Preparation method of high-performance CuCr electrical contact material for high-voltage vacuum circuit breaker

Abstract

The invention relates to the technical field of copper-chromium alloy smelting, in particular to a preparation method of a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker, which comprises the following steps: S1, charging a consumable electrode bar into a furnace; s2, starting a vacuum self-consuming arc; s3, vacuum self-consuming electric arc melting is carried out; s4, vacuum self-consuming electric arc hot feeding is carried out; s5, vacuum self-consuming arc cooling is carried out; according to the method, the high-purity degassed chromium powder and the electrolytic copper powder serve as raw materials, the CuCr55 electrical contact material is prepared through the vacuum consumable electric arc melting technology, material components and microstructures are evenly distributed, Cr particles are fine and tend to be spheroidized, the technology is stable, batch production is easy, and the batch stability is high.

Description

Technical Field

[0001] The invention relates to the technical field of copper-chromium alloy smelting, and in particular to a method for preparing a high-performance CuCr electric contact material for a high-voltage vacuum circuit breaker. Background Art

[0002] Cu in the CuCr contact provides a low melting point, high conductivity and good plasticity, which is beneficial to improving the breaking capacity of the switch. Cr has a high melting point, mechanical strength and a low cut-off value, which ensures that the switch has high voltage resistance, resistance to welding and low cut-off performance. Contacts with high chromium content can improve the breaking capacity of the contacts and ensure the safe operation of the switchgear. At the same time, the chromium element has good resistance to arc erosion. High chromium contacts can maintain a good surface state under the action of the arc and extend the service life of the contacts. Contacts with high chromium content have a higher voltage resistance and can work stably under high voltage environments, reducing the breakdown and flashover of the contacts. The fine and dispersed distribution of Cr particles is beneficial to improving the comprehensive electrical properties of copper-chromium contact materials. However, when the Cr content exceeds 50%, severe segregation occurs due to the presence of immiscible liquid phase regions.

[0003] Patent CN105018815A discloses a high Cr content, high voltage resistance copper-chromium contact material and its preparation method. The invention is based on the existing powder metallurgy, casting and arc melting processes that can only produce CuCr1 to CuCr50 materials. It develops a contact material with a Cr content of up to 70%. High melting point Cr is used as the collective skeleton, and Cu powder is added to form a CuCr compact of a certain strength. The copper-chromium contact material with a high Cr content is melted in a vacuum. The contact Cr particles prepared by this method are coarse, the impurity content is high, and the batch stability is low.

[0004] Patent CN 115213405A discloses a method for preparing a high-voltage copper-chromium contact material. The invention prepares a high-voltage copper-chromium contact material through powder mixing, cold isostatic pressing, vacuum sintering, arc melting, forging, and processing. The method uses Cr powder prepared by the aluminothermic method as the raw material to prepare the contact material, and the impurity content is high, and the Cr particles are prone to segregation.

[0005] In order to solve the above problems, the present invention decides to solve the problems by a method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker.

[0007] A method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker, characterized in that it comprises the following steps:

[0008] S1. Consumable electrode rod loading furnace:

[0009] Putting a consumable electrode rod with a Cr content of 53-55wt% into a smelting furnace, and controlling the single-side gap between the copper mold and the electrode rod to be 10-30mm;

[0010] Turn on the refrigerator in the smelting furnace, adjust the cooling water pressure to 2-4 bar, the helium pressure to 2-4 bar, and control the inlet water temperature to 16-24°C;

[0011] Close the furnace door and evacuate to 5×10 -3 mbar or less, when the pressure rise rate reaches below 0.01 mbar / min, inert gas is filled into the smelting furnace to 80-100 mbar;

[0012] S2, vacuum consumable arc starting:

[0013] Each time the arc is started, 25-35g of arc starting material is taken, the distance between the arc starting material and the end face of the consumable electrode rod is 20-30mm, the arc starting current is 2-3KA, the arc starting voltage is 20-25V, the droplet rate is 0.5-2g / s, the arc stabilization current is 20-30A, and the droplet control is switched after 4-5min;

[0014] S3, Vacuum consumable arc melting:

