Electrochemical studies of amorphous passive films prepared by ion beam

Alternating Fe,Cr layers were deposited on the glass and the pure iron substrates placed in a target chamber of a 200 KeV implanter. Fe-Cr amorphous films have been formed by ion beam mixing with 150 KeV Ar+, P+ and B+ respectively. The doses were varied from 1.5x1015ions/cm2 to 5x1016ions/cm2. The process of ion bombardment was simulated by TRIM-88 program. Microstructures of the ion-mixed Fe-Cr samples were examined by transmission electron microscope (TEM). The anodic polari-zation curves were obtained by means of a potentiodynamic sweep system. Results show that the corrosion resistance of the amorphous film in 1N H2SO4 solution is considerably increased than that of pure iron. It is found by X-ray photoelectron spectroscopy (XPS) analysis that the in-crease of the corrosion resistance is associated with an ultra-thin Cr-rich surface film, which contains a compound of [CrOx (OH)y·nH2O]. (author). 3 refs.; 4 figs.; 3 tabs