Dry Ceramic Matrix Composite Prepreg with Low-Moisture Binder
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Solution Overview
Problem
Ceramic matrix composite prepregs with water-based slurries have limited out-time and require special storage and handling conditions due to high moisture content, making them unstable for automated processing and layup procedures, which is a challenge in the aerospace industry for achieving desired properties and performance.
Innovation Solution
Development of a dry prepreg system where ceramic fibers are infiltrated with a preceramic matrix containing no more than 4 wt.% water, using an aqueous solvent and an organic binder system to provide tack and stability, allowing for longer storage and processing without humidity control, and enabling self-adherence and seamless lamination during layup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-based slurry is used to impregnate ceramic fibers, then the prepreg can be easily processed and applied, but the out-time is limited and special storage conditions are required
Solution Approach 1:
The invention changes the moisture content parameter from high (water-based slurry) to low (dry state with ≤4 wt.% water), transforming the prepreg from requiring immediate processing to allowing extended storage and handling without special conditions
Solution Approach 2:
The invention uses a composite binder system containing both aqueous solvent and organic binder components, where the organic binder provides long-term stability and tack while the aqueous component enables processing, creating a material that combines properties of both wet and dry systems
2Ease of operation
If water-based slurry is used to impregnate ceramic fibers, then the prepreg can be applied to substrates, but special storage and handling conditions are required due to high moisture content
Solution Approach 1:
The invention reduces the water content parameter from high to low (≤4 wt.%), changing the stability characteristic from requiring controlled storage to allowing ambient storage while maintaining composition stability during handling and processing
Solution Approach 2:
The organic binder acts as an intermediary substance that provides the necessary tack and stability properties, mediating between the ceramic fibers and the low-moisture environment to enable both stability and processability
3Stability of the object's composition
If dry state with low water content is used, then storage and handling are simplified without humidity control, but achieving adequate tack and lamination properties becomes challenging
Solution Approach 1:
The invention creates a composite binder system where organic binder components (such as polyvinyl butyral, polyvinyl acetate, or carboxymethyl cellulose) provide tack and adhesion properties in the dry state, while the aqueous solvent component enables infiltration and processing, achieving both stability and manufacturability
Solution Approach 2:
The invention applies different functional properties to different aspects of the binder system: the organic binder provides local tack and adhesion quality at the fiber-binder interface, while the aqueous component provides local flow and infiltration quality during processing, with each component optimized for its specific function
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 dry prepreg system provides improved stability and handling characteristics, allowing for longer out-time and easier processing, with enhanced tack and lamination properties, resulting in composites with desired mechanical and thermal performance without the need for special storage conditions.
Implementation Method 1
an organic binder system to provide tack and stability, allowing for longer storage and processing without humidity control, and enabling self-adherence and seamless lamination during layup
Data Source
AI summary
Dry prepregs for ceramic matrix composites are described. The dry prepregs comprise a tow or fabric of ceramic fibers infiltrated with preceramic matrix comprising low levels of an aqueous solvent. The preceramic matrix contains an inorganic portion and a binder system. Binder systems comprising a binder and a plasticizer for the binder are described.