# Fileset [multiscale-multifunc-fgm-3-264.xlsx](https://mdr.nims.go.jp/filesets/7aa66d01-9596-4cbb-9621-094e681270c8/download) ## Creator National Institute for Materials Science ## Rights ## Other metadata [Multiscale, Multifunctional and Functionally Graded Materials (pp.3-264)](https://mdr.nims.go.jp/datasets/99cf2073-85a4-45ce-a974-fdcf6644152a) ## Fulltext Sheet1 BookTitle_j BookTitle_e Volume/Issue Issueddate Page Title_j Title_e AuthorList_j AuthorList_e Abstract Language Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 3-8 Overview of Studies on Space Solar Power Systems and Elemental Technology Development Overview of Studies on Space Solar Power Systems and Elemental Technology Development Hiroaki Suzuki 1),a, Katsuto Kisara 2),b, Masayuki Niino 2),c and Masahiro Mori 1),d1)Japan Aerospace Exploration Agency, Chofu Aerospace Center,7-44-1 Jindaiji Higashimachi, Chofu, Tokyo 182-8522, Japan2)Japan Aerospace Exploration Agency, Kakuda Space Center, 1 Koganezawa, Kimigaya, Kakuda, Miyagi 981-1525, Japan Hiroaki Suzuki 1),a, Katsuto Kisara 2),b, Masayuki Niino 2),c and Masahiro Mori 1),d1)Japan Aerospace Exploration Agency, Chofu Aerospace Center,7-44-1 Jindaiji Higashimachi, Chofu, Tokyo 182-8522, Japan2)Japan Aerospace Exploration Agency, Kakuda Space Center, 1 Koganezawa, Kimigaya, Kakuda, Miyagi 981-1525, Japan Japan Aerospace Exploration Agency (JAXA) has studied Space Solar Power Systems (SSPS) using laser and microwave beams for years since 1998. Current SSPS study undertaken by JAXA consists of three main subjects, SSPS concepts and architectures study, technology demonstration and elemental technology development. In current research of Laser based SSPS (L-SSPS), we have studied some elemental technologies such as ultralight film mirror, wavelength selective mirror, laser generator based on direct solar pumping solid-state laser diode, laser transmission property in atmosphere, photovoltaic generation converting laser energy to electricity and photocatalytic hydrogen generation. This paper presents the introduction of SSPS concepts and architectures study and elemental technology development of L-SSPS.Keywords: M-SSPS, L-SSPS, Direct solar pumping solid-state laser, Laser transmission property in atmosphere, Photocatalytic hydrogen generation with laser English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 9-14 Prospect of YAG Laser Medium for Laser Space Solar Power System and Possible Application of Graded Structure for Efficient Cooling System Prospect of YAG Laser Medium for Laser Space Solar Power System and Possible Application of Graded Structure for Efficient Cooling System Yoshikazu Shinohara 1),a, Katsuto Kisara 2),b and Hiroaki Suzuki 3),c1)National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan2,3)Kakuda Space Center, Japan Aerospace Exploration Agency, 1 Koganezawa, Kimigaya, Kakuda, Miyagi 981-1525, Japan Yoshikazu Shinohara 1),a, Katsuto Kisara 2),b and Hiroaki Suzuki 3),c1)National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan2,3)Kakuda Space Center, Japan Aerospace Exploration Agency, 1 Koganezawa, Kimigaya, Kakuda, Miyagi 981-1525, Japan Laser medium for solar-pumped solid laser of 10MW-1GW power is a key to realize Laser Space Solar Power System (L-SSPS). Since it is an ultrahigh power system operated in space, the laser medium must satisfy the conditions such as high efficiency, high power per weight or volume, excellent durability and maintainability, thermal equilibrium operation, and excellent long-range propagation of oscillated laser. YAG (Y₃Al₅O₁₂) ceramics doped doubly with Nd and Cr is considered to be a suitable laser medium for L-SSPS at present. There are the following important points for L-SSPS application: 1) Optimization of the doping amount, 2) Process, 3) Temperature control. Feasibility of YAG ceramics is discussed from a view point of material science and proposed a YAG ceramics structure with graded distribution of dopants.Keywords: List the keywords covered in your paper. These keywords will also be used by the publisher to produce a keyword index. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 17-22 Dynamic, Modal and Wave Propagation Analyses of 3D Functionally Graded Continua Dynamic, Modal and Wave Propagation Analyses of 3D Functionally Graded Continua Ganesh Anandakumar a and Jeong-Ho Kim bDepartment of Civil & Environmental Engineering, University of Connecticut,261 Glenbrook Rd, U-2037, Storrs, CT 06269, USA Ganesh Anandakumar a and Jeong-Ho Kim bDepartment of Civil & Environmental Engineering, University of Connecticut,261 Glenbrook Rd, U-2037, Storrs, CT 06269, USA Transient dynamic behavior of a three-dimensional (3D) homogeneous cantilever beam under sinusoidal loading at the free end is verified using the finite element method (FEM). Explicit central difference technique is used for the time integration of finite elements. The tip displacement and maximum stress at the fixed end obtained using the FEM agree well with exact solutions. Modal analysis of a functionally graded (FG) 3D cantilever beam is investigated using Rayleigh-Ritz (RR) method and the FEM. The natural frequencies obtained using the RR method converges as the number of terms in the assumed base function increases. The natural frequencies vary considerably with the gradation of the beam, more for lower modes than for higher modes. Wave propagation in a fixed-free 3D bar is studied using the FEM. Axial stress results for the homogeneous bar with zero Poisson’s ratio agree closely with 1D exact solution. For the FG bar, we see that gradation affects stresses considerably more so at the fixed end than at other locations.Keywords: Functionally graded materials, Finite element methods, Dynamic analysis, Modal analysis, Rayleigh Ritz method, Wave propagation. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 23-28 Thermal Stress Analysis of an FGM Cylinder Under the Effect of Convection and Radially Varying Temperature Distribution Thermal Stress Analysis of an FGM Cylinder Under the Effect of Convection and Radially Varying Temperature Distribution Serra Topal 1), a, Mufit Gulgec 1), b1) Gazi University Department of Mechanical Engineering, Maltepe 06570 Ankara TURKEY Serra Topal 1), a, Mufit Gulgec 1), b1) Gazi University Department of Mechanical Engineering, Maltepe 06570 Ankara TURKEY The plane strain problem for a functionally graded solid cylinder with thermal energy generation under the effect of convective heat transfer is considered. In previous studies on FGM cylinders in the literature, the modulus of elasticity, the thermal conductivity and the thermal expansion coefficient are represented by using either exponential or power functions. However, this study considers different functions for these material properties, which results in a more realistic representation of the problem. The stress and strain components are evaluated analytically and their dependencies on the radially varying material parameters are presented at the elastic state. Critical values of the volumetric thermal energy generation evaluated for a homogeneous solid cylinder and for an FGM cylinder are compared by using the Tresca’s Yield Criterion. Numerical results are generated by considering a W/Cu FGM solid cylinder which has potential applications as an International Thermonuclear Experimental Reactor (ITER) component.Keywords: Functionally graded materials (FGMs), solid cylinder, stress-strain analysis, Tresca’s yield criterion, thermal energy generation. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 29-34 Approach to Optimum Layer Structure of Functionally Graded Materials Approach to Optimum Layer Structure of Functionally Graded Materials Kazuhiro Hasezaki and Yasutoshi NodaDepartment of Materials Science, Shimane University, Matsue 690-8504, Japan Kazuhiro Hasezaki and Yasutoshi NodaDepartment of Materials Science, Shimane University, Matsue 690-8504, Japan Minimum interlayer numbers of functionally graded materials (FGMs) are studied based on the empirical analysis of thermal stress due to the differences in the thermal expansion coefficient Da and temperature DT between sintering and room temperatures. It is found the maximum Da, DT, DaDT and the minimum interlayer number necessary to produce a NiCr / Fly ash FGM structure without interface cracking were 4.0×10^-6 K^-1, 1080 K, 0.043 and 2, respectively. The conditionDaDT < 0.043 was derived and confirmed to be valid for available FGM systems.Keywords: functionally graded material, thermal expansion coefficient, thermal stress, spark plasma sintering English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 35-40 Computational Evaluation of Effective Conductivity of ParticulateComposites with Imperfect Interfaces Computational Evaluation of Effective Conductivity of ParticulateComposites with Imperfect Interfaces M. Zhang* 1), a, P. C. Zhai 2), b, Q. J. Zhang 3), c1)School of Science, Wuhan University of Technology, Wuhan 430070, China2), 3)State Key Laboratory of Advanced Technology for Material Synthesis and Processing,Wuhan University of Technology, 122 Luoshi Road, CN430070 Wuhan, China M. Zhang* 1), a, P. C. Zhai 2), b, Q. J. Zhang 3), c1)School of Science, Wuhan University of Technology, Wuhan 430070, China2), 3)State Key Laboratory of Advanced Technology for Material Synthesis and Processing,Wuhan University of Technology, 122 Luoshi Road, CN430070 Wuhan, China This paper is aimed to numerically evaluate the effective thermal conductivity of randomly distributed spherical particle composite with imperfect interface between the constituents. A