Metal Carboxylate Formation during Indoor Atmospheric Corrosion of Cu, Zn, and Ni

Chemical analyses of surface films and corrosion products formed on pure Cu, Zn, Ni, and Ag samples exposed up to 12 months in various mild indoor environments have been performed by infrared reflection‐absorption spectroscopy (IRAS) and x‐ray photoelectron spectroscopy. The analyses reveal metal carboxylates to be the main ingredients on the surface of Cu, Zn, and Ni. Other ions, such as sulfate, chloride, nitrate, and ammonium ions are also present but in smaller amounts. The surface region on Ag contains mainly silver sulfide with smaller amounts of sulfate, ammonium, and chloride ions. The growth of the carboxylate layers, as followed by IRAS, exhibits an initial film formation with a thickness of a few nanometers for all exposure sites investigated. Subsequent growth to thicker layers was observed at sites with higher humidity levels. The unexpectedly high content of metal carboxylates found on Cu, Zn, and Ni may provide insight into possible processes involved in the atmospheric indoor corrosion of these metals.