EFFECTS OF AC-MODULATED PASSIVATION AND POSTTREATMENT ON COMPOSITION AND STABILITY OF PASSIVE FILMS

An investigation of the effects of alternating voltage modulated passi vation (AC-modulated passivation) and post-treatment on the compositio n and stability of passive films on 302 and 316 stainless steels by el lipsometry, electrochemistry, and surface Auger electron spectroscopy analysis was carried out. AC-modulated passivation increases the conce ntration of elements O, and the ratio Cr/(Cr + Fe) in the passive film , changes the depth composition profile of the film, roughens the surf ace of the passive film and makes it more favorable to the adsorption of molybdenum-containing ions during post-treatment Hence, the resista nce against the chemical dissolution of the passive film increased and the stability of the passive film improved.