Pressureless Sintering of B4C-TiB2 Ceramic Composites

Pressureless sintering of the B4C ceramics containing 0-25 vol pct TiB2 phase was studied in the isothermal and constant heating rate regimes. The B4C-TiB2 composites were pressureless sintered to a relative density of 97.5 percent at 2100 C. It was found that the heating rate had no visible effect on the density. A new approach to the constant heating rate analysis taking into account the coarsening kinetics was developed. It was shown that the sintering process is controlled by coarsening of TiB2 particles as well as by grain boundary diffusion. The effective activation energy for sintering was estimated. The isothermal microstructural evolution at the final stage of sintering is also discussed. (Author)