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Volume 51, Issue 4
Displaying 1-18 of 18 articles from this issue
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Tadahiro Wada, Kazuki Hiro, Shinji Yoshihara2004 Volume 51 Issue 4 Pages 199-205
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAs aluminum alloys have high strength-to-weight ratio, they are used for many automobile parts. Aluminum alloys are generally machined for the improvement of the dimensional accuracy. In finish cutting of the conventional aluminum alloy such as a 6061 aluminum alloy, the continuous chips have a bad influence on the machining operation. In this study, in order to clarify the influence of Si contents in the aluminum alloys on cutting characteristics, five kinds of the aluminum alloys, which had the different Si contents, were turned. The tool materials usedd were high speed steel and cemented carbide. In turning of the aluminum alloys, the chip configuration, cutting forces and tool wear were experimentally investigated. The main results obtained are as follows: (1) The inferior feed rate limit, which can be obtained the desirable chip configurations for the chip control, decreased with the increase of the Si contents of the aluminum alloys. (2) In case of the high speed steel tool, the tool wear increased with the increase of the Si contents. However, in case of the cemented carbide tool, there was little influence of the Si contents on the tool wear.View full abstractDownload PDF (4769K) -
Masakuni Ozawa, Ken-ichi Araki2004 Volume 51 Issue 4 Pages 206-210
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTechnology of porous alumina coating on stainless steel substrate was examined for the development of the environmental catalytic part, which was used under heat condition. Although oxidation resistance of stainless steel (SUS304) was not so high, the stable coat layer was made through a simple dipping-drawing procedure of γ-Al2O3 slurry. Thermal stability of the coat layer on stainless steel was examined by the change about surface area, XRD, and SEM morphology in the temperature range of 500-1100°C. The surface area was 108m2/g and 96m2/g after heat treatment in 0.2%O2-99.8%N2 at 900°C and 1000°C, respectively. The coat layer was stable with porous structure on stainless steel below the temperature of 1000°C.View full abstractDownload PDF (1903K) -
Hidekazu Yamamoto, Nobuya Machida, Toshihiko Shigematsu2004 Volume 51 Issue 4 Pages 211-216
Published: April 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSLithium-ion-conducting amorphous materials in the system Li2S-GeS2 were prepared by use of a high-energy ball-milling process. The amorphous materials were obtained over the wide composition range up to 66.7mol%Li2S content. The composition range in which the amorphous materials were obtained by the ball-milling process was much wider than the glass-forming region by conventional melt-quenching methods. The lithium-ion conductivities of the obtained amorphous materials increased with an increase in the Li2S content. The activation energies for conduction correspondingly decreased with increasing the Li2S content. The 66.7Li2S⋅33.3GeS2(mol%) sample showed the maximum conductivity 1.1×10-4Scm-1 at 298 K.DC polarization measurements suggested that a lithiumion transport number was almost unity for the obtained amorphous materials.View full abstractDownload PDF (536K) -
[in Japanese]2004 Volume 51 Issue 4 Pages 218
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (78K) -
Chikara Ohtsuki, Toshiki Miyazaki2004 Volume 51 Issue 4 Pages 219-225
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSArtificial bone, i.e. implant material, is widely used for reconstruction of damaged bone tissue. Implant material is required to show high biological affinity to the surrounding living tissue. Artificial materials are generally encapsulated by fibrous collagen tissues to be isolated from surrounding bone, when implanted in bony defects. However, some special types of ceramics are known to show ability of direct bone-bonding, i.e. bioactivity. Previous studies reported that the essential requirement for materials to exhibit the bioactivity is formation of bone-like apatite on their surfaces in body environment. The same type of apatite formation can be observed in a simulated body fluid (SBF) that mimics ion concentrations of human extracellular fluid. The apatite formation is triggered by specific functional groups such as Si-OH, Ti-OH, Zr-OH, Ta-OH, which can induce heterogeneous nucleation on the surface of materials. These findings bring us an idea that even bioinert metals show bioactivity, if such functional groups are formed on their surfaces with gradient structure. As a novel kind of surface treatment, the alkali treatment has been developed to induce bioactivity on various kinds of metal such as titanium, tantalum, zirconium and molybdenum. Bioactive surface layer composed of metal hydroxide is formed by the treatment and it takes a graded structure toward the interior of the substrates. Bioactive materials with graded structure are useful as artificial bones with ability of tight bone-bonding.View full abstractDownload PDF (2508K) -
