Using the cyclic-cold isostatic pressing procedure, silicon carbide powder was formed. The green density increased as the number of cycles increased. The effect of the number of cycles on green density was remarkable as the maximum pressure increased up to 300MPa. After C-CIP, the bending strength of pressureless sintered silicon carbide was measured. The average value of bending strength and the shape parameter, which is the index of reliability, increased as the number of cycles increased.

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Yttria- and ceria-doped tetragonal zirconia ((Y, Ce)-TZP) /Al₂O₃ composites were fabricated by HIPping at 1400° to 1600°C and 147MPa for 0.5h in Ar, and their bending strength, microstructure and stability under hydrothermal conditions at 180°C and 1MPa were studied. The bending strength of (4Y, 4Ce)-TZP/25wt% Al₂O₃ composites HIPped at 1400°C was 1600MPa. The thermal stability of (Y, Ce)-TZP/Al₂O₃ composites increased with decreasing HIP temperature, since it depends on the HIP temperature. (4Y, 4Ce)-TZP/25wt% Al₂O₃ composites HIPped at 1400°C showed improved stability under hydrothermal conditions at 180°C and 1MPa. The composites treated at 1600°C showed marked grain growth as compared with 3Y-TZP/Al₂O₃ composites, and their bending strength was greatly reduced to less than that of normal sintered bodies. HIPping below 1500°C in Ar was useful to densify the composites and to improve the fracture strength.

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Hydroxyapatite (HAp) powders with dispersed tetragonal zirconia particles were synthesized hydrothermally at 200°C under 2MPa for 10h. Transmission electron microscopy (TEM) demonstrated that the homogeneous mixture of ultra-fine HAp single crystals and zirconia particles could be obtained by the hydrothermal technique. The mixture with the volume ratio of HAp:zirconia=90:10 was hot-pressed at 1050°C under 30MPa for 1h in Ar, then post-sintered by HIP at the same temperature under 200MPa of Ar for 1h. The product had almost pore free microstructures consisting of HAp matrix and tetragonal zirconia particles. Its fracture toughness was 2.5 times as large as that of the transparent pure HAp ceramics. This ceramic was toughened by the crack deflection toughening mechanism and probably by the transformation toughening mechanism due to tetragonal zirconia particles dispersed in the matrix. Furthermore, the reactivity between HAp and zirconia was examined. The decomposition of HAp to β-tricalcium phosphate (β-TCP) was accelerated by zirconia, and CaO was not detected in every temperature. Thus the decomposition was taken place by dissolution of Ca components in zirconia in the first step, then HAp decomposed to β-TCP subsequently.

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The removal of metallic and/or oxide inclusions in green bodies for PSZ ceramic capillary contaminated in the forming process by nitric acid treatment was investigated. The main inclusions contaminated in the forming process was Fe, and it changed to Fe₂O₃ and/or Fe₃O₄ by oxidation in the calcining process. For infiltration of the acid and handling, the specimen with relative density below 70% having open pores and bending strength above 70MPa was desired. For the ease of removing of inclusions, it was desired that inclusions remained as metallic state. These conditions were achieved by calcining specimens in the temperature range from 600° to 800°C for 1h. PSZ ceramic capillaries for optical-fiber connector with Weibull modulus of 10.24 and bending strength of 925MPa were fabricated by sintering at 1450°C in air for 12h and HIP ping at 1400°C and 1000atm in an Ar atmosphere for 2h after the acid treatment.

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β-tricalcium phosphate (β-TCP) coating on yttria partially stabilized zirconia plate was studied. Firstly, calcium metaphosphate (CaP₂O₆) layer was coated on yttria partially stabilized zirconia as an interlayer by heating at 1000°C for 40min. Then, a mixed slurry of calcium metaphosphate and tetracalcium phosphate (Ca₄(PO₄)₂O) was brought into reaction on the zirconia plate by heating at 1200°C for 40min. The coated layer was found to be β-tricalcium phosphate with thickness of about 100μm.

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Subsolidus phase equilibria in Al₂O₃-Y₂O₃-SiO₂ system and the phase separation and crystallization behavior of glass in this system were studied by X-ray diffraction, differential thermal analysis, scanning electron microscopy and X-ray microanalysis. Phase relations, liquidus and solidus temperatures in this system were obtained. Phase equilibrium was not confirmed in a lower temperature than solidus temperature near 1340°C. The glass transition temperature (T_g) the starting temperature of crystallization (T_c), the 1st and 2nd peak temperatures of crystallization (T_o and T_o' respectively) were studied as a function of composition. The activation energy of crystallization ΔE was determined by analyzing the heating rate dependence of T_o and found to be in a range of 472-890kJ/mol, depending on the composition. ΔE had a tendency to increase with decrease in liquidus temperature, suggesting that the glass becomes stable in compositions with lower liquidus temperatures. During heat treatment of glass at 1300°C, the phase separation was found to occur as an early stage of crystallization.

