Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌)
Online ISSN : 1882-1022
Print ISSN : 0914-5400
ISSN-L : 0914-5400
110 巻, 1277 号
選択された号の論文の14件中1~14を表示しています
  • 山口 十志明, 坂本 渉, 余語 利信, 平野 眞一
    2002 年 110 巻 1277 号 p. 1-5
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    NO/O2 and NO/C3H6/O2 reactions were investigated over barium hexaaluminogallate (Ba (Al, Ga)12O19 and BaCo (Al, Ga)11O19) with Al/Ga=9/3, 6/6 and 3/9 ratios. BaCo(Al, Ga)11O19 was synthesized by crystallization at 1100°C via the coprecipitation precursor powders prepared by aqueous metal nitrates and ammonium carbonate. The NOx conversion amount in the NO/O2 reaction over all hexaaluminogallates was less than 10%. The addition of C3H6 as a reductant gas significantly improved the NOx conversion over BaCo(Al, Ga)11O19 in excess oxygen compared with that in the case of Ba(Al, Ga)12O19. The Al/Ga ratio influenced the morphologies and catalytic activities of hexaaluminogallate powders. With increasing Al/Ga ratio, the NOx reduction with C3H6 to N2 increased up to 40% and 28% for BaCo(Al, Ga)11O19 powders and Ba(Al, Ga)12O19 powders, respectively. Highly dispersed Co species are effective in accelerating the NO activation step in selective reduction with C3H6.
  • Mohammad-Ali FAGHIHI-SANI, 山口 明良
    2002 年 110 巻 1277 号 p. 6-11
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Among solid solutions (Al2OC)1-x(AlN)x, x=0-1, it has been found that (Al2OC)0.5 (AlN)0.5, x=0.5, is easier to form by a solid state reaction. In this regard, a homogeneous solid solution (Al2OC)0.5(AlN)0.5 was obtained through heating of a compact, including Al2O3, Al, AlN and graphite, at 1700°C for 5h in Ar atmosphere and rapid cooling down to 1400°C. In comparing with AlN, it showed better hydration resistance. The obtained solid solution starts to react with MgO at 1100°C in CO atmosphere to form spinel and carbon. Therefore, the spinel-carbon clinker was prepared through heating of MgO-(Al2OC)0.5(AlN)0.5 compact in CO gas at 1500°C for 5h. The precipitated carbon in the obtained clinker was amorphous and finely distributed among the spinel phase.
  • 小舟 正文, 武藤 和夫, 秋山 善一
    2002 年 110 巻 1277 号 p. 12-17
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    High density ceramics with compositions of 0.24Pb(Zn1/3Nb2/3)O3yPbTiO3⋅(0.76-y) PbZrO3 (PZNTZ 24/100y/76-100y), where y=0.350 to 0.456 were fabricated by normal sintering. The dielectric, piezoelectric and ferroelectric properties of these PZNTZ ceramics were systematically investigated. The morphotropic phase boundary (MPB) composition of PZNTZ 24/100y/76-100y system was at y=0.376. The highest values of electromechanical coupling factor, kp and piezoelectric constant, d31 were 63% and -191pC/N, respectively, and were obtained in the PZNTZ 24/37.6/38.4 ceramics. Regarding the ferroelectric properties, the largest remanent polarization, Pr=38.1μC/cm2 and the smallest coercive field, Ec=11.6kV/cm among the PZNTZ ceramics studied in this work were obtained in the PZNTZ 24/35.3/40.7 ceramics. The experimental results demonstrate the PZNTZ 24/37.6/38.4 ceramics are potential element materials for piezoelectric applications.
  • Jen-Sue CHEN, Wen-Tse LO, Jow-Lay HUANG
    2002 年 110 巻 1277 号 p. 18-21
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Tin oxide (SnO2) films were deposited by r. f. (Radio Frequency) magnetron reactive sputtering and subsequently annealed at 900°C. The effect of deposition parameters and Pt catalyst content on phases and gas sensitivity of the SnO2 films were investigated. It was shown that the amorphous phase disappeared, polycrystalline SnO2 formed after heat treatment, and the crystallinity of SnO2 reduced with decreasing oxygen flow rate. The gas sensitivity of tin oxide films deposited at 50 sccm was consistently higher than that of 25 sccm and invariably increased with the CO concentration. The sensitivity of Pt doped SnO2 films was, however, much superior to that of undoped samples. In addition, the sensitivity consistently decreased with the amount of Pt.
