Purpose

Aluminum alloy is susceptible to chloride ion attack in sea water, resulting in pitting damage and hence serious security risks for the related applications. To improve the corrosion resistance of Al alloy, micro-arc oxidation (MAO) technology has been developed to produce a protective dense oxide layer on top of Al alloy. However, the mechanism of MAO-induced corrosion resistance is still not fully understood, particularly on local corrosion issue. This paper aims to focus on comprehensively studying the corrosion-resistance mechanism by a series of technologies.

Design/methodology/approach

The corrosion behavior of samples was studied by open circuit potential (OCP), potentiodynamic polarization (PDP), electrode impedance spectroscopy (EIS) and localized electrode impedance spectroscopy (LEIS) tests in NaCl solution.

Findings

The MAO-coated Al alloy shows a more positive corrosion potential and a higher corrosion current density compared to the untreated counterpart, indicating a significantly enhanced corrosion-resistance. The study of surface morphology and structure also suggest significantly enhanced corrosion-resistance due to the MAO treatment.

Originality/value

Based on the results, a new corrosion model was proposed to describe the influence of MAO treatment on the corrosion process and corrosion mechanism of Al alloy, providing insights on the design of the corrosion-resistance coating for metallic alloys in marine applications.

中文翻译：

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铝基微弧氧化涂层腐蚀分析

目的

铝合金易受海水中氯离子的侵蚀，造成点蚀损坏，给相关应用带来严重的安全隐患。为了提高铝合金的耐腐蚀性能，已经开发出微弧氧化（MAO）技术，在铝合金表面形成一层保护性致密氧化层。然而，MAO 诱导的耐腐蚀性的机制仍未完全了解，特别是在局部腐蚀问题上。本文旨在通过一系列技术综合研究其耐腐蚀机理。

设计/方法/方法

通过开路电位（OCP）、动电位极化（PDP）、电极阻抗谱（EIS）和局域电极阻抗谱（LEIS）测试在NaCl溶液中对样品的腐蚀行为进行了研究。

发现

与未处理的对应物相比，MAO 涂层的铝合金显示出更正的腐蚀电位和更高的腐蚀电流密度，表明其耐腐蚀性能显着提高。表面形态和结构的研究还表明，由于 MAO 处理，其耐腐蚀性能显着提高。

原创性/价值

在此基础上，提出了一种新的腐蚀模型来描述 MAO 处理对铝合金腐蚀过程和腐蚀机制的影响，为海洋应用金属合金的耐腐蚀涂层设计提供见解。