All issues
Volume 56, Issue 3
March
Displaying 1-10 of 10 articles from this issue
- |<
- <
- 1
- >
- >|
Paper
Paper
-
Yuu Shikoda, Yoshinori Tokoi, Koji Suwa, Satoru Ishihara, Tsuneo Suzuk ...2009 Volume 56 Issue 3 Pages 93-97
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSPulsed wire discharge (PWD) is one of nano-sized powder production methods and has been applied for development of mass-produced apparatus. However, methods of collecting produced powders have not been developed yet, and are the major problem of the mass-produced apparatus. Thus, we developed an electrostatic collector for PWD to examine availability and to measure the powders collection efficiency. It was found from the results that we succeeded in collecting nano-sized powders using the electrostatic collector. Anode corona had high powder collection efficiency than cathode corona. This was attributed to the fact that nano-sized powders produced by PWD were positively charged or corona discharge characteristics were different.View full abstractDownload PDF (1245K) -
Yosuke Aoyama, Yoshikazu Kuroda, Teruo Takahashi, Noriyuki Tsuchida, Y ...2009 Volume 56 Issue 3 Pages 98-102
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSHigh nitrogen stainless steel (Fe-17Cr-12Mn-3Mo-1N) fabricated by metal injection molding (MIM) method has prominent strength and ductility. However, the tensile properties are unexplainable only by the influence of nitrogen solid solution strengthening. In this study, to clarify it, we have examined tensile-deformed microstructure. Strength of high nitrogen stainless steel was three times as high as that of SUS316L, without losing ductility, and micro-deformation twinnings were observed for the steels tensile-fractured at room temperature. It is thought that high strength with high ductility of this steel is attributed to solid solution strengthening of nitrogen and the formation of deformation twinning.View full abstractDownload PDF (1278K) -
Yosuke Aoyama, Midori Komada, Yoshikazu Kuroda, Teruo Takahashi, Noriy ...2009 Volume 56 Issue 3 Pages 103-107
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSMicrostructure and mechanical properties of high nitrogen steels containing 17Cr-12Mn-3Mo produced by means of metal injection moulding and nitrogen absorption methods were examined. The compacts were sintered at 1300°C, then furnace-cooled to 1200°C and were held at that temperature for 2 to 20 hrs. Subsequently, they were furnace-cooled. Thereafter, solution treatment was done at 1200°C. The solution treated compacts held at 1200°C for above 5 hrs had homogeneous microstructure. Increasing the holding time at 1200°C, ferrite phase disappeared due to the increment of nitrogen content and grain size became larger. Lattice constant of austenite phase also increased. Yield and tensile strength increased with increasing nitrogen content. Yield and tensile strength of the compact held at 1200°C for 10 hrs were 758 MPa, 1172 MPa respectively and elongation was 41 %. However, ductile-brittle transition (DBT) behaviour was seen, and the DBT temperature of every compact was about -20°C. From the fracture surface analysis, brittle fracture surface was identified as (111).View full abstractDownload PDF (969K)
Special Issue:Ferrite and Magnetic Particles as the Energy and Environment Materials
Summarization
-
Yohtaro Yamazaki2009 Volume 56 Issue 3 Pages 110
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSDownload PDF (94K)
Paper
-
Shenglei Che, Masahiko Watanabe, Kentaro Mori, Naoyoshi Sato, Takuya A ...2009 Volume 56 Issue 3 Pages 111-115
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSDissolution and segregation behavior of Ca in the Sintering process of MnZn ferrite were investigated by microstructure analysis. It was revealed that, as the temperature rises to above 1000°C, Ca dissolves to the spinel lattice and disperses uniformly in the ferrite at the soaking step. Ca begins to segregate to the grain boundaries in the slow cooling process, and the segregation proceeds below 1100°C rather than above. This suggests that control of the cooling in this temperature range is of great importance for the formation of high-resistivity grain boundaries and the lowering of core loss.View full abstractDownload PDF (1635K) -
Hideki Kurihara, Tatsuhiko Yajima, Kiyoshi Nomura2009 Volume 56 Issue 3 Pages 116-120
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSManganese ferrites were quickly prepared from manganese oxide and iron oxide powders by a microwave discharge generated between two pieces of carbon felt (MD/CF) with various powers in air atmosphere, and were characterized especially by X-ray diffractometry and Mössbauer spectroscopy. MnFe2O4 was produced within at least 40 s by MD/CF with more than 200 W microwave power in air atmosphere. With the increase of the applied microwave power, FeO powders were produced in addition to distorted MnFe2O4 by using MnO and Fe2O3 powders as starting mixture. Improved yield for MnFe2O4 were obtained by post annealing for 1 hour or by using the raw mixed materials of MnO, MnO2 and Fe2O3.View full abstractDownload PDF (1061K) -
