IEEJ Transactions on Fundamentals and Materials
Online ISSN : 1347-5533
Print ISSN : 0385-4205
ISSN-L : 0385-4205
Volume 127, Issue 8
Displaying 1-11 of 11 articles from this issue
Review
  • —The Case of Dielectric and Electrical Insulating Materials—
    Noriyuki Shimizu, Yuji Muramoto
    2007 Volume 127 Issue 8 Pages 429-432
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    Humankind is required to reduce environmental impact caused by its activity. Materials and products have been evaluated by criteria of performance in use and price. Now environmental impact is added to the criteria for evaluation. One of the future directions of science and technology is to minimize the environmental load of materials and products keeping their state-of-the-art performance. Adoption of natural materials is one of promising ways to realize that. This review will introduce some examples in the field of dielectric and electrical insulating materials.
    Download PDF (881K)
Paper
  • Yohei Miyazaki, Kazutaka Kitamori
    2007 Volume 127 Issue 8 Pages 433-438
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    In the simulation of plasma processes, minimizing the error associated with the electric field calculation in the vicinity of the sheath is an important consideration. The sheath length scale when compared to the plasma size and fact that the electric fields must be solved for self-consistently with equations describing the plasma chemistry make the electric field solution particularly expensive. Because an internal electric field is calculated based on the density of charged particles, it is necessary to obtain the density of charged particles correctly but at minimum possible expense. We describe an electric field simulation with high speed and good accuracy enabled by the description of the density of charges by spline functions. Preciously, we have taken advantage of the orthogonality of the Legendre polynomial in our methodology described as LPWS (Legendre Polynomial Weighted Sampling). Sampling with other orthogonal functions is also possible and as such we have generalized our method. The generalization, Orthogonal Polynomial Weighted Sampling (OPWS), whereby the method of obtaining the coefficient of B-spline function from the coefficient of the orthogonal expansion has been developed and is described in this paper.
    Download PDF (745K)
  • Minoru Amano, Tsutomu Katabami, Hiroyuki Yokosawa, Yotaro Akamine
    2007 Volume 127 Issue 8 Pages 439-444
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    We made a new fostering program for electric power engineer aiming to win market and to reduce management risk. The program is based on the best learning method of three skills of Robert L Katz (1)----expansion of human skill and conceptual skill put together at expansion speed of technical skill---- from four study verification results.
    This method is applied to the electric power engineer, and confirmed by Kirkpatrick level II.(2)
    It is thought that the above-mentioned two problems can be cleared by achieving the result which will correspond to level III and IV in the near future.
    Download PDF (695K)
  • Shota Sugano, Hideaki Wakabayashi, Hiroshi Inai
    2007 Volume 127 Issue 8 Pages 445-451
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    It is well known that surface-relief dielectric gratings with rectangular profile can be treated by uniform approximation of equivalent permittivity when the periodicity is very small compared with a wavelength. In optics, this phenomenon is the equivalent anisotropic effects or the form birefringence. When the periodicity is very small, the equivalent anisotropic effects will be shown in index modulated gratings. In this paper, the uniform approximation is described for electromagnetic scattering problem by index modulated gratings. Scattering properties by dielectric slabs are calculated by transmission-line theory and the equivalent permittivity obtained from our proposed formulation of uniform approximation. Scattering by index modulated gratings are analyzed rigorously by the matrix eigenvalue calculations by using Fourier expansion method and the spatial harmonics expansions. When the periodicity is small, both results are in good agreement. By investigating the difference between the equivalent permittivity and the numerical values corresponding to the permittivity of index modulated gratings, the applicable condition of the uniform approximation is shown. And the equivalent anisotropic effects of various permittivity profiles are compared.
