Synthesis of Ti_3SiC_2 by pressureless sintering of the elemental powders in vacuum

摘要

Green compacts fabricated from Ti, Si and C powders with molar ratio of 3:1:2 were pressureless sintered at 1340 deg C to 1750 deg C for 20-180 min in vacuum. X-ray diffraction (XRD) was applied to determine the phase compositions of the products. It was found that Ti_3SiC_2 was obtained in most cases. TiC is the most common impurity, while TiSi_2 and Ti_5Si_3 will occur, respectively, if the compacts are sintered at excessively high or low temperatures. Besides the reaction thermodynamics and kinetics, loss of Si and contamination of C may be the most important reasons for the appearance of the impurities. Sintering at 1450 deg C for 120 min yields samples containing 81 vol. percent Ti_3SiC_2. The purity of Ti_3SiC_2 in the products is hopefully increased if the molar ratio of the elemental powders were optimized.