The relationship between the electron work function and friction behavior of passive alloys under different conditions

Electron work function (EWF), adhesion and friction coefficient of three passive alloys were investigated. During dry sliding tests, surfaces having higher work functions showed larger coefficients of friction. While under oil-lubricated sliding condition, the trend was reversed. It appears that when the surface passive film was damaged, the surface broken atomic bonds became active, leading to larger friction. However, under the oil-lubricated sliding condition, the passive film was retained, resulting in a different trend. Surface adhesive forces of freshly polished surfaces and etched ones were measured using an atomic force microscope. Results of the adhesion measurement are consistent with the behaviors of the alloys observed during the friction tests. (C) 2015 Elsevier B.V. All rights reserved.