Synthesis and Characterization of a Metallic Ceramic Material–Ti<SUB>3</SUB>SiC<SUB>2</SUB>

Abstract

Various powder mixtures from the starting powders of Ti/Si/C, Ti/SiC/C, Ti/Si/TiC, Ti/SiC/TiC and Ti/TiSi2/TiC were used for the synthesis of ternary compound titanium silicon carbide (Ti3SiC2) by using a pulse discharge sintering (PDS) process. The Ti/Si/TiC powder was found to be the best among the five powder mixtures for Ti3SiC2 synthesis. Phase purity of Ti3SiC2 can be improved to ≈99 mass% at the sintering temperature of 1300°C for 15 min. The relative density of all the synthesized samples is higher than 98–99% at the sintering temperature above 1275°C. The nearly single phase Ti3SiC2 was found to show plastic deformation at room temperature and good machinability. Both electrical and thermal conductivity were found to be greater than two times of the values of a control pure Ti sample fabricated by the same sintering process. The thermopower of the synthesized Ti3SiC2 was measured to be nearly zero in the testing temperature range, much lower than some common low thermopower substances such as gold or carbon. Their mechanical properties at ambient and elevated temperatures were also examined. The ternary compound Ti3SiC2 is referred to as a “metallic ceramic” according to its physical and mechanical behavior representing both metals and ceramics.