All issues
Volume 44, Issue 3
Displaying 1-17 of 17 articles from this issue
- |<
- <
- 1
- >
- >|
-
[in Japanese]1997 Volume 44 Issue 3 Pages 216
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (86K) -
Masanobu Sugimori, Jing-Feng Li, Yoshimasa Kobayashi, Akira Kawasaki, ...1997 Volume 44 Issue 3 Pages 217-221
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe purpose of the present study was to synthesize SiC-AlN ceramic alloy powders (solid-solutions and their composites) by the reaction sintering of the mixed powders of Si, C and Al in a N2 atmosphere. This present process, which employs the direct reactions between the constituent elements in the SiC-AlN system, was revealed to be effective for the powder preparation in the SiC-AlN system. The reaction was found to occur significantly above 1073 K with preferential formation of AlN and followed by SiC at higher temperature. Although Si3N4 was also formed due to the reaction between Si and N2 during the reaction sintering, its formation can be avoided by conducting the 2-step reaction sintering; first in N2 gas containing 10%H2 at 1073 K and subsequently in Ar gas at 1773 K. Such a process resulted in a porous product compact of SiC-AlN alloys without other phases, which can be simply pulverized to powder. X-ray diffraction showed that solid solutions were formed in the powder state although the extent of solid solution formation was not clarified. The synthesized powder was further densified by hot-isostatic pressing (HIP) at 2123 K and 200 MPa for 2 h, and the mechanical properties, such as microreaders, strength and fracture toughness, were investigated.View full abstractDownload PDF (4578K) -
Kiyokata Iizumi, Gaku Shikata, Katsuya Kudaka, Shigeru Okada1997 Volume 44 Issue 3 Pages 222-226
Published: March 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSCr1-xMoxB2 ceramics were manufactured by hot-pressing at the temperatures between 1600 and 1900°C. CrB2, Mo and amorphous boron powders were mixed in selected ratios. The ceramics were characterized by lattice constants, density and hardness.
The X-ray diffraction data showed that the molybdenum solubility x into the ceramics is about 0.6 at the temperatures of 1600-1800°C and increases to about 0.8 at 1900°C. Apparent density of the ceramics increased as molybdenum content and hot-pressing temperature increased. SEM observations showed that boride grains in the ceramics grows rapidly over the hot-pressing temperature of 1800 °C . Vickers hardness of the ceramics is a function of hot-pressing temperature and molybdenum content, and reached maximum value of 26.5GPa at 1700°C and x=0.6.View full abstractDownload PDF (2778K) -
A Study of Cutting ModelEiichi Sentoku, Hiroshi Tanaka, Hiroshi Kawabata1997 Volume 44 Issue 3 Pages 227-231
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn recent years, many ceramics have been to developed for the uses. Some ceramics for mechanical or electronic parts are required to be cut as the green compact. The cutting of the green compact is decreased cracks on the machined surface. The purpose of the paper is to clarify the mechanism at cutting of green compact. The cutting mechanism is investigated and discussed from the results of the fracture test by a new type testing machine and of the cutting test by a lathe. In the cutting test, the radius of cutting edge were varied from 0.8mm to 4mm. A fracture model is proposed from AE(Acoustic Emission) signal caused by fracture and SEM image of fracture surface. The main results obtained are as follows; (1) AE signal shows there stages of fracturing the green compact. (2) The fracture energy is from 4 J/m2 to 7 J/m2. (3) A fracture model is available to clarify the cutting mechanism. (4) The tool with large side cutting edge angle is able to cut a work at high efficiency and to elongate the tool life.View full abstractDownload PDF (2629K) -
Narikazu Sashida, Tatsuya Shiogai, Keizou Tsukamoto, Yoshikazu Inoue1997 Volume 44 Issue 3 Pages 232-235
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSintering of the Sialon ceramics accompanied with decomposition of surface layer (i.s. SiO2) and Sialon itself. These decompositions are impossible to completely be restrain the decomposition, and give influence to the chemical composition, microstructure and crystal phase of the Sialon. The decompositions are influenced by sintering condition, especially temperature and pressure of nitrogen. In this paper, the influence of the decompositions to mechanical property (strength and toughness) of Sialon was studied. The oxygen content of raw material and sintering condition (nitrogen pressure) were changed to examine influence of decomposition. The results obtained were as follows, when oxygen content of raw material was small amount and the nitrogen pressure in temperature rising was low, the mechanical property of Sialon was high. This indicates that the decompositions of surface oxide layer of Sialon particle improves mechanical property of Sialon. The possibility of controlling decomposition of Sialon by sintering condition was found.View full abstractDownload PDF (1367K) -
