单宁酸复配缓蚀剂在铁质文物上的应用研究

Application of Modified Tannic Inhibitor in the Iron Relics

目的通过复配的方法改善单宁酸单一缓蚀剂的缺点,以提高对铁质文物的缓蚀效果。方法采用失重实验、扫描电镜显微观察、动电位极化法等,对比和评估了单宁酸和单宁酸复配缓蚀剂对5种铁质文物模拟样品的缓蚀效果,并在铁质文物上进行了应用试验。结果在3.5%Na Cl水溶液的腐蚀体系中,单宁酸复配缓蚀剂对低硫铸铁的缓蚀效果优异,对高硫铸铁的缓蚀效果略低。用单宁酸缓蚀后的试样表面呈斑驳膜层,成膜不牢固,用单宁酸复配缓蚀剂缓蚀后的试样表面成膜均匀、稳定。添加硅酸钠、磷酸二氢锌和乙醇胺的单宁酸改进配方使试样出现钝化现象,其腐蚀电流比空白样和单宁酸的腐蚀电流均有大幅降低。在铁质文物上的实际应用结果表明,采用单宁酸复配缓蚀剂处理的铁质文物的耐腐蚀性比单宁酸处理的更好。结论单宁酸复配缓蚀剂解决了单宁酸的酸性对铁质文物造成的潜在影响,克服了单宁酸成膜不完整和不牢固,以及改变文物外观颜色的缺点,并大幅提升了缓蚀效率。

The work aims to make up the shortcomings of the single tannic inhibitor through modification, so as to improve its corrosion-inhibition efficiency on the iron relics. The inhibition efficiency of the tannic acid and its modified inhibitor on five kinds of simulated iron relic samples was compared and evaluated through the weight loss experiment, SEM-EDS and potentiodynamic polarization method. These inhibitors were applied for tests on the iron relics. The modified tannic inhibitor had excellent inhibition effect to the low sulfur cast iron, slightly lower for the high sulfur cast iron in the corrosion system of 3.5% NaC1 aqueous solution. The inhibition film layer was uneven and unstable after inhibited by tannic acid, but homogeneous and stable after inhibited by modified tannic inhibitor. The passivation of the samples occurred due to the improved formula of tannic acid containing sodium silicate, zinc dihydrogen phosphate and ethanolamine. Its corrosion current was greatly lower than those of the non-inhibitor solution and tannic acid. The practical application results showed that the iron relics treated with modified tannic inhibitor had better corrosion resistance than those treated with tannic acid. The modified tannic inhibitor has solved the problem that the acidity of tannic acid potentially impacts the iron relics, overcome the shortage of incomplete and unstable thin film made by the tannic acid, and of changing the appearance color of cultural relics, and greatly improved the inhibition efficiency.