparticles were fully melted.