    Download PDF (539K)
  • Yuki Ito, Masashi Sato, Kenichi Wakisaka, Shinzo Yoshikado
    2007 Volume 127 Issue 8 Pages 452-458
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    Molybdenum silicide (MoSi2) has high electrical conductivity as much as metal, and high chemical stability than such as SiC in various atmospheres. Therefore, many kinds of MoSi2 bulk-type heaters are practically used for operation up to 1800°C, which is higher than that of SiC heaters. However, MoSi2 is fragile at room temperature and has low creep resistance at high-temperature. The purpose of this study is to fabricate heaters using thin films of MoSi2 deposited on alumina substrates and crucible by RF magnetron sputtering and evaluate their characteristics. MoSi2 thin film was deposited on outside of the alumina crucible without heating substrate and then Pt wire attached using Pt paste by sintering in vacuum. This MoSi2 thin film heaters showed almost linear R-T characteristics and uniform heating state. They also showed good controllability of voltage and stability of power-T characteristics to operate up to 1000°C. However, at 1300°C of heating temperature, heating area of MoSi2 thin film decreased caused by the reaction of Pt and MoSi2 in the case of long-term heating. Thus, Mo thin film was deposited, as a buffer layer, between Pt and MoSi2 thin film to prevent such a reaction. This thin film heater showed good linier R-T characteristics up to 1200°C. But, the temperature coefficient of resistance changed as heating operation was repeated. This is due to the diffusion of Mo atoms into MoSi2. Thus, thin film heater was fabricated with Mo3Si whose content of Mo is more than that of MoSi2. This heater showed less diffusion of Mo or Pt atoms into thin film and excellent practical characteristics up to 1000°C.
    Download PDF (1193K)
  • Norikazu Fuse, Shinjiro Fujita, Naoshi Hirai, Toshikatsu Tanaka, Masah ...
    2007 Volume 127 Issue 8 Pages 459-466
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    Partial discharge (PD) resistance was examined by applying a constant voltage for four kinds of biodegradable polymers, i.e. poly-L-lactic acid (PLLA), polyethylene terephthalate succinate (PETS), poly ε-caprolactone butylene succinate (PCL-BS), and polybutylene succinate (PBS), and the results were compared with those of low density polyethylene (LDPE) and crosslinked low density polyethylene (XLPE). The PD resistance is determined by the erosion depth and the surface roughness caused by PDs, and is ranked as LDPE ≅ XLPE > PLLA ≅ PETS > PBS > PCL-BS. This means that the sample with a lower permittivity has better PD resistance. Furthermore, observations of the sample surface by a polarization microscope and a laser confocal one reveal that crystalline regions with spherulites are more resistant to PDs than amorphous regions. Therefore, good PD resistance can be achieved by the sample with a high crystallinity and a low permittivity.
    Download PDF (2254K)
  • Madoka Baba, Yukihisa Suzuki, Masao Taki, Kaori Fukunaga, Soichi Watan ...
    2007 Volume 127 Issue 8 Pages 467-472
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    A new method to measure three-dimensional (3D) temperature distributions is developed. This method is applicable to the experimental studies to relate tissue temperature elevation with specific absorption rate (SAR) in a material exposed to radiofrequency electromagnetic fields (RF-EMF). The temperature sensor used in this study is micro-capsulated thermo-chromic liquid crystal (MTLC). A gel phantom containing MTLC is made from carrageenan. An exposure experiment is performed by using a dipole antenna. Temperature distributions are visualized as color distributions in real-time and non-destructive way. Calibration curve is obtained so as to relate the hue of the color to the temperature. Temperature distributions of the exposure experiment are estimated using the curve. The exposure experiments with other RF-EMF sources are also performed. These results show that this method has wide application for measuring 3D temperature distributions.
    Download PDF (5262K)
  • Hiroaki Uehara, Katsutoshi Kudo
    2007 Volume 127 Issue 8 Pages 473-480
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    Recently, polymer/polymer composite insulating systems have been widely used in high-voltage equipment and power cables. Such composite insulating systems always have an interface between two polymeric insulating materials. This interface may cause partial discharge and electrical treeing under high electric stresses. The electrical properties of this polymer/polymer interface have not yet been fully understood. It has been shown that the propagation characteristics of electrical trees in polymer/polymer composite insulating materials considerably vary depending on the combination of polymers. It has also been shown that a cavity or a thin gas layer generates near the polymer barrier molded in the base polymer, by the pressure of decomposing gas occurred in the tree channels during ac tree extension.
