US3431377A - Mercury contact switch having an alloy contact - Google Patents

Mercury contact switch having an alloy contact Download PDF

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Publication number
US3431377A
US3431377A US620388A US3431377DA US3431377A US 3431377 A US3431377 A US 3431377A US 620388 A US620388 A US 620388A US 3431377D A US3431377D A US 3431377DA US 3431377 A US3431377 A US 3431377A
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US
United States
Prior art keywords
contact
alloy
mercury
nickel
copper
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Expired - Lifetime
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US620388A
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English (en)
Inventor
Malcolm Barlow
Peter J Planting
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AT&T Corp
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Bell Telephone Laboratories Inc
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Filing date
Publication date
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Application granted granted Critical
Publication of US3431377A publication Critical patent/US3431377A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/06—Contacts characterised by the shape or structure of the contact-making surface, e.g. grooved
    • H01H1/08—Contacts characterised by the shape or structure of the contact-making surface, e.g. grooved wetted with mercury
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H1/0201—Materials for reed contacts

Definitions

  • This invention relates to electric switches and particularly to those in which mercury is used on the contacting surfaces to improve switching performance.
  • Switches of the kind under consideration are generally referred to as mercury switches. They take several forms and the ones disclosed in Patent 2,609,464, issued to I. T. L. Brown et a1. and Patent 2,868,926, issued to C. E. Pollard, 11:, are typical.
  • the interacting contact surfaces in mercury switches have generally been made of a precious metal.
  • contacts surfaced with pure platinum have been widely used.
  • contacts surfaced with an alloy of platinum and nickel are also commonplace.
  • copper is added to the material used on the contact surfaces in order to inhibit sticking.
  • the resulting alloy readily wets but amalgamates only slightly.
  • the new alloy readily wets but does not readily amalgamate.
  • more nickel can be used than before without significantly affecting the magnetic characteristics of the contacts.
  • copper can be mixed with nickel alone to form a copper-nickel alloy which, when used as a contact surface, readily wets but neither amalgamates significantly nor exhibits adverse magnetic characteristics.
  • the drawing shows a partial section view of an electromagnetically responsive switch made in accordance with this invention.
  • the illustrated switch comprises an envelope or housing 10 which may be made of glass and which has two ends 10a and 10b. Two spaced pole-piece terminals 11 and 12 are sealed in the end 10a. Both terminals are made from a magnetic material such as 52 alloy. 52 alloy is a composition consisting essentially of 52 percent nickel and 48 percent iron. Further, the facing inner ends of each terminal 11 and 12 are provided with a contact 13 and 14, respectively. The composition of the contacts 13 and 14 is described below in detail.
  • a metal tube 20 is sealed in the end 10b so as to extend into the housing 10.
  • One part of the tube 20 is located within the envelope and has a flared or cup-like portion 20a for holding an electrically conducting contact wetting liquid; viz, mercury 21.
  • the mercury 21 may be present in a quantity suificient to fill part of the housing 10 and cover the cup-like portion 20a.
  • the mercury 21 can be initially pure or it can contain additives such as copper or the like.
  • a reed or swinger 15 is secured to the cup 20a. It is made of a magnetic material such as 78.5 Permalloy. 78.5 Permalloy is a composition consisting essentially of 21.2 percent iron, 78.5 percent nickel and .3 percent manganese.
  • One end of the swinger 15 terminates in a contacting portion 15a and the other end terminates in a looped portion 15b.
  • the central portion of the swinger 15 is adapted to transport the mercury 21 readily between the portions 15a and 15b.
  • the looped portion 15b contacts the mercury 21 in the cup 20a and the contacting portions 15a is wetted by the mercury 21 transported by the central portion of the swinger 15.
  • the contact portion 15a is disposed between the terminals 11 and 12 in a position to readily engage the contacts 13 and 14.
  • An energizing coil 22 shown schematically in the drawing, surrounds the housing 10.
  • the contact 13, the contact 14, and, if desired, the portion of the swinger 15 which engages the contacts 13 and 14, are preformed of an alloy before assembly in the switch. Specifically, they are preformed from an alloy which is substantially non-magnetic; which will not amalgamate in bulk with the wetting agent (viz, the mercury 21) and only slightly, if at all, on the surface; and which will form an advancing contact angle with the wetting agent of 20 degrees or less.
  • an advancing contact angle is defined as the angle lying between a surface being wetted and a plane lying tangent to the leading edge of the medium which is wetting the surface.
  • the mercury 21 contains a small amount of copper
