Electrical resistivity and flexural strength of mullite‐bonded porous SiC: Effect of transition metal additives

Abstract

AbstractThe influence of various transition metal (Mo, Co, Ni, and Fe) additives on the electrical and mechanical properties of mullite‐strengthened SiC sintered in the range of 1100–1500°C under an Ar atmosphere was investigated. Kaolin was added as a low‐temperature sintering aid in the designed formulations. The addition of metal additives reduced the electrical resistivity, enhanced the mechanical strength, and produced samples with an approximately 40% porosity. The decrease in electrical resistivity was attributed to the in situ formation of electrically conductive metal silicides, whereas the conversion of kaolin to mullite enhanced the mechanical properties. The comparative study shows that at the same metal‐additive content (15 wt%), Fe was the most effective element to reduce the electrical resistivity and increase the flexural strength, which were recorded as 8.0 × 100 Ω cm and 20 ± 2 MPa, respectively, of the samples sintered at merely 1300°C.