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Volume 41, Issue 1
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[in Japanese]1994 Volume 41 Issue 1 Pages 2
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (94K) -
Atsushi Fukawa1994 Volume 41 Issue 1 Pages 3-8
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSRecently, CVD-coated cemented carbides have become to be applied for milling tools as well as turning tools, and these tools are increasingly required to be more excellent in cutting performance. This paper is a summary of recent studies of the present author on the improvement of cutting performance of CVD-coated cemented carbides for milling tools, in close relation to the properties, such as composition and microstructure, etc., of cemented carbide substrates.View full abstractDownload PDF (3495K) -
Hideshi Miura, Hiroshi Gondou, Tadatoshi Honda1994 Volume 41 Issue 1 Pages 9-13
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn order to test the feasibility of using the MIM approach to attain the high performance high speed steels, many processing variances of molding, debinding, sintering and heat treatment conditions were investigated in this paper by using a gas atomized high speed steel powder. The results obtained are summarized and compared with a water atomized powder as follows;
For the debinding of gas atomized powder compounds, about 39% of the total binder weight was removed by solvent extraction for 14.4ks, which was larger than that of water atomized powder compounds(about 33%). This was mainly due to the powder characteristics, for example the shape and size of gas atomized powder were rounder and coarser than that of water atomized powder. Since the carbon content of gas atomized powder compacts was unchanged after sintering in pure N2, densification of the compact started at lower sintering temperature compared with water atomized powder compacts. Sintered microstructures of gas atomized powder compacts showed a little coarse and angular carbides precipitated in the matrix.View full abstractDownload PDF (6775K) -
Keizo Kobayashi, Kenji Miwa, Minoru Fukunaga, Masahiro Machida1994 Volume 41 Issue 1 Pages 14-17
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWC-8.6mass%Fe-1.4mass%Al and WC-6.7mass%Fe-3.3mass%Al alloys were prepared by sintering of wet-mixed powder of WC, Fe and AI at 1713K for 2.4ksec in a vacuum and then their hot isostatic pressing.
The evaporation of 13% Al from WC-Fe-Al alloys have been observed in the fabricating process. The sintered WC-Fe-Al alloys have a fine microstructure. Especially, the WC-8.6mass%Fe-1.4mass%AI alloy, which has a few pores after sintering at 1713K, has 1.8GPa of TRS and 92.5HRA of hardness. Furthermore, the increase in weight due to oxidation in this alloy is about one half that of the conventional WC-12mass%Co alloy.View full abstractDownload PDF (1642K) -
Nobuyuki Shinohara, Shinji Shirai, Hiroaki Okamoto, Ken-ichi Takagi1994 Volume 41 Issue 1 Pages 18-21
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMetal molds and machine parts for die-casting need excellent corrosion resistance against molten metals. In this study, we investigated corrosion resistance of various kinds of boride base hard materials ( Mo2FeB2-Fe, Mo2NiB2-Ni, WCoB-Co, W-Mo2NiB2-TiB2 base cermets and TiB2 ceramic ) against a molten Al alloy (JIS ADC10), a Zn alloy (JIS D-2) and soft solders (JIS H5A and H70A). The corrosion resistances of these materials were estimated by measuring the dimensional changes after dipping in the molten metals.
The results indicated that the boride base hard materials, especially TiB2 containing materials had higher corrosion resistance than. conventional materials, such as WC-20mass%Co, SKD61 and SK1151. SEM micrographs showed that the binder phases comprising Fe, Co and Ni in the boride base hard materials react with the molten metals, prior to the boride phase. The boride base hard materials are consequently promising candidates for the die-casting machine parts and molds.View full abstractDownload PDF (2049K) -
Katsuhiro Nishiyama, Keisuke Taguchi, Ken-ichi Takagi, Shinya Ozaki1994 Volume 41 Issue 1 Pages 22-26
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSSliding friction experiments were conducted on B4C-TiB2 ceramics and Mo2FeB2 boride base hard alloy (cermet) against themselves. Friction and wear properties were studied by a reciprocal sliding apparatus under the dry condition in air. The test conditions included maximum sliding velocity of 0.019m/s, temperature up to 800°C and normal forces ranging from 2.5N to 33N. Friction coefficients as low as 0.09 to 0.14 were obtained at 800°C for B4C-TiB2. The lowest friction coefficients as well as 0.1 to 0.2 were observed for Fe-61%Mo2FeB2(H50) over the temperature range tested. For most of the sliding pairs, the wear rate was in the range of 10-6 to 10-5 mm3/N⋅m. It was presumably explained that the low coefficient of friction and good wear resistance were caused by the lubrication effect of oxide film.View full abstractDownload PDF (3064K) -
Kei Tokumoto, Hironobu Shinoaki, Tetsunori Kitada, Shigeya Sakaguchi1994 Volume 41 Issue 1 Pages 27-32
