Polyimide Abrasive Blade Tip for High-Temperature Bond Durability
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Solution Overview
Problem
Existing abrasive tips for rotatable blades in gas turbine engines face challenges with high processing temperatures during manufacturing and heat generation during operation, leading to potential delamination of polymeric overcoats and loosening of bonds between the blade and reinforcements due to heat conduction, which affects the longevity and performance of the abrasive tips.
Innovation Solution
The development of an abrasive tip with hard particles in a polymeric matrix material having a glass transition temperature greater than or equal to 225 degrees C, combined with fibers and an adhesive bonding, which provides improved heat resistance and reduced heat conductivity to mitigate these issues, along with a method of fabricating and attaching the tip to the airfoil section using a process that avoids elevated temperatures for bonding the overcoat and reinforcements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polymeric matrix materials with lower glass transition temperatures are used in abrasive tips, then ease of manufacture and bonding is improved, but heat resistance deteriorates causing delamination and bond loosening at high temperatures
Solution Approach 1:
The patent changes the fundamental thermal parameter of the matrix material by selecting polyimide with a glass transition temperature of at least 225°C, compared to conventional lower-temperature polymers. This parameter change enables the abrasive tip to maintain structural integrity and bonding at elevated temperatures without requiring complex modified bonding processes
Solution Approach 2:
The patent creates a composite material system combining polyimide matrix with abrasive particles (such as alumina, silica, or diamond). This composite structure provides both the high heat resistance needed for turbine engine environments and the abrasive functionality required for seal contact, while the polyimide binder maintains adequate bonding characteristics
2Duration of action of moving object
If conventional abrasive tips are used in gas turbine engines, then initial manufacturing is simpler, but longevity deteriorates due to heat-generated delamination and bond loosening during operation
Solution Approach 1:
By specifying a minimum glass transition temperature of 225°C for the polyimide matrix, the patent ensures the material can withstand operating temperatures in turbine engines without softening or degrading. This parameter threshold guarantees long-term durability while the polyimide's inherent properties provide adequate bonding strength, avoiding the need for overly complex material systems
Solution Approach 2:
The patent replaces conventional lower-cost, lower-temperature polymers with polyimide, which has higher initial material cost but dramatically extended service life. The increased longevity eliminates frequent replacement needs, making the overall system more economical despite the higher initial material specification
3Strength
If polymeric overcoats are applied to blade airfoil sections, then protection from damage is improved, but heat resistance deteriorates causing overcoat delamination at high processing and operating temperatures
Solution Approach 1:
The patent applies polyimide as an overcoat material on the blade airfoil section. Polyimide provides both protective functions (erosion and damage resistance) and high-temperature stability with a glass transition temperature of at least 225°C. This composite overcoat structure maintains protection capability while resisting heat-induced delamination that plagues conventional polymeric coatings
Solution Approach 2:
By selecting polyimide with elevated glass transition temperature (≥225°C) for the overcoat, the patent changes the thermal stability parameter of the protective layer. This enables the overcoat to maintain adhesion and protective function at the high temperatures encountered during both manufacturing processes and engine operation, preventing the delamination issues associated with lower-temperature polymers
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 temperature resistance and longevity of the abrasive tips, maintaining their thickness and bond integrity under rubbing conditions, reducing heat transfer and adhesive softening, thereby improving the durability and performance of the blades.
Implementation Method 1
The matrix material is a polymeric material that has a glass transition temperature greater than or equal to about 225 degrees C. (437 degrees F.)
Implementation Method 2
The blade includes an adhesive bonding the abrasive tip to the airfoil section
Implementation Method 3
Abradable seals or coatings (rub coatings) can be used to protect moving parts from damage during rub interaction
Data Source
AI summary
A blade includes an airfoil section extending between leading and trailing edges, first and second opposed sides each joining the leading and trailing edges, and an inner end and a free end. The blade also includes an abrasive tip at the free end of the airfoil section. The abrasive tip includes particles disposed in a matrix material. The matrix material is a polymeric material that has a glass transition temperature greater than or equal to about 225 degrees C. (437 degrees F.). A gas turbine engine and a method of fabricating a blade are also disclosed.