Nobuyoshi Takabatake, Shizuo Nakamura, Masayuki Kozima, Kentaro Ohhash ...2004 Volume 51 Issue 4 Pages 226-229
Published: April 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSLaminated TiO2/V2O5/ITO films acted under visible light irradiation were prepared by sol-gel processing. The absorption band of the TiO2/glass was found to shift to visible light regions using laminated TiO2/V2O5/ITO films. The rate of decomposition of CH3CHO on laminated TiO2/V2O5/ITO films was found to become more quickly than that on TiO2/glass under Xenon lamp irradiation. The earth connection seems to eliminate electron-hole recombination centers.View full abstractDownload PDF (1587K) -
Yoshiyasu Itoh, Takahiko Shindoh, Hideyasu Andoh, Shoko Suyama2004 Volume 51 Issue 4 Pages 230-236
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFunctionally graded materials, which have the extremely reductionability of thermal stress for temperature difference and/or different material constants, have been expected for various energy system components used at high temperatures. Until now, the functionally graded materials to apply to various energy apparatus have been developed. Thermal barrier coatings (TBCs) had been already applied to hot-section parts of gas turbine such as a bucket and a combustor. Nowadays, the multi-layered developments concerning to the high durability TBCs have been conducted concerning to the coating processes such as plasma spraying and electron beam physical vapor deposition. Moreover, a tungsten/copper graded component produced by sintering and infiltration method was developed as a heat sink material against high heat flux such as plasma. A functionally graded material of zinc oxide system was developed for the nonlinear element with a high surge energy absorption capability. Also, a tungsten/copper graded coating was developed by using low pressure plasma spraying as electric arc resistant coatings.View full abstractDownload PDF (9838K) -
Qingchun Shen, Jiayi Shan, Takashi Itoh, Kuniyuki Kitagawa2004 Volume 51 Issue 4 Pages 237-241
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn order to prevent the high temperature oxidation of C/C composites, we applied a multi-layer coating to them. First, the graded SiC layer was prepared on the C/C substrate with a pack cementation method. Second, the stress relaxation layer was coated on the graded SiC layer by sintering slurry of alumina mixed with ZrSi2 particles. Finally, the glaze layer was deposited on the stress relaxation layer by melting slurry of Al2O3-CaO-K2O-SiO2. We obtained results that the graded SiC layer creates the stronger bonding between the C/C substrate and the above coating layer by decreasing the difference in the coefficients of thermal expansion (CTE), the stress relaxation layer prevents to the generation of channels and the glaze layer or molten oxide film protects the substrate from high temperature oxidation.View full abstractDownload PDF (3442K) -
Masayuki Niino, Katsuto Kisara2004 Volume 51 Issue 4 Pages 242-249
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIt has been about 20 years since the concept of functionally graded materials (FGMs) was first proposed, and the FGM study is now in the level of practical application. The FGM research developed from the national projects by the national government has spread to the commercial level, and we came to see many FGM products made by mass production methods. In this report, several major samples of FGM application technologies created by private companies are introduced. In addition, the recent development of FGM study including international collaborations and the most advanced fields of studies are discussed. The FGM Forum of Japan that has devoted for promotion of FGM technology will be reported on its role and future activities.View full abstractDownload PDF (7904K) -
Masao Ogawa2004 Volume 51 Issue 4 Pages 250-254
Published: April 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe baseball spike is used carbon steel mainly. But, the spike was worn down with soil.
