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Volume 40, Issue 6
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[in Japanese]1993 Volume 40 Issue 6 Pages 578
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (71K) -
Tohru Kohno1993 Volume 40 Issue 6 Pages 579-584
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA fabrication process of sintered parts is recognized as a lower-cost process than other fabrication processes owing to lower consumption of energy and higher yield of materials. Recently, however, research and development of powder metallurgy processing for high performance materials which contain higher-cost process than conventional ones sometimes has been widely carried out.
In this paper some of our recent trials of process development for high strength and high ductility (toughness) sintered parts are introduced.
The topics are as follows ; 1) High strength Fe-Cu-P-C sintered alloys which have little dimensional change during sintering, 2) High strength high ductility W-Ni-Fe heavy alloys, 3) Sinter-forged high speed steels utilizing fine powders produced by high pressure water atomization, 4) Two-steps powder forging of rapidly solidified aluminum alloy powders.View full abstractDownload PDF (3231K) -
Akira Fujiki, Akiyoshi Ishibashi1993 Volume 40 Issue 6 Pages 585-588
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical properties of PM alloy steels containing 5%No, 5%Ni, 5%Co and 6%Cr were investigated in order to develop an intake valve seat insert for automobile engines. After the rig wear test, corrosion test and actual engine tests, the new intake valve seat insert material was developed. The material was 5% No PM molybdenum steel made through the transient liquid phase sintering, in which the copper phase is precipitated uniformly in the matrix. This material can be used for both leaded and unleaded gasoline engines.View full abstractDownload PDF (1714K) -
Koshiro Ueda, Mutsumi Moribayashi, Tohru Kohno1993 Volume 40 Issue 6 Pages 589-592
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe properties of HIP'ed specimens such as deformation, density, bending strength, hardness, and microstructure are investigated and compared with sintered specimens without HIP treatment (normal process). It is confirmed that the properties of HIP'ed specimens sintered at 1180-1195°C in vacuum are superior to normal process.
The result obtained can be summarized as follows;
1) The accuracy : the deformation of HIP'ed specimens are little (less than 60μm), whereas that of specimens made by normal process are more than 150μm.
2) The mechanical property : bending strength of HIP'ed specimens is 358-372kgf/mm2, whereas that of specimens made by normal process is 270kgf/mm2.View full abstractDownload PDF (2367K) -
Mitsuru Nakamura, Ko-ichi Kamada, Hiroshi Horie, Toshinori Kowata, Tos ...1993 Volume 40 Issue 6 Pages 593-597
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHIP method was applied to sintering-duffusion bonding technique of the sintered structural parts. An appearance of the bonding surface and the difference of mechanical properties of the bonded material was studied. The compositions of the green compacts used in this work were Fe-0.8mass%C-2mass%Cu and SUS304L-0.2mass%B. Bonding was carried out in three combinations of Fe-Fe, SUS-SUS and Fe-SUS. As a result, the temperature of HIP treatment was lower 200-300K compared to ordinary sintering condition. The bonded compact was obtained approximately 100% relative density. This process has an advantage diffusion bonding of the same materials ( Fe-Fe and SUS-SUS), because these specimens were fractured in basis material area. However, the dissimilar material (Fe-SUS) was brittle.View full abstractDownload PDF (3908K) -
Akira Hara, Masaru Yokota1993 Volume 40 Issue 6 Pages 598-601
Published: June 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFatigue phenomena in conventionally sintered Al-5%Cu-0.5%Mg-0.8%Si alloy with a density ratio of 91.5% has been investigated by using a cantilever type internal friction measurement device which is electro-magnetically drived and vibrated at the resonance frequency(fr). Changes in fr during vibration at a constant amplitude correspond to those in the internal friction(Q-1), and a marked decrease in fr occurs as a result of the formation of fatigue cracks. These cracks propagate mainly along grain boundaries in as-sintered specimens, and transgranularly in T6 treated ones.View full abstractDownload PDF (5159K) -
