Progress in Non Conventional and Novel Manufacturing Routes to Ceramics
Session CB-1 - Solution-based Processing
CB-1:IL02 Multi-porous Advanced Ceramics for Biomedical, Biotechnological and Environmental Applications
K. REZWAN, Advanced Ceramics, University of Bremen, Bremen, Germany
As a consequence of the growing and aging global population, the increasing numbers of industrialised countries as well as limited natural resources, questions concerning health, a clean environment, sustainable technologies and green chemistry have become of paramount importance. In search for novel approaches, these questions have rapidly propelled the evolvement of biomedical, biotechnological and environmental research areas. By functionalising porous ceramics with inorganic, organic and biological compounds, a great number of functional properties can be combined with the advantages of a chemically robust, but at the same time modifiable material substrate. Other and our own studies have shown that advanced ceramics are therefore of particular interest for biomolecule, virus or bacteria filtration and adsorption as well as for drug delivery systems. Key ideas and findings of these studies will be highlighted in this talk and discussed.
CB-1:L03 Phospho-silicate Hydraulic Cements: Studies of Hydration, Toughening and Self-Healing Behaviour
T. TROCZYNSKI, S. ZHOU, A. GOUDARZI, Materials Engineering, University of British Columbia, Vancouver B.C., Canada
The novel Calcium Phosphate Silicate Cement (CPSC) appears to combine the best properties of Calcium Phosphate Cement (CPC) and Calcium Silicate Cement (CSC). This presentation will discuss CPSC development process, including the effects of phosphates on the properties of CPSC after hydration (setting) at 37ºC for 3 to 28 days, and its final properties (variation of pH, compressive and 3-point bending strength, in vitro bioactivity and cytotoxicity). The phase transformations in CPSC during setting show that calcium hydroxide, produced during the hydration of calcium silicates, reacts with phosphate additives to form hydroxyapatite. The in-situ formation of a nanocomposite from the hydroxyapatite and calcium silicate hydrates appears responsible for the significant enhancement in CPSC strength, bioactivity, and biocompatibility, compared to pure CSC. Such CPSC has been toughened to > 2kJ/m2 fracture toughness by dispersion of short PVA fibres, resulting in strain-tolerant material, with the failure strain extending from 0.1% for pure CPSC to > 2% for PVA-CPSC. The self-healing abilities of such strain-tolerant composite cements has been studied by exposure to the Simulated Body Fluid (SBF) for up to 7 days at 37ºC. It was observed that this material has the unique ability to self-heal the damage (cracks), resulting in partial restoration of the load carrying capacity of the cement. The proposed mechanism includes preferential precipitation of calcium phosphates within the high-pH environment within the cracks.
CB-1:L04 Preparation and Visible Light Induced NOx Destruction Activity of C-NaTaO3 and C-NaTaO3/Cl-TiO2
XIAOYONG WU, QIANG DONG, SHU YIN, T. SATO, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
Recently, perovskite-type NaTaO3, one of the most promising photocatalysts, has been devoted remarkable efforts because of its outstanding photocatalytic performances in water splitting and toxic pollutant gas or solution removing. However, the excitation of NaTaO3 for photocatalysis was strictly limited in the UV light which accounts for less than 5% of total solar light, owing to the wide intrinsic band gap of NaTaO3 about 4 eV. Therefore, an effective visible light responsive NaTaO3 is still strongly required. In this work, a C doped NaTaO3 with visible light absorption was prepared by a facile hydrothermal reaction using water/ethylene glycol (EG) mixed solution as the solvent without adding any other special carbon precursor. In addition, the destruction of continuous NOx gas was employed to test the photocatalytic activity of samples. The experimental results presented that the visible light absorption, and the corresponding photocatalytic activity could be tuned by changing the EG volumes in the solvent of the hydrothermal reaction. Furthermore, a C doped NaTaO3/Cl doped TiO2 (C-NaTaO3/Cl-TiO2) composite was also employed expecting to improve the visible light induced photocatalytic activity.
CB-1:IL06 Fabrication of Advanced Ceramic Materials by the Complex Sol-Gel Process
A. DEPTULA1, M. BRYKALA1, W. LADA1, T. OLCZAK1, A.G. CHMIELEWSKI1, K.C. GORETTA2, 1Institute of Nuclear Chemistry and Technology, Warsaw, Poland; 2Argonne National Laboratory, Argonne, IL, USA
The Complex Sol-Gel Process (CSGP) was invented as an efficient means to synthesize a wide range of oxides. The main feature of this process is application of ascorbic acid (ASC), a very strong complexing agent, for preparation of the sols. The CSGP consists of following steps: preparation of starting solutions; addition of ASC; formation of complex sol solution; partial hydrolysis by addition of ammonia; evaporation to desired viscosity; and drying and final thermal treatment. The CSGP can form sols with cations of the 1st and 2nd groups, which do not form hydroxide sols. It produces highly amorphous gels with homogeneous distributions of their components. Strong bonds in the networks of the gels retard premature crystallization of individual components.
CSGP sols wet metallic supports well, which is a useful property for many thick-film applications. The coatings produced after thermal treatment adhere strongly to the metallic substrates. Nanocomposites of controlled crystallite size can be produced through various thermal treatments.
We have applied the CSGP to synthesize a wide variety of advanced ceramics, as irregularly shaped and spherical powders and as films, including: TiO2 and various titanates, high-temperature superconductors (Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O families), hydroxyapatite-based bioceramics, electrode materials for high-energy-density lithium-ion batteries and molten carbonate fuel cells (LiMn2O4, LiNixCo1-xO2, LiMg0.50Co0.95O2, Li1.1V3O8), laser gain media (Yb-doped KY(WO4)2 and Y3Al5O12), tritium breeding blankets for fusion reactors (Li2TiO3), nuclear fission fuels and surrogates (UO2 and ThO2), materials for W-188/Re-188 generator columns (TiO2-WO3, ZrO2-WO3, ZrO2-SiO2-WO3), Y902O3 microspheres in the internal radiation therapy of liver cancer, and silica glasses and CaTiO3-based synthetic rock for immobilization of high-level nuclear wastes. In this paper, we review the details of the processes and of the products that can be produced and we discuss the applicability and limitations of the CSGP.
CB-1:L08 Decorated Latex Particles with Inorganic Colloids: Synthesis and Processing
Q. MONEGIER DU SORBIER, A. AIMABLE, C. PAGNOUX, SPCTS, CNRS, ENSCI, Université de Limoges, CEC, Limoges, France
The elaboration of decorated latex particles with inorganic colloids is based on a surfactant free emulsion polymerization. The synthetized particles present the advantage of mixing properties from the organic material (polystyrene beads) and the inorganic colloids (silica) anchored at the interface latex/aqueous medium. Some parameters have been followed, such as the size, the conversion rate and the morphology, in order to get a better understanding of the synthesis progress. The nature of the reactants (inorganic colloid, initiator, amphihilic additive), their ionic interactions, and the experimental procedure were shown to influence the synthesis mechanism. Then forming processes such as the electrophoresis techniques were applied to these hydrid particles in order to study the organization of such micro and nano-scale elements. Materials with controlled porosity could thereafter be created by an appropriated thermal treatment.
CB-1:IL09 Probing the Functionalization of Nano-objects Used for Solution Processing with DOSY NMR
F. RIBOT, UPMC - CNRS - College de France, CMCP-UMR 7574, Paris, France
Nano-objects, such as oxo-clusters and nanoparticles, are versatile bricks from which advanced hybrid organic-inorganic materials can be designed by solution processing techniques. In the so-called nanobuilding block approach, the functionalization of the nanobricks is a very important step. Indeed, by modifying their surface, it can make them compatible with the medium, control their association or introduce new functions.
Examples based on titanium and organotin oxo-clusters and various nanoparticles (CeO2, TiO2, Au) will be presented to illustrate how DOSY (Diffusion Ordered Spectroscopy) NMR, a technique that provides, in solution, access to the diffusion coefficients of the different components of a mixture, can be used to monitor functionalization and distinguish free molecules from those that interact with the nano-objects.
CB-1:L10 Liquid-Phase Synthesis and Engineered Processing of Ceramic and Semiconductor Nanomaterials for Energy and Security Applications
M.Z. HU, Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
Solution-based methods are promising for low cost production and engineered assembly of the nano-building-blocks such as oxide nanoparticles, semiconductor nanocrystals and graphenes. Nanomaterials derived from the well optimized building-blocks needs to be further engineered during 1, 2, or 3 dimensional materials/device structure formations and assembly. Quantum dots are a class of nanocrystals through which quantum confinement could be utilized to enable flexible tailoring of absorption or photoluminescence optical properties ranging from ultraviolet to infrared. Such tunable nanomaterials offer great potential to enhance the efficiency of opto-electronic energy devices such as solid-state lighting and solar cells. Our research is to understand the nanocrystal growth during chemical solution synthesis and the molecular/engineering processing strategies to enhance the photoluminecent quantum yield. In addition, the speaker will present the work of nanocrystals and derived materials for optical management, controlling the light absorption (optical filters) and photoluminescence (wavelength shifters). A case is presented for nuclear detector application to achieve real-time wavelength discrimination of neutron and gamma rays.
CB-1:L11 Solvothermal Morphology Control of Zinc Oxide for Cosmetic Application
T. SATO, S. YIN, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan; T. Goto, T. Tanaka, Daito Kase Kogyo Co., Ltd, Osaka, Japan
Zinc oxide shows excellent UV shielding ability and visible light transparency because of the adequate bandgap energy of ca. 3.3 eV and low refractive index of ca. 2.1., therefore, zinc oxide nanoparticles have been used as cosmetics. However, the comfort of nanoparticles when supplied on the skin is modest. It is expected to improve the comfort of nanoparticles by coupling with plate-like microparticles which are generally used as extender pigments. In the present study, the composite of a plate-like mica extender pigment and morphology controlled zinc oxide nanoparticles, such as spherical and rod-like ones, were prepared by the two-steps soft solution reactions, i.e., after the deposition of spherical zinc oxide nanoparticles on a plate-like mica by solvothermal reaction, the morphology controlled zinc oxide nanoparticles were uniformly grown by the following solvothermal reaction using hexamethylenetetramine, monoethanolamine, triethanolamine and ethylene glycol as precipitants and surface modifiers. The plate-like mica uniformly coated with morphology controlled zinc oxide nanoparticles showed the excellent comfort as well as soft focus property.
