US2138599A - Contact element - Google Patents

Description

Cal

Patented Nov. '29, 1938 Childrcos B. Gwyn, In, Bannockburn, 111., assignor tol'. K'Maliory a o..lnc., Indiana lia, Ind.,a corporation of Delaware r 2,188,599 coarser simmno mm. Application July. 14.1931,

. SerlaiNo. 153,639

4 cum. (0!. zoo-16c) This invention relates to electrical make and break contacts. An object of the invention is to provide an electrical make and break contact which is suitable for usein connection with magnetos, relays and similar devices. a

Another object is to provide an electrical and break which may be substituted for con tacts of the platinum, iridium'a'nd similar types.

A further object is the provision of an electrical make and break contactof comparatively high hardness and which, compared to contacts commonly used in the various fields mentioned, is relatively free from' carburization.

Other objects of the invention will be apparent from the following description taken in connec-- tion with the appended claims.

The present invention comprises the combine-1 tion of elements, methods of'manufacture, and the product thereof brought out and exemplified in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claims. Y

While a preferred embodime iit of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the combination of elements without departing from the spirit of the invention.

For many purposes, such as for magneto contacts, relay contacts, etc., it has heretofore been customary to use electrical make and break contacts composed of platinum-ruthenium or platinum-iridium alloys. While such contacts are fairly satisfactory due to their hardnessand noncorrosiveness in normal and most industrial atmospheres, a low transfer (carry-over) under the electric arcing inherent to magneto and most relay operations, they possess the advantages of high initial cost and difliculty of fabrication. Moreover, the alloys platinum and iridium have shown a marked aiilnity for hydro-carbon vapors under electrical arcing conditions and this characteristic "seems to increase with the increased percentages of iridium necessary to produce sufficient mechanical strength and hardness of magneto and similar uses.

According to my invention an electrical contact is formed of an alloy of silver with palladium or platinum, nickel and copper. that the ingredients be present in the following ranges of proportions:

Per cent Silver- 50 to 80 Palladium or platinum 12to25 Copper 5 to 15 Nickel-4n excess of a trace up to '7 In place of nickel I may substitute an element having the alloying characteristics of this metal.

It is preferred It will benoted that this alloy contains a predominance of silver. This alloy is well suited for substitution for platinum or palladium base alloys inthe fabrication of electric contacts. 1

Aspiramples" of specific contact alloys which have .been found especially suitable after exhaustive life tests and actual service'operation the following two compositions are representative: a

v Contact alloy A 7 Per cent Silver 60 Palladium 23 Copper l2 Nickel 5 Contact (111011 B s Per cent Silver 6'! Palladium 14 Copper 13.4 Nickel 5.6

The contact in this invention compares favorably in the electrical characteristics with platinum or palladium base contacts, particularly on relay and magneto service, and is superior to such contacts from a carburi'zation standpoint when exposed to hydrocarbon vapors. As compared with palladium base or platinum basecontacts there is, in addition toother advantages, a substantial saving in cost.

' The contacts have also been found to be well suited forthermostatic control contacts and for contacts to work in atmospheres which are normally destructive to contacts, such as in gases containing H28, 802 or NI-IrOH. They are also useful wherever a very light contact pressure must be used, or a current of low value must be used, even at extremely high rates of operation.

The density of the alloy is comparatively low sothat the cost per contact 'is low.

This alloy can be substituted for white gold, and can be used in jewelry, for a thermostatic material, for pyrometer controls and for dental inserts as well as for electrical contacts.

Contacts may be formed of the alloy by any of the usual ni'ethods of fabrication, such as by upsetting or heading, by screwmachine operations, by molding or stamping or other methods.

This contact material has a relatively low vapor pressure, and consequently does not are heavily or transfer readily when used on direct or pulsating current and, therefore has a low co-eiiicient of contact resistance rise.

It shows little or no tendency toward oxidation in service.

' While the present invention as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims. What is claimed is:

1. An electric contact element formed of analloy composed of about 5m copper, in excess of a trace up to 7% nickel, 12 to of an element selected from the group consisting of 10 palladium and platinum and to silver.

2. An electric contact element formed of an 2,188,599 alloy composed of about 12% copper, 5% nickel,

- nickel.

cnmnnnss B. GWYN, JR.