复杂海洋环境中镍基激光熔覆层动态腐蚀行为与机理研究

Ni-based laser cladded coating is of important significance for the corrosion prevention of the marine equipment in China. However, the dynamic corrosion behavior and mechanism of Ni-based laser cladded coating as well as the relationship between the micro-features and dynamic corrosion mechanism of the different cladding regions are still not clear, which limit the application of this coating. This project will be carried out aiming to these scientific problems. Firstly, a dynamic corrosion simulating system will be set up based on the complex environment that the marine equipment serve in. Then, the influence mechanism of flow rate, impact angle and vibration frequency on the dynamic corrosion behavior of laser cladded coating will be revealed through uni-variate dynamic experiments, real-time electrochemical tests and the analysis of the corrosion morphology and products etc.. Second, the dynamic corrosion mechanism of laser cladded coating under the reciprocal action of various dynamic factors with electrochemical corrosion will be illustrated by various factor dynamic corrosion experiments and the quantitative analysis. Third, the essential relationship between the dynamic corrosion mechanism of different cladding regions and their micro-features, such as microstructure, grain orientation and phase composition etc., will be established by separately conducting microstructural characterization, surface potential distribution tests, dynamic corrosion experiments and real-time electrochemical tests etc. in overlapping region and non-overlapping region of the laser cladded coating. The results of the above research have important theoretical and practical value for promoting the rapid development of the marine equipment in China and the corrosion resistance optimization of Ni-based laser cladded coating.

镍基激光熔覆层在我国海洋装备防腐领域具有重要应用价值。然而，复杂海洋环境中该熔覆层的动态腐蚀行为和机理以及动态腐蚀机理与熔覆层不同熔覆区域微观特征的本质关系尚不明确，限制了其应用。本课题针对以上关键科学问题展开研究，首先，搭建海洋装备服役的复杂海洋动态腐蚀模拟测试系统，通过单变量动态腐蚀实验、实时电化学测试、腐蚀形貌及产物分析等，揭示冲蚀速度、冲蚀角及机械振动频率对熔覆层动态腐蚀行为的影响机理。其次，通过多因素动态腐蚀实验及定量分析方法阐明各动态因素与电化学腐蚀交互作用下熔覆层的动态腐蚀机理。第三，通过对熔覆层熔道搭接区及非搭接区分别进行微观组织表征、微区表面电位分布测试、动态腐蚀实验及对应实时电化学测试等，构建两熔覆区域动态腐蚀机理与二者微观组织、晶粒取向、物相组成等微观特征的本质关系。其研究结果对推动我国海洋装备的迅速发展及镍基激光熔覆层耐蚀性能优化具有重要的理论与实用价值。

镍基激光熔覆层在我国海洋装备防腐领域具有重要应用价值。然而，复杂海洋环境中该熔覆层的动态腐蚀行为和机理以及动态腐蚀行为与熔覆层不同熔覆区域微结构特征的本质关系尚不明确，限制了其应用。.本项目针对以上关键科学问题，首先，搭建了包含机械振动因素的更接近真实海洋装备服役环境的多因素协同作用动态腐蚀测试系统。其次，研究了熔覆层在冲刷速度、冲刷角、机械振动频率交互作用下的动态腐蚀行为特征，揭示了存在临界冲刷速度，流体剪切力和正应力联合控制，随着机械振动频率增加而加剧的镍基激光熔覆层动态腐蚀机理。第三，探究了熔覆层搭接区和非搭接区在不同冲刷速度和冲刷角条件下的动态腐蚀行为及机理。结合两熔覆区的晶粒形态、物相、晶界等微结构特征，揭示了二者动态腐蚀行为与其微结构特征的强关联性，即激光二次热影响导致的搭接区粗大晶粒增加了其在流体冲刷过程中的塑性变形，而其更显著的初晶相与共晶相间的元素差异以及元素二次扩散造成其更高的铁含量均增强了其电化学腐蚀敏感性。 .本项目的实施为镍基激光熔覆层在海洋装备上的防腐应用提供实验基础和理论依据。