CB-1:L12 Automobile Three-way Catalytic Application of Novel Oxygen Storage Materials: Calcium-Doped Ceria-Zirconia Solid Solutions
QIANG DONG, S. YIN, T. SATO, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
Ceria (CeO2)-based materials have been recognized as an important component of the three-way catalysts (TWCs) because of their excellent oxygen storage capacity (OSC). Since the 1990s, many studies have been devoted to CeO2-ZrO2 solid solutions, to reduce the emission of toxic pollutants (CO, NOx, hydrocarbons, etc.) from automobile exhaust due to their enhanced OSC in automotive TWCs, oxidation-reduction behavior and improved thermal stability at elevated temperatures. Herein, Ce0.5-xZr0.5CaxO2-x solid solutions were prepared via a facile solution route using Ce(NH4)2(NO3)6, ZrO(NO3)3.2H2O and Ca(NO3)2.4H2O. The introduction of adequate amounts of calcium ion enhanced the thermal stability and OSC. These novel OSC materials have the potential to be key materials in advanced catalytic converters for automotive three-way catalytic application.
CB-1:L13 Effect of Calcining Temperature of Si3N4 Poly-hollow Microspheres on the Properties of the Porous Si3N4 Ceramics Prepared by Aqueous Gelcasting
JIA-MIN WU, XIAO-YAN ZHANG, JIA-LU LI, JIN-LONG YANG, State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
Highly porous Si3N4 ceramics were prepared by aqueous gelcasting using Si3N4 poly-hollow microspheres as pore-forming agent and the effect of calcining temperature of Si3N4 poly-hollow microspheres on their properties was investigated. With the increase of the calcining temperature, the surfaces of the Si3N4 poly-hollow microspheres become coarser and coarser due to more rod-like β-Si3N4 grains appearing on their surfaces. Only the β-Si3N4 phase is observed in the porous Si3N4 ceramics regardless of the calcining temperature. The Si3N4 poly-hollow microspheres distribute uniformly in the Si3N4 green samples and porous Si3N4 ceramics, and they contact with each other, which could restrict the shrinkage, warpage and cracking of the final material. With the increase of the calcining temperature, the porosity of the porous Si3N4 ceramics increases, while shrinkage, flexural strength and fracture toughness decrease.
Session CB-2 - Polymer Derived Ceramics
CB-2:IL01 SiOC Composite Structures for Intermediate Service Temperatures with Increased Friction Properties
R. GADOW, P. WEICHAND, University of Stuttgart - IFKB, Stuttgart, Germany
PMC are widely used in lightweight engineering applications. The manufacturing technologies are fully developed and raw materials are cheap. The major limiting factor of these reinforced polymers is the maximum useable temperature.
Ceramic Matrix Composites are suitable for service temperatures up to 1500 °C. These composites are composed of ceramic matrices combined with ceramic fibers based on alumina or silicon carbide. This class of composites is handicapped by the high cost of processing and raw materials and therefore only attractive for applications in astronautics and military aviation. Composite materials, bridging the gap between PMC and CMC, are manufactured by the use of polysiloxanes and basalt fibers. Such competitive free formable Hybrid-composites are capable for service temperatures up to 600 °C in oxidative atmosphere. In order to make the material attractive for series applications, manufacturing technologies like RTM, filament winding or warm pressing are employed.
Beside the improved thermal resistivity in comparison to reinforced polymers and light metals, a major benefit of SiOC composites is investigated in the field of friction materials. The excellent properties in wear resistance and a high coefficient of friction make it an interesting alternative to CFC and CMC.
CB-2:IL02 Polymer-derived Ceramic Nanocomposites
V. PROUST1, A. BALLESTERO1, J. ALAUZUN2, S. BERNARD1, P. MIELE1, 1Institut Européen des Membranes (IEM-UMR 5635) ENSCM/UM2/CNRS - CC047, Montpellier Cedex, France; 2Institut C. Gerhardt, CMOS, Université Montpellier 2 - CC1701, Montpellier Cedex, France
Nowdays, there is a trend toward more flexibility and an increased interest in smart and adaptive materials with the objective to meet most industrial specifications. Inherent difficulties to the traditional techniques for the formulation of ceramics can be overcome by the development of novel synthetic paths where chemistry, processing and material science are combined coupled. The relatively recent Precursor-Derived Ceramics (PDCs) concept is a chemical route which offers original and new preparation opportunities in ceramic science. Those precursors are molecular and polymeric compounds with a skeletal structure that includes atoms such as metals and metalloids. In general, they contain the basal structure of the desired ceramics as well as peripherical organic groups which offer functionalities. Here, we will describe in details the two strategies to develop polymer-derived ceramic (PDC) nanocomposites. In a first part, we will speak about the dispersion of nanofillers (active/passive) in polymer-derived ceramics and in the second strategy, we will describe a general route by which nanocrystals inclusions can be readily generated during the elaboration of the bulk PDC component. These materials will be prepared as monoliths and membranes and fully characterized.
CB-2:L04 Heat Exchange Filters of Silicon Oxycarbonitride Glasses
A. TAMAYO, M.A. MAZO, L. VIVANCO, J. RUBIO, F. RUBIO, Ceramics and Glass Institute, CSIC, Madrid, Spain
Volumetric receivers of Silicon-Silicon Carbide ceramic filters are used in solar thermal power plants to transfer the heat of concentrated solar radiation to a fluid flowing through the filters. The high amplitude of the temperature range causes premature failures due to local stresses associated to thermal expansion. Moreover, the limited resistance against oxidation of this kind of materials urges the necessity to look for new materials that overcome the mentioned drawbacks.
Sol-gel derived silicon oxycarbonitride (SiCNO) glasses have been obtained from hybrid materials made of silicon alkoxides and hexamethyldisilazane. The obtained mesoporous SiCNO glasses remain amorphous up to very high temperature without degradation of the glassy matrix. The structural characterization carried out by spectroscopic and diffraction techniques throw a dependence on the nanodomain structure with the chemical composition of the obtained material. It turned out that the carbon incorporated into the glass network, which is controlled by the stoichiometry of the selected precursors, plays an important role in the appearance of crystalline phases when the materials are treated in air. beneficial for the design of optimized solar volumetric receivers stable at the operating conditions.
CB-2:L05 Highly Porous Wollastonite-diopside and Wollastonite-apatite Ceramic Foams from Low Temperature Foaming and Reactive Ceramization of Silicone-based Mixtures
L. FIOCCO, E. BERNARDO, P. COLOMBO, Dipartimento di Ingegneria Industriale, University of Padova, Italy
A commercial liquid silicone resin, filled with inexpensive CaCO3 and Mg(OH)2 microparticles, has been successfully converted into highly porous wollastonite-diopside and wollastonite-apatite ceramic foams, by low temperature foaming, at only 350°C, and ceramization at 900-1100°C. In the first case, operating with CaCO3 and Mg(OH)2, extensive foaming and phase development were promoted by the use of borax microparticles as secondary, multifunctional filler. In fact, borax contributes to the foaming, owing to a significant water release at 350°C, and to ionic interdiffusion, by formation of a sodium-borate liquid phase, upon firing at 1100°C. In the second case, operating with only CaCO3 microparticles as main fillers, the foaming was due to the control of solvent release, addition of borax and/or specific foaming additive (DCH). The apatite phase was developed by application of a novel treatment, based on phosphatization of samples preceramized at 700°C and final firing at 900°C.
CB-2:IL06 Polymer-Derived Ceramic Nanocomposites: Preparative Concepts towards Tailor-Made Phase Compositions and Properties
E. IONESCU, Technische Universitaet Darmstadt, Darmstadt, Germany
Polymer-derived ceramic nanocomposites (PDC-NCs) have been addressed in the last two decades and were shown to possess intriguing properties which make them excellent candidates as structural and (multi)functional materials for applications at high-temperatures and under harsh environments.
PDC-NCs can be synthesized via polymer-to-ceramic conversion of suitable single-source precursors, leading in a first step to amorphous single-phase materials, which subsequently undergo phase separation and crystallization processes to furnish bi- or multi-phase ceramic nanocomposites.
In the present work, the conversion of the single-source precursors into ceramics as well as the subsequent phase separation and crystallization processes to furnish PDC-NCs will be addressed in detail. Special emphasis will be set on describing the intimate relationship between the molecular architecture of the single-source precursors and the phase composition/microstructure of the resulting PDC-NCs.
Additionally, preparative concepts for the knowledge-based design of PDC-NCs with tailored phase compositions and property profiles as well as selected prospective applications thereof will be highlighted and discussed.
CB-2:IL07 High-Temperature-Stable Ceramic Nanocomposites
R. RIEDEL, E. IONESCU, Technische Universität Darmstadt, Institute for Materials Science, Darmstadt, Germany
Nanocomposite materials can be defined as consisting of at least two Gibbsian phases, one of them being nanoscaled. This class of materials has received increased attention in the 80ies, due to the work of Gleiter on nanocrystalline materials, showing that by reducing the size of the components within the composite materials towards the nanoscale, an enormous improvement in their properties (e.g. mechanical, electrical, optical etc.) can be achieved.
In this work, single-source-precursor-based preparative techniques for the synthesis of Si M C N O-based ceramic nanocomposites (M = Zr, Hf) as well as their high-temperature behavior will be presented. The nanocomposites were prepared upon ceramization of suitable single-source precursors, i.e. metal-modified polycarbosilanes, polysiloxanes and polysilazanes. The precursor-to-ceramic conversion will be addressed, with emphasis on the effect of the precursor architecture on the phase composition and microstructure of the resulting nanocomposite. Selected physico-chemical properties of the nanocomposites, their behavior in harsh conditions (high temperatures, oxidative/corrosive environments, thermo-mechanical loading etc.) and prospective structural applications will be highlighted and discussed.
