Abradable Coating Oxygen Debit Blending for High-Temperature Stability
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Solution Overview
Problem
Current abradable system pairs in gas turbine engines face limitations in high-pressure compressor development due to temperature-induced diffusion reactions, hot corrosion, and abrasive failure at elevated temperatures.
Innovation Solution
A method involving blending a first ceramic powder with a significant oxygen debit and a second ceramic powder with a lower oxygen debit, followed by thermal spraying and optional oxidation to reduce the net oxygen debit, is used to create an abradable coating with improved high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional abradable coatings are used in high-pressure compressor applications, then the system can operate at elevated temperatures, but the coatings suffer from temperature-induced diffusion reactions, hot corrosion, and abrasive failure
Solution Approach 1:
The patent applies composite materials by creating an abradable coating system consisting of multiple ceramic layers with different compositions and properties. The first layer contains ceramic particles in a metallic matrix providing abradability, while the second layer provides oxidation resistance. This composite structure allows the coating to withstand high temperatures without diffusion reactions and hot corrosion, while maintaining reliability through the protective second layer.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition and microstructure of the abradable coating through controlled oxidation. The coating is subjected to oxidation treatment that transforms the metallic matrix and ceramic particles, creating a more stable and corrosion-resistant structure. This parameter change in the material's chemical state improves its resistance to hot corrosion and diffusion reactions at elevated temperatures.
2Ease of operation
If the abradable coating is made softer to improve abradability, then cutting performance improves, but the coating becomes more susceptible to damage and failure at high temperatures
Solution Approach 1:
The patent applies local quality by creating distinct layers with different properties within the abradable coating system. The first layer near the rubbing surface is designed to be softer and more abradable for good cutting performance, while the second outer layer is designed to be harder and more oxidation-resistant for protection. This local differentiation of material properties allows the coating to simultaneously achieve ease of operation through controlled abradability and strength through protective hardening.
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 solution enhances the durability and temperature resistance of abradable coatings, reducing sintering and improving cutting performance without excessive dulling of the abrasive, thereby supporting higher compression ratios in gas turbine engines.
Implementation Method 1
thermal spraying the blend
Implementation Method 2
oxidizing the sprayed blend to reduce a net oxygen debit by at least 50%
Data Source
AI summary
In a method for forming an abradable material (36), the abradable material has at least 20% by volume rutile titania (44) and hBN (46). The method includes: blending a first titania powder having an oxygen debit of at least 5.0% with a second titania powder having an oxygen debit, if any, of less than 1.0%. The blend is thermal sprayed. The sprayed blend is then oxidized.