EP0369283B1 - Sintered contact material for low-tension switchgear, particularly for contactors - Google Patents

Sintered contact material for low-tension switchgear, particularly for contactors Download PDF

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EP0369283B1
EP0369283B1 EP89120515A EP89120515A EP0369283B1 EP 0369283 B1 EP0369283 B1 EP 0369283B1 EP 89120515 A EP89120515 A EP 89120515A EP 89120515 A EP89120515 A EP 89120515A EP 0369283 B1 EP0369283 B1 EP 0369283B1
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Prior art keywords
bismuth
oxide
contact material
sintered contact
material according
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German (de)
French (fr)
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EP0369283A2 (en
EP0369283A3 (en
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Wolfgang Haufe
Ralf-Dieter Dipl.-Ing. Krause
Bernhard Rothkegel
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Siemens AG
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Siemens AG
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    • 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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
    • H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts
    • H01H11/048—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts by powder-metallurgical processes

Definitions

  • the invention relates to a sintered contact material for low-voltage switching devices in energy technology, in particular for motor contactors, with silver (Ag), tin oxide (SnO2), bismuth oxide (Bi2O3) and copper oxide (CuO) made from an internally oxidized alloy powder (IOLP) of a silver-tin bismuth -Copper starting alloy, the tin oxide being present in mass fractions of 4 to 12% and the ratio of the mass fractions of tin oxide to bismuth oxide on the one hand and of tin oxide to copper oxide in the internally oxidized alloy powder, respectively, between 8: 1 and 12: 1.
  • Contact materials based on silver-tin oxide have proven to be particularly advantageous for use in low-voltage switchgear in power engineering, for example in motor contactors, but also in circuit breakers.
  • Contact pieces made of silver-tin oxide have a long service life in motor contactors, but have the disadvantage that thermally stable oxide layers form on the contact surfaces when exposed to arcing, which lead to increased contact resistance. This leads to inadmissibly high excess temperatures on the switching elements when the current is conducted in the switching device, which can lead to damage to the plastic parts.
  • DE-OS 33 04 637 ( ⁇ EP-A-0 182 386), DE-OS 34 21 758 ( ⁇ EP-A-0 170 812) and DE-OS 34 21 759 ( ⁇ EP-A- 0 164 664) describes sintered contact materials of the constitution AgSnO2Bi2O3CuO made from internally oxidized alloy powders, which on the one hand meet the demands made today on the number of life cycles and on the other hand the switch-on capacity. These materials can have a relatively high proportion of bismuth oxide, which is introduced either via the internally oxidized alloy powder or via a separate admixture of the bismuth oxide to the internally oxidized alloy powder. However, these materials only reach acceptable values with regard to overtemperature if the total mass fraction of oxide is limited to 8% to 11%.
  • materials for electrical contacts based on AgSnO2 which additionally contain a small proportion of compounds of refractory metals, namely vanadium oxide, molybdenum oxide or bismuth titanate and preferably still molybdenum carbide or tungsten carbide.
  • Such materials are said to be just as effective as tungsten oxide to be able to lower the contact point temperature, but to guarantee this lower contact point temperature for a larger number of switching cycles than a silver-tin oxide-tungsten oxide material.
  • the object of the invention is to further improve a material of the constitution AgSnO2Bi2O3CuO made from internally oxidized alloy powder.
  • the oxide content should be as high as possible and the overtemperature should be as high as possible low and in which the other properties are left in an optimal ratio to each other.
  • the object is achieved according to the invention in the case of a contact material of the type mentioned at the outset by bismuth zirconate as a further metal oxide which is admixed with the internally oxidized alloy powder.
  • Bismuth titanate may also be present within the scope of the invention.
  • the bismuth zirconate is preferably present as a mixed oxide 2Bi2O3.3ZrO2 and the bismuth titanate in a stoichiometric compound Bi2Ti2O2.
  • the mass fraction of bismuth zirconate and possibly bismuth titanate is between 0.1 and 5%, the total content of the oxides in mass fractions being a maximum of 20%.
  • bismuth zirconate powder and / or bismuth titanate powder are added to an internally oxidized alloy powder of a predetermined composition, organic solvents, in particular propanol, being used when the internally oxidized alloy powder is mixed with the powder of the additional oxides.
  • the lifetime switching number corresponds to the volume erosion of the contact material and the overtemperature corresponds to the contact resistance.
  • alloys made of AgSnBiCu are melted at a temperature of approximately 1323 K (1050 ° C.). Alloy powders of the same composition are obtained by atomizing the melt with water in a pressure atomization system. After drying, the powders are sieved to ⁇ 300 ⁇ m. This portion is quantitatively internal oxidized in an oxygen-containing atmosphere at temperatures between 773 K (500 ° C) and 873 K (600 ° C), after which AgSnO2Bi2O3CuO powder the following composition can be obtained in percentages by mass:
  • the specified AgSnO2Bi2O3CuO powders are powdered from bismuth zirconate (2Bi2O3.3ZrO2) and / or bismuth titanate (Bi2Ti2O7) added by wet mixing in a stirred ball mill using propanol and steel balls. After the mixture has dried, the steel balls are separated from the respective powder mixture by sieving.
  • the starting powders for the contact piece production of the material examples given in the table are composed as follows:
  • the internally oxidized alloy powder forms the basis with 100 percent by mass, to which the additional oxides are added in percentages by mass.
  • the starting powder mixture produced is compressed with a pressure of, for example, 600 MPa and the pressed bodies obtained are at a temperature between 1123 K (850 ° C.) and 1148 K (875 ° C.) sintered in air for 2 h.
  • the sintered contact pieces are hot pressed at a temperature of 923 K (650 ° C) and a pressure of, for example, 1000 MPa.
  • the grain size which can be controlled by the sintering temperature and duration, runs as a front inside the AgSnO2Bi2O3CuO powder particles 1.
  • the oxide precipitates 2 have an elongated, partly streak-like shape and are high in zirconate and / or titanium.
  • the structure of the structure according to the figure has a favorable influence on the electrical conductivity of the oxide layers which form on the contact surfaces when exposed to arcing.
  • two-layer finished molded parts are expediently manufactured with a solderable pure silver layer. These molded parts can be soldered directly onto the contact carrier, for example by motor contactors.
  • the new materials which were produced by sintering an internally oxidized alloy powder with the addition of bismuth zirconate powder and / or bismuth titanate powder, in particular with a total mass fraction of about 12% oxide, result in the required improvement in the overtemperature behavior. Values from 60 K to 70 K were measured, the lifetime switching number remaining at the same high level of the prior art. The range of properties is thus improved overall, with silver being saved in every case.

