PSP Cladding for Gas Turbine Microcrack Sealing
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Solution Overview
Problem
Gas turbine components with thin surface layers, particularly those made from hard-to-weld alloys or formed by additive manufacturing, are susceptible to microcrack formation, leading to cooling fluid leakage and potential failure due to their susceptibility to microcracks.
Innovation Solution
A clad article with a cladding layer formed from a pre-sintered preform (PSP) is applied over the microcracks to seal them, using a combination of alloys with distinct melting points and potentially including ceramic additives, which is brazed onto the surface to enhance mechanical properties and prevent fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the surface layer is made thin to minimize distance between cooling channels and surface, then cooling efficiency is improved, but susceptibility to microcrack formation increases
Solution Approach 1:
The patent applies a cladding layer composed of multiple alloys with different melting points (e.g., nickel-based superalloy, cobalt-based superalloy, iron-based superalloy) to create a composite surface layer. This composite structure provides both the thermal performance needed for efficient cooling and the mechanical integrity to resist microcrack formation, resolving the contradiction between thin surface layer requirements and microcrack susceptibility.
2Strength
If hard-to-weld alloys are used for the surface layer, then mechanical properties are improved, but susceptibility to microcrack formation increases
Solution Approach 1:
The cladding layer uses a composite structure of multiple alloys with distinct melting points, where each alloy contributes different mechanical properties. This composite approach maintains the high strength and temperature resistance of hard-to-weld alloys while reducing microcrack susceptibility through the synergistic combination of materials with complementary properties.
Solution Approach 2:
The patent applies different alloy compositions at different locations or layers of the cladding, with each alloy selected for its specific properties. This local differentiation allows the surface layer to have optimized mechanical properties in specific regions while maintaining overall resistance to microcrack formation.
3Ease of manufacture
If additive manufacturing techniques are used to form the surface layer, then manufacturing flexibility is improved, but susceptibility to microcrack formation increases
Solution Approach 1:
The cladding layer formed by additive manufacturing uses composite material structures with multiple alloys of different melting points. This composite approach compensates for the microcrack susceptibility inherent in additive manufacturing by creating a multi-phase material structure that enhances crack resistance while maintaining the manufacturing flexibility and design freedom of additive 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
The solution effectively seals microcracks, reducing cooling fluid leakage by at least 90% and improving the mechanical properties and durability of the gas turbine components, thereby enhancing their performance and efficiency.
Implementation Method 1
The PSP cladding layer is formed from a pre-sintered preform (PSP) brazed onto an article
Implementation Method 2
utilizing a combination of alloys with distinct melting points
Data Source
Figure 1~2
AI summary
A clad article (200) is disclosed including an article (100) and a cladding layer (202). The article (100) includes a surface layer (102), at least one cavity (104) disposed within the article (100) below the surface layer (102), and at least one microcrack (106) disposed in the surface layer (102). The surface layer (102) includes an HTW alloy (108). The cladding layer (202) is disposed on a surface (110) of the surface layer (102), and is formed from a PSP (204) brazed to the article (100). The cladding layer (202) is disposed over the at least one microcrack (106). A method for forming the clad article (200) is disclosed including disposing the PSP (204) on the article (100) and brazing the PSP (204) to the article (100). Brazing the PSP (204) to the article (100) forms the cladding layer (202) disposed on the article (100) over the at least one microcrack (106).