# Fileset [fgm-1997.xlsx](https://mdr.nims.go.jp/filesets/1198b5b0-190d-4bca-96a8-754c41fb918d/download) ## Creator National Institute for Materials Science ## Rights ## Other metadata [FY 1997 Proceedings of Functionally Gradient Materials (FGM'97) ](https://mdr.nims.go.jp/datasets/14f8da62-d4c5-4825-9403-bfdfe5442749) ## Fulltext Sheet1 BookTitle_j BookTitle_e Volume/Issue Issueddate Page Title_j Title_e AuthorList_j AuthorList_e Abstract Language １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 1-6 複合材料を基にした竹の破壊特性 Fracture Properties of Bamboo Based on Composite Material 天田重庚1)、孫運涛２）１）群馬大学２）群馬大学　大学院１）、２）376　群馬県桐生市天神町１丁目５－１ Shigeyasu Amada 1) and Yuntao Sun 2)1) Gunma University 2) Graduate School , Gunma University 1), 2) 1-5-1,Tenjin,Kiryu,Gunma 376 Functionally graded materials (FGM)1) are attracted in various fields because they can generate function as possible as they can. Bamboo is a typical, natural FGM and composite material2)3)4) and hierarchical structure5). Furthermore it has more splendid features such as a light -weight design based on hollow cylinder, very flexible6) and tough characteristics due to thin wall with discretely distributed nodes and to high strength. Most marvelous property is very fast growing speed. Growth of bamboo finishes almost within one year and the total growth ends within 5 years7). Bamboo has been used for the structural materials of foot-steps at construction sites in China, India and other countries because it has strong and tough properties. Among those properties, toughness is a main property which is closely related to resistance to fracture. Microscopically fracture of wood occurs at different level, for example, organ, tissue or cell. Fracture of woods has been discussed for various kinds and studied also on fracture mechanism9). The stress intensity factor K, strain energy release rate G and work of fracture have been measured for various woods10)11)12)13). But, the fracture properties of bamboo has not been studied yet. This paper presents fracture properties of bamboo at the macroscopic structural level based on fiber-reinforced composites and discusses on the obtained results based FGM. When bamboo is covered with heavy snow on its top, it can bend so flexibly to touch down the ground without any break. It suggests that bamboo has a higher toughness than woods. Fracture toughness is measured by tensile tests with the notched specimens. The fracture properties are given by a function of positions, that is, a graded structure of toughness is also shown. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 7-12 生物における傾斜構造発現メカニズムについて On the adaptive self-modeling mechanism of graded structure in natural composites 野方　文雄姫路工業大学　工学部　671-22　姫路市 Fumio NogataHimeji Institute of Technology, Faculty of Engineering, Himeji,671-22, Japan. It was found that plants have a cell-based sensing system for external mechanical stimuli, which is similar to the role of piezoelectric effects in bone, i.e., mechanical stress will change the resting electrical potential of plants therefore influencing the growth activity of their load carriers. The shape and ingenious construction observed in natural composites are a continuous process of the intelligent optimization based on the adaptive modelling system with a cell-based mechanosensor. It seems that this process is the best choice to survive in hard competition for energy and external mechanical condition with minimum materials that they get in the limited living space. It is also demonstrated that a man-made electric signal can manage the shape/structure of plants. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 13-19 遺伝的アルゴリズムを用いたFGM組成分布の最適設計手法 OPTIMIZATION METHOD OF FGM DISTRIBUTION PROFILE DESIGN BY GENETIC ALGORITHM 下島康嗣、山田康雄、馬渕　守、斎藤尚文、重松一典、中西　勝、中村　守、朝比奈　正名古屋工業技術研究所　(NIRIN) 462-8510 愛知県名古屋市北区平手町１丁目１番地 K. Shimojima, Y. Yamada, M. Mabuchi, N. Saito, I.Shigematsu, M. Nakanishi, M. Nakamura, T. AsahinaNational Industrial Research Institute of Nagoya (NIRIN), Hirate-cho, Kita-ku, Nagoya 462-8510, Japan The progress of technology requires high performance materials. However it is sometimes difficult to achieve the required high performance by single material. Therefore composite materials have been researched so far. Functionally graded materials (FGM), which is one of composite materials, can change the material property in each area for its objective such as heat transfer property, stiffness, and so on, by controlling a compositional distribution ratio of raw materials. Therefore we can make a product which has two or more different desirable properties in one body. However it is difficult to design a compositional distribution ratio of an FGM as a desired one, because material properties of one part relates to the other part and they are affected by its shapes and surroundings. In this paper, we propose the automatic distribution profile design system for FGM. The proposed system optimizes the distribution profile to satisfy required material properties. The design system consists of two parts: Analyzer and Optimizer. We employ the Finite Element Method as Analyzer for analysis of the state of the product and Genetic Algorithms as Optimizer for optimize of the distribution profile. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 21-26 傾斜超硬材料の開発 Development of Functionally Graded Super-hard Material 桑原光雄、船木光弘、平賀一仁、大石哲也ホンダエンジニアリング(株)埼玉県狭山市新狭山 M.Kuwabara, M.Funaki, K.Hiraga, T.OhishiHONDA ENGINEERING CO.,LTD Shinsayama Sayama-city Saitama Pref Japan A new super-hard material has been developed based on the technology gained through the research and development of ceramic production method. The new super-hard material has the characteristics of which surface has higher hardness, durability, and inside has stronger and more tenacious. This material has the functionally graded layer in mm- or cm-order, and realizes the drills, reamers, and dies that is hard to break or ware. Production line test proved it to have same or higher strength and tenacity as the high-grade super-hard material yet lasting 1.5 to 3 times longer. In this report, the mechanism of making this material is described. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 27-32 傾斜型アルミナ円板およびパイプの作製 Fabrication of Graded Alumina Disk Board and Pipe 小林弘旺産業技術短期大学 H. KobayashiCollege of Industrial Technology The functionally graded alumina disks with different porosity and structure were fabricated by powder stacking and pressureless sintering process, using alumina-graphite mixed powders or two types of alumina powders having different sintering characteristics. Wet powders with a large quantity of binder were laminated into a mold, and then were compacted by the vibration pressing method. The functionally graded disks were free from cracks,although they were curved by the difference of linear shrinkage. The satisfactory flat disks were obtained by the fanwise shape of green compact. The functionally graded alumina pipes were fabricated in plaster molds by the planetary slip casting method. Each slurry was casted into the molds set on a disk revolved both round its axis and on their axis. The graded pipes with different porosity and structure were free from cracks and warps. