Silver tungsten-nickel carbide contact and preparation method thereof

Abstract

The invention discloses a silver tungsten carbide nickel contact and a preparation method thereof.The preparation method comprises the following steps that S1, mixed powder composed of silver powder and nickel powder is put into a vapor deposition reaction chamber, a tungsten carbide precursor and argon are introduced into the vapor deposition reaction chamber for a reaction, and nano tungsten carbide coated mixed powder is obtained; s2, the nano tungsten carbide coated mixed powder and tungsten carbide powder are mixed and granulated, granules obtained after granulation are added into a forming press to be pressed and formed, and a pressed blank is obtained; and S3, the pressed blank is fed into a sintering furnace to be sintered, and then a sintered product is fed into an infiltration furnace to be subjected to infiltration operation. The silver powder and the nickel powder are coated with the nano tungsten carbide, the ultrahigh specific surface area of the nano tungsten carbide becomes a'high-speed channel 'of atomic diffusion, silver atoms and nickel atoms are rapidly migrated to a micron tungsten carbide contact point through surface diffusion, the interface bonding strength is remarkably improved, and the structure uniformity and the interface bonding strength of the contact are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical contact, in particular to a silver tungsten carbide nickel contact and a preparation method thereof. BACKGROUND

[0002] The electrical contact is a contact element of electrical switch, instrument and meter, etc., mainly bearing the role of connecting and breaking the circuit and load current. As a material for preparing the electrical contact, the silver-based electrical contact material is the most widely used and applied one. The silver tungsten carbide nickel is a special electrical contact material, having the advantages of arc erosion resistance, anti-welding and oxidation resistance. The silver tungsten carbide nickel contact material is widely used in various types of molded case circuit breakers, frame type universal circuit breakers and automobile electrical appliances. This is because the material has good anti-welding and electrical conductivity, low and stable contact resistance.

[0003] At present, the manufacturing process of the silver tungsten carbide nickel contact material mainly includes the infiltration method. The main step is to infiltrate the silver liquid into the silver tungsten carbide compact at a temperature above the melting point of silver, so that the prepared silver tungsten carbide contact has high density. Therefore, the silver tungsten carbide contact is usually manufactured by the infiltration method. However, due to the poor wettability of silver to tungsten carbide, metal elements such as nickel need to be added to improve the wettability of silver to tungsten carbide when the infiltration method is used for manufacturing, so that the silver liquid can infiltrate into the silver tungsten carbide compact to obtain a dense silver tungsten carbide contact. However, the metal elements are difficult to disperse uniformly and cannot effectively cover the surface of the tungsten carbide particles, so that the wettability of silver to tungsten carbide cannot be effectively improved, the infiltrated silver liquid is not enough to fill the silver tungsten carbide compact, and thus the density of the contact is not ideal, the metallographic structure is not uniform, and the arc burning resistance of the contact is low.

[0004] Therefore, a preparation process of silver tungsten carbide graphite contact material is disclosed in a Chinese patent, which includes the following steps: tungsten powder and graphite powder are subjected to plasma ball milling to promote the organization refinement, alloying, activation, chemical reaction and acceleration of in-situ gas-solid phase reaction of the powder, which can greatly improve the ball milling efficiency, significantly reduce the ball milling pollution, and form a unique structure to significantly improve the performance of the material. The silver-coated graphite powder prepared by the chemical coating process is subjected to plasma ball milling and powder burning to form particles, which are pressed into a compact and placed in a defatting furnace in an ammonia decomposition atmosphere to remove the compacting agent. The defatted compact is carbonized in a hydrogen atmosphere, and the carbonized compact is sintered in a sintering furnace in an ammonia decomposition atmosphere. The silver tungsten carbide graphite contact material prepared by the preparation method has higher uniformity and dispersion of the metallographic structure, fewer organization porosity defects, and better product bonding strength and bending strength than those of the conventional process.

