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Volume 51, Issue 6
Displaying 1-10 of 10 articles from this issue
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Toshikazu Tanaka2004 Volume 51 Issue 6 Pages 405-409
Published: June 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe Curie temperature and saturation magnetization of as-deposited Mn, MnZn, NiZn, and Co ferrite thin films by sputtering were different from those of heat-treated films at 700°C-900°C. After heat treatment, Curie temperature and saturation magnetization of Co ferrite thin films were invariable, whereas those of Mn, MnZn, and NiZn ferrite thin films depended on the heat treatment temperature. In the case of the ferrite thin films containing Mn and Zn, these results are explained by a nonequilibrium ion distribution, but another cause must exist in the case of the Co ferrite thin film. As-deposited sputtered ferrite thin films show nonequilibrium phenomena in both Curie temperature and saturation magnetization, whose cause is considered to depend on the ion content.View full abstractDownload PDF (316K) -
Koji Amezawa, Hidesato Kondo, Yoichi Tomii, Naoichi Yamamoto2004 Volume 51 Issue 6 Pages 410-414
Published: June 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSElectrical conduction in undoped and Ca-doped NdBO3 with the orthorhombic aragonite-type structure was investigated by using conductivity measurements under 0.4-5kPa of p(H2O) and 0.01-100kPa of p(O2) at 500-925°C. From humidity dependence and H/D isotope effect of the conductivity, it was found that NdBO3 became a protonic conductor under wet conditions by partially substituting Ca for Nd. The conductivities of 1mol%Ca-doped NdBO3 were 10-5.4-10-4.1 S⋅cm-1 under wet condition at 500-925°C. As temperature increased, electron holes became to contribute to the conduction, although protons were estimated as dominant charge carriers under the conditions employed. The p(H2O) and p(O2) dependence of the conductivity were discussed in terms of defect equilibrium. Conductivity behaviors as well as conductivity values of Ca-doped NdBO3 were rather similar to those of the Sr-doped LaBO3 with the same crystal structure.View full abstractDownload PDF (414K) -
[in Japanese]2004 Volume 51 Issue 6 Pages 416
Published: June 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (95K) -
Masaru Yokota, Fuminori Sugaya, Haruhisa Mifune, Kazuo Nakai, Shinichi ...2004 Volume 51 Issue 6 Pages 417-422
Published: June 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAlthough metal is comparatively resistant to deterioration, metallic cultural artifacts generally become eroded depending on the storage conditions. Metallurgical investigations on a number of ancient bronze mirrors have been performed by authors and the formation of pure copper lumps and unidentified corrosion products was confirmed on the surface of the mirrors and in the corroded layers. Accordingly, investigations to identify the corrosion products were performed by using an electron probe micro analyzer (EPMA), a scanning electron microscope (SEM) equipped with an energy dispersive spectroscope (EDS), a micro-X-ray diffraction analyzer (μ-XRD), and an X-ray photoelectron spectroscope (XPS). The evidences from the analyses suggest that microorganisms could have been the cause of the corrosion products. Researches and investigations are under way to confirm this perspective. This paper reports on the results obtained by now and visions of the future.
