LAUSR

Abstract Nitrile-butadiene rubber (NBR) exhibits the high friction and wear as a dynamic seal sliding against the engineering materials. To improve its friction and wear resistance, diamond-like carbon (DLC) films are devised to deposit on NBR rubber via plasma-enhanced chemical vapor deposition (PECVD). Prior to the deposition, Ar plasma pretreatment of NBR substrate is carried out, and the influence of Ar plasma pretreatment time on the adhesion and tribological behavior of DLC coated NBR is studied systematically. The typical micrometer- scale patches divided by random cracks are always observed on the DLC film coated NBR rubber, and the size of the patches increases with increasing pretreatment time. Moreover, the hardness of the films decreases monotonously as the increase of the pretreatment time, which means that Ar plasma pretreatment has an effect on the properties of the films. It is worth to mention that the adhesion strength between DLC films and rubber first increases and then decreases along with the change of Ar plasma pretreatment time. The tribotests results show that the DLC film with 30 min pretreatment exhibits the lowest friction coefficient of 0.2 (compared to ~0.8 of uncoated NBR) during 12,000 laps. The wear life of the superior DLC/NBR is studied further, and it is functional after 120,000 laps tribotests under the normal load of 10 N. Therefore, the DLC film can be considered as a promising candidate coating for the enhancement of wear resistance of rubbers.