Analysis of oxide scales on oxidised EN 1.4509 ferritic stainless steel catalyst support by scanning electron microscopy

Abstract

This study aims to investigate the oxidation behaviour at high temperature of a commercial ferritic stainless steel EN 1.4509. Tests of high temperature oxidation in air were carried out under isothermal condition (950 ºC) with different exposure times in order to obtain the oxidation kinetics law associated to this material. The surface and cross-section were analysed by scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM/EDS), where the oxide scales proved to be formed by an external Mn-Cr spinel and an inner chromia layer. These oxides were generated by the migration of metallic cations from the stainless steel to the atmosphere. The size of the generated spinel crystals increased when increasing the exposure time as well as the cross-section thickness did. Moreover, the surface modification of ferritic stainless steel EN1.4509 was studied when platinum is deposited on its surface. The feature of this surface-modified ferritic stainless steel against oxidative atmosphere was evaluated by SEM/EDS. This platinum deposition led to reach a different surface morphology in terms of crystal size and nature.