Symposium CA
Progress in Powder Processing Science and Manufacturing for Advanced Ceramics and Composites

Session CA-1 Advances in Powder Synthesis and Characterisation

CA-1:IL01 Magnetic Field Assisted Freeze Casting of Ceramic Powders
J. McKITTRICK, University of California, San Diego, La Jolla, CA, USA; M.M. PORTER, Clemson University, Clemson, SC, USA; M.B. FRANK, Nanocomposix, Inc., San Diego, CA, USA

Freeze casting is a method where a ceramic slurry is directionally solidified, thereby creating a porous ceramic with aligned (direction of solidification) lamellar walls surrounded by empty channels. Magnetic field-assisted freeze casting is a novel method to fabricate porous, anisotropic ceramic scaffolds with a hierarchy of architectural alignment in multiple directions. A weak rotating magnetic field (0.12 T) applied normal to the ice growth direction in a uniaxial freezing apparatus allowed the manipulation of magnetic nanoparticles to create different pore structures and channels with long-range order in directions both parallel and perpendicular to the freezing direction. Here, we report the fabrication of porous scaffolds consisting of different host ceramics: hydroxyapatite, ZrO2, Al2O3, or TiO2. The slurries were mixed with Fe3O4 nanoparticles that steer the particles in the direction parallel to the magnetic field, either static or rotating. The resulting microstructures and mechanical properties will be discussed.


CA-1:IL02 Synthesis and Characterization of Nanoparticles
M.-A. EINARSRUD, M. SlETNES, T.O.l. SUNDE, P.M. RORVIK, A. DAlOD, T. GRANDE, Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, Norway

Oxide nanoparticles have many interesting applications in ceramic technology, energy technology, ICT and medical technology. Wet chemical methods are versatile for the synthesis of these oxide nanoparticles. Aqueous wet chemical processing has the advantages of being simple, environmental friendly, easy to scale up and that complex oxides can be made. Starting from a stable aqueous solution containing the cations to build up the material, nanoparticles can be made by method such as sol-gel, modified Pechini synthesis, combustion synthesis, hydrothermal synthesis as well as spray pyrolysis. Here we will discuss the chemistry behind the preparation of stable aqueous solutions containing a wide range of cations where the use of complexing agents are necessary to hinder precipitation. Further examples of synthesis of nanoparticles will be given with focus on using hydrothermal and modified Pechini synthesis. Using hydrothermal synthesis we present how to prepare in situ functionalized TiO2, SiO2-TiO2 core shell particles, NaNbO3 and PbTiO3 nanorods prepared by the aid of surfactants and oriented attachment of cube-shaped nanoparticles. By the modified Pechini approach we describe the synthesis of (SrxBa1-x)2CaWyMo1-yO6 phosphors as well as Indium tin oxide nanoparticles.


CA-1:IL03  Synthesis of Oxide Particles: From Polymeric Precursors to Colloidal Synthesis Process
E.R. LEITE, Brazilian Nanotechnology National Laboratory - LNNano, Campinas, SP, Brazil

The synthesis of nanometric particles (nanoparticles) of ceramic materials has been consolidated in the last two decades as a multidisciplinary research area, aiming to obtain control over the phase purity, as well as in the shape, size, size distribution and degree of agglomeration of the nanoparticles. In general, this degree of control is only possible through the use of chemical synthesis routes, because those methods allow a better control of the process at a molecular level. In this lecture, I will report the advantages and disadvantages of the synthesis routes based on the Pechini method and on colloidal methods mainly based on the non-hydrolytic sol-gel route. Results related to the control of the size, shape, and degree of particle agglomeration will be presented, especially for oxides such as SnO2 (doped and undoped), ZrO2, TiO2, PbTiO3, and SrTiO3.


CA-1:IL04  Spray Pyrolysis of Fine Oxide Powder
K. WIIK, NTNU, Trondheim, Norway; S. LABONNOTE-WEBER, G. SYVERTSEN-WIIG, CerPoTech AS, Heimdal, Norway

The applications of ceramic materials are numerous, ranging from high temperature fuel cells (SOFC) and catalytic active materials, via dielectrics (ferro- and piezo-electric) to oxygen separation membranes and high temperature superconductors, to mention a few. These material systems have all in common that they are oxide based with rather complex compositions and proper materials processing is based on the availability of high purity, homogeneous and nano sized powders. A particular powerful method to obtain ceramic powders with nano-homogeneity and nano-size combined with a high production rate is spray pyrolysis. The precursors are typically based on water soluble metal salts (e.g. nitrates) mixed in correct proportions and atomized using pressurized air and subsequently fed into a hot rotating chamber where drying and reaction takes place. Here we will present a more thorough description of the spray pyrolysis process as such and give examples from the production of some chosen complex compositions, based on our more than 10 years of experience with ceramic powder production using spray pyrolysis.


CA-1:L05  Synthesis of Submicronic Silica Janus Particles by a Pickering Emulsion Method: Towards the Characterization of their Assemblies
K. LEBDIOUA, A. AIMABLE, M. CERBELAUD, A. VIDECOQ, SPCTS, Limoges, France

Janus particles are anisotropic particles presenting at their surface either different shapes or chemical compositions. They are potential new colloidal bricks for the new ceramic materials architectures based on innovative self-assemblies controlled by their asymmetric feature. Submicronic silica Janus particles are synthesized using a Pickering emulsion method, which consists in an emulsion with solid wax stabilized by the colloids. One side of the particles is masked and the other side is chemically modified. After removing the wax Janus particles are recovered. The immersion of the particles into the wax depends on their hydrophobicity, the emulsion being obtained by heating the system above the melting point of the wax. The effect of different surfactants is studied in order to modify the three-phase contact angle between the wax and the particles. Another critical parameter is the formation of a monolayer of particles at the surface, the formation of multilayers or aggregates being detrimental to the functionalization of the particles. Finally the Janus particles and their assemblies are characterized in different conditions, to get a better understanding of their specific interactions in suspension through sedimentation tests, cryo-SEM and confocal microscopy.


