吸附对金属钝化膜结构与稳定性影响的计算模拟及实验研究

The adsorption behavior of metal surfaces is closely related to the composition as well as structure of passive films and the local corrosion sensitivity. For this characteristic,this project studies the laws of adsorption on fcc metal/solution interface and film-forming in various environmental media based on the first-principles calculation; and further explains the relationship between preferential adsorption of erosive ions and the stability of the films as well as the mechanism of the electrochemical action combining with the results of experiments.Concentrating on the problems about adsorption-film and oxide-film in passivation theory, the 2-D and 3-D surfaces and grain boundaries of passive film are modeled to calculate the relationship between the concentration of defects in passive films and ion adsorption as well as partial dissolution. Experimental analysis are involved to study the electrochemical behavior of passive films in various environmental media. And by means of microscopic analysis such as STM and AFM and so on, the inherent law between adsorption and local corrosion of passive metals can be clear after a comprehensive study on the effect of such factors as passive film composition, structure, defect types and concentration, grain boundary characteristics on the stability of the passive film. The project is aimed at clarifying the mechanism of adsorption during the formation, stabilization, dissolution and rupture process of passive film as well as the physical and chemical reaction mechanism of the metal / film / solution interface.The project can provide theoretical support for the development of metal passivation theory system and provide novel ideas and approaches for the design and application of corrosion resistant materials.

本项目针对金属表面吸附与其钝化膜组成、结构和局部腐蚀敏感性密切相关的特点，基于第一性原理的计算模拟，研究不同介质环境中面心立方金属/溶液界面吸附与成膜的规律，结合实验，进而阐释侵蚀性离子优先吸附与膜层稳定性之间的关联及其电化学作用机制。围绕钝化理论中吸附膜与成相膜的科学问题，重在建立钝化表面二维/三维氧化模型、钝化膜晶界模型，计算膜中缺陷浓度与离子吸附、局部溶解之间的关系。通过对不同介质环境中钝化膜电化学行为的测试与分析，采用扫描隧道显微镜、原子力显微镜等微观分析方法，在综合考察钝化膜组成、结构、缺陷类型与浓度、晶界特征等参量对钝化膜稳定性影响的基础上，明确吸附与钝态金属局部腐蚀之间的内在规律。旨在阐明钝化膜形成、稳定化、溶解以及破裂过程中吸附的作用机理，以及金属/膜/溶液界面内在的物理化学机制。项目可为金属钝化理论体系的发展提供理论支撑，为耐蚀材料设计和应用提供新思路和新方法。

本项目针对金属表面吸附与其钝化膜组成、结构和局部腐蚀敏感性密切相关的特点，基于第一性原理的计算模拟，研究了不同介质环境中钝态金属的吸附成膜与点蚀破裂规律，结合原位观测等实验，阐释侵蚀性离子优先吸附与膜层稳定性之间的关联及其电化学作用机制。围绕钝化理论中吸附膜与成相膜的科学问题，重点建立了钝化膜晶态模型、钝化膜/基体界面模型以及金属间化合物/基体模型，计算膜中缺陷浓度与水解离、离子吸附和局部溶解之间的关系。采用扫描电镜、原子力显微镜等测试了不同介质环境中钝化膜形成和失效行为，系统分析了钝化膜组成、结构、缺陷类型与浓度、晶界特征等参量对钝化膜稳定性影响，明确吸附与钝态金属局部腐蚀之间的内在规律。结果表明：对于无缺陷金属Al(111)表面，钝化膜在H2O和O2分子的共同作用下形成，通过氧原子向内部的迁移生长，而非铝原子向外迁移；铝合金中Al2CuMg相表面钝化膜疏松且存在缺陷，膜厚度小于基体表面膜层，从原子尺度说明了影响铝合金表面微电偶作用的动力学机理；通过钝化膜/基体吸附模型的计算，阐述了空位和界面电子性质对钝化膜破裂机制的影响；应力作用下Mg2Si、α(Al-Cu-Fe)相与铝基体的电偶效应发生改变，塑性形变促进钝化膜失稳导致耐点蚀性能显著下降。项目旨在阐明钝化膜形成、稳定化、溶解以及破裂过程中吸附的作用机理，以及金属/膜/溶液界面内在的物理化学机制，所建立的第一性原理计算数据库可为金属钝化体系的发展提供支撑，为耐蚀材料设计和应用提供新思路和新方法。