The aerospace industry currently visually evaluates results from continuous salt spray and filiform exposures to judge the effectiveness of chromate-inhibited coatings. These methods, however, do not provide enough information for non-chromate-inhibited coatings. Quantitative tests are needed and are described in the paper. Electrochemical impedance spectroscopy (EIS) and galvanic current (Igalv) are two such tests. EIS response on bonded films measures barrier properties (Rpore) of coatings. EIS on corresponding non-bonded films measures the electrochemical passivation activity (Rct) of the inhibitors they contain. Prediction of field performance requires knowing both Rpore and Rct. Result comparisons are made between EIS and cyclic and continuous salt spray exposures for several non-chromate-inhibited primers and their chromate-inhibited and uninhibited controls. Filiform results are also discussed. Measuring Igalv with a tightly spaced titanium cathode gradually creates the anaerobic acidic conditions of crevice and pit environments. Inhibiting corrosion of aircraft aluminum alloys in these conditions is a predictor of inhibitor performance in crevice environments.


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    Title :

    Development of chromate-free corrosion inhibitors for aircraft aluminum alloys


    Contributors:
    Lewis, K.J. (author)


    Publication date :

    1999


    Size :

    26 Seiten, 5 Bilder, 4 Tabellen, 14 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English






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