High Temperature Oxidation of the Austenitic (35Fe27Cr31Ni) Alloy Sanicro 28 in O-2 + H2O Environment
Artikel i vetenskaplig tidskrift, 2010

The present study investigates the high temperature oxidation of alloy Sanicro 28 (35Fe27Cr31Ni) in 5% O-2 and in 5% O-2 + 40% H2O. Polished steel coupons were isothermally exposed in a tube furnace at 600, 700 and 800 A degrees C for up to 168 h. The samples were investigated by gravimetry, grazing angle X-ray diffraction (XRD), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy/energy dispersive X-rays (STEM/EDX). The results show that the material forms a protective scale in both environments. The scale is duplex. The inner part of the scale consists of corundum type chromium-rich (Cr (x) Fe1-x )(2)O-3, and the outer layer consists of spinel type oxide. Chromia is lost from the protective oxide by vaporization of CrO2(OH)(2) in O-2 + H2O environment. The capacity of Sanicro 28 to suffer chromia vaporization without forming a rapidly growing iron-rich oxide is attributed to its high Cr/Fe ratio. The spinel formed at the oxide/gas interface could in addition be beneficial for oxidation behavior in wet oxygen because it may slow down chromia evaporation.

Water vapor

stainless-steel

evaporation

Oxidation

oxides

Evaporation

900-degrees-c

Sanicro 28

304l

oxygen

water-vapor

flow-rate

chromium

Författare

Carolina Pettersson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Torbjörn Jonsson

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Christian Proff

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Mats Halvarsson

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Jan-Erik Svensson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Lars-Gunnar Johansson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Oxidation of Metals

0030-770X (ISSN) 1573-4889 (eISSN)

Vol. 74 93-111

Ämneskategorier

Kemi

DOI

10.1007/s11085-010-9199-1