2016 年 63 巻 7 号 p. 524-529
All-ceramic artificial teeth were produced using a high-speed centrifugal compaction process (HCP) combined with a resin shell-mold made by a 3D printer. Slurries of alumina or zirconia fine powders filled the inside and outside of the mold and then rotated at between 7,000 and 11,500 rpm in a centrifuge (HCP buried compaction method). Using this method, crack-free green compacts were produced. The shell-molds were not deformed or broken because the inner and outer pressures generated during the HCP were quasi-balanced. Two methods for mold-releasing, thermal decomposition and mechanical de-molding by hand, were investigated. Thermal decomposition introduced the critical problem of sintering inhibition. To obtain the final products, the compacts were air sintered after being released from the molds. For alumina, green compacts of high packing density (63 %) were sintered homogenously without considerable deformation. For zirconia, the packing density reached approximately 55 % with a density gradient. The zirconia compacts were sintered inhomogeneously, which resulted in a density gradient and deformation. The density gradient and shape deformation of the sintered compacts are discussed.