[0005] Chinese patent CN103824710B discloses a method for preparing silver tungsten carbide contact material by silver-coated tungsten carbide powder and its product, the technical solution of which is to use silver nitrate crystal and tungsten carbide powder as raw materials, to prepare silver tungsten carbide contact by chemical coating and liquid phase infiltration process, and the prepared product includes the following components by weight percentage: 38% to 42% tungsten carbide, 0 to 0.2% additives, and the rest is silver; wherein the additives refer to one or more than one of nickel, copper and zirconium. The silver tungsten carbide contact material prepared by the method has high density, high hardness, low and stable contact resistance, uniform metallographic structure, good high temperature oxidation resistance, arc erosion resistance and wear resistance.

[0006] The above patents all use silver coating to promote the uniform dispersion of silver and the added metal elements on the surface of tungsten carbide particles, so as to improve the uniformity and hardness, etc. However, since the silver coating is all chemical coating, the uniformity of the coating thickness is relatively poor, and it is easy to agglomerate. In the infiltration process, liquid silver will accumulate on the surface of tungsten carbide, blocking other metal elements from entering tungsten carbide, thus reducing the uniformity of the silver tungsten carbide contact material and the interface bonding strength. SUMMARY

[0007] In view of the defects of the prior art, the present application aims to provide a preparation method of silver tungsten carbide nickel contact, which comprises the following steps: S1, putting the mixed powder composed of silver powder and nickel powder into a gas phase deposition reaction chamber, introducing tungsten carbide precursor and argon into the gas phase deposition reaction chamber respectively for reaction to obtain nano tungsten carbide coated mixed powder; S2, mixing the nano tungsten carbide coated mixed powder and tungsten carbide powder and granulating, and adding the granulated granules into a molding press for compression molding to obtain a green body; S3, sending the green body into a sintering furnace for sintering, and then sending the sintered product into a infiltration furnace for infiltration operation.

[0008] The prior art is all adopting the silver infiltration metal coating, and the technical concept is to use the silver infiltration metal coating to improve the wettability of silver and tungsten carbide, however, in the infiltration process, liquid silver is accumulated on the surface of tungsten carbide, and other metal elements are blocked from entering the tungsten carbide. Therefore, the application breaks through the existing technical prejudice and firstly proposes that the silver powder and the nickel powder are coated with nano tungsten carbide to form a 50-100 nm thick coating layer on the surface of the silver powder and the nickel powder, and a sintering technology route based on the "nano tungsten carbide coating-micron matching system" is researched. In the sintering stage, the nano tungsten carbide is coated on the surface of the micron silver particles and the nickel particles. In the initial stage of heating, the super-high specific surface area of the nano tungsten carbide becomes a "high-speed channel" for atomic diffusion, and the silver atoms and the nickel atoms quickly migrate to the micron tungsten carbide contact point through surface diffusion, so that the nano tungsten carbide plays a "bridge" role for the diffusion of silver atoms and nickel atoms. In the infiltration stage, the liquid silver diffuses in the grain boundary of the micron tungsten carbide to form a coherent interface, and the penetration depth significantly exceeds that of the traditional process, and the tungsten released by the nano tungsten carbide reacts with the silver to generate Ag-W phase, which significantly improves the interface bonding strength.

[0009] Preferably, the mass ratio of the silver powder, the nickel powder and the tungsten carbide powder is (45-55):(10-25):(20-45), the particle size of the silver powder is 1-2 microns, the particle size of the nickel powder is 1-2 microns, and the particle size of the tungsten carbide powder is 0.5-2 microns.

[0010] Preferably, the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, and the ratio of the tungsten hexafluoride gas to the methane gas is 1:(8-12).

[0011] Preferably, in the step S1, the reaction temperature is 600-800 DEG C, the rotation rate of the reaction chamber is 30-60 r / min, the reaction time is 15-60 min, and after the reaction is completed, the reaction chamber is cooled to room temperature.

