Directional properties and microstructures of spark plasma sintered aluminum nitride containing graphene platelets

Abstract

Graphene platelets (GPLs) containing aluminum nitride (AlN) composites were produced by using both pressureless sintering and spark plasma sintering (SPS). Poor densifications were obtained when composites were pressureless sintered whereas highly dense composites were successfully produced by using SPS. In addition, the applied uniaxial load in the SPS resulted in the orientation of GPLs in the microstructure of composites, indicating that composites would have anisotropic properties. All the mechanical, thermal and electrical properties in the in-plane direction were better than the through-plane direction. Fracture toughness of composites with the addition of 1wt% GPLs were increased more than 30% compared to AlN matrix. Increased anisotropic effect with increasing amount of GPLs led to even larger differences on the thermal conductivities in through-plane and in-plane directions. AlN also became an electrically conducting material after ∼1wt% GPLs addition in both through-plane and in-plane directions.