CMC Seal Surface Coating for Leakage Reduction
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Solution Overview
Problem
Ceramic matrix composites (CMCs) used in gas turbine engines face challenges such as higher production costs, longer manufacturing times, limited geometries, porosity, and inconsistent machining, leading to efficiency losses due to cooling flow leakage and rough surfaces.
Innovation Solution
A ceramic matrix composite component with a seal surface coated with aluminum oxide and/or silicon dioxide, formed through grinding and electro discharge machining, followed by coating deposition, to enhance sealing and surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMCs are used to replace metallic nickel-based superalloys for high temperature resistance, then temperature resistance is improved, but manufacturing precision deteriorates due to porosity and inconsistent machining
Solution Approach 1:
A coating is applied to the CMC sealing surface before final machining operations. This preliminary coating layer protects the underlying CMC material from machining-induced roughness and provides a consistent surface finish that compensates for the orthotropic nature of CMCs
Solution Approach 2:
The patent changes the physical and chemical parameters of the sealing surface by applying a specialized coating that modifies surface properties. This coating alters the effective thermal expansion characteristics and surface morphology to achieve consistent sealing performance despite CMC's inherent manufacturing variability
2Temperature
If CMCs are used for high temperature resistance, then temperature resistance is improved, but reliability deteriorates due to porosity allowing cooling flow leakage
Solution Approach 1:
The patent applies a specialized coating specifically to the sealing surfaces of CMC components where sealing is critical. This localized treatment addresses the porosity issue at the sealing interface without requiring changes to the entire CMC structure, maintaining high temperature resistance while improving local sealing reliability
Solution Approach 2:
The coating acts as an intermediary layer between the porous CMC material and the sealing interface. This intermediate layer fills or seals the porous pathways that would otherwise allow cooling flow leakage, while still allowing the CMC to function at high temperatures
3Temperature
If CMCs are used for high temperature resistance, then temperature resistance is improved, but production efficiency deteriorates due to longer manufacturing cycle times
Solution Approach 1:
The coating is applied as a preliminary step that consolidates multiple potential operations into one. By applying the coating before final machining and sealing operations, the patent reduces the total number of manufacturing steps required, thereby reducing overall manufacturing cycle time despite the added coating process
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 coated CMC components provide improved sealing and reduced efficiency losses by maintaining a smooth surface finish and matching the coefficient of thermal expansion of the substrate, preventing undulations and gaps that could lead to leakage.
Implementation Method 1
matching the coefficient of thermal expansion of the substrate, preventing undulations and gaps that could lead to leakage
Implementation Method 2
depositing a coating on the CMC component. The coating includes aluminum oxide and/or silicon dioxide
Data Source
AI summary
A ceramic matrix composite (CMC) component includes at least one seal surface, the at least one seal surface disposed adjacent an interfacing surface for providing a seal therebetween; and a coating disposed on the seal surface. The coating includes an aluminum oxide and/or a silicon dioxide.