CN111001801A - Silver tungsten carbide-molybdenum composite electrical contact material, framework powder thereof and preparation method - Google Patents
Silver tungsten carbide-molybdenum composite electrical contact material, framework powder thereof and preparation method Download PDFInfo
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- 239000000843 powder Substances 0.000 title claims abstract description 82
- 239000000463 material Substances 0.000 title claims abstract description 55
- 229910052750 molybdenum Inorganic materials 0.000 title claims abstract description 44
- 239000011733 molybdenum Substances 0.000 title claims abstract description 44
- UYKQQBUWKSHMIM-UHFFFAOYSA-N silver tungsten Chemical compound [Ag][W][W] UYKQQBUWKSHMIM-UHFFFAOYSA-N 0.000 title claims abstract description 44
- 239000002131 composite material Substances 0.000 title claims abstract description 26
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- JKQOBWVOAYFWKG-UHFFFAOYSA-N molybdenum trioxide Chemical compound O=[Mo](=O)=O JKQOBWVOAYFWKG-UHFFFAOYSA-N 0.000 claims abstract description 81
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 52
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims abstract description 52
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 47
- 239000011812 mixed powder Substances 0.000 claims abstract description 37
- QXYJCZRRLLQGCR-UHFFFAOYSA-N dioxomolybdenum Chemical compound O=[Mo]=O QXYJCZRRLLQGCR-UHFFFAOYSA-N 0.000 claims abstract description 36
- 238000005245 sintering Methods 0.000 claims abstract description 34
- 238000002156 mixing Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 11
- 238000000498 ball milling Methods 0.000 claims abstract description 8
- 238000003825 pressing Methods 0.000 claims abstract description 6
- 229910052709 silver Inorganic materials 0.000 claims description 34
- 239000004332 silver Substances 0.000 claims description 34
- 239000002245 particle Substances 0.000 claims description 16
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 14
- 229910021529 ammonia Inorganic materials 0.000 claims description 7
- 238000000354 decomposition reaction Methods 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000007873 sieving Methods 0.000 claims description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 abstract description 15
- 230000008595 infiltration Effects 0.000 abstract description 12
- 238000001764 infiltration Methods 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract 2
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract 1
- 239000001569 carbon dioxide Substances 0.000 abstract 1
- 238000007599 discharging Methods 0.000 abstract 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 14
- 239000010937 tungsten Substances 0.000 description 13
- 229910052721 tungsten Inorganic materials 0.000 description 13
- 229910002804 graphite Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 239000000654 additive Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 239000011148 porous material Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000010891 electric arc Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000007806 chemical reaction intermediate Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910000476 molybdenum oxide Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- PQQKPALAQIIWST-UHFFFAOYSA-N oxomolybdenum Chemical compound [Mo]=O PQQKPALAQIIWST-UHFFFAOYSA-N 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 229910001930 tungsten oxide Inorganic materials 0.000 description 1
- 238000003466 welding Methods 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
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
-
- B22F1/0003—
-
- 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
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
- B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
- H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts
- H01H11/048—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts by powder-metallurgical processes
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Powder Metallurgy (AREA)
- Contacts (AREA)
Abstract
The invention discloses a silver tungsten carbide-molybdenum composite electrical contact material, framework powder and a preparation method thereof, and the technical scheme is that ultrafine tungsten carbide powder and nano molybdenum trioxide powder are mixed through ball milling; reacting molybdenum trioxide with free carbon in tungsten carbide at high temperature in an inert atmosphere to obtain molybdenum dioxide, discharging carbon dioxide, mixing the tungsten carbide, molybdenum trioxide and molybdenum dioxide mixed powder with a certain amount of pure silver powder, and sintering at high temperature in a reducing atmosphere to convert the molybdenum dioxide and molybdenum trioxide powder into molybdenum powder; and then the compact superfine silver tungsten carbide-molybdenum composite material is obtained by adopting the conventional pressing, sintering and infiltration processes. Compared with the traditional silver tungsten carbide, the superfine silver tungsten carbide-molybdenum composite electrical contact material has the advantages that negative effects caused by free carbon are eliminated, the product compactness and the strength are higher, the superfine silver tungsten carbide-molybdenum composite electrical contact material has good wear resistance and burning resistance, and the superfine silver tungsten carbide-molybdenum composite electrical contact material has a longer electrical life when being used in a low-voltage electrical appliance.
Description
Technical Field
The invention belongs to the field of electric contact material manufacturing processes, and particularly relates to a silver tungsten carbide-molybdenum composite electric contact material and a preparation method thereof.
