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Volume 15, Issue 7
Displaying 1-9 of 9 articles from this issue
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[in Japanese]1968 Volume 15 Issue 7 Pages 329-340
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
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1968 Volume 15 Issue 7 Pages 340a
Published: 1968
Released on J-STAGE: May 22, 2009
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1968 Volume 15 Issue 7 Pages 340b
Published: 1968
Released on J-STAGE: May 22, 2009
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[in Japanese]1968 Volume 15 Issue 7 Pages 341-350
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
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Shunjiro Saito1968 Volume 15 Issue 7 Pages 351-355
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHydrothermal treatment at 300°C of either Mg-Fe coprecipitate or hydroxide mixture does not yield magnesium ferrite, which however, was found to occur by the addition of small amount of hydrogen chloride under the same conditions.
This could be interpreted in terms of the formation of basic magnesium chloride as an intermediate, which takes part in the acceleration of magnesium ferrite formation.View full abstractDownload PDF (3908K) -
Akio Hara, Shuji Yazu1968 Volume 15 Issue 7 Pages 356-362
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt has been required to determine precise mechanical and physical properties of cemented carbides for their extensive applications. This paper presents the results of fatigue tests on several WC-Co cemented carbides. It is generally recognized that the data of fatigue test on hard materials are widely scattered, consequently, it is desirable to represent them statistically. The present authors obtained the most probable S-N equations and computed the S-N-P (P: probability of fracture) curves for each WC-Co cemented carbide. The observation of the fracture surface, coercive force measurement and X-ray diffraction study were made in order to study the fatigue mechanism and the results are briefly discussed.View full abstractDownload PDF (3900K) -
Hisashi Suzuki, Kozi Hayashi, Akio Hara1968 Volume 15 Issue 7 Pages 363-368
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSProperties of WC-TiC-10% Co and β-10%Co alloys containing up to 20 mol% of various carbides, i.e., V4C3, Cr3C2, ZrC, NbC, Mo2C and TaC were studied at room temperature.
The results are as follows:(1) Grain size of the β-phase in β-10%Co alloy is increased by addition of Cr3C2 and V4C3, and is reduced by ZrC, NbC and TaC. Heterogeneous β-phase appears as the amount of ZrC increases. (2) The lattice parameters of β'-phase, i.e., carbide containing β-phase, increase with increasing ZrC, NbC and TaC but decrease sharply with addition of Cr3C2, V4C3 and Mo2C. (3) A large amount of Cr3C2 dissolves into the binder phase, but the other carbides are almost insoluble. (4) The hardness of the alloys is increased by ZrC and reduced by Cr3C2. (5) The strength of the alloys, which is higher in Ni binder than in' Co binder, is decreased remarkably by adding V4C3, Cr3C2 and ZrC, and is improved by Mo2C, NbC and TaC. The strength of the three phase (WC-β-γ) alloys is associated with that of two phase (β-7) alloys, suggesting that the strength of two or three phase alloy is controlled by that of β-phase or of β/γ interface.View full abstractDownload PDF (1857K) -
Hisashi Suzuki, Kozi Hayashi1968 Volume 15 Issue 7 Pages 369-371
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFor developing the high strength WC-10%Co sintered alloy, coarse grained alloys were sintered in vacuum in various manufacturing processes. The grain size was kept constant (2-3μ) in all specimens, because it is well known that the strength of WC-10%Co alloy should reach a maximum around these grain sizes. The transverse-rupture strength was determined on 20 specimens in each alloy system according to ASTM-B406-64.
The results are as follows: The strength of the alloy depends on the carbon content, contiguity, and so forth, even if no micro pore is present in the structure. Under the optimum conditions, the high and low carbon alloys showed the average transverse-rupture strengths of about 350 and 370kg/mm2, respectively. Therefore, it was confirmed that the strength of such a high strength alloy is affected by the carbon content, as already pointed out by the present authors for the ordinary alloys.
It must be mentioned however, that the true strength would be lower than that obtained actually, taking account for the effect of planar loading resulted from the deformation of the surface at which the load was applied on the specimen.View full abstractDownload PDF (269K) -
Katsuya Kudaka, Eiichi Nakase1968 Volume 15 Issue 7 Pages 372-374
Published: December 25, 1968
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSRaw material (5.5μ) and crushed (1.2μ) powders of titanium hydride were mixed with graphite powder and heated at temperatures up to 1600°C in vacuum (10-5 Torr).
Particle size was the only factor governing the rate of carbide formation, provided that the reaction is thermodynamically favorable. It is shown that the adsorbed water was released above 100°C, that titanium hydride is dehydrogenated at 200-700°C, and that titanium carbide is formed from metallic titanium and carbon in solid state above 700°C, accompanied by the formation of carbon monoxide above 1200°C.
The oxygen content increases with decreasing particle size of the raw material. However, the difference in oxygen content due to particle size was found to decrease and disappear from 400°C to 700°C. Oxygen content increased again above 800°C and was proportional to the surface area of the sample powder. It was shown that the higher the reaction temperature, the more increases the combined carbon in the synthetized titanium carbide.View full abstractDownload PDF (201K)
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