CB-2:IL08 Micro-Meso-Porous Si-based Polymer-derived Ceramics (PDC) for Functional Applications
G.D. SORARU, Department of Industrial Engineering, University of Trento, Trento, Italy
Polymer pyrolysis is a flexible processing route to prepare Si-based ceramics of the general SiOCN system. Due to their unusual nanostructure they have shown a variety of different functionalities ranging from high temperature semiconductivity, photo luminescence to high lithium storage capacity to mention just some of them. The combination of these unique properties with a micro-meso-porous structure can provide materials for various applications including high temperature chemical sensors, lithium batteries and supercapacitors. In our laboratory, micro-mesoporous Si-based PDC have been obtained using different strategies: (i) by HF etching a phase separated SiOC; (ii) by pyrolysis in inert atmosphere of sol-gel derived hybrid xerogels and aerogels and (iii) from polycarbosilane aerogels obtained by crosslinking, via hydrosilylation reaction, a Si-H containing polymer. Pyrolysis of the porous precursors in pure hydrogen atmosphere allows preparing, for the first time, transparent bulk mesoporous SiOCs with potentialities as optical sensors for a variety of organic vapours as well as proton detection. Conversely, pyrolyis in Ar atmosphere leads to porous Si-O-C-based materials which can be used as chemresistors or high capacity anodes for lithium ion batteries.
CB-2:L10 Micromolding of Polymer Derived Ceramics for MEMS Applications
J. GROSSENBACHER1, M.R. GULLO1, V. BAKUMOV2, G. BLUGAN2, K. JAKOB2, J. BRUGGER1, 1Microsystems Laboratory (LMIS1), EPFL, Lausanne, Switzerland; 2EMPA, Swiss Federal Labs for Materials Science and Technology, Lab. for High Performance Ceramics, Duebendorf, Switzerland
Recently much of effort has been invested into improving the efficiency of micromachining techniques with polymer-derived ceramics (PDC). However, there are still remaining challenges when it comes to fabricate fully released and crack free bulk ceramic parts with high dimensional accuracy, due to the high shrinkage rate (30% vol.) and the necessity of a supporting substrate.
To overcome these limitations we propose here a novel molding approach to cost-efficiently microfabricate releasable complex shaped parts with sub-micrometric features. We improved the following aspects: Firstly, we used PDMS as mold material, which facilitates the demolding due to its elasticity. Secondly, we designed a microfluidic network composed of filling pots and microchannels to fill the microstructures. A breaking notch at the MEMS/filling channel interfaces allows releasing the parts from the fluidic network. Finally the combination of a PDC repellent and PDC wetting layer increased the molding fidelity while facilitating the demolding. After a final sintering step we achieved dense ceramic micrometer samples with sub-micrometric details.
In the presentation more details on the fabrication process, wetting layer engineering as well as SEM and EDX characterization of the MEMS parts will be provided.
Session CB-3 - Microwave Processing
CB-3:IL01 Microwave Energy Application for Materials' Processing and Environmental Technology
N. YOSHIKAWA, Graduate School of Environmental Studies, Tohoku University, Sendai, Japan
Microwave heating was discovered more than 60 years ago. And nowadays, it became popular for domestic ovens. Microwave has also been utilized for the industrial processes, such as drying and roasting.
On the other hand, there have been many application of microwave being investigated for materials' processing and environmental technologies. They are attempted to take advantage of some specific characteristics of microwave heating which differs from conventional one. Rapid heating, internal heating, selective heating are the features to be taken into consideration. Moreover, so-called "non-thermal effect" is the additional feature for which researchers are particularly interested.
In this presentation, it is intended to introduce some selected topics of research projects performed in our group. They include researches on fabrication of some functional materials and on handling industrial wastes and so on. It is also intended to interpret the phenomena observed in these applications from the fundamental view points of material vs. electromagnetic wave interaction.
CB-3:L02 Hot Pressing Microwave Sintering of Oxides Ceramics
A. THUAULT1, R. HEUGUET1, F.-X. LEFEVRE1, E. SAVARY1, 2, S. MARINEL1, 1Laboratoire de Cristallographie et Sciences des Matériaux, Caen Cedex, France; 2Laboratoire des Matériaux Céramiques et Procédés Associés - Université de Valenciennes et du Hainaut-Cambrésis, Maubeuge, France
Microwave sintering is a very promising process permitting to obtain high dense ceramics materials (>99%) for short time heating treatments. For specific applications such as transparent ceramics and functional ceramics, ultra fine grain size combined with high density is required.
For that purpose, a hot pressing microwave device, which consists in a single mode microwave (2.45 GHz) cavity equipped with a uniaxial press, has been designed and used for sintering oxides materials.
Model oxide materials such as spinel, Al2O3 and ZnO were chosen to investigate the microwave sintering with and without applied pressure.
The influence of the sintering parameters (heating rate, sintering temperature, dwell time and applied pressure) on the sintered oxide materials has been investigated in order to understand the specific effects of the pressure on the microwave sintered pieces microstructure. This process could be successfully used to obtain dense sintered pieces with controlled microstructures.
CB-3:L04 Microwave Absorbency Change of Nitride Powders under Vacuum Heating
S. SANO1, S. TAKAYAMA2, A. KISHIMOTO3, 1National Institute of Advanced Industrial Science and Technology, Nagoya-city, Aichi, Japan; 2National Institute for Fusion Science, Toki-city, Gifu, Japan; 3Okayama University, Okayama-city, Okayama, Japan
To know microwave and millimeter-wave behaviors is important as a basis of developing microwave and millimeter-wave heating technology. For this purpose, we have measured microwave and millimeter-wave absorbency change of ceramics as a function of temperature, mainly oxide ceramics, and metal powders by using a measuring system consisting of a microwave network analyzer, a circular wave-guide fixture and a vacuum heating furnace. In this study, nitride powders were subjected to measurements. From obtained results, electrically insulating nitride powders showed similar behavior compared to insulating oxides and electrically conductive nitride powders showed similar behavior compared to metal powders.
CB-3:IL05 Metal Chalcogenide Nanoparticles derived from Molecular Precursors: Microwave Synthesis, Characterization and Electronic Performance
J.J. SCHNEIDER, S. SANCTIS, F. ROTH, M. NOWOTTNY, R.W. HOFFMANN, Technische Universität Darmstadt, Fachbereich Chemie, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Darmstadt, Germany
Metal chalcogenide (chalcogenides = O, S, Se) nanoparticles are interesting for their wide variety of potential material applications. Especially solution based molecular routes to such materials are promising since they allow an entry into flexible substrate deposition. One of our interests in that area is devoted to their intriguing electronic properties as transparent conducting oxides (TCO). Mono and mixed metal phase oxidic materials have found widespread interest and application as inorganic transparent ceramic materials e.g. for field effect transistors (FET) or transparent electrodes while those bearing late transition metals and heavier chalcogenides like sulfur or selenium show high potential as solar cell absorber materials. Their electronic and optical properties can thus be fine tuned from dielectric over semiconducting to conducting behaviour thus making them ideal materials for printed electronics. Moreover in combination with biological structures such as DNA or tobacco mosaic virus (TMV) their intrinsic electronic properties in such hybrid materials are unique. In this lecture we will give an overview of our current achievements in the above mentioned area as well as the future research challenges lining up in front of us.
CB-3:L06 Single Mode Microwave Sintering of Alumina at 2450 and 915 MHz with a View of Scaling up Size Samples
R. HEUGUET1, A. THUAULT1, E. SAVARY2, F.-X. LEFEVRE1, S. MARINEL1, 1Laboratoire de Cristallographie et Sciences des Matériaux, Caen Cedex, France; 2Laboratoire des Matériaux Céramiques et Procédés Associés - Université de Valenciennes et du Hainaut-Cambrésis, Maubeuge, France
Alumina is a widespread oxide used in many applications, including functional or structural applications. This is probably one of the most investigated oxide material when studying fundamental of sintering either in conventional or unconventional processes. Recently, it has been shown that, using appropriate assembly consisting of a zirconia based insulator-susceptor, combined with an alumino-silicate fiber based insulator material, the 2.45 GHz single mode microwave sintering of alumina can be very well controlled. This means the grain size and the temperature distribution within the sample to be homogeneous and that the final microstructure can be tailored to many applications, while drastically lowering the overall time needed for material processing. However, the sample size being heat treated at 2.45 GHz is quite low (maximum diameter~40 mm) and, in a view of scaling up the dimension of the pieces, a single mode applicator working at 915 MHz was used. Up to now, very few works reported the use of such a cavity and frequency for sintering ceramics. The aim of this communication is to go through this scaling-up, in deeply investigating the effects of the frequency change on the microwave sintering of alumina. The temperature distribution and sample microstructure will be discussed.
CB-3:L07 Rapid Microwave (MW) Synthesis of Group 13 Carbides
J.L. KENNEDY1, 2, T.D. DRYSDALE1, D.H. GREGORY2, 1Dept of Electrical Engineering, University of Glasgow, Glasgow, UK; 2Dept. of Chemistry, University of Glasgow, Glasgow, UK
The group 13 carbides display a fascinating breadth of properties. Aluminium carbide is an intriguing material which can exert a strong influence over both the structural and mechanical properties of any material it interacts with. Al4C3 is often produced as an unwanted consequence of an industrial process but also finds application in its own right for example, in field-emission applications. Boron carbide is widely-used, finding applications as an abrasive, in wear-resistant parts, as a lightweight armour and as an absorbent in the nuclear industry. These applications are a result of its excellent mechanical and thermal properties.
Our previous work has shown that synthesis and processing times of structural and functional ceramics can be cut by orders of magnitude by switching from conventional to microwave heating processes. Here we demonstrate that it is possible to prepare Al4C3 and B4C in 30 min using a multimode MW cavity. Materials are characterised by powder neutron diffraction (PND), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric-differential thermal analysis (TG-DTA). Variable temperature PND data have been collected to probe stoichiometry and structural changes at elevated temperatures.
CB-3:L08 Influence of the Frequency and Applicator Type on Hydroxyapatite Microwave Sintering
E. SAVARY1, 2, A. THUAULT2, J.-C. HORNEZ1, M. DESCAMPS1, S. MARINEL2, A. LERICHE1, 1Laboratoire des Matériaux Céramiques et Procédés Associés - Université de Valenciennes et du Hainaut-Cambrésis, Maubeuge, France; 2Laboratoire de Cristallographie et Sciences des Matériaux, Caen Cedex, France
Hydroxyapatite (HA) is a well-known material for bone substitution applications. However, its low mechanical properties limit its structural applications. An interesting way to improve the mechanical resistance of those bioceramics consists in obtaining dense samples with fine microstructures. In this aim, microwave heating process represents a promising method due to the very short thermal treatment times usually reported. The main purpose of this study consists in investigating the sintering of HA materials using different microwave sintering processes: 2.45GHz single mode and multimode, 915MHz single mode and 2.45GHz single mode microwave hot pressing. Almost full dense samples with fine microstructures (submicronic) and improved mechanical properties are successfully obtained in less than 15 minutes of irradiation in 2.45GHz single mode cavity. Then, 2.45GHz multimode cavity and 915MHz single mode applicator allow increasing the dimensions of the sintered pieces (higher than 40mm diameter) close to the ones required for medical implants while keeping the high mechanical properties. Finally, the results obtained using microwave hot pressing at 2.45GHz are also deeply discussed in terms of density and grain refinement.