Our developed baseball spike is designed to connect cemented carbide and carbon steel by resistance welding. However, there is a problem of connecting technology of the ceramics and the metal, because of the temperature stress destruction which originates in the thermal expansion difference of the ceramics and the metal. It was necessary to develop the connecting technology in order to control this effectively. The cemented carbide tip and the shank are bonded by optimum welding condition, and so the bead is formed to the boundary section.
The bottom of cemented carbide tip contacts with a groove of shank surface in the point, and thus, electric current per unit time flows more and welding efficiency improves.
Coefficient of thermal conductivity of cemented carbide is large in comparison with carbon steel. With the heat energy when welding, the part of cemented carbide tip melts, then a solid solution layer is formed around cemented carbide tip. The hardness of this part shows the value between hardness of cemented carbide and carbon steel. In other words it becomes functionally graded spike. Finally, we could develop the baseball spike which is superior in abrasion, and with low cost.View full abstractDownload PDF (4720K) -
Akira Moriya, Jing-Feng Li, Ryuzo Watanabe, Noriyoshi Tsuji, Shinichi ...2004 Volume 51 Issue 4 Pages 255-259
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTitanium and titanium-alloy (Ti-6Al-4V) have recently been used as bolt and nut materials of jet engines. But the bolts and nuts often seize up with a material to be fixed because Ti and Ti-6Al-4V alloy have high friction coefficient and low thermal conductivity. In order to prevent seizing, the surfaces of the bolts and nuts of titanium and titanium-alloy are treated by plasma carburizing process. Plasma-carburizing that uses the glow-discharged hydrocarbon gases produces a high concentration of carbon in the surface layer within a short period of time. It has thus been frequently applied to industrial materials to concentrate carbon content in their surface region. However, the carburized materials often lose fatigue strength. In this study, the fatigue property of titanium and titanium-alloy after carburization was investigated. The following results have been obtained. (1) No significant differences in the fatigue property have been found between the carburized and non-carburized materials. (2) Fatigue property depends on the structure of base metal.View full abstractDownload PDF (3594K) -
Hua-Ping Xiong, Akira Kawasaki, Yan-Sheng Kang, Ryuzo Watanabe2004 Volume 51 Issue 4 Pages 260-265
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFunctionally graded metal/ceramic coatings with thicknesses varying from 0.75mm to 2.1mm were designed and deposited onto a steel substrate by plasma spraying. The heat insulation performance of these coatings were studied. It was found that, at a given heat flux, the thicker specimens exhibited higher surface temperature (Ts), greater temperature difference (ΔT) and higher effective thermal conductivity (λeff). The thermal cycling test with a surface temperature of 1400°C (during heating) was also conducted for the study of fracture mode of the specimens. Furthermore, the fracture behavior of the coatings at high surface temperatures between 1500°C and 1700°C was investigated. The coating thickness and surface temperature were found to influence the number and the length of cracks. The results showed that thinner coatings were susceptible to local spallation at the top coat, and while, the thicker FGM coatings were susceptible to cracking at the interface close to the bond coat.View full abstractDownload PDF (3793K) -
[in Japanese]2004 Volume 51 Issue 4 Pages 268
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (107K) -
Taro Atsumi, Hitoshi Taimatsu2004 Volume 51 Issue 4 Pages 269-273
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe ZnO-base oxides ZnO-0.5mol%Bi2O3-(0.5-x)mol%Nb2O5-xmol%TiO2-3mol%CoO (x=0-0.5) were synthesized at 1200°C, and their electrical properties were investigated. The microstructure of the sintered compacts consisted of ZnO grains containing Co and Bi-Zn-Nb-Ti-Co-O grain boundary phase. The compound composing the grain boundary phase was classified in three types depending on x. The I-V characteristic showed ohmic behavior at x=0, and non-linear behavior at x>0. The non-linear coefficient and the varistor electric field increased with increasing x, while the electrical conductivity decreased. The electrical properties are influenced by both the crystal structure and the composition of the grain boundary phase.View full abstractDownload PDF (2000K) -
