CN114951665B - Preparation method of low-cost high-density high-conductivity copper-chromium contact - Google Patents
Preparation method of low-cost high-density high-conductivity copper-chromium contact Download PDFInfo
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- CN114951665B CN114951665B CN202210546076.9A CN202210546076A CN114951665B CN 114951665 B CN114951665 B CN 114951665B CN 202210546076 A CN202210546076 A CN 202210546076A CN 114951665 B CN114951665 B CN 114951665B
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- GXDVEXJTVGRLNW-UHFFFAOYSA-N [Cr].[Cu] Chemical compound [Cr].[Cu] GXDVEXJTVGRLNW-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 64
- 239000000843 powder Substances 0.000 claims abstract description 63
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 58
- 238000005245 sintering Methods 0.000 claims abstract description 54
- 238000000498 ball milling Methods 0.000 claims abstract description 48
- 229910000599 Cr alloy Inorganic materials 0.000 claims abstract description 44
- 239000000788 chromium alloy Substances 0.000 claims abstract description 44
- 229910052802 copper Inorganic materials 0.000 claims abstract description 40
- 239000010949 copper Substances 0.000 claims abstract description 40
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 36
- 239000011651 chromium Substances 0.000 claims abstract description 36
- 239000007791 liquid phase Substances 0.000 claims abstract description 22
- 238000001816 cooling Methods 0.000 claims abstract description 21
- 238000002844 melting Methods 0.000 claims abstract description 21
- 230000008018 melting Effects 0.000 claims abstract description 21
- 229910052751 metal Inorganic materials 0.000 claims abstract description 21
- 239000002184 metal Substances 0.000 claims abstract description 21
- 239000011812 mixed powder Substances 0.000 claims abstract description 21
- 238000003825 pressing Methods 0.000 claims abstract description 21
- ZTXONRUJVYXVTJ-UHFFFAOYSA-N chromium copper Chemical compound [Cr][Cu][Cr] ZTXONRUJVYXVTJ-UHFFFAOYSA-N 0.000 claims abstract description 18
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 14
- 239000001257 hydrogen Substances 0.000 claims abstract description 14
- 238000001556 precipitation Methods 0.000 claims abstract description 11
- 230000032683 aging Effects 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 19
- 238000007723 die pressing method Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 8
- 239000002994 raw material Substances 0.000 abstract description 6
- 238000005272 metallurgy Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 238000010079 rubber tapping Methods 0.000 description 10
- 238000000926 separation method Methods 0.000 description 10
- 238000005303 weighing Methods 0.000 description 10
- 239000007790 solid phase Substances 0.000 description 7
- 239000011159 matrix material Substances 0.000 description 6
- 238000000280 densification Methods 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 238000010587 phase diagram Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000002679 ablation Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000001192 hot extrusion Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- 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
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- 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
- B22F3/02—Compacting only
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- 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
- B22F3/1003—Use of special medium during sintering, e.g. sintering aid
- B22F3/1007—Atmosphere
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- 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
- B22F3/1035—Liquid phase sintering
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0425—Copper-based alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/045—Alloys based on refractory metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C27/06—Alloys based on chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
- H01H1/025—Composite material having copper as the basic material
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- 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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
- B22F2003/248—Thermal after-treatment
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- 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
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
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Abstract
The invention relates to the field of metallurgy, and discloses a preparation method of a low-cost high-density high-conductivity copper-chromium contact, which comprises the following steps: (1) Performing vacuum ball milling on the copper-chromium alloy powder, the metal chromium powder and the electrolytic copper powder to obtain chromium-copper-chromium alloy-copper mixed powder; (2) Carrying out mould pressing and pressing on the chromium-copper-chromium alloy-copper mixed powder; (3) Carrying out partial liquid phase sintering on the pressed compact in vacuum or hydrogen atmosphere; (4) And cooling to the aging precipitation temperature, preserving heat, and continuously cooling to room temperature after chromium precipitation to obtain the copper-chromium contact. The invention adopts three raw materials and sintering at the temperature higher than the melting point of copper-chromium alloy powder and lower than the melting point of electrolytic copper, thus obtaining the copper-chromium contact with high compactness and high conductivity. The green body is uniformly shrunk after sintering, the size is controllable, and the copper-chromium contact is only contained with copper or chromium components, so that the copper-chromium contact is not influenced.