  • the contacts 13 and 14 are preformed from an alloy consisting of copper and platinum. More specifically, the alloy in the described embodiment consists of platinum and copper mixed in the atomic proportions PtCu Switches having preformed contacts made of PtCu have been tested for sticking and the results demonstrate that the problem of sticking has been drastically reduced.
  • four sample lots, each containing relays equipped with contacts surfaced with PtCu were subjected to heating tests. The purpose of these heating tests was to force amalgamation between the mercury and the contact surfaces so as to intensify any sticking propensity. Specifically, three of the four lots were subjected to heat at 90 degrees Centigrade for 16 hours. In two of the three lots, no sticking occurred whatsoever.
  • the stuck relay In the third lot, only one of the 10 relays stuck. The stuck relay, however, was found to be defective for other reasons; i.e., its swinger was partially dry. The fourth lot was subjected to heat at 90 degrees centigrade for 92 hours and not a single relay stuck.
  • the contacts 13 and 14 were preformed from a combination consisting of a fused alloy of PtCu and a base metal.
  • a fused alloy such as PtCu
  • the contacts 13 and 14 are readily made by bonding a sheet of the fused alloy over the base metal and then stamping or cutting out contacts from the composite structure.
  • the resulting contacts will have a base material adapted for joining to one of the terminals 11 or 12, and a contact surface adapted to engage the swinger and be wetted by the mercury 21.
  • the contacts 13 and 14 can be formed by sputtering or by electroplating the alloy metal over the base metal. Whichever method is used, however, the alloy metal overlay in the preformed contact should have a thickness on the order of 10 microns or greater.
  • the principles disclosed herein can be extended to other arrangements.
  • nickel is readily substituted for the platinum.
  • the preformed contact alloy consists of coppernickel.
  • the nickel substitution moreover, need not be complete.
  • an alloy made of copper, platinum and nickel is particularly advantageous when the propor tion of nickel present is 12 to 15 percent by weight.
  • an alloy consisting of platinum and copper is especially effective, other alloys containing copper will also create contact surfaces which wet easily and which do not stick.
  • the proportion of copper in the alloy can be varied.
  • platinum and copper are present in the proportions PtCu
  • the proportion of copper in the alloy can be as low as 5' percent by weight. Better reliability, however, is obtained when the percentage of copper is increased to the order of 55 percent by weight. Best reliability is obtained when the amount of copper in the alloy is just sufficient to chemically stabilize the interface between the contact and the Wetting agent.
  • the amount of nickel can be varied. While the composition of the alloy can go as high as 70 percent nickel by weight before the alloy becomes magnetic in its operating range, best results are obtained when the amount of nickel is kept within 20 to 65 percent by weight.
  • a first contact having a contact surface preformed from an alloy consisting of copper and a metal selected from the group consisting of nickel, and an alloy of platinum and nickel;
  • said first contact is a fused alloy consisting of copper and platinum and wherein the percentage of copper in said first contact ranges from 5 percent to 55 percent by weight.
  • said first contact having a contact surface wetted by said mercury, said contact surface being preformed from an alloy which is substantially non-magnetic, which is substantially free of amalgamation in said mercury, and which forms an advancing contact angle of less than 20 degrees when wet by said mercury;
  • said second contact having a contact surface wetted by said mercury and arranged to engage the contact surface on said first contact.
  • said alloy consists of copper and a metal selected from the group consisting of platinum, nickel and an alloy of platinum and nickel.
  • a first contact having a contact surface preformed from an alloy of platinum, nickel and copper wherein the percentage of copper in said first contact ranges from 5 percent to 55 percent by weight, and the percentage of nickel ranges from 12 to 15 percent by weight;
  • a first contact having a contact surface preformed from an alloy of nickel and copper
  • a first contact having a contact surface made of an alloy preformed from copper and at least one metal selected from the group consisting of platinum and nickel, the amount of nickel present being no more than 70 percent and the amount of copper being between 5 percent and 55 percent by Weight;

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US620388A 1967-03-03 1967-03-03 Mercury contact switch having an alloy contact Expired - Lifetime US3431377A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US62038867A 1967-03-03 1967-03-03
US78747268A 1968-12-27 1968-12-27

Publications (1)

Publication Number Publication Date
US3431377A true US3431377A (en) 1969-03-04

Family

ID=27088709

Family Applications (2)

Application Number Title Priority Date Filing Date
US620388A Expired - Lifetime US3431377A (en) 1967-03-03 1967-03-03 Mercury contact switch having an alloy contact
US787472A Expired - Lifetime US3491219A (en) 1967-03-03 1968-12-27 Mercury switch having at least one contact preformed from an alloy containing nickel,copper and tin

