Plasma Etching Repair of Gas Turbine Elastomeric Coatings
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Solution Overview
Problem
Existing methods for repairing eroded elastomeric coatings on gas turbine engine blades, such as those used in commercial aircraft, often leave debris on the repair surface, compromising the adhesion and durability of the new coating, and require time-consuming processes like grit-blasting.
Innovation Solution
A plasma etching process is used to remove the eroded region of the elastomeric coating, creating a new bonding surface, followed by applying an elastomeric repair coating with an interfacial tensile strength of over 1500 psi, using plasma etching in air or argon environments for 5 to 60 minutes, ensuring debris removal and surface activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional grit-blasting methods are used to prepare the surface for repair coating, then the eroded region can be removed, but debris is left on the repair surface compromising adhesion
Solution Approach 1:
The patent replaces the mechanical grit-blasting system with a plasma-based system. Instead of using abrasive particles mechanically impacting the surface, the invention uses plasma etching with controlled chemical reactions and ion bombardment to remove eroded material and prepare the surface, thereby eliminating debris contamination while maintaining ease of repair
Solution Approach 2:
The patent changes the fundamental parameters of the surface preparation process by transitioning from mechanical energy (grit-blasting) to plasma energy (ionization, excitation). By controlling plasma parameters such as gas composition, power input, and exposure time, the process achieves clean surface preparation without leaving debris, thus improving adhesion reliability
2Reliability
If plasma etching is used to remove the eroded region, then a clean bonding surface is created without debris, but the process time increases to 5-60 minutes
Solution Approach 1:
The patent applies partial action by etching only the eroded region rather than the entire coating surface. The plasma process is targeted and controlled to remove material only where needed, achieving sufficient surface preparation for adhesion without unnecessary extended processing time on intact areas
Solution Approach 2:
The patent optimizes plasma process parameters (power level, gas flow rate, pressure, exposure time) to achieve the desired surface preparation within a reasonable time frame. By adjusting these parameters, the process balances thoroughness of cleaning with efficiency, reducing excessive processing time while maintaining adhesion quality
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 plasma etching method provides a strong bond between the repair coating and the underlying coating, enhancing adhesion and durability without leaving debris, and achieving interfacial strengths up to 3400 psi, thus extending the life of the blades.
Implementation Method 1
plasma etching the elastomeric coating in the eroded region
Implementation Method 2
plasma etching in air or argon environments for 5 to 60 minutes, ensuring debris removal and surface activation
Data Source
Figure 1~2
Figure 3(a)~3(c)
AI summary
A repair process includes providing a gas turbine engine article (23) that has an elastomeric coating (66) that has an eroded region (72), plasma etching the elastomeric coating (66) in the eroded region (72), and applying an elastomeric repair coating (74) on the eroded region (72).