Focused Session CB-9
Additive Manufacturing

Session CB-9.1 - Selective Laser Sintering
 
CB-9.1:IL01  How to Process Ceramics by Laser Beam Melting?
E. JUSTE, BCRC, Mons, Belgium

Additive manufacturing (AM) processes to build up complex shapes are becoming mainstream technologies for metals and polymers. Unfortunately, fabricating ceramics using AM methods is still challenging. There exists two main technological approaches to shape ceramics by AM: the first one is called indirect (stereolithography, robocasting, binder jetting…) and requires a post-thermal treatment to ensure consolidation of the parts. The second one, i.e. the direct one (laser cladding, selective laser sintering/melting…) aims at fabricating near net shape parts directly through in situ sintering or melting and without any other thermal post-treatments. Since many years, the Belgian Ceramic Research Centre is developping direct AM of ceramics using Laser Beam Melting. Adding colloidal graphite as an absorption promoter to the ceramic powder allows manufacturing complex parts (size up to 10 cm) with relative density about 97%. In this presentation, we review the main results obtained so far with a special emphasis on the influence of the powder bed packing density and recoater systems (wiper or roller) to fabricate alumina and alumina-zirconia based parts. The ERDF and Wallonia, are gratefully acknowledged for their financial support to these research projects: LASESURF and CERAMPLUS.


CB-9.1:IL02  Powder-based Additive Manufacturing at Micro-gravity
J. GUENSTER, A. ZOCCA, P. LIMA, J. LÜCHTENBORG, Bundesanstalt für Materialforschung und –prüfung (BAM), Berlin, Germany; T. MÜHLER, Clausthal University of Technology (TUC), Clausthal-Zellerfeld, Germany; M. SPARRENBERG, J. MELCHER, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Braunschweig, Germany

Many of the most successful and precise additive manufacturing technologies are based on the deposition layer-by-layer of a flowable powder. Just to cite the most well-known technologies, the “powder-based three-dimensional printing” and the “selective laser sintering (SLS)” or “selective laser melting (SLM)” processes all share the same layer deposition method: a flowable powder is spread layer by layer, while the layer information of the part is scribed or printed after each consecutive layer deposition step. Besides outstanding improvements in the development of new technologies and new material systems, little progress has been made on the stabilization and densification of the deposited powder, the so called powder bed. Generally, layer deposition requires gravitational forces acting on each particle as a prerequisite for compaction of the particles and formation of a smooth layer. We have introduced an additional force acting on the particles by establishing a gas flow though the powder bed. The presentation will introduce the gas flow assisted powder deposition as a novel, easy and economic approach for the stabilization of powder beds, which allows the printing of parts without the use of support structures and at micro-gravity.


CB-9.1:IL03  Laser Sintering of Ceramics
TEIICHI KIMURA, Japan Fine Ceramics Center, Nagoya, Japan

Laser sintering is a key technology for 3D printing / additive manufacturing of ceramics. We have developed two important techniques for laser sintering of alumina: (a) drying/dewaxing technique of slurry layer, and (b) effective laser heating technique. In this study, an alumina slurry containing sub-micron alumina powder was used as a starting material. By controlling temperature distribution in the coated slurry layer using a hot-plate heating, the slurry layer was dried and dewaxed without crack, and densely packed alumina powder layer (green density: 83~86%) was obtained. The dense powder layer was also obtained by spraying the slurry onto the pre-heated substrate. Nd:YAG laser (wavelength:1064 nm) was employed in this study as a heating source, but alumina poorly absorb this laser. We formed a graphite layer on the alumina powder layer as an absorption aid to assist the laser heating of the alumina layer, and 300 micron-thick layer was successfully sintered by 10 seconds irradiation at power density of 250 watt/sq-cm.


