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Volume 47, Issue 5
Displaying 1-20 of 20 articles from this issue
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Masato Kikukawa, Sigemasa Matsunaga, Tsuneta Inaba, Osamu Iwatsu, Tohr ...2000 Volume 47 Issue 5 Pages 453-457
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn order to obtain spherical fine powders, a new high-pressure water atomization method using swirl water jet was developed. In this paper the effects of jet swirl angle(ω)upon the properties of powders were investigated. Cu-10 mass%Sn alloy was atomized by this method at the constant water pressure of 83.3MPa and constant metal orifice diameter of 4mm, while ω was varied from 0 to 0.18rad.
Median diameter of the powder by the laser diffraction method(D50)decreased from 12.5μm to 7.5μm with increasing w, and this corresponded to Fisher average diameter(DFS)at about ω=0.18 rad. The apparent and tap density of the powder increased about 1 and 1.5Mg/m3 respectively, and the particle shape observed by SEM became spherical with increasing ω.View full abstractDownload PDF (3525K) -
Masao Kaneko, Hiroyoshi Komaba, Masato Imamura, Akira Yanagisawa2000 Volume 47 Issue 5 Pages 458-464
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAttempts were made to fabricate various stainless steel fibers by the hot water soluble resin coated coil shaving method, a new method of fabricating metal fibers. The stainless steel fibers obtained were then cut into a length of about 100mm, and overlapped these fibers in random combination to prepare a felt. The felt was sintered in a normal vacuum thermal processing furnace. Experiments were conducted to study the mechanical characteristics of the sintered product with the change in sintering conditions such as sintering temperature, holding time, compressive force, etc. The results confirmed that a 1.33 Pa (80PaN2 partial pressure) vacuum produces SUS304, SUS316L, and SUS430 stainless steel fiber sintered products above a tensile strength of 10MPa with the combination of the following sintering conditions; sintering temperature of 1323 to 1423 K, compressive force of 2 to 10 KPa, and holding time of 0.6 to 1.8 Ks.View full abstractDownload PDF (2920K) -
Hiroyuki Y. Suzuki, Kenji Shinozaki, Shunzo Tashima, Hidenori Kuroki2000 Volume 47 Issue 5 Pages 465-473
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSComplete pore elimination from alumina compacts is attempted under various sintering conditions. An alumina powder of purity of 99.99 % and grain size of 0.2 μm is used as a raw material, and it is mixed with ion-exchanged water of 25 mass%, dispersing agent of 0.6 mass% and binder of 0.1 mass% to prepare slip. Compacting process is executed under high centrifugal force of 10, 000-20, 000g. Dense and homogeneous green compacts are obtained and they are subsequently sintered in dry hydrogen, vacuum or HIPed.
Although vacuum sintering allows the specimen attains slight higher density than air-sintered specimen, some pores remain in the structure and the specimen doesn't show translucency. HIP treatment of air-sintered specimen, on the other hand, realizes almost pore free microstructure and the specimen shows translucency. HIPed specimen shows higher strength(four-point bending strength of 750 MPa)in comparison with commercial translucent alumina, but no remarkable improvement of strength is marked in comparison with air sintered alumina. HIPed specimen loses translucency after annealing in air because of the restore of transgranular pores. In-line transmittance of the HIPed specimen decreases as the wave length decreases.View full abstractDownload PDF (4363K) -
Teruo Ohashi, Shinsuke Tsutsui2000 Volume 47 Issue 5 Pages 474-479
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe sintering behavior and sintered microstructures of mechanically alloyed Fe-9.5mass%Cu-0.5mass%P system have been examined by dilatometric and density measurements as well as optical microsocpic and SEM observations. Started materials for mechanical alloying (MA) were reduced pure iron powder, water atomized pure copper powder and crushed Cu-14mass%P alloy powder. MA was performed in argon gas atmosphere by using a planetary ball mill. The change in the crystallite size of the powders with MA time almost finished for 36 ks and the yielded size was estimated to be about 10 nm. Dilatometric curves show that the sintering of the MA powders begins above the temperature of about 800 K and is promoted by increasing MA time and the addition of phosphor. Sintering of MA powders at 1073 K for 36 ks gave a consolidated alloy, the density of which is comparative to that of an atomized powder alloy sintered at 1473 K. The microstructure of the sintered MA powder alloy is composed of copper particles of a few micrometer in diameter distributed in the matrix the grain size of which is less than about 5μm.View full abstractDownload PDF (5488K) -
