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Volume 66, Issue 9
Displaying 1-24 of 24 articles from this issue
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Tetsuya Ozaki, Yi Zhang, Masao Komaki, Chikashi Nishimura2002 Volume 66 Issue 9 Pages 857-860
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSNovel preparation process of V-Ni alloys for hydrogen purification membrane using chemical transport was investigated. Vanadium, NH4Cl, and PtCl2 as evaporating source were put in one side of a fused-silica tube, and Ni substrate was put in the other side. The fused-silica tube was sealed in vacuo, and set in a furnace with temperature gradients. Evaporating source temperature was 1173 K. Substrate temperature was higher or lower than the evaporating source temperature. HCl was formed from NH4Cl and PtCl2. Vanadium was chemically transported under temperature gradient via chlorides in the presence of HCl and diffused into the Ni substrate. After the treatment, weight and thickness of the substrate increased by diffusion of V into it. Maximal amount of V diffused into the Ni substrate with the substrate temperature of 1197 K. Vanadium content obtained by EDX analysis, 33-80 at%, was higher than that estimated from the weight increase, 10-25 at%, suggesting that the substrate after the treatment was not homogeneous and V-rich phases were formed at the substrate surface. When the substrate temperature was lower than the source temperature, Ni2V phase was observed. When substrate temperature was higher than source temperature, fcc and sigma phases were observed. Although chemical transport treatment of Ni onto V substrate was also attempted, Ni was not found in the substrate.View full abstractDownload PDF (514K) -
Hideo Yoshinaga, Seiji Dan, Akio Kawabata, Tetsuo Sakai2002 Volume 66 Issue 9 Pages 861-864
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSTin-based alloys are receiving much attention as new anode materials with high energy density for Li-ion secondary batteries. However, these alloys still show very poor cycle life because charge-discharge processes cause cracking and crumbling of the anode by large volume changes in the alloys.
In order to overcome the problem, we have proposed vanadium-based alloys which had very good ductility. Tin-vanadium alloys were successfully prepared by thermic process in which vanadium-oxide was reduced by Al-metal to vanadium-metal. The obtained Sn-V alloys are mainly composed of Sn3V2 phase containing tin impurity. Cycle life of the alloy anode was significantly improved by annealing it at 750°C because the amount of impurity tin was decreased greatly. The Sn3V2 alloy anode showed an initial rechargeable capacity of 500 Ah/kg, keeping 400 Ah/kg even after 50 charge-discharge cycles.View full abstractDownload PDF (330K) -
Yasuharu Yoshimura, Keiko Kanai, Kazuhiko Kita, Akihisa Inoue2002 Volume 66 Issue 9 Pages 865-868
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCold worked Cu-Zn alloys possess very high season cracking susceptibility. It is expected that the season cracking susceptibility of Cu-Zn alloys is reduced by adding appropriate elements. However, little is known about the relation between additional elements and the nature of the surface oxide film which is formed during the exposure in the anmonical environment.
In this paper, we intend to examine the effect of additional elements and cold working on the season cracking susceptibility of Cu-Zn alloys, and to develop a new Cu-Zn based alloy with a much lower susceptibility and good cold workability.
The results obtained under the JIS test condition indicate that a Cu-30 mass%Zn-1 mass%Si alloy has the lowest season cracking susceptibility which is nearly the same as that for Cu-20 mass%Zn alloy, due to the suppression of the formation of surface Zn-rich oxide film during exposure in an ammonical environment.View full abstractDownload PDF (571K) -
Akihiro Yamada, Mitsutoshi Shirota, C. L. S. Rizal, Takeshi Houga, Yuj ...2002 Volume 66 Issue 9 Pages 869-872
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSPulse electrodepositon is a useful technique with which it is possible to achieve atomic-scale control of the layer composition, thickness of the multilayer and the grain size in ferromagnetic films by regulating the pulse amplitude and width. It is possible to fabricate ferromagnetic films with various magnetic properties from a single electrolytic solution containing more than two kinds of metallic ions, by changing the step pulse wave. Multilayer films composed of a Ni-rich layer with high coercive force, an Fe-Ni layer with low coercive force, and a nonmagnetic Cu layer were produced by controlling the step pulse potential from a single electrolytic solution containing Fe, Ni and Cu ions. Moreover, we are able to produce thinner ferromagnetic films consisting of multiple layers with magnetic characteristics such as a wide variation in coercive force, high susceptibility, and large magnetoresistance effect by controlling the time interval of the step pulse.