CA-1:L06  Synthesis of Indium Hydroxide Powders by a Precipitation Method
WOO-SEOK CHO¹, EUN-KYOUNG CHOI^{1, 2}, WON-JUN LEE^{1, 3}, KYU-SUNG HAN¹, UNG-SOO KIM¹, JIN-HO KIM¹, KWANG-TEAK HWANG¹, JONG-YOUNG KIM¹, HAE-JIN HWANG³, KWANG-BO SHIM², ¹Korea Institute of Ceramic Engineering and Technology, Icheon, South Korea; ²Dept.of Materials Science and Engineering, Hanyang University, Seoul, South Korea; ³School of Material Science and Engineering, Inha University, Incheon, South Korea

For the production of a high-density ITO target, In2O3 powders with a small particle size and low agglomeration should be synthesized. The purpose of this study is to control the size and shape of the Indium hydroxide powder which affects the properties of the In2O3 powder. As a starting raw material, Indium metal was dissolved in a Nitric acid(HNO3) solution. Crystallite size of each sample was analyzed by X-ray diffraction and the shape and the size of the powder was analyzed by transmission electron microscopy. As a result, the particle size of Indium hydroxide was increased with increase in the concentration of In(NO3)3 and the particle size and shape of the Indium hydroxide remained unchanged with increase in the pH of the solution. The particle size increased with increase in the precipitation temperature during precipitation.


CA-1:L07  Effect of Iron Oxide Coloring on the Microstructure, Mechanical Properties and Aging Stability of 3Y-TZP
E. WILLEMS^{1, 2}, F. ZHANG^{1, 2}, B. VAN MEERBEEK², J. VLEUGELS¹, ¹Dept. of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Leuven, Belgium; ²KU Leuven BIOMAT, Dept. of Oral Health Sciences, KU Leuven & Dentistry, University Hospitals Leuven, Leuven, Belgium 

3 mol% yttria-stabilized zirconia (3Y-TZP) ceramics are very promising materials for dental restorations due to their transformation toughening induced fracture toughness. The use of dental 3Y-TZP ceramics is limited by a low translucency and a poor adhesion of veneering layers. One of the strategies to color 3Y-TZP involves the addition of coloring oxides such as Fe2O3 in the starting powder. In this study, we investigated the influence of 0.01-2 mol% Fe2O3 addition on the microstructure, mechanical properties, optical properties and the hydrothermal stability of zirconia ceramics. Commercially available high translucent zirconia starting powders were doped with iron oxide. Only the 0.01-0.1 mol% Fe2O3 doped 3Y-TZP had a proper shade for dental restorations. The obtained 3Y-TZP was composed of 87 vol% t-ZrO2 and 13 vol% c-ZrO2. The amount of cubic phase increased with increasing Fe2O3 content above 0.5 mol% Fe2O3. The 0.01-0.1 mol% Fe2O3 dopant did not change the hardness (~13 GPa) and fracture toughness (~3.6 MPa m1/2). Higher amounts of Fe2O3 substantially decreased the hardness. The hydrothermal aging resistance slightly improved with increasing Fe2O3 content up to 1 mol%, while the translucency decreased.


CA-1:L08  Structural and Transport Properties of Neodymium Tungstates Prepared via Mechanochemical Activation
Y.N. BESPALKO, V.A. SADYKOV. P.I. SKRYABIN, T.A. KRIEGER, Boreskov Institute of Catalysis, Novosibirsk, Russia; N.F. UVAROV, A.S. ULIHIN, Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia

In the last 10 years proton transport has been intensively studied in lanthanide tungstates Ln6WO12 with appreciable mixed electronic-proton conduction as promising candidates for development of ceramic hydrogen transport membranes. Transport properties of Nd5.5WO11.25-δ were improved by the partial substitution of Nd with different lanthanides in (Nd5/6La1/6)5.5WO11.25-δ and Nd5.5W0.5Mo0.5O11.25-δ basic systems. All materials have been prepared using mechanochemical activation (MA) of starting oxides in a high-power planetary ball mill. Studies of tungstates structural properties genesis by using thermal analysis, XRD, SEM, TEM with EDX analysis, IR and Raman spectroscopy have revealed that MA results in formation of a fluorite structure already after milling. High-density ceramic pellets have been obtained after sintering at 1300 °C. For all samples the electrical conductivity values measured in a humid atmosphere (up to ~ 10-3 S/cm at 550 °C) exceed those measured in a dry atmosphere indicating the proton character of conductivity.
The work was supported by the Russian Science Foundation (Project 16-13-00112).


Session CA-2 -Colloidal Processing

CA-2:IL01  Powder-Less Processing for Nano-structured Functional Ceramics: Realization of direct Fabrication from Solutions and/or Melts
MASAHIRO YOSHIMURA, Materials Sci. & Eng. National Cheng Kung University, Tainan, Taiwan & Tokyo Institute of Technology, Tokyo, Japan

Ceramics have mainly been fabricated via powders or particles, However solution processings is the least energy consumption when the shaped ceramics can be fabricated directly, i.e. in a single step.  The direct fabrication of ceramics in a solution  can be achieved via the interfacial reaction between a solid substrate and reactant(s), and solute specie(s) in a solution.  These processes  called as soft processing  might prepare various ceramics films like BaTiO₃, SrTiO₂, CaWO₄, etc., at low tempertures, RT-150℃, without any post firing.  The patterned ceramics can also be fabricated directly in solutions when those interfacial reactions are locally activated and/or scanned.  Other direct fabrication methods, ink-jet reaction method and spray deposition method have been developed for direct patterning of ceramics: CaWO₄, BaWO₄, TiO₂ and CeO₂ films and patterns. 
The novel melt processings have been re-investigated for the direct fabrication of bulk ceramics particularly for binary and ternary eutectic systems.  Melt casting and annealing of the eutectic amorphous phase could produce nano-structured ceramics in HfO₂-Al₂O₃-GdAlO₃ and C₁₂A₇-CaYAlO₄ systems, etc. 


CA-2:IL02  Layer by Layer Modification of Nanoparticles Surfaces in Suspension: From Order to Chaos during the Nanostructured Growth of a Ceramic Film
B. FERRARI, Z. GONZALEZ, J. YUS, A.J. SANCHEZ-HERENCIA, Institute of Ceramics and Glass, CSIC, Tailoring through Colloidal Processing Group, Madrid, Spain

Understanding the colloidal behavior of nanoparticles (NPs) is mandatory to prepare stable and disperse suspensions suitable for colloidal coating methods (dipping, spinning, etc.). In electrostatically stabilized suspensions, the morphology, the crystallography and the reactivity of the NPs, determine the charge distribution, while the ionic strength modulates the charge, determining NPs assembly during evaporation. However, in stable suspensions, the surface modifiers and suspensions additives result in effective tools to manage NPs flocculation and hence ordering. Among the coating processes, the Electrophoretic Deposition (EPD) has been considered as the most suitable technique to cover 3D complex shapes and macroporous substrates (i.e. scaffolds and foams). It also shows remarkable features comparing with the conventional methods, since it allows producing customized products saving cost in raw materials and it can be integrated in Industry 4.0 schemes as an ecological processes in green and sustainable engineering. We will discuss how the Layer-by-Layer (LbL) technology, understood as the alternate absorption of cationic and anionic polymers onto the particle surface, determines NPs assembly in 3D ceramic coatings.


