Patent Application
20060283622
This application is related to and claims the benefit of priority from French Patent Application No. 05 50399, filed on Feb. 10, 2005, the entirety of which is incorporated herein by reference.
The invention relates to an electric wire having a core of aluminum or aluminum alloy.
When an aluminum or aluminum alloy wire is crimped in a crimping sleeve, and given the difference in the thermal expansion coefficients of aluminum and the metal constituting the crimping sleeve, which is often a copper alloy, alumina is formed around the wire by oxidation in air. Unfortunately, alumina is electrically resistive and consequently leads to an increase in electrical contact resistance, which can lead to contact being broken, when conveying light currents, or else to overheating, when conveying heavy currents.
The object of the invention is to avoid this formation of a layer of aluminum around at the electric wire by coating the wire in a material that does not present insulating properties that are harmful to good electrical operation of the conductor.
U.S. Pat. No. 3,636,242 discloses an electric wire with a core of aluminum or aluminum alloy provided with a coating layer of zinc and nickel alloy, the content by weight of nickel in the alloy lying in the range 25% to 75%.
That arrangement presents the following technical problems.
Zinc is more electronegative than aluminum and plays a sacrificial role in the event of galvanic corrosion. A high proportion of nickel alloyed to the zinc decreases this protective property.
Furthermore, the cost of zinc is much lower than the cost of nickel, and such an arrangement is therefore expensive in proportion to the nickel content used.
Finally, co-deposition of nickel and zinc makes it possible to improve the resistance to corrosion compared with depositing pure zinc.
The invention enables a compromise to be found between these various criteria constituted by resistance to corrosion, including to galvanic corrosion, and the cost of a wire having a core of aluminum or aluminum alloy.
To do this, the invention proposes an electric wire comprising a core of aluminum or aluminum alloy provided with a coating layer of zinc and nickel alloy, wherein the content by weight of nickel in the alloy lies in the range 5% to 15%, ignoring ordinary impurities.
In a preferred embodiment, said zinc and nickel alloy is a co-deposition on said core, i.e. the zinc and the nickel are alloyed while they are being deposited on the core of aluminum or aluminum alloy.
Preferably, the thicknesses said coating layer lies in the range 0.1 micrometers (μm) to 10 μm on the finished wire.
Advantageously, said coating layer is deposited on the conductor by electrodeposition.
Said coating layer may optionally be passivated, e.g. by chromium, molybdate, or phosphate, in order to increase its resistance to corrosion.
The invention also relates to a single strand electric conductor constituted by a wire as specified above.
Finally, the invention relates to a multistrand electric conductor made by assembling together a plurality of wires as specified above.
The invention is described below in greater detail with reference to the figures that show merely a preferred embodiment of the invention.
As can be seen in
According to the invention, the content by weight of nickel in the alloy lies in the range 5% to 15%. The thickness of the coating layer 3 lies in the range 0.1 μm to 10 82 m.
In order to further passivate this alloy against oxidation, the alloy may also be treated by being chromated, by molybdate, or by phosphate, or the equivalent. This treatment may be implemented by dipping the coated wire.
An electric wire in accordance with the invention is manufactured by wire-drawing. The coating layer 3 is deposited by electrodeposition on the core in an intermediate state, and then the core and the coating layer are drawn down together to the final diameter.
The invention is preferably applied to aluminum or aluminum alloy wires having a diameter lying in the range 0.08 millimeters (mm) to 12 mm in their final state after being drawn.
Wires 1 as obtained in this way can be assembled and twisted together to form a multistrand electric conductor as shown in
The invention also applies to wires of large diameter suitable for making a single strand conductor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05 50399 | Feb 2005 | FR | national |