[0015] After switching to droplet control, vacuum consumable arc melting begins, with a melting current of 2-4KA, a melting voltage of 25-30V, a droplet rate of 5-10g / s, a stable arc current of 15-20A, and a melting time of 10-20min;

[0016] After the vacuum consumable arc melting is completed, the obtained copper mold is placed in a water cooling jacket and cooled to room temperature to obtain a smelted electric contact;

[0017] S4, Vacuum consumable arc heat compensation:

[0018] The smelting electric contact obtained in S3 is subjected to vacuum consumable arc heat shrinking, the smelting current is 1.5-2.5KA, the smelting voltage is 23-35V, the droplet rate is 1-2g / s, the arc stabilization current is 20-25A, and the heat shrinking is 2-5min;

[0019] S5. Vacuum consumable arc cooling:

[0020] The heat-compensated electric contact obtained in S4 is placed in a water-cooling jacket and cooled for 10 to 20 minutes before being taken out of the furnace to obtain a CuCr electric contact.

[0021] Furthermore, in step S1, the preparation method of the consumable electrode rod is:

[0022] The electrolytic copper powder and the high-purity degassed chromium powder are mixed according to the said proportion for 2 to 5 hours to obtain the copper-chromium mixed powder, the copper-chromium mixed powder is loaded into a rubber sleeve mold for powdering, and after the powdering is completed, it is pressed in a cold isostatic press at a pressure of 180 to 220 MPa and a holding time of 5 to 10 minutes to obtain an electrode rod, and finally the electrode rod is placed in a vacuum sintering furnace and sintered at a temperature of 700 to 1020° C. for 10 to 35 hours to obtain a consumable electrode rod.

[0023] Description: Cold isostatic pressing can effectively increase the density of powder materials and reduce porosity, thereby improving the mechanical strength and wear resistance of electrode rods; the sintering process helps to achieve uniform distribution of elements inside the material, reduce macro segregation, and improve the overall performance of the material; since cold isostatic pressing and sintering can optimize the microstructure of the material, this helps to improve the conductivity and arc stability of the electrode, thereby performing better in the arc melting process.

[0024] Furthermore, the powdering method is: hold the rubber sleeve tightly with both hands, first powder it in the forward direction 8 to 10 times, each time powdering, the bottom of the rubber sleeve is 20 to 50 cm above the ground, after the forward powdering is completed, use a rubber plug to seal the rubber sleeve radially, and then powder it in the reverse direction 8 to 10 times.

[0025] Description: Due to the reduction of friction, the powder particles can be arranged more closely, thereby improving the density and mechanical properties of the final product. Reverse milling helps to improve the microstructure of powder materials, reduce pores and defects, and improve the overall performance of the material.

[0026] Furthermore, in step S2, the arc starting material is an oxygen-free copper wire with a diameter of 1 to 3 mm and a length of 10 to 20 mm.

[0027] Description: Oxygen-free copper wire has extremely high conductivity, which helps to quickly establish a stable arc in the electric arc furnace, thereby improving the smelting efficiency. Due to the extremely low oxygen content of oxygen-free copper wire, it is not easy to further oxidize at high temperatures, which helps to maintain the purity of the smelting material and avoid the introduction of unnecessary oxides; oxygen-free copper wire has good high-temperature stability, which means that it can withstand high temperatures without significant degradation during the smelting process, which helps to protect the electrodes and furnace lining.

[0028] Furthermore, in step S3 and step S5, in the water cooling jacket, cooling water enters from the bottom of the water cooling jacket, flows out from the water outlet at the upper end and spreads to the surroundings, the water pressure is 0.3-0.5MPa, and the cooling water flow rate is 200-300L / min.

[0029] Note: As the cooling water flows from bottom to top inside the water cooling jacket, it can take away heat more efficiently because the natural convection of hot water rising and cold water falling helps to improve the heat exchange efficiency.

