Ultra-Low Wear and Anti-Oxidation Properties of Microcrystalline Graphite Oxide-Magnesium Silicate Hydroxide Composite Nanoadditives in the Poly-Alpha-Olefin Base Oil

Graphite-based materials and hydrothermal synthetic magnesium silicate hydroxide (MSH) had shown outstanding performances as lubricant additives. In this paper, microcrystalline graphite oxide-magnesium silicate hydroxide (MGO-MSH) composite additives using pre-oxidized MGO as one of the precursors were prepared at a mild hydration condition, and their tribological properties in poly-alpha-olefin oil (PAO 10) were demonstrated by a four-ball tester. The tribological results showed that the optimal concentration of MGO-MSH in oil was 0.3 wt% under 600 N, 600 rpm. Meanwhile, the average wear scar diameter of the ball samples tested in composite-suspending oil was reduced by 36.3% compared with that obtained by pure PAO 10. By means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectra, and X-ray photoelectron spectroscopy (XPS), it was verified that MGO was involved in the synthesis of MSH, and MSH was anchored on MGO during the hydrothermal process. In addition, it was confirmed that carbon-containing tribo-film was formed on the smooth wear region of the wear scar and was of excellent anti-oxidation wear properties.