Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
  • B22D11/004—Copper alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
  • B22D11/0611—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by a single casting wheel, e.g. for casting amorphous metal strips or wires
• • 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

Definitions

• the invention relates to a method for the production of copper-chrome contacts for vacuum switches.
• the invention also relates to the switch contacts thus produced.
• Vacuum interrupters for the power supply and distribution require electrical switching contacts made of an arc-resistant material, which meets the high thermal loads of z. T. over 5 MW / cm 2 , no gaseous or other harmful impurities is released and in particular can be produced economically.
• Copper-containing materials predominantly a mixture of copper (Cu) and chromium (Cr), are mostly used for switching contacts in vacuum interrupters, with i. a. of the
• Chromanteil between 20% -m (mass percent) and 50% (mass ⁇ percent) is.
• the particular, used in the vacuum switching technology forms of contact require countries, that the contact area to be machined must be such that a material thickness of at least 2 to 3 mm Benö ⁇ Untitled.
• the state diagram is to be used. This is known, for example, from the handbook of M. Hansen and K. Anderko "Constitution of Binary Alloys", McGraw-Hill Book Company, Inc. (1958), page 524.
• the state diagram Cu-Cr exhibits thermodynamic peculiarities, in particular a tectic and a monotectic, which will be discussed below. Since the two metals copper (Cu) and chromium (Cr) differ significantly in density, the direct herstel ⁇ is development of homogeneous melt materials not possible because the heavier component (Cu) is deposited. In general, so-called remelting materials are used for the highest quality contact materials.
• EP 0115292 Bl may be prepared by a coarse pre-sintered cylinder made of CuCr sphere with the aid of an electric arc in Edelgasatmo ⁇ is again remelted to a high density, homogeneous, fine-grained material Umschmelzwerkstoffe. Slices are then sawn from the cylindrical blanks obtained therefrom, which are subsequently machined again in order to obtain suitable final contours, slots and / or surfaces of the contacts. In particular, the necessary elimination of burrs which are produced during machining forms leads to high costs of contacts made in this way.
• a CuCr material Due to the high chromium content, a CuCr material is only suitable for the simplest forms of contact for contouring through punching. When machining the hard material, high tool wear with correspondingly high tool costs is unavoidable.
• the inventive method is based on the processing of a melt of CuCr by rapid solidification to thin, typically 1 to 2 mm thick strips or sheets, which can be set by the cooling rate of the melt a Cr concentration profile perpendicular to the sheet surface targeted.
• a melt of CuCr by rapid solidification to thin, typically 1 to 2 mm thick strips or sheets, which can be set by the cooling rate of the melt a Cr concentration profile perpendicular to the sheet surface targeted.
• Such amorphous metals are also referred to as metal glasses ⁇ .
• the chromium (Cr) naturally accumulates on the surface and the resulting density profile is "frozen” during solidification.
• Post-processing of the switching contacts is advantageously only in the region of the connection points to the contact carriers, i. in the solder range, necessary to produce the necessary tolerances and surface qualities.
• the inexpensive punched contacts thus produced can be connected as contact pads with contact-bearing structures, for. B. by brazing to achieve the required mechanical strength.
• the main advantages of the described method are on the one hand in the material savings by eliminating machining (sawing, turning, milling) as well as by targeted adjustment of electrical engineering necessary material thickness.
• machining sawing, turning, milling
• a larger economy is achieved.
• chromium since the expensive component chromium is only used in the contact surface area.
• punching process results in shorter production times and lower operating costs, since punching is easier to automate instead of turning and milling.
• the decisive advantage of the invention on the electrotechnical side is a considerably improved switching behavior on the one hand by the natural setting of a fine-grained structure near the surface, on the other hand also by the improved heat conduction through the positive Cu gradient towards the contact bottom.
• Figure 1 shows the state diagram of chromium (Cr) - copper (Cu)
• Figure 2 shows a micrograph of a copper-chromium material
• FIG. 3 shows an apparatus for the production of thin material strips of the type of production of amorphous metals
• FIG. 4 shows a micrograph in section through a Cu-Cr band produced with a device according to FIG. 3
• FIG. 5 shows the top view of an alloy strip with contact letters punched out of it
• FIG. 6 shows a vacuum switch contact with slotted contact ⁇ cup and a contact disk according to FIG. 5
