DE102020113766A1 - Silver tungsten carbide contact material and manufacturing process therefor - Google Patents

Abstract

A method of manufacturing the silver-tungsten carbide contact material, comprising the steps of: S1: uniformly mixing silver nitrate solution, polyethylene glycol, sodium hydroxide solution and dextrose solution and performing a reduction reaction under ultrasonic vibration and stirring conditions to precipitate silver and add it outside of the tungsten carbide powder envelop, thereby forming a composite powder of the tungsten carbide enveloped by the silver; S2: Mixing the composite powder of the tungsten carbide enveloped by the silver with the silver powder and pressing to form a compact; S3: Place the compact and silver block produced in S2 in a sintering furnace protected by the ammonia decomposition atmosphere, and carry out sintering and infiltration to obtain a silver-tungsten carbide contact material. The present invention further discloses a silver-tungsten carbide contact material produced by the above production method. The silver-tungsten carbide contact material produced by the present invention is a high-density infiltrating silver-tungsten carbide material, the mass ratio of tungsten carbide being 40% -90%.

Description

TECHNICAL AREA

The present invention relates to the technical field of contact material, in particular a silver-tungsten carbide contact material and a production method therefor.

STATE OF THE ART

With the increasing demands of the power distribution end of the power grid on the reliability of the electrical appliance, the manufacturers of electrical appliances are constantly developing low voltage power distribution products with higher disconnection indicators. Some electronic circuit breakers can already reach the limit separation indicator of 150kA. Improving the disconnection indicator of an electrical appliance means that the thermal entry force of the arc when it is disconnected is extremely high, at which point the contact material is extremely prone to being eroded by the arc, causing the electrical appliance to fail to turn on and a failure to occur.

Considering the properties of materials such as conductivity and corrosion resistance, a silver-tungsten carbide (AgWC) material is currently the most widely used material for high-index, low-voltage circuit breakers. On the one hand, the material comprises tungsten carbide particles dispersed in micrometer size and used as a reinforcing phase, thereby the ability of the material to be arc erosion resistant can be greatly improved; On the other hand, a powder metallurgical process and a liquid phase sintering (infiltration) process are used for the material in order to ensure good wetting of the silver and tungsten carbide particles, so that the material is prevented from splashing under the effect of the arc at high temperatures.

In order to improve the arc resistance of the silver-tungsten carbide material, it is customary to reduce the particle size of tungsten carbide in the material and to increase the content of tungsten carbide. In the case of the silver-tungsten carbide materials used for a large melting furnace and other special devices, the mass percentage of tungsten carbide is even to be increased to 60% and even more than 60%, while the average particle size of tungsten carbide is to be reduced to below 1 micron, which is a has very high demands on the manufacturing process of the material.

If the content of tungsten carbide in the silver-tungsten carbide powders is too high and the tungsten carbide particle size is too small, there is an extremely large tungsten carbide particle surface area in the mixed powders, whereby a situation inevitably occurs in the powder molding process that a large amount of tungsten carbide particles occurs adjoins each other. Due to an extremely high hardness, almost no plastic deformation will occur when the surfaces of the tungsten carbide particles come into contact and press each other, therefore the particles cannot interlock, making the compact extremely prone to cracking, even the compact cannot be molded .

Because of this, it is always a difficult problem in industry to manufacture a silver-tungsten carbide material with a high content of tungsten carbide. To a fairly high degree, further improvement in the separation performance of the electrical appliance is limited by the problem.

With the conventional coating process, an agglomeration of tungsten carbide particles cannot be avoided in the process of the chemical reaction, the silver generated by the reaction will not envelop the individual tungsten carbide particles, but rather envelop an agglomerate of several tungsten carbide particles, which is why there is direct contact between the coating powders a large amount of tungsten carbide particles, the formability of the powders being relatively poor.

CONTENT OF THE PRESENT INVENTION

The present invention aims to provide a silver-tungsten carbide contact material and a manufacturing method therefor, in view of the deficiencies in the prior art. Thereby, the density of the silver-tungsten carbide contact material can be effectively improved.

