Plasma-sprayed 3.9YSZ porous coatings with mille-feuille structure and high composite porosity for SOFC applications

摘要

A porous coating process for direct-oxidation solid oxide fuel cell (SOFC) electrodes that reduces manufacturing costs and production time is proposed. The process uses Al alloy-polyester as a pore former to create a mille-feuille structure and high porosity in plasma-sprayed 3.9mol% yttria-stabilized zirconia (3.9YSZ) coatings. With an insufficient amount of pore former (35vol.%), the as-sprayed coating surface has a higher surface roughness (R_a=12-13μm). When a sufficient amount of pore former (50vol.%) is used, the as-sprayed coating surface roughness (R_a) is 10-11μm. Apparent porosities in the range of 41.2 to 56.4vol.% are obtained for the etched and burned plasma sprayed coating. The porosity created with a sufficient amount of pore former (50vol.%) is significantly higher than that created with an insufficient amount (35vol.%). The monoclinic phase originally in the 3.9YSZ feedstock powder almost completely disappears after plasma spraying.