Yoichi Ishida, Noboru Miyata, Tatsuya Shiogai, Shigeru Aoki1997 Volume 44 Issue 3 Pages 236-240
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe effect of microstructure of silicon nitride on dynamic fracture toughness (KId) measured by one-point-bending impact test method was investigated. The specimens were sintered in the temperature range of 1823K to 2073K in N2 atmosphere, followed by hot isostatic pressing (HIPing) . Pressureless sintered (P.L.S.) silicon nitride was increased in density with sintering temperature. HIPed silicon nitride showed almost full density (3.26 X 10-3 kg/m3). In the case of P.L.S. silicon nitride, static fracture toughness (KIc) and dynamic fracture toughness (KId) have tendency to increase with sintering temperature. In HIPed silicon nitride, KIc had tendency to increase slightly with sintering temperature, but Kid was almost constant. Both silicon nitride was observed grain growth with sintering temperature which was observed by electron microscope, but the difference of microstructure between P.L.S. and HIPed silicon nitride was not observed. In the case of HIPed silicon nitride, we thought the following : specimen was broken along the grain boundary under the influence of grain size for static fracture, and specimen was broken abruptly without regard to particle and grain boundary for dynamic fracture.View full abstractDownload PDF (1428K) -
Kenji Nakahara, Kei Tokumoto, Shigeya Sakaguchi, Yasunori Hayashi1997 Volume 44 Issue 3 Pages 241-246
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe corrosion behavior of Ti-(0-40)mass%Mo alloys prepared through P/M technology was studied by corrosion test and electrochemical measurements. The corrosion rate of sintered Ti-Mo alloys in 35% HCl solution decreased remarkably with increasing molybdenum content. The corrosion rate of Ti-40mass%Mo alloy, for example, exhibited 5*10-3 [mm/year], which was 104 times lower than that of pure titanium. On the other hand, the corrosion rate in 3%NaCl solution wasn't affected by molybdenum content in alloys and was less than 10-3 [mm/Year].
Potentiodynamic polarization curves in 35%HCl solution showed that increasing molybdenum content caused the open circuit potential (corrosion potential) to be noble and the anodic current density to be low. It was thought that the presence of spontaneously passivated film in which molybdenum was enriched by preferential dissolution of titanium suppressed the anodic reaction and improved their corrosion resistance. On the other hand, potentiodynamic polarization curves in 3%NaCl solution revealed that increasing molybdenum content caused the open circuit potential to be base and the anodic current density to be high because molybdenum dissolved actively.View full abstractDownload PDF (1851K) -
Application of Infrared Radiation Heating Method to Evaluation of Thermal Shock Resistance of CermetTakashi Koyama, Kiyohiro Teruuchi, Teruyoshi Tanase, Mitsue Ogawa, Soo ...1997 Volume 44 Issue 3 Pages 247-252
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThermal shock resistance of cermets was tried to evaluate by the infrared radiation heating method that a thin circular disk is heated and fractured by infrared ray concentrated on the central area with a constant heat flux. Thermal shock fracture toughness R2c could be measured for specimens with an edge notch, while thermal shock strength R1c could not for the specimens without the notch. It was thought, however, that R2c might depend on radius of curvature of the edge notch. Using the data of R2c, thermal shock strength R1c was calculated from the consideration of stress concentration. As a result, it was considered that thermal shock strength R1c could be applied to evaluation of thermal shock resistance of cermet and thermal shock resistance of Ti(C, N)-Mo2C-Ni cermets increased with an increase in the content of nitrogen and Ni.View full abstractDownload PDF (1736K) -
Hideshi Miura, Yoshiaki Sakajiri, Mitsuharu Okada, Kenichi Takagi1997 Volume 44 Issue 3 Pages 253-256
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMetal injection molding (MIM) process has an advantage of fabricating three dimensional complex shaped components, which alleviates the need for secondary working operations. Therefore, MIM process is hoped to be a suitable production route for the hard materials such as cemented carbides. In this study, the effects of MIM processing variations on the mechanical properties and microstructures of WC-16, mass%., Co alloy were investigated. The results obtained were as follows:
(1) It was very difficult to debind completely and control the carbon content by using N2 gas as the thermal debinding atmosphere after solvent debinding.
