Impedance spectroscopy of chromate-free conversion coatings on aluminum alloys of various alloying systems

• D.O. Chugunov, Yu.A. Kuzenkov and S.Yu. Rybakov

Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences, 31-4, Leninsky prospect, 119071, Moscow, Russia

Abstract: Electrochemical impedance spectroscopy is a method for investigating the protective properties of coatings, including conversion coatings on aluminum alloys. This method allows to analyze corrosion processes and protection mechanisms, providing information about the structure and properties of coatings. Technologies of chromate-free coatings by chemical oxidation continue to develop, so understanding what characteristics coatings on various aluminum alloys will have depending on the composition of the converting solution and modifying additives is an urgent task. In this article, inhibited chromate-free IFKhANAL-3 conversion coatings on AMg3, D16, V95T3 and 1424 aluminum alloys were investigated using the electrochemical impedance method, based on which the effectiveness of the obtained oxide films for protecting alloys from corrosion was determined. It has been shown that non-inhibited coatings practically do not differ in their protective properties for different alloys, whereas filling coatings in a corrosion inhibitor solution and adding 1,2,3-benzotriazole to the converting solution has a greater effect on copper-containing aluminum alloys. At the same time, one of the key factors for the effectiveness of a corrosion inhibitor is the uniformity of the obtained coatings.

Keywords: impedance, electrochemical impedance spectroscopy, aluminum alloys, conversion coatings, corrosion inhibitors, chromate-free technologies

Int. J. Corros. Scale Inhib., 2025, 14, no. 2, 694-705
doi: 10.17675/2305-6894-2025-14-2-14

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