GILDES Model Simulations of the Atmospheric Corrosion of Copper Induced by Low Concentrations of Carboxylic Acids

Abstract

A computer simulation with a GILDES-based model using the COMSOL multiphysics software was performed for copper exposed to low concentrations of carboxylic acids in humidified air at room temperature. GILDES is a six-regime computer model (Gas, the Interface between gas and liquid, the Liquid, the Deposition layer, the Electrodic region near the surface and the Solid). The simulations were compared to previously published in-situ results for copper at the same conditions analysed by a quartz crystal microbalance (QCM) and infrared reflection absorption spectroscopy (IRAS). Experimental and calculated results agree with each other with respect to the effect of corrosion, showing formic acid as the most aggressive followed by acetic and propionic acid. This is supported by a higher ligand- and proton-promoted dissolution found in formic acid exposures, followed by acetic and propionic exposures. The dominating precipitated phases were Cu2O, Cu(OH)2, Cu(CH3COO)2 · H2O, Cu(HCOO)2 · 4H2O and Cu(CH3CH2COO)2 · H2O. Besides Cu2O, the simulations suggest that the hydrated form of the respective carboxylates is the most likely compound to be formed in this type of atmospheres.