Reactive sintering and thermodynamics of Ti₃SiC₂/SiC composites

The synthesis of Ti₃SiC₂/SiC composites was studied by testing 3TiC+2Si or 3TiC+2.2Si + xAl (x = 0 or 0.2) as sintering mixtures. In order to reveal the mechanism of reactive sintering of Ti₃SiC₂/SiC composites, the mixtures were sintered either by pressureless sintering or by sintering under pressure between 1200 °C and 1500 °C during 15min. The results showed that the nucleation of SiC grains occurs first at the surface of the TiC grains, limiting therefore the progression of the conversion at 1200 °C and 1300 °C. Silicon defects are the main limitation of the synthesis of Ti₃SiC₂/SiC composites because of volatilization and molten silicon losses. The addition of aluminum promotes the conversion by reacting with oxygen and resulting in the formation of Al₂O₃ at the grain boundaries. The optimum experimental parameters for the synthesis of Ti₃SiC₂/SiC composites were determined to be a TiC/Si/Al molar ratio of 3/2.2/0.2 maintained at 1500 °C for 15min.