Active Corrosion Protection by Epoxy Coating on Li2CO3-Pretreated Anodized Aluminum Alloy 2024-T3

Abstract

The fast leaching and robust barrier property of inhibitors are the basic fundamentals for the formation of active protective coatings to protect aluminum alloys. Herein, an active protective surface was developed based on an epoxy coating and an underlying lithium carbonate (Li2CO3)-treated anodized aluminum alloy 2024-T3. The morphology of the Li-LDH layer was studied to know its formation mechanism. The electrochemical studies revealed that the fast and adequate leaching of lithium led to a substantial increment of corrosion resistance of the scratched coating in 3.5 wt% NaCl from 1 to 8 days. Time of flight secondary ion mass spectroscopy (ToF-SIMS) results indicated that Li was distributed in the lateral direction and covered the scratched area. The 3D images indicated that different lithium compounds were formed and 90% of the scratched area was covered with the lithium protective layer over immersion time. A combined approach of morphology observations, electrochemical measurements, and ToF-SIMS showed the lithium protective layer offered good corrosion resistance. On the contrary, lithium provided fast and adequate leaching from the coating, demonstrating good active protection for aluminum and its alloys.

Study on the Influence of Surface Treatment Process on the Corrosion Resistance of Aluminum Alloy Profile Coating

“…At present, the most widely used treatment methods on aluminum alloy surfaces are anodizing and powder coating [1,[12][13][14]. Minhas Badar et al [15] developed an active protective coating surface using the rapid leaching and strong barrier properties of the corrosion inhibitor combined with the anodized aluminum alloy 2024-T3, and electrochemical studies showed that the rapid and sufficient leaching of lithium led to a significant improvement in the corrosion resistance of scratch coatings. X. H. Lin et al [16] used PEMHP (piezoelectric machine hammer peening) to study the surface modification of 6016 aluminum alloy anodizing film, including surface roughness, surface morphology, and hardness.…”