Tribological behavior and mechanism of well-dispersed and interface adhesion-enhanced graphene oxide based additive for lubricant oil

Although incorporating modified graphene oxide (GO) into base oil can significantly boost the lubrication properties, existing modification strategies inevitably introduce halogen ions that are harmful to the metal at the friction interface. In this work, long-alkyl chains are grafted onto the surface of GO through electrostatic interactions between GO and cetyltrimethylammonium hydroxide (CTAOH), improving the dispersion stability of GO in base oil. Subsequently, polyisobutylsuccinimide (PIBSI, T154) further is utilized to enhance the interfacial adhesion between CTAOH-GO and the tribological interface. The combination of surface modification of CTAOH and PIBSI dispersion greatly reduces the van der Waals forces between the CTAOH-GO nanosheets, resulting in the CTAOH-GO/T154 additive can be stably dispersed in 500 N base oil for more than 200 days. When the addition amount of GO is 0.075 wt% and the ratio of CTAOH-GO to T154 is 1:5, CTAOH-GO/T154 additive realizes the reduction of the average friction coefficient and the average wear scar diameter by 46.3 % and 30.6 % at 392 N, compared with pure 500 N base oil. Mechanism analysis exhibits that the excellent dispersion of CTAOH-GO/T154 and quick formation of tribo-film facilitate enhanced lubrication performance. Therefore, this work proposes an effective strategy to fabricate the GO-based additive for lubricating oil.