Xu Yuqing, Song Guangling, Zheng Dajiang, Liu Changsheng, Han Enhou
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China.
Center for Marine Materials Corrosion and Protection, Xiamen University, Xiamen 361005, China.
Materials (Basel). 2024 Jul 22;17(14):3623. doi: 10.3390/ma17143623.
The application of organic coatings is the most cost-effective and common method for metallic equipment toward corrosion, whose anti-corrosion property needs to be improved and evaluated in a short time. To rapidly and rationally assess the anti-corrosion property of organic coatings in the ocean splash zone, a new accelerated test was proposed. In the study, the corrosion protection property of the coating samples was measured by an improved AC-DC-AC test in a simulated seawater of 3.5 wt.% NaCl solution, a simulated ocean splash zone test and a new accelerated test combining the above two tests. The results showed that the corrosion rate of the coating samples was high in the improved AC-DC-AC test, which lost its anti-corrosion property after 24 cycles equal to 96 h. The main rapid failure reason was that the time of the water and corrosive media arriving at the carbon steel substrate under the alternating cathodic and anodic polarization with symmetrical positive and negative electric charges was shortened. The entire impedance of the coating samples was improved by about 1.6 times more than that in the initial early time in the simulated ocean splash zone test, which was caused by the damage effect from the salt spraying, drying, humidifying, salt immersion, high temperature and UVA irradiation being weaker than the enhancement effect from the post-curing process by the UVA irradiation. In the new accelerated test, the samples lost their corrosion resistance after 12 cycles equal to 288 h with the fastest failure rate. On account of the coupling process of the salt spraying, drying, humidifying, salt immersion, high temperature combined with the cathodic and anodic polarization and the UVA irradiation, the penetration and transmission rate of water and corrosive media in the coating were further accelerated, the corrosion rate on the carbon steel substrate was reinforced even larger and the destruction of the top polymer molecules was more serious. The new accelerated test showed the strongest damage-acceleration effect than that in the other two tests.
有机涂层的应用是金属设备防腐蚀最具成本效益且最常用的方法，其防腐性能需要在短时间内得到改善和评估。为了快速、合理地评估有机涂层在海洋飞溅区的防腐性能，提出了一种新的加速试验方法。在该研究中，通过在3.5 wt.% NaCl模拟海水中进行改进的交流-直流-交流试验、模拟海洋飞溅区试验以及结合上述两种试验的新加速试验来测量涂层样品的耐腐蚀性能。结果表明，在改进的交流-直流-交流试验中，涂层样品的腐蚀速率较高，在24个循环（相当于96小时）后失去防腐性能。主要的快速失效原因是在对称正负电荷交替阴极和阳极极化下，水和腐蚀性介质到达碳钢基体的时间缩短。在模拟海洋飞溅区试验中，涂层样品的整体阻抗比初始早期提高了约1.6倍，这是由于盐雾、干燥、加湿、盐浸、高温和紫外线照射的破坏作用弱于紫外线照射后固化过程的增强作用。在新加速试验中，样品在12个循环（相当于288小时）后失去耐腐蚀性，失效速率最快。由于盐雾、干燥、加湿、盐浸、高温与阴极和阳极极化以及紫外线照射相结合的耦合过程，水和腐蚀性介质在涂层中的渗透和传输速率进一步加快，碳钢基体上的腐蚀速率进一步增大，顶部聚合物分子的破坏更严重。新加速试验显示出比其他两种试验更强的损伤加速效应。
