巻号一覧
62 巻, 11 号
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島田 昌彦1998 年 62 巻 11 号 p. 977
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーPDF形式でダウンロード (117K) -
相原 智康, 正 朋祥, 川添 良幸1998 年 62 巻 11 号 p. 978-985
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe basic concept of the functionally graded material (FGM) is an active control of the structure of materials to be suitable for the object properties. This concept should be expanded to the atomistic level. In the present report, this idea is applied to the Ni(γ)/Ni3Al(γ′) (100) interface. Molecular dynamics simulation is performed to clarify the correlation between the atomistic structure of the interface and the microscopic elastic properties. The Ni-Al binary 64000 atom systems with the FGM and NFGM type interface structures are simulated at 298 K with Finnis-Sinclair potential. The spatial local distribution of the lattice constant, the site potential energies and the atomistic stress energies are analyzed under the strain free condition. The global and local changes of these properties are calculated for various elastic tensile conditions. The lattice constant misfit and the stress concentration at the interface is weakened by the application of the graded structure to the γ⁄γ′ interface. Under the elastic tensile condition, the stress gap at the interface is proportional to the tensile strain for the standard (NFGM) interface. On the other hand, in the FGM structural interface, such an increase of the stress gap is not observed. The atom level graded structure is certified to be effective to reduce the stress at the interfaces under elastic deformation conditions.抄録全体を表示PDF形式でダウンロード (933K) -
大森 守, 垣田 健, 大久保 昭, 平井 敏雄1998 年 62 巻 11 号 p. 986-991
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーWC powders have not been sintered by normal sintering and by hot press sintering without sintering additives. Spark plasma system (SPS) makes it possible to consolidate pure WC powders. The Vickers hardness and toughness of the dense WC were 24 GPa and 6 MPa·m1⁄2. The hardness was 50% larger than that of WC-Co hard alloys, and the toughness is half. A functionally graded material (FGM) of WC and WC-Co or Mo can afford good hard materials with high hardness and toughness. WC/WC-CoFGM was not obtained, because Co diffused rapidly at high temperatures during the densification of a WC layer. Two graded layers were enough to relax the residual stress of WC/Mo FGM and prevent cracks.抄録全体を表示PDF形式でダウンロード (1574K) -
土田 祐樹, 桐原 聡秀, 友田 陽, 辻本 得蔵1998 年 62 巻 11 号 p. 992-998
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーA new functionally graded coating method utilizing reaction diffusion and eutectic reaction has been developed. A Ti/Ti3Sn functionally graded material (FGM) has been successfully made using this method; a Ti plate or a round bar is at first covered by Ti-31 at%Sn powder, then heated up to 1888 K by 8.5 K/min and finally cooled by 5.0 K/min. This simple method has enabled us to obtain structurally sound FGMs, which show neither cracks nor detectable microstructure change after thermal cycle testing between room temperature and 1273 K. The microstructure is well graded and the surface completely consists of Ti3Sn, which has never been obtained by a eutectic coating method. The formation mechanism of such a graded microstructure is discussed.抄録全体を表示PDF形式でダウンロード (1292K) -
間渕 博, 津田 大, 立野 朋志, 森井 賢二1998 年 62 巻 11 号 p. 999-1005
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーIn order to clarify the phase equilibrium in the Ti-Al-Mn system, the vertical section and the microstructure of the L10/L12 two phase alloys have been determined experimentally. In addition, diffusion bonding of L10-type and L12-type alloys in the Ti-Al-Mn system was carried out to study a functionally graded diffusion layer. The Ti-43Al-5Mn(L10) and Ti-61Al-14Mn(L12) alloys were bonded at 1473 K for 1 h under 30 MPa pressure, and annealed at 1423 K for 48 h in a vacuum (∼10−4 Pa). The resulting diffusion layer had Al-rich L10 phase layer of about 70 μm and L12+L10(coherent precipitated) two phase layer of about 70 μm. The formation of the L12+L10(coherent precipitated) two phase microstructure is caused by the presence of the Ti-rich L12 phase field at higher temperatures. It was found that such diffusion layers have a gradual composition, a good linear expansion coefficient, and an excellent oxidation resistance for functionally graded materials.抄録全体を表示PDF形式でダウンロード (1254K) -
吉川 昇, 渡辺 嘉之, 菅原 誠司, 谷口 尚司, 菊池 淳1998 年 62 巻 11 号 p. 1006-1012
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーIt is known that silica (SiO2) is converted into Al/Al2O3 composite body, according to the following reaction:
(This article is not displayable. Please see full text pdf.)
