THE USE OF ELECTROCHEMICAL AND SURFACE-ANALYTICAL TECHNIQUES TO CHARACTERIZE PASSIVE OXIDE-FILMS ON NICKEL

Anodic oxide films formed on nickel in Na//2SO//4 solutions have been examined by electrochemical and surface-analytical techniques (RHEED, OK// alpha 61 X-ray emission spectroscopy, Auger electron spectroscopy, and replica electron microscopy). Depending on the conditions of formation, there can be large variations in the stability of the passive film towards dissolution. The relationship between the stability of the passive film, its defect character, and the measured corrosion currents is discussed. The nature and growth of thick porous films is examined.