Probing the tribological behaviors of diamond-like carbon film in water-based drilling fluid environment by varying normal loads

Abstract

This paper investigates the friction behavior and mechanism of diamond-like carbon (DLC) film and 26CrMo alloy steel under different loads in water-based drilling fluid environment. The results show that the coefficient friction and wear degree of DLC film in water-based drilling fluid environment are significantly lower than that of 26CrMo alloy steel under both low and high load. Raman, SEM and other test results suggest that the graphitization degree of worn DLC surface and the transfer layer on the surface of friction pair will increase with the increase of load. DLC film shows superior lubrication and wear resistance in water-based drilling fluid environment. Meanwhile, further investigation suggests that the friction and wear behavior of DLC film in water-based drilling fluid environment is also affected by the synergy of rolling effect, filling effect and polishing effect. Moreover, the barite particles wrapped in graphene dust will produce a low-friction synergy at the friction interface even if the DLC film is worn through. The relevant research results not only help to enrich the basic theory of lubrication and wear resistance technology of DLC film, but also help to promote the practical engineering application of DLC film in oil and gas environment. • DLC film exhibits lower COF and wear in water-based drilling fluid environment. • Graphitization of DLC film and transfer layer increase with the increase of load. • Friction behaviors are affected by rolling effect, filling effect and polishing effect.