[in Japanese]

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Three-dimensionally ordered macroporous (3DOM) nickel-yttria stabilized zirconia (Ni-YSZ) cermet anode was fabricated for lowering the polarization resistance of solid oxide fuel cell. For further improvement of cell performance, the pore surface of 3DOM Ni-YSZ cermet anode was coated with samaria-doped ceria (SDC) by sol-gel method. The performance of La_0.8Sr_0.2MnO₃ (LSM)-YSZ / YSZ / 3DOM Ni-YSZ cell at 600 C was successfully improved from 0.075 W cm^-2 to 0.13 W cm^-2 by the SDC coating.

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[in Japanese]

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SiC/BN nanocomposite powders were produced by heating the starting materials of boric acid, silica and carbon powders in nitrogen atmosphare. At above 800 oC, borosilicate glass was formed by reaction of boric acid with silica, and the SiC/BN composite powder was synthesized by carbothermal reduction and nitridation of borosilicate glass over at 1550 oC. The SiC/BN composites sintered by hot-pressing the nanocomposite powders showed high strength and good machinability.

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[in Japanese]

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SiC fabric layers including Al₂O₃ or Al₂O₃–mullite particles were joined to the oxidized dense SiC compact through the SiC/Al₂O₃ or Al₂O₃/mullite intermediate layers. The thickness of SiO₂ layer formed on the oxidized SiC surfaces is a key factor to control the joining. The laminate of SiC fabric / SiC-Al₂O₃ sheet or SiC fabric / Al₂O₃ –mullite sheet showed high damage tolerance to the surface cracks. The fabric layers prevented the propagation of cracks formed. Joining under a low applied pressure (< 2 MPa) was recommended to maintain the high strength of inside SiC compact. Increased pressure during the joining caused the creep rupture of inside dense SiC compact.

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Recently, there has been an increasing interest in the applications of porous SiC as functional materials for advanced energy systems. However, conventional processing routes for porous SiC are complicated and these materials show poor mechanical and chemical stability. In this study, porous SiC manufactured using the decarburization process has been constructed with open, spherical pores. These materials exhibited a substantially higher strength in comparison with other conventional porous SiC, due to their robust microstructure.

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[in Japanese]

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Porous mullite ceramics with Mg-Al spinel addition were fabricated using spherical PMMA particles as a pore former, and their pore size, porosity and microstructure were investigated. Bulk density and open porosity of mullite ceramics without spinel addition were 1.6-1.7g/cm³ and 46-50%, respectively. Open porosity of mullite ceramics with spinel addition was around 5% using PMMA with the size of 30μm. When PMMA with the size of 60 and 90μm were used, open porosity of mullite ceramics with spinel addition was 21 and 28%, respectively. These values were much lower than that of mullite ceramics without spinel addition. These results could be explained by the difference in their sinterability.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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In Japan, the amount of the emission of coal fly ash reaches to 8 million ton per year. Approximately 80 mass% of the total amount of the emission coal fly ash is reused as a reinforcing material in cement or asphalt. However, 20 mass% of it is embedded in the ground. Therefore, various researches concerning effective use of coal fly ash have been studied. Particularly, synthesis of micro powder of zeolite using coal fly ash is thought to be an attractive reuse method. However, fabrication of bulk body with zeolite using coal fly ash has not been studied yet. In this study, bulk hardening body with zeolite was synthesized using a coal fly ash and its physical properties were analyzed.

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Cordierite Ceramics were fabricated from coal fly ash added basic Magnesium Carbonate and amorphous Aluminium oxide. Their mechanical properties were examined. The stoichiometric mixtures was prepared by the raw materials which was sintered from 1100C to 1250C. The relative density of the sintered sample fired at 1150C reached 98% theoritical. Its flexural strength was 132 MPa, its elastic modulus was 184GPa, its Vickers hardness was 7.1GPa , its fracture toughness evaluated by IF method was 3.0MPam1/2 and its linear thermal coefficient of expansion of 2.6*10-6 K-1 respectively.

