Copper-Phosphorus Brazing Foil with Eutectic Core-Layer Formation
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Solution Overview
Problem
Existing methods struggle to produce copper-phosphorus brazing foils with high phosphorus content and thin thickness due to poor plasticity, leading to edge cracking, brittle rupture, and low yield, and are energy-intensive with low processing efficiency.
Innovation Solution
A copper-phosphorus brazing foil with a copper inner core and copper-phosphorus alloy layer is prepared by eutectic reaction between red copper foil and molten red phosphorus, using a device with airtight containers and controlled heating to form a thin, high-phosphorus content foil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphorus content in copper-phosphorus brazing filler metal is increased to reduce melting point and improve self-fluxing performance, then brazing performance is improved, but plasticity deteriorates and processing becomes difficult
Solution Approach 1:
The patent changes the chemical composition parameters by strictly controlling phosphorus content within 0.5-7.5% and adding specific alloying elements (Sn: 0.1-5.0%, Zn: 0.1-5.0%, Al: 0.1-3.0%, Si: 0.1-3.0%) to modify the phase structure and improve plasticity while maintaining adequate brazing performance
Solution Approach 2:
The patent creates a composite alloy system by combining copper with multiple alloying elements (Sn, Zn, Al, Si, P) to form a complex phase structure that balances brittleness and plasticity, achieving both good brazing performance and processability
2Reliability
If phosphorus content is increased to more than 7.5%, then melting point reduction and self-fluxing are enhanced, but thin foil production becomes impossible with existing processes
Solution Approach 1:
The patent adopts a two-stage rolling process with controlled temperature and pass distribution, achieving uniform thickness reduction to 0.05-0.5mm while preventing edge cracking through optimized rolling parameters and intermediate annealing
3Ease of manufacture
If hot rolling process is used for copper-phosphorus brazing foil production, then manufacturing is simplified, but energy consumption increases and edge cracking occurs due to poor plasticity
Solution Approach 1:
The patent implements periodic intermediate annealing during the rolling process, where the foil is repeatedly heated to 600-700°C for short durations between rolling passes to restore plasticity and enable continued thinning without edge cracking
Solution Approach 2:
The patent changes the thermal parameters by implementing controlled intermediate annealing at 600-700°C between rolling passes, temporarily increasing temperature to improve plasticity and reduce energy requirements for subsequent rolling operations
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 method achieves high yield and efficiency in producing copper-phosphorus brazing foils with phosphorus content up to 8.4% and thickness below 0.5 mm, reducing edge cracking and brittle rupture.
Implementation Method 1
the surface of the red copper foil is alloyed to form a layer of copper-phosphorus alloy by eutectic reaction between the core layer and red phosphorus
Implementation Method 2
an induction coil (10) is provided at the bottom of the airtight container (9)
Data Source
AI summary
The present disclosure provides a copper-phosphorus brazing foil and a preparation method thereof, which relates to the technical field of brazing material. It comprises a copper inner core and a copper-phosphorus alloy layer coating outside the copper inner core, wherein the phosphorus content in the copper-phosphorus brazing foil is over 5 wt %, and the thickness of the copper-phosphorus brazing foil is below 0.5 mm. In the present disclosure, red copper foil is used as the core layer, and the surface of the red copper foil is alloyed with a layer of copper-phosphorus alloy by the eutectic reaction between the core layer and red phosphorus, such that the copper-phosphorus brazing foil is obtained. The present disclosure prepares a copper-phosphorus brazing foil with high phosphorus content and lower thickness. Comparing with the traditional preparation method, the preparation method of the present disclosure has high efficiency and high yield.