利用电沉积二氧化硅薄膜构建金属表面新型、高效、绿色涂装防护体系

Traditional surface pretreatment processes, e.g. phosphating and chromatizing, in painting industry, can no longer meet the requirement of the sustainable development of the modern society, due to their environmentally unfriendly properties. Meanwhile, the recently developed silanization process has a problem of high selectivity with the topcoat, which impedes its wide industrial application. Previous work showed that, with the aid of electrochemically assisted technique, robust and nano-porous rough silica sol-gel films can be deposited onto conducting substrates. Using such advantage, this project proposes for the first time the use of electrodeposited silica films as the pre-treated layers for a new generation of protective painting system. Very recently, our preliminary investigation shows that the newly constructed painting system exhibits promising long-term protection properties. Accordingly, this project will investigate firstly the influence of some basic parameters on corrosion performance of the total painting system, after which a highly efficient protective painting system will be constructed. Further, get into the mechanistic study in the role of electrodeposited silica films played in the total paiting system, in particular focus on the theoretical study on "metal/silica film" and "silica film/protective coating" interfaces. Finally, the failure mechanism of the painting system will be also studied. The above-mentioned investigation will provide this novel paiting system the theoretical and practical guidances, and ultimately make it possible for its replacement of traditional painting system.

在涂装工业中，传统的金属表面预处理技术（如磷化与铬酸盐钝化）对环境不友好，已不能顺应现代社会"可持续发展"的要求，而近年来开发的有机硅烷化处理工艺存在与后续涂层较高的选择性问题，阻碍其大规模的工业化应用，促使我们将探寻更理想的金属表面预处理层的目光重新回到无机氧化物材料上。先前的工作表明，借助电化学辅助沉积技术，可在导电基体表面沉积得到"牢固"、纳米多孔的粗糙SiO2 sol-gel薄膜。利用上述特性，本项目第一次提出采用电沉积SiO2薄膜作为金属材料的预处理层，在此基础上构建新一代绿色涂装防护体系，预研结果显示具有优异的长效防护性能。项目将通过研究工艺与性能，优化、构建得到高效涂装防护体系，进而探明SiO2薄膜在整个防护体系中的内在作用机制，以及防护体系的失效机制。通过上述研究，为"金属/电沉积SiO2薄膜/有机涂层"涂装体系提供理论与应用基础，期望最终实现对传统涂装防护体系的更新换代。

本项目意在研究一种替代传统磷酸盐及铬酸盐技术的金属表面新型绿色高效预处理层---电沉积二氧化硅薄膜。通过项目实施，取得如下研究成果：.（1）明晰了金属表面电沉积二氧化硅薄膜的基本工艺与相关规律。发现了二氧化硅薄膜沉积的“临界pH值”现象，同时发现沉积动力受沉积电位调控，与碱催化机理相吻合。.（2）以电沉二氧化硅薄膜为预处理层构建得到了优异防护性能的涂装体系，对预处理层进行后续硅烷化或预先负载缓蚀剂等手段可进一步大幅度提高涂层体系的防护性能。其中以碳钢基体为例，经葡萄糖酸锌或聚吡咯烷酮缓蚀剂负载的电沉积二氧化硅薄膜/环氧清漆涂层体系（涂层厚度100微米）在模拟海水中浸泡一年后的低频阻抗值仍保持在1011Ωcm2，是目前文献报导的最高数值。.（3）在此基础上，采用分子动力学模拟手段研究了二氧化硅薄膜增强涂层界面的相关机制，发现无定型二氧化硅与多种聚合物涂层间具有较高的作用能，可能是电沉积二氧化硅薄膜增强作用的重要原因。.项目发表相关SCI论文13篇，其中专业领域顶级期刊Corrosion Science 6篇、材料领域权威期刊Journal of Materials Chemistry A 3篇，13篇论文被引用131次，篇均引用超10次；授权项目执行期间完成的专利2份。