Observation of the Density Distribution for an Aluminum Sintered Compact with an Acoustic MicroscopeNorimitsu Hirose, Junichi Asami1993 Volume 40 Issue 6 Pages 602-605
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe density distribution of an aluminum sintered compact was investigated with an acoustic microscope at 15MHz in pulse-wave mode in water using propagative media. The compact was tensile tested, and the result was discussed in terms of the acoustic image corresponding to the density. Green compact specimens were filled using three procedures to obtain the different density distributions of sintered compacts. The acoustic image obtained by relative echo intensity (REI) clearly revealed the density distribution of the specimen. The fracture of the specimens originated at lower density area or at a laminated defect, which were obviously characterized in acoustic inner-images before the tensile testing. The REI was significantly reduced at remarkably elongated areas where lower density areas had been observed before testing. The acoustic image was able to detect pore growth and substantial local elongation of the specimen to obtain the change in REI.View full abstractDownload PDF (4850K) -
Yoshiharu Yamamoto, Kiyoshi Gotani, Noriyoshi Shigaki1993 Volume 40 Issue 6 Pages 609-613
Published: June 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSDuring thermal decomposition of ammonium paratungstate (Monoclinic and Orthorhombic AP T), study on formation process of very fine grain tungsten oxide particle was carried out by thermobalance in nitrogen atmosphere. Thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and specific surface area measurement have been used to make clear the thermal decomposition process. The results obtained are as follows.
(1) Both monoclinic and orthorhombic APT decompose into WO3 through the following order:
5(NH4)2O⋅12WO3⋅5H2O→X(NH4)2O⋅12WO3→12WO3
5(NH4)2O⋅12WO3⋅11H2O→X(NH4)2O.12WO3→12WO3
(2) Crystal system of X(NH4)2O⋅12WO3 changed along the following step.
APT→Amorphous→Hexagonal ammonium tungsten bronze (→Monoclinic WO3)
(3) Ultrafine individual particles are formed on the original APT particle changed like spongy at around 773K, and the particles were uniform in size and shape.View full abstractDownload PDF (4856K) -
Keisuke Kageyama1993 Volume 40 Issue 6 Pages 614-617
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe relation between crystal distortion and Q value at microwave frequencies for Ba(Zn1/3Ta2/3)O3(BZT) and Ba(Zn1/3Ta2/3)O3-(Sr, Ba)(Ga1/2Ta1/2) O3(BSZGT) was investigated. The Q values of BZT and BSZGT increased with the increase of crystal distortion for long time sintering. The lack of Ba from the stoichiometric composition increased crystal distortion for BZT and BSZGT. But the lack of Ba did not always improve the Q values of BZT and BSZGT. The HIP treatment for BZT and BSZGT increased density and dielectric constant, but it showed a little effect on crystal distortion and the improvement of Q value.View full abstractDownload PDF (239K) -
Eiji Fujii, Hideo Torii, Masumi Hattori, Tatsuo Fujii, Kiyoshi Kuribay ...1993 Volume 40 Issue 6 Pages 618-622
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCox Fea-xO4 (0. 1≤×≤1.0) films and a Co0.1Fe2.9 O4/Zn0.5Fe2.5O4 double layered film were prepared on soda-lime glass substrate (a=87×10-7/deg) by plasma enhanced MOCVD and their microstructures and magnetic properties were studied. The Co ferrite films consisted of a random orientated initial layer (thickness < 100 nm) and an <100> orientated columnar layer. Conversion electron Mossbauer spectra and magnetization curves of the films indicated that the films had an easy axis perpendicular to the film plane. The Co ferrite film with higly perpendicular magnetic anisotropy could be obtained by using Zn ferrite film (thickness:210 nm) as a buffer layer between the Co ferrite film and the substrate.View full abstractDownload PDF (2121K) -
Shigetaka Wada1993 Volume 40 Issue 6 Pages 623-629
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSErosion of ceramic materials often limits their use in many structural applications. This paper reviews knowledge on the erosive wear of ceramics mainly in terms of the mechanical properties of a target material.