[0012] Preferably, in the step S1, the mixed powder is obtained by the following steps: the silver powder and the nickel powder are placed in a mixing barrel of a ball mill, and hard alloy balls and a dispersing agent are added to the mixing barrel for ball milling to obtain the mixed powder, wherein the ball milling time is 12-72 h, and the ball milling rotation speed is 100-500 r / min.

[0013] The application forms an Ag-Ni solid solution by high-energy ball milling of the silver powder and the nickel powder. In the sintering stage, the Ag-Ni solid solution occurs segregation, the Ni atoms migrate to the surface of the nano tungsten carbide and diffuse to the grain boundary of the micron tungsten carbide to form a coherent interface, and the depth of the infiltration is further improved.

[0014] Preferably, the added mass of the dispersing agent is 0.1-0.5% of the total mass of the silver powder and the nickel powder, and the volume of the hard alloy balls accounts for 30-40% of the total volume of the mixing barrel.

[0015] Preferably, the nickel powder is silver-coated nickel powder, which is prepared by the following steps: adding nickel raw material with a particle size of 0.8-1.8 microns into a silver-ammonia solution and stirring, adding ascorbic acid aqueous solution dropwise for reaction, then filtering and drying to obtain the silver-coated nickel powder, wherein the silver-ammonia solution is a mixed solution composed of silver nitrate aqueous solution and ammonia water, the concentration of silver nitrate in the silver-ammonia solution is 0.5-1.5 mol / L, the mass fraction of ascorbic acid in the ascorbic acid aqueous solution is 1-2%, the drying temperature is 70-90℃, and the drying time is 30-100 min.

[0016] The present application adopts silver-coated nickel powder, mixes it with silver powder, and coats the mixture of silver-coated nickel powder and silver powder with nano tungsten carbide, thereby forming a multi-layer coating system and multi-stage synergistic effect. Specifically, during the sintering stage, the nano silver in the silver-coated nickel powder has a high specific surface area and will diffuse and connect to the surface of the micron silver powder, and the nano tungsten carbide will further combine with the nano silver in the silver-coated nickel powder, so that during the subsequent infiltration stage, the nickel in the silver-coated nickel powder can also infiltrate along the silver infiltration channel and further infiltrate into the micron tungsten carbide, and therefore the silver-coated nickel powder can improve the infiltration depth of the nickel powder.

[0017] Preferably, in step S3, during the sintering process, the sintering temperature is 800-850℃, and the sintering time is 1.0-2.5 h.

[0018] Preferably, in step S3, during the infiltration process, the infiltration temperature is 1000-1050℃, and the infiltration residence time is 120-150 min.

[0019] A silver-tungsten carbide-nickel contact prepared by the above preparation method.

[0020] Compared with the prior art, the present application has the following beneficial effects: The present application coats silver powder and nickel powder with nano tungsten carbide. The ultra-high specific surface area of the nano tungsten carbide becomes a "high-speed channel" for atomic diffusion, and silver atoms and nickel atoms rapidly migrate to the micron tungsten carbide contact point through surface diffusion, so that the nano tungsten carbide plays a "bridge" role for the diffusion of silver atoms and nickel atoms. During the infiltration stage, liquid silver micron tungsten carbide diffuses at the grain boundaries to form a coherent interface, and the infiltration depth significantly exceeds that of the traditional process. Moreover, the reaction between tungsten released by the nano tungsten carbide and silver generates Ag-W phase, significantly improving the interface bonding strength and the uniformity of the silver-tungsten carbide contact material and the interface bonding strength. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed in the specification are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values between the recited upper and lower values. For numeric values, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined to create one or more new numeric ranges, which are to be considered disclosed in the present application.

