CN110295294B - Preparation method for optimizing copper-chromium contact by adding superfine crystal chromium phase - Google Patents
Preparation method for optimizing copper-chromium contact by adding superfine crystal chromium phase Download PDFInfo
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- CN110295294B CN110295294B CN201910530438.3A CN201910530438A CN110295294B CN 110295294 B CN110295294 B CN 110295294B CN 201910530438 A CN201910530438 A CN 201910530438A CN 110295294 B CN110295294 B CN 110295294B
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
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Abstract
The invention discloses a preparation method of a copper-chromium contact optimized by adding an ultrafine crystal chromium phase, and belongs to the technical field of medium-voltage vacuum switches. The method mainly comprises the following steps: (1) preparing materials; (2) vacuum induction melting; (3) atomizing to prepare powder; (4) mixing the powder; (5) pressing and sintering; (6) machining; the invention adopts a mixed powder sintering process to prepare the copper-chromium alloy contact on the basis of vacuum induction gas atomization, adopts vacuum induction gas atomization to prepare copper-chromium alloy powder, thereby providing a very fine chromium phase for the contact, and then adopts a solid phase sintering process to prepare the copper-chromium contact meeting the requirement of chromium content by adding conventional chromium powder, so that the contact not only avoids the gas content exceeding standard caused by pursuing fine chromium particles in the conventional production mode, but also greatly optimizes the contact performance because the size of the chromium phase is far smaller than that of the conventional chromium powder; the copper-chromium contact prepared by the method has low cost and excellent performance, and is suitable for industrial batch production.
Description
Technical Field
The invention belongs to the technical field of medium-voltage vacuum switches, and particularly relates to a preparation method of a copper-chromium contact optimized by adding an ultrafine crystal chromium phase.
Background
The copper-chromium alloy contact is a core component in the field of medium-voltage vacuum switches, and through years of research, the size of a chromium phase in a metallographic structure of the copper-chromium alloy contact is considered to be reduced, so that the electrical property and the mechanical property of a material can be greatly optimized, the mainstream preparation process of the copper-chromium alloy contact at present mainly comprises two types of smelting and powder metallurgy, the copper-chromium alloy contact prepared by conventional vacuum induction smelting has low cooling speed and generally larger chromium phase size, and the chromium phase size in a central area and an edge area of the contact is greatly different, so that even if an advanced electric arc smelting process is adopted, the cooling speed is further improved, but the chromium phase size is still kept between 20 and 50 microns, the size of an electric arc spot in a working condition environment is still larger, and the copper-chromium contact is not beneficial to fusion welding resistance under the service condition of the contact due to good mechanical property of an as-cast structure, but is prepared by adopting a mixed powder sintering process, although the problem of fusion welding resistance of the contact is solved well, the fusion welding resistance is limited by the original size of chromium powder, the size of a chromium phase is larger than that of a smelting process, the smelting process is not beneficial to the electrical performance requirement of the contact, the electrode induction smelting gas atomization process can be used for preparing powder with a very small chromium phase and is used for mixed powder sintering to prepare the copper-chromium contact, the electrode induction smelting gas atomization process is low in efficiency and not suitable for industrial batch production, and the process is limited, the argon gas consumption in the gas atomization process is very high, and huge production cost is formed, so that the practical application of the process is greatly limited.
Disclosure of Invention
Aiming at the problems, the invention provides a preparation method of the optimized copper-chromium contact by adding the ultrafine crystal chromium phase, which has low cost and excellent performance.
