A sedimentation process for the fabrication of solid oxide fuel cell cathodes with graded composition

Materials with graded composition can be obtained by a sedimentation process during which particles of a powder mixture within a suspension fall by gravity upon a substrate. This process has been used to fabricate bulk SOFC cathodes by sedimentation of lanthanum strontium manganate (LSM) and yttria stabilised zirconia (YSZ) powder mixture upon a dense YSZ substrate and subsequent firing. A numerical simulation of sedimentation based on Stokes' law has been developed to control material and process parameters. Two cathodes with different composition gradients have been obtained by changing the initial conditions of the sedimentation. Their compositions estimated by electron dispersive spectrometry (EDS) have been found to be in reasonably good agreement with the prediction of the numerical model.