Indentation Fracture Toughness of Al_2O_3 + GPLs and Si_3N_4 + GPLs Systems

摘要

The influence of 1 wt.% and 2 wt.% of graphene platelets (GPLs) addition on indentation fracture toughness (IF) of Al_2O_3 and Si_3N_4 based composites has been investigated and compared to the monoliths. Ceramic composites reinforced with GPLs were prepared using hot-press processing technology. Microstructures were observed at fracture surfaces by scanning electron microscopy (SEM). Crack type identification was performed by gradually polishing of the indentation surface and mechanical properties of both systems were measured. Indentation fracture toughness was calculated by various methods and R-curves were prepared. The main activated toughening mechanisms, responsible for the increased fracture toughness are crack deflection, crack branching and crack bridging in the forms of graphene sheet pull-out or graphene necking.