Stainless Steel Coated Conductive Wire for Bending Fatigue
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Solution Overview
Problem
Existing electrically conductive wires, such as Be-Cu alloys, are expensive and lack sufficient strength and durability against repeated bending fatigue, while alternative wires with stainless steel coatings do not meet conductivity and strength requirements.
Innovation Solution
A core wire made of high-conductivity metal, such as copper, with a diffusion layer containing at least 0.5% Fe and a thickness between 0.4% and 5% of the core wire diameter, covered by a stainless steel coating, enhances both strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a copper alloy containing beryllium is used to achieve high strength, then strength is improved, but cost increases due to expensiveness
Solution Approach 1:
The patent uses a composite structure consisting of a copper core wire and a stainless steel coating layer. This composite design allows the copper core to provide electrical conductivity while the stainless steel coating provides high strength, eliminating the need for expensive beryllium-containing alloys and achieving both performance requirements at lower cost.
2Quantity of substance
If a core wire with stainless steel coating is used to reduce cost, then cost is reduced, but electrical conductivity and strength are insufficient
Solution Approach 1:
The patent applies local quality by creating a diffusion layer at the interface between the copper core and stainless steel coating. This diffusion layer contains iron atoms that strengthen the copper core locally at the critical interface region, providing enhanced strength precisely where the bonding between layers occurs, while maintaining the overall low-cost structure.
3Quantity of substance
If a core wire with stainless steel coating is used to reduce cost, then cost is reduced, but durability against repeated bending fatigue is insufficient
Solution Approach 1:
The diffusion layer creates local quality at the interface by concentrating iron atoms from the stainless steel coating into the copper core surface. This localized iron enrichment strengthens the interface bonding and improves fatigue resistance precisely at the critical stress concentration zone, enhancing durability without requiring expensive materials throughout the entire wire structure.
4Strength
If the diffusion layer thickness is increased to improve strength, then strength is improved, but electrical conductivity decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the diffusion layer thickness to be within 0.4% to 5% of the core wire diameter. This parameter optimization ensures that enough iron diffuses into the copper core to provide adequate strength enhancement, while limiting the diffusion depth to preserve the electrical conductivity of the bulk copper core, achieving a balanced performance.
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 conductive wire achieves higher strength than Be-Cu with comparable conductivity and improved durability against bending fatigue, while maintaining electrical properties.
Implementation Method 1
The core wire includes a diffusion layer containing not less than 0.5 mass % iron (Fe), arranged to constitute the surface of the core wire
Data Source
AI summary
An electrically conductive wire includes a core wire made of metal, and a coating layer made of stainless steel covering a surface of the core wire. The metal constituting the core wire has an electrical conductivity greater than that of the stainless steel. The core wire includes a diffusion layer containing not less than 0.5 mass % Fe, arranged to constitute the surface of the core wire. The diffusion layer has a thickness that is not less than 0.4% and not more than 5% of the diameter of the core wire.