Al2O3 and ZrO2 powders formed by centrifugal compaction using the ultra HCP method

The influence of high speed centrifugal compaction process, the HCP method, on the properties of green compacts and sintered samples of Al2O3 and ZrO2 micropowders was investigated. This method may reduce friction between particles and prevent bridging of particles during compaction. The properties of the sintered materials strongly depend on the conditions of the centrifugal process: i.e. duration, rotation speed, solid content and dispersive liquids. The centrifugal compaction process of powder forming often results in gradient phase composition. An algorithm describing sedimentation of a group of spherical particles of different sizes and of different materials was used. Calculations for Al2O3 and ZrO2 deposition for the real conditions of the high-speed centrifugal compaction process have been carried out using the Barnea–Mizrahi equation. Deposition was carried out using an ultra-centrifuge with rotational speeds of 10,000, 20,000 and 30,000 rpm for various pH of dispersive liquids. Pore size and pore size distribution of Al2O3 and ZrO2 green compacts were measured by the mercury porosimetry method. Densities, Young's moduli and Vickers hardness distribution of sintered compacts prepared in various conditions are reported.