CMC Brake Interlayer Bonding for Uniform Densification
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Solution Overview
Problem
Traditional methods for fabricating ceramic matrix composite (CMC) structures for aircraft brake systems face limitations in withstanding high temperatures and stresses, particularly due to thermal and mechanical stresses induced by bulk densification processes, which can lead to density gradients and reduced strength.
Innovation Solution
The use of a CMC structure with nominally dense plies interleaved with compliant interlayers, bonded using techniques such as Field Assisted Sintering Technique (FAST), Spark Plasma Sintering (SPS), or localized Joule heating, to enhance bonding and interlaminar properties, allowing for improved thermal and mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional bulk densification processes (CVI, MI, PIP) are used to fabricate CMC structures, then the structures can be produced, but thermal and mechanical stresses are induced causing density gradients and reduced strength
Solution Approach 1:
The patent divides the bulk densification process into sequential stages: first forming individual dense plies separately, then stacking and bonding them into the final multi-layer CMC structure. This segmentation allows each ply to be densified independently without inducing thermal and mechanical stresses that would affect the entire thick preform, thereby eliminating density gradients and improving overall composite strength while maintaining fabrication capability
Solution Approach 2:
The patent applies preliminary densification to individual plies before they are stacked into the final structure. By pre-densifying each thin ply to high density before assembly, the subsequent bonding process occurs between already-densified surfaces, avoiding the need to densify thick stacked preforms which would induce harmful thermal and mechanical stresses and density gradients
2Device complexity
If plies are layered together to fabricate laminated preforms, then the structure can be built, but bonding between adjacent laminates is insufficient reducing overall strength
Solution Approach 1:
The patent introduces a bonding process using field assisted sintering technique (FAST) or spark plasma sintering (SPS) as an intermediary step between stacking plies and forming the final structure. This intermediary bonding process creates strong interlaminar bonds by applying localized electric fields and heat at the interfaces between plies, significantly improving interlaminar bonding strength while preserving the complex laminated structure
Solution Approach 2:
The patent changes the bonding parameters by using non-contact electric field-based sintering (FAST/SPS) instead of traditional contact-based bonding methods. By controlling electric field intensity, pulse duration, and temperature profiles, the process achieves strong interlaminar bonding without inducing excessive thermal stresses, thereby improving bonding strength while maintaining structural integrity
3Ease of manufacture
If traditional densification methods are used, then CMC structures can be produced, but they cannot withstand temperatures of 2550°F (1400°C) or greater in oxidizing environments
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where surface plies exposed to oxidizing environments are densified to higher densities and potentially different compositions than interior plies. This localized differentiation of ply quality allows the surface layers to withstand high temperature oxidation while interior layers maintain the overall structural form, enabling the CMC structure to reliably withstand temperatures of 2550°F (1400°C) or greater in oxidizing environments
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 approach enables the CMC structure to effectively withstand high temperatures and stresses, reducing thermal and mechanical stresses, and improving the strength and durability of brake components, such as rotor and stator disks, by promoting intimate contact and uniform densification between plies.
Implementation Method 1
bonded by at least one of a Field Assisted Sintering Technique (FAST), a Spark Plasma Sintering (SPS) process
Implementation Method 2
bonded by at least one of a Field Assisted Sintering Technique (FAST), a Spark Plasma Sintering (SPS) process
Implementation Method 3
bonded by at least one of a Field Assisted Sintering Technique (FAST), a Spark Plasma Sintering (SPS) process, a radiative heating process
Implementation Method 4
bonded by at least one of a Field Assisted Sintering Technique (FAST), a Spark Plasma Sintering (SPS) process, a localized Joule heating process
Data Source
AI summary
A brake component is disclosed. In various embodiments, the brake component includes a ceramic matrix composite (CMC) structure including a plurality of nominally dense plies, interleaved with a plurality of interlayers, wherein the plurality of nominally dense plies and the plurality of interlayers are bonded by at least one of a Field Assisted Sintering Technique (FAST), a Spark Plasma Sintering (SPS) process, or a localized heating process. In various embodiments, the brake component is a rotor disk or a stator disk.