Corrosion resistance of cerium-doped zinc calcium phosphate chemical conversion coatings on AZ31 magnesium alloy  

AZ31镁合金表面铈掺杂锌钙磷酸盐化学转化膜的腐蚀性能（英文）

作　　者：曾荣昌[1,2] 胡艳[1,2] 张芬[1,2] 黄原定 王振林[4] 李硕琦[1,2] 韩恩厚[5] 

机构地区：[1]山东科技大学材料科学与工程学院,青岛266590 [2]山东科技大学山东省矿山灾害预防控制重点实验室―省部共建国家重点实验室培育基地,青岛266590 [3]MagIC-Magnesium Innovation Center,Helmholtz-Zentrum Geesthacht Zentrumfür Material-und Küstenforschung GmbH [4]重庆理工大学材料科学与工程学院,重庆400054 [5]中国科学院金属研究所国家金属腐蚀控制工程技术研究中心,沈阳110016

出　　处：《Transactions of Nonferrous Metals Society of China》2016年第2期472-483,共12页中国有色金属学报（英文版）

基　　金：Project(51571134)supported by the National Natural Science Foundation of China;Project(2014TDJH104)supported by the SDUST Research Fund;the Joint Innovative Centre for Safe and Effective Mining Technology and Equipment of Coal Resources,Shandong Province,China;Project(cstc2012jj A50034)supported by the Natural Science Foundation of Chongqing,China

摘　　要：Zinc calcium phosphate （Zn-Ca-P） coating and cerium-doped zinc calcium phosphate （Zn-Ca-Ce-P） coating were prepared on AZ31 magnesium alloy. The chemical compositions, morphologies and corrosion resistance of coatings were investigated through energy-dispersive X-ray spectroscopy （EDS）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, electron probe micro-analysis （EPMA） and scanning electron microscopy （SEM） together with hydrogen volumetric and electrochemical tests. The results indicate that both coatings predominately contain crystalline hopeite （Zn3（PO4）2·4H2O）, Mg3（PO4）2 and Ca3（PO4）2, and traces of non-crystalline MgF2 and CaF2. The Zn-Ca-Ce-P coating is more compact than the Zn-Ca-P coating due to the formation of CePO4, and displays better corrosion resistance than the Zn-Ca-P coating. Both coatings protect the AZ31 Mg substrate only during an initial immersion period. The micro-galvanic corrosion between the coatings and their substrates leads to an increase of hydrogen evolution rate （HER） with extending the immersion time. The addition of Ce promotes the homogenous distribution of Ca and formation of hopeite. The Zn-Ca-Ce-P coating has the potential for the primer coating on magnesium alloys.在AZ31镁合金表面制备锌钙磷酸盐(Zn-Ca-P)涂层和铈掺杂锌钙磷酸盐(Zn-Ca-Ce-P)涂层。采用X射线能谱(EDS)、光电子能谱(XPS)、X射线衍射(XRD)、电子探针(EPMA)和扫描电镜(SEM)以及析氢实验和电化学测试技术研究涂层的化学成分、形貌和腐蚀性能。结果表明:两种膜层主要是磷酸盐(Zn_3(PO_4)_2·4H_2O)、Mg_3(PO_4)_2、Ca_3(PO_4)_2晶体簇和少量的MgF_2和CaF_2非晶颗粒组成。CePO_4的形成使Zn-Ca-Ce-P膜层更加致密,并具有更好的耐蚀性。两种涂层只能在浸泡前期为AZ31镁基体提供保护作用,随着浸泡时间延长,涂层与基体界面之间电偶腐蚀的发生加快了腐蚀速率。Ce的添加促进了Ca的均匀分布和磷化膜的形成。因此,Zn-Ca-Ce-P涂层具有作为镁合金底涂层的应用前景。

关 键 词：AZ31 magnesium alloy CERIUM zinc calcium phosphate chemical conversion coating corrosion resistance 

分 类 号：TG174.4[金属学及工艺—金属表面处理]