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the specific embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of the present application. Embodiment 1

[0023] A preparation method of a silver tungsten carbide nickel contact includes the following steps: S1, put the mixed powder composed of silver powder and nickel powder into a gas phase deposition reaction chamber, pass tungsten carbide precursor and argon into the gas phase deposition reaction chamber respectively to carry out reaction, and obtain nanometer tungsten carbide coated mixed powder; the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas and the methane gas is 1:8; the reaction temperature is 600°C, the rotation rate of the reaction chamber is 30r / min, the reaction time is 15min, and after the reaction is completed, the product is cooled to room temperature; S2, mix the nanometer tungsten carbide coated mixed powder and tungsten carbide powder and carry out granulation, and put the granulated granules into a molding press to carry out compression molding, and obtain a green body; S3, put the green body into a sintering furnace to carry out sintering, and then put the sintered product into a infiltration furnace to carry out infiltration operation; the sintering temperature is 800°C, the sintering time is 1.0h; the infiltration temperature is 1000°C, and the infiltration residence time is 120min. In the above steps, the mass ratio of the silver powder, the nickel powder and the tungsten carbide powder is 45:10:45, the particle size of the silver powder is 1 micrometer, the particle size of the nickel powder is 1 micrometer, and the particle size of the tungsten carbide powder is 0.5 micrometer. Embodiment 2

[0024] A preparation method of a silver tungsten carbide nickel contact includes the following steps: S1, put the mixed powder composed of silver powder and nickel powder into a gas phase deposition reaction chamber, pass tungsten carbide precursor and argon into the gas phase deposition reaction chamber respectively to carry out reaction, and obtain nanometer tungsten carbide coated mixed powder; the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas and the methane gas is 1:8; the reaction temperature is 600°C, the rotation rate of the reaction chamber is 30r / min, the reaction time is 15min, and after the reaction is completed, the product is cooled to room temperature; S2, mix the nanometer tungsten carbide coated mixed powder and tungsten carbide powder and carry out granulation, and put the granulated granules into a molding press to carry out compression molding, and obtain a green body; S2, the nano tungsten carbide coated mixed powder and tungsten carbide powder are mixed and granulated, and the granulated pellets are added into a molding press for compression molding to obtain a green compact; S3, the green compact is sent into a sintering furnace for sintering, and then the sintered product is sent into a infiltration furnace for infiltration operation, the sintering temperature is 850℃, the sintering time is 2.5h; the infiltration temperature is 1050℃, and the infiltration residence time is 150min. In the above steps, the mass ratio of silver powder, nickel powder and tungsten carbide powder is 55:25:20, the particle size of silver powder is 2 microns, the particle size of nickel powder is 2 microns, and the particle size of tungsten carbide powder is 2 microns. Example 3

[0025] A preparation method of a silver tungsten carbide nickel contact, comprising the following steps: S1, the mixed powder composed of silver powder and nickel powder is put into a gas phase deposition reaction chamber, and tungsten carbide precursor and argon are respectively introduced into the gas phase deposition reaction chamber for reaction to obtain nano tungsten carbide coated mixed powder; the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, the ratio of tungsten hexafluoride gas to methane gas is 1:10; the reaction temperature is 700℃, the rotation rate of the reaction chamber is 40r / min, the reaction time is 40min, and after the reaction is completed, the reaction chamber is cooled to room temperature; S2, the nano tungsten carbide coated mixed powder and tungsten carbide powder are mixed and granulated, and the granulated pellets are added into a molding press for compression molding to obtain a green compact; S3, the green compact is sent into a sintering furnace for sintering, and then the sintered product is sent into a infiltration furnace for infiltration operation, the sintering temperature is 820℃, the sintering time is 2h; the infiltration temperature is 1010℃, and the infiltration residence time is 110min. In the above steps, the mass ratio of silver powder, nickel powder and tungsten carbide powder is 50:25:25, the particle size of silver powder is 1.5 microns, the particle size of nickel powder is 1.5 microns, and the particle size of tungsten carbide powder is 2 microns. Example 4