Roberto Martínez Sánchez, Francisco Espinosa Magañ ...2000 Volume 47 Issue 5 Pages 480-483
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSHigh purity cobalt and titanium powders were equiatomically mixed and mechanically alloyed. The microstructure and phase transformation occurred on the powder product during its densification using the spark plasma sintering SPS technique were analyzed. CoTi and CoTi2 intermetallic compounds formed after fast sintering. Although metastable CoTi2 undergoes partial CoTi transformation the lattice parameter and micro-Vickers hardness of these sintered compounds show high stability when annealing from 973 to 1273 K. The material thus prepared can be reliably used at these temperatures showing excellent mechanical behavior.View full abstractDownload PDF (5772K) -
[in Japanese]2000 Volume 47 Issue 5 Pages 486
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (98K) -
Keiichi Tsuda, Akihiko Ikegaya, Toshio Nomura2000 Volume 47 Issue 5 Pages 487-495
Published: May 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSA functionally graded material is a compound of two different materials with gradient composition. In addition to combining the characteristics of the two materials, this new material is intended to have distinct characteristics of its own that will allow new applications. This concept was applied to the field of hard materials. The developed material consists of a titanium based ceramic surface layer, a tough cemented carbide core containing carbonitride with 131 type and WC phases, and an intermediate layer with graded composition. The surface region is characterized by a high compressive residual stress of 0.8 GPa. In this material development, we investigated the cutting condition under which tools are easily damaged, and used a newly developed temperature distribution measurement method to identify the temperatures generated within the tool under those condition. We used the resulting temperature distribution data to perform CAE analysis in order to calculate the thermal stress generated by temperature distribution change. We confirmed the compressive residual stress of the developed material exceeds the calculated thermal stress. Compared to conventional cermet tools, the developed material tools improved thermal crack resistance, wear resistance and breakage resistance. Furthermore, its wear resistance and peeling resistance are superior to those of coated cemented carbides.View full abstractDownload PDF (10349K) -
Nobuaki Asada, Yoshiharu Yamamoto, Tadashi Igarashi, Yoshihiko Doi, Ko ...2000 Volume 47 Issue 5 Pages 496-501
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn the previous study, the authors have succeeded in synthesizing new mono-tungsten carbonitride, i.e., stoichiometric W(C, N) with 11-20at%N by heating W+C mixed powder in N2gas of high-pressure of 10-160MPa at 1523-1673 K and also W(C, N) with 5 at%N by heating W powder in CH4+NH3 mixed gas of normal-pressure at 1573K. In this study, we investigated the possibility of synthesizing MoN and Mo(C, N) by using the high-pressure-N2process. It was found that Mo(C, N) with N content of 14-25 at% could be synthesized at 25-160MPa, while MoN could not.View full abstractDownload PDF (2106K) -
Kazuhiko Tanaka, Koji Hayashi2000 Volume 47 Issue 5 Pages 502-506
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNew tungsten mono-carbonitride W(C, N) powder had already been found by the authors to be synthesized by the following two processes: (1) heating of W+C mixed powder in high-pressure N2gas of 10-160 MPa at 1523-1773 K and (2) heating of W powder in CH4+NH3 mixed gas of normal-pressure at 1373-1573 K. In this study, the synthesis of Mo(C, N) was tried by the latter normal-pressure process, i.e., by heating Mo + C mixed powder in NH3 gas (method I) and by heating Mo powder in CH4+NH3 mixed gas (method II). It was found that Mo(C, N) with nitrogen content of 17 at% could be synthesized by method II, at 33-67 NH3 vol% in the mixed gas. The nitrogen content was much larger than the 5 at% of W(C, N) by method II and it was within 14-25 at% which are the nitrogen contents of Mo(C, N) synthesized by the high-pressure-N2 process.View full abstractDownload PDF (4038K) -
Hideshi Miura, Yousuke Nishida, Yasunao Kai, Shigeya Sakaguchi2000 Volume 47 Issue 5 Pages 507-509
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAl2O3-TiC composite materials for cutting tool have been produced by the powder metallurgy process such as hot pressing and HIP. However, there are still problems in fabricating three dimensional complex shaped components. Powder injection molding (PIM) process may solve those problems because of the near net shape forming with complexity.
