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63 巻, 8 号
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三浦 健一, 石神 逸男, 水越 朋之1999 年 63 巻 8 号 p. 949-958
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe influence of process parameters on nitrogen-to-titanium ratio, [N]/[Ti], has been investigated. Titanium nitride films were deposited onto substrates of high speed steel, SKH51. Chemical composition of the films was determined through the quantitative analysis method proposed before for electron probe microanalysis. Hardness was measured by Vickers hardness indentation at 0.098-0.49N loads. Process parameters which elevate the substrate temperature bring about a higher ratio [N]/[Ti]. Depth profile by glow discharge spectrometry revealed that the ratio decreased in the direction toward a film-substrate interface. Higher deposition rates of titanium on the substrate reduced the ratio. The ratio increased remarkably by applying a little bias voltage to a substrate, whereas an excess increase in the voltage decreased the ratio slightly. The ratio reduced as total gas pressure lowered; the result is probably due to a decrease in nitrogen partial pressure and to an increase in deposition rate of titanium on a substrate. Although a decrease in gas mixture ratio, [N2]/[Ar+N2], reduced nitrogen partial pressure, the change of the ratio [N]/[Ti] was slight; this must be attributed to a decrease in deposition rate of titanium on the substrate. Attempts have been made to clarify the relationship between the ratio [N]/[Ti] and film hardness. Hardness increased with decreasing the ratio from stoichiometry within the region of single-phase TiN. Also, the in-plane lattice parameter increased simultaneously. These results imply that internal compressive stress in the films affected the hardness. Results show that a variation in the hardness with composition cannot be due to the ratio [N]/[Ti] of TiN but rather to other factors e.g., grain size and strain. Precipitation of α-Ti in the films containing Ti2N causes the hardness to decrease. For single-phase α-Ti, an increase in the nitrogen content gave rise to a remarked increase in the hardness.抄録全体を表示PDF形式でダウンロード (1101K) -
折茂 慎一, 池田 一貴, 藤井 博信, 猿木 俊司, 福永 俊晴1999 年 63 巻 8 号 p. 959-964
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe purpose of this work is, first, to get precise information about the thermal stability and the site-occupation of hydrogen (deuterium) in the MgNi-H(D) system with an amorphous single phase, and then to clarify the origin of its hydriding properties from a viewpoint of the short range ordering. The sample was prepared by a mechanical alloying (milling) method, and the structural and hydriding properties were characterized by X-ray and neutron diffraction measurements, and by electrochemical p-c(hydrogen pressure-composition) isotherm measurement. The following results were obtained; (1) The amorphous single phase was prepared by milling for 80 h, after the solid-phase reaction between elemental Ni and nanostructured Mg2Ni. (2) The p-c isotherm clearly shows that there is a miscibility-gap (plateau), even in the amorphous phase. The hydrogen pressure of the miscibility-gap is located around 3×10−4 MPa at room temperature. (3) Hydrogen (deuterium) occupies the tetrahedral site composed of nearly [2Mg2Ni] in a wide range of hydrogen compositions. (4) The origin of their notable hydriding properties is the short range ordering in the amorphous single phase similar to the CsCl-type cubic structure. The single miscibility-gap in the system is also of importance.抄録全体を表示PDF形式でダウンロード (678K) -
前田 純也, 清木 晋, 和泉 輝郎, 塩原 融1999 年 63 巻 8 号 p. 965-969
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーYBCO/Ag superconducting rods prepared by the unidirectional solidification method were dipped into molten silver in order to fabricate low resistance metal contacts on the surfaces of the superconductors. In the case of dipping into a pure molten silver, a copper deficient reacted layer was formed at the boundary between YBCO/Ag superconductor and molten silver, although the temperature of the silver melt was lower than the melting temperature of the YBa2Cu3Ox/Ag phase. The formation of this reaction layer can be suppressed by means of the addition of YBa2Cu3Ox powder into the molten silver.抄録全体を表示PDF形式でダウンロード (697K) -
宗廣 修興, 藤井 敬二, 藤井 博信, 折茂 慎一1999 年 63 巻 8 号 p. 970-976
