3D printed Polymer Derived Ceramics

This page comprises a literature review of Polymer Derived Ceramics and transforming polymer 3D printed structures to Ceramics.

Search Phrases[edit | edit source]

• Polymer Derived Ceramics
• 3D printed Polymer Derived Ceramics
• Additive manufacturing of Polymer Derived Ceramics
• 3D printing of preceramic polymers
• Polymer precursor solid freeforming
• SiOC + 3D printing

Literature[edit | edit source]

Polymer Derived Ceramics: 40 Years of Research and Innovation in Ceramics[edit | edit source]

Colombo, Paolo, Gabriela Mera, Ralf Riedel, and Gian Domenico Sorarù. 2010. "Polymer-Derived Ceramics: 40 Years of Research and Innovation in Advanced Ceramics." Journal of the American Ceramic Society 93 (7): 1805–37. https://doi.org/10.1111/j.1551-2916.2010.03876.x.^[1]

Abstract Polymer to ceramic conversion opened a new avenue of applications such as porous ceramics, ceramic fibers, coatings etc.

Introduction

• The procedure is to convert preceramic polymers or (silicon based) polymer precursors into ceramics by method of thermolysis or curing.
• The benefit of this method is that, polymers can be processed into complex shapes with the help of polymer processing techniques like injection molding, extrusion, polymer infiltration pyrolysis, solvent coating, resin transfer molding.
• Polymer Derived Ceramics (PDCs) have similar properties exhibited by ceramics such as thermal, chemical and mechanical stability at high temperatures, creep and oxidation resistance for temperatures upto 1500 degrees celsius.
• PDCs have comparatively lower synthesis temperatures.

Preceramic Polymer Synthesis

• The properties of the final ceramic part are largely dependant on the the polymer precursor.
• Two important parameters
  

1. one Group X of polymer backbone
2. two Substituents R1 and R2 attached to Silicon
   

• Varying X gives us different Silicon based polymers

1. X=Si : poly(organosilanes)
2. X=CH2 : poly(organocarbosilanes)
3. X=O : poly(organosiloxanes)
4. X=NH : poly(organosilazanes)
5. X=[N=C=N] : poly{organosilylcarbodiimides)

• Chemical, thermal stability, solubility, electronic, optical rheological properties can be modified by changing the functional groups R1 amd R2.

Processing of Polymers Shaping, Cross-linking and addition of fillers

• The polymers can be shaped in the conventional polymer processing methods. i.e. handling can be done before heat treatment and is easier.
• Can be machined before converting to ceramics (major advantage).
• Creation of nanostructures (wires, belts, tubes) is possible.
• Preceramic polymers can be liquid or solid, are soluble in various solvents, can be melted at low temperatures (less than 150 degrees)
• Easier processing than powder based ceramic manufacturing techniques.
• Cross linking occurs during shaping or pyrolysis.
• Curing can be done after shaping (e.g. oxidative curing).
• Infiltrating already shaped polymers by precursors is also possible.
• Different fillers can be added to change the properties and structural base of the shaped precursor (e.g. iron fillers for magnetic properties).

Polymer to Ceramic Conversion

• Amorphous Ceramics can be obtained by thermal processing of preceramic polymers (most common method is oven pyrolysis.
• Laser pyrolysis can be used to produce coatings and nano sized particles (irradiation of aerosols)
• Hot pressing and spark plasma sintering can be applied to pyrolysed powders.

Processing Parameters influencing the PDCs

1. degree of cross-linking - can affect the plastic forming ability.
2. shape of fillers - high aspect ratio can introduce anisotropy and shrinkage problems.
3. Type of atmosphere - silazanes and carbosilnes are sensitive towards humidity.
4. oxygen content - can lead to unwanted elimination of carbon containing moities.
5. gas pressure - vacuum promotes carbothermal reactions
6. heating rate - composition and microstructure extent of crystallisation, carbothermal reduction reactions, filler reactions.
7. dwelling temp - composition and microstructure, extent of crystallisation, carbothermal reduction reactions, filler reactions.

Microstructure of PDCs

• Presence of nanodomains - these resist the crystallization of the PDCs. SiCN contains nanodomains of 1-3nm in size.
• PDCs can be amorphous up to 1000-1800 degrees.
• As temperature is increased, devitrification occurs. Chemical bonds are redistributed. Nucleation is initiated and crystal growth occurs.
• Incorporate "free" carbon in the form of basic structural units (some in form of graphene sheets). -- attributed properties -- high chemical durability and resistance to crystallization.
• As the carbon content increases the domain size is reduced.

Properties of PDCs

• Properties of PDCs can be varied by the use of precursors and fillers i.e. different electric, optical magnetic properties can be obtained.
• PDCs exhibit excellent oxidation resistance.
• Different mechanical properties can be obtained for fibers and bulk shapes.