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 33-38 SHS/HIP法によるZrO2-Al2O3/Cr3C2/Ni FGM作製および特性評価 Fabrication and Characterization of Zro2-A12O3/Cr3C2/Ni FGMs by SHS/HIP C.Divakar１）、宮本欽生２）、山口修３）１）大阪大学　接合科学研究所　567大阪府茨木市（National Aerospace Laboratories, Bangalore 560017, India より来日）２）大阪大学　接合科学研究所　567大阪府茨木市３）同志社大学　工学部　 610-03 京都府京田辺市 C.Divakar1), Y.Miyamoto2) and O.Yamaguchi3)1) Joining and Welding Research Jnstitute, Osaka University, Ibaraki 567, Osaka, on leave from National Aerospace Laboratories, Bangalore 560017, India 2) Joining and Welding Research Institute, Osaka University, Ibaraki 567. Osaka 3) Faculty of Engineering, Doshisha University, Tatara, Kyotanabe, Kyoto 610-03 Zirconia based ceramics are potential materials for aerospace applications because of their high melting points and oxidation resistance. The ZrO2- Al2O3 / Cr3C2- Al2O3-Ni / Cr3C2- Ni Functionally Graded Materials with 30 mm diameter and 5mm thickness were fabricated at 100 MPa nitrogen pressure using the SHS/HIP process. The FGMs have been characterized by hardness, fracture toughness, bending strength measurements and microscopic studies. The surface residual stress measured by x-ray diffraction were 100 Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 39-43 固液拡散によるTi-Al系傾斜機能材料の作製 Production of Ti-AI FGM by solid-liquid diffusion ○鈴木　勲1)、桐原聡秀1)、鈴木徹也2)、辻本得蔵2)1)茨城大学　大学院　316　日立市2)茨城大学工学部　316　日立市 I.Suzuki1), S.Kirihara1), T.Suzuki2), T.Tsuzimoto2)1)Graduate student, Ibaraki University, Hitachi 316, Japan 2)Faculty of engineering, Ibaraki University, Hitachi 316, Japan Although metal/ceramic FGM is ideal heat resisting material, its practical use has been restricted strongly with drawbacks such as crack generation by thermal stress and complicated manufacturing process of high cost. In this study, Ti/ Ti-Al FGM has been tried to produce by a simple method, i.e., solid-1iquid diffusion. Ti-Al intermetallic compound has a superior oxidation resistance and has comparatively close thermal expansion coefficient with Ti. In the present experiment, Ti plates were placed in contact with liquid of Al3Ti powder under various heating conditions, which resulted in formation of various reactants. Ti/Ti-Al FGM produced by heat treatment at 1417deg.C for 15min exhibited a good structural gradient consisting of Al5Ti2, TiAl, Ti3Al, and alpha Ti. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 45-50 湿式濾過法を用いた傾斜空隙構造を有する多孔体の作製法 Preparation of Porous Materials with Continuous Porosity Profile by Use of Filtration Method ○岩田政司,下野　晃,国技義彦,白塚山泰人,木城きくか,濃野将典鈴鹿工業高等専門学校　510-02　鈴鹿市 M.Iwata,A.Shimono,Y.Kunieda,Y.Shiratsukayama,K.Kishiro,M.NonoSuzuka National Conege of Technology,Suzuka 510-02,Japan A preparation method which can smoothly vary the porosity of a sintered material is proposed. A packing method based on semi-batchwise filtration operation of two suspensions is applied. A suspension of inorganic particles is put into a mixing tank, followed by a filtration of the suspension.Then, a suspension of carbonaceous particles is fed in continuously to the tank. The composition profile of the filter cake varies smoothly in the direction of cake thickness. After drying and consolidation of a filter cake, it is 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, provided that sedimentation of particles is negligible. Effect of sedimentation can be evaluated by making Ruth plots. It is concluded that in a packing of fine particles by semi-batchwise filtration an easy-to-filter-material should be selected as filter aid. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 51-56 湿式加圧成形法によるWSi2/ZrO2(2Y)系FGMの作製 Fabrication of Functionally Graded WSi2/ZrO2(2Y) Materiais Using Wet-Molding 荒田　顕司、芳仲　捷、廣田　健、山口　修同志社大学　工学部　610-03　京都府京田辺市 K. Arata, M. Yoshinaka, K. Hirota, and O. YamaguchiFaculty of Engineering, Doshisha University, Kyo-Tanabe Kyoto 610-03 , Japan Continuously graded WSi2/ZrO2(2Y) materials with high density (99.2% of theoretical) have been fabricated by uniaxial wet-molding, followed by hot pressing (1000deg.C/1h/30MPa) and hot isostatic pressing (1500deg.C/2h/196MPa). A mixed solution of glycerin and ethanol with the viscosity of =6 mPa*s has been used as a dispersion medium in molding process. The sintered materials show a linear composition profile with a transition from WSi2/ZrO2(2Y)=75/25 to =5/95 mol%. Vickers hardness Hv, in which the value is =11.2 GPa, is almost independent of the compositional change. Fracture toughness Kc increases from 5.6 to 10.3 MPa* m1/2 with increasing ZrO2(2Y) composition. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 57-62 共晶反応を利用した金属/金属間化合物傾斜機能材料の創製 Development of Metal/Intermetallic Compound Functionally Graded Material by Utilizing Eutectic Reaction ○桐原聡秀1〕、土田祐樹1)、友田陽2)、辻本得蔵2)1)茨城大学　大学院生、2)茨城大学　工学部　316　日立市 S. Kirihara1), Y. Tsuchida1), Y. Tomota 2), T. Tsujimoto 2)1) Graduate Student, Ibaraki Uhiversity 2) Faculty of Engineering, Ibaraki University, Hitachi 316, Japan An eutectic melting reaction was utilized for production of functionally graded materials (FGMs) by the present authors. Two different materials were joined by the eutectic reaction, and a mixed structure was formed with compositional gradient between those materials . In this study, metal/intermetallic compound (IMC) FGMs were fabricated by bonding metals with IMCs plates or coating IMC powder for metal pieces. The former technique was named an eutectic bonding method, and the latter was named an eutectic coating method. Ti/Ti3Sn and Ti/Ti5Si3 FGMs had been fabricated by those methods, and a thermal shock test had been carried out for them. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 63-68 共晶融液浸透法により作製したFGMにおけるセラミックス焼結体の密度と組成傾斜部組織の関係 Relation between Density of Sintered Ceramics and Structure of Compositionally Graded Part in FGM Which Is Made by Eutectic Melt Infiltrating Method 小林誠司1)、桐原聡秀1)、辻本得蔵2)1)茨城大学　大学院生、2)茨城大学　工学部　316　日立市 S.Kobayashi1),S.Kirihara1),T.Tsujimoto2)1)Graduate Student, Ibaraki University, Hitachi , Japan, 316 2)Faculty of Engineering,Ibaraki University,Hitachi , Japan,316 A eutectic melt infiltrating method is a way which forms compositional gradient part by making eutectic melt infiltrate through numerous holes of sintered ceramics. In this paper, the effects of the sintered ceramics density on structure and width of the compositional gradient part have been examined. The density of sintered ceramics was controlled by adding Ni(C) powder to the ceramics powder. The whole density of the sintered ceramics was measured by the Arkhimedes method and the surface density by picture-analyzing the microstructure observed by SEM. In making FGM the following properties are required for the sintered ceramics: a)The density of the sintered ceramics is high on both the planes of the metal side and of the end side. b)The density is rather less in the middle part of the sintered ceramics. