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arXiv 2303.09324physics.chem-ph
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氧还原反应对Mg-Al-Ca固溶体电化学阴极部分反应的贡献

Contribution of the oxygen reduction reaction to the electrochemical cathodic partial reaction for Mg-Al-Ca solid solutions

Markus Felten, Siyuan Zhang, Rasa Changizi, Christina Scheu, Mark Bruns, Michael Strebl, Sannakaisa Virtanen, Daniela Zander

摘要:

镁及镁合金的电化学腐蚀速率取决于所形成的表面层的稳定性。基于Mg基底,氧化物结构包括多孔板状Mg(OH)2层下方的致密MgO/Mg(OH)2混合物。虽然阳极部分反应的动力学主要归因于MgO,但最近的研究表明Mg(OH)2层厚度对阴极部分反应的影响。较薄的Mg(OH)2层与较高的氧还原速率动力学相关。在本研究中,提出的机制已被进一步研究,通过原位呼吸测量与Mg-Al-Ca固溶体在不同pH值的电解质(pH = 8-13)。结果表明,在镁腐蚀的钝化状态的表面层的结构的基础上的附加效果。此外,两个不同的富铝中间层在Mg/MgO-和MgO/Mg(OH)2界面观察和讨论的热力学稳定性在碱性浸渍条件下。

英文摘要:

The electrochemical corrosion rate of Magnesium (Mg) and Mg alloys depends on the stability of the formed surface layer. Based on the Mg substrate, the oxide structure comprises a dense MgO/Mg(OH)2 mixture underneath a porous plate-like Mg(OH)2 layer. While the kinetics of the anodic partial reaction has been mainly attributed to MgO, recent studies showed an effect of the Mg(OH)2 layer thickness on the cathodic partial reaction. A thinner Mg(OH)2 layer has been associated with a higher kinetics of the oxygen reduction rate. In the present study, the proposed mechanism has been further investigated via in situ respirometric measurements with Mg-Al-Ca solid solution in electrolytes with different pH values (pH = 8-13). The results indicate an additional effect based on the structure of the surface layer in the passive state of Mg corrosion. Furthermore, two different Al enriched interlayers at the Mg/MgO- and MgO/Mg(OH)2 interfaces were observed and discussed in terms of their thermodynamic stability under alkaline immersion conditions.

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