(2) An adequate carbon level of the alloy was achieved by thermal debinding in H2 gas atmosphere, and the sintered alloys showed the finer microstructure and higher mechanical properties compared with those of coventional P/M alloys.View full abstractDownload PDF (3137K) -
Yutaka Yanaba, Koji Hayashi1997 Volume 44 Issue 3 Pages 257-262
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe kinetic energy (Ek) of flying fragments in three-point bending test of WC-10mass%Co cemented carbide was experimentally evaluated by our devised convenient method for a test piece with size of 4×3×36mm3 and a span of 30mm, and the ratio of Ek to the elastic strain energy (E ?? )which was stored in the test piece just before the fracture was calculated. It was found that Ek increased from 0.016J to 0.046J and the ratio of Ek/E ?? increased from 0.09 to 0.15 with increasing flexural strength (σm). It was suggested that the error due to Ek in the relative value of fracture toughness (KIc) estimated by using the equation of σm= ?? KIcSmf1/2 ( ?? is a factor including the shape of fracture source, the roughness of fracture surface and the correction parameter, etc., and Smf is the total macroscopic area of fracture surfaces of fragments of one test piece), in the derivation of which Ek is neglected, was +6.5%, if the effect of the other factors on the relative value of KIc are small.View full abstractDownload PDF (376K) -
Yutaka Yanaba, Koji Hayashi1997 Volume 44 Issue 3 Pages 263-268
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe heights of bending fracture surface of WC-10mass%Co cemented carbide were measured by using OM (optical microscope) and AFM (atomic force microscope) in order to estimate the one-dimensional roughness of the surface (RO and RA, respectively) and then the microscopic fracture surface area (Sif) and Sif/Smf term in our proposed equation of σm= ?? KICSmf1/2 (Smf ; macroscopic fracture surface area of one test piece, σm ; flexural strength, ?? ; shape factor including the ratio of Sif or true fracture surface area (Sif) to Smf, KIC; fracture toughness). Next, the value of γ+P (formation energy of fracture surface, γ; specific surface energy, P; specific plastic deformation work) in the prior equation of Vσm2/18E=(γ+P)Sif+Ek (V; volume of specimen, on which stress operates, E; Young's modulus, Ek; kinetic energy of flying fragments) was evaluated The results obtained were as follows;
1)The RO and RA were 1.27 and 1.43, respectively, and thus, ?? and Sif/Smf were calculated to be 317mm2 and 3.30, respectively.
2)The value of γ+P was estimated to be 6.7×10-4J/mm2.
3)The physical rationality of the equation of σm= ?? KICSmf1/2 should be examined furthermore by investigating the correctness of this value of γ+P or Sif and also the dissipatoin energy by vibration accompanied by crack propagation.View full abstractDownload PDF (3116K) -
Katsuya Uchino, Akihiko Ikegaya, Tsuhio Miyagawa, Hidenori Kaneta1997 Volume 44 Issue 3 Pages 269-274
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSPrevious studies have indicated that by coating steel in multiple layers with a cemented carbide alloy powder using the spark plasma sintering process, the thermal stress between steel and cemented carbide is eased and a composite material without cracking and peeling can be produced.
As an evaluation of the above material's wear resistance, a Blast Erosion Test as well as a High Pressure Water Erosion Wear Resistance Test were carried out. For the Blast Erosion Test, which is a good test of water of wear resistance relative to the hardness of the material, the composite material with residual stress and fine grain size, was shown to have excellent wear resistance. However, in the High Pressure Water Erosion Test, owing to the occurrence of cracks, this same material of low elasticity did not show superiority to any other materials.View full abstractDownload PDF (4320K) -
Keizo Kobayashi, Kimihiro Ozaki, Akira Sugiyama1997 Volume 44 Issue 3 Pages 275-279
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA spark plasma sintering(SPS) was applied to sintering and joining of ceramics, cermet and Ni alloy. Cermet was Ti75C25-20mass%Ni which was synthesized by mechanical alloying(MA) process of elemental powders of Ti, C and Ni. TiC, Ni, NiTi and NiTi2 are synthesized by exothermic reaction in heating from this MA powder. When the mixture of Ni powder and Al powder was used as Ni alloy, the joining at 1073K was able to be done in SPS process. However, Ni powder needs 1273K for the joining. This is because the interface of Ti75C25-20mass%Ni/Ni alloy is joined with the compound of Ti and Al. Although ZrO2 was joined with the cermet at more than 1073K in SPS process, the cracks were observed in the ZrO2 layer.
