炉内成球法制备SiC空心陶瓷微球

Preparation of Hollow SiC Ceramic Microspheres With Drop-tower Technique

摘要: 采用干凝胶法，以聚碳硅烷（PCS）为原料，通过炉内成球技术制备了SiC空心陶瓷微球。并利用TG、IR、SEM、XRD等方法对陶瓷微球进行了成键结构、表面形貌等分析，讨论了有机聚合物的陶瓷化过程机理。结果表明，干凝胶成球技术能利用经纯化处理的聚碳硅烷在500~600 ℃下得到SiC空心陶瓷微球，采用乙醇作为发泡剂可使PCS凝胶粒子得到良好发泡效果，提高载气中氦气含量至50%~80%可提高干凝胶粒子在吸热阶段的升温速率，微球经辐照后在850 ℃下碳化生成以β-SiC为主要相结构的球壳，球壳具有较好的表面平整度。

Abstract: SiC ceramic microspheres were fabricated by drop-tower technique at low temperature using polycarbosilane (PCS) as raw material. The as-prepared microspheres were characterized by TG, IR, SEM and XRD. The reaction mechanism of organic polymer and the effects of process parameters (composition of furnace atmosphere and temperature) were investigated. The results show that ethanol as a blowing agent has a high blowing efficiency, and the content of helium gas in the furnace atmosphere ranging rising to 50%-80% can increase the heating-up rate of gel particles in heat-absorbing stage. The high sphericity morphology is obtained at 500-600 ℃. Moreover, the SEM spectra indicate that irradiation can increase the surface finish quality and evenness of hollow SiC ceramic microspheres.