pH-dependent electrochemical behaviour of Al3Mg2 in NaCl solution
pH-dependent electrochemical behaviour of Al3Mg2 in NaCl solution
复制标题
Al3Mg2 在 NaCl 溶液中的 pH 依赖性电化学行为
DOI：
10.1016/j.apsusc.2018.10.193
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发表时间：
2019-02-15
影响因子：
6.7
通讯作者：
Wang, G.
中科院分区：
文献类型：
--
作者：
Li, Y.;Cai, J. M.;Wang, G.
研究了pH值对AA 5000系列合金中β相（Al 3 Mg 2）电化学行为的影响及其在NaCl溶液中的腐蚀作用。采用扫描振动电极技术（SVET）研究了合成的Al 3 Mg 2金属间化合物颗粒与Al在0.01 M NaCl溶液中在2-12的宽pH窗口内的电偶腐蚀行为。结果表明，在pH 2 ~ 10.5范围内，Al_3 Mg_2作为阳极，在pH 12范围内，Al_3 Mg_2作为阴极。通过动电位极化曲线和电化学阻抗谱研究了Al 3 Mg 2合金的耐蚀性能。利用共聚焦激光扫描显微镜（CLSM）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）对样品进行了表面表征。这些结果表明，Al 3 Mg 2在pH 2时表现出Al和Mg元素的活性溶解，而在pH 3.5-12时发生选择性溶解。在pH3.5 -10.5范围内，偏离中性pH值会导致Mg元素的选择性溶解速率显著增加，从而导致腐蚀表面外层粗糙，内层相对致密。pH值为12时，Al元素的选择性溶解占主导地位，形成致密的Mg（OH）（2），使Al 3 Mg 2表面达到完全钝化。本工作有助于进一步了解AA 5000系列合金中β相的电化学行为。
The effects of pH on the electrochemical behaviour of beta-phase (Al3Mg2) and its role in corrosion of AA5000 series alloys in NaCl solution were investigated. The galvanic corrosion behaviour of synthesized Al3Mg2 intermetallic particle coupled with Al in 0.01 M NaCl solution over a wide pH window of 2-12 was studied using the scanning vibrating electrode technique (SVET). The results show that bulk Al3Mg2 acts as anode at pH 2-10.5, while cathode at pH 12. The corrosion resistance properties of bulk Al3Mg2 were then evaluated via potentiodynamic polarization and electrochemical impedance spectroscopy tests. Surface characterization were carried out by confocal laser scanning microscope (CLSM), scanning electron microscope (SEM) and X-ray photoelectron spectrometry (XPS). These results indicate that Al3Mg2 exhibits active dissolution of both Al and Mg elements at pH 2, while selective dissolution occurs at pH 3.5-12. At pH 3.5-10.5, any deviation from neutral pH causes a significant increase in the selective dissolution rate of Mg element, which results in a rough outer layer and a relatively compact inner layer of corrosive surface. At pH 12, the selective dissolution of Al element becomes dominant and the formation of compact Mg(OH)(2) achieves complete passivity on the surface of Al3Mg2. This work contributes to further understanding of the electrochemical behaviour of beta-phase in AA5000 series alloys.