Thermal Barrier Coating with Segmented Rounded Edges
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Solution Overview
Problem
Conventional thermal barrier coatings (TBCs) used in gas turbine engines face challenges such as spallation due to thermo-mechanical fatigue, especially in severe service environments, which reduces their durability and increases maintenance costs.
Innovation Solution
A thermal barrier coating system is developed with a dense YSZ coating, a bond coat, and a thermally insulating topcoat, featuring geometrically segmented surface features with rounded edges and a column structure. This configuration reduces stress concentrations and allows for stress relief through expansion joints and segmentation cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional thermal barrier coating is used to protect gas turbine components from high temperatures, then the component can operate at elevated temperatures, but the coating is vulnerable to cracking and spallation due to thermo-mechanical fatigue
Solution Approach 1:
The coating is divided into geometrically segmented regions with rounded edges and column structures, creating discrete zones that can independently accommodate thermal expansion and stress, preventing continuous crack propagation across the entire coating surface
Solution Approach 2:
Different regions of the coating are given different geometric properties - some areas have rounded edges to reduce stress concentration, while column structures provide pathways for stress relief, creating localized zones with optimized stress distribution characteristics
2Loss of energy
If the coating is made thicker to improve insulation, then the insulating factor increases, but the stress concentrations increase leading to higher risk of spallation
Solution Approach 1:
Rounded edges are incorporated into the geometric segmentation pattern, eliminating sharp corners that would act as stress concentration points, thereby allowing thicker coating applications without proportionally increasing spallation risk
Solution Approach 2:
The segmented geometry creates discrete regions that can expand and contract independently, distributing thermal stresses more evenly throughout the thicker coating structure and preventing the development of critical stress concentrations
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 proposed coating system significantly enhances the durability and spallation resistance of TBCs, reducing the risk of thermo-mechanical fatigue and maintaining efficient engine operation despite high temperatures and mechanical stresses.
Implementation Method 1
a thermally insulating topcoat configured to reduce stress concentrations in the dense ceramic layer
Implementation Method 2
feature a metallic column structure with rounded edges configured to reduce stress concentrations in the dense ceramic layer
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A thermal barrier coating disposed on a substrate (50) comprising a plurality of surface features (52) formed on the substrate (50) proximate an inner side (48) of the substrate (50), each of the plurality of surface features (52) comprising a metallic column having a top (68) with rounded edges (86); a dense layer (88) disposed in a valley (66) located between each of the plurality of surface features (52), and the dense layer (88) disposed on the top (68) and covering the rounded edges (86); a thermally insulating topcoat (54) disposed over the plurality of surface features (52).