  • 高橋 儀宏, 紅野 安彦, 藤原 巧, Kalidini B. R. VARMA, 小松 高行
    2002 年 110 巻 1277 号 p. 22-26
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Crystallization behaviors of the glass with a composition of 25Li2O⋅25B2O3⋅50GeO2 corresponding to lithium borogermanate LiBGeO4 have been examined. It has been confirmed that the LiBGeO4 crystalline phase is formed at the surface of heat-treated glasses. The second harmonic (SH) generation is found from transparent surface crystallized glasses, demonstrating for the first time that the LiBGeO4 phase shows optical nonlinearity. The SH intensity of LiBGeO4 crystallites (powdered state) prepared through crystallization is about ten times as large as that of pulverized α-quartz. The SH intensity of transparent crystallized glasses (bulk state) with crystalline layers of 3-4.5μm thickness increases with increasing heat treatment temperature (540-560°C) and, time (1-6h), and the maximum SH intensity among the samples studied is in the order of 1/10 in comparison with that of α-quartz single crystal. The transparent crystallized glass obtained by heat treatment at 550°C for 3h exhibits a clear and fine Maker fringe pattern, indicating a highly orientation of LiBGeO4 crystals at the surface.
  • 橋本 忍, 山口 明良
    2002 年 110 巻 1277 号 p. 27-31
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Spherical leucite crystals with 100μm in diameter were obtained when a starting sample consisting of K2SO4:Al2(SO4)3:SiO2(amorphous silica, 10μm)=5.9:1.0:1.1 (molar ratio) was heated at 1000°C for 3h and then treated with hot HCI. The effect of SiO2 polymorphs and their starting particle size on the size of the resulting spherical leucite crystals was investigated. In addition, the effect of preheating and grinding the starting sample on the size of leucite crystals was studied. The size of the spherical leucite crystals decreased with decreasing the size of SiO2 particles. When quartz particles with 3.2 to 52.8μm in diameter were used, the diameter of the spherical leucite crystals was in the range 19.0 to 55.2μm. When tridymite particles with diameter 3.0 to 72.0μm were used, the size of spherical leucite crystals was between 12.4 and 135.8μm. When the starting sample with amorphous SiO2 was preheated to 800°C, cooled to room temperature rapidly, and ground to 4.5μm, the size of spherical leucite crystals reached on average size of 2.6μm.
  • 金山 雅巳, 鎌田 郁子, 塩野 剛司, 西田 俊彦
    2002 年 110 巻 1277 号 p. 32-37
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    For two kinds of Si3N4-based ceramic composites reinforced with SiC whisker with different size, in the present study, the crack opening displacement (COD) was measured in situ in the scanning electro microscope (SEM). The magnitude of the shielding effect was evaluated by comparing it with a theoretical COD profile in an elastic body proposed by Irwin. The composite reinforced with smaller whisker did not exhibit noticeable crack-face interaction. For the composite reinforced with larger whisker, on the other hand, a shielding interaction due to elastic bridging by SiC whisker was recognized, leading to a remarkable rising-curve behavior. Stress intensity factor at crack tip, Ktip and crack propagation resistance due to whisker bridging, Kμ (a) linearly increased with increasing crack opening load. This suggested that the main bridging contribution in a region immediately behind the crack tip (approximately 150μm) is of an elastic nature. After whisker developing closure stress due to elastic bridging, relatively weak frictional bridging between whisker and matrix was also identified during crack propagation.
  • 本多 沢雄, 鈴木 勉, 西川 直宏, 淡路 英夫, 秋宗 淑雄, 広崎 尚登
    2002 年 110 巻 1277 号 p. 38-43
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Thermal shock fracture test using an infrared radiation heating (IRH) method was performed on alumina and two kinds of silicon nitride that have high and normal thermal conductivity. The thermal shock strength, R1c, and thermal shock fracture toughness, R2c, of these materials were estimated experimentally and theoretically, where the experimentally obtained values, which were termed experimental R1c or R2c, were measured by the IRH technique, and the theoretical values were calculated using material properties, which were termed calculated R1c or R2c. The results revealed that the silicon nitride having high thermal conductivity showed three-fold higher R2c value than the silicon nitride with normal thermal conductivity. A technique for estimating the R1c value using the experimental R2c was also developed, because it is difficult to measure the thermal shock strength, R1c, for materials with high thermal shock resistance, using the IRH technique, due to insufficient heat flux.
  • 鈴木 一孝, 粂 正市, 中野 喜久男, 管野 善則
    2002 年 110 巻 1277 号 p. 44-50
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Preforms were prepared by PIP (Polymer Impregnation and Pyrolysis) processing using polycarbosilane to 3-dimensional orthogonal weave fabrics of pitch-based carbon fiber. Porous matrices of the preforms were still more filled with β-SiC by PCVI (Pressure Pulsed Chemical Vapor Infiltration) processing using source gas mixture of SiCl4-CH4-H2 system to obtain dense 3-dimensional carbon fiber reinforced SiC matrix composites (3D-C/SiC). In the PCVI process, influence of the processing conditions on densification of the matrices was investigated in detail. The PCVI filling up to 120000 pulses were carried out under various conditions with varying temperature, residence time and gas flow rate. Then the filling-ratio was evaluated from changes in density and porosity, and crystal-phases of deposits were identified by XRD. The filling-ratio and the phase of deposits varied with the PCVI processing conditions. The PCVI processing under the conditions of 1373K in temperature, 1.5s in residence time, 4mol% each of SiCl4 and CH4 in molar-concentration and 80kPa in total pressure gave the highest filling-ratio. In this case, the number of pulses and operating time necessary for saturation of the filling-ratio were 60000 pulses and 192ks, respectively. The porosity of the densest composite was about 6% from macrosurface to 0.5mm in depth and less than 9% even to 1.5mm in depth. Also, it was found that higher total pressure was effective for increasing filling-speed without increasing the porosity, but disadvantageous in the consumption of the source gases.