In this study, we investigated the relationships between the magnetic field dependence of the magnetoresistance effect and the film preparation conditions for composition-modulated Fe-Cu-Ni alloy films produced by the pulse electrodeposition method. The MR ratio observed in the film has maximum values of 3.4% and 9% at 300 K and 5 K, respectively. A highly sensitive change of the electric resistance was obtained at a low magnetic field.View full abstractDownload PDF (339K) -
Tadaharu Yokokawa, Makoto Osawa, Kenji Nishida, Yutaka Koizumi, Toshih ...2002 Volume 66 Issue 9 Pages 873-876
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe partitioning behavior of platinum group metals (PGM) into γ matrix and γ′ precipitates for γ′ precipitation hardening Ni-base superalloys has been investigated using electron probe X-ray micro-analyzer (EPMA). The TMS-75 (Ni-12 mass%Co-3 mass%Cr-2 mass%Mo-6 mass%W-6 mass%Al-6 mass%Ta-5 mass%Re-0.1 mass%Hf) and five alloys with 1 at%PGM additions to TMS-75 were investigated. It became clear that in equilibrium state at 1100°C, Ir is slightly partitioned more into γ′ precipitates, Ru has a preference to partition into γ matrix, in contrast Rh, Pd and Pt are partitioned into γ′ precipitates, and the partitioning ratio of these elements is about Kiγ⁄γ′≈1⁄2. Furthermore, it appears that the partitioning behavior of refractory elements, such as W, Re, are not so changed by PGM addition, for example, Re is partitioned into γ matrix in any alloy (KReγ⁄γ′ is in range of 6 to 7.5).View full abstractDownload PDF (560K) -
Mari Nishi, Yuji Yamasaki, Ken-ichi Takagi2002 Volume 66 Issue 9 Pages 877-880
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIron base boride cermets show excellent mechanical properties, wear resistance, and high temperature properties. Recently, these cermets with oxide surface layer exhibited excellent corrosion resistance in a molten Al alloy. In this study, we investigated the relationship between structure of the oxide layer and corrosion resistance in a molten Al alloy for the cermet with the composition of 5%B-42.7%Mo-10.2%Cr-2.85%Ni-bal.Fe(%: mass%).
Thickness of the oxide layer increased with increasing the temperature and holding time. The cermet with the oxide layer formed from 973 to 1073 K exhibited excellent corrosion resistance. XRD and EDS analysis results indicated that the oxide layer consisted of two phase: an outer one of the Fe2O3 and an inner one of the (Fe, Cr)MoO4 which might contain B. After the corrosion resistance test in a molten Al alloy, the boride surface maintained the inner oxide layer. These results indicated that the inner oxide had excellent corrosion resistance against the molten Al alloy due to the tight bonding to the cermet and the formation of the dense oxide.View full abstractDownload PDF (501K) -
Kimihiko Kubo, Nobumitsu Hirai, Shigeta Hara2002 Volume 66 Issue 9 Pages 881-884
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn our laboratory, diffusion phenomenon in underpotential deposition (UPD) region has been studied so far. The effects of anionic species, Cl− and HSO4−/SO42−, in electrolyte solution on the diffusion phenomenon were investigated by combining electrochemical measurements with in situ electrochemical atomic force microscope(EC-AFM) observation. It has been confirmed experimentally that the inward diffusion of Cd to the Au(100) substrate is promoted when Cl− is present in electrolyte solution.View full abstractDownload PDF (433K) -
