PTFE Sheath Fabrication Using Inert Atmosphere to Prevent Copper Oxidation
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Solution Overview
Problem
The existing methods for fabricating electric wires with copper alloy conductors coated in PTFE-based sheaths face issues such as copper oxidation during lubricant evaporation and sintering, leading to high contact resistance and increased costs due to the need for additional anti-corrosion coatings.
Innovation Solution
The method involves heating the copper alloy conductor without an outer coating in an atmosphere with low oxygen content, primarily using inert gases like nitrogen, to prevent oxidation, allowing the PTFE sheath to become oxygen-proof and protect the conductor, thus eliminating the need for additional coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bare copper alloy conductor is used without outer coating, then fabrication cost is reduced and structure is simplified, but copper oxidation occurs during heating leading to high contact resistance
Solution Approach 1:
The patent applies an inert atmosphere (nitrogen or other oxygen-free gas) during the lubricant evaporation and sintering heating processes to prevent copper oxidation. The inert gas environment replaces oxygen, allowing the bare conductor to be heated without forming copper oxide, thus maintaining good contact resistance while eliminating the need for anti-corrosion coatings.
2Reliability
If an anti-corrosion coating (silver or nickel layer) is applied to the conductor, then copper oxidation is prevented during heating, but fabrication cost increases and manufacturing complexity increases
Solution Approach 1:
The patent eliminates the need for anti-corrosion coatings by using an inert atmosphere during heating. The inert gas environment provides oxidation protection directly, replacing the function of silver or nickel coatings and simplifying the overall wire structure to conductor-plus-PTFE-sheath only.
Solution Approach 2:
The inert atmosphere acts as an intermediary between the copper conductor and oxygen, preventing direct contact and oxidation reactions. This mediator approach protects the conductor without requiring a permanent coating layer.
3Ease of manufacture
If the wire is heated in air during lubricant evaporation and sintering, then the process is simple, but copper oxidation occurs forming a visible oxide layer
Solution Approach 1:
The patent replaces air with an inert atmosphere (nitrogen or oxygen-free gas) during the heating process. This maintains process simplicity while eliminating copper oxidation, as the inert gas prevents oxygen from contacting the heated conductor surface.
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
This approach prevents copper oxidation during the heating process, reduces fabrication complexity and costs, and ensures good adhesion between the PTFE sheath and the conductor, resulting in a non-oxidized copper alloy conductor within the PTFE-based sheath.
Implementation Method 1
heating the wire mainly in an atmosphere having a low oxygen content, thereby preventing the conductor oxidizing while it is being heated
Implementation Method 2
heating the wire so as to cause the lubricant to evaporate and the PTFE-based sheath to sinter
Implementation Method 3
heating the wire so as to cause the lubricant to evaporate and the PTFE-based sheath to sinter
Data Source
AI summary
An electric wire comprises a non-oxidized conductor of copper alloy having no outer coating and in direct contact with a PTFE-based sheath. It is fabricated as follows: providing a copper alloy conductor without an outer coating; forming a sheath of a PTFE-based material around the conductor; and heating the wire in order to evaporate the lubricant and sinter the sheath. In order to avoid oxidizing the copper during the heating step, the wire is heated mainly in an atmosphere having a low oxygen content. The lubricant evaporation and/or sintering line for stabilizing the sheath of the electric wire comprises one or more ovens, each having an enclosure in which an atmosphere having a low oxygen content is maintained.