Investigation of the effect of pressure, sintering temperature and time on silicon carbide microstructure

In this research, SiC ceramics were densified via spark plasma sintering (SPS) with 0.5wt.% B4C and 1.5wt.% C additions at temperatures ranging from 1900 to 2000?C for 5-65min under 10-50MPa applied pressure with an intermediate dwell at 1400?C, and the effects of applied pressure, sintering temperature, and dwelling time were examined. The samples sintered under 50MPa applied pressure had high density (>99%), and showed high elastic modulus (~420MPa). However, lower applied pressure caused a decrease in density and elastic properties. The increase of sintering temperature from 1900 to 2000?C, while sintering time and pressure remained the same, caused grains coarsening. Increasing the dwelling time for the samples sintered at 1900 and 2000?C showed that sintering at a relatively lower temperature for a longer period of time did not increase grain size significantly. On the other hand, increasing the dwelling time at 2000?C caused excessive grain growth. The results show that fine-grained highly dense SiC can be produced by spark plasma sintering at 1900?C for 5min under 50MPa.