United Technologies Corporation

Joseph Powers

John C Trocciola

Ronald G Martin

A matrix for holding the electrolyte within a phosphoric acid fuel cell is made from silicon carbide and a binder of polyestersulfone. Preferably the matrix consists of 10-20 weight percent polyethersulfone with a balance of silicon carbide. The matrix has improved strength, wettability and bubble pressure compared to the best known prior art matrix.

Silicon carbide matrix for fuel cells

A seal material especially adapted for phosphoric acid fuel cell stack sealing is described comprising an unfilled, unoiled high molecular weight polytetrafluoroethylene. Although the seal material is especially adapted as the regular seal around the plenums separating the oxygen and hydrogen gas inlets and outlets, it can also be used as a plenum or stack crack sealer. The material provides seal integrity and stability at temperatures in excess of 400.degree. F. (204.degree. C.)., e.g. 400.degree. F. to 450.degree. F. (204.degree. C. to 232.degree. C.), in a corrosive chemical environment at differential pressures above 50 psi (e.g. 50 psi to 80 psi). It can be used in electrochemical cells in general where high temperature, high pressure, corrosive environments prevail.

High temperature, high pressure chemical resistant seal material

A thermally conductive caulk particularly suited for use in a phosphoric acid fuel cell is made by mixing graphite into a stable aqueous dispersion of polytetrafluoroethylene and fluorinated ethylene propylene such that the solids floc to form a paste. The paste is applied to the part to be caulked and then dried and heat treated. Caulks made according to the present invention have good thermal conductivity and absorb very little phosphoric acid.

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Riverside, CT, United States of America

Joseph Powers