电火花表面改性对AZ91D镁合金电弧喷涂铝涂层耐蚀性的影响  

Effect of ESD Surface Modification on Corrosion Resistance of Electric Arc Spraying Aluminum Coating of AZ91D Magnesium Alloy

作　　者：赵建华[1,2] 王自红[1] 盖锐[1] 

机构地区：[1]重庆大学材料科学与工程学院,重庆400045 [2]国家镁合金材料工程技术研究中心,重庆400044

出　　处：《稀有金属》2014年第1期1-7,共7页Chinese Journal of Rare Metals

基　　金：重庆市科技攻关计划(CSTC;2008AA4029)项目资助

摘　　要：通过电弧喷涂／电火花沉积复合工艺在AZ91D镁合金表面制备了耐蚀性涂层。利用扫描电镜（SEM）、能谱分析仪（EDS）、电化学测试和浸泡实验等研究手段，研究了电弧喷涂／电火花沉积复合涂层的结构及耐腐蚀性能，并对涂层腐蚀机制进行了分析。结果表明：经电弧喷涂／电火花沉积复合处理后，Ecorr=-1．33V，较基体和喷涂铝涂层试样分别正移约280，40mV，腐蚀倾向性有所降低；点蚀电位为-0．704V，较电弧喷涂铝涂层试样提高约60mV，点蚀敏感性有所降低；电弧喷涂铝涂层试样的钝化电流ipass=4．6×10～A·cm～，电弧喷涂／电火花沉积处理试样的ipasa3．2×10^-6A·cm^-2，经电火花表面改性后，涂层钝化膜自修复能力大幅增强；在3．5％NaCl溶液中，经36h浸泡试验后，电弧喷涂铝涂层试样表面出现直径达150μm的点蚀坑；而电弧喷涂／电火花沉积复合涂层表面仅出现直径约5—8μm的点蚀坑，涂层发生的主要为亚稳态点蚀。Through the electric arc spraying （EASP）/electric spark deposition（ESD） compound process, the corrosion resistance coating was prepared on the surface of AZ91D magnesium alloy. The structure and the corrosion resistance of the composite coating were analyzed by means of scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS）, electrochemical test and im- mersion test. The corrosion mechanism of the coating was also studied. The results showed that, compared with the substrate and EASP sample, after EASP/ESD compound process, the free corrosion potential Ecorr was - 1.33 V, which was positively moved about 280, 40 mV, respectively, and the corrosion tendency was reduced. The pitting potential of the composite coating was - 0.704 V, which enhanced about 60 mV by sprayed aluminum layer, and the pitting sensitivity was reduced. The passive current of the EASP sample and EASP/ESD sample was 4.6 x 10 -3, 3.2 × 10 ^-5 A.cm^ -2 respectively. After ESD surface modification, the self-healing capabilities of the passive film were significantly enhanced. After 36 h immersion test in 3.5% NaCl solution, the diameter of the pitting corrosion of sprayed aluminum coating could reach 150 μm, however, the diameter of the pitting corrosion of EASP/ESD composite coating was just about 5 × 8 μm, and the coating occurred mainly metastable pitting.

关 键 词：电火花沉积 电弧喷涂 耐蚀性 镁合金 

分 类 号：TG174[金属学及工艺—金属表面处理]