Protective Action of Inorganic Inhibitors on Mechanically Activated Aluminum Surfaces

We study the protective action of chromate and phosphate corrosion inhibitors on the mechanically activated aluminum surfaces. The values of the electrode potential in the course of repassivation of aluminum in reference and inhibited corrosive media are lower by about 100-400 mV than in the case of free corrosion, which indicates the possibility of galvanic interaction of mechanically activated and intact regions of the metal. The highest repassivation rate is observed in the uninhibited medium and in the medium inhibited by chromate. In phosphate-containing solutions, it is somewhat lower. Both inhibitors substantially decrease the current density of potentiostatic polarization of the fresh section of aluminum, which leads to the formation of a protective film forms on this surface. The chromate corrosion inhibitor proves to be the most efficient under the indicated conditions.