The sintering behavior of nanosized tungsten powder prepared by a plasma process

The sintering behavior of nanosized tungsten powder (25 nm average size) synthesized by a thermal plasma process, in which ammonium paratungstate (APT) was reduced by hydrogen was investigated, compared with submicron W powder (0.5 μm average size) and nanosized W powder (23 nm average size) produced from the latter by high energy milling. The hardness of the compact of the plasma-synthesized powder (315 VHN) sintered at 1400 °C was higher than that of submicron-sized powder (193 VHN) and was similar to that of the milled powder (309 VHN). The plasma-synthesized powder, however, yielded a compact with much lower tendency to form cracks than the milled powder.