Yoshihiko Soeno, Yutaka Akashi, Hiromitsu Ino, Kiiti Siratori, Kenichi ...2002 Volume 66 Issue 9 Pages 885-888
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIt is important to assess environmental impacts of materials or products properly. But the typical method called Life Cycle Assessment has many problems. Above all, it is crucial that various kinds of environmental impacts cannot be integrated. We present an attempt to use the exergy concept to express environmental impacts. Exergy has been used to analyze thermal efficiency of the production process. However, to apply exergy to environmental problems, exergy of materials is important since chemical reaction of the wastes cause environmental problems. Exergy expresses gap of free energy between a given state and that of environment. Thus, the concept of exergy gives potential of environmental impacts. We analyzed impacts of life cycle of both steel and aluminum cans as an example. We have proposed a new diagram that represents exergy and mass flow in a system. The diagram consists of triangles and arrows. The three sides of triangle represent inputs, products and wastes of a unit process. The length and width of arrow express the magnitudes of exergy and mass, respectively. It was estimated that the total exergy of material wastes from life cycle of one thousand cans made of aluminum and steel are 540 MJ and 305 MJ, respectively. If the recycling rate is 100 per cent, the amounts of exergy are reduced to 49 MJ and 10 MJ. It is concluded that the present analysis based on exergy is useful to evaluate potential environmental impacts caused by mass discarding of materials. But it is still insufficient to evaluate impacts of trace toxic chemicals such as dioxin.View full abstractDownload PDF (271K) -
Hirotaka Ito, Hitoshi Saito, Shunji Ishio2002 Volume 66 Issue 9 Pages 889-892
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSPost-annealing effect on L10 ordering and coercivity in FePt compositionally modulated films was investigated. The films were prepared by radio frequency (RF) sputtering. The degree of compositional modulation was designed to vary from 30 at%Fe-Pt to 60 at%Fe-Pt with a period of a few atomic layers, and average composition of films was about 50 at%Fe-Pt. Post-annealing was done at temperature Ta (459 K∼861 K) for two hours. X-ray structural analysis revealed that L10 ordering begins at Ta≤553 K. Order parameter S and coercivity Hc are S∼0.6 and Hc∼0.3 MA/m at Ta=553 K, and S∼1.0 and Hc∼0.8 MA/m at Ta≥646 K, respectively. L10 ordering occurs through recrystallization, which takes place to reduce compositional modulation and strains.View full abstractDownload PDF (476K) -
Satoko Abe, Shinya Noguchi, Tetsumori Shinoda, Yoshihiro Oya-Seimiya2002 Volume 66 Issue 9 Pages 893-896
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSNb3Al is expected for practical application as a superconductive wire material. In this study, the compositional dependence of Tc for Nb-Al alloys, which were annealed at 1373 K, was investigated in the Nb-rich compositional range (from 18 to 23 at%Al). The value of Tc was evaluated by the specific heat measurement. The compositional distributions were analyzed by EPMA, and the phases were refined by powder X-ray diffraction.