• FIG. 1 shows the chromium-copper state diagram in such a way that 100% chromium content is plotted on the left side and 100% copper content on the right side.
• the chromium is known to have a comparatively high Melting point namely 1550 0 C. Copper other hand, has a comparatively low melting point, namely 1083 0 C. At a temperature of 1075 ° is formed at a copper content of 98.2 a eutectic. Below the melting point of copper, there is a narrow range of solubility for chromium. Otherwise, in the solid state below 700 0 C copper and chromium are not soluble in each other.
• the state diagram chromium-copper also has the special feature of a miscibility gap in the liquid state, with a monotectic is formed: Above the monotectic temperature of 1470 0 C in the range between about 6% copper and 58% copper up to a temperature of about 2000 0 C present two different CuCr melts that are not miscible with each other.
• NEN state latter means ( " This can be achieved, for example, by arc remelting according to EP 0 115 292 B1.
• FIG. 2 A microstructure of a copper-chromium material that was produced by the arc-remelting process is shown in FIG. Specifically, in FIG. 2, reference numeral 21 denotes a copper matrix in which chromium particles 22 are precipitated. Altogether, given the chromium content of a largely isotropic size and Konzentrationsvertei ⁇ development of the chromium particles 22 in the copper matrix 21st
• FIG 3 an arrangement, as übli ⁇ chlay is known for the preparation of amorphous metal films ( "sub-cooled glasses").
• the reference numerals in Figure 2 31 a rotatable about an axis perpendicular to the plane of axis I copper wheel , 32 a tub with a cooling bath for the copper wheel 31 and 33 a reservoir for a CuCr melt.
• the electric heater and other closed-loop control means are not illustrate in Figure 3 ⁇ provided.
• T> 2000 0 C from the reservoir 33 to the rotating wheel 31 is the same deposited on the surface of Cu-Cr material to ⁇ composition, wherein by cooling and solidification of the melt with a defined cooling rate dT / spe- dt-specific parameters can be preset.
• the lighter chromium preferably accumulates on the upper surface of the band. This is facilitated by the fact that the underside first solidifies, the upper portion of the ⁇ incurred band (sheet) but remains liquid longer and thus migrate the deposited Cr particles by your buoyancy in the heavier liquid copper to the top, where a concentration of chromium takes place.
• a thin strip 50 or a sheet before ⁇ given thickness with one of the melt corresponding copper and chromium concentration is predetermined by the transverse extent of the copper roller 31. With appropriate dimensioning can also produce sheets of greater width.
• the particular advantage of the specified production method is that segregation of the constituents can be predetermined according to their specific weight of the components during the cooling process. This means that the lighter components, in the present case the chrome particles or droplets, diffuse to the surface.
• FIG. 3 A micrograph of such a band-shaped contact material is shown in FIG. The grinding is carried out in a direction perpendicular to the band 50 of FIG. 3.
• 51 is the copper matrix and 52 is the chromium particles present therein.
• anisotropic a concentration distribution of the chromium content perpendicular to the surface of the belt 50.
• On the surface of the tape 50 results in a high chromium concen tration ⁇ and a finely dispersed distribution of the chromium particles.
• On the underside of the band 50 on the other hand, a low chromium concentration is present.
• the overall thermal conductivity perpendicular to the contact surface is greatly positively influenced, which results in an improved switching behavior, in particular in the sense of a higher switching capacity, compared to homogeneous, state-of-the-art contacts.
• 50 means the alloy strip from FIG. 3, which for example has a thickness of 2 mm.
• FIG. 1 A complete vacuum switch contact 100 for use as a radial field or axial field contact in vacuum switching devices is shown in FIG.
• the vacuum switch contact 100 consists of a contact pin 110 for current conduction and a contact pot 120 with slits 121 to 124 in the pot wall.
• the contact disk 60 from FIG. 5 is fixed by brazing on the upper edge of the contact pot 120 in such a way that the slots 61 to 64 adjoin the slots 121 to 124 in the wall of the contact pot 120.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
• Contacts (AREA)
• Manufacture Of Switches (AREA)
• Conductive Materials (AREA)

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• 2006
  • 2006-05-10 DE DE102006021772A patent/DE102006021772B4/de not_active Expired - Fee Related
• 2007
  • 2007-05-08 EP EP07728906A patent/EP2018445B1/fr not_active Not-in-force
  • 2007-05-08 CN CN200780016675.3A patent/CN101460640B/zh not_active Expired - Fee Related
  • 2007-05-08 WO PCT/EP2007/054453 patent/WO2007128819A2/fr not_active Ceased
  • 2007-05-08 DE DE502007005146T patent/DE502007005146D1/de active Active
  • 2007-05-08 AT AT07728906T patent/ATE482295T1/de active

Non-Patent Citations (1)

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