Integrated fabrication process for solid oxide fuel cells using novel plasma spraying

This study was aimed at developing an integrated fabrication process for solid oxide fuel cells (SOFC) with radio-frequency plasma spraying (RFPS) and/or hybrid plasma spraying (HYPS). Fundamental studies concerning particle velocity and deformation showed that the novel plasma spraying processes were mainly characterized by their superior capability for homogeneous heating and spraying of large size powders with relatively low particle velocity, and that even the lower particle velocities in RFPS (20 ms(-1)) and HYPS (40-70 ms(-1)) compared with those in direct current plasma spraying (200 ms(-1)) were found to be sufficient for deformation of impinging molten particles on the substrate. However, RFPS imposed a severe limitation on the substrate position because it led to a short flying distance for the molten particles. In this respect, HYPS was considered to be superior to RFPS. With 75 mu m YSZ powder, use of HYPS made it possible to get not only dense YSZ coating with relative density higher than 98% but also good gas permeability, lower than 5.7 x 10(-7) cm(4)g(-1)s(-1) (2500 mm H(2)O). Moreover, porous NiO and chemically stable LaCoO(3) could be prepared as electrodes by Ar-O(2) HYPS. Though the cell performance has not been investigated yet. these experimental results have proved that HYPS must be a strong candidate for new aspects of the production of SOFC. especially from economic and engineering points of view.