The 21.9 at%Al specimen, in which only Nb3Al existed, showed comparatively as high Tc (about 18 K) as that of the stoichiometry. On the other hand, in the 23.1 at%Al specimen, Nb3Al and Nb2Al coexisted. The 23.1 at%Al specimen had the same Tc as the 21.9 at%Al specimen. However, from the viewpoint of the superconductive property, the 23.1 at%Al specimen was better than the 21.9 at%Al specimen as a material because Nb3Al homogenized at the edge of the solute region (about 22 at%Al) by the precipitation of Nb2Al. It was indicated that Nb3Al alloy showed the good superconductive property which was almost the same at the stoichiometry despite of a relatively low annealing temperature of 1373 K.View full abstractDownload PDF (284K) -
Toshiharu Kobayashi, Yutaka Koizumi, Tadaharu Yokokawa, Hiroshi Harada2002 Volume 66 Issue 9 Pages 897-900
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSNi-base directionally solidified (DS) superalloys have the advantage of production costs over the single crystal (SC) superalloys because of better yield rate of casting and a simpler heat treatment compared with SC superalloys. In our previous work, we developed a third generation DS superalloy TMD-103 which exhibits good creep strength, equivalent with second generation SC superalloys. In this study, we attempt to develop a fourth generation DS superalloy that have better creep strength than TMD-103. To strengthen the grain boundaries of the new DS alloys, C and B were added to the fourth generation SC superalloy, TMS-138, that has good phase stability and a long creep life by Ru and Mo addition. Creep behavior of the as-cast and heat-treated new DS alloy is investigated. As a result of creep tests at 1100 degrees centigrade under a load of 137 MPa, the creep time at 1% strain in the heat-treated alloy is twice as long as that of TMD-103.View full abstractDownload PDF (716K) -
Yasubumi Furuya, Chihiro Saito, Teiko Okazaki2002 Volume 66 Issue 9 Pages 901-904
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSRapid-solidification method was applied to make the Fe-15 at%Ga ribbon whose thickness was about 100 μm with improvement of ductility. The Fe-15 at%Ga ribbon sample showed a very large magnetostriction of εmax=−400×10−6 in comparison with εmax=−40×10−6 for the conventionally melt-worked bulk material at applied magnetic field, 955 kA/m. In the bulk material with random crystal orientation, the dependence of magnetostriction on magnetization direction (θ) to the surface of ribbon was scarcely recognized. On the contrary, in rapid-solidified ribbon, that dependence was extraordinarily enhanced and large magnetostriction was obtained in the thickness direction of ribbon (θ\fallingdotseq90°) where coercive force showed the maximum value. Based on these experimental results, it is considered that the large magnetostriction is strongly correlated with special metallic microstructures in the rapid-solidified Fe-15 at%Ga ribbon with very strong magnetic anisotropy. Fe-Ga rapid-solidified ribbon has the promising possibility as a new magnetostrictive material as it has large magnetostriction, ductility and very small magnetostriction hysteresis.View full abstractDownload PDF (390K) -
Hayato Hashino, Tomoyuki Inoue, Kenji Gotouda, Hiromitsu Ino2002 Volume 66 Issue 9 Pages 905-908
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe forming ability of the Nd2Fe14(C, B) phase was investigated in melt-spun Fe90−zNd10(C, B)z (z=3, 5, 7, 9) alloys in which the ratio of carbon to boron was changed. The cooling rate of the molten sample was varied by changing the surface velocity of a single roller apparatus. It was confirmed that the substitution of a small amount of boron promotes the formation of the 2-14-1 phase in the samples z=3 to 7. The 2-14-1 phase is formed instead of Nd2Fe17CX phase with the substitution of 1 mol% boron abruptly. With increasing boron substitution, the Curie temperature of the 2-14-1 phase increases from 533 to 586 K, indicating the boron replacement of carbon in the 2-14-1 phase. On the other hand, in the alloys of the samples z=9, the volume fraction of the 2-14-1 phase increases with increasing boron substitution gradually, and the Curie temperature of the phase is almost constant (586 K) regardless of the ratio of carbon to boron in the alloys. The result indicates that carbon atoms are scarcely dissolved in the 2-14-1 phase. The magnetic properties are improved by the substitution of 15 to 40% carbon for boron as compared with the ternary Nd-Fe-B alloys. The (BH)max value reaches maximal 136 kJ/m3 in the sample Fe83Nd10CB6.View full abstractDownload PDF (404K) -
Takeshi Yamahira, Yoshiaki Shinya, Shizuka Tamoto, Mitsuru Aiba, Sumio ...2002 Volume 66 Issue 9 Pages 909-912