• S1: Gleichmäßiges Vermischen von Silbernitratlösung, Polyethylenglykol, Natriumhydroxidlösung (Natriumhydroxid Lösung) und Dextrose-Lösung und Durchführen einer Reduktionsreaktion unter Ultraschallschwingungs- und Rührbedingungen, um Silber auszufällen und dieses außerhalb des Wolframkarbid-Pulvers zu umhüllen, wodurch ein Verbundpulver des durch das Silber umhüllten Wolframkarbides gebildet wird; wobei die Dosierung der Silbernitratlösung durch die Dosierung des Silbers umgerechnet wird, und wobei die Dosierung m_Ag des Silbers mit der folgenden Formel berechnet wird: $$m_{Ag}=\frac{m_{WC}{\rho }_{Ag}}{{\rho }_{WC}}\times \frac{6}{d^3}\times \left(\frac{4}{3}{x}^3+x{d}^3+2d{x}^2\right),$$
  
  wobei m_wc die Gesamtmasse des Wolframkarbides, ρ_Ag die Dichte des Silbers, ρ_wc die Dichte des Wolframkarbides und d die durchschnittliche Partikelgröße des Wolframkarbid-Pulvers darstellt. Die Einheit für d ist in µm und x stellt die Dichte der Silberschicht in dem Verbundpulver des durch das Silber umhüllten Wolframkarbides dar.
• S2: Vermischen des Verbundpulvers des durch das Silber umhüllten Wolframkarbides mit dem Silberpulver und Pressen zu einem Pressling;
• S3: Platzieren des in S2 hergestellten Presslings und Silberblocks in einem durch die Ammoniak-Zersetzungsatmosphäre geschützten Sinterofen und Durchführen von Sintern und Infiltrieren, um ein Silber-Wolframkarbid-Kontaktmaterial zu erhalten.

The present invention is realized by the following technical solution: a method for producing the silver-tungsten carbide contact material, comprising the following steps:

• S1: Mixing silver nitrate solution, polyethylene glycol, sodium hydroxide solution (sodium hydroxide solution) and dextrose solution uniformly and performing a reduction reaction under ultrasonic vibration and stirring conditions to precipitate silver and coat it outside the tungsten carbide powder, thereby forming a composite powder of the tungsten carbide coated by the silver is formed; The dosage of the silver nitrate solution is converted by the dosage of the silver, and the dosage m _{Ag of} the silver is calculated using the following formula: $$m_{\mathrm{A.}G}=\frac{m_{\mathrm{W.}\mathrm{C.}}{\rho }_{\mathrm{A.}G}}{{\rho }_{\mathrm{W.}\mathrm{C.}}}\times \frac{\mathrm{6th}}{d^3}\times \left(\frac{\mathrm{4th}}{3}{x}^3+x{d}^3+2d{x}^2\right),$$
  
  where m _{wc is} the total mass of tungsten carbide, ρ _{Ag is} the density of silver, ρ _{wc is} the density of tungsten carbide and d is the average particle size of the tungsten carbide powder. The unit for d is in µm and x represents the density of the silver layer in the composite powder of the tungsten carbide coated by the silver.
• S2: Mixing the composite powder of the tungsten carbide coated by the silver with the silver powder and pressing to form a compact;
• S3: Place the compact and silver block produced in S2 in a sintering furnace protected by the ammonia decomposition atmosphere, and carry out sintering and infiltration to obtain a silver-tungsten carbide contact material.

The thickness of the silver layer of the composite powder of the tungsten carbide enveloped by the silver is preferably 10-200 nm in S1.

• Zugeben des Wolframkarbid-Pulvers und der Silbernitratlösung in einem Reaktionsgefäß und anschließendes Zugeben des Polyethylenglykols in dem Reaktionsgefäß, Schwingen und Rühren mit Ultraschall, sodass sie gleichmäßig vermischt werden;
• anschließendes Schwingen und Rühren mit Ultraschall, Zugeben der Natriumhydroxidlösung in dem Reaktionsgefäß, bis der pH-Wert der Lösung 8 bis 9 erreicht;
• anschließend weiteres Schwingen und Rühren mit Ultraschall, so dass sie gleichmäßig vermischt werden, dann wird ein Ultraschallrühren erhalten;
• allmähliches Zugeben der Dextrose-Lösung in dem Reaktionsgefäß, wobei die Zugabegeschwindigkeit 0,5-2 L/min beträgt;
• weiteres Schwingen und Rühren mit Ultraschall, nach vollständigem Ausfällen der Silberionen in der Lösung;
• Durchführen einer Reduktionsreaktion; Umhüllen des ausgefällten Silbers an dem Wolframkarbid-Pulver, um ein Verbundpulver des durch das Silber umhüllten Wolframkarbides zu bilden;
• Absaugen und Filtrieren der Reaktionspartnerlösung in dem Reaktionsgefäß, um das Verbundpulver des durch das Silber umhüllten Wolframkarbides abzuscheiden, wobei anschließend ein Reinigen und Trocknen durchgeführt werden.