Description

Die Erfindung bezieht sich auf einen Sinterkontaktwerkstoff für Niederspannungsschaltgeräte der Energietechnik, insbesondere für Motorschütze, mit Silber (Ag), Zinnoxid (SnO₂), Wismutoxid (Bi₂O₃) und Kupferoxid (CuO) hergestellt aus einem inneroxidierten Legierungspulver (IOLP) einer Silber-Zinn-Wismut-Kupfer-Ausgangslegierung, wobei das Zinnoxid in Massenanteilen von 4 bis 12 % vorhanden ist und das Verhältnis der Massenanteile von Zinnoxid zu Wismutoxid einerseits und von Zinnoxid zu Kupferoxid andererseits im inneroxidierten Legierungspulver jeweils zwischen 8:1 und 12:1 beträgt.The invention relates to a sintered contact material for low-voltage switching devices in energy technology, in particular for motor contactors, with silver (Ag), tin oxide (SnO₂), bismuth oxide (Bi₂O₃) and copper oxide (CuO) made from an internally oxidized alloy powder (IOLP) of a silver-tin bismuth -Copper starting alloy, the tin oxide being present in mass fractions of 4 to 12% and the ratio of the mass fractions of tin oxide to bismuth oxide on the one hand and of tin oxide to copper oxide in the internally oxidized alloy powder, respectively, between 8: 1 and 12: 1.

