Mechanical properties and microstructure of reaction sintering SiC ceramics reinforced with graphene-based fillers

TLDR: In this article, the fracture toughness and bending strength of reaction sintering SiC ceramics were evaluated as a function of the type of graphene source and graphene content, and the relationship between phase content and mechanical properties was discussed.

Abstract: To improve the fracture toughness and bending strength of reaction sintering SiC ceramics, graphene oxide (GO) and reduced graphene oxide (rGO) were selected as fillers to develop reinforced SiC ceramic composites by reactive sintering in the current work. Different amounts (0.5, 1.0, 1.5, or 3.0 wt.%) of graphene-reinforced reaction-bonded silicon carbide (RBSC) composites were fabricated. The mechanical behaviors of the materials were evaluated as a function of the type of graphene source and graphene content. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis showed that graphene was maintained after reactive sintering by liquid infiltration of molten silicon. Both the fracture toughness and bending strength of the RBSC increased with employing graphene-based additives. GO showed the most significant positive effects on improving mechanical performance of RBSC ceramics. The highest fracture toughness of 3.6 MPa m1/2 was obtained at 1.5 wt.% of GO addition. It was 33% higher than that of RBSC without graphene. The highest bending strength corresponded to the composite reinforced with GO content of 1.0 wt.%. It was about 58% higher than that of RBSC ceramic. The relation between phase content and mechanical properties was discussed. The main toughening mechanism was sheet pullout/debonding and the distribution of graphene along grain boundaries.