Comparative measurement of super-lubricity behavior elucidated by HEMM gear oil based nanolubricants followed by field training on FZG test rig

Abstract

This study investigates the lubricity characteristics of two nanoparticles, namely Graphene and aluminum oxide (Al₂O₃), when used as nano-dispersants in industrial graded gear oil for heavy earth moving machinery (HEMM). Dual step approach was followed to synthesize the Nanolubricants. The stability of the samples was studied by different methods for better comprehension and further evaluation. The thermophysical, physicochemical and surface properties of the nanolubricants were measured following acceptable standards. The tribological characteristics of the samples were also evaluated experimentally. All the nanolubricant samples showed stable colloidal suspension. The addition of Graphene and Al₂O₃ to gear oil resulted in a 21% and 25% reduction in the frictional force respectively. The metrics for estimating extreme pressure properties were recorded from a four-ball tester. The Graphene based nanolubricants showed a higher improvement in non-seizure load and weld load respectively, over Al₂O₃ based nanolubricants. Also, Graphene exhibited an increase in seizure pressure (p_oz) of 34.44%, whereas the same effect with Al₂O₃ showed 21.70% increment. The mechanics for improved tribological behavior with Graphene involve a load bearing effect whereas Al₂O₃ exhibits a ball bearing dominance when exposed to extreme pressure conditions. The nanolubricants significantly reduced motor torque and oil temperature when assessed on real-time test rig.