In situ deposition of metal coatings

Ceramic powder particles were metal coated by in situ deposition from decomposable compounds. The ceramic powder and a decomposable metal compound were mixed by tumbling and then heat treated in argon or in hydrogen to deposit the metal. Cermets with continuous metal matrices were obtained by hot pressing metal-coated powders or by in situ decomposition to form the metal during hot pressing. Tungsten-coated Eu₂O₃ powders were obtained by thermal decomposition of W(CO)₆ or by hydrogen reduction of WO₃. Europia-tantalum cermets were made by decomposition of tantalum hydride during hot pressing. Particles of Eu₂O₃ were coated with rhenium by decomposition of ReCl₃ or ReO_x and with molybdenum from the oxide. Cobalt and platinum coatings were deposited on ZrO₂-Y₂O₃ particles by decomposition of the chlorides. The uniformity of metal deposition depends on the mixing and on the particle size of the decomposable compound. The concurrent chemical reaction appears to enhance distribution of the metal by surface diffusion during the heat treatment that results in deposition. The extent of adherence or chemical bonding can be varied through the rate of deposition.