Ceramic Matrix Laminates Bonding via Chemical Vapor
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Solution Overview
Problem
Existing methods for fabricating sandwich structures with ceramic matrix laminates face challenges in forming a strong bond between face plates and core materials, particularly at high temperatures, due to thermal expansion differences and adhesive degradation.
Innovation Solution
The use of a ceramic felt core sandwiched between two ceramic matrix composite face plates, coupled using a chemical vapor process, which allows for in-situ core fabrication and increased density of face plates, and the application of a compression assembly for uniform infiltration and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesives are used to bond face plates to core material, then bonding is achieved at room temperature, but the bond fails at high temperatures due to thermal expansion differences and adhesive degradation
Solution Approach 1:
The patent uses the same ceramic material (silicon carbide) for both the core substrate and the matrix material, ensuring thermal and chemical compatibility. This homogeneity eliminates thermal expansion mismatches and chemical incompatibility that cause adhesive failure at high temperatures, allowing the laminate to maintain bond strength at elevated temperatures up to 2000°C.
Solution Approach 2:
The patent replaces the mechanical/chemical bonding system (adhesives) with a diffusion-based bonding mechanism. The silicon carbide matrix diffuses into the silicon carbide core substrate at high temperatures, creating a metallurgical-like bond without requiring organic adhesives that would degrade thermally.
2Strength
If high density ceramic matrix composite face plates are used, then strength and temperature resistance are improved, but manufacturing complexity increases due to the infiltration process
Solution Approach 1:
The patent combines multiple fabrication steps into a single infiltration process. The same chemical vapor deposition process that forms the ceramic matrix composite face plates also simultaneously infiltrates and bonds the core substrate, eliminating separate bonding operations and reducing overall manufacturing complexity despite the advanced materials involved.
Solution Approach 2:
The core substrate serves multiple functions: it provides the structural core, acts as the bonding interface, and undergoes in-situ densification during the infiltration process. The material itself participates in the bonding mechanism through diffusion, eliminating the need for separate adhesive application and curing steps.
3Temperature
If ceramic felt core is used instead of honeycomb or foam core, then high temperature resistance is achieved, but density increases reducing the strength-to-density ratio
Solution Approach 1:
The patent transforms the physical and chemical parameters of the core substrate through the infiltration process. The core substrate undergoes densification and chemical composition changes as the silicon carbide matrix infiltrates and bonds to it, creating a gradient structure that maintains low density while achieving high temperature resistance and improved mechanical properties.
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 results in a ceramic matrix laminate with enhanced strength-to-density ratio, high temperature resistance, and improved shear stress capacity, surpassing traditional materials like honeycomb-core polymer composites.
Implementation Method 1
infiltrating the preform
Implementation Method 2
oxidizing the core substrate after infiltration
Data Source
AI summary
The invention provides systems and methods for forming low density ceramic felt material cores which are sandwiched between ceramic matrix composites to form a ceramic matrix laminate possessing a high strength-to-density ratio while maintaining a stiffness required for mechanical applications. The core and face plates are coupled together using a chemical vapor process.