Session CB-4 - Spark Plasma and Flash Sintering
CB-4:IL01 Preparation of Ceramics by SPS Reactive Sintering: Success and Difficulties
F. BERNARD, S. LE GALLET, Laboratoire Interdisciplinaire Carnot de Bourgogne (UMR 6303 CNRS), Dijon, France
The main objective of many groups is to control Spark Plasma Sintering process that allows to sinter, to assemble, and to synthesize different kind of materials. Nevertheless, it is known how difficult it is to form completely a compound from numerous reactant species, making the formation of compounds by reactive sintering hazardous. The homogeneity of reactant powder mixture, which depends on the grain size, the grain size difference between the species and the species concentration, is indeed decisive to achieve full reaction progress. Despite these difficulties, reactive sintering gives rise to interest because it can be a powerful and cost effective method to obtain dense ceramics such as BCZY, carbides such as HfC and ZrC with finer microstructure, highly porous ceramics such as ZrB2, even transparent ceramics such as Lu3NbO7.With its experience in the SPS reactive sintering of intermetallic compounds, the laboratory ICB is interested in the reactive sintering of ceramics such as iodoapatite and silicon carbide. These two systems have in common the apparition of a liquid phase during the sintering. From these examples, the possibilities offered by the SPS technique to perform reactive sintering will be discussed including success and difficulties as well.
CB-4:IL02 Microstructure and Mechanical Properties of WC-FeAl Composites Fabricated by Pulse Current Sintering
R. FURUSHIMA, A. MATSUMOTO, K. KATOU, K. SHIMOJIMA, H. HOSOKAWA, National Institute of Advanced Industrial Science and Technology, Nagoya, Japan
Spark plasma sintering (SPS) technique is useful to densify ceramic-metal composites as well as hard-to-sinter ceramic materials. Here, we show the case where dense WC-FeAl composites as one of the ceramic-metal ones are successfully obtained from a conventional powder metallurgical process followed by the SPS technique. In the WC-FeAl composites, suppression of grain growth during the sintering is significantly important to improve the mechanical properties such as the hardness and the transverse rupture strength (TRS). The SPS technique gives an advantage of suppressing the grain growth during the sintering due to the rapid heating speed. Compressive stress applied to powders promotes the densification of the compact. From the above two advantages, the sintered WC-FeAl composites produced by SPS technique has better mechanical properties than those prepared from a conventional vacuum sintering. We also show the various parameters on the powder characteristics which influence the mechanical properties of the WC-FeAl composites sintered by the SPS technique.
CB-4:L04 New Developments for Suitable FAST/SPS Tool Materials
J. RAETHEL, M. HERRMANN Fraunhofer IKTS, Dresden, Germany; J. HENNICKE, FCT Systeme GmbH, Rauenstein, Frankenblick, Germany
Since FAST/SPS technology ensures a sufficient and fast consolidation of different materials the need for suitable tool material is rising, too. Graphite based materials are widely used and well known as FAST/SPS tool material but it also offers a few unwanted or weak properties for example a possible reaction or reduction of sample material as well as low mechanical values compared to other usable tool materials.
An approach for the FAST/SPS consolidation of Al2O3 and TiB2 based cutting tool inserts in newly developed FAST/SPS tool materials as well as a general strategy for further FAST/SPS tool material development will be presented.
CB-4:IL05 Spark Plasma Sintering of Multilayer Ceramics
C. ESTOURNES1, M. BOIDOT1, S. SELEZNEFF1, P. AUDIGIÉ1, D. OQUAB1, D. MONCEAU1, M. MAGLIONE2, C. ELISSALDE2, 1Institut Carnot CIRIMAT Toulouse Cedex, France; 2CNRS, Univ. Bordeaux, ICMCB, UPR 9048, Pessac, France
PECS techniques have known a huge development over the last two decades. In particular, SPS is an extremely powerful technique to sinter all classes of materials (metals, ceramics and polymers) as well as their composites. Thanks to the increase in sintering kinetics it allows, its field of activity also extends to the synthesis, to the assembly, and to the preparation of new materials (nanocomposites, multimaterials, nanoceramics) or graded materials (in composition, microstructure, porosity). Due to the lower temperature and the shorter durations achieved during SPS, interdiffusion or reaction between two adjacent materials can be limited, favoured or controlled. The potentialities of this technique to design new materials or architectures will be illustrated through few examples:
i) 2D, 3D and core/shell architectures have been prepared by SPS to obtain ferroelectric with modulated properties.
ii) Complete Thermal Barrier Coatings were obtained in a single short production step. Large range of coating compositions was fabricated and their oxidation kinetics were evaluated using of thermal cycling.
iii) All solid batteries developed by SPS, associating cathode/electrolyte/anode in a single step with relatively clean interfaces, exhibit very promising performances.
CB-4:L06 Ultra-Rapid Spark-Plasma Sintering of SiC powder
E. OLEVSKY, S. ROLFING, A. ILYINA, San Diego State University, CA, USA; Moscow Engineering Physics University, Russia
A method for conducting flash spark plasma sintering (SPS) type experiments with an industrial SPS device is developed. The effectiveness of this technique is studied for consolidation of SiC powder.
Specially constructed dies are designed to heat the pre-compacted SiC powder specimens to a critical temperature before applying any voltage to the specimens. The dies incorporating a sacrificial metal bushing heat the specimen allowing the electrode-punch of the SPS device setup to contact the specimen and pass current through it under elevated temperatures. The temperature at which the electrode contacts the specimen can be controlled by changing the material and the design of the bushing.
The experimental results demonstrate that flash sintering phenomena can be studied using conventional SPS devices. The role of the thermal runaway phenomena for material processing by flash sintering is theoretically analyzed. It is shown that the thermal runaway may affect the scalability of the powder consolidation.
CB-4:L08 Porosity Evolution under Spark Plasma Sinter-Forging
E.V. ALEKSANDROVA1, E.A. OLEVSKY2, 1, A.M. ILYINA1, E.G GRIGORYEV1, 1Engineering Physics University, Moscow, Russia; 2San Diego State University, San Diego, CA, USA
The constitutive modeling of hot deformation processing of a porous material is refined based on the outcomes of spark-plasma sinter-forging (SPSF) tests. The continuum theory of sintering is used for the analysis of the shrinkage kinetics of the electric current-insulated SPSF of a cylindrical powder specimen. Macro scale simulation of the electric-current insulated SPSF is carried out using finite element analyses. The calculation results are compared with the experimental data on the volume shrinkage and porosity evolution during SPSF of copper porous specimens. The conducted research provides a basis for further assessments of the contributions of field effects to the deformation behavior of powder materials subjected to spark-plasma sintering.
CB-4:L09 Dynamic Grain Growth during Spark Plasma Sintering of Transparent Alumina
BYUNG-NAM KIM, K. MORITA, H. YOSHIDA, Y. SAKKA, K. HIRAGA, National Institute for Materials Science, Tsukuba, Japan
During spark plasma sintering of alumina, the effects of heating rate, pressure and loading schedule on the grain size are examined. When the alumina is densified at low temperatures, high heating rates accelerate grain growth, though the total heating time is reduced. The densification during sintering includes the deformation of powder particles, which occurs mainly by grain-boundary sliding. The defects generated during grain-boundary sliding may enhance the grain-boundary mobility and accelerate the grain growth rate, that is the dynamic grain growth. It is considered, therefore, that the high deformation rate at high heating rates accelerates grain growth. The accelerated grain growth also appears in high-pressure sintering. The grain size after sintering increases with the applied pressure. High pressures lower the deformation temperature and increase the deformation rate. As a result, the high deformation rate during heating may generate defects and enhance the grain-boundary mobility. Lastly, the loading schedule during heating also affects the deformation and grain growth. Applying pressure at low temperatures may generate more defects and resultant acceleration of grain growth.
CB-4:L10 Low Temperature Densification of Tin Dioxide by Flash Sintering
R. MUCCILLO, E.N.S. MUCCILLO, Center of Science and Technology of Materials Energy and Nuclear Research Institute S. Paulo, SP, Brazil
Tin dioxide, which requires sintering aids to reach densification, has been exposed to ac electric fields in the 900-1300 C range. The electric fields produced current pulses leading to flash sintering, monitored by an experimental arrangement consisting of a vertical dilatometer with Pt terminal leads connected either to an ac power supply or to an impedance analyzer. The data collected were the linear shrinkage as a function of the temperature, the electric voltage and the electric current as a function of time, and impedance plots before and after flash sintering. The results show that the higher is the electric current through the samples, the higher is the delivered Joule heating, and consequently the larger is the attained shrinkage and the bulk density. Moreover, an important parameter for the homogeneity of the flash sintered pellet is its thickness-to-diameter ratio, because the electric current path depends on the distribution of the electric field in the bulk of the pellet. FEG-SEM observation of fracture surfaces shows that the current pulses promote grain growth, which is dependent on the electric current pulse. Moreover, the ceramic particles (or grains) stick together, a phenomenon typical of flash grain welding. Densities of 95% TD were achieved at 1100 C.
