泡沫碳化硅陶瓷的导电性能

Electrical properties of SiC foam ceramics

采用高分子热解和反应烧结方法制备出泡沫碳化硅陶瓷,研究了泡沫碳化硅陶瓷的体积分数变化和钛的掺杂对泡沫碳化硅陶瓷骨架导电性能的影响．结果表明：随着泡沫碳化硅陶瓷的体积分数提高,泡沫碳化硅陶瓷的电阻率降低,这是泡沫碳化硅陶瓷筋中部碳化硅的面积增加所引起的；掺杂的钛转变成 TiSi_2导电相改善了泡沫碳化硅陶瓷的导电性能．TiSi_2呈现离散和团聚两种形态分布,以不规则的形状位于碳化硅晶界之间,在碳化硅中作为施主杂质．泡沫碳化硅陶瓷表现出的正或负温度系数取决与掺杂的钛量的多少．

The SiC foam ceramics was prepared by macromolecule pyrogenation combined with reaction bonging methods. The effects of Ti doping and volume fraction of SiC foam ceramics on the electric characteristics of SiC foam ceramics were investigated. The results showed that the resistivity of SiC foam ceramics decreased with the increasing of volume fraction of SiC foam ceramics. It was due to the increase of SiC areas in the struts of SiC foam ceramic. The changing of doped Ti to TiSi2 improved the electric conductivity of SiC foam ceramics, TiSi2 distributed in the grain boundary of SiC in form of reunite or scatter. The electric property （NTC or PNC effect） of the SiC foam ceramics depended on the amount of Ti doping.