DE263603C - Process of providing wire made of aluminum or related metals with an insulating layer of high mechanical, thermal and electrical resistance - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- M 263603 CLASS 21 c. GROUP

in Berlin.

To provide resilience.

Patented in the German Empire on June 29, 1910.

It is known to use aluminum coils as a replacement for copper wire coils for electrotechnical Purposes to use, namely one has for such coils both bare and insulated Aluminum wire used.

When using aluminum wire, which is in a known manner with cotton, If silk etc. is insulated, the well-known inconveniences occur that through the insulation

ίο a significant part of what is available Winding space is lost, and that such coils do not exist because of the endangerment of the insulation withstand high temperature. If, on the other hand, you use bare wire that only passes through a extremely thin, invisible, natural oxide skin is protected, so the problem arises noticeable that the finished coils as a result of the weakness of this natural insulation only tolerate low voltage loads. Also, the thin insulating layer becomes light when the wire is wound into coils damaged, so that more or less turns are often short-circuited.

Since it is known that aluminum can be found in aqueous liquids, especially when there is passage of current, Can be strongly polarized (aluminum capacitor), so that the natural oxide skin can withstand higher voltages and damage to it Bodies is restored, and that even after the removal of the polarizing Liquids, the oxide skin is somewhat better electrically insulated than before Treatment, as has been tried, the finished coils made of aluminum wire afterwards to be treated in a watery bath. However, this does not result in a significantly higher dielectric strength, because the natural oxide layer only changes its properties very little.

The subject of this invention is now an aluminum coil which is made from a wire is what the advantage of organically insulated wires, namely the high insulation with the advantage of bare wires, namely that of good utilization of the winding space and resistance to high temperatures.

Before it is wound into coils, this wire is treated according to a process which is the combination of an electrolytic and an electrothermal process can be.

The treatment of the wire is carried out in such a way that it is used as a positive pole an electrical power source is drawn through an electrolytic bath, the bath voltage is chosen so high (z. B. 220 volts) that the polarization voltage of the aluminum is overcome and therefore a relatively strong current the polarization layer breaks through. It can be so strong that on the wire surface within the

Electrolyte fire phenomena occur. A harmful heating of the wire becomes avoided by the fact that it is drawn through the bath relatively quickly. The wire speed can e.g. B. 3 m per minute.

Since the polarization layer acts as a resistor for the permanent breakdown Current almost only the ohmic resistance of the electrolyte occurs, so the current density is reached relatively very high values of z. B. 10 amps per Square centimeters, with the largest part of the The electrical energy used is converted into heat and only a very small part for the electrolytic work is used.

The aluminum treated in this way differs from the ordinary or simply electrolytically polarized aluminum in every way; while the former is blank or is matt-bright, the aluminum treated in this way has a blue or blue-gray matt surface, and on closer examination it is found that a thin, very hard and tough layer is formed on the surface which is very resistant to friction, pressure and impact. The isolation ability this layer is also very good. It is Z. B. possible, two treated in this way Laying wires on top of each other and connecting them to the poles of a power source of 220 volts, without a noticeable current transfer taking place, while untreated wire or wire that only polarizes electrolytically is only able to withstand a fraction of a volt.

A large number of salt solutions can be used as bath liquid. Well proven has z. B. a solution of bicarbonate of soda.

When winding the wire into coils, it is possible because of the good insulation of this wire The same applies to bare aluminum wire in the event that subsequent post-treatment of the Coil is provided, always required intermediate layer between the individual wire layers in many cases can be completely spared. The insulating skin on the wire is in spite of her high insulation strength so thin that when calculating the winding space it becomes more like this Coils can be completely neglected. Thereby the resistance to high Temperature so high that the coil heats up to close to the melting temperature of the aluminum without the isolation suffering.

Nothing is changed in the subject matter of this invention when related to aluminum Metals, e.g. B. magnesium, aluminum alloys, etc., are used.

Claims (1)

Patent claim: Process, wire made of aluminum or related metals with an insulating layer to be provided with high mechanical, thermal and electrical resistance by using the wire as an electrode is drawn through an electrolytic bath, the voltage of which corresponds to the maximum polarization voltage of the bath liquid significantly exceeds, so that electrothermal due to the high current density at the wire surface Effects occur which support the electrochemical effects.