Applications of PDCs

• Polymer Derived Fibers, Fibers containing multi walled carbon nanotubes.
• Ceramic matrix composites (Brake Disc Rotors)
• Highly porous components - impact absorption, thermal protection, adsorption, gas separation and 3D reinforcement.
• Coatings
• Microcomponents

Polymer-derived SiCN cellular structures from replica of 3D printed lattices[edit | edit source]

Jana, Prasanta, Oscar Santoliquido, Alberto Ortona, Paolo Colombo, and Gian Domenico Sorarù. 2018. "Polymer-Derived SiCN Cellular Structures from Replica of 3D Printed Lattices." Journal of the American Ceramic Society 101 (7): 2732–38. https://doi.org/10.1111/jace.15533.^[2]

Abstract In comparison with metals and polymers, ceramics and/or carbon are more difficult to process into well-defined cellular architectures (e.g., cubic, tetrakaidecahedron, etc.) using Additive Manufacturing techniques. The present work reports a simple method for generating complex and precise SiCN ceramic lattices using a preceramic polymer and applying the replica approach to structures fabricated using stereolithography of plastic materials, with the associated ease of fabrication. Three-dimensional printed plastic lattices impregnated with a polysilazane were converted to SiCN by pyrolysis at 1000°C in inert atmosphere. In spite of the high amount of mass loss (~58%) and volume shrinkage (~65%), the impregnated structures did not collapse during pyrolysis, leading to highly porous (total porosity ~93 vol%) components possessing suitable strength for handling and potential use as lightweight components.

Introduction

• The method is beneficial because the additive manufacturing techniques for polymers are better developed than for ceramics.
• Synthesis of Silicon based ceramics via pyrolysis of preceramic polymers.
• SiC, SiOC and SiCN PDCs have been manufactured via selective laser curing, direct writing, stereolithography followed by pyrolysis.
• The process used is similar to the replication of polyurethane foams into ceramic foams. The method was seen to cost effective and simple.[1]

Experimental Method

• Polymer cellular lattice structures (cubic 10*10*10 mm and tetrakaidecahedron 12*12*12 mm) were printed using commercial photocurable acrylic resin.
• A mixture of commercial Polysilazane (gives SiCN upon pyrolysis), Pt catalyst and acetone solvent was used to impregnate the 3D printed structure.
• Pt Catalyst + acetone : immersion for 30 mins.
  
• add Polysilazane, keep for 30 mins.
  
• Take out and keep in air at room temperature for 1 day.
  
• Pyrolysis at 1000 degrees in argon environment at 5 degrees/min and 1 hour dwell time (furnace was purged for 5 hours before with argon to remove oxygen content.
  
• Free cooling till room temperature
  

Results

• During immersion ~12% volume expansion occurred. 7% expansion after drying for 1 day (acetone removed by evaporation).
• During pyrolysis - TGA analysis - ~8% weight loss from 150-300 degrees, ~88% weight loss from 300-475 degrees and total weight loss of 96% from RT-100 degrees.
• Cubic lattice original dimensions were strut diameter = 650um, cell size =~3500um, layer thickness 50um. After pyrolysis, strut diameter =~440um, cell size =~2200um. ~66% volume reduction and 30-35% reduction in linear dimension
• Further heating leaves us with only carbon lattice with strut diameter =~380um and cell size =~1700um.
• Compressive strength (cubic) 0.18 +-0.02MPa, elastic modulus 5.8 +-0.3 MPa.
• Problems - Struts were porous, cracks were present. Reasons - a. thermal expansion mismatch between silazane and polymeric structure, b. difference in shrinkage of 2 materials, c. release of pyrolysis gases through the layers.

Additive Manufacturing of Polymer Derived Ceramics[edit | edit source]

Eckel, Zak C., Chaoyin Zhou, John H. Martin, Alan J. Jacobsen, William B. Carter, and Tobias A. Schaedler. 2016. "Additive Manufacturing of Polymer-Derived Ceramics." Science 351 (6268): 58–62. https://doi.org/10.1126/science.aad2688.^[3]

Abstract The article reports two methods of manufacturing polymer derived ceramics from preceramic polymers. One is the standard stereolithography and curing of preceramic monomers by a patterned mask using Self-propagating polymer waveguide technology. The polymer structures are then pyrolyzed. Silicon oxycarbide microlattice and honeycomb structures are manufactured. The paper reports these structures having higher strength than the ceramic foams.

Method

• The usual uses of PDCs - a. synthesis ceramic fibers, b. densify ceramic matrix components.
• UV active photocurable monomers can be obtained by attaching thiol, viny, acrylate, methacrylate, or epoxy groups to inorganic backbone.
• Polymerization inhibitors and UV absorbers are added to confine the polymerization to the laser focal point.
• Some structures can be formed a 100-1000 times faster with self propagating polymer waveguide technology(SPPW).

