Repairing Ceramic Composite Articles via Laser-Assisted CVD
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Solution Overview
Problem
Ceramic composite articles used in turbine applications experience environmental degradation leading to erosion of the surface barrier, which can chip off prematurely due to mechanical impacts or stress fields, exposing the substrate and reducing the component's lifespan.
Innovation Solution
A method of repairing ceramic composite articles by cleaning the repair area using grinding, oxidants, halogens, or ultraviolet lasers, followed by depositing ceramic material, such as silicon carbide or boron carbide, using laser-assisted chemical vapor deposition to restore the matrix material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the barrier is applied on the surface to protect ceramic composite articles, then the articles are protected from environmental degradation, but the barrier may prematurely chip off due to micro-impacts or local stress fields, exposing the substrate
Solution Approach 1:
The patent applies a preliminary cleaning action to the repair area before deposition to remove contaminants, oxides, and carbonization that would interfere with bonding. This preliminary preparation ensures that the subsequently deposited barrier material achieves strong adhesion and integrates properly with the substrate, preventing premature chipping and improving long-term barrier integrity.
Solution Approach 2:
The patent employs laser heating to locally raise the temperature of the repair area to approximately 1000°F (538°C) or higher. This temperature parameter change enables the ceramic material to be deposited in a molten state, allowing it to flow and bond effectively with the substrate while maintaining barrier integrity and preventing premature failure.
2Duration of action of stationary object
If the substrate is exposed due to barrier erosion, then the component life is limited, but replacing the entire component is more costly and time-consuming than repair
Solution Approach 1:
The patent applies local quality by cleaning and depositing ceramic material only in the specific repair area where the barrier has eroded, rather than treating the entire component. The laser heating and deposition are confined to the exposed substrate regions, making the repair process efficient and cost-effective while extending component life without requiring complete replacement.
Solution Approach 2:
The patent replaces traditional mechanical repair methods with laser-assisted chemical vapor deposition. Instead of mechanical bonding or filler materials, the laser heating enables direct deposition of ceramic material that chemically bonds with the substrate, creating a robust repair that extends component life efficiently.
3Ease of manufacture
If conventional cleaning methods are used, then the repair area is prepared, but the deposited material may have high porosity and poor adhesion
Solution Approach 1:
The patent replaces conventional mechanical cleaning methods with laser heating to prepare the repair area. This thermal cleaning method removes contaminants, oxides, and carbonization more effectively than mechanical means, creating a superior surface for deposition that ensures low porosity and strong adhesion of the ceramic material.
Solution Approach 2:
The patent uses laser heating to raise the repair area temperature to approximately 1000°F (538°C) or higher, which fundamentally changes the surface properties of the substrate. This temperature parameter change enables better wetting and bonding of the deposited ceramic material, ensuring low porosity and high adhesion strength.
4Strength
If the repair area is cleaned by removing contaminants, then adhesion is improved, but the cleaning process must be precise to avoid damaging the surrounding barrier
Solution Approach 1:
The patent applies local quality by using laser heating that can be precisely focused only on the repair area, leaving the surrounding barrier intact. The laser beam can be controlled to heat specifically the exposed substrate regions to approximately 1000°F (538°C) or higher without affecting the intact barrier, enabling precise cleaning and preparation.
Solution Approach 2:
The patent replaces mechanical cleaning methods with laser heating, which offers superior spatial precision. The laser can be directed exactly at the repair area boundaries, providing controlled thermal cleaning that improves adhesion while protecting the surrounding barrier from damage, achieving both strong bonding and high cleaning accuracy.
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 method effectively repairs ceramic composite articles by replacing eroded areas with ceramic materials that match the composite's matrix, enhancing the component's robustness and extending its lifespan by reducing heterogeneity and preventing further erosion.
Implementation Method 1
cleaning the repair area includes contacting the repair area with energy from an ultraviolet laser
Implementation Method 2
cleaning the repair area includes contacting the repair area with an oxidant, halogen, energy from an ultraviolet laser
Implementation Method 3
the laser locally heating the surface to convert the gas precursor to the ceramic material
Implementation Method 4
laser assisted chemical vapor deposition uses a gas nozzle that is co-linear with the laser
Implementation Method 5
depositing a ceramic material in the cleaned repair area using laser assisted chemical vapor deposition
Implementation Method 6
convert the gas precursor to the ceramic material
Data Source
AI summary
A method of repairing an article including cleaning a repair area, wherein the repair area comprises a ceramic matrix composite; and depositing a ceramic material in the cleaned repair area using laser assisted chemical vapor deposition. Also disclosed is a repaired ceramic composite produced by this method.