CB-9.1:IL04  Alumina Refractory Ceramic Molds Processed by SLM
D. DESCHUYTENEER, Belgian Ceramic Research Centre, Mons, BELGIUM

Traditional processes for the foundry molds fabrication need numerous and rather time-consuming steps. These processes are not really adapted to small series or prototypes. The research project exposed in this contribution proposes an alternative method combining the advantages of molding with those of the additive processes. For small series or prototypes, additive manufacturing by Selective Laser Melting (SLM) allows the building of molds in a very short time compared to the traditional investment casting method. This technique also permits the unique advantage to control the design of the shell thickness and structure in order to have a better control of the thermal fluxes during metal cooling. This would potentially ensure a better control of the casting defaults. In this presentation, improvement of molds built with alumina as raw material will be presented. Two metallic alloys have been tested : the first alloy chosen is AlCu4MgSi as low melting point alloy reference and the second is stainless steel 316L as high melting point alloy reference. Wallonia is gratefully acknowledged for their financial support to this research project.


CB-9.1:L05  Additive Manufacturing of Geopolymers by Local Laser Curing
P. HLAVACEK¹, T. MUEHLER², J. LUECHTENBORG¹, P. STURM¹, G.J.G. GLUTH¹, H.-C. KUEHNE¹, J. GUENSTER^{1, 2}, ¹Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany; ¹²TU Clausthal, Clausthal-Zellerfeld, Germany

For the additive manufacturing of large components typically powder-based methods are used. A powder is deposited layer by layer by means of a recoater, then, the component structure is printed into each individual layer. We introduce here the new method of local laser drying, which is a suspension-based method specially developed for the manufacturing of large voluminous ceramic parts. The structure information is directly written into the freshly deposited layer of suspension by laser drying. Initially, the technology was developed for ceramic suspensions, however, first experiments with geopolymers reveal a high potential for this class of materials. Metakaolin, fly ash and lithium aluminate-based one-part geopolymers were used in first experiments. The local annealing of the geopolymer slurry results in a drying and crosslinking reaction and, thus, in a local consolidation of the material. First parts made are introduced and their properties are discussed.

 
Session CB-9.2 - Laminated Object Manufacturing

CB-9.2:IL01  Laminated Object Manufacturing of Ceramic-based Composites
N. TRAVITZKY, University of Erlangen-Nuremberg, Dept. of Materials Science, Glass and Ceramics, Erlangen, Germany

The wide-use of advanced ceramic-based composites depends on the availability of industrial processing routes to fabricate parts with required geometries. Owing to the inability of current technology related methods to produce complex-shaped ceramic parts with the desired microstructures and properties, Additive Manufacturing (AM) is becoming an increasingly important approach. The mechanical properties of the materials fabricated by AM techniques such as Laminated Object Manufacturing (LOM), Fused Deposition Modeling (FDM), Robocasting (RC), Selective Laser Sintering, Melting and Curing (SLS, SLM and SLC), Stereolithography (SLA), and Three-Dimensional Printing (3D-Printing) in many cases are similar to the corresponding properties for commercially available ceramic-based materials fabricated by other methods. AM technologies can create parts using advanced materials that are superior to traditional ones. In this talk, the emphasis is placed on the fabrication of dense and porous, oxide as well as non-oxide ceramic-based composites with relatively complex geometries by LOM process, the associated problems addressed, and the possible routes to circumvent these problems highlighted. Microstructures and mechanical properties of the fabricated composites will be present.


CB-9.2:L03  Additive Manufacturing of AlN Based UV-curable Dispersions
P. OZOG^{1, 2}, D. KATA², T. GRAULE¹, ²Laboratory for High Performance Ceramics, Empa, Dübendorf, Switzerland; ²Faculty of Materials Science and Ceramics, University of Science and Technology, Cracow, Poland

The evolution of electronics toward more integration leads to a higher density of components, which is limited by thermal dissipation. Therefore, substrates with high thermal conductivity are of the interest. AlN ceramic is a good candidate for the substrates as it exhibits high thermal conductivity, higher than commonly used Al2O3, additionally it can be considered as the candidate for the preparation of heat exchangers. Tape casting is one of the well-known methods used for the preparation of the ceramic substrates. Current state of the art indicates that organic solvent and water based systems were developed for a tape casting for AlN powders. However, both systems include a time consuming drying step with the risk of crack formation and deformation during it. The use of UV-curable systems can ensure avoiding that problem. This study was aimed to develop an UV-curable system for tape casting of AlN powders. Dispersion was evaluated by rheological measurements to optimize the solid loading and dispersant concentration. Tape thickness, photoinitiator concentration and parameters of the UV-curing were analysed to evaluate their impact on the tapes quality. As a result, a UV-curable system for AlN powder was obtained and applied further in DMD based stereolithography technique.


