Graphene Reinforced Silicon Carbide Nanocomposites: Processing and Properties

Abstract

This study investigates the effect of graphene nanoplatelets on the microstructure and mechanical properties of silicon carbide (SiC). Graphene nanoplatelets are dispersed in a liquid preceramic polymer by ball milling. Pyrolysis of the graphene nanoplatelet–preceramic polymer slurry results in near-stoichiometric SiC–graphene nanoplatelet powder. This method leads to improved dispersion of graphene in the SiC matrix as compared to conventional mechanical blending of dry powders and thereby significantly influences the resulting mechanical properties. Subsequently, spark plasma sintering (SPS) is used to consolidate dense bulk SiC–graphene composites with varying graphene content up to a maximum of 5 wt%. X-ray diffraction (XRD) investigation reveal that inclusion of graphene restricts grain growth of SiC matrix during SPS processing. Fracture toughness of SiC-graphene composite is increased by 40 % with the inclusion of 2 wt% graphene nanoplatelets. However, for higher graphene content the change in fracture toughness is limited. Improvement in fracture toughness is due to crack bridging reinforcing mechanism provided by the graphene platelets. Finally, Raman spectroscopy is used to understand the effect of SPS processing on integrity of graphene nanoplatelets.