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

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... 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. ABSTRACT Diesel nozzle tips with tapered spray holes (inwardly larger) were produced using newly developed powder metallurgy (P/M) processing. Spray holes were formed by resin cores made by a three-dimensional printer. A 2.6 μm steel powder (SCM415) was prepared as a slurry, and was compacted using a high-speed centrifugal compaction process into the resin mold with the core. The mold, core, and binder in the green compacts were eliminated by thermal decomposition, and the compacts were sintered by successive heating. Nozzle tips with three tapered holes were made in the sintered products without cracking or breakage. Although some problems exist in the remaining pores, large outlet holes (about 200 μm) and a carbon residue, the holes can be used for spray examination. KEY WORDS powder compaction with core, net shape formation, thermal decomposition of nozzle ABSTRACT This work explored porous metal impregnation via a high temperature centrifugation process. Impregnation was accomplished by combining a low Tm (411 K) Sn-Bi alloy and P/M-processed stainless steel or alumina matrices (normally exhibiting poor wettability by the alloy) in a capsule, followed by heating to 673 K. This capsule was subsequently set in a heat-insulating vessel and rotated in a centrifuge up to 10,000 rpm. By this process, the molten alloy was forcibly impregnated into the pores of the matrices. The minimum pore size at which the alloy penetrated the matrix was found to increase as the centrifugal force was increased. At the maximum centrifugal force, the alloy could be impregnated into pores only several microns in size. The impetus for impregnation was found to be the pressure applied to the molten alloy by the centrifugal force. The pore size that could be impregnated at a given centrifugal force (which correlated with the pressure generated) could be readily predicted using the Washburn equation. ABSTRACT We aimed to develop a new powder metallurgy process to produce next generation common rail diesel nozzles with tiny and complexly shaped holes. High-speed centrifugal compaction and powder metallurgy were used. Three nozzle samples with holes of straight and tapered (8°, 16°, enlarged inwardly) were made. Three samples without external and inner defects were examined by spray test, which was performed with an ambient pressure of 1 and 4 MPa, an injection pressure of 150 MPa, and was studied by filming using a high-speed camera at 8000 fps. The measuring parameters were the penetration, spray angle, and spray cone angle from the spray aperture. As the taper angle increased, the penetration and spray cone angle increased.