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Interfacial analyses of copper corrosion by acrylic and methacrylic acids using XPS, auger and grazing angle FTIR spectroscopy
Author(s) -
Yang D. Billy,
Wolf David
Publication year - 1995
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740230503
Subject(s) - copper , x ray photoelectron spectroscopy , fourier transform infrared spectroscopy , auger electron spectroscopy , chemistry , analytical chemistry (journal) , inorganic chemistry , chemical engineering , organic chemistry , physics , nuclear physics , engineering
We have observed that methacrylic acid (MA) is far more corrosive than acrylic acid (AA) on copper surfaces when copper was exposed to the vapor of these two acids at ambient temperature and environment. With the aid of modern surface‐sensitive instrumentation, which included grazing angle Fourier transform infrared (FTIR), XPS, x‐ray‐induced Auger electron and SEM/energy‐dispersive spectroscopies and white light stereo and metallurgical microscopy, we are reporting our results of an extensive study of the roles that MA and AA have in this unusual phenomenon of copper corrosion. By grazing angle FTIR analysis we demonstrated that copper carboxylate salt formation is very rapid upon short contact with the vapor of both acids, and the acids showed no evidence of polymerization. We have also demonstrated by XPS and x‐ray‐induced Auger electron spectroscopy that copper surfaces exposed to the MA vapor contains mainly Cu(II) species. However, the oxidation state of the copper exposed to AA vapor will depend on exposure time and environment. With limited exposure to the air, the copper surface remained shiny for up to 12 months test time. The spectrum obtained from the shiny area of the AA/Cu surface shows that it contains mainly Cu(I) mixed with some copper (II). When the spectrum was taken from a dull area of AA/Cu surfaces, the Cu(II) state was found to be predominant. These results strongly indicate that when the shiny AA/Cu surface changed to a dull color, the oxidation state of the copper also changed from +1 to +2. The molecular structure of the Cu(II)–AA salt is also believed to be altered. Both stereo microscopic and SEM/energy‐dispersive spectroscopy techniques were also used to perform the visual and microanalysis of the surface texture and elemental compositions of the corroded surfaces, respectively. The presence of oxygen was also found to play an important role in the overall corrosion processes. The differences in molecular structure of copper carboxylate salts of different oxidation states are discussed and are believed to be responsible for this unusual phenomenon. We believe that this finding will provide a good explanation for the cause of drastic differences of copper corrosion by acrylic and methacrylic acids.