This study has been performed to determine the production feasibility of Al2O3-30mass%TiC composite materials by PIM process, and the mechanical properties and microstructures of them. Especially, the effects of binder loading and debinding and sintering conditions on the mechanical properties (hardness and transverse rupture strength) were investigated in detail. Finally, high performance Al2O3-30mass%TiC composite materials were obtained by the optimized PIM process.View full abstractDownload PDF (3250K) -
Minoru Fukunaga, Masahiro Machida, Keizo Kobayashi, Kimihiro Ozaki2000 Volume 47 Issue 5 Pages 510-514
Published: May 15, 2000
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe microstructure, mechanical properties and high temperature oxidation resistance of WC-10mass%(Fe65Al35) and WC-10mass%(Fe62.5A132.5B5) alloys were investigated. Fe65Al35 or Fe62.5A132.5B5 were synthesized by mechanical alloying (MA) for 540 ks of Fe and AI powders, or Fe, Al and B powders. The obtained MA powders and WC powder were mixed with organic solvent in the planetary ball mill. The mixtures were consolidated by pulsed current sintering process.
WC-10mass%(Fe62.5Al32.5B5) alloy has higher density and higher hardness than WC-10mass%(Fe65Al35) alloy. WC-10mass%(Fe62.5Al32.5B5) alloy containing 0.37 mass% of oxygen has transverse-rupture strength of 0.78 GPa, which is higher than twice of that of alloys containing 3.4mass% of oxygen.
The oxidization of the cemented carbides with FeAl binder phase in the air starts at higher temperature than that of conventional WC-Co alloy. Especially, WC-10mass%(Fe62.5Al32.5B5) alloy has excellent oxidization resistance at 1041 K.View full abstractDownload PDF (6048K) -
Particle Erosion and Microstructure of Fe-Cr-C Cermet Materials Prepared by Mechanical Alloying (MA)Kazuhiro Hasezaki, Noriyuki Hayashi, Masatomo Kamada, Setsuo Takaki2000 Volume 47 Issue 5 Pages 515-520
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMA powder of Fe-Cr-C was prepared by mechanical milling of powders of chromium, carbon and iron in an argon atmosphere for 200 h. MA compacts were hot-pressed at 1273 K for 3h. A uniform structure of a-phase and M23C6 with a diameter of approximately 1 mm was observed. Fe-Cr-C MA alloys were evaluated on erosive wear resistance using the centrifugal erosion apparatus. In particular, Fe-50mass% Cr-4.8mass% C alloy showed wear rate less than 1/5 of that of Mod. 9Cr-1Mo steel and showed high wear resistance at medium and high impingement angles.View full abstractDownload PDF (3765K) -
Yuji Yamasaki, Mari Yonetsu, Ken-ichi Takagi2000 Volume 47 Issue 5 Pages 521-525
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe liquid phase sintering mechanisms of Mo2NiB2 base hard alloys were studied for three alloy compositions. The MozNiB2 boride phase exhibited the orthorhombic or tetragonal crystal structure depending on alloy composition and processing temperature. The orthorhombic M3B2 (M: Mo, Ni) was formed by a solid state reaction prior to liquid phase formation associated with the quasi-eutectic reaction between the orthorhombic M3B2 and the Ni base metallic phase in a Mo-Ni-B alloy. Full densification was achieved by the quasi-eutectic liquid phase.
