ELECTRICAL-PROPERTIES OF NI YSZ CERMETS OBTAINED THROUGH COMBUSTION SYNTHESIS/

The synthesis of NI/YSZ cermet with controlled microstructural charact eristics presents a lot of interest for many solid-state electrochemic al applications. These materials are generally obtained by reducing po orly sintered mixtures of YSZ with nickel oxide by hydrogen. We recent ly proposed an alternative route based on a thermite reaction performe d in a combustion regime. This method makes it possible, in one step, to synthesize highly porous cermet, to sinter the ceramic fraction, an d to dope it with yttria. Such an approach represents an application o f combustion synthesis or the self-propagating high-temperature synthe sis (SHS) technique. We present here electrical characteristics of Ni/ YSZ cermets produced by this method. The total electronic conductivity shows an unusually smooth percolation threshold. This fact makes it p ossible to obtain a fairly high electronic conductivity even at relati vely low metal Volume fractions. The ceramic fraction shows an excelle nt degree of sintering and an ionic conductivity not too different fro m the conductivity of YSZ single crystals with the same composition. ( C) 1998 Elsevier Science B.V. All rights reserved.