All issues
Volume 31, Issue 3
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Akira Chiba, Osamu Kimura1984 Volume 31 Issue 3 Pages 75-79
Published: April 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAn investigation has been made to elucidate the formation processes of manganese-zinc ferrites in the course of firing of raw materials by X-ray diffraction analysis and measurements of DTA as well as thermogravimetry. When Fe2O3, ZnO and MnO2 were used as the starting, materials, the formation of ZnMn2O4 proceeded preferentially at the early stage of firing in the range 580°-650°C.At temperatures, of 650° to 710°C, the reaction for the formation of ZnFe2O4 was mainly conducted. The solid state reaction occurred among the formed ZnMn2O4, ZnFe2O4 and remained Fe2O3 at 800°-1200°C, and the stoichiometric Mn1/2Zn1/2Fe2O4 was finally formed. It was also found that Mn3O4 is less reactive than MnO2, MnCO3 and Mn2O3 for the formation of ZnMn2O4 and that Mn3O4 alone affords, an another formation process.View full abstractDownload PDF (363K) -
Koji Hayashi, Masao Itabashi1984 Volume 31 Issue 3 Pages 80-82
Published: April 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe oxidation amount of TiH2 powder which was pulverized from 130 μm to 3μm by dry ball-milling and was left intact in the ball-milling pot was obtained by measuring the decrease in the pressure of air in the pot as a function of time.
The increase (ΔO2;%) in the oxygen content of TiH2 powder was calculated by the following equation; ΔO2??(Mv/mRT) (ΔP/760) ×100, where M is the molecular weight of oxygen, v is the volume of pot, m is the weight of TiH2 powder, R is the gas constant, T is the test temperature and ΔP is the decrease in the pressure [mmHg] of air due to oxidation in the pot. It was found that the oxidation of the TiH2 powder was not affected by the initial air pressure introduced into the pot in the range of 760-500 mmHg and it was fairly suppressed by the decreasing of test temperature and by the addition of solvents such as CH3 (CO) CH3, CCl4, CCl2F-CClF2, etc.View full abstractDownload PDF (228K) -
The Dimensional Change of Fe-Cu-B Based Sintered MaterialsTadao Hayasaka, Kazuo Asaka, Shigeru Ozawa1984 Volume 31 Issue 3 Pages 83-87
Published: April 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis report describes the results of our experiments on Fe-Cu-B based materials with regard to the dimensional change both during and after sintering, and the analysis of each phase of sintered compacts.
With the addition of no less than 0.03% of boron, Fe-Cu based materials show a shrinkage after sintering, and the maximum shrinkage with the addition of about 0.15% of boron. The dimension of sintered compacts contracts with an increase in copper content and rising in sintering temperature.
This is because the boron addition prevents the diffusion of copper into iron lattice and causes the occurrence of a liquid phase of Cu-B during sintering.View full abstractDownload PDF (2399K) -
(3rd report) The Preferable Conditions and Mechanism of Carbide FormationKanji Notomi, Seiya Furuta, Nobuyasu Kawai1984 Volume 31 Issue 3 Pages 88-93
Published: April 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA study has been made to reveal the preferable conditions for the variations of carbide morphology in HIP'ed roll steel pre-mixed with high chromium iron powder, and the mechanism of the variation has been discussed. High chromium gas atomized iron powder was mixed with gas atomized roll iron powder, followed by HIP'ing to a full density. The micro-hardness measurement, observation of microstructures and EPMA analysis were carried out.
The results are shown below:
(1) The region where high chromium iron powder existed transforms into massive carbides under the conditions where the chromium content of high chromium iron powder is 2.5% higher than that of roll iron powder, and a sufficient cementite or graphite exists in the roll iron powder.
(2) The mechanism of the variation of carbide morphology is explained in terms that the carbon consisting in cementite or graphite in the roll iron powder dissolves into matrix, and then precipitates into the carbides which existed in the high chromium iron powder.
(3) The type of the carbide which grows during HIP'ing depends on the chromium content of high chro-mium iron powder; cementite appears if the chromium content is less than 18%. (Cr, Fe)7C3 carbides also appears if the chromium content is more than 18%.View full abstractDownload PDF (3245K) -
Hisashi Suzuki, Hideaki Matsubara, Koji Hayashi, Kunio Shibuki1984 Volume 31 Issue 3 Pages 94-99
Published: April 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe transverse-rupture strength of HIP-treated WC-(5-20)%Co alloys coated with titanium nitride layer up to 514m by PVD process at 773K was mainly studied. The effect of annealing at 923-1273K on the strength of coated alloys was also studied.
The strength of coated alloys decreased generally with increasing thickness of coated layer; and the strength was lower as Co contents of alloys increased, excepting the case of 5%Co alloy. Decrease in the strength became markedly with decreasing Co contents, when coated alloys were annealed. At a fixed Co content and thickness of layer, the strength of coated alloys annealed at 1073-1273K was nearly the same, irrespective of annealing temperatures. The strength obtained after annealing was almost equal to that of coated alloy by CVD process (in this case, total thickness of coated layer and π-containing layer was regarded as the thickness of layer). The above phenomena concerning the strength of coated alloys could be clarified, based on the fact that fracture characteristics of coated alloy were substantially different between as PVD and annealea state, being in close relation to the fracture strength of coated layer.View full abstractDownload PDF (1812K) -
Effects of Grain Size of Powder and Testing Temperature on Deformation BehaviourKunio Okimoto, Tomio Sato1984 Volume 31 Issue 3 Pages 100-105
Published: April 25, 1984
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSForward extrusion of green compacts of 78zinc-22aluminium prealloy powder is carried out, and the deformation behaviour of the extruded body is stuaied by uniaxial tensile test. Effects of grain size and testing temperature cn deformation behaviour are also investigated. The results obtained are as follows:
1) Maximum value of 310% in total elongation of extruded green compact is obtained.
2) The optimum strain rate, at which a maximum total elongation is attained, increases as the grain and the particle size of powder become smaller.
3) As testing temperature increases, flow stress decreases remarkably and total elongation increases rapidly.
4) As in the case of wrought super-plastic materials, there is a good correlation between m value and total elongation of the powder compacts is a little inferior to that of the former.View full abstractDownload PDF (3921K)
- |<
- <
- 1
- >
- >|