There has been many controversies about the effects of additives in sintering of SiC. But no prior systematic work has been reported about the difference between the effects of B and $B_4C$ as additives.
The sintering behavior of SiC and its strength are studied and the optimum concentrations of additives and optimum conditions for sintering of SiC are determined. The effects of B and $B_4C$ are studied with some experiments such as, surface area measurement, diffusion phenomena and observations of dihedral angle and microstructure developed during firing.
The results show that B and $B_4C$ have same effects on reactive sintering of SiC except the easiness of transport for uniform distribution. The strength of sintered SiC without exaggerated grain growth is limited by extrinsic flaws and is nearly independent of temperature up to 1400℃.