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTi-8.4vol%M-47.4vol%TiC (M: Cr, Mo, W) alloys were prepared through P/M technology and their microstructures and mechanical properties were investigated. It was revealed that Ti-Cr-TiC alloy (Cr alloy) had 3 phases, which were TiC, α-Ti and β-Ti, Ti-Mo-TiC alloy (Mo alloy) had 2 phases, which were TiC and β-Ti and Ti-W-TiC alloy (W alloy) had 3 phases, which were TiC, β-Ti(Ti rich) and W(β-Ti type, W rich). It was noted that TiC grain size of W alloy was much smaller than that of both Cr alloy and Mo alloy. It was found that hardness and transverse-rupture strength of W alloy were much higer than those of both Cr alloy and Mo alloy.View full abstractDownload PDF (1600K) -
Toshiyuki Takahashi, Yuji Katsumura, Hisashi Suzuki1994 Volume 41 Issue 1 Pages 33-37
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt was previously reported by the present authors that the white ceramics with fine grain size of about 0.8μm showed an excellent transverse-rupture strength as high as about 1.3GPa. Then, the cutting performance of this fine grained ceramics tools was studied comparing with that of commercially available coarse grained white ceramics ones. The cutting performance of Al2O3 -30mass%TiC or Al2O3 -40mass%ZrO2 ceramics tools was also studied for comparison. It was found that the fine grained ceramics tools showed the smallest flank wear among four sorts of tools in turning tests of gray cast iron and carbon steel, and that they were superior to commercially available ceramics tools from the viewpoint of resistance to fracture in different cutting tests.View full abstractDownload PDF (5800K) -
Toshihiko Nishida, Kazuya Yamada, Hiromi Nakano, Kazuyori Urabe1994 Volume 41 Issue 1 Pages 38-42
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMixtures of Ti-C and Si-C powders respectively equimolar were mixed in various ratios. The final mixture was molded by using an pressure-resistant metallic mold whose inner wall was covered with a carbon felt for insulation. The molded mixture, once set in the mold, was ignited by a tungsten heater and, then, instantaneously uniaxially compressed of 1 GPa (SHS/HP processing). SEM and TEM observations were carried out to get insight in the microstructures obtained for the TiC/SiC composites. Two separated phases, namely SiC and TiC, were present in the composites prepared from Ti-C rich mixtures. In these cases, aggregates of SiC grains, often including some large pores, were found surrounded by the bulk polycrystalline TiC body. On the other hand, fine dispersions of TiC and SiC grains were obtained when nearly equimolar mixtures of Ti-C/Si-C were employed. In this latter case, a maximum value of 28 GPa for the Vickers hardness was measured.View full abstractDownload PDF (3273K) -
Tadahiko Watanabe, Kazuhisa Shobu, Eiji Tani1994 Volume 41 Issue 1 Pages 43-47
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTiB2-6%TaB2-1%CoB-2%TiC ceramics have a bending strength of 1000MPa and a porosity of 0.1vol%, but fracture toughness KIC of 3-3.5MPam1/2. Therefore, our desire is to improve the fracture toughness Klc of these ceramics. TiB2-6%TaB2-1%CoB-2%TiC-30%m-ZrO2 and TiB2 6%TaB2-1%CoB-2%TiC-40%t-ZrO2 ceramics in which t-ZrO2 contains 12mol%CeO2 have KIC of 7.5 and 12MPam1/2, respectively. It is thought that the high KIC of the ceramics containing m-ZrO2 and t-ZrO2 stabilized by CeO2 are mainly caused from the following reasons. The fracture cracks are stopped and diffracted by the micro-cracks between ZrO2 grain and other chemical composition grain which are caused by the difference of thermal expansion and which are occured by influence of the fracture cracks.View full abstractDownload PDF (4102K) -
Won Seung Cho, Koji Hayashi1994 Volume 41 Issue 1 Pages 48-52
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe dependence of the mechanical properties of SiC whisker(SiC(w))/Si3N4 composite ceramics on the crystal type( α or β) of Si3N4 starting powders were investigated for two kinds of composite ceramics(WR and WL) in which the longer axes of SiC(w) were random and unidirectionally oriented to the specimen axis, respectively. The results obtained were as follows; (1) The shape of β -Si3N4 grains in WR and WL composite ceramics were nearly the same as those of monolith; acicular grains for α-type powder and almost equiaxed grains for β-type powder. (2) Both the flexural strength(FS) and KIC of the WR and WL composite ceramics from α-type powder were higher than those from β-type powder. The ratios of both FS and KIC of composite ceramics from α-type powder to those from β-type powder were lower than those of FS and KIC of the monolith, which was ascribed to higher load transfer effect of SiC(w) than crack deflection effect by Si3N4 grains. (3) The increases in FS and KIC of composite ceramics by the unidirectional orientation of SiC(w) were higher in the composite from α-type powder than those in the composite from β-type powder. This was attributed to the preferential orientation of acicular β-Si3N4 grains in the composite from α-type powder which was promoted by the uni-directional orientation of SiC(w).View full abstractDownload PDF (2633K) -
Masami Ikeyama, Kazuo Saitoh, Akiyoshi Chayahara, Takahiro Tanaka, Nob ...1994 Volume 41 Issue 1 Pages 53-56
