Improving atmospheric plasma sprayed electrolyte layers of solid oxide fuel cells by use of a powder separator

Abstract

In order to increase the performance of solid oxide fuel cells (SOFCs) the property of the electrolyte deposited by atmospheric plasma spraying (APS) has to be optimized concerning surface roughness and density. In this work, a dense YSZ coating with homogenous structure was realized on a NiO-YSZ anode which was supported by a porous metal substrate made of Crofer 22 H. A powder separator, which was able to diminish fluctuations of the in-flight particle stream, was used the first time to stabilize the APS process. During powder feeding a fully yttria-stabilized zirconia powder was on-line separated into two parts: a fraction of fine particles which were fed directly to the plasma, and a fraction of coarse particles which were collected and reused. The resulting coating exhibited a high homogeneity both in cross section and on surface. Validated by SEM images, the optimized coating did not possess any cracks and the porosity ratio was close to that found by vacuum plasma spraying (VPS) when two separators were employed. The gas leak rate shows an obvious increase of electrolyte performance compared to results without any powder separator.