Hot Pressing Sintering and Properties of Silicon Carbide/Graphite Composite Ceramics Containing 30 wt% Graphite

ABSTRACT Silicon carbide/graphite composite ceramics containing 30 wt% (SiC/C30) and 35 wt% (SiC/C35) graphite were fabricated by hot pressing sintering, and the sintering behavior, microstructure, mechanical properties, and functional properties of the composite ceramics were investigated in detail. The combination of spray‐drying granulation and hot pressing sintering synergistically overcomes the densification barrier caused by high graphite content. The external driving force supplied by hot pressing sintering not only promotes densification, but also facilitates the formation of a continuous conductive network even when the carbon content is high. The appropriate sintering conditions with a temperature of 2125°C and a pressure of 40 MPa allow the preparation of SiC/C30 composite ceramics with superior mechanical properties and excellent functional performance with a bulk density of 2.763 g/cm 3 , a bending strength of 318 ± 3.8 MPa, a Vickers hardness of 5.73 ± 0.09 GPa, a fracture toughness (K IC ) of 2.36 ± 0.023 MPa·m 1/2 , a room‐temperature thermal conductivity of 69.92 ± 0.39 W/(m·K), an electrical conductivity of 8.932 ± 0.102 S/m, and coefficient of friction (COF) of 0.172 ± 0.00010.