Yoshitaka Kitamoto, Kenichiro Kimura, Yohtaro Yamazaki2009 Volume 56 Issue 3 Pages 121-126
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSThe present article describes core/shell nanoparticles composed of disordered alloy FePt core and iron-oxide shell with spinel structure for biomedical applications such as magnetic hyperthermia, which requires high ac magnetic susceptibility χ" at around room temperature. The nanoparticles are chemically synthesized by a polyol method in octylether as a solvent using Fe(CO)5 and Pt(acac)2 as precursors, and oleic acid and oleylamine as surfactants. The core/shell nanoparticles are formed under larger amount of Fe(CO)5 and surfactants compared with that for a synthesis of equiatomic FePt nanoparticles. For typical core/shell nanoparticles obtained in this study, the size of FePt core and the thickness of Fe-oxide shell are approximately 9 nm and 1.5 nm, respectively. The shell thickness increases with the increase of a concentration of Fe(CO)5, leading to the increase of the peak value of χ" and the peak temperature in the temperature dependence of χ".View full abstractDownload PDF (1004K) -
— Theoretical Formulation of Magnetic Force Applied to Micro Particle —Fujio Tsumori, Naoki Miyano, Hidetoshi Kotera2009 Volume 56 Issue 3 Pages 127-132
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSIt is important to control the microstructure of powder particles as they could be used to fabricate new functional materials. The deformation of microstructures by the application of magnetic fields is one of the effective methods for controlling microstructures. We attempt to employ magnetic particles and an elastic material to fabricate a new micro device without electric wiring. It is essential to understand how magnetic force works to the micro particle for designing a new micro actuator device.
Theoretical formulation is proposed and used to express magnetic effect and deformation of the elastic material. As the result, it is found that the proposed microstructure using magnetic particles and elastic material can be scaled down to nano level. Simple actuators of various sizes are fabricated to show they could work similarly even if the scales are different.View full abstractDownload PDF (836K) -
— Development of Simulation and Design System —Fujio Tsumori, Naoki Miyano, Hidetoshi Kotera2009 Volume 56 Issue 3 Pages 133-136
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSA simulation system for newly developed magnetic micro actuator is proposed and demonstrated in this paper. Magnetic energy and elastic deformation energy are formulated and used to derive deformation of the actuator. The deformation is determined by using the steepest descent method as the total energy is minimized.
We prepare two types of actuators to demonstrate reliability of the developed simulation system. Deformation patterns observed here show good agreement with simulated ones. A grid type actuator deformed through multiple stages. This characteristic manner was also observed virtually in the simulation system. This system would be useful to design a new arrangement of pillar structures of the present actuator.View full abstractDownload PDF (746K) -
Hiroshi Yamamoto, Hiroaki Nishio, Masaya Ikuta2009 Volume 56 Issue 3 Pages 137-144
Published: 2009
Released on J-STAGE: April 28, 2009
JOURNAL OPEN ACCESSAn experiment was carried out to investigate the effect of La2O3 substitution, molar ratio n {=Fe3+/(Co2++Ni2++La3+)}, concentration of alkali, inflowed time of alkali on the magnetic and physical properties of Co-Ni-La system spinel ferrite fine particles prepared by the chemical coprecipitation method without post-annealing. The chemical coprecipitation compositions were chosen according to the formula (CoO)0.5(NiO)0.5-x(La2O3)0.5x·n/2(Fe2O3), where x varied between 0 and 0.3 and n varied between 2.00 and 2.75. The typical magnetic properties were saturation magnetization σs=47.5×10-6 Wb·m/kg, residual magnetization σr=25.3×10-6 Wb·m/kg, coercivity HcJ =666.1 kA/m. To remove the superparamagnetic substance, the coprecipitation fine particles were etchied with dilute sulfuric acid. As a result, in the (CoO)0.5(NiO)0.475(La2O3)0.0125·1.25(Fe2O3) composition, when the excess NaOH and inflowed time were 0.9 mol and 1 s respectively, the following magnetic and physical properties were obtained: σs=75.9×10-6 Wb·m/kg, σr=58.1×10-6 Wb·m/kg, HcJ=1004.3 kA/m, K1=1.96×105 J/m3, K2=−6.4×105 J/m3, and HA=4.00 MA/m.View full abstractDownload PDF (1042K)
- |<
- <
- 1
- >
- >|