磷酸钠在NaCl溶液中对AZ31镁合金的缓蚀作用

Inhibition Effect of Sodium Phosphate on the Corrosion of AZ31 Magnesium Alloy in 3.5 wt% NaCl Solution

采用电化学阻抗法、动电位极化曲线法、全浸泡失重法和扫描电镜,研究了在3.5%(质量分数)Na Cl溶液中磷酸钠(Na3PO4)对AZ31镁合金腐蚀的抑制作用。结果表明:Na3PO4对3.5%Na Cl溶液中的AZ31镁合金具有缓蚀作用,其缓蚀率随着Na3PO4含量增大逐渐提高,当Na3PO4质量浓度为1.0 g/L时,缓蚀率达到81.5%。结合扫描电镜分析表明,Na3PO4在镁合金表面形成含有Mg(OH)2和Mg3(PO4)2的保护层,这层致密的膜减少了基体与Cl-接触,抑制了镁合金的阳极反应。

The corrosion inhibition behaviors of sodium phosphate（SP） on AZ31 magnesium alloy in 3.5 wt% sodium chloride solution were investigated by electrochemical impedance spectroscopy（EIS）, potentiodynamic polarization curve, static weight-loss test and scanning electron microscope（SEM）. The results indicate that SP protects AZ31 magnesium alloy from corrosion in 3.5 wt% sodium chloride solution, and the inhibition efficiency increases with higher SP content. When the SP concentration is 1.0 g/L, the inhibition efficiency is up to 81.5%. Moreover, according to the results of SEM, it is found that the corrosion inhibition of AZ31 magnesium alloy by SP is attributed to the protective film containing Mg（OH）2 and Mg3（PO4）2 formed on the electrode surface. The compact film, which reduces the substrate contact with Cl-, thus inhibits the anodic reaction of the magnesium alloy.