Nickel Brazing Filler Composition for Low-Temperature Stainless Steel Joining
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Solution Overview
Problem
Current nickel brazing filler metals for stainless steel heat exchangers face challenges in achieving low melting temperatures while maintaining sufficient corrosion resistance and wettability, as existing solutions either have poor corrosion resistance or insufficient wettability when the brazing temperature is lowered.
Innovation Solution
A nickel brazing filler metal with a composition of 8.0 to 19.0 mass % Cr, 7.0 to 10.5 mass % P, 0.1 to 1.5 mass % B, 2.0 to 8.0 mass % Cu, and Mo 10.0 mass % or less, along with optional Co, Fe, and Mn, to achieve a melting temperature of 1000° C. or less, excellent corrosion resistance, and a wettability spreading coefficient of 10 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the melting temperature of nickel brazing filler metal is lowered to reduce energy costs, then energy efficiency improves, but wettability becomes insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the nickel brazing filler metal by adding specific ranges of Al (0.1-1.0 mass%), Ti (0.1-1.0 mass%), and V (0.1-1.0 mass%) elements, along with controlling Cr (3.0-15.0 mass%) and other alloying elements. These compositional parameter changes enable the material to achieve both low melting temperature (900-1050°C) and sufficient wettability simultaneously, resolving the contradiction between energy efficiency and bonding reliability.
2Use of energy by moving object
If the melting temperature of nickel brazing filler metal is lowered, then energy costs decrease, but corrosion resistance becomes insufficient
Solution Approach 1:
The patent creates a composite alloy system combining nickel as the base metal with multiple alloying elements (Al, Ti, V, Cr, Mn, Mo, Si, B, P) in specific proportions. This composite composition achieves a eutectic melting point range of 900-1050°C while maintaining excellent corrosion resistance through the synergistic effects of Cr forming protective oxides and other elements enhancing structural stability, thus resolving the contradiction between low energy cost and corrosion resistance.
3Reliability
If conventional nickel brazing filler metals (BNi2, BNi5, Ni-Cr-P-Si) are used to ensure corrosion resistance, then corrosion protection is adequate, but melting temperature remains above 1000°C
Solution Approach 1:
The patent fundamentally changes the compositional parameters by introducing Al, Ti, and V elements in controlled amounts (0.1-1.0 mass% each) alongside Cr (3.0-15.0 mass%) and limiting harmful elements. This parameter optimization creates a eutectic system with melting temperature of 900-1050°C, successfully lowering the melting point from above 1000°C while preserving corrosion resistance through the protective oxide layer formed by Cr and other alloying elements.
4Temperature
If low melting temperature nickel brazing filler metals (BNi6, BNi7) are used to reduce brazing temperature, then energy costs decrease, but corrosion resistance becomes poor
Solution Approach 1:
The patent develops a composite nickel-based alloy incorporating Al, Ti, V, Cr, Mn, Mo, Si, and B elements in specific ratios. This multi-element composite structure achieves low melting temperature (900-1050°C) through eutectic composition while simultaneously ensuring excellent corrosion resistance via Cr-rich protective oxide layers and synergistic interactions among alloying elements, thereby resolving the contradiction between low brazing temperature and corrosion resistance.
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 nickel brazing filler metal effectively lowers brazing temperatures, reduces energy costs, and exhibits excellent corrosion resistance and wettability, making it suitable for stainless steel heat exchangers, refrigerant evaporators, and water heaters.
Implementation Method 1
having excellent wettability
Implementation Method 2
wettability spreading coefficient of 10 or more
Implementation Method 3
melting temperature of 1000° C. or less
Implementation Method 4
oxidation resistance and corrosion resistance are required
Data Source
AI summary
Provided is a nickel brazing filler metal which is capable of brazing and joining various stainless steel members at relatively low temperature, and has excellent corrosion resistance, and is used for brazing of a heat exchanger and the like. The nickel brazing filler metal is characterized by having a melting temperature of 1000° C. or less, exhibiting excellent Wettability, having corrosion resistance against acid, and containing 8.0 to 19.0 mass % of Cr, 7.0 to 10.5 mass % of P, 0.1 to 1.5 mass % of B, and 2.0 to 8.0 mass % of Cu, wherein a content of Mo is 10.0 mass % or less, a content of Si is 2.5 mass % or less, and the remainders are is Ni and unavoidable impurities. In addition, the nickel brazing filler metal may contain one or more elements selected from the group consisting of Co, Fe and Mn, where the content of Co is 5.0 mass % or less, the content of Fe is 3.0 mass % or less, the content of Mn is 3.0 mass % or less, and the total content of these elements is 8.0 mass % or less.