Blast furnace slag containing CaO, SiO₂, Al₂O₃ and MgO as main constituents was investigated as a possible raw material for tile manufacturing. Samples were made from 50 to 80wt% slag and modified by varying amounts of SiO₂, Al₂O₃, Li₂O and TiO₂. The proerties of the tile thus prepared were investigated using differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Samples heating at 860°C and 880°C for 2h, respectively. The major crystalline phase in the tile was gehlenite (2CaO⋅Al₂O₃⋅SiO₂), the bending strength was from 254 to 510kgf/cm², apparent porosity from 25.10 to 2.03% and the Vickers hardness was from 220 to 366kgf/cm².

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Thin films of TiO₂ were prepared from gas mixtures of TiCl₄ and O₂ using rf glow discharge. TiO₂ films were grown on glass, Si, Ti and MgO substrates at temperatures as low as 200°C by applying an rf power of 10W, although no film was deposited without glow discharge even at 470°C except on the Ti substrate. As the rf power was increased, the deposition rate increased and attained the maximum value which was more than five times as large as the initial deposition rate, but decreased in applying excessive rf powers. TiO₂ crystals of anatase phase were grown at temperatures lower than those for growth of rutile phase. The temperature at which the rutile phase formed depended on the substrate material. Rutile films which were grown on MgO (100) at temperatures above 300°C exhibited highly [110]-oriented crystal growth. For these films, the surface morphology and the degree of the orientation of polycrystallites in the [110] direction depended on the rf power.

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Apparently homogeneous transparent gels (polymer hybrid gels) were prepared from TEOS and PVA or PEG. IR spectra and DTA curves for the gels and pore characteristics of porous materials obtained by heating gels were examined. PVA incorporated into a gel seemd to be bound to the surrounding _??_Si-O-Si_??_ network more firmly than PEG. The pore volume by N₂ adsorption on a porous material made from the SiO₂-PEG system was much larger than that from the SiO₂-PVA system. Pore size distribution curve showed that most of pores in the porous material from the gel in the SiO₂-PEG6000 system were about 20Å in diameter, involving a little portion of somewhat larger pores. Difference in thermal behavior between PVA and PEG in polymer hybrid gel was discussed in terms of the difference in the ratio of hydrophilic to hydophobic groups in the original organic polymer.

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The laser-induced thermal shock test and thermal stress analysis by a finite element method were carried out for explaining the generation and propagation behavior of thermal cracks in ceramics such as silicon nitride, alumina and zirconia caused by high-power-laser irradiation. Different features of crack propagation were observed depending on the ceramic species, probably depending on their thermal properties. Maximum tensile stress in every axis direction was observed at certain locations, where the stress intensity factor was also largest. It was found that cracks might generate right under the center of a heat source circle and at the outside of the circle, and might propagate from righ under surface towards the radial direction. The initial point of cracks seems to a grain boundary phases which soften at high temperatures.

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Permeability of various liquids through a porous glass membrane prepared by phase separation of calcium aluminoborosilicate glass was discussed. It was found that liquid permeation behavior could be described with the Hagen-Poiseuille rule by applying the capillary bundle model to the membrane not depending on whether the liquid was hydrophilic or hydrophobic. Interfacial interaction of membrane pore with permeating liquid was not observed, because the pore size of membranes used was in the submicron to micron range. Furthermore, when kerosene was permeated through a membrane wetted with water, no flux could be obtained until applied pressure reached a critical pressure calculated from contact angle, interfacial tension and pore size. Thus, uniformly controlled pore size of porous glass membranes was confirmed by the permeation behavior as well as by mercury penetration porosimetry and by electron microscopic observation.

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Corrosion tests on magnesia refractories in molten CaO-SiO₂-CaF₂-Al₂O₃ slags have been conducted at 1873K in a high frequency induction furnace. By combining the corrosion rate with the microstructures of tested specimens and the theoretical analysis of the slag penetration, a penetration resistance coefficient of refractory, R_p was introduced as an index for evaluating the corrosion behavior of the refractory. Using this index the penetration behavior of the slag into the refractory was evaluated and the penetration rate of slag into the refractory was related to the corrosion rate, which suggests the possibility of developing a refractory resistant to both spalling and corrosion.

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This study was undertaken to examine the possibility to apply semiconductive In₂O₃ fine particles doped with SnO₂ to an electrically conductive component in the semiconductive glass composites, such as IC-thick film resistors. The effects of the chemical composition of the glass matrix on the microstructure and electrical conductivity of the semiconductive glass composites, and on the solubility of In₂O₃ in the glass matrix have been investigated and discussed. It has been found that the electrical conductivity of these composites gets high when the solubility of In₂O₃ in the glass matrix is high and the microstructure is densely sintered and homogeneous. Also, the formation of InBO₃ has been found to occur during firing and inhibit the densification of the composites. Thus, as the amount of InBO₃ formed gets larger, the connectivity of ITO particles in the microstructure which determines the electrical conduction paths in the composites becomes poorer. From these experimental results, a feasibility to apply the semiconductive In₂O₃ fine particles to the conductive component in the semiconductive glass composites is assessed to be to suitably select the chemical composition of the matrix glasses so as to increase the solubility of In₂O₃ in the glass matrix and to minimize the formation of InBO₃.