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Bi-Pb-Sr-Ca-Cu-O superconductive films with various T_c (65-105K) and various J_c (0-155A/cm² at 77K) were obtained by annealing thin films prepared by rfmagnetron sputtering at 823°-850°C for 110h. A high T_c and low J_c film showed a high magnetic sensibility. Especially, the magnetic sensibility of the film annealed at 844°C was 1.87mV/Gauss at 77.3K. However, the magnetic sensibility of the film with higher J_c (155A/cm²) which was obtained by annealing at 850°C, was low. The magnetic sensibility was high for the films with plate-like crystals partially parallel and partially perpendicularly oriented to the MgO substrate (mixed morphology). On the other hand, films composed of almost oriented plate-like crystale showed low magnetic sensibilities. It is considared that the invaded flux in the film with mixed morphology was very motive because of the weak-link grain boundaries.

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ZrSiO₄ fine powders were prepared from zirconium oxychloride (ZrOCl₂) and colloidal silica (SiO₂). Effects of the concentration of ZrOCl₂, calcination temperature, heating rate and size of secondary particles after hydrolysis on the preparation of ZrSiO₄ fine powders have been studied. The ZrSiO₄ precursors having Zr-O-Si bond were found in all the solutions after hydrolysis, and the formation rate of ZrSiO₄ was influenced significantly by the concentration of ZrOCl₂. Also the rate in the case of other concentrations than 0.4M was affected remarkably by heating rate, and there was a marked tendency for crystallization of ZrO₂ and SiO₂ to proceed preferentially and creation of ZrSiO₄ nucleus to be obstructed when the heating rate was slow. It is shown that ZrSiO₄ fine powders of the single phase were prepared at a relatively low temperature such as 1300°C by forming the ZrSiO₄ precursors having Zr-O-Si bond and by controlling the secondary particle size after hydrolysis.

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Evaporation of a liquid droplet of aqueous solutions of slightly soluble electlytes such as CaCO₃, CaSO₄, and KIO₄ and of concrete-soaked-rain water and concrete-soaked-distilled water on untreated and surface-treated glass plate has been investigated through the measurement of bottom length and contact angle of the liquid droplet against time. The deposition of the solute after evaporation has also been investigated. The contact angle decreased at a constant bottom length during the evaporation of a droplet on untreated glass plates. The solute deposited on the edge of the droplet and showed a caldera-like ring after complete evaporation. On the other hand, contact angle decreased to a limited value θ_R at a constant length of bottom of a droplet on the hydrophobic surface of glass plate with low surface energy and afterwards the length of bottom of a droplet decreased at a constant contact angle, θ_R during its evaporation. A crystalline agglomerate smaller than that of the initial liquid droplet was deposited after complete evaporation.

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Synthesis of mullite from fly ash mixed with alumina powder was studied. A suitable fly ash containing small amounts of flux components such as alkali, alkali earth metal and iron oxides and contents of the flux components reduced by pretreatment like magnetic led to separation, a mullite-like material with relatively good quality. When a 1:1 mixture of pretreated fly ash and γ-alumina was heated to above 1673K, 80% mullite yield was achieved. Properties of sintered bodies of mullite powder made from fly ash and γ-alumina were almost comparable to those of a synthetic commercial grade mullite body.

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The effects of aluminum doping on the thermoelectric power of sintered SiC were investigated. SiC added up to 0.6wt% aluminum was fired in the temperature range of 1900°-2050°C. The thermoelectric power was measured at 100°C in vacuum with a temperature difference of 10K across the specimen. The thermoelectric power increased with increasing aluminum addition and the firing temperature. Non-aluminum SiC fired at 1900°C had the lowest thermoelectric power at 2μV/K. On the other hand, SiC added 0.6wt% aluminum and fired at 2050°C had the highest thermoelectric power at 60μV/K.

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Pb_x(Zr_y, Ti_1-y)O₃ films were prepared by CVD using Pb(DPM)₂, Zr(O⋅t-Bu)₄, Ti(O⋅i-Pr)₄, and O₂ as starting materials. Metal alkoxide was selected for both Ti and Zr starting materials, which were effective for controlling Ti and Zr contents in the films. PZT films with the composition, x=ca.1.0 and y=ca. 0.5, were grown reproducibly with almost complete epitaxy on (100) MgO substrates. Deposition rate of film was about 200-300nm/min.

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