EP0099066A1 - Process for manufacturing a composite article from chromium and copper - Google Patents
Process for manufacturing a composite article from chromium and copper Download PDFInfo
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- EP0099066A1 EP0099066A1 EP83106620A EP83106620A EP0099066A1 EP 0099066 A1 EP0099066 A1 EP 0099066A1 EP 83106620 A EP83106620 A EP 83106620A EP 83106620 A EP83106620 A EP 83106620A EP 0099066 A1 EP0099066 A1 EP 0099066A1
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- powder
- copper
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- furnace temperature
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- Prior art date
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- 239000010949 copper Substances 0.000 title claims abstract description 39
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 30
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 27
- 239000011651 chromium Substances 0.000 title claims description 40
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims description 12
- 229910052804 chromium Inorganic materials 0.000 title claims description 11
- 239000002131 composite material Substances 0.000 title claims description 10
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 239000000843 powder Substances 0.000 claims abstract description 33
- 238000002844 melting Methods 0.000 claims abstract description 12
- 230000008018 melting Effects 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 6
- 239000010439 graphite Substances 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 4
- GNFTZDOKVXKIBK-UHFFFAOYSA-N 3-(2-methoxyethoxy)benzohydrazide Chemical compound COCCOC1=CC=CC(C(=O)NN)=C1 GNFTZDOKVXKIBK-UHFFFAOYSA-N 0.000 claims 1
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims 1
- 238000005470 impregnation Methods 0.000 description 12
- 239000011148 porous material Substances 0.000 description 10
- 238000005245 sintering Methods 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- 230000008595 infiltration Effects 0.000 description 4
- 238000001764 infiltration Methods 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910000967 As alloy Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000005247 gettering Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000004482 other powder Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000013354 porous framework Substances 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- 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
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
- B22F3/26—Impregnating
-
- 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
- H01H1/0206—Contacts characterised by the material thereof specially adapted for vacuum switches containing as major components Cu and Cr
Definitions
- the invention relates to a method for producing a composite material from chrome and copper as a contact material for medium-voltage vacuum circuit breakers.
- the composite material CrCu with about 40 to 60% Cr has already proven itself as a contact material for vacuum circuit breakers.
- the component Cu ensures sufficient electrical and thermal conductivity, while the framework material Cr both reduces burn-off and, with its low melting point of about 2173 K compared to tungsten, eliminates the risk of harmful thermal electron emission.
- the Cr greatly reduces the tendency of the contact pieces to weld and has good gettering properties.
- Porous blanks produced by pressing or pouring metal powder which either consist of pure Cr powder or in which one or more other powder additives are mixed with the Cr powder to achieve a liquid phase during sintering.
- the subsequent sintering in a high vacuum or pure protective gas at temperatures from 1573 K to 1773 K leads to a desired formation of sinter bridges between the powder grains, so that an increase in the framework strength takes place, which allows problem-free handling of the porous sintered blanks after the sintering process.
- the blanks are then placed in impregnation molds or placed on impregnation pads, receive an amount of impregnation metal, in this case copper, corresponding to the pore volume, and are in turn heated in a high vacuum or pure protective gas above the melting temperature of the impregnation metal.
- impregnation metal in this case copper
- the porous framework occurs due to capillary forces.
- the invention is therefore based on the object to develop a new method with which it is possible to produce a high-quality contact material made of chrome and copper, which meets the requirements of vacuum medium-voltage circuit breakers up to 36 kV operating voltage and breaking currents above 30 kA, and in which the aforementioned sources of error as well as the use of Cu powder with a high oxygen content are avoided.
- the object is achieved in that Cr-powder is poured into a ent q aste a shape that a piece of oxygen-poor copper is placed on the Cr-powder, in that subsequently the mold is closed with a porous cover, that then the Mold degassed in a high vacuum oven at room temperature until a pressure of better than 10 -4 mb is reached, then the furnace temperature is raised to a temperature as high as possible below the melting temperature of copper, that this furnace temperature is kept constant until a constant furnace pressure of better than 10 -4 mb is reached, and that the furnace temperature is then further increased without intermediate cooling to a final value of 100 K to 200 K above the melting temperature of the copper and this temperature is maintained until the porosity contained in the Cr powder mixture is completely filled by the liquid copper is.
- the furnace temperature just below the melting point of copper can be 1273 K ⁇ 20 K in a technical implementation. At this temperature, the furnace is kept constant for about an hour, an internal furnace pressure in the range of 10 -5 mb being preferably achieved.
