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Volume 25, Issue 8
Displaying 1-15 of 15 articles from this issue
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Takeshi Kameoka, Takashi Kimura1978 Volume 25 Issue 8 Pages 249-253
Published: December 25, 1978
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe role of liquid phase and pressure on the densification mechanism of hot pressing of iron-carbon alloys in the presence of liquid phase was clarified and also a strengthening of the alloys was investigated. With an increase of the sintering temperature, both sintering of iron powder and diffusion of carbon into iron powder occurred simultaneously and then densification proceeded by an easy movement of solid phase under a constant pressure of 10 kg/cm2 in the presence of liquid phase above the solidus line.
After cooling, the bending strength of Fe-2%C alloy was decreased by the presence of cementite network. The alloys were strengthened by annealing at 1100°C for 3 hrs in a vacuum or by addition of 3%Cu or Ni. An Fe-3%Ni-1.7%C alloy made by this process provided a bending strength of 280 kg/mm2.View full abstractDownload PDF (4013K) -
N. Kawai, H. Takigawa, M. Ishi, S. Furuta, Y. Inoue1978 Volume 25 Issue 8 Pages 254-257
Published: December 25, 1978
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFor establishing an optimum HIP condition to obtain high productivity, changes in density and bending strength were studied relating to various HIP conditions.
The results were summarized as follows :
1) The combination of 1100°C, 400 kg/cm2, and 30 minutes is enough for obtaining the theoretical density, and that of 1200°C, 400 kg/cm2, and 30 minutes is enough for reaching a saturation in bending strength.
2) The bending strength can be approximately expressed as a function of only the density.
3) The pressure plays a fundamental part of densification caused by plastic and creep deformation especially at the lower density region. The temperature is important for increasing diffusion to densify and to improve strength, especially near the theoretical density region, as well as for assisting the role of pressure by decreasing deformation resistance. The holding time is instrumental in the progress of creep and in the completion of sintering.View full abstractDownload PDF (1337K) -
Minoru Hirano, Katsumi Tsuji, Katsuhiko Honma, Hirofumi Fujimoto, Tsun ...1978 Volume 25 Issue 8 Pages 258-261
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn order to improve toughness and wear resistance of high speed steels, P/M high C high V high speed steels were investigated in this experiment. Modified SKH55 steel powders containing 1.08 to 3.56%C and 2.25 to 11.97%V were consolidated using hot isostatic press. It was found that a P/M steel containing under 10%V has transverse rupture strength of more than 350 kg/mm2. The wear characteristics of P/M steels were examined, rubbed against SNCM8, with the plate-disc type machine under unlubricated conditions. P/M high C high V high speed steels were found to have an excellent wear resistance. At 2.86 m/sec of sliding speed (adhesive wear zone), the wear rate decreased with increasing carbide content. While at 0.3m/sec of sliding speed (abrasive wear zone), the wear rate decreased linearly with increasing MC carbide content.View full abstractDownload PDF (3041K) -
Yasushi Shimanuki, Yoshio Nishino, Mitsuyoshi Masui, Hidekazu Doi1978 Volume 25 Issue 8 Pages 262-267
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffects of heat-treatments on microstructure of PAM René 95 consolidated by the hot-isostatic pressing (HIP) were examined in some detail. Microstructure of as-HIP'd specimen was characterized by highly serrated grain boundaries. It was clarified that such serrated grain boundaries were formed during slow cooling from HIP temperature across the γ′ solvus temperature. Grain boundaries were found to become smooth when the specimen was quenched from temperatures above the γ′ solvus temperature. Mechanical tests and microstructural observations revealed that the serrated grain boundaries improved ductility at both room- and elevated-temperatures by retarding crack propagation along grain boundaries. The creep properties of HIP'd and heat-treated specimens which contained serrated grain boundaries were found to be superior to the properties of cast +wrought material.View full abstractDownload PDF (6442K) -
Shigeharu Naka, Shin-ichi Hirano, Kazuaki Shimono, Yasuo Takeda1978 Volume 25 Issue 8 Pages 268-271
Published: December 25, 1978
