Mechanical properties of electrically conductive silicon carbide ceramics

The mechanical properties of electrically conductive SiC ceramics sintered with 2 vol% Y2O3 were characterized. A submicron SiC powder and a mixture of submicron SiC powder and polycarbosilane (PCS) were hot-pressed with 2 vol% Y2O3 at 2000 °C for 6 h under an applied pressure of 40 MPa in a nitrogen atmosphere. The SiC without PCS had a finer microstructure consisting of equiaxed grains, whereas the SiC with PCS had a coarser microstructure with equiaxed grains. The coarser microstructure was beneficial in lowering the electrical resistivity but resulted in deteriorated mechanical properties. The typical flexural strength, micro-hardeness, fracture toughness, and electrical resistivity values of the SiC ceramics without PCS were 678 MPa, 30 GPa, 5.2 MPa m1/2, and 7.8×10−2 Ω cm at room temperature, respectively.