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National Institute for Materials Science

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[FGMs Database: Journal of Functionally Graded Materials Vols. 28-34 (2014-2020)](https://mdr.nims.go.jp/datasets/691fbae4-c929-4f56-97c7-f9c15ce47382)

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Sheet1 Modifieddate BookTitle_e BookTitle Volume/Issue Ver Issueddate Page Title_j Title_e AuthorList_j AuthorList_e Abstract Language 7/6/20 Journal of Functionally Graded Materials Vol.28(2014) Journal of Functionally Graded Materials Vol.28, 1-8 (2014) 28  12/31/14 1-8 結晶粒微細化により母材を強化した複合砥粒傾斜機能砥石の製造とそれによるCFRPの穴あけ加工 Fabrication of Grain Refined Functionally Graded Grinding Wheel Reinforced by Composite Particles and its Application for Drilling of CFRP 谷口和也,佐藤尚,渡辺義見/名古屋工業大学, 倉知一正/岐阜県セラミックス研究所, 柘植英明/岐阜県工業技術研究所 Kazuya Taniguchi, Hisashi Sato, Yoshimi Watanabe / Nagoya Institute of TechnologyKazumasa Kurachi / Gifu Prefectural Ceramics Research InstituteHideaki Tsuge / Industrial Research Institute of Gifu Prefecture  This study aims to investigate machinability of carbon fiber reinforced plastic (CFRP) by grain refined Al based metal bond functionally graded grinding wheel (FGGW) containing diamond-composite particles. Diamond-composite particles which consist of nano-sized diamond particles and micro-sized green silicon carbide (GC) abrasive grains have been made by mechanofusion machine (Nobilta). The Al based metal bond FGGW was fabricated by reaction centrifugal mixed-powder (RCMP) method using mixed-powder of Al, Ti and diamond-composite particles. Since the formed Al3Ti phase acts as grain refiner, it is expected that the grain structure of Al matrix in FGGW fabricated by RCMP method with Ti particles becomes more refined than that fabricated without Ti particles. Using the fabricated FGGW, CFRP drilling tests were conducted by gyro-driving grinding wheel system. It is found that the FGGW fabricated by RCMP method with Ti particles have fine-grained Al matrix. It is also found that optimum additive amount of Ti on the FGGW is 4~6 mass%. It is concluded that the FGGW fabricated by RCMP method with Ti particles has better machinability of CFRP by gyro-driving grinding wheel system.Key words: Centrifugal casting, Grinding wheel, Grain refinement, Carbon fiber reinforced plastic (CFRP),Composite particles Japanese 7/6/20 Journal of Functionally Graded Materials Vol.28(2014) Journal of Functionally Graded Materials Vol.28, 1-8 (2014) 28  12/31/14 9-15 ZnSb 熱電材料を用いた小規模自立型太陽熱発電システムに向けた熱カスケード利用の検討 Preliminary Study on Thermal Cascading for Small Scale Stand-alone Oriented Solar Thermal Power Generating System Using ZnSb Thermoelectric Materials 草野剛嗣,長谷崎和洋/徳島大学大学院ソシオテクノサイエンス研究部, 新野正之,矢野歳和/航空宇宙技術振興財団 Koji Kusano, Kazuhiro Hasezaki / Institute of Technology and Science, the University of Tokushima, Masayuki Niino,Toshikazu Yano / Japan AeroSpace Technology Foundation  Hypothetical small scale stand-alone solar thermal power generating system has been constructed, of which thermo and electric responsiveness was predicted and clarified using improved ZnSb thermoelectric materials. The system consisted of solar collector, available primary and secondary home-use tanks, where the thermoelectric conversion module was sandwiched between these two tanks. The electric responsiveness and thermoelectric conversion efficiency was investigated. The product of overall heat transfer coefficient of the module and heat transfer area, kA affect the rate of heat transfer, period of heat exchange, the conversion efficiency and generating power. Higher kA leads to shorter completion time for heat exchange and higher thermoelectric conversion efficiency. However, the total electric energy was slightly affected by kA.The maximum energy efficiency of the system was 2.21 % and 0.413kWh at kA = 200 W/K with hot water (88.4 °C @ 0.46 m3).Key words: Thermoelectric semiconductor, Zinc antimonide, Concentrating solar power, Thermal cascading, Thermal storage, Thermal resistance Japanese 7/6/20 Journal of Functionally Graded Materials Vol.29(2015) Functionally Graded Materials Vol. 19, 2005 29  12/31/15 1-7 遠心力を用いた傾斜機能材料製造装置の開発 Development of FGMs Manufacturing System under Centrifugal Force 大矢泰正/株式会社大矢鋳造所,名古屋工業大学, 瀬戸口正嵩,服部祐幸,岩田直也,佐藤尚,渡辺 義見/名古屋工業大学 Yasumasa Oya / OHYA-CHUZOSHO Co., LtdMasataka Setoguchi, Yuko Hattori, Naoya Iwata, Hisashi Sato, Yoshimi Watanabee / Nagoya Institute of Technology  Centrifugal casting method is used for piping shape products, which can be applicable to fabricate functionally graded materials (FGMs). There are two types of the centrifugal casting machine, i.e., horizontal and vertical-types. In our previous study, it was shown that the horizontal machine is a better than the horizontal one to fabricate the pipe shaped FGMs by the reactive centrifugal castingmethod and centrifugal mixed-powder method. The present study developed a centrifugal casting machine for the FGMs production. A heating