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーEffect of mechanical grinding (MG) under argon and hydrogen atmospheres on structural and hydriding properties were investigated in detail. In MG-LaNi5 under argon atmosphere, the grain size reaches ∼20 nm for MG times of 60 min and almost remains unchanged for more longer MG times. The pressure-composition isotherm (P-C) in LaNi5 at room temperature indicates an enhancement of hydrogen solubility, a lowering of plateau pressure and a narrowing of width of plateau by MG like FeTi but not Mg2Ni. On the other hand, in reactive MG (RMG)-LaNi5 under hydrogen atmosphere, a nanocrystallized LaNi5H0.15 and amorphous phases coexist within 180 min of grinding time. For RMG times longer than 180 min, the nanostructured LaNi5H0.15 phase disappears and the remaining amorphous-LaNi5Hx dissociates into nano-Ni+LaNiyHz(y<5). The P-C isotherm indicates no-plateau in the LaNi5 produced by RMG longer than 60 min and the hydriding properties become worse and worse with increasing RMG times. From these results, we conclude that the hydriding properties could not be improved by structural modifications in the system containing metals with strong affinity for hydrogen like rare earth metals.抄録全体を表示PDF形式でダウンロード (586K) -
春名 匠, 山本 雅則, 柴田 俊夫1999 年 63 巻 8 号 p. 977-982
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーEnvironment-assisted Cracking (EAC) of Ti in methanol solutions containing various concentrations of HCl has been investigated by using a slow strain rate testing apparatus with a dynamic observation system. In the EAC test, dissolved oxygen and water content were strictly controlled because it is known that these two factors influence the cracking of this system. It was observed that cracks initiated from black pits which were generated during the test, and that the cracking mode was intergranular and transgranular at the initial and the final stage of the crack propagation, respectively. Cracking occurred at 0.004 to 0.04 and 0.0004 to 0.04 kmol·m−3 HCl for initial strain rates of 8.3×10−7 and 2.5×10−6 s−1, respectively. This behavior was also influenced by electrode potential, that is, the cracking occurred above a critical potential depending on the concentration of HCl. The critical potential was expressed as a negative function of a logarithm of the concentration of HCl, and the potential was lowered as the initial strain rate increased. It was concluded that initiation of EAC for this system is mainly controlled by an anodic localized corrosion mechanism.抄録全体を表示PDF形式でダウンロード (1068K) -
大橋 修, 吉岡 隆幸, 新田 勇, 長谷川 宏, 杉井 伸吾1999 年 63 巻 8 号 p. 983-988
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe effects of various sintering conditions on the density and tensile properties of copper powder compacts were investigated in an effort to elucidate the sintering mechanism of pulse electric current sintering, by observing the waveforms of electric current and voltage, the actual temperature and the fracture surface of specimens. The results are summarized as follows:
The density, tensile strength, area reduction and elongation of sintered tensile specimens were increased with an increase in applied load and observed sintering temperature. The tensile properties of the sintered specimens were improved using a large initial electric current to heat the specimens. The heat generation at the site of the carbon punch is greater than that at the site of the specimens. The specimens are heated by heat conduction from the carbon punch. Therefore, in the actual sintering, the temperature of the specimens is higher than the temperature observed in monitoring, and the sintering is promoted when a large initial current is applied. There was noise in the waveform of the electric current, and this is considered to be due to the generation of discharge phenomena.抄録全体を表示PDF形式でダウンロード (657K) -
上田 康1999 年 63 巻 8 号 p. 989-993
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーDissolution rates of sintered alumina in molten CaO-SiO2-Al2O3 slags at 1793, 1828 and 1863 K were measured by the rotating disk method. The alumina contents of the slag were 10, 20, and 30%, and the CaO/SiO2 ratio was 1.
The dissolution rate of alumina was linearly related to the square root of the specimen rotation rate. This result suggested that the dissolution process was controlled by mass transfer in the boundary layer of molten slag.
