Repairable Gas Turbine Coating System with Mesh Layer
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Solution Overview
Problem
Conventional coating systems for gas turbine engine components exposed to severe environmental conditions, such as high temperatures and corrosive substances, are non-repairable, leading to economical losses due to scrapping when layers wear away.
Innovation Solution
A coating system comprising a bond layer of CoNiCrAlY, a thermal barrier layer of yttria stabilised zirconia, and a mesh layer of CoNiCrAlY, with an abradable layer of magnesium spinel, allowing for partial removal and replacement of the thermal and abradable layers using water jet stripping without damaging the mesh and bond layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional coating system is used, then the article is protected from severe environmental conditions, but the coating system cannot be repaired when layers wear away, leading to scrapping of the article
Solution Approach 1:
The coating system is divided into distinct functional layers: a bond layer that remains permanently attached to the substrate, and a replaceable coating layer that can be removed and replaced. This segmentation allows the protective function to be maintained while enabling repairability through replacement of the worn layer.
Solution Approach 2:
The replaceable coating layer is designed to be removable when worn, allowing it to be discarded and replaced with a fresh layer. The bond layer is recovered and retained on the substrate, enabling the article to be reused without scrapping the entire component.
2Ease of repair
If the coating system is made repairable by allowing removal of layers, then the article can be reused, but the bond layer may be damaged during removal process
Solution Approach 1:
The coating system is divided into a bond layer and a replaceable coating layer with distinct functions. The bond layer is designed to remain permanently attached to the substrate through strong adhesion, while the replaceable coating layer can be removed without affecting the bond layer's integrity.
Solution Approach 2:
The replaceable coating layer is extracted as a separate, removable component from the bond layer. This allows the coating to be removed and replaced while the bond layer remains intact on the substrate, preventing damage to the bond layer during the removal process.
3Reliability
If a thick coating system is applied to provide adequate protection, then the article is well-protected, but the removal process becomes more difficult and time-consuming
Solution Approach 1:
The coating system is segmented into a bond layer and a replaceable coating layer. This segmentation allows the replaceable layer to be removed independently even when thick, reducing the time required for removal compared to removing an entire thick coating system.
Solution Approach 2:
The replaceable coating layer is extracted as a separate component that can be removed without affecting the bond layer. This extraction approach enables efficient removal of thick coatings by targeting only the replaceable layer, minimizing the time and effort required for maintenance.
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
Enables the protection of gas turbine engine components from severe environmental conditions and allows for repair of the coating system, extending the component's operational life and reducing economic losses associated with scrapping.
Implementation Method 1
the abradable layer and the thermal barrier layer are at least partially removable from the mesh layer and the bond layer without damaging the mesh layer and the bond layer
Data Source
AI summary
A coating system includes a bond layer including CoNiCrAlY; a thermal barrier layer at least partially disposed on the bond layer and including yttria stabilised zirconia; a mesh layer connecting the thermal barrier layer to the bond layer and including CoNiCrAlY; and an abradable layer disposed on the thermal barrier layer and including magnesium spinel. The mesh layer includes a plurality of cells connected to each other and is at least partially embedded in the thermal barrier layer. Each cell defines a cell opening therethrough and the cell opening of each of the plurality of cells at least partially receives the thermal barrier layer therein. The abradable layer and the thermal barrier layer are at least partially removable from the mesh layer and the bond layer without damaging them.