加热工艺对纳米Al_2O_3/TiO_2团聚粉末烧结特性的影响

Effects of heating process on sintering characteristic of agglomerated Al_2O_3/TiO_2 nanocrystalline powder

通过喷雾造粒技术制备出可用于热喷涂的纳米Al2O3/TiO2团聚粉末,使用高温电炉采取三种加热工艺进行了烧结。测定了团聚体粉末的松装密度;采用X射线衍射分析了相组成,并根据Scherrer公式计算了烧结前后平均晶粒大小;通过扫描电镜观察分析了团聚体粉末的形貌。结果表明,加热工艺对纳米团聚粉末的烧结行为影响较大,常规高温烧结在实现烧结致密化的同时将导致纳米晶粒的较大生长;两步烧结法可在抑制晶粒生长的情况下,实现松装密度的大幅度提高,是一种较为先进的烧结方法。

Nanosturctured Al2O3/TiO2 agglomerated powders used for thermal spraying were prepared by spray granulation.Then,they were sintered via three kinds of heating process in high temperature electric furnace.Apparent density of them were measured.X-ray diffraction（XRD） was used to analyze phase constituent, and the mean grain size was calculated by Scherrer formula.Scanning electron microscopy（SEM） was used to examine the morphology.It is observed that the heating process has an important effect on the sintering behavior of agglomerated nanocrystalline powder.The conventional sintering practice gaining preferable density at the highest temperature are always accompanied by rapid grain growth.The two-step sintering method can increase apparent density to a great extent and suppress the grain growth,so,it is an advanced sintering method.