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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。
The Zn-Ca-P coating and the Ce-doped Zn-Ca-Ce-P coating were prepared on AZ31 magnesium alloy. The chemical composition of the coating was studied by X-ray diffraction (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), electron probe (EPMA) and scanning electron microscopy (SEM) Topography and corrosion properties. The results show that the two films are mainly composed of phosphate (Zn_3 (PO_4) _2 · 4H_2O), Mg_3 (PO_4) _2, Ca_3 (PO_4) _2 crystal clusters and a small amount of MgF_2 and CaF_2 amorphous particles. The formation of CePO 4 makes the Zn-Ca-Ce-P film more dense and has better corrosion resistance. Both coatings only provide protection for the AZ31 magnesium matrix during the pre-soaking period. As the immersion time is extended, galvanic corrosion between the coating and the matrix interface accelerates the corrosion rate. The addition of Ce promoted the uniform distribution of Ca and the formation of phosphating film. Therefore, Zn-Ca-Ce-P coating has the potential application as a magnesium alloy primer.