Initial Atmospheric Corrosion of Copper Induced by Carboxylic Acids

Abstract

The interaction of carboxylic acids with copper is a phenomenon found both outdoors and, more commonly, indoors. The influence on copper of some carboxylic acids (formic, acetic, propionic, and butyric) have so far been studied at concentrations levels at least three or four orders of magnitude higher than actual indoor conditions (< 20 ppb, volume parts per billion), and with only limited emphasis on any mechanistic approach. In this licentiate study a unique analytical setup has been successfully applied for in situ characterization and quantification of corrosion products formed during initial atmospheric corrosion of copper in the presence of acetic, formic or propionic acid. The setup is based on monitoring mass changes by the quartz crystal microbalance (QCM) and simultaneously identifying the chemical species by infrared reflection-absorption spectroscopy (IRAS). Post-analysis of corrosion products was performed by coulometric reduction (mass of copper (I) oxide formed), grazing incidence xray diffraction (phase identification) and atomic force microscopy (surface topography). The absolute amounts of mass of individual constituents in the corrosion products, mainly copper (I) oxide or cuprite, copper (II) carboxylate and water or hydroxyl groups, have been deduced in situ during exposure in 120 ppb of carboxylic acid concentration, 95% relative humidity and 20ºC. An overall result is the consistency of analytical information obtained. For copper (I) oxide the quantified data estimated from IRAS, QCM or coulomeric reduction agrees with a relative accuracy of 12 % or better. The interaction of copper with the carboxylic acids seems to follow two spatially separated main pathways. A proton-induced dissolution of cuprous ions followed by the formation of copper (I) oxide, and a carboxylate-induced dissolution followed by the formation of copper (II) carboxylate. The first pathway is initially very fast but levels off with a more uniform growth over the surface. This pathway dominates in acetic acid. The second pathway exhibits iii a more constant growth rate and localized growth, and dominates in formic acid. Propionic acid exhibits low rates for both pathways. The difference between the carboxylic acids with respect to both total corrosion rate and carboxylate-induced dissolution can be attributed to differences in acid dissociation constant and deposition velocity.

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

“…This is in agreement with experimental results where the hydrated form of the carboxylate was considered more likely to be formed in a low pollutant atmosphere (120 ppb). 10,11 The constants for surface dissolution reactions were chosen to have the same value as in previous estimations for copper in SO 2 environment. 9 But both parameters were varied in order to investigate their influence in the corrosion process.…”

“…11 We consider next the variation of some constants and how they influence the simulated results, in order to explore possible reasons for differences with the experimental results. Figure 5 shows the influence of the K H constant on the precipitated amount of the hydrated acetate.…”

Alkanethiols as Inhibitors for the Atmospheric Corrosion of Copper Induced by Formic Acid: Effect of Chain Length

“…3,4 The copper corrosion mechanism induced by low concentrations of carboxylic acids has been extensively studied both experimentally 2 and through GILDES, a multiregime computer model which involves the gas phase (G), the gas/liquid interface (I), the liquid phase (L), the deposition layer (D), the electrodic region near the surface (E), and the solid phase (S). For more details, see.…”

Sensing the Instant Corrosivity of Haze Using Electrochemical Probes by Electrochemical Noise Technique

“…Nishikata et al [29][30][31][32][33][34][35][36] used EIS to study the corrosivity of atmosphere to different types of steels, and the effects of electrolyte concentration and pH value on the atmospheric corrosivity of metal were also studied. EIS was used to study the atmospheric corrosion of steel under an electrolyte film in wet-dry cycles by Dong et al 37 Leygraf et al [38][39][40] used situ X-ray transmission spectromicroscopy, infrared reflection absorption spectroscopy (IRAS) and a quartz crystal microbalance to investigate the atmospheric corrosivity of metals.…”