UMR CNRS 7315

Additive Manufacturing: a new way to elaborate complex ceramic parts

Thierry Chartier

Science of Ceramic Processing and of Surface TreatmentsLimoges - France

http://www.unilim.fr/spcts

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Numerical technologies used to fabricate (useful) objects directly from CAD data sources

Additive technologies generally use a layered procedure

Main advantages Reduced cost – Do not require tooling (prototype – short-run

production) Reduced time to market Complex shapes and specific architectures Able to build miniaturized parts with a high dimensional definition

(µwaves components, MEMS…) Allows to test a material with a small number of parts Flexible technique with the ability to directly redesign parts in the

CAD file to optimize a property, a shape, a dimension, restricted by conventional manufacturing methods

Additives Technologies

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Additive manufacturing

Additive manufacturing techniques will open new ways of thinking about objects design and fabrication

J. Cesarano, Sandia National Laboratories

From potery to advanced ceramics

Robocasting: computer controlled deposition of a ceramic system through a syringe

Rapid Prototyping and Solid Freeform Fabrication toward Additive Manufacturing

Additives Technologies

Julia Greer, Caltech, USA

(a)

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Systems installed at the end of 201338% USA - 23% in Europe – 22% Asia(Wholers’ 2014 report)

Since 1990s, Additive Manufacturing grew slowly. It was a niche of solution, often expensive for manufacturing

Explosion in additive manufacturing in 2013. President Obama said:“Additive manufacturing has the potential to revolutionize the way we make almost everything”

Direct fabrication of useful parts is increasing of about 30% per year

Additives Technologies

Other 12,3%Russia 1,4%

Taiwan 1,5%

China 8,8%

Korea 2,5%

Japan 9,4%

Spain 1,3%Italy 3,5%

UK 4,3%

Sweden 1,2%France 3,3%Germany 9,1%

Canada 1,9%

Turkey 1,4%

US 38,0%

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Main Additive Technologies used in the ceramic domain

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• Material extrusion (Fuse Deposition Modeling - Robocasting):material is selectively dispensed through a nozzle or orifice

Resolution: diameter filament extruded

• Material jetting (Ink-jet printing): droplets of build material are selectivelydeposited

ExOne, Houston, USA

J. Cesarano, Sandia National Laboratories

SPCTS, Limoges, France

Ceradrop, Limoges, France

Main Additives Technologies used for ceramic fabrication

2,5 D method

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• Binder jetting (3D Printing)a liquid binder is selectively deposited to consolidate a powder bed

M. Cima, MIT, USA

Main Additives Technologies used for ceramic fabrication

Voxeljet, Friedberg, Germany

Deposition homogeneous thin layer

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Courtesy David Huson - Centre for Fine Print Research University of the West of England

3D Printing used in ceramic tableware to fabricate concept models in physical form - advantage to speed up the design process- allows many iterations of the design idea to suit the customers needs

Main Additives Technologies used for ceramic fabrication

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• Selective Laser Sintering: thermal energy (IR laser) selectively (pre)sinters regions of a powder bed

Main Additives Technologies used for ceramic fabrication

Layer-wise Slurry Deposition (LSD)

laser treatmentlayer formationslurry preparation

H2O

powder

cleaning

waterlaserbeam

selective laser sintering

Specific merits of the LSD process low-cost raw materials with low content of organics powder bed density > 60% (slurry) - strong support for the part to be built simple, robust and inexpensive technology easy process upscale for parts large in size

Phenix systems, Riom, France

Courtesy Jens Günster

Deposition homogeneous thin layer

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LSD: Adapted to the fabrication of traditional ceramics

Courtesy Jens Günster

80 m

m

Porcelain Prototype Laser sintering of conventional slurry820 layers (100μm thickness) - 20hEnergy consumption laser: < 4 kWh material cost: < 1€

J. Günster, S. Engler, J. G. Heinrich, Forming of Complex Shaped Ceramic Products via Layer-wise Slurry Deposition (LSD). Bull. Eur. Ceram. Soc. 1 (2003), 25.T. Muehler, J. Heinrich, C. M. Gomes , J. Günster: Slurry-based Additive Manufacturing of Ceramics. Int. J. Appl. Ceram. Technol. 13 MAY (2013) DOI: 10.1111/ijac.12113

Main Additives Technologies used for ceramic fabrication

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• Sheet lamination (Laminated Object Manufacturing (LOM)): Sheet of material are bonded to form an object

Curved Layer LOM - Un. of Dayton, Ohio, USA

Cutting (laser), stacking, lamination of tape cast green sheets

Indirect: Lamination on a paper laminatedmandrel

3DCeram, Limoges, France

• Photopolymerization (stereolithography): reactive system is selectively cured by light-activated polymerization

Main Additives Technologies used for ceramic fabrication

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Stereolithography (SL)

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1. Creation of the 3D CAD file of the part

2. Export to .STL file and 3D model slicing in cross-sectional layers (interplane spacing = deposited layer thickness) Conditions of fabrication generated

3. Printing layer by layer 4. Cleaning, debinding and

sintering 5. Finishes

Space-resolved UV polymerization of cross-sectional patterns of a reactive system: suspension of ceramic particles in sensitive monomer/oligomer

Process overview

Stereolithography (SL)

Layer thickness: 25 – 150 µm depending on the reactivity and definitionResolution: 80 µmFabrication speed: 100 layers/hour

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Polymerization of each cross-sectional pattern by a deflected UV laser beam

First development:High concentrated ceramic-based systems, with a suitable rheology (shear- thinning, high yield-value)

Scanning system

Spreading system

UV Laser beam

Part under construction – Self supported stack

Paste reservoir64 vol.% Al2O3 - d50 = 1.4 µm

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Sufficient reactivity- Cure depth (CD): Processing time- Mechanical properties of the

green part

Concentrated suspensions- Cohesion during debinding- Sintering- Deposition of thin layers

