Laser Cleaning of Diffusion-Coated Turbine Components
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Solution Overview
Problem
Current methods for removing diffusion aluminide coatings from gas turbine engine components often result in substrate alloy depletion and altered airflow characteristics, leading to component scrapping, as they involve complete removal of the coating, including the diffusion zone, using harsh chemicals and mechanical processes.
Innovation Solution
A method using laser beam pulses to selectively remove contaminants and optionally parts of the additive layer from the diffusion coating without damaging the underlying diffusion zone, allowing for rejuvenation and recoating with an aluminide coating that matches the original chemistry and microstructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If complete removal of diffusion coating is performed using harsh chemicals and mechanical processes, then the coating is fully removed, but substrate alloy depletion and altered airflow characteristics occur leading to component scrapping
Solution Approach 1:
The patent replaces mechanical and chemical removal processes with laser beam technology. The laser beam selectively removes contaminants and oxide layers from the diffusion coating without requiring harsh chemicals or mechanical abrasion, thereby preserving the substrate integrity while achieving coating removal.
Solution Approach 2:
The laser beam process applies localized energy to specific areas of the coating, allowing selective removal of contaminants and oxide layers only where needed. This localized approach prevents widespread substrate damage and maintains the integrity of the underlying diffusion zone.
2Ease of manufacture
If complete removal of diffusion coating is performed, then the coating is fully stripped, but labor and cost increase
Solution Approach 1:
The laser beam process eliminates the need for multiple mechanical blasting steps and chemical treatments, consolidating the removal process into a single efficient operation that reduces labor time and associated costs.
Solution Approach 2:
The laser beam process removes only the necessary portions of the coating (contaminants and oxide layers) rather than completely stripping the entire diffusion coating. This partial removal approach achieves the repair objective while preserving valuable substrate and coating material.
3Ease of manufacture
If harsh chemicals are used for acid stripping, then the additive layer is removed, but special facilities and safety requirements are needed
Solution Approach 1:
The laser beam process replaces chemical acid stripping with a physical energy-based process. This substitution eliminates the need for special chemical handling facilities, storage requirements, and safety infrastructure associated with harsh chemicals.
Solution Approach 2:
The laser beam process uses energy that does not require complex facility infrastructure. The laser system itself is portable and can be brought to the component, eliminating the need for fixed chemical stripping facilities with special ventilation, containment, and waste treatment systems.
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 labor and cost, maintains dimensional and airflow requirements, and preserves the substrate integrity, improving repair yields and avoiding the need for full-stripping repairs with acids.
Implementation Method 1
subjecting the surface of the component containing contaminants to laser beam pulses to remove contaminants from the component
Data Source
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AI summary
A method (300) of removing contaminants (12) from a surface of a gas turbine engine component (10) protected by a diffusion coating (20) that comprises an additive layer (50) on the surface of the component (10) and a diffusion zone (60) in the surface of the component (10). The method (300) includes subjecting the surface containing contaminants (12) to laser beam pulses to remove contaminants (12) from the component (10) such that contaminants (12) on the surface of the component (10) are removed without damaging or removing the diffusion zone (60) of the diffusion coating (20). Methods for controlled removal of at least a portion (52) of a thickness (22) of a diffusion coating (20) from a coated superalloy component (10) are also provided.