Family Applications After (1)

Application Number Title Priority Date Filing Date
US787472A Expired - Lifetime US3491219A (en) 1967-03-03 1968-12-27 Mercury switch having at least one contact preformed from an alloy containing nickel,copper and tin

Country Status (7)

Country Link
US (2) US3431377A (fr)
AT (1) AT295631B (fr)
BE (1) BE711477A (fr)
DE (1) DE1690535B1 (fr)
FR (1) FR1555269A (fr)
GB (1) GB1219204A (fr)
NL (2) NL6802863A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3491219A (en) * 1967-03-03 1970-01-20 Bell Telephone Labor Inc Mercury switch having at least one contact preformed from an alloy containing nickel,copper and tin
US3495061A (en) * 1968-07-11 1970-02-10 Ibm Contacts for reed switches
DE3817361A1 (de) * 1987-05-25 1988-12-08 Matsushita Electric Works Ltd Gasdichtes schaltglied

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3584173A (en) * 1969-08-13 1971-06-08 Cunningham Corp Reed switch with improved contact isolation
DE2924252A1 (de) * 1979-06-15 1980-12-18 Bosch Gmbh Robert Schaltungsanordnung zur registrierung von fehlausloesungen fuer wenigstens eine dem schutz der insassen eines fahrzeugs bei einem unfall dienenden sicherheitseinrichtung
FR2473217A1 (fr) * 1980-01-08 1981-07-10 Socapex Interrupteur a contacts mouilles et a commande magnetique, et relais electrique comportant un tel interrupteur
EP0072135B1 (fr) * 1981-07-24 1986-03-19 Standex Electronics (Uk) Limited Relais à lames de contact sous enveloppe scellée contenant du mercure
US6979789B1 (en) 2005-03-21 2005-12-27 Agilent Technologies, Inc. Switches having wettable surfaces comprising a material that does not form alloys with a switching fluid, and method of making same

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2769875A (en) * 1953-09-25 1956-11-06 Bell Telephone Labor Inc Mercury contact switch
US3018354A (en) * 1959-10-22 1962-01-23 Bell Telephone Labor Inc Means for preventing contact sticking in mercury contact switches
US3054873A (en) * 1959-11-27 1962-09-18 Bell Telephone Labor Inc Liquid-contact switch
US3114811A (en) * 1961-11-16 1963-12-17 Bell Telephone Labor Inc Reduction of sticking of mercury-wetted contacts
US3146328A (en) * 1961-11-07 1964-08-25 Bell Telephone Labor Inc Non-sticking electrical contacts

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2547536A (en) * 1951-04-03 Formation of a surface easily
NL190202B (nl) * 1953-09-21 Nicholson Terence Peter Cilinderkoppakking voor een verbrandingsmotor.
US2868926A (en) * 1957-06-25 1959-01-13 Bell Telephone Labor Inc Switch
US3344373A (en) * 1966-02-07 1967-09-26 Automatic Elect Lab Switching device employing a globule of magnetizable electrically conductive fluid
NL137148C (fr) * 1967-03-03

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2769875A (en) * 1953-09-25 1956-11-06 Bell Telephone Labor Inc Mercury contact switch
US3018354A (en) * 1959-10-22 1962-01-23 Bell Telephone Labor Inc Means for preventing contact sticking in mercury contact switches
US3054873A (en) * 1959-11-27 1962-09-18 Bell Telephone Labor Inc Liquid-contact switch
US3146328A (en) * 1961-11-07 1964-08-25 Bell Telephone Labor Inc Non-sticking electrical contacts
US3114811A (en) * 1961-11-16 1963-12-17 Bell Telephone Labor Inc Reduction of sticking of mercury-wetted contacts

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3491219A (en) * 1967-03-03 1970-01-20 Bell Telephone Labor Inc Mercury switch having at least one contact preformed from an alloy containing nickel,copper and tin
US3495061A (en) * 1968-07-11 1970-02-10 Ibm Contacts for reed switches
DE3817361A1 (de) * 1987-05-25 1988-12-08 Matsushita Electric Works Ltd Gasdichtes schaltglied
US4866227A (en) * 1987-05-25 1989-09-12 Matsushita Electric Works, Ltd. Sealed contact device

Also Published As

Publication number Publication date
FR1555269A (fr) 1969-01-24
AT295631B (de) 1972-01-10
DE1690535B1 (de) 1970-12-23
BE711477A (fr) 1968-07-01
US3491219A (en) 1970-01-20
NL137148C (fr)
NL6802863A (fr) 1968-09-04
GB1219204A (en) 1971-01-13

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