Microstructural evolution of TiB2-SiC composites empowered with Si3N4, BN or TiN: A comparative study

Three near fully dense TiB2-SiC composites were achieved, benefiting from the coaddition of SiC and a nitride compound (Si3N4, h-BN or TiN). All composites were produced by spark plasma sintering (SPS) at 1900 degrees C. The in-situ formed TiC phase was identified in the all three composites due to occurring a chemical reaction between TiO2 oxide and SiC reinforcement. Although h-BN additive remained intact in the final microstructure of TiB2-SiC composites, Si3N4 additive participated in some chemical interaction with B2O3 and TiO2 surface contaminations, leading to the in-situ generation of h-BN, TiB2, and SiO2 phases. In contrast, TiN additive reacted with the in-situ formed TiC, producing the TiCxN1-x compound during the sintering process. Liquid phase sin-tering was also identified as one of the involved mechanisms, enhancing the sinterability of the prepared composites.