Abradable Coating Protrusion Wear Pattern Turbine Seal
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Solution Overview
Problem
Current methods for reducing blade wear in gas turbine engines, such as using abradable ceramic coatings, lead to increased tip clearance due to erosion and thermal breakdown, resulting in decreased engine efficiency.
Innovation Solution
A method involving a substrate with protrusions and an unconverted topcoat, where an initial rub event creates a wear pattern and subsequent high-temperature conversion hardens the topcoat, preserving the channel and maintaining equal wear between the blade tip and seal, thereby reducing clearance and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If abradable ceramic coatings are used on BOAS, then blade wear is reduced, but tip clearance increases due to erosion and thermal breakdown
Solution Approach 1:
The coating is pre-converted at lower temperature before engine operation to establish thermal stability and controlled abradability. This preliminary thermal treatment ensures the coating will maintain proper wear characteristics during subsequent high-temperature operation, preventing both excessive wear and thermal breakdown that would increase tip clearance
Solution Approach 2:
The patent applies a two-stage thermal treatment process: initial conversion at lower temperature (first parameter state) followed by in-service conversion at higher temperature (second parameter state). This parameter transformation sequence optimizes the coating's thermal and mechanical properties to balance wear resistance with tip clearance maintenance
2Strength
If abradable ceramic coatings are used, then blade tip protection is improved, but coating durability decreases due to erosion and thermal breakdown
Solution Approach 1:
The coating undergoes preliminary thermal conversion before engine operation to pre-establish its thermal stability and structural integrity. This preliminary action prepares the coating to resist erosion and thermal breakdown during prolonged service, extending its durable life while maintaining protective functions
Solution Approach 2:
The initial low-temperature conversion creates a buffer zone of thermal stability that cushions the coating against subsequent high-temperature thermal shock and erosion. This beforehand cushioning prevents catastrophic thermal breakdown and extends coating service life
3Temperature
If thermally insulating ceramic coating is applied, then heat protection is improved, but wear resistance decreases due to abradability requirements
Solution Approach 1:
The coating's thermal and mechanical properties are transformed through controlled thermal conversion at different stages. Initial conversion at lower temperature establishes baseline thermal stability, while subsequent high-temperature conversion in service optimizes both thermal insulation and wear resistance properties simultaneously
4Loss of energy
If blade tip clearance is reduced, then engine efficiency is improved, but blade wear increases
Solution Approach 1:
The coating is pre-treated thermally before engine operation to establish optimal abradability and wear characteristics. This preliminary preparation ensures that when the blade operates at reduced clearance for improved efficiency, the coating will wear controllably to maintain the clearance without causing excessive blade wear
Solution Approach 2:
Through controlled thermal conversion, the coating's physical and chemical parameters are optimized to achieve a balance where reduced tip clearance can be maintained while wear is controlled through the coating's transformed structural properties
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
This approach results in a long-lasting, abradable and durable coating that maintains optimal sealing between the blade tip and the seal, reducing air leakage and improving engine efficiency by preserving the wear pattern and resisting particle erosion.
Implementation Method 1
converting the topcoat... converting the coating during a high-temperature event
Implementation Method 2
subsequent high-temperature conversion hardens the topcoat
Data Source
AI summary
A method of forming a coating includes disposing a substrate having a plurality of protrusions on a seal and layering a topcoat over the protrusions. The method of forming a coating also includes creating a wear pattern and converting the topcoat. A turbine section includes a casing, a plurality of blades within the casing, and a substrate deposited on the casing having a plurality of protrusions. The turbine also includes an unconverted topcoat disposed over the plurality of protrusions, the topcoat having segmented portions defining a plurality of faults extending from the protrusions through the topcoat. A method of forming a coating includes creating a channel in the coating during an initial rub event and converting the coating during a high-temperature event. Converting the coating includes preserving the channel created during the initial rub event.