In this study, composite bodies were fabricated at different reaction temperatures and their mechanical properties were investigated. The composite bodies fabricated below 1273 K had high hardness and revealed a brittle nature. On the other hand, in the composite bodies fabricated above 1273 K, hardness decreased and ductility increased a little. It is possible that plastic deformation occurs in the widened Al part in the coarse composite structures, and this is related with the decrease in hardness.
The gradation of hardness in the composite bodies was attempted by changing the reaction temperature. A silica rod was dipped into a molten Al bath at 1073 K, and the temperature was increased to 1373 K. There was no hardness variation along the radial direction in the cross section of the rod. When the reaction temperature was decreased form 1373 K to 1073 K, hardness was graded to be larger in the core area. However, the maximum hardness was not high as expected from the non-graded (reacted at constant temperature of 1073 K) specimens. By lowering the reaction temperature together with moving the specimen (gradual plunging), hardness gradation along the longitudinal direction was accomplished and large hardness difference existed. It was found that the cause for high hardness was related with the formation of nano-scaled composite microstructures containing low temperature (θ, γ)-Al2O3 phases.抄録全体を表示PDF形式でダウンロード (1399K) -
池田 裕子, 葛西 裕, 村上 昌三, 〓谷 信三1998 年 62 巻 11 号 p. 1013-1017
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーStyrene-butadiene rubber vulcanizates with the graded crosslinking densities (FGR-Vs) were prepared by mixing and heat-pressing. The compounding sheets containing different amounts of sulfur and accelerator were layered and cured at 150°C for 40 minutes under pressure. In the cure temperature, the rubber molecule became low viscous liquid and the reagents were diffused in the rubber matrix. Consequently, the graded dispersion of the reagents was obtained and FGR-Vs were produced. The thickness of the vulcanizates was ca. 2 mm. The properties of FGR-Vs were compared with those of the conventional (i.e., non-graded) vulcanizates (SBR-Vs) by the swelling test, the tensile test and the dynamic mechanical analysis. The hardness of the graded materials was evaluated by a micro hardness tester. The hardness and swelling behavior of the FGR-Vs proved the gradient of crosslinking density for the samples. The simple method based on the layering of two compounding sheets was found to give a gradient with a wider range than that on the layering of several compounding sheets. The variation of layered compounding sheets brought about vulcanizates with various gradients in the hardness, i.e., the crosslinking density. The good correlation between the crosslinking densities determined by swelling test and tensile test was observed. The modulus at 100% elongation and the solvent uptake of FGR-Vs depend on the overall crosslinking density of the vulcanizates as well as those of SBR-Vs. From the temperature dispersions of dynamic modulus and tanδ of the FGR-Vs and SBR-Vs, the δ peak of the former was found to be broader than that of the latter. The broadness of tanδ became wider with increasing of the degree of the gradient.抄録全体を表示PDF形式でダウンロード (437K) -
江 莞, 渡辺 龍三, 川崎 亮1998 年 62 巻 11 号 p. 1018-1024
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーIt has recently received much interest to incorporate a specific gradient function to a composite, according to the specific application of the composite. The composition profiles, as well as the microstructures of such materials have to be optimized with respect to the intended material function. For this reason the compositional dependence of the material properties are needed to obtain an optimum design, usually by means of numerical calculations. In present study, the dependence of the thermal conductivity of sintered Mo/ZrO2 composite on composition and microstructure were investigated, which is necessary information for the design of a thermal-stress release type functionally graded material. It was found that the thermal conductivity of the sintered Mo/ZrO2 composite exhibits a S curve against composition. The shape of S curve depends not only on the composition but also on the composite microstructure. The compositional dependence of the thermal conductivity of this composite was discussed in relation to theories that have so far been proposed. A fitting method for the experimental data was proposed on the basis of theoretical equations, in which microstructural transition in these sintered composites was taken into account.抄録全体を表示PDF形式でダウンロード (726K) -
