NaCl 溶液中回收AZ31 镁合金的腐蚀和电化学特性

利用熔炼工艺,将回收镁合金型材(RMA)进行了制备。在回收过程中,添加适量的Al、MnCl_2,最终得到合金AZ31,其中各元素质量分数如下:Al 3.31%、Zn 0.82%、Mn 0.27%、Fe 0.002%、Cu 0.004%、Ni 0.000 7%,剩余为Mg。研究了RMA的结构、在NaCl溶液中的腐蚀和电化学特性,并与商业化镁合金(CMA)进行了对比。X射线衍射仪和金相显微镜表明, RMA和CMA主要由镁基底组成,另外还有少量的Mg_(17)Al_(12)第二相。在NaCl溶液中进行的腐蚀试验和电化学特性研究表明, RMA抗腐蚀特性差于CMA,这可能与RMA中有更多的第二相有关。将两种合金作为镁电池原型器件的负极材料,进行放电性能测试。结果表明, RMA的放电时间和放电容量优于CMA。当NaCl电解质溶液浓度从0.6 mol/L增加至0.9 mol/L时,两种合金材料的放电时间和放电容量都得到了增加。

Corrosion and Electrochemical Performances of Recycled AZ31 Magnesium Alloy in NaCl Solutions

Recycled magnesium alloys (RMA) were prepared by smelting method. In the recycling process, alloy of AZ31 was obtained by adding proper Al and MnCl₂ and the mass fraction of each element was as follows: Al 3.31%, Zn 0.82%, Mn 0.27%, Fe 0.002%, Cu 0.004%, Ni 0.0007% and the rest of Mg. The structure, corrosion and electrochemical properties in NaCl solutions of RMA were investigated and compared to those of the commercial magnesium alloys (CMA). X-ray diffractometry and metallomicroscope show that the main phases of RMA and CMA are Mg matrix and minor phases are second phases Mg₁₇Al₁₂. Due to more second phases, RMA presents the worse anti-corrosion properties than CMA according to corrosion experiment and electrochemical properties in the solution of NaCl. Two alloys were used as the anode materials for the prototype magnesium battery to test the discharge performance. The results show that the discharge time and discharge capacity of RMA are better than CMA. When the concentration of NaCl electrolyte solution increased from 0.6 mol/L to 0.9 mol/L, the discharge time and capacity of both alloys increased.