Oxidation behaviour of Incoloy 800HT in pure oxygen

Abstract

This work aims to investigate oxidation behavior of Incoloy 800HT in pure oxygen at atmospheric pressure. The alloy was prepared in coupon with a surface finishing up to 1200 grit SiC abrasive paper. The oxidation was performed in tubular furnace at 850°C under pure oxygen gas during the various times. Morphology and element composition of thermal oxide scale was characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. Both X-ray diffraction (XRD) and Raman spectroscopy techniques were performed to identify oxide phases. Electron micrographs illustrated different oxide morphology developed during different oxidation time. The spallation revealed multi-layer that was different in morphology and oxide species. XRD and Raman spectroscopy provided a coincident result that corundum and spinel oxides were a typical oxide grown on Incoloy800HT. The oxidation of Incoloy800HT in pure oxygen was revealed that Cr2O3 corundum oxide was an initial developed oxide, whereas, (Fe,Cr)2O3 corundum oxide and (Fe,Cr)3O4 spinel oxide were a subsequent developed oxide with different stoichiometry compositions, depending on a distance from metal/oxide interface, that the oxide preferred to be a Cr-rich (resp. a Fe-rich) at the inner part (resp. the outer part). Moreover, for a longer time, a spinel oxide became a predominant oxide instead of a corundum oxide, relating to the outer part of the thicken oxide.