Effect of Oil‐Soluble Graphene on the Tribological and Rheological Properties of Magnetorheological Fluids

Abstract

Magnetorheological fluid (MRF) is a widely utilized intelligent material that faces the in‐use thickening (IUT) problem caused by wear. As commonly being used polar antiwear agents aggravate the sedimentation of MRF, a new method to improve the tribological properties of MRF using nonpolar oil‐soluble graphene rather than polar additives is proposed. Orthogonal and control experiments conducted with a four‐ball machine show that oil‐soluble graphene greatly improves the antiwear performance of MRF. More specifically, the MRF with oil‐soluble graphene reduces wear volume up to about 90% compared with all control experiments, including blank samples without any additives, the samples with the surfactant but without graphene, and the ones with the commercial antiwear agent ZDDP. The results also indicate that both lubricant and MRF get the best antiwear effect when graphene concentration in the base oil is 2 mg ml−1. This implies that oil‐soluble graphene improves the tribological properties of the systems primarily by enhancing the pressure‐bearing capacity of the carrier fluid. Moreover, oleophilic graphene increases the magnetorheological effect of MRF and reduces its off‐state viscosity by about 4% through isolating particles and filling gaps. In summary, the proposed method can solve the IUT problem of MRF along with ensuring its performance.

The effect of microparticles/nanoparticles surface modification on the magnetorheological fluid properties: A review

“…In addition, Carlson (2002) demonstrated that fluid viscosity increases in the absence of a magnetic field as the number of cycles increases in using MRF in their applications. Also, Numerous studies have made progress on tribological features such as the wear characteristics, tribological performance, and coefficient of friction of MR fluids (Lee et al, 2011; Li et al, 2022; Lv et al, 2022; Sohn et al, 2009; Wong et al, 2001).…”

Study on the tribological and rheological properties of magnetorheological fluids based on different base oils

“…Li [15] obtained the formula of MRF with excellent frictional properties through experimental research on six different types and different mass fractions of lubricating additives. Lv [16] proposed a new method to improve the tribological properties of MRF using nonpolar oil-soluble graphene, and the results showed that MRF get the best anti-wear effect when graphene concentration in the base oil is 2 mg/ml. Thakur [17] prepared a new kind of MRF with graphite flake, and the results showed that the graphite flake can be used as lubricants to reduce wear.…”