偏钒酸铵及固溶退火处理对AZ31镁合金电化学性能的影响

Influences of NH_4VO_3 and Solution Treatment on Electrochemical Properties of AZ31 Magnesium Alloy

为了改善AZ31镁合金在3.5wt%NaCl溶液中的抗腐蚀和活化性能,通过浸泡、电化学阻抗谱、恒电流和动电位极化扫描试验研究了偏钒酸铵及固溶退火处理对AZ31镁合金自腐蚀和电化学性能的影响。结果表明:偏钒酸铵能抑制AZ31镁合金的腐蚀,当0.5%偏钒酸铵加入到3.5wt%NaCl溶液时,合金的缓蚀率高(65.7%),自腐蚀电流小,为0.0033 mA/cm2。在-1.0 V下合金的电流密度高达30.0 mA/cm2,开路电位Eocp和活化电位Eact分别为-1.60 V和-1.35V。AZ31镁合金经350℃固溶4、8、16和24h,与铸态合金相比,其放电电位和耐蚀性有所降低。可是,随固溶时间延长,合金元素固溶度增大,结果导致合金放电性能和耐蚀性能提高。

In order to improve the anti-corrosion and activation property of AZ31 magnesium alloy in 3.5wt%NaC1 solution, the effects of NI-LVO3 and solution annealing treatment on self-corrosion and electrochemical properties of AZ31 magnesium alloy were investigated by immersion tests, electrochemical impedance spectroscopy tests, galvanostatic and potentiodynamic polarization tests. The results show that the corrosion ofAZ31 magnesium alloy can be inhibited by NtLVO3. Corrosion-inhibition ratio is high （65.7%）and self-corrosion current is low （0.0033 mA/cm2）, and its activation properties is improved when 0.5%NI-LVO3 is added into 3.5%NaCl solution. The current density of the alloy reaches to 30.0 mA/cm2 at -1.0 V; open circuit potential Eo~ and activation potential Esct are -1.60 V and -1.35 V, respectively. After solution treatment at 350℃ for 4, 8, 16 and 24 h, compared with the as-cast alloy, the discharge potential and corrossion resistance of the solution-treated alloy are decreased. However, along with the extending of the solution treatment time, the solubility of alloying element increases. The results lead to the increase of the discharge ability and the corrosion resistance.