Large scale production of graphene aluminum composites by stir casting: Process, microstructure and properties

Graphene has recently garnered significant attention as an exceptional nanofiller for aluminum (Al) matrix composites due to its remarkable mechanical strength, elevated thermal and electrical conductivities. For practical industrial applications, it is necessary to develop large-scale production technology. To this end, we have utilized a scalable stir-casting process to fabricate graphene-reinforced aluminum matrix composites. The microstructure, mechanical properties, electrical and thermal conductivities of the composites with varying graphene contents were characterized. Through testing, it was confirmed that graphene remained intact within the aluminum matrix during the stir-casting process, and the damage to the graphene sheet during the fabrication of composites was slight. High-resolution microscopic observation shows that aluminum, graphene and aluminum carbide co-exist within the composites. Compared to its pure aluminum counterpart, the Vickers hardness of the optimal composite sample (with a graphene content of 0.2 wt.%) exhibits a significant increase of 42%. Also, this superior composite sample exhibits a remarkable increase of 5% and 38% in its electrical and thermal conductivities respectively. The performance evolution and improvement mechanisms have been thoroughly investigated and revealed. The test results suggest that preformed blocks and stir casting are promising technologies for the large-scale production of graphene-aluminum composites.