Reprocessing of tungsten alloy swarf by oxidation-reduction, pressing and sintering

Tungsten and the tungsten alloy group materials have a wide range of uses extending from everyday ones, e.g. the coil of an incandescent lamp or the contact tip of an electrical switch or an automobile horn, to components of nuclear fusion reactors or ion drive motors in space probes. The reason for this range of uses lies in the many outstanding properties of tungsten, in particular its high melting point, low vapor pressure, high atomic number, good electrical and thermal conductivity. In the Tungsten–Oxygen system (W–O) there are not only the stoichiometric oxides WO3, WO2.9, WO2.7, WO2, but also non-stoichiometric structures that represent the ordered or partially ordered defect structures of the oxygen-rich oxide in which the central W atom is octahedrally surrounded by six oxygen atoms. In WO3 neighbouring octahedra are in contact only at the corners. With increased oxygen deficiency (reduction, conversion to lower oxides) common edges and surfaces are progressively formed. The aim of this work was to produce a homogeneous powder for recycling from heavy metal swarf. [Continues.]