CA-2:L03  Role of Electrostatic Interactions in the Adsorption of Colloids in Pickering Emulsions
M. CERBELAUD, A. VIDECOQ, A. AIMABLE; Univ. Limoges, CNRS, SPCTS, UMR 7315, Limoges, France; L. ALISON, H. TERVOORT, A. STUDART, Complex Materials, Department of Materials, ETH Zurich, Zurich, Switzerland

Emulsions or foams stabilized by colloidal particles are now currently used for a wide range of applications. For example emulsions can be used for the synthesis of inorganic Janus particles [1] and foams to produce highly porous ceramics [2]. Stable foams or emulsions can indeed be achieved by the adsorption of particles at the liquid-liquid or liquid-gas interface. In this case, droplets or bubbles are covered by layers of colloidal particles, which give them a high stability. However, the dynamics and stabilization mechanisms at the colloidal level are poorly understood. In this study, we propose to analyze the early dynamics of emulsification by means of Brownian dynamics simulations based on experimental systems. We will particularly focus on the role of electrostatic interactions in the first stage of emulsification. We will show that these interactions, which are not always considered in these systems, play actually an important role in the adsorption of colloidal particles at the liquid-liquid interface.
[1] A. Zenerino et al., J. Colloid Interface Sci. 450 (2015) 174–181; [2] I. Akartuna et al., Advanced Materials 20 (24) (2008) 4714–4718.


CA-2:IL04  Processing of Stable and Reliable Zirconia Ceramics for Dental Applications
FEI ZHANG^{1, 2, 3}, J. VLEUGELS¹, H. REVERON³, T. FÜDERER⁴, S. SCHOMER⁴, N. COURTOIS⁵, A. LIENS³, B. VAN MEERBEEK², J. CHEVALIER³, ¹University of Leuven, Dept of Materials Engineering, Heverlee, Belgium; ²University of Leuven & Dentistry, BIOMAT, Dept of Oral Health Sciences, University Hospitals Leuven, Leuven, Belgium; ³University of Lyon, UMR CNRS 5510 (MATEIS), INSA de Lyon, France; ⁴Ceramic Materials, Swerea IVF AB, Mölndal, Sweden; ⁵ANTHOGYR, Sallanches, France

Zirconia ceramics have drawn great interest in dental field mainly because of their good mechanical properties, biocompatibility and aesthetic potential. Nevertheless, their long-term stability in oral condition is risked by the hydrothermal aging problem. Classical 3 mol% yttria-stabilized zirconia (3Y-TZP) used for fixed dental prostheses can be modified by the grain boundaries via doping suitable trivalent oxides like La2O3. This grain boundary engineering resulted in a better balance between the translucency, aging-stability and mechanical properties including crack resistance and flexural strength. On the other hand, for implants and abutments, composites can be alternative since aesthetic requirement is not as critical as crowns. In this talk, we will focus on zirconia-based composite made of ceria-stabilized zirconia (Ce-TZP) and two second phases (alumina and strontium aluminate). These perfectly stable poly-phasic composites had ultrafine microstructure and benefited from the transformation induced plasticity, hence being strong, flaw tolerant and less sensitive to surface treatments.


CA-2:IL05  Colloidal Process of Hematite Photoanode for Solar Water Splitting
F.L. SOUZA, Universidade Federal do ABC, Santo Andre, Sao Paulo, Brazil

The efficiency of nanostructures for photoelectrochemical water-splitting is fundamentally governed by the capability of the surface to sustain the reaction without electron trapping or recombination by photogenerated charge. This talk will summarize the latest progress on hematite, designed with columnar morphology via colloidal process under hydrothermal condition, for photoelectrochemical cell application. The columnar morphology efficiently minimizes the number of defects, grain boundaries, and surface traps normally present on the planar morphology. In fact, the nanostructure design faster becomes a key factor in the race for enhancing the photoelectrochemical device performance. In addition, the major drawback related to the hole diffusion through the solid/liquid interface will be addressed by correlating the use of high annealing temperature combined with dopant addition. Finally, a critical view and depth of understanding of these two parameters will be discussed focusing on the molecular oxygen evolution mechanism from the sunlight-driven water oxidation reaction.


CA-2:IL06  New Water-based Organic Additives in Colloidal Processing of Ceramics and Composites
M. SZAFRAN, Warsaw University of Technology, Faculty of Chemistry, Warsaw, Poland

Colloidal processes are recently willingly applied in fabrication of high-quality ceramic elements and composite materials. Among these we can distinguish e.g. preparation of granulates for die pressing as well as slurries for tape casting, gelcasting, etc. Colloidal processes of ceramics and composites require new, effectively working processing agents like deflocculants, binders or organic monomers. The results of studies on the application of new water dispersible poly(acrylic-styrene) and poly(acrylic-allyl) binders for die pressing and tape casting of Al2O3 ceramics will be presented. The properties of these polymers were modified by insertion of selected amphiphilic macromonomers into the polymeric chains. These amphiphilic macromonomers, due to the proper ratio of the hydrophilic to hydrophobic fragments, play the role of an internal plasticizer by changing the glass transition temperature and the adhesion to the ceramic particles. The author will present also the synthesis and application of new organic compounds based on glycerol and saccharides which are synthesized from low-toxic, water-soluble, inexpensive and renewable materials. The results showed that the obtained compounds could play multifunctional role in gelcasting of ceramic powders.


