Preparation of a graphite / SiC composite casting material and study of its performance

Abstract

The inferior mechanical properties and thermal conductivity of carbon graphite materials are attributed to the presence of pores and cracks. The integration of graphite with ceramics has been proposed as a method to enhance these properties; however, graphite/ceramic composites fabricated through pressureless sintering often exhibit inadequate integration. In this paper, a diffuse-continuous network dual-reinforced graphite/silicon carbide(SiC) ceramic composite was prepared by integrating the graphite powder micro-thermal press forming technology with the fused deposition modelling(FDM) technology and combining the pressureless sintering and vacuum pressure impregnation processes. It was found that the addition of high purity silicon powder to the material formulation reacts with the resin carbon to form silicon carbide particles (SiC-p), which can play a role in diffusion enhancement. However, the addition of excessive silicon powder can have a detrimental effect, and the performance of diffusion enhanced graphite/silicon carbide composites is positively correlated with the density of billet formation, and the effect of diffusion continuous network dual enhancement is more obvious, and the performance of the composites is better compared to that of single diffusion enhancement. The compressive and flexural strengths of the graphite/SiC composites finally obtained reached 59.47 MPa and 44.25 MPa, respectively, and the thermal conductivity was 43.62 W/m·K, and the porosity and open porosity were 29.62 % and 20.48 %, respectively, which are comparable to those of manmade graphite castings, and have better gas permeability, which is expected to be applied in the casting field.