In-situ observation system for oxidation films using laser Raman spectroscopy was constructed and the growth processof oxide films during thermal oxidation of Fe-6.5mass%Si alloy at 1073K in O2, CO2 and CO-CO2 (PCO/PCO2=1) atmospheres was investigated. In-situ Raman spectra of the oxide films formed in these atmospheres could be_obtained using the system with an SN-filter and a chopper unit to reduce the effect of Rayleigh scattering and thermal radiation. In a CO, atmosphere strong Raman peaks of Fe3O4and α-Fe2O3 were observed even in the early stage of oxidation of the alloy, which suggested that the oxidation rate in the CO2 atmosphere was higher than that in the O2 or CO-CO2 atmosphere. Since the difference of oxidation behavior in these atmospheres was not detected by thermogravimetry, the usefulness of the system at high temperatures was confirmed.