Background
The electrical contact material is the core part of the electrical switch, and is responsible for the tasks of connecting and disconnecting the circuit and loading current, so the performance of the electrical contact material determines the performance of the low-voltage electrical appliance and the reliability of operation. Silver tungsten carbide materials have been used in electrical products such as low-voltage molded case circuit breakers, universal circuit breakers, earth leakage protection switches, dual-power transfer switches, and the like, instead of part of silver tungsten materials due to their characteristics of high hardness, strong electrical wear resistance, fusion welding resistance, higher corrosion resistance than silver tungsten materials, and stable temperature rise. It is generally used as the moving contact material to match with silver graphite, silver tungsten carbide graphite, etc., and can also be paired in dynamic and static symmetry.
Except for part of tungsten carbide materials with high silver content, the silver tungsten carbide materials are generally manufactured by adopting an infiltration process. I.e. filling the tungsten carbide/silver tungsten carbide skeleton with molten silver, which is required to ensure good wettability between the filler metal and the filled skeleton. Because the wettability of silver and tungsten carbide is not ideal, the material manufactured by the direct infiltration process cannot meet the use requirement due to the problems of poor density and the like, and one or more additives of metals such as nickel, copper and the like are generally added in the industry to improve the wettability of silver and tungsten carbide so as to improve the infiltration effect. The additive improves the wettability of silver and tungsten carbide to some extent, but the free carbon present in the tungsten carbide powder cannot be solved by the above method, and particularly, a silver tungsten carbide material having a tungsten carbide particle size of 1 μm or less is produced. Theoretically, the thinner the tungsten carbide in the silver tungsten carbide material is, the larger the specific surface area of the tungsten carbide is, the higher the dispersion degree is, the better the arc burning resistance of the material is, but the thinner the tungsten carbide powder is, the higher the free carbon content is, and the existence of the free carbon causes great difficulty in the application of the superfine silver tungsten carbide in the electrical contact.
The tungsten carbide powder is generally obtained by reacting graphite with tungsten powder or tungsten oxide powder, and the method needs excessive graphite, so that inevitable graphite is remained in the tungsten carbide powder to influence the purity of the tungsten carbide powder. According to the national standard GB/T4295-2008 of tungsten carbide powder, the mass fraction of free carbon of the tungsten carbide powder with the particle size of more than or equal to 1 micron is less than or equal to 0.06 percent, the mass fraction of the free carbon of the tungsten carbide powder with the particle size of 0.4-0.6 micron is less than or equal to 0.15 percent, and because the free carbon density is small, the volume percentages of the free carbon of the two materials are respectively as follows: less than or equal to 0.42 percent and less than or equal to 1.03 percent, and the finer the particles, the higher the free carbon content.
The infiltration process of silver tungsten carbide material mainly utilizes the wettability among materials to fill silver liquid into the framework under the action of capillary force, so that the framework is compact. Because free carbon and silver liquid are not moist completely, the silver liquid can't get into the region at free carbon place during infiltration, and silver is in the liquid phase during infiltration, and free carbon can be with the silver liquid reverse discharge that exists in the skeleton, can not avoid using free carbon to form tiny hole as the center after the infiltration. The existence of the holes can reduce the physical and mechanical properties of the material, further influence the use performance of the material, and particularly reduce the burning loss resistance and the electric arc resistance of the material.
Patent CN104384512B discloses a method for preparing a silver tungsten carbide contact material, which mainly adopts a ball milling method to add additives to improve the wetting relationship between tungsten carbide and silver, but cannot remove the influence of free carbon, and the existence of free carbon still forms pores.
Patent CN103824710B discloses a method for preparing silver tungsten carbide contact material by silver-coated tungsten carbide powder and a product thereof, wherein wetting and combination of tungsten carbide and silver are improved by a coating method, free carbon is coated by silver during coating, but silver liquid coated outside the graphite is discharged by graphite during high-temperature silver liquid phase to form pores.
Patent CN108264048A discloses a method for removing free carbon in transition metal carbide, which mainly uses Ca-CaCl2Removal of free carbon and removal of CaC by acid leaching2The method has complicated process and introduces Ca and CaCl2And acid, etc. may have material residues that affect the infiltration and end-use properties of the material.