[0026] A preparation method of a silver tungsten carbide nickel contact, comprising the following steps: S1, the silver powder and nickel powder are placed in the mixing barrel of the ball mill, and hard alloy balls and dispersants are added to the mixing barrel for ball milling to obtain a mixed powder, wherein the ball milling time is 12 h, the ball milling speed is 100 r / min, the added mass of the dispersant is 0.1% of the total mass of the silver powder and the nickel powder, and the volume of the hard alloy balls accounts for 30% of the total volume of the mixing barrel; then, the mixed powder composed of the silver powder and the nickel powder is placed into a vapor deposition reaction chamber, tungsten carbide precursors and argon are respectively introduced into the vapor deposition reaction chamber for reaction to obtain a nano tungsten carbide coated mixed powder; the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas to the methane gas is 1:10; the reaction temperature is 700°C, the rotation rate of the reaction chamber is 40 r / min, the reaction time is 40 min, and after the reaction is completed, the reaction chamber is cooled to room temperature; S2, the nano tungsten carbide coated mixed powder and the tungsten carbide powder are mixed and granulated, and the granulated pellets are added to a molding press for compression molding to obtain a green compact; S3, the green compact is sent into a sintering furnace for sintering, and then the sintered product is sent into a infiltration furnace for infiltration operation, the sintering temperature is 820°C, the sintering time is 2 h; the infiltration temperature is 1010°C, and the infiltration residence time is 110 min. In the above steps, the mass ratio of the silver powder, the nickel powder and the tungsten carbide powder is 50:25:25, the particle size of the silver powder is 1.5 microns, the particle size of the nickel powder is 1.5 microns, and the particle size of the tungsten carbide powder is 2 microns. Example 5

[0027] A silver tungsten carbide nickel contact preparation method comprises the following steps: S1, the silver powder and nickel powder are placed in the mixing barrel of the ball mill, and hard alloy balls and dispersants are added to the mixing barrel for ball milling to obtain a mixed powder, wherein the ball milling time is 12 h, the ball milling speed is 100 r / min, the added mass of the dispersant is 0.1% of the total mass of the silver powder and the nickel powder, and the volume of the hard alloy balls accounts for 30% of the total volume of the mixing barrel; then, the mixed powder composed of the silver powder and the nickel powder is placed into a vapor deposition reaction chamber, tungsten carbide precursors and argon are respectively introduced into the vapor deposition reaction chamber for reaction to obtain a nano tungsten carbide coated mixed powder; the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas to the methane gas is 1:10; the reaction temperature is 700°C, the rotation rate of the reaction chamber is 40 r / min, the reaction time is 40 min, and after the reaction is completed, the reaction chamber is cooled to room temperature; S2, the nano tungsten carbide coated mixed powder and the tungsten carbide powder are mixed and granulated, and the granulated pellets are added to a molding press for compression molding to obtain a green compact; S3, send the green compact into a sintering furnace to perform sintering, and then send the sintered product into a infiltration furnace to perform infiltration operation, the sintering temperature is 820℃, the sintering time is 2h; the infiltration temperature is 1010℃, and the infiltration residence time is 110min. In the above steps, the mass ratio of the silver powder, the nickel powder and the tungsten carbide powder is 50:25:25, the particle size of the silver powder is 1.5 microns, the particle size of the nickel powder is 1.5 microns, and the particle size of the tungsten carbide powder is 2 microns. Example 6

