Development of thermal spraying-sintering technology for solid oxide fuel cells

A thermal spraying-sintering process has been developed for an electrolyte and interconnect layer, which results in improved gas tightness, a thinner layer, and higher electric conductivity as required for solid oxide fuel ce lls (SOFCs), The process is characterized by the heat treatment of composit ion-controlled plasma-sprayed layers, For the electrolyte, the addition of MnO2 to zirconia powder is effective for reducing the sintering temperature to obtain gas tightness and for suppressing the reaction between zirconia and air electrode material, An electrolyte layer of 60 mu m thickness with sufficient gas tightness and high ionic conductivity was obtained by this p rocess. For the interconnect, chromium-rich lanthanum chromite powder, La0. 8Ca0.2Cr1.10O3, is optimum for both gas tightness and high electric conduct ivity of the layer, In addition, a single cell with a 60 mu m electrolyte w as successfully fabricated using the thermal spraying-sintering process. As a result of an operating test using O-2 and humidified H-2 at 1000 degrees C, a power density of 0.73 W/cm(2) was obtained. It was demonstrated that the thermal spraying-sintering technology is effective for the fabrication of a thin gas tight layer for SOFCs.