Tribological Properties of a Semi-Liquid Lubricant with Surfactant Additives

— The properties of a semi-liquid lubricant (Lb) with additives were tested using a KT-2 oil testing machine; its stability and influence on the ‘wheel flange—rail’ friction pair was assessed. The analysis is based on laboratory wear tests of locomotive wheel flanges. Investigation of lubricants with additives showed their low colloidal stability, the highest oil release being observed with the addition of sulfo compounds and phospho additives. The thermal stability of lubricants with additives shows that at approximately 220°C the lubricants melt completely and turn into a liquid state. After conducting tribological tests on a KT-2 oil testing machine of a lubricant with a hydroquinone additive, white crystals formed on the surface of the facility. The dependence of the friction coefficient on the test temperature of the studied lubricant with additives was obtained. X-ray fluorescence analysis of the locomotive wheel flange surface showed a change in the concentration of chromium and manganese in the surface layer of the sample before and after bench tests, which may indicate the formation of a stable transfer layer providing good tribological properties. Empirical coefficients were obtained to determine the wear rate of the locomotive wheel flange for the studied additives.