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Volume 69, Issue 7
Displaying 1-11 of 11 articles from this issue
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Xin Zhang, Jiuxing Zhang, Qingmei Lu, Yanqin Liu2005 Volume 69 Issue 7 Pages 497-501
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSThe single phase p-type filled skutterudite CemLanFeCo3.0Sb12 compounds, where voids were filled by double elements, were synthesized by Spark plasma sintering (SPS) using powders of Co, Sb, Fe and rare earth Ce, La as starting materials. The thermoelectric properties of them were also studied. The results indicated that the electrical conductivity of CemLanFeCo3.0Sb12 compounds decreased with Ce and La filling fraction. The electrical conductivity decreases with the filling fraction of the Ce and La, while the lattice constant and the Seebeck coefficient of the compounds increase with the filling fraction of the Ce and La. Compared with the same filling fraction, the lattice thermal conductivity of CemLanFeCo3.0Sb12 is found to be smaller than that of CemFeCo3.0Sb12 and LanFeCo3.0Sb12. The compounds with m+n=0.3 had a minimum value of thermal conductivity in this invertigation, indicating that when the Sb voids in the skutterudite structure were filled by Ce and La the coupling rattling and the irregular distribution between the two filler ions that give rise to the mass change of atom lead to the additional phonon scattering produced by lattice aberration. The compound Ce0.1La0.2FeCo3.0Sb12 has the dimensionless figure of merit ZT=0.60 at 800 K.
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The Effect of Catalyst Density for Adhesion of Electroless Deposited Copper Films on Glass SubstrateNaoki Okamoto, Takashi Kimura, Tohru Watanabe2005 Volume 69 Issue 7 Pages 502-508
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSIn the present study, the adhesive properties and initial deposition processes of electrolessdeposited Cu films to glass substrates in detail. The adhesive strengths of Cu thin films which were electrolessdeposited on the glass substrates were evaluated by adhesive tape test, while their surface structures were analyzed by using TEM. We used two-step catalyzation (sensitization-activation) method for pretreatment of electrolessdeposition onto glass substrates. The catalyst distribution can be made to vary. The adhesive strength of Cu films tends to increase with decreasing SnCl2 concentration in sentitizer and increased with increasing surface roughness of glass substrates. In order to specify the exfoliation site, the quantitative analysis of Sn and Pd on the exfoliated film and the substrate was investigated by XPS. XPS analysis showed that Sn and Pd existed on the exfoliated films and only Sn existed on the substrates. The results indicated that the exfoliation of all the films electrolessdeposited on glass substrates occurred in the interface between the Sn adsorbates and the Pd adsorbates. The drying pretreatment after activation improved adhesive strength.
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Tomiko Yamaguchi, Kazumasa Nishio, Hidenori Era, Mitsuaki Katoh2005 Volume 69 Issue 7 Pages 509-516
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSPure titanium has an excellent biocompatibility in comparison with stainless steels and Ti-Al-V alloys. We would expect pure titanium to have application for artificial joints and artificial bones if the wear resistance of the pure titanium were to be improved. So the surface modification of the pure titanium was performed using YAG laser beam. The laser power was 1.5 kW and Ar was used as the shielding gas. The shielding gas flow rate was changed from 5 to 40 L/min with a constant laser torch traveling speed of 500 mm/min. First, we investigated effects of the shielding gas flow rate on the Vickers hardness of the laser melted zone. When the shielding gas flow rate decreases, the average hardness increases and the oxygen and nitrogen concentrations of the laser melted zone also increase. We made clear the relationship between the average hardness and the nitrogen equivalent in the laser melted zone as follows. When the square root of the nitrogen equivalent (Neq=N+O/2) was less than 0.1, a plot of the average hardness for the square root of the nitrogen equivalent reveals a linear relationship. However, the average hardness of the laser melted zone increased more than the value indicated by the linear relationship when the square root of the nitrogen equivalent was above 0.1. Next, metallurgical analyses of the laser melted zone were performed using an electron probe micro analyzer (EPMA), an X-ray diffraction method (XRD) and a transmission electron microscope (TEM), and effects of the behavior of oxygen and nitrogen on the hardness of the laser melted zone were studied. A uniform dislocation structures in the laser melted zone is observed over a wide area where there is the linear relationship between the hardness and the square root of the nitrogen equivalent. Lamellar structure, which alternated between two phases of αTi and TiN in the laser melted zone, was formed where the hardness is greater than those indicated by the linear relationship. One phase of TiN contained a large quantity of nitrogen, and the other phase of αTi contained little nitrogen. It is found that the lamellar structure composes of αTi and Ti-nitrides (TiN and TiN0.26). It is also observed that a wide area of αTi possesses a twin structure with a high dislocation density.
