Friction Behavior of Anodic Oxide Layer Coating on 2017A T4 Aluminum Alloy under Severe Friction Solicitation: The Effect of Anodizing Parameters

Abstract

This article aims to highlight the wear mechanisms and friction behavior of the 2017A T4 anodized aluminum alloy used for automotive and aerospace applications. The effect of the processing parameters on the durability of the anodized layer under high friction is studied. Scratch tests were carried out to study the level of the friction coefficient with the increase in the thickness of the oxide layer formed on the Al 2017 A (AU4G) substrate. The results of the scratch tests show that the variation in the anodization duration, which influences the thickness of the oxide layer, induces an increase in the coefficient of friction. Besides, the variations in friction coefficient with sliding distance are influenced by the changes in wear morphology and degree of oxidation. Treated surfaces with a thickness of 50 μm have the lowest friction coefficients and wear rates. Their improved wear resistance may be related to the increased bond strength compared to other anodized surfaces. The tribological damage was characterized by the detachment of debris, which increases with the increase of the duration of anodization. Upon sliding, its detachment leads to delamination of the underlying anodic aluminum oxides and subsequent abrasion of the aluminum substrate.