In case that the process of microbiological deterioration of metallic cultural artifacts is clearly ascertained, we expect it will contribute to the advancement of conservation science for cultural artifacts.View full abstractDownload PDF (5600K) -
Hiroyuki Y. Suzuki, Kenji Shinozaki, Shunzo Tashima, Hidenori Kuroki2004 Volume 51 Issue 6 Pages 423-434
Published: June 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSHigh-Speed Centrifugal Compaction Process (HCP) is a variety of wet compacting method for fine ceramic powders by using huge centrifugal force of about 10, 000g. The compacting mechanism of the HCP differs from that of slip casting, a conventional wet compaction method, and therefore the HCP possesses a number of unique characteristics such as a higher compacting speed than pressure casting, wide applicability for net shape formation, as well as defect removing function. Because of homogeneous and flawless green microstructure, the HCP alumina shows a superior sinterabiliy and higher strength and hardness than most other alumina. These advantages can be emphasized with a higher centrifugal force.View full abstractDownload PDF (5492K) -
Toshiko Osada, Kazuaki Nishiyabu, Yasuo Karasaki, Shigeo Tanaka, Hides ...2004 Volume 51 Issue 6 Pages 435-440
Published: June 15, 2004
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSProducing the micro size parts by Metal Injection Molding (MIM) needs more sophisticated technique than the conventional injection molding. Especially, inhomogeneous state of the feedstock will strongly influence on the quality of the final products. In order to evaluate the mixing and pelletizing conditions of the feedstock, statistical variations of density and binder contents in individual pellet were investigated by the weight measurement. These variations were discussed with coefficient of variation. The micro dumbbell specimens were fabricated using the feedstock, and the density and strength were investigated. Moreover, in order to improve the feedstock properties, re-pelletizing was performed. It was found that the homogeneity of the pellet was one of the important factors for quality of the micro size parts produced by MIM.View full abstractDownload PDF (6064K) -
Takashi Itoh, Takeshi Yamashita, Kuniyuki Kitagawa2004 Volume 51 Issue 6 Pages 441-446
Published: June 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt is indispensable for the thermoelectric power generation harnessing waste thermal energy to develop the highperformance thermoelectric materials covering the middle temperature range between 500 and 800 K. Skutterudite compounds and filled skutterudite compounds are the hopeful thermoelectric materials for the middle temperature range. These compounds are usually synthesized by melting. In this study, a skutterudite compound CoSb3 was focused and prepared through the synthesis by mechanical alloying (MA) and the consolidation by spark plasma sintering (SPS). In order to obtain a single phase of the compound CoSb3, the MA syntheses were carried out under various MA conditions in milling time and rotation speed. XRDs were measured to identify the phases for the MA powders and the sintered bodies. The thermoelectric properties of the consolidated compounds were also measured. The influences of MA conditions on the properties were discussed. It was clarified, as a result, that Seebeck coefficient and electrical resistivity are influenced by the milling time and the rotation speed.View full abstractDownload PDF (406K) -
Masaaki Otsu, Tomonori Fukunaga, Hideshi Miura2004 Volume 51 Issue 6 Pages 447-450
Published: June 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSelective laser sintering (SLS) is one of the promising processes for rapid production of complex shaped parts. The relative density of sintered parts obtained by the ordinary SLS process, however, is about 60% and the infiltration process is normally needed after sintering. This study has been performed to improve the relative density and tensile strength of SLSed 316 stainless steel powder (Rapid Steel 2.0) compacts by changing the sintering conditions and adding fine carbonyl Fe powder. By changing the sintering temperature from 1070°C to 1300°C and the sintering time from 4 hours to 8 hours, the relative density was increased from 62% to 80% and the tensile strength was improved from 64 MPa to 262 MPa. As the carbonyl Fe powder was added, the relative density and tensile strength were increased. In the case of 40 wt% carbonyl Fe powder added, the tensile strength became 463 MPa since the shape of pore became spherical and the pore size was fine.View full abstractDownload PDF (3266K) -
Satoshi Sunada, Kazuhiko Majima, Yusuke Miyazaki, Takeshi Hasegawa2004 Volume 51 Issue 6 Pages 451-457
Published: June 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThree kinds of sintered SUS444 stainless steels (P/M stainless steels) whose porosity ratios were 6.9, 9.1 and 13.3 were used in this experiment, and their pitting corrosion behaviors in MgC12 solution were investigated by means of electrochemical measurement and SEM observation compared with normal type SUS444 stainless steel (I/M stainless steel) produced by conventional method. The pitting corrosion resistance of P/M stainless steel decreased with the increasing porosity ratio, and it was lower compared with the I/M stainless steel. The potential of pitting corrosion decreased with an increase in porosity, and the pitting corrosion rate increased as the anodic potential and the porosity ratio increased.View full abstractDownload PDF (1722K) -
Yoshimoto Wanibe, Katsushi Kusaka, Seiji Yokoyama, Takashi Itoh2004 Volume 51 Issue 6 Pages 458-461
Published: June 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis invited lecture consists of two kinds of content. One is a topic about recent trends in technical information which P/M in US has been searching for. MPIF and APMI have had several Special Interest Programs every annual International Conference or World Congress. The trends are summarized by classifying these programs into some categories arbitrarily chosen. The other is the régime of our presentation "Micro structural Dependency of Soft Magnetism in a Sintered Stainless Fe-12%Cr Alloy" in the special interest program 7 'P/M Technologies for Emerging Electronic & Electromagnetic Applications' at the PM2TEC 2003 in Las Vegas.View full abstractDownload PDF (377K)
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