Anomalous scattering study of oxide scales formed at 1173 K on surface modified stainless steel

The effect of lanthanum deposits on AISI 304 grade stainless steels has been studied by anomalous scattering, X-ray diffraction, Rutherford backscattering spectrometry (RBS) and scanning electron microscopy coupled with a energy dispersive spectrometer (SEM-EDX). The lanthanum deposits were obtained by the pyrosol method which implies the interaction at 473 K of an aerosol of lanthanum nitrate with the steel surface. The deposits enhance the corrosion resistance of the stainless steels specimens under synthetic air at 1173 K by a factor of three with respect of the non-treated steels. The main crystalline component of the protective oxide scale is demonstrated to be Fe2O3. This result is explained on the basis of the oxide crystallinity and the chemical reactions at the alloy surface during the deposition procedure.