Effects of B4C particle size on pore structures of porous TiB2–TiC by reaction synthesis

Porous TiB2–TiC were prepared by SHS using Ti and B4C powder mixtures. The pores, phase constituents, microstructures and composition distribution of TiB2–TiC were analyzed. The influences of B4C particle size and pressure in green compacts on pore sizes and structures of final products were also discussed. Via combustion front quenching, the reaction process between Ti and B4C particles was achieved. The results showed that the pore size decreased and combination between TiB2 and TiC became closer with the decrease of B4C particle size and increase of pressure. During the reaction, B4C particles decomposed layer by layer, and reacted with the melted Ti to form poor boron phases of TiB and Ti3B4 with needle-like shapes, which existed in quenched samples. With further reacting, TiB and Ti3B4 phases gradually changed to TiB2 with rectangle and hexagonal-plate shapes. The regular TiB2 particles were bound together by TiC, which constructed the skeleton of pores.