Corrosion Protection of Powder Metallurgy Al Alloys by Sol-Gel Based Coatings Systems

摘要

Aluminum alloys that include Cu and Mg are widely used as structural materials in aerospace industry due to their low densities and good mechanical properties. Nevertheless, these alloys are subjected to corrosion in aggressive media because of the inhomogeneous distribution of Cu associated with intermetallic compounds. This work reports a new approach combining powder metallurgy and sol-gel methods as an alternative to Cr(VI)-based conversion coating for corrosion protection. The corrosion behavior of AA2024-T3 and the powder metallurgy alloy PM2124-T4 obtained from spherical and irregular powders were studied before and after applying the sol-gel coating. The electrochemical assessment was performed by electrochemical impedance spectroscopy (EIS) and the characterization of the alloys by scanning electron microscopy (SEM). The results of this work have shown an improvement of the corrosion performance after the application of sol-gel coating.