Cathodic inhibition mechanism of magnesium alloys by using iron-complex inhibitor
(1. Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou 510632, China;
2. Shaoguan Research Institute of Jinan University, Shaoguan 512027, China;
3. Institute of Surface Science, Helmholtz-Zentrum Hereon (Hereon), Geesthacht 21502, Germany;
4. Faculty of Engineering, University of Kiel, Kaiserstra？e 2, Kiel 24143, Germany)
2. Shaoguan Research Institute of Jinan University, Shaoguan 512027, China;
3. Institute of Surface Science, Helmholtz-Zentrum Hereon (Hereon), Geesthacht 21502, Germany;
4. Faculty of Engineering, University of Kiel, Kaiserstra？e 2, Kiel 24143, Germany)
Abstract: The effect of a cathodic inhibitor (3-methylsalicylate, 3-MeSA) on the corrosion properties of Fe-contained pure Mg was investigated. The composition of Fe-rich particles, corrosion surface morphology, and molecular structure of 3-MeSA provide experimental and theoretical evidence for the corrosion behavior of Fe-contained Mg alloy and the corresponding cathodic inhibition mechanism of 3-MeSA. The results showed that silicon in a solid solution within Fe-rich particles was found, and the features of corrosion spots may correlate with different Fe/Si ratios. Although 3-MeSA can form an adsorptive layer on Mg substrate, its inhibition mechanism can be mainly ascribed to the capability to chelate Fe2+/Fe3+ ions released from self-corrosion of Fe-rich particles, preventing the re-deposition of the reduced Fe species.
Key words: magnesium; iron-rich impurity; iron complex; cathodic inhibitor; quantum chemical calculation