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSTi50Ni50−xCux(x=0, 5, 10, 15 at%) fine fibers(diameter=φ80 μm, length=20 cm∼1 m) were successfully developed by the arc-melted rapid-solidification method. It has been very difficult to do the conventional melt-work processing from the bulk material of this alloy to very fine fiber because of the brittleness of the especially in the range of Cu≥8 at%. The fibers showed good shape memory effect. As Cu content increased, the temperature hysteresis(=Af-Mf) of recovery strain-temperature curves as well as that in the DSC curves became smaller. The tensile strength showed more than 1000 MPa in Ti50Ni40Cu10 at%. Therefore, the developed rapid-solidified, thermoelastic fine fiber actuator/sensor materials have high potential for applications for micro-machines and the fillers of smart composites.View full abstractDownload PDF (348K) -
Seiji Fukuyama, Dongsheng Sun, Kiyoshi Yokogawa2002 Volume 66 Issue 9 Pages 913-916
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSHydrogen embrittlement (HE) of niobium was investigated in 1.1 MPa hydrogen and helium from room temperature to 80 K with the strain rates of 4.2×10−2∼4.2×10−5 s−1 by using the specially designed equipment. HE increased with decreasing temperature, reached a maximum, and then decreased rapidly with decreasing temperature. The maximum HE temperature decreased with decreasing strain rate, namely HE increased with increasing strain rate above 200 K while that increased with decreasing strain rate below 200 K in result. Cleavage fracture was mainly observed in hydrogen, while ductile rupture was observed in helium. Dimple rupture was also observed in hydrogen below 100 K. It is discussed that HE is caused by hydride formation at the crack tip, where HE above 200 K is controlled by the fracture of the hydride and that below 200 K is controlled by hydrogen diffusion to form the hydride.View full abstractDownload PDF (515K) -
Kenichi Nakajima, Yohji Uchiyama, Kohmei Halada2002 Volume 66 Issue 9 Pages 917-920
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIt is needed to investigate process chain of each material for clarifying the environmental improvement by industrial materials recycling.
The study aims at investigating amounts of steel processing scraps generated by the Japanese industry in order to develop materials flow analyzed by an input-output table. The ratio of generated scraps per steel consumption and the ratio of shipment scraps per steel consumption in each industry were estimated based on the data investigated by the Japan Ferrous Raw Materials Association. The deviation of ratios was calculated for discussing the accuracy of the estimation.View full abstractDownload PDF (336K) -
Masahiko Kai, Atsushi Inoue, Saburo Hoshi, Katsumi Nomura, Xin Yao, Te ...2002 Volume 66 Issue 9 Pages 921-924
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSMany applications of the superconducting magnets using high-Tc oxide superconductors are expected to operate in a persistent current (PC) mode. For the PC mode operation, a PC switch (PCS) is considered to be an essential device. The special properties are required for the PCS material, which is not only a high critical current but high electric resistance in the normal state in order to cut off the current flow efficiently through switching.
The liquid phase epitaxy (LPE) method could afford REBa2Cu3Oy (RE123) thick films with a high critical current density in the superconducting state and a reasonable electric resistivity in the normal state. However, the long current pass is necessary to achieve a required value for the application such as several ohms of its electric resistance. In this study we have studied to fabricate a meander shaped LPE film to realize a high electric resistance in the normal state. The seed film on an MgO single crystalline substrate was shaped into a meander type by the chemical etching method and dipped into the solution for the LPE growth. The meander shaped RE123LPE film with a long current path on the MgO substrate of 2 inches in diameter could be successfully grown. This phenomenon could be explained by the change of the growth mode in the side wall from step growth to that limited by the nucleation on a(b)-c plane. This is introduced by the small step-advancing rate of the RE123 crystal on the MgO surface and above the dissolved MgO substrate. The film revealed a high resistance value of 1.7 Ω at 100 K.View full abstractDownload PDF (526K) -
Masayuki Sagara, Kazuhiko Noda, Yasuyuki Katada, Toshiaki Kodama2002 Volume 66 Issue 9 Pages 925-928
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn the generation and growth process of crevice corrosion, it is considered that pH of the solution inside the crevice decreases because of hydrolysis reaction by metallic ion. In this study, in-situ measurement for surface pH distribution of the stainless steel in crevice corrosion process was carried out by a scanning chemical microscopy (SCHEM) using photo current characteristics of semiconductor.
