Abstract
A novel binderless granulation method, Pressure Swing Granulation (PSG) was applied to the granulation of waxed hardmetal powders in which the conventional spray drying (SD) technique has been facing difficulties to produce good granules. Properties of granules and green compacts from the PSG based process were examined and compared with those from the SD based process. Mechanical properties of sintered bodies were evaluated with a Cemented Carbide Industrial Standard of Japan Cemented Carbide Tool Manufacturers' Association.
Spherical granules of sizes ranging 0.1-1mm in diameter were obtained with a high yield. Angle of repose and relative bulk density of granule beds were much improved compared with those of original powder beds and the bed of spray dried granules. Density of green compacts with pressures of 0.5-1.5tf/cm2 (49.0-147.1MPa) was greater than 50% of theoretical density which should be sufficient for obtaining good quality of sintered products. The sintered samples of compaction at a pressure of ltf/cm2 and sintering at 1673K in vacuum for lh showed sufficient mechanical properties for industrial use.