CA-2:L07  Homogeneity Enhancement of Additives on Boron Carbide by Precipitation Method
M.F. TOKSOY, C. ELCI, Izmir Institute of Technology, Department of Mechanical Engineering, Turkey

Boron carbide is a structural ceramic material with exceptionally good physical and chemical properties. However sintering of boron carbide is extremely difficult due to its high melting point, strong covalent bonding and thin oxide film around the powder particles. Thus producing boron carbide articles is a challenge and limiting the application areas. In order to overcome these limitations research efforts are focused to decrease sintering temperature and improve fracture toughness. These studies are aimed to introduce secondary phases and additives were used such as carbon, metal oxides and pure metals. Homogeneous distribution of additives is critical since mechanical properties of boron carbide decreases with increasing additive content.
This study proposes to use precipitation method to enhance homogeneity of alumina and yttria addition to the highest level. Yttrium hydroxide and aluminum hydroxide salts are dispersed and added into boron carbide slurry which has high pH levels. Solution is aged then calcined to form metal oxide layers around the boron carbide particles. Additive-boron carbide ratio is changed and effect of different ratios on sintering behavior is investigated. Microstructural characterization of sintered part and characteristics of powder is completed by using SEM, EDX. Precipitation method enhanced the dispersion of additives compared to ball milled samples.
Acknowledgement. Authors would like to thank Scientific and Technological Research Council of Turkey (TÜBİTAK) for their support. Grant No: 116M205


Session CA-3 - Shape Forming and Green Body Processing and Characterization

CA-3:IL01  Aqueous Gelcasting: A Versatile and “Green” Technique to Shape Ceramics
L. MONTANARO, P. PALMERO, M. LOMBARDI, C. PETIT, J.-M. TULLIANI, Dept. Applied Science and Technology DISAT, Politecnico di Torino, Torino, Italy 

Gelcasting is a well-known wet forming method based on the combination of ceramic processing and polymer chemistry. A ceramic powder is dispersed into a monomer solution, prior to casting into a nonporous mold and then polymerization is promoted. Ceramic particles are entrapped into the rigid and homogenous polymeric network. After gel formation, gelcast green materials can be easily demolded and dried; they are characterized by a quite high strength and a low amount of organic additives. The technique is highly versatile and has been extended to a variety of ceramic materials. Different monomers were used for gelcasting, starting from acrylamide systems, now withdrawn due to their neurotoxicity. Alternatively, natural gelling agents present the advantage of a low environmental impact, water can be used as dispersing medium, and their polymerization can be promoted by cooling below the glass-transition temperature, without the use of catalyst and initiator, needed for synthetic monomers. Some positive experiences of aqueous gelcasting performed to produce porous ceramic bodies having controlled porosity features (pore size, volume and geometry) are here collected. Some new results obtained in the development of microstructurally graded ceramic materials are also highlighted.


CA-3:IL02  Nano/Microstructure Control of Advanced Materials and their Applications by Smart Powder Processing
MAKIO NAITO, TAKAHIRO KOZAWA, AKIRA KONDO, Joining and Welding Research Institute (JWRI), Osaka University, Ibaraki, Japan

Recently, various novel powder processing techniques were rapidly developed for advanced material production due to the growing of high-tech industry, especially in consideration of green and sustainable manufacturing. Smart powder processing stands for green and sustainable powder processing technique that creates advanced materials with minimal energy consumption and environmental impacts. Particle bonding technology is a typical one to make advanced composites.By making use of particle bonding, a new one-pot processing method to synthesize nanoparticles without applying extra heat was developed. Furthermore, one-pot processing achieving both the synthesis of nanoparticles and their bonding with another kind of particles to make nanocomposite granules was also developed. As a result, it can custom various kinds of nano/micro structures and can produce new materials such as all-solid-type LIB and SOFC with a simpler manufacturing process. On the other hand, by carefully controlling the bonding between different kinds of materials, separation of composite structure into elemental compoment is also possible, which leads to the development of novel technology for recycling composite materials and turns them to high-functional applications. Examples will be also introduced.


CA-3:IL03  Environmentally Benign Debinding Procedures for Thermoplastic Based Ceramic Processing Route
L. GORJAN, T. LUSIOLA, D. SCHARF, F. CLEMENS, Empa, Materials Science and Technology, Lab. for High Performance Ceramics, Dübendorf, Switzerland

Thermoplastic ceramic feedstocks can be heated above the melting point of the thermoplastic binder material and shaped by different techniques like extrusion, pressing, injection moulding or even 3D-printing (FDM method). The challenging and time-consuming operation for thermoplastic ceramic processing is the removal of the organic binder from the shaped green bodies prior to sintering, without causing any deformation or cracks. We prepared thermoplastic feedstocks of PZT powder with different types of ethylene-vinyl acetate (EVA) as the backbone polymer binder and a paraffin wax as the secondary, low molecular binder. Activation energy of the decomposition was evaluated using the model free method. The modelling was assisted by well-known practical strategies to investigate the debinding behaviour. Different mathematical models of binder decomposition were used to describe the binder content during the process and compared to each other. We demonstrate that than 90% of the binder can be removed at only 200°C in a partial debinding step, even for a multicomponent binder system with ethylene vinyl acetate binder. This economic process enables a very rapid final binder removal and sintering step to produce dense and crack-free samples.


CA-3:L04  Preparation of TiO2-Y2O3 and UO2-Y2O3 Pellets by Freeze Granulation or Slip Casting
F. LA LUMIA, L. RAMOND, G. BERNARD-GRANGER, CEA Marcoule, Bagnols-sur-Cèze, France; C. Pagnoux, SPCTS, Limoges, France

The current production of MOX fuels is carried out by a dry route process, involving steps with fine powders (grinding, mixing, pressing). In order to limit dust retention in glove boxes and thus to decrease workers dose rates, new liquid route processes are investigated. They also grant better actinide homogeneity in the final material compared to the dry process. The key step of these liquid route processes is the preparation of a stable and well-dispersed aqueous actinide oxides suspension through the use of an optimized amount of dispersant, in order to have a charged, yet fluid and settling-resistant suspension. Two liquid routes for pellet shaping have been investigated. The first one is the freeze-granulation of the suspension followed by a granules pressing step. The second one consists to slip cast the suspension into porous mold. This research was first carried out on TiO2 and Y2O3 powders, selected for their suspension properties (Point of Zero Charge and particle morphology) to surrogate UO2 and PuO2 respectively. Then TiO2 was replaced with the active powder UO2. Electrokinetic and rheological properties of TiO2-Y2O3 or UO2-Y2O3 suspensions have been investigated and subsequent granules and pellets have been characterized.


CA-3:L05  Tribochemically Induced Optical Property Changes in MgO-Nanoparticle Powders
T. SCHWAB, D. THOMELE, University of Salzburg, Salzburg, Austria; K. McKENNA, University of York, York, UK; O. DIWALD, University of Salzburg, Salzburg, Austria

As an insulator Magnesium Oxide does not show optical absorptions in the range of visible light. Moreover, this oxide is optically isotropic and thus non-birefringent which makes it suitable for translucent ceramics. For production of optical ceramics, particle powders are pressed and subsequently subjected to sintering. Here we investigated optical properties (color and translucence) of nanocrystalline MgO particle ensembles during pressing and tracked at the same time the formation of paramagnetic species. We observed significant changes upon pressing: an absorption band in the range of visible light associated with a change of color from white to yellow. Complementary measurements with electron paramagnetic resonance spectroscopy point to the pressure-induced emergence of oxygen radicals. These radicals are stable in high vacuum conditions and oxygen atmosphere but degrade by water adsorption. Comparison of pressure and light induced radical formation provides a base for the assignment of UV-Vis absorption features as well as EPR signals and point to a tribochemically induced reaction path. These findings will have an impact on the processing of MgO based nanocrystalline ceramics and are particularly relevant for heterogeneous catalysis and surface chemistry of ceramic oxides.