  • 上村 裕美, 松井 光彦
    2002 年 110 巻 1277 号 p. 51-54
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Recently NASICON (Na3Zr2Si2PO12) has been used as the solid electrolyte for EMF (electromotive force) CO2 sensors. However, it has been difficult to obtain a sufficiently high quality of this type of sensor. In general, when the EMF CO2 sensor is exposed to a high-humidity atmosphere, the EMF of the sensor decreases to less than two-thirds of its initial value. For the purpose of improving the humidity resistance of the sensor, the reason for the decrease of the EMF sensor after exposure to a high-humidity atmosphere is investigated, and an appropriate counterplan is devised. In this report, Li2CO3, Li2CO3-La2O3, and Li2CO3-La9.33Si6O26 are adopted as materials for the sensing electrodes. Li2CO3 reacts with NASICON and forms friable compounds when these materials are exposed to an atmosphere of 90% relative humidity at 60°C. In contrast, Li2CO3-La9.33Si6O26 is the material most resistant to humidity, because La9.33Si6O26 prevents the reaction between NASICON and Li2CO3.
  • 三田村 久吉, 馬場 恒孝, 前田 敏克
    2002 年 110 巻 1277 号 p. 55-59
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Influence of additives and hot-pressing temperature on properties of the synthetic rock was investigated, which was developed for preparing a harmless and stabilized crystalline solid of fly ash from municipal waste incinerator. Upon sintering at 1200°C for 16h, it was revealed that the addition of 20mass% TiO2 and 1.5mass% Na2O was necessary for the preparation of dense rock products. X-ray diffractometry showed that these additives promoted the formation of perovskite (CaTiO3) and gehlenite (Ca2Al2SiO7) minerals. During hot pressing, bulk density of the synthetic rock increased steeply with temperature between 1000 and 1100°C. On the other hand, its open porosity decreased rapidly with temperature between 1050 and 1150°C. These facts imply that a temperature of 1100-1150°C is suitable for the hot pressing of fly ash.
  • 松本 峰明, 金子 賢治, 安富 義幸, 大原 智, 福井 武久, 小沢 保夫
    2002 年 110 巻 1277 号 p. 60-62
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Spray pyrolysis was used to fabricate TiO2-Ag composite powders for application in oxide barrier between filaments of superconducting multifilamentary tapes. The powders were prepared from an aqueous solution of TiO2 sol and AgNO3. SEM and TEM observations revealed that the average size of the synthesized powder was less than 1μm and consisted of well-dispersed fine primary particles of TiO2 and Ag. It was clearly observed that the microstructure of the particles was altered by conditions of heat treatment.
  • 山本 修, 笹本 忠, 稲垣 道夫
    2002 年 110 巻 1277 号 p. 63-66
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    Self-supported zircon films were successfully formed by heat-treating a gel prepared from the precursor solution of Zr(OC4H9)4 and Si(OC2H5)4 by the sol-gel method. The effect of additives, such as Ni(NO3)2, Cu(NO3)2 and CuCl2, on the formation of zircon film was examined. It was found that the addition of Cu(NO3)2 in precursor solution was effective for obtaining a single-phase zircon at low heat-treatment temperature. From thermal analyses and X-ray diffractometry, the crystallization temperature of zircon was found to be about 950°C. A zircon film with the size of 8mm×8mm×6μm was obtained which did not contain any crack.
  • 末廣 隆之, 多々見 純一, 井出 貴之, 目黒 竹司, 米屋 勝利, 松尾 秀逸
    2002 年 110 巻 1277 号 p. 67-69
    発行日: 2002/01/01
    公開日: 2010/08/06
    ジャーナル フリー
    AlN fibers were synthesized by the gas-reduction-nitridation of Al2O3 fibers with different characteristics. The constituent phase in Al2O3 raw fibers changed from γ-Al2O3 to α-Al2O3, while the surface roughness increased and the specific surface area decreased through the heat treatment. The extent of nitridation of resultant fibers decreased with the decrease in specific surface areas, and with the increase in crystallite size of the raw materials. In particular, the samples transformed to α-Al2O3 were found to have lower reactivity. The enhancement of reduction-nitridation reaction can be attributed to (1) the nitridation progress at a low temperature because of the similarity in crystal structure between AlN and transition aluminas, and (2) the persistence of γ-Al2O3 at a high temperature, due to the suppression of the polymorphic transformation of alumina by the preceding formation of AlN.
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