Non-continuous abradable coating blocks for turbine sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Continuous abradable coatings in high-temperature mechanical systems face issues with increased residual stress, reduced bond strength, and reduced useful life due to thermal and mechanical conditions, leading to premature replacement and increased leakage.
Innovation Solution
A non-continuous abradable coating with distinct portions of coating blocks differing in parameters such as size, pitch, and shape, applied using thermal spraying with templates to reduce stress and enhance erosion resistance, allowing for improved abradability and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous abradable coating is applied to reduce clearance and improve sealing, then leakage is reduced, but residual stress increases and bond strength decreases
Solution Approach 1:
The coating is divided into discrete coating blocks separated by spacing rather than forming a continuous layer. This segmentation reduces residual stress by allowing thermal expansion and contraction of individual blocks independently, while maintaining sealing effectiveness through the distributed block structure that still contacts the rotating blade.
Solution Approach 2:
The coating blocks have varying properties in different regions - the blade rub portion has different coating block parameters (size, pitch, shape) compared to the first and second portions. This local differentiation optimizes each region for its specific function: the blade rub portion for ease of abrasion and the other portions for structural integrity and sealing.
2Ease of manufacture
If a uniform abradable coating is used to simplify manufacturing, then ease of manufacture improves, but blade rub performance and erosion resistance decrease
Solution Approach 1:
Different portions of the coating have different block parameters optimized for their specific functions. The blade rub portion has coating blocks with parameters optimized for easy abrasion by the rotating blade, while the first and second portions have parameters optimized for erosion resistance and structural stability, allowing each region to perform optimally.
Solution Approach 2:
The coating is segmented into distinct portions with different characteristics rather than being uniform. This segmentation allows the blade rub portion to be optimized for abrasion while other portions are optimized for different functions, improving overall performance despite increased manufacturing complexity.
3Reliability
If more coating material is applied to ensure adequate protection, then erosion resistance improves, but material consumption increases and coating life decreases
Solution Approach 1:
The discontinuous block structure reduces material consumption compared to a continuous coating while maintaining protective function. The spacing between blocks allows for reduced material usage while the blocks themselves provide sufficient erosion resistance and blade rub performance when properly designed.
Solution Approach 2:
Coating material is concentrated in the block portions where it is most needed for protection rather than being distributed uniformly across the entire surface. This local concentration of material in the coating blocks provides adequate erosion resistance and blade rub performance while minimizing overall material consumption.
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 non-continuous coating design improves blade rub performance, reduces stress, increases erosion resistance, and minimizes leakage while requiring less material, offering enhanced protection and longer coating life compared to continuous and uniform coatings.
Implementation Method 1
thermal spraying an abradable coating composition through the one or more templates to cause the abradable coating composition to deposit on the substrate
Implementation Method 2
A rotating part, for example, a turbine blade, can abrade a portion of a fixed abradable coating applied on an adjacent stationary part
Data Source
AI summary
In some examples, a component includes a substrate and a non-continuous abradable coating on the substrate. The abradable coating includes a first portion defining a first plurality of coating blocks, a second portion defining a second plurality of coating blocks, and a blade rub portion extending between the first portion and the second portion and defining a third plurality of coating blocks. At least one of the first plurality of coating blocks or the second plurality of coating blocks is different than the third plurality of coating blocks in at least one coating block parameter.