ELLIPSOMETRIC AND ELECTROCHEMICAL INVESTIGATION OF PASSIVE FILM FORMATION ON IRON-NICKEL ALLOYS

New results for electrochemical behavior of iron-nickel alloys are needed in order to completely understand the mechanism of passive film formation in boric acid and borax solution, pH 8.5. The aim of this paper was to obtain additional experimental data for these alloys by using ellipsometric and electrochemical measurements. A Gaertner ellipsometer, model L 119, was used. Optical properties for all the samples in the bulk were calculated. By using the Drude and the Rowe and Shewchun approximations the thickness of the passive film formed on alloys was obtained. The value of film thickness increases with the iron content. An interpretation of both electrochemical and ellipsometric results is presented.