Investigation of electrochemical properties of inhibited chromate-free conversion coatings on AMg3 aluminum alloy during exposure in a humidity chamber

Aluminum alloys of Al-Mg system have high corrosion resistance, but studies show that they are characterized by pitting corrosion even under atmospheric conditions.Therefore, various coatings for their protection are used, including those obtained by chemical oxidation.In this paper, studies of chromate-free inhibited IFKhANAL-3 conversion coatings were carried out in G-4 humidity chamber combined with electrochemical impedance spectroscopy, conductometric analysis, and X-ray spectral microanalysis.This made it possible to identify the factors of the beginning of the corrosion process and, in particular, show that the corrosion inhibitor does not undergo desorption during testing.It was shown that the addition of 1,2,3benzotriazole to the converting solution contributes to both an increase in the active resistance (Rf) of the oxide film and a delayed emergence of the first corrosion damage on the coating in comparison with unmodified coatings.Based on conductometric data, it has been shown that a decrease in the porosity of the coatings is observed during G-4 humidity chamber tests.