CA-3:L06  Comparison of Different Methods for Polycrystalline Er:YAG Ceramics
M. LAGNY, J. BOEHMLER, E. BARRAUD, S. LEMONNIER, S. BIGOTTA, M. EICHHORN, Institut franco-allemand de recherches de Saint Louis, Saint Louis, France; Y. LORGOUILLOUX, A. LERICHE, Laboratoire des Matériaux Céramiques et procédés Associés, LMCPA, Pôle universitaire de Maubeuge, Maubeuge, France

In last decades, transparent polycrystalline ceramics are widely studied and find various applications in different fields like electronics, biology or optical systems. The current subject here is to develop a Solid State Heat Capacity Laser (SSHCL) which exhibits an emission at 1.6 µm so-called “eye-safe” emission. The main improvement of this laser is to replace the current gain medium, the single crystal, by polycrystalline ceramic which induces better thermo-mechanical performances due to the possibility of making a gradient of the active Er3+ ion. This gradient help to reduce the overheating phenomenon which can occur during the lasing time and the metallurgy approach allow to tune the microstructure to reduce the thermal stress. Today, the focus will be on different methods to obtain a doping gradient, starting from powder, green bodies or already dense ceramics. All these approaches will be compared in terms of diffusion of Er3+ ion diffusion with the help of SEM-EDX and EPMA characterization.


CA-3:IL07  Multilayer Ceramic Systems by Tape Casting Process
P.-M. GEFFROY, R. BOULESTEIX, E. BECHADE, T. CHARTIER, SPCTS, Université de Limoges, Limoges, France

The multilayer ceramic systems is of great interest for many applications, solid oxide fuel cell, microelectronic devices, ceramic membranes, etc… The tape casting process allows to produce these multilayer ceramic systems, but this involves to control the shrinkage during the sintering step and the chemical reactivity between layers. The recent works reported in the literature show new approaches to obtain the specific design of multilayers system by tape casting. This talk is focused on new process routes to obtain multilayer systems with specific microstructure in relation with the optimal properties required for application. Particular attention is given to the impact of process parameters on the microstructure of final ceramic part for different applications. Finally, the main keys of ceramic process are discussed for different applications.


CA-3:IL08  Advanced Techniques for Green Body Characterization and Control of Sintered Texture
SATOSHI TANAKA, Nagaoka University of Technology, Nagaoka Niigata, Japan

Homogeneous packing structure of green body is crucial for microstructure of sintered ceramics. Spray-dried granules are used to improve the fluidity of powders and to achieve structural uniformity in a green body. However, granules also cause the hierarchical structures in the green body. Coarse pores may develop from this structure. We clarify the hierarchical structure of green body and development process of sintered structure in alumina ceramics by direct observations using optical microscopy and micro-focus X-ray computed tomography (micro-CT). The alumina green body was prepared by dry-pressing of several types of granules. The samples were observed by optical microscopy, electron microscopy, and micro-focus X-ray computed tomography at each manufacturing step at sintering temperatures. We observed the same alumina ceramic sample from the green body stage to sintered ceramics stage. For the typical granule containing submicron particles with binder, the result showed interface of granules in the green body, and these became noticeable with sintering. This is because the particles in each granule shrunk at low sintering temperatures. Furthermore, larger pores grew into coarser pores by combining with smaller neighboring pores during sintering.


CA-3:L09  Development of Transparent Ceramics: Understanding and Control of Microstructure
R. STOCKY, J. BOEHMLER, S. LEMONNIER, French-German Research Institute of Saint-Louis, France; Y. LORGOUILLOUX, A. LERICHE, University of Valenciennes and Hainaut-Cambrésis, France

The main challenge for armor systems is to optimize and enhance the protection against specific threats but also to reduce weight. These last years, one material is in the spotlight: the Mg-Al-Spinel. This ceramic has many advantages such as high transparency in the UV, visible and mid-IR, good mechanical properties. An improvement of these properties can be achieved by a fine control of the characteristics of the powder, which are crucial since they are directly influencing the sintering behavior. The aim of this work is to study the influence of different treatments of a spinel powder on its characteristics and furthermore on its sintering behavior. An optimization of the process is necessary to remove remaining voids and to better control the microstructure and thus the mechanical properties. Commercial spinel powder was submitted to a treatment consisting of a suspension step, followed by a mixing and a drying steps. Evaluation of treatment effect was done, based on the rheological behavior of the powder and the modification of physical characteristics (particle size, compressibility, angle of repose) and on its sinterability. As a result, these treatments influence also the microstructure of the ceramic (grain size) and the sintering temperature, and thus the transparency.


Session CA-4 - Sintering

CA-4:IL01  On the Role of the Electric Field on the Sintering of Oxide Ceramics
O. GUILLON, Forschungszentrum Juelich, Juelich, Germany

Beyond standard FAST/SPS (Field Assisted Sintering Technique / Spark Plasma Sintering) limited to a few Volts but applying moderate to large uniaxial mechanical pressures, the role of an electric field on the densification and coarsening of oxide ceramics is still under debate. By using an instrumented sinter-forging equipped with a separate power source as well as a unique hybrid-flash FAST/SPS, it is possible to quantify and rationalize such effects on densification rates, sintering parameters such as uniaxial viscosity and sintering stress as well as the microstructure of oxide ceramics.