Für den Einsatz in Niederspannungsschaltgeräten der Energietechnik, beispielsweise in Motorschützen, aber auch in Leistungsschaltern haben sich Kontaktwerkstoffe auf der Basis von Silber-Zinnoxid als besonders vorteilhaft erwiesen. Kontaktstücke aus Silber-Zinnoxid erreichen in Motorschützen eine hohe Lebensdauerschaltzahl, haben aber den Nachteil, daß sich bei Lichtbogeneinwirkung auf den Kontaktflächen thermisch sehr stabile Oxidschichten ausbilden, die zu einem erhöhten Kontaktwiderstand führen. Dadurch treten bei Dauerstromführung im Schaltgerät unzulässig hohe Übertemperaturen an den Schaltgliedern auf, die insbesondere zu Schäden an den Kunststoffteilen führen können.Contact materials based on silver-tin oxide have proven to be particularly advantageous for use in low-voltage switchgear in power engineering, for example in motor contactors, but also in circuit breakers. Contact pieces made of silver-tin oxide have a long service life in motor contactors, but have the disadvantage that thermally stable oxide layers form on the contact surfaces when exposed to arcing, which lead to increased contact resistance. This leads to inadmissibly high excess temperatures on the switching elements when the current is conducted in the switching device, which can lead to damage to the plastic parts.

In der DE-OS 33 04 637 (≙ EP-A-0 182 386), der DE-OS 34 21 758 (≙ EP-A-0 170 812) und der DE-OS 34 21 759 (≙ EP-A-0 164 664) werden aus inneroxidierten Legierungspulvern hergestellte Sinterkontaktwerkstoffe der Konstitution AgSnO₂Bi₂O₃CuO beschrieben, die einerseits die heute gestellten Forderungen an die Lebensdauerschaltzahl und andererseits an das Einschaltvermögen erfüllen. Bei diesen Werkstoffen kann ein relativ hoher Wismutoxid-Anteil vorhanden sein, der entweder über das inneroxidierte Legierungspulver oder über eine separate Zumischung des Wismutoxides zum inneroxidierten Legierungspulver eingebracht wird. Allerdings erreichen diese Werkstoffe hinsichtlich der Übertemperatur nur dann akzeptable Werte, wenn der Gesamtmassenanteil an Oxid auf 8 % bis 11 % begrenzt wird.In DE-OS 33 04 637 (≙ EP-A-0 182 386), DE-OS 34 21 758 (≙ EP-A-0 170 812) and DE-OS 34 21 759 (≙ EP-A- 0 164 664) describes sintered contact materials of the constitution AgSnO₂Bi₂O₃CuO made from internally oxidized alloy powders, which on the one hand meet the demands made today on the number of life cycles and on the other hand the switch-on capacity. These materials can have a relatively high proportion of bismuth oxide, which is introduced either via the internally oxidized alloy powder or via a separate admixture of the bismuth oxide to the internally oxidized alloy powder. However, these materials only reach acceptable values with regard to overtemperature if the total mass fraction of oxide is limited to 8% to 11%.

In der DE-A-32 32 627 sind weiterhin Werkstoffe für elektrische Kontakte auf der Basis von AgSnO₂ beschrieben, welche zusätzlich noch einen kleinen Anteil von Verbindungen hochschmelzender Metalle enthalten, nämlich Vanadiumoxid, Molybdänoxid oder Wismuttitanat sowie vorzugsweise noch Molybdäncarbid oder Wolframcarbid. Solche Werkstoffe sollen ebenso wirksam wie Wolframoxid die Kontaktstellentemperatur zu senken vermögen, diese erniedrigte Kontaktstellentemperatur aber für eine größere Schaltspielzahl gewährleisten als ein Silber-Zinnoxid-Wolframoxid-Werkstoff.In DE-A-32 32 627 materials for electrical contacts based on AgSnO₂ are also described, which additionally contain a small proportion of compounds of refractory metals, namely vanadium oxide, molybdenum oxide or bismuth titanate and preferably still molybdenum carbide or tungsten carbide. Such materials are said to be just as effective as tungsten oxide to be able to lower the contact point temperature, but to guarantee this lower contact point temperature for a larger number of switching cycles than a silver-tin oxide-tungsten oxide material.