furnace and a spinning-casting mold are placed on a steel-frame, and the mold is rotated horizontally by belt drive. Inert gas injection system and washer of damping alloyare used to avoid the oxidation of fine-particles in the mold and to reduce the vibration of machine, respectively. The cooling rate of the materials before and after the solidification is roughly estimated from the resultant lamella structure of the FGMs.Key words: Centrifugal force, Manufacturing system, Casting, High damping alloy, Cooling rate Japanese 7/6/20 Journal of Functionally Graded Materials Vol.29(2015) Functionally Graded Materials Vol. 19, 2005 29  12/31/15 7-9 Original paper Coaxially Introduced Flame Spraying of Alumina with Different Particle Sizes Original paper Coaxially Introduced Flame Spraying of Alumina with Different Particle Sizes Kazuto TAKAI /Nippon Coating Industry Co. Ltd, Soshu KIRIHARA/Joining and Welding Research Institute, Osaka University Kazuto TAKAI /Nippon Coating Industry Co. Ltd, Soshu KIRIHARA/Joining and Welding Research Institute, Osaka University In a newly developed rod-feeding flame spraying process, solid resin rods containing fine particles were successfully fed into a Rokide® flame gun to deposit thin ceramic layers. In this investigation, alumina particles with average diameters of 1.8 μm or 170 nm were dispersed in liquid acrylic resins. Alumina particles with different sizes were successfully incorporated in the liquid acrylic resins in high volume fractions. The obtained slurries were injected into brass molds, and shaped into solid resin rods. We compare the film from a previous study with the film prepared here, with different particle size diameters. The sprayed alumina particles were collected in a water bath for microtextural observation using scanning electron microscopy and crystal phase analysis by X-ray diffraction.Key words: fine particles, Rokide® gas flame spraying, solid resin rod, thixotropic English 7/6/20 Journal of Functionally Graded Materials Vol.30,(2016) Functionally Graded Materials Vol. 19, 2005 30  3/31/17 1-4  Al被覆Mg合金薄板材の作製およびその機械的性質の調査 Fabrication of Al-coated Mg alloy sheet and investigation of its mechanical properties 徳永透子,大野宗一,松浦清隆/北海道大学大学院工学研究院 Toko Tokunaga1, Munekazu Ohno, Kiyotaka Matsuura / Faculty of Engineering, Hokkaido University  In order to achieve a light and corrosion-resistant structural material, Al-coated Mgalloy sheet has been fabricated by hot extrusion followed by hot rolling. The sheetwas successfully rolled at 623 K without any breaking of the Al coating layer, andthe sheet exhibited an excellent corrosion resistance. The mechanical propertieshave been investigated by tensile tests at various temperatures and strain rates. Atroom temperature, the stress value drops immediately after reaching the maximum,while the value decreases as the temperature increases and the strain rate decreases.It has been demonstrated that the sheet exhibits elongation of 707 % at 573 K at1.0×10-3 s-1 when tensile-tested in the rolling direction. After the elongation, theAl coating layer remained on the Mg alloy substrate. No cracks or debonding wereobserved at interfaces of Mg alloy/Al3Mg2 and Al3Mg2/Al.Key words: Mg 合金, 超塑性, コーティング, 耐食性 Japanese 7/6/20 Journal of Functionally Graded Materials Vol.30,(2016) Functionally Graded Materials Vol. 19, 2005 30  12/31/16 5-10 Original paper 分子動力学シミュレーションを用いたナノ粒子の低温焼結特性に関する数値解析 A numerical analysis of the low-temperature sintering propertiesof nano-particles by Molecular dynamics simulation. 松原典恵,宗籐伸治,古君修/九州大学大学院 Norie Matsubara, Shinji Munetoh, Osamu Furukimi / Kyushu University A sub-micron-sized metal particle has been used as a jointing material between a semiconductor device and a circuit electrode because of its low-temperature sintering characteristic. In this study, we have investigated a behavior of particles during heating using the molecular dynamics (MD) simulation, and we analyzed the driving force of low temperature sintering characteristic of particles. The Langevin equation and the Finnis-Sinclair potential were used on solving the equation. An Iron particles with a diameter of around 240 Å were heated at temperatures above/below the melting point (Tm) for the estimation of diffusion coefficient. The average diffusion coefficient near the center of the particle was 10-5 cm2/sec at above Tm and was 10-8-10-9 cm2/sec at below Tm. On the other hand, the average diffusion coefficient at the outer layer of a particle becomes two or three orders in magnitude bigger than the center of the particle. It is conceivable that an enhanced sintering of nano-particles at low temperature is due to the high diffusion coefficient near the surface.Key words: MD simulation, Diffusion coefficient, Metal particle, Jointing material Japanese 7/6/20 Journal of Functionally Graded Materials Vol.31(2017)  31  12/31/17 1-5 MoSi2 Oxidation-Resistance Lifetime of FunctionallyGraded Materials Coatings for γ-TiAl MoSi2 Oxidation-Resistance Lifetime of