Facile method preparation of oil-soluble tungsten disulfide nanosheets and their tribological properties over a wide temperature range

Ultrathin oil-soluble tungsten disulfide nanosheets surface-capped with oleylamine (OA-capped WS 2 ) were prepared by liquid phase thermal decomposition method without any solid by-products, a facile method with potential for large-scale production. OA-capped WS 2 nanosheets exhibit good dispersibility and long-term stability in poly alpha olefin oil and significantly enhance the lubricating properties of the base oil over a wide temperature range (from 25 °C to 200 °C). This is because the surface-capped WS 2 nanosheets can be well adsorbed on friction surfaces forming a lubricating film (mainly WS 2 ) and participate in tribological chemical reaction to generate a chemical reaction film consisting of WO 3 , FeS, FeSO 4 , iron oxides , and FeOOH on the worn steel surfaces during friction process .