Mo在Sialon陶瓷中的相反应及热力学分析

Phase Reaction and Thermodynamic Analysis of Mo in Sialon Ceramics

采用常压烧结和气压烧结方法制备了Mo-Sialon陶瓷,研究了烧结过程的物相组成及微观结构演变规律,并对其烧结机理进行了热力学分析。结果表明:常压烧结下,在1 600℃烧结,钼主要以Mo_5Si_3形式存在,在1 750℃烧结,Mo_5Si_3大部分分解形成大量的MoSi_2,当温度升高至1 850℃时,钼全部以MoSi_2形式存在;若采用氮气气压烧结至1 850℃,钼主要以Mo_5Si_3形式存在;微观结构表明,在陶瓷材料基体中,长柱状晶粒和等轴状晶粒交错分布,硅钼化合物以等轴状晶粒形貌均匀分布于Sialon晶粒交界处;实验结果与热力学及相图分析结果一致。

Mo-Sialon ceramics were prepared by using atmospheric sintering and pressure sintering methods. The phase composition and microstructure evolution during sintering process were studied. And the sintering mechanism was studied by thermodynamic analysis. The results show that when sintered at 1 600 ℃, Mo mainly exists in the form of Mo5Si3. When sintered at 1 750 ℃, most Mo5Si3 is decomposed into MoSi2. When sintering temperature rises to 1 850 ℃, all Mo exists in the form of MoSi2. Under the condition of 1 850 ℃ and N2 pressure, Mo mainly exists in the form of Mo5Si3. Mierostructure analysis results show that in ceramic substrate, long columnar grains and equiaxed grains distribute alternately. Silicon molybdenum compounds with equiaxed grain morphology are distributed evenly at the junction of Sialon grain boundaries. The experimental results are consistent with the thermodynamics and phase diagram.