Abstract
The consolidation of injection molded compacts by Pulsed Discharge Sintering Process, that enables rapid sintering under the condition of high temperature combined with pressure application in various environments, is proposed as a novel process of near net forming. The proposed PHIP (Pseudo Hot Isostatic Pressing) technique using a pressure-transmitting medium of spherical graphite powder makes it possible to manufacture compacts with three dimensional shapes (PHIP-PDS). For the first time, temperature distribution along radial direction of graphite die was measured in the real time under PHIP-PDS. There existed temperature gradient in the die, that depended on holding temperature, inside diameter and thickness of die. Titanium powders, mixed with 36.2 vol% organic binder, were injection molded. After debound in 100 Torr Ar atmosphere at various temperature, they were consolidated by PHIP-PDS process. The temperature necessary to fully densify them under 50 MPa pressure was 1373K for PHIP-PDS, which was about 300K higher than that for PDS. Contraction percentage of the compacts was 25% for longitudinal (loading) direction, while 6% for transverse direction. Chemical analysis of titanium compacts showed 0.12-0.17wt% carbon and 0.22-0.28wt% oxygen.