The technical scheme of the invention is as follows: a preparation method for optimizing a copper-chromium contact by adding an ultrafine crystal chromium phase mainly comprises the following steps:
(1) ingredients
Taking a Cu rod, a Cr block and conventional Cr powder as raw materials for later use, wherein the mesh number of the conventional Cr powder is-80 + 320;
(2) vacuum induction melting
According to the weight ratio of 19: 1-4: 1, putting the Cu rod and the Cr block into a ceramic crucible in a vacuum induction melting furnace, vacuumizing until the vacuum degree reaches 9 multiplied by 10-1When the pressure is less than Pa, the ceramic crucible is subjected to gradient additionHeating by a thermal power mode to melt the raw materials, closing a vacuum system when Cu starts to melt, introducing argon or other inert gases until the vacuum degree is-0.08-0.02 MPa, simultaneously preheating a tundish, keeping the power at 7-45KW, waiting until the molten metal is completely melted, uniformly stirring, keeping the superheat degree at 100-200 ℃ according to the components of the molten metal, and preparing for atomization;
(3) atomized powder
Filling argon into a vacuum melting system, ensuring that the vacuum melting system is in a micro-positive pressure state, starting high-pressure argon flow in an atomization system when the temperature of a tundish is detected to be more than or equal to the melting point of the alloy, wherein the pressure of the atomization argon flow is 2-8MPa, pouring molten metal in a ceramic crucible into the tundish, enabling the molten metal to flow through a high-pressure argon injection area through a guide pipe, atomizing and crushing the molten metal into a large number of fine liquid drops by the high-pressure argon flow, and solidifying the fine liquid drops into particles in flight, wherein the size of a chromium phase reaches 200nm-5 mu m, and selecting CuCr alloy powder with the powder particle size of-100 meshes as a subsequent raw;
(4) mixed powder
Mixing the CuCr alloy powder and conventional Cr powder according to the weight ratio of 3: 1-1: 1 to obtain mixed powder, and then mixing the mixed powder with steel balls according to a ball-to-material ratio of 100: 100, mixing, and mixing powder, wherein the mixing time is 3-10 h;
(5) pressing and sintering
Pressing the uniformly mixed powder by adopting a mould pressing mode, wherein the density is more than 95%, and then carrying out vacuum sintering, wherein the vacuum degree is 5 multiplied by 10-2Pa grade below, and keeping the temperature for 3-5h at 950-1050 ℃.
(6) Machining
And (5) machining according to the drawing requirements.
Further, the specific steps of the gradient heating power mode in the step (2) are as follows: s1: heating the ceramic crucible with 35-45KW of power, and keeping the temperature for 10-15 min; s2: heating power is increased to 55-65KW, and heat preservation is carried out for 7-8 min; s3: and increasing the heating power to 75-85KW again, and reducing the heating power to 7-30KW when the Cu starts to melt, and keeping until the molten metal is completely melted.
Further, the purity of the high-pressure argon in the steps (2) and (3) is 99.99%, the gas flow velocity is 230-750m/s, the high-purity argon is used for atomizing to prepare powder, the purity of the prepared metal powder is ensured, and the particle size of the metal powder is conveniently controlled through the range of the gas flow velocity.
Further, in the CuCr alloy powder obtained in the step (3), the Cr content accounts for 5-20%, the chromium content in the CuCr alloy obtained after pressing and sintering in the step (5) is 25-50%, because the copper-chromium alloy has high viscosity and fast heat dissipation, when the chromium content is higher than 20%, a package blocking phenomenon is easy to occur in an atomization process, the Cr content accounts for 5-20%, the chromium content is increased by adding conventional chromium powder subsequently, and finally, the copper-chromium alloy with the chromium content of 25-50% is prepared by adopting a mixed powder sintering process, so that the requirement for preparing the copper-chromium alloy contact is met.
Further, the powder mixing in the step (4) is carried out in a ball mill, and the specific process is as follows: adding the mixed powder and the steel balls into a mixer, adding a ball milling aid into the mixer, mixing the materials at the rotating speed of 10-30 r/min for 3-10h, spraying water to a grinding head or a grinding tail of the ball mill during ball milling, controlling the temperature in the ball mill to be 60-80 ℃ through cooling water, enabling the ball mill to be easier to grind by adding the ball milling aid, improving the yield of the ball mill, and better protecting devices in equipment.
Furthermore, the ball milling auxiliary agent is polyvinylpyrrolidone, and the addition of polyvinylpyrrolidone can reduce ball milling resistance and improve ball milling quality.