本間 敬之, 喜多 洋介, 逢坂 哲禰1998 年 62 巻 11 号 p. 1025-1030
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーGradient control of magnetic properties, such as coercivity, Hc, in electrochemically-deposited thin films was attempted in order to establish the methodology for the preparation of functionally graded magnetic thin films. By applying ultra-thin “seed” layers of CoB or CoP, the Hc of electroless CoNiP films growing on them can be controlled toward the film thickness direction. Furthermore, sequential control of the rotating speed of substrates during the deposition can achieve programmed control of the gradient in Hc. These procedures are expected to be useful methods for optimizing graded magnetic properties of the films as recording media which are suitable for the overall system parameters such as local gradient of the recording head field.抄録全体を表示PDF形式でダウンロード (901K) -
吉川 信一1998 年 62 巻 11 号 p. 1031-1037
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーGraded nitrogen concentration is suitable to obtain iron nitride with giant magnetization. Rf sputter deposition was applied to prepare both multilayered and granular thin films in the Fe-Al-N ternary system. A giant magnetization component was observed at the multilayered interface because of the iron nitride formed in a solid state reaction between Fe and AlN layeres. A small amount of nitrogen in AlN was supplied to the α-Fe forming iron nitride reaction layer with a nitrogen concentration gradient through the interface. A granular film with α-Fe dispersed in the amorphous matrix was also obtained by annealing the reactive sputter codeposited Fe-Al-N ternary thin film in a H2 flow at 500°C. They showed a soft ferromagnetic behavior of α-Fe.抄録全体を表示PDF形式でダウンロード (994K) -
湯上 浩雄, 内藤 均1998 年 62 巻 11 号 p. 1038-1043
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーFunctionally graded materials (FGM) have been studied for many kinds of materials in order to improve mechanical or thermal properties. We have applied the FGM concept to solid electrolyte materials in order to improve electrical properties as well as mechanical stability of solid oxide fuel cells (SOFC).
In this study, we have adopted yttria-stabilized zirconia (YSZ) as a base electrolyte material, because YSZ is the key material for SOFC. The matching is quite important in both chemical and mechanical properties between electrolyte and electrodes for the SOFC system. From this point of view, we have studied a single-component SOFC using electron-ion mixed conducting CeO2 doped YSZ as the electrode material.
The aim of this work is improving the electrical and electrochemical properties as well as mechanical properties of the single-component SOFC by functionally graded CeO2 concentration in the mixed conducting Ce-YSZ electrode.
The oxygen transport properties of FG electrolytes were studied by electrical impedance and SIMS measurements. We have found that the oxygen diffusion property at the electrode/electrolyte interface is improved in FG electrolytes. In addition, the over-potential of the FG electrode measured by current interrupt method shows low values compared with the non-FG electrodes.抄録全体を表示PDF形式でダウンロード (567K) -
湯川 宏, 岸本 正俊, 森永 正彦1998 年 62 巻 11 号 p. 1044-1050
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe electronic structures of oxygen-ion compositional graded metal-oxide systems, Fe/FeO and Zr/ZrO2, are simulated by the DV-Xα cluster method. For each system, a model cluster involving the oxygen-ion compositional graded region is set and used for the calculation. The major differences in the model clusters between two systems are as follows; (1) The oxygen ions occupy octahedral interstitial sites in the Fe/FeO system, but tetrahedral interstitial sites in the Zr/ZrO2 system. (2) The metal-oxygen interatomic distance varies significantly in the oxygen-ion compositional graded region for the Fe/FeO system, but does not for the Zr/ZrO2 system. These structural differences affect directly the electronic structures of the compositional graded region. For example, both the O-2s and 2p bands spread over a wide energy region in the Fe/FeO system, but narrow in the Zr/ZrO2 system. Also, for the Fe/FeO system, the oxygen ion located in the bcc Fe side is in an unstable chemical bond state, because of the shorter Fe-O distance. As the position of the oxygen ions approaches the FeO side in the compositional graded region, the oxygen ion tends to make more stable chemical bond with the surrounding Fe ions. On the other hand, for the Zr/ZrO2 system, relatively stable chemical bond is formed between Zr and O ions in the compositional graded region.抄録全体を表示PDF形式でダウンロード (529K) -
