AZ31镁合金钕基转化膜工艺与耐蚀性能研究

Preparation process and corrosion resistance of neodymium-based conversion coating on AZ31 magnesium

研究了AZ31镁合金钕基转化膜的制备工艺,并对膜层形貌、化学组成和耐腐蚀性能进行了分析。通过正交优化得到了钕基转化膜的4个工艺条件的最佳水平组合为Nd(NO3)3浓度为5g/L,H2O2浓度为5mL/L,成膜时间9min,成膜温度40℃。结果表明,采用最佳工艺得到的钕基转化膜层均匀且致密,其主要成分是Nd2O3和少量MgO。通过动电位极化曲线和析氢实验研究了钕基转化膜层对AZ31镁合金在3.5%(质量分数)NaCl溶液中耐蚀性能的影响,结果表明,钕基转化膜可以大大降低AZ31镁合金的腐蚀速率,当Nd(NO3)3浓度为5g/L时,钕基转化膜的腐蚀电流密度最小,耐腐蚀性能最好。

The forming process,morphology composition and corrosion resistance of neodymium-based(Ndbased)conversion coating on AZ31 magnesium was investigated.The best combination of forming process selected by orthogonal layout was 5g/L Nd(NO3)3,5mL/L H2O2 at 40℃for 9min.The results indicated that Nd-based conversion coating formed by the optimum process became uniform and compact,and was composed of Nd2O3 and MgO.The corrosion resistance of Nd-based conversion was examined by potentiodynamic polarization curves and hydrogen evolution test,the results showed that Nd-based conversion coating can efficiently slow down the corrosion rate of AZ31 magnesium.When Nd(NO3)3was 5g/L,Nd-based conversion coating performed the smallest corrosion current density and the best corrosion resistance.