Preferably, S1 further comprises:

• Adding the tungsten carbide powder and the silver nitrate solution in a reaction vessel, and then adding the polyethylene glycol in the reaction vessel, vibrating and stirring with ultrasound so that they are uniformly mixed;
• then vibrating and stirring with ultrasound, adding the sodium hydroxide solution in the reaction vessel until the pH of the solution reaches 8 to 9;
• then further ultrasonic vibrating and stirring so that they are mixed evenly, then ultrasonic stirring is obtained;
• gradually adding the dextrose solution in the reaction vessel, the rate of addition being 0.5-2 L / min;
• further vibrating and stirring with ultrasound, after complete precipitation of the silver ions in the solution;
• Performing a reduction reaction; Coating the precipitated silver on the tungsten carbide powder to form a composite powder of the tungsten carbide coated by the silver;
• Sucking off and filtering the reactant solution in the reaction vessel in order to deposit the composite powder of the tungsten carbide enveloped by the silver, with cleaning and drying then being carried out.

The solid-liquid ratio of the tungsten carbide powder and the silver nitrate solution is preferably 5-70 g / L.

The molecular weight of the polyethylene glycol in S1 is preferably 500-20,000, the amount added being 7-12% of the mass of the tungsten carbide powder. Because polyethylene glycol is added as a stabilizer, the polyethylene glycol envelops the surface of the tungsten carbide particles in the ultrasonic process, whereby the surface potential energy of the particles is increased and the agglomeration of the tungsten carbide particles is inhibited.

The concentration of the dextrose solution in S1 is preferably 30-300 g / L. The fact that a dextrose solution of low concentration is used as the reducing agent prevents the silver from precipitating too quickly, and at the same time, in combination with a growth-inhibiting function of the polyethylene glycol, the thickness of the silver housing layer is effectively controlled.

The average particle size of the tungsten carbide powder in S1 is preferably 0.5-8 μm.

The porosity of the compact in S2 is preferably 5-55%.

The present invention further provides a silver-tungsten carbide contact material in which the tungsten carbide has a mass percentage of 40-90%.

In the present invention, the exterior of the tungsten carbide powder particles is covered by a pure silver casing layer having a thickness of 10-200 nm to obtain a tungsten carbide-silver composite powder in a monodisperse core-casing structure, namely, a tungsten carbide composite powder covered with the silver, physical insulation between the tungsten carbide particles is formed with the pure silver. Since the silver has excellent ductility, in the press molding process of the powder, the adjacent tungsten carbide particles can engage with each other through the pure silver housing layer enveloping an outer layer to form a mechanical combination, whereby the molding performance of the powder is significantly improved to form the mixed silver-tungsten carbide - Ensure powder with a high tungsten carbide content, thereby making the high-density silver-tungsten carbide material with a high Realize tungsten carbide content. With the above method, the molding of the composite powder dispersed in individual particles is ensured, thereby the moldability of the powder is greatly improved.

Figure list

• 1 zeigt eine Gewebe-SEM-Fotografie des Silber-Wolframkarbid-Kontaktmaterials in einer ersten Ausführungsform der vorliegenden Erfindung.
• 2 zeigt eine bei der Leistungsprüfung für das herkömmliche Silber-Wolframkarbid-Kontaktmaterial erhaltene Gewebe-SEM-Fotografie in einer ersten Ausführungsform der vorliegenden Erfindung.
• 3 zeigt eine metallografische Fotografie des Silber-Wolframkarbid-Kontaktmaterials in einer ersten Ausführungsform der vorliegenden Erfindung.
• 4 zeigt eine metallografische Fotografie des Silber-Wolframkarbid-Kontaktmaterials in einer zweiten Ausführungsform der vorliegenden Erfindung.

The present invention is explained in more detail below in connection with figures.

