| 摘要 |
PURPOSE: To improve hardness, wear resistance, deflective strength and productivity and to obtain a sintered compact substantially comprising only fine tungsten carbide by specifying the average particle size and theoretical density ratio and using a discharge activating press sintering method. CONSTITUTION: A slurry comprising a WC source powder and a solvent such as acetone is sufficiently kneaded and homogenized in a ball mill or 'Attoritor(R)' mixer and to obtain a dry powder 1. The obtd. powder is supplied in a die 2 in an atmospheric environment and pressed by electrodes 3 facing each other under specified pressure, while low-voltage rectangular waves at low frequency is intermittently applied to discharge in the powder to vaporize impurities and to activate the surface. Further specified pressure is added while DC voltage is increased step by step and the current is increased in steps to perform the discharge activating press sintering at about 1550 deg.C final temp. for 7.5min sintering time. By this method, the obtd. tungsten carbide sintered compact consists of tungsten carbide and inevitable impurities and has 0.3-2.0μm average particle size and >=99.9% theoretical density ratio. |
