Synergistic effects of graphene nanosheets on the microstructure, hardness and tribological performance of Al/WC nanocomposites fabricated by flake powder metallurgy

Abstract

This research investigates the characteristics of a newly developed Al-WC-graphene nanocomposite, fabricated via flake powder metallurgy (FPM) technique. For exploring the best root for a successful graphene nanosheets (GNSs) dispersion, two distinct mixing procedure examined. The effects of GNS concentration and FPM processing parameters on the microstructure, porosity, hardness, fracture and dry sliding wear behavior of the produced nanocomposites were studied by XRD, FESEM, OM, density measurement, hardness measurement and pin-on-disk wearing test techniques. Findings revealed that 6 h of concurrent milling produced optimal porosity and hardness. While increasing GNSs content led to decreased density, addition of 0.5 vol% of GNSs improved the microhardness by up to 105 % as compared to that of the reference sample. Analysis of the fracture surfaces indicated diminishing of the composite's ductility by graphene addition. The nanocomposite containing 0.5 vol% of GNSs demonstrated superior wear resistance (up to 38 % improvement) under low loads and distances, whereas 1 vol% GNSs addition enhanced tribological performance (up to 33 % improvement) at higher loads and distances. These results attributed to formation of a protective tribo-layer that provided insights into the underlying wear mechanisms.