Efect of K_(2)HPO_(4) Concentration on the Formation,Structure,Composition and Protectiveness of Conversion Coating Deposited on AZ31 Magnesium Alloy  

作　　者：Liping Wu Junhua Dong Xianfei Zheng Zhongying Wang Xiaoying Sun Xiuling Shang Wei Ke Changgang Wang 

机构地区：[1]Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [2]Changda Hospital,Anshan 114000,China [3]Ansteel Group Corporation General Hospital,Anshan 114000,China [4]Guangdong Midea Air-Conditioning Equipment CO.,LTD,Foshan 528311,China

出　　处：《Acta Metallurgica Sinica(English Letters)》2025年第3期481-496,共16页金属学报(英文版)

基　　金：financially supported by the National Natural Science Foundation of China(No.52373322).

摘　　要：In deaerated 0.05 M,0.1 M,0.2 M and 0.5 M K_(2)HPO_(4) solutions with pH 9.5,AZ31 magnesium(Mg)alloy was subjected to potentiostatic polarization at−0.8 VSCE to deposit a phosphate conversion coating.The morphology,structure,chemical composition,and protective performance of the conversion coating during the formation process were characterized.The results showed that amorphous Mg(OH)_(2) and MgHPO_(4) and crystallized KMgPO_(4)·6H2O(struvite-K)were successively deposited on the surface of AZ31 Mg alloy in the four solutions.MgHPO_(4) was converted from Mg(OH)_(2),while struvite-K was transformed from MgHPO_(4).The distribution of Mg(OH)_(2),MgHPO_(4) and struvite-K along the thickness of the coating difers with K_(2)HPO_(4) concentration.As the concentration of K_(2)HPO_(4) increased,the coating time was gradually shortened,and the coating was gradually thinned.Meanwhile,the ratio of the nucleation rate to the growth rate of struvite-K crystal nuclei increased,resulting in a decrease in the size of struvite-K crystal.When the concentration of K_(2)HPO_(4) increased from 0.05 to 0.1 M,the content of struvite-K increased,and the protective performance of the coating was enhanced.However,as the concentration of K_(2)HPO_(4) continued to increase to 0.5 M,the content of struvite-K and the protective performance of the coating decreased.

关 键 词：Magnesium alloy Potentiostatic technique Phosphate coating 

分 类 号：TG1[金属学及工艺—金属学]