Modern Problems of Materials Science
Investigation of the Co-Free Spinel Used in a Role of Protective Layers in Soc Application
Monika Łazor (Monika.Lazor.dokt@pw.edu.pl) 1,2,3, Leszek Ajdys1,2,3, Yevgeniy Naumovich1,2, Blanka Seredyńska3, Paulina Wiecińska3, Agnieszka Żurawska1,2
1. Center for Hydrogen Technologies CTH2, Institute of Power Engineering
2. Department of High Temperature Electrochemical Processes, Institute of Power Engineering
3. Chemical Faculty, Warsaw University of Technology
PDFKeywords
interconnect, protective coating, pre-oxidation, spinel oxides, EPD
Abstract
Interconnects have a significant role in the SOC (Solid Oxide Cell) stacks. These elements provide electrical contact by the transfer of electrons between adjacent cells, while simultaneously preventing the mixing of fuel and oxidant streams. Typically, interconnects are composed of ferritic steel with high chromium content that can result in the growth of an oxide layer on the steel surface and the evaporation of harmful volatile chromium compounds directly impacting on the air electrode. This phenomenon leads to a loss of the stack performance. In order to prevent degradation of SOC stacks caused by CrOx volatility, their surface is covered with special ceramic protective layers. Additionally, the coating should have a low area specific resistance (ASR), uniformity, and strong adhesion across the whole coated region. State-of-the-art materials are based on Mn1+xCo2-xO4 group spinel (MCO, x usually 0.5 or 1). However, the utilization of cobalt in SOC technology at an industrial level is hindered by its toxicity, scarcity, and supply uncertainty. Nevertheless, merely applying ceramic coatings to interconnects may not be sufficient, particularly in the context of steel corrosion, so there is a need of additional thermal treatment of the steel substrate depending on the used temperature and atmosphere.