Description
Technical Field
The invention relates to the field of metallurgy, in particular to a preparation method of a low-cost high-density high-conductivity copper-chromium contact.
Background
Copper-chromium contact materials are widely used in medium-high voltage vacuum switches because of their excellent breaking properties, fusion welding resistance, arc ablation resistance and high electrical and thermal conductivity, wherein copper is a matrix component and the weight ratio varies between 50 and 75%. At present, four processes are mainly used for producing copper-chromium contact materials, namely a powder mixing sintering method, an infiltration method, a vacuum casting method and an arc melting method.
The mixed powder sintering method is a main method for producing the copper-chromium contact because of high material utilization rate, low energy consumption and high product performance consistency, and is divided into a solid phase sintering method and a liquid phase sintering method, however, the density of the copper-chromium material produced by the solid phase sintering method is relatively low, so that the process also needs to carry out densification subsequent treatment such as re-pressing and re-sintering, hot extrusion, hot forging and the like, thereby greatly increasing the production cost of the contact and greatly increasing the production period; conventional liquid phase sintering generally requires a liquid phase content of less than 30%, however, the content of liquid phase source-copper in the copper-chromium contact is too large to reach 50-75%, and copper leakage, collapse or serious deformation of a blank body can occur due to excessive liquid phase during sintering, so that the method is not applicable.
Disclosure of Invention
In order to solve the technical problems, the invention provides a preparation method of a low-cost high-density high-conductivity copper-chromium contact. The invention adopts three raw materials and sintering at the temperature higher than the melting point of copper-chromium alloy powder and lower than the melting point of electrolytic copper, thus obtaining the copper-chromium contact with high compactness and high conductivity. The green body is uniformly shrunk after sintering, the size is controllable, and the copper-chromium contact is only contained with copper or chromium components, so that the copper-chromium contact is not influenced.
The specific technical scheme of the invention is as follows: a preparation method of a low-cost high-density high-conductivity copper-chromium contact comprises the following steps:
(1) And carrying out vacuum ball milling on the copper-chromium alloy powder, the metal chromium powder and the electrolytic copper powder together, and taking out after ball milling is finished to obtain chromium-copper-chromium alloy-copper mixed powder.
(2) And carrying out compression molding on the chromium-copper chromium alloy-copper mixed powder.
(3) Taking out the pressed compact after pressing, carrying out partial liquid phase sintering in vacuum or hydrogen atmosphere, heating to a sintering temperature which is not lower than the melting temperature of copper-chromium alloy powder and lower than the melting temperature of electrolytic copper powder, and cooling along with a furnace after heat preservation.
(4) And cooling to the aging precipitation temperature, preserving heat, and continuously cooling to room temperature after chromium in the copper-chromium alloy is precipitated, so as to obtain the low-cost high-density high-conductivity copper-chromium contact.
In the step (1), three raw materials, namely copper-chromium alloy powder, electrolytic copper powder and metal chromium powder, are subjected to ball milling treatment, and high-uniformity mixed powder can be obtained after ball milling. In the step (2), the mixed powder is pressed, so that the density is improved, and preparation is carried out for subsequent sintering.
In step (3), the invention performs sintering under vacuum or hydrogen atmosphere at a temperature above the melting point of the copper-chromium alloy powder and below the melting point of electrolytic copper. In the high-temperature sintering process, copper-chromium alloy powder is melted to form a liquid phase, electrolytic copper powder and metal chromium powder are in a solid phase state, at the moment, solid phase particles are adjusted in position within a certain scale due to capillary force formed by copper-chromium alloy liquid in gaps between the electrolytic copper powder and the metal chromium powder and viscous flow of the liquid phase, and are distributed in the most compact arrangement, and after heat preservation, the copper-chromium contact with high density and high conductivity is obtained through rapid densification. Compared with the conventional solid-phase sintering, the method does not need to carry out subsequent densification treatment; compared with the conventional liquid phase sintering, the sintering process has the advantages that the content of a liquid phase source (copper-chromium alloy powder) is adjustable, so that the blank body is uniformly contracted after sintering, the size is controllable, and the copper-chromium contact component is not influenced because the copper-chromium contact component only contains copper or chromium.
