AZ63镁合金在氯化钠溶液中的孔蚀及缓蚀研究

Study on Pitting and Corrosion Inhibition of AZ63 Magnesium Alloy in Sodium Chloride Solution

通过失重法、线性电位扫描、动电位扫描、电化学阻抗谱等分析手段,研究AZ63镁合金在NaCl溶液中的孔蚀行为,考察缓蚀剂磷酸钠和复配剂氟化钠对AZ63镁合金孔蚀的影响,并用扫描电镜观察AZ63镁合金的腐蚀形貌。结果表明:NaCl溶液浓度增加会使镁合金的孔蚀倾向增大,但NaCl质量分数超过5.5%后,击穿电位与再钝化电位差值的下降幅度显著减小;Na3PO4能够有效阻止AZ63镁合金在氯化钠溶液中的腐蚀,PO43-浓度增加使E b值增大,2.0%Na3PO4对镁合金的缓蚀率达到92.8%;NaF溶液与Na3PO4复配可减缓AZ63镁合金的腐蚀速度,添加0.16%NaF时,极化电阻增大至3092Ω·cm2。

Pitting behavior of AZ63 magnesium alloy in sodium chloride solution was investigated by weight-loss mea- surement, linear sweep voltammetry （ LSV）, staircase voltammetry （SCV） and electrochemical impedance spectroscopy （EIS）. Influence of trisodium phosphate and sodium fluoride on the corrosion inhibition of AZ63 magnesium alloy was observed. The surface morphology of the alloy was observed with scanning electron microscope （SEM）. The results show that higher Cl- concentration results in higher pitting corrosion tendencies. However, the values of Eb-E decreased gradually when Cl- concentration went beyond 5.5%. The pitting corrosion tendencies of the alloy in high sodium chloride concentration solution were greater than in lower concentration solution. The corrosion rate of magnesium alloy could decrease by using trisodium phosphate as corrosion inhibitor, and pitting potential Eb increased with the increasing of PO43- concentration. When the mass fraction of trisodium phosphate was 2.0 % , the inhibitive efficiency of AZ63 magnesium alloy was 92.8 %. The corrosion rate of AZ63 magnesium alloy decreased, and the resistance value was 3092 Ω· cm2 when 0.16% sodium fluoride and 2.0% N3PO4 were used as compound agent.