[0028] A preparation method of a silver tungsten carbide nickel contact, comprising the following steps: S1, put the silver powder and the nickel powder into a mixing barrel of a ball mill, and add hard alloy balls and sodium dodecyl sulfate into the mixing barrel to perform ball milling, to obtain mixed powder, wherein the ball milling time is 60h, the ball milling rotation speed is 300r / min, the added mass of the sodium dodecyl sulfate is 0.3% of the total mass of the silver powder and the nickel powder, and the volume of the hard alloy balls accounts for 35% of the total volume of the mixing barrel; then, put the mixed powder composed of the silver powder and the nickel powder into a gas phase deposition reaction chamber, and pass tungsten carbide precursor and argon into the gas phase deposition reaction chamber to perform reaction, to obtain nanometer tungsten carbide coated mixed powder; the tungsten carbide precursor is tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas and the methane gas is 1:10; the reaction temperature is 700℃, the rotation rate of the reaction chamber is 40r / min, the reaction time is 40min, and after the reaction, wait for cooling to room temperature; S2, mix the nanometer tungsten carbide coated mixed powder and the tungsten carbide powder and perform granulation, and add the granulated granules into a forming press to perform compression molding, to obtain a green compact; S3, send the green compact into a sintering furnace to perform sintering, and then send the sintered product into a infiltration furnace to perform infiltration operation, the sintering temperature is 820℃, the sintering time is 2h; the infiltration temperature is 1010℃, and the infiltration residence time is 110min. In the above steps, the mass ratio of the silver powder, the nickel powder and the tungsten carbide powder is 50:25:25, the particle size of the silver powder is 1.5 microns, the particle size of the nickel powder is 1.5 microns, and the particle size of the tungsten carbide powder is 2 microns. Example 7

[0029] A preparation method of a silver tungsten carbide nickel contact, comprising the following steps: S1, put the silver powder and nickel powder into the mixing barrel of the ball mill, and add hard alloy balls and sodium dodecyl sulfate to the mixing barrel for ball milling, to obtain a mixed powder, wherein the ball milling time is 60 h, the ball milling speed is 300 r / min, the added mass of the sodium dodecyl sulfate is 0.3% of the total mass of the silver powder and the nickel powder, and the volume of the hard alloy balls accounts for 35% of the total volume of the mixing barrel, wherein the nickel powder is a silver-coated nickel powder, which is prepared by the following steps: adding a nickel raw material with a particle size of 0.8 microns into a silver-ammonia solution and stirring, adding an ascorbic acid aqueous solution dropwise for reaction, and then filtering and drying to obtain the silver-coated nickel powder, wherein the silver-ammonia solution is a mixed solution composed of a silver nitrate aqueous solution and ammonia water, the concentration of silver nitrate in the silver-ammonia solution is 0.5 mol / L, the mass fraction of ascorbic acid in the ascorbic acid aqueous solution is 1%, the drying temperature is 70°C, and the drying time is 30 min; Then, the mixed powder composed of the silver powder and the nickel powder is placed into a gas phase deposition reaction chamber, tungsten carbide precursors and argon are respectively introduced into the gas phase deposition reaction chamber for reaction, to obtain a nano-tungsten carbide coated mixed powder; the tungsten carbide precursors are tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas to the methane gas is 1:10; the reaction temperature is 700°C, the rotation rate of the reaction chamber is 40 r / min, the reaction time is 40 min, and after the reaction is completed, the product is cooled to room temperature; S2, the nano-tungsten carbide coated mixed powder and the tungsten carbide powder are mixed and granulated, and the granulated pellets are added into a molding press for compression molding, to obtain a green compact; S3, the green compact is sent into a sintering furnace for sintering, and then the sintered product is sent into an infiltration furnace for infiltration operation, the sintering temperature is 820°C, the sintering time is 2 h; the infiltration temperature is 1010°C, and the infiltration residence time is 110 min. In the above steps, the mass ratio of the silver powder, the silver-coated nickel powder and the tungsten carbide powder is 50:25:25, the particle size of the silver powder is 1.5 microns, the particle size of the nickel powder is 1.5 microns, and the particle size of the tungsten carbide powder is 2 microns. Example 8

