金属表面超疏水分级微纳结构高效可控制备与防腐机理研究

Corrosion failure is a bottleneck problem that restricts the application and development of oceaneering metallic materials. The fabrication of superhydrophobic hierarchical micro-nano structures can provide an effective and new method to solve metallic corrosions. This project is aimed at the urgent problems about theoretical design, effective controllable fabrication and anticorrosion mechanism of superhydrophobic anticorrosion hierarchical micro-nano structures on metal surfaces. Firstly, the mathematical model between structural feature and wettability are determined by analyzing liquid-air interfacial characteristics in composite wetting conditions as well as studying static equilibrium and dynamic instable mechanisms of a suspension droplet. Afterwards, the parametric design criterion for superhydrophobic hierarchical structures is also proposed under the droplet static-dynamic coupling constraints. The reasonable process dimensions and path plans for machining anticorrosion structures are also achieved. Furthermore, a low-speed unidirectional electrospark wire-electrode erosion technology is applied to optimize processing parameters on Al alloy. Then, the one-step controllable preparation of superhydrophobic and anticorrosion hierarchical structures is achieved based on structural design criterion. Besides, the cellular automata simulations of chloride diffusions between the prepared hierarchical Al alloy and seawater are conducted. After that, the micro-scale superhydrophobic corrosion process and the evolution rule of corrosion parameters with time and structure are obtained. The influence mechanisms of wetting interfacial properties on corrosive behaviors are clarified, and also the anticorrosion mechanisms of hierarchical structures are revealed. This project can establish theoretical foundations and provide technical supports for industrial applications of superhydrophobic and anticorrosion surfaces.

腐蚀失效是制约海洋工程金属构筑物应用与发展的瓶颈，超疏水分级微纳结构制备为解决金属腐蚀问题提供有效新途径。针对目前迫切需要解决的金属表面超疏水耐蚀分级微纳结构理论设计、高效可控构建及防腐机理研究难题，本项目结合复合润湿状态液-气接触界面特征、悬浮液滴静力平衡及动态失稳机理分析，建立结构特征与润湿特性关系数学模型，提出液滴静动耦合约束超疏水分级结构参数设计准则，获得结构加工成形合理工艺尺寸，指导耐蚀表面加工路径合理规划；采用低速单向走丝电火花诱导烧蚀技术，开展铝合金表面加工工艺参数优选实验，实现设计准则指导下超疏水耐蚀分级结构一步高效可控制备；基于制备铝合金分级试样-海水界面氯离子扩散行为的元胞自动机模拟，还原微观尺度超疏水表面腐蚀过程，获得腐蚀特征参量随时间及结构演变规律，阐明润湿界面特性对腐蚀行为影响机制，揭示分级结构防腐机理，为超疏水耐蚀表面工业应用奠定坚实理论基础和提供技术支持。

金属表面超疏水分级微纳结构高效可控制备与防腐机理研究，针对目前迫切需要解决的金属表面超疏水耐蚀分级微纳结构理论设计、高效可控构建及防腐机理研究难题，经过项目执行期三年研究，（1）建立了结构特征与润湿特性关系数学模型，提出了液滴静动耦合约束超疏水分级结构参数设计准则；（2）进一步采用电火花诱导烧蚀、一步电化学、水热处理等技术，开展了合金表面加工工艺参数优选实验，实现了超疏水耐蚀分级结构一步高效可控制备，尤其制备的复合分级结构宏观上表现为脆弱纳米片状结构填充至相互连接微米凸台之间，形成了硬质材料对脆弱纳米结构的“铠装”保护作用，从而获得优异机械稳定性；（3）同时，基于制备合金分级试样-海水界面离子扩散行为研究，阐明了润湿界面特性对腐蚀行为影响机制，揭示了分级结构防腐机理，对于制备超疏水试样，不仅仅表现出修饰膜层对腐蚀介质的物理隔离作用，还表现出分级结构表面对腐蚀介质的动态驱离效果，故其膜层阻抗最大；（4）此外，相对疏水样块，复合制备试样的驱离效果更加明显，这是由于复合制备两级结构特征更加明显，分级复合结构的存在明显增加了表面粗糙度，提高了空气的滞留量，表现出增强的Cassie润湿状态下的固-气-液三相复合接触界面特征，其表面固-液接触比例最小，粗糙表面对液体的粘滞阻力最低，水滴运动需要克服的能量势垒也最少，动态疏水效果最明显，因此耐腐蚀性能最好。本项目的开展，为超疏水耐蚀表面设计、高效可控构筑及工业应用奠定理论基础和提供技术支持。