US1894260A - Integral unilateral conductor of electric currents - Google Patents

Description

. JR. ET AL 1,894,260

Jan. 17, 1933- w. T. ANDERSON INTEGRAL UNILATERAL CONDUCTOR OF ELECTRIC CURRENTS Filed July 26. 1930 VENTOR ATTORNEY Patented Jan. 17, 1933 UNITEDSTATES PATENT OFFICE wnrmu 'r. mnnson, .13., AND nns'rnn r. BIRD, or nnwmx, NEW JERSEY, as-

sreuons 'ro mnovra cnnmcan AND MANUFACTURING company, or NEWARK, NEW JERSEY, A conromrron or NEW annsnr INTEGRAL UNILATEBAL CONDUCTOR OF ELECTRIC OUBRENTS Application filed July 26,

This invention refers to improvements in the structure of unilateral conductors of electricity which are composed so as to form an integral unit.

Extended investigation has disclosed the existence of a number of metals having peculiar properties with reference to the conduction of electricity. When compounds of these metals are formed on the surfaces of the metals under proper chemical conditions, electricity does not flow as readily from the metal into the compound as it does from the compound into the metal. The junctions between the metals and the compounds are therefore unilateral conductors of electricity.

When these junctions were desired for rectification of considerable amounts of electric energy it became essential that the efficiency of the rectification be considered. All of the junctions between mother metals and their compounds were not found to be equally good. The problem of contact between the compound and the electric circuit conductors external to the rectifier was another vital part of the unit etliciency.

There was no especial difficulty with the contact between the mother metal and the external conductors because of the fact that the mother metal is usually heavy enough to be connected by soldering or welding to the external conductors. The method of securing contact between the external conductors and the metallic compound formed on the mother metal is then the-major consideration.

There are a number of methods of securing good contact between a compound formed on the surface of a mother metal and an external conductor of electric current. The earliest of these consisted in mechanically pressinga block of soft metal, such as tin, against the surface of the compound.

In this particular case, the mother metal was copper and the compound formed on the surface was copper oxide. It was later discovered that it Was possible to reduce a portion of the surface of the compound to produce a metallic layer on the outside of the compound with which good contact may be made.

I This metallic surface layer has a compar- 1930. Serial No. 470,949.

atively high point to point resistance and the efliciency of the individual unit would be materially reduced if contact was made with the reduced layer in only one spot. For this reason, contact is made all over the surface of the reduced layers by the use of collector plates pressed against them.

The collector plates cover a number of polnts on the surface of the metal layer and since the collector plate is of low resistance itself, it makes possible a low resistance contact to the whole surface of the metallic layer. However, any tarnish or dirt on the metallic layer Wlll interfere with the contact between the collector and the surface layer, and such a condition of course will increase the resistance of the joint and interfere with the best operation of the unit as a whole.

It is therefore, very essential that the metall1c layer on the surface of the oxide be clean so that the best possible contact may be obtalned with the collector plate. In the case of the copper copper-oxide rectifier unit, the

metallic surface layer is composed of copper.

Copper is subject to corrosion from air especially when the air is moist and a tarnish gradually forms on the surface. This tarnish is commonly an amorphous form of cuprous oxide. Amorphous cuprous oxide is affected in time by air and the presence of traces of carbon dioxide in the air so that cupric oxide mixed with copper carbonate and blue-green hydroxide are formed.

All of these copper compounds are very poor conductors of electricity and even in very thin layers offer an appreciable resistance to the passage of currents, and the presence of traces of these compounds between the collector plates and the metallic surface layer will materially reduce the efficiency of the unit.

It is an object of this invention to provide means to prevent the formation of the tarnish on the surface of the clean copper and so prevent the loss in efiiciency that results therefrom. The most desirable method of obtaining this result is that of alloying the copper with nickel built into the surface layer so that there is a form of nickel bronze for the surface layer rather than the pure copper.

Another method is that of painting the units with" lacquer so that the air is permanently removed from contact with the surface .of the metallic layer. Certain) char acteristics of these rectifier units make the use of protective lacquers undesirable be cause of their poor heat transmission.

The cop r co per-oxide rectifier'units are definitely li mite as to the temperature they can withstand; j If this limiting temperature Referring to the drawing, the unilateral electrical conducting unit is shown to include, a central la er 5 of the mother metal, which is preferab y copper, which has formed on each side thereof the layers 3, 4 of a comound of the mother metal, such compound or example being cuprous oxide.

Layers 3, 4 of cuprous oxide, or other compound of mother metal, have their outer surfaces reduced to provide thin la ers of me- .tallic copper, which are alloyed with nickel to form layers 1 and 2, of nickel bronze. The

complete unit, it wil be seen, consists of five distinct layers all inte ally united. The two bronze layers 1 an 2 are connected to one side of the external circuit, and the inner lager 5, of mother metal, is connected at the ot er side of the external circuit.

The nickel is alloyed with the copper to form a nickel bronze, by depositing the nickel electrolytically simultaneously with the reduction of the cuprous oxide.

Nickel ammonium sulphate slightly acidified with boric acid can be used for the electrolyte and sufficient acid is added to act upon the cuprous oxide to reduce it to co per.

As soon as the surface of the oxi e is covered with metal, the reduction ceases and pure nickel can be further deposited until a desired thickness is reached.

The method of forming the nickel-bronze alloy is' fully disclosed in U. S. Letters PatintbNo. 1,749,995, issued to us on March 11,

The surfaces of this unit will not oxidize and the electrical conductivity of the bronze layers is sufiicient so that use of additional means of collecting the current is not necessa l l ickel bronze is materiall more resistant to corrosion than copper, an the addition of nown for their poor amount of nickel, from a trace suchas one-tenth of one per cent, up to a material quantity such as 40 'per cent, results in an apfirec able gain in resistance to oxidation,

' avmg thus described our invention, what 'we claim as new and desire to secure by Letters Patent, is:

1. A unilateral electrical conductor comprising a layer of mother metal having integrally united thereto, a layer of a compound of the mother metal, and a la er of a compo sition metal integrally unite to the layer of compound, said composition metal having the mother metal as one of its elements.

2. In combination, copper having cuprous oxide formed thereon, said combination constituting in and of itself a unidirectional current carrying device, and means for making intimate contact with. the cuprous oxide to establish an electric circuit through said combination, said means comprisin a layer of copper reduced from the oxi e and combined with nickel to form a layer of nickel bronze on the cuprous oxide.

3. A unilateral electrical conductor, comrising a base of metallic copper having a ayer of cuprous oxide formed thereon, said cuprous oxide layer having its outer surface reduced to provide a thin layer of metallic copper, and metallic nickel alloyed with the thin layer of copper.

This specificatmn signed this 21st day of July, 1930/ WILLIAM T. ANDERSON, J a. LESTER F. BIRD.

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