Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 44, Issue 9
Displaying 1-14 of 14 articles from this issue
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  • [title in Japanese]
    [in Japanese]
    1997 Volume 44 Issue 9 Pages 806
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.806
    JOURNAL FREE ACCESS
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  • The Fundamental Characteristics of Forming Bonded Magnet Powder Using Ultrasonic Vibration
    Yoshiyuki Hashimasa, Masakazu Okita, Shuji Mino, Naoyuki Ishigaki
    1997 Volume 44 Issue 9 Pages 807-811
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.807
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    The compaction molding attached ultrasonic vibration, which was applied longtitudinaly through upper punch was studied for the bonded magnet composed of an anisotropic Nd-Fe-B powder and an epoxy resin binder in order to melt binder without heating of mold. In this work, the influence of the amplitude and duration of ultrasonic vibration on the compound temperature in the dies was investigated. The results show that the minimum time of ultrasonic vibration required for binder melting can be shortened by increasing the amplitude, then bonded magnets can be compacted efficiently. The bonded magnets made by this method have a powder volume fraction of 77.7% at compacting pressure of 550MPa. This value of compacting pressure is lower than that of warm compaction molding required to obtain same volume fraction.
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  • Magnetic Properties of Sm(Fe, Co, V)7 Nitriding Compounds
    Hiroshi Yamamoto, Kasyu Takahashi, Takeshi Okano, Syunji Suzuki, Akira ...
    1997 Volume 44 Issue 9 Pages 812-817
    Published: September 15, 1997
    Released on J-STAGE: December 04, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.812
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    This experiment was carried out to investigate the magnetic and physical properties of Sm(Fe, Co, V)7NY compounds. The preparation of melt spun ribbons of Sm10(Fe0.95Co0.05)xV7.5 (X=82.5-102.5) system alloys was tried by the single roller rapid-quenching method. And the effect of roller velocity, heat-treatment and nitrogenation on some properties were investigated. The optimum making conditions and some properties are as follows : composition-Sm10(Fe0.95Co0.05)82.5V7.5N17.45; roller velocity -50m/s; pre-heating condition -650°C×0.5h (in Ar atmosphere) ; nitriding condition-525°C×5h (in high-purity N2 gas at pressures of 4.9MPa); magnetic properties-HcJ= 428kA/m (5380 Oe), σr=86.3×10-6 Wb.m/kg (68.7 emu/g), σs =134.7×10-6 Wb⋅m/kg (107.2 emu/g), Tc=492°C, Lattice constant ; a=0.5030nm c=0.4277nm.
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  • Improvement of Intrinsic Coercivity in HDDR-proccessed Anisotropic Permanent Magnets
    Takashi Ikegami, Satoshi Hirosawa
    1997 Volume 44 Issue 9 Pages 818-821
    Published: September 15, 1997
    Released on J-STAGE: December 04, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.818
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    High-coercivity anisotropic magnet powder of HcJ=1.24MA/m has been developed in HDDR process by substituting Dy for Nd to decrease the value of irreversible thermal flux losses. The newly developed powder provides lower irreversible thermal losses than MQP-B up to 100°C when molded into resin-bonded magnets. The magnets made from the high-HcJ powder give higher relative open flux when magnetized under a magnetization field of 1.2MA/m at 80°C than magnetized at 20°C. To magnetize these magnets at high temperature also decreases the value of irreversible thermal flux losses.
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  • Development of Compression-Molded Nd-Fe-B Anisotropic Bonded Magnets
    Hideki Matsunaga, Masakazu Okita, Shuji Tsujimoto, Naoyuki Ishigaki
    1997 Volume 44 Issue 9 Pages 822-826
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.822
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    High-energy compression-molded bonded magnets, composed of anisotropic Nd-Fe-B powder, epoxy resin and lubricant with low melting point, were developed. The influence of the lubricant on the magnetic properties, the degree of magnetic orientation and the mechanical strength of bonded magnets were investigated. The results show that the frictional force between powders is decreased by using a lubricant with low melting point. Bonded magnets made by this method have a powder volume fraction and degreee of magenetic orientation of 78Åì and 95Åì, respectively. The mechanical damage of the magnetic powder in compounding and compression process is suppressed by using the lubricant with low melting point. Bonded magnets with a high mechanical strength can be obtained by improvement in the compounding process.
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  • Magnetic Properties of Sm-Co and Sm-Co/M (M=Co, Fe) Exchange-Spring Films
    Yoshihiro Yamazaki, Kazuhide Takano, Hitoshi Takamura, Satoshi Sugimot ...
