Segmented Thermal Insulating Coating for Gas Turbine Blades
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Solution Overview
Problem
Conventional protective coatings for gas turbine components, such as turbine blade outer air seals, are vulnerable to erosion and spalling due to internal stresses caused by high temperatures, leading to reduced durability and efficiency over time.
Innovation Solution
A turbine article with a metal alloy substrate and geometric surface features, coated with a thermally insulating topcoat having segmented portions separated by faults that dissipate internal stresses, reducing the risk of delamination and spalling through controlled deposition processes like thermal spraying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a continuous thermally insulating topcoat is applied to protect the substrate, then thermal insulation performance is improved, but internal stresses cause delamination and spalling over time
Solution Approach 1:
The continuous topcoat is divided into segmented portions separated by faults or gaps. This segmentation allows the topcoat to accommodate thermal expansion and contraction without building up excessive internal stresses, thereby preventing delamination and spalling while maintaining thermal insulation performance.
Solution Approach 2:
The topcoat incorporates faults or gaps that create a porous structure. These voids allow for stress relief during thermal cycling and provide pathways for stress dissipation, enhancing the coating's reliability under high temperature conditions while preserving its insulating properties.
2Temperature
If the topcoat is made thicker to improve thermal insulation, then temperature protection is enhanced, but internal stresses increase leading to greater vulnerability to erosion and spalling
Solution Approach 1:
By segmenting the thick topcoat into portions separated by faults, the coating can achieve greater thickness for improved thermal protection without proportionally increasing internal stresses. The segmentation creates stress relief zones that prevent the buildup of critical stress levels even in thicker coatings.
Solution Approach 2:
The faults are pre-formed or formed during the coating application process before the coating is fully cured. This preliminary action creates stress relief pathways in advance, allowing the coating to withstand thermal cycling and mechanical stresses without developing critical stress concentrations that would lead to spalling.
3Ease of manufacture
If a conventional continuous coating is used, then manufacturing simplicity is maintained, but the coating requires replacement or refurbishment after a period of use
Solution Approach 1:
The segmented coating structure can be applied using conventional thermal spray processes with minimal modification to existing manufacturing equipment. The segmentation is achieved through controlled deposition patterns or by forming sacrificial spacers during application, maintaining ease of manufacture while dramatically extending service life through improved stress management.
Solution Approach 2:
The fault pattern is incorporated during the initial coating application process rather than requiring subsequent modification. This preliminary incorporation of stress relief features ensures long-term durability without adding complex post-processing steps, maintaining manufacturing simplicity while extending the coating's operational lifespan.
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 solution effectively reduces internal stresses in the thermally insulating topcoat, enhancing its resistance to spalling and delamination, thereby extending the lifespan and maintaining the efficiency of gas turbine components.
Implementation Method 1
a thermally insulating topcoat having segmented portions separated by faults extending through the topcoat to reduce internal stresses within the topcoat
Implementation Method 2
controlled deposition processes like thermal spraying
Data Source
Figure 1
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AI summary
A gas turbine article includes a substrate, a plurality of geometric surface features that protrude from the substrate, and a thermally insulating topcoat disposed over the plurality of geometric surface features. The thermally insulating topcoat includes segmented portions that are separated by faults that extend through the topcoat from the geometric surface features.