Improved Corrosion Protection of Aluminum Alloys by System Approach Interface Engineering: Part 1—Alclad 2024-T3 Available to Purchase

This study investigated the development of chromate-free corrosion protection systems for Alclad 2024-T3 (UNS A92024) aluminum alloy ([2A]) based on the concept of system approach interface engineering (SAIE) by chemical and plasma techniques. Anode magnetron enhanced direct current (DC) cathodic plasmas were used to treat [2A] surface and to create interface engineered systems of cathodic electrocoat (E-coat)/plasma polymer/plasma-treated [2A]. Plasma polymer coatings provided not only a corrosion-resistant layer on [2A] surface but also an excellent adhesion base for subsequent cathodic E-coat. When tested by sulfur dioxide (SO₂) and Prohesion salt spray tests, these plasma-modified systems showed excellent corrosion protection characteristics. The corrosion test results of SO₂ and Prohesion salt spray tests showed that most of these plasma polymer-coated systems outperformed or performed comparably to the two types of controls used in this study (i.e., chromate conversion-coated and E-coated or chromated primer [Deft 44-GN-36] painted [2A] panels). The sample surface preparation effect on the corrosion performance of these plasma interface engineered systems also was studied, and x-ray photoelectron spectroscopy (XPS) was used to monitor the surface composition changes on [2A] surfaces.