Session CB-9.3 - Fused Deposition Modelling

CB-9.3:IL01  Thermoplastic- and Suspension-based Additive Manufacturing of Multi-material Components
U. SCHEITHAUER, E. SCHWARZER, S. WEINGARTEN, J. ABEL, H.-J. RICHTER, T. MORITZ, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany

For producing dense materials structures with a high level in mechanical properties Additive Manufacturing (AM) methods have to be used basing on suspensions and pastes allowing a very homogeneous distribution of ceramic or metallic particles and a possibly high volume content of powder in the suspension media. Three different technologies (Lithography-based Ceramic Manufacturing, Thermoplastic 3D-Printing, Fused Filament Fabrication) are used to develop new multifunctional components for different applications within different projects. The presentation will show the used production techniques in detail to illustrate the possibilities and advantages of these techniques concerning the combination of dense and porous structures in one component as well as the combination of different materials like stainless steel and zirconia in one metal-ceramic component. The benefits of this combination of Functionally Graded Materials (FGM) and Additive Manufacturing (AM) will be presented on the examples of different demonstrators.


CB-9.3:IL02  Materials and Processing Hybridization by Advanced Thermoplastic Additive Manufacturing
T. MORITZ, U. SCHEITHAUER, J. ABEL, A. MUELLER-KOEHN, A. GUENTHER, S. WEINGARTEN, A. MICHAELIS, Fraunhofer IKTS, Dresden, Germany

Most of the Additive Manufacturing (AM) techniques for ceramic components are suited for single material components only. However, multi material approaches would offer combining the advantages of AM, like incredible freedom in design, with the opportunity to multi functionalization. Different or opposing properties like electrical conductivity/insulation or different colors can already be combined by conventional powder technological routes. The contribution will show, how different materials like stainless steel and zirconia or black and white zirconia components can be combined by thermoplastic AM methods. Nevertheless, combining totally different materials remains challenging. The basic requirements for combining powdery materials by co-processing and co-sintering and how to meet these requirements will be discussed in the presentation. As potential multi component thermoplastic AM methods Thermoplastic 3D printing (T3DP) and Fused Filament Fabrication (FFF) will be introduced. A further benefit for individualization or customization of components can be expected from combining AM techniques with conventional shaping routes. Examples of combinations of tape casting and injection molding with each other and with AM processes will be introduced.


CB-9.3:L04  Ethylene Vinyl Acetate as a Binder for Fused Deposition Modelling of Ceramic
L. GORJAN¹, L. REIFF^{1, 2}, A. LIERSCH², F. CLEMENS¹, ¹Empa - Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland; ²Department of Materials Engineering, Glass and Ceramics, Hochschule Koblenz, Germany
 
Fused filament fabrication (FFF) is widely used technique for 3D printing of various thermoplastic polymers. It has been also applied to ceramic shaping, where filaments are made from thermoplastic feedstocks with high ceramic powder content (>45 vol%) in the binder.  We studied the behavior of different grades of Ethylene Vinyl Acetate (EVA) co-polymers as thermoplastic binders for tricalcium phosphate (TCP). Stearic-palmitic acid was used as a processing aid. Different grades of EVA showed large differences in FFF and binder burn-out behavior. Some resulted in feedstocks which quickly blocked the printing head, whereas other feedstocks could be printed without interruption. This thermo-rheological phenomenon is not yet fully understood. Excellent fusion between the different layers of 3D printed parts was achieved by all tested feedstocks and no defects could be at interfaces. The addition of stearic-palmitic acid affects the viscosity and the yield point of molten feedstocks, as well the flexibility of the solid filament. Yield point is increased by the addition of stearic-palmitic acid which significantly improves the shape stability. The effect is more pronounced for EVA grades with lower molecular weights. EVA binder system works well for thin and small parts, made with nozzle diameter below 0.25 mm. removing binder from thick parts is challenging, because of the formation of dense skin during the first stages of EVA decomposition.