CA-4:IL02  Discrete Element Simulation of Sintering
D. JAUFFRES, C.L. MARTIN, Univ. de Grenoble Alpes, CNRS, Grenoble-INP, SIMaP, Grenoble, France; A. Lichtner, Dept. of Mat. Sci. and Eng., University of Washington, Seattle, Washington, USA; R.K. BORDIA, Dept. of Mat. Sci. and Eng., Clemson University, Clemson, South Carolina, USA; J. VILLANOVA, ESRF, The European Synchrotron CS 40220, Grenoble Cedex, France

This talk reviews recent advances in the simulation of sintering based on the Discrete Element Method (DEM). In DEM, particles are explicitly modeled. Each particle interacts with its neighbors through appropriate contact laws. The appearance of new contacts and the loss of others is inherently included. In this contribution, we present results originating from various examples of DEM applications. We examine composite powders made of a sintering matrix mixed with inclusions and the retarding consequences of inclusions. We demonstrate the use of DEM for simulating multilayered systems in which the appearance of defects originates mainly from the particulate nature of the material to sinter. Finally, we model the anisotropic sintering of freeze-cast structures to obtain porous ceramics for use in various fields of materials science. DEM simulations confirm that freeze-cast structures experience more strain along their freezing direction than transverse to it. Here, the DEM simulations are based on X-ray tomography images that provide a realistic initial structure for the simulations. The anisotropic behavior can be explained by the orientation of free surfaces and by the fact that contacts with normal oriented in the freezing direction provide a driving force for shrinkage.


CA-4:IL03  Microstructural Control and Characterization of Dense and Porous Ceramics
W. PABST, T. UHLIROVA, V. NECINA, E. GREGOROVA, Department of Glass and Ceramics, University of Chemistry and Technology, Prague, Czech Republic

Both dense and porous ceramics have been mainstays of ceramic research and development for many decades. Concerning porous ceramics this contribution focusses in detail on two new shaping techniques that have turned out to be rather successful: foaming with wheat flour and biological foaming with yeast. As a paradigmatic example of dense ceramics we present recent results on highly dense spinel ceramics prepared by SPS. Following a brief discussion of microstructural control parameters, the quantitative microstructural characterization by image analysis techniques is explained. In particular, it is shown that the characterization of planar sections of porous materials should always be based on a set of three independent Minkowski-functional-based microstructural descriptors (porosity, pore surface density, mean curvature integral density) and that topological information like the 3D Euler number or total curvature integral density can only be obtained by tomographic techniques (disector probe). On the other hand the grain size of dense polycrystalline ceramics should be standardly characterized by both the mean intercept length and the Jeffries grain size. Also the determination of grain and pore size distributions is briefly discussed, including the random section problem.


CA-4:IL05  Comparison of Hot Pressing and Pulsed Electric Current Sintering of ED Machinable Ceramics
F. KERN, U. SCHMITT-RADLOFF, A. GOMMERINGER, R. GADOW, Universität Stuttgart - IFKB, Stuttgart, Germany

Electrically conductive ceramics for EDM often show poor sinterability. Therefore pressure assisted sintering processes such as hot-pressing (HP) and spark plasma sintering (SPS) are applied. Features of ED-machinable composites from the group of TZP and ZTA-based composites reinforced with TiC or TiN, NbC and WC consolidated by SPS and HP are discussed. >From an economic view the shorter dwell and cooling cycles are attractive. Faster cycles are required for TZP materials which are highly vulnerable to retransformation upon cooling. Mechanical properties - hardness, toughness and bending strength – of properly processed materials from both processing routes are comparable. Hot pressed materials are typically slightly tougher due to a coarser microstructure. Distinct differences were observed in electric conductivity and machinability. During SPS some conductive dispersions such as NbC in ZTA-NbC tend to form rigid conductive backbones within the microstructure. This may lead to strongly enhanced electrical conductivity and if the processing cycles are not adjusted to incomplete densification. Sintering cycles cannot be transferred from one technology to the other by simple rules of the thumb but have to be carefully elaborated to exploit the full potential of the materials.


CA-4:L06  Analysis of Densification Kinetics Depending on Grain Growth for Zirconia
BYUNG-NAM KIM, KOJI MORITA, HIDEHIRO YOSHIDA, JI-GUANG LI, National Institute for Materials Science, Japan; HIDEAKI MATSUBARA, Tohoku University, Japan

During sintering of powder compacts, several methods have been proposed to determine the activation energy and the grain-size exponent, but no method for the unspecified density function. In this study, an experimental method is proposed to determine the unspecified density function during isothermal sintering of Y2O3-stabilized zirconia. An interesting point is that the relationship between the grain size G and the relative density D is not constant but dependent on the temperature, though a constant relationship has widely been recognized. With increasing temperature, the density-dependence of the grain size decreases in the intermediate stage, whereas it increases in the final stage. The grain-size exponent evaluated is 2.75 and 1-2 in the intermediate and final stage, respectively. The grain-size exponent of 1-2 in the final stage was not expected, because almost all theoretical models have predicted an exponent of 4 for a mechanism of grain-boundary diffusion. In our experiments, however, the grain-size exponent of 4 apparently yields a large deviation from the experimental densification kinetics. With the grain-size exponent and the density function determined experimentally, the existing theoretical models are evaluated and the sintering mechanism is discussed.


CA-4:IL07  Sintering of Tailored Pore-Grain Structures: Multi-Scale Analysis
E.A. OLEVSKY, San Diego State University, San Diego, CA, USA

Macroscopic modeling of sintering offers a powerful tool that enables the study of some difficult aspects of powder consolidation, i.e., shape effects, size and density distribution effects, constraints and processing under external stresses. A single macroscopic-scale analysis, however, heavily relies upon empirical or idealized approaches limited in terms of the insight on the microstructure development during sintering. To address the above-mentioned challenges, a new approach, which does not require the formulation of material constitutive equations, is developed. In this novel approach the influence of any number of material structure parameters on sintering kinetics and on specimen distortion can be investigated. The examples of diffusion sintering of ceramic composites and of viscous sintering of a bi-layer porous specimen containing voids of anisotropic shapes are considered. The new integrated multi-scale framework taking into account the complex interplay between processing conditions and microstructure-constitutive properties provides a practical pathway to design and optimize manufacturing of advanced ceramic and metal systems with programmable macroscopic characteristics and micro-structure.


CA-4:L09  Two-Step Sintering Effects on the Properties of Pressureless-Sintered Ceramics
F. MAZZANTI, F. BEZZI, P. FABBRI, S. GRILLI, G. MAGNANI, E. SALERNITANO, M. SCAFÈ, ENEA SSPT-PROMAS-TEMAF, Laboratory of Materials Technologies Faenza, Faenza (RA), Italy

The Two-Step Sintering (TSS) process is a useful method to obtain high sintered density and to limit the grain growth associated to the sintering process final stage. One of the main advantages of this method is the lowering of the sintering temperature. In this work, the TSS process effects were demonstrated for silicon carbide (SiC) powder doped with boron and carbon and for yttria partially stabilized zirconia (Y-ZrO2). The microstructure and mechanical properties of TSS SiC and ZrO2 were determined and compared to those obtained with the conventional sintering process, performed on SiC at 2130 °C and on ZrO2 at 1500 °C . Solid state sintering of SiC was successfully conducted below 2000 °C. As consequence, TSS-SiC showed finer microstructure and higher flexural strength than conventional SiC. TSS-ZrO2 was successfully sintered at 1350°C and exhibited finer microstructure than conventional ZrO2. Nevertheless, mechanical properties as flexural strength remained substantially unchanged. The grain size reduction, instead, affected TSS-ZrO2 hydrothermal stability: the zirconia phase transformation, from tetragonal to monoclinic, was strongly inhibited by the higher density and the finer microstructure, as demonstrated by means of accelerated ageing tests.