    In this study, we will investigate the 3-dimensional simulated tree utilizing three layers model considering a thin gas layer on a barrier based on a DBM model with growth probability.
    The results show that the critical fields of air layer are related to the easiness of tree propagation in the air layer. Moreover, it is suggested that the three layers model is more effective than the two layers model when the tree propagation is discussed in detail.
    Download PDF (1216K)
  • Hiroshi Yamamoto, Kenta Osanai
    2007 Volume 127 Issue 8 Pages 481-486
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    This experiment was aiming for making high performance isotropic bonded magnet. And this experiments were carried out to investigate the effect of Ti addition for magnetic properties of Sm-Fe-Co-Mn system nitriding compounds with TbCu7-type structure. Sm10(Fe0.9Co0.1)89.5-xMn0.5Tix (x = 0˜1.0) alloy ribbons were prepared by the single roller rapid-quenching method. And the effects of alloy composition, and conditions of heat-treatment and nitrogenation on the magnetic properties were examined. The optimum preparation conditions of the compounds are as follows. Composition: {Sm10(Fe0.9Co0.1)89Mn0.5Ti0.5}86.8- N13.2, roller velocity: 50 m/s, heat treatment: 700 °C×60 min in high-purity Ar gas, and nitriding condition: 420 °C×15 h in high-purity N2 gas. Typical magnetic properties of the obtained compound powders are Jr = 0.97 T, HcJ = 730.8 kA/m, (BH)max = 140.0 kJ/m3 (17.6 MGOe), and TC = 500 °C. It was found that this sample was an exchange spring magnet from XRD, TEM photograph and recoil loops of the hysteresis curve. The value of (BH)max for the isotropic compression molding bonded magnet prepared from the {Sm10(Fe0.9Co0.1)89Mn0.5Ti0.5}86.8N13.2 powder is 94.8 kJ/m3 (11.9 MGOe), when the density of bonded magnet is 6.07 Mg/m3. And the reversible temperature coefficient of Jr is α(Jr) = -0.04 %/°C, the temperature coefficient of HcJ in the range from 25 °C to 125 °C obtained by a linear extrapolation is α(HcJ) = -0.40 %/°C.
    Download PDF (1690K)
  • Daisuke Tashima, Kenji Kurosawatsu, Mitsufumi Taniguchi, Masafumi Uota ...
    2007 Volume 127 Issue 8 Pages 487-492
    Published: August 01, 2007
    Released on J-STAGE: September 01, 2007
    JOURNAL FREE ACCESS
    In this study, ketjen black was used for polarized electrodes instead of conventionally used acetylene black in order to improve the capacitance of activated carbon-based Electric Double Layer Capacitor (EDLC). Usually, ketjen black exhibits higher electronic conductivity compared to acetylene black, so that ketjen black could be considered as conducting filler. Moreover, N2 adsorption-desorption isotherm as well as TEM observation revealed that ketjen black used in this study has different type of pore structures compared to acetylene black. The capacitances of prepared EDLC were evaluated from discharge characteristics. It was found that the ketjen black containing EDLC showed fairly high capacitance compared to acetylene black containing one. Especially, 8 wt% ketjen black containing EDLC showed the highest capacitance among the prepared samples. The specific capacitance of the best one was evaluated as 59.2 F/g. It was also found that the 8 wt% ketjen black containing EDLC exhibited fairly stable capacitance at elevated tempareture from temperature dependence of capacitance for 10 wt% acetylene black containing EDLC and 8 wt% ketjen black containing one.
    Download PDF (1527K)
Letter
feedback
Top