numerical homogenization technique based on the finite element method (FEM) with representative volume element (RVE) was used to evaluate the effective properties with periodic boundary conditions. Modified random sequential adsorption algorithm (RSA) is applied to generate the three dimensional RVE models of randomly distributed spheres of identical size with the volume fractions up to 50%. Several investigations have been conducted to estimate the influence of the imperfect interfaces on the effective conductivity of particulate composite. Numerical results reveal that for the given composite, due to the existence of an interfacial thermal barrier resistance, the effective thermal conductivity depends not only on the volume fractions of the particle but on the particle size.Keywords: Finite element method, Effective thermal conductivity, Imperfect interface English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 41-46 Hypersonic flutter analysis of functionally graded panels under thermal and aerodynamic loads Hypersonic flutter analysis of functionally graded panels under thermal and aerodynamic loads Kim, Sun-Bae 1),a and Kim, Ji-Hwan 2),b1)School of Mechanical and Aerospace Engineering, Seoul National University San 56-1, Sillim-dong, Gwanak-Gu, Seoul 151-742, Korea2)Institute of Advanced Aerospace Technology, School of Mechanical and Aerospace Engineering,Seoul National University, San 56-1, Sillim-dong, Gwanak-Gu, Seoul 151-742, Korea Kim, Sun-Bae 1),a and Kim, Ji-Hwan 2),b1)School of Mechanical and Aerospace Engineering, Seoul National University San 56-1, Sillim-dong, Gwanak-Gu, Seoul 151-742, Korea2)Institute of Advanced Aerospace Technology, School of Mechanical and Aerospace Engineering,Seoul National University, San 56-1, Sillim-dong, Gwanak-Gu, Seoul 151-742, Korea In this work, hypersonic aero-thermo post-buckling and thermal flutter behaviors of Functionally Graded (FG) panels under thermal and aerodynamic loads are investigated. The volume fractions of constitutive materials of the panels are gradually varied from ceramic to metal in the thickness direction based on a simple power law distribution. Thus, the material properties of the panel are also changed by a linear rule of mixture. Furthermore, the material properties are assumed to be temperature dependent because the panels are mainly used in the high temperature environments. Using the principle of virtual work, the equations of motion of the first-order shear deformation plate theory (FSDPT) are derived and the finite element method is applied to get the solution. In the formulation, the von Karman strain-displacement relationship is used for structural nonlinearity, and the partial second-order piston theory is adopted to consider the aerodynamic nonlinearity. Newton-Raphson iterative technique is used to solve the governing equations, and linear eigenvalue analysis is performed to obtain the hypersonic flutter boundaries.Keywords: Functionally Graded Materials (FGMs), Flutter and Hypersonic Airflows English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 47-52 Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded Viscoelastic Model, Part-I: Development, Implementation and Verification Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded Viscoelastic Model, Part-I: Development, Implementation and Verification Eshan V. Dave 1),a, Glaucio H. Paulino 1),b and William G. Buttlar 1),c1) Department of Civil and Environmental Engineering, University of Illinois,205 N. Mathews Avenue, Urbana, IL 61801, United States Eshan V. Dave 1),a, Glaucio H. Paulino 1),b and William G. Buttlar 1),c1) Department of Civil and Environmental Engineering, University of Illinois,205 N. Mathews Avenue, Urbana, IL 61801, United States Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions are the major cause of such graded non-homogeneity. Current pavement analysis and simulation procedures either ignore or use a layered approach to account for non-homogeneities. For instance, the recently developed Mechanistic-Empirical Design Guide (MEPDG) [1], which was recently approved by the American Association of State Highway and Transportation Officials (AASHTO), employs a layered analysis approach to simulate the effects of material aging gradients through the depth of the pavement as a function of pavement age. In the current work, a graded viscoelastic model has been implemented within a numerical framework for the simulation of asphalt pavement responses under various loading conditions. A functionally graded generalized Maxwell model has been used in the development of a constitutive model for asphalt concrete to account for aging and temperature induced property gradients. The associated finite element implementation of the constitutive model incorporates the generalized iso-parametric formulation (GIF) proposed by Kim and Paulino [2], which leads to the graded viscoelastic elements proposed in this work. A solution, based on the correspondence principle, has been implemented in conjunction with the collocation method, which leads to an efficient inverse numerical transform procedure. This work is the first of a two-part paper and focuses on the development, implementation and verification of the aforementioned analysis approach for functionally graded viscoelastic systems. The follow-up paper focuses on the application of this approach.Keywords: viscoelasticity, functionally graded materials, numerical simulations, correspondence principle, finite-element method English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 53-58 Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded Viscoelastic Model, Part-II: Applications Asphalt Pavement Aging and Temperature Dependent Properties through a Functionally Graded Viscoelastic Model, Part-II: Applications Eshan V. Dave 1),a, William G. Buttlar 1),b, and Glaucio H. Paulino 1),c1) Department of Civil and Environmental Engineering, University of Illinois, 205 N. Mathews Avenue, Urbana, IL 61801, United States Eshan V. Dave 1),a, William G. Buttlar 1),b, and Glaucio H. Paulino 1),c1) Department of Civil and Environmental Engineering, University of Illinois, 205 N. Mathews Avenue, Urbana, IL 61801, United States This is the second article in a series of two papers describing simulation of functionally graded viscoelastic properties in asphalt concrete pavements. The techniques developed are applicable to other viscoelastic material systems with continuous, spatial grading of material properties. A full-depth asphalt concrete pavement has been simulated to demonstrate the applicability and importance of the graded viscoelastic analysis method. Based on the graded finite elements developed by Kim and Paulino[1], Buttlar et al. [2] used graded finite elements to determine typical responses to tire loading for an aged asphalt concrete pavement. In the current study, a similar pavement section is studied using the viscoelastic graded analysis (rather than elastic). Graded, layered and homogeneous material variations were used for a series of simulations, and the results from different approaches were compared.Keywords: viscoelasticity, functionally graded materials, numerical simulations, correspondence principle, finite-element method English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 59-64 Thermodynamics of FGM: new approach for free energy and the equilibrium state calculations Thermodynamics of FGM: new approach for free energy and the equilibrium state calculations Michael Gasik 1), a, Yevgen Bilotsky 1),b, Bohdan Lev 2),c1) Helsinki University of Technology ? TKK, P.O. Box 6200, FIN-02015 TKK, Espoo, Finland2) Department of Synergetic, Bogolyubov Institute of Theoretical Physics, NAS Ukraine, Metrolohichna 14-b, UKR-03143 Kyiv, Ukraine Michael Gasik 1), a, Yevgen Bilotsky 1),b, Bohdan Lev 2),c1) Helsinki University of Technology ? TKK, P.O. Box 6200, FIN-02015 TKK, Espoo, Finland2) Department of Synergetic, Bogolyubov Institute of Theoretical Physics, NAS Ukraine, Metrolohichna 14-b, UKR-03143 Kyiv, Ukraine FGM thermodynamics has been mostly based on adaptation of classical Gibbs-Helmholtz approach for infinite systems to locally “homogeneous” zones. A statistical sum calculation in this theory cannot predict inhomogeneous distributions. A new approach to the statistical description of solid solutions is suggested, which takes into account possible formation of spatially inhomogeneous simultaneous particle and field distributions in finite space domains. The formation of new periodical or gradated structure in binary system is described. The effective free energy of system was determined and the condition of formation of such spatially inhomogeneous distribution of interacting particles was obtained. New method may be applied to FGM to calculate ab initio free energy of these systems without usual limitations of classical theory.Keywords: FGM, statistics, inhomogeneous distribution, binary solutions, finite volume systems. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 65-70 Mixture screening design to choose formulations for functionally graded fiber cements Mixture screening design to choose formulations for functionally graded fiber cements C.M.R. Dias 1), a, H. Savastano Jr 2),b , M. E. S. Taqueda 3),c, V.M. John 4),d1),4 Dep. de Const. Civil, Escola Politecinica, Universidade de Sao Paulo (USP), Av. Prof. Almeida Prado, trav. 2, n.83 - Edif. de Eng. Civil - Cid. Universitaria, 05508 900, Sao Paulo-SP, Brazil2) Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de Sao Paulo (USP), Avenida Duque de Caxias Norte, 225, 13635-900 Pirassununga, Sao Paulo, Brazil.3) Dep. de Quimica, Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 580, Bl. 13, Conjunto das Quimicas, Cidade Universitaria, 05508-900, Sao Paulo, Brazil. C.M.R. Dias 1), a, H. Savastano Jr 2),b , M. E. S. Taqueda 3),c, V.M. John 4),d1),4 Dep. de Const. Civil, Escola Politecinica, Universidade de Sao Paulo (USP), Av. Prof. Almeida Prado, trav. 2, n.83 - Edif. de Eng. Civil - Cid. Universitaria, 05508 900, Sao Paulo-SP, Brazil2) Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de Sao Paulo (USP), Avenida Duque de Caxias Norte, 225, 13635-900 Pirassununga, Sao Paulo, Brazil.3) Dep. de Quimica, Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 580, Bl. 13, Conjunto das Quimicas, Cidade Universitaria, 05508-900, Sao Paulo, Brazil. This work employing the screening strategy to examine thirteen mix proportions of sixcomponent fiber cement formulations composed of ordinary Portland cement, ultra-fine cement, limestone filler, silica fume, cellulose and polyvinyl alcohol fibers. The vacuum de-watering technique was applied in the production of fiber cement specimens cured for 10 days and submitted to four-point bending tests. The mechanical properties such as limit of proportionality (LOP), modulus of elasticity (MOE), modulus of rupture (MOR) and specific energy (SE) were evaluated and these properties were correlated with the raw material fractions resulting in mixture rules. Results indicate that screening can be a promising methodology with which to generate coherent fiber cement mixture rules, optimize formulations in terms of costs and performance and even facilitate the choosing of formulations for functionally graded fiber cements.Keywords: mixture design, screening, functionally graded fiber cement, mechanical properties, and simultaneous optimization. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 73-78 Functionally Graded Thermal Barrier Coatings with Improved Reflectivity and High-Temperature Capability Functionally Graded Thermal Barrier Coatings with Improved Reflectivity and High-Temperature Capability Robert Vassen 1),a, Holger Kassner 1),b, Alexandra Stuke 1),c, Daniel Emil Mack 1),dMaria Ophelia Jarligo 1),e and Detlev Stover 1),f1) Institute of Energy Research, Forschungszentrum Julich GmbH, 52428 Julich, Germany Robert Vassen 1),a, Holger Kassner 1),b, Alexandra Stuke 1),c, Daniel Emil Mack 1),dMaria Ophelia Jarligo 1),e and Detlev Stover 1),f1) Institute of Energy Research, Forschungszentrum Julich GmbH, 52428 Julich, Germany Conventional thermal barrier coating (TBC) systems consist of a duplex structure with a metallic bondcoat and a ceramic, heat isolative topcoat. In modern TBCs the ceramic topcoat is further divided into layers with different functions. One example is the double layer system in which conventional yttria stabilized zirconia (YSZ) is used as bottom and new materials as pyrochlores or perovskites are used as topcoat layers. These systems demonstrated an improved temperature capability compared to standard YSZ. Examples of such systems will be shown. In modern gas turbines the increased temperatures and gas pressures lead to an increased fraction of radiative heat flow. Coatings with increased reflectivity can be used to avoid the direct heating of the metallic substrates by this radiation. An effective method to produce such coatings is suspensionplasma spraying. These reflective coatings are deposited on top of the TBC system and will lead to a further grading and improved performance of the coating.Keywords: Thermal barrier coating, gas turbines, ceramic top coats, plasma spraying, reflective coatings English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 79-84 Analysis and Simulation of FGM Thermal Barrier Coatings Hot Burner Testing Analysis and Simulation of FGM Thermal Barrier Coatings Hot Burner Testing Michael Gasik 1),a, Akira Kawasaki 2), b1) Helsinki University of Technology - TKK, FIN-02015 Espoo, Finland2) Tohoku University, 981 Sendai, Japan Michael Gasik 1),a, Akira Kawasaki 2), b1) Helsinki University of Technology - TKK, FIN-02015 Espoo, Finland2) Tohoku University, 981 Sendai, Japan For FGM thermal barrier coatings thermal-mechanical fatigue due to temperature cycling is one of the critical parameters which determine the lifetime of the TBC. In Tohoku University, a method known as “hot burner test” has been developed and was implemented into the standard JIS H 7851. For further optimization of the testing conditions and selection of the parameters for comparison of different test results knowledge of temperature and heat flux inside the test jig is necessary. FEM analysis of the heat flux and temperature inside the 14 mm diameter test stainless steel jig has been performed. Homogenous YSZ top coat with NiCrAlY bondcoat as well as FGM TBC with different gradation profiles were compared. Distributions of the temperature and heat flux are critical at the edges of the test piece and thermocouples locations, which must be taken into account when comparing test data for coatings with rather different composition and structure. The largest stress gradients develop at the ceramic-metal interface (duplex) and near the edges of the TBC.Keywords: Coatings, Hot Burner Test, Superalloys, Zirconia, Residual Stresses, Simulation English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 85-90 Thermomechanical Evaluation and Thermal Expansion Behavior of Plasma-sprayed Thermal Barrier Coatings Thermomechanical Evaluation and Thermal Expansion Behavior of Plasma-sprayed Thermal Barrier Coatings Kenta Takagi 1),a, Akira Kawasaki 1),b, Yoshio Harada 2),cand Masakazu Okazaki 3),d1) Department of Materials Processing, Tohoku University, 6-6-02, Aramaki, Aoba, Aoba-ku, Sendai, 980-8579, Japan2) Tocalo Co., Ltd., Akashi Hyogo, Japan3) Departement of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka, Nagaoka, 940-2188, Japan Kenta Takagi 1),a, Akira Kawasaki 1),b, Yoshio Harada 2),cand Masakazu Okazaki 3),d1) Department of Materials Processing, Tohoku University, 6-6-02, Aramaki, Aoba, Aoba-ku, Sendai, 980-8579, Japan2) Tocalo Co., Ltd., Akashi Hyogo, Japan3) Departement of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka, Nagaoka, 940-2188, Japan We are investigating the feasibility of measuring thermal expansion coefficient (CTE) of free-standing thermal barrier coatings with a practical thickness of several hundred micrometers by mean of a widespread thermomechanical analysis toward its industrial standardization. First of all, this study conducted the preliminary investigation for the accurate measurement of thin samples with dense yettria-stabilized zirconia (YSZ) ceramics. With a sample supporting jig and proper conditions, even the usual thermomechanical analysis could give the accurate CTE values of thin samples down to 0.3mm thick. Also it showed good reproducibility with small measurement error less than 5%. In actual, this modified method could provide the reasonable CTE values of plasma-sprayed YSZ samples with thickness of >0.3mm. Further investigation with this method found a slight monotonic decrease in the CTE with annealing. This decrease was estimated to arise from the continuous change of microstructure which still went on even after saturation of sintering shrinkage. All the results demonstrated the present method to be available for the industrial standard.Keywords: Thin zirconia ceramics, Coefficient of thermal expansion, Sintering, Industrial standardization. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 91-96 Thermal Fatigue Damage Evaluation of EB-PVD TBC Specimens -Its Potential and Problems-. Thermal Fatigue Damage Evaluation of EB-PVD TBC Specimens -Its Potential and Problems-. M. OKAZAKI 1),a, S. YAMAGISHI 1) , M. SAKAGUCHI 1) and T. OKAMURA 1)1) Nagaoka University of Technology, Tomioka, Nagaoka, JAPAN M. OKAZAKI 1),a, S. YAMAGISHI 1) , M. SAKAGUCHI 1) and T. OKAMURA 1)1) Nagaoka University of Technology, Tomioka, Nagaoka, JAPAN Thermal fatigue damage evolution behavior in thermal barrier coatings (TBCs) was studied, by employing the originally designed two dimensional ring-shape TBC specimen. The TBC specimen consisted of Ni-based superalloy IN738LC substrate, bond coat, and 8 wt.% Y₂O₃-stabilized ZrO₂ (YSZ) top coat. The top coat was fabricated by electron-beam physical vapor deposition (EB-PVD) method with 250 micron-meters in thickness. Three kinds of MCrAlY bond coat alloys were specified as an experimental variable. Through the work, special attention was paid not only to the failure life of TBC specimen, but also to the underlying failure mechanisms. Some problems have been also pointed out, on feeding back these experimental findings to engineering applications.Keywords: Thermal barrier coatings, EB-PVD, Bond coat , Thermal fatigue, Spalling, Thermally grown oxide. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 97-102 Development of Novel Functionally Graded Al₂O₃-Lanthanum Hexaaluminate Ceramics for Thermal Barrier Coatings Development of Novel Functionally Graded Al₂O₃-Lanthanum Hexaaluminate Ceramics for Thermal Barrier Coatings Zahra Negahdari 1),a, Monika Willert-Porada 1),b, Florian Scherm 2),c1) Chair of Materials Processing, Faculty of Applied Science, University of Bayreuth, D-95447 Bayreuth, Germany2) Chair of Metals and Alloys, Faculty of Applied Science, University of Bayreuth, D-95447 Bayreuth, German Zahra Negahdari 1),a, Monika Willert-Porada 1),b, Florian Scherm 2),c1) Chair of Materials Processing, Faculty of Applied Science, University of Bayreuth, D-95447 Bayreuth, Germany2) Chair of Metals and Alloys, Faculty of Applied Science, University of Bayreuth, D-95447 Bayreuth, German Lanthanum hexaaluminate (LHA) has superior thermo-chemical stability at temperatures higher than 1000 °C and is a promising competitor to Y-ZrO₂-based thermal barrier coatings (TBCs). The yet unresolved problem is control of microstructure of high LHA content ceramics and adjustment of porosity upon, to arrive at a material exhibiting low thermal conductivity at high temperature combined with structural reliability. Therefore, a functionally graded alumina/lanthanum hexaaluminate (FGLHA) with a gradient in composition was developed. The thermal diffusivity and thermal conductivity of FGLHA were compared with the one of the monolithic composite ceramics. The alumina-rich composites showed excellent mechanical properties whereas the LHA-rich composites presented lower thermal conductivity.Keywords: Lanthanum hexaaluminate, functionally graded materials, Thermal properties, Thermal barrier coatings English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 103-108 Thermal Diffusivity Measurements of the Layered Materials by the Laser Flash Method Thermal Diffusivity Measurements of the Layered Materials by the Laser Flash Method Megumi Akoshima 1), a, Tetsuya Baba 1), b, Mitsue Ogawa 2), Takashi Tanaka 3),Yoshio Harada 4), Akira Kawasaki 5) and Fumio Ono 6)1) National Metrology Institute of Japan (NMIJ), AIST, Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563 Japan2) Japan Fine Ceramics Center (JFCC), 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 465-8587, Japan3) Sumitomo Metal Technology Inc., 1-8 Fuso-cho, Amagasaki, Hyogo 660-0891, Japan4) TOCALO Co. Ltd., 1-8 Fuso-cho, Amagasaki, Hyogo 660-0891, Japan5) Graduate School of Engineering, Tohoku Univ., 6-6-02 Aramaki-aza Aoba, Aobaku, Sendai, Miyagi 980-8579, Japan6) Osaka Science & Technology Center, 1-8-4 Utsubohonmachi, Nishi-ku, Osaka 550-0004, Japan Megumi Akoshima 1), a, Tetsuya Baba 1), b, Mitsue Ogawa 2), Takashi Tanaka 3),Yoshio Harada 4), Akira Kawasaki 5) and Fumio Ono 6)1) National Metrology Institute of Japan (NMIJ), AIST, Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563 Japan2) Japan Fine Ceramics Center (JFCC), 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 465-8587, Japan3) Sumitomo Metal Technology Inc., 1-8 Fuso-cho, Amagasaki, Hyogo 660-0891, Japan4) TOCALO Co. Ltd., 1-8 Fuso-cho, Amagasaki, Hyogo 660-0891, Japan5) Graduate School of Engineering, Tohoku Univ., 6-6-02 Aramaki-aza Aoba, Aobaku, Sendai, Miyagi 980-8579, Japan6) Osaka Science & Technology Center, 1-8-4 Utsubohonmachi, Nishi-ku, Osaka 550-0004, Japan Ceramics-based thermal barrier coatings are used as heat and wear shields of blades of gas turbine. There are strong needs to evaluate thermophysical properties of coatings, such as thermal conductivity, thermal diffusivity and heat capacity of them. Since coatings are attached on substrates, it is not easy to measure these properties separately. In order to evaluate the thermal diffusivity of coating attached on substrate, we have tried to apply the multi-layer model based on the response function method and established a procedure for the measurement by the laser flash method. We verified the procedure by the measurements from room temperature to about 1000 K for two-layer ceramics sample prepared by the doctor blade tape casting method. The thermally sprayed CoNiCrAlY coating on the SUS304 substrate was also used for verification. The thermal diffusivity of coating attached on substrate approximately agreed with that of the single-layer coating removed from substrate. In the case of the ceramics sample, the thermal diffusivity of the coating including the interfacial thermal resistance determined within about 20 % uncertainty. We compared the laser flash measurement signals of the samples prepared by the thermal spraying with variant thickness and found the difference among them. It was found that the procedure has enough resolution to detect the heat shield effect caused by the change with about 200 μm in thickness. The result shows that the procedure and analysis were practically effective for the thermal diffusivity estimation of coating attached on the substrate without remove from substrate.Keywords: Thermal Diffusivity, Laser Flash Method, Layered Material, Thermal Barrier Coating English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 109-114 Three Dimensional Modeling of Inclined Surface Cracks in FGM Coatings Three Dimensional Modeling of Inclined Surface Cracks in FGM Coatings S. Kosker 1),a, S. Dag 1),b and B. Yildirim 2),c1) Department of Mechanical Engineering, Middle East Technical University, Ankara 06531, Turkey2) Department of Mechanical Engineering, Hacettepe University, Ankara 06800, Turkey S. Kosker 1),a, S. Dag 1),b and B. Yildirim 2),c1) Department of Mechanical Engineering, Middle East Technical University, Ankara 06531, Turkey2) Department of Mechanical Engineering, Hacettepe University, Ankara 06800, Turkey This study presents a three dimensional finite element method for mixed-mode fracture analysis of an FGM coating-bond coat-substrate structure. The FGM coating is assumed to contain an inclined semi-elliptical crack at the free surface. The trilayer structure is examined under the effect of transient thermal stresses. Strain singularity around the crack front is simulated by utilizing collapsed wedge-shaped singular elements. The modes I, II and III stress intensity factors are computed by applying the displacement correlation technique and presented as a function of time. Four different FGM coating types are examined in the parametric analyses which are metal-rich, ceramic-rich, linear variation and homogeneous coatings. The results provided illustrate the influences of the FGM coating type and crack inclination angle on the transient behavior of the mixed-mode stress intensity factors.Keywords: Functionally Graded Materials (FGMs); Semi-Elliptical Surface Crack; Finite Element Method; Displacement Correlation Technique; Thermal Stresses. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 115-120 Analytical Solution of a Crack Problem in a Radially Graded FGM Analytical Solution of a Crack Problem in a Radially Graded FGM Suat Cetin 1), a, Suat Kad?o?lu 1),b1) Middle East Technical University, 06531, Ankara, Turkey Suat Cetin 1), a, Suat Kad?o?lu 1),b1) Middle East Technical University, 06531, Ankara, Turkey The objective of this study is to determine stress intensity factors (SIFs) for a crack in a functionally graded layer bonded to a homogeneous substrate. Functionally graded coating contains an edge crack perpendicular to the interface. It is assumed that plane strain conditions prevail and the crack is subjected to mode I loading. By introducing an elastic foundation underneath the homogeneous layer, the plane strain problem under consideration is used as an approximate model for an FGM coating with radial grading on a thin walled cylinder. The plane elasticity problem is reduced to the solution of a singular integral equation. Constant strain loading is considered. Stress intensity factors are obtained as a function of crack length, strip thicknesses, foundation modulus, and inhomogeneity parameter.Keywords: Functionally Graded Material (FGM), Stress Intensity Factor, Crack Problem, Elastic Foundation. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 121-126 Numerical Simulation of Mixed-mode Crack Propagation in Functionally Graded Materials Numerical Simulation of Mixed-mode Crack Propagation in Functionally Graded Materials Li MA, Zhi-Yong WANG and Lin-Zhi WUCenter for Composite Materials, Harbin Institute of Technology, Harbin 150001, P.R.China Li MA, Zhi-Yong WANG and Lin-Zhi WUCenter for Composite Materials, Harbin Institute of Technology, Harbin 150001, P.R.China This paper addresses the numerical simulation of mixed-mode crack propagation in Functionally Graded Materials (FGMs) by means of eXtended Finite Element Method (XFEM), endowed with elastic and toughness properties which gradually vary in space. The method allows to follow crack paths independently of the finite element mesh, this feature is especially important for FGMs, since the gradation of the mechanical properties may lead to complex propagation paths also in simple symmetric tests. Each step of crack growth simulation consists of the calculation of the mixed-mode stress intensity factor by means of a non-equilibrium formulation of the interaction integral method, determination of the crack growth direction based on a specific fracture criterion. A specific fracture criterion is tailored for FGMs based on the assumption of local homogenization of asymptotic crack-tip fields in FGMs. The present approach uses a user-defined crack increment at the beginning of the simulation. Crack trajectories obtained by the present numerical simulation agree well with available experimental results for FGMs. The computational scheme developed here serve as a guideline for fracture experiments on FGM specimens (e.g. initiation toughness and R-curve behavior).Keywords: Functionally Graded Materials (FGMs); eXtended Finite Element Method (XFEM); Mixed-mode Crack; stress intensity factor English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 127-134 The Effective Conductivity of Multiphase Composites with Imperfect Thermal Contact at Constituent Interfaces The Effective Conductivity of Multiphase Composites with Imperfect Thermal Contact at Constituent Interfaces M. Zhang* 1), a, P. C. Zhai 2), b and Q. J. Zhang 3), c1) School of Science, Wuhan University of Technology, Wuhan 