Aufgabe der Erfindung ist es demgegenüber, einen aus inneroxidiertem Legierungspulver hergestellten Werkstoff der Konstitution AgSnO₂Bi₂O₃CuO weiter zu verbessern. Dabei soll zwecks Silbereinsparung der Oxidanteil möglichst hoch und trotzdem die Übertemperatur möglichst niedrig und bei dem die übrigen Eigenschaften in einem optimalen Verhältnis zueinander belassen sind.In contrast, the object of the invention is to further improve a material of the constitution AgSnO₂Bi₂O₃CuO made from internally oxidized alloy powder. In order to save silver, the oxide content should be as high as possible and the overtemperature should be as high as possible low and in which the other properties are left in an optimal ratio to each other.

Die Aufgabe ist erfindungsgemäß bei einem Kontaktwerkstoff der eingangs genannten Art durch Wismutzirkonat als weiteres Metalloxid, das dem inneroxidierten Legierungspulver zugemischt ist, gelöst. Im Rahmen der Erfindung kann zusätzlich auch Wismuttitanat vorhanden sein. Vorzugsweise liegen das Wismutzirkonat als Mischoxid 2Bi₂O₃.3ZrO₂ und das Wismuttitanat in stöchiometrischer Verbindung Bi₂Ti₂O₇ vor. Dabei beträgt der Massenanteil an Wismutzirkonat und gegebenenfalls Wismuttitanat zwischen 0,1 und 5 %, wobei der Gesamtgehalt der Oxide in Massenanteilen maximal 20 % ist.The object is achieved according to the invention in the case of a contact material of the type mentioned at the outset by bismuth zirconate as a further metal oxide which is admixed with the internally oxidized alloy powder. Bismuth titanate may also be present within the scope of the invention. The bismuth zirconate is preferably present as a mixed oxide 2Bi₂O₃.3ZrO₂ and the bismuth titanate in a stoichiometric compound Bi₂Ti₂O₂. The mass fraction of bismuth zirconate and possibly bismuth titanate is between 0.1 and 5%, the total content of the oxides in mass fractions being a maximum of 20%.

Zur Herstellung eines solchen Werkstoffes wird einem inneroxidierten Legierungspulver vorgegebener Zusammensetzung Wismutzirkonatpulver und/oder Wismuttitanatpulver hinzugefügt, wobei beim Naßmischen des inneroxidierten Legierungspulvers mit dem Pulver der Zusatzoxide organische Lösungsmittel, insbesondere Propanol, verwendet werden.To produce such a material, bismuth zirconate powder and / or bismuth titanate powder are added to an internally oxidized alloy powder of a predetermined composition, organic solvents, in particular propanol, being used when the internally oxidized alloy powder is mixed with the powder of the additional oxides.

Im Rahmen der Erfindung ergab es sich überraschenderweise, daß speziell durch den Zusatz von Wismutzirkonatpulver und weiterhin von Wismuttitanatpulver zu einem inneroxidierten Legierungspulver aus AgSnO₂Bi₂O₃CuO gegenüber dem Stand der Technik bei hoher Lebensdauerschaltzahl eine Absenkung der Übertemperatur erreicht wird.In the context of the invention, it was surprisingly found that, in particular, the addition of bismuth zirconate powder and further of bismuth titanate powder to an internally oxidized alloy powder made of AgSnO₂Bi₂O₃CuO compared to the prior art results in a reduction in the excess temperature with a high number of life cycles.

Weitere Einzelheiten und Vorteile der Erfindung ergeben sich aus der nachfolgenden Beschreibung des Verfahrens zur Herstellung von Kontaktstücken aus dem neuen Werkstoff, wobei auf eine Figur und weiterhin eine Tabelle mit Einzelbeispielen für unterschiedliche Werkstoffzusammensetzungen Bezug genommen wird. Es zeigen die Figur ein typisches Gefügebild des neuen Werkstoffes und die Tabelle Meßwerte für die Lebensdauerschaltzahl und für die Übertemperatur.Further details and advantages of the invention result from the following description of the method for producing contact pieces from the new material, reference being made to a figure and also to a table with individual examples for different material compositions. The figure shows a typical microstructure of the new material and the table of measured values for the lifetime switching number and for the overtemperature.

