Diamond-like carbon graphene nanoplatelet nanocomposites for lubricated environments

The tribological behaviour of diamond-like carbon (DLC) and graphene nanoplatelets (GNP) nanocomposite has not been previously explored in a lubricated environment, with some previous studies reporting only on graphene materials on the surface of the DLC. In this study DLC-GNP nanocomposite films with various GNP coverages were synthesised by a 3 step process: spin coating a GNP suspension, heat treatment, and DLC deposition. In this study, the effect of the GNP coverage on the mechanical properties, and tribological response of the DLC-GNP nanocomposite film were studied at elevated temperatures against a cast iron pin in a base-oil lubricated environment. The study shows decrease in friction and wear of the DLC-GNP nanocomposites as the GNP coverage increased, with the lowest friction (COF ∼0.03) and wear (∼1.6 × 10−19 m3/Nm−1) achieved with a 4.5% coverage. This study reports the addition of GNP into the DLC matrix reduced both friction and wear by creating a highly graphitic transfer film on the counter-body, but for higher GNP coverages agglomeration during the spin coating of GNP islands were recorded, leading to removal of the GNP during sliding wear negating the friction reduction effect of the GNP.