• 1 Figure 12 shows a tissue SEM photograph of the silver-tungsten carbide contact material in a first embodiment of the present invention.
• 2 Fig. 10 shows a tissue SEM photograph obtained in the performance test for the conventional silver-tungsten carbide contact material in a first embodiment of the present invention.
• 3 Figure 13 shows a metallographic photograph of the silver-tungsten carbide contact material in a first embodiment of the present invention.
• 4th Figure 12 shows a metallographic photograph of the silver-tungsten carbide contact material in a second embodiment of the present invention.

DETAILED DESCRIPTION

In connection with the detailed embodiments, the present invention will be explained in more detail below, but the present invention is not limited to these detailed embodiments. Those skilled in the art should understand that the present invention covers all optional solutions, improved solutions and equivalent solutions within the scope of the claims.

Embodiment 1

• a. Lösen von 3,25 Kg Silbernitratfeststoffen in 2500 L entionisierten Wasser, um eine Silbernitratlösung zuzubereiten;
• b. Zugeben von 33,2 Kg von Wolframkarbid-Pulvern und Silbernitratlösung in dem Reaktionsgefäß, anschließendes Zugeben von 3 Kg von Polyethylenglykol und angemessener Menge an entionisiertem Wasser, Behandeln mit Ultraschall und Rühren für 2 Stunden;
• c. Weiteres Behandeln mit Ultraschall und Rühren, allmähliches Zugeben der Natriumhydroxidlösung in dem Gefäß, bis der pH-Wert der Lösung 8-9 erreicht, und weiteres Behandeln mit Ultraschall und Rühren für 0,5 Stunde;
• d. Weiteres Behandeln mit Ultraschall und Rühren, allmähliches Zugeben der Dextrose-Lösung mit einer Konzentration von 100 g/L, wobei die Zugabegeschwindigkeit 1,5 L/min beträgt, bis das Silber in der Lösung vollständig ausgefällt wird, weiteres Behandeln mit Ultraschall und Rühren für 0,5 Stunde;
• e. Absaugen und Filtrieren der Lösung, Reinigen des erhaltenen Verbundpulvers mit entionisiertem Wasser und Trocknen;
• f. Einlegen des in dem Schritt e erhaltenen Verbundpulvers und des Silberpulvers in einem V-Typ-Pulvermischer, um ein Mischen für 10-12 Stunden durchzuführen, um ein AgWC-Pulver mit einem Silbergehalt von 5% zu erhalten;
• g. Pressen des in dem Schritt f erhaltenen AgWC-Pulvers mittels einer Pulverformeinrichtung zu einem Pressling;
• h: Platzieren des in dem Schritt g erhaltenen Presslings und Silberblocks in einem durch die Ammoniak-Zersetzungsatmosphäre geschützten Sinterofen, Sintern bei 1000J und Infiltrieren für 2 Stunden, Herausnehmen aus dem Ofen nach Abkühlen, nach dem Reinigen wird ein Silber-Wolframkarbid-Kontaktmaterial erhalten.

A method of making the silver-tungsten carbide contact material comprising the following steps:

• a. Dissolving 3.25 kg of silver nitrate solids in 2500 L of deionized water to prepare a silver nitrate solution;
• b. Adding 33.2 kg of tungsten carbide powders and silver nitrate solution to the reaction vessel, then adding 3 kg of polyethylene glycol and appropriate amount of deionized water, sonicating and stirring for 2 hours;
• c. Further treatment with ultrasound and stirring, gradually adding the sodium hydroxide solution in the vessel until the pH of the solution reaches 8-9, and further treatment with ultrasound and stirring for 0.5 hour;
• d. Further treatment with ultrasound and stirring, gradually adding the dextrose solution at a concentration of 100 g / L, the rate of addition being 1.5 L / min until the silver in the solution is completely precipitated, further treatment with ultrasound and stirring for 0.5 hour;
• e. Suctioning off and filtering the solution, cleaning the composite powder obtained with deionized water and drying;
• f. Placing the composite powder and the silver powder obtained in the step e in a V-type powder mixer to perform mixing for 10-12 hours to obtain an AgWC powder having a silver content of 5%;
• G. Pressing the AgWC powder obtained in step f into a compact by means of a powder molding device;
• h: Placing the pellet and silver block obtained in step g in a sintering furnace protected by the ammonia decomposition atmosphere, sintering at 1000J and infiltrating for 2 hours, removing from the furnace after cooling, after cleaning a silver-tungsten carbide contact material is obtained.

It goes without saying that step h is from the prior art, the setting of the sintering temperature and the infiltration time not being restricted to the exemplary embodiment, and this is not explained in detail here.