山根 久典, 森田 浩一郎, 島田 昌彦1998 年 62 巻 11 号 p. 1051-1054
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーK(Ta, Nb)O3 crystals having a composition gradient were prepared by non-equilibrium cooling from melts of K(TaxNb1−x)O3 with x=0.3−0.7. Electron microprobe analysis revealed that the Ta content was rich in the core region of the crystals and decreased gradually to the edge with increasing Nb content. Zoning structures were observed in the crystals by polarized optical microscopy and high-temperature microscopy. There were three zones (cubic, tetragonal and orthorhombic phases from the core to the rim) or two zones (tetragonal (core) and orthorhombic phases (rim)). The boundary between the cubic and tetragonal zones moved to the edge with increasing temperature. The crystals exhibited broad peaks for the dielectric constant against temperature. No frequency dependence of the peak position was recognized from 100 kHz to 10 MHz.抄録全体を表示PDF形式でダウンロード (546K) -
小松 高行, 紅野 安彦, 坂井 亮介1998 年 62 巻 11 号 p. 1055-1062
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーTransparent TeO2-based glass-ceramics with graded optical nonlinearity such as second harmonic generation (SHG) have been fabricated for the first time through the two-step heat-treatment of 15K2O-15Nb2O5-70TeO2/7.5Li2O-7.5Na2O-15Nb2O5-70TeO2 joined glass sample. The gradual distribution of the species of alkali metal ions at the interface is confirmed from X-ray diffraction analyses. This result indicates the gradation of the second harmonic intensity at the interface, because the perfect solid solution between Na+ and K+ occurrs in the crystalline phase showing SHG and the intensity of second harmonicity decreases with increasing Na2O/K2O ratio. The fabrication of the transparent glass-ceramics having the gradient of the degree of the crystallization of the phase showing SHG has been also tried using the joined glass of 15K2O-15Nb2O5-70TeO2 (sample A) and 15K2O-15W2O6-70TeO2(sample B). Sample B is very stable thermally against crystallization. The crack is observed at the interface of such glass-ceramics because a large difference in the thermal expansion coefficient between the crystallized sample A showing SHG and the sample B maintaining the glassy state. The transparent Er3+ and Eu3+-doped glass-ceramics have been successfully prepared, and it is found that the intensity of the frequency upconversion fluorescence at around 550 nm due to the 4S3⁄2→4I15⁄2 transition of Er3+ in the glass-ceramics is strong compared with that in their precursor glass. This gives a new possibility for the fabrication of optically functionally graded TeO2-based glass-ceramics.抄録全体を表示PDF形式でダウンロード (770K) -
伊崎 昌伸, 石崎 博基, 芦田 淳, 小見 崇, 伊藤 太一郎1998 年 62 巻 11 号 p. 1063-1068
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーWurtzite zinc oxide (ZnO) film was cathodically deposited on a conductive glass substrate from a simple aqueous zinc nitrate solution kept at 335 K. ZnO films with changing resistivity in the thickness direction was prepared at increased deposition rate by controlling potential method composed of 1st-step electrolysis at the cathode potentials ranging from −0.9 to −1.2 V referred to Ag/AgCl electrode for electric charge of 60 C m−2 and of following 2nd-step electrolysis at −0.7 V up to 200 C m−2. The sheet resistivity of the ZnO films decreased by about three orders of magnitude with the increase in the film thickness from 0.3 to 0.9 μm. Defect-free and 0.9 μm-thick ZnO film with smooth surface was obtained by using controlling potential method with 1st-step electrolysis of −1.2 V for approximately 1 h and showed optical transmission of 74% at visible wave length.抄録全体を表示PDF形式でダウンロード (646K) -
王 新栄, 増本 博, 染野 義博, 平井 敏雄1998 年 62 巻 11 号 p. 1069-1074
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーDevelopment of high-quality optical filters has received considerable attention because it’s important device in the wavelength division multiplexing technique to realize optical communication with high speed and great capacity. In this work, the graded refractive index profiles are induced in the structure of designed multilayer filters by means of the concept of the functionally graded materials (FGM). Optical characterization of designed and fabricated novel filters with graded refractive index profiles in the SiO2-TiO2 system was investigated.
