CMC Surface Silicon Extraction for Gas Turbine Interfaces
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Solution Overview
Problem
High-temperature reactions between metallic elements in metal components and unreacted silicon in ceramic matrix composites (CMCs) lead to detrimental diffusion and phase formation, compromising the performance of gas turbine engine components.
Innovation Solution
A method to reduce free silicon in the surface region of CMC components by contacting them with a wicking medium containing a reactive element at elevated temperatures, limiting diffusion and reactions with metal components during assembly and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If free silicon is present in the CMC component after melt infiltration, then the CMC component achieves its structural integrity and material properties, but detrimental reactions and diffusion occur at high temperatures between metallic elements and free silicon
Solution Approach 1:
The patent extracts free silicon from the surface region of the CMC component by contacting it with a wicking medium containing a reactive element at elevated temperatures. This removes the harmful free silicon that would otherwise diffuse into metal components and form low-melting-temperature phases, while preserving the structural integrity of the CMC component.
Solution Approach 2:
The patent introduces a wicking medium containing a reactive element as an intermediary between the CMC component and the metal component. This intermediary selectively reacts with free silicon in the CMC, preventing direct contact and harmful reactions between silicon and metallic elements, thereby protecting the metal-CMC interface.
2Productivity
If the CMC component is assembled with a metal component at high temperatures, then the composite structure achieves its functional performance, but unwanted reactions occur across the metal-CMC interface
Solution Approach 1:
The patent performs preliminary action by extracting free silicon from the CMC component surface before assembly with the metal component. This pre-treatment prevents harmful reactions during high-temperature operation, allowing the metal-CMC composite to be assembled and operated without detrimental interface reactions.
3Stability of the object's composition
If the surface region of the CMC component contains free silicon, then the material maintains its desired composition and properties, but diffusion into metal components occurs at elevated temperatures
Solution Approach 1:
The patent applies local quality by selectively modifying only the surface region of the CMC component where free silicon is extracted, while preserving the bulk material composition and properties. This localized treatment prevents diffusion at the critical interface region without altering the overall material characteristics of the CMC component.
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
Significantly reduces unwanted reactions and diffusion across the metal-CMC interface, enhancing the thermal stability and mechanical properties of composite components in gas turbine engines.
Implementation Method 1
At high temperatures, the free silicon present in the CMC component may become highly mobile and diffuse into the metal component
Implementation Method 2
The extraction comprises contacting the surface region with a wicking medium comprising an element reactive with silicon
Data Source
AI summary
A method of processing a ceramic matrix composite (CMC) component includes extracting silicon from a surface region of the CMC component such that free silicon is present in the surface region at a reduced amount of about 5 vol. % or less. The extraction comprises contacting the surface region with a wicking medium comprising an element reactive with silicon. The extraction is carried out at an elevated temperature prior to assembling the CMC component with a metal component.