Development of an improved devitrifiable fuel cell sealing glass I.: Bulk properties

A designed compositional series of 22 devitrifiable glasses for sealing solid oxide fuel cell components was studied. Candidate oxides were selected on the basis of chemical compatibility with the fuel cell environment. The influence of each component on viscosity, thermal expansion, and crystallization were evaluated through systematic addition to a base composition. The most promising results were achieved within the system BaO-SrO-B(2)O(3)-Al(2)O(3)-Ta(2)O(5)-SiO(2). Additions of SrO and BaO maximize the thermal expansion of the bulk glass, achieving a coefficient of thermal expansion ranging from 10.8 to 13.9 ppm/K (200-500 degrees C). Devitrification of the glasses yielded similar thermal expansion coefficients ranging from 10.7 to 14.4 ppm/K. The addition of Al(2)O(3) and Ta(2)O(5) allows a critical sealing viscosity to be achieved at 900 degrees C in a glass with just 6 mol % of B(2)O(3). Five promising candidate sealing glasses have been identified. (c) 2007 The Electrochemical Society.