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 69-74 ZrO2/Ni系FGMの熱衝撃試験における縦割れと界面はく離の相互作用(ZrO2/Ni系FGMコーティングヘのレーザ改質の適用に関する検討) Interaction Between Vertical Cracks and Interfacial Delamination under Thermal Shock Test of ZrO2/Ni FGM (Effect of Laser Cracking Method on ZrO2/Ni FGM) ○森谷信一、黒田行郎、只野　真、佐藤政裕、新野正之航空宇宙技術研究所　宮城県角田市 S.Moriya, Y.Kuroda, M.Tadano, M.Sato, M.NiinoNational Aerospace Laboratory, Kakuda City, Miyagi Pref., Japan Ceramic-metal functionally graded materials are newly-developed composite materials . Since the materials have attractive advantages in severe thermal-mechanical and chemical environments, they have been developed as advanced materials in aerospace engineering, nuclear engineering, etc. Currently, a ZrO2/Ni FGM is being investigated in Japan as a new chamber inner-wall material of rocket thrust engines to improve their performance; the main problem has been found to be the damage of the material under burner heating conditions, such as the spalling at the heated ceramic surface, vertical cracking perpendicular to the heated surface, and interfacial delaminations between the ZrO2 layer and FGM layer and between the FGM layer and Ni substrate. To improve the resistance to the damage, a laser thermal shock pre-treatment for the material has been tried and some preliminary experiments have been done. It has been shown that the laser thermal shock pre-treatment, which is used to introduce pre-vertical cracks at the ceramic surface before the service, may be an effective method for the improvement of the resistance to the service damage. In this study, to understand the damage mechanism and to establish an optimum design of the material, a numerical analysis was conducted. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 75-80 SiC傾斜組成炭素繊維複合材料の耐酸化性及び耐熱衝撃性 Oxidation and thermal shock resistance of SiC compositionally graded carbon fiber reinforced carbon composite materials 藤井貴美夫　山田禮司日本原子力研究所　茨城県東海村 K. Fujii and R. YamadaJapan Atomic Energy Research Institute, Tokai-mura Ibaraki-ken, Japan Oxidation and thermal shock resistance of SiC compositionally graded carbon fiber reinforced carbon composite (CFRC) materials that are composed of a CVD SiC layer, a SiC/C layer and a CFRC substrate was studied by oxidation and thermal shock tests in air. Two types of CFRCs were used: 1-D continuous fiber reinforced and 2-D felt reinforced composites. It was found that a SiC/C layer was to some extent effective to increase the resistance and that its effectiveness was larger when a difference in thermal expansion coefficient (CTE) between a substrate and beta-SiC was smaller. The degree of improvement in the oxidation and the thermal shock resistance for CFRC substrates was lower than that for isotropic graphite substrate. The above difference was attributed to erosion of carbon by oxidation through cracks in CVD SiC layer that occurred during the coating due to a large mismatch of CTEs between beta-SiC and CFRC substrates. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 81-88 熱応力緩和層を有する再使用型高性能エンジンの開発 Development status of the reusable high performance engines composed of FGMs with thermal stress relaxation ○黒田行郎1)、日下和夫1、毛呂明夫1)1)　航空宇宙技術研究所、角田宇宙推進技術研究センター　宮城県 Y.Kuroda1), K.Kusaka1), A.Moro1)1) Kakuda Research Center, National Aerospace Laboratory, Miyagi, Japan The development study of the two kinds of reusable high performance engine is described. One is the ZrO2/Ni FGMs chambers. This engine is the promising candidate for the future Japanese orbiting maneuvering system (OMS) engine of the H- II orbiting plane (HOPE). The other one is the reaction control system (RCS) engine which may also be used compatibly with HOPE. Developed RCS chambers are made of carbon fiber-reinforced carbon matrix (C/C) composites coated with SiC FGMs. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 89-94 C/C複合材のロケット燃焼室への適用《C/C-SiC(FGM)燃焼器耐久性評価試験》 Application of C/C composites to rocket combustion chambers (Evaluation test of C/C-SiC (FGM) coatings to combustion chambers) ○日下和夫1〕、只野　真1)、佐藤政裕1)　黒田行郎1)　早田喜穂2)、久手幸徳2)、木内規之2)1)　航空宇宙技術研究所　角田宇宙推進技術研究センター宮城県角田市2)　日本石油株式会社　中央技術研究所　231　横浜市 K. Kusaka l), M. Tadano l), M. Sato l), Y, Kuroda 1) Y. Sohda 2), Y. Kude 2), N. Kiuchi 2)1) Kakuda Research Center, NAL, Kakuda, Miyagi, Japan 2) Nippon oil company, Ltd. , Yokohama 231, Japan Maximizing the performance levels of the chambers, along with increasing their durability and lighteing their weight, are inportant objectives that must be achieved in order to realize the reusability of the thrust engines for the orbital transfer vehicles. Carbon fibers-reinforced carbon matrix (C/C) composites are one promising candidate for a substance which meets these requirement, because of their superior properties, such as high specific strength, specific modulus, and fracture strength at high temperatures. Firing tests were performed, at Pc=1.0 MPa, MR=1.65, to evaluate the durability using the two types of C/C-SiC (FGM) chambers, i. e. , the nozzle expansion ratio epsilon of the first developed chambers is 1.75 (1st), and that of the other one is 30 (2nd). The items evaluated in the test series were, (1) Durability under reperted combustion tests and, (2) Engine performance. We inspected the chamber damage using the non-destructive method after the firing tests. In the second generation of the chamber, the 3600 successive combution tests that we originally aimed for were successfully completed. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 95-100 回収型カプセルによるSiC/C-FGM複合材の実環境評価 Results of High Performance Material Experiment (HIPMEX) on C/C composites with SiC/C-FGM coating 木内規之、久手幸徳、井土泰二、早田喜穂日本石油(株)　中央技術研究所　ニューマテリアル研究室231　神奈川県横浜市中区千鳥町 N. Kiuchi, Y. Kude, Y. Ido and Y. SohdaNew Materials R&D Division Central Technical Research Laboratory Nippon Oil Company, Ltd. , 8, Chidori-cho, Naka-Ku, Yokohama, 231 Japan High Performance Material Experiment (HIPMEX) is object to evaluate high-temperature material (C/C composites with SiC coating) under the actual reentry environment. C/C composites were prepared with plain laminates. SiC/C-functionally graded material (FGM) coating was applied for the oxidation protection of C/C composites. The C/C composites with FGM coating was mounted on the surface of the reentry capsule. After the experiment in the actual reentry environment, specimens were analyzed. As a result, it was found that there was no damage on the FGM coating of material. