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

Abstract

AbstractA 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°C). According to the calculated Pr–Si–C‐phase diagram, the liquid phase was formed at ∼1217°C, which effectively improved the sintering rate of SiC by the solution–reprecipitation process. When the sintering temperature increased from 1400 to 1600°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.