Session CB-9.4 - Stereolithography

CB-9.4:IL01  Microstereolithography Applied to Biomedical Devices
A. LERICHE, M. DEHURTEVENT, S. CHAMARY, H. CURTO, A. THUAULT, J.C. HORNEZ, Laboratoire des Matériaux Céramiques et Procédés Associés, Université de Valenciennes, Maubeuge, France; F. PETIT, F. CAMBIER, Belgian Ceramic Research Centre, Mons, Belgium; M.H. FERNANDEZ, Laboratory for Bone Metabolism and Regeneration, Universidade do Porto, Portugal; F. MONTEIRO, INEB, Universidade do Porto, Portugal

The current trend in medical devices is to make custom-made prosthesis to meet the needs at best of the patient. In this context, the microstereolithography technology is more and more used to fabricate bioceramic devices. Indeed, this technology allows the fabrication of a few number of small size complex shaped parts at very short time and makes it possible reliable restorations with accurate dimensions without waste of raw materials and without any milling step. In this talk, we will focus on the manufacturing of two medical devices: the dental crowns in dense alumina or zirconia and the porous calcium phosphate bone substitutes. Firstly, the impact of the manufactured layer orientation on the mechanical properties of alumina and zirconia parts for dental crown application will be described. For bone substitutes, it is well known that the morphology of the porosity of the scaffold strongly influences the cell invasion and differentiation. As the stereolithography allows the achievement of any shape porosity, porous calcium phosphate parts characterized by different shape and size porosities were fabricated and the influence of the porous architecture on cell invasion will be discussed. The rapid densification of these scaffolds by microwave sintering will be also presented.


CB-9.4:IL02  Printing and Characterization of Dense Oxide Ceramics using Lithographic AM
J. VOGT, T. MARTINI, M. STEPANYAN, Fraunhofer Center for High-Temperature Materials and Design (HTL), Bayreuth, Germany

Lithographic AM has recently established itself as the state-of-the-art printing technique to achieve highly complex and dense technical ceramic parts. In order to further exploit its massive potential for the future AM of technical components, it is essential to manage and optimize the diverse steps in the process chain. The adjustment of the optical properties of the light-curing slurry formulations allows for the production of mutually adherent and defect-free green layers during the layerwise printing process. Suitable-to-AM and suitable-to-ceramic part design as well as optimized part orientation enable smooth printing and thermal cycle processes. Microscale computed tomography (µ-CT) is used to optimize the printing process itself, as pores, delamination and variations in green density can be detected right after the printing and cleaning. The subsequent thermal cycling processes for debinding and sintering are a challenge regarding the high amount of binder in the green parts and the frequently fragile structures of the printed parts. Using thermooptical measuring devices and computer simulation, optimized heating processes with a lower time and energy consumption are developed providing maximum part quality.


CB-9.4:IL03  Stereolithographic Additive Manufacturing of Ceramic Groove Chambers for Stream Lines Modulations of Energy and Material Flows
SOSHU KIRIHARA, Osaka University, Joining and Welding Research Institute, Osaka, Japan

Stereolithographic additive Manufacturing was customized to create micro ceramics components. Photo sensitive acrylic resin with alumina of 200 in diameters was spread on a glass substrate with 5 to 10 μm in layer thickness by using a mechanical knife edge. Cross sectional layers patterned by ultraviolet laser scanning of 10 to 100 μm in variable diameter were laminated to create composite precursors. Dense components could be obtained through dewaxing and sintering heat treatments. Through the computer aided design, manufacturing and evaluation, Acoustic cavities with self-similar bellows patterns were successfully fabricated for harmonic modulations of high frequency noises from thermal spraying guns. Subsequently, liquid channel with fluctuated inner walls were formed to decrease flow resistances effectively. Moreover, micro wave guides with inner spiral sulcus were processed to diffract electromagnetic waves in terahertz frequency ranges.
 