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 101-106 SiCコーティングのインピーダンス特性について Impedance Characteristics of SiC Coadng ○若松義男1)、庄子哲雄2)、小川和洋3)、齋藤俊仁1)1)　航空宇宙技術研究所　角田宇宙推進技術研究センター　981-15　宮城県角田市2)　東北大学　工学部　981　宮城県仙台市3)　東北大学　大学院　981　宮城県仙台市 Y. Wakamatsu1),T.Shoji2),K.Ogawa3) and T.Saito1)1) Natioal Aerospace Laboratory, Kakuda Research Center, Kakuda, Miyagi 981-15 Japan 2) Tohoku University, Department of Technology, Sendai, Miyagi 981 Japan 3) Tohoku University, Graduate School, Sendai, Miyagi 981 Japan CC composites coated with SiC/C FGM had been evaluated under simulated conditions for an aerospace application. FGM layer of specimens showed a fairly good durability on the heating test in a high speed hot air flow. On the other hand, damage was found on a coating layer of SiC. It means that a study of the behavior of oxidation of SiC and a quantitative non-destructive evaluation technology of SiC coating are very important for practical use of CC composites. Authors paid attention to an impedance characteristic of SiC and started the study to apply an impedance spectroscopy method into the quantitative non-destructive evaluation. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 107-111 超構造熱電材料における次元性の効果と傾斜構造の適用性 Dimensionality Effects on Thermoelectric Properties and its Application for Functionally Graded Structures 吉野淳二東京工業大学　理学部　152　東京都目黒区 J. YoshinoTokyo Institute of Technology, Department of Physics, Meguro-ku, Tokyo 152, Japan Thermoelectric figure of merit for low dimensional systems have been evaluated based on Boltzmann equation and relaxation time approximation assuming SiGe as quantum well materials. Although calculated energy dependence of differential conductivity for three, two, and one dimensional systems are very similar to each other, it is found that dimensionless thermoelectric figure of merit, ZT, is enhanced with decreasing dimension. Enhancement of factor of three on ZT has been expected for modulation doped one dimensional systems. However, ZT almost linearly depend on temperature like bulk SiGe, and therefore it seems that these systems are not adequate for application of functionally graded structures. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 113-116 段階的添加法により作製した傾斜機能材料の電気的特性 The Electrical Properties of Functionally Graded Materials Manufactured by a Progressive Lamination Method 保母康雄　石倉俊宏　林　二一　渡辺茂男　内田悦行　比嘉俊太郎愛知工業大学 Y.Hobo, T.Ishikura, N.Hayashi, S.Watanabe, Y.Uchida, S.HigaAichi Institute of Technology Various kinds of insulating materials are used to shield electrical machinery. In order to enhance the operating performance of machines still further, it is necessary to use ever better insulators. Two solutions are available to meet this demand: either the development of new materials, or the control of electrical fields within existing materials. The authors have attempted to manufacture a material permitting the control of field force.s with the aid of the benefits provided by functionally graded materials (FGMs). The basic idea behind their thinking is to guard against damage to machinery by bringing about relaxation in those parts where field forces are too high, and increasing forces in parts where they are too low. The FGMs described in this paper are combined from titanium oxide mixed with barium, and Korean kaolin. They allow a graded change in relative permittivity between the two surfaces. The paper compares the relative permittivities of these FGMs with those of 15 kinds of uniform material. There is a concluding discussion on the field relaxation effect. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 117-122 FGMの出力特性測定について Quantitative EValuation of Effective Maximum Power of FGM 篠原嘉一、今井義雄、磯田幸宏、西田勲夫金属材料技術研究所　茨城県つくば市 Y. Shinohara, Y.Imai, Y.Isoda and I.A.NishidaNational Research Institute for Metals, Tsukuba, Ibaraki, Japan Measurement of effective maximum power Pmax is necessary to evaluate the power generating performance of functionally graded thermoelectric materials (FGM). The reliable value of Pmax can be obtained only from the accurately measured values of internal resistance rint and thermoelectromotive force Eo under a temperature difference delta T. The measured values are changed by i)the Peltier heat and the Joule heat, ii)the thickness of the lead connected with an electrode, iii)the current density and the flow direction of current, iv)the environmental pressure, and so on. Electrical resistivity rho at room temperature with these factors was measured at the beginning, and the effects of these factors on rint and Eo under delta T were investigated to heighten the reliability of the measured values. On the basis of these results, Pmax of FGM was evaluated quantitatively. The value of Pmax was highly reproductive, and its temperature dependence was agreed well with the estimated value from the thermoelectric properties of constitutional materials. It is concluded that the reliable evaluation of Pmax has been realized by this study. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 123-128 FGMデータベースシステム FGM Database System ○木皿且人、毛呂明夫、康燕生、新野正之航空宇宙技術研究所 K. Kisara, A. Moro, Y.S.Kang, M. NiinoNational Aerospace Laboratory This report will introduce the concept and status of a database system for anational project entitled: A Study in the Development of Energy Conversion Materials through the Formation of Gradient Structures Angstrom h, which project is being promoted by some thirty-odd industrial, academic and govemmental organizations. While the database system will be, organizationally speaking, somewhat loose-knit, it is expected that the project's initial goal will be realized within a fixed period of time. In order to provide a convenient means of comunication for researchers working in various organizations to exchange information, complete their work assignment in a short space of time and maintain a common perspective, the establishment of some method of information-sharing is essential. At the same time the report will describe measures of the need for maintenance of the database and a network to make use of it in real time so as to promote support for the project and, additionally, show that the use of the Internet is a viable method of operating the system at this present time. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 129-134 低温用熱電材料のFGM化 FGM formation of thermoelectric materials for low temperature range 腰越美営1)、工藤康全2)、橋本政靖2)、塩田一路1)、西田勲夫3)1)工学院大学　192　東京都八王子市2)工学院大学　大学院　192　東京都八王子市3)金属材料技術研究所　305　茨城県つくば市 M.Koshigoe1), Y.Kudo2), M.Hashimoto2), I.Shiota1) and, I.A.Nishida3)1)Kogakuin University, Hachioji-City, Tokyo 192 Japan 2)Kogakuin University (Gra.), Hachioji-City, Tokyo 192 Japan 3)National Research Institute for Metals, Tsukuba-City, Ibaraki 305 Japan FGM forming is one of promising methods to improve the efficiency of thermoelectric materials. Soldering is the most simple and feasible method to join materials with difference carrier concentration. High melting point solder (m.p.497K) is traditionally used to join Bi2Te3. However, the melting point of the solder is too low to use in the FGM. Bi-2.5mass%Ag eutectic alloy has a melting point of 535K, which is 40K higher than traditional one. Moreover no electric barrier can be worried at the interface, because of its low electric resistivity. In this report, feasibility of Bi-2.5mass%Ag eutectic alloy was studied as the soldering material for Bi2Te3. Wettability of the alloy was remarkable when flux was applied. A reacted layer was observed between the solder and Bi2Te3, of which main composition was Bi. Electric resistivity at the joined part was higher than we expected. