Fracture toughness and toughening mechanisms in graphene platelet reinforced Si3N4 composites

Silicon nitride + 1 wt.% graphene platelet composites were prepared using various graphene platelets with the aim to improve the fracture toughness of Si3N4. The fracture toughness was significantly higher for all composites in comparison to the monolithic Si3N4, with the highest value of 9.92 MPa m0.5. The main toughening mechanisms originated from the presence of graphene platelets, and the increase in the fracture toughness values was attributable to crack deflection, crack branching and crack bridging.