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Volume 56, Issue 12
December
Displaying 1-12 of 12 articles from this issue
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Paper
Rapid Communication
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Keitaro Enami, Masaki Ohara, Takanori Igarashi, Junji Fujita, Katsuyos ...2009 Volume 56 Issue 12 Pages 717-721
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSThe utilization of the magnesium alloy in the engine parts of the automobiles and motorcycles is expected to improve fuel efficiency. But the creep resistance at 150°C∼250°C is required in the engine parts, which prevents the use of the magnesium alloy. In this research, AM60 magnesium alloy chip mixed with 10 volume percent calcium oxide powder was processed into a magnesium composite billet, in which the calcium oxide powder was finely and uniformly dispersed, by the Equal Channel Angular Bulk Mechanical Alloying (ECABMA) method. The composite billet was extruded at 450°C into a round bar, whose diameter was 20 mm or 40 mm. The mechanical properties of the extruded magnesium composites, such as the creep resistance at 175°C, were investigated. The extruded magnesium composite was found to have the higher strength at room temperature and 250°C, and the higher creep resistance at 175°C than those of the ADC12 aluminum alloy.View full abstractDownload PDF (918K)
Special Issue: Application of Electromagnetic Processing to Synthesis of Nano-structured Functional Materials
Summarization
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Yukio Makino2009 Volume 56 Issue 12 Pages 724
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSDownload PDF (101K)
Memorial Lecture of JSPM Award
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Yukio Makino2009 Volume 56 Issue 12 Pages 725-737
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSMaterials fabrication based on millimeter (MM)-wave and pulsed high current (SPS) heating processes have been reviewed and characteristics of these processes are discussed from the standpoints of the interaction between electromagnetic energy and solid materials. Capabilities of these processes in the fabrication of functional materials are indicated by exemplifying several successful results such as highly-strengthened or nano-structured alumina, highly thermal conductive AlN and preferentially oriented dense nano-structured anatase. In MM-wave heating process, the interactions between millimeter-wave and charged species in solid, such as ponderomotive force, have the important roles on the consolidation of powder materials, while atomistic mechanism in SPS heating process has not been explained well, though pulsed high current effect is important. Synthesis of pseudobinary T-Al-N (T: transition element) coatings by PVD process is also reviewed as an example of the processes assisted by electromagnetic energy. Hardness of the nitride coatings can be improved by dissolving AlN into TN and the formation of pseudobinary hard phase dissolved AlN is qualitatively explained by the pressure effect of energetic particle bombardment in PVD process. The experimental values of the maximum solubility of AlN into TN show good agreement with the values predicted by the band parameters method, indicating the importance of prediction based on electronic picture.View full abstractDownload PDF (1839K)
Review
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Hiroaki Katsuki2009 Volume 56 Issue 12 Pages 738-743
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSMicorwave-hydrothermal (M-H) processes have received considerable attention as a new promising method for rapid synthesis, energy saving, crystallization of new phases, and selective crystallization of ceramic powders. In this review, the effect of microwave radiation on the formation of smaller and uniform α-Fe2O3 powders from FeCl3 solution at 100∼140°C and some properties of powders were investigated. To develop α-Fe2O3 powders prepared by M-H process as a new red pigment for porcelain over 800°C, the sintering characteristics of these powders at 800∼1200°C and the effect of Al3+ ion addition into α-Fe2O3 lattice on the thermal stability at 900°C were also investigated.View full abstractDownload PDF (1098K) -
Effect of Internal Current for the Structure Formation of Specimen in Spark Plasma Sintering ProcessTatsuya Misawa, Noboru Shikatani, Yuji Kawakami, Takashi Enjoji, Masak ...2009 Volume 56 Issue 12 Pages 744-751
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSTo clarify the influence of internal pulsed current upon the sintering behavior of powder materials during spark plasma sintering processing, simultaneous measurement of internal current using magnetic probe was carried out. By magnetic probe measurement, the internal current that flows through the specimen during SPS process was several hundred ampere, and the ratio of the internal current to the total current was found to be dependent on the electrical conductivity, diameter of powder material and the progress of SPS process. The measurement and estimation of an internal pulsed current using a magnetic probe in the specimen is very useful for in situ observation of the sintering behavior during the SPS process. The XRD intensity of (002), (102) and (103) of ZnO nano-particles specimen was gradually decreased with the increase in the progress of SPS process, so, the preferential orientation in ZnO nano-powder occurred.View full abstractDownload PDF (1069K)
Paper
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Miki Miyanaga, Daiji Tabayashi, Makoto Setoyama, Hideki Moriguchi, Aki ...2009 Volume 56 Issue 12 Pages 752-757
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSIt has been progressed to study the effect of the metal composition on the mechanical properties of the hard coating synthesized by the PVD method. In traditional method the film with one metal composition is generally deposited by the alloy cathode with the corresponding metal composition in one running, and thereafter investigated on the mechanical properties. On the other hand, a new efficient method, said as the combinatorial method, was suggested for studying the effect of the metal composition on the film characteristics. In this method, the film with various compositions can be obtained at once in one running. In the present report, the effect of the metal composition on the film hardness and the change of the crystal structure were studied in the Ti-Al-N film prepared by the combinatorial method. In combinatorial method, it was found that the film hardness was rapidly decreased with the deposition of the B4 type crystal. This showed the excellent agreement with the result obtained in the traditional method and the propriety of this combinatorial method was proved in the range of the study about the mechanical property of Ti-Al-N film synthesized by the unbalanced magnetron sputtering.View full abstractDownload PDF (780K) -
Takuya Yasuno, Tetsuya Naruse, Tohru Kohno, Masakazu Kawahara, Masao T ...2009 Volume 56 Issue 12 Pages 758-762
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSA hyper eutectic Al-24mass%Si alloy powder atomized in Ar was consolidated by spark plasma sintering (SPS) and the effect of the microstructure on mechanical properties of the sintered compact was examined. The sintered compact produced by SPS method at a sintering temperature of 723 K which is 150 K lower than that of PM method was fully densified, and had good mechanical properties. When the Al-24mass% alloy powder was consolidated by SPS, the microstructure became a morphology which proeutectic Si regularly arranged at the boundary between the powder particles. This result indicates the occurrence of the local melting on the powder surface. Consequently, the stable oxide film on the powder particle surface was removed by occurrence of spark plasma during SPS and the strong bonding between the particles was obtained.View full abstractDownload PDF (795K) -
Keizo Kobayashi, Kimihiro Ozaki, Toshiyuki Nishio, Syuji Tada, Hiroyuk ...2009 Volume 56 Issue 12 Pages 763-767
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSPorous titanium compacts were prepared by a pulsed current sintering of titanium fiber under a low pressure. The punch fixed on the electrode enabled the fabrication of the porous material with any thickness. When a non-conductive die was used for the pulsed current sintering, pulsed current was passed to titanium fiber directly. Therefore the each titanium fiber of 100 μm diameter was joined by applying 0-800 A pulse current for five seconds. When the frequency of the pulsed current was higher, the compact was sufficiently heated, and the junction of the titanium fiber became strong. In these experimental conditions, the porous titanium compact having porosity from 40 % to 60 % were formed stably.