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 135-140 異なるキャリア濃度のPbSnTe系接合体の熱電特性 Thermoelectric Properties of Joined PbSnTe System with Different Carrier Concentrations 磯田幸宏1）、篠原嘉一2）、今井義雄2）、西田勲夫2),橋本政靖3）、海部宏昌4）、大橋修5)1)新潟大学　大学院生　950-21　新潟市2)金属材料技術研究所　305　茨城県3)工学院大学　大学院生4)東京都立大学　192-03　東京都5)新潟大学　950-21　新潟市 Y.Isoda1), Y.Shinohara2), Y.Imai2), I.A.Nishida2) ,M.Hashimoto3), H.T.Kaibe4),0.0hashi5)1) Graduate Student, Niigata University, Niigata 950-21,Japan 2) National Research Institute for Metals,Ibaraki 305,Japan 3) Graduate Student,Kogakuin University, Tokyo 192,Japan 4) Tokyo Metropolitan University,Tokyo 192-03,Japan 5) Niigata University,Niigata 950-21,Japan The effect of joined interface on thermoelectric properties of the joined material has been evaluated to develop higher performance of PbSnTe FGM. Pb0.75Sn0.25Te and Pb0.5Sn0.5Te discs cut from the solidified ingots were joined at 700K by the liquid phase diffusion bonding technique. Pb0.75Sn0.25Te with low hole concentration nh and Pb0.5Sn0.5Te with high nh were for low and high temperatures, respectively. Electrical resistance R, thermal conductivity kappa and Seebeck coefficient alpha were measured at 300K. Since the joined interface showed a value of 10 micro ohm mm**(-2), R of the joined material was 14% higher than the total R of Pb0.75Sn0.25Te and Pb0.5Sn0.5Te discs. However, the measured values of kappa and alpha of the joined material were agreed well with the estimated values from kappa and alpha of ingots. It is clear that the joined interface has little thermal resistance, and that only R is affected by the joining technique. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 141-146 キャリア濃度傾斜化PbTeの出力特性 Power Output Characterization of Functionally Graded Materials Controlled Carrier Concentration of PbTe by Joining Melt-grown Materials 折橋正樹(1)*、野田泰稔(2)、陳　立東(1)、康　燕生(3)、毛呂明夫(3)、平井敏雄(1)1)東北大学　金属材料研究所　980-77　宮城県仙台市青葉区片平2-1-12)東北大学　大学院工学研究科　980-77　宮城県仙台市青葉区荒巻字青葉3)航空宇宙技術研究所　角田宇宙推進技術研究センター981-15　宮城県角田市君萱小金沢１ Masaki Orihashi(1)*, Yasutoshi Noda(2), Lidong Chen(1) , Yansheng Kang(3), Akio Moro(3) and Toshio Hirai(1)(1) Institute for Materials Research, Tohoku University, 2-1-1 , Katahira, Aoba-ku, Sendai, Miyagi 980-77, Japan (2) Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-77, Japan (3) National Aerospace Laboratory, Kakuda Research Center, Koganezawa 1 , Kimigaya, Kakuda, Miyagi 981 -15, Japan The 2-stage functionally graded materials (FGM) of carrier concentration controlled PbTe were prepared by plasma activated sintering (PAS) joining the discs cut from melt-grown PbTe ingots. The component materials of PbTe ingots were prepared by the Bridgman method with 2000 and 4000 mol ppm PbI2 as n-type dopant, respectively. The thermoelectric characterization of the FGM was made in the temperature range from 300 to 700 K. The thermoelectric power (alpha) and the electrical conductivity (sigma) for the FGM was almost intermediate between those for the components. Output power of the FGM was estimated under the large temperature span (delta T), which was 4.5 mW under delta T=200 K at maximum. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 147-151 PAS法によるセグメント型熱電変換素子の作製と評価 Preparation and characterization of segmented thermoelectric elements 康燕生1）、野田泰稔2〕、Jurgen Schilz1)、 新野正之1）1)航空宇宙技術研究所　角田宇宙推進技術研究センター　981-15　宮城県角田市　2)東北大学　工学部　材料物性学科　980-77　宮城県仙台市 Yan-Sheng Kangl), Yasutoshi Noda2), Jurgen Schilz1), Masayuki Niino1)1) National Aerospace Laboratory, Kakuda Research Center, Kakuda-City, Miyagi 981 -15, Japan 2) Tohoku University, Department of Materials Science, Sendai, Miyagi 980-77, Japan In order to explore a high conversion efficient thermoelectric device, which can cover a wide range from an intermediate temperature to room temperature, we have developed a method to synthesize a segmented thermoelectric element. This kind of element was composed of a semiconductor of PbTe, a Bi-Te base solid solution and metallic electrodes of Ni, Cu, or Fe and Al. We prepared the segmented element by a process of plasma activated sintering (PAS) and we characterized the electric and metallographic properties of joint between semiconductor/semiconductor and metal/semiconductor junctions. The element was prepared by two stages of PAS those included different sintering temperatures for densifying semiconductor materials. The observation of SEM and analysis result of EPMA indicate that the joint of metal/semiconductor or semiconductor/semiconductor has no crack and nor severe reaction except at the Cu/semiconductor interface. The results of inspection of potential voltage profiles indicate that low resistive junctions such as Ni/Bi2(Te,Se)3/Ni/PbTe for n-type and Ni/(Bi,Sb)2Te3/Ni/SnTe/PbTe/SnTe/Ni for p-type are successfully prepared and they are expected for composing segmented thermoelectric branches in an electric generator. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 153-157 Bi-Te/FeSi2型セグメント熱電素子の成形 Formation of Bi-Te/FeSi2 based segmented thermoelectric elements Jurgen Schilz 1)、康燕生 l)、野田泰稔２）、新野正之１）１）航空宇宙技術研究所　角田宇宙推進技術センター　981-15　宮城県角田市君萱字小金沢１　e-mail: juergen.schilz@dlr.de ２）東北大学　大学院工学研究科　工学部材料物性学科　980-77　宮城県仙台市青葉区荒巻 Jurgen SCHILZ 1), Yan-Sheng KANG l), Yasutoshi NODA 2), Masayuki NIINO 1)1) National Aerospace Laboratory (NAL), Kakuda Research Center, Koganezawa 1 , Kimigaya, Kakuda-City, Miyagi-Pref. 981-15, Japan, e-mail: juergen.schilz@dlr.de 2) Tohoku University, Faculty of Engineering, Department of Materials Science, Aramaki, Aoba, Aoba-ku, Sendai, Miyagi-Pref. 980-77 We report on the development of a stacked thermogenerator element consisting of bismuth-telluride (Bi-Te) based materials for the low temperature and iron disilicide (FeSi2) for the high temperature stage. Starting materials were prealloyed and doped semiconductor powders, which were consolidated and joined by means of uniaxial hot pressing (plasma activated sintering). Due to the large difference in thermophysical and thermomechanical properties, Bi-Te and FeSi2 cannot be directly joined in a single processing step. Therefore we investigated the use of Ni as a suitable common interface material with intermediate coefficient of thermal expansion. It is known that Ni gives a thermally and electrically stable joint to Bi-Te. A joint of Ni to FeSi2, however, was found to be not thermally stable due to the development of a too large thermal strain. FeSi2 has obviously a very low yield strength. Therefore an additional interface is required to release the occuring thermal stresses. We have identified nickel-iron based (NiFe) as applicable materials