Fabrication and Properties of TiC Matrix Composite Reinforced with Dispersed Graphite Microcrystals Formed during the Sintering

Titanium carbide containing 5-15 wt% graphite was fabricated by hot-pressing at 2000°-2200°C using carbon black as a starting carbon material. B4C of 1wt% was doped in TiC as sintering additive before mixing with carbon black. X-ray diffractometry and SEM revealed that the grain growth of TiC was suppressed significantly by the carbon addition, and that the carbon black changed to flaky graphite microcrystals 3-5μm across and 0.5-2μm thick. The graphite microcrystals were located at the TiC grain boundaries and even in TiC grains. Carbon addition increased the flexural strength of the composite appreciably. The composite with 10% carbon had the strength of 767MPa, nearly double for monolithic TiC, 427MPa. The fracture toughness of 6.72MPa√m the 10% carbon composite was obtained, as compared with 5.19 and 3.76MPa√m for monolithic TiC doped with and without B4C as a sintering additive, respectively.