FunctionallyGraded Materials Coatings for γ-TiAl Masayuki Ohshima, Shohei Matsuda / Intelligent Structures and Mechanics Systems Engineering, Graduate School of Advanced Science and Technology, Tokushima University, Toshimitsu Tetsui / High-Temperature Materials Center, National Institute for Materials Science, Kazuhiro Hasezaki / Department of Mechanical Science, Graduate School of Science and Technology, Tokushima University Masayuki Ohshima, Shohei Matsuda / Intelligent Structures and Mechanics Systems Engineering, Graduate School of Advanced Science and Technology, Tokushima University, Toshimitsu Tetsui / High-Temperature Materials Center, National Institute for Materials Science, Kazuhiro Hasezaki / Department of Mechanical Science, Graduate School of Science and Technology, Tokushima University A functionally graded material (FGMs) MoSi2/Mo was adopted for oxidation resistance coating of γ-TiAl. The MoSi2 coating was produced by dipping Mo plates in the molten salt. The obtained MoSi2 coating layer resulted was approximately 60 μm in thickness. The oxidation resistance of MoSi2/Mo was examined at 1323–1423 K for 3–400 h in still air, as a criterion for the lifetime of MoSi2/Mo/γ-TiAl FGMs. The oxidation at 1423 K for 30 h in still air caused Si to diffuse into Mo without cracks or voids at MoSi2/Mo interlayer. The MoSi2 activation energy of volume diffusion was estimated as 523 ± 75 kJ/mol, which was consistent with the available data. The lifetime of the MoSi2 coating was approximately five times larger than that of a NbSi2 coating under the same condition. An oxidation-resistant MoSi2/Mo FGMs coating has a longer lifetime than an NbSi2/Nb coating for γ-TiAl.Key words: siliconization, oxidation, coating, functionally graded materials, γ-TiAl intermetallic compound English 7/6/20 Journal of Functionally Graded Materials Vol.31(2017)  31  3/31/18 6-13 希薄溶液環境下における腐食測定方法の検討と異種金属の反応性 Consideration for Measuring Method and Reactivity of Dissimilar Metals in Low Concentration Solution 八木雄太/株式会社ナカボーテック, 芝浦工業大学, 沢登甲陽, 鈴木良治, 野田和彦/ 芝浦工業大学 Yuta Yagi / Nakabohtec Corrosion Protecting Co., LTD., Shibaura Institute of Technology, Koyo Sawanobori, Ryoji Suzuki, Kazuhiko Noda / Shibaura Institute of Technology It is difficult to determine precise electrochemical data and analyze corrosion behavior in dilute solution, because dilute solution is a high solution resistance environment. In order to solve these problems, it is necessary to establish an electrochemical measurement method to analyze corrosion behavior. In this study, we examined about electrochemical impedance spectroscopy and coupling current measurement which is a suitable electrochemical measurement method in a low-concentration electrolyte environment using pure zinc, pure iron and stainless steel type 304 (SUS304). In low concentration solution, it was found out that electrochemical impedance spectroscopy has to use two-electrode cell and coupling current measurement is effective method to analyze corrosion behavior. The charge transfer resistance of pure zinc is fixed in 0.0001—0.01 M NaCl solution and decreases in 0.01 M or more. That of Fe drastically decreases in 0.0001—0.001 M, mildly decreases in 0.001—0.5 M and increases in 0.5 M or more. That of SUS304 is fixed in all concentration. The coupling current decreases with decreasing of solution concentration. The reason of decreasing ofcoupling current is estimated that solution resistance increases by decreasing of solution concentration.Key words: Electrochemical impedance spectroscopy, Two-electrode cell, High resistance solution, Coupling current Japanese 7/6/20 Journal of Functionally Graded Materials Vol.31(2017)  31   2017/12/31 14-23 界面に垂直なき裂を有する傾斜機能圧電積層厚板の非定常電気熱弾性応答 Transient Thermal Response of a Functionally Graded Piezoelectric Laminate with a Crack Normal to the Bimaterial Interface 上田整,岡田真幸,仲上佳寿/ 大阪工業大学 Sei Ueda, Masayuki Okada, Yoshihisa Nakaue / Osaka Institute of Technology In this paper, the fracture problem of a functionally graded piezoelectric material strip (FGPM strip) containing a crack perpendicular to the interface between an FGPM strip and a homogeneous layer is considered. The problem is solved for the laminate that is suddenly heated from the surface of the FGPM strip. The surface of the homogeneous layer is maintained at the initial temperature. