Comparative performance of Cathodic Electrodeposition, powder, and zinc flake organic coatings on Nano‑Treated AA1050, AA5005, and AA7075 Aluminum Alloys

Abstract

This study presents a comparative assessment of organic coating systems applied to nano-treated 1050, 5005, and 7075 aluminum alloys, aiming to enhance corrosion resistance in high-performance industrial environments. The alloys were subjected to a zirconium oxide-based nano pretreatment with varying activation durations (60–90 s) and coating times (6–8 min). Subsequently, three distinct organic coating methods were applied: cathodic electrodeposition (CED), powder coating, and zinc flake coating. The performance of the coatings was evaluated using cross-cut adhesion tests, cyclic corrosion tests (EN ISO 11997-1 Cycle B, Renault 47-01-000-E), and copper-accelerated acetic acid salt spray (CASS) tests (DIN 50 021). Coating thicknesses were determined via scanning electron microscopy (SEM). The findings revealed that zinc flake coatings failed the adhesion tests, whereas CED and powder coatings demonstrated high performance under optimized pretreatment conditions (90 s activation, 8 min nano coating). Notably, the 7075-alloy exhibited superior compatibility across multiple tests, achieving the highest corrosion resistance with CED coatings. These results offer a practical roadmap for selecting environmentally friendly and high-performance coating strategies for aluminum alloys intended for use in harsh service conditions