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Volume 44, Issue 12
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[in Japanese]1997 Volume 44 Issue 12 Pages 1068
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (63K) -
Atsushi Iga1997 Volume 44 Issue 12 Pages 1069-1074
Published: December 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe sintering of ZnO+Bi2O3+Sb2O3 ceramics was studied. Usually, ZnO varistors have been sintered at a temperature higher than 1200°C, because Sb2O3 in the raw material retards sintering by evaporating at low temperature and forming Sb-compond thin films on ZnO surface. When Bi2O3 and Sb2O3 were mixed and heattreated beforehand and added to ZnO, the ZnO+Bi2O3+Sb2O3 could be sintered at about 900°C. During heattreatment with Bi2O3, Sb2O3 reacted with Bi2O3 and stopped sublimating, and the effect of sintering retardation was disappeared.View full abstractDownload PDF (4294K) -
Atsushi Iga1997 Volume 44 Issue 12 Pages 1075-1077
Published: December 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSBy heat-treating the mixture of Bi2O3 and Sb2O3 beforehand and adding the mixture to ZnOwith other metal oxides, ZnO varistors were sintered at tempersture 850-950°C and the electric characteristics were studied. When the content ratio of Bi2O3 and Sb2O3 was 3:1 in the ZnO+Bi2O3+Sb2O3+CoO+MnO+Al2O3, the varistor voltage and α-value became minimum. These values, V1mA/mm and α, increased with increasing amount of Sb2O3 content. The effect of Cr2O3-addition was studied.View full abstractDownload PDF (136K) -
Tsuyoshi Yoshida, Atsushi Nakahira, Kazunori Kijima, Yong-Ho Choa, Koi ...1997 Volume 44 Issue 12 Pages 1078-1082
Published: December 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffect of micronsize-B4C dispersion on the sintering behavior and microstructures of SiC has been investigated for the SiC/B4C composite prepared by pressureless sintering technique. Especially relation between sintering additives and the sintering behavior of SiC/B4C composite was studied.
Nearly fully dense composites were obtained by the pressureless sintering technique in argon atmosphere at 2250-2300°C for lh of holding time. From SEM and TEM observations of the microstructure for these SiC/B4C composites, the dispersion of micronsize-B4C as the second phase into SiC matrix was found to inhibit SiC grain growth. In the case of SiC/B4C composite system prepared by the pressureless sintering technique, SiC matrix showed the rod-like grain up to 10 vol% of B4C addition. With the addition of 20% B4C, the morphology of SiC matrix grain was relatively round and fine. Furthermore, HREM observation showed no reaction phase at grain boundary of SiC matrix grain and B4C dispersion. The hardness was also evaluated for these SiCB4C composite system.View full abstractDownload PDF (1790K) -
Jing-Feng Li, Akira Kawasaki, Ryuzo Watanabe1997 Volume 44 Issue 12 Pages 1083-1088
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe sintering behavior of fine-grained ZrO2 (3mol%Y2O3) powder compacts containing 10-30vol% Al2O3 during constant-heating-rate sintering has been studied, with particular emphasis on the size effect of Al2O3 particles. The additions of Al2O3 particles retarded the densification and the effect was more remarkable with increasing Al2O3 volume fraction. The retardation effect of the Al2O3 dispersion particles was found to be independent of the particle size, and has been discussed from the following two aspects: (1) interactions between the dispersion particles that create a constraint on the matrix, and (2) formations of large pores or low-density regions around the dispersion particles due to non-uniform parking density in the mixed powder compacts.View full abstractDownload PDF (3957K) -
Masato Fujimoto, Nobuyuki Nakamura, Setsuo Takaki1997 Volume 44 Issue 12 Pages 1089-1094
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSintering behavior and microstructures of Ti-(5-10)mass%Al-(1-10)mass%Mo alloy compacts prepared by the technique of mixing Ti, TiAI and Mo powders were investigated by means of optical microscopy. Mechanical properties of the sintered materials were also examined in connection with microstructures.
