Manufacturing of NiO/NiTiO3 porous substrates and the role of zirconia impurities during sintering

Anode substrates based on Ni/TiO2 cermets were fabricated for planar solid oxide fuel cells (SOFC) with the aim of improving the thermoelastic behavio r of Ni/8 mol.% Y2O3-stabilized zirconia (8YSZ) substrates. This offers the possibility of adjusting the thermal expansion coefficient to any electrol yte membrane considered. NiO/NiTiO3 specimens were fabricated from Coat-Mix (R) powders by rate-controlled and constant heating rate sintering. The hea t treatments led to a significant change in activation energy and, especial ly at high sintering temperatures, in the morphology of the microstructures compared with NiO/8YSZ substrates. A TEM investigation revealed droplet-sh aped impurities at the grain boundaries, which are regarded as the reason f or liquid phase sintering of these substrates. (C) 1999 Elsevier Science S. A. All rights reserved.