Hydrogen-barrier coatings against dual-atmosphere corrosion for IT-SOFC interconnect applications
Matthieu Tomas, Jan‐Erik Svensson, Jan Froitzheim
Abstract
A key component of a Solid Oxide Fuel Cell (SOFC) is the interconnect, which connects individual fuel cells in series to form a fuel cell stack. The interconnect is exposed to air and fuel in parallel; these so-called dual-atmosphere conditions cause severe corrosion on the air-side. This work investigates interconnect coatings that can mitigate this effect. Physical Vapour Deposition (PVD) coatings of Cr2O3, CeO2, YSZ, and Al2O3 on ferritic stainless steel (AISI 441) were exposed under dual-atmosphere conditions for up to 3000 h. The evolution of the corrosion products was evaluated using optical microscopy and Scanning Electron Microscopy (SEM) in combination with Energy-dispersive x-ray Spectroscopy (EDS). The SEM analysis showed that a chromia coating was not sufficient to reduce the dual-atmosphere effect, while other coatings on the fuel-side suppressed the dual-atmosphere effect by forming a barrier to hydrogen permeation. The best outcomes were observed with Al2O3 coatings on the fuel-side, which drastically reduced the dual-atmosphere effect. A 30 nm Al2O3 coating displayed acceptable Area-Specific Resistance (ASR).