Graphene nanoplatelets reinforced aluminum alloy matrix composites produced by spark plasma sintering

Aluminum alloys (A.A.) are interesting for their low weight and good mechanical properties. The addition of graphene nanoplatelets (GNPs) can reduce the density and modify the functional properties and mechanical performance of the metal matrix. Graphene reinforced A.A. matrix composites (AA-GNPs) were prepared by spark plasma sintering technique (SPS), using commercial graphene nanoplatelets mixed with recycled milled A.A. chips. Monolithic A.A. and aluminum composites with 2.5 wt.% of GNPs (AA-2.5GNPs) were compacted into disc-shaped samples. The microstructure was studied and characterized by optical (O.M.) and scanning electron (SEM) microscopies. Hardness was measured, and tribological properties were studied by the ball-on-disc technique. The coefficients of friction and wear rates were evaluated. Worn surfaces were studied by SEM and confocal microscopy, and the oxidation level was measured using EDX spectrometry. The developed process presented here provides promising results for preparing AA-2.5GNPs nanocomposites from low-cost recycled A.A. chips with SPS.