Yukio Sakabe2004 Volume 51 Issue 4 Pages 274-284
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCalcium-doped BaTiO3-based dielectrics have a high resistance to reduction. This can be explained by taking the following three factors into account: 1) decrease in conduction electron density caused by acceptor Ca ions at the Ti site, 2) low freezing temperature of the equilibrium reaction by Ca ions at the Ti site, and 3) large enthalpy change in the reduction reaction by Ca ions at the Ba site. Fine-grained BaTiO3 ceramics can be prepared using the tetragonal BaTiO3 powder using ultra-fine starting BaTiO3 powder synthesized by hydrolysis method. The non-uniform distortion is caused in the grains during sintering, which is attributed to the surface tension and clamping stress from the thin grain boundary layer. This suppresses the tetragonality symmetry of the grains and provides the BaTiO3 ceramics with a high dielectric constant, low loss, and flat capacitance temperature characteristics. The Ca-doped ultra-thin dielectric layer compatible with nickel electrode can realize the nickel electrode multilayer capacitors of large capacitance and large volumetric efficiency, which is competitive with the Ta and Al-electrolytic capacitors and as reliable as conventional precious metal electrode multilayer capacitors.View full abstractDownload PDF (6383K) -
Hiroshi Kagata, Ryuichi Saito, Hidenori Katsumura2004 Volume 51 Issue 4 Pages 285-288
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDielectric properties of Al2O3-MgO-ReOx (Re: rare earth) systems in the microwave region have been studied. We found that the magnetoplumbite phases in the MgO-poor regions of MgReAl11O19(Re: La-Tb) compositions had positive TCF (temperature coefficient of resonance frequency) values in spite of having low dielectric constants of under 20. By mixing a lead-free glass with the Al2O3-MgO-Sm2O3 system, a novel LTCC which we term an AMSG (which A represents Al2O3, M represents MgO, S represents Sm2O3, and G represents glass) was obtained that was characterized by a low dielectric constant (<10), a near zero TCF, and high bending strength. When firing these AMSG green sheets inserted between HTCC(high temperature cofired ceramics) alumina or magnesia green sheets that cannot be sintered at the AMSG sintering temperature, the AMSG sheets were seen to shrink not in the x-y directions but in the z direction due to the constraining effects of the HTCC layers. The obtained non-shrinkage substrate had precise dimensions and a high degree of flatness. The AMSG and the non-shrinking techniques have potential for application to integrated RF modules in mobile communications equipment.View full abstractDownload PDF (315K) -
Katsu Yanagimoto, Kazuhiko Majima, Satoshi Sunada, Yoshikazu Aikawa2004 Volume 51 Issue 4 Pages 289-292
Published: April 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDC biased permeability (μAC) of the powder composite cores was examined for several soft magnetic materials with the viewpoint of partial DC permeability (μΔ) and coercivity (Hc). The materials with low coercivity had μAC in proportion to μΔ while the materials with higher He shows no relation between μAC and μΔ. It was confirmed that the low and constant He and high μΔ in the BH curves were necessary to improve DC biased permeability.View full abstractDownload PDF (1652K) -
Katsu Yanagimoto, Kazuhiko Majima, Satoshi Sunada, Yoshikazu Aikawa2004 Volume 51 Issue 4 Pages 293-296
Published: April 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSElectromagnetic wave absorbing properties of composite sheets using Ar gas atomized and attrition milled powders of several soft magnetic compositions were examined. The sheet of Fe-50Ni powders whose aspect ratio was the largest of all tested materials showed the maximum u" value, and the sheet of Fe-6Si powders whose average particle size was the minimum showed the maximum frequency of μ" maximum. Concerning the flattening behavior of the atomized powders which was confirmed to relate with the mechanical properties of the materials, the larger aspect ratio could be obtained for the softer material, and the larger average particle size could be obtained for the material of the larger maximum elongation.View full abstractDownload PDF (1837K)
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