Braze Interlock Joining for Complex Turbine Vane Assemblies
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Solution Overview
Problem
Casting large or complex metal or alloy components, such as nozzle guide vanes for gas turbine engines, often results in high rejection rates due to defects and limitations in design complexity, as traditional methods require complex and costly processes like bi-casting that can lead to integrity issues and high leakage.
Innovation Solution
A technique involving the use of a braze material that forms a mechanical interlock between components without metallurgical bonding, utilizing an adhesion-resistant material to prevent adherence and employing pre-sintered preform braze alloys that can be heated to form a softened state conforming to the joint region, then cooled to secure the components with reduced porosity and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional casting methods are used to form large or complex metal components, then design complexity and component size are limited, but manufacturing precision and defect rates deteriorate due to casting defects and tolerance deviations
Solution Approach 1:
The invention divides a complex component into multiple separate components that are joined together using mechanical interlocks and adhesion-resistant materials. This segmentation allows each component to be manufactured with higher precision using conventional methods while achieving complex overall geometries through assembly, thereby resolving the contradiction between design complexity and manufacturing precision.
2Reliability
If single crystal casting is used to form nozzle guide vanes, then component integrity is improved, but design complexity is restricted and rejection rates increase
Solution Approach 1:
The nozzle guide vane is divided into multiple components joined by mechanical interlocks with adhesion-resistant materials, replacing the single crystal casting approach. This segmentation maintains component integrity through precise mechanical joining while enabling complex geometries that cannot be achieved with single crystal casting, thus resolving the contradiction between reliability and design complexity.
3Adaptability or versatility
If bi-casting process is used to form complex articles, then design complexity is improved, but process complexity and leakage issues increase
Solution Approach 1:
The invention uses separate components joined by mechanical interlocks and adhesion-resistant materials instead of bi-casting. This approach achieves complex designs through modular assembly rather than complex integrated casting processes, reducing process complexity and eliminating leakage issues associated with bi-casting while maintaining design versatility.
4Strength
If components are joined with metallurgical bonding, then structural strength is improved, but adhesion to joint surfaces increases causing defects
Solution Approach 1:
The invention introduces an adhesion-resistant material as an intermediary between the braze material and joint surfaces. This intermediary prevents direct metallurgical bonding and adhesion to joint surfaces, eliminating defects while maintaining structural strength through the mechanical interlock formed by the softened braze material. This resolves the contradiction between structural strength and joint defect rate.
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 method reduces defect rates, allows for more complex geometries, and provides a low-leakage structural connection suitable for high-temperature environments, while maintaining component integrity and reducing manufacturing costs by enabling batch processing of multiple components.
Implementation Method 1
An adhesion resistant material present between the braze material and the joint surface. The adhesion resistant material is configured to resist adherence of the braze material to the joint surface.
Implementation Method 2
heating the braze material to a processing temperature to form an at least softened material in the joint region
Implementation Method 3
cooling the at least softened material to form a mechanical interlock including the braze material in the joint region joining the first and second components
Data Source
AI summary
The disclosure describes example techniques and assemblies for joining a first component and a second component. The techniques may include positioning the first and second component adjacent to each other to define a joint region between adjacent portions of the first component and the second component, the joint region being coated with an adhesion resistant coating. The techniques may also include positioning a braze material in the joint region, heating the braze material to form an at least softened material, and cooling the at least softened material to form a mechanical interlock including the braze material in the joint region joining the first and second components. The braze material does not metallurgically bond to the joint surface.