Deposition and characterization of hydrogenated diamond-like carbon thin films on rubber seals

Thin films of hydrogenated diamond-like carbon (DLC) have been deposited on hydrogenated nitrile butadiene rubber (HNBR) for reduction of friction and enhancement of wear resistance of dynamic rubber seals. The wax removal and pre-deposition plasma treatment of HNBR substrates are proven to be crucial and effective for the improvement of film performance due to enhanced adhesion. The crack network formed during deposition enhances the flexibility of DLC thin films and its density can be tuned. After being stretched to 50% strain, the 300 nm thick DLC films still adhere very well on the rubber substrates and no spallation or delamination has been observed. The optimized DLC thin film on plasma treated HNBR rubber exhibits very low coefficient of friction of 0.167 at 1 N normal load (compared to > 1 of uncoated HNBR rubber) and 0.194 at high normal load of 3 N and after being stretched to 50% strain.