摘要
通过Machu测试、电化学交流阻抗(EIS)和扫描电子显微镜(SEM)等方法研究了添加氧化铈对AZ91D镁合金表面富镁涂层防护性能的影响.氧化铈添加量较少(0.1%,w)时,对涂层耐蚀性无影响;添加量过多(3%)时,涂层耐蚀性降低;添加氧化铈颗粒为0.5%时,涂层的阻抗增大,涂层电容降低,对AZ91D镁合金基体的保护性能明显提高.尽管添加氧化铈不改变富镁涂层对AZ91D镁合金的保护机制,但可显著延长涂层的服役寿命.氧化铈能够降低纯镁颗粒的电化学反应活性,使镁粉腐蚀速率降低,阴极保护时间延长.添加一定量氧化铈后,也有利于涂层屏蔽性能提高,氧化铈能降低AZ91D镁合金表面阳极腐蚀电流密度,提高镁合金腐蚀电位,从而有利于富镁涂层发挥对镁合金基体的阴极保护作用.
The effect of ceria particles on the corrosion resistance of Mg-rich primer on AZ91D magnesium alloy was studied using the Machu test, electrochemical impedance spectroscopy （EIS）, and scanning electron microscopy （SEM）. The results show that addition of a small amount of cerium oxide （0.1%, mass fraction） had no effect on the corrosion resistance of the coating, and the addition of excessive particles （3%） reduces the corrosion resistance of the coating. However, addition of 0.5% ceria particles to the Mg-rich primer can significantly improve the protection performance of the primer on AZ91D magnesium alloy. The coating resistance increases and coating capacitance decreases after the addition of ceria particles. Although the addition of ceria does not change the protection mechanisms of the magnesium-rich primer on AZ91D magnesium alloy, the electrochemical activity of the magnesium particles in the primer decreases and the service life of the Mg-rich primer is obviously prolonged. The ceria particles also result in an improved barrier effect. In addition, the presence of ceria particles on the AZ91D alloy surface can increase the corrosion potential and decrease the current density of the alloy, which is beneficial for cathode protection of the pure magnesium particles on the alloy substrate.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2012年第2期407-413,共7页
Acta Physico-Chimica Sinica
基金
教育部科学技术重点项目(108129)资助~~
关键词
耐蚀性
AZ91D镁合金
富镁涂层
氧化铈
电化学交流阻抗
Corrosion resistance
AZ91D magnesium alloy
Mg-rich primer
Ceria Electrochemical impedance spectroscopy
