Fretting wear behaviors of acrylonitrile-butadiene rubber (NBR) against diamond-like carbon and graphene coatings

Abstract

The study focuses on understanding how to govern the fretting wear behaviors under dry lubricated contact to find out the keys to develop new coatings for rubber seal applications. Fretting wear behaviors of acrylonitrile-butadiene rubber (NBR) against steel substrate, diamond-like carbon, and graphene coatings were comparatively investigated under dry conditions. Dynamic analyses were performed in combination with examinations through scanning electron microscopy (SEM), 3D surface profilometry, and X-ray photoelectron spectroscopy (XPS). Experimental results show that, there was significant difference between the fretting running regime for graphene coating and the fretting running regimes for diamond-like carbon (DLC) coating and steel substrate; the mixed fretting regime (MFR) disappeared and the boundary between the partial slip regime (PSR) and the slip regime (SR) shifted to the direction of smaller amplitude displacement in running condition fretting map (RCFM). Moreover, it had excellent anti-friction and wear-resistant performances under fretting condition. However, the fretting running behaviors of the DLC coating are similar to those of the steel substrate, so the DLC coating could not migrate the fretting running regimes effectively. The damage on all the tribopairs in partial slip regime was very slight and the adhesion was the main damage mechanism for the DLC coating and the steel substrate in the MFR and SR. The sticky layers on the worn surface played an important role. For the graphene coating, no obvious damage could be observed on the tribopairs. Therefore, the graphene coating exhibited widely potential applications for alleviating fretting wear.