材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
48 巻 , 6Appendix 号
選択された号の論文の10件中1~10を表示しています
  • Takao HANABUSA
    1999 年 48 巻 6Appendix 号 p. 63-73
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Thin film coating by physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques are advancing intensively in the technology of mechanical as well as electrical fields. Deposition by these techniques essentially develops residual stresses in the film for intrinsic and extrinsic reasons. The microstructure of the film normally exhibits a strong preferred orientation on a crystallographic scale. Residual stresses and the microstructure of the growing film influence the properties of the film as well as the film/substrate system. The present paper demonstrates the recent developments in X-ray stress evaluation of the film having a very sharp preferred orientation. A new method of X-ray stress measurement for such films having a strong texture is presented in place of the conventional sin2Ψ method. C-axis oriented aluminum nitride (AlN) films, [111] fiber textured aluminum and titanium nitride (TiN) films and [110] fiber textured TiN films are investigated to study the residual stress and the effect of heat treatment on the state of residual stress. The effects of patterning the film on residual stress are also investigated.
  • Shao-Yun FU, Xiao HU, Chee-Yoon YUE
    1999 年 48 巻 6Appendix 号 p. 74-83
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Extrusion compounding and injection molding processes are frequently employed to fabricate short-fiber-reinforced polymers. During extrusion compounding and injection molding processing, considerable shear-induced fiber breakage takes place and results in a fiber length distribution (FLD) in final short-fiber-reinforced polymer (SFRP) composites. Also, during compounding and molding processing, progressive and continuous changes in fiber orientation occur and lead to a fiber orientation distribution (FOD) in final composites. Both FLD and FOD are governed by a number of design and fabrication factors including original fiber length, fiber content, mold geometry and processing conditions. The mechanical properties such as strength, stiffness and fracture toughness or specific work of fracture (WOF) of SFRP composites have been shown to depend critically on FLD and FOD. The present paper reviews previous research work on the effects of design/fabrication factors on FLD and FOD and the effects of FLD and FOD on the strength, stiffness and toughness or WOF of SFRP composites. Conclusions which can be drawn from the literature are presented with discussions of areas in which further research is required.
  • Jian-Feng YANG, Tohru SEKINO, Yong-Ho CHOA, Koichi NIIHARA
    1999 年 48 巻 6Appendix 号 p. 84-89
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The pressureless sintering was investigated to fabricate dense Si3N4/SiC nanocomposites from commercially available Si nitrided Si3N4 powder. MgAl2O4+ZrO2 (totally 10 and 15wt%) or Y2O3+Al2O3 (totally 10.5 and 14wt%) and 5-30vol% SiC were used as sintering additives and second phase dispersions, respectively. With increasing SiC content, the density of the composite containing less amount of sintering additives decreased linearly, while the large amount of sintering additives decreased gradually the density or kept it constant. The composites with higher SiC content presented a relatively smaller Si3N4 grain size, because the Si3N4 grain growth was inhibited by SiC particles that pinned the grain boundary movement. While decrease in strength was observed for the composites with less amount of sintering additives, an improvement of the strength was found for the composites with high amount of sintering additives. The strength change of the composites was consistent with their densification behavior and microstructural observation. Composite with 20vol% SiC exhibited high strength up to 1GPa. With increasing SiC content, hardness increased but toughness decreased. It is concluded that the results of this study provide an economic way to fabricate the Si3N4/SiC nanocomposite with high performance.
  • Tsuneshichi TANAKA, Hideaki NAKAYAMA, Akiyoshi SAKAIDA, Noriyo HORIKAW ...
    1999 年 48 巻 6Appendix 号 p. 90-97
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Tensile strength distribution of carbon fibers was investigated for different gauge lengths ranging from 2 to 100mm. In tensile tests, the fiber diameter was determined as the three-point minimum diameter d3 at neighborhoods of both ends and the center of gauge section by using an optical microscope. Weibull analysis of the data and the effective volume model for tensile strength of carbon fiber showed that the shape parameter a was not constant for different gauge lengths and the effective volume model could not be applied effectively to the results. It was found that these were caused by the fact that the diameter was never constant along a carbon fiber. Consequently, in this study, it was aimed to derive the distribution of the tensile strength σ0 for the true minimum diameter d0 along the gauge length. In order to do this, two-dimensional distributions of d3 and d0 were derived from the data of diameter measured at every 0.1mm along a single fiber with the gauge length of 100mm. Combining these distributions of d3 and d0 with the distribution of the tensile strength σ3 for the diameter d3, the distribution of the strength σ0 was derived analytically, and calculated by using numerical values of included parameters. The distributions of σ0 obtained for respective gauge lengths mutually agreed very well and could be represented by a single normal distribution, and this showed the validity of the present analysis.
