It has been reported that the size and distribution of β-Si₃N₄ particles existing in silicon nitride raw powder are crucial factors governing the microstructure of silicon nitride ceramics. Considering such the grain growth behavior, a processing strategy for controlling the microstructure of silicon nitride ceramics has been developed. The key point of this process is to control the size, distribution and orientation of large elongated β-Si₃N₄ grains via seeding of morphologically regulated β-Si₃N₄ single crystal particles. Silicon nitrides with textured microstructure where elongated β-Si₃N₄ grains were unidirectionally or two-dimensionally orientated could be fabricated by combining the seeding with forming methods of extrusion or tape casting. The textured silicon nitride exhibited superior mechanical properties such as high strength, high fracture toughness, high creep resistance, and had a high Weibull modulus of about 50. Moreover it has been revealed that the material exhibits unique tribological and thermal properties.

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The Nodal Wear Model (NWM) constitutes a working tool that may be employed to study the processes of differential corrosion in the Pierce-Smith converter (PSC) with the aim of achieving significant improvements in duration and productivity of the diverse lining alternatives that may be used. Both knowledge of the wear mechanisms as well as the definition of the corrosion equations are necessary to apply the NWM to the PSC. By means of the NWM, the outputs of corrosion in the tuyere zone of the PSC may be interpreted. The present paper analyzes the wear mechanism for thermal spalling. An equation is proposed which, as well as justifying the damage occasioned in the refractory bricks, it can also be used in the development of new designs.

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In this study, the change in the desulfurization characteristics of limestone induced by adding some alkali metal compounds and chlorides to limestone was investigated by thermobalance experiments. In addition, molecular dynamics (MD) simulations were performed to elucidate the effect of alkali-metal chloride additions on the CaO calcination for the desulfurization process. The experimental results obtained show that the addition of NaCl into the limestone is the most effective in improving the desulfurization efficiency. The X-ray diffraction analyses of the calcined seashell, limestone and NaCl-doped limestone found that the calcined seashell, as well as the calcined NaCl-doped limestone, have a similar structure as the CaO crystal. These two materials also show a high desulfurization efficiency. The MD simulations show that NaCl doping into the CaO contributes to the crystallization of CaO, while KCl and LiCl dopings have a small contribution. Therefore, the NaCl doping has a predominant effect on the CaO crystallization leading to a high desulfurization efficiency.

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The sinterability of three kinds of commercially available nano-sized SiC powders and a treated nano-sized SiC powder was investigated using Al₂O₃-Y₂O₃-CaO as a sintering additive. The commercially available, as-received nano-sized SiC powders were difficult to sinter to a relative density of >95% by conventional hot pressing. The effects of the free carbon and SiO₂ impurities in the starting powders on the sinterability of the nano-sized SiC powders were identical to those on the submicron SiC powders. However, both the extremely high free carbon content and low green density of the commercially available nano-sized SiC powders were responsible for their poor sinterability. The reduction of the free carbon content by oxidation and the control of the SiO₂ content by acid treatment were beneficial for enhancing the sinterability of the nano-sized SiC powder during liquid-phase sintering.

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The micro-thermoelectric hydrogen sensor (micro-THS) detects the hydrogen gas working with the thermoelectric effect of SiGe thin film and the Pt-catalyzed exothermic reaction of hydrogen oxidation. Integration of Pt/alumina ceramic catalyst on the membrane of the micro-THS was evitable to ensure the high sensitivity and long-term stability of the sensor. The various compositions of Pt/alumina ceramic catalysts were milled by a ball-mill technique to improve the dispersion of the catalyst, and were mixed with conventional organic vehicle like paste. The paste was deposited on micro-THS using dispenser method and the effects of the ball-mill technique and catalyst composition on the sensitivity, ΔV_s, of the micro-THS for the hydrogen/air mixture gas flow were investigated. The shape of ceramic catalyst became uniform, and agglomeration of catalyst powder could not be observed using ball-mill technique. The 10 mass% Pt/alumina ceramic catalyst was the optimized platinum content of the ball-milled powder paste, and the micro-THS with this catalyst produced the larger voltage signal of 12.2 mV at the operating temperature of 100°C.

