Effect of the graphene content on the microstructures and properties of graphene/aluminum composites

A graphite mold was filled with a mixed powder of aluminum and graphene. It was evacuated to 2×10^-1 Pa, pre-pressed under 10 MPa, heated to 450℃ where it was kept for 5 min, pressed again under 40 MPa, heated to 600℃ where it was kept for another 5 min to prepare graphene/aluminum (G/Al) composites. The effect of the graphene content on the microstructure, and thermal, electrical, mechanical and anticorrosive properties of the composites was investigated. Results indicate that when the graphene content is 0.5 wt.%, it is uniformly dispersed at grain boundaries in the Al matrix. Compared to pure Al the resulting composite has thermal and electrical conductivities that are respectively 7.1% and 4% higher, tensile strength and hardness that are 30.6% and 44% higher, and a corrosion resistance that is 31% higher. When the graphene content exceeds 0.5 wt.%, it agglomerates at grain boundaries in the Al matrix, leading to a decrease of all the above-mentioned properties.