纯镁及AZ91D镁合金微弧氧化膜层耐蚀性的对比  

Comparison of corrosion resistance of MAO coatings fabricated on pure Magnesium and AZ91D Magnesium alloy

作　　者：王占营[1] 马颖[1] 安守静 王晟[1] WANG Zhan-ying;MA Ying;AN Shou-jing;WANG Sheng(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou Univ.of Tech.,Lanzhou 730050,China)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《兰州理工大学学报》2023年第3期1-8,共8页Journal of Lanzhou University of Technology

基　　金：甘肃省创新研究群体计划资助(1111RJDA011)。

摘　　要：基于硅酸盐电解液体系,在纯镁、AZ91D镁合金基体上制备微弧氧化膜,通过不同的表征手段对比两种基体材料下膜层的耐蚀性能.结果表明:AZ91D镁合金表面微弧氧化膜层的成膜性更好,且膜层中Mg_(2)SiO_(4)、MgF_(2)等物相更多,因此,点滴、电化学耐蚀性更好.纯镁微弧氧化膜在整个腐蚀过程中表现为全面腐蚀,在腐蚀后期基本丧失对基体的保护作用,而AZ91D镁合金微弧氧化膜层在浸泡后期出现了局部腐蚀,但仍然可以有效地保护基体.合金化后由于不同元素电极电位的不同,使得微弧氧化在基体表面α、β相区域出现了选择性起弧,这种交替的击穿放电现象有利于膜层致密度、成分及缺陷等微观组织结构特征参量的改善,从而使得AZ91D镁合金表面微弧氧化膜层具有更好的耐蚀性能.Micro-arc oxidation(MAO)coatings were prepared in the silicate-containing electrolyte on pure magnesium and AZ91D magnesium alloy substrates,and different characterization methods were used to compare the corrosion resistance of the coatings on the two substrates.The results showed that the AZ91D-MAO coating has better formability and more Mg_(2)SiO_(4)and MgF_(2)phases,resulting in better spotting and electrochemical corrosion resistance than that of Mg-MAO coating.The Mg-MAO coating exhibits overall corrosion in the whole deterioration process,but it basically loses the protection to the matrix in the late corrosion stage,for the AZ91D-MAO coating,localised corrosion occurs at the later stage of immersion,but the coating still can protect the substrate effectively.Due to the different electrode potentials of different elements after alloying,the selective arcing occurs on theαandβphase regions of the substrate surface.This alternating discharge phenomenon is conducive to the improvement of microstructure parameters such as the compactness,composition and defects of the coating,which results in a better corrosion resistance of the AZ91D-MAO coating.

关 键 词：基体材料 微弧氧化 耐蚀性 致密性 

分 类 号：TG174[金属学及工艺—金属表面处理]