Substitution of hexavalent chromate conversion treatment with a plasma electrolytic oxidation process to improve the corrosion properties of ion vapour deposited AlMg coatings
Substitution of hexavalent chromate conversion treatment with a plasma electrolytic oxidation process to improve the corrosion properties of ion vapour deposited AlMg coatings
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DOI：
10.1016/j.surfcoat.2010.09.017
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发表时间：
2010-12
影响因子：
5.4
通讯作者：
Nayef M. Alanazi;A. Leyland;A. Yerokhin;A. Matthews
中科院分区：
文献类型：
--
作者：
Nayef M. Alanazi;A. Leyland;A. Yerokhin;A. Matthews
在本文中，等离子体电解氧化（PEO）是一种潜在的有益的沉积后处理铝-5 wt.%，使用离子气相沉积（IVD）将Mg涂层沉积到Ti合金基底上，以取代有毒的六价铬转化处理，同时增强这种IVD涂层的阻隔保护性能。通过动电位极化扫描、开路电位测量和电化学阻抗谱研究了IVD涂层上PEO层在水中的腐蚀行为。通常，IVD铝基涂层需要涂层后喷丸处理以致密涂层结构;然而，发现PEO层可以成功地在沉积到Ti合金基材上的沉积IVD涂层上形成，提供了一种具有成本效益的工艺来改善腐蚀行为。PEO处理可独特地提高IVD涂层的耐腐蚀性; PEO层在含有Cl−离子的水性环境中具有有效的防腐蚀性能。一个更积极的腐蚀电位，较低的腐蚀电流和增加的极化电阻记录的PEO层，相比传统的铬酸盐转化处理。
In this paper plasma electrolytic oxidation (PEO) is examined as a potentially beneficial post-deposition treatment for Al-5wt.%Mg coatings deposited onto Ti alloy substrates using Ion Vapour Deposition (IVD), with a view to replacing toxic hexavalent chromate conversion treatments and at the same time enhancing the barrier protection properties of such IVD coatings. The aqueous corrosion behaviour of PEO layers formed on IVD coatings was evaluated by means of potentiodynamic polarisation scans, open circuit potential measurements and electrochemical impedance spectroscopy. Normally, IVD aluminium-based coatings require a post-coat shot peening treatment to densify the coating structure; however it was found that PEO layers could be formed successfully on as-deposited IVD coatings deposited onto Ti alloy substrates, providing a cost effective process to improve corrosion behaviour. PEO treatment provides unique improvements in the corrosion resistance of IVD coatings; the PEO layer possesses effective anticorrosion properties in aqueous environments containing Cl−ions. A more positive corrosion potential, lower corrosion current and increased polarisation resistance were recorded for PEO layers, compared to traditional chromate conversion treatments.