Investigation of Chromium Volatilization from FeCr Interconnects by a Denuder Technique
Artikel i vetenskaplig tidskrift, 2010

A technique is presented for accurate and time-resolved quantification of chromium volatilization from alloys at high temperature. A denuder tube which is coated with Na2CO3 is placed downstream of the samples. CrO2(OH)(2) that evaporated from the samples is collected on the denuder and converted to the thermally stable Na2CrO4. The chromate is then dissolved in water and determined quantitatively. Three commercially available ferritic 22% Cr steels intended for use as solid oxide fuel cell interconnect materials (Sanergy HT, Crofer 22 APU, and ZMG 232) have been investigated with respect to chromium volatilization and oxidation rate. The effect on chromium volatilization of a submicrometer cobalt coating on the steel surface is reported. Comparisons are made with a conventional thick ceramic coating. The experiments are carried out at 850 degrees C in N-2 - 20% O-2 - 3% H2O atmosphere. The submicrometer Co coatings proved to be very efficient, reducing Cr volatilization by 1 order of magnitude. Microscopic studies show that both uncoated steel and steel coated with a submicrometer cobalt film develop two-layered oxide scales with the bottom part consisting of a Cr-rich corundum-type oxide. The uncoated samples develop a top layer consisting of (Cr, Mn)(3)O-4 oxide, whereas the Co-coated samples exhibit a top layer consisting of Co-rich spinel oxide. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3462987] All rights reserved.

oxide fuel-cells

alloys

base

cathode

transport

ferritic stainless-steels

sofc interconnect

oxidation

evaporation

vaporization

coatings

Författare

Jan Froitzheim

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Hamed Ravash

Chalmers, Kemi- och bioteknik

E. G. Larsson

Chalmers University of Technology

Lars-Gunnar Johansson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Jan-Erik Svensson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Journal of the Electrochemical Society

0013-4651 (ISSN)

Vol. 157 9 B1295-B1300

Ämneskategorier

Kemi

DOI

10.1149/1.3462987