材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
53 巻 , 6 号
選択された号の論文の19件中1~19を表示しています
  • 西田 成樹, 中平 敦, 福西 興至
    2004 年 53 巻 6 号 p. 590-593
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Saponite clays with fine magnetite particles were synthesized by adding solution containing Fe2+ and Fe3+ ions and 10N-NaOH to 1wt%-clay suspension in order to expand the application of clay as an absorbent. The products were analyzed by X-ray powder diffraction (XRD) and thermal analysis. Their microstructure was observed by transmission electron microscopy (TEM). The properties of absorption were evaluated by nitrogen gas and by methylene blue adsorption measurement. The results of XRD showed that products indicated only two phases, clay and magnetite crystal structure, and saponite with fine magnetite particles. Furthermore, from the results of methylene blue adsorption measurement, the usage of saponite clays with fine magnetite particles could result in the removal of methylene blue as an absorbent.
  • 北村 真, 大槻 主税, 尾形 信一, 上高原 理暢, 谷原 正夫, 宮崎 敏樹
    2004 年 53 巻 6 号 p. 594-598
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    α-tricalcium phosphate (TCP) porous body with a continuous 10-50μm pore structure was attained. The α-TCP porous body was fabricated by conventional sintering process from slurry composed of β-TCP and potato starch. Two molding methods were attempted on the fabrication of the porous body; one is direct casting in alumina crucible (CP method), the other is impregnation in polyurethane sponge (SP method). Porosity was controlled by the amounts of starch added in the slurry. Porous body fabricated by CP method showed higher uniformity of pore size distribution than SP method. Compressive strength of the porous body fabricated by CP method was higher than that of the porous body fabricated by SP method. Compressive strength of the porous body fabricated by CP method increased with decreasing the porosity of the body ranging from 45% to 75%. On the other hand, compressive strength of the porous body fabricated by SP method did not increase with decreasing its porosity. Formation of macropores more than 100μm due to decomposition of sponge may govern the compressive strength of the porous body when it was fabricated by SP method. These results indicate that the casting process may give easy fabrication with superior structure in porous α-TCP through conventional sintering.
  • 安藤 柱, 横内 正洋, 李 相起, 高橋 宏治, 中尾 航, 末永 博義
    2004 年 53 巻 6 号 p. 599-606
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Alumina ceramic reinforced by SiC whisker was sintered. Three point bending specimen was made from the composite ceramic. A semi-elliptical surface crack up to 450μm in diameter (aspect ratio≈0.9) was introduced on the specimen. Basic crack-healing behavior of the cracked-sample was studied systematically as a function of crack-healing temperature, and also bending strength of crack-healed sample was tested systematically. Followings are main conclusions obtained; (1) Alumina reinforced by SiC whisker exhibited large crack-healing ability. (2) The fracture toughness KIC of the composite alumina was increased by the SiC whisker reinforcement considerably as compared with alumina reinforced by SiC particles. (3) The crack-healed alumina exhibited the same level bending strength (σB) as the base material and very high σB up to 1473K. (4) The alumina was able to heal the crack even under cyclic stress at 1473K, and the critical stress intensity factor (KHSC) was found to be 3.8MPa √m.
  • 松平 恒昭, 北岡 諭, 葛島 勇介, 淡路 英夫, 伊岐見 大輔
    2004 年 53 巻 6 号 p. 607-612
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Aluminum titanate (Al2TiO5: AT) ceramics have been recently applied as refractories in Al alloy casting systems, because they have excellent thermal shock resistance and corrosion resistance to molten Al alloys. The AT ceramics contain many microcracks at grain boundaries as a result of the large thermal expansion anisotropy during cooling after sintering. In this study, cyclic and static fatigue of the AT ceramics was investigated at actual casting operating temperatures (R. T. -700°C) and the fatigue life related to the morphological change of the microcracks. At R. T., the microcracks around the main crack tip are thought to propagate according to crack resisting-reactivating and wedging-microcracking mechanisms. When the microcracks were closed at 300°C due to the thermal expansion of each AT grain, grain bridging degradation occurs predominantly instead of above mechanisms. In contrast, at the temperature of 700°C that AT grains are bonded together via glassy phase added as a sintered aid, microcracks underwent repeated initiation and self-healing via a glassy phase segregated at the grain boundaries.