Further, before the mixed powder after ball milling is pressed in the step (5), the mixed powder is added into an absolute ethyl alcohol solution and uniformly mixed, then an alternating high-frequency pulse electric field is introduced into the mixed solution, so that the mixed solution is uniformly dispersed for 35-50min under the action of the alternating high-frequency pulse electric field at the temperature of 100 ℃ and 120 ℃, then the treated mixed solution is subjected to centrifugal separation, microfiltration membrane filtration and drying, and the powder after ball milling is subjected to the treatment, so that the powder is uniformly dispersed and is not easy to agglomerate, and the material prepared by pressing, sintering and molding the dispersed alloy powder has excellent mechanical property and good electrical property, and the electrical life of the contact is effectively prolonged.
Furthermore, the electric field intensity of the alternating high-frequency pulse electric field is 45-70kV/cm, the pulse width is 20-35 mus, and the pulse frequency is 500-1000Hz, and the dispersion effect of the high-frequency pulse electric field is optimized by treating the mixed liquid by the high-frequency pulse electric field with the parameters.
Further, the surface treatment is carried out on the metal contact finished product after the pressing and sintering treatment in the step (5), and the specific treatment process is as follows: placing the prepared metal contact finished product into a vacuum environment, scanning the surface of the metal contact finished product by using a plasma generator, rotating the prepared metal contact finished product in different directions in the scanning process, wherein the angle between a plasma beam and the metal contact finished product is always kept at an included angle of 45-50 degrees, the scanning speed is 6-12mm/s, the frequency of plasma is 330-, the processing efficiency is improved.
The invention has the beneficial effects that:
(1) the invention adopts a mixed powder sintering process to prepare the copper-chromium alloy contact on the basis of vacuum induction gas atomization, adopts vacuum induction gas atomization to prepare copper-chromium alloy powder, thereby providing a very fine chromium phase for the contact, and then adopts a solid phase sintering process to prepare the copper-chromium contact meeting the requirement of chromium content by adding conventional chromium powder.
(2) The invention obtains the copper-chromium alloy powder with the chromium phase size of 200nm-5um in batches with lower cost through the quenching of vacuum induction gas atomization, but because the copper-chromium alloy has large viscosity and fast heat dissipation, when the chromium content is higher than 20 percent of the alloy, the atomization process is easy to have the phenomenon of package blocking, through test verification, the Cr content of the copper-chromium alloy powder prepared by the process is considered to be less than or equal to 20 percent, the Cr content is improved by adding the conventional Cr powder subsequently, and finally, the copper-chromium alloy contact with the Cr content of 25-50 percent is prepared by adopting the mixed powder sintering process, and the contact has extremely small chromium phase size compared with the mixed powder sintered copper-chromium contact prepared by adopting the conventional chromium powder, so the performance is more excellent compared with the mixed powder sintered contact prepared by adopting the conventional chromium powder to atomize the copper-chromium alloy, the cost is extremely low, and the method is suitable for industrial batch production.
(3) When the ball mill is used for ball milling, the ball milling resistance can be reduced and the ball milling quality can be improved by adding the ball milling auxiliary agent, and meanwhile, in the process of ball milling, the purpose of cooling is achieved by spraying water to a grinding head or a grinding tail of the ball mill, so that the yield of the ball mill is improved, and devices in the equipment can be better protected.
(4) According to the invention, the mixed powder after ball milling is treated by introducing the alternating high-frequency pulse electric field, so that the powder is uniformly dispersed and is not easy to agglomerate, and the material prepared by pressing, sintering and forming the dispersed alloy powder has excellent mechanical properties and good electrical properties, and the electrical life of the contact is effectively prolonged.
(5) According to the invention, the surface of the prepared metal contact finished product is subjected to plasma scanning treatment, so that impurities or a thin oxide layer on the surface of the metal contact finished product can be removed, the surface resistance of the contact metal finished product is reduced, the electrical property of the contact metal finished product is improved to a certain extent, the area from the plasma beam to the surface of the metal contact finished product is maximized through the included angle between the plasma beam and the metal contact finished product, and the treatment efficiency is improved.
Drawings
FIG. 1 is a flow chart of the operation of the present invention;
FIG. 2 is a CuCr spherical powder containing 20% Cr according to the present invention;
FIG. 3 shows the fine dispersed Cr particles inside the spherical CuCr powder of the present invention containing 20% Cr;
FIG. 4 is a gold phase diagram of CuCr30 of the present invention.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following examples, but the scope of the present invention is not limited thereto.