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Hiroshi Hosono, Kazuhiro Takio, Hideyuki Kuwahara, Kazuo Ichii, Toshio ...2005 Volume 69 Issue 7 Pages 517-522
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSIn order to evaluate dissolved nitrogen concentration penetrated during nitriding reaction of Fe-(5, 10, 14, 20 and 30)mass%Cr alloys, the specimens of 1 mm in thickness were nitrided at various partial pressures of nitrogen (pN2: 0.081, 0.051, 0.020, 0.002 and 0.001 MPa) for 36 ks at 1023 and 1223 K, respectively.
Only CrN was precipitated in the nitrided layer of the Fe-5 mass%Cr alloy, nitrided at 1023 K under any pN2 studied, whereas CrN and Cr2N were for the alloy more than 10 mass%Cr at 1023 K. On the other hand, only CrN was precipitated for the alloys with 14 and 20%Cr nitrided at higher pN2 than 0.051 MPa at 1223 K. CrN and Cr2N were detected for the alloys with 20 and 30%Cr at 1023 K. Furthermore, some Fe-Cr alloys had no precipitation after nitriding them under a definite condition of pN2 and mass%Cr. Based on these experimental results, foils of Fe-Cr alloys with about 100 μm in thickness were nitrided at 1223 K to measure nitrogen solubility. Using the standard Gibbs energy of formation of CrN after the literature, the solubility limits of nitrogen in Fe-Cr alloys were obtained as;
0.12 mass%N for Fe-3 mass%Cr alloy, 0.15 mass%N for Fe-5 mass%Cr alloy.
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Akira Terayama, Hideki Kyogoku, Masaru Sakamura, Shinichiro Komatsu2005 Volume 69 Issue 7 Pages 523-529
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSThis paper presents the fabrication condition of the TiNi alloy powder by mechanical alloying and its shape memory characteristics of the sintered alloy. The effect of mechanical alloying condition on the characteristics of mechanically alloyed powder (MA powder) was investigated. Also, the difference in sintering behavior between the MA powder and the mixed elemental powders by V-blender and the microstructure, shape memory characteristics of the sintered alloys were also examined. The MA powder was fabricated by milling using a planetary ball mill in rotational speed from 200 rpm to 500 rpm for various milling times in an atmosphere of Ar gas. These two types of powders prepared in different processes were sintered by a pulse-current pressure sintering equipment at various sintering temperatures. The powder agglomerated and its particle size became larger with an increase in milling time. The mixture of Ti and Ni powders changed into an amorphous state by processing for 3.6 ks over 300 rpm. The alloy sintered by the MA powder showed more uniform phase of TiNi than that by the mixed elemental powders sintered in a same manner, however, the former showed a lower density than the later due to a larger particle size of its MA powder of before-sintering.
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Toshikazu Akahori, Mitsuo Niinomi, Hiroyuki Toda, Konosuke Yamauchi, H ...2005 Volume 69 Issue 7 Pages 530-537
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSTensile and fatigue properties are important mechanical properties in drawn wires for biomedical and dental applications because of the credibility against the monotonic loading fracture or fatigue failure. The mechanical properties and deformation behavior of drawn wires of Ti-29Nb-13Ta-4.6Zr with diameters of 1.0 mm and 0.3 mm (designated as TNTZd1.0 and TNTZd0.3) were investigated to know a potential for biomedical and dental applications in this paper.
The microstructure of forged Ti-29Nb-13Ta-4.6Zr subjected to a solution treatment at 1063 K (TNTZST) comprises a single β phase with an average diameter of 25 μm. While that of TNTZd1.0 comprises a needle-like single β phase elongated parallel to the drawing direction. Tensile strengths of TNTZd1.0 and TNTZd0.3 are approximately 740 MPa and 800 MPa, respectively. While both elongations are nearly equal to each other (approximately 5.0%). The elastic modulus of TNTZd1.0 is approximately 50 GPa and that slightly smaller than approximately 55 GPa of TNTZd0.3. The notch-fatigue limit of TNTZd1.0 is 250 MPa. TNTZST exhibits the maximum elastic strain of approximately 1.4%. And the stress-strain curve shows a single gradient during elastic deformation region. The stress-strain curves of TNTZd1.0 and TNTZd0.3 in the elastic deformation region show two gradients, and the values of the maximum elastic strains in both wires are approximately 2.9% and 2.8%, respectively.
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Hiromi Takabayashi, Masahiro Kitada, Katsuhiro Tsujimoto2005 Volume 69 Issue 7 Pages 538-543
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSThe discoloration and chemical composition changes of red-lead used for wood-block print made in the late Edo period have been investigated. Both the chromaticity and lightness of red-lead decrease with discoloration, and its hue exhibits very little change. This is due to the reflectance decrease of red-lead in a long-wavelength range beyond the absorption edge of 580 nm. Red-lead is a mixture of Pb3O4 and β-PbO and has a grain size of 0.05-0.2 μm. The X-ray diffraction intensity of β-PbO considerably decreases with discoloration in comparison with that from Pb3O4. This result shows that β-PbO is more reactive than Pb3O4 in the mixture. The results of XPS measurement suggest that both lead chloride and lead carbonate exist in the surface layer of red-lead.
