Mechanical and tribological performance of ion-beam deposited diamond-like carbon on polymers

Ion-beam deposited diamond-like carbon (DLC) is an attractive coating material because of its combination of low friction, high hardness and chemical inertness. A nitrogen ion source is used, both to modify the substrate surface and to crack a low vapour pressure oil which is evaporated and condensed onto the substrate surface. Owing to the low deposition temperature—components never exceed 80 °C during the coating process—and the ability to harden and densify the substrate surface in the same process, such DLC coatings are of particular importance for engineering polymers. In this study DLC coatings (approximately 1 μm thick) have been applied to a range of commercially available polymer substrates. Depositions have been carried out with and without surface modification of the polymer by ion bombardment prior to DLC coating. The assessment of the mechanical properties of these coatings is reported, including adhesion, wear resistance and fracture toughness.