The influence of B4C content on the pore structure of reaction-synthesized porous Ti3AlC2-TiB2 composite ceramics.

Using a mixture of TiH 2 , Al, B 4 C, and graphite powders with a molar ratio of 3+2 m/1.2/m/2-m (where m ranges from 0 to 0.25, with increments of 0.05), porous Ti 3 AlC 2 -TiB 2 composite ceramics were successfully synthesized through activated reaction sintering. The effect of B 4 C content on the phase composition, volumetric expansion, microstructure, and pore structure parameters (including pore size, porosity, and permeability) was systematically studied. When the molar ratio of B 4 C was less than 0.1, the volumetric expansion rate, average pore size, and permeability increased with the addition of B 4 C, reaching maximum values of −5.46 %, 2.23 μm, and 92.4 m3 m−2·10 kPa−1 h−1, respectively. Conversely, when the B 4 C molar ratio exceeded 0.1, the parameters related to the pore structure of the porous Ti 3 AlC 2 -TiB 2 composite ceramics decreased, with minimum values of −10.40 %, 1.46 μm, and 68 m3 m−2·10 kPa−1 h−1, respectively. In addition, the pore formation mechanism of the porous Ti 3 AlC 2 -TiB 2 composite ceramics was systematically explored. The revolution tendency of pores is related to the decomposition of TiH 2 , Kirkendall partial diffusion, diffusion between B and C, and the transition process of the final phase Ti 3 AlC 2 -TiB 2. This research work could provide a reference for the preparation of the MAX phase composite porous materials. [ABSTRACT FROM AUTHOR]