Friction and Wear Properties of Spherical Methyl Silicone Resin as an Additive in Polyethylene Glycol Base Oil

This study investigates spherical methyl silicone resin, a potentially environmentally friendly additive free of sulfur, phosphorus, and chlorine, as a lubricant additive in polyethylene glycol 200 (PEG 200) base oils. We evaluated concentration-response characteristics and tribological performance across PEG base oils containing 0.01–0.05 wt% resin. Tribological testing was conducted with a four-ball wear tester at 98 N and 1450 rpm for 30 min. All tested concentrations demonstrated excellent friction-reduction and anti-wear performance, with an optimal efficacy observed at 0.02 wt%. Surface characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. This friction-reducing and anti-wear performance is attributed to the formation of silicon-oxygen species and graphene-like carbon structures, thereby effectively suppressing direct surface contact and mitigating wear. Consequently, spherical methyl silicone resin demonstrates considerable potential as a green lubricant additive for bearing steel applications.