Liquid-Enhanced Laser Stripping of Ceramic Coatings
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Solution Overview
Problem
Ceramic coatings on gas turbine engine components often develop defects such as pores or inter-columnar gaps, necessitating the removal and reapplication of the coating to maintain performance and prevent damage from high thermal loads.
Innovation Solution
A method involving the application of a liquid, such as water or ink, to the ceramic coating, followed by the directed application of laser pulses to spall the coating off the component, utilizing a fiber laser generator with controlled pulse duration and power to avoid damaging the underlying metallic bond coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to remove ceramic coating, then the coating can be removed, but the underlying metallic bond coating is damaged
Solution Approach 1:
The patent utilizes the phase transition of liquid (water or water-based solution) to steam through rapid heating by laser pulses. This phase change generates mechanical stress that spalls the ceramic coating off the component without requiring direct contact or mechanical force that would damage the metallic bond coating underneath.
Solution Approach 2:
The patent replaces conventional mechanical or chemical removal methods with a laser-based thermal field approach. The laser pulses create controlled thermal stress through liquid phase transition, substituting mechanical scraping or chemical etching processes that would compromise the metallic bond coating.
2Productivity
If high power laser pulses are used to remove ceramic coating quickly, then productivity increases, but the metallic bond coating becomes damaged
Solution Approach 1:
The patent introduces a liquid intermediary (water or water-based solution) between the laser and the ceramic coating. The liquid absorbs the laser energy and converts it to phase transition, mediating the energy transfer to spall the coating without allowing excessive heat to reach and damage the metallic bond coating.
Solution Approach 2:
The liquid undergoes rapid phase transition from liquid to steam when exposed to laser pulses, creating mechanical stress that removes the ceramic coating. This phase change mechanism enables high-speed removal while the liquid acts as a heat sink, protecting the underlying metallic bond coating from thermal damage.
3Manufacturing precision
If liquid is applied to enhance laser stripping, then the ceramic coating is effectively removed, but additional process complexity is introduced
Solution Approach 1:
The patent uses a disposable or easily replenishable liquid (water or water-based solution) that is applied to the component surface, used for a single pass or short duration, and then discarded or replenished. This simple, low-cost consumable enables effective coating removal without requiring complex reusable 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
Effectively removes the ceramic coating while preserving the metallic bond coating, allowing for the reapplication of a new coating and improving the component's heat resistance and operational life.
Implementation Method 1
directing a plurality of laser pulses at the ceramic coating with the applied liquid in order to spall the ceramic coating from the component
Implementation Method 2
each of the plurality of laser pulses have a pulse duration that is between 2 nanoseconds and 500 nanoseconds
Implementation Method 3
directing a plurality of laser pulses at the ceramic coating with the applied liquid in order to spall the ceramic coating from the component
Implementation Method 4
the liquid further includes an ink to absorb energy from the plurality of laser pulses
Data Source
AI summary
A method for stripping ceramic from a component includes applying a liquid to a ceramic coating of an outer surface of the component. The method also includes directing a plurality of laser pulses at the ceramic coating with the applied liquid in order to spall the ceramic coating from the component.