Sintering Behavior and Hardness of Tungsten Prepared by Hard Metal Sludge Recycling Process without Ammonium Paratungstate

In this paper, we suggest a novel recycling process for hard metal sludge that does not use ammonium paratungstate. Ammonia, which in the conventional is essential removing sodium and crystallized tungstate, was used process. Instead of ammonia, acid to remove tungstate resulting formation tungstic (H2WO4). Tungsten powders were successfully synthesized by hydrogen reduction through H2O decomposition, WO3 WO2 reduction, tungsten formation. The prepared from spherical shape had higher sintering density than facet-shaped oxide. enhanced their sinterability resulted an increase size grains. This result high diffusion rate atoms along particle surfaces. Despite having density, hardness sintered lower High energy milling effectively reduced grain improved hardness. milled value (max. 471 HV) best previously reported (389 HV). sum, can be hardened, thereby improving its reducing size, with using proposed