Preparation and properties of superfine W-20Cu powders by a novel chemical method

摘要

A novel glycine-nitrate process (GNP) has been developed to fabricate ultrafine W-20 wt.%Cu (W-20Cu) composite powders, with ammonium metatungstate [(NH_4)_6H_2W_(12)O_40xH_2O], cupric nitrate trihydrate [Cu(NO_3)_2·3H_2O] as main raw materials and glycine[C_2H_5NO_2] as a complexant and incendiary agent. Precursor powders were obtained after the self-propagation reaction in a suspension containing above materials. The precursor powders were then hydrogen-reduced to convert into W-20Cu powders. Phase constitution and morphology of the precursors, as well as the resultant W-20Cu powders were characterized. Density and microstructure of the sintered W-20Cu samples were tested to investigate the sinterability of the W-20Cu powders. It is shown that the GNP produces superfine W-20Cu powders with particle size of about 200 nm. The powders show good sinterability. Relative density above 98.1% of the theoretical is achieved for the powder compacts sintered at 1200℃ in hydrogen. The sintered W-20Cu samples have electrical conductivity of 40.1% IACS and a Vickers hardness of 278.