Synthesis and characterization of W–Cu nanopowders by a wet-chemical method

Abstract A wet-chemical process was employed to prepare W–Cu nanopowders. Precursors containing some tungstates were obtained by adding precipitants into a complex solution containing ammonium metatungstate and copper nitrate, afterwards spray-drying the complex solutions. The precursor powders were then calcined and hydrogen-reduced to convert into W–Cu powders. Phase constitution and morphology of the precursors, the calcined powders, as well as the reduced powders were characterized. Relations between the ratio of W to Cu in the complex solutions and the phase constitution of the calcined precursors were investigated. The effects of the reduction temperature and H 2 flow rate on the hydrogen reduction kinetics and the crystallite size of the W–Cu powder were also studied. It was shown that the wet-chemical process produces W–Cu powders with nanosized particles of about 100 nm. The composition of the calcined precursors varies with the ratio of W to Cu in the complex solution, and only CuWO 4 was found in the calcined precursors when the ratio of W to Cu is 74:26(wt.%). The reduction temperature and H 2 flow rate have a great influence on the hydrogen-reduction process and the crystallite size of the resulting W–Cu powders.