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

Abstract Porous TiB 2 –TiC were prepared by SHS using Ti and B 4 C powder mixtures. The pores, phase constituents, microstructures and composition distribution of TiB 2 –TiC were analyzed. The influences of B 4 C 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 B 4 C particles was achieved. The results showed that the pore size decreased and combination between TiB 2 and TiC became closer with the decrease of B 4 C particle size and increase of pressure. During the reaction, B 4 C particles decomposed layer by layer, and reacted with the melted Ti to form poor boron phases of TiB and Ti 3 B 4 with needle-like shapes, which existed in quenched samples. With further reacting, TiB and Ti 3 B 4 phases gradually changed to TiB 2 with rectangle and hexagonal-plate shapes. The regular TiB 2 particles were bound together by TiC, which constructed the skeleton of pores.