Lithography based additive manufacturing of structural and functional ceramics

Transcription

1 Lithography based additive manufacturing of structural and functional ceramics Dipl.-Ing. Sonja Baumgartner Christian Doppler Laboratory Photopolymers for Digital and Restorative Dentistry

2 StereoLithographic Ceramic Manufacturing Additive manufacturing: selective light curing of photosensitive monomer slurries Inorganic filler materials (ceramic powders) Filled green parts used as polymer/ceramic composites or (after thermal post processing) dense ceramic parts!

3 Processing DLP Light engine: 460 nm Resolution: ~25 µm Building size: 77x44 mm Laser Diode-laser: 375 nm, 405 nm Resolution: ~15 µm Building size: 100x100 mm Combination I: Laser + Light engine Resolution: ~ 20 µm Building size: 144x90 mm Combination II: DLP + Inkjet Resolution: 360 dpi

4 Exposure strategies 1 Light Source: LED 460 nm (a), Diode-Laser 405 nm (b) 2 DMD Chip (dynamic mask) (a), Beam expander (b) 3 Optics (a), Laser Scanner (b) 4 Coating system 5 Tiltable vat 6 Building platform 7 Back light Manufactured part 8 5 "Lichthärtende Schlicker für die stereolithographische Herstellung von Dentalkeramiken"; US (B2) b Device and method for processing lightpolymerizable material for the layered assembly of molds, WO Method and device for generative production of a mould with non-planar layers, EP (A1) Device and method for processing lightpolymerizable material for building up object in layers, WO (A1) 2a 3a 1a 1b 2b

5 Postprocessing Debinding up to ~450 C Sintering up to ~1600 C past printing past drying past debinding past sintering Solvent Binder, Polymer matrix Inorganic filling material (up to 48vol%) Dense ceramic part (> 99,5% th. density) R. Gmeiner, G. Mitteramskogler and J. Stampfl, Int. J. Appl. Ceram. Technol., 1-8 (2014)

6 Workflow Printing Process Debinding Sintering Testing 3D CAD Model (STL)

7 Process Parameters Support structures Sintering Testing Debinding Printing Process 3D CAD Model (STL) Rheoplus 90 Slurry development viscosity coater designs Pa s C RG/73_492_6_30 C 1; RG/ ; CP25-1-SN185 RG/73_492_6_40 C 1; RG/ ; CP25-1-SN185 RG/73_492_6_50 C 1; RG/ ; CP25-1-SN185 RG/73_492_6_60 C 1; RG/ ; CP25-1-SN185 RG/70_492_AFG_D540_ ; CP25-1-SN RG/70_492_AFG_D540_ C /s 100 Scherrate. 40 C 60 C ; CP25-1-SN185 RG/70_492_AFG_D540_ ; CP25-1-SN185 RG/70_492_AFG_D540_ ; CP25-1-SN185 Anton Paar GmbH

8 Process Parameters Sedimentation Stability Penetration depth absorber content intensity exposure time (refractive index) Overpolymerization closed pores Printing Process 3D CAD Model (STL) Debinding Sintering Testing

9 Process Parameters From theory to practice (TGA, TMA): Temperature deviations Cracks Interlaminar Intralaminar Printing Process 3D CAD Model (STL) Debinding Sintering Testing Delamination Residues of carbon Reduced translucency

10 Process Parameters Shrinkage Upscaling Debinding Sintering Testing up to -28% Printing Process 3D CAD Model (STL) Distortion Cleaning

11 Process Parameter Mechanical properties Biaxial bending strength Translucency Printing Process 3D CAD Model (STL) Debinding Sintering Testing Precision Fitting

12 Materials Al 2 O 3 TCP Bioactive Glasses ZrO

13 Material properties Measured biaxial bending strength [MPa] Biaxial bending strength in literature [Mpa] Al 2 O 3 ZrO 2 Material 45S5 Bioglass TCP 521 [3] 1098 [4] 124 [5] [1] [2] 24 Density [g/cm³] 3,82 5,9 2,7 3,14 Relative Density [%] 99,6 99,92 > Solid loading green parts [vol%] ,7 50 Max. building speed. [mm/h] Source: [1] Verband der Keramischen Industrie e.v., Brevier Technische Keramik, 2003, p.270 [2] L.L. Hench et al., Properties of bioactive glasses and glass-ceramics ; pp in Handb. Biomater. Prop. Edited by J. Black and G. Hastings. Springer US, 1998 [3] R. Felzmann et al., Lithography-based Additive Manufacturing of Customized Bioceramic Parts for Medical Applications ; in ACTAPRESS, [4] G. Mitteramskogler et al., Light Curing Strategies for Lithography- Based Additive Manufacturing of Customized Ceramics, Euromat 2013 [5] R. Gmeiner et al., Stereolithographic Ceramic Manufacturing of High Strength Bioactive Glass, accept. & await. publication in Int. J. Appl. Ceram. Tec., 2014 [6] M. Pfaffinger et a., Thermal Dedinding of Ceramic-filled Photopolymers, Verbundwerkstoffe Symposium

14 Dipl.-Ing. Sonja Baumgartner Christian Doppler Laboratory Photopolymers for Digital and Restorative Dentistry