The dissolution rate decreased with increasing alumina content of the slag, and the diffusion coefficient of alumina was almost unchanged. The decrease of the dissolution rate was due mainly to a decrease of the driving force.
The dissolution rate and the diffusion coefficient of alumina increased with rising temperature. The increase of the dissolution rate was due mainly to the increased alumina diffusion coefficient.抄録全体を表示PDF形式でダウンロード (390K) -
末光 毅, 西尾 光司, 井頭 賢一郎, 元島 栖二1999 年 63 巻 8 号 p. 994-1001
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーIn the course of developing a high-efficiency ceramic gas turbine capable of withstanding intense heat conditions, we developed a turbine nozzle composed of separate ceramic parts assembled and then wound with ceramic-fiber-reinforced material. We synthesized silicon carbide on the surface of the carbon fiber of a three-dimensional fabric using chemical vapor infiltration (CVI) and a silicon carbide film formed at 1300 K and above. The lower the deposition temperature, the lower the deposition rate, but the differences in the deposition rate on the surface and inside the fabric became smaller. After heat cycle tests, a turbine nozzle model with a matrix formed by CVI exhibited residual strength that was nearly twice that produced by conventional methods. We attribute this to the silicon carbide film formed by CVI inhibiting oxidation damage to the ceramic fiber.抄録全体を表示PDF形式でダウンロード (1843K) -
菅原 茂夫, 渡辺 慈朗1999 年 63 巻 8 号 p. 1002-1008
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe (001) surface of a white-tin crystal was etched with a HCl-NH4NO3-CuSO4 solution (288 K) in order to form etch-hillocks at dislocation sites, and their shape and growth rate were investigated by replica electron microscopy. The hillocks took the shape of a square pyramid surrounded with lateral surfaces of {011} planes and often showed traces of Cu precipitates on their apices. Their height and width increased with etching time at rates of 5.2×10−9 and 9.4×10−9 m/s, respectively.
Moreover, etch patterns of some surfaces belonging to the [100] and [11\bar1] zones were observed by optical microscopy. The dissolved thickness of their surfaces was measured by two-beam interferometry. In the [100] zone, flattened pyramidal hillocks formed only on the surfaces which were inclined gently to a (001) surface relative to the inclination of a (011) surface; no hillock formed on the surfaces belonging to the [11\bar1] zone. On the other hand, the dissolution rates of the surfaces showed a minimum value of 1.9×10−9 m/s on a (011) surface, and their rates increased in both zones as the angular distance from a (011) surface increased. A maximum dissolution rate of 5.2×10−9 m/s was obtained on a (001) surface.
These results indicate that surface orientation as well as the two conditions of dissolution rate proposed by Batterman must be satisfied for the stable growth of etch-hillocks on the surface of white-tin crystal.抄録全体を表示PDF形式でダウンロード (1532K) -
篠崎 信也, 深見 直孝, 加来 浩, 向井 楠宏1999 年 63 巻 8 号 p. 1009-1014
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーA basic research study for improvement of plasma-sprayed alumina coatings has been conducted. The wettability of the molten manganese/alumina ceramic system was examined by the sessile drop method. A MnAl2O4 spinel layer was formed at the interface, suggesting the existence of wettability between the molten manganese and the spinel. When the spinel was dense, the contact angle was about 88 deg for the temperature range from 1573 K to 1623 K. When there were open pores in the spinel layer and a sintered porous spinel substrate was used, the contact angle exceeded 90 deg. Therefore, the effect of interfacial conditions on the wettability was discussed. Owing to the rapid vaporization of manganese, the contact angle decreased with time at temperatures of 1673 K and above.抄録全体を表示PDF形式でダウンロード (976K) -
王 栄光, 加藤 昌彦, 中佐 啓冶郎1999 年 63 巻 8 号 p. 1015-1021
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーA commercially supplied pure titanium was ion-implanted at 1.5 MeV with different doses of N2+ ranging from 5×1020 to 2×1021 ions per 1 m2, and the titanium hydride formation behavior was investigated in 10 mass% sulphuric acid aqueous solutions.