Disclosure of Invention
In order to solve the problems and the defects of the prior art, the invention aims to provide the silver tungsten carbide-molybdenum composite electrical contact material and the preparation method thereof.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a silver tungsten carbide-molybdenum composite electrical contact material, which comprises the following steps:
(1) pre-mixing powder: uniformly mixing tungsten carbide powder and molybdenum trioxide powder through ball milling to obtain first mixed powder;
(2) removing free carbon: under the inert atmosphere, sintering the first mixed powder at the temperature of 500-700 ℃ for 2-5 hours in a heat preservation way, and enabling free carbon in the tungsten carbide powder to fully react with the molybdenum trioxide powder to remove the free carbon and enable the molybdenum trioxide to be partially converted into molybdenum dioxide to obtain second mixed powder;
(3) mixing silver powder: mechanically and uniformly mixing the silver powder and the second mixed powder to obtain third mixed powder;
(4) sintering, granulating and reducing oxides: sintering the third mixed powder in a step sintering mode under a reducing atmosphere, wherein in the first step, the third mixed powder is sintered and insulated for 2-5 hours at the temperature of 500-;
(5) and (4) crushing, sieving and granulating the powder subjected to sintering treatment in the step (4), and pressing and infiltrating according to a conventional silver tungsten carbide process to obtain the silver tungsten carbide-molybdenum composite contact material.
The particle size of the tungsten carbide powder in the step (1) is further set as follows: 0.4-0.8 μm; the particle diameter of the molybdenum trioxide is as follows: 40-80 nm.
Further setting the mass ratio of the tungsten carbide powder to the molybdenum trioxide powder in the step (1) as follows: 50:2-50:1.
The mass ratio of the silver to the second mixed powder in the step (3) is further set as follows: 1:9-1:1.
Further setting is that the inert gas in the step (2) is argon.
It is further provided that the reducing atmosphere described in the step (4) is a hydrogen atmosphere or an ammonia decomposition atmosphere.
In addition, the invention also provides the silver tungsten carbide-molybdenum composite electrical contact material prepared by the preparation method.
In addition, the invention also provides silver tungsten carbide-molybdenum composite electrical contact material framework powder.
The invention has the advantages that:
the application realizes the innovative technical thought of the above invention: during infiltration of the silver tungsten carbide material, the influence of free carbon on the material cannot be solved, and particularly, the silver tungsten carbide material containing superfine tungsten carbide powder ensures that the performance of the superfine silver tungsten carbide material cannot be optimized to an optimal state. According to the invention, the problem of free carbon in tungsten carbide powder is solved by introducing molybdenum trioxide, molybdenum trioxide and a reaction intermediate product molybdenum dioxide are reduced into molybdenum in a reducing atmosphere, and the wettability of tungsten carbide and silver is improved by taking molybdenum as an additive, so that an ideal superfine silver tungsten carbide-molybdenum electrical contact composite material is obtained.
In order to ensure that the molybdenum trioxide powder is fully contacted with free carbon, the specific surface area of the molybdenum powder is increased by selecting the nano molybdenum trioxide powder, and the free carbon in the tungsten carbide is removed under the inert atmosphere at a certain temperature after the tungsten carbide powder and the nano molybdenum trioxide powder are premixed. And (3) removing free carbon, adding silver powder, mixing, reducing molybdenum trioxide into molybdenum dioxide in a stepped heat preservation mode under a reducing atmosphere, and then heating to reduce the molybdenum dioxide into molybdenum powder in order to prevent the molybdenum trioxide from volatilizing at high temperature.
According to the invention, free carbon in tungsten carbide is removed by adding the molybdenum oxide powder, and adverse effects brought by the free carbon are improved. Molybdenum which is the final reduction product of molybdenum trioxide is a high-melting-point and high-wear-resistance metal material and is also a common raw material of an electrical contact. Because molybdenum has certain solubility in silver at the conventional infiltration temperature, the wettability of molybdenum and silver is better, and the molybdenum powder and the tungsten carbide powder are fully contacted, the wettability relation of tungsten carbide and silver can be improved, so that the strength of the material after infiltration is improved. Through the optimization of the process, the problems of free carbon and wettability of tungsten carbide and silver are solved, the silver liquid can smoothly fill the pores around the tungsten carbide-molybdenum, so that the physical properties of the material such as conductivity, compactness, bonding strength and the like are further improved, and the electrical properties of the corresponding material such as burning loss resistance, electric arc resistance and the like are greatly improved when the material is used.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the following examples.
Example one
(1) Pre-mixing powder: weighing 4.9kg of tungsten carbide powder with the average particle size of 0.4 micron and 0.15kg of molybdenum trioxide powder with the average particle size of 40nm, and performing ball milling for 20 hours.