[0030] A preparation method of a silver-tungsten carbide-nickel contact, comprising the following steps: S1, the silver powder and nickel powder are placed in the mixing barrel of the ball mill, and hard alloy balls and sodium dodecyl sulfate are added to the mixing barrel for ball milling, to obtain a mixed powder, wherein the ball milling time is 60 h, the ball milling speed is 300 r / min, the added mass of the sodium dodecyl sulfate is 0.3% of the total mass of the silver powder and the nickel powder, and the volume of the hard alloy balls accounts for 35% of the total volume of the mixing barrel, wherein the nickel powder is a silver-coated nickel powder, which is prepared by the following steps: adding a nickel raw material with a particle size of 1.8 microns into a silver-ammonia solution and stirring, adding an ascorbic acid aqueous solution dropwise for reaction, and then filtering and drying to obtain the silver-coated nickel powder, wherein the silver-ammonia solution is a mixed solution composed of a silver nitrate aqueous solution and ammonia water, the concentration of silver nitrate in the silver-ammonia solution is 1.5 mol / L, the mass fraction of ascorbic acid in the ascorbic acid aqueous solution is 2%, the drying temperature is 90℃, and the drying time is 100 min; Then, the mixed powder composed of the silver powder and the nickel powder is placed into a vapor deposition reaction chamber, tungsten carbide precursors and argon are respectively introduced into the vapor deposition reaction chamber for reaction, to obtain a nano tungsten carbide coated mixed powder; the tungsten carbide precursors are tungsten hexafluoride gas and methane gas, the ratio of the tungsten hexafluoride gas to the methane gas is 1:10; the reaction temperature is 700℃, the rotation rate of the reaction chamber is 40 r / min, the reaction time is 40 min, and after the reaction is completed, the reaction chamber is cooled to room temperature; S2, the nano tungsten carbide coated mixed powder and the tungsten carbide powder are mixed and granulated, and the granulated pellets are added into a molding press for compression molding, to obtain a green compact; S3, the green compact is sent into a sintering furnace for sintering, and then the sintered product is sent into an infiltration furnace for infiltration operation, the sintering temperature is 820℃, the sintering time is 2 h; the infiltration temperature is 1010℃, and the infiltration residence time is 110 min. In the above steps, the mass ratio of the silver powder, the silver-coated nickel powder and the tungsten carbide powder is 50:25:25, the particle size of the silver powder is 1.5 microns, the particle size of the nickel powder is 1.5 microns, and the particle size of the tungsten carbide powder is 2 microns. Comparative Example 1

[0031] A preparation method of a silver tungsten nickel contact, comprising the following steps: S1, a mixed powder composed of silver powder, nickel powder and tungsten carbide powder, the mass ratio of the silver powder, the nickel powder and the tungsten carbide powder is 50:25:25, the particle size of the silver powder is 1.5 microns, the particle size of the nickel powder is 1.5 microns, and the particle size of the tungsten carbide powder is 2 microns; S2, the mixed powder is granulated, and the granulated pellets are added into a molding press for compression molding, to obtain a green compact; S3, the green compact is sent into a sintering furnace to be sintered, and then the sintered product is sent into a infiltration furnace to be infiltrated, the sintering temperature is 820℃, the sintering time is 2h; the infiltration temperature is 1010℃, and the infiltration time is 110min.

[0032] The final products obtained in the above examples 1-8 and the comparative example are tested in density, hardness, conductivity, electrical life and the like. Among them, the density, hardness, conductivity and the like are tested according to the national standard test method. When testing the electrical life, the contact material is pressed into a sheet-shaped contact with a specification of Φ 6*2 in advance, and then the sheet-shaped contact is tested in electrical life under the conditions of a current of 125A, a voltage of 380V, a power factor of 0.51, and an operating frequency of 30 times / minute. The test results are shown in Table 1.

