J. Mater. Sci. Technol. ›› 2017, Vol. 33 ›› Issue (9): 971-988.DOI: 10.1016/j.jmst.2017.01.005

Special Issue: 2017腐蚀与防护专辑

• Orginal Article • Previous Articles     Next Articles

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

Cui Lan-Yueab, Hu Yanab, Zeng Rong-Changab*(), Yang Yong-Xinab, Sun Dan-Dana, Li Shuo-Qiab, Zhang Fenab, Han En-Houc   

  1. aCollege of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
    bState 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, Qingdao 266590, China
    cNational Engineering Centre for Corrosion Control, Institute of Metals Research, Chinese Academy of Sciences, Shenyang 110016, China
  • Received:2016-08-21 Revised:2016-11-22 Accepted:2016-12-05 Online:2017-09-20 Published:2017-10-16
  • Contact: Zeng Rong-Chang
  • About author:

    1 The authors contributed equally to this work.

Abstract:

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, pH 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 pH 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 HCO3-, SO42-, HPO42- and H2PO4- ions during the corrosion of the AZ31 alloy due to its lower buffering pH 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.

Key words: Magnesium alloy, Biomaterials, Tris, Buffer, Corrosion