Gas Turbine Ceramic Tile Attachment for Stress-Relieved Thermal Protection
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Solution Overview
Problem
Current thermal protection systems for gas turbine components face limitations in mechanical resistance, maximum operating temperature, thermal conductivity, and reliability due to stress issues at metal-ceramic interfaces, particularly with brazing methods, which can lead to overheating and detachment risks.
Innovation Solution
A thermal protection method involving the direct brazing, casting, or cementing of high-temperature resistant ceramic elements with a root portion into a seat within the metallic wall of gas turbine components, using an interface material to reduce stress and enhance the mechanical interlocking between ceramic and metal components, thereby forming a stress-free and reliable joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If brazing is used to join ceramic tiles to metal components, then mechanical attachment is achieved, but stress concentration and joint failure occur due to different thermal expansion coefficients
Solution Approach 1:
The patent introduces a metallic intermediate layer between the ceramic tile and the metal component. This intermediate layer acts as a stress-absorbing mediator that accommodates the differential thermal expansion between ceramic and metal, preventing stress concentration at the ceramic-metal interface and eliminating the need for brazing while maintaining strong mechanical attachment
Solution Approach 2:
The patent changes the physical state and properties of the metallic intermediate layer through controlled oxidation during processing. The layer transforms from a ductile metal state to a more brittle oxide state that provides both mechanical support and stress relief, fundamentally altering the stress distribution characteristics at the interface
2Temperature
If TBC (Thermal Barrier Coatings) are applied to protect metal surfaces, then thermal insulation is provided, but maximum operating temperature and thickness are limited
Solution Approach 1:
The patent employs a composite structure consisting of a ceramic tile layer for primary thermal protection, a metallic intermediate layer for mechanical support and stress management, and a metal substrate for structural integrity. This composite configuration enables the system to withstand temperatures exceeding conventional TBC limits while providing greater design flexibility in thickness and geometry
3Temperature
If mechanically fixed ceramic tiles are used for thermal protection, then thermal insulation is achieved, but gaps between tiles require additional cooling air
Solution Approach 1:
The patent merges the ceramic thermal protection function with the metal substrate structural function through direct mechanical attachment of ceramic tiles to the metal component surface. This integration eliminates gaps between protective elements and the substrate, preventing hot gas infiltration and reducing the need for cooling air to purge tile gaps
4Strength
If ceramic tiles are brazed to metal surfaces, then permanent joining is achieved, but shear stress and tensile stress cause ceramic failure
Solution Approach 1:
The metallic intermediate layer serves as a stress-distributing intermediary between the ceramic tile and metal substrate. It prevents direct stress transfer that would cause ceramic failure, instead distributing loads uniformly across the interface through plastic deformation and oxidation-induced property changes
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 method increases temperature capability by over 300K, reduces heat flux by more than 50%, decreases cooling air consumption, and enhances the reliability and versatility of thermal protection for various gas turbine components, minimizing the risk of ceramic element failure.
Implementation Method 1
Metal and ceramic materials feature significantly different thermal expansion coefficient, thus resulting in shear stress at the metal-ceramic interface and tensile stress within the ceramic material
Implementation Method 2
the surfaces of gas turbine components are protected by thermal barrier coatings which insulate components by means of thermally insulating materials, capable to sustain a significant temperature difference
Implementation Method 3
High temperature TPS based on brazing ceramic on metal surfaces of gas turbine components
Data Source
Figure 1
Figure 2~3
Figure 4A~5B
AI summary
A thermal protection system (3) for gas turbine components comprises a component (2) of a gas turbine (1) and a high temperature resistant ceramic element (4) which is coupled to a wall (5) of the component (2); the ceramic element (4) comprises at least a root portion (7) matching and engaging a hollow seat (10) formed in the wall (5) of the component (2); the root portion (7) is a brazed-in or cast-in or cemented-in root portion (7) so that the root portion (7) and the wall (5) of the component (2) are mechanically interlocked thus defining a shape-coupling (11), and are also connected by a brazed or cast or cemented joint (21).