Sn对Mg-Al-Sn-Zn系海水电池用镁阳极材料组织及电化学性能的影响

Effect of tin on the microstructure and electrochemical properties of Mg-Al-Sn-Zn magnesium alloy anodic materials for seawater batteries

采用金相显微镜、X射线衍射、扫描电镜和结合能谱仪研究了Sn对镁阳极材料显微组织、相结构、表面形貌及成分分布的影响;并通过恒电流法、动电位极化法和排水集气法等研究了该镁合金的腐蚀行为和电化学性能.结果表明:合金元素Sn的加入可以抑制棒状β-Mg17Al12相沿晶界析出,随着Sn含量的增大,颗粒相Mg2Sn增多;均匀化处理使大部分β-Mg17Al12相溶解,而残留Mg2Sn未溶相.Sn的加入可以提高镁合金自腐蚀电位和析氢率,当Sn质量分数为1%时镁合金阳极的放电电压和电流效率最大.析氢率随电流密度的增大而增大,当电流密度为20mA.cm-2时电流效率最高,可达82.28%.腐蚀产物主要成分为MgO和Al2O3,且疏松,易脱落,使镁合金阳极的工作电位负而且稳定,可促进电池反应深入进行.

The morphologies, microstructure and composition distribution of magnesium alloy anodic materials for seawater batteries were studied by metallographic microscopy, X-ray diffraction （XRD） , scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. The corrosion behavior and electrochemical properties of the Mg alloys were also investigated by the constant current method, potential polarization and collecting gas through drainage. The results showed that tin restrained β-Mg17 Al12 phase precipi- tation along grain boundaries. With the content of tin increasing, granular Mg2Sn phase improved. After uniform heat treatment, most of β-Mg17Al12 phase dissolved, but most of Mg2Sn phase did not. Tin could improve the self-corrosion potential and the release hydrogen rate. The magnesium alloy anode with 1% tin had high discharge potential and current efficiency. With the current density increasing, the release hydrogen rate augmented. The current efficiency reached 82.28% at 20mA·cm ^-2. The main compositions of the corrosion products were MgO and Al2O3 which were easily peeled off. As a result, more negative and stable work potential was produced and the reaction was accelerated continuously.