Rub Material Using Polymer Micro-Balloons for Turbomachine Coating
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Solution Overview
Problem
Existing abradable coatings in turbomachines, such as those used in gas turbine engines, face issues with temperature management during rub interactions, where glass fillers can lead to higher surface temperatures and reduced aerodynamic efficiency due to their higher temperature capability compared to the polymer matrix, causing blade tip damage and heat flux into the blades.
Innovation Solution
A rub material comprising a polymeric matrix with polymer micro-balloons, such as silicone rubber and acrylonitrile micro-balloons, is used instead of glass fillers, limiting the maximum rub temperature by reducing the temperature capability of the filler and allowing it to wear away at a lower temperature, thus keeping blade tips cooler and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass fillers are used in the abradable coating, then the effective modulus of the coating is increased and deformation associated with aerodynamic forces is reduced, but the maximum rub temperature increases and heat flux into the blades increases
Solution Approach 1:
The patent changes the material parameter of the filler from glass (high temperature capability) to polymer micro-balloons (lower temperature capability). This parameter change reduces the maximum rub temperature while maintaining adequate coating modulus through the unique properties of polymer micro-balloons, resolving the contradiction between strength and temperature.
Solution Approach 2:
The patent uses a composite material system consisting of polymer matrix (silicone rubber) combined with polymer micro-balloons as filler. This composite approach allows the coating to achieve the desired balance between mechanical properties (modulus) and thermal properties (temperature capability) by combining materials with complementary characteristics.
2Strength
If glass fillers are used in the abradable coating, then the coating provides structural support, but blade tip damage occurs and aerodynamic efficiency is reduced
Solution Approach 1:
The patent changes the filler material parameter from glass to polymer micro-balloons, which have lower temperature capability and wear at lower temperatures. This prevents the high-temperature damage to blade tips while maintaining structural support through the composite structure of polymer matrix with micro-balloon reinforcement.
3Temperature
If the coating material has high temperature capability, then the coating can withstand higher temperatures, but heat flux into the blades increases
Solution Approach 1:
The patent changes the temperature capability parameter of the coating material from high (glass filler) to lower (polymer micro-balloons). This parameter change reduces the heat flux into the blades while the polymer matrix provides adequate thermal resistance, resolving the contradiction between temperature capability and energy loss.
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 use of polymer micro-balloons in the silicone matrix reduces the maximum rub temperature, limits heat flux into the blades, and enhances the durability of the coating by maintaining lower surface temperatures, thereby improving the aerodynamic efficiency and reducing blade tip damage.
Implementation Method 1
the micro-balloons have said concentration of 5-50% by volume... allowing it to wear away at a lower temperature
Implementation Method 2
limits the maximum rub temperature by reducing the temperature capability of the filler and allowing it to wear away at a lower temperature, thus keeping blade tips cooler and improving durability
Data Source
AI summary
A rub material (124) comprises a polymeric matrix (128) and polymeric micro-balloons (130) in the matrix.