- the holding time at the temperature above the melting point of copper is preferably 20 to 30 minutes.
- the Cr powder should have a particle size distribution of 50 ⁇ m to 200 ⁇ m, but preferably in proportions of at least 150 ⁇ m; in the second case the particle size can be below this, in the range from 25 ⁇ m.
- electrolytically produced chromium which also has a maximum oxygen content of 500 ppm.
- the Cr powder produced from this can have a particle size distribution which is smaller than in the case of chromium produced thermally, for example with particle sizes from 25 pm. Otherwise, the individual sub-process steps are carried out according to the first example.
- the blank produced according to the above examples is cooled under vacuum. After cooling, the Cr-Cu composite block can be broken down into contact pieces of the required geometry. If metallographic cuts of the material are produced, it can be seen that the composite material produced with the method according to the invention has practically no strength-increasing sintered bridges and practically no pores. With the new process, contact pieces can be reproducibly produced on Cr-Cu basis, which have suitable properties for medium-voltage vacuum circuit-breakers.
- titanium and zirconium as alloy components for copper can improve the getter properties; on the other hand, iron, cobalt or Nickel can be added to the Cr powder in order to improve the wetting properties.
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Powder Metallurgy (AREA)
- High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
Abstract
Beim Verfahren gemäß der Erfindung wird Cr-Pulver in eine entqaste Arbeitsform, insbesondere aus Graphit, geschüttet., Auf dieses Cr-Pulver wird ein Stück aus sauerstoffarmem Kupfer gelegt. Anschließend wird die Arbeitsform met einem porösen Deckel, insbesondere aus Graphit, verschlossen. Die Arbeitsform wird dann in einem Hochvakuumofen bei Raumtemperatur solange entgast, bis ein Druck von besser als 10-4 mb erreicht ist. Danach wird die Ofentemperatur auf eine möglichst hohe Temperatur unterhalb des Schmelzpunktes von Kupfer erhöht. Diese Ofentemperatur wird solange konstant gehalten, bis ein Ofeninnendruck von besser als 10-4 mb erreicht ist. Anschließend wird ohne Zwischenabkühlen die Ofentemperatur weiter langsam erhöht bis zu einem Endwert von 100 K bis 200 K oberhalb der Schmelztemperatur des Kupfers und diese Temperatur solange beibehalten, bis die in der Cr-Pulverschüttung enthaltene Porosität vollständig vom flüssigen Kupfer ausgefüllt ist.In the method according to the invention, Cr powder is poured into a degassed working mold, in particular made of graphite. A piece of oxygen-poor copper is placed on this Cr powder. The working mold is then closed with a porous cover, in particular made of graphite. The working form is then degassed in a high vacuum oven at room temperature until a pressure of better than 10 -4 mb is reached. The furnace temperature is then raised to a temperature as high as possible below the melting point of copper. This furnace temperature is kept constant until an internal furnace pressure of better than 10- 4 mb is reached. The furnace temperature is then slowly increased without intermediate cooling to a final value of 100 K to 200 K above the melting temperature of the copper and this temperature is maintained until the porosity contained in the Cr powder fill is completely filled by the liquid copper.
Description
Die Erfindung bezieht sich auf ein Verfahren zum Herstellen eines Verbundwerkstoffes aus Chrom und Kupfer als Kontaktwerkstoff für Mittelspannungs-Vakuum-Leistungsschälter.The invention relates to a method for producing a composite material from chrome and copper as a contact material for medium-voltage vacuum circuit breakers.
Als Kontaktmaterial für Vakuum-Leistungsschalter hat sich bereits der Verbundwerkstoff CrCu mit etwa 40 bis 60 % Cr gut bewährt. Dabei gewährleistet die Komponente Cu eine hinreichende elektrische und thermische Leitfähigkeit, während das Gerüstmaterial Cr sowohl abbrandmindernd als auch mit seinem im Vergleich zu Wolfram niedrigen Schmelzpunkt von etwa 2173 K die Gefahr einer schädlichen thermischen Elektronenemission beseitigt. Außerdem setzt das Cr die Verschweißneigung der Kontaktstücke stark herab und besitzt gute Gettereigenschaften.The composite material CrCu with about 40 to 60% Cr has already proven itself as a contact material for vacuum circuit breakers. The component Cu ensures sufficient electrical and thermal conductivity, while the framework material Cr both reduces burn-off and, with its low melting point of about 2173 K compared to tungsten, eliminates the risk of harmful thermal electron emission. In addition, the Cr greatly reduces the tendency of the contact pieces to weld and has good gettering properties.
