Effect of the amounts of silicon on the in situ synthesis of Ti_3SiC_2 based composites made from TiC/Si powder mixtures

摘要

This paper describes how variations in silicon content and heat treatment influence the phase composition of TiC/Si powder mixtures during heat treatment. The sintering procedure is investigated with respect to the phases produced with a particular emphasis on maximisation of the Ti_3SiC_2 content. The heat treated products have been analysed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. In the heat treated products Ti_3SiC_2 and TiC are the dominant phases and SiC and TiSi_2 are found in smaller (0-30 vol.%) amounts. The composition was found to depend on both Si content and heat treatment temperature and time. The silicon content can be optimised with respect to maximum Ti_3SiC_2 production, but its value changes with different temperature programs. The highest amount (56 vol.%) of Ti_3SiC_2 is achieved by heat treating powder mixtures of initial composition 3TiC/2.2Si at 1350° for 1 h. Heat treatment at lower temperatures (1250-1300 °C) results in an incomplete reaction and production of TiSi_2.