The effect of exposure conditions on performance evaluation of post-treated anodic oxides on an aerospace aluminium alloy: Comparison between salt spray and immersion testing

SURFACE & COATINGS TECHNOLOGY

卷:399

Article

Usman, B. J.¹  Scenini, F.^1,2  Curioni, M.^1,2 

[1] Univ Manchester, Dept Mat, Corros & Protect Grp, Oxford Rd, Manchester M13 9PL, Lancs, England

[2] Univ Manchester, Mat Performance Ctr, Dept Mat, Oxford Rd, Manchester M13 9PL, Lancs, England

关键词: Corrosion testing;    Anodizing;    Sealing;    Salt spray;    EIS;    Cerium;   

DOI  :  10.1016/j.surfcoat.2020.126157

来源: Elsevier

【 摘 要 】

In this work, the effect of the corrosion testing methodology on the degradation of anodized and post-treated AA-2024T3 specimens is considered. Two post-treatments are selected for the anodized layers, namely hydrothermal sealing and cerium-based post treatment. The two post-treatments are selected such that in one case corrosion protection mainly arises from a barrier effect (hydrothermal sealing) and in the other it arises from active inhibition (cerium-based treatment). It is found that salt spray and immersion testing provide similar results for the hydrothermally sealed oxides, but differ substantially for the cerium-treated oxides. The discrepancy is due to the fact that the continuously refreshing electrolyte layer during salt-spray testing promotes film dissolution and hinders precipitation of aluminium hydroxide and cerium compounds, unlike in stagnant bulk electrolyte. Hence, salt-spray testing is likely to be more aggressive than immersion testing for those systems that rely on active inhibition.

【 授权许可】

Free