When the implantation dose is larger than 1×1021 ions per 1 m2, the titanium nitride is detected on the implanted surface by the atomic force microscope(AFM) and X-ray diffraction(XRD). According to the XRD analysis of the unimplanted specimen hydrogen-charged at a constant current density of 500 A/m2, the amount of hydride increases with increasing charging time and the whole surface is covered by hydride when the charging time is 12 ks. For all of the implanted specimens, on the other hand, the amount of hydride is less than that for the unimplanted specimens within the charging time of 12 ks. The amount of hydride on the specimen implanted with 1×1021 ions per 1 m2 is a little larger than those implanted with 5×1020 and 2×1021 ions per 1 m2. The observation by AFM supports the results of XRD analysis.抄録全体を表示PDF形式でダウンロード (982K) -
浅岡 照夫, 三尾 淳1999 年 63 巻 8 号 p. 1022-1028
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーAluminium ion implantation into near equi-atomic titanium-nickel alloy was carried out to clarify the effect of the surface characteristics on the shape memory properties in cyclic deformation. Obvious changes in deformation behavior were observed in the ion-implanted specimens. At a low implantation dose, the R phase accommodation process followed by the martensite phase deformation proceeded at a lower stress than that of the non-implanted alloy. On the other hand, stress-strain curves of the specimen which has a high implantation dose revealed the charactoristics of a mixed structure consisting of the R phase, the martensite phase and the austenite phase. In the latter case, the shape memory properties were degraded and almost disappeared after several cyclic deformations. Two factors were considered to explain these results: First, the residual stress field induced by implanted aluminium ions at the surface assiseted the R phase and the martensite accommodation stress. Second, a shift in transformation temperatures due to preferential sputtering of titanium atoms at the surface followed by a composition change. When the implantation dose was low, the first factor seemed to play a major role. When the implantation dose exceeded some critical value, the second factor was important. Thus we assume the mechanism in which the doformation in the surface region has a trigger effect, transmitting the deformation toward the inner region of the specimen.抄録全体を表示PDF形式でダウンロード (574K) -
田中 康徳, 時本 雄次, 福本 昌宏1999 年 63 巻 8 号 p. 1029-1035
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーFor the energy saving, thermoelectric conversion materials (TEC) are attracting much attention. However, the conversion efficiency of thermoelectric materials is remarkably low in the single element compared to the other conventional power generations. Therefore, the thermoelectric elements have to be composed as the thermo-module in which the huge numbers of the elements are connected. In many configurations of TEC, the thick coating may be advantageous in joining or laminating.
The plasma spraying, which was characterized to be a high deposition rate process, was used to fabricate the thick coating of the thermoelectric elements. We previously reported that β-FeSi2 thermoelectric coating could be fabricated by plasma spraying, and the thermoelectric property was the same as the bulk material.
In this study, the Si-Ge system was focused because of its excellent thermoelectric property in a high temperature range. Moreover, the spraying and some treatments were applied for improving the thermoelectric properties with the aim of clarifying the conditions to fabricate high performance Si-Ge TEC coating.
The results obtained are summerized as follows;
(1) MA-spraying process could be applied for the fabrication of SiGe thermoelectric coating.
(2) The boundary at the joined layers in the case of FGM coating was diminished by polishing the coating surface before spraying the next layer. Joint type FGM coating of Si-Ge doped with different fractions of P could be fabricated by plasma spraying.
(3) The thermoelectric coating made from the granulated powder had a quite fine and dense microstructure. The resistivity of the coating decreased to one-tenth of coating made from the conventional MA powder, and consequently its power factor reached the level over than that of the sintered body.抄録全体を表示PDF形式でダウンロード (1075K) -
吉岡 隆幸, 大橋 修, 渡辺 健彦1999 年 63 巻 8 号 p. 1036-1042
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーDiffusion bonding is a useful method to join different metals, though it is indicated that the tensile strength of the joint decreases due to the formation of oxide at the bonding interface.
