Mechanical and thermal properties of reduced graphene oxide reinforced aluminum nitride ceramic composites

High density reduced graphene oxide (rGO) reinforced aluminum nitride (AlN) composites were successfully fabricated by the one-step spark plasma sintering (SPS) method. Raman spectra showed that the raw material of GO was thermal reduced to rGO during the SPS process, and the reduction of GO can be strongly affected by the carbonaceous atmosphere. With the rGO content increasing (0-2 wt %), the dispersion of rGO and relative density of the composites decreased, decreasing the elastic modulus and hardness accordingly. However the flexural strength had a slight increase when rGO content was ≤1 wt%, and the fracture toughness increased from 3.5 to 5.2 MPa m1/2 with the rGO due to the crack bridging and pulling out of rGO. The thermal conductivity of the composites was low and sharply decreased from 92.5 to 37.4 W m−1 K−1 with the addition of rGO, which are attributed to the low crystalline quality and high vacancy defects in rGO and the increase of interfacial thermal resistance.