Rapid synthesis of ternary carbide Ti₃SiC₂ through pulse-discharge sintering technique from Ti/Si/TiC powders

Abstract

Ti/Si/TiC powders with molar ratios of 1:1:2 (M1) and 2:2:3 (M2) were prepared for the synthesis of a ternary carbide Ti₃SiC₂ by using the mixture method for 24 hours in an Ar atmosphere. The synthesis process was conducted at 1200 °C to 1400 °C under a pressure of 50 MPa, using the pulse-discharge sintering (PDS) technique. After sintering, the phase constituents and microstructures of the samples were analyzed by X-ray diffraction (XRD) technique and observed by optical microscopy and scanning electron microscopy. The results showed that the phases in all the samples consisted of Ti₃SiC₂ and small amounts of TiC, and the optimum sintering temperature was found to be in the relatively low range of 1250 °C to 1300 °C. By the standard additive method, the relative content of Ti₃SiC₂ was calculated. For the M1 samples, the lowest TiC content can be only decreased to about 3 to 4 wt pct, whereas the content of Ti₃SiC₂ in the M2 samples is always lower than that in the M1 samples. When the M2 powder was sintered at 1300 °C for 8 to 240 minutes, the TiC peaks were found to show a very low intensity, and the corresponding content of Ti₃SiC₂ was calculated to be higher than 99 wt pct. The grain size of Ti₃SiC₂ increased from 5 to 10 µm to 80 to 100 µm in the entire applied sintering temperature range. The relative density of the M2 samples was measured to be higher than 99 pct at sintering temperatures above 1275 °C. It indicates that the PDS technique can rapidly synthesize high-content Ti₃SiC₂ from the Ti/Si/TiC powders in a relatively low temperature range.