Addition of (5-10)mass%A1 and (1-10)mass%Mo contributes to sintering densification of titanium compact, since the particle size of TiAI and Mo powders are much finer than that of Ti powder. While, the diffusion of Al and Mo atoms into titanium matrix greatly depend on temperature, so that the powder compacts have to be sintered for 3.6ks at a temperature above 1573K to obtain homogeneous materials in the chemical composition. The structure of compacts is of β (bcc) single-phase at 1573K, but a (hcp) phase precipitates during cooling from the sintering tempereature. When Al content is more than 8mass%, Ti3Al can also precipitate and this makes the sintered materials brittle. On the other hand, when Mo content is more than 6mass%, a phase preferentially precipitates along grain boundary and this results in a decrease of elongation attributed to intergranular fracture. As a result of alloy design, Ti-8mass%Al-4mass%Mo alloy with fine two-phase structure of (α+β) was selected to obtain optimal tensile properties at both temperature of room temperature and 873K.View full abstractDownload PDF (5503K) -
Atsushi Ariga, Hajime Katsuta, Kazuro Kawamura1997 Volume 44 Issue 12 Pages 1095-1099
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effects of additives on the densification and color quality of TiN ceramics were studied. Some oxides (Al2O3, CaCO3, TiO2, Y2O3, ZrO2) as additives were prechecked by sintering, and we selected TiO2 as an addition. TiN was densified by pressureless sintering at 1550° to 1850°C in N2. Samples with addition of 8wt% TiO2 sintered at 1550°, 1700°, and 1850°C showed the relative densities of 97.7, 99.8, and 99.7%, respectively. The optical reflectivity of polished samples was similar to that of gold. Vicker's hardness of some sintered bodies reached about 16GPa. Therefore, polished sintered bodies can be used for ornament.View full abstractDownload PDF (2437K) -
Chang-meng Wang, Ryuzo Watanabe1997 Volume 44 Issue 12 Pages 1100-1106
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSInfiltration-combustion reaction between Ti green compact and molten Al was studied. The infiltration height change obtained by in-situ measurement, showed a linear proportion to the root of immersing time, but an incubation period was observed in the initial stage of the immersion. Using thermocouple embedded in the Ti green compacts, the combustion temperature of Ti powder and molten Al was determined to be about 1360K, which is lower than the calculated adiabatic temperature, 1580K, of the combustion synthesis of TiAl3. In the preform immersed into molten Al for 30s, granular products were observed at the surfaces of Ti particles. By the observation on the helium-gas-quenched sample, it was confirmed that disintegrated Ti particles and spherical particles of TiAl3 were formed. The crevice between the as-reacted TiAl3 particles was found to be filled with molten Al by the further infiltration to form Al/TiAl3 composite. The final microstructure of this reaction is a cermet type one with about 74 vol% of TiAl3 and the average particle size is about 12μm.View full abstractDownload PDF (3645K) -
Atsushi Hibino1997 Volume 44 Issue 12 Pages 1107-1114
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCombustion synthesis process is attracted as new synthesizing technology of TiAI intermetallic compound. However, since the synthesized products tend to be heterogeneous and by-products such as TiAl3 or α, β Ti-Al solid solution are synthesized in addition to TiAl, homogeneous and superior material is not obtained yet. To realize combustion synthesis of the compound, control conditions of microstructure and synthesized phase should be established. In this paper, a numerical model of TiAl combustion synthesis is driven, and combustion behavior and phase control condition are investigated. The numerical analysis is performed by solving the model equations with finite differential method.
