Laser Coating Ablation for Safe Substrate Protection
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Solution Overview
Problem
Current methods for removing surface coatings, such as Diamond-Like Carbon (DLC), Vitrified Contaminant Materials (CMAS), and paints/primers containing Hexavalent Chromium, are either inefficient, generate toxic waste, or damage substrates, lacking an environmentally beneficial solution.
Innovation Solution
A laser-based coating removal system that directs high irradiance laser pulses to elevate surface temperatures, disassociating the coatings from the substrate, converting them into safer forms like vapor-phase carbon dioxide or particulate trivalent chromium, while minimizing heat conduction into the substrate to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional coating removal methods are used, then coatings can be removed, but toxic waste is generated and substrates are damaged
Solution Approach 1:
The patent replaces conventional mechanical or chemical coating removal methods with a laser-based system. The laser delivers controlled radiant energy to the coating, causing thermal decomposition and vaporization of harmful substances like hexavalent chromium, while converting them into less toxic forms. This substitution eliminates mechanical contact and chemical waste generation, protecting substrates from damage while maintaining high removal efficiency.
Solution Approach 2:
The laser system converts harmful substances in the coating (such as hexavalent chromium and toxic organic compounds) into less harmful forms through controlled thermal decomposition. The harmful chemicals are transformed into stable, less toxic compounds or vaporized and captured, turning the harmful coating material into a benefit by eliminating its toxicity while maintaining effective removal.
2Productivity
If high radiant energy is used to remove coatings rapidly, then productivity increases, but heat conduction into the substrate increases causing damage
Solution Approach 1:
The laser system employs pulsed radiant energy delivery rather than continuous exposure. By delivering energy in controlled pulses with specific duration and intervals, the system achieves rapid coating removal during the pulse while allowing heat dissipation between pulses. This periodic action maintains high productivity through rapid sequential processing while preventing excessive heat accumulation in the substrate.
Solution Approach 2:
The system optimizes multiple laser parameters including wavelength, pulse duration, irradiance, and duty cycle to achieve selective heating. By adjusting these parameters, the laser energy is concentrated in the coating layer with minimal penetration into the substrate, enabling rapid coating removal while maintaining substrate temperature within safe limits. The parameter optimization creates a sharp thermal gradient that confines heating to the coating.
3Productivity
If laser wavelength is optimized for surface absorption, then coating removal efficiency improves, but substrate absorption varies requiring active surface recognition
Solution Approach 1:
The system selects and optimizes laser wavelength based on the absorption characteristics of the coating material. By matching the laser wavelength to the coating's absorption peak, maximum energy coupling is achieved, enabling efficient ablation. The wavelength is chosen to create sufficient contrast between coating and substrate absorption, allowing effective removal while minimizing substrate interaction, thereby reducing or eliminating the need for complex active surface recognition 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
The laser-based method efficiently and safely removes environmentally harmful coatings, avoiding the drawbacks of traditional methods by rapidly converting them into less toxic forms that can be collected and disposed of, while protecting the substrate from damage.
Implementation Method 1
directing a laser pulse to a first position on a surface having an identified coating. The laser pulse rapidly elevates the surface temperature at the first position
Implementation Method 2
converting them into safer forms like vapor-phase carbon dioxide or particulate trivalent chromium
Implementation Method 3
the coating to disassociate from the surface... the components of the CMAS are disassociated from the surface by disrupting the chemical bonds
Implementation Method 4
A high absorptivity of the material surface is also valuable, as this reduces the amount of laser energy needed to achieve a desired ablation rate
Implementation Method 5
the heat conduction into the substrate must be minimized... In some embodiments, the heat conduction into the surface from the laser pulse is limited
Data Source
AI summary
A laser-based method of removing a coating from a surface comprises directing a laser pulse to a first position on the surface, removing the coating from the first position by rapidly elevating a surface temperature of the first position using the laser pulse and thereby disassociating the coating from the surface and collecting the disassociated coating. In some embodiments, the coating comprises an environmentally harmful substance such as Hexavalent Chromium. In some embodiments, the coating comprises Diamond-Like Carbon (DLC), Vitrified Contaminant Material (CMAS). The disassociated coating is collected by a waste collector.