(1. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082；2. 湖南人文科技學(xué)院 化學(xué)與材料科學(xué)系，婁底 417000)
摘 要: 以硅溶膠、炭黑和TiO2為原料，采用碳熱還原法合成TiC-SiC復(fù)合粉末。研究反應(yīng)溫度和TiO2添加量對(duì)合成TiC-SiC復(fù)合粉末的物相組成和顯微形貌的影響；對(duì)反應(yīng)過程進(jìn)行熱力學(xué)分析和計(jì)算，探討TiC-SiC復(fù)合粉末的生長機(jī)理。結(jié)果表明：TiC-SiC復(fù)合粉末適宜的合成條件為在1 600 ℃保溫1 h；在反應(yīng)過程中，TiC先于SiC形成，TiC的形成抑制了SiC顆粒的生長；當(dāng)復(fù)合粉末中TiC的含量(質(zhì)量分?jǐn)?shù))為10%左右時(shí)，SiC的合成過程由氣−固(V-S)機(jī)理反應(yīng)轉(zhuǎn)變?yōu)闅?#8722;固機(jī)理和氣−氣機(jī)理共同反應(yīng)；復(fù)合粉末主要由球狀顆粒、短棒狀顆粒以及少量晶須組成；隨著復(fù)合粉末中TiC含量的增加，SiC晶須的生長受到抑制，其形貌逐步由長纖維狀向短棒狀和顆粒狀過渡。
關(guān)鍵字: TiC-SiC；復(fù)合粉末；碳熱還原法；生長機(jī)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
