AZ91D镁合金表面电弧喷涂/微弧氧化复合陶瓷涂层结构组成与耐蚀性研究  

Structure and Corrosion Resistance of Composite Ceramic Coating Prepared by EASP/MAO on AZ91D Magnesium Alloy

作　　者：赵建华[1,2] 张宗伟[1] 王自红[1] 

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

出　　处：《稀有金属》2013年第4期549-556,共8页Chinese Journal of Rare Metals

基　　金：重庆市科技委员会科技攻关计划(CSTC;2008AA4029)资助项目

摘　　要：通过一种新的电弧喷涂/微弧氧化(EASP/MAO)复合工艺,在AZ91D镁合金表面制备了复合陶瓷涂层。电弧喷涂处理试样在430℃下进行了热扩散处理后,在以硅酸盐碱性电解液体系中进行微弧氧化处理。利用扫描电镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)对复合涂层表面和截面形貌、元素和相组成进行了分析,利用CS2350双单元电化学工作站对涂层试样在3.5%NaCl溶液中的动电位极化曲线进行了测定。结果表明:在430℃、氩气保护氛围下,保温热扩散处理2 h后,在基材与喷涂铝层间形成了热扩散层,扩散层由Al3Mg2和Al12Mg17两相组成。由于电弧喷涂铝涂层存在较多的表面缺陷,其对AZ91D镁合金基材只能起到有限的保护作用。经微弧氧化处理后,电弧喷涂铝涂层表面形成氧化铝陶瓷层,主要由α-Al2O3和γ-Al2O3两相组成。跟AZ91D镁合金基体相比,经微弧氧化处理10,20 min后的试样在3.5%NaCl溶液中的自腐蚀电位分别正移到-0.8279,-1.0570 V,较基体约分别提高770,550 mV,腐蚀倾向降低,基体的自腐蚀电流密度为经过微弧氧化处理10 min后试样的4.1倍,为经过微弧氧化处理20 min试样的460.6倍。Through a new electric arc spraying （EASP）/micro-arc oxidation （MAO） compound technology, composite ceramic coating was prepared on the surface of AZglD magnesium alloy. The sprayed sample was treated with heat diffusion treatment at 430℃, and then processed with MAO in silicate alkaline electrolytic solution. The surface and cross section morphology, elements and phase com- position of the composite coating were analyzed by means of scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS） and X-ray diffraction （XRD）. By CS2350 double-cell electrochemical workstation, the potential dynamic polarization curves of the coating sample in 3.5% NaC1 solution were tested. The results showed that after treated with heat diffusion treatment at 430℃ in argon gas protection atmosphere for 2 h, thermal diffusion layer was generated between the substrate and aluminum coating. The ther- mal diffusion layer was composed of A13 Mg2 and Al12 Mg17 phases. Owing to the electric arc spraying aluminum coating existed many surface defects, the protective effect of the coating to AZglD magnesium alloy base material was limited. After micro-are oxidationprocess, aluminum oxide ceramic layer was generated on the aluminum coating, and the ceramic layer was mainly composed of ct-A1203 and ＂y-A12 03 phases. Compared with the AZ91 D magnesium alloy substrate, in 3.5 % NaC1 solution, the free corrosion potential of the samples treated with MAO for 10 and 20 min was moved to -0.8279 and - 1.0570 V, which enhanced about 770 and 550 mV com- pared with the substrate, respectively. The corrosion tendency was reduced; the free corrosion current density of the substrate was 4.1 times and 460.6 times to the sample treated by micro-arc oxidation with 10 and 20 min.

关 键 词：电弧喷涂 微弧氧化 耐蚀性 陶瓷层 热扩散层 

分 类 号：TG178[金属学及工艺—金属表面处理] TB37[金属学及工艺—金属学]