  • 井上 栄規, 鎌田 郁子, 塩野 剛司, 西田 俊彦
    2004 年 53 巻 6 号 p. 613-617
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to improve the brittleness of ceramic materials, alumina/30vol% stainless steel (SUS316L) composites were prepared and their mechanical properties were studied from the viewpoint of particle size of dispersed stainless steel. The toughening mechanism of the composite was estimated using COD (Crack Opening Displacement) technique. Increase in the particle size was effective in promoting the interaction between fractured surfaces and enhanced the stress shielding of the crack tip, resulting in improvement of the fracture toughness. For the composite prepared from stainless steel with an average particle size of 20μm, the fracture toughness remarkably increased to 9.5MPa·m1/2, compared with 2.4MPa·m1/2 for monolithic alumina. Blocking of crack propagation and crack deflection were observed around stainless steel particles, as increasing the particle size.
  • 塩見 治久, 向井 仁, 増井 睦美, 橋詰 良美, 秋田 有紀子
    2004 年 53 巻 6 号 p. 618-622
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Three kind of typical calcium silicate powders, i. e. wollastonite, tobermorite and xonotolite, were mechano-chemically activated in air for 24h with a vibration ball-mill. The cakes of the vibration ball-milled calcium silicate added with a fair amount of water were carbonated at 50°C or 80°C in 0.33MPa CO2 for 3h in order to obtain the specimens with a different carbonation ratio. The removal efficiencies of phosphorous for the carbonated specimens were investigated by immersing them in Na2PO4 aqueous solution containing 5ppm phosphorous. After immersing the specimens for prescribed duration in the test solution, the remaining amount of phosphorous in a supernatant liquid was measured by an inductively coupled plasma spectroscope. In the case of the specimens with lower carbonation ratio, about 80% of phosphorous in the Na2PO4 test solution was removed by immersing for 5 to 10 days. In this case, however, very fine precipitation of calcium phosphate was formed. On the other hand, well carbonated specimens showed lower dephosphorizing rate, and it took above 40 days to remove 80% of phosphorous in the test solution. In this case, no fine precipitation was observed even after immersing the specimens for 40 days. It was necessary to obtain the consolidated bodies of calcium silicate with above 50% of carbonation ratio for the removal of phosphorous without fine precipitation of calcium phosphate.
  • 若杉 隆, 吉田 真人, 田中 勝久, 大田 陸夫
    2004 年 53 巻 6 号 p. 623-626
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the composite materials made from metal and glass, high adhesion between them is required. It was reported that high adhesion obtained by the reaction between metal and glass. The glass composition with high activity coefficient of NiO, which is used as an adhesion agent, is desirable to promote the reaction between them. In order to research an optimum composition of glass with high adhesion to metal, activity coefficients of NiO in borosilicate melts was measured by chemical equilibration method. The activity coefficient of NiO decreased with increase of basicity of melts and NaF generally added to enamel increases the activity coefficient of NiO. A relationship between the acitivity coefficient of NiO and optical basicity of melts was found and it is expected that optical basicity would be able to use to find an glass composition for enamel.
  • 元屋敷 靖子, 菅田 淳, 植松 美彦, 城野 政弘
    2004 年 53 巻 6 号 p. 627-632
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue crack growth test of a grain-oriented 3% silicon iron was carried out under constant amplitude loading. Shape of a specimen surface around the fatigue crack tip was transferred to thin plastic films, and these replica films were observed by means of an Atomic Force Microscope (AFM) with high resolution. In the high K region, two preferential slip systems operated in the vicinity of the crack tip. Slip behavior around the crack tip was observed at the maximum and minimum loads for several loading cycles, and slip deformation during loading or unloading cycles was evaluated quantitatively. By considering the slip deformation and intervals of two adjacent slips, it is found that the fatigue crack grows by two preferential slip systems operating alternately. The crack propagation was occurred by the slip deformation and the crack path was inclined because two slips operated asymmetrically.
  • 元屋敷 靖子, 菅田 淳, 植松 美彦, 森山 拓哉, 城野 政弘
    2004 年 53 巻 6 号 p. 633-638
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fatigue test was conducted on a grain-oriented 3% silicon iron under constant amplitude loading. Slip behavior around the fatigue crack tip was observed at the several levels of one loading cycle by means of Atomic Force Microscope (AFM) in order to elucidate the fatigue crack mechanisms. The quantitative evaluation of the fatigue crack growth behavior could be achieved by using the image processing technique. During loading, slips could begin to operate only when the applied stress reached to a certain level. Two preferential slip systems operated at the crack tip in this material. They moved alternately and caused the crack opening and propagation during loading. On the other hand, slips moved in the opposite direction to those during loading at the crack tip alternately and this led the crack closure during unloading. It can be said that the crack open plastically by the slip deformation after it open elastically.
