化学氧化法合成氧化石墨及其陶瓷复合材料

基于Hummer化学氧化法,以不同纯度的石墨为原料,在氧化阶段改变氧化剂(KMnO4)的添加速率,研究了氧化石墨的制备及其结构形成。结果表明:石墨原料纯度及氧化剂添加速率对氧化石墨结构有重要影响。以高纯度石墨为原料,在合适的添加速率下制备出的氧化石墨具有高的结晶性和纯度。扫描电镜观察制得的氧化石墨呈片层结构,厚约50nm。X射线分析显示对称氧化石墨(002)强衍射峰,无残留石墨峰和其它杂质峰。红外光谱分析氧化石墨含—OH,C=O,C—O等含氧基团。Ar气氛下对氧化石墨进行热解,产物为石墨烯。将制得的氧化石墨引入聚硅氧烷中,经交联和热解制出具有层状复合结构呈一定取向分布的石墨烯和硅氧碳陶瓷复合材料。

SYNTHESIS OF GRAPHITE OXIDES BY CHEMICAL OXIDATION METHOD AND CERAMIC COMPOSITES

Graphite oxides （GO） are synthesized by the chemical oxidation method using different purity graphite as raw materials and the various adding rate of strong oxidizing agents （KMnO4） at the stage of oxidation in the fabrication process. High purity and highly crystallized GO can be obtained through using high purity graphite with appropriate addition rate of KMnO4,and the as-prepared GO was characterized by X-ray diffraction analysis. Moreover,the permanganate-addition rate changes the inter-layer space of GO and the amount of oxygen-containing groups in the GO products. Graphene can be formed by thermal reduction of GO. Finally,a graphene and ceramic composite was fabricated by addition of GO into polysiloxane precursors followed by thermal cross linking and pyrolysis. The GO pellets form layered assembly in the precursors that transform into graphene after pyrolysis. This gives rise to a unique layered composite with staked graphene sheets homogeneously distributed in silicon oxycarbide ceramics.