Für die Herstellung des Verbundwerkstoffes CrCu kommen aufgrund der Mischungslücke im System Cr-Cu für den gewünschten Konzentrationsbereich von etwa 40 bis 60 % Cr-Gehalt nur pulvermetallurgische Verfahren in Betracht. Am gebräuchlichsten ist das Herstellen von Preßkörpern aus Cr-Pulver oder CrCu-Pulvermischunqen, deren Poren nach der Sinterung mit flüssigem Cu aufgefüllt werden. Derartige Sintertränkverfahren sowie auch die übrigen bekannten pulvermetallurgischen Verfahren sind wegen der Oxidationsneiqung des Chroms schwierig zu beherrschen. Insbesondere besteht die Gefahr, durch schlechte Benetzbarkeit einzelner Kornflächen oder Passivschichtbildung Poren- oder Tränkfehler zu erhalten. Auch wenn diese nur in der Größenordnung von 5 bis 50 um liegen, kann durch sie eine Beeinträchtigung des Schaltverhaltens bewirkt werden. In der Praxis ergibt sich daraus eine gewisse Streubreite im Ausschaltvermögen.For the production of the composite material CrCu, only powder metallurgical processes can be considered due to the mixture gap in the Cr-Cu system for the desired concentration range of approximately 40 to 60% Cr content. The most common is the production of compacts from Cr powder or CrCu powder mixtures, the pores of which are filled with liquid Cu after sintering. Such sintering impregnation processes and also the other known powder metallurgy processes are difficult to master because of the oxidation tendency of the chromium. In particular, there is a risk of poor wettability of individual grain surfaces or passive layer formation to obtain pore or watering defects. Even if they are only in the order of 5 to 50 μm, they can have an adverse effect on the switching behavior. In practice, this results in a certain spread in the breaking capacity.
Bei anderen bekannten Verfahren werden z.B. poröse Rohlinge durch Pressen oder Schütten von Metallpulver hergestellt, die entweder aus reinem Cr-Pulver bestehen oder bei denen zum Erzielen einer flüssigen Phase beim Sintern ein oder mehrere weitere Pulverzusätze dem Cr-Pulver zugemischt werden. Das anschließende Sintern im Hochvakuum oder reinem Schutzgas bei Temperaturen von 1573 K bis 1773 K führt zu einer gewünschten Ausbildung von Sinterbrücken zwischen den Pulverkörnern, so daß ein Anstieg der Gerüstfestigkeit erfolgt, der eine problemlose Handhabung der porösen-Sinterrohlinge nach dem Sinterprozeß erlaubt. In einem weiteren Arbeitsganq werden die Rohlinge dann in Tränkformen eingelegt oder auf Tränkunterlagen aufgelegt, erhalten als Auf- oder Unterlage eine dem Porenvolumen entsprechende Menge an Tränkmetall, in diesem Fall Kupfer, und werden wiederum im Hochvakuum oder reinem Schutzgas über die Schmelztemperatur des Tränkmetalls erhitzt. Hierbei tritt durch Kapillarkräfte eine Infiltration des porösen Gerüstes ein.In other known methods e.g. Porous blanks produced by pressing or pouring metal powder, which either consist of pure Cr powder or in which one or more other powder additives are mixed with the Cr powder to achieve a liquid phase during sintering. The subsequent sintering in a high vacuum or pure protective gas at temperatures from 1573 K to 1773 K leads to a desired formation of sinter bridges between the powder grains, so that an increase in the framework strength takes place, which allows problem-free handling of the porous sintered blanks after the sintering process. In a further work process, the blanks are then placed in impregnation molds or placed on impregnation pads, receive an amount of impregnation metal, in this case copper, corresponding to the pore volume, and are in turn heated in a high vacuum or pure protective gas above the melting temperature of the impregnation metal. In this case, infiltration of the porous framework occurs due to capillary forces.
