Preparation of submicrometer nickel powders by the reduction from nonaqueous media

Nickel powders in the submicrometer size range were prepared by a chemical reduction-precipitation method from nonaqueous solutions of nickel salts. H ydrazine was used as the reducing agent and paraffin oil, ethylene glycol, di- and tri-ethanolamine as the reaction media in order to carry out the re actions at higher temperatures, and, for the latter two media, to provide t he appropriate basic environment for the reduction. The characteristics of the resulting endproducts, especially the particle size and size distributi on, as well as the micromorphological characteristics, the yield of the rea ction and the purity of the nickel powders, depend on the reaction conditio ns. The mean particle size of the nickel powders can be lowered also by cha nging the homogenous nucleation into a heterogeneous one by adding traces o f palladium. Nickel powders with mean particle sizes ranging from 0.1 to se veral mu m and with up to 99.8% purity were obtained in this way. (C) 1999 Acta Metallurgica Inc.