深海环境下Fe基非晶涂层的腐蚀行为及其对涂层结构和性能的影响

With the shortage of energy sources under earth, people are converting eyes to the deep-sea. The complex and harsh corrosion environments in deep-sea, however, bring new challenges to the engineering materials used in the sea, which arose an urgent demand for the development of new advanced anti-corrosion materials and coatings. Fe-based amorphous coatings developed in recent years show a good possibility to be used in deep-see due to their excellent mechanical and anti-corrosion properties. However, little work has been done on corrosion behavior and corrosion effect on structure and performance of the Fe-based amorphous coating in deep-sea enviorment. In this project, typical Fe-based amorphous coatings will be chosen as target materials, then corrosion behavior in deep-sea environment will be extensively studied in both experimental and theoretical aspects. The detailed research contents include: 1) Corrosion behavior and pitting mechanism of Fe-based amorphous coating in deep-sea environment; 2) Stress-corrosion behavior of the coatings in deep-sea; 3) Structure effect (eg., partially crystallized) on corrosion of the coatings' 4) The structure and properties of the coatings after deep-sea corrosion. It is envisaged, on the basis of above mentioned researches, the pitting mechanism of the amorphous coating in deep-sea can be disclosed, and the effect of corrosion on structure and properties of the coatings can be clarified. The present research can provide a new technic support and theoretical base for the development of advanced anti-corrosion coatings in deep-sea engeering applications.

随着陆地能源资源日渐枯竭，世界各国已将目光投向深海能源开发。然而复杂的深海环境和严苛的海洋腐蚀给工程材料的安全服役带来极大的挑战。发展高性能深海工程材料及防护性涂层材料是突破深海能源开发技术瓶颈的关键。近年来发展起来的Fe基非晶涂层因其具有优异的力学和耐蚀性能，在深海工程领域呈现广阔的应用前景，并有望成为新一代深海防护材料。然而，有关Fe基非晶涂层在深海环境下的腐蚀行为以及腐蚀对涂层结构和性能的影响尚缺乏深入研究。本项目拟以典型Fe基非晶涂层为对象，深入开展以下研究：1）非晶涂层在深海环境下的腐蚀行为及影响因素；2）在深海环境中非晶涂层的应力腐蚀特征；3）非晶涂层的结构对腐蚀行为的影响，4）深海腐蚀对非晶涂层结构与性能的影响。通过以上研究，揭示深海环境中非晶涂层的点蚀机制，阐明深海腐蚀对非晶涂层结构和性能的影响规律，为开拓Fe基非晶涂层在深海领域的应用提供技术储备和理论依据。

我国海洋强国战略的实现依赖于深海关键装备与材料的提升，而高压、低温等极端深海腐蚀环境给海洋工程材料的安全服役带来极大的挑战。开发新型高性能深海工程材料及防护涂层是突破深海开发技术瓶颈的关键。在基金委资助下，本项目四年来围绕上述关键问题开展了以下研究：1）模拟深海环境(0-2400 m)腐蚀原位电化学装置的研制；2）深海静水压力对不锈钢腐蚀行为的影响规律及作用机制；3）深海静水压力对Fe基非晶涂层腐蚀行为的影响规律及作用机制；4）封孔处理对非晶涂层深海腐蚀行为的影响；5）晶化对Fe基非晶合金深海腐蚀行为的影响规律与机制; 6）新型高铬Fe基非晶合金/涂层的设计及其磨损腐蚀行为。项目研究结果发现：深海静水压力降低了不锈钢与Fe基非晶涂层的腐蚀性能，但非晶涂层深海耐蚀性能显著优于传统316L不锈钢。深海高静水压力导致不锈钢表面钝化膜不均匀化，从而加速点蚀萌生与生长；深海高静水压力导致非晶涂层表面钝化膜中点缺陷浓度与膜厚同时增加，因此增加了均匀腐蚀速率，但未影响点蚀性能。开发出适用于Fe基非晶涂层的新型封孔剂材料（PTFE纳米颗粒），腐蚀性能优于常规封孔剂(如磷酸铝)；封孔处理降低涂层表面能并减少贯穿孔隙，因此显著提高了非晶涂层的深海耐蚀性能。纳米晶化降低Fe基非晶合金的深海耐蚀性能，发现存在一临界晶化率（30%），高于该临界晶化率，非晶合金深海腐蚀性能出现显著恶化，分析认为这是由于纳米晶化导致钝化膜中Cr与Mo分布的不均匀性所致。根据这一研究结果，本项目进一步优化设计出新型高铬Fe基非晶合金/涂层，其耐磨性与耐蚀性能显著由于目前文献报道的Fe基非晶合金，建立了成分-硬度/模量/断裂韧性-耐磨性的关联图谱，揭示了合金元素对非晶合金腐蚀性能的影响机制。本项目在ACS Applied Materials & Interfaces, Journal of Materials Chemistry A, Electrochimica Acta, Journal of Alloys and Compounds等发表SCI论文10篇, 另有2篇论文整理待投，获授权发明专利4项，申请中1项。项目的顺利完成对深海环境下高性能防护涂层的理论设计提供了科学依据与基础数据。