Selecting solid lubricant coatings under fretting conditions

Based on the investigation of several bonded solid lubricant coatings under fretting contact, a systemic approach was put forward to help the coating selection for fretting conditions. Some simple techniques, like ball cratering, scratch test and nanoindentation test, can be used to pre-select the coatings, because the fretting endurance of the coatings was found to be closely related to their behaviors in ball cratering and scratch tests. The fretting performance of the candidate coatings was further compared by a dissipated energy approach, where the lifetime of each coating can be fitted by one master curve whatever the contact pressure and the displacement amplitude. The comparison of the master curves for different coatings can help the coating selection. The master curve of a given coating may also be used to predict the coating lifetime only by knowing the initial energy dissipated in the contact. Finally, a straightforward and synthetic evaluation and comparison of the coatings from several aspects can be realized by a polar diagram.