Novel smart and self-healing cerium phosphate-based corrosion inhibitor for AZ31 magnesium alloy

• Published in: Corrosion science 2020-07, Vol.170, p.108648, Article 108648
• Main Authors: Calado, Lénia M., Taryba, Maryna G., Morozov, Yegor, Carmezim, Maria J., Montemor, M. Fátima
• Format: Article
• Language: English
• Subjects: A. Alloy; A. Magnesium; A. Organic coatings; A. Rare earth elements; B. EIS; Cerium; Corrosion; Corrosion effects; Corrosion inhibitors; Corrosion prevention; Electrochemical impedance spectroscopy; Electrodes; Lanthanide phosphates; Magnesium base alloys; Organophosphates; Protective coatings; Scanning; Spectrum analysis
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2020.108648

[Display omitted] •Modification of hybrid epoxy-silane coating with Ce(DEHP)3 corrosion inhibitor.•Improved corrosion protection of AZ31 with Ce(DEHP)3.•Cyclic corrosion inhibition effect of Ce(DEHP)3.•Self-healing in coating defects in the presence of the inhibitor.•pH-activated corrosion inhibitor. Tri(bis(2-ethylhexyl)phosphate) (Ce(DEHP)3) was used as novel corrosion inhibitor for protection of AZ31 coated with an epoxy-silane hybrid coating. Electrochemical Impedance Spectroscopy (EIS) in 0.05 M NaCl showed that Ce(DEHP)3-modified coating offered superior corrosion protection compared to a reference coating. Localized electrochemical techniques (Localized Electrochemical Impedance Spectroscopy – LEIS, Scanning Vibrating Electrode Technique – SVET, and Scanning Ion-Selective Electrode Technique – SIET) were employed to assess the corrosion healing effect of Ce(DEHP)3 in defect-containing coatings. Results showed that Ce(DEHP)3 introduces cyclic pH-dependent corrosion inhibition, involving the combined action of cerium and organophosphate ions through formation of protective Ce- and P-containing species.