Chemical and thermomechanical compatibility between Ni–GDC anode and electrolytes based on ceria

Abstract

The scope of the present work is to study the thermal and chemical compatibility between a Ni–Ce 0.9Gd 0.1O 1.95 cermet, with 39 vol.% Ni, and two electrolytes based on Ce 0.9Gd 0.1O 1.95 (GDC). The cermet was synthesized as a composite NiO–Ce 0.9Gd 0.1O 1.95 by a polymeric organic complex solution method and subsequently reduced to Ni–Ce 0.9Gd 0.1O 1.95 cermet. The GDC electrolytes were prepared by: (a) chemical precipitation process with nitrates as precursors and (NH 4)OH as precipitant agent and (b) from a commercial submicronic powder modified with 1.0 wt.% Bi 2O 3 for improving the sintering mechanism. The anode was fixed on the electrolyte by isostatic pressing of powders and the obtained sandwich was cosintered between 1350 and 1400 °C for 2 h to obtain dense electrolytes with high ionic conductivity along with well-developed anode/electrolyte interfaces of solid oxide fuel cells. The cosintered anode/electrolyte interfaces were characterized by using scanning electron microscopy. The study of the possible diffusion of nickel from the anode into the electrolyte was performed by EDAX analysis. The reaction products formed into cosintered materials were determined by X-ray diffraction (XRD). It is found that the anode is compatible with both electrolytes up to 1400 °C without formation of new phases at these temperatures even during prolonged treatments.