Example 1
(1) Ingredients
Taking a Cu rod, a Cr block and conventional Cr powder as raw materials for later use, wherein the mesh number of the conventional Cr powder is-80 + 320;
(2) vacuum induction melting
According to the weight ratio of 19: 1, putting the Cu rod and the Cr block into a ceramic crucible in a vacuum induction melting furnace, vacuumizing until the vacuum degree reaches 9 multiplied by 10-1Heating the ceramic crucible by adopting a gradient heating power mode when the pressure is lower than Pa so as to melt the raw materials, closing a vacuum system when Cu starts to melt, filling argon or other inert gases with the purity of 99.99 percent until the vacuum degree is-0.08 MPa, simultaneously preheating a tundish, keeping the power at 7KW until molten metal is completely melted, uniformly stirring, keeping the superheat degree at 100 ℃ according to the components of the molten metal, and preparing for atomization;
(3) atomized powder
Filling argon with the purity of 99.99 percent into a vacuum melting system, ensuring that the vacuum melting system is in a micro-positive pressure state, starting high-pressure argon flow in an atomization system when the temperature of a tundish is detected to be equal to the melting point of an alloy, pouring molten metal in a ceramic crucible into the tundish, enabling the molten metal to flow through a high-pressure argon injection region through a guide pipe, atomizing and crushing the molten metal into a large number of fine liquid drops by the high-pressure argon flow, and solidifying the fine liquid drops into particles in flight, wherein the size of a chromium phase reaches 200nm, CuCr alloy powder with the powder particle size of-100 meshes is selected as a subsequent raw material through screening, and the content of Cr in the CuCr alloy powder accounts for 5 percent;
(4) mixed powder
Mixing the CuCr alloy powder and conventional Cr powder according to the weight ratio of 3: 1 to obtain mixed powder, and then mixing the mixed powder with steel balls according to a ball-to-material ratio of 100: 100, mixing, and mixing powder, wherein the powder mixing time is 3 hours;
(5) pressing and sintering
Pressing the mixed powder in a mould pressing mode, wherein the density is 93%, and then performing vacuum sintering, wherein the vacuum degree is 5 multiplied by 10-2And keeping the temperature for 3 hours at 950 ℃ below Pa grade, wherein the chromium content in the CuCr alloy is 25 percent.
(6) Machining
And (5) machining according to the drawing requirements.
Example 2
(1) Ingredients
Taking a Cu rod, a Cr block and conventional Cr powder as raw materials for later use, wherein the mesh number of the conventional Cr powder is-80 + 320;
(2) vacuum induction melting
The Cu rod and the Cr block are put into a ceramic crucible in a vacuum induction melting furnace according to the weight ratio of 10:1, and the ceramic crucible is vacuumized until the vacuum degree reaches 9 multiplied by 10-1Heating the ceramic crucible by adopting a gradient heating power mode when the pressure is lower than Pa so as to melt the raw materials, closing a vacuum system when Cu starts to melt, filling argon or other inert gases with the purity of 99.99 percent until the vacuum degree is-0.03 MPa, simultaneously preheating a tundish, keeping the power at 25KW until molten metal is completely melted, uniformly stirring, keeping the superheat degree at 150 ℃ according to the components of the molten metal, and preparing for atomization;
(3) atomized powder
Filling argon with the purity of 99.99 percent into a vacuum melting system, ensuring that the vacuum melting system is in a micro-positive pressure state, starting high-pressure argon flow in an atomization system when the temperature of a tundish is detected to be equal to the melting point of an alloy, pouring molten metal in a ceramic crucible into the tundish, enabling the molten metal to flow through a high-pressure argon injection region through a guide pipe, atomizing and crushing the molten metal into a large number of fine liquid drops by the high-pressure argon flow, and solidifying the fine liquid drops into particles in flight, wherein the size of a chromium phase reaches 1 mu m, CuCr alloy powder with the powder granularity of-100 meshes is selected as a subsequent raw material through screening, and the content of Cr in the CuCr alloy powder accounts for 12 percent;
(4) mixed powder
Mixing the CuCr alloy powder and conventional Cr powder according to the weight ratio of 2: 1 to obtain mixed powder, and then mixing the mixed powder with steel balls according to a ball-to-material ratio of 100: 100, mixing, and mixing powder, wherein the powder mixing time is 6 hours;
(5) pressing and sintering
Pressing the mixed powder in a mould pressing mode, wherein the density is 93%, and then performing vacuum sintering, wherein the vacuum degree is 5 multiplied by 10-2And keeping the temperature for 4 hours at the temperature of 1000 ℃ below Pa grade, wherein the chromium content in the CuCr alloy is 35 percent.
