Quantitative methods of predicting relative effectiveness of corrosion inhibitive coatings

Conference · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:370907

Aklian, J H; Lewis, K J; Zook, J D ^[1]

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1. Courtaulds Aerospace, Burbank, CA (United States)

Results from several test methods are corroborated in predicting relative protection by non-chromate corrosion inhibitors in coatings for aircraft aluminum. Candidates are compared to both uninhibited and chromate-inhibited controls. Greater corroboration of results under a variety of test conditions gives greater confidence that new materials will protect aircraft aluminum alloys for the life of an aircraft, in a large range of exposure environments. Visually evaluated salt spray and filiform exposures used by the aerospace industry to judge the effectiveness of chromate-inhibited coatings, do not provide an adequate picture for non-chromates. Additional tests, electrochemical in nature, are needed and are suggested herein. Electrochemical impedance spectroscopy (EIS) on both bonded and non-bonded films distinguishes barrier properties of inhibited coatings from their electrochemical passivation activity, enabling more accurate prediction of long term field behavior. Passivation of aircraft aluminum alloys in acidic solution is a rapid predictor of crevice or pit corrosion inhibitor capability. Measurement of long term galvanic currents with a titanium cathode is recommended to determine capabilities of inhibited coatings in preventing localized (crevice) corrosion.

• OSTI ID: 370907
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
CHROMATES
CORROSION INHIBITORS
CORROSION PROTECTION
CREVICE CORROSION
FILMS
IMPEDANCE
PASSIVATION