Research On Synthesizing And Performance Of Sealant For Solid Oxide Fuel Cells

A fuel cell is a device that can convert chemical energy directly to electrical energy with high efficiency and low pollution. There are two basic designs for SOFC applications: tubular and planar. Compared with tubular designs, planar designs have significant advantages: including lower cost and higher power densities. However, planar designs must overcome a significant challenge: the need for effective, high temperature sealing materials to prevent fuel leakage. Thus it is a strict request to sealing materials. So the performance of SOFC is always influenced by sealants and sealing techniques.AF is a series of glass sealants operated at middle or high temperature which is based on the materials of SiO₂ - B₂O₃ - Al₂O₃ - BaCO₃ - PbO₂ - ZnO. According to the different proportions every system has a certain name. Based on the previous research two glass compositions named AF8 and AF9 with better performance than others were investigated further more. In this paper, the particle size distribution of ball-milling powders, the resistivity and thermal expansion coefficient were compared between them. Gas leakage and wetting performance at high temperature of AF8 were studied as emphases.In this thesis, a novel method to measure leakage rate was presented based on oxygen coulometric titration. In this method, using the principle of oxygen pump and oxygen sensor, a formula for the calculation of leakage rate was derived from Nernst equation, Faraday law and ideal gas law. In the gas leakage test, AF8 was used for sealing two YSZ discs to form a gas chamber, constant current was applied on the oxygen pump to take out oxygen from the gas chamber and cause its oxygen partial pressure change, then the concentration...