Investigation of phase and structural changes in the surface layers of friction pair materials

Abstract

1. During the operation of a heavily-stressed friction pair, secondary structures are formed in the surface layers of the pair materials. The appearance of these structures is linked with the effect exerted on the surface layers by high pulsating temperatures and local pressures, which are responsible for the setting up of rapidly propagating thermal and physicochemical processes. 2. The character of formation of the secondary structures and their phase compositions will vary depending on the chemical composition of the starting structure and the physicochemical properties of both pair materials. The properties of these structures differ substantially from those of the starting structures, and largely determine the service characteristics of a friction pair. Because of their high hardness and brittleness, they initiate the formation of microcracks and zones of deep local wear. 3. The surface layers of a friction pair are subjected to deep plastic strains, which promote structural transformations during friction. 4. The service properties of a friction pair must presumably depend on the character of interaction between the structural constituents of the surface film produced during friction, as well as on the physicomechanical and other properties of these secondary structures. 5. To determine in greater detail the nature of the secondary structures and the kinetics of their formation, it will be necessary to resort to phase, x-ray structural, and layer-by-layer spectral analyses.