Electroless Deposition of Ni-P Coatings on HNBR for Low Friction Rubber Seals

Abstract

This paper reports a simple and cost-effective procedure to coat hydrogenated nitrile butadiene rubber (HNBR) with a well-adherent Ni-P film by using the electroless plating method. A HNBR surface functionalization process was first optimized, creating an interpenetrating network with polyvinylpyrrolidone (PVP). Silver nanoparticles were deposited on PVP and acted as catalysts for the Ni-P film deposition, eliminating the expensive tin-palladium sensitization/activation step. A homogeneous, low phosphorous Ni-P film was obtained after 60–120 min of plating in an alkaline bath, with an average thickness of 3 to 10 µm, respectively. The PVP internetwork played an important role on the strong adhesion of the film, 1.0 ± 0.5 MPa. The tribological behavior of Ni-P-plated HNBR samples was studied for 1, 5 and 10 N applied loads under dry sliding on a pin-on-disc configuration and the coefficient of friction (CoF) was reduced by ~30–49%, compared to uncoated HNBR (loads 1–5N). Based on these results, Ni-P-coated rubber can be regarded as a novel solution for enhancement of the tribological behavior of dynamic seals; it can be regarded as a means to avoid machinery failure. This method offers an alternative to the diamond-like carbon (DLC) coatings.