In the step (4), because chromium is dissolved in copper in a solid solution mode and copper-chromium alloy powder is used in the high-temperature liquid phase sintering in the previous step, a large amount of chromium is dissolved in a copper matrix in a solid solution mode, and the conductivity of the copper matrix is seriously affected.
Preferably, in step (1): the content of chromium in the copper-chromium alloy powder is 0.9 to 1.3 weight percent.
Preferably, in step (1): the granularity of the copper-chromium alloy powder is 800-2000 meshes; the granularity of the metal chromium powder is 120-500 meshes; the electrolytic copper powder is 200-350 meshes.
The step uses finer copper-chromium alloy powder because the finer alloy powder is filled in the pores of the electrolytic copper powder and the metal chromium powder in the mixing and pressing processes, thereby improving the density.
Preferably, in step (1): the copper-chromium alloy powder accounts for 15-25% of the total weight of the contact, and the metal-chromium powder accounts for 25-50% of the total weight of the contact; the electrolytic copper powder occupies the balance of the contact.
Preferably, in step (1): the ball-milling ball material ratio is 3:1-5:1; the ball milling time is 60-120 min.
Preferably, in step (1): the ball milling adopts pure chromium balls.
Preferably, in step (2): the pressure of the die pressing is 500-800 MPa, and the pressure maintaining time is 1-3 s.
Preferably, in step (3): the sintering temperature is 1078-1082 ℃, the heating time is 30-60 min, and the heat preservation time is 10-30 min.
Preferably, in step (4): the aging precipitation temperature is 450-550 ℃, and the heat preservation time is 120-300 min.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention adopts three raw materials, namely copper-chromium alloy powder, electrolytic copper powder and metallic chromium powder, and starts sintering at a temperature higher than the melting point of the copper-chromium alloy powder and lower than the melting point of pure copper in vacuum or hydrogen atmosphere. In the sintering process, the copper-chromium alloy powder is melted, the electrolytic copper powder and the metal chromium powder are in a solid phase state, and after heat preservation treatment, the copper-chromium contact with high density and high conductivity is obtained by rapid densification without subsequent densification treatment.
(2) The liquid phase sintering process has the advantages that the number of liquid phase sources (copper-chromium alloy powder) is adjustable, so that the blank body is uniformly contracted after sintering, the size is controllable, and the liquid phase sintering process only contains copper or chromium components and cannot influence the copper-chromium contact components.
Drawings
FIG. 1 is a golden phase diagram of a copper-chromium 30 contact prepared in example 1;
fig. 2 is a golden phase diagram of a copper-chromium 30 contact prepared in comparative example 6.
Detailed Description
The invention is further described below with reference to examples.
General examples
A preparation method of a low-cost high-density high-conductivity copper-chromium contact comprises the following steps:
(1) Vacuum ball milling (pure chromium ball, ball-to-material ratio is 3:1-5:1, 60-120 min) is carried out on copper-chromium alloy powder (800-2000 meshes, chromium content is 0.9-1.3 wt%), metal chromium powder (120-500 meshes) and electrolytic copper powder (200-350 meshes) together, and the mixed powder of chromium-copper-chromium alloy and copper is obtained after ball milling is finished. Wherein, the copper-chromium alloy powder accounts for 15-25% of the total weight, and the metal chromium powder accounts for 25-50%; the electrolytic copper powder accounts for the balance.
(2) And (3) carrying out mould pressing and pressing on the chromium-copper-chromium alloy-copper mixed powder, wherein the pressing pressure is 500-800 MPa, and the pressure maintaining time is 1-3 s.
