Copper-Tin Alloy Laser Weldability and Recyclability
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Solution Overview
Problem
Current copper alloys used in electrical engineering and electronics, such as Cu-Zn and Cu-Fe, face challenges in recyclability, weldability, and property trade-offs like conductivity and corrosion resistance, with CuFe2P alloys being difficult to recycle due to tin contamination and having poor laser weldability.
Innovation Solution
A copper-tin alloy with specific compositions of tin, nickel, cobalt, zinc, iron, and phosphorus, allowing for properties comparable to CuFe2P alloys while enabling easy recycling and excellent laser weldability, formed into a composite material with a tin layer for corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Cu-Zn alloys are used to achieve sufficient mechanical strength and bendability, then tensile strength and hardness increase, but weldability deteriorates due to high vapor pressure of zinc
Solution Approach 1:
The patent changes the chemical composition parameters by replacing zinc with tin and adjusting the ratios of copper, iron, and phosphorus. This parameter change maintains mechanical strength while eliminating the high vapor pressure issue that causes poor weldability in Cu-Zn alloys.
Solution Approach 2:
The patent extracts zinc from the alloy composition and replaces it with tin. This removal of the problematic element (zinc with high vapor pressure) while retaining the desired mechanical properties through alternative alloying elements solves the weldability issue.
2Reliability
If alloying elements like nickel and chromium are added to improve corrosion resistance, then corrosion resistance increases, but electrical conductivity significantly decreases
Solution Approach 1:
The patent changes the alloying strategy by using tin instead of nickel and chromium. Tin provides corrosion resistance through formation of protective oxide layers and intermetallic phases, while having minimal impact on electrical conductivity compared to nickel and chromium additions.
Solution Approach 2:
The patent creates a composite microstructure with multiple phases including copper matrix, tin-rich intermetallic compounds, and phosphorus-containing precipitates. This composite structure provides both corrosion resistance from the protective phases and maintains electrical conductivity through the continuous copper matrix.
3Strength
If CuFe2P alloy is used to improve strength and relaxation behavior, then tensile strength increases, but laser weldability deteriorates due to Fe2P precipitates deflecting the laser beam
Solution Approach 1:
The patent modifies the local distribution and morphology of intermetallic phases. Instead of coarse Fe2P precipitates that deflect laser beams, the invention creates fine, uniformly distributed tin-rich intermetallic phases and phosphorus-containing precipitates that do not interfere with laser beam transmission, enabling good laser weldability while maintaining strength.
4Reliability
If tin is added to CuFe2P alloy for corrosion protection, then corrosion resistance improves, but electrical conductivity decreases by 25% and recyclability deteriorates due to tin contamination
Solution Approach 1:
The patent optimizes the tin content parameter to a specific range (0.5-3.0 wt.%) that provides sufficient corrosion resistance through protective tin-rich phases while limiting tin concentration to prevent excessive conductivity loss and facilitate recyclability. This parameter optimization balances all three requirements.
Data Source
AI summary
The invention relates to a copper-tin alloy, comprising 0.2 to 0.8 wt % Sn, 0.1 to 0.6 wt % Ni and / or Co, 0 to 0.05 wt % Zn, 0 to 0.2 wt % Fe, 0.008 to 0.05 wt % P and the remainder Cu. The invention furthermore relates to a corresponding composite material having a base material of such an alloy and to applicable uses thereof. The technological and physical properties are comparable to those of a CuFe2P alloy. However, the alloy according to the invention and a tinned composite material derived herefrom can be easily recycled.