Correspondence Between Wear Mechanisms and Friction Response in the Time–Frequency Domain of a Metallic Pair Under Sliding Conditions

Abstract

A detailed analysis of the friction data from laboratory tests was carried out with a focus on the identification of the wear mechanisms acting on the contacting surfaces. In the past work, dynamical system theory has been successfully applied to tribosystems involving rolling pairs. However, its applicability to sliding metallic pairs is still far from being straightforward. To address this problem, a dynamic analysis in time and frequency was applied to the coefficient of friction (COF) data obtained from pin-on-disc tests of self-mated AISI-SAE 1080 steel. The tests were performed in either air or N2 atmosphere and under a series of normal loads and sliding speeds. The power spectral density (PSD) and time–frequency spectrograms were calculated from the friction data by applying a fast Fourier transform. The samples from the tests with N2 atmosphere attenuated the frequencies in the bandwidth between 8 and 10 Hz for all angular velocities, and it was validated by statistical analysis. Using a 3D profilometer, the width and depth of the wear tracks were measured, and the corresponding wear-rates were estimated. The lower wear-rates in the test with air are associated with the formation of oxides acting as a tribolayer on the contact. This study demonstrates that the wear mechanisms acting on the contacting surfaces in pin-on-disc tests can be correlated with the COF response in the frequency domain.