(3) Taking out the pressed compact after pressing, carrying out partial liquid phase sintering in vacuum or hydrogen atmosphere, heating to sintering temperature (not lower than melting temperature of copper-chromium alloy powder and lower than melting temperature of electrolytic copper powder, preferably 1078-1082 ℃) for 30-60 min, preserving heat for 10-30 min, and cooling along with a furnace.
(4) Cooling to the aging precipitation temperature of 450-550 ℃, preserving heat for 120-300 min, and continuously cooling to room temperature after chromium precipitation to obtain the low-cost high-density high-conductivity copper-chromium contact.
Example 1
Respectively weighing copper-chromium alloy powder with 1000 meshes of granularity and 1% of chromium content, high-purity metal chromium powder with 200 meshes of granularity and electrolytic copper powder with 250 meshes of granularity according to the proportion of 15%,29.85% and 55.15% of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. Sintering the pressed compact in a hydrogen furnace for 30min to 1078 ℃, preserving heat for 15min and then cooling. And (5) keeping the temperature for 240min when the temperature is reduced to 500 ℃, and then reducing the temperature to the tapping temperature to obtain the copper-chromium 30 contact.
As shown in fig. 1, the copper-chromium 30 contact prepared in example 1 has uniform copper-chromium distribution, no holes and precipitated fine chromium particles are dispersed in a copper matrix.
Example 2
Respectively weighing copper-chromium alloy powder with 1500 meshes of granularity and 1.2 percent of chromium content, high-purity metal chromium powder with 400 meshes of granularity and electrolytic copper powder with 300 meshes of granularity according to the proportion of 20 percent, 39.76 percent and 40.24 percent of the total weight, adding the powder into a ball milling tank, adding 4 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 90 minutes, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 700MPa, the dwell time is 2s, and then demoulding to obtain a pressed compact. Sintering the pressed compact in a vacuum furnace for 40min to 1080 ℃, preserving heat for 20min, and then cooling. And (5) keeping the temperature for 180 minutes when the temperature is reduced to 520 ℃, and then reducing the temperature to the tapping temperature to obtain the high-density high-conductivity copper-chromium 40 contact.
Example 3
Respectively weighing copper-chromium alloy powder with 800 meshes and 1 percent of chromium content, high-purity metal chromium powder with 120 meshes and electrolytic copper powder with 200 meshes according to the proportion of 25 percent, 49.75 percent and 25.25 percent of the total weight, adding the powder into a ball milling tank, adding pure chromium balls with 5 times of the weight, closing the ball milling tank, vacuumizing, performing ball milling for 120 minutes, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 800MPa, the dwell time is 6s, and then demoulding to obtain a pressed compact. Sintering the pressed compact in a vacuum furnace for 50min to 1082 ℃, preserving heat for 25min and then cooling. And (5) keeping the temperature for 300min when the temperature is reduced to 480 ℃, and then reducing the temperature to the tapping temperature to obtain the high-density high-conductivity copper-chromium 50 contact.
Comparative example 1
The difference from example 1 is only that no copper-chromium alloy powder is used and conventional solid phase sintering is employed
Respectively weighing high-purity metal chromium powder with the granularity of 200 meshes and electrolytic copper powder with the granularity of 250 meshes according to the proportion of 30% and 70% of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. And (3) placing the pressed compact into a hydrogen furnace for sintering, heating to 1078 ℃ for 30min, preserving heat for 15min, and cooling to the tapping temperature to obtain the copper-chromium 30 contact.
Comparative example 2
The difference from example 1 is only that no copper-chromium alloy powder is used and conventional liquid phase sintering is employed
Respectively weighing high-purity metal chromium powder with the granularity of 200 meshes and electrolytic copper powder with the granularity of 250 meshes according to the proportion of 30% and 70% of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. And (3) placing the pressed compact into a hydrogen furnace for sintering, heating to 1090 ℃ for 30min, preserving heat for 15min, and cooling to the tapping temperature to obtain the copper-chromium 30 contact.
