Effects of surface preparation on the corrosion resistance of TSA anodized aluminum alloys

Abstract

This study examines the impact of surface preparation on the corrosion resistance of anodized AA2198-T851 aluminum alloy. Two pretreatment methods were employed: (i) alkaline degreasing in 10 wt.% NaOH at 60 °C followed by de-smutting in 30 vol.% HNO3, and (ii) etching in an oxidizing acidic solution (K3 Smutt-Go, 7 V, 20 °C) intended to remove copper-containing intermetallic particles. Surface preparation methods were analyzed using SEM, FEG-SEM, SEM-EDS, and XPS. Corrosion resistance was tested through EIS, and NSST. All electrochemical tests were conducted in 0.1 mol L−1 NaCl solution, and the NSST followed ASTM B117-16. The findings show that removing intermetallic particles greatly improves the corrosion resistance of TSA-anodized AA2198-T851. Among the tested conditions, the etched samples exhibited superior performance, showing no observable corrosion after 336 hours of salt spray exposure, confirming their enhanced corrosion resistance.