Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C5/00—Alloys based on noble metals
  • C22C5/06—Alloys based on silver
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
  • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
  • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
  • C22C32/0021—Matrix based on noble metals, Cu or alloys thereof
• • 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
  • H01H1/0237—Composite material having a noble metal as the basic material and containing oxides
  • H01H1/02372—Composite material having a noble metal as the basic material and containing oxides containing as major components one or more oxides of the following elements only: Cd, Sn, Zn, In, Bi, Sb or Te
  • H01H1/02376—Composite material having a noble metal as the basic material and containing oxides containing as major components one or more oxides of the following elements only: Cd, Sn, Zn, In, Bi, Sb or Te containing as major component SnO2

Definitions

• This invention relates to those electrical contact materials which are widely used with electrical apparatuses such as switches, brakers, contactors, and so on.
• the electrical contact materials made in accordance with this invention are those made from Ag-Sn-In alloys which have been prepared by a melting method and internally oxidized, and differ from those prepared by mixing and sintering powdered Ag and oxidized and powdered Sn and In by a powder metallurgical method.
• Ag-Cd oxides alloys As an electrical contact material for the above-mentioned use, Ag-Cd oxides alloys are known. However, since Cd is harmful to health, they have been replaced by Ag-Sn oxides alloys without the employment of Cd. Such Ag-Sn oxides alloys are most extensively employed today as contact materials. Since it is considerably difficult to completely internally oxidize Sn of Ag-Sn alloys when Sn is contained therein at a rate more than 5 weight %, In is added to the alloys as an auxiliary solute metal element.
• In has to be added as much as more than 2%, although In oxides have a low refractoriness and comparatively weak in hardness. Therefore, the present inventors have pursued to internally oxidize, without the addition of In, solid-solution type alloys contained with more than 5 weight % of Sn. They were successful in the internal oxidation of such alloys which was conducted in an oxygen atmosphere of more than 10 atm, as disclosed in U.S. Patent No. 5, 078, 810.
• the present invention provides electrical contact materials made of solid-solution type alloys consisting of 5-20 weight % of Sn, more than 0.1 weight % to lett than 1 weight % of In, and the balance of Ag, and which has been internally oxidized.
• the present invention further provides a method for making electrical contact materials, which comprises activating solid-solution type alloy consisting of 5-20 weight % of Sn, more than 0.1 weight % to less than 1 weight % of In, and the balance of Ag, by preheating, followed by internally oxidizing the alloys by heating them in an oxygen atmosphere of more than 10 atmospheres to 200 atmospheres and at a temperature of 750 to 500°C to that the alloys are kept in solid phase and do not liquify.
• Ag-Sn of 5-20 weight % alloys which have been prepared by melting procedures at distinguished from powder metallurgy procedures, are internally oxidized with the addition to the alloys of a trace amount of In.
• the above-mentioned lower limit percentage of Sn is, when Sn it oxidized, to afford to the alloys such refractoriness with which they can work at electrical contacts.
• the upper limit of Sn is not to make the alloys too brittle.
• one or more of iron family elements that is, Fe, Ni, and Co may be added to the alloys at an amount of 0.001 to 1 weight % in total so as to regulate alloy structres.
• the above alloy (1), (2), and (3) were prepared by melting the above mentioned constituents and cast to ingots of 120mm in diameter and 400mm in length.
• the above alloy (4) which belongs to a prior art, was likewise made to an ingot, for its comperison with the alloys (1), (2), and (3) of this invention.
• Each alloy ingots was hot-pressed to a square bar of 30mm in thickness and 50mm in width.
• the bar was cut to a length of 500mm, and its upper and lower surfaces were shaved off in 3mm each to obtain a bar of 24mm in thickness, 50mm in width, and 500mm in length.
• pure silver of 2.5mm was hot-bonded.
• the bar was then rolled to a sheet having a thickness of 1.2mm, and punched out to obtain disk-shaped contacts of 6mm in diameter and 1.2mm in thickness. After they had been preheated in a furnace at 500°C, they were internally oxidezed by heating them to 700°C in an oxygen atmosphere of 25 atm for 48 hours.
• the aforementioned preheating of the alloys in advance of the internal oxidation is for activating them so that oxygen could penetrate smoothly into the alloys when they are subjected to baking for the internal oxidation.
• the heating temperature is selected to the lowest among the aforementioned range, the oxygen atmosphere could be made as higher as possible so far as alloys would not present a liquidous phase, about 200 atm is maximum therefor, becuase such is practical in carrying out this invention ecomonically and technically advantageously at an industrial scale.
• the electrical contact materials made in accordance with this invention are afforded with such conductivities which are satisfactory well within the range of practically employable values. And, their electrical characteristics, especially their initial contact resistances are considerably improved, and their temperature rising in use is lowed subseguently.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Contacts (AREA)
• Manufacture Of Switches (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (4)

Families Citing this family (8)

Citations (4)

• 1991
  • 1991-04-09 JP JP3164089A patent/JPH04311543A/ja active Pending
• 1992
  • 1992-03-27 TW TW081102359A patent/TW208720B/zh active
  • 1992-04-07 KR KR1019920005916A patent/KR920019955A/ko not_active Application Discontinuation
  • 1992-04-08 EP EP92303107A patent/EP0508746A1/en not_active Withdrawn
  • 1992-04-08 CN CN92102222A patent/CN1065688A/zh active Pending

Patent Citations (4)

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