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. By using the Laplace and Fourier transforms, the thermoelectro- mechanical fracture problem is reduced to a singular integral equation, which is solved numerically. The stress intensity factors are computed and presented as a function of the normalized time, the nonhomogeneous and geometric parameters.Key words: Functionally graded piezoelectric material, Fracture mechanics, Stress intensity factor, Normal crack, Transient response Japanese 7/6/20 Journal of Functionally Graded Materials Vol.31(2017)  31  12/31/17 24-28 SPS法により作製されたBa8AuxSi46-x クラスレートにおける新たな熱—電力変換効果の検証 Ba8AuxSi46-x Clathrate Synthesized by SPS for a Novel Heat-Electric Conversion Effect 刑部有紀, 小坪優一, 辰見翔太, 岩永純平, 山外啓太, 三好和之輔, 宗藤伸治, 古君修, 中島邦彦 / 九州大学 Yuki Osakabe, Yuichi Kotsubo, Shota Tatsumi, Junpei Iwanaga, Keita Yamasoto, Kazunosuke Miyoshi, Shinji Munetoh, Osamu Furukimi, Kunihiko Nakashima / Kyushu University Preciously, we suggested a novel heat-electric power conversion effect without temperature gradient. In this study, we purposed synthesizing sample for a novel effect with Spark Plasma Sintering (SPS). This effect needs joining n-type, intrinsic and p-type semiconductors. In addition, intrinsic semiconductor must have narrower band gap than n- and p-type semiconductors. Therefore, we payed attention to Ba8AuxSi46-x for satisfying these requirements. Ba8AuxSi46-x is changed its electrical properties by Au contents. Furthermore, this materials show that n- and p-type semiconductors show wider band gap than intrinsic semiconductor. In this study, we synthesized two layers sample of n-type and p-type Ba8AuxSi46-x with SPS. Sintering process was expected promoting Au diffusing from p-type to n-type, and form a Au gradient part in n/p interface. According to results of WDX, chemical composition gradient was observed in n/p interface. This result showed that sample synthesized by SPS satisfied two requirements. Therefore, the sample was heated under uniform temperature and generated voltage showed 2.5 mV at 500°C. These results suggested SPS was suitable method for synthesizing samples of a novel effect.Key words: thermoelectric material, clathrate, spark plasma sintering, composition gradient Japanese 7/6/20 Journal of Functionally Graded Materials Vol.31(2017)  31  12/31/17 29-32 Original paper 多結晶クラスレートによる等温環境下での発電の検証および向上 Verification and improvement of power generation under the uniform temperature environment by the poly-crystalline clathrate 岩永 純平, 天野 博史, 三好 和之輔,  刑部 有紀, 宗藤 伸治, 古君 修 / 九州大学大学院 Junpei Iwanaga, Hiroshi Amano, Kazunosuke Miyoshi, Yuki Osakabe, Shinji Munetoh, Osamu Furukimi / Kyushu University A novel electric power generation different from the Seebeck effect by using poly-crystaline Ba8AuxSi46-x clathrate consisted of two layers, n-type and p-type materials, was devised. In order to investigate composition dependence of generated voltage, poly-crystalline clathrate samples consisted of two layers with various Au composition were prepared by SPS method. According to composition analysis, the mixed layer was formed at the interface of two layers. The sample consisted of n-type Ba8Au4.5Si41.5 / p-type Ba8Au5.5Si40.5 can generate around 2.0 mV at 723 K under no temperature difference. It is considered that this voltage was caused by charge separation with the diffuse of electrons and holes exited at mixed layer with narrower band gap part on interface. Ba8Au4.0Si42.0 / Ba8Au6.0Si40.0 and Ba8Au4.8Si41.2 / Ba8Au5.2Si40.8 samples showed around 4.0 and 1.0 mV at 723 K, respectively. These results suggested that the voltage increased with difference of Fermi level between n- and p-type semiconductors.Key words: Thermoelectric material, clathrate, SPS, Ba8AuXSi46-X Japanese 7/8/20 Journal of Functionally Graded Materials Vol.32(2018)  32   2018/12/31 1-6 調和組織制御による革新的構造材料の創製 Creation of Innovative Structural Materials via Harmonic Structure Design 飴山 惠, 川畑美絵 / 立命館大学理工学部機械工学科, 中谷 仁 / 立命館大学大学院理工学研究科院生 Kei Ameyama ,  Mie Kawabata / Department of Mechanical Engineering, Faculty of Science and Engineering, Ritsumeikan University , Masashi Nakatani / Graduate student, Graduate school of Science and Engineering, Ritsumeikan University Harmonic Structure (HS) has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the HS is heterogeneous on micro- but homogeneous on macro-scales. The most unique feature of HS is its continuously connected UFG Shell structure. In the present work, the HS design has been applied to pure metals and alloys via SPD powder metallurgy process. At a macro-scale, the harmonic structure materials exhibited significantly better combination of strength and ductility, as compared to their homogeneous microstructure counterparts. This behavior is essentially related to the ability of the HS to promote a large strain hardening and uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability. Such outstanding mechanical properties of HS materials are attributed to the continuously connected UFG-Shell structure. This unique microstructure provides stress-concentration in the micro scale and stress dispersion in the macro scale.Key words: strength, ductility, strain hardening, unique deformation, stress concentration Japanese 7/8/20 Journal of Functionally Graded Materials Vol.32(2018)  32   2018/12/31 7-12 金属粉末の高密度充填化と積層造形技術への応用 High Packing Metallic Powder for Application of Additive Manufacturing 渡辺義見, 佐藤 尚 / 名古屋工業大学・物理工学専攻, 小寺 諒 / 名古屋工業大学・機械工学科第二部学生, 現（株）アルプス技研 Yoshimi Watanabe, Hisashi Sato / Department of Physical Science and Engineering, Nagoya Institute of Technology, Ryo Kotera / Undergraduate Student, Department of Mechanical