Synthesis of Ag/ZnO mixture for powdered contact materials

The processes of a ultrafine Ag/ZnO mixture produced by coprecipitation from salt solutions were investigated. The coprecipitation in AgNO₃-ZnNO₃-Na₂CO₃ system was analyzed in the presence of surfactants, considering the pH value and a solution composition contribution. The optimal coprecipitation conditions were Na₂CO₃ precipitating agent excess of ～20%, providing a pH value of ～10, with subsequent thermal decomposition of the mixture at about 700 K. A thermal analysis of the precursor mixtures were carried out. The phase composition, dispersity and morphology of the precipitates were determined before and after a thermal treatment. The size decrease of the precipitated particles, as well as dispersity and distribution uniformity increase of the oxide inclusions in the target composite matrix is due to the presence of surfactants in solutions.