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Volume 33, Issue 5
Displaying 1-9 of 9 articles from this issue
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[in Japanese], [in Japanese], [in Japanese]1986 Volume 33 Issue 5 Pages 225-231
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (1537K) -
Kazutaka Makino, Masaharu Yamada, Akira Higashiyama, Kohtaro Kuramitsu1986 Volume 33 Issue 5 Pages 232-239
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe heterogeneity of powder bulk density formed in the compacted powder has a great influence on the mechanical strength and the dimension accuracy of the final product. However, the formation mechanism of powder bulk density distribution in the powder compact has not yet been sufficiently clear up to now. To elucidate the formation mechanism, the refraction phenomenon of loose bulk density zone through the interface between powders was investigated and discussed. And it was pointed out that the refraction condition between powders can be described by "the difference between the incidence angle aA and the refraction angle aB of a loose bulk density zone to and from the powder interface coincides with that between the internal friction angles φA (incidence) and φB (refraction) of powders." This condition was experimentally checked by X-ray radiograph of the refraction phenomena of loose bulk density zone produced in powder.View full abstractDownload PDF (3769K) -
Noboru Suzuki, Atsushi Endo, Hiroshi Utsugi1986 Volume 33 Issue 5 Pages 240-245
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe surface properties and the surface-treatments of zirconium boride and titanium boride with cetyl alcohol were investigated through X-ray photoelectron spectroscopy, X-ray diffractometry, scanning electron microscopy and pyrolysis. The followings were found: (1) The surfaces of borides were covered by oxide films. (2) The crystallographic structure of substrate, particle size and the shape or agglomeration of the particles were not affected by the surface-treatment. (3) The pyrolysis of the surface-treated borides has taken place in the temperature range of 300-500°C and the main pyrolysis product was perceived to be cetene. This trend is similar to the pyrolysis of the surface-treated ZrO2 and Ti02 with cetyl alcohol.
Accordingly, the surface-treatment of borides with alcohol was perceived to be performed by the dehydration-condensation of alcohol with the surface hydroxide of the oxide film formed on borides.View full abstractDownload PDF (1747K) -
Hiroshi Takigawa, Seiya Furuta, Kiyomi Ohe, Nobuyasu Kawai, Kazuo Ogat ...1986 Volume 33 Issue 5 Pages 246-250
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe fatigue properties of P/M superalloys can be significantly damaged by defects, which act as sites for fatigue fracture initiation. These defects can be introduced as inclusions either during the melting operation, during powder atomization or during subsequent handling.
Equipments for producing cleaner powders by Ar gas atomization have been designed and installed, and the properties of produced MERL76 superalloy powders were examined. As a result, this method was capable of producing fine and clean powders with an average grain size of 56 μm and an oxygen content of less than 100 ppm. Results also indicated that the amount of non-metallic inclusions of produced powders was less than those in the commercialized powders, which was detected by the new water elutriation method.View full abstractDownload PDF (2828K) -
Hiroshi Takigawa, Kenji Iwai, Nobuyasu Kawai, Toshinori Yokomaku1986 Volume 33 Issue 5 Pages 251-256
Published: July 25, 1986
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe mechanical properties of powder Ni-base superalloy consolidated by HIP were obtained for AF 115, MERL76 and Mod. IN100, where the influence of powder handling atmosphere upon the low cycle fatigue life of the consolidated materials was investigated in order to establish the powder consolidation process. Moreover, the differences of mechanical properties between HIPed material and conventional casted one were examined. The results obtained are as follows :
1) In order to get a confidence of low cycle fatigue life, the powders should be handled in the protected atmosphere such as Ar gas or vacuum.
2) Powder consolidation process making use of HIP equipment was established and made it possible for the HIPed materials to possess the satisfactory mechanical properties.
3) Low cycle fatigue life and tensile properties of HIPed materials are much superior to those of conventionally casted ones. This is due to the nature of homogeneity and fine crystal structure of powder materials.
