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Volume 37, Issue 3
Displaying 1-14 of 14 articles from this issue
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Takaaki Tabata1990 Volume 37 Issue 3 Pages 391-397
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSConventionally, sintered materials have been considered less reliable than wrought materials in mechanical properties such as tensile strength and impact energy, because of its consequential pores. Thus, sintered materials have been thought unsuitable for applications in important safety-related parts.
Now, production of improved sintered materials with tensile strength exceeding 110kgf/mm2 has been made possible by developed techniques of high density compaction, high temperature sintering, and precisely controlled heat treatment, using partially alloyed steel powders with excellent compressibility. In 1979, as the first producer in the world, Tokyo Sintered Metals Corp. pioneered production of automotive power steering oil pump parts.
In every industry, compactness and light-weight are the current of the times, and applied conditions for such machine component constructural parts are getting severer. We have succeeded in developing material which has high toughness and wear-resistivity in addition to high tensile strength. This material is now applied in production of starter parts for automobile.View full abstractDownload PDF (4618K) -
Kohmei Halada, Hiroo Suga1990 Volume 37 Issue 3 Pages 398-404
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSSize-distribution and locational distribution were investigated for zinc powders produced by the centrifugal atomization with various diameters of the rotating disk, revolution rates and pouring rates of molten zinc. During atomization surface temperature of the rotating disk and atomizing state were monitored by use of a thermoviewer and a VTR camera. The monitoring of the atomization showed the necessity of heating the surface of the disk up to the melting temperature of the metal to obtain fine powders. The relation of the mean diameters of obtained powders to the rotating conditions was found that the mean diameter in dimensionless form was proportional to the inverse square of Weber number. The produced powders showed bimodal size-distributions, which corresponded to the direct-drop-formation breakup.
Finer powders were located nearer to the center of the atomizing chamber, and the pouring rate did not affect the size distributions of powders collected on the bottom of the chamber. Flight of finer powders made by the direct-drop-formation breakup depended on the size of the powder and on the rotating conditions. When the pouring rates were too high an instable columnar breakup occurred to make coarse powders which were flown far-ther.View full abstractDownload PDF (2377K) -
Kohemi Halada, Hiroo Suga1990 Volume 37 Issue 3 Pages 405-411
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFlying distance of the particles atomized by use of a centrifuge was investigated. Numerical calculations sup-ported the experimental results that the finer powders flied shorter than coarser powders. However, the calculated flying distance became a couple of times greater than that observed. Three different hypotheses on the discrepancy of the flight distance were discussed, i.e. (i) the effect of counter flow, (ii) the reduction of centrifugal force transmitted to the droplet and (iii) the increase of the drag force to the flying droplet. The increase of the drag force caused by deformation of the droplet at the moment of departure from the rotating disk explained reasonably the experimental results.View full abstractDownload PDF (459K) -
Takeshi Kaneko1990 Volume 37 Issue 3 Pages 412-420
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffects of cold roll and compression on Ta single crystals grown by electron beam melting methods were systematically studied.
The rolling effect was determined using X-ray techniques and microphotography at successive stages of roll-ing, and the operating slip systems were determind from observations of slip traces on the side and front surfaces rolled. The mean grain size and the mean strain were determined by using the Hall method. The rolling texture was determined by the X-ray pole figure method at successive stages of rolling.
Stress-strain curves of various Ta single crystals were obtained in order to clarify the effect of compressive deformation. The following results were obtained: According to the X-ray investigations and surface observa-tions, the mechanical structure of Ta single crystals subject to cold rolling is destroyed in the order, {110}-<110> and <111>, {111}-<110>, and {100}-<010> and <011>.
The work-hardening effect of Ta crystals, examined by using compression tests, was determined to be, small and in the order, of directions <110>, <111> and <100>. The cold-rolled texture of Ta single crystals is grouped in {100}-<110> and {111}-<l12> orientations, and it is the same as that of Fe single crystals.View full abstractDownload PDF (5865K) -
Shinichi Hirano, Shin Tajima1990 Volume 37 Issue 3 Pages 421-425
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe formation process and magnetic properties of Fe3C particles were investigated. Various iron oxides as a starting material were carbureted with CO gas in a furnace. Fe3C was formed at the reaction temperatures from 450 to 600°C. The partial pressure of CO gas was controlled by mixing with N2 gas to prevent the free carbon deposition due to the disproportionation of CO gas. Synthesized Fe3C particles were identified as a single phase by XRD and the weight change measurement. The saturation magnetization of Fe3C increased from 80 to 117 emu/g with the increase of the reaction temperature, while the coercive force decreased from 170 to 80 Oe with the increase of the reaction temperature.View full abstractDownload PDF (1864K) -
Masahiro Anzai, Takeo Nakagawa1990 Volume 37 Issue 3 Pages 426-432
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSGenerally, particle composite alloy is fabricated by powder metallurgy. The other hand, Plasma Powder Melting (PPM) method has been put into practical use for welding machine in the field of surface hardening. In this study, it is attempted to fabricate metal-carbide composite materials using PPM method.
