换热器T2紫铜管在水线部位的腐蚀机理研究

目的 基于对换热器中T2紫铜管因受残留水作用而出现泄漏降压现象的研究，分析换热器T2紫铜管在水线部位的腐蚀机理。方法 通过T2紫铜管的润湿试验，对腐蚀样品进行宏观和微观形貌观察，对点蚀坑部位的腐蚀产物进行EDS和XPS等表征手段分析，探究腐蚀产物的成分和结构，从而推导出反应机理。结果 铜管水线上部位和下部位都以均匀腐蚀为主，但是颜色有所差异。水线部位以点蚀为主，肉眼即可见排成直线的斑点状腐蚀坑，腐蚀产物的颜色主要为黑色和绿色。根据表征分析结果可知，腐蚀体系中含有HCO3^‒和SO4^2‒。腐蚀产物的组成有，内层Cu2O，外层CuO，水线部位和水线以下部位铜管表面还有一层CuCO3Cu(OH)2膜。结论 根据腐蚀产物的元素分析可知，在HCO3^‒和SO4^2‒共同存在的环境中，铜具有很高的点蚀敏感性，T2紫铜管很容易发生局部腐蚀，加之氧浓差电池的作用，水线部位铜管发生严重的点蚀以致穿孔失效。

Corrosion Mechanism of T2 Copper Tube at Water Line Positions

The work aims to analyze the corrosion mechanism of T2 copper tubes at the waterline positions based on the study of the phenomenon of leakage and pressure reduction in T2 copper tubes within heat exchangers due to residual water effects. Wetting experiments were conducted to T2 copper tubes, followed by macroscopic and microscopic observations of corroded samples and characterization of corrosion products at pitting sites using techniques such as EDS and XPS to explore their composition and structure, thereby deducing the reaction mechanism. Both the above and below sections of the copper waterline were primarily affected by uniform corrosion, with slight color variations. Pitting corrosion was predominantly observed at the waterline position, with visible linear scattered corrosion pits that were predominantly black and green in color. According to the results of characterization analysis, it was known that the corrosion system contains HCO3– and SO42–. The composition of corrosion products included an inner layer of Cu2O and an outer layer of CuO. Additionally, a layer of CuCO3Cu(OH)2 film was present on the surface of the copper tubes both at the waterline position and below it. Elemental analysis of the corrosion products indicates that copper exhibit high sensitivity to pitting in environments containing HCO3– and SO42–. T2 copper tubes are prone to localized corrosion, exacerbated by the action of oxygen concentration cells, leading to severe pitting corrosion and eventual perforation failure at the waterline positions.