  • 永井 光輝, 臺丸谷 政志, 小林 秀敏
    2004 年 53 巻 6 号 p. 639-646
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The thermal deformation of a circular tube subjected to high-temperature and high-rate moving internal pressure was examined experimentally and analyzed numerically with FEM code, Marc. The time histories of temperature were observed from thermo-couples embedded at several positions along the circular tube with a constant cross-section. Also, the time histories of high-rate moving internal pressure were measured by piezoelectric elements embedded in the inner surface layer of the circular tube. As the first step of numerical analysis, the thermal conductivity analysis was carried out to predict the time histories of temperature at inner surface of the circular tube under the condition of two-dimensional small section model in the cylindrical coordinates. In the second step, the whole temperature distribution of circular tube was calculated using the results of the first step analysis. Additionally, thermal stress analysis was carried out based on the results of the whole temperature distribution of circular tube and thermal deformations of inner and outer surfaces of the circular tube were successfully predicted.
  • 森田 辰郎, 辻 寛治
    2004 年 53 巻 6 号 p. 647-653
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    This study was conducted to get basic information concerning fatigue crack initiation through dislocation dynamics simulation. This simulation was based upon the movement of discrete edge dislocations on slip planes vertical to the surface under a cyclic applied shear stress. The equation which rigorously describes the shear stress acting on dislocations near the surface was obtained using the concept of image dislocations. The result of the simulation showed that no slip step was formed only by the movement of dislocations generated from a dislocation source because the same number of dislocations with the opposite sign alternately escaped from the surface. However, it was found that the formation of a slip step occurred under the existence of sessile dislocations randomly distributed in the material. That is because the stress field of the sessile dislocations disturbed the behavior of movable dislocations. Furthermore, the result of the simulation concerning plural slip planes showed that a fatigue crack can be produced by the growth of each slip step under the existence of the sessile dislocations.
  • 戸梶 惠郎, 大矢 耕二, 森 清二, 高藤 新三郎, 加藤 容三
    2004 年 53 巻 6 号 p. 654-660
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to investigate the effect of cold work on the fatigue behaviour of beta Ti-22V-4Al alloy, rotary bending fatigue tests have been performed using smooth specimens aged after cold work of two different reductions (CWA). The fatigue behaviour of the CWA specimens was evaluated and compared with that of solution treated and aged specimens (STA). It was found that the CWA specimens showed two different crack initiation modes, surface and subsurface crack initiation, depending on stress level, as similarly seen in the STA specimens. In the surface fracture regime, the fatigue strength of the CWA specimens increased remarkably compared with that of the STA specimens and the CWA specimen of higher reduction exhibited higher fatigue strength than the counterpart. Since the crack initiation process had a considerably large fraction of fatigue life, the increase in fatigue strength due to cold work was attributed to increased crack initiation resistance. In the subsurface fracture regime, fatigue strength was almost similar regardless of cold work. A smooth facet was seen at the subsurface crack initiation site. The sizes of the facets were one to two times as large as the average grain size of each CWA specimen and the subsurface crack origin became deeper as stress level decreased. Furthermore, fatigue life tended to increase with decreasing maximum stress intensity factor for facet.
  • 近藤 良之, 栄 中, 久保田 祐信, 工藤 隆夫
    2004 年 53 巻 6 号 p. 661-666
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    It has been recognized that the threshold stress intensity factor ΔKth of short crack is dependent on many factors. Dependencies of ΔKth on material hardness, mean stress and crack size could be successfully evaluated on the basis of crack closure phenomenon. As a consequence, the (ΔKeff)th was almost constant for a wide range of conditions. In this study, however, extraordinary decrease in the (ΔKeff)th was found to occur in some limited condition. It was shown that the reduction was caused by the conjunction of three conditions, namely, high stress ratio (R) larger than 0.8, short crack and hard material whose Vickers hardness was higher than 300. The lowest value of (ΔKeff)th obtained in this study was 0.7MPam1/2 for steel. The fracture surface morphology was trans-granular and no indication of environmental effect was found. The fatigue crack propagation rate near the threshold condition could be uniquely evaluated even in such a short crack regime using the effective stress intensity factor with the following modification {ΔKeff-(ΔKeff)th, a}. Here, (ΔKeff)th, a is the (ΔKeff)th for crack length a. This evaluation could be applicable in short crack regime as short as 0.04mm. ΔKeff still plays a role as the governing parameter for fatigue crack propagation of short crack.
  • 荻原 慎二, 小池 靖人, 丸山 克也, 小林 訓史, 向後 保雄
    2004 年 53 巻 6 号 p. 667-672
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Fiber fragmentation behavior in a single carbon fiber reinforced epoxy composite is investigated experimentally and analytically. Strength distribution of the carbon fiber is also measured. Fiber fragmentation process is observed during tensile loading on the composites. The effect of loading rate on the fiber fragmentation behavior is discussed. The statistical prediction model of fiber fragmentation behavior assuming that the constant interfacial shear stress presents is used to estimate the interfacial shear stress. It is found that the fiber fragmentation behavior is well predicted by using the measured fiber strength distribution and an assumed interfacial shear stress. A Monte Carlo simulation technique in which a stress transfer model based on the linear elasticity is used is also conducted to describe the fiber fragmentation behavior. The effect of loading rate on the failure process around the fiber breaks is also discussed.