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSGlassy carbon preheated at 2000°C was exposed under 90 kb and 65 kb at high temperatures in order to elucidate the processes of the graphitization and the formation of diamond from the carbon with the characteristic bond nature under high pressure and temperature conditions. In the present work, the process of the diamond formation as the stable phase was followed by the X-ray diffraction method and the scanning electron microscopic observation. The diamond well developed with the {111} face was found to form on a graphite grain, which had been grown as a meta-stable phase under high pressures and temperatures.View full abstractDownload PDF (1243K) -
Tosikazu Sakai1978 Volume 25 Issue 8 Pages 272-274
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of oxygen composition on the crystal phases and flexural strength of AIN hot-pressed under 200 kg/cm2 for one hour at 1600-2100°C was examined. The A1N pseudo-polytype in 2Hδ structure was formed in the specimens hot-pressed at temperatures above 1900°C containing about 2.7 wt% oxygen. In these experiments, specimens from the powder with 2.7 wt% oxygen (97.6 mol% A1N) had the highest strength of 48 kg/mm2. The oxygen addition enhances densification and increases flexural strength because of forming spinel-type aluminum oxynitride and/or needle-shaped pseudo-polytypes in the grain boundary of A1N. The excess formation of the pseudo-polytype, however, seemed to be undesirable in the attainment of strong material.View full abstractDownload PDF (223K) -
Masahiko Shimada, Noriyuki Ogawa, Mitsue Koizumi1978 Volume 25 Issue 8 Pages 275-276
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHigh pressure sintering of pure materials of AlN, α-Si3N4 and TiC without additives was carried out at 800-1400°C under the pressures of 30 kbar and 50 kbar for 0.5 hr. The maximum density of sintered bodies for the above materials was nearly 100% for AlN, 9800 for TiC and 96% for α-Si3N4.View full abstractDownload PDF (144K) -
Tadahiko Watanabe, Kenji Ishibai1978 Volume 25 Issue 8 Pages 277-282
Published: December 25, 1978
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThis paper describes the effects of sintering conditions such as atmosphere, temperature, amount of Ni·P binder, sintering pressure and time on the mechanical properties of the product of TiB2-Ni·P alloys.
1) In the case of sintering in the air nitrogen and, oxygen in the air react with TiB2 and Ni·P to produce TiB2, TiN, TiBO3, BN, Ni4B3, Ni2P and NiP2. It is thought that these TiN, Ti2O3 and BN decrease the bending strength and the hardness of the alloy sintered in the air.
2) The alloy sintered at 1300-1500°C in a vacuum has a strong bending strength. One of the reasons is that TiB2 or the surface layer TiBO3 of TiB2 particle combines with Ni4B3. These TiB2 or TiBO3 becomes the surface of TiB2 particle from 1200-1300°C and so TiB2-Ni·P is rapidly sintered in this range.
3) The strongest bending strength of 85kg/mm2 and the hardness of Hυ1560kg/mm2 were obtained by the TiB2-12%Ni·P alloy sintered at 1400°C under a die pressure of 115kg/cm2 for 14 min in a vaccum.View full abstractDownload PDF (2673K) -
Yoshio Fujiwara, Fumihiro Ueda, Takeshi Itaba1978 Volume 25 Issue 8 Pages 283-286
Published: December 25, 1978
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSVarious mechanical properties of hot isostatic pressed WC-Co alloy were investigated and compared with those of conventionally sintered alloy. The results obtained are as follows: (1) Transverse rupture strength and fatigue strength at room temperature of hot isostatic pressed alloys become remarkably larger than those of conventionally sintered alloy. (2) The effect of HIP treatment on transverse rupture strength decreases gradually with the rise of temperature. As a reult of this tendency, trnasverse rupture strength of WC-10%Co alloy at high temperatures above 900°C becomes to be unaffected with HIP treatment. (3) Fracture toughness (KIC) is unaffected with HIP treatment.View full abstractDownload PDF (1233K) -
Toshio Ogawa, Kiichi Minai, Kikuo Wakino1978 Volume 25 Issue 8 Pages 287-291
Published: December 25, 1978
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSPhysical and electrical properties of Pb(SnaSb1-a)O3 ceramics are described. Pb(Sr Sbt1-a)O3 compound has a cubic pyrochlore type structure represented by the formula Pb2Sn2aSb2-2aO7-a (1/8<a<2/3). The relative intensity of X-ray diffraction lines fitted well with the calculated one when the crystal structure of Pb(SnaSb1-a)O3 was assumed to have the pyrochlore type structure.
