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

Abstract

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.