Turbine Blade Tip Abrasive Coating Repair Without Deep Machining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tip repair methods for gas turbine engine blades, such as preform and in situ weld build-ups, face challenges like economy of scale issues, material stress, limited repeatability, and the potential for causing further damage during the repair process, particularly due to deep machining and welding.
Innovation Solution
A method involving progressive nickel-based layer plating and machining to fill cracks and oxidation, with a nickel-based base layer and abrasive layer applied to the blade tip, allowing for precise restoration of the substrate and reducing the need for extensive material removal, while maintaining the blade's structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preform repair technique is used, then blade tip can be replaced, but substantial material removal is required which penetrates into internal passageways
Solution Approach 1:
The damaged abrasive coating and oxidized material are selectively removed only from the tip surface through controlled machining, while preserving the internal passageway trunks and substrate integrity. This extracts only the necessary damaged portions without substantial material loss.
Solution Approach 2:
The repair process applies localized treatment only to the damaged tip region rather than requiring complete tip replacement. The nickel-based alloy restoration is applied locally to the machined surface, preserving the original blade structure and internal passageways.
2Ease of repair
If in situ weld build-up repair is used, then material stress is introduced, but repair can be performed without preform replacement
Solution Approach 1:
The welding process is replaced with a mechanical deposition process where nickel-based alloy powder is deposited onto the machined tip surface and then heat-treated. This substitution eliminates the high-stress welding process while achieving similar restorative results through controlled material deposition and diffusion bonding.
3Reliability
If deep machining is performed to remove damaged material, then cracks and oxidation can be removed, but further substrate damage may occur
Solution Approach 1:
The machining process is controlled to remove only the necessary amount of damaged material (abrasive coating and oxidized layer) without excessive depth that would damage the substrate. The machining stops at the substrate surface or slightly below, preserving the internal passageway trunks while effectively removing all harmful damaged material.
4Reliability
If conventional repair methods are used, then blade can be restored, but economy of scale issues arise
Solution Approach 1:
The repair process uses controlled heat treatment parameters (temperature, time, atmosphere) to achieve diffusion bonding of the deposited nickel-based alloy to the substrate. By optimizing these thermal parameters, the process achieves reliable restoration while improving efficiency and consistency across multiple blades, addressing economy of scale requirements.
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 enables effective repair of damaged turbine blade tips by progressively filling cracks and oxidation, improving the blade's durability and reducing the stress on the substrate, thereby enhancing the blade's performance and extending its service life without the limitations of previous repair techniques.
Implementation Method 1
The exemplary base layer comprises a nickel alloy (e.g., nickel-chromium-aluminum alloy) electroplate applied to a nominal base layer thickness
Implementation Method 2
After base layer application, the abrasive and matrix may be applied (e.g., via electroplating) to a desired abrasive layer thickness
Implementation Method 3
Eventually, due to diffusion with the nickel alloy, the very thin nickel flash layer will cease to be distinct
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A method for repairing a blade (20)wherein the blade comprises a metallic substrate (22) shaped to define an airfoil having a tip. A coating (34) is on the tip. The method comprises: machining to at least partially remove the coating (34); plating a nickel-based base layer (32'); and plating an abrasive layer (34') comprising a nickel-based matrix (36) and an abrasive (38).