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSVariations of surface hardness of alumina induced by ion implantation were studied by using a dynamic ultramicrohardness tester changing the maximum loads as 2, 20 and 120 gf. Implanted ion species and energies were 0.4 MeV B+, 0.7 MeV Si+ in which 1.3 MeV Cu+, and their projection ranges were almost the same of 0.6μm. and 3 MeV of B2+, Si2+ and Cu2+. The implantation dose was mainly 1×1016 ions/cm2. Hardness for the loads of 2 and 20 gf was increased in any implantation. But the change in hardness for 120 gf was negligibly small. Apparent depth profile of the dynamic hardness, which was obtained from the "load-depth" data in indentation, showed clear increase of hardness in the top layer and relatively softer layer beneath of it. The thickness of the harder layer was in-creased with the increase of the implantation energy. Heat treatment (1000°C. 1 hr, in Ar) made the surface softer generally. Comparing with the unimplanted samples. however, the dynamic hardness, especially for the loads of 20 gf was increased. There was a tendency that the heavier ion species and the higher energy implantation showed the larger increase of hardness.View full abstractDownload PDF (301K) -
Hidenori Kohzuki, Tsuguo Ishihara, Yasuo Okuno, Muneyuki Motoyama1994 Volume 41 Issue 1 Pages 57-62
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to investigate the effect of the self-bias voltage applied to a substrate on the formation of cubic boron nitride (c-BN) film, boron nitride (BN) films were deposited on silicon wafer by varying the self-bias voltage, using the reactive ion plating method with a hot cathode plasma discharge in a parallel magnetic field. The crystal structures of these BN films were identified by characteristic X-ray emission spectra of boron measured with an EPMA and infrared absorption spectra.
The self-bias voltage in excess of-15 V must be applied to a substrate for the formation of c-BN film. But c-BN film grows independently of the self-bias voltage about 5 minutes after starting the deposition. Therefore, c-BN film can be deposited without excessive ion bombardment by dropping the self-bias voltage during the deposition. The deposition rate of BN film decreases with an increase in the self-bias voltage. It is effective for the increase of its deposition rate to drop the self-bias voltage after the initial period of the deposition.View full abstractDownload PDF (324K) -
Sung-Soo Lee, Hideaki Itoh, Hiroyasu Iwahara1994 Volume 41 Issue 1 Pages 63-67
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFine-grained diamond coating was obtained on W, Mo or Ti wire substrates by the microwave plasma CVD method from a gas mixture of the CO-H2 system. The effects of CVD parameters on a uniform coating of polycrystalline diamond were investigated under the constant conditions of reaction time (5 h) and CO concentration (5 vol%), using the wire substrates mounted horizontally on a pyrophyllite susceptor. Homogeneous and fine-grained diamond film was prepared on the whole surface of W wire substrate with the wire height of 2 mm from the susceptor, which was placed parallel to the irradiation direction of microwave power (750-1100 W). Deposition conditions under higher microwave power, lower pressure and lower wire height were found to be suited for preparation of microcrystalline and uniform coating of diamond. Plasma density and substrate temperature are considered to have great influences on the nucleation of diamond.View full abstractDownload PDF (4408K) -
Yasushi Tomiku, Hideaki Takano, Yoshichika Bando1994 Volume 41 Issue 1 Pages 71-74
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWe report the preparation processes and magnetic properties of ε' iron carbide ultrafine particles. Ultrafine particles of δ-FeO(OH) and CoFe2O4 were selected as starting materials for ε' iron carbide ultrafine particles. δ-FeO(OH) particles and CoFe2O4 particles were coated with SiO2 for preventing agglomeration of particles during heating. δ-FeO(OH) particles were heated at 450°C for 3h in air to be transformed into a-Fe2O3. The α-Fe2O3 particles were granular and a little sintered in spite of SiO2 coating. After α-Fe2O3 and CoFe2O4 were reduced to metal, α-Fe metal and alloy particles were respectively carburized at 210°C for 4h in the mixing gas flow of CO and H2 in the volume ratio of 1/4. XRD patterns reveal that both particles are ε' iron carbide single phase. Both of ε' iron carbide phase particles were granular and 20-30nm in diameter. The saturation magnetizations of the ε' iron carbide ultrafine particles obtained from starting materials of δ-FeO(OH) and CoFe2O4 were 65 and 69 emu/g respectively, while the coercive forces were 1200 and 1270 Oe.View full abstractDownload PDF (3513K) -
Nobuya Matsutani, Osamu Inoue, Kouichi Kugimiya1994 Volume 41 Issue 1 Pages 75-78
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWe have developed new low loss ferrites with a magnetic loss of less than 100kW/m3 at MHz, 50mT and 80°C, which was 1/5 times of that of coventional low loss ferrites. These new low loss ferrites were obtained by the following principle and technology:
(1) A simple method was applied to separate the magnetic loss into a hysteresis loss, an eddy current loss and a residual loss.
