Cobalt phosphate octahydrates nanoflowers as oil-base additives for enhanced tribological performance

Recently, nanomaterial lubricant additives have attracted the attention of tribologists. Herein, a novel cobalt phosphate octahydrates (CoP) nanoflower was synthesized, and as an oil-base additive, CoP exhibited extraordinary tribological performance for titanium alloy. Compared with the pure PAO8, the friction coefficient (COF) and wear rate (WR) has been reduced by 69.77% and 99.27% at a concentration of 10 wt% CoP. Besides, SEM, EDS, and XPS characterization confirmed that CoP could fill and repair the surface of titanium alloy to make the worn surface smoother, and be deposited on the surface to form a deposition layer to protect the titanium alloy from severe wear. The low shear force between CoP nanosheets in the deposition layer promotes lubrication, achieving low COF.