High electrical resistivity of pressureless sintered in situ SiC–BN composites

SiC–BN composites with a BN content of 6 wt.% were pressureless sintered to ∼99.4% theoretical density at 2200 °C for 1 h and found to have a high electrical resistivity of 1.24 × 1010 Ω cm. Starting B4C and C were added to react partially with Si3N4 for in situ synthesis of BN and also to serve as sintering aids. Interface diffusion of B and N from BN into SiC was crucial to improving the insulating and dielectric properties through carrier compensation without causing any obvious decrease in the thermal conductivity.