From the calculation, the combustion behavior and the compound formation behavior are able to be simulated. At first TiA13 is formed, secondly Ti-Al solid solution is synthesized. TiAl is formed by reaction between the both compounds. The synthesis process and the synthesized phase are affected by combustion temperature. In case that the temperature is low, the formation reaction of TiAl is inferiority and the synthesized products become to be TiAl3 and Ti-Al solid solution. In case that the combustion temperature is high, TiAl is synthesized. Same result is able to be obtain from the experiment of the TiAl synthesis. TiAl is detected in a sample that the temperature is high, and for the low temperature sample TiAl phase is not found. Therefore, the combustion temperature is important for controlling of the synthesized phases, and it is found that the temperature should be control accurately to obtain the homogeneous and superior compound.View full abstractDownload PDF (492K) -
Masateru Nose, Takekazu Nagae, Masaru Yokota, Shigeoki Saji, Yoshihito ...1997 Volume 44 Issue 12 Pages 1115-1120
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe alloy powder of 2Nb/Al composition was prepared by mechanical alloying. The alloy powder became homogeneous and showed an amorphous-like pattern in X-ray diffraction after milling with a small amount of additives for 396ks. This mechanically alloyed powder kept the amorphous phase even after heating up to 973K for 600s, and was changed to Nb2Al phase by heating over the temperature of 1073K. The compact of this powder sintered at 973K for 300s by pulse current pressure sintering (PCPS) was not consolidated, although the amorphous structure was kept even after heating. On the other hand, the compact sintered at 1673K by PCPS method consisted of mainly Nb2Al phase and a small amount of uncertain phase. The density for the compacts sintered at 1673K was 7.16 × 103 kg/m3, which is about 5% higher than that for Nb2Al. Vickers hardness was 1000-1100, which is 15 to 30 % higher than that of Nb2Al (850-870). It can be speculated that these results are attributed to the finely dispersed particles containing Fe, which came from the container and/or balls for the mechanical alloying.View full abstractDownload PDF (1448K) -
Norio Matsui, Keizo Kobayashi, Akira Sugiyama, Kimihiro Ozaki1997 Volume 44 Issue 12 Pages 1121-1125
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFe52Cr48+5mass%X(X=Si, C) were synthesized by mechanical alloying (MA) of the elemental powders of Fe, Cr and Si/C using a planetary ball milling for 180ks under 1.33kPa argon gas atomosphere. These MA powders were consolidated by spark plasma sintering (SPS) process.
The X-ray diffraction patterns of mechanical alloyed Fe52Cr48+5mass%Si and Fe52Cr48+5mass%C powders were almost similar with that of mechanical alloyed Fe52Cr48 powder. The σ-phase was obtained by only SPS of Fe52Cr48+5mass%Si. In this MA-SPS process, Fe52Cr48 alloy without σ-phase was synthesized and formed because of the few Si contamination in this process. The sintered Fe52Cr48 alloy without σ-phase had a coefficient of thermal expansion lower than that of SUS304 stainless steel.View full abstractDownload PDF (1606K) -
Kimihiro Ozaki, Keizo Kobayashi, Akira Sugiyama1997 Volume 44 Issue 12 Pages 1126-1130
Published: December 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to prepare a bulk amorphous alloy, Al-based amorphous powder was sintered. Mechanical alloyed Al70Ti12Si18 powder was used. The powder structure included amorphous and nano-crystalline phases. This powder was milled with Sn, with lower melting point, by mechanical alloying for 36ks. The amorphous powder was coated with Sn by mechanical alloying. This milled powder was sintered by spark plasma sintering in the temperature over the melting point of Sn, but under the crystallization temperature of Al70Ti12Si18 powder. A disk specimen of 10mm diameter and 2mm thickness was prepared. The disk specimen of the amorphous alloy was prepared at sintering temperature of 503K and holding time of 1.2ks at 375MPa. The specimen consisted of amorphous phase, crystallized phase and the remained Sn phase. The amorphous phase crystallized at sintering temperature of 533K.View full abstractDownload PDF (4423K) -
M. Sherif El-Eskandarany1997 Volume 44 Issue 12 Pages 1131-1142
