Properties of Spinel Protective Coatings Prepared Using Wet Powder Spraying for SOFC Interconnects

Abstract

A wet powder spraying (WPS) method was applied to prepare protective layers of manganese cobalt spinel oxide (MCO) on commercial stainless steels of solid oxide fuel cell (SOFC) interconnects. Densification of the MCO layer was dependent on the thermal treatment condition in which a reactive sintering increased the coating density. An applied MnO sublayer reacted with the MCO layer during sintering, and resulted in secondary phase formation and limited densification. Both MCO and MnO-MCO coatings were adhering to the steel substrates and suppressed chromium diffusion during oxidation. The area specific resistance (ASR) of a test specimen including the MCO layer was 0.03 Ωcm 2 at 700°C after 800 h, lower than with MnO-MCO, which is believed to be due to the denser protective layer of the single phase and more limited chromia scale growth. Thus, an effective protective layer of metallic interconnects could be prepared using a simple wet coating method after optimization of the sintering conditions.

Self-healing atmospheric plasma sprayed Mn1.0Co1.9Fe0.1O4 protective interconnector coatings for solid oxide fuel cells

“…The effectiveness of dense chromium protective layers on metallic interconnects for solid oxide fuel cells induced a broad research on different material compositions applied by several coating techniques [5]. Hong et al [13] achieved a densification of wet powder sprayed manganese-cobalt oxide coatings by reactive sintering. This cost efficient application technique faces the time and cost consuming sintering steps.…”

In situ investigation of atmospheric plasma-sprayed Mn–Co–Fe–O by synchrotron X-ray nano-tomography

“…Due to the high operation temperature of SOFCs, a thermal expansion coefficient that is matching to the adjacent functional layers and the interconnect is as essential for protective coatings as their chemical stability in oxidizing atmosphere and a high electronic conductivity. Fulfilling these demands, Mn 1.0 Co 1.9 Fe 0.1 O 4 (MCF) was tested as material in combination with various application techniques, as there are atmospheric plasma spraying (APS) [20][21][22][23][24][25][26], wet powder spraying [27,28], aerosol deposition [18], physical vapor deposition [29] and electrophoretic deposition [14]. Compared to the others, APS combines the advantageous of achieving high density without sintering steps and relatively low manufacturing costs.…”

Impact of CeCo-Coated Metallic Interconnectors on SOCs Towards Performance, Cr-Oxide-Scale, and Cr-Evaporation

“…Different techniques are available in order to apply various types of coatings. 1,[26][27][28] They can be applied by physical vapor deposition (PVD), 24 wet powder spraying (WPS), 29 atmospheric plasma spraying (APS), 27,30,31 screen printing, [32][33][34][35] electrophoretic deposition 36 and sol-gel processing. 37 A self-healing effect was observed for a manganesecobalt-iron oxide coating applied by APS.…”