烧结气氛对合成MgAl_2O_4-Ti(C,N)复合陶瓷的影响

Effect of sintering atmosphere on synthesizing of MgAl_2O_4-Ti(C,N) composite ceramics

以金属铝粉、钛白粉和轻烧MgO细粉为原料,通过设计100%焦炭粒(简称C气氛),10%钛白粉+90%焦炭粒(简称TC气氛),以及10%硅微粉+90%焦炭粒(简称SC气氛)3种埋粉条件下的高温烧结还原性气氛,采用X射线衍射仪(XRD)、扫描电镜(SEM)和微区电子探针分析(EPMA)等手段,研究了铝热还原氮化法(1600℃3h)制备MgAl2O4-Ti(C,N)复合陶瓷在不同烧结气氛下的相组成和显微结构的变化。结果表明在不同气氛下,烧后试样的主要物相均为MgAl2O4和Ti(C,N),Ti(C,N)可能会固溶氧,气氛对Ti(C,N)的影响较大。和单纯埋炭气氛下相比,在TC气氛下有助于Ti(C,N)的生成,但晶粒细小;在SC气氛下不利于Ti(C,N)的生成,且有玻璃相存在。

Three kinds of mixed powders,i, e. coke granular,mix of 90% C ＋10% TiO2 and mix of 90% C ＋10% SiO2 were designed to form sintering reduction atmospheres at high temperature. The MgAl2O4 -Ti（C,N） composite ceramics were prepared by aluminothermic reduction nitridation method in above-mentioned three atmospheres respectively at 1600 ℃ for 3 h. The phase compositions and microstructures of MgAl204 - Ti（C,N） composite ceramics obtained were investigated by X-ray diffraction （XRD） analysis, scanning electronic microscope（SEM） and electron probe microanalysis（EPMA）. The results showed that MgAl204 and Ti（C, N） were the main phases in all specimens fired in different atmospheres,and a certain amount of oxygen element might be solid - solved in Ti （ C, N）. The atmosphere has a great influence on formation and grain size of Ti（C,N）.Under the protection of 10% TiO2 ＋90% C mixture （TC）,Ti（C,N） grain is prone to forming,but the grain size is smaller than that in C atmosphere. However,the protection of 10% SiO2 ＋90% C （SC） is unfavorable to the formation of Ti （ C, N）, and glass phase was found.