Comparative example 3
The difference from example 1 is only that the copper-chromium alloy powder is used entirely without electrolytic copper powder
Respectively weighing copper-chromium alloy powder with 1000 meshes and 1 percent of chromium content and electrolytic copper powder with 250 meshes according to the proportion of 29.3 percent and 70.7 percent of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls with the weight, closing the ball milling tank, vacuumizing, performing ball milling for 60 minutes, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. And (3) placing the pressed compact into a hydrogen furnace for sintering, heating to 1078 ℃ for 30min, preserving heat for 15min, and cooling to the tapping temperature to obtain the copper-chromium 30 contact.
Comparative example 4
The difference from example 1 is only that the sintering temperature is below the melting point of the copper-chromium alloy
Respectively weighing copper-chromium alloy powder with 1000 meshes of granularity and 1% of chromium content, high-purity metal chromium powder with 200 meshes of granularity and electrolytic copper powder with 250 meshes of granularity according to the proportion of 15%,29.85% and 55.15% of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. Sintering the pressed compact in a hydrogen furnace for 30min to 1070 ℃, preserving heat for 15min and then cooling. And (5) keeping the temperature for 240min when the temperature is reduced to 500 ℃, and then reducing the temperature to the tapping temperature to obtain the copper-chromium 30 contact.
Comparative example 5
The difference from example 1 is that the sintering temperature is above the melting point of pure copper
Respectively weighing copper-chromium alloy powder with 1000 meshes of granularity and 1% of chromium content, high-purity metal chromium powder with 200 meshes of granularity and electrolytic copper powder with 250 meshes of granularity according to the proportion of 15%,29.85% and 55.15% of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. Sintering the pressed compact in a hydrogen furnace for 30min to 1090 ℃, preserving heat for 15min, and cooling. And (5) keeping the temperature for 240min when the temperature is reduced to 500 ℃, and then reducing the temperature to the tapping temperature to obtain the copper-chromium 30 contact.
Comparative example 6
The difference from example 1 is that the aging precipitation treatment was not performed
Respectively weighing copper-chromium alloy powder with 1000 meshes of granularity and 1% of chromium content, high-purity metal chromium powder with 200 meshes of granularity and electrolytic copper powder with 250 meshes of granularity according to the proportion of 15%,29.85% and 55.15% of the total weight, adding the powder into a ball milling tank, adding 3 times of pure chromium balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. And (3) placing the pressed compact into a hydrogen furnace for sintering, heating to 1078 ℃ for 30min, preserving heat for 15min, and cooling to the tapping temperature to obtain the copper-chromium 30 contact.
Comparative example 7
The difference from example 1 is only that the ball milling uses conventional iron balls
Respectively weighing copper-chromium alloy powder with 1000 meshes of granularity and 1% of chromium content, high-purity metal chromium powder with 200 meshes of granularity and electrolytic copper powder with 250 meshes of granularity according to the proportion of 15%,29.85% and 55.15% of the total weight, adding the powder into a ball milling tank, adding 3 times of iron balls, closing the ball milling tank, vacuumizing, performing ball milling for 60min, taking out, and performing ball material separation by using a copper wire screen to obtain the chromium-copper-chromium alloy-copper mixed powder. And (3) placing the powder obtained in the previous step into a die for die pressing, wherein the pressing pressure is 600MPa, the dwell time is 1s, and then demoulding to obtain a pressed compact. Sintering the pressed compact in a hydrogen furnace for 30min to 1078 ℃, preserving heat for 15min and then cooling. And (5) keeping the temperature for 240min when the temperature is reduced to 500 ℃, and then reducing the temperature to the tapping temperature to obtain the copper-chromium 30 contact.
Performance testing
The copper-chromium contacts prepared in each example and comparative example were tested for performance and the results are shown in the following table:
from the above table data, it can be seen that:
(1) The copper-chromium materials prepared in examples 1, 2 and 3 have the characteristics of high relative density, high conductivity and high hardness, and the comprehensive performance is generally superior to that of each comparative example; fig. 1 is a gold phase diagram of example 1, showing that the copper-chromium material is in a fully dense state without voids, and fine chromium particles are dispersed in the copper matrix.
