(1. 湖南大学 材料科学与工程学院，长沙 410082；2. 湖南人文科技学院 化学与材料科学系，娄底 417000)
摘 要: 以硅溶胶、炭黑和TiO2为原料，采用碳热还原法合成TiC-SiC复合粉末。研究反应温度和TiO2添加量对合成TiC-SiC复合粉末的物相组成和显微形貌的影响；对反应过程进行热力学分析和计算，探讨TiC-SiC复合粉末的生长机理。结果表明：TiC-SiC复合粉末适宜的合成条件为在1 600 ℃保温1 h；在反应过程中，TiC先于SiC形成，TiC的形成抑制了SiC颗粒的生长；当复合粉末中TiC的含量(质量分数)为10%左右时，SiC的合成过程由气−固(V-S)机理反应转变为气−固机理和气−气机理共同反应；复合粉末主要由球状颗粒、短棒状颗粒以及少量晶须组成；随着复合粉末中TiC含量的增加，SiC晶须的生长受到抑制，其形貌逐步由长纤维状向短棒状和颗粒状过渡。
关键字: TiC-SiC；复合粉末；碳热还原法；生长机理
TiC-SiC composite powders by carbothermal reduction
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Department of Chemistry and Materials Science,
Hunan Institute of Humanities, Science and Technology, Loudi 417000, China）
Abstract:The TiC-SiC composite powders were synthesized by carbothermal reduction using silica sol, carbon black and titanium oxide as raw materials. The effects of reaction temperature and titanium oxide content on the phase compositions and morphologies of TiC-SiC composite powders were investigated. The thermodynamic analysis and calculation were performed systematically during the reaction, and the growth mechanism of TiC-SiC composite powders was discussed. The results show that synthesizing TiC-SiC composite powders at 1 600 ℃ for 1 h is suitable. In the reaction process, TiC forms ahead SiC, and the formation of TiC inhibits the grain growth of SiC particles. When TiC content (mass fraction) is about 10%, the formation mechanism of SiC is transferred from vapor-solid mechanism to the combination of vapor-solid and vapor-vapor mechanism. The composite powders are mainly composed of spheric particles, short rod-like particles and a small amount of whiskers. With the increase of TiC content in the composite powders, the growth of SiC whiskers is inhibited and the morphology of SiC gradually transferred from long fiber to short rod-like and round-like particles.
Key words: TiC-SiC; composite powder; carbothermal reduction; growth mechanism