430070, China2), 3) State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, CN430070 Wuhan, China M. Zhang* 1), a, P. C. Zhai 2), b and Q. J. Zhang 3), c1) School of Science, Wuhan University of Technology, Wuhan 430070, China2), 3) State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, CN430070 Wuhan, China This paper studies the effective thermal conductivity of multiphase composite in which a thermal boundary resistance exists at constituent interfaces. Based on the theoretical framework of conductivity for binary system composites in the presence of a thermal contact resistance between matrix and inclusion given by Y. Benveniste and T. Miloh (1986), the fundamental concept is generalized for the case of multiphase composites with imperfect contact which permits a temperature discontinuity between matrix and inclusions of different phases. A micromechanics model, the “generalized self-consistent scheme (GSCS)” based on a particle-matrix embedding in the effective medium, is generalized to evaluate the effective conductivity of multiphase medium with imperfect thermal contact at constituent interfaces. Numerical results are given for three-phase particulate composites with spherical particles to illustrate the effect of imperfect interfaces on the effective thermal conductivity of multiphase composites.Keywords: Effective thermal conductivity, Multiphase composites, Thermal contact resistance, Micromechanics model. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 135-140 Report on FY 2007 Functionally Graded Materials Database Report on FY 2007 Functionally Graded Materials Database Katsuto Kisara 1),a, Tomomi Konno 2), b and Masayuki Niino 2),c1)JAXA, Koganesawa 1, Kimigaya, Kakuda city, Miyagi, 981-1525, JAPAN2)Japan Aerospace Technology, Izumi-cyuoh 1-16-6, Izumi-ku, Sendai city, Miyagi, 981-3133, JAPAN Katsuto Kisara 1),a, Tomomi Konno 2), b and Masayuki Niino 2),c1)JAXA, Koganesawa 1, Kimigaya, Kakuda city, Miyagi, 981-1525, JAPAN2)Japan Aerospace Technology, Izumi-cyuoh 1-16-6, Izumi-ku, Sendai city, Miyagi, 981-3133, JAPAN Functionally Graded Materials Database (hereinafter referred to as FGMs Database) has been run by Japan Aerospace Exploration Agency (JAXA) since October, 2002. So far, the database contains 1,815 research paper information including 12,790 figures and tables, 2,632 author information, 904 PDFs, and 563 university, research institution and company information. The database had been used by 34,968 users from 113 countries in FY2007, where the effective total visits counted to 73,072. Approx. 20% of users had repeatedly visited the website. In FY 2007 users from Japan were significantly increased. Additionally, the interest of Europe and Middle east/Africa region was remarkable.Keywords: FGMs database, Internet, Functionally Graded Materials English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 141-146 SYNTHESIS AND PROPERTIES OF GRADED POROUS TI-TIO2 MULTIFUNCTIONAL COMPOSITES OBTAINED BY DIFFERENT PROCESSING METHODS SYNTHESIS AND PROPERTIES OF GRADED POROUS TI-TIO2 MULTIFUNCTIONAL COMPOSITES OBTAINED BY DIFFERENT PROCESSING METHODS Sofiane Bouazza, Elke Fuchs, Andreas Rosin and Monika Willert-PoradaChair of Materials Processing, Faculty of Applied Natural Sciences, University of Bayreuth,D-95447 Bayreuth, Germany Sofiane Bouazza, Elke Fuchs, Andreas Rosin and Monika Willert-PoradaChair of Materials Processing, Faculty of Applied Natural Sciences, University of Bayreuth,D-95447 Bayreuth, Germany Functionally graded materials for load bearing implants have a long history of academic development and an already high degree of maturity. Efforts are now undertaken to improve the biocompatibility and even induce bioactivity within the implant-bone interface by optimised surface nanostructure of porous ceramic and metalic layers grown or sintered on a metallic implant, in order to arrive at cementless implants capable of fast osteointegration and high interface strength. Several new methods for surface structure and composition modification are presented for Ti-alloy based implants: a nano-structuring of the surface by re-deposition of TiO2 using an ECRMicrowavePlasma treatment combined with ion bombardment on a sintered TiO2 ceramic surface, a multiscale modification of porous Ti-coatings by means of Micro-Arc-Oxidation, MAO, and a meso-structuring of the surface by means of a laser treatment. The goal is to establish a multifunctionality in such materials by formation of a morphological and compositional gradient spanning many dimensions. The applicability of these methods to real implants is discussed for a dental implant. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 149-154 Adaptive composite materials with novel architectures Adaptive composite materials with novel architectures Jean-Francois SILVAIN 1), a, Valerie DENIS-LUTARD 1), b, Pierre-MarieGEFFROY 2), c and Jean-Marc HEINTZ 1), d1) CNRS, Universite de Bordeaux, Institut de Chimie de la Matiere Condensee de Bordeaux(ICMCB), 87 avenue du Dr. A. Schweitzer, Pessac, F-33608, France2) ENSCI, Laboratoire de Science des Procedes Ceramiques et de Traitements de Surface,S.P.C.T.S., 47 a 73 Avenue Albert Thomas, F-87065 Limoges, France. Jean-Francois SILVAIN 1), a, Valerie DENIS-LUTARD 1), b, Pierre-MarieGEFFROY 2), c and Jean-Marc HEINTZ 1), d1) CNRS, Universite de Bordeaux, Institut de Chimie de la Matiere Condensee de Bordeaux(ICMCB), 87 avenue du Dr. A. Schweitzer, Pessac, F-33608, France2) ENSCI, Laboratoire de Science des Procedes Ceramiques et de Traitements de Surface,S.P.C.T.S., 47 a 73 Avenue Albert Thomas, F-87065 Limoges, France. Today, there is a strong push to improve the thermal management of electronic components in order to increase the performance and the reliability of electronic devices. Up to now, most of the heat sinks are mainly made of Copper that presents a good thermal conductivity (TC) but a coefficient of thermal expansion (CTE) much higher than the ceramic of the DBC (direct bonding Copper). It induces interfacial thermal stresses and indeed it decreases the reliability of the global electronic system. Therefore, there is a strong need for the development of novel heat dissipation material having low CTE combined with high TC. Carbon fibres reinforced copper matrix offers a good compromise between thermo mechanical properties (i.e. CTE) and medium TC. In order to increase surface TC, pure Copper can be added on the top surface and/or on the bottom one of the composite heat sink playing the role of heat spreader for hot spots linked with the Si components. The fabrication technique of these materials is based on powder metallurgy technique. The thermal properties of adaptive materials, TC and CTE, have been measured for different Copper thicknesses and architectures ([C/Cu], [Cu ? C/Cu] and [Cu ? C/Cu ? Cu]). Simulation of the TC and CTE have been performed and compared to the experimental results.Keywords: Thermal management, thermal conductivity, coefficient of thermal expansion, Coppermatrix composite, powder metallurgy, Carbon fibre English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 155-160 The Effect of Particles’ Size on the Plastic Behavior of Particles Reinforced Metal Matrix The Effect of Particles’ Size on the Plastic Behavior of Particles Reinforced Metal Matrix Lisheng Liu 1),a Dongfeng Cao 2),b, Hai Mei 2),c Qingjie Zhang 1),b1) State Key Laboratory of Materials Synthesis and Processing, Wuhan University of Technology,Wuhan, 430070, China2) Department of Engineering Structure and Mechanics, Wuhan University of Technology, Wuhan, 430070, China Lisheng Liu 1),a Dongfeng Cao 2),b, Hai Mei 2),c Qingjie Zhang 1),b1) State Key Laboratory of Materials Synthesis and Processing, Wuhan University of Technology,Wuhan, 430070, China2) Department of Engineering Structure and Mechanics, Wuhan University of Technology, Wuhan, 430070, China The size effect on particles reinforced metal matrix composites (MMCp) was investigated by a numerical method. A numerical multi-particles unit cell model has been constructed to carryout numerical analysis. In this model, circle particles were randomly placed in matrix according to uniform distribution, the sizes of particles in the paper were classified into 4 groups: 6μm, 13.5μm ,50μm, and 100μm respectively. For investigating the effect of particles’ size on the plastic behavior of MMCp, the Griffith fracture criterion and the damage of ceramic particles wereconsidered. Result showed that there was a close relationship between the particle size and the deformation behavior of the composites. Yield strength and plastic work hardening rate of thecomposites increase with decreasing particle size. The predicted stress?strain behaviors of the composites were in agreement with the experimental results.Keywords: MMCp , damage model, size effect, Griffith fracture English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 161-166 Basic approach to graded compound of magnetic particle with polyester resin in magnetic field Basic approach to graded compound of magnetic particle with polyester resin in magnetic field Mikiya Ito 1),a, Tatsuro Sakamoto 1),b and Minoru Suzuki 1),c1) Materials Technology Division, Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji-shi, Tokyo, 185-8540, Japan Mikiya Ito 1),a, Tatsuro Sakamoto 1),b and Minoru Suzuki 1),c1) Materials Technology Division, Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji-shi, Tokyo, 185-8540, Japan Functionally Graded Material (FGM) is a characteristic material having many functions and possibilities. The improvement of the long term stability is strongly necessitated by railway polymeric materials. To carry out the purpose, FGM is an expected material that enables to improve the certain properties and affinities. The authors tried to produce a graded compound of the magnetic particles in the polymer matrix in the magnetic field. From the results, the graded compound of the magnetic particles was produced by the control of magnetic flux. In particular, the control of time during which the magnetic field was charged was effective to improve the dispersion state of the magnetic particles in polymer matrix.Keywords: FGM (Functionally graded material), Unsaturated Polyester, Magnetic particle, Magnetic field, Mechanical property. