Van Sy Le, Quoc Binh Phan Minh, Lal Bhajan, Nguyen Quy Bau, Van Hung Tran, Panaitescu Casen, Nam Nguyen Dang
PetroVietnam University 762 Cach Mang Thang Tam Street, Long Toan Ward Ba Ria City 790000 Vietnam.
Chemical Engineering Department, Universiti Teknologi Petronas Bandar Seri Iskandar 32610 Perak Malaysia.
RSC Adv. 2020 Sep 16;10(57):34387-34395. doi: 10.1039/d0ra01956a.
In this study, strontium is used as an alloying element for improving the pitting resistance of Mg-5Al-4Sn based alloys in an alkaline solution. Potentiodynamic polarization measurements suggest that the addition of strontium increases the robustness of the pitting resistance as a result of the higher pitting potential and wider range of passive potential. Electrochemical impedance spectroscopy (EIS) confirms the formation of a solid passive film on the alloy surface due to a significant increase in the passive film and the charge transfer resistance, as well as lower film and double layer constant phase element magnitude values. Additionally, the potentiostatic polarisation results also show a lower passive current density and passive film stability, resulting in an increase in the breakdown time when the amount of strontium added to the alloy increases from 0.0 to 1.0 wt%. Furthermore, the scanning electron microscopy results indicate that insignificant corrosion is observed on alloy specimens containing strontium, whereas there is fierce corrosion on alloy based surfaces. This robust corrosion resistance could be attributed to the α-grain reduction and refined precipitates at the alloy grain boundaries, resulting in promoted formation of the passive film which is formed from a mixture of magnesium, aluminum and tin oxides/hydroxides, as confirmed by the X-ray photoelectron spectroscopy results.
在本研究中，锶用作合金元素，以提高Mg-5Al-4Sn基合金在碱性溶液中的耐点蚀性。动电位极化测量表明，由于点蚀电位较高且钝态电位范围较宽，添加锶提高了耐点蚀的稳定性。电化学阻抗谱（EIS）证实，由于钝化膜和电荷转移电阻显著增加，以及膜和双层常相位元件幅值较低，合金表面形成了固态钝化膜。此外，恒电位极化结果还表明，钝化电流密度和钝化膜稳定性较低，当合金中锶的添加量从0.0 wt%增加到1.0 wt%时，击穿时间增加。此外，扫描电子显微镜结果表明，含锶合金试样上观察到的腐蚀不明显，而基于合金的表面则存在剧烈腐蚀。这种强大的耐腐蚀性可归因于α晶粒减少和合金晶界处析出物细化，导致由镁、铝和锡氧化物/氢氧化物混合物形成的钝化膜的形成得到促进，X射线光电子能谱结果证实了这一点。
