ATOMIC-FORCE MICROSCOPY, SCANNING ELECTRON-MICROSCOPY AND ELECTROCHEMICAL CHARACTERIZATION OF AL-ALLOYS, CONVERSION COATINGS, AND PRIMERS USED FOR AIRCRAFT

Characterization of the metal-coating interface is crucial to the unde rstanding and prediction of the performance of corrosion protective co atings. To date, such characterization has been incomplete and perform ed on a scale of measurement that gives little microscopic-scale infor mation. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) have the ability to provide such information. We present in thi s work the use of such methods to examine the interface between steel and marine coatings and to image the surface of untreated aircraft alu minum alloys. We have also imaged these aircraft alloys after chromate /phosphate pretreatment. AFM and SEM have also been used to investigat e the changes in surface morphology, which accompany changes in the sa mples due to exposure. Electrochemical noise methods, electrochemical impedance spectroscopy measurements, and Prohesion(TM) testing were pe rformed in parallel with the AFM/SEM measurements. The results, along with implications for aircraft coatings, are discussed. (C) 1997 Elsev ier Science S.A.