Mn–Co spinel protective–conductive coating on AL453 ferritic stainless steel for IT-SOFC interconnect applications

Abstract

This paper presents research on the synthesis and properties of the Mn 1.5 Co 1.5 O 4 (MC) spinel powder, as well as its application for the preparation of a MC thick film on the AL453 steel to be used for metallic interconnect material in IT-SOFCs. In order to prepare the MC micropowder with excellent homogeneity of the chemical and phase compositions, EDTA gel processes were utilized. In order to improve the contact electrical resistance between an AL453 steel interconnect and the La 0.8 Sr 0.2 FeO 3 (LSF) cathode and protect the cathode from Cr poisoning, the surface of the AL453 steel was coated with a protective manganese cobaltite spinel matrix using screen printing in combination with an appropriate heat treatment. The oxidation of the AL453/MC composite layer carried out in the air-H 2 O gas mixture at 1,073 K for 55 h showed that the spinel coating may serve as an effective barrier against outward Cr diffusion from the AL453 steel and, therefore, significantly inhibit the formation of volatile Cr vapors from the chromia scale. The contact ASR study of the interconnect-cathode interface in the AL453/MC/LSCM/LSF/LSCM/MC/AL453 system carried out in the range of 723−1,073 K in air showed a very large drop in ASR compared to the resistance of the AL453/LSCM/LSF/LSCM/AL453 system without the spinel coating.

Oxidation properties of the Crofer 22 APU steel coated with La0.6Sr0.4Co0.2Fe0.8O3 for IT-SOFC interconnect applications

“…This modification is carried out by depositing active protective-conducting coatings on the steel's surface [9,10]. Many types of coating materials are in use, including La 0.9 Sr 0.1 MnO 3 [11], La 0.8 Sr 0.2 CoO 3 [12], Agperovskite [13], (Mn,Co) 3 O 4 [14][15][16], and Y or Co [17,18]. Such a modification makes it possible for the layered substrate made of corrosion-resistant steel and the protective-conductive coating to achieve low electrical surface resistance that does not change in time as well as high resistance to cyclic thermal oxidation and to effectively prevent chromium migration from the chromium-containing steel substrate.…”

Evaluation of electrodeposited Mn‐Co protective coatings on Crofer 22 APU steel

“…An effective solution is to coat the alloy surface with protective layers . Many different materials have been evaluated for a possible corrosion protection . Among the materials, Mn‐Co spinels have been proposed as being very effective in reducing chromium evaporation .…”

Influence of yttria surface modification on high temperature corrosion of porous Ni22Cr alloy

“…In the case of the Cr rich alloys used in the fuel cell industry, the oxide usually is Cr 2 O 3 which offers protection of the alloy and have high enough electrical conductivity at high temperatures. The corrosion issues of the dense metallic plates are studied for a long time and currently are often solved by applying protective coatings on their surface . These coatings lower the rate of the oxide scale formation and thus influence the interfacial electrical resistance.…”