Mit den vorstehend beschriebenen Tränkverfahren zur Herstellung der Cr-Cu-Verbundwerkstoffe lassen sich jedoch trotz sorgfältigster Arbeitsweise keine völlig fehlerfreien Tränkungen erzielen: Dafür sind im wesentlichen drei Gründe verantwortlich:
- Beim Umchargieren der Öfen zwischen Sinter- und Tränkprozeß kommt es bei den stark getteraktiven Cr-Gerüsten zu einer Neubelegung der Gerüstoberfläche mit dünnen Oxid- bzw. chemiesorbierten Gashäuten, die die Benetzunq mit dem flüssigen Tränkmetall erschweren. Aus thermodynamischen Gründen treten diese Oxidationsprozesse bereits unterhalb von etwa 1000 K selbst im Hochvakuum und in reinem Schutzgas auf, da sich in wirtschaftlich anwendbaren Öfen keine Sauerstoff - partialdrücke unter 10-10 mb erzielen lassen. Als Resultat dieser Erscheinung treten Tränkfehler auf, die sich in Form von Mikrolunkern und Poren äußern.
- When the furnaces are re-charged between the sintering and impregnation processes, the heavily getter-active Cr frameworks are reloaded with thin oxide or chemically sorbed gas skins, which make it difficult to wet them with the liquid impregnation metal. For thermodynamic reasons, these oxidation processes already occur below around 1000 K even in a high vacuum and in a pure protective gas, since no oxygen partial pressures below 10- 10 mb can be achieved in economically applicable furnaces. As a result of this phenomenon, impregnation errors occur, which are expressed in the form of microholes and pores.
Durch den Sinterprozeß und die damit verbundene Ausbildung von Sinterbrücken werden schlecht zugängliche Porenbereiche erhalten, die von flüssigem Tränkmetall gar nicht oder nur unvollkommen erreicht werden. Damit ist auch die Möglichkeit, reduzierende Substanzen wie z.B. Kohlenstoff über die flüssige Tränkmetallphase an das Gerüstmetall zu brinqen, eingeschränkt, so daß in diesen Restporenbereichen, die von der Sinterbrückenbildung herrühren, Restoxide vorhanden sind, die das Schaltvermögen des Werkstoffes beeinträchtigen.Due to the sintering process and the associated formation of sintered bridges, poorly accessible pore areas are obtained which are not or only incompletely reached by liquid impregnation metal. This also makes it possible to use reducing substances such as Bringing carbon to the scaffold metal via the liquid impregnation metal phase is restricted, so that residual oxides are present in these residual pore areas, which result from the formation of the sintered bridge, which impair the switching capacity of the material.
Durch die versteifende Wirkung fester Sinterbrücken wird die Möglichkeit des Gerüstmaterials zur Deformation beträchtlich verringert. Wird das mit Cu oder Legierungen davon imprägnierte Cr-Gerüst von der Infiltrationstemperatur des flüssigen Tränkmetalls abgekühlt, so tritt wegen der unterschiedlichen Wärmeausdehnungen zwischen Cr und Cu ein Volumendefizit auf, das durch einen gemeinsamen gleichmäßigen Schrumpf von Gerüst- und Tränkmetall nicht aufqefangen werden kann. Diese bekannte Erscheinung kann ebenfalls zu Fehlstellen und im Lichtmikroskop unsichtbaren Mikroporositäten führen, die die Qualität des Werkstoffes für Hochleistungsschaltaufgaben verschlechtern können.The stiffening effect of solid sintered bridges considerably reduces the possibility of the framework material for deformation. If the thereof impregnated with Cu or alloys Cr skeleton cooled from the infiltration temperature of the liquid infiltration metal, a volume deficit occurs due to different thermal expansions between Cr and Cu, which can not be efangen by a common uniform shrinkage of scaffolding and infiltration metal on q . This known phenomenon can also lead to imperfections and microporosities which are invisible in the light microscope and which can deteriorate the quality of the material for high-performance switching tasks.
Es ist versucht worden, diese Störungen zu vermeiden. So kann z.B. Cr-Pulver und Cu-Pulver gemischt werden, dadurch unterbleibt eine direkte Berührung der Cr-Körner weitgehend und es bilden sich im anschließenden Sinterprozeß keine oder nur vereinzelte deformationsbehindernde Sinterbrücken aus. Obwohl dieser Fertigungsprozeß die sterische Behinderung der Cr-Partikel aufhebt, kann mit einem derartigen Werkstoff keine ausreichende Schaltleistung erzielt werden. Ursache dafür ist die Wechselwirkung zwischen dem üblicherweise mit etwa 500 ppm sauerstoffverunreinigtem Cu-Pulver und dem getteraktiven Cr-Pulver. Bereits unterhalb 1273 K, d.h. also 1000°C, wird dabei bei einsetzender Cu20-Dissoziation das oxidationsfreudige Cr-Pulver aufoxidiert. Wegen der hohen Oxidationswärme des Cr kommt es zur Ausbildung stabiler Oberflächenoxide, die durch eine normale Vakuumentgasung Dicht mehr entfernt werden können.Attempts have been made to avoid these disturbances. For example, Cr powder and Cu powder are mixed, this largely prevents direct contact of the Cr grains and no or only a few deformation-preventing sinter bridges form in the subsequent sintering process. Although this manufacturing process eliminates the steric hindrance of the Cr particles, a sufficient switching capacity cannot be achieved with such a material. The reason for this is the interaction between the Cu powder, which is usually contaminated with about 500 ppm of oxygen, and the getter-active Cr powder. Already below 1273 K, i.e. 1000 ° C, the oxidizing Cr powder is oxidized when Cu20 dissociation begins. Due to the high heat of oxidation of the Cr, stable surface oxides are formed, which can be removed more tightly by normal vacuum degassing.
