Amorphous Brazing Foil Ring for Induction Joining of Brittle Alloys
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Solution Overview
Problem
Existing brazing methods, particularly selective heating processes like induction brazing, struggle to effectively join metalloid-containing and chromium-containing alloys due to their brittleness and poor formability, leading to unreliable braze joints and inefficient heating processes.
Innovation Solution
The use of an amorphous or partially amorphous brazing foil in the form of a wound ring band with a short-circuited current path allows for efficient induction brazing by generating eddy currents, enabling quick and reliable heating of high-temperature solders with metalloid contents up to 30 atomic percent, which are otherwise difficult to process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metalloid-containing brazing alloys (Si, B, P > 10 at.%) are used to lower melting point and improve corrosion resistance, then the brazing alloy achieves lower liquidus temperature and higher corrosion resistance, but the alloy becomes brittle and difficult to form in crystalline state
Solution Approach 1:
The patent changes the physical state parameter of the brazing alloy from crystalline to amorphous by controlling the cooling rate during solidification. This parameter change allows the alloy to maintain low liquidus temperature (achieved through metalloid content) while eliminating brittleness and improving formability, as the amorphous structure lacks the grain boundaries and intermetallic phases that cause brittleness in crystalline alloys
Solution Approach 2:
The patent creates a composite structure with an amorphous metalloid-containing alloy layer (5-30 at.% Si, B, and/or P) combined with a ductile metal matrix (Ni, Co, or Cu base). This composite approach allows the metalloid layer to provide low melting point and corrosion resistance while the metal matrix provides ductility and formability, resolving the contradiction between brittleness and desired chemical properties
2Productivity
If selective heating process (induction brazing) is used to locally heat the joint, then the heating efficiency is improved and process time is reduced, but reliable brazing cannot be achieved with metalloid-containing alloys due to their poor formability and brittleness
Solution Approach 1:
The patent changes the physical state parameter of the brazing alloy from crystalline to amorphous by controlling the cooling rate during solidification. This parameter change allows the alloy to maintain low liquidus temperature (achieved through metalloid content) while eliminating brittleness and improving formability, as the amorphous structure lacks the grain boundaries and intermetallic phases that cause brittleness in crystalline alloys
Solution Approach 2:
The patent applies the brazing alloy to the joint in an amorphous state before induction heating, where it can be easily formed and positioned due to its ductility. The preliminary formation of the amorphous alloy layer ensures proper placement and contact with the joint, and subsequent induction heating then reliably melts and bonds the alloy without the reliability issues that would arise from trying to heat and form brittle crystalline alloys simultaneously
3Reliability
If chromium is added to enhance corrosion resistance of nickel-, cobalt-, and iron-based brazing alloys, then corrosion resistance is improved, but the alloy becomes more difficult to process and form
Solution Approach 1:
The patent changes the physical state parameter of the brazing alloy from crystalline to amorphous by controlling the cooling rate during solidification. This parameter change allows the alloy to maintain low liquidus temperature (achieved through metalloid content) while eliminating brittleness and improving formability, as the amorphous structure lacks the grain boundaries and intermetallic phases that cause brittleness in crystalline alloys
Solution Approach 2:
The patent creates a composite structure with an amorphous metalloid-containing alloy layer (5-30 at.% Si, B, and/or P) combined with a ductile metal matrix (Ni, Co, or Cu base). This composite approach allows the metalloid layer to provide low melting point and corrosion resistance while the metal matrix provides ductility and formability, resolving the contradiction between brittleness and desired chemical properties
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 enables the production of reliable, high-temperature brazed joints with improved corrosion resistance, reducing process time and energy requirements, and is suitable for complex or large components that cannot be easily heated uniformly.
Implementation Method 1
The brazing alloy in the form of a foil with a short-circuited current path between two adjacent layers is inductively heated
Implementation Method 2
This short-circuited current path allows the eddy currents necessary for induction brazing processes to be generated in the ring
Implementation Method 3
The alloy melts, wets these components, and fills capillary gaps
Implementation Method 4
The alloy melts, wets these components, and fills capillary gaps
Implementation Method 5
This bond is based on the diffusion of atoms from the alloy and the base material to each other
Data Source
Figure 1a~2b
AI summary
Disclosed is a hard soldering method wherein an amorphous or partially amorphous hard soldering film having a composition that has a metalloid content of 10 to 30 atomic percent is disposed at a joining point between two or more parts. The hard soldering film has the shape of a wound circular strip that has a short-circuited current path between at least two layers lying on top of one another. The hard soldering film is inductively heated and melted, and a hard soldered joint is created between the parts.