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SiO₂ glass thin films doped with CdSe microcrystals were prepared by the RF-sputtering technique. The concentration and mean diameter of the microcrystals strongly depended on the relative surface area of CdSe chips on SiO₂ target, and the size distribution was remarkably influenced by the substrate temperature. The size distribution was independent of the mean diameter, and standard deviation was below 10.0Å which is nearly half of that of CdS_xSe_1-x microcrystals in a typical commercial filter glass. The quantum size effect in CdSe crystals was found from the blue shift of the optical absorption edge. However, the shift clearly deviated from the simple theoretical predictions based on the confined exciton effect and individually confined electron and hole effect. Thus, introduction of electric correlation of electron-hole and the influence of the matrix on the dielectric constant of the microcrystals into the latter effect were found to be necessary to obtain good agreement with the experimental data. Quantum confined Stark effect would iufluence the electro-optic effect of the film.

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Alumina green sheets with the additions of TiO₂ and Cr₂O₃ were prepared by doctor blade process and sintered at temperatures from 1500 to 1600°C in reducing atmosphere. Densification, electrical properties and microstructure were investigated. TiO₂ addition decreases the resistivity, however, it decreases the density of sintered bodies and results in porous microstructure. Chromium and titanium metals and small amounts of carbon were detected in the porous ceramics. The evolution of gas produced by the reaction of carbon during sintering was considered to cause the deterioration in densification and the decrease in electrical resistivity.

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ICP (inductively coupled plasma) flash evaporation, which was a recently developed process for film growth, was applied to the preparation of BaTiO₃ films. Powders of BaTiO₃ (ave. dia. -0.1μm) were evaporated in thermal Ar+O₂ plasma and deposited onto substrates under 20-60kPa. Uniform and translucent films could be obtained on polished fused silica plates. They were consisted of cubic BaTiO₃ and the lattice parameter ranged between 0.400 and 0.401nm. The compositions of the films shown by Ba/Ti atomic ratio were 0.98-1.02. The effect of deposition. conditions on the deposition manner were investigated. The results suggested that the mechanism of film growth in ICP flash evaporation was characterized by a masstransport limited process under very high supersaturation. Epitaxial growth was also observed for the films deposited on (100) MgO single crystals.

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Compaction and sintering behavior of a high purity alumina powder (>99.99%) treated with aluminate (A), silane (S) and titanate (T) coupling agents were investigated. The surface treatment increased the green density of pressed-bodies, the effectiveness of the coupling agents on the density increase being S (57.2%)>T(56.4%)>A(53.9%)>non-treated (51.4%) at 2wt% addition. Microstructure development after firing for 2h at 1600°C was considerably dependent on the types of metals contained in coupling agents. Alumina treated with 2wt% of aluminate (Al) exhibited uniform and fine grains similar to the non-treated system. Grain growth and densification were enhanced in the alumina treated with 2wt% of titanate (Ti) and columnar grains were formed in the alumina treated with 2wt% of silane (Si). Both bending strength and fracture toughness decreased by the addition of coupling agents. Intragranular fracture was observed in the alumina treated with 2wt% of silane although intergranular fracture was prominent in other systems.

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Effects of alkali and alkaline earth metal ions on sintering and the thermal expansion behaviors of nepheline were investigated. Densification at lower sintering temperatures was promoted y Li₂CO₃ or Na₂CO₃ addition. The thermal expansion of nepheline decreased on substitution of Li⁺ for Na⁺, and increased on substitution of K⁺ for Na⁺. Nepheline solid solutions in the system M_xNa_1-xAlSiO₄ (M=Li and K) had mean axial thermal expansion coefficients ranging from 14×10^-6/°C to 20×^-6/°C from room temperature to 1000°C.

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Sintered composites of silica-containing Na₂WO₄ as a phase transformation agent and sodium borosilicate glass were prepared, and silica polymorphs in silica/glass sintered composites were identified and quantitatively analyzed by means of XRD. The amount of tridymite increased with the addition of Na₂WO₄. It was found that the thermal expansion is controllable by the amount of silica polymorphs, particularly tbat of tridymite, in silica/glass composites. Addition of Na₂WO₄ to the composites increased the dielectric constant, which may be attributed to the increase in the amounts of sodium and tungsten ions which have high polarizabilty.