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The bone-bonding ability, known as bioactivity, of ceramic biomaterials is usually evaluated by the potential for hydroxyapatite (HAp) formation on their surfaces after exposure to a simulated body fluid (SBF) proposed by Kokubo et al. We previously reported that an organic-inorganic hybrid synthesized from 2-hydroxyethylmethacrylate and 3-methacryloxypropyltrimethoxysilane showed formation of HAp on its surface in SBF, when calcium ions were incorporated into the hybrid. In the present study, the hybrid was combined with α-tricalcium phosphate porous body or calcium phosphates powder (CPP) consisting of dicalcium phosphate anhydrous and tetracalcium phosphate as the Ca²⁺ sources, to improve the mechanical strength of the hybrid. These composites formed HAp on their surfaces in SBF. The mechanical strength of the hybrid was improved by the reinforcement with calcium phosphates. When CPP was used, the compressive strength of the composite increased after soaking in SBF for one day. The combination of the hybrid and calcium phosphates offers a novel design for bioactive materials.

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Ternary alkali borosilicate glasses containing sulfur were prepared by conventional melt quenching method, and their chemical bonding states were investigated based on X-ray Photoelectron Spectroscopy (XPS) and ²⁹Si, ¹¹B Magic Angle Spinning (MAS)-Nuclear Magnetic Resonance (NMR) measurement. The glass samples changed in color from blue to reddish brown due to the remaining sulfur and their glass compositions. These phenomena is closely related with the glass structure. From S2p photoelectron spectra, it can be seen that the sulfur exists with a negative charge in the glass. The formation of non-bridging oxygen components was observed from O1s photoelectron spectra of the glasses, which colored to brown and reddish brown. Furthermore, the signal of silicon atoms coordinated to the sulfur was detected in these glasses by the ²⁹Si MAS-NMR measurement. From these results, it was considered that sulfur atoms bonded silicon atoms at the formation range of non-bridging oxygen component, and the bond of silicon to sulfur in the glasses caused the change in the sample coloration.

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We established a simple electrothermal vaporization (ETV)/inductively coupled plasma mass spectrometry (ICP-MS) technique without separating analyte elements from a matrix to determine trace metallic impurities of eight elements (Na, Mg, Al, Cr, Mn, Fe, Ni, and Cu) in a Y-1 (strontium (Sr)-bismuth (Bi)-tantalum (Ta)-oxygen (O)) thin film for semiconductor ferroelectric random-access memories. To improve the linearity of each calibration curve (20 pg ml^-1-10 ng ml^-1), we added the same concentration of Sr, Bi and Ta to a mixed standard solution as those in the sample solution as a mixed modifier. The recovery percentages obtained by adding 1 ng ml^-1 of each element to the sample solution were between Al (90%)-Cr (105%). The detection limit (3σ) was 1.9×10¹⁰ (Mn)-1.3×10¹² (Al) atoms cm^-2 for a Y-1 thin film with a diameter of 150 mm. The proposed method was applied to the real samples to determine the eight metallic elements (10¹¹-10¹³ atoms cm^-2).

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The irreversible transformation of a tellurum oxide glass layer inserted between two ends of two silica glass optical fibers was monitored via the intensity of a light passed through the circuit. This structure is used for a heat-induced optical fuse after the soft glass layer has been coated with a light absorber. Heat-induced breakage occurred when the glass crystallized or flowed in the presence of a shearing stress. Without the stress, the optical link was maintained through the glass melt but suddenly broke due to the crystallization. Contrary to this, the stress deformed the glass bridge and broke the optical link less than 0.4 s. Thus, the shearing stress at the splicing point helps the device respond immediately and reliably.

