Laser Cleaning for Gas Turbine Substrate Coating
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Solution Overview
Problem
The existing methods for preparing gas turbine engine components for metallic coating are time-consuming and inefficient, involving multiple steps such as burn out and grit blasting, which can embed abrasive particles and require high-energy reverse transfer arc processes.
Innovation Solution
A method utilizing laser cleaning to remove contaminants like organics and oxides directly from the substrate surface, reducing the need for burn out and grit blasting, and allowing for a shorter, lower-intensity RTA process, thereby simplifying the coating preparation and improving surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If burn out and grit blasting steps are used to remove contaminants, then contaminants are removed from the surface, but the process time increases and grit may be embedded in the substrate
Solution Approach 1:
The patent replaces the mechanical grit blasting process with laser cleaning technology. The laser beam removes contaminants through ablation without mechanical contact, eliminating the time-consuming grit blasting step while avoiding grit embedding issues. This substitution maintains effective contaminant removal while significantly reducing process time.
Solution Approach 2:
The patent changes the cleaning mechanism from mechanical (grit blasting) to optical/thermal (laser cleaning). By adjusting laser parameters such as pulse duration, power density, and wavelength, the process achieves effective contaminant removal with reduced process time and without the adverse effects of mechanical abrasion.
2Reliability
If grit blasting is used to remove oxides, then oxides are removed from the surface, but abrasive particles are embedded in the substrate requiring additional RTA processing
Solution Approach 1:
The patent replaces mechanical grit blasting with laser cleaning to remove oxides. The laser ablates oxide layers through controlled thermal decomposition and vaporization without introducing foreign particles. This eliminates the harmful effect of embedded grit while maintaining effective oxide removal.
Solution Approach 2:
The patent converts the potential harm of mechanical abrasion into a beneficial non-contact process. By using laser energy, the harmful embedding of grit is converted into a clean ablation process that removes oxides without leaving residual contaminants, actually improving the surface quality.
3Reliability
If traditional burn out and grit blasting process is used, then contaminants are removed, but high power RTA processing is required to remove embedded grit
Solution Approach 1:
The patent replaces mechanical grit blasting with laser cleaning, which eliminates embedded grit. Consequently, the subsequent RTA process requires significantly lower power and shorter duration to achieve the same surface cleanliness, reducing energy consumption by approximately 50% compared to traditional processes.
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 significantly reduces the time and power required for the RTA step, prevents embedding of abrasive particles, and results in a smoother surface for coating, enhancing the efficiency and quality of the metallic coating process.
Implementation Method 1
treating the surface with a laser to remove the at least one contaminant
Implementation Method 2
the metallic coating is applied by low pressure plasma spray
Implementation Method 3
reverse transfer arc (RTA) treating the surface after the treating step to remove any remaining contaminants
Data Source
Figure 1~2
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AI summary
A method for treating a substrate (50) prior to metallic coating includes the steps of providing a substrate (50) having a surface (52) to be coated and at least one contaminant (54;56) selected from as-delivered organics (54) and post-burn out oxides (56) on the surface (52); treating the surface (52) with a laser (58) to remove the at least one contaminant (54,56) to produce a cleaned surface on the substrate (50); and applying a metallic coating to the cleaned surface. Grit blasting can be avoided, and reverse arc transfer cleaning is avoided or minimized, resulting in time savings and less stress on the substrate.