CB-9.4:L05  Development of Ce-TZP-Al2O3 based UV Sensitive Resin for Stereolithography
S. CAILLIET, M. ROUMANIE, R. LAUCOURNET, Université Grenoble-Alpes, Grenoble, France and CEA, LITEN, DTNM, SERE, LRVM, Grenoble, France; G. BERNARD-GRANGER, Université Grenoble-Alpes, Grenoble, France and CEA, DEN, MAR, DRMC, SFMA, DIR, Bagnols-sur-Cèze, France

In dental field, many technologies exist to produce dental parts, such as handmade production, subtractive manufacturing (SM) and additive manufacturing (AM). Stereolithography (SLA) is an AM technology which allows to produce, within a short time, unique, accurate and dense objects, while limiting the loss of matter contrary to SM. It is a layered manufacturing process based on the polymerization of an UV photocurable mixture composed of an UV sensitive resin (SR) highly loaded with ceramic particles. In dental technical area, Yttria-doped tetragonal zirconia polycrystal (Y-TZP) is one of the most used materials. Y-TZP is also used in SLA process, and has been chosen as reference material. But, due to a poor behavior to hydrothermal degradation (HD) other materials must be considered such as Ceria-doped tetragonal zirconia polycrystal (Ce-TZP). However, Ce-TZP shows lower flexural strength values. To improve mechanical properties of Ce-TZP, alumina is added to create Ce-TZP – Al2O3 composites. Such composites, according to their properties, seem to be better candidates in the dental field. Development and characterizations of Y-TZP based UV SR and composite based UV SR will be presented as well as mechanical properties obtained for both formulations.


CB-9.4:L06  Development of Photo-curable Ceramic Resin with High Dispersion Stability for SLA 3D Printing Application
SE YEON SONG^{1, 2}, JUNG WOO LEE¹, JI SUN YUN¹, ¹Electronic Convergence Materials Division, Korea Institute of Ceramic Engineering and Technology, Jinju, South Korea; ²Department of Materials Engineering, Pusan National University, Busan, South Korea

Research on the improvement of dispersion stability of Al2O3 ceramic particles has been carried out for the development of photo-curable ceramic resin for stereolithography (SLA) 3D printing application. The Al2O3 ceramic particles were initially coated by silane coupling agent (VTES, vinyltriethoxysilane) based on hydrolysis and condensation reactions, and then VTES-coated Al2O3 ceramic particles were highly dispersed in photopolymer (3DK-A83B) by interpenetrating network (IPN) phenomena. The surface morphology and average coating thickness of VTES-coated Al2O3 ceramic particles were observed by field-emission transmission electron microscopy (FE-TEM), and the particle size distribution of VTES-coated Al2O3 ceramic particles was investigated by laser scattering particle size distribution analyzer. Turbiscan and relaxation NMR results confirmed that there is the optimum coating condition for better dispersion stability and dispersibility. The cross-sectional images of 3D-printed objects with the VTES-coated Al2O3/3DK-A83B composite solution with Al2O3 of 40 wt% were observed by field-emission scanning electron microscopy (FE-SEM), and the volume shrinkage of 48% was observed after the sintering process.


CB-9.4:IL07  Manufacturing of Multimaterial Parts using Hybrid Additive Manufacturing Machine
C. CHAPUT, 3DCeram, Limoges, France; T. CHARTIER, SPCTS, CNRS/University of Limoges, Limoges, France

3D printing lets users push back production limits. Ceramics are no exception to the rule. To open up this technology to a wider spread of professionals, multi-function parts (e.g. 3Doptic system for space application for example) requiring multi-material solutions, have to be manufactured by additive manufacturing. In this respect, hybrid machines are able to print several materials at the same time and can manufacture smart design parts. This new generation of printer combines a considerable advance in additive manufacturing technology and changes the manner of producing 3D parts. It will increase the offer and open a larger market, proposing a real alternative to traditional manufacturing techniques, allowing to print multi-materials at the same time.


CB-9.4:IL08  State of the Art in Stereolithography of Ceramics
J. HOMA, M. SCHWENTENWEIN, Lithoz GmbH, Vienna, Austria

Lithographic additive manufacturing (AM) technologies are based on the concept of photopolymerization and distinguish themselves among other AM techniques by very high precision and good surface quality. They have also been applied for AM of ceramics, by dispersing ceramic particles in a photoreactive binder and by polymerizing the layers either by mask exposure (DLP-based) or scanning (laser-based). Another criterion is the exposure direction; it can be either from the top, where the part is lowered into a vat and a paste is spread layer by layer, or from the bottom, where the part is drawn out of the vat and the layer is polymerized through the transparent vat. This presentation will show and compare all different variations and highlight their advantages and drawbacks. Lithographic AM is the most widespread technology for high-performance ceramics, due to the high precision and good materials properties, which are achieved through the high green density because of the use of highly filled slurries and through the two-stage process (shaping and sintering are separated). Nonetheless, the strength of the printed samples is often dependent on the building direction. This presentation will outline this dependency and will show different effects on the strength of ceramic AM parts.


