Characterization of Al rich oxide layers on austenitic stainless steels by fluorescence spectroscopy

AbstractAbstractAn Al rich oxide passivation technique has been developed to improve the corrosion resistance of the stainless steel to ozone added ultra-pure water. Fluorescence spectroscopy was applied to the study on the selective oxidation of aluminum containing austenitic stainless steel in low oxygen atmosphere at 1,353K. It was found that in the thermal oxidation under low oxygen pressure, the minor alloying constitution of Al resulted in the formation of thin oxide layers. The frequency shifts of fluorescence spectra show that the compressive stresses exist in the oxide layers as a result of the difference of the thermal expansion coefficients between substrate steels and α-Al2O3, and depends on the thickness of the oxide layers. It is confirmed that pure α-Al2O3 protective layers grown on the stainless steels, which remain stable and attached to the stainless steels in ozone added ultra-pure water. These act as a diffusion barrier and protect the stainless steels from the metal dissolution.Keywords: Raman spectroscopyfluorescence spectroscopystress; α-Al2O3piezospectroscopic analysis