Powder processing methodology for production of graphene oxide reinforced aluminium matrix composites

In this paper, the preparation and properties of reduced graphene oxide (rGO) reinforcement of aluminium matrix nanocomposites (AMCs) are presented. The commercial colloidal graphene oxide was firstly coated on the selected aluminium powder particles, and the graphene oxide was then reduced through thermal annealing process. The rGO-aluminium powder dispersions were prepared in order to provide coated aluminium particles before synthesis of the metal matrix nanocomposites. As-received pristine aluminium powder and pre-synthesised rGO-AMCs were cold compacted into disc-shaped specimens and sintered. The mechanical properties and microstructure were studied and characterised via Vickers hardness, a flexural bending test, X-ray diffraction and scanning electron microscopy. The rGO was observed to be dispersed effectively in the aluminium matrix and well consolidated within the composites. The relevant factors for the powder metallurgy process, e.g. compaction pressure, density, sintering conditions, have been elaborated and optimised. Enhancements of 32% in micro hardness of 0.3 wt.% rGO-Al composites were observed compared to the baseline pure aluminium prepared under identical experimental conditions. The graphene oxide and graphene nanosheets have proven potentially capable of realising mechanical reinforcements in aluminium matrix composites under cold compaction and sintering powder metallurgy techniques only.