US2061624A

US2061624A - Silver alloy

Info

Publication number: US2061624A
Application number: US720251A
Authority: US
Inventors: Jr Childress B Gwyn
Original assignee: PR Mallory and Co Inc
Current assignee: Duracell Inc USA
Priority date: 1934-04-12
Filing date: 1934-04-12
Publication date: 1936-11-24
Anticipated expiration: 1953-11-24

Description

Patented Nov. 24, 1936 PATENT OFFICE SILVER ALLOY Childress B. Gwyn, Jr., Indianapolis, Ind., assignor, by mesne assignments, to P. R. Mallory & 00.. Inc., Indianapolis, Ind., a corporation of Delaware No Drawing. Application April 12,1934, Serial No. 720,251

5 Claims. (01. 75-1 13) LThis invention relates to a silver alloy for use as a replacement for pure silver and for uses to which previously known silver alloys have been employed, of which may be mentioned particu- 5 larly uses for the alloy of the present invention in connection with silverware and electrical contacts.

Alloys, of which silver is an ingredient, have been utilized heretofore for'such purposes as electrical contacts, silverware, coined silver, etc.

The alloys of the prior art including silver as I the principal ingredient have not proved entirely satisfactory for certain of the uses, particularly as electrical contacts. For that particular use,

15 the present alloy is desirable not only because of its uniform electrical conductivity, but also for I its arc snufiing properties, together with its resistance to mechanical deterioration, its anticorrosive properties, as well as its desirability 'as 20 an alloy which is conveniently manufactured and not prohibitive in cost.

The present invention seeks to accomplish the .fulfillment of the foregoing requisites, and to obtain an alloy of improved and desirable nature 5 conducive to simplicity of manufacture and mass production.

With these and'other objects in view, which will be more apparent as the description progresses, reference will now be had to the pre- 30 ferred ingredients of the alloy and mode of manufacture.

The alloy of the present invention is basically silver with additions of copper, cadmium and cobalt. In the formation of the alloy, it is preferable to provide a composition of the materials above specified in the following proportion by weight: i

r Parts 40 Silver '70 to 80 Copper 12 to 6 Cadmium 8 to 18 Cobalt 2 to 1 These several ingredients in the proportions named are melted together and allowed to cool, preferably being agitated to obtain a thorough mixture of the molten mass and a final homogeneous solid alloy, The resultant alloy has 50 been found to head very readily when upset into contacts and to be recognized as having a most desirable ductility and tenacity. It may also be readily polished and will retain the shine or lustre. Its use'in silverware as well as its de- 55 sirability as a replacement for coin or fine silver .cally active atmospheres with my improved alloy 10 show marked improvement over the fine, and coin silver and other silver alloys of the prior art.

Practically no sulphide coating will form on my alloy in atmospheres of sulphur dioxide, ofammonium polysulphide, etc.

The alloy of the present invention furthermore has been proved to have far superior arc snufiing properties than any known silver alloy of the prior art, and even superior to the use of either cadmium or cobalt alone or either cadmium or 00- balt alloyedwith silver for that purpose. This superiority over cadmium and cobalt alone is of even greater importance when it is appreciated that the inherent electrical resistance of cadmium is 7.54 micro-ohms per cubic centimeter at C. and the electrical resistance of cobalt is 9.80 micro-ohms per cubic centimeter at.20 C. whereas tests of the present alloy indicate an electrical resistance of only 3.98 micro-ohms per cubic centimeter at 20 C. When it is considered that pure silver has an electrical resistance of 1.59 micro-ohms per cubic centimeter at 20 0., it will be obvious that the resistance of the alloy approaches that of pure silver, being increased thereover not enough to be detrimental in the use of the alloy for contact purposes. While my alloys have been manufactured utilizing the proportionate number of parts specified as the respective limits of the several ingredients as listed above, it is to be understood that my invention is not necessarily confined to the particular proportions recited nor to the exclusion of other ingredients. Tests have shown, contrary to what might be expected upon cursory consideration, that the use of the twelve parts 5 of the copper gives a harder alloy than the use of six parts of copper. It may also be stated in passing, that an alloy comprising 18 parts of silver, 12 parts of copper, 8 parts of cadmium, and 2 parts of cobalt results in an'alloy having approximately 10.13 density and the utilization of 75 parts of silver, 6 parts of copper, 18 parts of cadmium and 1 part of cobalt results in an alloy having an approximate density of 10.048. I have found it desirable, in any event, to maintain a. proportion of silver and other ingredients of the alloy such that the total of the cadmium and/or copper, and/or cobalt shall not exceed 25% of the total. Furthermore, the percentage of. copper and of cadmium should each preferably be in excess of the percentage of cobalt but in any event, the sums of the percentages of copper and cadmium must exceed the percentage of cobalt and preferably vary materially so.

The alloy has been found to be particularly useful and serviceable as voltage, cutout, and current relay contacts used in conjunction with internal combustion engines, as electrical horn relay contacts, and as contacts used with electrical (resistance type) welding machines. These uses are in addition to-its superiority when used for silverware, silverware refinishing and replacements. In addition, this alloy makes an excellent easy solder for joining together silver and/or silver alloys.

Any deviation from the percentage of the alloying constituents as detailed above is not to be construed as a departure from the scope of my invention as it is entirely possible that I may desire to vary one "or more of the above constituents in order to obtain desirable characteristics for other or varied uses not detailed above,

or for special circuit or arcing characteristics,

and more particularly for definite fusing or nonfusing characteristics under given electrical conditions.-

Having thus described my invention, I claim: 1. An alloy consisting of '70 to 80 parts of approximately 10 silver, 6 to-12 parts of copper, 8 to 18 parts of cadmium and 1 to 2 parts of cobalt.

2. An alloy consisting of about 78 parts of silver, 12 parts of copper, 8 parts of cadmium and 2 parts of cobalt.

3. An alloy consisting of about parts of silver, 6 parts of copper, 18 parts of cadmium and l part of cobalt.

4. An alloy consisting substantially entirely of 6 to 12 parts copper, 8 to 18 parts cadmium, 1 to 2 parts cobalt and 70 to parts silver characterized by superiority of arc-snuffing ability over the materials cadmium, cobalt, cadmiumsilver alloys and cobalt-silver alloys, further characterized by greater resistance to sulfide corrosion than fine silverand coin silver, and still further characterized by an electrical resistance of about 3.98 micro-ohms per cubic centimeter at 20 C. and by a density of approximately 10 grams per cubic centimeter.

5. An electrical contact composed substantially entirely of 6 tov 12 parts copper, 8 to 18 parts cadmium, 1 to 2 parts cobalt and '70 to 80 parts silver characterized by superiority ofarcsnufllng ability over the materials cadmium, cobalt, cadmium-silver alloys and cobalt-silver alloys, further characterized by greater resistance to sulfide corrosion than fine silver and coin silver, and still further characterized by an electrical resistance of about 3.98 micro-ohms per cubic centimeter at 20 C. and by a density of grams per cubic centimeter.

CHILDRESS B. GWYN, JR.