(2) Removing free carbon: and (2) sintering the tungsten carbide-molybdenum trioxide mixed powder at 500 ℃ for 3 hours under the inert atmosphere, so that free carbon in the tungsten carbide powder and the molybdenum trioxide powder fully react to remove the free carbon and partially convert the molybdenum trioxide into molybdenum dioxide.
(3) Mixing silver powder: 5kg of silver powder is weighed and mixed with the treated tungsten carbide powder in a powder mixing machine for 10 hours.
(4) Sintering, granulating and reducing oxides: sintering the mixed powder in a step sintering mode under a reducing atmosphere, wherein the mixed powder is sintered and insulated for 3 hours at 500 ℃ in the first step, and the mixed powder is sintered and insulated for 4 hours at 900 ℃ in the second step. The first step of sintering converts all molybdenum trioxide into molybdenum dioxide, and the second step of sintering converts molybdenum dioxide into molybdenum; after the molybdenum reduction is completed, a silver (tungsten carbide-molybdenum) 50 powder sintered body is obtained.
(5) And crushing, sieving and granulating the sintered powder, pressing into a silver (tungsten carbide-molybdenum) 50 framework according to a conventional silver tungsten carbide process, presintering for 2 hours at 900 ℃ under an ammonia decomposition atmosphere, and infiltrating for 40 minutes at 1080 ℃ under the ammonia decomposition atmosphere to obtain the silver (tungsten carbide-molybdenum) 35 composite contact material.
Example two
(1) Pre-mixing powder: 7.75kg of tungsten carbide powder with the average particle size of 0.5 micron and 0.375kg of molybdenum trioxide powder with the average particle size of 60nm are weighed, and the ball milling time is 15 hours.
(2) Removing free carbon: and (2) sintering the tungsten carbide-molybdenum trioxide mixed powder at 650 ℃ for 3.5 hours under the inert atmosphere, so that free carbon in the tungsten carbide powder and the molybdenum trioxide powder fully react to remove the free carbon and partially convert the molybdenum trioxide into molybdenum dioxide.
(3) Mixing silver powder: weighing 2kg of silver powder, and mixing the silver powder with the treated tungsten carbide powder in a powder mixer for 6 hours.
(4) Sintering, granulating and reducing oxides: sintering the mixed powder in a step sintering mode under a reducing atmosphere, wherein in the first step, the mixed powder is sintered and insulated for 4 hours at the temperature of 600 ℃, and in the second step, the mixed powder is sintered and insulated for 5 hours at the temperature of 1000 ℃. The first step of sintering converts all molybdenum trioxide into molybdenum dioxide, and the second step of sintering converts molybdenum dioxide into molybdenum; after the molybdenum reduction is completed, a silver (tungsten carbide-molybdenum) 80 powder sintered body is obtained.
(5) And crushing, sieving and granulating the sintered powder, pressing into a silver (tungsten carbide-molybdenum) 80 framework according to a silver tungsten carbide conventional process, presintering for 2 hours at 950 ℃ under an ammonia decomposition atmosphere, and infiltrating for 2 hours at 1100 ℃ under a vacuum atmosphere to obtain the silver (tungsten carbide-molybdenum) 60 composite contact material.
EXAMPLE III
(1) Pre-mixing powder: 6.3kg of tungsten carbide powder with the average particle size of 0.7 micron and 0.3kg of molybdenum trioxide powder with the average particle size of 80nm are weighed, and the ball milling time is 20 hours.
(2) Removing free carbon: and (2) sintering the tungsten carbide-molybdenum trioxide mixed powder at 550 ℃ for 2.5 hours under the inert atmosphere, so that free carbon in the tungsten carbide powder and the molybdenum trioxide powder fully react to remove the free carbon and partially convert the molybdenum trioxide into molybdenum dioxide.
(3) Mixing silver powder: 3.5kg of silver powder is weighed and mixed with the treated tungsten carbide powder in a powder mixing machine for 8 hours.
(4) Sintering, granulating and reducing oxides: and sintering the mixed powder in a step sintering mode under a reducing atmosphere, wherein in the first step, the mixed powder is sintered and insulated for 3 hours at 550 ℃, and in the second step, the mixed powder is sintered and insulated for 3.5 hours at 950 ℃. The first step of sintering converts all molybdenum trioxide into molybdenum dioxide, and the second step of sintering converts molybdenum dioxide into molybdenum; after the molybdenum reduction is completed, a silver (tungsten carbide-molybdenum) 65 powder sintered body is obtained.
