High-temperature glassy-ceramic sealants SiO2-Al2O3-BaO-MgO and SiO2-Al2O3-ZrO2-CaO-Na2O for solid oxide electrochemical devices

Glasses of the SiO2-Al2O3-BaO-MgO and SiO2-Al2O3-ZrO2-CaO-Na2O systems were synthesized in the perspective to apply them as sealants in SOFC at operating temperatures of 700-900 °C. Thermal properties of the chosen glass compositions and their compatibility with the SOFC materials (YSZ-electrolyte and alloy-interconnector Crofer22APU, 15×25T) were investigated by means of synchronic thermal analysis and high-temperature dilatometry. The elemental analysis was performed by atomic emission spectroscopy. The average values of the temperature coefficients of the linear extension are 10.0×10−6 °C−1 for glass 45%SiO2- 15%Al2O3-25%BaO-15%MgO and 9.5×10−6 °C−1 for glass 60%SiO2-10%Al2O3-10%ZrO2-5%CaO-15%Na2O. The gluing microstructure in YSZ/glass/Crofer22APU was studied by scanning electron microscopy. The crystallization process of silicate phases was revealed to occur in the SiO2-Al2O3-BaO-MgO glass. The analysis of the crystallization products was performed by Raman spectroscopy and X-ray diffraction. Glassy ceramics was proved to possess better parameters in comparison with amorphous glass to be used as a sealant in electrochemical sensors and oxygen sensors. The SiO2-Al2O3-ZrO2-CaO-Na2O low-temperature amorphous glass can be applied in SOFC.