电场作用下薄层液膜中缓蚀剂的吸脱附行为与缓蚀机理研究

The space electric field exists in some service environment of corrosion inhibitors. In the thin electrolyte layer, electric field affects the diffusion and migration of corrosion inhibitors significantly. The electric double layer at the metal/thin electrolyte layer interface and the structure of corrosion inhibitor molecules may also alter under the space electric filed. At the meanwhile, some other behaviors may be changed dramatically due to the presence of the space electric filed, including: the distribution of corrosion inhibitors on the surface of metal, the supplement and restoration of corrosion inhibitors at the interface, the intermolecular forces between the inhibitor molecules and metal atoms, processes of adsorption and desorption for inhibitor molecules, the structure and composition of inhibitors/corrosion products composite membrane, etc. Thus, it is essential to make clear the influence of space electric filed on the behavior of corrosion inhibitors, which ensures the effective application of inhibitors and complements the scientific theory of corrosion inhibitor. The project elucidates the influence of space electric filed on the migration and distribution of corrosion inhibitors in a thin electrolyte layer based on in situ atomic force microscopy and digital 3D optical observation, as well as ex situ sample analyses. We also study the mechanism of adsorption and desorption for inhibitor molecules on the surface of metal in a thin electrolyte layer via the combined approach of electrochemical tests and surface characterizations. To clarify the change in molecule structure of corrosion inhibitor under the space electric filed, quantum chemical evaluation is applied in the work, which fundamentally explains the effect of the space electric filed on the corrosion inhibitor in a thin electrolyte layer.

缓蚀剂的一些使用场合存在着空间电场。薄液膜中，电场对缓蚀剂的迁移、扩散会产生显著影响；在电场作用下，金属/薄液膜双电层构造可能发生变化；特别是电场可能改变缓蚀剂分子的结构。由于电场的作用，缓蚀剂在金属表面的分布、界面缓蚀剂的补充与修复、缓蚀剂分子与金属间的作用力、缓蚀剂在金属表面的吸脱附行为、缓蚀/腐蚀复合膜结构与组成等均可能发生改变。弄清存在空间电场时缓蚀剂的作用特性，这不仅是确保电场存在环境下缓蚀剂合理使用的前提条件，同时也是对缓蚀剂科学理论的必要充实与补充。本项目利用原位原子力显微镜测试、3D显微镜观察，结合取样分析，阐明电场对薄液膜中缓蚀剂迁移、分布的影响；采用薄液膜电化学测试技术，结合表面微观分析手段，研究在电场存在时，缓蚀剂作用下金属的腐蚀电化学行为，探讨缓蚀剂在金属表面的吸脱附机制。结合量子化学计算，阐明电场对缓蚀剂结构的影响，从本质上揭示存在电场时薄液膜中缓蚀剂的作用机制。

缓蚀剂的一些使用场合存在着空间电场，而电场的改变，还会导致磁场的产生。电磁场对缓蚀剂的迁移、扩散会产生显著影响；在电磁场作用下，金属/薄液膜双电层构造会发生变化；特别是电磁场可以改变缓蚀剂分子的结构。由于电磁场的作用，缓蚀剂在金属表面的分布、界面缓蚀剂的补充与修复、缓蚀剂分子与金属间的作用力、缓蚀剂在金属表面的吸脱附行为、缓蚀/腐蚀复合膜结构与组成等均会发生改变。我们研究发现，仅需微弱的电场，就会导致无机缓蚀剂如亚硝酸盐、铬酸盐、钼酸盐等的迁移发生改变，从而导致金属仅局部受到保护；而强电场则会直接影响有机缓蚀剂分子的能隙值、吸附原子净电荷、偶极矩等参数，从而影响有机缓蚀剂的缓蚀性能。另外，通过制备不同的纳米缓蚀剂，探讨电场对纳米缓蚀剂的影响发现，电场会导致MOFs纳米缓蚀剂的中心金属离子从框架结构中游离出来，从而破坏其框架结构，导致其缓蚀性能显著降低甚至丧失。微弱的磁场就能显著影响有机缓蚀剂的缓蚀性能，总体上磁场能够提高缓蚀剂的缓蚀效率，磁场强度越大缓蚀剂的缓蚀效率越高；不同偶极矩的缓蚀剂受到磁场的影响不同，磁场对偶极矩较大的缓蚀剂影响较大。