Anti-Friction Properties of Modified Graphene Oxide Lubricants for Wire Rope in a Mine Hoist

To solve the serious tribological problem between the internal steel wires of the lifting wire ropes caused by lubrication failure under harsh lifting conditions, the anti-friction properties of modified graphene oxide lubricants were studied. Firstly, octadecylamine functionalized graphene oxide (ODA-GO) and its reduced material by hydrazine hydrate (ODA-rGO) were prepared. Their chemical structure, surface morphology, interlayer spacing and defects were investigated, and their dispersibility in a wire rope lubricant named IRIS was explored. Then, the anti-wear and friction reduction properties of modified oils were evaluated by four-ball machine and the lubrication mechanism was analyzed. Finally, the effect on the friction reduction between wires of ODA-GO lubricant was analyzed. The results showed that ODA was grafted on GO surface through amidation reaction and nucleophilic substitution reaction. ODA-GO had a high grafting density of octadecyl chains with good dispersion in IRIS, while ODA-rGO showed the opposite results. However, the optimal friction reduction and anti-wear properties of ODA-rGO were better than ODA-GO. Besides, the modified graphene-based materials would be adsorbed on the contact surfaces and filled the damaged areas to reduce wear. Furthermore, the ODA-GO lubricant reduced the coefficient of friction of the wires by 10% and reduced the fatigue wear significantly.