New route to prepare anodic coatings on dense and porous metallic supports for SOFC application

Abstract

Metallic cell supports have been developed for the new generation of fuel cells. A sol—gel process has been used to prepare anodic coatings on these supports at moderate thermal treatment temperature, in order to keep good support mechanical behavior and limit metallic corrosion. Indeed, we take advantage of the numerous reaction routes that the sol—gel method can offer to first synthesize NiO—YSZ (yttria-stabilized zirconia) homogeneous composites, and then to process films of different thicknesses on metallic supports by dip-coating. In this work, the metallic supports could be either dense or porous. To begin with, duplex microstructured anodes were prepared from both thin and thick layers, directly deposited on dense metallic supports. The interfacial anodic layer, around 100 nm thick, improves adhesion and accommodates stresses between the metallic interconnect and active thick anode. Moreover, by dipping the substrate into an optimized slurry containing sol—gel composite powders, films a few microns thick have been obtained, and constitute the active anodic part. A heat treatment at only 800°C leads to a coherent anodic duplex stacking which is continuous, homogeneous and adherent. Subsequently, thick anodic films have also been deposited on two different porous supports, with both the dip-coating process and slurry routes. These thick anodic coatings were characterized after thermal treatment at 800°C.