(5) And crushing, sieving and granulating the sintered powder, pressing into a silver (tungsten carbide-molybdenum) 65 framework according to a conventional silver tungsten carbide process, presintering for 1 hour at 880 ℃ under an ammonia decomposition atmosphere, and infiltrating for 2 hours at 1050 ℃ under the ammonia decomposition atmosphere to obtain the silver (tungsten carbide-molybdenum) 45 composite contact material.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.
Claims (10)
1. A preparation method of a silver tungsten carbide-molybdenum composite electrical contact material is characterized by comprising the following steps:
(1) pre-mixing powder: uniformly mixing tungsten carbide powder and molybdenum trioxide powder through ball milling to obtain first mixed powder;
(2) removing free carbon: under the inert atmosphere, sintering the first mixed powder at the temperature of 500-700 ℃ for 2-5 hours in a heat preservation way, and enabling free carbon in the tungsten carbide powder to fully react with the molybdenum trioxide powder to remove the free carbon and enable the molybdenum trioxide to be partially converted into molybdenum dioxide to obtain second mixed powder;
(3) mixing silver powder: mechanically and uniformly mixing the silver powder and the second mixed powder to obtain third mixed powder;
(4) sintering, granulating and reducing oxides: sintering the third mixed powder in a step sintering mode under a reducing atmosphere, wherein in the first step, the third mixed powder is sintered and insulated for 2-5 hours at the temperature of 500-;
(5) and (4) crushing, sieving and granulating the powder subjected to sintering treatment in the step (4), and pressing and infiltrating according to a conventional silver tungsten carbide process to obtain the silver tungsten carbide-molybdenum composite contact material.
2. The method of making a silver tungsten carbide-molybdenum composite electrical contact material of claim 1, wherein: the particle size of the tungsten carbide powder in the step (1) is as follows: 0.4-0.8 μm; the particle diameter of the molybdenum trioxide is as follows: 40-80 nm.
3. The method of making a silver tungsten carbide-molybdenum composite electrical contact material of claim 1, wherein: the mass ratio of the tungsten carbide powder to the molybdenum trioxide powder in the step (1) is as follows: 50:2-50:1.
4. The method of making a silver tungsten carbide-molybdenum composite electrical contact material of claim 1, wherein: the mass ratio of the silver to the second mixed powder in the step (3) is as follows: 1:9-1:1.
5. The method of making a silver tungsten carbide-molybdenum composite electrical contact material of claim 1, wherein: and (3) in the step (2), the inert gas is argon.
6. The method of making a silver tungsten carbide-molybdenum composite electrical contact material of claim 1, wherein: the reducing atmosphere in the step (4) is a hydrogen atmosphere or an ammonia decomposition atmosphere.
7. A silver tungsten carbide-molybdenum composite electrical contact material prepared by the preparation method according to any one of claims 1 to 6.
8. The framework powder of the silver tungsten carbide-molybdenum composite electrical contact material is characterized by being prepared by the following steps:
(1) pre-mixing powder: uniformly mixing tungsten carbide powder and molybdenum trioxide powder through ball milling to obtain first mixed powder;
(2) removing free carbon: under the inert atmosphere, sintering the first mixed powder at the temperature of 500-700 ℃ for 2-5 hours in a heat preservation way, and enabling free carbon in the tungsten carbide powder to fully react with the molybdenum trioxide powder to remove the free carbon and enable the molybdenum trioxide to be partially converted into molybdenum dioxide to obtain second mixed powder;
(3) mixing silver powder: mechanically and uniformly mixing the silver powder and the second mixed powder to obtain third mixed powder;
(4) sintering, granulating and reducing oxides: sintering the third mixed powder in a step sintering mode under a reducing atmosphere, wherein in the first step, the third mixed powder is sintered and insulated for 2-5 hours at the temperature of 500-;
(5) and (4) crushing, sieving and granulating the powder sintered in the step (4).
9. The skeletal powder of claim 8, wherein: the particle size of the tungsten carbide powder in the step (1) is as follows: 0.4-0.8 μm; the particle diameter of the molybdenum trioxide is as follows: 40-80 nm.
10. The skeletal powder of claim 1, wherein: the mass ratio of the tungsten carbide powder to the molybdenum trioxide powder in the step (1) is as follows: 50:2-50:1, wherein the mass ratio of the silver to the second mixed powder in the step (3) is as follows: 1:9-1:1.
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