New insights into the effect of Tris-HCl and Tris on corrosion of magnesium alloy in presence of bicarbonate,sulfate,hydrogen phosphate and dihydrogen phosphate ions  

作　　者：Lan-Yue Cui Yan Hu Rong-Chang Zeng Yong-Xin Yang Dan-Dan Sun Shuo-Qi Li Fen Zhang En-Hou Han 

机构地区：[1]College of Materials Science and Engineering,Shandong University of Science and Technology [2]State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology,Shandong University of Science and Technology [3]National Engineering Centre for Corrosion Control,Institute of Metals Research,Chinese Academy of Sciences

出　　处：《Journal of Materials Science & Technology》2017年第9期971-986,共16页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 51241001 and 51571134);SDUST Research Fund (No. 2014TDJH104)

摘　　要：In vitro degradation is an important approach to screening appropriate biomedical magnesium（Mg） alloys at low cost. However, corrosion products deposited on Mg alloys exert a critical impact on corrosion resistance. There are no acceptable criteria on the evaluation on degradation rate of Mg alloys. Understanding the degradation behavior of Mg alloys in presence of Tris buffer is necessary. An investigation was made to compare the influence of Tris-HCl and Tris on the corrosion behavior of Mg alloy AZ31 in the presence of various anions of simulated body fluids via hydrogen evolution, p H value and electrochemical tests.The results demonstrated that the Tris-HCl buffer resulted in general corrosion due to the inhibition of the formation of corrosion products and thus increased the corrosion rate of the AZ31 alloy. Whereas Tris gave rise to pitting corrosion or general corrosion due to the fact that the hydrolysis of the amino-group of Tris led to an increase in solution p H value, and promoted the formation of corrosion products and thus a significant reduction in corrosion rate. In addition, the corrosion mechanisms in the presence of Tris-HCl and Tris were proposed. Tris-HCl as a buffer prevented the formation of precipitates of HCO;, SO;,HPO;and H;PO;ions during the corrosion of the AZ31 alloy due to its lower buffering p H value（x.x）.Thus, both the hydrogen evolution rate and corrosion current density of the alloy were approximately one order of magnitude higher in presence of Tris-HCl than Tris and Tris-free saline solutions.In vitro degradation is an important approach to screening appropriate biomedical magnesium(Mg) alloys at low cost. However, corrosion products deposited on Mg alloys exert a critical impact on corrosion resistance. There are no acceptable criteria on the evaluation on degradation rate of Mg alloys. Understanding the degradation behavior of Mg alloys in presence of Tris buffer is necessary. An investigation was made to compare the influence of Tris-HCl and Tris on the corrosion behavior of Mg alloy AZ31 in the presence of various anions of simulated body fluids via hydrogen evolution, p H value and electrochemical tests.The results demonstrated that the Tris-HCl buffer resulted in general corrosion due to the inhibition of the formation of corrosion products and thus increased the corrosion rate of the AZ31 alloy. Whereas Tris gave rise to pitting corrosion or general corrosion due to the fact that the hydrolysis of the amino-group of Tris led to an increase in solution p H value, and promoted the formation of corrosion products and thus a significant reduction in corrosion rate. In addition, the corrosion mechanisms in the presence of Tris-HCl and Tris were proposed. Tris-HCl as a buffer prevented the formation of precipitates of HCO_3^-, SO_4^(2-),HPO_4^(2-) and H_2PO_4^- ions during the corrosion of the AZ31 alloy due to its lower buffering p H value(x.x).Thus, both the hydrogen evolution rate and corrosion current density of the alloy were approximately one order of magnitude higher in presence of Tris-HCl than Tris and Tris-free saline solutions.

关 键 词：Magnesium alloy Biomaterials TRIS Buffer CORROSION 

分 类 号：TG172[金属学及工艺—金属表面处理]