(6) Machining
And (5) machining according to the drawing requirements.
Example 3
(1) Ingredients
Taking a Cu rod, a Cr block and conventional Cr powder as raw materials for later use, wherein the mesh number of the conventional Cr powder is-80 + 320;
(2) vacuum induction melting
According to the weight ratio of 4: 1, putting the Cu rod and the Cr block into a ceramic crucible in a vacuum induction melting furnace, vacuumizing until the vacuum degree reaches 9 multiplied by 10-1Heating the ceramic crucible by adopting a gradient heating power mode when the temperature is lower than Pa so as to melt the raw materials, closing a vacuum system when Cu starts to melt, filling argon or other inert gases with the purity of 99.99 percent until the vacuum degree is 0.02MPa, simultaneously preheating a tundish, keeping the power at 45KW until molten metal is completely melted, uniformly stirring, keeping the superheat degree at 200 ℃ according to the components of the molten metal, and preparing for atomization;
(3) atomized powder
Filling argon with the purity of 99.99 percent into a vacuum melting system, ensuring that the vacuum melting system is in a micro-positive pressure state, starting high-pressure argon flow in an atomization system when the temperature of a tundish is detected to be equal to the melting point of an alloy, pouring molten metal in a ceramic crucible into the tundish, enabling the molten metal to flow through a high-pressure argon injection region through a guide pipe, atomizing and crushing the molten metal into a large number of fine liquid drops by the high-pressure argon flow, and solidifying the fine liquid drops into particles in flight, wherein the size of a chromium phase reaches 5 mu m, CuCr alloy powder with the powder granularity of-100 meshes is selected as a subsequent raw material through screening, and the content of Cr in the CuCr alloy powder accounts for 20 percent;
(4) mixed powder
Mixing the CuCr alloy powder and conventional Cr powder according to the weight ratio of 1: 1 to obtain mixed powder, and then mixing the mixed powder with steel balls according to a ball-to-material ratio of 100: 100, mixing, and mixing powder, wherein the powder mixing time is 10 hours;
(5) pressing and sintering
Pressing the mixed powder in a mould pressing mode, wherein the density is 93%, and then performing vacuum sintering, wherein the vacuum degree is 5 multiplied by 10-2And keeping the temperature at 1050 ℃ for 5 hours until the temperature is below Pa grade, wherein the chromium content in the CuCr alloy is 50 percent.
(6) Machining
And (5) machining according to the drawing requirements.
Example 4
Example 4 is essentially the same as example 2, except that:
the specific steps of the gradient heating power mode in the step (2) are as follows: s1: heating the ceramic crucible with 40KW of power, and keeping the temperature for 13 min; s2: heating power is increased to 60KW, and heat preservation is carried out for 7.5 min; s3: and increasing the heating power to 80KW again, reducing the heating power to 20KW when the Cu starts to melt, and keeping until the molten metal is completely melted.
Example 5
The powder mixing in the step (4) is carried out in a ball mill, and the specific process is as follows: the mixed powder and the steel balls are added into a ball milling mixer, the polyvinylpyrrolidone is added into the ball milling mixer, then the mixed powder is ball milled for 6 hours at the rotating speed of 20 r/min, water is sprayed to a grinding head or a grinding tail of the ball mill in the ball milling process, the temperature in the ball mill is controlled to be 70 ℃ through cooling water, the ball mill is easier to grind through adding the polyvinylpyrrolidone, the yield of the ball mill is improved, and devices inside equipment can be better protected.