CB-4:L11 Iodate-substituted Hydroxyapatite Sintering at Low Temperature by SPS
A. COULON, L. CAMPAYO, A. GRANDJEAN, Commissariat a l'energie atomique et aux energies alternatives-Centre de Marcoule, Bagnols-sur-Ceze, France; D. LAURENCIN, Institut Charles Gerhardt de Montpellier, Montpellier, France; S. Le Gallet, Laboratoire Interdisciplinaire Carnot de Bourgogne, Dijon, France; S. ROSSIGNOL, Groupe d'Etude des Matériaux Hétérogenes, Limoges, France
In order to avoid the release of iodine 129 (long-lived intermediate-level waste) in the environment, strategies have been developed to incorporate iodine in dense durable host matrices intended to be stored in deep geological repositories. Previous studies demonstrated the feasibility of obtaining an iodate-substituted hydroxyapatite (HA-CaI) powder by a wet-precipitation route. This apatite thus requires a shaping to produce a dense ceramic. In this work, sintering of HA-CaI powder at low temperature (T<400°C) by spark plasma sintering (SPS) was carried out. This consolidation was only possible if a hydrated layer was present at the surface of apatite crystals. Infrared spectroscopy was performed to determine the proportion of hydrated layer. The relative density of sintered ceramics was determined by hydrostatic weighing. Results show that the higher the proportion of hydrated layer, the better the uniaxial cold compaction and densification during sintering. A high pressure and a slow heating rate allowed a relative density above 80% to be reached. The structure of HA-CaI was retained during sintering as characterized by X ray diffraction and Raman spectroscopy, and no loss of iodine was observed.
CB-4:L13 Effect of Carbon Contamination on Transparent MgAl2O4 Spinel during SPS Processing
K. MORITA1, B.-N. KIM1, H. YOSHIDA1, K. HIRAGA2, Y. SAKKA1, 1Advanced Ceramics Group, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, Japan; 2Materials Science and Engineering, Kitami Institute of Technology, Kitami, Hokkaido, Japan
Spark-plasma-sintering (SPS) technique has succeeded to fabricate transparent ceramics. For MgAl2O4 spinel, however, the transmission tends to be lower in SPS technique than in HIP techniques. The limited transmission is likely to be related to discoloration after SPS processing. Although the discoloration has generally been ascribed to trace carbon contamination and oxygen vacancies formed under the vacuum condition, the reason remains unclear. The present study was therefore performed to discuss the effects of both trace impurities and oxygen vacancies on the transmission.
The in-line transmission Tin of spinel can be improved with decreasing heating rate α; Tin in visible range increases from »0% for α = 100°C/min to »50% for α = 10°C/min. Raman spectra of the SPSed spinel clearly reveals two broad peaks at around 1350 cm-1 and 1600 cm-1, which are related to the D- and G-bands arising from glassy carbon, respectively. The carbon peak becomes sharp and larger with increasing α. In addition, the peak positions shift with α and take the same values to those of the carbon paper and the graphite die used in the SPS processing. This suggests that the carbon contamination is enhanced with α during SPS processing and would cause light scattering and/or absorption.
Session CB-5 - Bio-inspired Processing
CB-5:IL01 Generation of Inorganic Functional Materials by Molecular Bionics
J. BILL, Institute for Materials Science, University of Stuttgart, Stuttgart, Germany
Nature provides a variety of biominerals with outstanding functional properties. Layered structures found e. g. in nacre or fiber-based materials, like bones or the spicules of deep sea sponges exhibit exceptional mechanical and optical performance. Such architectures represent promising models for the design of multifunctional inorganic materials. In addition, the formation mechanisms of biominerals, which are governed by self-assembly processes and are directed by bioorganic templates, provide paradigms for the in vitro and in vivo synthesis of inorganic functional materials at ambient conditions.
Molecular bionics aims to apply the principles of biomineralization processes for the generation of complex-structured multifunctional inorganic materials. Within the scope of this contribution (bio)organic composites containing oxides of elements like zinc, titanium or vanadium by molecular bionics are discussed. Both the synthesis and the structure as well as the electrical and mechanical properties of the obtained materials are considered.
CB-5:IL02 Characterization and Simulation of Bioinspired Optical Ceramics Templated from Lepidopteran Wings
WANG ZHANG, WANLING WANG, JIAJUN GU, QINGLEI LIU, DI ZHANG, State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, China
Recently, an increasing number of researchers have directed their attention to the wings of lepidopterans (butterflies and moths) because of their dazzling colors. According to one previous study, these iridescent colors are caused by periodic structures on the scales that make up the surfaces of these wings. These materials have recently become a focus of multidiscipline research because of their promising applications in the display of structural colors, advanced sensors, and solar cells. This work will provide a broad overview of the research into these wings. Specifically, the review focuses on characterization and simulation of bioinspired optical materials templated from lepidopteran wings scales.
CB-5:IL03 Biomimetic Approach to Design Collagen/Apatite Composites for Tissue Engineering and Biomimeralization Studies
YAN WANG, S. VON EUW, M. ROBIN, F. BABONNEAU, M.-M. GIRAUD-GUILLE, T. AZAIS, N. NASSIF, LCMCP-UMR7574-CNRS-UPMC, Paris, France
We will show that a process based on a "one-pot" co-precipitation method, coupling the liquid-crystalline properties of collagen to a hydroxyapatite mineralization process, leads to the synthesis of a collagen/apatite composite with high similarities with the bone tissue in terms of composition and structure.
From the organic point of view, the hierarchical structure i.e. level 4 described in the literature, and the mechanical anisotropy of bone are reproduced. From a mineral point of view, the structure of the synthetic platelets and their related behavior in water mimic the biological one.
This work affirms the importance of physico-chemical processes occurring in biomineralization, as usually discussed from a biological control point of view.
We will show that the resulting material provides original models to study fundamental questions on bone biomineralization .It represents a good starting point for applications in bone tissue engineering and for the design of new implantable materials since autologous bone is still considered as the gold standard.
CB-5:L04 Hydroxyapatite Interfacial Growth Inspired by Marine Mussel Adhesion
HAESHIN LEE, Department of Chemistry Director, Center for Nature-inspired Technology Korea, Advanced Institute of Science and Technology (KAIST) Daejeon, South Korea
In this presentation, a universal biomineralization route, called polydopamine-assisted hydroxyapatite formation (pHAF), that can be applied to virtually any type and morphology of scaffold materials is demonstrated. Inspired by the adhesion mechanism of mussels, the pHAF method can readily integrate hydroxyapatites on ceramics, noble metals, semiconductors, and synthetic polymers, irrespective of their size and morphology (e.g., porosity and shape). Surface-anchored catecholamine moieties in polydopamine enriches the interface with calcium ions, facilitating the formation of hydroxyapatite crystals that are aligned to the c-axes, parallel to the polydopamine layer as observed in natural hydroxyapatites in mineralized tissues. This universal surface biomineralization can be an innovative foundation for future tissue engineering.
CB-5:IL05 Sustainable Biotemplated Porous Ceramics for Biomedical and Environmental Remediation
L. TRECCANI, Advanced Ceramics, University of Bremen, Bremen, Germany
Due to their properties such as high surface area, permeability, temperature, mechanical and chemical stability, porous ceramics are highly attractive for a variety of technological systems including filters, bioreactors and bone substitutes. Fundamental for fabrication of high-performance porous ceramic membranes is a straightforward processing method enabling the simultaneous and precise control of different parameters, including material porosity, pore size and structure, which are critical for improving overall material performance.
In this talk two sustainable routes using biomolecules for obtaining porous ceramics with tailorable properties are presented. First, an ionotropic gelation route using biopolymers as template is shown for creating porous microbeads, monoliths and multilayered membranes with adjustable morphology, specific surface area and pore size, which can be used for filtration, and remediation purposes. Second, a freeze gelation-based one-pot process employing proteins to control scaffold microstructure, porosity and mechanical stability is shown. This method enables the fabrication of biocompatible, near-net, customisable, complex-shaped porous scaffolds for potential use as biodegradable bone substitutes and versatile platform for local drug delivery.
CB-5:IL06 Novel Functional Hierarchical Materials Bioinspired from Nature Microstructures
DI ZHANG, WANG ZHANG, JIAJUN GU, SHENMING ZHU, HUILAN SU, QINGLEI LIU, State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, China
Biological materials naturally display an astonishing variety of sophisticated nanostructures that are difficult to obtain even with the most technologically advanced synthetic methodologies. Inspired from nature materials with hierarchical structures, many functional materials are developed based on the templating synthesis method. This review will introduce the way to fabricate novel functional materials based on nature bio-structures with a great diversity of morphologies, in State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University in near five years. We focused on replicating the morphological characteristics and the functionality of a biological species (e.g. wood, agriculture castoff, butterfly wings). We change their original components into our desired materials with original morphologies faithfully kept. Properties of the obtained materials are studied in details. Based on these results, we discuss the possibility of using these materials in photonic control, solar cells, electromagnetic shielding, energy harvesting, and gas sensitive devices, et al. In addition, the fabrication method could be applied to other nature substrate template and inorganic systems that could eventually lead to the production of optical, magnetic, or electric devices or component.
CB-5:L07 (Bio)Materials Alchemy: Chemical Transformation of Bio-organic and Bio-inorganic 3-D Hierarchical Structures into 3-D Replicas of New (Non-Biogenic) Functional Inorganic Materials
K.H. SANDHAGE, S.C. DAVIS, W.B. GOODWIN, C.G. CAMERON, Y. FANG, Y. CAI, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA; J.P. VERNON, J.D. BERRIGAN, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA; I.J. GOMEZ, J.C. MEREDITH, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA; J. AIZENBERG, M. KOLLE, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA; A. LETHBRIDGE, P. VUKUSIC, School of Physics, University of Exeter, Exeter, UK
Remarkable examples of the biological assembly, under gentle ambient conditions, of intricate three-dimensional (3-D) rigid organic and/or inorganic materials in complex, yet well-controlled, hierarchical (micro-to-nanoscale) patterns can be found throughout nature. However, the range of inorganic chemistries assembled by living organisms is quite limited. Man-made processes provide a far more extensive range of functional inorganic chemistries, although often not with the 3-D hierarchy or gentle processing conditions achieved via biological routes. The fabrication of structures with complex 3-D hierarchical morphologies and with a wide range of tailorable inorganic chemistries may be accomplished by combining biology with synthetic inorganic chemistry; that is, structures with a desired 3-D morphology may first be biologically assembled and then transformed via a morphology-preserving synthetic process into a new functional inorganic chemistry. In this presentation, several shape-preserving strategies (coating-based and fluid/solid reaction-based) will be illustrated for converting bio-organic and bio-inorganic structures into 3-D replicas comprised of new (non-biogenic) functional inorganic materials for catalytic, optical, electromagnetic, and other applications.
