Effects of pressure parameters on alumina made by powder injection moulding

The effects of injection molding pressure and holding time on the properties of injection moulded (IM) parts, and the pressure–volume–temperature (PVT) relationship of the plastic ingredient and alumina feedstocks were investigated. The properties of IM parts include the mass, dimension, surface flatness, green density, sintered density and four-point bending fracture strength of the test bars. The results reveal that the pressure-time traces where the gate pressure is increased from 22 to 117 MPa and the holding time up to 75 s, illustrate the trend of the property change under these pressures. High holding pressures (⩾70 MPa) and longer holding time (more than 5 s) would be favored to increase molded mass, dimension and to decrease the surface sinking of green pieces. The data also show that the pressures and holding time exert no significant influence on the bulk density of green parts, the sintered density nor the bending strength of sintered alumina.