INFLUENCE OF MOLYBDENUM ON THE CORROSION PROPERTIES OF STAINLESS-STEEL FILMS

Fine-grained, 304 type stainless steel films have been prepared by magnetron sputtering. The chemical composition and the microstructure of these sputter-deposited steels as well as the chemical composition and the thickness of their passive layers have bean characterized and compared with those of the bulk 304 stainless steel. The resistance against localized corrosion of the films in 5 M NaCl solution was found to be markedly higher than that of bulk. The pitting potentials of the different samples spread over 450 mV. In the potentiodynamic polarization curves, a large number of current transients were observed. In order to determine the influence of molybdenum on the corrosion properties of stainless steel, films with increasing concentrations of Mo were produced without changing the deposition parameters. The pitting potential of these films became more noble and more reproducible with increasing Mo content. The number of current transients decreased. In 1 M HCl solution the passivation ability was found to be increased with increasing Mo content.