PHYSICAL-CHEMICAL FACTORS EFFECT ON THE STRUCTURE AND PROPERTIES OF METALS UNDER CONDITIONS OF CONTACT DEFORMATION DURING FRICTION IN A SURFACE-ACTIVE LUBRICATING MEDIUM

Based on the concepts of the physical-chemical mechanics of contact interaction, a materials science analysis of these factors effect on the structure and wear resistance of an antifriction alloy under friction in surface-active lubricating media has been carried out. Tests of the bronze BrA5 − steel 45 friction pair were carried out on a reversible sliding friction machine under conditions corresponding to the operating modes of heavily loaded friction units. The role of physical-chemical factors related to the surface activity of the medium was revealed using an experimentally obtained set of macroscopic integral criteria (phenomenal indicators of friction and wear) and microscopic (microstructural) criteria (physical broadening of X-ray lines, the period of the crystal lattice, the elemental composition of the surface layer of the material of the contact deformation zone), determined using the X-ray diffraction method. It is shown that the formation of a wear-resistant structural state of a material in a surface-active lubricating medium is based on two structure-forming processes. The first one is connected with the formation of a stationary macroscopic diffusion flow of atoms of alloying elements and their transition into a lubricating medium, which leads to the creation of a surface plasticized layer, and the second process is a decrease in the density of dislocations in the material of the deformation zone, which indicates the effect of plasticizing the material (reducing its yield point stress). As a result of these processes, the material of the contact zone differs significantly from the initial one in terms of stress state, microstructure, and mechanical properties. The use of lubricants containing surfactants in tribounits contributes to the formation of a wear-resistant structure in the antifriction material.

friction, wear, metals, lubricants, surfactants, phase transformations, contact deformation, structure