Georg Kunschert

Recent Development Aspects of Metal Supported Thin-Film SOFC

In recent years, the metal supported solid oxide fuel cell (MSC) technology has attained high interest for the electrical power supply in vehicles as an Auxiliary Power Unit (APU) that operates independently from the main engine. Its advantages compared with other fuel cell technologies can be seen in a higher mechanical stability and in a better thermo and redox behaviour. Those attributes are urgently needed for mobile applications.

Ceramic PVD Coatings as Dense/Thin Barrier Layers on Interconnect Components for SOFC Applications

In the last decade of SOFC metallic interconnect component development barrier coatings have proven being indispensable as functional layers and therefore gained serious attention. Diffusion processes at the interface between metallic and other cell materials have demonstrated harmful influence on degradation of SOFC stacks. Recent scientific developments of perovskite barrier layers show that innovative pulsed PVD technologies make it feasible to deposit thin films of highest density and conductivity. Simultaneously, through applying PVD methods it is possible to drastically reduce the employed perovskite material. PVD coatings in the thickness range of around 1 µm have been applied on porous substrates of Plansees P/M ODS ferritic FeCr- alloy ITM for MSC type SOFC as well as on bulk components. Long term oxidation tests at 850{degree sign}C in combination with SEM/EPMA imaging and element sensitive mappings are shown and verify the functionality of described coatings as diffusion barrier layers.

Investigation of Oxide-Nucleation on Ferritic FeCr Interconnect Alloys for Solid Oxide Fuel Cells Exposed to Anode and Cathode Gases at 850°C

In recent years solid-oxide fuel cell (SOFC) interconnect components have proven to be a key-component accountable for the functionality of high temperature fuel cells. Amongst adequate thermal expansion and high temperature strength, highest oxidation resistance in anode and cathode gases under thermal cycling conditions is required in order to reach long term durability, particularly when using thin film light-weight components with particular focus on automotive applications. In order to match the challenging parameter profile Plansee developed the mechanically alloyed ITM, a ferritic P/M Fe26Cr alloy strengthened with additions of Y2O3 dispersoids, since it has been observed that apart from their HT strengthening effect, which is of specific interest for thin sheets components, finest ODS particles reduce the growth and enhance the adhesion of the forming oxide layers. The latter effect is of particular interest in applications where alloys are exposed to HT cyclic conditions. In this work the nucleation phase of the oxide scale formation on P/M ODS Fe26Cr ITM is compared to that on a reference ingot steel Fe22Cr in typical anode gases containing significant amounts of H2, CO and approximately 3% H2O as well as in laboratory air at 850°C. Thermal cycling oxidation tests following the COTEST standard up to 168h are carried out in both environments. Moreover cyclic oxidation tests are performed in dry anode gas. Detailed studies of oxide scale formation and evolution by means of electron microscopy of cross sections as well as oxide surfaces are undertaken.