Low-temperature Pr3Si2C2-assisted liquid-phase sintering of SiC with improved thermal conductivity

A novel Pr3Si2C2 additive was uniformly coated on SiC particles using a molten-salt method to fabricate a high-density SiC ceramics via liquid-phase spark plasma sintering at a relatively low temperature (1400 degrees C). According to the calculated Pr-Si-C-phase diagram, the liquid phase was formed at similar to 1217 degrees C, which effectively improved the sintering rate of SiC by the solution-reprecipitation process. When the sintering temperature increased from 1400 to 1600 degrees C, the thermal conductivity of SiC increased from 84 to 126 W/(m K), as a consequence of the grain growth. However, an increasing amount of the sintering additive increased the interfacial thermal resistance, resulting in a decrease of thermal conductivity of the materials. The highest thermal conductivity of 141 W/(m K) was obtained for the material having the largest SiC grains and an optimized amount of the additive at the grain boundaries and triple junctions. The proposed Pr3Si2C2-assisted liquid-phase sintering of SiC can be potentially used for the fabrication of SiC-based ceramic composites, where a low sintering temperature would inhibit the grain growth of SiC fibers.

Automated summary

In this study, a novel Pr3Si2C2 additive was prepared and successfully applied in the liquid-phase sintering of SiC ceramics. It was found that an appropriate amount of additive could improve the sintering rate and thermal conductivity of SiC, while excessive additive could decrease the thermal conductivity due to increased interfacial thermal resistance. SiC materials with optimized amount of additive and grain boundary structure exhibited the highest thermal conductivity.