Preceramic Resin Stereolithography for Fully Dense Ceramics
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Solution Overview
Problem
Existing additive manufacturing techniques for ceramics result in porous structures with low strength due to porosity and inhomogeneity, limiting their application in high-temperature environments and complex shapes.
Innovation Solution
A preceramic resin formulation comprising molecules with C=X and C≡X bonds, photoinitiators, thermal initiators, and 3D-printing agents is used to create fully dense ceramic structures through UV-cure-based stereolithography, followed by thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If powder-based additive manufacturing techniques are used to create ceramic structures, then complex shapes can be fabricated, but the resulting structures are porous and have low strength
Solution Approach 1:
The invention changes the fundamental parameter of the starting material from ceramic powder to preceramic polymer resin. This parameter change enables the material to be deposited as a dense liquid that cures to form fully dense ceramic structures, eliminating the porosity inherent in powder-based methods while maintaining the ability to fabricate complex shapes through additive manufacturing
Solution Approach 2:
The invention introduces preceramic polymer resin as an intermediary material between the additive manufacturing process and the final ceramic structure. The resin acts as a mediator that can be precisely deposited layer-by-layer to form dense green bodies, which are then converted to fully dense ceramics through pyrolysis, avoiding the porosity problems of direct powder sintering
2Ease of manufacture
If sintering is used to consolidate ceramic powders, then ceramic structures can be formed, but residual porosity is unavoidable and strength is severely decreased
Solution Approach 1:
The invention inverts the conventional approach by instead of starting with powder and attempting to eliminate porosity through sintering, it starts with a liquid resin that cures to form a dense green body, then uses pyrolysis to convert the organic material to dense ceramic. This inversion of the process sequence eliminates residual porosity that plagues sintered parts
Solution Approach 2:
The invention changes the consolidation mechanism from thermal sintering of particles to photopolymerization of resin followed by pyrolytic conversion. This parameter change in the consolidation process enables full density to be achieved without the porosity that is inherent in sintering processes
3Shape
If conventional additive manufacturing processes are used for ceramics, then layer-by-layer fabrication is achieved, but fabrication rates are slow and binder removal is time-consuming
Solution Approach 1:
The invention enables continuous photopolymerization of the preceramic resin during the additive manufacturing process, eliminating idle time between layers. The resin is deposited and cured in continuous operation, and the pyrolysis step consolidates the entire structure simultaneously, removing the time-consuming sequential binder removal process required by conventional methods
4Ease of manufacture
If ceramic materials are processed by sintering or thin film deposition, then ceramic structures can be created, but flaws such as porosity and inhomogeneity are introduced that govern strength
Solution Approach 1:
The invention changes the processing parameters from high-temperature sintering of powders to photopolymerization of resins followed by controlled pyrolysis. This parameter change enables atomic-level homogeneity in the green body that translates to uniform dense ceramic structures after pyrolysis, eliminating the porosity and inhomogeneity that govern strength in conventionally processed ceramics
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
The method produces fully dense, high-strength ceramic structures with minimal porosity and uniform shrinkage, suitable for complex shapes and high-temperature environments.
Implementation Method 1
UV-cure-based stereolithography
Implementation Method 2
thermal treatment
Data Source
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AI summary
This disclosure enables direct 3D printing of preceramic polymers, which can be converted to fully dense ceramics. Some variations provide a preceramic resin formulation comprising a molecule with two or more C=X double bonds or C=X triple bonds, wherein X is selected from C, S, N, or O, and wherein the molecule further comprises at least one non-carbon atom selected from Si, B, Al, Ti, Zn, P, Ge, S, N, or O; a photoinitiator; a free-radical inhibitor; and a 3D-printing resolution agent. The disclosed preceramic resin formulations can be 3D-printed using stereolithography into objects with complex shape. The polymeric objects may be directly converted to fully dense ceramics with properties that approach the theoretical maximum strength of the base materials. Low-cost structures are obtained that are lightweight, strong, and stiff, but stable in the presence of a high-temperature oxidizing environment.