The ceramics formed under the hot pressing condition had high density and its microstructure was composed of a mixture of fine grains (1-2μ) and coarse grains (-10μ).
Electrical resistivity of a hot pressed sample (a= 1/2) greatly changed its original value after annealing in oxygen gas.View full abstractDownload PDF (3482K) -
Mitsuhiro Takata1978 Volume 25 Issue 8 Pages 292-294
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt has been tried to densify PbTiO3-PbZrO3-Pb(Zn, Nb)O3 piezoelectric ceramics by hot isostatic press(HIP)method.
Specimens were set in the chamber of HIP equipment without any sealed containers and sintered at atcmperature of 900-1200°C under a pressure of 170-1600 kg/cm2 in incrt gas atmospheres. Since the working gas was pure argon or nitrogen gas, the deoxidizing phenomenon was inevitable for some specimens in apart ofabatch. This phenomenon was easily observed by the change in color and the decrease ofelectrical resistivity. These deoxidized specimens were able to show the recovery by heat treatment at a temperatureof 800-1000°C in oxygen atmosphere. Isostatically hot pressed ceramics showed no defect on polished surface, the equivalent piezoelectric properties and a mechanical strength about 20% higher than that of thenormally sintered materials with a density of 97%.View full abstractDownload PDF (1109K) -
Eizo Takama1978 Volume 25 Issue 8 Pages 295-297
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt has been investigated to densify manganese-zinc ferrite for magnetic heads by the hot isostatic press (HIP) method. The sintering process consists of a conventional presintering and a HIP at high gas pressure. It is necessary for the densification of ferrites by non-encapsulating HIP to make the density of ferrites more than 95% of the theoretical value in presintering process. Ferrites with uniform grain size are obtained by controlling grain growth in the process of HIP.View full abstractDownload PDF (1238K) -
Tadashi Shinohara, Shiro Murakami, Tsutomu Iimura1978 Volume 25 Issue 8 Pages 298-301
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe preparation of high density MnZn ferrite by hot isostatic press (HIP) is investigated.
The procedures contain the first sintering, hot isostatic press (at 1200°C) and annealing, and the porosity of this HIP ferrite is less than 0.2%. Densification mechanism maybe grain growth and compression of pore by isostatic pressure. Magnetic characteristics of HIP ferrite are those of IIMHz: 1800, μ5MHz: 1040, Bio: 5000G, Hc: 0.06Oe and Tc: 220°C.
This ferrite will be suitable for high density recording magnetic head materials.View full abstractDownload PDF (1250K) -
Tsutomu Iimura, Shiro Murakami, Tadashi Shinohara1978 Volume 25 Issue 8 Pages 302-306
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPreparation of the high dense Ni-Zn ferrite were investigated by the hot isostatic pressing. Results obtained were as follows:
The density of specimens after hot isostatic pressing was above 99.8%i but the transverse-rupture strength were decreased to the half value compared to normally sintered ferrite. It was found that lowering of transverse-rupture strength results from fracture of grain boundary which is considered to be due to reduction of grain boundary in hot isostatic pressing.
When the isostatic pressed ferrite was annealed at 1100°C for 3 h in air, the magnetic properties and the hardness of grain boundary clearly recovered up to those of normally sintered ferrite.View full abstractDownload PDF (3876K) -
Eiichi Hirota, Ken Hirota, Mitsuo Satomi, Tomozo Nishikawa1978 Volume 25 Issue 8 Pages 307-310
Published: December 25, 1978
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMaking processes of a spinel-ferrite having a cube-texture were studied with examining (i) an anisotropic grain-orientation of raw-material powders informing process and (ii) a topotactic reaction in hot-press sintering. Followings are described, 1) fabrication of raw-material, a-FeOOH and y-MnOOH, having a large and well-defined shape, 2) observation of powder-orientation in forming process by SEM, 3) decomposition, ferrite-formation and orientation of ferrite powders in hot-press sintering, and 4) measurements of grain orientation by X-ray analysis. In this study, a hot-pressed Mn-ferrite having 72% orientation of <110>-axis and 58% of <111>-axis was obtained.View full abstractDownload PDF (2883K)
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