水玻璃包覆炭黑直接制备超细SiC粉体  

SYNTHESIS OF ULTRAFINE SiC POWDER FROM CARBON BLACK COATED WITH WATER GLASS

作　　者：潘顺龙[1] 杨岩峰[1] 张敬杰[1] 宋广智[1] 

机构地区：[1]中国科学院理化技术研究所

出　　处：《硅酸盐学报》2005年第8期980-985,共6页Journal of The Chinese Ceramic Society

摘　　要：以水玻璃和炭黑为原料,采用喷雾干燥技术制备水玻璃包覆炭黑前驱粉体,经碳热还原反应合成SiC。由于前驱体中原料间混合均匀,有效地提高了反应动力学,使其在1550℃下2h后就能实现完全反应,制得超细β-SiC。对于反应所得的产物,用x射线衍射、电子显微镜、Brunauer-Emmett-Teller(BET)分析等进行了表征。研究表明:该前驱体在1550℃反应5h后,得到的产物中O的质量分数为1.68%,Na残留量为61×10-6,平均晶粒尺寸为60nm,BET比表面积为10.5m2/g。碳热还原反应过程中,反应温度和时间对该体系都有重要的影响,升高温度有利于提高反应速率;延长反应时间则有利于增加体系的转化率。但是,温度过高会导致产率下降、晶粒粗化;过度延长反应时间也会导致晶粒生长。高温、短时间才有利于得到高质量的SiC产物粉体。Uhrafine SiC powder was synthesized by carbothermal reduction of the precursor of carbon black coated with water glass, which was prepared by spray drying the slurry of carbon black and water glass. This provides close contact between the reactants. The carbothermal reduction of the precursors can be completed at 1 550 ℃ for 2 h and uhrafine β - SiC is obtained. The powder produced was characterized by X-ray diffraction, Brunauer - Emmett - Teller analysis, scanning electron microscopy and transmission electron microscopy. The powder synthesized at 1 550 ℃ for 5 h was high quality with an oxygen content of 1.68% in mass fraction, sodium content of 61× 10^-6 , average crystalline size of 60 nm and specific surface area of 10.5 m^2/ g. The influence of temperature and time on the reaction was studied. Increasing the reaction temperature is favorable for enhancing the reaction rate, while prolonging the reaction time is favorable for the increase of SiC yield. But higher the temperatures lead to the decrease of yield and a longer reaction time results in the coarsing of crystalline. This shows that short reaction times with high temperatures produce high-quality SiC powder.

关 键 词：碳化硅 水玻璃 炭黑 碳热还原反心 喷雾干燥 

分 类 号：TQ174.758[化学工程—陶瓷工业]