  • Takayuki KUSAKA, Masaki HOJO, Shojiro OCHIAI, Tomoaki KUROKAWA
    1999 年 48 巻 6Appendix 号 p. 98-103
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Effects of loading rate on mode II interlaminar fracture behavior of unidirectional CF/conventional-epoxy (T300/2500, Toray) and CF/toughened-epoxy (IM600/133, Toho Rayon) composite laminates were investigated over a wide range of loading rate from quasi-static to impact at room temperature (displacement rate, δ=10-7-101m/s). A newly developed experimental method using the SHPB (Split Hopkinson Pressure Bar) technique and the ENF (End Notched Flexure) specimen was employed for measuring the accurate fracture toughness at very high loading rates. The mode II fracture toughness at the onset of crack growth showed positive rate dependence (fracture toughness increased with increasing loading rate) at lower loading rates, while it showed negative rate dependence (fracture toughness decreased with increasing loading rate) at higher loading rates; there existed a local maximum value of fracture toughness at intermediate loading rates. The impact fracture toughness was about 13 and 29% lower than the local maximum value for the conventional epoxy composite and toughened epoxy composite, respectively; the toughened epoxy composite was more sensitive to the loading rate than the conventional epoxy composite. Microscopic observation showed that the debonding of fiber/matrix interface was dominant at lower loading rates and that the cohesive fracture of matrix resin was dominant at higher loading rates. The transition point of microscopic fracture morphology approximately coincided with the local maximum point of macroscopic fracture toughness. In addition, the load-displacement relation was non-linear just before the onset of crack growth at lower loading rates but almost linear up to the maximum point at higher loading rates.
  • Sung-Ho YOON, Jun-Young KIM
    1999 年 48 巻 6Appendix 号 p. 104-109
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effects of the winding process variables on the tensile properties of the filament wound structures were investigated. The ring specimens, consisted of the carbon fiber as reinforcement and the epoxy as resin, were fabricated through the filament winding technique for the measurement of the tensile properties. The fiber tensions and the fiber ends were considered as the winding process variables. The fiber tensions per fiber bundle varied from 4.9N to 29.4N. The fiber ends varied from 1 end to 6 ends. The tensile properties of the ring specimens were evaluated through the split disk test. The fiber volume fractions and the void contents for the ring specimens were also measured by the resin digestion. According to the results, the tensile properties of the ring specimens were sensitive to the fiber tensions and the fiber ends, which were closely related to the fiber volume fractions and the void contents. Therefore, the suitable selection for the winding process variables should be conducted to maximize the structural performance and to increase the productivity of the filament wound structures.
  • Shin AKUTSU, Yoshio UTSUSHIKAWA
    1999 年 48 巻 6Appendix 号 p. 110-115
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this study, we examined the correlation among the crystal structure, the unpaired electron, and the magnetism of carbon fine particles. From the result of X-ray diffraction, it is determined that the saturation magnetization of the carbon fine particles is influenced by degree of crystallinity, when the degree of crystallinity is 3.62%. The saturation magnetization is 8.5×10-7Wb·m/kg. The saturation magnetization of carbon fine particles increases with decreasing grain size, and the grain size of the carbon fine particles having the highest Ms of 8.5×10-7Wb·m/kg is 19nm. From the ESR spectrum, the g-factor of the carbon fine particles is found to be 2.0023. The magnetism of carbon fine particles may be due to the electron spin. Electron spin density of the carbon fine particles is 1.6×1022kg-1 and it is observed that the electron spin density increases by 1.5 times as compared with graphite. From the temperature dependence of ESR, it is found that the linewidth of the ESR increased with decreasing temperature, and the spin-spin relation time T2 decreased with decreasing temperature.
  • Masafumi KOBUNE, Hiromi IIDA, Yoshiaki SORAI, Atsushi MINESHIGE, Satos ...
    1999 年 48 巻 6Appendix 号 p. 116-121
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Sodium yttrium calcium-oxyhydroxyapatites powders with compositions of {[Ca9.98-0.9xY0.9xNa0.02](PO4)6[(OH)1.98-0.9xO0.9x_??_0.02], x=0-1.0 (here _??_ denotes vacancies at OH lattice sites} were synthesized by the wet process. Porous (Ca, Y, Na)-Ap (here Ap denotes apatite) ceramics having apparent porosities of around 33% were prepared at high temperature under steam flow. On the basis of the results of X-ray diffraction, all the obtained ceramics exhibited almost single-phase (Ca, Y, Na)-Ap with hexagonal structure. The impedance for all samples linearly changed from 106 to 104Ω at 50°C in the humidity range of 40-95%RH. Apatites produced by substituting Y3+ and Na+ for Ca2+ in apatite structure showed an excellent conductivity. This is attributed to both ordinary protonic conduction caused by the self-dissociation of physically adsorbed water and another conduction caused by OH vacancies introduced by substituting Y3+ and Na+ for Ca-sites.
  • Jae-Hung HAN, Junji TANI, In LEE
    1999 年 48 巻 6Appendix 号 p. 122-127
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this paper, multi-modal vibration control of smart composite plates has been studied. Piezoelectric films and ceramics have been used as sensors and actuators in surface bonded forms. For modeling and analysis of smart composite plates, an efficient finite element method based on the layerwise plate theory has been used. The effect of thickness changes due to bonded piezoelectric materials and variable in-plane displacement fields on the dynamic, actuating and sensing characteristics have been considered in the finite element formulation. This study includes an optimization method based on genetic algorithms to select appropriate locations of piezoelectric sensors and actuators of a smart composite plate for maximization of control performance. The cost function used in the optimization is based on degrees of controllability, observability, and spillover prevention. Experimental multi-modal vibration control has been also performed. A smart composite plate is prepared according to the optimization results for the experimental works. Coupled positive position feedback algorithms have been implemented in digital signal processing (DSP) system. The control results show that vibration level of the controlled modes has been significantly reduced with negligible effect on the residual modes.
  • Katsukuni YOSHIDA, Tomohiro GOYA
    1999 年 48 巻 6Appendix 号 p. 128-129
    発行日: 1999/06/15
    公開日: 2009/06/03
    ジャーナル フリー
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