Preceramic Resin for Dense Ceramic 3D Printing
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Solution Overview
Problem
Current additive manufacturing techniques for ceramics are limited in processing ceramic matrix composites, resulting in porous and weak ceramic parts due to flaws like porosity and inhomogeneity, and lack the ability to create complex shapes or achieve the theoretical strength of ceramic materials.
Innovation Solution
A preceramic radiation-curable resin composition is developed, comprising specific molecules and fillers, which can be 3D printed and then thermally treated to produce dense ceramic parts with improved strength and thermal stability, bypassing the need for sintering or organic binders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ceramic processing methods (sintering or thin film deposition) are used, then ceramic parts can be manufactured, but the parts suffer from porosity and inhomogeneity that reduce strength and reliability
Solution Approach 1:
The patent changes the fundamental processing parameters by using preceramic polymers instead of ceramic powders, and using UV curing instead of sintering. This parameter change enables direct formation of dense, homogeneous ceramic structures without the porosity and inhomogeneity that plague conventional sintering processes, thereby simultaneously improving manufacturing precision and fracture strength
Solution Approach 2:
The patent utilizes the phase transition of preceramic polymers upon UV curing and subsequent pyrolysis to transform from a processable liquid/soft solid state to a dense ceramic state. This phase transition approach allows the material to be formed in a homogeneous state and then converted to the final ceramic structure, avoiding the porosity issues of powder sintering
2Shape
If additive manufacturing techniques are used to create complex ceramic shapes, then geometric flexibility is improved, but the parts still exhibit porosity and inhomogeneity that limit strength
Solution Approach 1:
The patent changes the material state parameter from ceramic powder to preceramic polymer, and the processing method from layer-by-layer powder deposition to UV-cured polymer formation. This enables complex geometries to be formed as homogeneous polymer structures that convert to dense ceramics, maintaining both geometric flexibility and high strength
Solution Approach 2:
The patent uses preceramic polymers as a composite material that combines the processability of polymers with the ceramic-forming capability. This composite approach allows complex shapes to be formed in the polymer state and then converted to ceramic, achieving both geometric complexity and high strength without the porosity of powder-based methods
3Shape
If ceramic particles are printed in organic binders, then complex shapes can be formed, but binder removal creates porosity and reduces strength
Solution Approach 1:
The patent extracts and eliminates the organic binder component entirely by using preceramic polymers that self-support and self-sinter upon UV curing and pyrolysis. This extraction of the binder eliminates the source of porosity that occurs during binder removal, achieving both complex shapes and high density
Solution Approach 2:
The preceramic polymer acts as an intermediary material that replaces the organic binder function while providing structural support and ceramic-forming capability. This intermediary material is converted to ceramic in situ, eliminating the need for binder removal and the associated porosity
4Ease of manufacture
If conventional sintering of compacted porous materials is used, then ceramic parts can be manufactured, but the process severely limits manufacturable geometries
Solution Approach 1:
The patent inverts the conventional approach by forming the green body as a UV-cured polymer structure with the desired complex geometry, then converting it to ceramic through pyrolysis. This inversion of the process sequence (forming first, then converting) enables complex geometries that would be impossible to achieve through conventional sintering of compacted powders
5Productivity
If additive manufacturing processes are used, then fabrication speed can be improved, but thermal gradients cause cracks and reduce reliability
Solution Approach 1:
The patent changes the processing temperature parameter from high-temperature sintering to UV curing at ambient or low temperatures, followed by controlled pyrolysis. This parameter change eliminates the large thermal gradients that cause cracking during rapid sintering, maintaining both high fabrication speed and crack-free reliability
Solution Approach 2:
The patent utilizes controlled phase transitions of the preceramic polymer (UV curing, then pyrolysis) instead of rapid thermal sintering. This phase transition approach allows for more uniform heating and conversion, reducing thermal gradients and preventing cracks while maintaining productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the direct conversion of preceramic polymers into dense ceramic structures with enhanced mechanical properties, overcoming the limitations of existing techniques by achieving high strength and thermal stability, suitable for various industrial applications.
Implementation Method 1
heating the 3D-printed preceramic polymer material to fire or pyrolyze the polymer material, thereby producing a ceramic material
Implementation Method 2
A preceramic polymer material is prepared from a preceramic resin composition that is UV-cured in a 3D printer
Data Source
AI summary
Some variations provide a preceramic resin precursor formulation comprising: first molecules containing at least one Si—N bond and/or at least one Si—C bond; and second molecules of the formula R4—N═C═S, wherein R4 may be a UV-active functional group. In some embodiments, R4 is selected from ethynyl, vinyl, allyl, acrylate, methacrylate, vinyl ether, epoxide, oxetane, thiol, thioketone, isothiocyanate, or combinations thereof. The first and second molecules are reacted with an isothiocyanate to form third molecules, providing a preceramic radiation-curable resin composition. The resin composition contains at least one Si—N bond and/or at least one Si—C bond in the main chain of the third molecules. Side chains of the third molecules may be selected from hydrogen, unsubstituted or substituted hydrocarbon groups, halides, esters, amines, hydroxyl, or cyano. The resin composition may be 3D printed and thermally treated to generate a ceramic material.