Vertically Cracked Thermal Barrier Coatings With Selective Crack Distribution
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Solution Overview
Problem
Existing thermal barrier coatings for gas turbines, such as dense, vertically-cracked (DVT) thermal barrier coatings, are difficult to produce, have undesirable densities, and are prone to spallation, while the current processes do not allow for tailored regions of vertical cracking or welding operations on combustion liners with the coating intact.
Innovation Solution
A method for forming vertically cracked thermal barrier coatings by locally applying heat to a substrate, creating discrete regions of vertical cracks, either through controlled cooling or weld shrinkage, resulting in a low-density coating with selective crack distribution, enabling increased cracking control and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dense, vertically-cracked (DVT) thermal barrier coating is used to improve thermal fatigue resistance, then thermal fatigue resistance is improved, but the coating is difficult to produce and has undesirable density
Solution Approach 1:
The patent applies local quality by creating vertically cracked regions only in specific areas where thermal fatigue resistance is needed, rather than making the entire coating dense. The coating system includes a first region with vertical cracks and a second region with different crack characteristics, allowing each region to have optimized properties for its specific function.
Solution Approach 2:
The patent segments the thermal barrier coating into multiple regions with different crack patterns and densities. The first region has vertically oriented cracks while the second region has cracks with different orientation or density, allowing the system to achieve thermal fatigue resistance in critical areas while maintaining ease of manufacture overall.
2Reliability
If DVT thermal barrier coating is applied to improve thermal fatigue resistance, then thermal fatigue resistance is improved, but the coating is subject to spallation under certain operating conditions
Solution Approach 1:
The patent uses local quality by providing vertical cracks only in the first region where thermal fatigue resistance is critical, while the second region maintains different crack characteristics that preserve coating adhesion and prevent spallation. This localized approach allows the coating to resist thermal fatigue where needed without sacrificing overall adhesion.
3Ease of manufacture
If conventional thermal barrier coating process is used, then coating is formed, but tailored regions of vertical cracking cannot be achieved
Solution Approach 1:
The patent achieves local quality by forming a thermal barrier coating with a first region containing vertically oriented cracks and a second region containing cracks with different orientation or density. This is accomplished through controlled application processes that create distinct crack patterns in different regions, enabling tailored crack distribution for specific performance requirements.
4Reliability
If thermal barrier coating remains on combustion liner inner diameter, then coating protection is maintained, but welding operations on outer diameter cannot be performed
Solution Approach 1:
The patent enables local quality by creating a coating structure where the first region with vertical cracks provides thermal fatigue resistance on the inner diameter, while the second region allows for welding operations on the outer diameter. The selective crack distribution permits welding access without compromising the protective function of the coating in critical areas.
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
This approach reduces production costs, increases process efficiency, decreases spallation, and allows for welding operations on turbine components while maintaining coating durability and survivability, even when one surface is being welded.
Implementation Method 1
Heat is applied locally to at least one discrete portion of the second surface of the substrate. At least one vertical crack in the thermal barrier coating is formed disposed over the at least one discrete portion
Implementation Method 2
At least one discrete portion of the second surface of the substrate is welded, producing weld shrinkage at the at least one discrete portion. At least one vertical crack in the thermal barrier coating disposed over the at least one discrete portion is formed by the weld shrinkage
Data Source
AI summary
A method for forming a vertically cracked thermal barrier coating is disclosed including positioning an article relative to a heat source. The article includes a thermal barrier coating disposed on a first surface of a substrate, and the substrate includes a second surface distal across the substrate from the first surface. Heat is applied locally to at least one discrete portion of the second surface of the substrate. At least one vertical crack in the thermal barrier coating is formed disposed over the at least one discrete portion. An article is disclosed including a substrate and a vertically-cracked thermal barrier coating disposed on the substrate. The vertically cracked thermal barrier coating includes at least one vertical crack in the thermal barrier coating and at least one of a low density of less than 85% of a theoretical density for the thermal barrier coating and a selective crack distribution.