喷雾干燥法制备纳米结构热喷涂喂料的非均匀结构形成机理

The Formation Mechanism of Non–uniform Structure for the Thermal Spraying Nanostructured Feedstock Prepared by Spray–drying Method

利用α–Al2O3和金红石相TiO2两种纳米粉末,采用喷雾干燥方法制备了纳米结构Al2O3–13%TiO2喂料。随着浆料中固相物含量的减少,喂料的尺寸减小。中空的球形颗粒内部呈现非均匀结构,一侧变薄甚至出现空洞。喷雾造粒过程浆料液滴表面蒸发速度不同,导致固相物同时向表面和前部迁移,是形成这种特殊结构的主要原因。

The nanostructured Al2O3–13 %TiO2 feedstock was prepared by spray–drying method using two kinds of nano–powder of α–Al2O3 and rutile–TiO2 as raw material.The feedstock dimension became smaller with the solid phase material in the slurry decreasing.Interior of the hollow spherical grains present the non–uniform structure,and the side became thinning or even empty.During the process of spray pelletization,the difference of slurry droplet surface evaporation rate made the solid phase simultaneously transfer to...