(1. 重慶理工大學 材料科學與工程學院，重慶 400054；
2. 重慶市特種焊接材料與技術高校工程研究中心，重慶 400054)
摘 要: 為改善鎂合金的耐蝕性能，采用化學沉積法在AZ31鎂合金表面制備了微-納級別尺度CaF2/MgF2復合膜層，分析該復合膜層的形貌、成分及相結構。采用Hank’s仿生溶液中浸泡和電化學測試技術，結合浸泡過程中膜層EIS譜和表面形貌成分的變化，研究CaF2/MgF2復合膜層的體外降解行為。結果表明：該復合膜層外層為納米尺度的片狀CaF2 晶體，內層為致密的MgF2轉化膜。CaF2膜層提高了單一氟轉化層的自腐蝕電位φcorr和極化電阻Rp，浸泡13 d后其電荷轉移電阻仍維持在1×104 Ω·cm2以上。試樣在Hank’s溶液中浸泡7 d后CaF2膜層發(fā)生局部溶解；9 d后在CaF2層局部脫落處，Cl-滲透到MgF2膜層而發(fā)生點蝕。
關鍵字: 鎂合金；CaF2/MgF2； 膜層；降解性能；生物材料
（1. School of Materials Science & Engineering, Chongqing University of Technology, Chongqing 400054, China;
2. Chongqing Municipal Engineering Research Center of Institutions of Higher Education for Special Welding Materials and Technology, Chongqing 400054, China）
Abstract:CaF2/MgF2 composite film was prepared on AZ31 magnesium alloy by chemical treatment to improve its corrosion resistance. The morphology and composition of the composite film were analyzed. The evolution of electrochemical impedance spectroscope (EIS) patterns and the change of the surface appearance and chemical composition of the composite film in Hank’s solutions were investigated to study the degradation process of film. The results show that the composite film consists of nanoscale flaky-like CaF2 crystals in out layer and compact MgF2 conversion film in inner layer. The corrosion potential φcorr and polarization resistance Rp of the fluorine conversion layer are improved by the CaF2 film. And the Rct of the composite coating after 13 d immersion in Hank’s solution is still above 1×104 Ω·cm2. CaF2 dissolves partially and adsorbs some of phosphate ions after 7 d immersion in Hank’s solution. After 9 d immersion, pitting corrosions occur because of the partial exfoliation of CaF2 film and the infiltration of Cl- into the MgF2 film.
Key words: magnesium alloy; CaF2/MgF2; coating; degradation behavior; biomaterial
