A Concurrent Process for the Synthesis and Fabrication into Rods of the Ternary Compound Ti3SiC2 by means of a Traveling-Zone Sintering Method

A Concurrent process for the synthesis and fabrication into rods of the machinable ceramic Ti3SiC2 by using a traveling-zone sintering method was investigated. Two different powder mixtures were prepared for the synthesis of Ti3SiC2. The first (TSC1) had the stoichiometric composition of Ti/Si/C = 3:1:2. In the second (TSC2), TiC was used instead of C to give a molar composition Ti/Si/TiC = 2:2:3. In the production of Ti3SiC2 rod from TSC1, there was a tendency for the cylindrical mold to become cracked during the sintering, because the synthesis of Ti3SiC2 from the simple mixture of Ti, Si and C occured by a tandem process and the primary exothermic reaction of Ti with C to form TiC caused a large thermal expansion of the material compact. On the other hand, Ti3SiC2 rod was successfully produced from the TSC2 mixture. Their density was elevated as increasing the sintering temperature and reducing the rate of movement of the stage, but employing too high temperature caused a reaction between the material powder and the mold, resulting in the product having unsatisfactory properties. The Ti3SiC2 rod produced contained varying amounts of TiC phase, the percentage of which showed a tendency to decrease under the same sintering conditions required to obtain a high density. We concluded that a well-densified, homogeneous Ti3SiC2 rod with high purity can be produced by the traveling-zone sintering method under the sintering conditions of a high temperature and a prolonged sintering time, if attention is paid to preventing reaction between the material compact and the mold.