Frictional and mechanical behaviour of graphene/UHMWPE composite coatings

Bulk-modified ultra-high molecular weight polyethylene (UHMWPE) is a biomaterial currently used for joint replacements. As an alternative, we assess the frictional behaviour of coatings based on graphene/UHMWPE composites and sprayed graphene, which maintain the high performance of the UHMWPE matrix. Composite coatings were prepared with 0-4.6 wt% of graphene nanoplatelets (GNP) and 1-2 layered graphene (2LG). Mechanical properties of the coatings were measured by nanoidentation and friction coefficients were determined with a ball-on-disk tribometer. The results indicate that GNP present better tribological behaviour than 2LG. Spray-coated GNP shows the lowest friction, 40% less than UHMWPE, although with low adhesion. An increase of 10% in elastic modulus and 30% in hardness was measured for composite coatings with 2-5 wt% graphene.