Die Lebensdauerschaltzahl korrespondiert bekanntermaßen mit dem Volumenabbrand des Kontaktwerkstoffes und die Übertemperatur mit dem Kontaktwiderstand. Es sind vier Beispiele des Standes der Technik und fünf Ausführungsbeispiele der Erfindung gegenübergestellt.As is known, the lifetime switching number corresponds to the volume erosion of the contact material and the overtemperature corresponds to the contact resistance. Four examples of the prior art and five exemplary embodiments of the invention are compared.

Zur Herstellung der inneroxidierten Legierungspulver für die in der Tabelle angegebenen Beispiele werden Legierungen aus AgSnBiCu bei einer Temperatur von etwa 1323 K (1050°C) erschmolzen. Durch Zerstäuben der Schmelze mit Wasser in einer Druckverdüsungsanlage werden daraus gleich zusammengesetzte Legierungspulver erhalten. Nach dem Trocknen werden die Pulver auf < 300 µm abgesiebt. Dieser Anteil wird in sauerstoffhaltiger Atmosphäre bei Temperaturen zwischen 773 K (500°C) und 873 K (600°C) quantitativ inneroxidiert, wonach AgSnO₂Bi₂O₃CuO-Pulver folgender Zusammensetzung in Massenanteilen in Prozent erhalten werden:

Figure imgb0001
To produce the internally oxidized alloy powders for the examples given in the table, alloys made of AgSnBiCu are melted at a temperature of approximately 1323 K (1050 ° C.). Alloy powders of the same composition are obtained by atomizing the melt with water in a pressure atomization system. After drying, the powders are sieved to <300 µm. This portion is quantitatively internal oxidized in an oxygen-containing atmosphere at temperatures between 773 K (500 ° C) and 873 K (600 ° C), after which AgSnO₂Bi₂O₃CuO powder the following composition can be obtained in percentages by mass:
Figure imgb0001

Den angegebenen AgSnO₂Bi₂O₃CuO-Pulvern werden Pulver aus Wismutzirkonat (2Bi₂O₃.3ZrO₂) und/oder Wismuttitanat (Bi₂Ti₂O₇) durch Naßmischen in einer Rührwerkskugelmühle unter Verwendung von Propanol und Stahlkugeln zugesetzt. Nach dem Trocknen des Gemisches werden die Stahlkugeln von der jeweiligen Pulvermischung durch Absieben getrennt. Die Ausgangspulver für die Kontaktstückherstellung der in der Tabelle angegebenen Werkstoffbeispiele sind wie folgt zusammengesetzt:

Figure imgb0002
The specified AgSnO₂Bi₂O₃CuO powders are powdered from bismuth zirconate (2Bi₂O₃.3ZrO₂) and / or bismuth titanate (Bi₂Ti₂O₇) added by wet mixing in a stirred ball mill using propanol and steel balls. After the mixture has dried, the steel balls are separated from the respective powder mixture by sieving. The starting powders for the contact piece production of the material examples given in the table are composed as follows:
Figure imgb0002

Bei dieser Aufstellung bildet das inneroxidierte Legierungspulver die Basis mit 100 Massenanteilen in Prozent, zu denen die Zusatzoxide in Massenanteilen bezogen auf 100 % hinzugemischt werden. Bei der Herstellung der Kontaktstücke wird das erzeugte Ausgangspulvergemisch mit einem Preßdruck von z.B. 600 MPa verdichtet und werden die erhaltenen Preßkörper bei einer Temperatur zwischen 1123 K (850°C) und 1148 K (875°C) über 2 h an Luft gesintert. Zur Erzielung einer kleinen Restporosität werden die gesinterten Kontaktstücke bei einer Temperatur von 923 K (650°C) und einem Druck von z.B. 1000 MPa warm nachgepreßt. Eine weitere Verdichtung und Verfestigung wird durch eine zweite Sinterung bei einer Temperatur zwischen 1123 K (850°C) und 1148 K (875°C) während 2 h erreicht. Anschließend erfolgt als letzter Herstellschritt ein Kaltkalibrieren zur Endform bei einem Druck von z.B. 1000 MPa.In this list, the internally oxidized alloy powder forms the basis with 100 percent by mass, to which the additional oxides are added in percentages by mass. In the manufacture of the contact pieces, the starting powder mixture produced is compressed with a pressure of, for example, 600 MPa and the pressed bodies obtained are at a temperature between 1123 K (850 ° C.) and 1148 K (875 ° C.) sintered in air for 2 h. To achieve a small residual porosity, the sintered contact pieces are hot pressed at a temperature of 923 K (650 ° C) and a pressure of, for example, 1000 MPa. Further densification and solidification is achieved by a second sintering at a temperature between 1123 K (850 ° C) and 1148 K (875 ° C) for 2 hours. Then the last manufacturing step is a cold calibration to the final shape at a pressure of eg 1000 MPa.

