Sintering kinetics of pure and doped boron carbide

The sintering of pure and doped boron carbide was investigated over the temperature range 1898 to 23800K and at additive levels ranging from 0.75 to 10.0%. The addition of 0.75 and 3.8 wt% of AlF3, Ni, Fe, and Cu deactivated the sintering of B4C at all temperatures. In contrast, the addition of 10.0 wt% these additives resulted in enhanced shrinkage in B4C for the temperatures 1898 and 21330K. At the highest temperature, 23800K, the addition of 10.0 wt% AlF3 was the only case where enhanced shrinkage was observed. In this case, x-ray analysis showed the formation of a B12C2Al compound and the release of fluorine. These results are interpreted in terms of a grain-boundary diffusion process for pure and doped B4C