Limit scattering phenomena- Cure width (Cw): Dimensional resolution

SL and µ-SL suspensions

UV reactivity

Interaction with UV light

Rheology

Requirements

Stereolithography (SL)

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• Formulation – Choice of components

Reactive system - Formulation

Powder + dispersant + oligomer + diluent + photoinitiator

Curable resin (oligomer: acrylate)

Reactive diluentDecrease viscosity (powder loading)HDDA (1,6-hexane diol diacrylate) (η =8 mPa.s, 2 functional)

PhotoinitiatorCuring process at 365 nm wavelengthBenzophenone derivative

High reactivity (EC < 10 mJ.cm-2)

High mechanical strength (3 functional)

Low viscosity (< 200 mPa.s)

Low shrinkage during polymerization

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Cure depth and cure width

CD – cure depth

Ei – incident energy

Ec – critical energy for polymerization

Dp - penetration depthcharacteristic of the system = f (particle size, volume fraction, refractive index…)Takes into account scattering phenomena that control both the cure depth and the dimensional resolution

Cw – cure width

2ω0 – spot diameter

Dimensionnal resolution

1 layer1 scanning

CD

Cw

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p

Dw D

CC2

2 0

c

ipD E

EDC lnDimensional resolution

0

100

200

300

400

500

600

700

800

900

10 100 1000 10000

Poly

mer

ized

thic

knes

s (µ

m)

Ei (mJ.cm-2)

05 vol.%10 vol.%15 vol.%20 vol.%30 vol.%40 vol.%50 vol.%

150

200

250

300

350

400

450

500

0 10 20 30 40 50 60

Poly

mer

ized

wid

th (µ

m)

Silica concentration (vol%)

The polymerized thickness (time of fabrication) is decreasing and polymerized width (dimensionnal resolution) is increasing with the concentration of ceramic (inert and scattering) particles

Powder loading

• Silica loaded suspensions (d50=2.25µm)

Polymerized thickness in agreementwith the Beer Lambert law:

Ei=156mJ.cm-2

smaller penetration of the beam (Dp) and light scatteringcaused by particles 18

c

ipD E

EDC lnp

Dw D

CC2

2 0

Cure depth when: - optical contrast (npowder/nresin) - d50 (increase of scattering centers at constant vol%)

Interaction of the UV light with the loaded resin controlled byscattering phenomena

The refractive index ratio (powder/resin) is an important parameter governing the light scattering

nSiO2 1.56Al2O3 1.79ZrO2 2.25Resin 1.49

Material – Particle size

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Al2O3

Examples of applications of Stereolithography

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Controlled porous structure for: tissue adhesion and bone anchorage

(osteointegration) mechanical strength

HAP parts implanted at Limoges HospitalScanner data of the patient

Simulation / creation of the implantSurgeon demand

Biomedical (SL)

3D implant realized from scanner data

HAP Biactive Implant with a perfect integration without inflammation ideally suited to the morphology of the patient:

aesthetical results

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Intervertebra bone substitute Occular implant

Clinical CaseAge : 40 yearsSex : MaleSurgery date : 09/06/06Surgery duration : 120 minImplant surface : 9 x 7 cmImplant thickness : 5 mmFixation holes : 8 + 3Topography : Frontal

Dielectric resonator shielded in an alumina metallized cavity

S21

(dB)

Frequency (GHz)

Simulation

TE110 cavity mode

TM111 cavity mode

DR

Measurement

(a) Precise position of the resonator inside the cavity

Compact device and easy to be integrated on a substrate carrier by classical route

High quality factor (Q0=4300 -12GHz)

Telecommunication (SL)

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(a)

20.5 mm

S 11 sim.

S21 sim.

S 21 meas.

S 11 meas.

(c)

Frequency (GHz)

S (d

B)

Experimental (meas.) - Simulated (sim.)

Bandpass

Electromagnetic Band Gap (EBG) waveguide for antenna• Periodic structures (photonic crystals) allow the existence of frequency bands for which waves cannot be propagated (forbidden band)• The introduction of a structural defect in this periodic structure works like a waveguide

Open new horizons in the conception of resonant devices

|S| (

dB)

S11

S21

3D pyramidal 4-pole filters and collective Ku bandpass (17.5GHz) alumina filtersMany filters within a single ceramic part

Gold metallization (sputtering technique) + laser etching

1mm

500µm

100µm

Telecommunication (SL)

Low insertion loss filter working around 17.5 GHz.

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Coupling filter and antenna

Industry: ex. Production of SynGaz (SMR)Steam reforming

CH4 + H2O CO + 3 H2

(850°C, 20 bars)

Water gas shiftCO + H2O CO2 + H2 +

Reactor

Metallic tubes + catalyst charge

SMR plantIntensification of process

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Luxury

Conclusions

Stereolithography makes it possible to fabricate useful complexobjects with high dimensional accuracy, difficult even not possible toachieve by conventional routes

Towards direct production of applicable parts with useful final propertiesAdditive technologies become true fabrication processing methods

Open the way to new functions or improved properties and to thinkabout objects design and fabrication

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Bottom-up

Molecularself-assembly (e.g. EISA)

Structural elements + « Interfaces/Interphases »

1 µm

Top-down ApplicationsAdditive

manufacturingmethods

FundamentalStructure of

colloidal suspensions

SPCTS Laboratory

Particle interactions

VR

VA

VT

Distance

InterparticlePotential Electrostatic

van der Waals

Combining top-down and bottom-up fabrication approaches is a greatchallenge but it opens outstanding opportunities

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Web: http://www.unilim.fr/spcts

Thank you for your attention