Bei obigen Werkstoffen wird nach der Sinterung ein spezifisches Gefüge mit unterschiedlichen Oxidteilchengrößen und -formen sowie Oxidkonzentrationen erhalten, das in der Figur in Anlehnung an ein lichtmikroskopisches Gefügebild wiedergegeben ist. Erkennbar sind die ehemaligen Teilchen des inneroxidierten Legierungspulvers 1 mit Oxidfeinausscheidungen 2 und angelagerten gröberen Oxidausscheidungen 3. Durch die Umkörnung der Oxidausscheidungen an den Grenzen des inneroxidierten Legierungspulvers aus AgSnO₂Bi₂O₃CuO entsteht ein umschließendes, nahezu oxidfreies Silbernetzwerk 4, das eine hohe Sinterverdichtung bewirkt und die es aufgrund ihrer Duktilität erlaubt, einen nahezu porenfreien Kontaktwerkstoff durch Kaltverdichten herzustellen.In the above materials, a specific structure with different oxide particle sizes and shapes and oxide concentrations is obtained after sintering, which is shown in the figure based on a light microscopic micrograph. The former particles of the inner-oxidized alloy powder 1 with fine oxide precipitates 2 and coarser coarse oxide precipitates 3 are recognizable Ductility allows an almost non-porous contact material to be produced by cold compression.

Die Umkörnung, die durch die Sintertemperatur und Sinterdauer steuerbar ist, verläuft als Front ins Innere der AgSnO₂Bi₂O₃CuO-Pulverteilchen 1. In dieser Front besitzen die Oxidausscheidungen 2 eine längliche, zum Teil schlierenartige Form und sind hoch zirkonat- und/oder titanathaltig.The grain size, which can be controlled by the sintering temperature and duration, runs as a front inside the AgSnO₂Bi₂O₃CuO powder particles 1. In this front, the oxide precipitates 2 have an elongated, partly streak-like shape and are high in zirconate and / or titanium.

Überraschenderweise führt der Gefügeaufbau gemäß der Figur zu einer günstigen Beeinflussung der elektrischen Leitfähigkeit der sich bei Lichtbogeneinwirkung auf den Kontaktflächen ausbildenden Oxidschichten.Surprisingly, the structure of the structure according to the figure has a favorable influence on the electrical conductivity of the oxide layers which form on the contact surfaces when exposed to arcing.

Zur Verwendung als Kontaktstücke in Niederspannungsschaltgeräten der Energietechnik werden zweckmäßigerweise Zweischichten-Fertigformteile mit einer lötfähigen Reinsilberschicht gefertigt. Diese Formteile können unmittelbar auf die Kontaktträger beispielsweise von Motorschützen aufgelötet werden.For use as contact pieces in low-voltage switchgear In energy technology, two-layer finished molded parts are expediently manufactured with a solderable pure silver layer. These molded parts can be soldered directly onto the contact carrier, for example by motor contactors.

