芳香氨基类化合物对铁缓蚀行为的分子动力学模拟

Molecular dynamics simulation of the corrosion inhibition behavior of aromatic amine on iron

采用分子动力学模拟方法研究了2种芳香氨基类缓蚀剂(对氨基苯磺酸、2-氨基5-硝基苯甲酸)在Fe(110)表面的吸附行为,计算了吸附能,并对其缓蚀机理进行了深入分析,研究结果表明,芳香氨基类分子的极性端基会吸附在金属表面上,而非极性端基则背离金属表面,并通过自身的扭转形变实现稳定吸附;两种缓蚀剂膜均能有效阻碍溶液中的腐蚀介质向金属铁表面扩散,从而达到延缓金属腐蚀的目的。另从缓蚀剂膜阻碍腐蚀介质粒子(H_3O和H_3O^+)向金属表面扩散的角度,研究了腐蚀介质粒子在2-氨基5-硝基苯甲酸缓蚀剂膜中的扩散行为,计算其扩散系数,结果表明,缓蚀剂膜能有效抑制腐蚀介质的迁移,削弱其腐蚀能力:与中性H_3O分子对比,缓蚀剂膜对H_3O^+带电离子的扩散具有更强的抑制效果。

The adsorption behaviors of two kind of aromatic amine corrosion inhibitors （p-aminobenzene sulfonic acid, 2-amino- 5-nitro-benzoic acid） on a Fe（110） surface were investigated by molecular dynamics simulation method, and the inhibition mechanism was also discussed in depth. The results demonstrate that the polar head group of the aromatic amine molecule is attached to the metal surface while the non-polar deviates from the metal surface, stable corrosion inhibitor molecule absorption is achieved by self distortion. As a result, the formed dense corrosion inhibitor monolayer efficiently restrains the diffusion of the corrosive media to the metal surface, which delays its corrosion. The corrosion inhibition mechanism of 2-amino-5-nitro-benzoic acid inhibitor for iron against corrosion was investigated, from the aspect of corrosive medium particles （H2O, H3O^＋） diffusion to the metal surface hindered by the corrosion inhibitor membrane. The diffusion coefficients of corrosive medium particles in corrosion inhibitor membrane indicated that the inhibitor could form stable membranes, which could effectively limited the diffusion of corrosive medium particles to the metal surface, in order to inhibit or delay corrosion. The membrane was better at limiting the diffusion of charged particle （H3O＋） than that of a neutral particle （H2O）.