Abradable Ceramic Coating for Gas Turbine Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current gas turbine engines face challenges in reducing over-tip leakage and maintaining efficiency at high temperatures, with existing sealing methods being complex and inefficient.
Innovation Solution
A gas turbine engine design featuring an abradable runner with a substrate, an aluminum-containing bond coat, an intermediate ceramic layer with a stabilized tetragonal phase constitution, and an abradable ceramic layer, which reduces thermal conductivity and allows for abradability, eliminating the need for labyrinth sealing and active tip clearance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If labyrinth sealing and active tip clearance control are used to reduce over-tip leakage, then sealing effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent extracts the sealing function from complex mechanical systems (labyrinth seals and active clearance control) and implements it through a simple abradable ceramic coating layer on the blade track. This coating layer directly provides the sealing effect by being abraded during blade contact, eliminating the need for complex sealing mechanisms while maintaining sealing effectiveness.
Solution Approach 2:
The abradable ceramic coating layer performs self-service by automatically adjusting the tip clearance through controlled abrasion during blade contact. The coating is designed to wear away progressively, maintaining optimal sealing clearance without requiring external active control systems, thus simplifying the overall device while preserving sealing reliability.
2Power
If higher inlet temperatures are used to improve efficiency, then power output increases, but thermal stress and material degradation worsen
Solution Approach 1:
The patent employs a composite thermal barrier coating system consisting of multiple layers: a bond coat layer, an intermediate ceramic layer with stabilized tetragonal phase, and an abradable ceramic layer. This composite structure combines materials with complementary properties to resist thermal stress, prevent oxidation, and maintain structural integrity at high operating temperatures, enabling higher power output while preserving reliability.
Solution Approach 2:
The patent utilizes parameter changes in the ceramic coating materials, specifically the phase transformation properties of zirconia (tetragonal to monoclinic transition), to accommodate thermal expansion and contraction cycles. The stabilized tetragonal phase in the intermediate layer provides thermal shock resistance by controlling phase transformation behavior, allowing the system to withstand high temperature variations without failure.
3Reliability
If abradable ceramic layer with high porosity is used to improve abradability, then sealing performance improves, but mechanical strength decreases
Solution Approach 1:
The patent applies local quality by creating distinct porosity levels in different coating layers. The abradable ceramic layer has high porosity (30-50%) to ensure easy abrasion and effective sealing, while the intermediate ceramic layer has lower porosity (10-20%) to provide mechanical strength and structural support. This spatial variation in porosity allows each layer to optimize its function without compromising the other.
Solution Approach 2:
The thermal barrier coating is segmented into multiple functional layers: a dense bond coat for adhesion, an intermediate ceramic layer for mechanical strength and thermal insulation, and an abradable ceramic layer for sealing. This segmentation allows each layer to be optimized independently for its specific function, with the intermediate layer compensating for the reduced strength of the highly porous abradable layer.
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 design enhances durability, erosion resistance, and thermal shock resistance, allowing for higher operating temperatures and improved efficiency with reduced specific fuel consumption and simpler configurations.
Implementation Method 1
the abradable ceramic layer is configured to be abraded by the contact by the blade tip
Implementation Method 2
The intermediate layer includes between about 4 wt. % and about 20 wt. % yttria and a balance zirconia or hafnia... The abradable ceramic layer defines a second porosity, and the second porosity is higher than the first porosity
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An article may include a substrate including a metal or alloy; a bond coat directly on the substrate; an intermediate ceramic layer on the bond coat; and an abradable ceramic layer directly on the intermediate ceramic layer. The intermediate ceramic layer includes a stabilized tetragonal prime phase constitution and defines a first porosity. The abradable ceramic layer includes zirconia or hafnia stabilized in the tetragonal prime phase by a second mixture including between about 5 wt. % and about 10 wt. % ytterbia, between about 0.5 wt. % and about 2.5 wt. % samaria, and between about 1 wt. % and about 4 wt. % of at least one of lutetia, scandia, ceria, neodymia, europia, or gadolinia, and a balance zirconia or hafnia. The abradable ceramic layer defines a second porosity, and the second porosity is higher than the first porosity.