Der Erfindung liegt daher die Aufgabe zugrunde, ein neues Verfahren zu entwickeln, mit dem es möglich ist, einen hochwertigen Kontaktwerkstoff aus Chrom und Kupfer herzustellen, der den Anforderungen von Vakuum-Mittelspannungs-Leistungsschaltern bis 36 kV Betriebsspannung und Ausschaltströmen oberhalb 30 kA genügt, und bei dem die vorerwähnten Fehlerquellen sowie zusätzlich die Verwendung von Cu-Pulver mit hohem Sauerstoffgehalt vermieden werden.The invention is therefore based on the object to develop a new method with which it is possible to produce a high-quality contact material made of chrome and copper, which meets the requirements of vacuum medium-voltage circuit breakers up to 36 kV operating voltage and breaking currents above 30 kA, and in which the aforementioned sources of error as well as the use of Cu powder with a high oxygen content are avoided.
Gemäß der Erfindung wird die Aufgabe dadurch gelöst, daß Cr-Pulver in eine entqaste Form geschüttet wird, daß auf das Cr-Pulver ein Stück aus sauerstoffarmen Kupfer gelegt wird, daß anschließend die Form mit einem porösen Deckel verschlossen wird, daß dann die Form in einem Hochvakuumofen bei Raumtemperatur entgast wird, bis ein Druck von besser als 10-4 mb erreicht ist, daß danach die Ofentemperatur auf eine möglichst hohe Temperatur unterhalb der Schmelztemperatur von Kupfer erhöht wird, daß diese Ofentemperatur solange konstant gehalten wird, bis ein konstanter Ofeninnendruck von besser als 10-4mb erreicht ist, und daß anschließend ohne Zwischenabkühlen die Ofentemperatur weiter erhöht wird bis zu einem Endwert von 100 K bis 200 K oberhalb der Schmelztemperatur des Kupfers und diese Temperatur solange beibehalten wird, bis die in der Cr-Pulvermischung enthaltene Porosität vollständig vom flüssigen Kupfer ausgefüllt ist.According to the invention the object is achieved in that Cr-powder is poured into a ent q aste a shape that a piece of oxygen-poor copper is placed on the Cr-powder, in that subsequently the mold is closed with a porous cover, that then the Mold degassed in a high vacuum oven at room temperature until a pressure of better than 10 -4 mb is reached, then the furnace temperature is raised to a temperature as high as possible below the melting temperature of copper, that this furnace temperature is kept constant until a constant furnace pressure of better than 10 -4 mb is reached, and that the furnace temperature is then further increased without intermediate cooling to a final value of 100 K to 200 K above the melting temperature of the copper and this temperature is maintained until the porosity contained in the Cr powder mixture is completely filled by the liquid copper is.
Die Ofentemperatur dicht unterhalb des Schmelzpunktes von Kupfer kann bei einer technischen Durchführung bei 1273 K {± 20 K liegen. Bei dieser Temperatur wird der Ofen etwa eine Stunde konstant gehalten, wobei vorzugsweise ein Ofeninnendruck im Bereich von 10-5 mb erreicht wird. Die Haltezeit bei der Temperatur oberhalb des Schmelzpunktes von Kupfer liegt vorzugsweise bei 20 bis 30 Minuten.The furnace temperature just below the melting point of copper can be 1273 K {± 20 K in a technical implementation. At this temperature, the furnace is kept constant for about an hour, an internal furnace pressure in the range of 10 -5 mb being preferably achieved. The holding time at the temperature above the melting point of copper is preferably 20 to 30 minutes.