As the plasma in sintering was not observed in this study, the joining and sintering of ceramics/cermet/Ni alloy in SPS depends on the same principle as a hot pressing.View full abstractDownload PDF (3117K) -
O.H. Kwon, Yoshifumi Fukushima, Mitsuo Sugimoto, Nobuyuki Hiratsuka1997 Volume 44 Issue 3 Pages 283-287
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMeasurements are reported of the thermo-e. m. f. of a thermoelectric junction composed of polycrystalline ferrites or double-layered ferite films as a function of the temperature. Thethermo-e. m. f. of the bulk and ferrite films was much larger than that of the conventional thermoelectric junction made of metals. A positive or negative thermoelectric power was observed depending on the difference in the combination of ferrites. Application of a magnetic field had a reducing effect upon the thereto-e. m. f. at temperature of room to the curie temperature. The temperature dependence was almost linear from room temperature up to about 500°C and above which it showed a tendency to saturate. This may perhaps be due to the structual peculiarites of the ferrites.View full abstractDownload PDF (223K) -
Kiyotaka Kato, Akihiro Matsumoto, Kunisuke Ando, Tei Ieki1997 Volume 44 Issue 3 Pages 288-293
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn this paper, application of metal injection molding to FeAl intermetallic compounds and the properties of sintered FeAl compacts were described. The powder material was pre-alloyed powder(Fe-40at% Al) manufactured by SHS process, which had average particle size of 4.0μm. Consolidation process by sintering, microstructure and mechanical properties of sintered compacts were investigated. The results obtained in this study were summarized as follows:
(1) Relative density of the compact sintered at 1523K for 7.2ksec in vacuum(10°Pa order) was 94%. At this sintered condition, apparent porosity was almost zero. Raising sintering temperature to 1548K, relative density was improved to 99%.
(2) The sintered compact had the microstructure in which fine particles considered as aluminium oxide were dispersed in the matrix of single phase of B2(FeAl).
(3) The compact sintered at 1523K for 7.2ksec gave 0.2% proof stress of 340MPa, tensile strength of 630MPa and elongation of 3.4% at room temperature.View full abstractDownload PDF (5426K) -
Atsuko Kobayashi, Naoichi Yamamoto, Joseph Kirschvink1997 Volume 44 Issue 3 Pages 294-300
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFerromagnetic materials, magnetite crystals, have been extracted and identified from magnetotactic bacteria, polyplacophoran mollusks (chitons), salmons, tuna and recently tissues of the human brain. Ferritin, the iron storage nonheme-protein contains hydrated iron oxide (Fe2O3-nH2O) in its core. It is suggested that this hydrated oxide in ferritin would be the precursor of magnetite in both magnetotactic bacteria and the chitons. Many studies have described that ferritin were related with cell proliferation, specially tumor cell growth. In this study, we attempted to investigate the presence of magnetite in tumor tissues. We report the first detection of magnetic materials in various human tumor tissues (melanoma, breast, ovary, testicle, sarcoma, meninginoma, glioblastoma, astrocytoma, glioma, metastasis) with the use of SQUID magnetometry. The magnetometory data for the magnetic materials are consistent with magnetite (Fe3O4). Its concentration of various tissue types were measured via sIRMs. Tumor tissues were also stained blue with the Perls staining method for detecting ferritin. Our experiments show that the distribution of magnetite and ferritin in tumor tissues might depend on the etiology of the tumor. Ferritin distribution as indicated through staining suggest an irregular pattern with distinctive foci. However, a spacial covariance between ferritin and magnetite was unable to demonstrate in this study.View full abstractDownload PDF (3232K) -
Shigeya Sakaguchi, Kei Tokumoto1997 Volume 44 Issue 3 Pages 301-307
Published: March 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTi-Mo alloys have difficulties in manufacturing by melting-casting process because of its heavy gravitational segregation.
Sintered Ti-Mo and Ti-Mo-TiC alloys were developed by the powder metallurgical process, and their microstructures, mechanical properties and corrosion behaviors were investigated.
Ti-30mass%Mo alloy was consisted of β-Ti phase, its corrosion resistance in 35%HCI solution was far better than that of pure titanium, this was thought to be caused by the spontaneously passivated film, in which molybdenum was enriched by preferential dissolution of titanium, suppressing the anodic reaction.
Ti-Mo-(33 - 80) mass%TiC alloy had two phases of TiCx and β-Ti phases, and increasing the TiC content increased the hardness, and maximum hardness of HRC 66 was obtained in Ti-Mo-45mass%TiC alloy, but slightly decreased the transverse-rupture-strength. Its potentiodynamic curve revealed also same as that of Ti-30mass%Mo alloy. In conseqence of these results, this alloy was thought to have both wear resistance and corrosion resistance.View full abstractDownload PDF (1636K)
- |<
- <
- 1
- >
- >|