Effects of Y2O3–RE2O3 (RE = Sm, Gd, Lu) additives on electrical and mechanical properties of SiC ceramics containing Ti2CN

Dense SiC–Ti2CN composites were fabricated from β-SiC and 4 vol% TiN powders with 2 vol% equimolar Y2O3–RE2O3 (RE = Sm, Gd, Lu) additives by conventional hot pressing. Electrical and mechanical properties of the SiC–Ti2CN composites were investigated with a variation of sintering additive composition. Relative densities of ∼99.9% were achieved for all specimens. All specimens exhibited electrical resistivities on the order of ∼10−5 Ω m. These low electrical resistivities were attributed to heavy nitrogen doping in the SiC lattice (carrier density ∼1020 cm−3). Typical electrical resistivity, flexural strength, fracture toughness, and Vickers hardness values of the SiC–Ti2CN composite sintered with 2 vol% Y2O3–Lu2O3 additives were 2.2 × 10−5 Ω m, 722 MPa, 4.6 MPa m1/2, and 25 GPa, respectively.