A comparative study on the formation of Micro-arc oxidation coatings on AZ31B and AC84 magnesium alloys

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, COATINGS & FILMS

Surface & Coatings Technology Pub Date : 2025-09-29 DOI:10.1016/j.surfcoat.2025.132743

Chi-Hua Chiu , Shih-Yen Huang , Yu-Ren Chu , Shun-Han Yang , Peng-Wei Chu , Jyh-Wei Lee , Yoshihito Kawamura , Yueh-Lien Lee

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Abstract

This study investigates the micro-arc oxidation (MAO) behavior of AZ31B and Mg–8Al–4Ca (AC84) magnesium alloys, with emphasis on the role of the β–Al–Ca phase (β phase). Constant-voltage MAO treatments were performed, and the resulting coatings were characterized by SEM and TEM. At low voltage (150 V), the high conductivity of the β phase in AC84 promoted localized discharges, leading to uneven and thinner coatings compared to the more uniform coatings on AZ31B. At higher voltages (≥200 V), AC84 formed stable Mg–Ca-rich silicate/oxide phases, enhancing coating corrosion resistance. However, reduced discharge intensity in AC84 at high voltages also limited coating growth, resulting in thinner layers under identical conditions. Selective removal of surface β phases prior to MAO improved coating uniformity and thickness, yielding characteristics closer to those of AZ31B. These findings demonstrate the significant influence of β phase distribution and anodizing voltage on MAO coating evolution and performance.

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AZ31B和AC84镁合金微弧氧化膜形成的对比研究

本文研究了AZ31B和Mg-8Al-4Ca （AC84）镁合金的微弧氧化（MAO）行为，重点研究了β - al - ca相（β相）的作用。采用恒压MAO处理，用扫描电镜和透射电镜对涂层进行表征。在低电压（150 V）下，AC84中β相的高电导率促进了局部放电，导致涂层不均匀且更薄，而AZ31B的涂层更均匀。在较高电压下（≥200 V）， AC84形成稳定的富镁钙硅酸盐/氧化物相，增强了涂层的耐蚀性。然而，高压下AC84放电强度的降低也限制了涂层的生长，导致在相同条件下涂层更薄。在MAO之前选择性去除表面β相可以改善涂层的均匀性和厚度，使其性能更接近AZ31B。这些结果表明β相分布和阳极氧化电压对MAO涂层的演变和性能有显著影响。

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来源期刊

Surface & Coatings Technology 工程技术-材料科学：膜

CiteScore

10.00

自引率

11.10%

发文量

921

审稿时长

19 days

期刊介绍： Surface and Coatings Technology is an international archival journal publishing scientific papers on significant developments in surface and interface engineering to modify and improve the surface properties of materials for protection in demanding contact conditions or aggressive environments, or for enhanced functional performance. Contributions range from original scientific articles concerned with fundamental and applied aspects of research or direct applications of metallic, inorganic, organic and composite coatings, to invited reviews of current technology in specific areas. Papers submitted to this journal are expected to be in line with the following aspects in processes, and properties/performance: A. Processes: Physical and chemical vapour deposition techniques, thermal and plasma spraying, surface modification by directed energy techniques such as ion, electron and laser beams, thermo-chemical treatment, wet chemical and electrochemical processes such as plating, sol-gel coating, anodization, plasma electrolytic oxidation, etc., but excluding painting. B. Properties/performance: friction performance, wear resistance (e.g., abrasion, erosion, fretting, etc), corrosion and oxidation resistance, thermal protection, diffusion resistance, hydrophilicity/hydrophobicity, and properties relevant to smart materials behaviour and enhanced multifunctional performance for environmental, energy and medical applications, but excluding device aspects.