(Invited) Contribution of Oxygen Reduction to Mg Corrosion: Computational Modelling

Abstract

The magnesium corrosion mechanisms are still a matter of discussions. Independent from that there is agreement that the cathodic behaviour is based on the superposition of water and oxygen reduction reactions [1]. Accessing the amount of cathodic reaction contributions to the entire corrosion current density via experiment is challenging [2,3]. In a recent work of Wang et al. [4] a combined experimental and computational approach was utilized to explore the superposition of cathodic reactions during Mg corrosion in aqueous electrolytes for different iron impurity situations. The study shows significant variation of percentual contribution of oxygen reduction to the cathodic current for the studied purity levels.In this work a computational modelling approach is presented accordingly. It is based on the numerical model developed by Höche [5] and enables virtual local electrochemical testing and computational assessment of (electro-)chemical system and transport descriptors. Respective simulation results show, how corrosion and testing system parameters change the measured oxygen approach curves. Subsequently a multi-parameter calibration enabled the quantification of oxygen reduction reaction to the entire corrosion process. The reproduction of experimental results and strategies for model improvement are discussed. REFERENCES: [1] Höche, D., Blawert, C., Lamaka, S. V., Scharnagl, N., Mendis, C., & Zheludkevich, M. L., The effect of iron re-deposition on the corrosion of impurity-containing magnesium. Physical Chemistry Chemical Physics, 18-2 (2016), 1279-1291.[2] Yasakau, K. A., Höche, D., Lamaka, S. L., Ferreira, M. G., & Zheludkevich, M. L., Kelvin microprobe analytics on iron-enriched corroded magnesium surface. Corrosion, 73-55 (2017), 583-595.[3] E.L. Silva, S.V. Lamaka, D. Mei, M.L. Zheludkevich, The Reduction of Dissolved Oxygen During Magnesium Corrosion, ChemistryOpen, 7 (2018) 664-668.[4] C. Wang, W. Xu, D. Höche, M.L. Zheludkevich, S.V. Lamaka, Exploring the contribution of oxygen reduction reaction to Mg corrosion by modeling assisted local analysis, Journal of Magnesium and Alloys, 11 (2023) 100-109.[5] Höche D., Simulation of corrosion product deposit layer growth on bare magnesium galvanically coupled to aluminum. Journal of the electrochemical society, 162-1 (2014), C1. ACKNOWLEDGEMENTS: C. Wang, W. Xu, thank China Scholarship Council for the funding, grants no. 201806310128 and 201908510177