Abstract
The composition of thin oxide film formed on SUS 304 stainless steel in 30% HNO3 solution was examined by the combined use of XPS and FT-IR spectroscopy. From the XPS and IR results, it is concluded that the oxide film was composed of a mixture of CrO3 (or Cr2O72-), Cr2O3, Fe2O3 containing a small amount of CrOOH and γ-FeOOH. The XPS results are not always consistent with the IR results. There is some possibility that hexavalent ions of chromium in the film is converted into trivalent ions during XPS measurement in a ultra high vacuum of 5×10-10torr.
