In exploring the solid oxide fuel cell (SOFC) sealing applicability of boroaluminosilicate glass, the crystallization of 4K2O-1Li2O-12MgO-10B2O3-40SiO2-16Al2O3-12MgF2 composition with and without containing 5PbO/BaO/ZnO (wt.%) content were studied by means of dilatometry, DSC, XRD, FTIR, SEM and microhardness analysis. Density of base K-Li-Mg-B-Si-Al-F glass (2.59 g.cm–3) is found to be increased on addition of the network modifier oxides PbO, BaO and ZnO content. Addition of Pb2+, Ba2+ and Zn2+ furthermore increased the glass transition temperature (Tg) and decreased coefficient of thermal-expansion value (<7.55×10-6/K, 50-500°C). A characteristic exothermic peak is found to be appeared in DSC thermograph at the temperature range 800-900°C; and that is ascribed to the formation of crystalline phase fluorophlogopite mica, KMg3(AlSi3O10)F2. Opaque glass-ceramics were prepared from K-Li-Mg-B-Si-Al-F glasses (with and without containing PbO, BaO and ZnO content) by controlled heat-treatment at 1000°C. Interlocked type microstructure combined of flake like fluorophlogopite mica crystals is obtained in ZnO-containing K-Li-Mg-B-Si-Al-F glass-ceramic; and such microstructural pattern is ascribed to cause large thermal-expansion (10.91-13×10-6/K, 50-800°C). ZnO-containing boroaluminosilicate glass-ceramic is, hence, considered with potential interest as they can exhibit the microcrack resistivity in high temperature recycling operation (like SOFC).
Keywords: Boroaluminosilicate glass; crystallization; fluorophlogopite mica; microstructure; SOFC
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