中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 23 No. 11 November 2013 |
（1. College of Material Science and Engineering,
Shandong University of Science and Technology, Qingdao 266590, China;
2. State Key Laboratory for Corrosion and Protection, Institute of Metals Research,
Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The influence of phosphating bath at different temperatures on the formation and corrosion property of calcium-modified zinc phosphate conversion coating (Zn-Ca-P coating) on Mg-Li-Ca alloy was investigated. The morphologies, elemental distribution and chemical structures of the coatings were examined via SEM, EPMA, EDS, XRD and FT-IR. The corrosion resistance was assessed by hydrogen evolution, potentiodynamic polarization and EIS. The results show that the coating is composed of single element Zn and ZnO at below 45 °C; whereas the coatings are predominantly characterized by Zn3(PO4)2·4H2O and small amount of element zinc and ZnO at above 50 °C. Mg-Li-Ca alloy with Zn-Ca-P coatings prepared at 55 °C has the highest corrosion resistance. However, the hydrogen evolution rates of the coatings obtained at 40-50 °C is accelerated due to the galvanic corrosion between the imperfection of the single element Zn coating and the Mg substrate.
Key words: magnesium alloy; lithium; calcium; phosphate conversion coating; corrosion; biomaterial