Für das erfindungsgemäße Verfahren kann aluminothermisch oder elektrolytisch hergestelltes Chrom verwendet werden. Im ersten Fall sollte das Cr-Pulver eine Teilchengrößenverteilung von 50 um bis 200 um haben, vorzugsweise aber mit Anteilen von mindestens 150 um; im zweiten Fall kann die Teilchengröße darunter und zwar im Bereich ab 25 µm liegen.Chromothermally or electrolytically produced chromium can be used for the process according to the invention. In the first case, the Cr powder should have a particle size distribution of 50 µm to 200 µm, but preferably in proportions of at least 150 µm; in the second case the particle size can be below this, in the range from 25 µm.
Weiterhin hat es sich als zweckmäßig erwiesen, eine Arbeitsform aus Graphit zu verwenden, weil Kohlenstoff im flüssigen Kupfer in geringer Menge löslich ist und daher über einen Transport in der flüssigen Phase als Reduktionsmittel für Cr-Oxidverunreinigungen Anwendung findet.Furthermore, it has proven to be expedient to use a working form made of graphite, because carbon is soluble in the liquid copper in a small amount and is therefore used as a reducing agent for Cr oxide impurities via transport in the liquid phase.
Besonders vorteilhaft bei der Erfindung ist, daß kein festigkeitssteigernder Sinterprozeß mit Ausbildung von stabilen Sinterbrücken durchgeführt, sondern daß unmittelbar von der in einer Form befindlichen Cr-Pulverschüttung ausgegangen wird. Ohne Umchargieren des Ofens und zusätzliche Handhabung von Sinterrohlingen kann das Porenvolumen der Pulverschüttung vollständig mit flüssigem Kupfer aufgefüllt werden, so daß sich ein praktisch porenfreier Verbundwerkstoff ergibt.It is particularly advantageous in the invention that no strength-increasing sintering process with the formation of stable sintering bridges is carried out, but that the Cr powder fill located in a mold is used directly. Without recharging the furnace and additional handling of sintered blanks, the pore volume of the powder filling can be completely filled with liquid copper, so that a practically non-porous composite material results.
Anhand nachfolgender Ausführunqsbeispiele wird die Erfindung im einzelnen beschrieben:
- Bei Verwendung von aluminothermisch hergestelltem Chrom mit einem maximalen Sauerstoffgehalt von 500 ppm wird das daraus erzeugte Cr-Pulver mit einer Teilchengröße mit Anteilen von mindestens 150 um in eine vorher entgaste Graphitform eingefüllt. Der Tiegel besitzt z.B. einen Durchmesser von 85 mm und eine Länge von 250 mm und wird bis zu einer Höhe von etwa 180 mm mit Cr-Pulver gefüllt. Auf das Cr-Pulver wird sauerstoffarmes Kupfer als massives Stück aufgelegt, das den restlichen Tiegelinhalt füllt. Der Tiegel wird mit einem porösen Graphitdeckel verschlossen und im Hochvakuumofen zunächst solange bei Raumtemperatur entgast, bis ein Druck im Bereich von 10-5 mb, also besser als 10-4 mb erreicht ist. Anschließend wird mit dem Aufheizen begonnen, das immer dann unterbrochen wird, wenn der Druck auf über 10-4 mb ansteiqt. Bei einer Temperatur von etwa 1273 K
- When using aluminothermally produced chromium with a maximum oxygen content of 500 ppm, the Cr powder produced therefrom is filled into a previously degassed graphite mold with a particle size of at least 150 μm. The crucible, for example, has a diameter of 85 mm and a length of 250 mm and is filled with Cr powder up to a height of approximately 180 mm. Oxygen-poor copper is placed on the Cr powder as a solid piece that fills the remaining crucible contents. The crucible is closed with a porous graphite cover and degassed in a high vacuum oven at room temperature until a pressure in the range of 10 -5 mb, better than 10 -4 mb, is reached. The heating is then started, which is interrupted whenever the pressure rises to over 10 -4 mb. At a temperature of around 1273 K.
Bei einem anderen Ausführungsbeispiel wird elektrolytisch hergestelltes Chrom verwendet, das einen maximalen Sauerstoffgehalt von ebenfalls 500 ppm hat. Das daraus erzeugte Cr-Pulver kann aber in diesem Fall eine Teilchengrößenverteilung haben, die kleiner als bei aluminothermisch hergestelltem Chrom ist, beispielsweise mit Teilchengrößen ab 25 pm. Ansonsten werden die einzelnen Verfahrensteilschritte entsprechend dem ersten Beispiel durchgeführt.In another embodiment, electrolytically produced chromium is used, which also has a maximum oxygen content of 500 ppm. In this case, however, the Cr powder produced from this can have a particle size distribution which is smaller than in the case of chromium produced thermally, for example with particle sizes from 25 pm. Otherwise, the individual sub-process steps are carried out according to the first example.
