INVESTIGATION ON ELECTROCHEMICAL CORROSION CHARACTERISTIC OF 2A14 ALUMINUM ALLOY IN NITRIC ACID

In order to evaluate the left life of the aircraft tank in the storage stage and enhance the reliability of aircraft, the electrochemical corrosion characteristic of 2A14 aluminum alloy has been investigated by the polarization curve method, electrochemical impedance spectroscopy methods and soaking corrosion test in this paper. The corrosion equivalent relationship of 2A14 aluminum alloy at different conditions was established. Moreover, the corrosion mechanism and law of 2A14 aluminum alloy in the solution of N2O4-HNO3 were obtained. It is shown that the nitric acid with the volume fraction of 30% corrodes 2A14 aluminum alloy had the fastest speed. The corrosion intensity of the specimen increases with the increase of the environment temperature. In the corrosion program, the corrosion is begun with the pit with very small size. As the time passes by, the pits expand and the adjacent pits combines together to be a larger pit. Finally, the thickness of the specimen decreases uniformly as the corrosion product peels off from the surface of the specimen. Therefore, the corrosion evaluation of aluminum alloy structure can be performed by weighting or measuring the thickness in application.