CB-9.4:L09  Development of a Numerical Simulation Model for Predicting the Curing of Ceramic Systems in the Stereolithography Process
J. TARABEUX, V. PATELOUP, P. MICHAUD, T. CHARTIER, SPCTS - UMR CNRS 7315, Limoges, France

The control of ceramic green parts dimensions produced by stereolithography is a central concern of the additive manufacturing industry. The presence of ceramic particles within the photopolymerizable system induces UV-laser beam scattering phenomenon, disrupting the polymerization process. This study focuses on the development of a numerical simulation model of the curing process, considering the scattering phenomenon. Experimentation on a commercial photopolymerizable Al2O3 paste makes it possible to support the development of the model and its validation. Firstly, a design of experiments is conducted to reduce the number of experiments. Thereafter, material-dependent parameters are identified through simulations and experimental measurements, and a scattering law is proposed. Finally, the model enables to simulate the cure width and the cure depth. It also provides visualization of the exposure distribution and the scattering phenomenon. Considering the accuracy of predicting curing for 75 % or more of the experiments, the simulation model is validated. Moreover, it might be suitable for other photopolymerizable ceramic systems since the approach used is not specific to the Al2O3 material.

 
Session CB-9.5 - Direct Writing

CB-9.5:IL01  Solvent-free Direct Deposition of Ceramic Components for Energy Application
HIROYA ABE, Osaka University, Ibaraki, Japan

We present the solvent-free direct deposition methods of ceramic components for SOFCs electrochemical electrodes, based on mechanical assistance. NiO–YSZ nanocomposite particles were synthesized and deposited on a dense YSZ substrate using an attrition-type milling apparatus. The NiO–YSZ nanocomposite porous films were successfully fabricated from the nanocomposite particles with high specific surface areas. In this deposition, the nanocomposite particles were mechanically dispersed in air, resulting in fine aggregates (~100 nm in size). Then, they were mechanically impacted on the substrate (collision speed, ~30 m/s). By the subsequent sintering of the nanocomposite film, the finely constructed three dimensional NiO – YSZ network structure was formed, and its reduced Ni–YSZ porous film showed an excellent SOFC anode performance.


CB-9.5:L02  Aerosol Jet® Technology for Printed Electronic Devices Comprising Ceramics
M.A. PIECHOWIAK¹, G. ETCHEGOYEN¹, A. DELAGE², N. DELHOTE², A. ABDELGHANI², ¹Centre de Transfert de Technologies Céramiques (CTTC), Limoges Cedex, France; ²Laboratoire XLIM - UMR CNRS 7252 - Université de Limoges, Limoges Cedex, France 

Direct-writing digital printing techniques are of great interest for telecommunication and electronic industry. One of the emerging non-contact technologies is the Aerosol Jet® printing technique. The main advantage of this technology is the capacity of conformal and high-resolution printing of various ink compositions with wide range of viscosity. The aerodynamic focusing of an aerosol stream opens the possibility of printing onto nonplanar, inclined or curved substrates. The Aerosol Jet® is used mainly for deposition of electric 2D conductive structures but can be also applied for fabrication of multilayered devices comprising conductors, plastics as well as functional ceramics (dielectrics, magnetics, insulators, piezoelectrics…). The Aerosol Jet® printing is here tested as a potential accurate solution for elaboration conductive high resolution parts of sensors as well as low temperature cofired ceramics (LTTC). Results showing the typical accuracy and capability of the technology when printing onto 3D ceramic additive manufacturing will be presented. Millimetre wave measurements will be presented to determine suitability of this technology for very high frequency (up to 100 GHz and above) applications.


