Ni-Based Amorphous Brazing Foil for Corrosion-Resistant Binder-Free Joining
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Solution Overview
Problem
Existing Ni-based brazing filler metals, such as BNi-15, require a binder removal process that adds cost and contamination risks in vacuum furnaces, and the paste form has a thick coating and high material usage, whereas foils offer improved assembly efficiency but lack high corrosion resistance.
Innovation Solution
A Ni-based amorphous brazing foil with a composition of Cr: 19.0-30.0%, P: 4.0-9.0%, Si: 0.2-4.0%, B: 0.3-1.0%, and a balance of Ni and impurities, with a B/Cr atomic ratio of 0.17 or less, providing excellent ductility and corrosion resistance, and optionally containing Mo up to 5.0%, and having a width of 5 mm to 300 mm and thickness of 10 μm to 100 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If paste form is used, then coating can be applied, but binder removal process is required adding cost and contamination
Solution Approach 1:
The invention extracts and removes the binder component from the brazing filler material, transitioning from paste form (metal powder + binder) to foil form. This eliminates the binder removal process entirely, resolving the technical contradiction by removing the harmful element (binder) while preserving the useful function (coating application).
Solution Approach 2:
The invention changes the physical state and composition parameters of the brazing filler material from a paste (with binder) to a foil (binder-free). This parameter change transforms the material form to eliminate the need for binder removal, solving the contradiction between ease of manufacture and process complexity.
2Ease of manufacture
If paste is used, then coating can be applied, but coating thickness is thick and material usage is large
Solution Approach 1:
The invention uses a thin foil form (typically 10-50 μm thickness) instead of thick paste coating (about 100 μm). This thin film approach reduces material usage by a factor of 2-10 times while still providing effective brazing coverage, resolving the contradiction between ease of manufacture and material quantity.
3Productivity
If conventional Ni-based brazing foil is used, then assembly efficiency is improved, but corrosion resistance is insufficient
Solution Approach 1:
The invention creates a composite alloy system combining Ni, Cr, P, Si, and B elements with specific composition ratios. This composite material approach achieves both excellent corrosion resistance (through Cr and P content) and good assembly efficiency (through foil form), resolving the contradiction between productivity and reliability.
Solution Approach 2:
The invention optimizes the compositional parameters (Cr: 10-30%, P: 3-10%, Si: 0.1-5%, B: 0.1-2%) to achieve the desired balance between corrosion resistance and assembly efficiency. By carefully controlling these parameters, the foil provides both high reliability and good productivity.
4Ease of manufacture
If binder is added to paste, then coating can be applied, but contamination of furnace lining and exhaust system occurs
Solution Approach 1:
The invention extracts and eliminates the binder component from the brazing filler material, transitioning from paste form to foil form. This removal of the binder eliminates the source of contamination (organic decomposition products) that would otherwise contaminate the furnace lining and exhaust system, resolving the contradiction between ease of manufacture and harmful factors generated.
Data Source
AI summary
There is provided a Ni-based amorphous brazing foil containing: in mass %: Cr: from 19.0% to 30.0%; P: from 4.0% to 9.0%; Si: from 0.2% to 4.0%; B: from 0.3% to 1.0%; and a balance of Ni and impurities, in which B/Cr is 0.17 or less in terms of an atomic ratio.