Metal sludge generated by polishing stainless steel was consolidated by hot rolling. The sample consolidated at 900°C and 1100°C shows a bcc and fcc structure, respectively, and consists of fine grains with grain size of 5 to 10μm. The density increases with increasing reduction and temperature of rolling, and reaches 7.7Mg/m³ for the sample consolidated at 1100°C and a reduction of 80%. On the other hand, a highest hardness of 435HV is obtained for the sample at 1000°C and a reduction of 80%, and a further increase in rolling temperature causes a slight decrease in hardness due to the phase transformation into fcc. It is found that the consolidated sample have hardness superior to the sample produced by melting the sludge. The tensile strength of 1050MPa and elongation of 7% is obtained for the sample at 1100 and a reduction of 80%. It is said that the metal sludge consolidated by hot-rolling have a fine structure and high strength. The powder metallurgical method is thought to be useful for the reclamation of the metal sludge.

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Fe-Si-Al powder cores were made by shock wave compaction in order to obtain high compacted density, and their electromagnetic properties were investigated. The compacted density with shock wave was higher than that compacted conventionally. The initial permeability and also the permeability under DC bias increased with increase of the green density. Demagnetizing factor of the core was estimated large compared to that of conventionally pressed core, and the reason is supposed that the longitudinal direction of the particle is orientated to the shock wave direction. On the other hand, the resistivity of compaction by shock wave was lower than that of conventional pressing. It is guessed that the surface insulator was broken by the shock wave. The eddy current loss decreased with increase of the resistivity, and over about 0.01Ωm it showed approximately constant. It is suggested that eddy current generates only inside the particle over about 0.01Ωm, however below the critical resistivity it runs inter-particle due to the contact between particles.

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Al₂O₃-TiN micro-composite powder was prepared by reduction and nitridation of mixed Al₂O₃-TiO₂ powder. By adding Ti-isopropoxide as TiO₂ source, TiO₂-coated Al₂O₃ grain was obtained. A suitable condition for the reduction and nitridation was determined at 950-1450°C in a flowing mixed N₂-H₂ gas, with suppressed grain growth and sufficient nitridation. A partial coating was observed in Al₂O₃-TiN composite powder as well as in the Hot-pressed sintered body, which enhances the electric conductivity. Therefore, this method is promising for preparing materials for electric discharge machining.

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The dependence of α-Fe particle size on the formation of Fe₁₆N₂ with giant magnetization was studied by nitriding α-Fe fine particles below 200°C with different particle size (60nm, 120nm, 300nm) derived from α-Fe₂O₃. Nitridation of the largest α-Fe particle (300nm) was difficult to obtain Fe₁₆N₂. Mixtures of Fe₁₆N₂ with unreacted α-Fe and Fe₄N were obtained by nitridation of the smaller α-Fe particles (120nm, 60nm). The nitridation process was most controllable for α-Fe particle of 120nm to obtain the most amount of Fe₁₆N₂. Magnetization was not enhanced by the formation of Fe₁₆N₂ probably due to disordering of the nitrogen introduced into Fe lattice. Monodispersed α-Fe particles could be obtained by thermal decomposition of Fe(CO)₅ in octylether. Their size could be controlled with the amount of added stabilizer in the ether. They could be nitrided to Fe₁₆N₂ in low temperature nitridation.

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Spherical TiO₂ powders were prepared by Chloride process. These powders have Specific Surface Area (SSA) of about 15m²/g and average particle size of about 100nm. The results give the evidence of a strong effect of the quench-cooling by using the quench-cooling device for controlling a wide range of temperature in flame. These microstructures (single crystal, bi-crystal or poly-crystal) and crystal phases (anatase or rutile) were observed by TEM bright field images and electron diffraction patterns. This study suggested that these spherical TiO₂ powders had potential for the solid state reaction to form spherical BaTiO₃ ultra-fine powders for high quality MLCC.

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Hybrid atomization is a new atomization technique that combines gas atomization with centrifugal atomization. This process can produce fine, spherical powders economically with a mean size of about 10μm diameter and a tight size distribution. Experiments on the process were carried out using a Sn-9mass%Zn alloy to investigate the influence of processing parameters on powder characteristics in hybrid atomization. The primary atomization mechanism under normal hybrid atomization conditions is predicted to be direct drop formation mode.

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Monosized silicon particles with narrow particle size distribution have been successfully prepared by pulsed orifice ejection method (POEM). Monosized Silicon particles with desired size could be formed by adjusting process parameters of rod position, supplied pressure and rod displacement. The obtained silicon particles can be divided into two kinds according to their shapes. One is grape-fruit type silicon particles, which is polycrystalline and consists of many grains mainly in random boundaries. The other one is lemon type, which consists of only two or three grains in twin boundaries with cross-sections sometimes found to be single crystal.

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In the present study, to develop controlled-release dosage forms, interfacial reaction method was used to design of the porous inorganic microcapsule of drug. First, the inorganic microspheres with sharp size distribution were produced by using interfacial reaction method. Second, pore volume of porous shell, the route of drug release, was tried to increase. Third, impregnation method or suspension method was used to design of the porous inorganic microcapsules of water soluble drug and the porous inorganic microcapsules of poor solubility drug.
1) The inorganic microspheres with under 5μm size and sharp size distribution could be produced by using interfacial reaction method. The agitation speed preparing W/O emulsion was important in producing microspheres with sharp size distribution.
2) Pore volume of porous microspheres increased with the volume of the pore formations generated by adding NaOH and K(OH)₂. The addition of hydroxide was effective in the porous microspheres.
3) The porous inorganic microspheres could be loaded with water soluble drug and poor solubility drug by using impregnation method or suspension method. The dissolution test results showed the amount of drug release could be controlled with pore of the porous inorganic microcapsule.

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A novel powder extrusion technique was presented for processing metallic short fibers from their powders mixed with a fiber forming agent. The fiber forming agent is expected to prevent bonding between each powder particle during extrusion, while it elongates uniformly with the metal powder and is easy to remove from the extruded bar to recover the metallic fiber. When sodium chloride was mixed to over 93vol% in the aluminum powder, aluminum short fiber with smooth surface appearance was successfully fabricated by extrusion at 723K with an extrusion ratio of 17.6 (partially 100) followed by desalination in water. Decrease in sodium chloride addition into aluminum powder below 90vol% tended to produce rather long but branched aluminum fiber and the recovery rate decreased.

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Powder extension technique was applied to production of aluminum short fiber and effects of particle size of raw powders (aluminum and sodium chloride employed as fiber forming agent) and extrusion parameters (temperature and extrusion ratio) on fiber length, surface appearance and recovery rate were examined. Extrusion temperature which reduced the difference in flow stresses of aluminum and sodium chloride, for example 723K, improved uniformity, surface appearance and recovery rate of aluminum fiber, and the fiber length increased with extrusion temperature. Increasing in extrusion ratio and both particle size of aluminum and sodium chloride also gave rise to longer fiber formation. Long aluminum fiber with a length of 40 to 50mm, which was formed from welding of segregate aluminum powder particles during extrusion, was fabricated using sodium chloride with larger particle size (mean particle size 467μm).

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