Specific Features of Wear of Oil-Scraper Piston Rings with Tin Coatings in Bench Tests for Friction and Wear

We study the process of wear of commercial oil-scraper piston rings of a D100 locomotive diesel generator in a reciprocating friction machine simulating their operating conditions. The degree of wear of these rings is determined by their weight and the increase in the working surface of a ring for different sliding speeds. We also evaluate the changes in their microhardness prior to and after tests. The character of structural changes of the friction surface for different parameters of testing is established by the method of electron-probe microanalysis. It is shown that the run-in tin coating is absent on the leading edges of the rings, where the characteristic friction bands are formed with the appearance of a graphite network of the substrate. A specific feature of structuring of the inclined surface is established in the area, where this surface is adjacent to the working collar. In order to increase the durability of these rings in operation, it is recommended to deposit ion-plasma nanocoatings with additional quality control and guarantee the relaxation of residual stresses.