Braze Material with Surface-Embedded Melt Modifiers
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Solution Overview
Problem
Brazing of certain superalloys is hindered by the tendency of melting point depressants to form embrittling phases, leading to segregation issues and detrimental effects on mechanical properties, and existing microwave brazing techniques face challenges in localized heating and heat loss.
Innovation Solution
A braze material comprising particles with melt-modifying constituents, such as melting point depressants and microwave coupling enhancers, are embedded in the outer surface region of the particles, allowing for controlled melting and improved heating rates through conventional or microwave radiation, while maintaining the mechanical properties of the brazement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If melting point depressants are added to braze alloy to enable brazing of superalloys, then brazing becomes possible, but embrittling phases form and mechanical properties deteriorate
Solution Approach 1:
The braze alloy is segmented into multiple powder sizes: coarse powder containing the base superalloy composition and fine powder containing the melting point depressants. This segmentation prevents the fine depressant particles from segregating to the brazement surface while still enabling them to form eutectics and facilitate brazing, thus avoiding embrittling phase formation and maintaining mechanical properties.
Solution Approach 2:
The invention applies local quality by concentrating melting point depressants in the fine powder fraction that remains distributed within the brazement structure, while the coarse powder provides the bulk mechanical properties. This localized distribution ensures depressants are present where needed for brazing without overwhelming the overall structure with embrittling phases.
2Strength
If two powders with different compositions are used to control melting point depressant distribution, then mechanical properties are maintained, but powder segregation occurs during brazing
Solution Approach 1:
The braze material is segmented into coarse and fine powder fractions with different compositions. The fine powder containing melting point depressants is designed to remain dispersed within the brazement structure due to its size, preventing segregation while maintaining composition control and mechanical properties.
3Productivity
If microwave coupling enhancers are added to braze powder to improve microwave heating, then heating rate increases, but excessive enhancers cause property losses
Solution Approach 1:
Microwave coupling enhancers are concentrated in the fine powder fraction rather than being uniformly distributed. This local concentration provides sufficient microwave absorption to enable rapid heating and melting of the braze material, while the overall low volume of enhancers prevents detrimental effects on brazement mechanical properties.
4Ease of manufacture
If conventional brazing is used to join superalloy components, then manufacturing is achieved, but heat loss and lack of localized heating occur
Solution Approach 1:
The invention replaces conventional thermal conduction-based heating with microwave electromagnetic field heating. The fine powder fraction containing microwave coupling enhancers absorbs microwave energy efficiently, enabling rapid and localized heating of the braze material without significant heat loss to the surrounding superalloy components.
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 enhances the mechanical properties of brazements, promotes broader use of brazing processes, and improves heating efficiency, particularly in gas turbine engine components, by ensuring localized melting and reduced segregation of melt-modifying constituents.
Implementation Method 1
heating a braze material, typically in the form of a braze alloy powder... to a temperature above the melting point of the braze alloy
Implementation Method 2
a second approach entails direct microwave heating of a braze alloy powder, which is more susceptible to absorbing microwave energy than bulk metals
Implementation Method 3
the braze alloy will typically have a composition essentially or nearly the same as the substrate, but modified to contain one or more melting point suppressants, such as boron and/or silicon, which form low melting eutectics with the substrate material
Implementation Method 4
melting point suppressants, such as boron and/or silicon, which form low melting eutectics with the substrate material
Data Source
AI summary
A braze material and processes for making and using the material, such as for use in the manufacturing, coating, repair, and build-up of superalloy components. The braze material is composed of particles with melt-modifying constituents that are limited to the surfaces of the particles, yet are capable of sufficiently promoting the heating of the particles by conventional means and microwave radiation to achieve at least partial melting of the particles. The melt-modifying constituents are in the form of particulates embedded in the outer surface region of each particle. The particulates are formed of melting point depressant(s) and/or microwave coupling enhancer(s), are much smaller than the particle in which they are embedded.