Electrical and thermal properties of SiC–AlN ceramics without sintering additives

Ceramics of SiC–AlN, consisting of α-SiC (6H and/or 4H) and 2H SiC–AlN solid solution (2Hss), were fabricated by conventional hot-pressing in an Ar atmosphere without sintering additives. The electrical resistivities of the SiC–AlN ceramics were 1.9 × 106 Ω cm for 2 vol% AlN, 3.7 × 109 Ω cm for 10 vol% AlN, and 1.1 × 1010 Ω cm for 35 vol% AlN, at room temperature. There was an increasing trend in resistivity with increasing AlN content which was most likely due to increased Al impurities at Si site acting as deep acceptors for trapping nitrogen-derived carriers. The thermal conductivity of the SiC–AlN ceramics showed a decreasing trend: 104.1 W/m K at 2 vol% AlN, 49.8 W/m K at 10 vol% AlN, and 35.1 W/m K at 35 vol% AlN content, due to increasing 2Hss content in the ceramics. There was a trade-off in improving both the thermal conductivity and electrical resistivity in SiC–AlN ceramics.