Short-Fiber CMC Honeycomb Abradable Coating for Hot Turbomachines
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Solution Overview
Problem
Existing abradable coatings in turbomachines are heavy, require cooling due to their metallic composition, and cannot be made from long-fiber ceramic matrix composite (CMC) due to thickness limitations, limiting their ability to adapt to complex geometries and withstand high temperatures.
Innovation Solution
An abradable coating with a tubular cell structure composed of short discontinuous fibers densified by a ceramic matrix, allowing for complex shapes and reduced thickness, integrated with CMC materials, reducing mass and cooling requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic tubular cell structures are used for abradable coatings, then the structural strength and integrity are maintained, but the mass increases and cooling requirements arise
Solution Approach 1:
The patent applies composite materials by combining ceramic matrix composite (CMC) with metallic tubular cell structures. The CMC provides high-temperature resistance and reduced density, while the metallic structure maintains mechanical strength. This composite approach resolves the contradiction between strength and weight by integrating materials with complementary properties.
2Temperature
If long-fiber ceramic matrix composite is used, then high-temperature resistance is achieved, but the thickness cannot be reduced below 0.2 mm due to weaving limitations
Solution Approach 1:
The patent utilizes porous CMC materials with controlled porosity to achieve both high-temperature resistance and reduced thickness. The porous structure allows the material to maintain mechanical integrity at thin dimensions while retaining thermal barrier properties. This enables thickness reduction below the 0.2 mm limitation of woven long-fiber CMC.
3Productivity
If the abradable coating is placed directly in the combustion chamber, then aerodynamic efficiency is improved, but the coating is exposed to hot combustion gases requiring cooling
Solution Approach 1:
The patent changes the material parameters of the abradable coating by using CMC materials with inherent high-temperature resistance. This parameter change allows the coating to withstand direct exposure to combustion gases without requiring active cooling systems, thereby maintaining aerodynamic efficiency while tolerating thermal exposure.
4Productivity
If complex geometries are required for the abradable coating, then aerodynamic performance is optimized, but manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by varying the density, porosity, and fiber orientation of the CMC material in different regions of the abradable coating. This allows optimization of local aerodynamic performance while maintaining manufacturability through targeted material property adjustments rather than complex geometric modifications throughout the entire structure.
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 coating provides improved adaptability to complex geometries, reduces mass and cooling needs, and ensures continuity with CMC components, enhancing operational efficiency and aerodynamic performance.
Implementation Method 1
the densification of the first preform of the assembly by infiltration with a molten composition comprising silicon
Implementation Method 2
the molten composition allows the tubular cell structure to be welded to the component
Implementation Method 3
a fibrous reinforcement of short discontinuous fibers densified by a ceramic matrix
Data Source
Figure 1~2
Figure 3A~3D
Figure 4
AI summary
Abradable coating (100) comprising a tubular cell structure, characterized in that the tubular cell structure comprises a fibrous reinforcement of discontinuous short fibres densified by a ceramic matrix.