Example 6
Before the mixed powder after ball milling is pressed in the step (5), firstly adding the mixed powder into an absolute ethyl alcohol solution and uniformly mixing, then introducing an alternating high-frequency pulse electric field into the mixed solution to ensure that the mixed solution is uniformly dispersed for 45min under the action of the alternating high-frequency pulse electric field at the temperature of 110 ℃, then carrying out centrifugal separation, filtering by a microporous filter membrane and drying on the treated mixed solution, wherein the electric field strength is 60kV/cm, the pulse width is 30 mu s, and the pulse frequency is 800Hz, the mixed solution is treated by the high-frequency pulse electric field with the parameters to ensure that the dispersion effect of the high-frequency pulse electric field is optimized, the powder after ball milling is uniformly dispersed and is not easy to agglomerate, and the material prepared by pressing, sintering and molding the dispersed alloy powder has excellent mechanical property and good electrical property, the electrical life of the contact is effectively prolonged.
Example 7
And (5) performing surface treatment on the metal contact finished product subjected to the pressing and sintering treatment in the step (5), wherein the specific treatment process is as follows: the prepared metal contact finished product is placed in a vacuum environment, the surface of the metal contact finished product is scanned by a plasma generator, the prepared metal contact finished product is rotated in different directions in the scanning process, the angle between a plasma beam and the metal contact finished product is kept at an included angle of 48 degrees all the time, the scanning speed is 9mm/s, the frequency of the plasma is 450HZ, due to the fact that the plasma beam has high ionization energy, impurities or thin oxide layers on the surface of the metal contact finished product can be removed through plasma treatment on the surface of the metal contact finished product, the surface resistance of the contact metal finished product is reduced, the electrical performance of the contact metal finished product is improved to a certain extent, the area from the plasma beam to the surface of the metal contact finished product is maximized through the included angle between the plasma beam and the metal contact finished product, and the treatment efficiency is improved.
Test examples
The relevant performance parameters of the optimized Cu-Cr contact by adding ultrafine grained Cr phases, prepared according to examples 1-7 of the present invention, are shown in Table 1:
table 1: related performance parameter table of copper-chromium contact
As can be seen from Table 1, the conductivity of the copper-chromium contact prepared by the method is more than or equal to 23MS/m, the hardness is more than or equal to 70HB, and the density is more than or equal to 7.8g/cm3The oxygen content is less than or equal to 500ppm, and the nitrogen content is less than or equal to 20 ppm; the copper-chromium alloy contact prepared by the invention not only improves the mechanical properties such as hardness, fusion welding resistance and the like, optimizes the electrical property of the copper-chromium alloy contact, avoids the problem of gas content exceeding the standard caused by pursuing fine chromium particles in the conventional production mode, but also is conventional chromium powder with a far small chromium phase size.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (5)
1. A preparation method for optimizing a copper-chromium contact by adding an ultrafine crystal chromium phase is characterized by mainly comprising the following steps:
(1) ingredients
Taking a Cu rod, a Cr block and conventional Cr powder as raw materials for later use, wherein the mesh number of the conventional Cr powder is 80-320;
(2) vacuum induction melting
According to the weight ratio of 19: 1-4: 1, putting the Cu rod and the Cr block into a ceramic crucible in a vacuum induction melting furnace, vacuumizing until the vacuum degree reaches 9 multiplied by 10-1Heating the ceramic crucible with gradient heating power below Pa to melt the raw materials, closing the vacuum system when Cu begins to melt, introducing argon or other inert gas to a vacuum degree of-0.08 to (-0.02) MPa, preheating the tundish, and maintaining the powerWhen the molten metal is completely melted and cleaned at 7-45kW, uniformly stirring, and keeping the superheat degree of 100-200 ℃ for atomization according to the components of the molten metal;
(3) atomized powder
