Synthesis of silicon carbide whiskers using reactive graphite as template

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• 作者：Yawei Li ; Qinghu Wang ; Haibing Fan ; Shaobai Sang ; Yuanbing Li ; Lei Zhao
• 关键词：Silicon carbide ; Graphite flake ; Expanded graphite
• 刊名：Ceramics International
• 出版年：January, 2014
• 年：2014
• 卷：40
• 期：1_part_PB
• 页码：1481-1488
• 全文大小：2294 K

文摘

Silicon carbide whiskers have been synthesized by using reactive graphite as a template. Natural graphite flake was firstly activated using chemical oxidation and thermal oxidation methods. After that, the reactive graphite sources were mixed with silicon powder and heated in the coke bed at 1200 and 1400 掳C. The structural evolution of graphite and morphologies of SiC whiskers were studied with the aids of XRD, SEM, TEM and EDS techniques. The results showed that natural graphite flake can be activated into reactive graphite such as oxidized graphite and expanded graphite with much more defects using thermal and chemical oxidation methods. The expanded graphite with a great deal of defects has higher reactivity than natural graphite flake and oxidized graphite and accelerates the formation of long and thick SiC whiskers. It is proposed that the vapor-solid mechanism is predominant for the growth of 尾-SiC whiskers in this system. During heating-up, Si or SiO vapors meet with the activated carbon atoms on graphite substrate to form SiC nucleus. Then these vapors continually deposit on the SiC nucleus following the SiC whiskers which grow along the 銆?11銆?direction.