Sealing of tartaric sulfuric (TSA) anodized AA2024 with nanostructured LDH layers

Abstract

In this work, a functional sealing of a TSA anodic layer on AA2024 is suggested based upon the formation of inhibitor-containing Zn–Al layered double hydroxides (LDH). The LDH structures are formed in the pores of the anodic layer and on top of it as a result of hydrothermal treatment in a Zn²⁺-containing bath as shown by the structure, morphology and composition analysis. The resulting LDHs were loaded with a well-known corrosion inhibitor (vanadate). Electrochemical impedance spectroscopy, salt spray tests and scanning vibrating electrode techniques have shown a remarkable improvement in corrosion resistance of the LDH-modified sample in comparison with conventional hot-water sealing. The vanadate-loaded LDHs rendered a significant long-term active protection for the covered aluminum alloy substrate.