3 FIG. 13 shows a metallographic photograph of the silver-tungsten carbide contact material obtained by the method for manufacturing the silver-tungsten carbide contact material in the first embodiment, a tissue SEM photograph being as in FIG 1 is shown. In the first embodiment, a performance test is carried out for the available silver-tungsten carbide materials on the market, and the tissue SEM photograph obtained is as in FIG 2 shown. By comparing between 1 and 2 It can be found that the fabric of the silver-tungsten carbide contact material in the first embodiment has no pores, the silver and the tungsten carbide are excellently combined with each other, and a high density is achieved.

Embodiment 2

• a. Lösen von 6,5 Kg Silbernitratfeststoffen in 4000 L entionisierten Wasser, um eine Silbernitratlösung zuzubereiten;
• b. Zugeben von 66,79 Kg von Wolframkarbid-Pulvern und Silbernitratlösung in dem Reaktionsgefäß, anschließendes Zugeben von 5 Kg von Polyethylenglykol und angemessener Menge an entionisiertem Wasser, Behandeln mit Ultraschall und Rühren für 2 Stunden;
• c. Weiteres Behandeln mit Ultraschall und Rühren, allmähliches Zugeben der Natriumhydroxidlösung in dem Gefäß, bis der pH-Wert der Lösung 8-9 erreicht, und weiteres Behandeln mit Ultraschall und Rühren für 0,5 Stunde;
• d. Weiteres Behandeln mit Ultraschall und Rühren, allmähliches Zugeben der Dextrose-Lösung mit einer Konzentration von 100 g/L, wobei die Zugabegeschwindigkeit 3L/min beträgt, weiteres Behandeln mit Ultraschall und Rühren für 0,5 Stunde nach vollständigem Ausfällen des Silbers in der Lösung;
• e. Absaugen und Filtrieren der Lösung, Reinigen des erhaltenen Verbundpulvers mit entionisiertem Wasser und Trocknen;
• f. Einlegen des in dem Schritt e
  
  erhaltenen Verbundpulvers und des Silberpulvers in einem V-Typ-Pulvermischer, um ein Mischen für 10-12 Stunden durchzuführen, um ein AgWC-Pulver mit einem Silbergehalt von Ausmaß 5% zu erhalten;
• g. Pressen des in dem Schritt f erhaltenen AgWC-Pulvers mittels einer Pulverformeinrichtung zu einem Pressling;
• h: Platzieren des in dem Schritt g erhaltenen Presslings und Silberblocks in einem durch die Ammoniak-Zersetzungsatmosphäre geschützten Sinterofen, Sintern bei $1000⌟$
  
  und Infiltrieren für 2 Stunden, Herausnehmen aus dem Ofen nach Abkühlen, dann wird ein Silber-Wolframkarbid-Kontaktmaterial erhalten.

A method of making the silver-tungsten carbide contact material comprising the following steps:

• a. Dissolving 6.5 kg of silver nitrate solids in 4000 L of deionized water to prepare a silver nitrate solution;
• b. Adding 66.79 kg of tungsten carbide powders and silver nitrate solution to the reaction vessel, then adding 5 kg of polyethylene glycol and appropriate amount of deionized water, sonicating and stirring for 2 hours;
• c. Further treatment with ultrasound and stirring, gradually adding the sodium hydroxide solution in the vessel until the pH of the solution reaches 8-9, and further treatment with ultrasound and stirring for 0.5 hour;
• d. Further treatment with ultrasound and stirring, gradually adding the dextrose solution at a concentration of 100 g / L, the rate of addition being 3L / min, further treatment with ultrasound and stirring for 0.5 hour after complete precipitation of the silver in the solution;
• e. Suctioning off and filtering the solution, cleaning the composite powder obtained with deionized water and drying;
• f. Inserting the in step e
  
  obtained composite powder and the silver powder in a V-type powder mixer to carry out mixing for 10-12 hours to obtain an AgWC powder having a silver content of 5%;
• G. Pressing the AgWC powder obtained in step f into a compact by means of a powder molding device;
• h: placing the compact and silver block obtained in step g in a sintering furnace protected by the ammonia decomposition atmosphere, sintering at $1000⌟$
  
  and infiltrating for 2 hours, removing from the furnace after cooling, then a silver-tungsten carbide contact material is obtained.