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 167-172 Synthesis, Structure and Properties of Niobium Aluminum Oxynitride and Tantalum based Compound Prepared through Citrate Route Synthesis, Structure and Properties of Niobium Aluminum Oxynitride and Tantalum based Compound Prepared through Citrate Route Yuji Masubuchi 1), a, Shinichi Yamamoto 1), b, Takashi Takeda 2), c andShinichi Kikkawa 1), d1) Graduate School of Engineering, Hokkaido University, Sapporo, JAPAN2) Nano Ceramics Center, National Institute for Material Science, Tsukuba, JAPAN Yuji Masubuchi 1), a, Shinichi Yamamoto 1), b, Takashi Takeda 2), c andShinichi Kikkawa 1), d1) Graduate School of Engineering, Hokkaido University, Sapporo, JAPAN2) Nano Ceramics Center, National Institute for Material Science, Tsukuba, JAPAN The oxynitrides with composition A_1-xB_x(O_yN_z) (A: Nb and Ta, B: Al) were studied inpreparation through citrate route and NH₃ nitridation. In the case of Nb, the product of x = 0.5prepared at 1000 oC was a new compound of a = 0.435 nm with rock salt structure. In this structure, Aland Nb atoms were distributed randomly in the cation sites. Anion sites were also randomly occupiedby oxide and nitride ions with some amount of vacancy. The chemical composition was representedas Nb_0.56Al_0.44O_0.38N_0.37□_0.25 from Rietveld refinement and oxygen/ nitrogen measurement. In the caseof Ta, monoclinic Ta3N5 crystallized with a small amount of Ta₄N₅ impurity at x = 0.5. Aluminumcompound was co-present as amorphous impurity.Keywords: Niobium Aluminum Oxynitride, Tantalum Nitride, Citrate Route, Ammonia Nitridation, Crystal Structure, Superconductor. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 175-179 Biocompatibility aspects of NiTi-based medical implants Biocompatibility aspects of NiTi-based medical implants Timo Jamsa 1),a, Virpi Muhonen 1), 2),b, Anatoli Danilov 1) and Juha Tuukkanen 2),c1) Department of Medical Technology, Institute of Biomedicine, University of Oulu2) Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu Timo Jamsa 1),a, Virpi Muhonen 1), 2),b, Anatoli Danilov 1) and Juha Tuukkanen 2),c1) Department of Medical Technology, Institute of Biomedicine, University of Oulu2) Department of Anatomy and Cell Biology, Institute of Biomedicine, University of Oulu Nickel-titanium is a functional alloy currently used in various clinical applications, especially in vascular stents. There is an increased interest in the orthopaedic use of NiTi-based implants. The alloy enables the manufacture of applications of constant load, controllable motion, and minimal invasiveness. NiTi is considered biocompatible and it possesses mechanical properties that make it an especially good candidate for bone tissue surroundings. In our studies, we have investigated the effects of surface properties of NiTi on its biocompatibility. The martensitic phase was shown to have lower biocompatibility of material in comparison with austenitic NiTi. Cellular cytotoxicity increased and cell adhesion diminished on martensite phase. This was observed with both osteoblasts and osteoclasts. Our studies showed that the thickness of the oxide layer does not necessarily enhance the biocompatibility. The surface state of NiTi is strongly affected by thermal oxidation. Surface properties affect the initial adsorption of proteins and other macromolecules onto the biomaterial surface; this in turn impacts the following cellular responses, such as proliferation and differentiation, which are dictated by adhesion to the extracellular matrix components. Since adhesive force is connected to the interaction with the adsorbed molecules, it might be an important factor in the biocompatibility. Sol-gel derived titania-silica surface treatment was observed to increase the bone-implant coating of functional intramedullary NiTi nails. Sol-gel treatment together with the bending force increased the fixation of the implant (osseointegration). These studies indicate that the surface properties of NiTi are important for its biocompatibility.Keywords: Nitinol, shape memory, implant, biocompatibility, surface properties, cell behaviour. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 181-186 Various nanotube scaffolds for cell proliferation Various nanotube scaffolds for cell proliferation F. Watari 1), a, T. Akasaka 1), K. Ishikawa 1), M. Matsuoka 1), E. Hirata 1), N. Terada 1),A. Yokoyama 1), M. Uo 1), S. Itoh 1), Y. Yawaka 1), M. Suzuki 2), N. Takashi 1), Y.Totsuka 1), Y. Kitagawa 1), S. Abe 1), I.D. Rosca 3), Y. Kuboki 1) and Y.Bando 4)1) Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan2) Institute for Geo-Resources and Environment, AIST, Tsukuba, Ibaraki 305-8567, Japan3) Mechanical & Industrial Engineering, Concordia University, Montreal, Quebec H3G1M8, Canada4) Nanoscale materials center, NIMS, Tsukuba, Ibaraki 305-0044, Japan F. Watari 1), a, T. Akasaka 1), K. Ishikawa 1), M. Matsuoka 1), E. Hirata 1), N. Terada 1),A. Yokoyama 1), M. Uo 1), S. Itoh 1), Y. Yawaka 1), M. Suzuki 2), N. Takashi 1), Y.Totsuka 1), Y. Kitagawa 1), S. Abe 1), I.D. Rosca 3), Y. Kuboki 1) and Y.Bando 4)1) Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan2) Institute for Geo-Resources and Environment, AIST, Tsukuba, Ibaraki 305-8567, Japan3) Mechanical & Industrial Engineering, Concordia University, Montreal, Quebec H3G1M8, Canada4) Nanoscale materials center, NIMS, Tsukuba, Ibaraki 305-0044, Japan Carbon nanotubes (CNT) and their derivatives with different structure and compositions have unique features. In the present study, cell proliferation was performed on various nanotubes such as single walled CNTs, multiwalled CNTs and imogolite which is nanotubes of aluminosilicate. SEM observation of the growth of osteoblast-like cells cultured on CNTs showed the morphology fully developed for the whole direction, which was different from that extended to the one direction on the usual scaffold. Numerous filopodia were grown from cell edge, extended far long and combined with CNT meshwork. Apatite precipitation in simulated body fluid, affinity for proteins and saccharides, and nanosize meshwork structure with large porosity would be the properties responsible for these cell adhesion and growth. Imogolite showed the similar properties to CNTs. Nanotubes could be the favorable materials for biomedical applications.Keywords: carbon nanotube, imogolite, cell culture, scaffold, tissue regeneration, apatite English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 187-192 Fabrication of Apatite/Titanium Functionally Graded Coating Using Supersonic Free-Jet PVD Fabrication of Apatite/Titanium Functionally Graded Coating Using Supersonic Free-Jet PVD Atsushi Yumoto 1),a, Takahisa Yamamoto 2),b,Ichiro Shiota 1),c and Naotake Niwa 1),d1) Faculty of Engineering, Kogakuin University, Tokyo 192-0015, JAPAN2) Gradiate School of Frontier Sciences, University of Tokyo, Tokyo 113-8656, JAPAN Atsushi Yumoto 1),a, Takahisa Yamamoto 2),b,Ichiro Shiota 1),c and Naotake Niwa 1),d1) Faculty of Engineering, Kogakuin University, Tokyo 192-0015, JAPAN2) Gradiate School of Frontier Sciences, University of Tokyo, Tokyo 113-8656, JAPAN Hydroxyapatite (HAp) is very attractive in medical field. The objective of this study is to produce HAp/Ti composite coating with Supersonic Free-Jet PVD (SFJ-PVD). The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form a thick coating film. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the pressure difference between the chambers and accelerated to the supersonic flow of 4.2 Mach through a specially designed supersonic nozzle. With SFJ-PVD, we obtain a uniform high-density HAp/Ti composite coating. XRD analysis reveals that the composite coating is composed of Ti and HAp. An in-vitro study was carried out to investigate the bioactivity of the HAp/Ti composite coating under simulated bodyfluid.Keywords: biomaterial, nanoparticle, simulated body fluid, bone-like apatite, supersonic gas flow English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 193-198 Preparation of functionally graded bio-ceramic film by MOCVD Preparation of functionally graded bio-ceramic film by MOCVD Mitsutaka Sato 1), a, Rong Tu 1),b , Takashi Goto 1),c , Kyosuke Ueda 2),d and TakayukiNarushima 2),e1) Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Miyagi 980-8577, Japan.2) Department of Materials Processing, Tohoku University, Aramaki Aza Aoba 6-6, Aoba-ku, Sendai, Miyagi 980-8579, Japan. Mitsutaka Sato 1), a, Rong Tu 1),b , Takashi Goto 1),c , Kyosuke Ueda 2),d and TakayukiNarushima 2),e1) Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Miyagi 980-8577, Japan.2) Department of Materials Processing, Tohoku University, Aramaki Aza Aoba 6-6, Aoba-ku, Sendai, Miyagi 980-8579, Japan. Functionally graded Ca-Ti-O/Ca-P-O films were prepared by MOCVD. The phases, composition and morphology of Ca-Ti-O and Ca-P-O films changed depending