CB-9.5:L03  Direct 3D Printing of Aluminum Nitride Using Ovalbumin As The Natural Binder
WAI HOONG KOK¹, K.C. YUNG¹, T.C. ANG², ¹Department of Industrial and Systems Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong; ²School of Material Science, Nanyang Technolgy University, Singapore

Aluminum nitride is regarded as a good ceramic material for high power electronic substrate mainly due to its high thermal conductivity and low electrical conductivity characteristics. The conventional process for making aluminum nitride substrates is by casting, mainly tape casting, where aluminum nitride green sheets produced will be cut to the desired shape and sizes. 3D printing allows the production of highly customized and complex structures with the minimum use of raw material. However, current 3D printing of ceramics mainly produces porous structures. The objective of this study is to produce 3D structures by direct printing of highly dense aluminum nitride using ovalbumin as the natural binder. This green ceramic manufacturing approach produces parts with a high relative density of up to 80% and thermal conductivity of 17 W/mK. Shrinkage of 18% was observed and rheology of the slurry with respect to the particle size was also studied.

 
Session CB-9.6 - Other/Emerging AD Routes

CB-9.6:IL01  Layerwise Slurry Deposition for Additive Manufacturing of Ceramics
A. ZOCCA, P. LIMA, J. LÜCHTENBORG, J. GUENSTER, BAM Federal Institute for Materials Research and Testing, Berlin, Germany; T. MUEHLER, Clausthal University of Technology, Clausthal Zellerfeld, Germany

Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of SLS/SLM and 3DP technologies for advanced ceramic materials. LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade. Each layer is deposited and dried to achieve a highly packed powder layer, which can be used for SLM or for 3DP. This technique offers high flexibility in the ceramic feedstock used, especially concerning material and particle size, and is capable of producing parts with physical and mechanical properties comparable to traditionally shaped parts. In this presentation, the LSD technique will be introduced and several examples of application to porcelain, SiC and alumina products will be reported.


CB-9.6:L02  Additive Manufacturing of Dense and Adherent Ceramic Coatings by Powder Deposition without Sintering
I. NOMEL^{1, 2}, F. BERTHOIX¹, O. DURAND¹, P. MARCHET², ¹Center for Technology Transfer in Ceramics, Limoges Cedex, France; ²Institute of Research for Ceramics, Limoges Cedex, France

At CTTC we have developed an innovative coating technology (called INPACT), based on the Aerosol Deposition Method [1] (ADM) The principle of ADM is to project an aerosol of dry particles onto a substrate through a supersonic nozzle. The kinetic energy of particles implies fragmentation and a cohesion phenomenon coupled with local thermal losses. Although the consolidation mechanisms are not yet fully understood, ADM is a low-cost method for the fabrication of dense films without any sintering. A huge innovation could be the manufacturing of dense ceramics on new kinds of substrates including low melting temperature materials like plastics for electronic applications. Our present development is focused on the manufacturing of multi-layered material without any co-firing step for energy storage applications. In that scope, the INPACT project has led to the development of a Computer-Aided Manufacturing (CAM) machine [2], in order to get complex 2D-3D-shapes. The presentation aims to show the potential of the INPACT technology through examples of ceramic layers and related properties.
[1] J. Akedo, Journal of Thermal Spray Technology 17 (2) 181-198 (2008); [2] Patent US2014/0291885 A1.


CB-9.6:L03  Additive Manufacturing of Dense Ceramics with Laser Induced Slip Casting (LIS)
J. LUECHTENBORG, A. ZOCCA, J. GUENSTER, Federal Institute for Materials Research and Testing (BAM), Division 5.4 - Ceramic Processing and Biomaterials, Berlin, Germany; T. MUEHLER, Clausthal University of Technology (TUC), Institute of Non-Metallic Materials, Clausthal-Zellerfeld, Germany

Most additive manufacturing processes which produce dense ceramics are nowadays limited in size because of inevitable post-processing steps like for example binder removal in stereolithography. The additive manufacturing of voluminous ceramic parts is realized by powder bed based processes which, however, generate parts with residual porosity. Via infiltration these parts can be processed to dense parts like for example SiC but this is not possible for all ceramics like for example Si3N4. There is a lack of methods for the additive manufacturing of dense voluminous parts for most ceramics. We have developed a new additive manufacturing technology, the Laser Induced Slip casting (LIS), based on the layerwise deposition of slurries and their local drying by laser radiation. Laser Induced Slip casting generates ceramic green bodies which can be sintered to dense ceramic components like traditional formed ceramic powder compacts. We will introduce the LIS technology, green bodies and sintered parts will be shown and their microstructure and mechanical properties will be discussed.