In this study, diffusion bonding process was employed to make the joint of copper (tough pitch copper described as TPC, and oxygen free high conductivity copper expressed as OFHC) and several metals (molybdenum, nickel and platinum). The effect of oxygen content in the copper and kind of coupling metal on the tensile strength of the joint was investigated using XRD and SEM.
When TPC was joined to molybdenum or nickel, molybdenum oxide or nickel oxide formed at the bonding interface and the tensile strength of the joint decreased extremely. While when platinum was used as the coupling metal, the oxide did not form there.
In the case of OFHC, the oxide did not form at the bonding interface between OFHC and any metal.
These results could be explained thermodynamically. If TPC was joined to a metal, whose standard free energy of formation of oxide was lower than that of Cu2O, Cu2O dispersed in TPC was reduced and a metal oxide formed at the bonding interface. If TPC was joined to a metal, which had a higher standard free energy of formation of oxide than that of Cu2O, Cu2O remained stable and the oxide did not form at the interface.
In OFHC, oxygen is dissolved in copper, therefore the activity of oxygen must be considered for the calculation of free energy change. The calculated free energy change indicated that the oxide did not form at the bonding interface between OFHC and any metal.抄録全体を表示PDF形式でダウンロード (1043K) -
鄭 棟碩, 富田 洋祐, 榎 学, 岸 輝雄1999 年 63 巻 8 号 p. 1043-1052
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーLaminate materials of Nb/Nb-aluminide were in-situ fabricated with pure Nb and Al foils by hot pressing. A pressure of 15 MPa was applied at the final temperature of the four-step heat treatment cycle, and this process made the multi-layered materials where Nb and Nb-aluminide layers were well bonded. The major phase of the layer was identified to be NbAl3 phase by X-ray diffraction and SEM-EDS, and Nb2Al phase was also formed in the interface of Nb and NbAl3 layer. Therefore, the aluminide layer was stacked in the order of Nb/Nb2Al/NbAl3. The formation process of these phases is considered as, Nb(solid phase)+Al(solid phase)→Nb(solid phase)+Al(liquid phase)→Nb(solid phase)+NbAl3(solid phase)→Nb(solid phase)+NbAl3(solid phase)+Nb2Al(solid phase). Nucleation and growth of the NbAl3 phase in the first stage of the formation process is due to the solid Nb/liquid Al reaction, and the formation of the Nb2Al layer in the second stage is caused by the diffusion of Nb into the NbAl3 layer. The thickness of aluminide layers (NbAl3 and Nb2Al phase) well agreed with values calculated by the diffusion contorolled parabolic growth law.抄録全体を表示PDF形式でダウンロード (2358K) -
桐野 文良, 大友 茂一, 小礒 良嗣1999 年 63 巻 8 号 p. 1053-1061
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe influence of heating treatment on the crystal structure and magnetic properties of Al doped Fe-Ta-C nano-crystalline thin films were studied. Crystal Plane orientation of Fe in 9.8 mol%Al-doped Fe-Ta-C film changed from (110) to (200) and Hc increased after pre-annealing at 663 K which is lower than the crystallization temperature. Preffered orientation of Fe crystal Plane changed from (110) to (200) by substrate heating also. The crystal structure and magnetic properties changed very little when the heating rate from room temperature to the crystallization temperature of 863 K was 0.06∼0.15 K/s. On the other hand, when the cooling rate to room temperature from 863 K was 0.06∼0.30 K/s, TaC crystalline particle size at the lower cooling rate of 0.06 K/s was found to be larger than that at the higher cooling rate. The magnetostriction of Fe in 9.8 mol%Al-doped Fe-Ta-C thin film also increased to 1.8×10−6, at the cooling rate of 0.30 K/s.抄録全体を表示PDF形式でダウンロード (779K) -
武藤 侃, 川岸 秀一朗, 田上 道弘1999 年 63 巻 8 号 p. 1062-1068