The orthorhombic M3B2 transformed to the tetragonal M3B2 with increasing temperature in the solid state for Cr and V containing Mo-Ni-B alloys, where Cr and V were mainly distributed in the M3B2 phase. The quasi-eutectic liquid phase also lead to full densification in these alloys.View full abstractDownload PDF (2291K) -
Satoshi Kinoshita, Takeshi Saito, Masaki Kobayashi, Koji Hayashi2000 Volume 47 Issue 5 Pages 526-533
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe developed a process for fabrication of new WC-Co base cemented carbides with highly oriented plate-like triangular prismatic WC grains. The characteristic of the fabrication process is that W +graphite mixed powder is used as the starting material for WC phase, instead of WC powder; the other fabrication conditions are the same as conventional ones. A large amount of triangular planes, i.e., (0001) crystal planes of WC grains in the sintered alloy were highly oriented vertically to the powder die-compaction direction. The new alloy showed generally higher fracture toughness and transverse-rupture strength than conventional alloy at an identical Co content, mean free path of binder phase or hardness, especially when the crack propagation direction is parallel or vertical to the powder diepressing direction.View full abstractDownload PDF (4034K) -
Toshiyuki Takahashi, Takeshi Saito, Masaki Kobayashi, Koji Hayashi2000 Volume 47 Issue 5 Pages 534-540
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe chemical reaction of A12O3-Ti(C, N) ceramics with Ni plate, which occurred by heating those couple at 1463 K, was investigated as a function of the N/(C+N) atomic ratio and amount of Ti(C, N). The followings were obtained: (1) Ni reacted only with Ti(C, N) grains in the ceramics, (2) Ni penetrated into the ceramics, dissolving a large part of Ti(C, N) grains, (3) the thickness of the Ni penetrated-layer, i.e., the chemical reaction-layer, decreased with increasing N/(C+N) atomic ratio and decreasing Ti(C, N) amount, (4) the relation between the thickness and the heating time was almost linear, and (5) the above result that the thickness decreased with increasing N/(C+N) atomic ratio was supposed to be the lower solubility and/or diffusion-rate of N atom in the penetrating-Ni phase than those of Ti and C atoms.View full abstractDownload PDF (4313K) -
Shuichi Imasato, Shigeya Sakaguchi, Kazumitu Sugano, Yasunori Hayashi2000 Volume 47 Issue 5 Pages 541-546
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe corrosion resistance of WC-Ni-Cr3C2 cemented carbides in acidic and neutral solutions had been shown to be improved at low carbon and high Cr3C2 content. Some remarkable peaks were observed in the polarization curves as the active dissolution, the passivation and over passivation regions, but they were not clear on what of the reactions cause.
In this report, WC-Ni-Cr3C2 cemented carbides were polarized and maintained at each potential in 3%NaCl + 0.1N H2S04 solution, and the partial polarization curves of W, Ni and Cr were calculated from the dissolved amounts of metallic elements in the test solution. The first peak in the vicinity of E ?? is due to the dissolution of Ni and Cr as binder metal. W starts to dissolve and an oxide or hydroxide film is formed as passivation film in this region. The reaction in the over passivation region is the dissolution of Ni, Cr, and W with the destruction and the disappearance of the passive film. The passivation film formed on low carbon content alloy has an excellent corrosion resistance at higher content of solid solution of W and Cr in the binder Ni phase.View full abstractDownload PDF (3717K) -
Kazuo Hamashima, Kimihiko Sato2000 Volume 47 Issue 5 Pages 547-552
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe overlay of boride cermet was fabricated on low carbon steel by plasma transfered arc welding with the composite powders made from MoB, Ni and so on. Dispersed boride ceramics were hardly found in the overlay alloy, when using agglomerated powder was used. On the other hand, the micro-structure consisted of dispersed Mo2NiB2 particles and Ni matrics were formed successfully, when semi-sintered powder was used.
