A RuO2 nanosheet monolayer (RuO2ns(ML)) was fabricated by a self-assembly method on a flexible polymer film, polyethylene terephthalate (PET). This RuO2ns(ML)/PET was used as the current collector for preparation of a thick RuO2ns/PET film by electrophoretic deposition. The EPD film exhibited stable pseudo-capacitive behavior in acidic electroyltes. This new electrode assembly method can be utilized to fabricate highly anti-corrosive and conducting films on various substrates that current transparent and/or flexible conducting electrodes cannot offer.

View full abstract

Conductive ruthenate nanosheets derived via total exfoliation of layered ruthenate were deposited onto a flat glass substrate via electrostatic self-assembly, yielding a monolayer of the nanosheets with a variety of the nanosheet coverage. Patterned Au was vacuum-deposited on the surface of the nanosheet film as current collectors. Conductivity of a single nanosheet was evaluated on the basis of I-V measurement at interval between the collector and the cantilever used while visualization by tapping-mode AFM.

View full abstract

Silicon Nitride was joined with glass or silicon nitride powder as insert materials under mechanical pressure. Joining was successfully conducted. Joined silicon nitride exhibited high strength near bulk silicon nitride.

View full abstract

SiC ceramics were reaction joined in the temperature range of 1450-1800 degree C by using TiB2-based composites starting from four kinds of joining materials, namely Ti-BN, Ti-B4C, Ti-BN-Al and Ti-B4C-Si. XRD analysis and microstructure examinations were carried out on the SiC joints. It was found that the former two joining materials do not yield good bond for SiC ceramics at temperatures up to 1600 degree C. However, Ti-BN-Al results in the connection of SiC substrates at 1450 degree C by the formation of TiB2-AlN composite. Dense interlayer and crack-free interface are produced from both Ti-BN-Al and Ti-B4C-Si powder mixture at 1800 degree C.Mechanical properties of dense SiC joints were measured and analyzed.

View full abstract

Joint techniques of metal and SiC are important issue of SiC components for energy applications. Tungsten has high strength, high melting point and very closed CTE against SiC, the joint of tungsten and SiC is very attractive. Nano-powder Infiltration and Transition Eutectoid (NITE) method is able to produce dense SiC/SiC composites. The NITE-SIC/SIC composites have high resistant against the pressure, thus, the diffusion bonding method is able to apply the joining of tungsten and SiC. In present research, plates and tubes of joined tungsten and SiC were fabricated and characterized to develop the joining technique of tungsten and SiC.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

SiCf(SUB)/SiC composites are one of the candidate materials for structural material of advanced energy systems, because of their good mechanical and chemical stability at elevated temperature. In this study, unidirectional and 2-demensional reinforced SiCf(SUB)/SiC composites were fabricated using hot-press method. Anisotropic mechanical-thermal properties of SiCf(SUB)/SiC composites were evaluated by tensile test and laser flash method.

View full abstract

SiC fiber-reinforced SiC (SiC/SiC) composites are attractive materials for the applications of nuclear power and aerospace planes. In order to produce the components of SiC/SiC composites by Nano-infiltration and transient eutectic-phase (NITE) process technique, the near-net shape fabrication technique is necessary. Densification procedure of the preforms is essential to establish the near-net shape forming technique. In this research, the correlation of densification of performs and the condition of hot-pressing for the fabricated SiC/SIC composites was studied

View full abstract

Continuous SiC fiber-reinforced SiC matrix composites (SiC_f/SiC) have been considered to be a key material as structural components for aerospace and energy fields. Our novel fabrication process of continuous SiC_f/SiC composites with high performance based on interfacial and microstructure control and our approach to improvement of mechanical and thermal properties of SiCf/SiC composite based on modeling and analysis were reviewed. The simple fabrication process of two-dimensional SiC_f/SiC composite using sheet stacking, hot-pressing and electrochemical process was developed. Interfacial properties of the composite were quantitatively evaluated, and these results lead to the material design of the composite with high mechanical properties and the optimization of its fabrication process. Simple model of thermal conductivity of the composite was suggested by our experimental data, and higher thermal conductivity of the composite was successfully achieved.

