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About Samer Darwich

Chemnitz University of Technology, Surface Technology and Functional Materials, Chemnitz, Germany Email: samer.darwich@s2006.tu-chemnitz.de

Sol-Gel Coating for Aluminum Alloy: Self-Healing Characteristics

Water-based sol-gel coatings have been developed in the last years as cost-efficient and environmentally friendly protective layers. The stability of sol-gel films is often limited in the absence of functional compounds to generate self-healing. In this work, a water-based sol-gel coating was applied on aluminum alloy 6082. Benzotriazole and cerium nitrate were used as dopants and added to the sol after aging. The coating was injured in order to generate self-healing. The self-repairing feature of the defected specimen was evaluated by electrochemical impedance spectroscopy (EIS) in chloride solution. Healing qualification was examined by monitoring the defect size during the immersion test. The experiments show that the samples coated with an inhibitor-doped film are better protected against corrosion even after long-time immersion in chloride solution. The defect size after healing was smaller than that of the samples coated with non-doped film, which exhibited low stability in chloride solution. The defect size was several times bigger after the corrosion test. A contact stylus instrument and a scanning electron microscope (SEM) were used to characterize the defect surface profiles before and after healing.