中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 25 No. 6 June 2015 |
（1. College of Materials Science and Engineering, Shandong University of Science and Technology,
Qingdao 266590, China;
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, Qingdao 266590, China;
3. Institute of Metals Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:In situ growth of nano-sized layered double hydroxides (LDH) conversion film on AZ31 alloy was synthesized by a urea hydrolysis method. The formation mechanism of the film was proposed. Firstly, the dissolved Mg2+ ions deposited into a precursor film consisted of MgCO3 and Mg5(CO3)4(OH)2· 4H2O; secondly, the precursor translated into the crystalline Mg(OH)2 in alkaline conditions; finally, the Mg2+ ions in Mg(OH)2 were replaced by Al3+ ions, Mg(OH)2 translated into the more stable LDH structure, simultaneously, the OH- ions in the interlayer were exchanged by , thus led to the formation of the LDH (Mg6Al2(OH)16CO3·4H2O) film. The results indicated that the LDH film characterized by interlocking plate-like nanostructures and ion-exchange ability significantly improved the corrosion resistance of the AZ31 Mg alloy.
Key words: magnesium alloy; hydrotalcite; conversion film; corrosion resistance; ion-exchange
