Synthesis of single-phase Ti3SiC2 from coarse elemental powders and the effects of excess Al

Single-phase Ti3SiC2 was successfully prepared by using a new ratio of raw materials and coarse starting powder (similar to 70 mu m). To reveal the mechanism of aluminum acting as a sintering aid in the reaction synthesis of singlephase Ti3SiC2, mixtures of 3T1/1.5Si/1.9C/xAl (x = 0-0.6) were sintered to synthesize Ti3SiC2 through pressureless sintering. The results showed that the molten Al reacted with oxygen to act as a deoxidizer and promoted the nucleation of Ti3SiC2 during the sintering process. An optimal amount of Al can accelerate the reaction between the TiC and Ti5Si3 intermediate phases, while excessive Al will hinder diffusion and reduce the purity of Ti3SiC2 by forming Al2O3 on the grain boundaries. The optimum experimental parameters for the synthesis of single-phase Ti3SiC2 were determined as a Ti/Si/C/Al molar ratio of 3/1.5/1.9/0.5, holding at 1400 degrees C for 2 h.