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Satoshi Okano, Hisashi Kuwano2005 Volume 69 Issue 7 Pages 544-547
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSA duplex stainless steel composed of 23% ferrite and austenite has been aged at 593 K. A change in the mean internal magnetic field of Fe in ferrite has been confirmed by Mössbauer spectroscopy with increasing aging time. The result is attributed to the compositional change owing to the phase decomposition of ferrite. A mottled structure characteristic of the spinodal decomposition was observed by TEM at the aging time of 180 ks(50 h). After aging 360 ks(100 h), precipitates were observed as black spot in the bright field images of TEM. The precipitate is interpreted as Cr-rich phase by HAADF-STEM observation. The volume fraction of the Cr-rich phase has been measured as a function of aging time by Mössbauer spectroscopy and TEM observation. Both result showed a fairly well agreement with each other. The decomposition fraction of ferrite y is expressed by a sigmoidal function,
y=1-exp (-ktn)
where n=0.67.
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Hiroaki Nakano, Masayuki Matsuno, Satoshi Oue, Masaaki Yano, Shigeo Ko ...2005 Volume 69 Issue 7 Pages 548-554
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSThe electrodeposition of Fe-Ni alloys was performed galvanostatically in the sulfate solutions of pH 1-3 at 40°C and the alloy deposition behavior was compared with that of Zn-iron-group metal alloys to investigate their codeposition mechanism. The deposition behavior of Fe-Ni alloy showed a typical feature of the anomalous codeposition, in which electrochemically less noble Fe deposits preferentially under most plating conditions. The anomalous codeposition behavior in Fe-Ni alloy deposition was evidently dependent on the pH buffer capacity of the solutions. This can be explained in terms of the preferential adsorption of FeOH on the deposition sites of more noble Ni due to the extremely smaller dissociation constant of FeOH+ than NiOH+ in the multi-step reduction process of hydrated iron-group metal ions.
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Yasushi Sasajima, Minoru Ichimura2005 Volume 69 Issue 7 Pages 555-559
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSUnidirectional solidification experiments of a model alloy of succinonitrile (SCN)-acetone that is a transparent organic compound and is available for a direct observation were performed in order to clarify the solidification process of binary alloy. The dependences of primary arm spacing (DAS1) of dendrite and secondary arm spacing (DAS2) on the growth speed of a crystal were studied.
The sample, heareafter called as the cell, was inserted into the gap of the two slides (26 mm×76 mm×1.3 mm each), of which distance was 200 μm. The cell was pulled at a constant speed V toward the low temperature side under the fixed temperature gradient (1 K/mm). Changing pulling speed of the cell controlled the growth speed of the crystal.
The composition of the examined samples is SCN-1.9 mass% acetone and SCN-6.0 mass% acetone. DAS1-V relationship was studied for the 1.9 mass% case only and found to be in proportional with the growth speed V-1/2. This is almost the same as that of unidirectional solidification of aluminum-(0.1-6.9) mass%Si alloy. DAS2 of 1.9 mass% and 6.0 mass% changed with growth speed as V-1/3.
However, when growth speed increased, DAS2 of 1.9 mass% and 6.0 mass% decreased more than the V-1/3 relationship. DAS2 of 6.0 mass% separated from the curve of V-1/3 earlier than that of 1.9 mass%.
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Kinji Saijo, Kazuo Yoshida2005 Volume 69 Issue 7 Pages 560-566
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSThe effect of surface roughness on the bond strength in aluminum/steel and copper/steel joined by low-temperature surface-activated bonding was examined. The greater the surface roughness, the greater the bonding pressure that was required to achieve tight bonding that resisted peeling up to the point where the aluminum or copper plates fractured. In the case of aluminum/steel, the aluminum, whose surface roughness was 0.3 μmRa, bonded tightly with steel under 495 MPa of loading pressure. When the surface roughness of aluminum increased from 0.3 μmRa to 1.7 μmRa, the bonding pressure required to achieve tight bonding doubled. Copper with a surface roughness of 0.07 μmRa bonded tightly with steel under 750 MPa of loading pressure. When the surface roughness of copper increased from 0.07 μmRa to 0.38 μmRa, the bonding pressure required to achieve tight bonding was essentially unchanged. But when the copper roughness increased to 1.47 μmRa, 1/3 more bonding pressure was needed to achieve tight bonding.
The surface roughness of each metal was significantly increased by RF ion etching for individual reasons. The surface of copper was roughened because the Ar ion-sputtering yield is so strongly dependent on the orientation of crystal planes. In contrast, the aluminum surface was only slightly roughened due to the crystal plane effect. But the aluminum sample included many intermetallic compounds, whose ion-sputtering yields differ from aluminum. These differences also make the surface rough.
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