Session CB-6 - Solid Freeform Fabrication
CB-6:L01 Lithography-based Ceramic Manufacturing: A Novel Technique for Additive Manufacturing of High-Performance Ceramics
M. SCHWENTENWEIN, J. HOMA, Lithoz GmbH, Vienna, Austria
In this paper the recently introduced AM-technology Lithography-based Ceramic Manufacturing (LCM) is presented. This technique is based on the selective curing of a photosensitive slurry by a mask exposure process which generates a photopolymer matrix that temporarily acts as scaffold and binder for the ceramic particles. In analogy to conventional binder systems, the polymer matrix is later on removed at elevated temperatures to give the dense ceramic structure. LCM gives rise to high green densities and thus, enables the production of strong, dense and accurate ceramic parts without any constrictions by geometrical limitations. Materials that could already be structured successfully include alumina, zirconia, tricalciumphosphate or silica. In the sintered state, the parts produced by this technology show very similar mechanical properties as classical formed ceramics; for alumina a theoretical density of over 99.3 % and 4-point bending strength of over 430 MPa has already been realized. These characteristics are perfectly acceptable for the use of such compounds as functional parts in numerous areas of application. This makes the LCM-process an innovative and capable production method, especially for complex shaped structures, customized parts or small series production.
CB-6:L03 Three Dimensional Printing of Calcia-based Ceramic Core Composites
HUOPING ZHAO, C.S. YE, Z.T. FAN, State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan, P.R. China
Three-dimensional printing has been used as a rapid freeform fabrication process to fabricate a wider range of green ceramic components with complex structures difficult to obtain using traditional ceramic fabrication process. In this study, calcia-based ceramic core composites were fabricated by three dimensional printing and sintering operation. The green bodies were printed using a CaO/TiO2 powder mixture as a precursor material and ethylene glycol as a binder. They were sintered at 1400-1500 °C for 2 h. The phases and microstructures of these samples were characterized by X-ray diffraction and scanning electron microscopy. The effect of TiO2 content and the sintering temperature on the density, hydration resistance and bending strength of the sintered bodies was investigated. It was found that increment of TiO2 content and sintering temperature would result in an increase of density of the sintered bodies and then increase of hydration resistance and bending strength.
CB-6:L04 Deposition and Drying of Inkjet Printed Dielectric Layers: Understanding and Optimization
M. SINGLARD, M. LEJEUNE, A. AIMABLE, A. VIDECOQ, SPCTS laboratory, Limoges, France; C. Dossou-Yovo, E. Beaudrouet, CERADROP, Limoges, France
Multilayer thick film hybrid circuits are traditionally fabricated by screen printing where the dielectric and metallic layers are successively deposited on a substrate with intermediate sintering steps. The European project Sprintronics aims to develop a new technology for the manufacturing of thick film hybrid circuits by inkjet printing (IJP) to improve (i) the definition of the micro-circuits by using very fine nozzle aperture, (ii) the complexity of the configuration via CAD file and (iii) cost efficiency as IJP is an additive method without tools. The layers quality is controlled by the ink formulation, the ejection and deposition parameters and the drying conditions. The optimization of the drying step is crucial for the success of the project in terms of compacity and topography of the layers.
This work presents a study on the drying of inkjet printed ceramic layers. The influence of the ejection parameters (droplet size, velocity and spreading related to electrical waveform and ejection frequency), deposition parameters (overlapping, splat lattice) and drying parameters (heating power and time, filling strategy thanks to infrared unit and CAD) is studied. Layers are characterized in terms of droplet spreading, drying uniformity, microcracking and topography.
CB-6:L05 3D-Printing of Bioactive Glass-Ceramic Scaffolds from Preceramic Polymers and Fillers
H. ELSAYED1, A. ZOCCA1, E. BERNARDO1, C.M. GOMES2, J. GÜNSTER2, P. COLOMBO1, 3, 1Dipartimento di Ingegneria Industriale, University of Padova, Padova, Italy; 2Division of Ceramic Processing and Biomaterials, BAM Federal Institute for Materials Research and Testing, Berlin, Germany; 3Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA
Wollastonite/Apatite bioactive glass-ceramics were fabricated by mixing a silicone resin preceramic polymer containing calcium carbonate as a filler (yielding wollastonite) with bioactive glass powder in the system (SiO2-CaO-P2O5-K2O-Na2O- MgO-CaF2). The crystallization kinetics of the resulting glass-ceramics was investigated using DTA, XRD and SEM techniques. Zn-containing silicates were also developed either by adding Zn oxide directly to the powder glass undergoing sinter-crystallization, or by embedding it in the preceramic polymer. Hardystonite (Ca2ZnSi2O7) and willemite (Zinc silicate) formed upon heat treatment, which modify the biological response of the Wollastonite/Apatite glass-ceramics.
This approach enables the fabrication of scaffolds via 3D printing techniques. A complete physicochemical, microstructural and mechanical characterization of the produced bioceramic, as well as degradation and in vitro assays, will be presented.
Session CB-7 - Other Non Traditional or Novel Routes
CB-7:IL01 New Materials Processing under Strong Gravitational Field
T. MASHIMO, Institute of Pulsed Power Science, Kumamoto University, Kumamoto, Japan
A strong gravitational field causes the displacement and sedimentation of atoms in solids, by which we can change the crystalline state and composition, respectively, in multicomponent condensed matter, although a microgravity field has been used to suppress the effects of gravity. We presented a self-consistent diffusion equation for sedimentation of atoms in condensed matter. We have developed a high-temperature ultracentrifuge to generate a strong acceleration field of even over 1 million (1x106) G, and, for the first time, succeeded in realizing the sedimentation of the constitutive solute atoms in a solid alloy. Various kinds of alloys, compounds and polymers have been investigated under a strong gravitational field, and the composition change, graded structure, chemical reaction, etc. have been achieved. We have also realized the sedimentation of isotope atoms and doping of impurity in semiconductor. Furthermore, we recently succeeded in realizing gravity-induced structure changes of some compounds due to displacement of atoms, which enable us to synthesize new crystal structures by using strong gravity. It is expected that strong gravitational field will be used as an atomic-scale materials processing to control compositions, nanostructure and impurities, and also to synthesize new materials. In this talk, the basics of strong gravity science are reviewed, and recent progress and future prospects for materials processing are described.
CB-7:IL02 Multifunctional Nanofibers: New Methods for Synthesizing Composites on a Fiber
J.D. STARR, M.A.K. BUDI, J.S. ANDREW, University of Florida, Gainesville, FL, USA
Multiferroic materials hold enormous potential for a variety of applications, including tunable microelectronics and multiphase memory. The development of novel complex oxide-based composite materials provides an opportunity to fabricate multiferroic materials with performance suitable for real-world applications. In composite multiferroics, the resultant magnetoelectric effect arises from coupling at the interface between a piezoelectric and a magnetostrictive phase. Therefore, it is desirable to assemble a composite such that the interfacial contact area between each phase is maximized for increased performance. Here, we present the first example of composite nanostructured building block with a Janus-type morphology for multiferroic applications. This composite is composed piezoelectric BaTiO3 and magnetostrictive CoFe2O4 in an architecture that simultaneously provides access to the bulk and surface properties of both phases. These Janus-type fibers combine the large contact area of a core-shell fiber with the segmented ordering of a thin film, and allow for the control of both composition and surface anisotropy, providing additional degrees of freedom in the design of composite materials.
CB-7:L03 Anisotropic Property and Nanostructure of Phosphate Glass
S. ITO, S. INABA, H. HOSONO, J. ENDO, Tokyo Institute of Technology, Yokohama, Japan
Glass is generally known to have a disordered isotropic structure, although some glasses have anisotropic structures showing birefringence when their structures are frozen under stress. We investigated the relation between anisotropic property and structure of alkali metaphosphate glasses in the system of (Li, Na, K, Cs)2O-P2O5. Thin rod-like samples of 0.05-0.5 mm in diameter were prepared by being drawn directly from melt at near glass transition temperature and cooled to room temperature under tensile stress. We found that multi alkali metaphosphate (Li, Na, K, Cs)PO3 glasses had highly oriented P-O-P chain structure and showed unique anisotropic behaviours compared to single alkali metaphosphate glasses, LiPO3 or NaPO3. The former type metaphosphate glass showed a large birefringence comparable to quartz crystal and a drastic change of mechanical properties with birefringence. The anisotropic glass showed also a huge lengthwise shrinkage of about 35 % without volume change, when it was heat-treated and its anisotropy disappeared. Those unusual anisotropic properties will be discussed in terms of the chain structure in glass.
CB-7:IL05 Femtosecond Laser Shock Processing of Solids and its Dynamics
T. SANO, A. HIROSE, Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, Osaka, Japan
Femtosecond laser ablation of solids drives shock wave resulting in highly-compressed state of the solids. The shock wave is generated by the recoil force during the plasma expansion induced by the femtosecond laser ablation of solids, followed by the propagation into the solids. The peak pressure reaches more than 100 GPa depending on the conditions. One of the most distinctive phenomena in the femtosecond laser-driven shocked materials is the quenching of high-pressure phases. Although the clear mechanism is still open, we suggest the ultrafast compression of the femtosecond laser-driven shock wave would cause the unique phenomena. Increase of the density of lattice defects such as dislocation and stacking faults and grain refinement are induced by the ultrafast deformation, followed by structure transitions. Nonequilibrium state of these structures would play an important role to retain these unique structures to the ambient pressure. The quenching of high-pressure phases of Fe and Si and hardening of Fe and Al using femtosecond laser-driven shock wave will be addressed in the talk. In-situ observation of femtosecond laser-shocked state will also be introduced.
CB-7:L07 Strong-gravity Experiments on Perovkite-type Oxides
M. TOKUDA1, Y. OGATA1, K.J. ISRAM1, A. YOSHIASA2, T. NISHIYAMA2, T. MASHIMO1, 1Institute of Pulsed Power Science, Kumamoto University, Kumamoto, Japan; 2Faculty of Science, Kumamoto University, Kumamoto, Japan
A strong gravitational field causes the displacement and sedimentation of atoms in solids, by which we can change the crystalline state and composition, respectively, in multicomponent condensed matter, although a microgravity field has been used to suppress the effect of gravity. Perovskite-type doped manganite, La1-xSrxMnO3 (LSMO) has unique magnetoresistance effect which is called "colossal magnetoresistance (CMR)". The CMR effect of LSMO is related to a Mn-O-Mn bond angle, which can be controlled by replacement of R (R = La, Nd etc.) site. It's expected that the strong gravity can induce by change the bond angle.In this study, we performed a strong gravity experiment on the LSMO single crystals and investigated the crystal structure and physical properties. It was found that the magnetic moment increased a little, and the Raman spectra showed appearance of a new raman peak in gravity experimental sample. The crystal structure analysis is now under study. The detailed result are presented.