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The influence of the size of coarse particles on packing and sintering behavior was investigated for mixtures consisting of a fine and a coarse alumina powders of which the average particle sizes were 0.52μm and from 2 to 12μm, respectively. In most mixing ratios, green compacts containing large coarse particles had high densities, large pore sizes and broad pore size distributions. For low volume fractions of fine particles, the densification of mixtures containing smaller coarse particles proceeded faster at any firing temperature. For high volume fractions of fine particles, the densification of mixtures containing small coarse particles proceeded slower at low firing temperatures, but proceeded faster at high firing temperatures. For mixtures containing small coarse particles, these facts are explained by the large inhibiting effect of the coarse particles on the densification of fine particles at low firing temperatures and by the large shrinkage of coarse particles at high firing temperatures.

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Corrosion behavior of 93wt% alumina ceramics was investigated. The weight, the bending strength and the thickness of corroded layer were measured after exposed in sulfuric acid at temperatures of boiling point and 90°C. The weight decreased with time, but the weight loss rate became small. On the contrary, the thickness of corroded layer, which was determined by a porous zone depth formed on the surface of secimens as a result of dissolution of grain boundary phase, increased linearly with time. The bending strength decreased with an increase in the corroded layer depth. However, the morphology of fracture was inconsistent with the assumption that the corroded layer depth corresponds to a flaw dimension causing the failure. As large numbers of pore were observed on the fracture surface of the specimens, it was suggested that a combined flaw of the pore and the corrosion layer governs the strength of corroded alumina.

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The heat treatment conditions were examined to synthesize rod-shaped β-LiAlO₂ long crystals in the LiOH-Al₂O₃-NaOH system with a molar ratio of 43.0:10.8:46.2. The best rcaction condition obtained was heating at a rate of 3-5°C/min up to 600°C and kceping for 3h at the temperature.

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Thermal shock resistant zirconia ceramics reinforced by zirconia fibers have been developed. Two types of fibers, 2.5 and 0.2mm in average fiber length mere studied. Zirconia ceramics were stabilized with 1.5mol% Y₂O₃ or 10mol% CaO, and the density was about 82% of the theoretical density. The thermal shock tests involved quenching to room temperature in water with a temperature drop of 600K, or quenching in air with a temperature difference of 1240K. The bending strength did not change after 50 quenching tests for the Y₂O₃ stabilized zirconia ceramics reinforced with long fibers.

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A fibrous compound with the composition of NaMg₄Si₆O₁₅(OH)₃ was formed from synthetic-micas with swelling character (Na-fluor-tetra-silicic mica, NaMg_2.5Si₄O₁₀F₂, and Na-fluor-taeniolite, NaMg₂LiSi₄O₁₀F₂) by hdrothermal treatment with pure water or agueous NaOH solutions. The temperatures and pressure applied were 300, 450, 600°C, and 100MPa, respectively. The run duration was 7 days. The size and the aspect ratio of the fibrous compound were depended on the experimental conditions. An average size is about 100μm in length and 0.5μm in width. Beeause of the crystal habit, this compound may be a potential substitute of asbestos, and a new plastic filler. The fibrous compound showed almost the same XRD pattern as those of NaMg₄Si₆O₁₅(OH)₃ and Na₂Mg₄Si₆O₁₆(OH)₂ which have been reported independently to have the same triple-chain silicate structure. These two kinds of structure are quite similar to that of sepiolite but have from one to two Na ions instead of H₂O molecules which are found in sepiolite. The two compounds could be the end members of the solid solution system called here as “Na-sepiolite”. The present fibers were identified as an end member of NaMg₄Si₆O₁₅(OH)₃. The conditions to produce the “Na-sepiolite” fiber in a high yield were as follows: to use Na-fluor-tetra-silicic mica and a solution of high NaOH concentration (≥5M/dm³), and to treat at higher temperatures than 450°C. Under these conditions, the Na-fluor-tetra-silicic mica was converted to “Na-sepiolite” almost completely.

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Cordierite ceramics sintered with an addition of aluminum titanate were cut and pierced by pulsed CO₂ laser. Effects of average beam power and thickness of workpiece plates on maximum cutting speed were examined. Piercing behavior such as minimum value of average beam power for piercing and diameters of holes were also examined. It is concluded that cordierite ceramics can be cut and pierced by CO₂ laser without serious failures, which are often observed during laser machining of structural ceramics such as Al₂O₃, SiC and ZrO₂. The machined surfaces are covered with glassy layers.

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The phase, lattice parameter and dielectrie constant-temperature characteristics of BaTiO₃-Pb(Mg_1/3Nb_2/3)O₃ [PMN] solid solutions were investigated using XRD and impedance analysis. The solid solutions were divided into three different compositional regions from the temperature dependence of dielectric constant. In the range from 0 to 10mole% PMN, peaks in dielectric constant-temerature plots became broader and Curie temperature decreased with increasing PMN content. In the range from 15 to 60mol%, the dielectric constant was very low and peaks were extremely broad. In the range from 80 to 100mol%, the dielectric constant was high and its temperature coefficient was small. The ferroelectric phase transition from normal to diffuse phase is also discussed.

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