    1997 Volume 44 Issue 9 Pages 827-832
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.827
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    The structure and magnetic properties of Sm-Co films and Sm-Co/M (M=Co, Fe) multilayered films prepared by rf sputtering were investigated. The results show that a hard magnetic phase as Sm2Co17 and SmCo5 phase and a soft magnetic phase were formed by annealing Sm-Co and Sm-Co/M films. Sm16Co84 film annealed for 1.8 ks at 773 K had the springback ratio of [Mr-M(H)]/[Mr-M(H)]=0.72. This film was found to behave as a exchange-spring magnet composed of a hard magnetic phase and a soft magnetic phase. Sm16Co84/Fe multilayered film was also found to be a exchange-spring magnet.
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  • Magnetic Properties of SmFe7Nx+αFe Nanocomposite Magnets and their Application
    Akira Fukuno, Tomomi Yamamoto, Tetsuya Hidaka, Hideki Nakamura
    1997 Volume 44 Issue 9 Pages 833-838
    Published: September 15, 1997
    Released on J-STAGE: July 12, 2010
    DOIhttps://doi.org/10.2497/jjspm.44.833
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    Nanocomposite magnet materials with composition of (Sm8Zr3Fe85Co4)85N15 were prepared by rapidly quenching method including heat treatment and nitrogenation. The ranges of grain sizes are 20-40nm. X-ray diffraction study indicated that hard phase is SmFe7Nx, and that soft phase are a-Fe. By compositional analysis of fine grains using TEM-EDS, it is revealed that magnetically hard phase of SmFe7Nx have a composition of Sm richer ratio than that of 1-7 stoichiometry. Magnetic properties of those powders were as follows : Br=0.99T, Hcj=656kA/m, (BH)max=140kJ/m3, Hk/HcJ=33%. Magnetic properties of their bonded with epoxy resin through die press process were as follows: Br=0.76T, Hcj=672kA/m, (BH)max=96kJ/m3, Hk/HcJ = 35%. Performance of spindle motors equipped those bonded fabricated in ring shape meets magnetic properties of bonded magnets.
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  • Development of the Bonded Magnets Mixed with Different Magnetic Powders
    Atsunori Kitazawa, Yusuke Sakagami
    1997 Volume 44 Issue 9 Pages 839-842
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.839
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    Rare-earth magnets composed of two or more kinds of magnetic powders have some excellent properties, because some disadvantages of one kind of magnetic powders are compensated by the other. Temperature properties are improved by the interparticle interaction in the Sm2Co17+Sm2Fe17Nx resin bonded magnets. Mechanical strength of Sm2Co17+ HDDR-processed Nd2Fe14B bonded magnets is higher than that of HDDR-processed Nd2Fe14B bonded magnets. In the Sm2Fe17Nx+ Nd2Fe14B bonded magnets, high energy product is achieved. With proper adjustment of the preparation conditions, the magnetic properties of the Sm2Fe17Nx+ Nd2Fe14B bonded magnet are Br=1.08T, Hcj=967kA/m, (BH)max=200kJ/m3. The temperature coefficients of Br and Hcj in this magnet are -0.07%/°C and -0.51 %/°C.
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  • Sintering Behavior of Mo Powder Compact Applied SPS Spark Plasma Sintering Method
    Takashi Sakamoto
    1997 Volume 44 Issue 9 Pages 845-850
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.845
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    In this study we used the SPS spark plasma sintering method (hereafter SPS) with single Mo powder, a mixed powder and an added Ni powder which was thought to promote sintering of the Mo powder. SPS is a very effective sintering method for Mo powder sintering too, because density remarkably improved when using the lower sintering temperature. But, grain particles in the microstructure grew to a large size as sintering progressed. This sintering process is significantly time dependent, while surface and boundary diffusion proceeds quickly and soon comes to an end. The density of Mo mixture added Ni powder increased more in lower sintering temperatures than the single Mo powder on SPS. However, the decrease of activation energy on densification for sintering of Mo mixture added Ni powder is smaller than that of Mo powder.
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  • Inner Defect Evaluation of Metal Injection Molded Specimens
    Norimitsu Hirose, Yoshimitsu Kankawa, Junichi Asami
    1997 Volume 44 Issue 9 Pages 851-857
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.851
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    Inner defects of metal injection molded specimen at varied injection speed were investigated by secondary electron images, acoustic images, radiographs and finite element method.
    In particular, the inner defects occurred near gate, the shape and distribution state at low injection speed differed from high injection speed. We consider that the irregular tensile stress caused by shrinkage of crystallized polymer (polypropylene) as binder used in this study had occurred the inner defects. The shrinkage area of polymer with crystallized at cooling is differ at injection speed, and at termination of injection molding, the area is at center at low injection speed and is near capillary wall at high injection speed. At the area, the particle size and distribution of metal powder (SUS316L) were not uniform in scale of them. Therefore, tensile stress occurred partially among metal powders, the partial tensile stress causes the origin of crack.
    The results of comparison surface with inner defects of acoustic images show that inner defects exist under surface where compound consisted of metal powder and binder composition, changes as contrast of acoustic surface images.