Engineering, Nagoya Institute of Technology Flowability and packing structure of metallic powder are ones of key issue to achieve good formability of additive manufacturing. In this article, packing structure of metallic powders is studied using two kinds of gas-atomized ferric powders and two kinds of model powders. The packing fraction of the powders is increased by tapping. The packing behavior by tapping is different depending on characteristics of powder. Larger angle of repose is observed for the powder with higher packing fraction after the tapping. Since fine powder penetrates into the opening gaps located in the coarse powder, high packing fraction can be achieved by mixing of the coarse powder and fine powder. Moreover, stacking behavior of powder bed with these powders is also investigated using handmade additive manufacturing machine. Obtained data allowed us to discuss the formability of additive manufacturing.Key words: Additive Manufacturing, Metallic Powder, Flowability, Packing, Angle of Repose, Tapping Japanese 7/8/20 Journal of Functionally Graded Materials Vol.32(2018)  32   2018/12/31 13-23 平行き裂を有する傾斜機能遮熱コーティング積層板の非定常熱弾性応答 A Crack Parallel to the Interface Between a Functionally Graded Thermal Barrier Coating and a Homogeneous Elastic Substrate under Transient Thermal Loading 上田整, 伊與田宗慶 / 大阪工業大学,  正岡恭彦 / 大阪工業大学大学院 Sei Ueda, Muneyoshi Iyota / Osaka Institute of Technology, Yasuhiko Masaoka / Osaka Institute of Technology In this paper, the fracture problem of a functionally graded thermal barrier coating (FGTBC) containing a crack parallel to the interface between the FGTBC and a homogeneous substrate is considered. The problem is solved for the laminate that is suddenly heated from the upper surface of the FGTBC. The bottom surface of the homogeneous substrate is maintained at the initial temperature. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. By using both the Laplace and Fourier transforms, the thermo-mechanical fracture problem is reduced to a singular integral equation and a system of singular integral equations which are solved numerically. The stress intensityfactors of the crack are computed and presented as a function of the normalized time for the various values of the nonhomogeneous and geometric parameters.Key words: Functionally Graded Thermal Barrier Coating, Fracture Mechanics, Parallel Crack, Stress Intensity Factor, Transient Response Japanese 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 1-7 Quasi-static and Dynamic Analysis of Multi-Layered Steel Beams: Core Optimization Quasi-static and Dynamic Analysis of Multi-Layered Steel Beams: Core Optimization Asmita Rokaya, Linhui Zhang, Jeongho Kim, / Department of Civil and Environmental Engineering, University of Connecticut Asmita Rokaya, Linhui Zhang, Jeongho Kim, / Department of Civil and Environmental Engineering, University of Connecticut This paper addresses the quasi-static and dynamic response of multi-layered steel beams using finite element analysis. The steel beam has four corrugated cores in between the top and bottom substrates. The cores are arranged with corrugated sheets of different thickness. Quasi-static test is first performed to select a suitable material, either thin steel substrate made of steel 1008 or thick steel substrate made of steel 1018, for the top substrate plate, and is then validated with finite element analysis. Upon quasi-static tests and finite element validations, the top plate is selected and dynamic responses of various core layups are further evaluated. The stress-strain relations of carbon steel 1018 at high strain rates are measured using the Split-Hopkinson pressure bar. A finite element modeling procedure for dynamic analysis is validated with a set of shock tube experiments. Corrugated multi-layered steel core arrangements are taken into account for design parameters in order to maximize mitigation of blast load effects onto the main structure.Keywords: Carbon steel beam, Multi-layered steel beam, Corrugated core, Shock tube test English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 8-11 Verification of a Heat-electric Power Conversion Mechanism with Narrow Band Gap using the Thermal-probe Method Verification of a Heat-electric Power Conversion Mechanism with Narrow Band Gap using the Thermal-probe Method Yuki Osakabe, Shota Tatsumi, Yuichi Kotsubo, Keita Yamasoto, Shinji Munetoh, Osamu Furukimi, Kunihiko Nakashima / Department of Materials Science and Engineering, Kyushu University Yuki Osakabe, Shota Tatsumi, Yuichi Kotsubo, Keita Yamasoto, Shinji Munetoh, Osamu Furukimi, Kunihiko Nakashima / Department of Materials Science and Engineering, Kyushu University Thermoelectric power generation is based on the Seebeck effect and occurs with a temperature gradient. Recently, we prepared a single crystalline Ba8AuxSi46-x clathrate with Au composition gradient and reported a heat-electric power conversion with narrow band gap. However, the mechanism was not clearly elucidated. In this