B4C CMC Brake Composite Structure for Low-Silicon Heat Capacity
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Solution Overview
Problem
Existing C/C and CMC components for aircraft brakes face challenges in incorporating boron or boron carbide materials due to limitations in heat capacity and silicon content, which affects their ability to absorb and dissipate heat effectively.
Innovation Solution
A method of forming fibrous preforms with ceramic particle layers interspersed between fiber layers, using varying grit sizes to control silicon infiltration, and performing silicon melt infiltration to create composite components with higher specific heat capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If boron or boron carbide materials are incorporated into carbon fiber structures to increase heat capacity, then the heat absorption capability is improved, but the silicon content increases which limits further incorporation
Solution Approach 1:
The patent applies local quality by varying the ceramic particle size in different layers of the composite structure. Outer layers contain larger particles (e.g., 44-60 mesh) while inner layers contain smaller particles (e.g., 100-150 mesh). This gradient structure allows silicon to infiltrate outer regions while preserving the inner regions for high heat capacity materials, resolving the contradiction between heat capacity and silicon content limits
Solution Approach 2:
The composite is segmented into multiple layers with different ceramic particle sizes and compositions. This segmentation allows different functional zones: outer layers handle silicon infiltration and structural integrity, while inner layers maximize heat capacity. The segmentation enables incorporating more high heat capacity materials without exceeding silicon content limits
2Use of energy by moving object
If larger amounts of high heat capacity materials are incorporated into carbon fiber structures, then heat absorption capability is improved, but structural limitations prevent further incorporation
Solution Approach 1:
The patent creates a multi-phase composite material system combining carbon fibers, ceramic particles (boron carbide, silicon carbide), and metal matrix (aluminum). This composite structure allows high heat capacity materials to be incorporated at volumes exceeding traditional limits (up to 60-70% ceramic content) while maintaining structural integrity through the hierarchical arrangement of fibers, particles, and matrix
Solution Approach 2:
Different regions of the composite have optimized local compositions: outer layers have larger ceramic particles for structural stability and controlled silicon infiltration, while inner layers have finer particles for maximum heat capacity. This local quality variation enables higher overall heat capacity material content without compromising structural limitations
3Strength
If silicon melt infiltration is performed to densify the composite, then structural integrity is improved, but silicon content increases reducing heat capacity
Solution Approach 1:
The patent uses local quality by creating a ceramic particle size gradient where outer layers have larger particles that allow controlled silicon infiltration for structural integrity, while inner layers have smaller particles that limit silicon penetration and preserve heat capacity. This spatial variation in particle size enables simultaneous achievement of structural strength and heat capacity
Solution Approach 2:
Ceramic particles act as intermediaries between the silicon melt and the carbon fiber structure. The particles control silicon infiltration kinetics and distribution, allowing structural densification while limiting silicon content in regions critical for heat capacity. The ceramic layer serves as a mediator that enables beneficial silicon infiltration while preventing excessive silicon accumulation
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 results in composite components with enhanced heat capacity and reduced silicon content, improving wear performance and heat dissipation in aircraft brakes.
Implementation Method 1
forming a first ceramic particle layer over a first textile layer, the first ceramic particle layer having a first group of ceramic particles
Implementation Method 2
densifying the fibrous preform
Implementation Method 3
performing a silicon melt infiltration after densifying the fibrous preform
Implementation Method 4
Boron or boron carbide materials possess relatively high heat capacities and thermal stability
Data Source
AI summary
A method of fabricating a composite component, includes forming a fibrous preform by forming a first ceramic particle layer over a first textile layer, the first ceramic particle layer having a first group of ceramic particles, disposing a second textile layer over the first ceramic particle layer, forming a second ceramic particle layer over the second textile layer, the second ceramic particle layer having a second group of ceramic particles, and disposing a third textile layer over the second ceramic particle layer. The method further includes densifying the fibrous preform.