In order to obtain SiC whisker dispersed Si3N4, the reaction mechanism and the condition of SiC whiskerizing through the reaction between Si3N4+C was studied thermodynamically. In this work, Si3N4+C mixture was heat treated in 0.1MPa of Ar at temperatures from 1350 to 1750°C. SiC whiskers were obtained in the powder mixture heated above 1600°C. By using the Si3N4 powder heat treated at 1100°C for 24h in air, however, no SiC whiskers were obtained in the carbon mixed powder, indicating that the surface oxide of Si3N4 powder does not take part in the SiC whisker formation reaction. The experimentally measured nitrogen partial pressure during SiC whiskerizing was in good agreement with the equilibrium nitrogen partial pressure between Si and Si3N4, and it suggests that Si vapour is in equilibrium with Si3N4. Supersaturation for the carbothermal reduction of Si3N4 was calculated as a function of temperature. Supersaturation took value 10 to 20 during SiC whiskerizing.
