Abstract
The influence of a short‐time prefilming treatment with benzimidazole‐2‐thiol on the corrosion resistance of Cu Zn 22Al 2 has been examined.
The efficiency of the prefilming treatment has been evaluated by recording the anodic and the cathodic polarization curves in 0.1 N NaCl.
Ellipsometric measurements have been carried out in order to obtain some information on the properties of the layer.
Comparative data on “prefilmed” and “bare” Cu Zn 22Al2 specimens have been obtained in aqueous chloride solutions circulating in a corrosion loop and by tests in moist atmosphere containing SO~2~.
Galvanic corrosion testing have been carried out by using small not prefilmed areas and large prefilmed ones, simulating in this way the partial removal of the film from the metallic surface.
The results suggest that a metal‐inhibitor film forms on Al‐brass, which mainly affects the cathodic reaction rate.
Furthermore, the tests clearly indicate that the effect of benzimidazole‐2‐thiol is strongly influenced by a pre‐existing oxide layer on the alloy surface.
A good protection against atmospheric corrosion is reached by prefilming treatment.
Corrosion loop testing indicate that prefilming does not hinder the formation of protective corrosion products on the surface of the alloy in flowing aqueous solutions.