Influence of environmental parameters on the corrosion behavior of 90/10 cupronickel tubes in 3.5% NaCl

Abstract

The paper describes an experimental study concerning the influence of major environmental parameters (temperature, chloride, carbon dioxide, and oxygen) on the corrosion behavior of 90/10 Cu–Ni alloys widely used for heat-transfer tubes. Electrochemical techniques have been used to investigate the corrosion behavior of 90/10 Cu–Ni alloys in aerated 3.5% NaCl solutions, at temperatures of 25, 50, and 80°C with and without the injection of carbon dioxide. The results have revealed increases in chloride corrosion rates of the 90/10 Cu–Ni alloy with temperature and decreases with CO₂ presence. Tests performed in aerated chloride–CO₂ solutions have shown higher corrosion rates relative to those conducted in deaerated chloride solutions saturated with CO₂ species. The surface morphology of polarized specimens in chloride solutions with and without CO₂ presence has shown a susceptibility to pitting attack. Pit characteristics have been found to be highly influenced by CO₂ presence.

Keywords:

• 90/10 copper nickel alloys
• Chloride ions
• CO₂
• Corrosion

Acknowledgment

The authors would like to thank Hanan Abbas for her role in sample characterization utilizing SEM.