17%Cr-14%Ni-2%Mo austenitic stainless steels were used as test specimens. Test specimens were immersed in artificial seawater with addition of hydrogen peroxide. As a result of the tests, although surface showed uniform pH distribution in early stage, the decrease of pH at one area near the crevice was observed in latter stage. The area extended as the time passed. This area almost agreed with the position at which crevice corrosion occurred. From these results, it was proven that SCHEM was promising to investigate crevice corrosion behavior of the stainless steel. The effect of nitrogen in stainless steel on the crevice corrosion resistance was also investigated.View full abstractDownload PDF (366K) -
Takeshi Hara, Masayoshi Nishiyama, Masayuki Sato, Nozomu Izumi, Saburo ...2002 Volume 66 Issue 9 Pages 929-934
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSWe have prepared a single-phase film of NaCl-type iron-nitride in order to re-investigate its magnetic property. We have observed 57Fe Mössbauer spectra of NaCl-type Fe-N0.63 films prepared with the contamination of air in Ar-N sputtering gas. The magnetic components are not the intrinsic property of the NaCl-type iron-nitride but owing to oxide formation.
To search an optimum condition for synthesizing the NaCl-type iron-nitride without oxidation, we prepared specimens on Kapton substrate by using a Helicon sputtering system under various substrate temperature and RF power to coil in a mixture of Ar and N2 gas. Partial pressure ratio of P(N2)⁄P(Ar) was kept at 20 in an atmosphere of high concentration N2 gas. The amounts of NaCl-type iron-nitride formed on the substrate increases with an increase of RF power to coil, being independent on the substrate temperature. It also increases rapidly with decreasing the substrate temperature blow 90 K. A single phase film of NaCl-type FeN with a lattice constant of 0.457 nm have been obtained under the condition of RF power to coil of 150 W and the cooled substrate of 90 K. From 57Fe Mössbauer measurements, we have newly found that the NaCl-type iron-nitride shows no magnetic order but is paramagnetic at 4.5 K.View full abstractDownload PDF (484K) -
Ken’ichi Miura, Itsuo Ishigami2002 Volume 66 Issue 9 Pages 935-943
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSTitanium nitride films were deposited onto substrates of stainless steel, SUS304, by varying film thickness, substrate temperature, substrate bias voltage and total gas pressure. The protective quality was evaluated by the electrochemical test in accordance with critical passivation current density method where a deaerated solution of 0.5 kmol/m3 H2SO4-0.05 kmol/m3 KSCN was used as an electrolyte. Scanning electron microscopy was used to examine surface morphology and cross-sectional fracture of the films. Residual stress in the films was determined by using sin2ψ method. An increase in film thickness brought about high protective quality. The protective quality was improved with increasing substrate temperature; pores in the size of micron order were observed on all parts of the surface of the films deposited at lower substrate temperatures, while few pores existed on the films deposited at higher temperatures. This result indicates that these pores are one of the factors influencing on the protective quality. The film deposited without any substrate bias voltage had morphology with a typical columnar structure of a zone I structure according to the classification by Thornton, and showed complete protectiveness. Increasing the bias voltage the protective quality deteriorated, whereas an excess increase in the bias gave rise to slightly higher protective quality. The films with lower compressive stress had few pores and possessed higher protective quality. This result suggests that the formation of the pores originate in the compressive stress. Although a decrease in total gas pressure gave rise to higher compressive stress, the protective quality became higher; the contradiction is comprehensible by taking high orientation of the films into account.View full abstractDownload PDF (1201K) -
Ken’ichi Miura, Itsuo Ishigami2002 Volume 66 Issue 9 Pages 944-949