CA-4:IL10  Processing of Dental Zirconia: How to Play on the Trade-off between Aesthetics, Mechanical Properties and Long-term Stability?
J. CHEVALIER, FEI ZHANG, H. REVERON, E. CAMPOSILVAN, L. GREMILLARD, University of Lyon, UMR CNRS 5510 (MATEIS), INSA de Lyon, France

The use of zirconia in dentistry has been showing an unpreceded evolution this past decade. For example, monolithic zirconia restorations, for which thick glass-ceramic veneers are no more mandatory, are becoming a real buzz in the dental community. Zirconia dental implants are also proposed as a serious alternative to titanium by several companies, including major players in the field. In addition to the conventional 3Y-TZP, several other compositions are today proposed, with the addition of alumina to improve aging resistance or with more yttria (such as in 4 or 5Y-TZP) to improve translucency, or even with the addition of secondary phases as for certain implants. In all cases, there is always a compromise between aesthetics (translucency and colour), mechanical resistance (generally relate to the potential of transformation toughening) and long-term stability (often referred as aging). In this talk, we will describe the different ‘zirconia’ ceramics that can be found on the market or in development and how they are placed in this trade-off between aesthetics, resistance and aging. We will then show how microstructural control through processing can lead to zirconia ceramics with improved properties, both for dental restorations and implants.


CA-4:L11  Thin Water Films on Nanocrystalline Oxides: Influence on Particle Coarsening, Coalescence and Grain Morphology Evolution
O. DIWALD, D. THOMELE, Department of Chemistry and Physics of Materials, University of Salzburg, Salzburg, Austria; A. GHEISI, Department of Chemical and Bioengineering, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany; J. BERNARDI, University Service Center for Transmission Electron Microscopy, Vienna University of Technology, Vienna, Austria; H. GRÖNBECK, Department of Physics and Competence Centre for Catalysis, Chalmers University of Technology, Gothenburg, Sweden

An important question to conventional sintering is how and to what extent residual water inside metal oxide particle powders affects coarsening and coalescence during heat treatment. We employed powders of MgO nanocubes with size distributions in the range below 10 nm as a model system for transformation studies of nanocrystalline particle systems. Using X-ray Diffraction, Electron Microscopy and Sorption Analysis we characterized particle powders at different levels of dispersion and after heat treatment in different gas environments. In the course of these studies we were able to describe the impact of adsorbed water on the evolution of MgO grain size, morphology and the level of intergrowth. While in water free environments, which are guaranteed at base pressures of p < 10-5 and under continuous pumping up to annealing temperatures of T = 1173 K, we obtained grains of almost cubic habit with predominant (100) planes, thin films of water were found to promote mass transport on such particle systems. This leads to substantial particle growth and intergrowth. At the same time, it stabilizes (110) faces and step edges on the grain surfaces and interfaces. The concomitant effects of kinetics and thermodynamics, which is based on the hierarchy of surface energies, to microstructure evolution inside MgO nanoparticle ensembles will be discussed.


CA-4:L12  Sintering and Viscous Behavior of a Low Temperature Co-fired Ceramic (LTCC) - From Experimental Characterization to Numerical Simulation of Co-sintering
A. HEUX¹, G. ANTOU¹, N. DELHOTE², N. PRADEILLES¹, A. MAITRE¹, ¹Univ. Limoges, CNRS, SPCTS, UMR 7315, France; ²Univ. Limoges, CNRS, XLIM, UMR 7252, France

Because of their low sintering temperature and good dielectric properties (low loss tangent), LTCC are easily associated with thin and highly conductive metallic films (Silver, Gold) in micro-electronic applications (5G applications up to millimeter-wave region). Co-sintering is a crucial step in the elaboration process of these multi-material components. Indeed, control of the final dimensions as well as their possible damages to the macroscopic and microscopic scales during the co-sintering step are key points controlling their electromagnetic performances. That is why there is a keen interest in the development of comprehensive modeling tools for prediction of final shape and dimensions. Densification behavior and viscosity of the LTCC are characterized. The sintering behavior is analyzed by determining the associated apparent activation energy and its evolution during the densification process using the Constant Heating Rate and Master Sintering Curve methods. The material viscous response is characterized by cyclic loading dilatometry measurements. Finally, these thermomechanical properties are integrated in a finite element numerical model. This model is applied to understand and predict the mechanical response during the co-sintering of LTCC-base multi-layers.


CA-4:L13  Ultrastrong Zirconia Ceramics Fabricated by an Oscillatory Pressure Sintering Process
TIANBIN ZHU^{1, 2, 3}, ZHIPENG XIE³, YAWEI LI^{1, 2}, ¹The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, China; ²National-provincial Joint Eingineering Research Center of High Temperature Materials and Lining Technology, Wuhan University of Science and Technology, Wuhan, China; ³State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China

The strength of ceramics is far lower than their theoretical value due to the presence of many flaws during powder consolidation. A straightforward approach to improve their fracture strength is to minimize the number and size of flaws within the ceramics. Here, we report a sintering strategy for the fabrication of ultrastrong ceramics through the introduction of oscillatory pressure. We have fabricated a fully dense 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) with a three-point bending strength of up to 1.81 GPa (about two times that of 3Y-TZP ceramics produced by commonly used pressureless sintering under a similar sintering schedule)—making this the strongest zirconia ceramics yet achieved. Strengthening of this material is based on the use of a dynamic oscillatory pressure during sintering to remove flaws and strengthen grain boundaries. We believe that this sintering process can be applied to manufacture many other ceramics with very high strength for structural applications.

