Densification of additive-free B4C-SiC composites by spark plasma sintering

The B4C-SiC composites were obtained through densification of B4C and β-SiC powders with different ratios using Spark Plasma Sintering (SPS). Thermal treatment was conducted in the 1850–2000 °C temperature range under pressure of 70 MPa. Starting powder ratio effect on sintering behavior, relative density, microstructural development, and mechanical properties of obtained composites was investigated. Results showed that only starting compounds were observed in sintered ceramics with uniformly distributed and densely compacted B4C and SiC grains. Maximal relative density (100 %) was achieved for 25 % B4C-75 % SiC sample densified at 2000 °C. Obtained composites' microhardness ranged from 33 to 43 GPa, depending on constituents' content and densification temperature. Maximal microhardness was achieved for composite with the maximal amount (75 %) of B4C densified at 2000 °C. Composites' behavior in extreme conditions was evaluated through their interactions with laser beam and obtained results showed that SPS is effective densification method for obtainment of additive-free B4C-SiC composites applicable in extreme radiation environments.