Designed reflection filters have the symmetrical structure with graded refractive index profiles combining with the layers modifying index difference and exhibit higher optical performance than unmodified rugate filter. Designed transmission filters exhibit almost 100% transmittance at the designated wavelength band which can be changed in the range from 1 to 50 nm and a wide reflection region with almost 100% reflectance. A designed 31-layer SiO2-TiO2 film with graded refractive index profiles was fabricated by helicon plasma sputtering and which has superior process controls and consequently better reproducibility. The measured transmittance spectrum exhibited a reflectance of 99.8% at a central wavelength of 730 nm and high transmittance over the wavelength region outside of the reflected band, which corresponded well with calculated one.抄録全体を表示PDF形式でダウンロード (710K) -
小柳 剛, 岸本 堅剛, 李 鎔勲, 長本 泰征1998 年 62 巻 11 号 p. 1075-1081
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe microstructures at grain boundaries of SiGe, CoSb3 and BiSb (mainly Bi) thermoelectric sintered materials have been controlled by using the plasma-treated raw powders in order to improve their thermoelectric properties. The powder surfaces of these materials were treated in the SiH4 plasma for SiGe, the O2 plasma for CoSb3, and the O2, H2, Ar, CoSb3+H2 plasmas for Bi, and their thermoelectric materials were sintered by the spark plasma sintering. For the SiGe samples, the Seebeck coefficient was enhanced by using the SiH4 plasma-treated raw powder, and the result was compared with the calculated one based on the energy filtering effect at Si-rich grain boundaries. For the CoSb3 samples sintered using the O2 plasma-treated raw powder, a decrease in the electrical conductivity and an increase in the Seebeck coefficient was observed, which were considered to be caused by the energy filtering effect of oxide layers at grain boundaries. The thermal conductivity was decreased. As a result, the figure of merit was improved by using the O2 plasma-treated raw powder. For the Bi samples sintered using the O2 plasma-treated raw powder, the electrical conductivity was increased, suggesting a decrease in the defects at grain boundaries. This result led to an improvement in the figure of merit. The room temperature values of the figure of merit were in excess of that calculated assuming that Bi single crystal grains are randomly oriented. The Bi samples sintered using other plasma-treated powders had also a higher figure of merit than that of the single crystal. For BiSb samples sintered using the O2 plasma-treated raw powder, an increase in the electrical conductivity was also observed.抄録全体を表示PDF形式でダウンロード (646K) -
杉山 明, 小林 慶三, 尾崎 公洋, 西尾 敏幸, 松本 章宏1998 年 62 巻 11 号 p. 1082-1087
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーThe formation process of functionally graded Mg2Si-FeSi2 thermoelectric material made by the mechanical alloying (MA) and the spark plasma sintering (SPS) was investigated.
The MA was performed in a planetary ball mill using three elemental powders. The powders were prepared by the mixing of Mg2Si-xmass%FeSi2 (x=0,20,40,60,80,100). The MA powders were consolidated by the SPS method. During SPS, the heating program was held at 643 K for 600 s, at 973 K for 300 s and at 923 K for 600 s, in order to attain densification and phase transformation to β-FeSi2. The structural evolution during milling and after sintering was detected by X-ray diffraction (XRD). The heat treatment was monitored by differential scanning calorimetry (DSC).
