Influence of pH on the Formation, Composition and Protectiveness of Fluoride Conversion Film Deposited on AZ31 Magnesium Alloy in KF Solution

作     者：Liping Wu Chen Liu Jie Wei Junhua Dong Lin Zhao Chao Li Wei Ke Yiqing Chen Changgang Wang Liping Wu;Chen Liu;Jie Wei;Junhua Dong;Lin Zhao;Chao Li;Wei Ke;Yiqing Chen;Changgang Wang

作者机构：Shenyang National Laboratory for Materials ScienceInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China State Key Laboratory of Metal Material for Marine Equipment and ApplicationAnshan114009China 

出 版 物：《金属学报:英文版》 (Acta Metallurgica Sinica(English Letters))

年 卷 期：2023年第36卷第9期

页      面：1397-1408页

核心收录：

学科分类：0806[工学-冶金工程] 08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 

基　　金：This work was finically supported by the National Natural Science Foundation of China(No.51701221) the Major R&D Project of Liaoning province(2020JH1/10100001) the State Key laboratory of Metal Material for Marine Equipment and Application(No.SKLMEA-K201907) Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2019193,KGFZD-135-19-02) 

主　　题：Magnesium alloy Potentiostatic deposition Fluoride film KF solution 

摘      要：In deaerated 0.1 M KF solution at pH 5, pH 7.5 and pH 9, fluoride films were deposited on AZ31 magnesium (Mg) alloy at − 1.4 V vs saturated calomel electrode (SCE). The morphology, phase composition, elemental and compositional depth distribution of different fluoride films and their influences on the corrosion resistance of AZ31 Mg alloy were explored in detail. The results indicated that the films deposited at weak acidic and nearly neutral pH consisted of two layers with amorphous Mg(OH)_(2) and MgF_(2) as the inner layer, and Mg(OH)_(2), MgF_(2) and KMgF_(3) crystals the outer layer. The film deposited at alkaline pH was a monolayer structure consisting of amorphous Mg(OH)_(2) as the major constitute and MgF_(2) as the minor constitute. The protectiveness of fluoride film was intimately related to its composition and structure. The content and crystal regularity of KMgF_(3) were the two main factors influencing the protectiveness of fluoride film. The fluoride film deposited at pH 7.5 offered the best protection to AZ31 Mg alloy.