The Enhanced Lubrication of Water-Based Cutting Fluid by Functionalized GO

Abstract

Water-based cutting fluid (WCF) is more and more widely used in metal processing to meet the requirements for advanced manufacturing nowadays. However, the utilization of WCF is disputed for low wettability, which causes unstable lubrication. A new type of graphene oxide (GO)-based Pickering emulsion was developed as WCF due to the superior performance of GO in lubrication. Functionalized GOs (fGOs), including pristine GO, edge-functionalized GO (e-GO), and basalplane-functionalized GO (b-GO), were used as Pickering particles to prepare WCFs with three kinds of commercial cutting fluids. Results showed that the prepared WCFs were uniform and stable, in which the emulsion-e-GO exhibited the most significant enhancement to the friction-reducing, tapping torque-reducing, and extreme pressure performances. Compared with the base emulsions, the coefficient of friction and tapping torque were, respectively, decreased by 20% and 9%, and the last nonseizure load increased by 33%. Meanwhile, the emulsion-GO showed the best anti-wear property, and the wear volume could be decreased by 78.5% compared with the based emulsions. The lubrication mechanism was analyzed by X-ray absorption near edge structure (XANES), which showed that the addition of fGOs generated effective films to enhance the lubrication performances of WCFs. The superior performance of emulsion-e-GO could be attributed to the formation of compact, well-ordered, and thick lubrication films. And the faster built-up speed of lubrication films for emulsion-GO strengthened the anti-wear property.