Towards an Easy Electrochemical Method for Evaluating Sealing Quality of Anodized Aluminium

Abstract: A variety of methods are employed for evaluating the sealing quality of anodized aluminium. These tests are based on various mechanisms, can be qualitative or quantitative, and vary in the level of detail and preparation necessary to obtain good results. In this work, we evaluate a variety of electrochemical methods (electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and open circuit potential (OCP) evolution with time measurements) as candidates for sealing quality evaluation. The desirable criteria for a target electrochemical test method are that it is non-destructive, requires little or no prior sample preparation, is applicable to long anodized profiles, is completed in a short time, and yields results that are interpretable with very little or no post-test data processing. Selected electrochemical tests were carried out on sulphuric acid anodized AA6060 aluminium alloy samples hydrothermally sealed at a constant time (30 minutes) in de-ionized water at varying temperatures, 50 ^°C, 60 ^°C, 70 ^°C, 80 ^°C, 90 ^°C, and 98 ^°C, respectively. The feasibility of a simple electrochemical method (OCP evolution) for evaluating the barrier properties (corrosion resistance) of sealed and partially sealed anodized aluminium samples is demonstrated.

Ackowledgements

This work was developed in the scope of the R&D Project in Co-promotion “ANOD 2: Advancing Anodization for Energy Efficiency and Enhanced Durability”, operation no. 20585, operation code in the COMPETE2030 Funds Desk FEDER-02055500, with funding FEDER,Fundo Europeu de Desenvolvimento Regional, through the Research and Development Incentive System, within the scope of Portugal 2030, and had laboratory support from project UID 00481/2025 Centre for Mechanical Technology and Automation, https://doi.org/10.54499/UID/00481/2025, supported by national funds from FCT, Fundação para a Ciência e a Tecnologia, I.P.