Atmospheric corrosion of Cu by UV, ozone and NaCl

Abstract

The effects of ultraviolet (UV), ozone and NaCl on the atmospheric corrosion of Cu have been studied. The corrosion products were analysed by X-ray diffraction and quantified by coulometric reduction. Surface morphology after exposure was studied by scanning electron microscopy. The protection effect of naturally formed copper oxide was shown by comparing the corrosion behaviours of Cu and Ag with UV and ozone but in the absence of NaCl. Ultraviolet illumination had a significant accelerating effect on Cu corrosion regardless of the presence of ozone. With ozone and NaCl, the accelerating effect of UV was more evident at low relative humidity (RH) (60%) than at high RH (90%). Loading of NaCl is critical for the formation of Cu₂(OH)₃Cl, a common corrosion product of Cu in marine environments. Oxidation of Cu₂O to Cu₂(OH)₃Cl in the presence of NaCl by oxygen and ozone is a possible pathway for the formation of Cu₂(OH)₃Cl.

Keywords:

• Copper
• Corrosion
• UV
• Ozone
• Photocorrosion

Acknowledgement

This work was funded through the Mandaree Enterprise Corp. as part of the Technical Corrosion Collaboration organised by D. Dunmire at the US Office of the Secretary of Defense.