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[in Japanese]

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The lightweight ceramics were fabricated by firing incinerated ash of sewage sludge added with 1 wt% carbon in Ar gas. The mixtures were pressed into disks of 20 mm in diameter and the disks were fired at the temperature range from 1050 to 1150 C for 1 h. The lightweight ceramic that has the apparent porosity under 1 gcm^-3 was obtained by firing at 1075 C.

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[in Japanese]

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Zirconia sol / smectite composites were prepared by mixing of swelling montmorillonite and zirconium oxychloride solution under ultrasonic. The obtained composites were characterized by XRD, nitrogen adsorption, and ammonia temperature programmed desorption (TPD). The obtained composites show higher solid acidity than the commercial acid montmorillonite (K10, Aldrich). The acid amount showed the linear relationship with the specific surface area. This shows that the origin of new acid point basically depend on the new surface of silicate layer.

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[in Japanese]

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To evaluate the movement of a droplet on superhydrophobic surfaces (Contact angle: 150 ^o <), the experimental system was assembled. We prepared ZnO coating with nanoscale roughness on the surface of a tube of SiO₂ glass. Then, transparent superhydrophobic coatings were obtained. Water droplets on a superhydrophobic surface have high mobility by applying weak external force (Electric field, Gravitation, and Airstream). Rolling/slipping ratio depended on the droplet volume.

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[in Japanese]

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The hydroxyapatite (HAp) has an excellent biocompatibility; however, the mechanical strengths, especially the toughness value and Young's modulus of this dense ceramics, are different from those of living cortical bones. Thus, much attention has been devoted to fabricate the ceramics/polymer hybrids having mechanical properties similar to those of natural bone. We have developed the porous HAp ceramics with bi-model pore structure by firing apatite fiber compacts mixed with carbon beads. Using the porous HAp ceramics, the bioactive HAp / biodegradable poly-L-lactide (PLLA) hybrids were fabricated by introducing PLLA into the porous HAp ceramics via enzyme polymerization of L-lactide using lipase PS as an enzyme.

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[in Japanese]

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Unidirectionally interconnected porous material composed of hydroxyapatite/collagen nanocomposite (HAp/Col) was fabricated by roll-up of the HAp/Col filter-paper-like wavy membrane of which one side was filled with HAp/Col paste. Accodingly, pore number was decreased to a half to the previous porous HAp. Bone repairing capability of the HAp/Col porous material was evaluated by segmental tibial defect of dog. At 4 weeks after implantation, the same degree of new bone ingrowth to the HAp/Col as the previous porous HAp/Col was observed even the porosity was decreased. Further, defromation of the HAp/Col was smaller than that of the previous one.

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[in Japanese]

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[in Japanese]

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The sized nano MgFe2O4 ferrite powder having heat generation ability in an AC magnetic field was prepared by bead milling and studied for application in thermal coagulation therapy. The heat ability was improved by a decrease in crystal size using bead mill. The maximum ability obtained for the sample having 6.2 nm in crystal size. After the milling, the calcination of the sample was also effective for the improvement of the heat ability.

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[in Japanese]

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We have prepared hollow calcium-phosphate microsphere by salt-assisted ultrasonic spray-pyrolysis technique, and aimed to control the particle morphology by changing i) concentration of added salt (NaCl) in starting solution (Ca/P ratio=1.50) and ii) pyrolysis temperature. In case of pyrolysis temperature of 850 ºC and concentration of NaCl in the range of 0.60-1.50 mol·dm–3, we observed formation of secondary particles consisting of rod-like primary particles. Thus, morphology of microsphere can be controlled by changing concentration of NaCl in starting solution and pyrolysis temperature.

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Novel calcium phosphate bone paste without necessity of mixing just before using, was fabricated by combining calcium phosphate powders with a viscose starch liquid. The paste prepared by blending equi-volume of alpha-wheat starch and a mixture of dicalcium phosphate anhydrous (DCPA) and tetracalcium phosphate (TTCP) powders was tended to precipitate bone-like apatite within 3 days after soaking a simulated body fluid (SBF). This paste may be easy-handling material, show bioactivity and expected to avoid varying in mechanical properties across the whole body.

