Sol-gel/co-precipitation method for the preparation and characterization of zirconia-tungsten composite powders

Abstract

Sol-gel and co-precipitation are interesting processes in view to prepare ceramic-metal composite powder. Using metal salts as starting compounds it is possible in a first step to synthetise a mixed precipitate and in a second reduction step, in a H₂/Ar atmosphere, to obtain such a composite powder. Stabilized zirconia-tungsten composite powder have been prepared by this way without mixing and milling steps. Each step of the synthesis has been characterized. Stability of the mixed precipitate suspension and surface area of the dried powder are largely influenced by the tungsten salts content. The temperature of formation of zirconia changes from 510 °C without tungsten precursor up to 695 °C for a 60% tungsten molar ratio composition. Composite zirconia-tungsten powders, in a large range of composition, are obtained at 1100 °C with morphologies depending on humidity and thermal treatment conditions.