  • 越智 真治, 高木 均
    2004 年 53 巻 6 号 p. 673-677
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper deals with the effect of heat-treatment on mechanical properties of both natural fibers and natural fiber reinforced plastics First, bamboo and Manila hemp fibers were heat-treated in air and Ar, and we investigated the effect of oxygen during heat-treatment on the tensile strength of these natural fibers. As a result, in the case of heat-treatment in Ar, the tensile strength of bamboo and Manila hemp fibers was able to resist higher temperature than that in air. Next, mechanical properties of heat-treated natural fiber reinforced plastics were examined. The results showed that although these natural fibers embedded in the resin, the tensile strength of natural fiber reinforced plastics decreased at the same temperature as heat-treated natural fibers in air. This dependence is derived from the remained oxygen in lumens.
  • 日紫喜 剛啓, 一宮 利通, 大野 俊夫, 高田 和法, 平 陽兵, 藤井 秀樹
    2004 年 53 巻 6 号 p. 678-685
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Ultra-high-strength concrete (UHSC) with compressive strength of 150N/mm2 makes it possible to reduce the weight of prestressed concrete structures. Particularly in case that UHSC is applied to pretensioned members, high bond strength can also be expected to reduce the transfer length. Considerable autogenous shrinkage of UHSC, however, reduces effective prestress and causes cracking due to the restraint of reinforcing steel. A new type UHSC with less autogenous shrinkage was developed, and its basic characteristics were investigated. Prestressing tests parameterizing the type of prestressing steel and the amount of introduced stress were also conducted to determine transfer length and to verify the effect of reduced autogenous shrinkage. Furthermore the predictability of effective prestress considering shrinkage and creep strain was studied.
  • 易 庠華, 木下 敍幸, 吉延 匡弘, 関 惠元
    2004 年 53 巻 6 号 p. 686-691
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Sugi (Cryptomeria japonica) rotary veneers with thickness of 3.5mm were compressed in the radial direction using the moisture content in the veneers enclosed in an airtight device set on a hot-press to improve its mechanical properties. The compressive deformation of the rotary veneers with moisture contents of 30% or more were approximately fixed by the compression at 200°C for 3 minutes or 180°C for 8 minutes: These conditions for permanent fixation of the rotary veneers were similar to those of Sugi sawed veneers. The resistance of surface to wear of the compressed rotary veneers was 2 times higher than those of the uncompressed veneers. The dynamic Young's modulus in the longitudinal direction of the rotary veneers increased with an increase in degree of compression. These improvements in the resistance of surface to wear and dynamic viscoelasticity in the longitudinal direction of the rotary veneers were similar to those of the sawed veneers and resulted from increased in density by compression. The dynamic Young's modulus in the tangential direction of the rotary veneers, however, scarcely increased by compression and was much less than that of the compressed sawed veneers. The specific dynamic Young's modulus in the longitudinal direction of the compressed rotary veneers also increased due to an increase in density by the compression, whereas that of the compressed sawed veneers did not vary. It was thought that the difference in the behavior of the specific dynamic Young's modulus between the rotary veneers and the sawed veneers was due to the lathe checks that existed only in the rotary veneers, that is, the compression disappeared from both of the voids of the cells and those caused by the lathe checks for the rotary veneers but disappeared only from the voids of the cells for the sawed veneers.
  • 大谷 俊博, 荻 博次, 平尾 雅彦
    2004 年 53 巻 6 号 p. 692-698
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Electromagnetic acoustic resonance (EMAR) is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method is free from extra energy losses, resulting in the measurement of intrinsic ultrasonic attenuation in solids. In this study, the EMAR was applied to detect the creep damage of a Ni-base superalloy (Waspaloy). The material was exposed to the temperature of 1073K at various stresses. We measured ultrasonic attenuation for 1-6-MHz frequency range as the creep advanced. The attenuation coefficient exhibits much larger sensitivity to the damage accumulation than the velocity. In a short interval, between 35% and 40% of whole life, attenuation experiences a large peak and ultrasonic velocity shows a small depression, being independent of the stress. This novel phenomenon is interpreted as resulting from microstructure changes, especially, dislocation mobility. This is supported by TEM observations for dislocation structure. This technique has a potential to assess the damage advance and to predict the creep life of metals.
  • 井上 裕嗣
    2004 年 53 巻 6 号 p. 699-703
    発行日: 2004/06/15
    公開日: 2009/06/03
    ジャーナル フリー
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