Anodic Delamination Filiform Corrosion on Coated Aluminum

2 Anodic Delamination (Filiform Corrosion) on Coated Aluminum 

Cathodic debonding requires electron-conducting oxides and an interface that allows electrochemical reactions to occur. The latter usually requires the presence of ions and water molecules at the interface and therefore will dominate at high relative humidity. 

At low humidity and in the presence of insulating oxides such as MgO or AI2O3, cathodic debonding cannot occur and anodically driven debonding will prevail, which is called filiform corrosion (FFC, introduced by Sharman in 1944 [40]) in the corrosion community, as this type of debonding is character- 

FFC is known to appear only under specific conditions. It depends on the substrate used, the coating, and the humidity, and on the presence of a defect with a metal salt contamination as well as on the presence of oxygen [44—48]. Typically, it occurs in environments with a relative humidity well below 100% and usually it arises from surface defects in the protective film in the presence of soluble ionic species. 

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