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  • Mechanical Properties Al-Cr Base Alloys Containing Icosahedral Phase Produced by Extrusion of Atomized Powder
    Hisamichi Kimura, Akihisa Inoue, Kenichiro Sasamori, Norito Kawamura
    1997 Volume 44 Issue 9 Pages 858-863
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.858
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    Bulk Al96-xCr3Ce1Cox(x=1, 1.5, 2) and Al95-x Cr3Ce1CoxTM1(TM=Zr, Mn, Fe) materials with a dimension of about φ8 mm×300 mm were produced by extrusion of gas atomized powders at 523, 573, 623, 673 and 723 K. The gas atomized powder has a spherical shape with an average diameter of about 15μm, which consists of icosahedral, Al, Al9Co2 and Al13Cr2 phases. The bulk Al94.5Cr3Ce1Co1.5 material extruded at 573 K consists of icosahedral, Al, Al9Co2 and Al13Cr2 phases. The Yong's modulus, Vickers hardness (Hv), ultimate tensile strength and plastic elongation in the bulk form are 83 GPa, 170, 570 MPa and 8.4 % for Al94.5Cr3Ce1Co15 and 89 GPa, 210, 670 MPa and 4.4 % for Al93.5Cr3Ce1Co1.5Mn1, respectively. The Hv at the testing temperature of 573 K for the Al94.5Cr3Ce1Co1.5 and Al92.5Cr3Ce1Co1.5Zr2 bulk materials are 55 and 75, respectively, which are more than twice as large as that for the 7075-T6 alloy.
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  • Oxidation Behavior of Ni Powder and Ni Powder Compact
    Michio Yamazaki, Shouichi Ochiai, Yasuhiro Watanabe
    1997 Volume 44 Issue 9 Pages 864-869
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.864
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    Ni powder samples and Ni powder compacts were oxidized at 450, 500 and 550°C up to 40 h in air. The change of oxidation fraction as afunction of time obeyed, for Ni powder samples, the Jander equation withan activation energy of 0.948×105 J/mol. For the Ni powder compactsthe increase of oxidation fraction was similar, at the beginning, to thatfor free powders but gradually diminished, the final fraction being lessthan unity. The Jander's model was modified, for powder compacts, byintroducing the effect of decrease of concentration difference ofdiffusing species in each particle due to packing of oxide between theparticles. This modified model for compacts gave an activationenergy of 1.113×105 J/mol. The activation energy of oxidation of bulk Ni samples are much higher than the present ones for powdersor powdrer compacts, The two possible reasons for the discrepancy werediscussed with regard to the difference of oxidation temperatures and tothe tensile stress formed between Ni particles and oxide shells aroundthe paticles.
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  • Formation of Free Graphites during Sintering Green Compact Made of Mixture of Iron Powder Including Boron any Graphite
    Satoshi Uenosono, Kuniaki Ogura, Yoshifumi Nakano, Ji-Bin Yang
    1997 Volume 44 Issue 9 Pages 870-875
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.870
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    The sintered steel made of a green compact of the iron powder containing b oron and sulfur and 1.4mass% graphite consisted of ferrite microstructure and free carbon more than 1.0mass%. The X-ray diffraction analysis of the residue made by dissolving the sintered steel into nitric acid proved that free carbon has been graphitized. The graphite in the, sintered steel orientated higher than the added graphite powder. The free graphite precipitated in the pore sites of the sintered steel on cooling after sintering.
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  • Slip Casting and Sintering of Y-PSZ(Part1)
    Preparation Conditions of Slurry
    Saburo Sano, Kenichi Koizumi, Takumi Banno, Yasuo Shibasaki, Kiichi Od ...
    1997 Volume 44 Issue 9 Pages 876-880
    Published: September 15, 1997
    Released on J-STAGE: May 22, 2009
    DOIhttps://doi.org/10.2497/jjspm.44.876
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    This study is concerned with the fabrication of engineering ceramics parts with complicated shape by using slip casting process. Preparation conditions of slurries for 3 kinds yttria partially stabilized zirconia (Y-PSZ) powders were examined by the measurement of zeta-potential and viscosity. As the powder characteristics, the isoelectric points of Y-PSZ powders were determined from zeta-potential measurement to be pH7.9 and 9.0 for powders produced by hydrolysis and pH5.3 for a powder produced by neutralization coprecipitation. Well-dispersed slurries were found for Y-PSZ powders by adding organic polymer deflocculant (polycarboxilic ammonium) to the zeta-potential of the powder becoming enough high at the negative side. When the adding amount of deflocculant was shorted and the zeta-potential was around OmV, the viscosity of the slurry becoming very high and can't use for slip casting. In a case of a Y-PSZ powder produced by hydrolysis, low viscosity slurry can be prepared without adding deflocculant since the zeta-potential is high enough at the positive side.
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