Filling argon into a vacuum melting system, ensuring that the vacuum melting system is in a micro-positive pressure state, starting high-pressure argon flow in an atomization system when the temperature of a tundish is detected to be more than or equal to the melting point of the alloy, wherein the pressure of the atomization argon flow is 2-8MPa, pouring molten metal in a ceramic crucible into the tundish, enabling the molten metal to flow through a high-pressure argon injection area through a guide pipe, atomizing and crushing the molten metal into a large number of fine liquid drops through the high-pressure argon flow, and solidifying the fine liquid drops into particles in flight, wherein the size of a chromium phase reaches 200nm-5 mu m, and selecting CuCr alloy powder with the powder granularity of-100 meshes as a subsequent raw material through;
(4) mixed powder
Mixing the CuCr alloy powder and conventional Cr powder according to the weight ratio of 3: 1-1: 1 to obtain mixed powder, and then mixing the mixed powder with steel balls according to a ball-to-material ratio of 100: 100, mixing, and mixing powder, wherein the mixing time is 3-10 h;
(5) pressing and sintering
Pressing the uniformly mixed powder by adopting a mould pressing mode, wherein the density is more than 95%, and then carrying out vacuum sintering, wherein the vacuum degree is 5 multiplied by 10-2The Pa grade is lower, and the temperature is kept for 3-5h at the temperature of 950-;
(6) machining
Machining according to the drawing requirements;
the specific steps of the gradient heating power mode in the step (2) are as follows: s1: heating the ceramic crucible with the power of 35-45kW, and keeping the temperature for 10-15 min; s2: heating power is increased to 55-65kW, and heat preservation is carried out for 7-8 min; s3: increasing the heating power to 75-85kW again, reducing the heating power to 7-30kW when Cu starts to be melted, and keeping until the molten metal is completely melted;
before the mixed powder obtained after ball milling and mixing in the step (5) is pressed, firstly adding the mixed powder into an absolute ethyl alcohol solution and uniformly mixing, then introducing an alternating high-frequency pulse electric field into the mixed solution to uniformly disperse the mixed solution for 35-50min under the action of the alternating high-frequency pulse electric field at the temperature of 100-120 ℃, and then carrying out centrifugal separation, filtration by a microporous membrane and drying on the treated mixed solution;
the electric field intensity of the alternating high-frequency pulse electric field is 45-70kV/cm, the pulse width is 20-35 mu s, and the pulse frequency is 500-1000 Hz;
and (5) performing surface treatment on the metal contact finished product subjected to the pressing and sintering treatment in the step (5), wherein the specific treatment process is as follows: and placing the prepared metal contact finished product into a vacuum environment, scanning the surface of the metal contact finished product by using a plasma generator, and in the scanning process, rotating the prepared metal contact finished product in different directions, wherein the angle between a plasma beam and the metal contact finished product is always kept at an included angle of 45-50 degrees, wherein the scanning speed is 6-12mm/s, and the frequency of the plasma is 330-550 Hz.
2. The method as claimed in claim 1, wherein the purity of argon in step (2) is 99.99%, and the gas flow rate is 230-750 m/s.
3. The method for preparing a Cu-Cr contact optimized by adding ultrafine grained Cr phase as claimed in claim 1, wherein the content of Cr in the CuCr alloy powder obtained in step (3) is 5-20%, and the content of Cr in the CuCr alloy obtained after pressing and sintering in step (5) is 25-50%.
4. The method for preparing the contact tip of copper and chromium optimized by adding the ultrafine grained chromium phase according to claim 1, wherein the powder mixing in the step (4) is performed in a ball mill by the following specific processes: adding the mixed powder and steel balls into a mixer, adding a ball-milling auxiliary agent, mixing at the rotating speed of 10-30 r/min for 3-10h, spraying water to a grinding head or a grinding tail of the ball mill during ball milling, and controlling the temperature in the ball mill to be 60-80 ℃ through cooling water.
5. The method for preparing a copper-chromium contact optimized by adding ultrafine grained chromium phase according to claim 4, wherein the ball milling aid is polyvinylpyrrolidone.
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| CN111636061A (en) * | 2020-04-21 | 2020-09-08 | 陕西斯瑞新材料股份有限公司 | Preparation method for producing CuCr composite contact through batch type laser cladding |
| CN111748716A (en) * | 2020-06-01 | 2020-10-09 | 陕西斯瑞新材料股份有限公司 | Method for preparing Cu-Zr/Diamond copper-based composite material by using matrix alloying method |
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