Extrusion and rarefaction of lubricant in boundary layer is the key processes of adhesive wear of highly loaded tribocontacts

Abstract

A comprehensive analysis of the Adhesion-Deformation, Elasto-hydrodynamic and Hydrodynamic friction models is presented, which describe different modes of lubrication in accordance with the Stribeck curve. The main provisions of these models are considered in conjunction with the Langmuir-BET theory of adsorption and Hertz's elastic-deformation theory of curvilinear contacts. It is shown that the revealed contradictions require their resolution, and the discovered multiple effects need a scientifically based interpretation. It is proposed to develop a more generalized model of friction and wear based on naturally occurring processes that have been hidden from direct observations for a long time. These are: Extrusion of lubricating layers in the convergent elastically deformed and Rarefaction in divergent elastically deformed regions of tribo-contacts. Understanding these processes makes it possible to predict the localization sites and causes of the occurrence of primary subsequent acts of adhesion of friction surfaces and their wear in the following cycle: “rarefaction and desorption of lubricating layers, which leads to deformation destruction of oxide films and adhesion of juvenile surface areas, after which to tearing of a fragment material from the bearing and the neoplasm of the protrusion on the shaft - in the divergent elastically deformed areas of the contact. Then microcutting by this fragment of the bearing surface occurs with the release of the wear product in the convergent elastically deformed region, which accordingly leads to a change in the actual geometry and tension of the tribo-contact. Further, in other areas of the renewed contact, adhesive interaction occurs in other divergent areas according to the same mechanism. A deep understanding of the reasons for the desorption of lubricating layers will make it possible to develop and apply new highly efficient technological and material science methods in order to increase the resource of highly loaded tribo-systems of machines and mechanisms.