Two major erosion mechanisms are the fracture mechanism and the scratching mechanism. These erosion mechanisms are affected by the mechanical properties of a target material, such as the hardness and the fracture toughness, as well as the erosion conditions such as the mechanical properties of an impacting particle, the impact velocity and the impact angle.
The erosive wear rate(V) is largely dependent on the ratio of the hardness of the target material(Hvt) to that of the impact particle(Hvp). When Hvt/Hvp<1, the most part of the erosive wear is caused by the fracture mechanism. When Hvt/Hvp>1, on the other hand, the erosion mechanism is mainly the scratching. When the erosive wear is caused by the fracture mechanism, V is related to the fracture toughness of the target material(Kct), as expressed by the equation VocKctb, where b is a negative number. In other words, the larger the hardness and fracture toughness of the target material are, the better the target material is as the anti-erosion material.View full abstractDownload PDF (1765K) -
Shigeru Unami, Osamu Furukimi1993 Volume 40 Issue 6 Pages 630-636
Published: June 15, 1993
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffects of graphite addition and sintering temperature on tensile strength of sintered compacts made from 1%Cr-0.7%Mn-0.3%Mo steel powder have been investigated.
A sintered compact with 0.9% graphite addition gives the maximum strength of 760MPa at the process condition of compacting pressure of 690MPa and sintering temperature of 1523K. The major factors controlling tensile strength of 1%Cr-0.7%Mn-0.3%Mo sintered compact have been proved to be sintered density, contents of carbon and MnO⋅Cr2O3 spinet inclusions and amount of cementite precipitated in grain boundaries.
The decrease of tensile strength of the sintered compact with 1.2% graphite addition is caused by precipitation of cementite in grain boundaries. The tensile strength lowers with the increase of sintering temperature from 1423K to 1473K because of the decrease of carbon content. The tensile strength increases with the increase of sintering temperature from 1473K to 1523K because of the reduction of MnO⋅Cr2O3 spinel oxide.View full abstractDownload PDF (2885K) -
Takeshi Kaneko1993 Volume 40 Issue 6 Pages 637-644
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTensile testing at room temperature and microstructural characterization were performed on a series of tungsten heavy alloys containing 91.3-97.0wt% tungsten. Ductility of the alloys decreased continuously with increasing tungsten content. The ultimate tensile strength exhibited a maximum near 95.5wt% tungsten. The strength maximum resulted from a trade-off between volume fraction strengthening and microstructure limited ductility.
Fracture surface observations indicated that the maximum strength is correlated with the tungsten cleavage failure mode. At higher tungsten contents the tendency toward intergranular failure increased.View full abstractDownload PDF (4130K) -
Katsuhiro Nishiyama, Yasunori Kotani, Kiyoshi Miyama, Soukichi Umekawa1993 Volume 40 Issue 6 Pages 645-648
Published: June 15, 1993
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffects of Cu addition on the mechanical properties of Al-16vol%Pb-3vol%Mg alloys, and also on friction and wear properties were investigated. A ring-on-block type Ogoshi wear test and a pin-plate type test were conducted in air to study the dry sliding behavior of Al-Pb-Mg-Cu alloys against high carbon chromium bearing steel(SUJ2). The wear characteristics were compared with that of leaded bronze(LBC4). The result obtained were summarized as follows:
(1) The mechanical properties depend on Cu content and porosity. A maximum bending strength of 120Mpa was obtained at 3vol%Cu content.
(2) The wear ratio against hard steel(SUJ2) is almost independent of Cu content.
(3) The wear ratio of alloys with 0-6vol%Cu against SUJ2 is less worn than the currently used LBC4.
(4) The wear ratio of the alloys decreases with increasing applied load.View full abstractDownload PDF (1522K)
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