Synthesis and properties of conductive B ₄ C ceramic composites with TiB ₂ grain network

Abstract

Abstract High electrical resistance and low fracture toughness of B 4 C ceramics are 2 of the primary challenges for further machining of B 4 C ceramics. This report illustrates that these 2 challenges can be overcome simultaneously using core‐shell B 4 C‐TiB 2 &TiC powder composites, which were prepared by molten‐salt method using B 4 C (10 ± 0.6 μm) and Ti powders as raw materials without co‐ball milling. Finally, the near completely dense (98%) B 4 C‐TiB 2 interlayer ceramic composites were successfully fabricated by subsequent pulsed electric current sintering ( PECS ). The uniform conductive coating on the surface of B 4 C particles improved the mass transport by electro‐migration in PECS and thus enhanced the sinterability of the composites at a comparatively low temperature of 1700°C. The mechanical, electrical and thermal properties of the ceramic composites were investigated. The interconnected conductive TiB 2 phase at the grain boundary of B 4 C significantly improved the properties of B 4 C‐TiB 2 ceramic composites: in the case of B 4 C‐29.8 vol% TiB 2 composite, the fracture toughness of 4.38 MPa·m 1/2 , the electrical conductivity of 4.06 × 10 5 S/m, and a high thermal conductivity of 33 W/mK were achieved.