Influence of the nanoporous alumina layer characteristics on the tribological behaviour of EN AW-6082 aluminum alloy treated by an innovative hard anodizing process

The present work concerns the tribological characterization of an EN AW-6082 wrought aluminum alloy treated according to an innovative anodic oxidation process in which the nanoporous anodic oxide layer was sealed with Ag+ ions (G.H.A.R technology). The tribological tests in dry conditions were conducted in ball-on-disk configuration (standard ASTM G99): the disc, made of the selected aluminum alloy, was treated with G.H.A.R and subjected to the standard process of hot fixing with Ag+ ions. Spherical-headed pins, used as counterpart material and made of the same aluminum alloy, were treated with G.H.A.R using n. 3 different conditions of anodic oxidation and final heat sealing. Samples treated with a traditional hard anodizing treatment were also taken in account to compare the wear properties of the different surfaces. Firstly, the influence of a preliminary polishing procedure before anodizing treatment on the anodic oxide characteristics was evaluated together with the tribological behavior in wear tests complying ASTM G99 standard. In the second part of the work, tribological tests were conducted at linear speeds equal to 0.05 and 0.10 m/s and a load of 5 N to compare the coefficient of friction (COF) and specific wear rates (WR). All wear tests were performed in triplicate. The results allowed to highlight a substantial dependence of the COF and of the surface duration on the sliding speed for the couplings examined. © 2023 Associazione Italiana di Metallurgia. All rights reserved.