CB-7:L08 Effect of Grain Size Distribution and Pressure on the Microstructure of Polycrystalline Diamond
J. WESTRAADT1, Centre for HRTEM, NMMU, Port Elizabeth, South Africa; W. MATIZAMHUKA, Diamond Research Laboratories, Element Six, Springs, South Africa; C. MASILELA, I. SIGALAS, CoE Strong Materials, WITS, Johannesburg, South Africa
Polycrystalline diamond (PCD) consists of micron sized diamond particles that are bonded together using a high-pressure (5.5GPa) and high-temperature (1450ºC) process in the presence of a cobalt sintering aid. Due to its exceptional mechanical properties this material finds extensive use in the abrasives industry as cutting, milling and drilling tools. PCD however suffers from thermal instability when the material is exposed to high temperatures. Previous studies indicate that the cobalt matrix is responsible for the thermal instability. In this study we investigated the effect of sintering pressure and grain size distribution on the final sintered microstructure. Diamond mixes consisting of successively finer particles (30µm, 4µm, 0.5µm and 50nm) were prepared and sintered using pressures of 5.5GPa, 6.8GPa and 7.7GPa. The resulting sintered materials were sectioned polished and investigated with scanning electron microscopy and image analysis to determine the diamond content. The diamond content increased as a function of pressure for all the diamond mixes. Addition of diamond particles 0.5µm and 50nm in size did not improve the sintered density of the final diamond compact.It was shown that the sub-micron particles graphitise during the powder preparation steps before sintering.
CB-7:L11 Development of Nanostructured Inorganic Binder for Ecofriendly Ceramic Processing
H.N. YOSHIMURA, M.B. LIMA, Universidade Federal do ABC, Santo André, SP, Brazil
This study was conducted to check the possibility of incorporating an inorganic binder in-situ during the ceramic processing of alumina powders for the reduction of organic binders, which can contribute to reducing greenhouse gas emissions caused by their thermal decomposition. The route involved the chemical-mechanical modification of the surface of alumina particles induced by milling in aqueous medium at different pHs for the formation of aluminum hydroxide [Al(OH)3] phases with subsequent hydrothermal treatment for the conversion to boehmite (AlOOH). The results showed that the pH of the suspension affected significantly the formation of aluminum hydroxides. The hydroxides formed at different pHs presented different behaviors during the conversion to boehmite via hydrothermal treatment. The effect of inorganic binder in the formability of alumina powder was verified using a device which simulated the extrusion process. The results showed that the formation of hydroxide nanoparticles on the surfaces of alumina particles may reduce significantly the organic binder content. The nanostructured boehmite-based inorganic binder results in the powder's plasticity, inhibits the water migration during forming process (extrusion), and increases the mechanical strength of formed body.
CB:P01 Synthesis and Characterization of VO2 Particles by Solvothermal Approach
H. HAMA, Q. DONG, S. YIN, T. SATO, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
VO2 is known to show the fully reversible phase transition between monoclinic VO2 (M) and rutile VO2 (R) around 68 °C, associated with drastic changes of the infrared transmission. Furthermore, phase transition temperature can easily decrease near room temperature by metal ion doping. Therefore, VO2 (M) is considered as a promising candidate for energy-efficient window coatings. Although VO2 has many polymorphs, only VO2 (M) and VO2 (R) have infrared modulation ability, therefore, the synthesis of the single phase of VO2 (M) particles is important. In addition, the particles size and morphology make a large influence on optical property. Since solvothermal reaction can easily control the polymorphs, size and morphology, it is best approach for VO2 (M) synthesis. In this research, we synthesized VO2 (M) particles by a simple solvothermal approach. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron mic roscopy (TEM), and thermogravimetric/differential thermal analysis (TG-DTA). The samples were assigned to monoclinic VO2 (M), and they caused the phase transition near 68 °C.
Acknowledgment: This research was supported in part by Hatano Foundation
CB:P02 Ceramic and Composite Fe2O3 Based Nanofiber Mats by Electrospinning
V. HALPERIN, G.E. SHTER, G.S. GRADER, Technion - Israel Institute of Technology, Haifa, Israel
Iron oxide is an abundant material used in wide range of applications from macrostructural industrial catalysts to nanostructured devices such as photovoltaics. Electrospinning is a routine method for generating polymer fibers and it is recently being applied for ceramic and composite nanofibers.
We present an investigation of precursor synthesis and processing of Fe2O3 ceramic and polymer/ceramic composite fiber mats. Precursors were prepared as suspension of α-Fe2O3 nanoparticles, Polyvinylpyrrolidone and special additives in propanol. Various solid loads and compositions, as well as preparation routes, were tested. The effect of electrospinning parameters such as work distance, voltage and feed rate on the fibers and mats morphology was studied. The controlled "green" fibers diameter was varied in 20-1000 nm range. Optimal thermal treatment profiles were developed based on the TGA/DTA/MS data and sintered ceramic mats with desired phase composition, fibers diameter and porosity were obtained. These mats are targeted to application as relatively new type of nanostructured catalyst for different processes.
CB:P05 Solution Synthesis and Photocatalytic Property of Fibrous titania
K. IMAKAWA, Q. DONG, S. YIN, T. SATO, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Miyagi, Japan
Titania is one of the most famous photocatalysts, where the performance greatly changes depending on the cystallite size, shape, crysallitiy, etc. Generally, nanocrystals of titania show excellent photocatalytic activity, but the recovery of them from a solution is difficult. Potassium tetratitanate (K2Ti4O9) has a unique layered structure and tends to show a fibrous morphology. Taking advantage of this feature, synthesis of fibrous titania using K2Ti4O9 as a precursor was attempted in this research. K2Ti4O9 was prepared by the flux method using a KCl flux and ion exchanged with a HCl aqueous solution to form H2Ti4O9. And then, titania was prepared by solvothermal treatment of H2Ti4O9 in different solvents such as methanol and ethanol. The photocatalytic activity was evaluated by the DeNOx ability. The products consisted of fibrous titania with similar morphology as the K2Ti4O9 precursor. The products consisted of anatase titania when the concentrations of alcohols was 0-75 vol. %, but mixture of monoclinic and anatase titania with relatively weaker XRD diffraction peak intensity. All the samples showed the photocatalytic activities superior to commercial titania (Deussa P25) under UV light irradiation.
Acknowledgment:This research was supported in part by Hatano Foundation
CB:P06 Solid State Catalyst: Utility in Silicon Resin Synthesis as PDC
F. VIVIER, Politecnico di Torino, Torino, Italy
Polymer Derived Ceramics (PDCs) represent an alternative synthesis route for the realization of ceramic components through the pyrolysis of polymeric precursors, the silicon-based PDC demonstrated to be excellent candidates.
The silicon resin studied here is a polymethylsilsesquioxane containing hydroxyl and ethoxy side groups which ensure its condensation. Its application as PDC has already been the subject of many publications; but the utility of the usual solid catalyst has never been studied. The solid cross-linking proposed for this study is the aluminium acetylacetonate.
Former studies have been developed on liquid solutions of silicon resins and catalysts in solvent, ensuring the complete contact between species -with maximum efficiency-, this work proposes a solid state mixing and questions the real utility of the catalyst.
This work is divided in two parts: the first one is about resin behavior and reactions occurring in temperature, using different methods as DSC and TGA. The second step deals with kinetic analysis under isothermal conditions at different T.
CB:P07 Microwave Technique: An Innovated Method for Sintering Beta-eucryptite Ceramic Materials
R. BENAVENTE, A. BORRELL, M.D. SALVADOR, Instituto de Tecnologia de Materiales (ITM), Universitat Politecnica de Valencia, Valencia, Spain; F.L. Penaranda-Foix, Instituto de Aplicaciones de las Tecnologias de la Información y de las Comunicaciones Avanzadas (ITACA), Universitat Politecnica de Valencia, Valencia, Spain; O. GARCÍA-MORENO, R. TORRECILLAS, Centro de Investigación en Nanomateriales y Nanotecnología (CINN) (CSIC-UO-PA), Llanera, Spain
Microwave sintering has emerged in recent years as a new, fast, cheap and green technology for sintering a variety of materials. The main advantages of microwave heating can be summarized as follow: reduced processing times, energy costs and environmental benefits. Nevertheless, understanding how this specific heating drives to obtain ceramic materials with a combination of unique, structural and functional properties is the big challenge.
The present work shows the different and improved properties achieved with beta-eucryptite nanocomposite ceramic materials by microwave heating in respect of the conventional method. Microcracking evolution in addition to the microstructure of the sintered materials along the several thermal cycles have been studied. Mechanical properties related to this behaviour change dramatically.
Thus, the microwave technique is a promising tool for sintering new materials by controlling the composition of the phases, chemical reactivity and nanostructure, using up to 70% less energy in the whole sintering process than conventional heating. This technique becomes part of the new and innovative technologies "eco-green".
CB:P08 Microwave Sintering of Ceramic Electrolyte Nanomaterials
K. SABOLSKY, A. BULBULE, S. CRONIN, K.A. SIERROS, E.M. SABOLSKY, Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV, USA; S. MORROW, Hadron Technologies, Arvada, CO, USA
The sintering of bulk ceramic oxides usually results in significant grain growth during the high temperature processing using conventional heating methods. The objective of this work is to investigate thermal processing of nano-scale precursor powders utilizing microwave sintering technologies, where the thermal schedule may be abbreviated to restrict unwanted grain growth. The goal is to retain grain sizes for the ceramic <0.1 μm while attaining >97% theoretical density. The main ceramic electrolyte composition focused upon in this work was CeO2 with various lanthanide dopants; doped-cerias are one the highest performing oxygen electrolyte systems used in solid-oxide fuel cell and electrolysis processes. Pellets were fabricated from both nano- and micron-size precursor powders for comparison purposes, and the samples were thermally processed between 1000-1500°C utilizing a 9 kW microwave furnace (2.45 GHz). The effects of the processing techniques to the final density, microstructure, and electrical and mechanical properties were characterized. Electrochemical impedance spectroscopy (EIS) was utilized to characterize the resistance associated with the bulk and the grain boundaries of the dense materials.
