1School of Metallurgy and Materials Eng., Faculty of Eng., University of Tehran
2School of Metallurgy and Materials Eng, Faculty of Eng., University of Tehran
Aluminium matrix composites (AMCs) developed for lightweight applications particularly in aerospace and automobile sectors. Graphene nanoplates (GNPs) became an attractive reinforcing agent for AMCs due to their high thermal conductivity, low coefficient of thermal expansion, high damping capacity and excellent self-lubrication properties. In this study, aluminum-graphene-graphite (Al-GNPs-Gr) hybrid nanocomposites fabricated through a relatively new technique termed as flake powder metallurgy. In the first stage, Al-GNPs powder mixtures containing different amounts (0.25, 0.5, 0.75 and 1.0 wt.%) of GNPs were ball milled along with semi-spherical Al powders for 6h and subsequently consolidated through hot extrusion at 480°C. The resultant Al-GNPs composites subjected to SEM and optical microscopy as well as macrohardness and porosity measurements. A pin-on-disc wear testing tribometer used to carry out the dry sliding wear tests on these samples. The results confirmed that the Al-GNPs composite containing 0.5 wt.% of reinforcing agent exhibited the maximum macrohardness together with minimum wear rate. Then Al-GNPs-Gr hybrid nanocomposites containing different amounts of graphite (3, 5, 7 and 9 wt.%) and keeping 0.5 wt.% GNPs constant were synthesized via the same route as for Al-GNPs composites. SEM and optical microscopy images of composite samples confirmed that the reinforcing particles distributed uniformly within the layered structure (flakes) of the Al matrix. The results of sliding wear tests revealed that Al-0.5 wt.%. GNPs-9 wt.% Gr hybrid nanocomposite showed the minimum wear rate among the hybrid composites. However, Al-0.5wt.%. GNPs nanocomposite showed the minimum wear rate among all the composite samples.