Load dependence of oxidative wear in metal/ceramic tribocouples in fretting environment

For a large number of non-oxide ceramic/metal as well as for non-oxide particulate reinforced composite/metal tribocouples, oxidative wear is reported to play a major role in the overall damage and material removal process. The designing of new materials with improved resistance to oxidative wear requires understanding of the combined effect of the material properties and operating parameters on the wear resistance. In this paper, an analytical model to predict the dependence of the oxidative wear volume on load and sliding velocity is presented. The model is developed using basic chemical kinetics and Hertzian contact mechanics, and is valid for the case of a stable oxide layer. Exponential dependence of wear volume on operating parameters (load, sliding velocity) is predicted in the proposed model. It has been shown to successfully explain the qualitative experimental load dependence of the wear volume for five ceramic/metal tribocouples (Al2O3/steel, WC–TiC–Co/steel, TiB2–MoSi2/steel, ASP23 steel/alumina and Ti6Al4V/alumina) that exhibit oxidative wear. The activation energy of the oxidation of metallic counter bodies under fretting conditions was also calculated using the model, which turns out to be significantly lower than in the static conditions.

► Analytical model for oxidative wear.
► Combination of chemical kinetics and Hertzian contact mechanics.
► Derivation of exponential load dependence of the oxidative wear volume.
► Validation of the model with five ceramic/metal tribocouples experiments.
► Calculation of activation energy of oxidation reaction in fretting condition.