(2) The sintering temperatures of comparative example 1 and comparative example 4 were below the melting point of each component of the contact, and no liquid phase appeared at the time of sintering, so the relative density was low and the conductivity was also low.
(3) In comparative example 2, when the copper powder is sintered at 1090 ℃, the melting point of the electrolytic copper powder is exceeded, the proportion of the liquid phase is up to 70%, the sintered blank is difficult to maintain the original shape, serious collapse and copper leakage occur, serious unevenness of the structure is caused, and the conductivity and hardness cannot be tested.
(4) In comparative example 3, only copper-chromium alloy powder was used, but since the sintering temperature was higher than the melting point of the copper-chromium alloy powder, a large amount of liquid phase was also present, resulting in contact collapse and copper leakage.
(5) In comparative example 5, copper-chromium alloy powder and electrolytic copper powder were used, but the sintering temperature was higher than the melting points of the two powders, and the liquid phase ratio was too high during sintering, so that the copper-chromium contact collapsed and copper leakage occurred.
(6) In comparative example 6, no aging precipitation treatment was performed, so that chromium precipitation in the copper matrix was small, and the conductivity was low. The golden phase diagram is shown in figure 2.
(7) Comparative example 7 since iron balls were used during ball milling, trace iron was introduced into the powder during ball milling, and iron was diffused in copper during final sintering, resulting in a decrease in conductivity.
The raw materials and equipment used in the invention are common raw materials and equipment in the field unless specified otherwise; the methods used in the present invention are conventional in the art unless otherwise specified.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent transformation of the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.
Claims (9)
1. The preparation method of the low-cost high-density high-conductivity copper-chromium contact is characterized by comprising the following steps of:
(1) Carrying out vacuum ball milling on copper-chromium alloy powder, metal chromium powder and electrolytic copper powder with the chromium content of 0.9-1.3 wt%, and taking out after ball milling is finished to obtain chromium-copper-chromium alloy-copper mixed powder;
(2) Carrying out mould pressing on the chromium-copper-chromium alloy-copper mixed powder;
(3) Taking out the pressed compact after pressing, carrying out partial liquid phase sintering in vacuum or hydrogen atmosphere, heating to a sintering temperature which is not lower than the melting temperature of copper-chromium alloy powder and lower than the melting temperature of electrolytic copper powder, and cooling along with a furnace after heat preservation;
(4) And cooling to the aging precipitation temperature, preserving heat, and continuously cooling to room temperature after the chromium in the copper-chromium alloy is precipitated, so as to obtain the low-cost high-density high-conductivity copper-chromium contact.
2. The method of manufacturing according to claim 1, wherein: in step (1):
the granularity of the copper-chromium alloy powder is 800-2000 meshes;
the granularity of the metal chromium powder is 120-500 meshes;
the granularity of the electrolytic copper powder is 200-350 meshes.
3. The method of manufacturing according to claim 1, wherein: in step (1): the copper-chromium alloy powder accounts for 15-25% of the total weight of the contact, and the metal-chromium powder accounts for 25-50% of the total weight of the contact; the electrolytic copper powder occupies the balance of the contact.
4. The method of manufacturing according to claim 1, wherein: in step (1):
the ball-milling ball material ratio is 3:1-5:1;
the ball milling time is 60-120 min.
5. The method of manufacturing according to claim 4, wherein: in step (1): the ball milling adopts pure chromium balls.
6. The method of manufacturing according to claim 1, wherein: in the step (2): the pressure of the die pressing is 500-800 MPa, and the pressure maintaining time is 1-3 s.
7. The method of manufacturing according to claim 1, wherein: in the step (3): the sintering temperature is 1078-1082 ℃, the heating time is 30-60 min, and the heat preservation time is 10-30 min.
8. The method of manufacturing according to claim 1, wherein: in the step (4): the aging precipitation temperature is 450-550 ℃, and the heat preservation time is 120-300 min.
9. A highly dense, highly conductive copper-chromium contact made by the method of any one of claims 1-8.
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