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The alumina/polyimide multi-layers were fabricated by dry process using sputtering and vapor deposition polymerization. The alumina layer and polyamic acid layer as a polyimide precursor were coated on a Si substrate at room temperature. The layered structure was prepared under the continuous and discontinuous depositions; the former was to evaporate continuously under vacuum, while the latter was to expose in air after each layering process and to form the next layer under vacuum. After alternating depositions of up to 7 layers, the layered composites were heated to 573 K for 1 h to induce thermal imidization. Under the discontinuous deposition, cracks and delaminations occurred in the laminate. As for continuous deposition, the alumina/polyimide composite remained a multi-layered structure without cracks and delaminations.

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According to XED analysis, the chrysotile changed to an amorphous phase after heating at 600°C for 3 h. With heating at temperatures exceeding 700°C, chrysotile changed to forsterite. After heating at 1000°C for 3 h, observation by phase-contrast microscopy revealed that only a very small number of chrysotile particles remained in the sample. In contrast, treating of the JIS A 1481: 2006 sample under the same conditions (1000°C, 3 h) resulted in the complete disappearance of chrysotile particles.

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Naβ-alumina is a two-dimensional ionic conductor in which insulating spinel layers separate conducting planes of Na⁺ ions. Naβ-alumina ceramics is expected to be used as solid electrolytes because it is strong ionic conductor and mechanically reliable. Therefore, we prepared c-plane-oriented Naβ-alumina ceramics from three aluminum sources using a hot-pressing method and evaluated their ionic conductivity and mechanical strength. In all samples, the ionic conductivity perpendicular to the pressing direction was ten times greater than in the parallel direction. The mechanical strength parallel to the pressing direction was 1.5 times larger than that in the perpendicular direction. The samples made from a mixture of 50 mol% platelike gibbsite and 50 mol% spherical alumina showed the maximum preferential orientation with favorable relative density.

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Highly c-axis-oriented aluminum nitride (AlN) thin films were prepared on silicon single crystal substrates by rf magnetron sputtering technique. The piezoelectric responses of the AlN films were evaluated under frequencies of 0.1 Hz to 1.5 MHz at room temperature. The response showed a good flat gain and a small phase delay under frequencies of 1 Hz to 1.5 MHz. Furthermore the AlN output signal was ascertained under a pressure of 0.2 MPa and a frequency of 1 Hz at 700°C. The piezoelectric response of the AlN films hardly changed in the temperature range from 25 to 700°C. It is confirmed that the AlN thin films have a good possibility for a wide-band pressure sensor under high temperatures.

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This paper describes the fabricating of ceramic micro-scale patterns over a wide area using colloidal suspensions of ceramic powders in the improved Micromolding in Capillaries (MIMIC) method. As the patterning mechanism is based on capillary actions of suspensions, the MIMIC process has a difficulty in that the patterning lengths are determined by the characteristics of the suspensions. For fabricating a striped pattern of long lines with various suspensions, we added a new process of second capillary action of liquids with a high infiltration characteristic after existing MIMIC process, so that the suspensions were moved farther inside with the strong capillary force arising from the liquids which afterward infiltrate. In addition, by repeating the series of capillary actions of suspensions and infiltrating liquids, we could double the patterned lengths of the tin oxide. This study demonstrates the possibility of wide-area patterning of a suspension that is not likely to voluntarily infiltrate with improved MIMIC process.

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In order to purify waste water containing fluoride, the calcium additive method has usually been used to recover fluoride ions in the form of refractory calcium fluoride. In this case, the removable fluoride concentration is limited to be 10-15 mg/l due to the solubility of calcium fluoride. In this study, we report 3CaO•Al₂O₃•3CaSO₄•32H₂O (ettringite) as a highly absorbent substance for the fluoride. The fluoride concentration of the water treated with the ettringite was achieved to be less than 8 mg/l without sludge.

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