Characterization of the oxides formed at 1000 °C on the AISI 304 stainless steel by X-ray diffraction and infrared spectroscopy

Abstract

The aim of this work is to show the contribution of the infrared spectroscopy (FT-IR) to the identification of the oxides formed on the AISI 304 stainless steel during isothermal oxidation at 1000 °C, in air. This work focuses on the differentiation of spinel type AB 2O 4 structures and corundum type M 2O 3 structures. It is shown that after 100 h oxidation, the scale is composed of two subscales. The structural analyses were performed both on the adherent subscale and on the external subscale, which spalled off during cooling to room temperature. In the spalled subscale, the infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses exhibit the presence of two spinel phases: Mn 1.5Cr 1.5O 4 and FeCr 2O 4, as well as hematite Fe 2O 3. The FT-IR and XRD analyses of the adherent subscale enable us to distinguish the spinel Mn 1.5Cr 1.5O 4 and FeCr 2O 4 structures which are difficult to identify by XRD alone. Chromia Cr 2O 3 appears to be slightly present in the adherent subscale. According to our results, the parabolic regime of the kinetic curve corresponds to a scale growth mechanism governed by an inward oxygen diffusion.