Black Phosphorus Quantum Dots in Aqueous Environments as Lubricants

Frictional losses are one of themain factors affectingthe reliabilityand service life of mechanical components. In this article, blackphosphorus quantum dots (BPQDs) were prepared using the sonication exfoliation approach and investigatedas aqueous solution lubrication. The prepared BPQDs with average diametersof 3.1 & PLUSMN; 0.6 nm were evenly distributed in pure water and exhibitedexcellent dispersion stability. Pure water and BPQDs aqueous solutionwere added at the same amount each time between the ball (GCr15 steel)and the plate (diamond-like carbon coating deposited on the surfaceof TC4 titanium alloy) to evaluate the differences in their tribologicalproperties. The addition of BPQDs to pure water resulted in a 36.5%reduction in the coefficient of friction (COF) compared to pure water.The calculated wear rates also decreased by 59.0% at the same time(10 N). The initial Hertzian contact pressure ranged from 1000 to1300 MPa. Additionally, the superior friction reduction and antiwearperformance of the BPQD aqueous solution are principally attributableto the tribofilm that forms on the worn surface as well as its adsorptionand rolling effect. This work aims to provide some meaningful guidelinesfor tribologists on the future study of BPQDs with low friction andlow wear in the field of solid-liquid composite lubricationsystems.