Iron-Based Brazing Foil Composition for Cost Reduction
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Solution Overview
Problem
Iron-based brazing alloys with high iron content exhibit increased melting points and undesirable coarse grain formation, leading to reduced mechanical strength and inadequate rheological and wetting characteristics, making it challenging to achieve a perfect brazed joint, especially when trying to reduce nickel content due to rising raw material costs.
Innovation Solution
Developing an iron-based brazing foil with specific compositions such as FeRestNiaCrbSicBdPe or FeRestNiaCrbMofCugSicBdPe, where the sum of Si, B, and P content ranges from 15 to 22 atomic % and Si and P from 2 to 10 atomic %, allowing for ductile, amorphous foils with improved rheological and wetting characteristics, while reducing nickel content and maintaining low raw material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the iron content of the brazing alloy is increased to reduce nickel content and raw material costs, then raw material costs are reduced, but the melting point increases and processing temperature increases leading to coarse grain formation and reduced mechanical strength
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ranges of multiple alloying elements (Fe: 70-90 at.%, Ni: 5-20 at.%, Cr: 5-15 at.%, Si: 2-10 at.%, B: 0.5-5 at.%, P: 0.1-3 at.%) to achieve the desired balance between cost reduction and mechanical strength preservation. This compositional parameter optimization allows the brazing alloy to maintain low melting point while reducing nickel content
Solution Approach 2:
The patent creates a composite brazing alloy system combining multiple elements (Fe-Ni-Cr-Si-B-P) where each element contributes specific properties. The synergistic interaction between these elements produces a composite material that achieves both cost-effectiveness (reduced Ni) and performance (maintained strength and controlled melting point)
2Quantity of substance
If the iron content of the brazing alloy is increased to reduce nickel content, then raw material costs are reduced, but inadequate rheological and wetting characteristics prevent perfect brazed joints
Solution Approach 1:
The patent uses parameter changes by optimizing the content of rheology-modifying elements (Si: 2-10 at.%, B: 0.5-5 at.%, P: 0.1-3 at.%) to improve the flow and wetting characteristics of the brazing alloy. These compositional adjustments ensure proper filler material distribution and adhesion to substrates while maintaining reduced nickel content
Solution Approach 2:
The patent introduces intermediary elements (Si, B, P) that act as mediators to improve the interaction between the brazing alloy and the substrate. These elements enhance wetting characteristics and rheological properties, facilitating reliable brazed joints even with high iron content and reduced nickel
3Quantity of substance
If the processing temperature is increased to accommodate higher iron content, then the brazing alloy can be processed, but coarse grain formation occurs in the parent material reducing its mechanical strength
Solution Approach 1:
The patent applies parameter changes by formulating a low melting point brazing alloy (melting point below 1200°C) through specific compositional ranges. This allows processing at lower temperatures that prevent coarse grain formation in the parent material while still accommodating high iron content (70-90 at.%) in the brazing alloy
Solution Approach 2:
The patent applies local quality by creating a compositional gradient strategy where the brazing alloy has high iron content (70-90 at.%) but is balanced with specific amounts of melting point depressants (Ni: 5-20 at.%, Cr: 5-15 at.%, Si: 2-10 at.%, B: 0.5-5 at.%, P: 0.1-3 at.%). This localized compositional design enables low processing temperature while maintaining high iron content benefits
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 results in brazing foils with excellent rheological and wetting characteristics, enabling the production of reliable, high-quality brazed joints with reduced processing temperatures below 1200°C, suitable for industrial applications like joining stainless steel or nickel alloys, and minimizing coarse grain formation in parent materials.
Implementation Method 1
heating the brazing composite to a temperature above the liquidus temperature of the brazing foil
Implementation Method 2
an increased iron content results in inadequate rheological and wetting characteristics of the brazing alloy
Implementation Method 3
produced as a ductile, at least partially amorphous brazing foils by means of a rapid solidification process
Data Source
AI summary
Disclosed are amorphous, ductile brazing foils with a composition consisting essentially of FeRestNiaCrbSicBdPe, wherein 0 atomic %≦a<25 atomic %; 0 atomic %≦b≦15 atomic %; 1 atomic %≦c≦10 atomic %; 4 atomic %≦d≦15 atomic %; 1 atomic %≦e≦9 atomic %; any impurities≦0.5 atomic %; rest Fe, wherein 2 atomic %≦c+e≦10 atomic % and 15 atomic %≦c+d+e≦22 atomic %, or consisting essentially of FeRestNiaCrbMofCugSicBdPe, wherein 0 atomic %≦a<25 atomic %; 0 atomic %≦b≦15 atomic %; 1 atomic %<c≦10 atomic %; 4 atomic %≦d≦15 atomic %; 1 atomic %≦e≦9 atomic %; 0 atomic %<f≦3 atomic %; 0 atomic %≦g≦3 atomic %; any impurities≦0.5 atomic %; rest Fe, wherein 2 atomic %≦c+e≦10 atomic % and 15 atomic %≦c+d+e≦22 atomic %. Also disclosed are brazed objects formed using these foils, particularly exhaust gas recirculation coolers and oil coolers, and methods for making the brazing foils and for making the brazed parts.