Characteristics of a SiO2–B2O3–Al2O3–BaCO3–PbO2–ZnO glass–ceramic sealant for SOFCs

A glass system based on SiO2–B2O3–Al2O3–BaCO3–PbO2–ZnO was prepared and a sort of compounding was optimized to determine the composition with best performance named AF8. The technical thermal expansion coefficient (t-TEC) is 10.58 × 10−6 K−1 between 323 and 773 K. The resistivity of AF8 is 1.95 × 104 Ω cm at 800 °C. The optimum sealing temperature range was 850–880 °C. AF8 glass sealant could adhere with electrolyte of yttria stabilized zirconia (YSZ) well and there were no perforative pores in the sealant. The leak rate of AF8 glass was 0.81 × 10−7 mbar l s−1 cm−1 at 800 °C tested by oxygen coulometric titration which was closed to the required value. Around the sealing temperature, contact angle of AF8 on YSZ is about 110°. This angle can make them adhere well under a suitable pressure, and also avoids glass spreading freely on surface of the electrolyte. All measured results approved that AF8 may become a practical sealant for SOFCs.