 
Session CA-5 - Innovation in Manufacturing Technology

CA-5:IL02  High Performance of Ceramics and Manufacturing Process Innovation
YOSHIO SAKKA, National Institute for Materials Science, Japan Science and Technology Agency, Tsukuba, Japan

A new competitive funding program of “High Performance of Ceramics and Manufacturing Process Innovation” supported by Japan Science and Technology Agency (JST) has started since December 2016. This program is the “Industry needs response type” in A-STEP (Adaptable and Seamless Technology Transfer Program through Target-driven R&D) aiming to bolster Japanese industrial competitiveness by contributing to the solution of technical issues common in industry. NIMS project of “Fabrication of highly structure controlled ceramics through advanced fine powder processing” has been conducted for 10 years and related to the A-STEP projects. In this presentation, at first some researches on the innovative ceramic manufacturing processing in A-STEP program will be introduced. Through the process innovation based on basic science, it is expected to establish a generic technology and the breakthrough of the manufacturing process. Then some achievements in ceramic processing at NIMS such as colloidal processing under external fields and novel high-speed sintering techniques will be demonstrated. For the development of high-performance ceramics, feedback from advanced analytical technology, computer science, and simulations is crucial. JST works to accelerate innovative driven by close collaboration among industry, academia and government, and facilitated by a platform for dialogue among all three sections.


CA-5:IL03  Challenges in Scaling up Zirconia-based Bioceramics: From the Development of a Material at the Laboratory Scale to an Effective Industrial Production
H. REVERON¹, FEI ZHANG¹, M. FORNABAIO², P. PALMERO², L. MONTANARO², T. FÜRDERER³, N. COURTOIS⁴, J. CHEVALIER¹, ¹Université de Lyon-INSA de Lyon, MATEIS CNRS UMR 5510, Villeurbanne Cedex, France; ²Department of Applied Science and Technology, INSTM R.U. PoliTO, LINCE Lab., Politecnico di Torino, Torino, Italy; ³DOCERAM, MOESCHTER GROUP Holding GmbH & Co. KG, Dortmund, Germany; ⁴Anthogyr SAS, Sallanches, France

Y-TZP ceramics are considered suitable materials for aesthetic dental restorations and implants due to their toughness and strength properties. Nevertheless, their propensity to undergo Low Temperature Degradation in-vivo conditions (LTD or aging) is driving researchers to find new compositions to replace Y-TZP in the dental field. An innovative nano-powder engineering route able to produce fine powders for processing ceria-stabilized zirconia (Ce-TZP) bioceramics containing two second phases (alumina and strontium aluminate) was developed at the lab-scale. Optimized composition exhibited high biaxial strength (>1GPa), toughness >10 MPa√m, perfect hydrothermal stability (absence of aging) and very high flaw tolerance (Weibull modulus m=60) thanks to (a) a grain-refinement never achieved before, (b) the use of Ce instead of Y as stabilizing agent and (c) the possibility of adjust precisely the stabilization degree in final ceramics (from 10.0 to 11.5 mol% ceria). In this presentation we will show issues encountered when scaling-up the processing of these ceramics (cracking, density, microstructure and properties variations, etc.) to produce larger sizes and quantities required for the industrial production of dental implants.


CA-5:IL04  Advanced Ceramic Processing with External Magnetic Field
TOHRU S. SUZUKI, Ceramics Processing Group, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan

Tailored microstructure in ceramics is important for improving their properties. Especially, crystallographic orientation is expected to be effective way to utilize the anisotropic properties and to understand their properties as well. We have reported that the crystalline orientation can be controlled even in diamagnetic ceramics by a high magnetic field. A crystal with an anisotropic magnetic susceptibility rotate to an angle minimizing the system energy when placed in a magnetic field. In addition, the other processing can be used simultaneously to control the elaborate microstructure. Control of multi-axial crystalline orientation was achieved by both geometric effect and a magnetic field. These two effects are expected to control different axes of orientation in case the easy magnetization axis is different from the oriented axis by the geometric effect. We reported that bi-axial orientation could be achieved by slip casting of the platelet particles in a strong magnetic field where the c-axis of the platelet particle was aligned by the force of gravity, and the a- and b-axes were aligned by the magnetic field. We demonstrate that laminar composites with alternate crystalline-oriented layers are produced by electrophoretic deposition in a strong magnetic field.


CA-5:IL05  Machining Techniques to Prepare Complicated Shape Parts with Extremely Fine Details
F. PETIT, Belgian Ceramic Research Centre, Mons, Belgium

Fabricating ceramic parts with a high degree of complexity and fine details remains highly challenging. Additive manufacturing (especially stereolithography) is promising but it is still far from maturity. It suffers from a lack of reliability and cannot provide defect free parts except for very specific geometries. Hybrid manufacturing is a term that typically describes integration of multiple unit manufacturing processes into one machine. The combination of several technologies in one single device is meant to enable shorter processing time, reduced inspection time and handling while decreasing the cut production costs of products. It also aims at producing parts exhibiting a greater design freedom or intricacy and sometimes radical geometries that conventional manufacturing is not able to produce. In this presentation, an original hybrid manufacturing approach conceived for ceramics is presented. It combines in a single setup conventional CNC machining of ceramics in the green state with laser milling. This combination allows a dramatic reduction of the manufacturing time (at least by an order of magnitude) especially for parts exhibiting very fine and delicate features (< 0.2 mm). 
The European Regional Development Fund (ERDF) and Wallonia, are gratefully acknowledged for their financial support to these research projects: HAINOLASE and CERAMPLUS


CA-5:L06  Polymer - spinel Nanocomposites for Applications in Modern Sensors and Actuators
E. MARKIEWICZ, K. CHYBCZYNSKA, Institute of Molecular Physics PAS, Poznan, Poland; A. GRZABKA-ZASADZINSKA, S. BORYSIAK, Poznan University of Technology, Poznan, Poland

Composites are materials which consist of two or more phases of different properties. The properties of composites depend on the number of phases, their volume fractions, properties of individual phases and also on the way in which the phases are interconnected. Therefore, the properties of composites are neither the sum nor the mean of properties of constituent phases. The application of spinels (materials with magnetic order dependent on the method of preparation) as the phase dispersed in polymer matrix allows to obtain materials for application in many modern devices. This enables to eliminate permanent magnets of high mass and large dimensions in e.g. loudspeakers. The aim of this work was development of the preparation method of the composites consisting of cellulose matrix and spinel CoFe2O4 as well as the investigation of dielectric and magnetic properties of these materials. In order to obtain polymer – spinel nanocomposites the optimized planetary ball milling method was used. This method involves fragmentation of the ceramic and polymer powders using a planetary ball mill resulting in nanometer size of the particles characterized by large effective surface that substantially influences the macroscopic properties of the obtained material.
This work was supported by grant MINIATURA1(ID: 369709) from National Science Centre - Poland