Mit nach obiger Vorschrift hergestellten Kontaktstücken wurden Lebensdauer- und Erwärmungsprüfungen in Motorschützen durchgeführt. Es wurden Siemens-Schütze mit einem AC-3-Nennbetriebsstrom von 250 A verwendet. Wesentliche Kenngrößen sind dabei die Lebensdauerschaltzahl bei 4-fachem AC-3-Nennbetriebsstrom (4 x Ie AC-3=1000 A) und die maximale Übertemperatur der Anschlußschienen des Schaltgerätes bei Dauerführung des AC-1-Nennbetriebsstromes von IeAC-1=300 A. Die Messungen der Übertemperatur wurden während der Lebensdauerprüfung bis zu einer Schaltzahl von 5.10⁴ durchgeführt. Die zugehörigen Meßwerte sind in der Tabelle angegeben.With contact pieces manufactured according to the above regulation, service life and heating tests were carried out in motor contactors. Siemens contactors with an AC-3 nominal operating current of 250 A were used. Significant parameters are the number of lifespan cycles with 4-fold AC-3 nominal operating current (4 x I e AC-3 = 1000 A) and the maximum overtemperature of the switching device's connecting rails when the AC-1 nominal operating current is kept at I eAC-1 = 300 A. The measurements of the overtemperature were carried out during the service life test up to a switching number of 5.10⁴. The associated measured values are given in the table.

Die vier Vergleichswerkstoffe des oben abgehandelten Standes der Technik, die durch Sinterung von inneroxidierten Legierungspulvern hergestellt wurden, sind eingangs aufgelistet. Die Meßwerte zeigen, daß bezüglich Übertemperatur Werkstoffe der Konstitution AgSnO₂Bi₂O₃CuO und AgSnO₂Bi₂O₃CuO + Bi₂O₃ Werte unterhalb von 80 K nicht erreichen, was in der Praxis in manchen Fällen als unbefriedigend angesehen wird.The four comparison materials of the prior art dealt with above, which were produced by sintering internally oxidized alloy powders, are listed at the beginning. The measured values show that materials of the constitution AgSnO₂Bi₂O₃CuO and AgSnO₂Bi₂O₃CuO + Bi₂O₃ do not reach values below 80 K, which in practice is considered unsatisfactory in some cases.

Hier ergeben nun die neuen Werkstoffe, die durch Sinterung eines inneroxidierten Legierungspulvers unter Zumischung von Wismutzirkonatpulver und/oder Wismuttitanatpulver hergestellt wurden, insbesondere bei einem Gesamtmassenanteil von etwa 12 % Oxid, die geforderte Verbesserung des Übertemperaturverhaltens. Es wurden Werte von 60 K bis 70 K gemessen, wobei die Lebensdauerschaltzahl auf dem gleichen hohen Niveau des Standes der Technik bleibt. Damit ist das Eigenschaftspektrum insgesamt verbessert, wobei sich in jedem Fall eine Silbereinsparung ergibt.

Figure imgb0003
Here, the new materials, which were produced by sintering an internally oxidized alloy powder with the addition of bismuth zirconate powder and / or bismuth titanate powder, in particular with a total mass fraction of about 12% oxide, result in the required improvement in the overtemperature behavior. Values from 60 K to 70 K were measured, the lifetime switching number remaining at the same high level of the prior art. The range of properties is thus improved overall, with silver being saved in every case.
Figure imgb0003

Claims (9)

  1. Sintered contact material for low voltage switchgear for power engineering, in particular for a motor contactor, containing silver (Ag), tin oxide (SnO₂), bismuth oxide (Bi₂O₃) and copper oxide (CuO) and produced from an internally oxidised alloy powder (IOAP) of a silver-tin-bismuth-copper starting alloy, the tin oxide content being from 4 to 12% by weight and the ratio of tin oxide to bismuth oxide on the one hand and of tin oxide to copper oxide on the other hand as weight percentages in the internally oxidised alloy powder being in each case between 8:1 and 12:1, characterised by bismuth zirconate (2Bi₂O₃.3ZrO₂) as a further metal oxide which is admixed with the internally oxidised alloy powder.
  2. Sintered contact material according to claim 1, characterised in that in addition bismuth titanate (Bi₂Ti₂O₇) is present.
  3. Sintered contact material according to claim 1 and claim 2, characterised in that the bismuth zirconate is present as a mixed oxide and the bismuth titanate as a stoichiometric compound.
  4. Sintered contact material according to claim 1 and claim 2, characterised in that the total amount of bismuth zirconate and bismuth titanate is between 0.1 and 5% by weight.
  5. Sintered contact material according to claim 3, characterised in that the total amount of bismuth zirconate and bismuth titanate is between 0.5 and 4% by weight.
  6. Sintered contact material according to claim 4, characterised in that the amount of bismuth zirconate is between 0.5 and 3% by weight.
  7. Sintered contact material according to claim 2, characterised in that the amount of bismuth titanate is between 0.1 and 2% by weight.
  8. Sintered contact material according to one of the preceding claims, characterised in that the total oxide content of oxides amounts to at most 20% by weight.
  9. Sintered contact material according to claim 6, characterised in that the amount of all oxides is about 12% by weight.
EP89120515A 1988-11-17 1989-11-06 Sintered contact material for low-tension switchgear, particularly for contactors Expired - Lifetime EP0369283B1 (en)

