Centrifugal Compaction of Various Shapes

In the centrifugal compaction process of ceramics, shapes of the compacts may be limited because the centrifugal force acts only in one direction of each compact. The uniformity and soundness of the compacts are investigated by comparing their different parts packed with particles moving at a right angle or in the reverse direction to that of the centrifugal force. An Al₂O₃ powder with the average particle size of 0.22 μm and the purity of 99.99% is dispersed in a ball mill to prepare slips with the water content of 25% and coefficients of viscosity in the range of 400∼600 mPa.s. The compacts are examined for moisture, green density, ignition loss and 1250°C-1.5hr sintered density, and proved to be uniform without taking any measure when they are packed by the right-angle movement. They also become uniform by the reverse-direction movement when the top end of the die cavity is provided with vents for air and supernatant. The centrifugal compaction process can be used to obtain sound and uniform compacts with various shapes by sintering at 1250°C for 1.5hr.