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe purpose of this paper is to consider the effects of initial grain size and strain rate on the ductile behavior of a Cu-30 mass%Zn alloy under high temperature deformation, and the related microstructural changes associated with it. Salt bath tensile tests on specimens with initial grain sizes of 12, 22 and 45 μm were studied under various strain rates from 3.3×10−5 s−1 to 2.0×10−2 s−1 at 673 K. The elongation and the fractured optical microstructures of the specimens were investigated. Maximum elongation of the specimens occurred at an initial grain size of 12 μm under a strain rate of 6.7×10−4 s−1. In this case most of the microstructure of the specimens changed to a fine dynamic recrystallized structure. The possibility that the principal deformation mechanism of the fine structure is grain boundary sliding, similar to superplasticity should be considered. As a consequence, the specimens exhibit high elongation. Under the lower strain rates, dynamic recrystallization occurred, i.e. dynamic recrystallized fine grains were observed. The dynamic recrystallized grains grew after the deformation, and thus the elongation of the specimens decreased.By increasing the strain rate or the initial grain size, the slight dynamic recrystallized structure occurred around the initial grain boundary. The dynamic recrystallized structure zones are geometrically softer than the initial grains, and thus basal slip is likely to be the dominant mechanism. Therefore the specimens show low elongation and shear fracture. Furthermore, the extent of ductility depends on the shape of the cavity which is induced by the differences of the initial grain size and the strain rate.抄録全体を表示PDF形式でダウンロード (1919K) -
長谷川 信一, 小林 剛, 佐藤 幸一, 五十嵐 淑郎, 内藤 久仁茂1999 年 63 巻 8 号 p. 1069-1074
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーA simple pretreating method was studied for determination of trace elements in pure iron samples by inductively coupled plasma mass spectrometry (ICP-MS) using chromazurol B (CAB) as a separating reagent of iron. A proposed procedure involved the separation of iron-CAB chelate as precipitate by filtration through a membrane filter after adjusting the pH of the sample solution. A surfactant, TritonX-100, was added to the sample solution for solubilization of other metal-CAB chelates. The optimum condition for iron separation was pH 5, 5 cm3 of 0.01 M CAB and 5 cm3 of 1% TritonX-100. In this method, some trace elements such as Mn, Ni, Co, Cu, Mg, Zn, Cd and Tl were determined by ICP-MS using the filtrate. An acceptable result was obtained for certified standard samples with high sensitivity.抄録全体を表示PDF形式でダウンロード (503K) -
多田 英司, 野田 和彦, 熊井 真次, 水流 徹1999 年 63 巻 8 号 p. 1075-1082
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーCorrosion fatigue tests on a commercial iron were carried out in a borate buffer solution containing 5 mol/m3 NaCl to clarify the evolution mechanism of the damage current during cyclic straining. By analyzing the strain and current response induced by the triangular load waveform, it was found that the damage current steeply increased just after a threshold strain on the loading cycle and decayed after the maximum strain on the unloading cycle. In order to investigate the relationship between the deformation at the crack tip and the current response during decreasing strain, the current decay induced by the triangular strain was compared with that induced by the trapezoidal strain. It was found that the decay rate of the current induced by the triangular load waveform was faster than that induced by the trapezoidal load waveform. Therefore, this current response induced by the trapezoidal load waveform was simulated by assuming that this response was attributed to anodic dissolution and repassivation at the fresh surface emerged during the loading cycle. The simulated current was in good agreement with the current response measured in the experiment. Consequently, the damage current induced by the triangular load waveform can be attributed to the anodic dissolution and repassivation processes at the crack tip, fundamentally. However, it was found that this current is also influenced by the deformation at the crack tip during a decrease in the strain.抄録全体を表示PDF形式でダウンロード (705K) -
須藤 一1999 年 63 巻 8 号 p. 1083-1084
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーUltrahigh-strength mortar mixed with surface-oxidized silicon-carbide as a fine aggregate was prepared by means of press-casting followed by curing in an autoclave. The relation between modulus of elasticity up to 111 GPa and compressive strength up to 360 MPa of mortar mixed with silicon-carbide was discussed, and it was revealed that the contributions of the aggregate hardness and of the interfacial strength between the aggregate and the cement paste on the elasticity of mortar were important.抄録全体を表示PDF形式でダウンロード (169K)
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