著者

森山 実 鎌田 喜一郎 小林 義一

出版者

社団法人 日本セラミックス協会

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.99, no.1148, pp.286-291, 1991-04-01 (Released:2010-08-06)

参考文献数

15

被引用文献数

4 9

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Titanium nitride (TiN) ceramics without additives were fabricated by the hot-pressing (HP), and their mechanical and electrical properties were investigated. Hot-pressing was performed at various sintering parameters such as sintering temperature (1800°-2250°C), sintering time (30-180min), pressing pressure (2-14MPa) and ambient gas (Ar) pressure (vacuum-10atm). Densification was promoted at higher temperature, higher pressing pressure and longer sintering time. The TiN ceramics fabricated by hot-pressing at 2100°C×60min under the pressing pressure of 14MPa in the normal ambient gas pressure showed the representative properties: bulk density; 5050kgm-3 (relative density 92.8%), Vickers microhardness; 8.52GPa, flexural strength; 265MPa, static modulus (Young's modulus); 387GPa, dynamic modulus; 459GPa, and volume resistivity; 0.360μΩ·m. These properties were affected especially by the ambient gas pressure during hot-pressing. The TiN ceramics prepared in vacuum showed 30-40% augmentation, on the average, in hardness, flexural strength, Young's modulus and resistivity, compared with those prepared under normal (1atm) and higher pressures (5, 10atm). TiN ceramics with high mechanical properties were obtained by sintering in vacuum.

著者

銭 端芬 大矢 豊 中川 善兵衛 浜野 健也

出版者

社団法人 日本セラミックス協会

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.103, no.1202, pp.1022-1026, 1995-10-01 (Released:2010-08-06)

参考文献数

20

被引用文献数

3 3

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Aluminum titanate ceramics were fabricated from compacts of aggregated mixture of alumina and titania. The mixture was prepared by precipitation of aluminum hydroxide from aqueous solution of aluminum nitrate, containing rutile powder. After calcination, the mixture was crushed and classified to fractions' 2-5, 5-10, 10-20, 20-47 and 47-77μm sizes. The SEM observation of compacts of the aggregates revealed that the aggregates were not broken by the compaction. The fired bodies of the compacts consisted of oriented aluminum titanate grains. The sizes of the oriented regions were about 4 times larger than the initial aggregate sizes. The reasons for the formation of the oriented grains were considered as follows: the formation of aluminum titanate has low change in free energy, increases elastic energy, and is endothermic. Because of these reasons, grain boundary energy becomes significant in nucleation of aluminum titanate and, therefore, the nucleation occurs epitaxially to result in the oriented texture. The semi-quantitative estimation of change in energies during formation of aluminum titanate agrees with the argument.

著者

伊藤 義康 亀田 常治 西田 勝利 梅澤 正信 今井 義一 市川 宏

出版者

社団法人 日本セラミックス協会

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.106, no.1236, pp.830-834, 1998-08-01 (Released:2010-08-06)

参考文献数

16

被引用文献数

2 2

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Toughness of ceramic-matrix composites can be optimized through coatings the reinforcing fibers. Chemical vapor deposition (CVD) process is a key technology for fiber coatings. The mechanical properties of continuous silicon carbide fibers (Hi-Nicalon) have been studied as a function of the thickness of the pyrolytic boron nitride (P-BN) coating by CVD process. The compressive residual stress at the P-BN coating layer decreases slightly with increasing the coating thickness. It is considered that, with including the residual stress effect, cracking of the P-BN coating layer occurs first in a monotonic tensile fracture test. In addition no degradation of the silicon carbide-fiber in ultimate tensile strength is observed regardless of the P-BN coating thickness.

著者

小菅 勝典 浜田 善久 大塚 良平

出版者

社団法人 日本セラミックス協会

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.99, no.1148, pp.282-285, 1991-04-01 (Released:2010-08-06)

参考文献数

11

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This study was undertaken to obtain kaolinite from serpentinite by treating with AlCl3 solution under various hydrothermal conditions. The serpentinite used as a starting material was from Hidaka district, Kochi Pref. Magnetite included was removed by wet magnetic separation after crushing under 280mesh. Then, 0.4g of the purified serpentinite was sealed in an ample together with AlCl3 solution and heated in an autoclave above 150°C. When this material was treated with 0.5-1.0mol/l AlCl3 solution at 200° and 245°C for 48h boehmite and/or Al24O11(OH)44Cl6 were formed together with kaolinite. Treatment with 0.5mol/l AlCl3 solution yielded only boehmite in addition to kaolinite. To prevent the formation of boehmite, mixed solutions of AlCl3 and HCl were used. When the concentrations of AlCl3 and HCl were 0.5 and 0.3mol/l, respectively, white kaolinite with low crystallinity was obtained at 245°C for 48h or 200°C for 65h. It was found that metallic elements except Si was exracted completely from the starting material into the solutions. About 98% of Si in the starting material was converted to kaolinite. The experimental results indicate that the transformation from serpentine to kaolinite proceeds at low reaction temperature in a short duration. This is presumably because the kaolinization of serpentine proceeds topotaxially as a consequence of virtually indentical crystal structure of serpentine and kaolinite.