The junction of the titanium fiber occurred in the early stage of the pulsed current sintering and became stronger by the latter heating. Even if the obtained porous titanium compact heated in the air, most of the joints between the titanium fibers did not come off.View full abstractDownload PDF (1421K) -
Kiyoshi Mizuuchi, Kanryu Inoue, Yasuyuki Agari, Yoshiaki Morisada, Mas ...2009 Volume 56 Issue 12 Pages 768-774
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSDiamond-particle-dispersed-silver (Ag) matrix composites were fabricated in solid-liquid co-existent state by Spark Plasma Sintering (SPS) process from the mixture of diamond powders, Ag powders and Si powders. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 1113 K and 1188 K for 0.45 ks during SPS process. No reaction at the interface between the diamond particle and the Ag matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. The relative packing density of the diamond-Ag composite fabricated was 95-97 % in a volume fraction range of diamond between 40 % and 50 %. Thermal conductivity of the diamond-Ag composite containing 50 vol.% diamond reached 717 W/mK, approximately 80 % the theoretical thermal conductivity estimated using Maxwell-Eucken's equation.View full abstractDownload PDF (1542K) -
Hiroyuki Nakayama, Keizo Kobayashi, Kimihiro Ozaki, Shuji Tada, Masash ...2009 Volume 56 Issue 12 Pages 775-779
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSThe (70-x)TiC-xTiB2-26Fe-4Al (mass%) cermets were fabricated by mechanical milling of TiC, TiB2, Fe and Al powders and subsequent pulse current sintering method. The highly dense cermets were obtained by a reaction for formation of Fe-Al intermetallic compound between Fe and molten Al. The prepared cermets were mainly composed of TiC, TiB2 and Fe-Al intermetallic compound. In addition, small amount of Fe2B was observed. The thermal conductivity of prepared cermets lineally increased with increasing TiB2 volume fraction. The measured thermal conductivities were higher than those of the theoretical values. The deflecting strength and hardness of the cermets achieved 0.8 GPa and HRA 89, respectively.View full abstractDownload PDF (1541K) -
Khanh Quoc Dang, Masakazu Kawahara, Shinichi Takei, Makoto Nanko2009 Volume 56 Issue 12 Pages 780-787
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSPure Al2O3 powder was sintered by a pulsed electric current sintering (PECS) process with different pulse current waveforms from two types of power generators: an inverter (frequency 16 kHz) type and a pulsed direct current (DC) (frequency 300 Hz) type. The sample temperature during the PECS process as well as the sintering behavior was investigated. The effects of pulse current waveform on the sintering process were discussed. For the same die temperature ranging from 1100 to 1400°C at holding period, the sample temperature under experiments using the inverter was higher than that under experiments using the pulsed DC. Densification and grain growth were predominated by sample temperature and did not depend on the pulse current waveform directly.View full abstractDownload PDF (1896K) -
Masao Tokita, Nobuyuki Tamari, Tomonari Takeuchi, Yukio Makino2009 Volume 56 Issue 12 Pages 788-795
Published: 2009
Released on J-STAGE: January 19, 2010
JOURNAL OPEN ACCESSSPS consolidation of β-SiC powder was performed using Yb2O3-Al2O3 as sintering additives. Densification behavior and mechanical properties of SPS-consolidated SiC were compared with those of hot-pressed SiC. Nearly full densification was attained at about 1750°C for SPS-consolidated SiC and at about 1900°C for hot-pressed SiC, respectively. Both optimal bending strength and fracture toughness of SPS-consolidated SiC were 720MPa and 4.0MPa·m1/2 and these values were higher than those (640MPa and 3.5MPa·m1/2) of hot-pressed SiC, indicating that SPS consolidation can improve the bending strength without degradation of fracture toughness. From XRD and Raman scattering analysis, it is suggested that 3C-type disordered structure is preserved in the SPS-consolidated SiC and the improvement of the bending strength without degradation of fracture toughness is attained by the preservation of the 3C-type disordered structure.View full abstractDownload PDF (1203K)
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