ABSTRACT

Corrosion behaviour of Zn exposed in the coastal zone of the Nansha Islands for nearly 3 years was studied through gravimetric, and morphological observations, component analysis, and electrochemical measurements. The kinetics of the corrosion process is linear, indicating that the corrosion products have no significant protective effect on the substrate. The average corrosion rate (V_d) fluctuated with time, which was attributed to the different morphologies of corroded product film formed on the skyward and field-ward sides. Corrosion products formed on the skyward side had a three-layer structure in which Zn₅(OH)₈Cl₂·H₂O was enriched in both the outer and inner layer, NaZn₄Cl(OH)₆SO₄·6H₂O was enriched in the intermediate layer. Simultaneously, corrosion products formed on the field-ward side had a double-layer structure, in which Zn₅(OH)₈Cl₂·H₂O was concentrated in the inner layer and NaZn₄Cl(OH)₆SO₄·6H₂O was enriched in the outer layer. The degrees of corrosion on both sides at different exposure periods were also discussed.

摘要

通过重量和形态观察、成分分析和电化学测量研究了近3年暴露在南沙群岛沿海地区的锌的腐蚀行为。腐蚀过程的动力学是线性的，表明腐蚀产物对基体没有明显的保护作用。平均腐蚀速率（V _d）随时间波动，这归因于在天空侧和向场侧形成的腐蚀产物膜的不同形态。朝天一侧形成的腐蚀产物呈三层结构，外层和内层均富集Zn ₅ (OH) ₈ Cl ₂ ·H _{2 O，NaZn 4}Cl(OH) ₆ SO ₄ ·6H ₂ O在中间层富集。同时，向场侧形成的腐蚀产物具有双层结构，其中Zn ₅ (OH) ₈ Cl ₂ ·H ₂ O集中在内层，NaZn ₄ Cl(OH) ₆ SO ₄ ·6H ₂ O在外层富集。还讨论了不同暴露时间下两侧的腐蚀程度。