Nach vollständiger Porenfül'lung wird der gemäß obigen Beispielen hergestellte Rohling unter Vakuum abgekühlt. Nach dem Erkalten kann der Cr-Cu-Verbundblock in Kontaktstücke der erforderlichen Geometrie zerlegt werden. Werden metallographische Anschliffe des Werkstoffes hergestellt, so ist erkennbar, daß der mit dem erfindungsgemäßen Verfahren hergestellte Verbundwerkstoff praktisch keine festigkeitssteigernden Sinterbrücken und praktisch keine Poren aufweist. Mit dem neuen Verfahren können somit reproduzierbar auf Cr-Cu- Basis Kontaktstücke erzeugt werden, welche geeignete Eigenschaften für Mittelspannungs-Vakuum-Leistungsschalter haben.After the pores have been completely filled, the blank produced according to the above examples is cooled under vacuum. After cooling, the Cr-Cu composite block can be broken down into contact pieces of the required geometry. If metallographic cuts of the material are produced, it can be seen that the composite material produced with the method according to the invention has practically no strength-increasing sintered bridges and practically no pores. With the new process, contact pieces can be reproducibly produced on Cr-Cu basis, which have suitable properties for medium-voltage vacuum circuit-breakers.
Bei dem auf Cr-Cu-Basis beschriebenen Ausführungsbeispielen sind in an sich bekannter Weise weitere Elemente als Zusätze verwendbar: Beispielsweise können einerseits durch Titan und Zirkon als Legierungsbestandteile zum Kupfer die Gettereigenschaften verbessert werden; andererseits können Eisen, Kobalt oder Nickel dem Cr-Pulver zugesetzt werden, um dadurch die Benetzunqseigenschaften zu verbessern.In the exemplary embodiments described on the basis of Cr-Cu, further elements can be used as additives in a manner known per se: on the one hand, titanium and zirconium as alloy components for copper can improve the getter properties; on the other hand, iron, cobalt or Nickel can be added to the Cr powder in order to improve the wetting properties.
Die Handhabung der genannten Zusätze bei Cr-Cu-Verbundwerkstoffen ist im Zusammenhang mit der Erfindunq beherrschbar und ändert nichts Grundsätzliches am beschriebenen Herstellungsverfahren.The handling of the additives mentioned for Cr-Cu composites is manageable in connection with the invention and does not change anything fundamental in the production process described.
Claims (9)
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3226604 | 1982-07-16 | ||
| DE19823226604 DE3226604A1 (en) | 1982-07-16 | 1982-07-16 | Process for the preparation of a composite material based on Cr/Cu for medium-voltage vacuum power switches |
| DE3322866 | 1983-06-24 | ||
| DE19833322866 DE3322866A1 (en) | 1983-06-24 | 1983-06-24 | Process for the production of a composite material of chromium and copper |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0099066A1 true EP0099066A1 (en) | 1984-01-25 |
| EP0099066B1 EP0099066B1 (en) | 1986-05-07 |
| EP0099066B2 EP0099066B2 (en) | 1992-07-22 |
Family
ID=25803079
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP83106620A Expired - Lifetime EP0099066B2 (en) | 1982-07-16 | 1983-07-06 | Process for manufacturing a composite article from chromium and copper |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4503010A (en) |
| EP (1) | EP0099066B2 (en) |
| DE (1) | DE3363383D1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0231767A1 (en) * | 1986-01-10 | 1987-08-12 | Mitsubishi Denki Kabushiki Kaisha | Contact material for vacuum circuit breaker |
| GB2249318B (en) * | 1990-10-22 | 1994-06-15 | Raybestos Prod Co | Metallic friction facing material and its production |
| WO1997014163A1 (en) * | 1995-10-10 | 1997-04-17 | Abb Patent Gmbh | Process and device for making a contact |
| EP0903760A3 (en) * | 1997-09-01 | 1999-09-15 | Kabushiki Kaisha Toshiba | Vacuum valve |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0760623B2 (en) * | 1986-01-21 | 1995-06-28 | 株式会社東芝 | Contact alloy for vacuum valve |