study, we investigated carrier-generation behavior using the thermal-probe method during the heating. A single crystal of Ba8AuxSi46-x clathrate was grown by the Czochralski method. Wavelength- dispersive X-ray spectroscopy showed that this single crystal has an Au-content gradient. The Seebeck coefficient of the sample was evaluated by the thermal probe method at room temperature and 300 °C. Results for 300 °C show that heating promotes adecrease of the Seebeck coefficient near the n/p interface. This decrease of the Seebeck coefficient indicated the electrons were excited by heating near the n/p interface.Key words: thermoelectric properties, BaAuSi clathrate, single crystal, Czochralski method, thermal probe method English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 12-15 Coating of Al-Cu Alloy with Ti-N Graded Film by Reactive DC Sputtering Coating of Al-Cu Alloy with Ti-N Graded Film by Reactive DC Sputtering Tsutomu Sonoda, Akira Watazu / National Institute of Advanced Industrial Science and Technology (AIST) Tsutomu Sonoda, Akira Watazu / National Institute of Advanced Industrial Science and Technology (AIST) Coating of Al-Cu alloy with Ti-N graded film was examined by reactive DC sputtering, in order not only to improve the surface hardness and the corrosion resistance or the biocompatibility of the aluminum alloy but also to relax the stress concentrated at the interface between the coated film and the alloy substrate. The deposition of the Ti-N graded coatings were realized by varying continuously nitrogen content in Ar-N2 sputter gas during the reactive sputtering. Deposited films appeared to be uniform and adhesive, and their color tone was bronze with a red tinge. Their surface hardness reached over Hv1400. According to GDOES (Glow Discharge Optical Emission Spectroscopy) in-depth profiles, the nitrogen concentration in the film gradually decreased in depth direction from the surface toward the alloy substrate, confirming that Ti-N graded film had formed on the alloy substrate. On the basis of XRD, it was assumed that not only a-titanium phase but also titanium nitride phases such as TiN and Ti2N were formed in the graded film. Furthermore it was confirmed that the corrosion protective property of the Al- Cu alloy could be improved by coating it with the graded coating.Key words: graded coating, titanium nitride, sputter-deposition, corrosion resistance, biocompatibility English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 16-22 Original paper Strength improvement of poly(vinyl alcohol) (PVA) reinforced by Halloysite nanotube (HNT) treated with sulfuric acid Original paper Strength improvement of poly(vinyl alcohol) (PVA) reinforced by Halloysite nanotube (HNT) treated with sulfuric acid Antonio Norio Nakagaito, Hitoshi Takagi / Institute of Technology and Science, Tokushima University,  Kohei Fujii / Graduate School of Advanced Technology and Science, Tokushima University,  Yu Dong / Department of Civil and Mechanical Engineering, Curtin University Antonio Norio Nakagaito, Hitoshi Takagi / Institute of Technology and Science, Tokushima University,  Kohei Fujii / Graduate School of Advanced Technology and Science, Tokushima University,  Yu Dong / Department of Civil and Mechanical Engineering, Curtin University Halloysite nanotube (HNT) is a natural clay mineral with a hollow and tubular structure, which can be a potential reinforcement for biodegradable polymers such as poly(vinyl alcohol) (PVA). This study investigates the improvement of interfacial adhesion between HNT and PVA by means of controlled acid etching on HNT surfaces. Such an improvement is attributed to a porous structure with rough HNT surfaces in that acid favors the dissolution of AlO6. The strength of PVA/HNT nanocomposites increased up to 10% when HNT were subjected to 1 h acid treatment. However, the reinforcement effect could have been more pronounced if HNT aspect ratio were maintained during the composite fabrication process.Key words: halloysite, clay, poly(vinyl alcohol), acid, etching English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 23-27 Formation of Oriented and Graded Grain Structure in Fe-Cu-C Alloy by Liquid Phase Sintering and Carburization Formation of Oriented and Graded Grain Structure in Fe-Cu-C Alloy by Liquid Phase Sintering and Carburization Ryuzo Watanabe / Japan Aerospace Technology Foundation, Yasuaki Okita / Joining and Strength Res. Dept., JFE Steel Corp.,  Akira Kawasaki / Department of Materials Processing, Tohoku Univ. Ryuzo Watanabe / Japan Aerospace Technology Foundation, Yasuaki Okita / Joining and Strength Res. Dept., JFE Steel Corp.,  Akira Kawasaki / Department of Materials Processing, Tohoku Univ. Quantitative microstructural measurements were made on the oriented and graded structures of the liquid-phase sintered and subsequently carburized Fe-Cu-C compacts. The possible mechanism of the formation of the microstructure has been proposed, in which a concurrent effect of chemically driven