CB:P09 Morphological Control and Characterization of NaYF4 Upconversion Particles by Microwave-assisted Solvothermal Methods
Y. SUZUKI, Q. DONG, S. YIN, T. SATO, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Miyagi, Japan
Near-infrared-to-visible up-conversion (UC) fluorescence materials which include rare-earth ions are expected for the applications such as solar battery, etc. In this study, the UC fluorescence crystal of sodium yttrium fluoride (NaYF4) doped with Yb3+and Er3+ was fabricated by microwave solvothermal synthesis and the particle morphology and UC fluorescence were characterized. In a typical procedure for the synthesis of lanthanide-doped NaY0.93F4:Yb0.05/Er0.02 particles, after mixing desired amounts of deionized water, NaF aqueous solution and RE(NO3)3 (RE = Y, Yb and Er) aqueous solution under stirring, the solution was transferred into a Teflon-lined autoclave and heated in a microwave oven at 200 ℃ for 1 h. The obtained particles were washed with water and ethanol several times and dried. The products were characterized by XRD, SEM, measurement of UC luminescence spectra. NaY0.93F4:Yb0.05/Er0.02 are synthesized by the addition of excess amounts of NaF. NaY0.93F4:Yb0.05/Er0.02 consisted of agglomerated particles with rod-like crystals of ca. 1 μm in diameter and 5 μm in length. Under near-infrared laser excitation with 980 nm wavelength, the UC luminescence of visible light was emitted, where the intensity increased by the addition of excess amounts of NaF.
CB:P10 Structure of Zirconium Alloy Consolidated by Electric Pulse Consolidation
E.G. GRIGORYEV, L.Y. LEBEDEVA, NRNU "MEPhI", Moscow, Russia; E.A. OLEVSKY, San Diego State University, San Diego, CA, USA
Zirconium alloy powders (Zr +1% Nb) of spherical and flake forms have been consolidated by high voltage electric discharge consolidation.
The experimental dependence of the electric conductivity of the powders of spherical shape and flake shape on the applied pressure has been investigated. The influence of the current pulse amplitude on the final density of the consolidated zirconium powder alloy samples has been analyzed for differen t applied pressures. The maximum amplitude of the electric current density above which the consolidation process is unstable and has a nature of blowout has been determined. The conducted metallographic analysis showed the preservation of the microstructure of initial powder particles after the process of high voltage electric discharge consolidation.
CB:P11 Spark Plasma Sintering of Titanium Nitride Fine Powders
M.S. YURLOVA, B.A. TARASOV, A.N. NOVOSELOV, E.G. GRIGORYEV, NRNU MEPhI, Moscow, Russia; E.A. OLEVSKY, San Diego State University, San Diego, CA, USA
Nitride ceramics with high strength, high melting point and high thermal stability are very attractive materials for wide range of applications. However, the fabrication of fully dense components with required grain size is difficult via traditional powder processing techniques. The field assisted consolidation technologies and, in particular, spark plasma sintering provide a very effective way to address this problem. In the present study the specifics of sintering kinetics of titanium nitride powders with dif ferent average particle sizes (<100 nm and 25 microns) by spark plasma sintering are examined. The details of the processing of nano-powders by spark plasma sintering, and the effects of sintering parameters (pressure, temperature and holding time) on the properties, structure and fracture mechanisms of consolidated compacts are investigated.
CB:P12 Graphene as Toughening Agent in Alumina Ceramics
I. HUSSAINOVA, M. DROZDOVA, M. AGHANJAN, R. IVANOV, Department of Materials Engineering, Tallinn University of Technology, Tallinn, Estonia
Graphene is promising components for next-generation high-performance structural and multifunctional composite materials. Recently developed industrial scale technology of alumina nanofibers (ANFs) production allows creating brand new hybrid carbon-ceramic nanomaterials combining the properties of constituents. It was found that quality and quantity of graphene sheets on the ANF surface essentially depends on the pyrolysis of carbon source conditions such as gas flow, duration, temperature and the composition of the gas mixture. The alumina/graphene composites were produced by two methods of powder metallurgy: hot isostatic pressing (HIP) and spark plasma sintering (SPS). Both composites show improvement in both mechanical properties and electrical properties as compared to monolithic alumina. The main advantage of the graphene growth on the fibres surface is a lack of complicated step of constituents mixing. Graphene platelets are believed to act as toughening agents prevailing crack propagation under loading.
CB:P13 Al2O3 // 3Y-TZP // Graphene Multilayers Produced by Tape Casting and Spark Plasma Sintering. A Rheological, Sintering and Characterization Study
A. BORRELL, M.D. SALVADOR, E. RAYON, Instituto de Tecnologia de Materiales, Universitat Politecnica de Valencia, Valencia, Spain; C.F. GUTIERREZ-GONZALEZ, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN) (CSIC-UO-PA), Llanera (Asturias), Spain; A. RINCON, R. MORENO, Instituto de Ceramica y Vidrio, CSIC, Madrid, Spain; A.S.A. CHINELATTO, Universidade Estadual de Ponta Grossa, Uvaranas, Ponta Grossa - PR, Brasil
The aim of this work is to propose a procedure to obtain dense and free defects multilayered alumina-zirconia coatings with graphene. Green tapes of alumina alumina+5vol.%3Y-TZP and alumina+5vol.%3Y-TZP mixed with graphene-oxide (2 vol.%) were obtained by aqueous tape casting. of the three compositions. The rheological behaviour of concentrated suspensions was optimized considering the sonication mode and time and the content of deflocculant. Green tapes were punched and laminated in order to form ceramic laminates alternating up to 18 layers The obtained multilayer discs with 20 mm in diameter were sintered by spark plasma sintering (SPS) technique at 1400 ºC under vacuum and with pressure.
By means of optical and electronic microscope images of the ceramic cross-sections, it was revealed that the sintered laminates had a high green density and layer thicknesses of 100 µm without any apparent defect showing a good cohesion between them. Raman spectroscopy analysis confirmed the presence of tetragonal zirconia in alumina coatings and revealed carbon content inside all the samples. Nanoindentation results revealed that hardness and elastic modulus values were similar for all coatings, being higher than 27 GPa and 300 GPa, respectively.
CB:P14 Dispersion Strengthening Effect on the Spark Plasma Sintering of Ferritic/Martensitic Steels
I.A. BOGACHEV, I.I. CHERNOV, M.S. STALTSOV, NRNU MEPhI, Russia; E.A. OLEVSKY, San-Diego State University, USA
Microcrystalline mechanically alloyed powders of 13Cr-2Mo ferritic/martensitic steels with and without nanoscale yttria dispersed particles were compacted using spark plasma sintering (SPS) to near-theoretical density at a temperature of 1273 K (1000 °C). The initial powder morphology influence on the sintered specimens' grain size, shrinkage and final density are considered. Studies on densification behavior revealed that steels with dispersed particles densified faster when compared to 13Cr-2Mo steel without yttria. Also nanoscale particles stabilized the grain boundaries during sintering process leading to a less intensive grain growth. It is shown that the duration of mechanical alloying and particle morphology affect the final compacts' density & dispersion strengthened phase distribution. Heating rate and holding time influences on the densification of the processed samples are considered too.
CB:P15 Reactive Sintering of TaB2 by Spark Plasma Sintering
J. LASZKIEWICZ-LUKASIK, L. JAWORSKA, P. PUTYRA, B. SMUK, The Institute of Advanced Manufacturing Technology, Cracow, Poland
Tantalum diboride was synthesized and sintered from metallic tantalum powder and amorphous boron powder in one technological process using the Spark Plasma Sintering method. The precursors were: tantalum with grain size below 5µm and boron with particle size in the range of 1-2µm. Tantalum powder, before mixing with boron, was subjected to high-energy milling under argon atmosphere in order to reduce specific surface area. The process should be carried out without air, due to oxidation and the adsorption of oxygen. During reactive sintering SPS process oxidation participation should be limited because of high exothermic reactions. Morphologies of the powders before and after milling were studied using SEM. Reactive sintering processes were carried out at temperatures from 1800°C up to 2200°C at 48MPa. Sintering duration was in the range of 1-30min. Volume changes of samples and temperature increase during the synthesis were observed and determined. The result of X-Ray phase composition analysis and microstructure observations using SEM are presented. Relative density, Young's modulus, Vickers hardness and fracture toughness of the materials were determined. During the reactive sintering the material of only one phase- TaB2, with high level of densification, was obtained.
CB:P19 Directed Laser Synthesis of Composite Ceramics Y3Al5O12-Y2Ti2O7- Al2O3-Al2TiO5
P.A. MÁRQUEZ AGUILAR1, M. VLASOVA1, M. KAKAZEY1, A. BYKOV2, S. LAKIZA2, V. STETSENKO2, 1Center of Investigation in Eng. and Applied Sciences of the Autonomous University of the State of Morelos (CIICAp-UAEMor), Cuernavaca, Mexico; 2Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Kiev, Ukraine
Directed laser synthesis of composite oxide ceramics is a promising method for the preparation of materials with a complex of new properties which are formed under conditions of directional high-rate heating and subsequent high-rate cooling. Phase composition of the formed ceramics depends on the composition of initial mixtures, modes of laser radiation and the physic-chemical properties of the initial components. In presented investigation the compacted mixtures consisting of (mol. %): (40-84.5) Al2O3 - (12-40) Y2O3 - (4-27) TiO2 were irradiated by continuous-action laser with λ = 1064 nm, capacity 120 W and the linear traversing speed of the beam 0.15 mm/s. Investigations have shown that phase formation is carried out within the framework of binary mixtures Al2O3 - Y2O3, Y2O3 - TiO2, Al2O3 - TiO2 and accompanied by the formation of Y3Al5O12, Y2Ti2O7, Al2TiO5 and Al2O3. With increasing alumina content in initial mixtures and at constant ratio of TiO2/Y2O3 in ceramic material is increased corundum content. With increasing of the ratio and constant alumina content in initial mixtures in ceramic material is increased Y2Ti2O7 content and is decreased Y3Al5O12 content. Microstructure of the ceramic body and the texture of surface depend on the ratio of the formed phases.