Tribological behaviours of black phosphorus/MoS2 composites as water-based lubrication additives

In this investigation, a self-assembly method was used to fabricate black phosphorus (BP)/MoS2 composites as water-based lubrication additives. The tribological behaviours of the lubrication additives for GCr15 steel ball/TC4 titanium alloy disk contact under different mass ratios, loads and rotational speeds were also investigated. The experimental results showed that 0.01 wt.% BP and 0.04 wt.% MoS2 as water-based lubrication additive have the best the synergistic lubrication effect. Compared with pure water, coefficient of friction (COF) and wear rate of the lubrication additive at the test conditions of 8 N and 150 r/min were reduced by 32.6% and 68.8%, respectively. As the loads increased, the COFs and wear rates of all the lubricants including pure water, BP as water-based lubrication additive (BP-WL), MoS2 as water-based lubrication additive (MS-WL) and BP/MoS2 composites as water-based lubrication additive (BM-WL) were all reduced. As the rational speeds increased from 100 to 250 r/min, all the lubricants were firstly decreased and then increased. Based on tribological tests and wear surface analysis, the lubrication mechanism of BM-WL is proposed. The interlaminar shear and the adsorption of BP/MoS2 composites on the wear surface of the friction pairs are the key to reducing COFs sand wear rates. In addition, the tribo-chemical reaction films consists of FeO/Fe2O3, Al2O3 and TiO2 were formed during the friction process, which can effectively protect the surface of the titanium alloy/steel contact from wear.