镁合金表面硅酸盐封闭磷化膜的腐蚀失效行为  

Corrosion Failure Behavior of Silicate Sealed Phosphating Film on Sur‐face of Magnesium Alloy

作　　者：陈力[1] 陈玉峰[1] 张鉴达 CHEN Li;CHEN Yufeng;ZHANG Jianda(Shijiazhuang Vocational and Technical College,Shijiazhuang 050000,China;Hebei Normal University,Shijiazhuang 050000,China)

机构地区：[1]石家庄职业技术学院,河北石家庄050000 [2]河北师范大学,河北石家庄050000

出　　处：《电镀与精饰》2022年第1期57-62,共6页Plating & Finishing

基　　金：河北省高等学校科学技术研究项目(Z2019033)。

摘　　要：在镁合金表面制备磷化膜并对其进行硅酸盐封闭,然后以3.5%氯化钠溶液作为腐蚀介质浸泡不同时间,采用全浸腐蚀法和电化学工作站考察硅酸盐封闭磷化膜的腐蚀失效行为。结果表明,浸泡48 h以内,磷化膜的腐蚀程度较轻,晶粒间的缝隙较少,其电化学阻抗谱表现为单一容抗弧且容抗弧半径相差不大,能较好的抑制腐蚀发生。随着浸泡时间延长,磷化膜表面锈斑明显增多且颜色加深,腐蚀面积呈大幅度增加的趋势,表面较粗糙、晶粒间形成了细长的缝隙,电荷转移电阻和缓蚀效率都呈现先大幅度降低然后基本不变的趋势,耐蚀性能逐步下降。当浸泡超过168 h后,磷化膜遭到严重破坏,表面几乎完全覆盖锈斑且形成了贯穿性缝隙,电化学阻抗谱表现为容抗弧和感抗弧特征,其耐蚀性能很差处于失效状态,对镁合金起不到防护作用。Phosphating film was prepared on the surface of magnesium alloy and then sealed with sili-cate,and the corrosion failure behavior of silicate sealed phosphating film was investigated by total im-mersion corrosion method and electrochemical workstation taking 3.5%sodium chloride solution as cor-rosion medium immersed for different time.The results showed that the corrosion degree of phosphating film was light and the gaps between the grains was less when immersed less than 48 h,the electrochemi-cal impedance spectrum showed a single capacitive arc,and the radius of capacitive arc had little differ-ence,indicating that the phosphating film could effectively inhibit the corrosion.With the prolongation of immersion time,the rust spots on the surface of phosphating film increased obviously and the color deepened,the corrosion area increased greatly,and the surface was rough and the thin cracks were formed between the grains.Moreover,the charge transfer resistance and corrosion inhibition efficiency both decreased greatly at first and then basically remained the same,indicating that the corrosion resis-tance weakened gradually.After immersed for more than 168 h,the phosphating film was seriously damaged and its surface was almost completely covered with rust spots and formed penetrating cracks.The electrochemical impedance spectra showed capacitive arc and inductive arc characteristics,its cor-rosion resistance was poor and was in failure state,and it could not play a protective effect on magnesium alloy.

关 键 词：硅酸盐封闭磷化膜 镁合金 腐蚀失效行为 防护作用 缓蚀效率 

分 类 号：TB43[一般工业技术]