Agali Guliyev, Aynur Sharifova, Begali Bektemirov
The analysis of experimental research results shows that the most effective filler is the material which, during its reduction, forms a new and stable surface layer protected by a strong adsorption film on the friction surface. In this case, the friction unit operates under the conditions of selective transfer, and a tribologically favorable protective layer is formed on the surface. It was observed that the material referred to as a multilayer lubricant consists of a copper alloy, copper-coated particles — Cu, Cu-C, Cu+(Cu-C) — and an adsorbed layer of plastic lubricating material. The spaces between these layers are filled with a mixture of graphite and lubricating materials. As a result, a decrease in the wear intensity of copper alloy specimens occurs, and a protective coating with a complex structure may form on the surface of the steel specimen. For the first time, CT (HK50) grease was used in this study, taking into account the limited availability of industrial lubricants capable of providing the selective transfer effect. The physical and mechanical properties required for the investigation were determined. One of the main distinguishing features of this research is the first-time application of grease lubricants containing Cu–C and Cu + (Cu–C) fillers. It was found that the incorporation of copper-coated graphite into the grease, together with the grease composition, including the dispersion medium, dispersed phase (solid hydrocarbon), and various fillers, contributes to the formation of the selective transfer layer. In addition, the lubrication mechanism of graphite is associated with the boundary lubrication model. The dependence of the friction torque on time under both elastic and plastic deformation conditions was investigated. The microstructure of the passivating layer formed on the friction surface under these conditions was also determined. Under such conditions, lubrication increases the wear resistance of the friction pair, improves its antifriction properties, and enhances the load-bearing capacity of the friction unit. Thus, the mechanism of action of the lubricating material is explained by the formation of a soft coating on the friction surface during operation as a result of new tribochemical transformations occurring in the lubricant. This coating ensures surface protection, increases wear resistance, and contributes to the reduction of friction force.