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCorrosion resistance of stainless steel, SUS304, coated with titanium nitride films deposited under different substrate bias voltage was studied. Tow types of tests were employed to evaluate corrosive behavior of coated substrates: one was by exposing the substrates to the gas generated through hydrolyzing a resin mixture of ABS and PVC at 433 K under a pressure of 2.5 MPa, and the other was to measure the change in anodic current density of coated substrate at −200 mV vs. Ag/AgCl(3.33 kmol/m3KCl) in a 0.5 kmol/m3 H2SO4-0.05 kmol/m3 KSCN solution at 298 K with immersion time. Residual stress of the films was determined by using sin2ψ method. Corrosion tests indicated that the coated substrates corroded more rapidly as the compressive stress in the film increased. The effect of compressive stress on maintenance of corrosion-protective quality of the films was quantitatively treated. The increase rate of the substrate area exposed to electrolyte through the pores in the film was estimated from a variation rate of an anodic current density versus immersion time. This work indicated that a decrease in compressive stress makes great contribution to maintenance of the protective quality.View full abstractDownload PDF (621K) -
Toshiro Tomida, Shigeo Uenoya, Naoyuki Sano2002 Volume 66 Issue 9 Pages 950-957
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCube texture development in 3%Si steel and doubly-oriented electrical steel sheets by oxide-separator-induced decarburization have been investigated. Decarburization anneal of 3%Si-1%Mn-0.05%C steel sheets by using a SiO2-containing separator led to a remarkable development of the cube texture {100}⟨001⟩. More than 90% of grains in the decarburized material well aligned to the cube orientation, and the grain size was about 0.4 mm. Cube-oriented nuclei emerged during primary recrystallization after a proper double-stage cold-rolling prior to the decarburization, and they selectively grew in decarburized α-ferrite layers. The doubly oriented Si-steel sheets by this process showed a large magnetic induction, low core losses and a low magnetostriction in the rolling and transverse directions. The mechanism of the cube texture evolution is discussed.View full abstractDownload PDF (947K) -
Sumiko Sanuki, Kazuyuki Nakagawa, Tomoko Kato, Shigeru Nagaoka, Hirosh ...2002 Volume 66 Issue 9 Pages 958-965
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSReddish cuprous oxide crystals can be readily formed by irradiating an aqueous alkaline Cu(II) solution containing suitable complexing agents with UV or sunlight in the presence of a photocatalyst such as TiO2 or ZnO. Various factors, including the Cu(II) concentration, pH of the Cu(II) solution, amount of TiO2 catalyst, method used to agitate the test suspension, concentration of potassium sodium tartarate, and intensity of UV radiation, affecting cuprous oxide preparations were investigated. Concentrations of Cu(II) and potassium sodium tartarate have no significant effect on reaction rates, while pH, and amount of TiO2, play important roles in the reaction. The dispersion of TiO2 in Cu(II) solution is another important factor. Cu(II) reduction is not affected as far as the Cu(II) concentration plotted against the cumulative intensity of UV radiation is concerned. It is necessary to stop the cuprous oxide formation before the complete reduction of Cu(II), since metallic copper is formed on cuprous oxide.View full abstractDownload PDF (1137K) -
Sumiko Sanuki, Kazuhiko Ito, Hiroshi Majima2002 Volume 66 Issue 9 Pages 966-972
Published: 2002
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA possible method to recovery Se0 by introducing H2Se gas generated by photocatalytic reaction in an aqueous solution containing Se(IV) was experimentally studied. Assuming a proposed flowsheet for Se0 recovery, the related problems for this process were examined. The principal results obtained are as follows: 1) H2Se gas evolved by photocatalytic reduction can be absorbed in an aqueous Se(IV) solution, resulting Se0 generation according to the following reaction.: 2H2Se+Se(IV)=3Se0+4H+. 2) Produced Se0 fine particles present red color, and sodium formate, sodium citrate and sodium sulfate are effective aggregation agents for Se0. 3) A process consisting of photocatalytic reduction of waste water containing Se(VI) and Se(IV), Se0 recovery by absorbing H2Se in Se(IV) solution, was assumed as possible method. 4) The presence of sulfate ion in waste water greatly disturbed the progress of photocatalytic reduction of Se(VI) and Se(IV). 5) Formic acid was found as most effective pH regulating agent to acidify waste water exhausted from Se0 recovery circuit, and this reagent also useful as reductant to prohibit the recombination of reduced product and positive hole generated on photocatalytic reaction. And 6) Repeated use of TiO2 catalyst was efficiently done under the high intensity of UV light irradiation.View full abstractDownload PDF (367K)
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