Preparation of electrically conducting SiC/MoSi2 composites from metal mixtures of preceramic polymer

Electrically conducting SiC/MoSi2 composites were prepared from mixtures of polymethylsilane (PMS) with Mo metal filler or MoCl5 at 5–15 wt%. Pelletized specimens were formed by uniaxially pressing the Mo mixtures into a mold at temperatures up to 400°C and 20 kpsi, while films were obtained by spin-coating the MoCl5 mixture solution on Si wafer. Both types of samples were pyrolyzed at 900–1400°C to induce the transformation into the SiC/MoSi2 composite phase. It appeared that the formation of the composite phases was initiated by reaction between excess Si, from the pyrolyzed polymer, and Mo metal or MoCl5 at over 1000°C. The electrical conductivity of pellet from the Mo mixture exhibited 10−2 S·cm−1 with the positive temperature dependence, which is about 1/50 those of commercial heating element. Morphology and microstructural development of the prepared products was characterized by TGA/DSC, SEM, XRD, and high-resolution TEM.