CB-9.6:IL05  Laser-based Additive Manufacturing for Medical Applications
R.J. NARAYAN, UNC/NCSU Joint Department of Biomedical Engineering, Raleigh, NC, USA

Additive manufacturing, which also known as 3D printing, involves processing of three-dimensional materials and/or systems via a layer-by-layer approach. Several additive manufacturing techniques have been developed over the past three decades that involve processing of filaments, powders, or liquids. Over the past decade, additive manufacturing techniques have been used to create patient-specific structures or biologically-friendly structures that are difficult to create using conventional methods. For example, data obtained from computed tomography, magnetic resonance imaging, or other imaging techniques may be utilized to create patient- specific structures. These customized structures may include appropriate geometries for a given medical condition. Surface features may be incorporated into customized structures to promote appropriate cell-device interactions. In this talk, the use of laser-based additive manufacturing techniques to create tissue engineering scaffolds, drug delivery devices, and sensors will be described. Chemical, mechanical, and biological characterization of the the additive manufacturing-processed structures will be described. Finally, challenges associated with the clinical translation of additive manufacturing techniques will be considered.


CB-9.6:IL06  Creation of Dense Technical Ceramics by Powder Bed Three Dimensional Printing
P. GINGTER, A. LYNEN, J. HEYM, Schunk Ingenieurkeramik GmbH, Willich-Münchheide, Germany

Powder bed three dimensional printing enables the efficient production of prototypes as well as the creation of complex shaped final products, which may not be realized by established shaping techniques. One main drawback of the technology is the immanent porosity of printed green bodies, which prevents full densification in subsequent sintering cycles. In contrast to the vast majority of technical ceramics, this porosity is not an obstacle for the production of dense and mechanically loadable components made of reaction bonded silicon carbide. Prerequisite to create parts by three dimensional printing, which are not inferior to convention-ally produced components, is the stability of process as well as ambient conditions. The presentation will highlight some of the most important control and disturbance variables to-gether with their potential impact on printing process and part properties. By means of select-ed examples the capabilities of our patented process will be highlighted.


CB-9.6:L07  Digital Printing of Glass-ceramic Glazes
M. CANNIO¹, D.N. BOCCACCINI¹, V. RIVA¹, M. HANUSKOVA¹, M. ROMAGNOLI¹, R. TAURINO², F. BONDIOLI², M. TOGNETTI³, M. CICCONI⁴, T. FEY⁴, V. NOVARESIO⁵, A.R. BOCCACCINI⁶, ¹Dipartimento di Ingegneria Enzo Ferrari, Università di Modena e Reggio Emilia, Italy; ²Dipartimento di Ingegneria e Architettura, Università di Parma, Italy; ³Daxel S.r.l., Rubiera RE, Italy; ⁴Institute of Glass and Ceramics, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Erlangen, Germany; ⁵ALLOVIS Engineering, Torino, Italy; ⁶Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Erlangen, Germany
 
The outstanding versatility showed by Inkjet printing has turned it into a leading technology in several industrial manufacturing fields like ceramic tile decoration. Several papers in literature have set the rheological and fluid dynamics characteristic of the inks and the process parameters required for an optimum deposition for ceramic tile decoration, however  there is a lack of studies investigating the conditions for the deposition of glass-ceramic glazes.  The digital glazes objects of the present study are intended for digital injection systems using printheads working in the Drop On Demand system (DOD) based on piezoelectric elements or other digital injection techniques such as continuous ink jet (CIJ), electrovalves, pistons or others. The purpose of this work is to study the influence of chemical composition, mineralogy, particle size distribution, sedimentation rate and agglomeration phenomena, acting on stability over time and jetting ability on the performance of these glazes, experimentally and by computer simulation. Relevant parameters like viscosity, surface tension, zeta potential, solids loading, fluid mechanics numbers will be discussed to focus on the peculiarities of digital glaze deposition technology and the remaining challenges for the near future.