hBN/TiO2 water-based nanolubricants: a solution for stick–slip mitigation in tribological applications†

In this study, the stick–slip behaviour of synthesised water-based nanolubricants was investigated via an Rtec ball-on-disk tribometer. By varying the lubricating conditions, including the concentration of hBN/TiO₂ as nanoadditives, the tribological properties and lubrication mechanisms were analysed, especially the stick–slip phenomenon. Compared with dry and wet conditions, the hBN/TiO₂ nanolubricant presented better efficiency in mitigating stick–slip and achieving friction stability. The relationship between anti-stick–slip properties and lubrication assisted in the selection of high-performance water-based nanoadditives. At a concentration of 0.5 wt% hBN/TiO₂, the nanolubricant achieved the lowest average coefficient of friction (COF) of up to 78% compared to that under dry conditions. Additionally, the 0.5 wt% hBN/TiO₂ nanolubricant showed an excellent anti-stick–slip effect, with the overall stick–slip phenomenon and threshold speed reduced by 77% and 72%, respectively, compared with those under dry conditions. Moreover, the findings indicate that the anti-stick–slip effect under wet conditions is superior to that under dry conditions. The mechanism of hBN/TiO₂ nanoadditives in inhibiting stick–slip behaviour involves trapping wear debris and forming uniform tribofilms. It can be predicted that an optimal concentration of hBN/TiO₂ (0.5 wt%) can eliminate the stick–slip phenomenon and effectively improve the friction state of the sliding interface.