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| Corrosion Mechanism of T2 Copper Tube at Water Line Positions |
| Received:April 11, 2024 Revised:May 07, 2024 |
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| DOI：10.7643/issn.1672-9242.2024.05.012 |
| KeyWord:T2 copper tubes waterline pitting HCO3–and SO42– localized corrosion oxygen concentration cells |
| Author | Institution |
| LI Chao |
Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
| WANG Changgang |
Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
| DONG Junhua |
Institute of Metal Research, Chinese Academy of Sciences, Shenyang , China |
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| Abstract: |
| 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. |
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