Mechanical properties of ion-beam deposited diamond-like carbon on polymers

Abstract

Ion-beam deposited diamond-like carbon (DLC) is an attractive coating material owing to its combination of low friction, high hardness, and chemical inertness. A 40–80 keV nitrogen bucket 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. The technique is of special interest owing to the low deposition temperature—components never exceed 80°C during the coating process. Further, the ability to harden and densify the substrate surface in the same process is of particular importance for engineering polymers. Thick DLC coatings (approximately 1 μm) have been applied to a range of polymers, with and without surface modification. The assessment of the mechanical properties of these coatings is reported, including surface roughness, friction hardness, and adhesion. Comparisons are made with untreated polymers and those ion implanted with nitrogen at a range of doses.