In situ synthesis of Mn_3O_4/graphene nanocomposite and its application as a lubrication additive at high temperatures

摘要

Graphene-based nanoadditives are widely used in the field of lubrication due to their two-dimensional (2D) structure and excellent mechanical properties. However, researches on the high-temperature performances and rheological properties of graphene-based lubricant are still insufficient. In this study, Mn3O4/graphene (Mn3O4#G) nanocomposite is synthesized in situ by hydrothermal method, and it is used as nanoadditive in lithium grease. When the concentration of Mn3O4#G is 0.03 wt%, the coefficient of friction (COF) and wear scar depth can be reduced by 35% and 76% (100 degrees C, 150 N), respectively. In addition, when the temperature is 120 degrees C, the grease with 0.03 wt% Mn3O4#G can still achieve stable lubrication performance. On the contrary, pure grease (P.G) has already failed to lubricate at the temperature of 80 degrees C. According to the computational fluid dynamics (CFD) results, the shear thinning phenomenon of the grease can be observed. And the central suction effect occurring in the friction area will be conducive for the nanoadditives to enter the friction contact area.