Multi-Layer Thermal Barrier Coating for Gas Turbine Erosion Resistance
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Solution Overview
Problem
High-temperature mechanical systems, such as gas turbine engines, face challenges with thermal barrier coatings (TBCs) due to erosion and contamination from deleterious environmental species like CMAS, which degrade the coatings and reduce their effectiveness in protecting the substrate, and traditional deposition techniques like EB-PVD are inefficient and limited in producing multi-layer coatings with varying microstructures.
Innovation Solution
A multi-layer TBC is formed using a suspension plasma spray technique, comprising layers with columnar and dense microstructures, deposited using fine particles to prevent environmental species migration and improve thermal cycling performance, while offering improved efficiency and cost-effectiveness compared to traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional EB-PVD technique is used to form TBC, then coating can be deposited, but the deposition process is inefficient and limited in producing multi-layer coatings with varying microstructures
Solution Approach 1:
The TBC is divided into multiple layers (first layer with first microstructure, second layer with second microstructure, third layer with third microstructure) where each layer has different microstructural characteristics. This segmentation allows each layer to be optimized for specific functions such as thermal insulation, erosion resistance, and environmental species barrier properties, resolving the limitation of traditional single-layer or uniform microstructure coatings
Solution Approach 2:
Different regions of the coating (different layers) are given different microstructural qualities - the first layer may have a columnar microstructure for thermal insulation, the second layer may have a mixed microstructure for intermediate properties, and the third layer may have a equiaxed microstructure for erosion resistance. This local differentiation of properties enables the coating to address multiple performance requirements simultaneously
2Temperature
If TBC is used to protect substrate from high temperatures, then substrate temperature is reduced, but erosion and contamination from environmental species like CMAS degrade the coating effectiveness
Solution Approach 1:
The TBC system uses composite material structures with multiple layers having different compositions and microstructures. The combination of layers with varying porosity, phase composition, and microstructural characteristics creates a composite system that provides both thermal protection and resistance to erosion and chemical contamination from environmental species
Solution Approach 2:
The coating incorporates layers with controlled porosity - some layers may have higher porosity for thermal insulation while other layers have lower porosity to act as barriers against environmental species penetration. The porous structure is strategically designed to balance thermal performance with protection against erosion and contamination
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 multi-layer TBC effectively reduces thermal energy transfer, enhances erosion resistance, and extends the service life of high-temperature components by preventing deleterious species from penetrating the coating, thereby improving thermal cycling performance and durability.
Implementation Method 1
A multi-layer TBC is formed using a suspension plasma spray technique
Implementation Method 2
thermal barrier coating (TBC) to reduce the substrate temperatures
Data Source
AI summary
An article that includes a substrate; a first layer including yttria and zirconia or hafnia, where the first layer has a columnar microstructure and includes predominately the zirconia or hafnia; a second layer on the first layer, the second layer including zirconia or hafnia, ytterbia, samaria, and at least one of lutetia, scandia, ceria, neodymia, europia, and gadolinia, where the second layer includes predominately zirconia or hafnia, and where the second layer has a columnar microstructure; and a third layer on the second layer, the third layer including zirconia or hafnia, ytterbia, samaria, and a rare earth oxide including at least one of lutetia, scandia, ceria, neodymia, europia, and gadolinia, where the third layer has a dense microstructure and has a lower porosity than the second layer.