for this purpose. From the standpoint of electrical and thermal transport, all junctions exhibit reliable properties. Problems are occurring at the FeSi2/NiFe interface, as here a reaction layer develops which has obviously different thermomechanical properties than the parent materials. This reaction layer causes the junction to break after an additional heat treatment. For a further improvement a third interlayer has to be found which reduces the reaction Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 159-164 AgSbTe2系化合物の熱電特性 Thermoelectric Properties of AgSbTe2 米田征司1)、太田英二2)、今井義雄3)、篠原嘉一3)、磯田幸宏4)、木村隆3)、西田勲夫3)、海部宏昌5)1)慶應大(院)、2)慶應大　223　神奈川県横浜市　（慶応義塾大学）3)金属材料技術研究所　305　茨城県つくば市4)新潟大学　大学院生　950-21　新潟県新潟市5)東京都立大学　192-03　東京都八王子市 S. Yoneda1), E. Ohta2), Y. Imai3), Y. Shinohara3), Y. Isoda4), T. Kimura3), I.A. Nishida3) and H.T. Kaibe5)1) Graduate Student, Keio University, Yokohama, Kanagawa 223 , Japan 2) Keio University, Yokohama, Kanagawa 223 , Japan 3) National Research Institute for Metals, Tsukuba-shi, Ibaraki 305, Japan 4) Graduate Student, Niigata University, Niigata, Niigata 950-21 , Japan 5) Tokyo Metropolitan University, Hachioji, Tokyo 192-03, Japan Thermoelectric properties of unidirectionally solidified p-type AgSbTe2 boule have been evaluated to develop functionally graded thermoelectric materials (FGM) with complex structure of Ag2Te and Sb2Te3. The boule had two kinds of different structures in it; one is Widmannstatten structure near the surface of boule, and another is eutectic structure in the center of boule. The eutectic structure contained more Ag2Te precipitates. Both the structures showed the different temperature dependence of thermoelectric properties, which were strongly affected by the transformation at 418 K and also 633 K. High temperature phase of AgSbTe2 above 633 K revealed its high potential of power generation. These results suggest that there is a high possibility to realize superior FGM by controlling structure. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 165-169 p型中温域熱電材料の作製と熱電特性 Preparation and Thermoelectric Properties of p-type Pb1-xSnxTe(x=0.00-0.50) and AgSbTe2 野田泰稔1)、西田勲夫2)、康燕生3)、新野正之3)1)東北大学　980-77　宮城県仙台市2)金属材料技術研究所　305　茨城県つくば市3)航空宇宙技術研究所　角田宇宙推進技術研究センター　981-15　宮城県角田市 Y. Noda1). I. A. Nishida2). Y. -S. Kang3). M. Niino3)1)Tohoku University, Sendai-City, Miyagi 980-77, Japan 2)National Research Institute for Metals, Tsukuba-City, Ibaraki 305, Japan 3)National Aerospace Laboratory, Kakuda Research Center, Kakuda-City, Miyagi 981-15, Japan The thermoelectric materials of Pb1-xSnxTe(x=0.00-0.50) and AgSbTe2 were prepared by melt-growth and plasma-activated sintering (PAS). As-grown ingots were characterized by conposition analysis and thermoelectric measurements. The uniform composition profile was detected in the region of 80 % of total length of both Pb1-xSnxTe and AgSbTe2 ingots, while some fluctuations in semiconductive properties were observed in AgSbTe2 ingot. The carrier concentration of Pb1-xSnxTe changed in the order of magnitude from 10**(18) to 10**(20) cm-3 with an increase of x, and that of AgSbTe2 was in 10**(19) cm-3. The semiconductive properties for AgSbTe2 were characterized by larger thermoelectric power and lower Hall mobility than those for Pb1-xSnxTe. By using literature data of thermal conductivity, the figure of merit estimated at 300 K for PAS-AgSbTe2 was 9.72 x 10**(-4) K-1, which was 2-7 times larger than those for PAS-Pb1-xSnxTe. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 171-176 PbTe系熱電材料の液相拡散接合 Liquid Phase Diffusion Bonding of PbTe system 橋本政靖1)、塩田一路2)、大橋　修3)、海部宏昌4)、今井義雄5)、篠原嘉一5)、西田勲夫5)1)工学院大学　大学院、2)工学院大学　192　東京都八王子市3)新潟大学　950-21　新潟県新潟市4)東京都立大　192-03　東京都八王子市5)金属材料技術研究所　305　茨城県つくば市 M. Hashimoto1), I. Shiota2), O. Ohashi3), H. T. Kaibe4), Y. Imai5), Y. Shinohara5), I. A. Nishida5)1)Kogakuin University, Grad., Hachioji, Tokyo, 192, Japan 2)Kogakuin Uuiversity, Hachioji, Tokyo, 192, Japan 3)Niigata University, Niigata, Niigata, 950-21, Japan 4)Tokyo Metropolitan University, Hachioji, Tokyo, 192-03, Japan 5)National Research Institute for Metals, Tsukuba, Ibaraki, 305, Japan The solidified PbTe system compounds with different carrier concentrations were joined by liquid phase diffusion bonding technique, in order to prepare the segmented thermoelectric materials with 2-stages of carrier concentration as a constructions of FGM. PbI2-doped PbTe compounds were for the segmented n-type material and Pb1-xSnxTe compounds were also for the p-type material. Pb-60mass%Sn alloy with 50 micro meter in thickness as soldering material was inserted into the interface between the PbTe compounds and the joining was performed under 2.0MPa at 700K for 900s in Ar . The observations by means of both optical and electronic microscopes revealed that insert metal was melted and reacted with PbTe to form an alloyed layer of less than 2 micro meter in thickness. No remarkable increase in resistivity was confirmed in the vicinity of the interface. The mechanical strength over the interface was maintained in heating up to 676K. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 177-182 n型PbTeにおける製造工程の特性に与える影響 Influence of Solidification Process on Thermoelectric Properties of n-type PbTe. 黒崎美奈1)、橋本政靖1)、塩田一路2)、西田勲夫3)1)工学院大学　大学院　192　東京都八王子市2)工学院大学　192　東京都八王子市3)金属材料技術研究所　305　茨城県つくば市 M .Kurosaki1),M.Hashimoto1),I.Shiota2)and I.A.Nishida3)1)Kogakuin University (Gra), Hachioji-City, Tokyo 192 Japan 2)Kogakuin University, Hachioji-City, Tokyo 192 Japan 3)National Research Institute for Metals. Tsukuba-City. Ibaraki 305 Japan FGM (functionally graded material) forming is one of promising methods to improve the efficiency of thermoelectric materials. Materials with well controlled electric properties due to carrier concentration are required to from the FGM. However, the carrier concentration in a fabricated material often deviates from the expected one, and uniformity of the carrier concentration in an ingot also largely varies. Effects of the volume of the cavity of a quartz tube, time of melting and agitation, and solidification rate were inveastigated to establish the fabrication condition of n-PbTe. The carrier concentration in an ingot, which was fabricated in a large quartz tube, was less than one in a small tube, though the amount of the added dopant was the same. It may be caused by evaporation and deposition of the dopant in the large cavity. No difference of the thermoelectric properties was observed when the melting and agitation time was longer than 15min. The carrier concentration was uniformly distributed in an ingot when the solidification rate was high. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 183-188 インサート材を用いた異キャリア濃度PbTe接合材の熱電特性 Thermoelectric Properties of PbTe Sintered Conpact of Two Layers with Carrier Concentrations Having Insert Metal at a Interface. 