on the molar ratio of each precursors, total pressure (P_tot) and substrate temperature (T_sub). CaTiO₃ films in a single phase were obtained at Tsub = 973 and 1073 K. CaTiO₃ films prepared at 873 K had a dense and smooth surface, whereas that prepared at T_sub = 1073 K had complicated rough surface with a cauliflower-like texture. The graded texture of CaTiO₃ films from columnar to fine grains was advantageous to good adherence for metal substrates. α-TCP and HAp films in a single phase were obtained at T_sub = 973 and 1073 K. Both α-TCP and HAp films had a dense and smooth surface. The maximum deposition rate of Ca-Ti-O and Ca-P-O films were 44 and 20 μm/h, respectively, and several 10 times grater than that of sputtering method. Apatite formation rate strongly depended on the surface morphology of film. Apatite formed after 3 days on the CaTiO₃ film, 14 days on the α-TCP film and 6 hours on the HAp film in a Hanks’ solution.Keywords: Metal organic chemical vapor deposition, Hydroxyapatite, Calcium titanate, α-tricalcium phosphate English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 199-204 Fabrication of Titanium / Biodegradable-polymer FGM for Medical Application Fabrication of Titanium / Biodegradable-polymer FGM for Medical Application Yoshimi Watanabe 1), a, Yoshimi Iwasa 1),b, Hisashi Sato 1),c,Akira Teramoto 2),d and Koji Abe 2),e1) Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Aichi, Japan2) Shinshu University, Tokida 3-15-1, Ueda 386-8567, Nagano, Japan Yoshimi Watanabe 1), a, Yoshimi Iwasa 1),b, Hisashi Sato 1),c,Akira Teramoto 2),d and Koji Abe 2),e1) Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Aichi, Japan2) Shinshu University, Tokida 3-15-1, Ueda 386-8567, Nagano, Japan Ti and Ti alloys are widely used as metallic implants, because of their good mechanical properties and nontoxic behavior. However, they have problems as the implant-materials, namely, high Young’s modulus comparing that of bone and low bonding ability with bone. There is a need to develop the Ti and Ti alloys with lower Young’s modulus and good bonding ability. In previous study, Ti composite containing biodegradable poly-L-lactic-acid (PLLA) fiber has been fabricated to improve these problems. However, this composite has low strength because of the imperfect sintering of Ti matrix. To improve its strength, sintering of Ti matrix should be completed. In this study, Ti-NaCl composite material was fabricated by spark plasma sintering (SPS) method using powder mixture of Ti and NaCl to complete the sintering of Ti matrix. To obtain porous Ti samples, Ti-NaCl composite were put into hot water of 100^o C. The porous Ti was dipped into PLLA melt in order to introduce PLLA into the pores of porous Ti. Finally, Ti-PLLA composite was obtained, and PLLA plays a role as reinforcement of Ti matrix. It was found that the Ti-PLLA composite has gradient structure and mechanical properties.Keywords: Commercially pure (CP) Ti, poly L-lactic acid (PLLA), spark plasma sintering (SPS), biomaterial, wear English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 205-210 Mechanical properties-graded Ti alloy implants for orthopedic applications Mechanical properties-graded Ti alloy implants for orthopedic applications T.K. Jung 1), a, H. Matsumoto 2),b, T. Abumiya 2),c, N. Masahashi 2),d, M.S. Kim 3),e and S. Hanada 2),f1) Innovation Plaza Miyagi, Japan Science and Technology Agency, Sendai 989-3204, Japan2) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan3) School of Materials Science and Engineering, Inha University, Incheon 402-751, Korea T.K. Jung 1), a, H. Matsumoto 2),b, T. Abumiya 2),c, N. Masahashi 2),d, M.S. Kim 3),e and S. Hanada 2),f1) Innovation Plaza Miyagi, Japan Science and Technology Agency, Sendai 989-3204, Japan2) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan3) School of Materials Science and Engineering, Inha University, Incheon 402-751, Korea Low Young’s modulus is attained by controlling phase stability of b (bcc) Ti-Nb-Sn alloys consisting of non-cytotoxic elements, based on experimental results that Young’s modulus decreases with decreasing temperature toward a” (orthorhombic) martensitic transformation start temperature (M_s). Cold groove rolled, metastable b (Ti-35%Nb)-4%Sn alloy exhibits low Young’s modulus of about 40 GPa at 297 K, measured by the free resonance vibration method. This value is much lower than that of Ti-6%Al-4%V and close to that of human cortical bone. By heating one edge of the groove rolled rod to 573 K for 4 h, hardness and Young’s modulus are found to increase significantly at the heated zone and to change depending on distance from the heated zone. The increase in hardness is explained mainly by fine a precipitation and additionally by microstructure refinement through reverse transformation a”→b of deformation-induced martensite. From these results, an advanced stem having high strength at the necked part can be developed for a new artificial hip joint, keeping low Young’s modulus at the distal part implanted in a femur.Keywords: Ti alloy, implant, stem, mechanical property, Young's modulus, hardness, English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 211-216 Calcium Phosphate Coating on Blast-treated Titanium Implants by RF Magnetron Sputtering Calcium Phosphate Coating on Blast-treated Titanium Implants by RF Magnetron Sputtering K. Ueda 1),a T. Narushima 1),b T. Goto 2),c T. Katsube 3),d H. Nakagawa 3),eH. Kawamura 3),f and M. Taira 4),g1) Department of Materials Processing, Tohoku University, Sendai 980-8579, Japan2) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan3) Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan4) Department of Dental Materials Science and Technology, Iwate Medical University School ofDentistry, Morioka 020-8505, Japan K. Ueda 1),a T. Narushima 1),b T. Goto 2),c T. Katsube 3),d H. Nakagawa 3),eH. Kawamura 3),f and M. Taira 4),g1) Department of Materials Processing, Tohoku University, Sendai 980-8579, Japan2) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan3) Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan4) Department of Dental Materials Science and Technology, Iwate Medical University School ofDentistry, Morioka 020-8505, Japan Calcium phosphate coating films were fabricated on Ti-6Al-4V plates and screw-type implants with a blast-treated surface using radiofrequency (RF) magnetron sputtering and were evaluated in vitro and in vivo. Amorphous calcium phosphate (ACP) and oxyapatite (OAp) films obtained in this study could cover the blast-treated substrate very efficiently, maintaining the surface roughness. For the in vitro evaluations of the calcium phosphate coating films, bonding strength and alkaline phosphatase (ALP) activity were examined. The bonding strength of the coating films to a blast-treated substrate exceeded 60 MPa, independent of film phases except for the film after post-heat-treatment in silica ampoule. When compared with an uncoated substrate, the increase in the ALP activity of osteoblastic SaOS-2 cells on a calcium phosphate coated substrate was confirmed by a cell culture test. The removal torque of screw-type Ti-6Al-4V implants with a blast-treated surface from the femur of Japanese white rabbit increased with the duration of implantation and it was statistically improved by coating an ACP film 2 weeks after implantation. The in vitro and in vivo studies suggested that the application of the sputtered ACP film as a coating on titanium implants was effective in improving their biocompatibility with bones.Keywords: titanium, amorphous calcium phosphate, oxyapatite, adherence test, alkaline phosphatase activity, removal torque English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 217-222 Modelling of processing of FGM bioimplants Modelling of processing of FGM bioimplants Michael Gasik 1),a, Baosheng Zhang 1),b1) Helsinki University of Technology ? TKK, FIN-02015 TKK, Espoo, Finland Michael Gasik 1),a, Baosheng Zhang 1),b1) Helsinki University of Technology ? TKK, FIN-02015 TKK, Espoo, Finland Bioimplants composed of metal and ceramic parts are recently widely used in medicine. It was shown that properties of these implants might be substantially improved with functionally graded materials (FGM). In this work ceramics FGM are considered with emphasis on the optimal processing technique. For ceramic balls and liners of total hip replacement prosthesis optimal sintering procedure is very important irrespectively on the initially selected graded composition profile to get beneficial stresses distribution after sintering and assembling. Different examples are shown and influence of the sintering and gradient profile selection on final properties is discussed.Keywords: biomaterials, functionally graded materials, ceramics, sintering, finite element analysis, alumina, zirconia. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 225-230 Advanced nanostructure-controlled functionally graded materials employing carbon nanotubes Advanced nanostructure-controlled functionally graded materials employing carbon nanotubes Mehdi Estili *, Kenta Takagi, Akira KawasakiDepartment of Materials Processing, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan Mehdi Estili *, Kenta Takagi, Akira KawasakiDepartment of Materials Processing, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan Capability of multiwalled carbon nanotubes (CNTs) to create in-depth gradients in properties and functionalities of conventional materials has been investigated for the first time.Functionally graded material (FGM) concept has also been employed for the first time to bridge conventional materials to their advanced nanocomposites containing a high concentration of CNTs, which is promising for unexplored yet novel structural, electronic and biomaterial applications. In this study, α-alumina ceramics considered as the most challenging case has been used as the matrix. Bulk, layered, nanostructure-controlled, CNT-based, functionally graded α-alumina ceramics have been fabricated employing a recently established powder processing technology. In-depth gradients in microstructure, grain size and hardness have been successfully achieved in alumina ceramic without cracking, delamination or warping, after homogeneous and gradual incorporation of the CNTs within the alumina ceramic matrix. The FGM approach showed promise to successfully bridge conventional ceramics to their nanocomposites containing a high concentration of CNTs.Keywords: Alumina, Carbon nanotubes, Functionally graded materials, Powder technology, Nanocomposites, Spark plasma sintering English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 231-236 Reinforcement of Alumina with Surface Modified Carbon Nanotubes Reinforcement of Alumina with Surface Modified Carbon Nanotubes Go Yamamoto 1), a, Toshiyuki Hashida 2), b, Mamoru Omori 2), cand Hisamichi Kimura 3), d1) Institute of Fluid Science, Tohoku University, Japan2) Fracture and Reliability Research Institute, Tohoku University, Japan3) Institute for Materials Research, Tohoku University, Japan Go Yamamoto 1), a, Toshiyuki Hashida 2), b, Mamoru Omori 2), cand Hisamichi Kimura 3), d1) Institute of Fluid Science, Tohoku University, Japan2) Fracture and Reliability Research Institute, Tohoku University, Japan3) Institute for Materials Research, Tohoku University, Japan Multi-walled carbon nanotube (MWCNT) reinforced alumina composites were prepared by spark plasma sintering using pristine MWCNTs and acid-treated MWCNTs. The effect of acid treatment on the structure and surface potential of the MWCNTs was examined by transmission electron microscopy (TEM) and zeta potential analyzer. It is demonstrated that with the acid treatment of the MWCNTs, we have deliberately introduced nanoscale defects and negatively charged functional groups on the surface of the MWCNTs. The average depths of the defects are typically 4.8-10.8 nm. Mechanical measurements revealed that surface modification of the MWCNTs is effective in improvement of bending strength and fracture toughness of the MWCNT/alumina composites. Only 0.9 vol.% acid-treated MWCNT addition results in 27% and 25% simultaneous increases in bending strength (689.6 MPa) and fracture toughness (5.90 MPa m^1/2), respectively. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 239-244 Fabrication of (cemented carbides/steel) bilayered materials by powder metallurgy Fabrication of (cemented carbides/steel) bilayered materials by powder metallurgy A. Thomazica, C. Pascalb and J.M. ChaixcLaboratoire de Science et Ingenierie des Materiaux et Procedes, SIMaPGrenoble INP-CNRS-UJF, BP75 ? 38402 Saint Martin d’Heres, France A. Thomazica, C. Pascalb and J.M. ChaixcLaboratoire de Science et Ingenierie des Materiaux et Procedes, SIMaPGrenoble INP-CNRS-UJF, BP75 ? 38402 Saint Martin d’Heres, France This paper analyses the effects of five parameters (composition, compaction pressure, heating rate, sintering temperature and duration) on the sintering of a bilayered (cementedcarbide/steel) material. Design of experiments is used to reduce the number of experiments and to analyse the results. After sintering, each sample is characterized (difference of shrinkage, shrinkage anisotropy, density and microstructure). Composition, sintering temperature and duration are the three main parameters which control the sintering of bimaterials, their microstructure and the interface quality. The heating rate and the compaction pressure have no significant effect in the tested domain.Keywords: multimaterial, co-sintering, cemented carbide, steel, η-phase, D.O.E. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 245-250 Effects of Inhomogenization on Sintering Behavior of Ni/Al₂O₃ Powder Mixtures Effects of Inhomogenization on Sintering Behavior of Ni/Al₂O₃ Powder Mixtures Kazunari Shinagawa 1), a12217-20 Hayashi-cho, Takamatsu, Kagawa 761-0396, JAPAN Kazunari Shinagawa 1), a12217-20 Hayashi-cho, Takamatsu, Kagawa 761-0396, JAPAN Aiming at the modification of the sinterability of metal/ceramic powder mixtures, the influence of the homogeneity in microstructure on the sintering behavior is examined. Ni/Al₂O₃ specimens, with ratios ranging from 0/100 to 100/0, are prepared by compaction through two different procedures of mixing and granulating, to change the degree of particle dispersion. The sintering stress and the viscosity of the specimens are measured by sinter-compression tests to consider the sinterability from the viewpoint of both driving force and resistance. The sintering rate of the inhomogeneous compacts, with agglomeration of powder particles, is larger than that of the homogeneous compacts. This is because the viscosity becomes low, but the sintering stress does not change much by inhomogenizing the microstructure.Keywords: Powder processing, Composite, Sinterability, Sintering stress, Homogeneity English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 253-258 Manufacturing of Functionally Graded Porous Products by Selective Laser Sintering Manufacturing of Functionally Graded Porous Products by Selective Laser Sintering M. Erdala, S. Dagb, Y. Jandec and C.M. TekindDepartment of Mechanical Engineering, Middle East Technical University, Ankara 06531, Turkey M. Erdala, S. Dagb, Y. Jandec and C.M. TekindDepartment of Mechanical Engineering, Middle East Technical University, Ankara 06531, Turkey Selective laser sintering (SLS) is a rapid prototyping technique which is used to manufacture plastic and metal models. The porosity of the final product obtained by SLS can be controlled by changing the energy density level used during the manufacturing process. The energy density level is itself dependent upon manufacturing parameters such as laser power, hatching distance and scanning speed. Through mechanical characterization techniques, it is possible to quantitatively relate the energy density levels to particular strength values. The present study is directed towards manufacturing functionally graded polyamide products by changing the energy density level in a predetermined manner. The mechanical properties of the functionally graded components are characterized by means of tensile testing. Both homogeneous and functionally graded specimens are produced and tested in order to examine the influence of the energy density level on the mechanical response and on the ultimate tensile and rupture strengths. Selective laser sintering is shown to possess the potential to produce functionally graded porous specimens with controlled variations in physical and mechanical properties.Keywords: Selective Laser Sintering; Porosity; Layered Manufacturing; Tensile Testing. English Multiscale, Multifunctional and Functionally Graded Materials Multiscale, Multifunctional and Functionally Graded Materials 631-632 2010-01-01 259-264 Intermetallic Coating Using a 3-Dimensional Micro Welder Intermetallic Coating Using a 3-Dimensional Micro Welder Kiyotaka Matsuura 1),a, Naoki Mizuta 1),b, Soshu Kirihara 2),c, Yoshinari Miyamoto 3),d and Atsushi Yumoto 4),e1) Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan2) Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 057-0047, Japan3) Toyo Tanso Co.,Ltd., 5-7-12 Takeshima, Nishiyodogawa-ku, Osaka, Osaka 555-0011, Japan4) Faculty of Engineering, Kogakuin University, Hachioji, Tokyo 192-0015, Japan Kiyotaka Matsuura 1),a, Naoki Mizuta 1),b, Soshu Kirihara 2),c, Yoshinari Miyamoto 3),d and Atsushi Yumoto 4),e1) Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan2) Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 057-0047, Japan3) Toyo Tanso Co.,Ltd., 5-7-12 Takeshima, Nishiyodogawa-ku, Osaka, Osaka 555-0011, Japan4) Faculty of Engineering, Kogakuin University, Hachioji, Tokyo 192-0015, Japan The authors have studied a new method of intermetallic coating using a small TIG welder. This method is based on a reaction between small liquid beads produced from very thin metal wire and the substrate metal surface. The authors designed a computer-aided 3-dimensional micro welder (3DMW) for a previous study on freeform fabrication of intermetallics, and have applied it to this study on intermetallic coating. In this study, a predetermined length of thin aluminum wire was fed onto the titanium substrate surface, and a spark was stricken from a thin electrode of a W-Ce₂O₃ alloy to make a small aluminum liquid bead on the titanium substrate surface and to simultaneously melt a small area of the substrate surface beneath the liquid bead. All process conditions had been programmed beforehand, including the length of the wire feeding per spark, the position of the electrode, electric power, movement of the stage holding the substrate, etc. The liquid bead containing aluminum and titanium rapidly solidified on the titanium substrate surface producing titanium aluminides on it. Repetition of the aluminum wire feeding, the electrode positioning and the spark striking produced a coating layer consisting of sub-layers of TiAl₃, TiAl and Ti₃Al from the surface side to the substrate side. Vickers hardness and wear resistance of the coated sample were remarkably improved.Keywords: Surface modification, Titanium aluminides, TIG welding, CAD/CAM, Rapid prototyping English