Abradable Turbine Seal Material with Organic Microballoons
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Solution Overview
Problem
In gas turbine engines, traditional abradable seal materials with glass microspheres and inorganic fillers can melt or fuse, causing residue that blocks air cooling holes and adheres to engine components, leading to reduced engine longevity due to high operating temperatures.
Innovation Solution
A high-temperature resilient abradable material comprising a silicone polymeric matrix with organic microballoons, reduced levels of residue-forming elements, and less than one weight percent of inorganic filler, specifically fumed silica with particle sizes up to 20 nanometers, providing thermal stability and abradability up to 550°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass microspheres and inorganic fillers are used in abradable seal material, then matrix reinforcement and thermo-oxidative stability are improved, but residue forms that blocks air cooling holes and adheres to engine components
Solution Approach 1:
The patent removes glass microspheres and significantly reduces inorganic filler content (to less than 1 weight percent) from the abradable seal material formulation. This extraction of harmful residue-forming components eliminates the source of blockages while maintaining material performance through alternative organic microballoon fillers and optimized silicone polymer matrix composition.
2Strength
If inorganic fillers are used for matrix reinforcement, then material strength is improved, but materials melt and fuse at high temperatures causing blockages
Solution Approach 1:
The patent fundamentally changes the material composition parameters by replacing inorganic fillers with organic microballoon fillers and optimizing the silicone polymer matrix. This parameter change shifts the material's thermal behavior so that it decomposes into gases rather than melting and fusing, achieving thermal stability above 500°C without residue formation that causes blockages.
3Reliability
If silicone rubber matrix is abraded at high temperatures, then sealing function is maintained, but silicone oxidizes to form residue that blocks cooling holes
Solution Approach 1:
The patent transforms the harmful oxidation reaction into a beneficial outcome by formulating the silicone polymer matrix with specific compositional ratios and adding antioxidants. The controlled oxidation now produces gaseous products that escape through the abraded seal rather than forming solid residue, converting the harmful blocking effect into a harmless gas release mechanism.
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 material maintains matrix reinforcement and thermo-oxidative stability, reduces residue-related blockages, and enhances erosion resistance, offering improved abradability and longevity in high-temperature environments without adhering to engine components.
Implementation Method 1
The organic microballoon particles are selected from a material that is stable to a temperature of at least about 400 degrees Fahrenheit (204°C)
Implementation Method 2
up to 30 weight percent of fumed silica having a maximum particle size no larger than from about 5 nanometers to about 20 nanometers
Implementation Method 3
When the silicone rubber is abraded and is passed through the turbine, the silicone is oxidized to form water, carbon dioxide, and silica
Data Source
AI summary
The invention comprises an abradable material containing up to 30 weight percent of fumed silica having a maximum particle from about 5 nanometers to about 20 nanometers and about 1.5 to about 5 weight percent of an abradable organic microballoon filler within an abradable silicone polymer matrix having an elasticity of less than 300 percent.