Nickel Brazing Filler Composition for Low-Temperature Stainless Joining
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Solution Overview
Problem
Existing nickel brazing filler metals for stainless steel heat exchangers face challenges in achieving low melting temperatures, sufficient wettability, and good corrosion resistance, especially when brazing temperatures are reduced to lower energy costs.
Innovation Solution
A nickel brazing filler metal with a composition of 8.0 to 19.0% Cr, 7.0 to 10.5% P, 0.1 to 1.5% B, 2.0 to 8.0% Cu, and optional Co, Fe, and Mn, with a melting temperature of 1000°C or less, ensuring excellent wettability and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the melting temperature of nickel brazing filler metal is lowered to reduce energy costs, then the brazing temperature can be reduced, but sufficient wettability cannot be obtained
Solution Approach 1:
The invention changes the chemical composition parameters of the brazing filler metal by adding specific elements (B: 0.05-2.0 mass%, Si: 0.05-3.0 mass%, Cu: 1.0-15.0 mass%) to modify the melting temperature and wettability characteristics, resolving the contradiction between low temperature and sufficient wettability
Solution Approach 2:
The invention creates a composite alloy system combining Ni-Cr-P base metal with additional elements (B, Si, Cu) to achieve a synergistic effect where the composite composition provides both low melting temperature and excellent wettability that individual elements cannot achieve alone
2Reliability
If conventional nickel brazing filler metals (BNi2, BNi5, Ni-Cr-P-Si) are used to ensure corrosion resistance, then corrosion resistance is maintained, but the melting temperature exceeds 1000°C
Solution Approach 1:
The invention modifies the composition parameters by limiting Cr content to 3.0-15.0 mass% (lower than conventional alloys) and adding B, Si, and Cu elements to achieve both low melting temperature (1000°C or less) and maintained corrosion resistance through the synergistic effect of the composite alloy system
3Temperature
If low melting temperature nickel brazing filler metals (BNi6, BNi7) are used, then the melting temperature is reduced, but corrosion resistance becomes insufficient
Solution Approach 1:
The invention creates a composite alloy system that combines the low-melting-temperature characteristics of BNi6/BNi7 with corrosion-resistant elements (Cr: 3.0-15.0 mass%, P: 5.0-15.0 mass%) and wettability-enhancing elements (B, Si, Cu) to achieve a balanced performance with melting temperature of 1000°C or less and sufficient 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 filler metal achieves a liquidus temperature of 1000°C or less, with a wettability spreading coefficient of 10 or more and corrosion resistance below 0.50 mg/m²·s, suitable for brazing stainless steel heat exchangers at reduced temperatures.
Implementation Method 1
having excellent wettability
Implementation Method 2
wettability spreading coefficient of 10 or more
Data Source
Figure 1(a)~1(b)
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.