-Monomers are selected to change the refractive index upon polymerization and induce internal reflection and trapping the UV light and propagating the polymerization.
-The structures can be manufactured with patterned mask instead of rastering laser pointers in the pool of liquid monomer.
-Ceramics fabricated with SPPW exhibit very smooth surface.

• Similar pyrolysis techniques were used [2] (1000 degrees in argon) and 42% mass loss and 30% linear shrinkage was reported.
• Mechanical Properties such as failure strength and elastic modulus of the cellular structures can be calculated using formulae.

Structure Nano domains of silica tetrahedra in network of graphene network. The center of the nanodomain is silicon oxygen tetrahedra.

Oxidation in PDCs

• Upto 1300 degrees for 10 hours - replacement reaction at the SiOC surface, creating amorphous SiO2 oxide layer and releasing CO or CO2.
• More heat treatment - Increased thickness of clear thin oxide film and shift in coloration.
• 1440 degrees for 10 hours - hazy surface oxide = cristobalite.
• 1500, 1600, 1700 degrees - similar behaviour with increased mass loss rate.
• between 1400-1500 change from amorphous to crystalline -carbothermal reaction.

Fabrication of polymer derived ceramic parts by selective laser curing[edit | edit source]

Friedel, T., N. Travitzky, F. Niebling, M. Scheffler, and P. Greil. 2005. "Fabrication of Polymer Derived Ceramic Parts by Selective Laser Curing." Journal of the European Ceramic Society, European Materials Research Society 2004, Symposium Q: Polymer Derived Ceramics (PDCs), 25 (2): 193–97. https://doi.org/10.1016/j.jeurceramsoc.2004.07.017.^[4]

Summary

• Process similar to selective laser sintering. Polysiloxane powder added with SiC is cured with CO2 laser beam.
• 50% polymer and 50% SiC in volume, subsequent pyrolysis at 1200 degrees in argon.
• The parts were infiltrated with liquid silicon to increase density after curing.
• The strength and density after liquid infiltration were considerably good.

Stereolithography of SiOC Ceramic Microcomponents[edit | edit source]

Zanchetta, Erika, Marco Cattaldo, Giorgia Franchin, Martin Schwentenwein, Johannes Homa, Giovanna Brusatin, and Paolo Colombo. "Stereolithography of SiOC Ceramic Microcomponents." Advanced Materials 28, no. 2 (2016): 370–76. https://doi.org/10.1002/adma.201503470.^[5]

Summary

• Used in applications such as semiconductor industry, photonic-crystals, microelectromechanical systems, biochips, and scaffolds or bone tissue regeneration.
• Si-rich and carbon-rich nanosized domains provide with enhanced thermomechanical properties such as creep, oxidation and crystallisation resistance.

1. Polysilazanes - limited availability, sensitive to moisture and oxygen, produce Si-O-C system.
2. Polysiloxanes - insensitive to air, moisture, cheap, commercially available, inexpensive and available in different physical and chemical forms.

• Chemical used - engineered photosensitive methyl-silsequioxane preceramic polymer (MK-TMSPM) (made from silicone, and organixally modified silicon alkoxide, 3-(trimethoxysilyl methacrylate.
• Photoinduced cross-linking in MK-TMSPM system using UV radiation (stereolithography) and then pyrolysis to transform into ceramic.
• Similar amount of shrinkage was observed (~25% in linear dimensions). No deformation in shape. Scaffolds were smooth and completely defect free. Similar behaviour of mass loss during pyrolysis.
• Using different solvents might yield a different ceramic density (i.e. more dense structures).

SiOC ceramics with ordered porosity by 3D-printing of a preceramic polymer[edit | edit source]

Zocca, Andrea, Cynthia M. Gomes, Andreas Staude, Enrico Bernardo, Jens Günster, and Paolo Colombo. "SiOC Ceramics with Ordered Porosity by 3D-Printing of a Preceramic Polymer." Journal of Materials Research 28, no. 17 (September 2013): 2243–52. https://doi.org/10.1557/jmr.2013.129.^[6]

Direct Ink writing of micromimetic SiOC ceramic structures using a preceramic polymer[edit | edit source]

Pierin, Giovanni, Chiara Grotta, Paolo Colombo, and Cecilia Mattevi. "Direct Ink Writing of Micrometric SiOC Ceramic Structures Using a Preceramic Polymer." Journal of the European Ceramic Society 36, no. 7 (June 1, 2016): 1589–94. https://doi.org/10.1016/j.jeurceramsoc.2016.01.047.^[7]

Recent Advances in 3D printing of porous ceramics : A review[edit | edit source]

Cellular ceramics produced by rapid prototyping and its applications[edit | edit source]

References[edit | edit source]