磁控溅射镀铝AZ31镁合金等离子体电解氧化揭示的放电通道结构及其腐蚀行为  

Discharge channel structure revealed by plasma electrolytic oxidation of AZ31Mg alloy with magnetron sputtering Al layer and corrosion behaviors of treated alloy

作　　者：胡攀峰 魏兵剑 程昱琳 程英亮[1] Pan-feng HU;Bing-jian WEI;Yu-lin CHENG;Ying-liang CHENG(College of Materials Science and Engineering,Hunan University,Changsha 410082,China)

机构地区：[1]湖南大学材料科学与工程学院,长沙410082

出　　处：《Transactions of Nonferrous Metals Society of China》2024年第1期139-156,共18页中国有色金属学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 51671084)。

摘　　要：在硅酸盐-六偏磷酸盐电解液中对覆盖薄磁控溅射铝层的AZ31镁合金进行等离子体电解氧化(PEO),以研究PEO机理并提高合金的耐腐蚀性。使用SEM和EDS检测涂层形貌并追踪涂层中Mg和Al元素的分布。新的涂层主要在靠近涂层/金属基体界面的放电通道下部形成。在放电通道上部先前形成的氧化物大部分以固态形式保留在原先的位置,只有少部分熔融氧化物通过涂层的微孔流出,到达表层。阴离子可以通过涂层充满电解液的孔传输,自由地进入涂层的最深部位。在3.5%NaCl (质量分数)中进行开路电位、极化曲线和EIS测试。结果表明,致密的磁控溅射Al层可以显着提高AZ31镁合金的耐腐蚀性,其耐腐蚀性甚至优于PEO处理后的样品。Plasma electrolytic oxidation(PEO)of AZ31 magnesium alloy with a thin magnetron sputtering Al layer was carried out in a silicate–hexametaphosphate electrolyte to investigate the PEO mechanism and improve the corrosion resistance of the alloy.SEM and EDS were employed to examine the coating morphology and trace the Mg and Al elements in the coatings.It is found that new coating is mainly formed at the lower part of the discharge channels close to the interface of coating/metal substrate.The previously formed oxides at the upper part of discharge channels are largely kept in their original solid forms within the discharge channels.Only a small fraction of the molten oxide flows out through the micropores of the coating,reaching the top layer.The anionic species can freely access the innermost of the coatings,which are also transported through the electrolyte-filled pores.The corrosion behavior of the coatings was examined by open circuit potentials,polarization curves and EIS tests in 3.5 wt.%NaCl.Owing to its compact nature,the magnetron sputtered Al layer can significantly improve the corrosion resistance of the AZ31 Mg alloy,which is even better than that of the samples after PEO treatment.

关 键 词：AZ31镁合金 磁控溅射Al层 等离子体电解氧化 放电通道 耐腐蚀性能 

分 类 号：TG174.4[金属学及工艺—金属表面处理]