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 °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 TiC_xN_1-x compound during the sintering process. Liquid phase sintering was also identified as one of the involved mechanisms, enhancing the sinterability of the prepared composites.