Aqueous medium improved tribological properties of 1,2,3-TrI [Cis-9-hexadecenoyl] for titanium alloy: Insights in virtue of molecular simulations

1,2,3-TrI [Cis-9-Hexadecenoyl](GTM) is a common oiliness additive. In this paper, the anti-wear property of GTM was found poor when it was directly used as lubricating oil for titanium alloy. However, when it was added to water and made into O/W emulsion, it could play an effective role. The wear volume of titanium alloy sample lubricated by the emulsion was reduced by 75% compared to that lubricated by pure oil. It was difficult to fully uncover the underlying mechanism of these phenomena by experimental methods alone. With the help of molecular simulation method, the changes of GTM in chemical activity and adsorption capacity caused by water medium were revealed on atomic scale. The adsorption energies between GTM and titanium alloy under different temperature were quantitatively calculated. The superior anti-wear performance of the emulsions was related to following three aspects: (1) Water medium enhanced the adsorption capacity of GTM; (2) Water medium changed the composition of lubrication film; (3) The adsorption film in the water medium was less affected by temperature. Based on above results, an approach to predict tribological properties of oiliness additive was proposed. Using this method, the lubrication effects of several oiliness additives were successfully predicted.