今井義雄、篠原嘉一、磯田幸宏、西田勲夫金属材料技術研究所　茨城県つくば市 Y. Imai, Y. Shinohara, Y. Isoda, I.A.NishidaNational Research Institute for Metals, Tsukuba, Ibaraki, Japan PbI2-doped PbTe with a graded carrier concentration ne has a risk that the gradient would be lost at high temperature, if the diffusionis of PbI2 is not controlled. Starting powders with different ne were prepared by crashing n-type PbTe ingots doped with different amounts of PbI2, and were hot pressed with an inserted Fe foil to form a PbTe sintered compact of two layers with different ne. We investigated the sinterbility, the interfacial characteristic and the thermoelectric properties of the compacts. The results showed; 1) Two-layered compacts of high density were obtained at hot-press temperatures of 1073 and 1023K. 2) An excellent interface was obtained at 1023K. The interface at 1073K was not as good. It was caused by the reaction between Fe and PbTe. 3) A two-layered compact at 1023K showed higher Seebeck coefficient and maximum power than each of the constitutional compacts. 4) The iron is promaising as an insert material to suppress the diffusion of PbI2 between PbTe layers. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 189-194 不純物添加と焼結体ミクロ構造の複合傾斜化の熱電機構 Thermoelectric Mechanism of Impurity Doped and Hot Pressed Thermoelectric Material with Microstructure of FGM 梶川武信1)、志田啓亮1)、白石健太郎1)、大森　守2)、平井敏雄2)1)湘南工科大、2)東北大学　金属材料研究所 T.Kajikawa1) ,K.Shida1),K. Shiraishi1),M.Omori2),T.Hirai2)1) Shonan Institute of Technology, 2) Institute of Material Research, Tohoku University Thermoelectric and electrical transport mechanisms of impurity doped and hot pressed thermoelectric material have been investigated in order to establish the FGM thermoelectric element, of which the performance is broad for wide temperature range. The sintered structure has the complex relationship between the production parameters and the thermoelectric performance. Antimony doped, hot-pressed magnesium silicide made by spark plasma sintering has been studied in this research. In the experiment the temperature dependence of Seebeck coefficient alpha, electrical conductivity sigma and Hall mobility could be obtained for different sintering temperature and different dopant concentrations. It is clarified that the thermoelectric performance of sintered Mg2Si+Sb for low temperature range was determined with various kinds of scattering mechanisms different from that for single crystal or solidified thermoelectric materials. Moreover, for high temperature range the change of scattering mechanism could affect the temperature dependence of alpha based on the investigation of alpha-ln sigma and temperature dependence of Hall mobility. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 195-200 Si80Ge20溶製粉/MA粉複合焼結体の熱電特性 Thermoelectric Properties of Sintered Composites of B-doped Melt-solidified and Mechanically Alloyed Si80Ge20 Powders ○岡村寛志1)、皆川量之1)、新野真紀子1)、宮島雅史2)、渡辺龍三1)1)東北大学　工学部　980-77　仙台市2)ダイキン工業(株)　MEC研究所　305　茨城県つくば市御幸が丘 H. Okamura1), K. Minagawa1), M. Niino1), M. Miyajima2), R. Watanabe1)1) Department of Materials Processing, Faculty of Engineering, Tohoku University, Sendai 980-77, Japan 2) Daikin Industries Ltd., MEC Laboratory, 3 Miyukigakoka, Tsukuba, Ibaraki 305, Japan To obtain thermoelectric materials with high figure of merit, p-type Si80Ge20 sintered composites were prepared using two different powders. The one was prepared by melt-solidified (MS) process and the other was prepared by mechanical alloying (MA) using vibratory ball milling . The melt-solidified (MS) powder possesses high electrical conductivity and high thermal conductivity, while the mechanically alloyed powder possesses low electrical conductivity and low thermal conductivity. Also the influence of the ratio of carrier concentration, nMA/nMS on the behavior of thermoelectric properties was investigated by changing the amount of dopant B in the MA powder. The thermoelectric properties of sintered composite were measured at room temperature as a function of the volume fraction of MA powder. The maximum figure of merit, which is 13.4% higher than monolithic materials, was obtained at the composition of 40vol% MA powder with lower nMA/nMS. The electrical conductivity for lower nMA/nMS showed a percolative characteristic. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 201-207 SiGe熱電半導体と電極の接合及びその安定性評価 Thermoelectric Semiconductor and Electrode - Fabrication and Evaluation of SiGe / electrode 長谷崎　和洋1)、佃　洋1)、山田　明1)、中島　昭二2)、康　燕生3)、新野　正之3)三菱重工業(株)　長崎研究所1)、三菱重工業　(株)　長崎造船所2)、航空宇宙技術研究所　角田宇宙推進技術研究センター3) K. Hasezaki1), H. Tsukuda1), A. Yamada1) , S. Nakajima2), Y. Kang3) and M. Niino3)Nagasaki Research & Development Center1) , Mitsubishi Heavy Industries, LTD. Nagasaki Shipyard & Machinery Works2), Mitsubishi Heavy Industries, LTD. Kakuda Research Center, National Aerospace Laboratory3), Japan Joints between a Silicon-Germanium thermoelectric semiconductor and electrodes were prepared by hot-pressing. Tungsten and carbon electrodes were joined to either side of n-type Si0.8Ge0.2 (P 0.3 atomic %) respectively, with thin sheets of titanium foil inserted between them, and then pressed and joined at 1523K in vacuum. Resistance and Seebeck coefficient of the carbon / SiGe / carbon electrode were measured in the temperature range from 600 to 1100K. The resistance ranged from 0.012 to 0.015 ohms , and the Seebeck coefficient from 200x10**(-6) to 250x10**(-6)V/K. Furthermore, mechanical alloyed Si-Ge powder and tungsten electrodes were sinetered by hot-pressing at 1473K in vacuum. To evaluate the upper limit of heating dependence, the carbon / SiGe / carbon electrode was exposed in an argon atmosphere at 1273K and 1373K for 300 hours. After exposure testing, SEM observation showed the presence of many voids in the junction layer of the SiGe/carbon electrode, which had not previously shown any voids either at the stage of its joining by hot-pressing or exposed at 1273K. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 209-213 傾斜(Si-MoSi2)/SiGe熱電素子に於ける電気的、機械的特性の最適化 Optimization of Electrical and Mechanical Properties of Graded (Si-MoSi2)/SiGe Thermoelectric Conversion Unit 林君山1)、宮本欽生1)、柴田賢朗2)、広田健2)、山口修2)1)大阪大学　接合科学研究所、2)同志社大学　工学部 J. S . Lin1), Y. Miyamoto1), K. Shibata2), K. Hirota2), O. Yamaguchi2)1) JWRI, Osaka University, 2) Faculty of Engineering, Doshisya University Based on the concept of functionally graded materials, the thermoelectric conversion unit of SiGe with graded electrodes was designed and fabricated by HIP sintering process in order to obtain a good electrical and mechanical contact. The composite of Si and MoSi2 was used as the electrode, and the effect of the MoSi2 volume fraction on the electrical resistivity was studied. The results showed that the electrical resistivity decreased exponentially with increasing MoSi2 content and reached the order of 10**-4 ohm*cm when the volume fraction of MoSi2 was beyond 25%. The graded (Si-MoSi2)/SiGe obtained has dense microstructures and well bonded interfaces. The electrical resistivity decreased continuously from the SiGe to the surface electrode in the zone of graded structure. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 215-218 SiGe/Si焼結体の作製とその熱電気的特性 Preparation of SiGe/Si composite sintered alloys and their thermoelectric properties 岸本堅剛、小柳　剛山口大学　工学部　755　山口県宇部市 K. Kishimoto and T. KoyanagiFaculty of Engineering, Yamaguchi University, Ube, Yamaguchi 755, Japan SiGe raw powder was coated with Si thin layers by the SiH4-plasma treatment, and then sintered to obtain SiGe/Si composite alloys. The potential barrier scattering effect, which enhances the Seebeck coefficient, was studied for the SiGe/Si composite alloys. Numerical calculation of the Seebeck coefficient for SiGe/Si composite alloys was also made. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 219-224 Ir/W/Ta傾斜構造を有する熱電子発電器エミッタ Ir/W/Ta graded structure emitter of thermionic energy converter 加藤　昌宏　　岡本　謙一　五十嵐　廉東京タングステン株式会社　931　富山県富山市 M. Katoh K. Okamoto T. IgarashiTokyo Tungsten Co., Ltd. Toyama-shi, Toyama, 931, Japan Iridium exhibits excellent thermionic electron emission characteristics in a cesium plasma converter owing to its high work function in vacuum. The output characteristics of iridium emitters are expected to be improved, based on the calculated results of the relationship between the work function of emitter and maximum power density. The main components of the thermionic energy converter are made from tantalum. When tantalum component reacted with iridium emitter, a 2226K low-melting-point phase appeared. A three-layer structure using tungsten as an intermediate layer was selected to enhance the thermal stability of the emitter. The iridium/tungsten/tantalum graded structure emitter have been successfully produced by annealing at high temperature following hot isostatic pressing. At the iridium/tungsten and tungsten/ tantalum interfaces, graded composition layers of about 300 micro meter and about 150 micro meter thick, respectively, were formed after annealing at 2470K for 80 hours. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 225-231 補助コレクタ型熱電子発電器の試作と発電出力特性 Fabrication and Power Generation Characteristics of a Thermionic Converter with an Auxiliary Collector 福田隆三、春日康弘、加藤健、今井寛之、清水定明電子技術総合研究所　305　茨城県つくば市梅園1-1-4 R. Fukuda, Y. Kasuga, K. Kato, H. Imai, S. ShimizuElectrotechnical Laboratory, 1-1-4, Umezono, Tsukuba-City, Ibaraki 305 Japan A thermionic energy converter with an auxiliary collector was fabricated and power-generation tested experimentally in order to reduce the internal voltage loss. The converter is a plane-parallel type and the emitter is made of polycrystalline tungsten, the collector and the auxiliary collector both made of sputter-coated PtOx. When the auxiliary collector was not operated, the output power of unignited mode at TE=1800K, TR=521K, d=0.2mm, was Vout=1.0V, Jout= 0.88A/cm2. On the other hand, when the auxiliary collector was operated at the same conditions, the output power was degraded to Vout=1.0V, Jout= - 2.0A/cm2. The converter was structurally defective that the side of the main collector was exposed to the Cs plasma between the emitter and the auxiliary collector, and a lot of ion currents flew into the main collector. The improved electrode structure was devised to solve this problem. The barrier index of the W-PtOx converter was not less than 2.2V at TE=1800K, worse than a present level. But the PtOx collector was superior in supplying oxygen to the emitter, because the oxygenated bare work function of W-emitter phi o= 5.31V was obtained at TE=1800K, Tc=954K. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 233-238 高密度プラズマによる熱電子発電器電極の加熱 Electrode Heating by High Density Plasma in Thermionic Energy Converter 荻野明久1)、鄭偉2)、神藤正士1),2)1）静岡大学　大学院理工学研究科、2）静岡大学　大学院電子科学研究科 Akihisa Ogino1) , Zheng Wei2) , Masashi Kando1),2)1) Graduate School of Science and Engineering , Shizuoka University 2) Graduate School of Electronic Science and Technology , Shizuoka University To evaluate electrode heating of thermionic energy converter by high density plasma produced by external source, one-dimensional PIC(Particle-In-Cell) simulation was used to analyze plasma characteristics between parallel flat electrodes. Plasma initially confined between electrodes with quantitative balance condition of electrons and ions was considered. The plasma was assumed that electron and ion collisions with other neutrals were dominant. The particles are modeled as 4,000 sheets which move in one direction (along x) under a self-consistent time-varying field. In a very short timescale, fast-moving electrons are not confined and lost to the wall. As the result, positive ion sheaths are formed near the walls where ni >> ne. Therefore, ion bombardment can heat the electrode. Electrode temperature can be calculated by using the results of PIC simulation and equations of heat conduction in equilibrium. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 239-246 傾斜機能材料を用いた熱電子発電素子の設計試作 Development of Thermionic Energy Converter with FGM 加藤寿仁、新井敬、礒貝和博三井造船(株)　千葉県市原市 T.Kato, T.Arai, K.IsogaiMitsui Engineering & Shipbuilding Co. Ltd., Ichihara-City, Chiba Pref., Japan Thermionic energy conversion is an attractive method for generating electricity by high temperature heat source such as concentrated solar light. In order to improve high temperature endurance capability, a thermionic energy converter has been developed by applying functionally graded material to the plane-electrodes; an iridium (Ir) emitter electrode having a diameter of 2cm and a niobium-oxide (NbOx) collector. Both electrodes were connected by several thin components, called heat-choke, which were designed to reduce the thermal conduction and serve as part of the converter envelope. To date, the thermionic energy converter was successfully fabricated. The designed performance of the converter is the output power density of 8W/cm2 and the energy conversion efficiency of 15% at the emitter temperature of about 1800K. Japanese １９９７年度　傾斜機能材料論文集　＜ＦＧＭ’９７＞ FY 1997 Proceedings of Functionally Gradient Materials 12 1998-05-01 247-252 レーザMBE法による強誘電体/強磁性体傾斜機能材料の形成とその物性 Formation of Ferroelectric/Ferromagnetic Functionally Grated Materials by Laser MBE and Their Physical Properties 田畑　仁、田中秀和、植田研二、川合知二大阪大学　産業科学研究所 H.Tabata, H.Tanaka, K.Ueda and T.KawaiInstitute of Scientific and Industrial Research , Osaka University Artificial functionally graded materials (FGMs) of ferroelectric/ferromagnetics have been constructed by a laser MBE. The stacking periodicity can be controlled from 1-unit cell to several hundreds unit cells. By controlling the stacking periodicity, the dimensionally and induced lattice stress can be controlled. In the case of (La,Sr)MnO3/BaTiO3 FGMs, magnetic layer is expanded owing to the lattice mismatch of 2.8%. In thins case lattice stress of 1 GPa is introduced at the interface. Curie temperature decreases with decreasing the stacking periodicity below around 10 unit cells. It depends on the short rage correlation. Japanese