(2) Hysteresis loss and eddy current loss were simultaneously reduced by the segregation of additives highly concentrated at grain boundaries.
(3) Residual loss, which is probably associated with domain wall resonance, was reduced to almost zero by controlling permeability.View full abstractDownload PDF (243K) -
Kazuharu Iwasaki, Ken Segawa, Keiichi Kagami, Masahiro Kikkawa1994 Volume 41 Issue 1 Pages 79-83
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSRecently cordless telephones and mobile telephone systems have been developed rapidly, so that high quality dielectric filter is required.
BaO-RE2O3-TiO2system is suitable for microwave dielectrics because of its high dielectric constant and high Q value. The effects of fabrication conditions, such as calcination temperature, press condition, sintering time and sintering temperature on dielectric properties of BaO-Bi2O3-Nd2O3-Sm2O3-TiO2 ceramics were investigated.
Spherical grains were observed at sintering temperature 1305°C, and cylindrical grains at 1348°C in these ceramics.It was proved by X-ray analysis that these grains had BaNd2Ti5O14 type crystal structure. Large massive grains of TiO2 rutile type structure were also observed at 1408°C.
As these crystal structures change, dielectric properties also change remarkably;the dielectric constant and temperature coefficient increase with Increasing sintering temperature and the Qu factor has a maximum value at about 1360°C.
The other fabrication conditions also have a favorable influence upon the properties of this ceramic systemView full abstractDownload PDF (1429K) -
Kenji Higashi, Yasushi Matsumura, Mamoru Mabuchi, Shinji Tanimura1994 Volume 41 Issue 1 Pages 84-87
Published: January 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe tensile behavior of a powder metallurgically processed Al-5mass%Mg-2.2mass%Mn alloy with a fully recrystallized fine grained structure of 3 μm in size was characterized at strain rates between 10-4 and 2 s-1 at temperatures from 748 to 823 K. This alloy exhibited superplasticity at high strain rates around 10-2 s-1. A maximum elongation of 570 % was obtained at a constant strain rate of 6x10-3 s-1 at 823 K. An analysis of the threshold stress indicated that the true stress exponent is 2 for all testing temperatures and the true activation energy for superplastic flow is equal to that for lattice diffusion in aluminum. It is postulated that superplastic flow in the P/M Al-Mg-Mn alloy is controlled by a grain boundary sliding mechanism accommodated by dislocation climb or glide controlled by lattice diffusion.View full abstractDownload PDF (248K) -
Toshihiko Yamaguchi, Yasushi Ibata, Makoto Watanabe, Shinji Ando, Hide ...1994 Volume 41 Issue 1 Pages 88-92
Published: January 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFatigue crack growth of the sintered ferrous materials by HIP has been investigated taking the microstructures and the pattern of fractured surfaces into account.
The results obtained are summarized as follows:
(1) In the case of constant stress ratio, the fatigue crack growth rate(da/dN) of sintered materials by HIP with diffusion alloyed powder had a tendency to become slower than that of sintered materials by HIP with prealloyed and mixed elemental powders under the same stress intensity factor range(ΔK). The material constant value (m) in da/dN=C(ΔK)m was found in the range of 3.8 to 5.3, which was the same as that of wrought materials. Sintered iron compacts showed higher da/dN and m values than those of sintered materials by HIP.
(2) The ΔKth(da/dN<10-9m/cycle) of sintered iron compacts was higher than that of sintered materials by HIP. The influence of stress ratio was recognized with the relationship between da/dN and ΔK of any sintered materials by HIP.
(3) Fatigure crack grew preferentially in the ferrites as forming the slip bands close together. The behavior of fatigue crack growth was distinctly dependent on the microstructures, the cracks propageted linearly through the pearlites, and the cracks penetrated through or bypassed the cementites.
(4) The fractured surface reflected the local intergranular fracture in the region of low crack growth rate(da/dN<10-9m/cycle). On the other hand, the striation like pattern was mainly observed in the region of high crack growth rate(da/dN=10-7-10-9m/cycle). As the stress ratio was increased, unevenness of the fractured surface was more distinguished.View full abstractDownload PDF (3439K)
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