Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/02—Contacts characterised by the material thereof
  • H01H1/0203—Contacts characterised by the material thereof specially adapted for vacuum switches
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
  • C22C29/067—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds comprising a particular metallic binder
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/02—Contacts characterised by the material thereof
  • H01H1/021—Composite material
  • H01H1/023—Composite material having a noble metal as the basic material
  • H01H1/0233—Composite material having a noble metal as the basic material and containing carbides
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9265—Special properties
  • Y10S428/929—Electrical contact feature

Definitions

• a contact material for a vacuum switch having a composition comprising from 50 to 75 percent of tungsten carbide, from 0.3 to 5 percent of cobalt, and a remainder of copper, said tungsten carbide having a finely pulverized structure of a grain size of less than 1.2 microns.
• W-Cu alloys can be used as contacts in vacuum switches, and that contacts made of these alloys exhibit high resistance against welding of the contacts. It is also found that the contacts made of such materials can minimize the erosion of the contacts due to arcing in the vacuum switch.
• the tungsten-copper alloys have advantageous features as described above, the material has a drawback in that its so-called chopping level is considerably high.
• W-Cu alloys containing bismuth have been proposed.
• the W-Cu- Bi alloys were found to be inferior in workability in brazing.
• a primary object of the present invention is to provide a contact material to be used in a vacuum switch, which is operable with high reliability and has a low chopping level.
• Another object of the invention is to provide a contact material for a vacuum switch, which has a minimumrange of variation in the chopping level.
• Still another object of the invention is to provide a contact material for a vacuum switch, wherein the value of current above which the contacts tend to be welded is comparable to those in the W-Cu alloys.
• a contact material for a vacuum switch at a composition comprising from 50 to 75 percent of tungsten carbide, from 0.3 to 5 percent of cobalt, and a remainder of copper, said tungsten carbide having a minute pulverized structure of less than 1.2 microns.
• the present invention contemplates the provision of a contact material for a vacuum switch of greater capacities than 10 MVA at 3.3 KV, whereby the composition of the WC-Co-Cu alloy according to the present invention is adapted to be used for such an application.
• Pulverized tungsten carbide of approximately 1.2 microns in grain size was molded under a pressure of 0. l 5
• the percentage of voids in the presintered material was 55 percent by volume.
• the material was thereafter impregnated with 2 percent of Co-Cu alloy in vacuum at 1,300C.
• the material thus obtained was machined into contacts of approximately 24 mm in diameter, and
• the chopping level of the contacts was 3.5A, and the interruptable current was more than 4.8 KA.
• the contacts were not fused toelectricalperformancetests were carried out theregi gether under a current of 20KA flowing therethrougl EXAMPLE 2.
• Tungsten carbide powder of 0.7-micron grain size with the material according to the present invention. and cobalt powder of 2-micron gram size were mixed Table Composition Grain size lnterruptable Chopping Gas content by weight) of WC (or W) Current level As will be apparent from the above table, the interruptable current increases when cobalt is added, when the percentage of tungsten carbide becomes low, or
• the resulting mixture was press-formed under a pressure of 0.2 ton/cm and presintered in vacuum at 1,300C.
• the eentie of voids of the presintered material was 42 percent by volume.
• the presintered material was impregnated with Cu at l,300C in vacuum.
• the contact material thus obtained was formed into contacts as described in Example I, and electrical performance tests were carried out thereon. As a result, the chopping level was found to be 2.6A, the interruptable current was 4.5 KA, and the current fusing the contacts together was found to be 30 KA.
• finely pulverized tungsten carbide is used as the principal component, to which an appropriate amount of Co-Cu alloy is added, and the resulting mixture is formed into desired contacts, whereby interrupters and circuit breakers of high performance and reliability can be produced.
• a contact material for a vacuum switch consisting essentially of from about 50 to 75 percent of tungsten carbide having a finely pulverized structure of a grain size of less than 1.2 microns, from 0.3 to 5 percent of cobalt, and a remainder of copper.
• a method of producing a contact material for a vacuum switch in which a component of tungsten carbide having a finely pulverized structure of a grain size of less than 1.2 microns is press-formed and presintered into a porous structure, which is thereafter impregnated with another components of Co-Cu alloy, the ratio in amount of said components being from about 50 to percent of tungsten carbide, from 0.3 to 5 percent of cobalt, and a remainder of copper.
• a method of producing a contact material for a vacuum switch in which a component of tungsten carbide having a finely pulverized structure of grain size of less than 1.2 microns is mixed with a component of cobalt to form a mixture thereof, then press-formed and presintered into a porous structure, and is thereafter impregnated with a component of copper, the ratio of said components being from about 50 to 75 percent of tungsten carbide, from 0.3 to 5 percent of cobalt, and a remainder of copper.

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Cited By (8)

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Citations (4)

• 1972
  • 1972-03-07 JP JP47023320A patent/JPS5140940B2/ja not_active Expired
• 1973
  • 1973-03-06 US US00338568A patent/US3807965A/en not_active Expired - Lifetime

Patent Citations (4)

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