Towards Additive Manufacturing of High-Performance Ceramics
Stephen Farias, PhD
Chief Science Officer
Flame retardant, conductive, bioprinting
Polymers, non-oxide ceramics, oxide ceramics, tissue culture
Electrospun nanofibers, silver nanowires, synthesis/purification
Drug delivery, encapsulation, insecticide, enzyme
Flame retardant, permethrin encapsulated, IR reflective, nonwovens
Basics of Additive Manufacturing
• Fused Deposition Modeling (FDM)• Heated filament deposited layer
by layer
• Stereolithography (SLA)• Light activated crosslinking
photocuring from solution
• Selective Laser Sintering (SLS)• Laser sintering/fusing of powder
bed
Current AM of Ceramics
• Can do simple clays (pottery and artistic media) using extrusion printers• Fire print in a kiln post print
• Engineering Ceramics• Can be printed via various
techniques using binder formulations
• Need to post-process to remove binders and sinter
Problems for High-Performance Ceramics“The main problem of AM ceramics lies with the formulation of feedstock” [3]
Ultra-High Temperature Ceramics are not directly additively manufactured due to:• Not easily sintered• Laser energy deposition induces microcracking• Incongruent melting (decomposition)
SLS - Powder Bed Fusion
Excessive volume changes/cracking associated with debinding.
[3] A. Zocca, P. Colombo, C. M. Gomes, and G. Jens, “Additive Manufacturing of Ceramics: Issues, Potentialities, and Opportunities,” vol. 98, no. 7, pp. 1983–2001, 2015.[4] M. C. Leu, S. Pattnaik, and G. E. Hilmas, “Investigation of laser sintering for freeform fabrication of zirconium diboride partst” Virtual Phys. Prototyp., vol. 7, no. 1, pp. 25–36, 2012.
Binder Phase Consolidation
Required Post-Processing
25 mm
Laser sintered and post-processed ZrB2 part.[3]
High-Performance Ceramics (Carbides, Nitrides and Borides)
Strongly Covalent Bonds→ High-Melting Temperatures, Structural Stability → Difficult Processing/Part Formation
?
Now: Simple Non-Oxide Coatings
(Above) Ceramic sharp wing
leading edge for hypersonics. [1][2]
Non-oxide (carbides, nitrides, borides) withstand extreme environments and have many adventurous thermal characteristics:
• Extreme temperature (often above Mp >3000°C), oxidation resistance, chemical reactivity, radiation, mechanical stress• Have high thermal conductivity for efficient heat transfer
Note: white bars show spontaneous reaction temperatures for synthesis from metal or metal oxide precursors in CH4 or NH3
Future: Complex, Selectively DepositedUHTC Components
(Above) Ni single-piece
AM rocket engine.
Our Solution: Synteris™ Selective Laser Reaction Sintering (SLRS)
• Laser heating of the precursor causes reaction with the gas to synthesize the desired non-oxide in-situ as parts are being formed
• Reaction occurs spontaneously below melting or sintering temperatures, lowering thermally induced stress
• Particles bind with chemically-induced reaction-bonding
• By altering the reactant gas other non-oxides may be produced (e.g. CH4 for carbides, NH3 for nitrides, etc.)
Conversion of unique Metal/Metal-Oxidecomposite precursor system should satisfy:
1. Full conversion with few impurities
2. Timely conversion
3. Reactive isovolumetric formation
Our Solution: Synteris™ Continued
• By combining specialty precursors for SLRS we can approach net-shape ceramic prints
• Tuned combinations of reactants that expand and contract to form final phase
R1 R2
PC PC
Carbon Source
Carbon Source
Example SiC and TiC Prints
Example 3D TiC Lattice
Acknowledgements
• Johns Hopkins University Inventors• Adam Peters, PhD
• Michael Brupbacher, PhD
• Dajie Zhang, PhD
• Collaborators• Sreekant Narumanchi, PhD - NREL
• Doug Devoto - NREL
• Winston Frazer – Danae Inc
• Funding
• Business Support