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical alloying (MA) method using ball-milling and/or rod-milling techniques has been employed for synthesizing several metallic amorphous alloy powders and nanocrystalline powders of metal nitrides, metal hydrides, and metal carbides. This review paper shows: (1) the effect of the milling media (balls or rods) on the solid state amorphization reaction, (2) the effect of annealing on the mechanically alloyed powders and (3) the consolidation of the mechanically reacted powders into full dense nanocrystalline compacts. Some mechanical and physical propertied of the as-consolidated powders are presented.View full abstractDownload PDF (6304K) -
M. Sherif El-Eskandarany, Mamoru Omori, Kenji Sumiyama, Toshio Hirai, ...1997 Volume 44 Issue 12 Pages 1143-1147
Published: December 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSElemental powders of Al (79 vol.%), TM (TM; Ti, Mo and Cu) (1 vol.%) and J3-SiC (20 vol.%) compound were mechanically alloyed using ball-milled technique. The end-product which is a composite Al-SiC-TM nanocrystalline powders was consolidated into compact (20 mm in diameter) using the plasma activated sintering method. The as-milled and as consolidated samples were characterized by means of X-ray diffraction, transmission electron microscopy, scanning electron microscopy and chemical analysis. Moreover, the hardness of the compacted sample was determined using a Vickers indenter with a load of 10 kg, and found to be 2.27 GPa. In addition, the density of the consolidated sample was determined by Archimedes' principle using water immersion and found to be 3×103 kg.m-3. The effect of the TM elements on the mechanical properties (Poisson's ratio, Young's modulus and shear modulus) of Al-SiC bulk composite has been studied.View full abstractDownload PDF (4641K) -
Shinsaku Hanasaki, Junsuke Fujiwara, Tadahiro Wada, Masanori Yosutomi1997 Volume 44 Issue 12 Pages 1151-1156
Published: December 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSNodular cast iron (FCD) has high tensile strength and high hardness. However, in turning of FCD with a cemented carbide tool, the tool wear in turning of FCD becomes larger than that in turning of gray cast iron (FC). Furthermore, in high speed cutting of FCD, the progress of the tool wear increases rapidly with the increase of the cutting speed. In this study, in order to find out the effective tool materials for the high speed turning of the nodular cast iron, a ductile cast iron JIS FCD700 was turned with the various commercial tool materials at the cutting speed from 1.67m/s to 20m/s under the depth of cut 0.3 or 1.0mm and the feed rate 0.2 or 0.4mm/rev. The main results obtained are as follows: (1) In turning of FCD700, the TiN-TiCN-Al2O3 TiN coated cemented carbide tool is the effective tool materials for wide range of cutting speed, and it can be adapted for the high feed rate. (2) In turning of FCD700 with the TiC added Al2O3 ceramics tools, the progress of the tool wear becomes slow with the increase of TiC under the cutting speed from 1.67m/s to 5.0m/s. However, in higher speed cutting than 10m/s, the progress of the tool wear becomes fast with the increase of TiC.View full abstractDownload PDF (3740K) -
Yukihiro Kadogawa, Toshio Fukui, Yoshiharu Matsuda1997 Volume 44 Issue 12 Pages 1157-1161
Published: December 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEach aqueous solution of LiNO3 and Al(NO3)3 obtained by dissolving in a proper amount of distilled water was used as the starting solution, mixing them. γ-LiAlO2 was synthesized by a sol-gel method from the starting solutions with each small amount of Si(OC2H5)4 and the additives such as MnCl2, CoCl2, NiCl2 or CuCl2. γ-LiAlO2 began to form at a temperature around 700°C and its formation was most remarkable at 1000°C of the heighest temperature used in this study. The phase transition from β-to γ-LiAlO2 was observed in temperature range from 600° to 700°C. Each additive of MnCl2 and CuCl2 revealed the acceleration effect for the formation of γ-LiAlO2 and in particular, CuCl2 among the additives was most effective for its formation. Also, the addition of CuCl2 ranging in the con-centration from 1.0×10-3 to 4.5×10-3 mol revealed the acceleration effect for the formation of γ-LiAlO2 and that of CuCl2 with a concentration of 3.5×10-3 mol was especially most effective for its formation.View full abstractDownload PDF (315K)
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