Weight loss for abrasion and corrosion resistance for molten aluminum of the Mo2NiB2-Ni cermet overlay were examined. Its weight loss in abrasion test was one fifth of Cc alloy (Stelite #12), and its corrosion resistance was superior to the nitrided alloy steel extremely. However, this boride cermet is not so suitable to overlay alloy, because it is too difficult to control its microstructure of overlay.View full abstractDownload PDF (4738K) -
Tsutomu Yamamoto, Shinichi Kouno, Katsumi Miyatake2000 Volume 47 Issue 5 Pages 553-558
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThis study was carried out to easily evaluate thermal shock resistance of WC-Co based alloys at room temperature by YAG laser machining. Surface state and bending strength of the HIPed alloys with different Co content and WC grain size were investigated before and after introducing thermal cracks on the surface of the as-ground alloys by YAG laser machining which is considered to be similar to wire electric discharge machining (WEDM) in thermal shock.
The results obtained were as follows: (1) βWC1-x and W2C phases and also thermal cracks were observed on the laser-machined surface. The number of thermal cracks decreased with the increase of Co content in the alloy and it was fewer in micro grain alloy than in fine grain alloy. (2) Bending strength (σmG) before laser machining showed a maximum value in 12mass%Co alloy and it was larger in micro grain alloy than in fine grain alloy at the same Co content. On the other hand, the strength (σmL) after laser machining decreased with the decrease of Co content and remarkably decreased in micro grain alloy. (3) The strength ratio of σmL to σmG decreased with decreasing Co content and WC grain size, and also it showed a good correlation with the thermal shock damage resistance parameter of the alloy. The abovementioned results were almost the same as the cases of WEDM.View full abstractDownload PDF (5326K) -
Yutaka Yanaba, Koji Hayashi2000 Volume 47 Issue 5 Pages 559-563
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn the past study on the transverse-rupture strength (σm) of WC-10mass%Co hardmetal, the authors had derived an equation of σd-1=σ0-1+Kα1/2 (σd; the external stress which operated on the fracture origin at the moment of fracture, σ0; the intrinsic fracture strength, K; 2σ0-1ρ-1/2, ρ; the effective tip radius of microstructural defect which acted as the fracture origin, a; the half of the major-axis length of the fracture origin), and also had clarified that this equation holds on various kinds of hard materials. Furthermore, the slope value (K) of the σd-1-α1/2 regression line was suggested to have a correlation with the fracture toughness (KIC) in a similar way as the slope of σm-Smf1/2 regression line (Smf; total macroscopic fracture surface area of fragments). In this study, this suggestion was investigated on four kinds of hard or brittle materials such as high speed steel, WC-10mass%Co hardmetal, Si3N4 ceramics and Mn-Zn ferrite. It was found that the K has surely a strong correlation with KIC, and KIC can be expressed by an unified equation of KIC??0.7K-1.View full abstractDownload PDF (2843K) -
Keiich Tsuda, Akihiko Ikegaya, Tsugio Miyagawa, Yosifumi Suehiro2000 Volume 47 Issue 5 Pages 564-568
Published: May 15, 2000
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe have studied on Functionally Graded Material (FGM) which is composed of Cobalt- composition graded cemented carbide layers and a steel substrate. The graded cemented carbide powders stacked on steel were sinter-bonded by pulse-current resistance heating. We manufactured the desired structure and confirmed the stress relief, high bonding strength, and distribution of functionality of coated layers between the surface with high wear resistance and the inside with high toughness. We applied FGM to a stabilizer blade which is oil drilling tool. It was tested in the Ministry of International Trade and Industry's (MITI) Sanriku-oki well in Japan. The wear resistance of FGM blade was 20 times higher than conventional type of stabilizer in the MITI well. These results suggest that we might expect the new stabilizer to have high performance in deeper wells.View full abstractDownload PDF (6041K)
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