High Pressure. Synthesis of Highly Dense Ti3SiC2 by HIP and Its Characterization.

The pure and dense Ti3SiC2 material was tried to fabricate by two different approaches; HIP sintering of the SHS-derived Ti3SiC2 powders, and the reactive-HIP sintering of the mixed powders of Ti, SiC, and C. The product with the highest content of Ti3SiC2 consisted of 97.3vol% Ti3SiC2 and the remaining TiCx. This material was obtained by the reactive-HIP, carried out at 1500°C, 40MPa for 30min. The density was 99% of theoretical. The Ti3SiC2 grains had columnar and plate-like shapes, which included many stacking faults along the (001) plane. The Vickers hardness, Young's modulus, fracture toughness, and flexural strength were 4GPa, 283GPa, 11.2MPa √m, 410MPa, respectively. These mechanical properties are considered to be almost the intrinsic property of the bulk Ti3SiC2. The severe oxidation of the Ti3SiC2 started at about 1100°C. The electrical resistivity was 1.77×10-6Ωm at room temperature. It increased with increasing temperature, but showed the discontinuous change at around 1030-1040K. The Seebeck coefficient was 4-20μV/K in the range from 300K to 1200K. This small positive value suggests that the Ti3SiC2 is a semimetal with hole carriers.