Atmospheric Corrosion of Cu during Constant Deposition of NaCl

Abstract

A laboratory environment chamber with a constant deposition rate of NaCl was built. With this chamber, the corrosion behavior of Cu during constant NaCl deposition was investigated with different CO2 concentrations and ultraviolet (UV) illumination. XRD and coulometric reduction techniques were used to identify and quantify the corrosion products. An Na2CO3 solution was found to be more suitable than KCl solutions for quantification of Cu corrosion products. Cuprite was always the dominant corrosion product during exposure of Cu in various environments. UV illumination accelerated formation of cuprite significantly but had very little effect on formation of cupric corrosion product. CO2 in the environment was important in determination of cupric corrosion products. With 350 ppm CO2, paratacamite was the dominant product, while tenorite was dominant with <1 ppm CO2. This explains why tenorite is not a common cupric corrosion product in the field. Pitting corrosion was always the dominant form of corrosion at the beginning of the exposure period but uniform corrosion dominated at later times. The new environment chamber enables the determination of Cu corrosion kinetics in the lab, especially the formation of paratacamite, which provides insight into Cu atmospheric corrosion in the field.