ZnFe2O4@C/graphene oxide nanocomposites designed for enhancing the friction reduction property of lubricants

Abstract

Improving the friction reduction property of lubricant to ensure the efficient operation of advanced heavy-duty machinery has been taken seriously. Herein, as a novel additive with a distinctive sphere-on-sheet structure, ZnFe2O4@C/graphene oxide (ZnFe2O4@C/GO) nanocomposites were designed via the response surface method to drastically enhance the friction reduction property of the polyalphaolefin oil. The particular lubrication mechanism of the ZnFe2O4@C/GO nanocomposites was simultaneously revealed. Results showed that the friction coefficient could be reduced by an order of magnitude (less than 0.05) at several frictional moments under the contact stress of 1.20 GPa when the ZnFe2O4@C/GO nanocomposites were added to polyalphaolefin oil. Specifically, the largest decrease in friction coefficient during the friction process was from 0.24 to 0.025 (approximately 90 %). According to the molecular dynamics simulations, the outstanding friction reduction property of the ZnFe2O4@C/GO nanocomposites was determined by the sliding structures with low shear force between the bent graphite in the ZnFe2O4@C microspheres and the graphene tribofilms at the friction interface. These findings reveal the application prospects of the ZnFe2O4@C/GO nanocomposites as a superior lubricant additive for advanced heavy-duty machinery in the future.