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
  • H01H1/021—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
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

• the invention relates to a sintered contact material for low-voltage switchgear in power engineering from A g S n0 2 with Bi 2 0 3 and Cu0 as further metal oxide additives, the volume fraction of total metal oxide being between 10% and 25% with a SnO 2 volume fraction of 70% of the total oxide quantity .
• Contact materials based on silver-metal oxides have proven to be particularly advantageous for low-voltage switchgear in energy technology, for example in contactors or circuit breakers.
• cadmium oxide in particular was used as the active component, with these contact materials in particular fulfilling the desired electrical-technological properties and having proven themselves in the long-term use of switching devices.
• cadmium is known to be one of the toxic heavy metals and when the contact pieces burn off, CdO is also released to the surrounding area, efforts have been underway for some time to replace the CdO as completely as possible with other metal oxides.
• these materials should have an arc burn-up that is just as small, as well as low welding power and, in particular, low heating with continuous current flow, like the proven AgCdO materials for contact pieces.
• a new sintered contact material for the above purpose based on AgSnO 2 has already been disclosed, in which Bi203 and CuO and optionally CdO are provided as further metal oxides and the volume fraction of total metal oxide is between 10% and 25% with a SnO 2 - Volume part is ⁇ 70% of the total amount of oxide.
• the contact material is made by powder metallurgy from an internally oxidized alloy powder (so-called IOLP).
• the material with the following composition is especially suitable for the cadmium-free alternative in mass fractions of 87.95% Ag, 9.97% SnO 2 , 0.98% Bi 2 0 3 and 1.10% CuO Tests have now shown that the specified material does not yet fully meet the needs of practice.
• the object of the invention is therefore to provide a further material of the constitution AgSnO 2 Bi 2 O 3 CuO for the above-mentioned application.
• the object is achieved in that the SnO 2 mass fraction is specifically in the range from 4% to 8 % .
• the Bi 2 0 3 mass fraction is preferably between 0.5% and 4%, while the CuO mass fraction is between 0.3% and 1%; the rest is silver.
• the ratio of the mass fractions in% of SnO 2 to CuO is preferably between 8: 1 and 12: 1.
• GB-A-20 55 398 describes materials based on silver metal oxide, for the production of which sheets are produced from alloys, which are subsequently oxidized internally. So this is not a factory made with powder metallurgical processes substances, in particular not egleiterspulvern to the internal oxidation of L followed by compaction and sintering.
• GB-A-20 55 398 specifies, inter alia, a composition in mass fractions of 90.8% Ag, 8.5% Sn, 0.2% Bi and 0.5% Cu for the starting alloy. Otherwise, in the prior art, further components, for example cobalt, iron or nickel, are still added to the specified four-component system.
• the present invention was based on the surprising finding that the Sn0 2 content can be reduced and thus the Bi 2 0 3 content can be increased in order to obtain more favorable temperature properties than in the prior art.
• An alloy of AgSnBiCu of the specified composition is melted at 1353 K from 93.60% fine silver grains, 5.20% tin grains, 0.6% metallic bismuth as fragments and 0.6% copper in rod form.
• an alloy powder of the same composition is obtained.
• the powder portion is sieved to L 200 ⁇ m.
• This portion is internally oxidized in an oxygen-containing atmosphere between 723 K and 872 K, after which a composite powder of AgSnO 2 Bl 2 O 3 CuO of the composition in mass fractions of 92.10% Ag, 6.50% SnO 2 , 0.66% Bi 2 0 3 and 0.74% CuO is obtained.
• Such a composite powder is quantitatively completely internally oxidized and is referred to as IOLP.
• the composite powder is used to produce contact pieces by pressing in a die with 600 MPa.
• the contact pieces are sintered at 1173 K for one hour in air.
• the contact pieces are compacted by hot pressing at 923 K at 900 MPa. Further compression and solidification is achieved by a second sintering at 1173 K for one hour in air and a subsequent cold compression at 800 MPa.
• Metallographic micrographs show that the structure of the contact material produced in this way is fine and uniform with an average oxide particle size of 1.5 ⁇ m.
• method steps as in example 1 were selected; However, starting materials of the following composition in mass fractions were assumed: 93.96% fine silver grains, 4.00% tin grains, 1.64% metallic bismuth and 0.40% copper, from which an alloy is melted. Corresponding alloy powder is produced from this in the manner described above.
• an IOLP of AgSnO 2 Bi 2 C 3 CuO of the composition in mass fractions of 92.70% Ag, 5.01% SnO 2 , 1.80% Bi 2 0 3 and 0.49% Cuo is obtained.
• This IOLP is the starting material for the material and the contact pieces to be made from it.
• This material essentially corresponds to that of the material except for a larger grain size
• the welding force of the contact materials produced according to the invention was determined in a test switch.
• the measured values obtained essentially correspond to those of the AgCd012Bi2031, O contact material produced from internally oxidized alloy powder.
• service life and heating tests were carried out in motor contactors.
• the key parameters are the AC4 service life switching numbers of the contact pieces and the overtemperature of the current paths. in the Compared to AgCdO 12 Bi 2 O 3 1.0 materials, the lifespan switching numbers are about a factor of 1.8 higher, with higher temperatures only showing up to 10 ° C higher temperatures.
• test data of the new materials are shown in the table in comparison to the known material.
• the tin content is reduced to a suitable range, starting from the predetermined volume fraction of the sum metal oxides, and thus at least the relative Bi 2 0 3 fraction is increased, which leads to unexpectedly good results.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Composite Materials (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Contacts (AREA)
• Manufacture Of Switches (AREA)
• Glass Compositions (AREA)
• Powder Metallurgy (AREA)

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Publications (3)

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Cited By (5)

Citations (3)

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• 1984
  • 1984-06-12 DE DE19843421759 patent/DE3421759A1/de not_active Withdrawn
• 1985
  • 1985-05-31 DE DE8585106748T patent/DE3587004D1/de not_active Expired - Fee Related
  • 1985-05-31 AT AT85106748T patent/ATE84905T1/de not_active IP Right Cessation
  • 1985-05-31 EP EP85106748A patent/EP0164664B1/fr not_active Expired - Lifetime
  • 1985-06-11 JP JP60127036A patent/JPH0768593B2/ja not_active Expired - Lifetime
  • 1985-06-11 ZA ZA854389A patent/ZA854389B/xx unknown
  • 1985-06-11 BR BR8502760A patent/BR8502760A/pt not_active IP Right Cessation

Patent Citations (3)

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