[0033] Table 1 Performance test results of the contacts obtained in examples 1-8 and the comparative example

[0034] From the above results, it can be seen that the density, hardness, conductivity and electrical life of the silver tungsten carbide nickel contact obtained in examples 1-8 are all better than those of the comparative example 1; the density and hardness of the silver tungsten carbide nickel contact obtained in examples 5-6 are better than those of examples 1-3, the conductivity and electrical life are equivalent to those of examples 1-3; and the density, hardness, conductivity and electrical life of the silver tungsten carbide nickel contact obtained in examples 7-8 are all better than those of examples 1-6. It can be seen that the density, hardness, conductivity and the like of the contact obtained by the method of the present application are all obviously improved compared with the traditional contact, and can meet the needs of actual production.

[0035] The above only describes the preferred embodiments of the present application, and is not used to limit the application, and any modification, equivalent replacement, improvement and the like within the design concept of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a silver tungsten carbide nickel contact, characterized in that: The steps include: S1. Place a mixed powder composed of silver powder and nickel powder into a vapor deposition reaction chamber, and introduce a tungsten carbide precursor and argon gas into the vapor deposition reaction chamber to react to obtain a nano-tungsten carbide coated mixed powder; S2, mixing the nano-tungsten carbide coated mixed powder and the tungsten carbide powder and granulating them, and adding the granulated granules into a molding press for compression molding to obtain a compact; S3. The compact is sent into a sintering furnace for sintering, and then the sintered product is sent into an infiltration furnace for infiltration operation.

2. The preparation method according to claim 1, characterized in that The mass ratio of silver powder, nickel powder and tungsten carbide powder is (45-55): (10-25): (20-45), the particle size of silver powder is 1-2 microns, the particle size of nickel powder is 1-2 microns, and the particle size of tungsten carbide powder is 0.5-2 microns.

3. The preparation method according to claim 1, characterized in that The tungsten carbide precursor is tungsten hexafluoride gas and methane gas, and the ratio of tungsten hexafluoride gas to methane gas is 1: (8-12).

4. The preparation method according to claim 1, characterized in that In step S1, the reaction temperature is 600-800°C, the rotation rate of the reaction chamber is 30-60 r / min, the reaction time is 15-60 min, and after the reaction is completed, it is cooled to room temperature.

5. The preparation method according to claim 1, characterized in that In step S1, the mixed powder is obtained by the following steps: placing silver powder and nickel powder in a mixing barrel of a ball mill, and adding carbide balls and a dispersant to the mixing barrel for ball milling to obtain a mixed powder, wherein the ball milling time is 12-72 hours and the ball milling speed is 100-500 r / min.

6. The preparation method according to claim 5, characterized in that The added mass of the dispersant is 0.1-0.5% of the total mass of the powder and nickel powder, and the volume of the cemented carbide balls accounts for 30-40% of the total volume of the mixing barrel.

7. The preparation method according to claim 5, characterized in that The nickel powder is silver-coated nickel powder, which is prepared by the following steps: adding a nickel raw material with a particle size of 0.8-1.8 microns to a silver-ammonia solution and stirring, adding an ascorbic acid aqueous solution dropwise for reaction, and then filtering and drying to obtain the silver-coated nickel powder, wherein the silver-ammonia solution is a mixed solution consisting of a silver nitrate aqueous solution and ammonia water, the silver nitrate concentration in the silver-ammonia solution is 0.5-1.5 mol / L, the mass fraction of ascorbic acid in the ascorbic acid aqueous solution is 1-2%, the drying temperature is 70-90° C., and the drying time is 30-100 minutes.

8. The preparation method according to claim 1, characterized in that In step S3, during the sintering process, the sintering temperature is 800-850° C. and the sintering time is 1.0-2.5 hours.

9. The preparation method according to claim 1, characterized in that In step S3, during the infiltration process, the infiltration temperature is 1000-1050° C., and the infiltration residence time is 120-150 min.

10. A silver tungsten carbide nickel contact, characterized in that: The method is prepared according to any one of claims 1 to 9.

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