| JP2640142B2 (en) * | 1989-06-05 | 1997-08-13 | 三菱電機株式会社 | Contact material for vacuum switch tube and its manufacturing method |
| SE9100396D0 (en) * | 1991-02-08 | 1991-02-08 | Sandvik Ab | SET FOR PREPARATION OF A COMPONENT BODY |
| US5701993A (en) * | 1994-06-10 | 1997-12-30 | Eaton Corporation | Porosity-free electrical contact material, pressure cast method and apparatus |
| US7832857B2 (en) * | 2008-08-18 | 2010-11-16 | Levinson Dennis J | Microbial cellulose contact lens |
| AT11814U1 (en) * | 2010-08-03 | 2011-05-15 | Plansee Powertech Ag | METHOD FOR THE POWDER METALLURGIC MANUFACTURE OF A CU-CR MATERIAL |
| RU2751861C1 (en) * | 2020-12-22 | 2021-07-19 | Федеральное государственное бюджетное образовательное учреж-дение высшего образования "Волгоградский государственный технический университет" (ВолгГТУ) | Method for obtaining carbon-graphite composite material |
| RU2751865C1 (en) * | 2020-12-22 | 2021-07-19 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Волгоградский государственный технический университет" (ВолгГТУ) | Method for obtaining carbon-graphite composite material |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1513972A (en) * | 1966-03-11 | 1968-02-16 | Mallory Metallurg Prod Ltd | Powder metallurgy improvements |
| FR2251898A1 (en) * | 1973-11-16 | 1975-06-13 | Siemens Ag | |
| DE2521504A1 (en) * | 1974-05-23 | 1975-12-04 | English Electric Co Ltd | PROCESS FOR PRODUCING AN ELECTRODE FOR VACUUM SWITCH OR VACUUM SPARK GANG |
| GB2024258A (en) * | 1978-05-31 | 1980-01-09 | Mitsubishi Electric Corp | Contact for vacuum interrupter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1194674A (en) * | 1966-05-27 | 1970-06-10 | English Electric Co Ltd | Vacuum Type Electric Circuit Interrupting Devices |
| DE2240493C3 (en) * | 1972-08-17 | 1978-04-27 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Penetration composite metal as a contact material for vacuum switches and process for its manufacture |
| DE2619459C3 (en) * | 1976-05-03 | 1978-11-09 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Sintered composite material as a contact material for vacuum medium-voltage circuit breakers |
-
1983
- 1983-07-06 EP EP83106620A patent/EP0099066B2/en not_active Expired - Lifetime
- 1983-07-06 DE DE8383106620T patent/DE3363383D1/en not_active Expired
- 1983-07-13 US US06/513,479 patent/US4503010A/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1513972A (en) * | 1966-03-11 | 1968-02-16 | Mallory Metallurg Prod Ltd | Powder metallurgy improvements |
| FR2251898A1 (en) * | 1973-11-16 | 1975-06-13 | Siemens Ag | |
| DE2521504A1 (en) * | 1974-05-23 | 1975-12-04 | English Electric Co Ltd | PROCESS FOR PRODUCING AN ELECTRODE FOR VACUUM SWITCH OR VACUUM SPARK GANG |
| GB2024258A (en) * | 1978-05-31 | 1980-01-09 | Mitsubishi Electric Corp | Contact for vacuum interrupter |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0231767A1 (en) * | 1986-01-10 | 1987-08-12 | Mitsubishi Denki Kabushiki Kaisha | Contact material for vacuum circuit breaker |
| GB2249318B (en) * | 1990-10-22 | 1994-06-15 | Raybestos Prod Co | Metallic friction facing material and its production |
| WO1997014163A1 (en) * | 1995-10-10 | 1997-04-17 | Abb Patent Gmbh | Process and device for making a contact |
| CN1070635C (en) * | 1995-10-10 | 2001-09-05 | Abb·专利有限公司 | Method and device for manufacturing contacts |
| EP0903760A3 (en) * | 1997-09-01 | 1999-09-15 | Kabushiki Kaisha Toshiba | Vacuum valve |
| US6107582A (en) * | 1997-09-01 | 2000-08-22 | Kabushiki Kaisha Toshiba | Vacuum valve |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3363383D1 (en) | 1986-06-12 |
| US4503010A (en) | 1985-03-05 |
| EP0099066B2 (en) | 1992-07-22 |
| EP0099066B1 (en) | 1986-05-07 |
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