Mechanical properties and toughening mechanisms of graphene platelets reinforced Al2O3/TiC composite ceramic tool materials by microwave sintering

A type of Al2O3/TiC composite ceramic tool material reinforced with graphene platelets (GPLs) was fabricated by microwave sintering. The effects of GPLs content on the microstructure, mechanical properties and toughness mechanisms of Al2O3/TiC/GPLs composite ceramic tool materials were studied. The experimental results showed that the microstructure of the composite became finer with the incorporation of GPLs. The optimal mechanical properties were achieved with 0.2 wt% GPLs. The relative density, Vickers hardness and fracture toughness were 97.7±0.2, 18.5±0.5 GPa and 8.7±0.4 MPa m1/2, respectively. Compared to Al2O3/TiC composites, the Vickers hardness decreased by 12.7%, but the fracture toughness increased by 67.3%. Also, agglomerated GPLs and pores were observed in the new composite ceramic tool materials. The toughening mechanisms were crack deflection, crack bridging, crack branching and pull-out of GPLs.