Studies on Sintering Atmosphere for Nano Crystalline Particles of alpha-Silicon Carbide Doped with Boron

摘要

Nano particles of silicon carbide doped with both boron and carbon were sintered at between 2000-2100 deg C in different atmospheres, viz. vacuum, argon and nitrogen atmosphere for different sintering times. The effect of atmosphere on the sintering of nano-crystalline a-silicon carbide has been thoroughly studied with dopants. It has been found that it has a very critical influence in the case of nano crystalline silicon carbide sintering. This study shows that for both the dopants, effective sintering of silicon carbide to full densification can be achieved in the above temperature range under vacuum atmosphere (3 mbar) with a sintering time of 15 min, whereas nitrogen atmosphere has a retarding effect on the sintering of nano-crystalline a-silicon carbide. The results are described in terms of a diffusion model proposed in an earlier investigation. A decrease in the diffusion coefficients of boron and carbon and thereby a decrease in densification was observed. This might be due to the incorporation of nitrogen in the lattice vacant sites. A highertemperature increases the diffusion coefficients and helped in achieving full densification in the nitrogen atmosphere.