热镀锌层在模拟沿海工业大气环境中的腐蚀行为

通过无浸润式干湿交替循环加速腐蚀试验模拟热镀锌层在沿海工业大气环境中的腐蚀过程. 采用腐蚀失重和动态极化曲线，结合扫描电子显微镜(SEM)、能谱分析仪(EDS)、X射线衍射(XRD)和极化曲线分别对腐蚀24，48，96，192，336和672 h的热浸镀锌钢试样进行测试分析. 结果表明,镀锌层的腐蚀动力学变化规律符合经验公式D=Btn，腐蚀速率随时间延长先减小后增大. 腐蚀产物在96 h前均匀致密，腐蚀过程受阴极扩散过程控制，96 h后腐蚀过程受阳极过程控制. 含Cl元素的腐蚀产物NaZn4SO4Cl(OH)6·6H2O和Zn12(OH)15Cl3(SO4)3·5H2O对镀锌层的保护作用比初期产物Zn5(CO3)2(OH)6等保护作用差.

Corrosion behavior of hot dip galvanized coating exposed in a simulated coastal-industrial atmosphere

The corrosion process of hot-dip galvanized coating in a simulated coastal-industrial atmosphere was investigated by means of an unsaturated dry-wet alternating cycle accelerated corrosion test. By using weight loss measurement and potentiodynamic polarization, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffractometry (XRD) analyzed corrosion behavior of hot-dip galvanized coating exposed after 24, 48,96, 192, 336, and 672 h. The results show that corrosion kinetics followed the empirical equation D=Btn, and there is a corrosion rate transition from corrosion acceleration to deceleration. Before 96 h the corrosion process is controlled by the cathode diffusion process, while after 96 h by the anodic. The protectiveness of corrosion products NaZn4SO4Cl(OH)6·6H2O and Zn12(OH)15Cl3(SO4)3·5H2O which containing Cl is worse than that of initial products Zn5(CO3)2(OH)6.