Each metal (Fe, Ni, Co alloy) and carbide (Cr3C2, NbC, WC) powders are mixed, which are directly melted by plasma arc in the graphite mold so as to obtain metal-carbaide composite materials.
In Fe-Cr3C2, Ni-Cr3C2, Fe-NbC, and Ni-NbC systems, the strength value of these composites were remarkably high in comparison with the products without reinforcing. The factor of strength is caused by change of matrix structure, dispersion of particles and residual stress between metal matrix and carbide.
In all of the composites, bending modulus decreased monotonously with increasing of carbide, and hardness of these increased monotonously.
It has succeeded in making 3-dimensional model of metal-carbide composites using PPM method.View full abstractDownload PDF (5341K) -
Yoshikazu Suzuki, Katsuyoshi Shimokawa, Hidero Unuma, Yoshinobu Ueda1990 Volume 37 Issue 3 Pages 433-438
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt was reported previously by the present authors that by quick heating in vacuum some gases evolved from the Ni-Ti compact during exothermic fusing reaction. It was also suggested that the gas evolution might take the part of triggering the self-exothermic reaction. Gas evolution of H2, and deposits of Na, Cl and O were confirmed by gas chromatography and Auger analysis.
The mechanism of the reaction in Ni-Ti compacts was examined by a microscopic analysis on the semireacted specimens and the calculation of the exothermic heat quantity.
The results showed that the exothermic fusing reactions of the Ni-Ti compact occurr in the composition range 48-56 at%Ni through step reactions of each intermetallic compounds, and that the reaction heat of NaCl and Na2O formation bring about the exothermic fusing reaction.View full abstractDownload PDF (1475K) -
Shigenori Tanabe, Jiro Shibata, Hiyroyuki Ichinose1990 Volume 37 Issue 3 Pages 439-444
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe effect of tin additions on the sintering process of iron powder compact was investigated by means of dilatometric and microscopic examinations, X-ray diffraction and EPMA. The results were summarized as follows:
(1) The first expansion of dilatometric curves from 633 to 773K was caused by penetrating in between iron particles of molten Sn and was analogous to "Copper Growth" in Fe-Cu mixed powder compact.
(2) The second expansion from 1013 to 1173K was caused by disappearing of intermetallic compounds and preferentially diffusing of Sn element in iron matrix.
(3) Compounds (FeSn2, FeSn, and Fe5Sn3) were formed and disappeared correspondingly with the phase diagram. When heated up to 1223K, Sn element was uniformaly dissolved in the iron matrix.
(4) The compact containing larger amount of Sn expanded largely in the first and second expansion region, but shrinked largely at temperatures of 1173K and above because the sinterig was more accelerated in aFe phase than in TFe phase.View full abstractDownload PDF (1419K) -
Yoshikazu Suzuki, Teruhisa Watanabe, Shigeo Tsuchida1990 Volume 37 Issue 3 Pages 445-450
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSP/M 7091 alloy sheets were rolled directly from sintered compacts, and the properties of the sheets were investigated. The alloy powder, and the mixed powders M1 and M2 having same composition of 7091 alloy were used for starting powders. M1 was the mixture of AI-Zn-Co mother alloy, Al-Mg mother alloy, Al-Cu mother alloy and Al elemental powders. M2 was the mixture of Al-Co mother alloy, Zn, Mg and Cu elemental powders. The green compacts of the alloy powder and the M1, M2 powders were sintered 803-863 K for 1 h in N2. The sintered compacts were hot rolled and cold rolled, then were heat treated to T6 condition. Results obtained were as follows:
1) While the cracking of P/M sheets often occurred during hot rolling process when they were made from 7091 alloy powder and mixed powder M1. The cracking of the sheet from mixed powder M2 was not observed.
2) The highest UTS and elongation values of the P/M sheets rolled from sintered compacts in this study were about 590MPa and 11%, but these values were lower than those of the P/M sheets rolled from degassed and hot pressed compacts of 7091 alloy powder.