It goes without saying that step h is from the prior art, the setting of the sintering temperature and the infiltration time not being restricted to the exemplary embodiment, and this is not explained in detail here. 4th Fig. 13 shows a metallographic photograph of the silver-tungsten carbide contact material obtained by the method of manufacturing the silver-tungsten carbide contact material in the second embodiment.

So far, preferred embodiments of the present invention have been described and it should be pointed out that various developments and modifications are possible for those skilled in the art without departing from the principle of the present invention, exhaust gas cleaning unit, which should also be regarded as the scope of the invention.

Claims (10)

A method of manufacturing silver-tungsten carbide contact material, characterized in that it comprises the following steps: S1: uniformly mixing silver nitrate solution, polyethylene glycol, sodium hydroxide solution and dextrose solution and performing a reduction reaction under ultrasonic vibration and stirring conditions to precipitate silver and this outside encasing the tungsten carbide powder, thereby forming a composite powder of the tungsten carbide encased by the silver; The dosage of the silver nitrate solution is converted by the dosage of the silver, and the dosage m _{Ag of} the silver is calculated using the following formula: $$m_{\mathrm{A.}G}=\frac{m_{\mathrm{W.}\mathrm{C.}}{\rho }_{\mathrm{A.}G}}{{\rho }_{\mathrm{W.}\mathrm{C.}}}\times \frac{\mathrm{6th}}{d^3}\times \left(\frac{\mathrm{4th}}{3}{x}^3+x{d}^3+2d{x}^2\right),$$

where m _{wc is} the total mass of tungsten carbide, ρ _{Ag is} the density of silver, ρ _{wc is} the density of tungsten carbide and d is the average particle size of the tungsten carbide powder, and where the unit for d is in µm and x is the density of the silver layer in the composite powder of the tungsten carbide covered by the silver. S2: Mixing the composite powder of the tungsten carbide coated by the silver with the silver powder and pressing to form a compact; S3: Place the compact and silver block produced in S2 in a sintering furnace protected by the ammonia decomposition atmosphere, and carry out sintering and infiltration to obtain a silver-tungsten carbide contact material. Method for producing silver-tungsten carbide contact material according to Claim 1 , characterized in that in S1 the thickness of the silver layer of the composite powder of the tungsten carbide enveloped by the silver is 10-200 nm. Method of manufacturing according to Claim 1 or 2 characterized in that S1 further comprises: adding the tungsten carbide powder and the silver nitrate solution in a reaction vessel, and then adding the polyethylene glycol in the reaction vessel, vibrating and stirring with ultrasound so that they are uniformly mixed; subsequent vibration and stirring with ultrasound, adding the sodium hydroxide solution in the reaction vessel until the pH value of the solution reaches 8 to 9, then further vibration and stirring with ultrasound so that it mixes evenly then ultrasonic agitation is obtained; gradually adding the dextrose solution in the reaction vessel, the rate of addition being 0.5-2 L / min, further vibrating and stirring with ultrasound, after complete precipitation of the silver ions in the solution, carrying out a reduction reaction, coating the precipitated silver on the tungsten carbide -Powder to form a composite powder of the silver-clad tungsten carbide, sucking and filtering the reactant solution in the reaction vessel to deposit the composite powder of the silver-clad tungsten carbide, followed by cleaning and drying. Method for producing silver-tungsten carbide contact material according to Claim 3 , characterized in that the solid-liquid ratio of the tungsten carbide powder and the silver nitrate solution is 5-70 g / L. Method for producing silver-tungsten carbide contact material according to Claim 3 or 4th , characterized in that in S1 the molecular weight of the polyethylene glycol is 500-20,000, the amount added being 7-12% of the mass of the tungsten carbide powder. Method for producing silver-tungsten carbide contact material according to Claim 3 , 4th or 5 , characterized in that in S1 the concentration of the dextrose solution is 30-300 g / L. Process for producing silver-tungsten carbide contact material according to one of the Claims 3 to 6th , characterized in that in S1 the average particle size of the tungsten carbide powder is 0.5-8 µm. Method for producing silver-tungsten carbide contact material according to one of the preceding claims, characterized in that in S2 the porosity of the compact is 5-55%. Silver-tungsten carbide contact material, characterized in that it is combined with a method for producing silver-tungsten carbide contact material according to one of the Claims 1 to 8th is made. Silver-tungsten carbide contact material Claim 9 , characterized in that the mass percentage of the tungsten carbide is 40-90%.

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