Nickel/Yttria-Stabilized Zirconia Cermets from Combustion Synthesis: Effect of Process Parameters on Product Microstructure

The synthesis of a nickel/yttria-stabilized zirconia (Ni/YSZ) cermet with tailored microstructural characteristics has much interest for many solid-state electrochemical applications. These materials are generally obtained through a route based on the reduction, via hydrogen gas, of poorly sintered mixtures of YSZ with nickel oxide. The present paper proposes an alternative route based on a thermite reaction performed in a combustion regime. Such an approach indicates the application of combustion synthesis or a self-propagating high-temperature synthesis (SHS) technique. The more-interesting features of this route include the absence of any external source of energy during the reaction, the possibility to synthesize a porous cermet in a single step, its sintering, and the doping of the ceramic component with yttria. The synthesis of Ni/YSZ cermets through this route is analyzed in some detail, and this analysis shows the influence of the process parameters on the phase composition and microstructure of the products.