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

Abstract

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.