For Mg-Si the formation of the Mg2Si phase is observed after milling for 1080 ks. But the Mg2Si phase was easily formed during milling when a third element such as Fe was included. For Mg2Si-xmass%FeSi2 phases of Mg2Si, FeSi, Fe and Si were observed after milling for only 180 ks. The MA powder was functionally graded with high density by SPS. However, the α-FeSi2 and FeSi phase were observed in the sintered sample.抄録全体を表示PDF形式でダウンロード (603K) -
岩田 政司, 下野 晃, 木城 きくか, 国枝 義彦1998 年 62 巻 11 号 p. 1088-1094
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーA preparation method, which can smoothly vary the porosity profile of a sintered material, was proposed. A packing method based on semi-batchwise filtration operation of two suspensions was applied. A suspension of ceramic particles was put into a mixing tank, followed by the filtration of the suspension. Then, a suspension of carbonaceous particles was fed in continuously to the tank. The composition profile of the filter cake was found to vary smoothly in the direction of cake thickness. After drying and consolidation, the cake was sintered in an oxidizing atmosphere, resulting in a porous sintered material. A porosity profile of the material can be designed based on the filtration theory, assuming that sedimentation of particles is negligible. Effect of sedimentation can be evaluated by making a Ruth plot. It was concluded that in packing fine particles by semi-batchwise filtration, an easy-to-filter-material should be selected as one component of the binary mixture.
The fabrication of porous hydroxyapatite was tried for use as an artificial bone or an artificial tooth-root. To improve the mechanical strength of porous hydroxyapatite, the capsule-free HIP sintering was conducted. Although the hardness of porous hydroxyapatite increased after the treatment, it was still lower than those of natural bones or tooth-roots. Addition of another component seemed to be essential to further improvements of the mechanical properties of the porous hydroxyapatite.抄録全体を表示PDF形式でダウンロード (671K) -
亘理 文夫, 横山 敦郎, 佐相 史徳, 宇尾 基弘, 松野 浩宜, 川崎 貴生1998 年 62 巻 11 号 p. 1095-1101
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーVarious imaging methods were applied to observe and evaluate the functionally graded structure of dental implant and tissue reaction around the implant inserted in an animal experiment. To optimize the mechanical properties and biocompatibility the dental implant with the graded structure that increases the content of hydroxyapatite (HAP) in the longitudinal direction, from pure titanium (Ti) at one end up to 20% or 100%HAP at the other end, was fabricated through the process of powder metallurgy. After the external appearance was observed either with the naked eye or by optical microscopy, X-ray tranmission image was taken. The cross-section was then investigated by the secondary electron image and the compositional image using reflection electrons in a scanning electron microscope, line analysis and elemental mapping in EPMA (electron probe microanalysis) and the features of these methods were compared. All the methods for the optical images based on the reflection and scattering of light due to surface morphology, the X-ray transmission and reflection electron images based on the atomic number dependence, line analysis and mapping based on the characteristic X-ray emission confirmed the gradient structure. For the observation of the new bone formation around the implant which was inserted in the femora of rats, the compositional image by reflection electrons and EPMA elemental mapping were applied. These imaging methods whose contrast is based on the electronic structure of the specimens have the features that specimen preparation is simple without ultra thin sectioning and staining, and the recognition and evaluation of new bone area is easy. It would be more effective to use together with the conventional method to observe histologically the stained thin specimen by optical microscopy.抄録全体を表示PDF形式でダウンロード (1380K) -
金 鉉敏, 宮路 史明, 小久保 正1998 年 62 巻 11 号 p. 1102-1107
発行日: 1998年
公開日: 2008/04/24
ジャーナル フリーBioactive titanium and its alloys with functionally graded structure were prepared by subjecting the metals to a simple chemical treatment. An amorphous sodium titanate layer integrated with the metal substrates through a graded structure was formed on the metals by 5.0 kmol·m−3-NaOH treatment at 60°C for 24 h and subsequent heat treatment at 600°C for 1 h. In a simulated body fluid with pH and ion concentrations nearly equal to those of human blood plasma, the treated metals released Na+ ions from the surface sodium titanate layer via ion exchange with H3O+ ions in the fluid to form a hydrated titania abundant in Ti-OH groups on the surfaces of the metal and to increase the ionic activity product of apatite in the fluid. The Ti-OH groups on the metals induced apatite formation and the increased ionic activity product accelerated it. The apatite formed on the metal was tightly integrated with the metal substrates through a graded structure in which the apatite gradually changed into the metal via hydrated titania and titanium oxide. The chemically treated metals could also form the apatite layer in the body to bond to and integrate with bone. Bioactive titanium and its alloys in this type are therefore believed to be very useful as artificial bone substitutes under load-bearing conditions.抄録全体を表示PDF形式でダウンロード (1449K)
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