基于微区电化学的球墨铸铁管腐蚀管垢介尺度生长机理研究

Corrosion scale is easy to generate in the inner wall of the metal pipe of water distribution system (WDS) in the long run. It has become one of the key factors that affect the stability and safety of water quality. The formation and dissolution of corrosion scales is influenced by multi-scale effects, such as chemical/electrochemical reaction processes in micro-scale and water hydraulic and quality variations in macro-scale. The scale is characterized by multi-scale effect and eventually forms a complex structure. Limited by the conventional experimental and theoretical methods, the scientific analysis on the growth kinetics of corrosion scales has not been achieved..Ductile iron pipes of WDS are studied in this project, and the research is guided by meso-scale theory. Localized electrochemical measurement technology is used to in-situ monitor the meso-scale structure of the scale surface in real time. According to the unified principle of mesoscale theory, we seek to express the function expression of coordination between micro and macro control mechanism. And the ductile iron pipe scale meso-scale growth kinetics model is established. In addition, the stability condition of the mesoscale structure of corrosion scale growth is proposed, and a theoretical study on the stability of WDS based on the evaluation of pipe scale state is established..Through the implementation of this project, the key reason of WDS water quality deterioration caused by corrosion pipe scale will be revealed, and the water quality stability control mechanism can be accurately explained. Finally this work is of great significance to maintaining water quality and ensuring safe operation of WDS.

金属供水管道长期运行中易在管壁内侧形成腐蚀管垢，已成为影响管网水质稳定和水质安全的关键因素之一。腐蚀管垢的生成和溶解受多尺度作用的影响（微尺度上的化学/电化学反应过程、宏尺度上水力水质条件的变化），具有多尺度效应特征和复杂结构。由于常规实验手段和理论方法的限制，目前尚未实现对腐蚀管垢生长动力学的科学解析。.本项目以球墨铸铁管为研究对象，以介尺度理论为指导，引入微区电化学原位测量技术，对腐蚀管垢表面的介尺度结构进行实时监测。依据介尺度原理统一规律寻求表达微观和宏观两种控制机制之间竞争中协调的函数表达式，建立球墨铸铁腐蚀管垢生长的介尺度动力学模型。并提出腐蚀管垢介尺度结构的稳定性条件，建立基于管垢状态评价的供水管网水质稳定性判定理论。.本项目的实施将从本质上掌握腐蚀管垢引起的管网水质恶化的机理，并准确揭示供水管网的水质稳定性控制机制，对于保障供水管网水质稳定和安全运行意义重大。

本项目以目前供水管网使用最广泛的带水泥砂浆内衬的球墨铸铁管为研究对象，引入具有微米级空间分辨率的微区电化学测试技术，建立了介尺度下带内衬球墨铸铁管全生命周期腐蚀垢层生长过程的实时、原位监测方法。根据供水管道腐蚀垢层的生长特征，确定了带内衬球墨铸铁管腐蚀失效的三个不同阶段：（I）内衬完整保护期、（II）内衬局部失效期和（III）内衬脱落期。同时，分别研究了内衬完整保护期的水泥砂浆的溶蚀特征和内衬脱落期的裸露球墨铸铁的长期腐蚀规律，阐明了带内衬供水管道不同腐蚀阶段导致水质恶化的主要原因和途径。.然后，针对内衬局部失效期，采用SVET和三维视频显微技术相结合，对宏观尺度因素（典型水质条件）与微观尺度因素（管壁腐蚀电化学反应）共同作用下球墨铸铁腐蚀垢层的生长过程进行原位监测，探讨了介尺度下腐蚀管垢的稳定性控制机制，提出了球墨铸铁供水管道腐蚀垢层生长及铁释放的概念模型。最后，根据供水管道不同腐蚀阶段管壁状态的特征，提出了与各阶段相适应的水质稳定性判定方法，并通过模拟循环管路系统进行了验证。.该项目的实施从本质上掌握了宏观典型水质因素和微观腐蚀电化学反应过程共同作用下供水管道腐蚀垢层稳定性的控制机理，揭示了带内衬球墨铸铁管因腐蚀管垢表面微区电化学特性差异导致金属污染物富集和释放，进而引发水质恶化的根本原因，为供水管网保持水质稳定和安全运行提供了重要的理论指导。