Barium-free sealing materials for high chromium containing alloys

Abstract

The key-requirements for glass ceramic sealing materials to achieve high efficiencies in planar solid oxide fuel cells are leak tightness, high insulating resistance, and low reactivity in contact with the anode or cathode gases and the interconnect material. Therefore SCHOTT has developed special glasses and glass-ceramics for chromium alloys, like Cr5FeY (CFY, Plansee SE). Especially the CFY material requires adapted sealing materials due to its lower coefficient of thermal expansion (CTE) compared to ferritic stainless steels and the possibility for interface reactions originating from the high chromium content and the glass seal components. In this study, new glass-ceramic sealing materials for chromium containing alloys are presented. Results show that barium-free glass-ceramics are advantageous when sealing high chromium alloys in terms of interface reactions. Because of the absence of barium oxide, formation of detrimental chromate phases at the interface was avoided. The new glasses show low porosity, high hermeticity, and strong bonding toward the CFY material, fulfilling the requirements of SOFC sealants. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.