Abradable Layer Composition for Gas Turbine Sealing
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Solution Overview
Problem
High-temperature mechanical systems, such as gas-turbine engines, face challenges in maintaining efficiency due to gas leakage between turbine blades and shrouds, which existing abradable coatings fail to adequately address, especially under extreme temperature conditions and CMAS reactions.
Innovation Solution
An abradable layer comprising zirconia or hafnia as the base oxide, with ytterbia as the primary dopant and samaria, lutetia, scandia, ceria, gadolinia, or neodymia as co-dopants, providing porosity between 25 vol.% and 50 vol.% and lacking yttria to enhance erosion resistance and thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional abradable coatings are used to reduce gas leakage, then sealing performance improves, but erosion resistance and CMAS reaction resistance deteriorate under extreme temperature conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the abradable coating by using zirconia or hafnia as base oxide with specific rare earth oxide dopants (ytterbia, samaria, lutetia, scandia, ceria, gadolinia, neodymia, europia) and eliminating yttria. This compositional parameter change provides both adequate abradability for sealing and improved resistance to erosion and CMAS reactions under extreme temperatures.
Solution Approach 2:
The patent creates a composite material system combining zirconia or hafnia base oxide with multiple rare earth oxide dopants. This composite structure achieves synergistic effects where the base oxide provides mechanical strength and thermal stability, while the rare earth dopants enhance CMAS reaction resistance and control abradability, resolving the contradiction between sealing performance and durability.
2Productivity
If the gap between blade tip and shroud is reduced to increase efficiency, then energy loss decreases, but the demand for abradable layer performance increases under higher temperature conditions
Solution Approach 1:
The patent modifies the thermal and mechanical parameters of the abradable coating through selective doping with rare earth oxides. The chosen dopants (particularly ytterbia, samaria, and the combination with lutetia, scandia, ceria, gadolinia, neodymia, or europia) provide enhanced thermal stability and structural integrity at elevated temperatures, enabling the coating to maintain its sealing function under the increased temperature conditions required for higher efficiency operation.
3Use of energy by stationary object
If porosity is increased to enhance thermal insulation, then thermal insulation performance improves, but mechanical strength may deteriorate
Solution Approach 1:
The patent employs a composite material system where zirconia or hafnia base oxide provides mechanical strength framework, while rare earth oxide dopants (ytterbia, samaria, lutetia, scandia, ceria, gadolinia, neodymia, europia) create a synergistic structure that maintains both porosity for thermal insulation and sufficient mechanical strength. The specific combination of dopants reinforces the porous structure, preventing collapse while maintaining insulation performance.
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 abradable layer effectively reduces gas leakage, increases engine efficiency by up to 5%, and resists CMAS reactions, maintaining thermal insulation and mechanical integrity under high-temperature conditions.
Implementation Method 1
As the turbine blade rotates, the tip of the turbine blade contacts the abradable layer and wears away a portion of the layer to form a groove in the abradable layer corresponding to an approximate path of the turbine blade
Implementation Method 2
The abradable layer is porous, and comprises a porosity between about 25 vol. % and about 50 vol. %
Data Source
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AI summary
A system may include a blade track or blade shroud and a gas turbine blade that includes a blade tip. The blade track or blade shroud may include a substrate and an abradable layer formed over the substrate. The abradable layer may include at least one of zirconia or hafnia; ytterbia; samaria; and at least one of lutetia, scandia, ceria, gadolinia, neodymia, or europia. The abradable layer may include a porosity between about 25 vol. % and about 50 vol. %. The blade track or blade shroud and the gas turbine blade may be configured so the blade tip contacts a portion of the abradable layer during rotation of the gas turbine blade, and the abradable layer may be configured to be abraded by the contact by the blade tip.