Oxygen pump method for leak rate testing of SiO2–B2O3–Al2O3–BaO–PbO2–ZnO glass sealant for SOFC

A method for oxygen leak rate testing was presented based on oxygen pump technique. In this method, using the theory of oxygen pump and oxygen sensor, a formula for the calculation of leak rate was derived from Nernst equation, Faraday law and ideal gas law. In the gas leakage testing, a glass sealant based on SiO2–B2O3–Al2O3–BaO–PbO2–ZnO (named AF8) was used to seal two yttria stabilized zirconia (YSZ) plates together to form a small gas chamber, one plate worked as oxygen pump and the other worked as oxygen sensor. Constant current was applied on the oxygen pump to take out/into oxygen from the gas chamber resulting in its oxygen partial pressure change, the corresponding concentration voltage data were collected continuously for the calculation of the oxygen leak rate. With this method, the calculated leak rate of AF8 was 8.2 × 10− 8 mbar l s− 1 cm− 1 at 800 °C which was smaller than the required value of 10− 7 mbar l s− 1 cm− 1.