View full abstract

The conditions for the fabrication of silicon carbide (SiC) composite with chopped SA fibers having carbon interface (SA/C) addition were investigated by hot-pressing technique, using the sintering aids (5 mass% Al₄C₃ and 1 mass% B₄C). An acid treatment (75 cm³ H₂SO₄, 25 cm³ HNO₃; 1.0 g SA/C) was carried out in order to enhance the dispersibility of SA/C in the SiC matrix, owing to the bond formation of COO^- groups with the surface of SA/C. The fracture toughness of the SiC composite with no acid-treated SA/C addition was 5.6 MPa∙m^1/2, whereas that of the SiC composite with acid-treated SA/C fiber increased to 7.0 MPa∙m^1/2.

View full abstract

To obtain high performance ZrB2 base ultrahigh temperature ceramics, hybridization of continuous SiC fiber and ZrB2 matrix, and monolithic ZrB2 has been proposed. Design procedure to obtain higher cracking stress and larger strain to failure are discussed. Theoretical considerations were evaluated through experimental studies.

View full abstract

[in Japanese]

View full abstract

We studied formation mechanism of tobermorite under hydrothermal condition by using synchrotron X-ray diffraction. The diffraction analysis was carried out in-situ using new-designed autoclave cell from 100deg to 190deg. Pre-curing cakes prepared from silica stone, quicklime, HPC, gypsum and water, were used as starting materials. Kinetics of tobermorite crystallization was studied by Avrami-equation. Sulfate ions had a important effect on crystallization of tobermorite in ALC.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Preparation of hybrid film from colloidal nanosheet solution was carried out by anodic electrodeposition. In the case of metal phosphate, nanosheet electrochemical treatment provided ordered nanosheet film with several tens m in thickness. On addition of aniline, polyaniline emerged on anode by radical polymerization and ordered hybrid film was formed with intercalation of polyaniline as monolayer. By using chemically grafted nanosheet with organic silane, interlayer spacing expanded by several sub-nanometers.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Taking account the charge balance, β-tricalcium phosphate (β-TCP) powders co-doped with Mg²⁺ ions and SiO₄^4- ions were synthesized via solid-state reaction, and then the substitution mode of each metal ions and their characteristics were investigated. Mg²⁺ ions were substituted for Ca(5) and Ca(4) sites up to 13.64 mol%, and the excess Mg²⁺ ions replace additionally for vacancy in order to substitute SiO₄^4- ions with changing the occupancy factor and keeping the charge balance. The substitution of Mg²⁺ ions and SiO₄^4- ions into β-TCP structure induced the improvement of the mechanical properties and the inhibition of the bioresorbability.

View full abstract

[in Japanese]

View full abstract

Si-containing hydroxyapatite (SiHAp) particles with 1.67 and 1.95 in Ca/(P+Si) were synthesized by the wet chemical method; 0.08M Si(OC₂H₅)₄ and slurry of 0.5M Ca(OH)₂ (pH 10.5) were mixed together, and the mixture was aged for 0 and 24 h. Then, 0.217 or 0.177M H₃PO₄ solution was dropwisely added to the mixture at a rate of 3ml/min at 80°C. The local structure around Si, P and H in SiHAp was analyzed by solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. After the ²⁹Si NMR analysis, Qⁿ (n=0, 2, 3, 4) structure units were present in the samples derived from the Ca(OH)₂ slurry with 0 h aging, and the aging increased the fraction of Q⁰ content in SiHAp, or it promoted the Si(IV) incorporation into the HAp lattice. In contrast, it suppressed the fractions of the condensed silicate units (Qⁿ (n=2, 3, 4)).

View full abstract

The influence of flushing water on the precipitate formation from urine in drainpipes was investigated. In the case of using flush water, hydroxylapatite and amorphous calcium phosphates were precipitated as rigid scale on the surface of drainpipe. In contrast, in the case of waterless condition, struvite was precipitated in gel-like matrix composed of amorphous calcium phosphates and organic compounds, resulting from high concentration of urine and high pH. It is suggested that the waterless condition prevents the formation of rigid scale on the surface of the drainpipe.