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Porous calcium-phosphate hardened body was fabricated mixing calcium-phosphate paste (CPP), porous spherical -calcium orthophosphate (-Ca3(PO4)2: -TCP) agglomerates and cyclodextrin (CyD). The porous spherical -TCP agglomerates were prepared by the spray pyrolysis technique, using calcium-phosphate solution with 0.1 mass% colloidal silica. Considering the fact that the setting time of CPP has to be within 15 min for surgery operation, the maximum amount of CyD for the incorporation into starting powder of CPP was found to be 8.33%, whereas that of CyD for the incorporation into malaxation liquid was 0.56%. The remaining CyD in CPP was expected to be utilized for releasing some drugs into the body fluid.

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We have succeed in development of the novel apatite cement using hydroxyapatite (HAp) particles surface-modified with inositol phosphate (IP6). In the present investigation, biological apatite powder (hereafter, bone HAp) instead of pure HAp was used as a starting powder for the chelate-setting cement. The bone HAp powders including various bone minerals, Na+, K+, Ca2+, Mg2+, F-, PO42-, and CO32-, were synthesized via conventional wet process. The compressive strength derived from bone HAp powders surface-modified with IP6 (IP6-Bone HAp) attained maximum ~16 MPa in the case of the powder/liquid ratio = 1/0.40 [w/w]. This value was comparable to the compressive strength of IP6-HAp cement fabricated under the same conditions.

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We have successfully developed novel "chelate-setting apatite cement" using hydroxyapatite particles surface-moidified with inositol phosphate (IP6-HAp). Two kinds of the specimens, "bm-IP6-HAp" and "bm-HAp" cements, were fabricated from ball-milled HAp-100 powders with and without surface modification of IP6, respectively. In order to examine changes of compressive strengths of the IP6-HAp cements during immersing in a simulated body fluid (SBF), we fabricated four kinds of specimens. The compressive strength of IP6-HAp and bm-IP6-HAp cements increased with immersing time. Furthermore, the results of the 7 days immersion into SBF showed that the formation of bone-like apatite occurred on the surface of the specimens.

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[in Japanese]

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Using a homogeneous precipitation method with hexamethylenetetramine as a precipitant, ZnO particles were directly precipitated from solution. Zinc acetate was used as a precursor, and water-ethylene glycol (EG) was used as a solvent. The spherical ZnO particles were obtained from the solutions that contain EG 75-95vol% at 95oC. The spherical particles, which gave a monophasic polycrystalline XRD patterns, consist of many primary ZnO grains.

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ZnO nanoparticles was prepared by a novel solvothermal process which silane coupling agents were added in the synthesis system in order to prevent the rapid growth of ZnO nanoparticles and to improve their dispersion stabilities in solvent and polymers. Redispersible ZnO nanoparticles witch possesses strong blue to green fluorescence with emission maxima around 460 nm (excited at 365nm) was obtained. It was also found that these nanoparticles were redispersible in urethane resin without strong aggregation by TEM analysis.

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We studied synthesis of BaTiO₃ at low temperatures in NaOH solutions containing Ba(OH)₂•8H₂O and titania or titanate particles. Cubic BaTiO₃ crystals were successfully obtained at room temperature (25°C) under a highly basic condition with 2.9 M NaOH in a polypropylene bottle. Fine particles of anatase and titanate were effectively reacted with Ba²⁺ with a large amount of OH^- even at room temperature. The particle size and crystallinity of BaTiO₃ grown in the solutions depended on the Ba/Ti molar ratio and the concentrations of NaOH and Ba²⁺ ion.

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[in Japanese]

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Hollandite-type K_xGa_xTi_8-xO₁₆ (x~1.6) fine particles were prepared by electrostatic spray deposition (ESD) method. Deposited powder showed crystallization above 600C by TG-DTA. Most of heated-treated materials at 600C showed hollandite-type structure, and a small amount of by-procuct included as TiO₂ and K₂Ti₆O₁₃. Crystallite side calculation by Hall's method showed 20~30 nm and corresponded to the scanning electron microscope image.

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