Effect of Na₂MoO₄ on bond strength of adhesive-bonded phosphate coated magnesium AZ31 sheets

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• 作者：Ting-Ting Wan^a ; Zhong-Xia Liu^a ; ^{liuzhongxia@zzu.edu.cn} ; Ming-Zhe Bu^a ; Pei-Chung Wang^b
• 关键词：AZ31 magnesium sheets ; Surface treatment by chemical solutions ; X-ray photoelectron spectroscopy ; Lap-shear ; Durability
• 刊名：International Journal of Adhesion and Adhesives
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：40
• 期：Complete
• 页码：38-48
• 全文大小：1575 K

文摘

A pretreat phosphate solution having the formulation of KMnO₄, K₂HPO₄, Na₂SiO₃, NaF and Na₂MoO₄ was developed to improve the strength of adhesive-bonded magnesium AZ31 joints. The phosphate coating which has the magnesium phosphate, MgO, Mg (OH)₂, MgF₂ and minor Al₂O_3,, Al(OH)₃ Al_0.35-0.55Si_0.10-0.48P_0.13-0.35O_2.1-2.2 and, Al_0.35Si_0.48P_0.18O_2.2, and Al_0.52P_0.48O_2.2 was formed on the surface of the magnesium AZ31 after treatment. The additives Na₂MoO₄ in a phosphate-permanganate solution mainly act as an accelerator to speed up the coating formation. The combination of Na₂MoO₄ and NaF improves significantly the corrosion resistance of the magnesium AZ31 and performance of adhesive bonded joints. The joint strength and durability of the bonded Mg AZ31 joints in hot-humid environmental condition are superior to that of the phosphate treated (RPT) and CrO₃ etching (CET) pretreated samples.