3) Hydrogen contents of the P/M sheets rolled from sintered compacts decreased with increasing the sintering temperature. And it was less than 2 p.p.m., for the sheets rolled from compacts sintered at 863 K.View full abstractDownload PDF (3540K) -
Kazuhiko Majima, Kyotaro Amafuji, Mitumasa Yamamoto, Hiroshi Nagai, Ke ...1990 Volume 37 Issue 3 Pages 451-455
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe relation between cationic mass fraction and the sputtering time in the passive film of Ti-4Fe specimen was investigated by ESCA compared with Ti-6Al-4V and Ti-5Al-2.5Fe specimens, where the specimens were held at 1.2 VSHE or 2.4 VSHE for 10 ks in the physiological saline solution.
When the specimens were held at 1.2 VSHE, it was observed that Al increased remarkably in the passive film of Ti-6Al-4V and Ti-5Al-2.5Fe specimens, while V and Fe decreased compared with their initial contents. The Fe content in the passive film of Ti-4Fe specimen, however, was confirmed to be nearly the same as the initial value.
The localized attack was observed on the surfaces of Ti-6Al-4V and Ti-5Al-2.5Fe specimens during kept at 2.4 VSHE, where the α phase has been preferentially attacked and Al content decreased in the localized attack region. However, the Ti-4Fe specimen was not attacked even in this case and showed the good corrosion resistance.View full abstractDownload PDF (2687K) -
Nobujiro Tsuchiya, Osamu Terada, Minoru Saito, Hisashi Suzuki1990 Volume 37 Issue 3 Pages 456-461
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSUsing reduced and carburized SKH57 powder, titanium nitride (TiN) and titanium carbide (TiC) powders, SKH57 tool steels having TiN or TiC in the amounts up to 25.27 vol% were sintered, HIP-ed and usually heat-treated. The mechanical properties such as hardness (Hv) and transverse-rupture strength were studied.
It was noted that M6C, MC and TiN particles were observed in the structure of TiN added steel, being in good contrast to MC and TiC solid solution particles in TiC added one. Then, the former steel was always higher in the hardness than the latter under the same amount of additions. It was found that SKH57 having, for instance, 17.30 vol% TiN showed the hardness of 1070-1130 Hv and the strength of about 2.5 GPa.View full abstractDownload PDF (6022K) -
Mitsuo Ueki, Kozo Kitamura, Hisashi Suzuki1990 Volume 37 Issue 3 Pages 462-465
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSome properties of TiC-20 vol%TiN-10 vol%Mo2C-10 vol%Ni alloys with additional TaC up to 22.5 vol% in exchange of TiC were investigated. With increase of the amount of additional TaC, the alloy showed the finer carbonitride structure which resulted in increase of the hardness of the alloy. In spite of the fine structure, high temperature mechanical properties were improved with additional TaC, leading to the superior cutting performance.View full abstractDownload PDF (1372K) -
Masakuni Ozawa, Mareo Kimura1990 Volume 37 Issue 3 Pages 466-473
Published: April 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe thermal stability of Ce added γ-Al2O3 was investigated in the temperature range up to 1200°C. The addition of Ce prevented the phase trasition of γ-Al2O3 to α-Al2O3 and improved the thermal stability of alumina at 1200°C. The surface area after being heated at 1200°C for 5 hours was 40 m2/g for 1 mol % Ce added alumina and 12 m2/g for pure alumina. The activation energy of the phase trasition had a constant value, about 580kJ/mol, regardless of the Ce addition. The isothermal transformation data at 1250°C were represented by the kinetic equation, X=1-exp{-K(t-t0)n}, where X is the fraction transformed, K is the rate constant, t is the time and n is the dimensionless time exponent. The sintering of alumina at 1000°C was due to the change of γ-Al2O3 to θ-Al2O3 with the volume diffusion and was not influenced by the Ce addition. The state of the added Ce was examined with electron spin resonance method using Gd as a probe, and was characterized by the fine CeO2 on alumina surface.View full abstractDownload PDF (2504K) -
Eiichi Sentoku, Mikito Kumagai, Yoshio Fujimura, Takeji Hachisuka1990 Volume 37 Issue 3 Pages 474-479
Published: April 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn recent years, many ceramic and cermet tools with various kinds of properties have appeared on the market. The purpose of this paper is to clarify the tool life of TiC-Cr3C2 compound ceramic tool on the prototype for the machining of carbon steel at high cutting speed. The tool life was studied and discussed upon both continuous and intermittent cutting by turning. The cutting speed for examination was 250m/min and 300m/min.
The results obtained are as follows;
(1) In continuous cutting, tool life of TiC-Cr3C2 compound ceramic tool was larger than those of cermet and ceramic tools.
(2) In intermittent cutting, the chamfer angle of 30°on the edge gives the longest tool life. In this case, the failure on the tool edge was caused by pile up of micro chipping.
(3) Since TiC-Cr3C2 compound ceramic tool shows good cutting performance to the carbon steel, the cermet tool will be replaced by this tool.View full abstractDownload PDF (4971K)
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