| Abstract Scope |
This study investigates the influence of carbon content (2.5-13.0 wt.%), on
pressureless sintered SiC ceramics with 0.8 wt.% B4C. Electrical resistivity sharply decreases from 4.7×102 to 9.1×10−2 Ωcm as carbon exceeds 7.0 wt.%, attributed to the formation of a conductive network. Thermal conductivity decreased from 151.6 to 116.5 Wm−1K−1 due to increased phonon scattering, carbon volume fraction, and porosity. The highest flexural strength (384.0 MPa) and hardness (29.1 GPa) occur at 4.0 wt.% carbon, but both drop at higher content. Fracture toughness increases from 2.7 to 3.8 MPa m1/2 with more carbon, driven by enhanced crack deflection. At 10.0 wt.% carbon, the material exhibits resistivity of 9.3 × 10−1 Ωcm, thermal conductivity of 129.9 Wm−1K−1, flexural strength of 226.2 MPa, fracture toughness of 3.6 MPa m1/2, and hardness of 21.8 GPa. The results demonstrate a trade-off between electrical conductivity and mechanical properties as carbon content increases. |