View full abstract

[in Japanese]

View full abstract

Hybrids of chitosan and 3-glycidoxypropyltrimethoxysilane (GPTMS) were well osteocompatible. Their hydrogel is suitable as an injectable material for bone-defect repair when they are controllable in viscosity and gelation. Thus, the hydrogels of the chitosan-GPTMS hybrids were prepared using disodium hydrogen phosphate (DSP) or glycerophosphate (GP) to study their gelling and degradation behaviors. As the GPTMS content in the hydrogels and pH of the precursor sols increased, the gelation time decreased, while the hydrogels showed similar profiles of weight loss in the phosphate buffer solution. The hydrogels thus have a potential as injectable materials.

View full abstract

Siloxane-containing vaterite (SiV)/poly (L-lactic acid) (PLLA) hybrid (SiPVH) fibermats have extraordinary potential for bone regeneration applications. In this study, SiPVH fibermats with 30 and 60 wt% of SiV particles were prepared with melt-blending and subsequent electrospinning methods. Hydroxyapatite (HA)-coated SiPVH (HA-SiPVH) fibermats were also prepared by soaking in 1.5 SBF. Various techniques (SEM, XRD, GPC, and ICP-AES) were applied to characterise the structure, mechanical properties, and Si releasing ability. SiPVH30 exhibited significantly enhanced properties, such as sustained Si release and higher strength in comparison with SiPVH60.

View full abstract

The porous calcium-deficient hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂: HAp) - alginate (AG) composite (mass ratio of HAp/AG ratio: 10.0) has been fabricated in this research. The starting calcium-deficient whisker-like HAp particles were prepared by the homogeneous precipitation method, i.e., the heating of the solutions (500 cm³) containing 0.167 - 0.900 mol dm^-3 Ca(NO₃)₂, 0.100 mol dm^-3 (NH₄)₂HPO₄, 0.200 - 0.500 mol dm^-3 urea and HNO₃ at 80°C for 24 h and then 95°C for 72 h. The mixture of calcium-deficient HAp and 2.5 - 7.5 mass% AG alginate (HAp/AG ratio =10) were frozen at -5 - -196°C. The frozen materials were lyophilized at -50°C for 24 h and put into 1 mol dm^-3 CaCl₂ solution for 24 h. Finally, these samples were lyophilized under the same conditions described above. The resulting composite materials contained large pores with size of 50 to 200 μm when the frozen was conducted at -5°C.

View full abstract

[in Japanese]

View full abstract

-

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

A natural superlattice was built by intercalating a SnS layer into the van der Waals gap of layered TiS₂, as has been observed by HRTEM. In the in-plane direction, the thermoelectric performance was found to be much improved, because the electron mobility was maintained while the phonon transport was suppressed, which was identified due to softening of transverse sound velocity because of weak interlayer bonding. It is also found that in the cross-plane direction, the thermal conductivity is even lower than the predicted minimum thermal conductivity and the random transverse displacement of the SnS layers in the direction parallel to the layers possibly accounts for it.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Silicon nanosheet, which has the two-dimensional silicon backbone structure, is one of the most interest materials because of their nanoscale thickness and macroscale area. Here we report the soft synthesis of two-dimension silicon nanosheet terminated with phenyl groups. From the photoluminescence measurement, the band gap of the silicon nanosheet is determined about 3.0 eV, which is agreement with the theoretical direct band gap for Si6H6. It means that the silicon nanosheet indicate the nature of a monolayer sheet, reflecting completely fabrication of silicon monolayer sheet in organic solvents.

View full abstract

[in Japanese]

View full abstract

Water resistivity of lead glasses contained in CRT was examined in acidic and basic conditions. The leaching model in these conditions was estimated from leached amount of each element and surface change. Because of the reduction of the use of CRT, the waste CRT glass may be disposed as landfill. In such a situation, the long-term stability of the glass should be clarified. Funnel glass showed diffusion controlled leaching in acid. Neck glass showed formation and dissolution of altered layer in acid. Both glasses showed formation of protective layer in basic condition.

View full abstract