Self-propagating high-temperature synthesis of TiC-TiB2-based Co cermets from a Co-Ti-B4C system and fabrication of coatings using the cermet powders

TiC-TiB2-based Co cermets with various Co contents were successfully synthesized by self-propagating high-temperature synthesis (SHS) from a Co-Ti-B4C system. Effects of Co content and particle size of Ti and B4C powders on the SHS reaction were investigated. It was found that with an increase in Co content, the ignition delay time first decreased and then increased. The SHS products consisted of the desired phases of TiC, TiB2 and Co regardless of the Co content. The particle size of Ti and B4C powders had negligible effects on the combustion temperature and SHS products to some extent. However, the ignition of SHS reaction was significantly dependent on the Ti and B4C powders, especially on the B4C powders. The formation mechanism of TiC and TiB2 during SHS was proposed based on the combustion-wave quenching experiment. Moreover, the TiC-TiB2-based Co cermet coatings were fabricated by atmospheric plasma spraying using the SHS-derived powders, which could provide better wear resistance for the alloy substrates such as steel.