liquid film migration, and the decrease in the grain boundary energy, both originated from carbon dissolution, as well as of the surface flattening by capillarity, is the main cause for the formation of oriented and elongated grains. The energy minimization in the graded mirostructure was discussed in terms of the total interface energy in liquid phase sintered alloys. The constancy of the total interface energy throughout the graded compact, the linear relationship between the liquid volume fraction and dihedral angles, as well as the liquid flow towards carbon-diffusion front, strongly suggest that the graded compact is energetically in equilibrium.Keywords: liquid phase sintering, functionally graded materials, liquid flow, energy minimization English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 28-36 Influence of Holding at High Temperatures and Heat Cycles on Young's Modulus and Hardness of Thermal Barrier Coatings Measured by Nano-Indenter Influence of Holding at High Temperatures and Heat Cycles on Young's Modulus and Hardness of Thermal Barrier Coatings Measured by Nano-Indenter Masahiko KATO / Dept of Mech. Sys. Eng, Fukuyama University, Taichi IWATA / Graduate student, Hiroshima University Masahiko KATO / Dept of Mech. Sys. Eng, Fukuyama University, Taichi IWATA / Graduate student, Hiroshima University Changes of the Young's modulus and hardness of thermal barrier coatings (TBCs) isothermally held at high temperatures or subjected to heat cycles were experimentally studied using a nano-indenter. 8mass% yittria-stabilized zirconia (YSZ) was plasma-sprayed on a Ni-based superalloy with a CoNiCrAlY bond coat layer. The specimen was isothermally held or heatcycled at temperatures of 1323 K, 1373 K, and 1473 K, and the Young's modulus and hardness were then measured using the nano-indenter. Both the Young's modulus and hardness results for the isothermally held specimensshowed almost constant values at a maximum indentation load of 100 mN, and monotonically increased with holding time at a maximum indentation load of 1000 mN before reaching constant values. When the specimens were heatcycled at maximum temperatures of 1323 K, 1373 K, and 1473 K, both the Young's modulus and hardness, measured at a maximum indentation load of 1000 mN, decreased with increasing heating time after reaching maximum temperature. The heating times corresponding to the maximum indentation values decreased as the heating temperatures increased. Cross-sectional observation showed that sintering of the intersplat followed by cracking occurred in the top coat. Equations to predict the changes of the Young's modulus and hardness were semi-theoretically derived and agreed with the experimental result.Key words: Thermal barrier coatings, Young's modulus, Hardness, Nano-indenter, Heat cycles English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 38-43 Effect of powder blending ratio on porous structure formed by combustion synthesis reaction between Ni and Al together with space holder Effect of powder blending ratio on porous structure formed by combustion synthesis reaction between Ni and Al together with space holder Yunmao Shu / Department of Materials Science and Engineering, Graduate School of Engineering, NagoyaUniversity,  Asuka Suzuki / Department of Materials Process Engineering, Graduate School of Engineering, NagoyaUniversity Yunmao Shu / Department of Materials Science and Engineering, Graduate School of Engineering, NagoyaUniversity,  Asuka Suzuki / Department of Materials Process Engineering, Graduate School of Engineering, NagoyaUniversity We have fabricated various porous nickel aluminides with bi-modal pore size distribution by combustion synthesis reaction between Ni and Al with NaCl space holder powder. Effects of powder blending ratio in Ni+Al+NaCl powder mixture on porosity and size of small pores derived from the reaction. NaCl powder, which is a former of large pores, affects not only the large pores but also the small pores derived from the reaction between Ni and Al. Tendencies of change in porosity and size of the small pores with the amount of NaCl were different depending on Ni:Al molar ratio. The reason was discussed in shrinkage of volume of metallic cell wall due to the formation of nickel aluminides from Ni and Al mixture.Key words: nickel aluminide, combustion synthesis, porous metal, spacer method English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 44-53 自由表面に垂直なき裂を有する傾斜機能遮熱コーティング積層板の非定常熱弾性応答 A Normal Crack in a Functionally Graded Thermal Barrier Coating Bonded to a Homogeneous Elastic Substrate under Transient Thermal Loading 上田整, 伊與田宗慶 / 大阪工業大学,  中野祐也 / 大阪工業大学大学院 Sei Ueda, Muneyoshi Iyota / Osaka Institute of Technology, Yuya nakano / Osaka Institute of Technology In this paper, the transient thermal fracture problem of a functionally graded thermal barrier coating (FGTBC) containing a normal crack bonded to a homogeneous substrate is considered. The problem is solved for the laminate that is suddenly heated from the upper surface of the FGTBC. The bottom surface of the homogeneous substrate is maintained at the initial temperature. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. By using both the Laplace and Fourier transforms, the thermo-mechanical fracture problem is reduced to a singular integral equation, which is solved numerically. The stress intensity factors of the embedded crack and the edge crack are computed and presented as a function of the normalized time for the various values of the nonhomogeneous and geometric parameters.Keywords: Functionally Graded Thermal Barrier Coating, Fracture Mechanics, Normal Crack, Integral transform, Stress Intensity Factor Japanese 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 54-57 Application of Weldable Functionally Graded Cemented Carbide to Extruder Screws Application of Weldable Functionally Graded Cemented Carbide to Extruder Screws Yoshio Nakajima, Hidenori Takahashi, Yasuki Miyakoshi / Hokkaido Research Organization, Masao Tokita, Hideo Ando / NJS Co., Ltd., Kenji Shimamura, Kenichi Satoh / Sapporo Kensaku Kogyo Co., Ltd. Yoshio Nakajima, Hidenori Takahashi, Yasuki Miyakoshi / Hokkaido Research Organization, Masao Tokita, Hideo Ando / NJS Co., Ltd., Kenji Shimamura, Kenichi Satoh / Sapporo Kensaku Kogyo Co., Ltd. Coal ash generated in thermal power plants is kneaded, extruded through a pipe by a screw, and formed into a pellet shape in extruder machines. As the screw rubs with high-hardness ash at high pressure, the edge becomes most susceptible to wear. By welding a wear-resistant material to the edge of the screw, it is possible to increase the continuous use time of such machines. Therefore, a weldable functionally graded material (FGMs), cemented carbide, was developed using the spark plasma sintering (SPS) method. This FGMs consists of three layers: wear-resistant, intermediate, and weldable layers. As these three layers have different sintering temperatures, sintering is carried out via the SPS method using an appropriate mold. The application of this material to the screw surface of an extruder results in a lifetime of approximately 3000 h, which is about three times longer than that of a conventional product coated by thermal spraying.Key words: spark plasma sintering (SPS), weldable FGMs, cemented carbide, wear resistance English 7/8/20 Journal of Functionally Graded Materials Vol.33(2019)  33  12/31/19 58-68 円板状き裂を有する傾斜機能遮熱コーティング積層板の非定常熱弾性応答 A Penny-shaped Crack in a Functionally Graded Thermal Barrier Coating Bonded to a Homogeneous Elastic Substrate under Transient Thermal Loading 上田整 / 大阪工業大学, 水澤将大 / 大阪工業大学大学院 Sei Ueda / Osaka Institute of Technology, Shodai Mizusawa / Osaka Institute of Technology In this paper, the fracture problem of a penny-shaped crack in a functionally graded thermal barrier coating (FGTBC) bonded to a homogeneous substrate is considered. The problem is solved for the laminate that is suddenly heated from the upper surface of the FGTBC. The bottom surface of the homogeneous substrate is maintained at the initial temperature. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. By using both the Laplace and Hankel transforms, the thermo-mechanical fracture problem is reduced to a singular integral equation and a system of singular integral equations which are solved numerically. The stress intensity factors of the crack are computed and presented as a function of the normalized time for the various values of the nonhomogeneous and geometric parameters.Key words: Functionally graded thermal barrier coating, Fracture mechanics, Penny-shaped crack, Stress intensity factor, Transient response Japanese 7/8/20 Journal of Functionally Graded Materials Vol.34(2020)  34  12/31/20 1-9 界面に垂直な平行き裂群を有する傾斜機能圧電積層厚板の非定常電気熱弾性応答 Transient Thermal Response of a Functionally Graded Piezoelectric Laminate with an Infinite Row of Parallel Cracks Normal to the Bimaterial Interface 上田整, 馬渕由行 / 大阪工業大学 Sei Ueda, Yoshiyuki Mabuchi / Osaka Institute of Technology In this paper, the fracture problem of a functionally graded piezoelectric material strip (FGPM strip) containing an infinite row of parallel cracks perpendicular to the interface between an FGPM strip and a homogeneous layer is considered. The problem is solved for the laminate that is suddenly heated from the surface of the FGPM strip. The surface of the homogeneous layer is maintained at the initial temperature. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. By using the Fourier transform, the thermos-electro-mechanical fracture problem is reduced to a singular integral equation, which is solved numerically. The stress intensity factors are computed and presented as a function of the normalized time for the various values of the nonhomogeneous and geometric parameters. The results for the crack contact problem are also included.Key words: Functionally graded piezoelectric material, Fracture mechanics, Stress intensity factor, Elasticity, Infinite row of parallel cracks Japanese