Graphene nanosheet reinforced ZrB₂-SiC ceramic composite by thermal reduction of graphene oxide

A graphene nanosheet reinforced ZrB₂-SiC ceramic composite (GNs/ZrB₂-SiC) using graphene oxide (GO) was hot pressed at 1950°C and 30 MPa for 1 h. Raman and XPS analysis showed multilayer GNs structures were successfully introduced into the composite by in situ thermal reduction of GO during the hot pressing process. The homogeneous dispersion of GO guaranteed the uniform distribution of GNs structures in the composite. Mechanical properties such as bending strength, fracture toughness and hardness were studied for the ZrB₂-SiC composite with different volumes fraction of GO. The addition of approximately 5 vol% graphene nanosheets improved the fracture toughness of ZrB₂-SiC up to 7.32 MPa m^0.5, and the strength was also raised to 1055 MPa. The toughening mechanisms were graphene crack bridging and pulling out induced crack deflection in the GNs reinforced composite.