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DE3838950 1988-11-17
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DE4117311A1 (en) * 1991-05-27 1992-12-03 Siemens Ag CONTACT MATERIAL ON A SILVER BASE FOR USE IN SWITCHGEAR DEVICES IN ENERGY TECHNOLOGY
DE4201940A1 (en) * 1992-01-24 1993-07-29 Siemens Ag SINTER COMPOSITE FOR ELECTRICAL CONTACTS IN SWITCHGEAR OF ENERGY TECHNOLOGY
ATE136394T1 (en) * 1992-06-10 1996-04-15 Duerrwaechter E Dr Doduco MATERIAL FOR ELECTRICAL CONTACTS BASED ON SILVER-TIN OXIDE OR SILVER-ZINC OXIDE
US5822674A (en) * 1992-09-16 1998-10-13 Doduco Gmbh + Co. Dr. Eugen Durrwachter Electrical contact material and method of making the same
DE19503182C1 (en) * 1995-02-01 1996-05-15 Degussa Sintered material used as electrical contacts for switching amperage rating
US20090202855A1 (en) * 2008-01-09 2009-08-13 Saxton David M Porous sliding bearing and method of construction thereof
US8320089B1 (en) 2009-04-16 2012-11-27 Musco Corporation Apparatus, method, and system for integrating ground fault circuit interrupters in equipment-grounded high voltage systems
CN108772053B (en) * 2018-06-29 2020-12-15 辽宁石油化工大学 Bismuth titanate/bismuth oxide photocatalyst and preparation method and application thereof
CN113502414B (en) * 2021-06-10 2022-01-07 暨南大学 High-thermal-conductivity aviation aluminum alloy and application thereof in preparation of ultra-large-area LED light source radiator

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US4141727A (en) * 1976-12-03 1979-02-27 Matsushita Electric Industrial Co., Ltd. Electrical contact material and method of making the same
DE3232627A1 (en) * 1981-09-24 1983-04-07 Doduco KG Dr. Eugen Dürrwächter, 7530 Pforzheim Material for electrical contacts
DE3146972A1 (en) * 1981-11-26 1983-06-01 Siemens AG, 1000 Berlin und 8000 München METHOD FOR PRODUCING MOLDED PARTS FROM CADMIUM-FREE SILVER METAL OXIDE COMPOSITIONS FOR ELECTRICAL CONTACTS
DE3304637A1 (en) * 1983-02-10 1984-08-16 Siemens AG, 1000 Berlin und 8000 München SINTER CONTACT MATERIAL FOR LOW VOLTAGE SWITCHGEAR
EP0152606B1 (en) * 1984-01-30 1987-09-09 Siemens Aktiengesellschaft Contact material and production of electric contacts
DE3421758A1 (en) * 1984-06-12 1985-12-12 Siemens AG, 1000 Berlin und 8000 München SINTER CONTACT MATERIAL FOR LOW VOLTAGE SWITCHGEAR IN ENERGY TECHNOLOGY AND METHOD FOR THE PRODUCTION THEREOF
DE3421759A1 (en) * 1984-06-12 1985-12-12 Siemens AG, 1000 Berlin und 8000 München SINTER CONTACT MATERIAL FOR LOW VOLTAGE SWITCHGEAR OF ENERGY TECHNOLOGY

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JP2810162B2 (en) 1998-10-15
US4980125A (en) 1990-12-25
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EP0369283A2 (en) 1990-05-23
EP0369283A3 (en) 1991-03-13
BR8905828A (en) 1990-06-12

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