Anodizing by Electrochemical Oxidation (ECO) of the Laser Powder Bed Fusion-processed A357 aluminium alloy: microstructural characterization and dry sliding behaviour

Considering the increasing interest for Al alloys in the packaging industry, where component lightweighting allows higher process efficiency, as well as the increasing use of additively manufactured parts, which may not show a satisfactory tribological behaviour in the as-built condition, anodising by Electrochemical Oxidation (ECO) and Plasma Electrolytic Oxidation (PEO) was applied to as-built A357 (AlSi7Mg0.6) produced by Laser Powder Bed Fusion (LPBF). ECO allowed to compensate surface and surface-connected defects in LPBF A357 and produced a thicker, less-defective anodic oxide than PEO, providing higher wear resistance whilst maintaining a lower Coefficient of Friction (COF) in dry sliding tests against 100Cr6 steel. Polishing before ECO only resulted in negligible friction and wear improvements, even if it improved the compactness of the anodic oxide.