A proposal for a fretting wear criterion for coated systems with complete contact based on accumulated friction energy density

This paper presents the results of basic studies that investigate fretting behaviour in different steel-pairing coatings. The experiments enabled the identification of the variation in the temporal and tribological behaviour of each pairing as a result of the chosen coating. The experiments were performed on a test bench for the determination of friction coefficients with a standardised torsion test. Using flat annular contact surfaces that were pressed together under a pressure of 25 or 50 MPa, the tested samples were alternatingly loaded with twisting angle amplitudes of 0.23° and 0.5° (or 46 and 100 μm slip, respectively). This technique enabled the recording of optical damage (fretting, etc.) and strength-affecting mechanisms (damage of the substrate material). The results were evaluated using an appropriate damage criterion, thereby identifying the accumulated dissipated friction energy as a fail-related physical quantity.