The stress rupture strength of the powder materials is, however, lower especially in the low stress region than that of casted one. This difference between them may be due to the crystal grain size.View full abstractDownload PDF (3692K) -
Toshihiko Nishida, Nobuyuki Yoshifuji, Tomozo Nishikawa1986 Volume 33 Issue 5 Pages 257-261
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical properties and chemical corrosion behavior of two kinds of polycrystalline MgO normally sintered without additives (MG-S) and with SiO2, CaO additives (MG-12) were studied. Effective fracture energy (γeff) measured by "Work of Fracture" technique increased from about 30 J/m2 at room temperature to about 60 J/m2 at 800°C for both MG-S and MG-12, and the values were nearly constant of 60J/m2 Up to 1450°C for MG-S. γeff decreased gradually, however, with increasing temperature to about 30 J/m2 at 1450°C for MG-12 showing the fractured surface change from transgranular to intergranular one, and also large internal friction with relaxation of Young's modulus measured by sonic resonance technique was observed at 900°C, which must have resulted from an elasticity of grain boundary glassy phase. On the other hand, MG-12 showed poor corrosion resistance as a result of static immersion test in K2CO3 molten salt. The microscopic observation after treatment at 1000°C showed the polycrystal affected at the grain boundary concentrically.View full abstractDownload PDF (2648K) -
Hisashi Suzuki, Hideaki Matsubara, Noritoshi Horie1986 Volume 33 Issue 5 Pages 262-269
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe diamond deposition on WC-Co alloy substrate was studied using so-called hot-filament method, according to the depositing conditions previously published. To clarify the phenomena, model experiments using the substrate of coarse WC-10%Co alloy, the surfaces of which were treated in different ways, were mainly conducted.
The substrate temperature from 1073 to 1223 K was needed for the diamond deposition. The number of diamond particles increased, when the substrate surface was scratched, and it further increased when the surface was etched to some extent to remove the binder after the scratching. As for the etched substrate, diamonds deposited after several minutes of reaction time at the edge of WC particles or at the edge of scratches on the particles. The incubation period for diamond deposition was clearly observed for the non-etched substrate. The carbon absorption of binder and the graphite formation on binder during reacting were confirmed. It was demonstrated that the adhesion between diamond and substrate for the etched substrate was sufficient enough, in good contrast to the case of non-etched substrate. The mechanism of adhesion mentioned above was described.View full abstractDownload PDF (7099K) -
Koji Hayashi, Yoshihiro Onomura1986 Volume 33 Issue 5 Pages 270-273
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe room temperature transverse-rupture strength of Si3N4-10 mol%MgO-5.5 mol%A1203 ceramics was investigated in relation to the heating rate (0.07-0.33 Ks-1) during sintering, considering the effects of impurity carbon (about 1, 4 mol%) in Si3N4 powder and additional SiO2 (0-3 mol%).
It was found that the strength dependency on heating rate was largely affected by the carbon content in Si3N4 powder; the strength considerably decreased with decreasing heating rate in the case of Si3N4 powder with 4 mol% carbon, but it hardly changed with heating rate in the case of Si3N4 powder with 1 mol% carbon. The result was discussed on the basis of weight loss of specimens during sintering, carbon content of sintered specimens, microstructural defect which acted as a fracture source, etc.View full abstractDownload PDF (1457K) -
Nobujiro Tuchiya, Osamu Terada, Koji Hayashi1986 Volume 33 Issue 5 Pages 274-279
Published: July 25, 1986
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe microstructure of deposited layer in TiC-Mo2C-Ni cermet which was CVD-coated with titanium carbide under the nearly same conditions as in the case of the coating of WC-Co cemented carbides, in particular the microstructure of the phases containing Ni which was incorporated into the layer, was investigated.
It was made clear that the Ni incorporated in the layer existed in the form of NiTi and Ni3Ti compounds. The micropores were formed in both the coated layer and the substrate near the interface, accompanied with the formation of those compounds. The incorporation of Ni or the formation of the compounds in the layer would be understood by taking into consideration the fact that the carbon content of titanium carbide deposited on TiC-Mo2C-Ni cermet was much lower than the stoichiometric value, and also by assuming that the compounds were relatively unstable.View full abstractDownload PDF (4472K)
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