[0030] Furthermore, in steps S2, S3 and S4, respectively, an inert gas and / or a refining agent is rotatably sprayed into the vacuum consumable smelting furnace, and the method of rotatably spraying the inert gas and / or the refining agent is:

[0031] In S2, the inert gas is sprayed by rotating alone, the nozzle speed is 150-350 r / min, the inert gas flow rate is 1.5-4.5 L / min, and the spraying time is 5-10 min;

[0032] In S3, the inert gas is firstly rotated and sprayed alone, the nozzle speed is 350-450r / min, the inert gas flow rate is 1.5-2.5L / min, until the melt mass reaches 70-80% of the total melt mass, and then the refining agent is rotated and sprayed, the addition amount of the refining agent is 0.1-0.3% of the total melt mass, and the spraying time is 2-5min;

[0033] In S4, the refining agent is sprayed alone in a rotating manner, the nozzle speed is 150-350 r / min, the amount of the refining agent added is 0.05-0.1% of the melt mass, and the spraying time is 5-10 min.

[0034] Description: Improve smelting efficiency and purity: In the arc starting stage, the inert gas is sprayed in a rotating manner to stabilize the arc and avoid oxidation. At the same time, the flow of inert gas helps to remove oxides and non-metallic inclusions on the surface of the molten pool, thereby improving the purity of the smelting process;

[0035] Optimize the smelting process: In the smelting stage, injecting gas first and then co-blowing with refining agent can ensure the uniformity inside the molten pool and the uniform distribution of components; gas injection helps to control the temperature and atmosphere of the molten pool, while the addition of refining agent can further remove impurities and improve the physical and chemical properties of the alloy;

[0036] Enhance the organization and performance of the alloy: Rotating and blowing the refining agent alone during the hot shrinkage stage can promote the solidification process of the alloy, reduce shrinkage holes, and improve the microstructure of the alloy. The addition of the refining agent helps to refine the grains and improve the mechanical properties and corrosion resistance of the alloy.

[0037] Furthermore, the inert gas is one or more of argon or nitrogen, and the purity of argon and nitrogen is ≥99.99%.

[0038] Description: Argon and nitrogen are very stable inert gases that are not easy to react chemically with other substances. Therefore, they can be used as protective gases to prevent material oxidation and corrosion.

[0039] Furthermore, the refining agent comprises, by mass, 15 to 20 parts of sodium fluoroborate, 6 to 10 parts of sodium chloride, 5 to 8 parts of calcium carbonate and 0.4 to 0.6 parts of tri-tert-butylphosphonium tetrafluoroborate.

[0040] Description: Sodium fluoroborate helps remove impurities from the metal surface and improves the purity of the metal. In addition, sodium fluoroborate can also be used as a chemical reagent and electrochemical antioxidant to help improve the processing performance and corrosion resistance of metals; sodium chloride can help separate metal and non-metallic impurities, thereby improving the quality of the final product; calcium carbonate can reduce the impact of acidic substances during the refining process. It can also be used as a desulfurizer to help remove harmful impurities such as sulfides; tri-tert-butyl phosphorus tetrafluoroborate can improve the yield and selectivity of the reaction and has the advantages of excellent catalytic performance.

[0041] Compared with the existing preparation method of CuCr electrical contact material, the beneficial effects of the present invention are:

[0042] (1) The present invention uses high-purity degassed chromium powder and electrolytic copper powder as raw materials and adopts a vacuum consumable arc melting process to prepare CuCr55 electrical contact material. The material composition and microstructure are evenly distributed, the Cr particles are small and tend to be spheroidized, the process is stable, and it is easy to mass produce with high batch stability.

[0043] (2) The preparation method of the present invention performs rotary blowing of inert gas and refining agent according to the vacuum consumable arc melting stage to improve the melting efficiency and purity: in the arc starting stage, the inert gas is rotated and blown alone to stabilize the arc and avoid oxidation. At the same time, the flow of inert gas helps to remove oxides and non-metallic inclusions on the surface of the molten pool, thereby improving the purity of the melting process; the melting process is optimized: in the melting stage, the gas is first blown and then co-blown with the refining agent to ensure the uniformity inside the molten pool and the uniform distribution of components; gas blowing helps to control the temperature and atmosphere of the molten pool, and the addition of the refining agent can further remove impurities and improve the physical and chemical properties of the alloy; the organization and performance of the alloy are enhanced: in the heat shrinkage compensation stage, the refining agent is rotated and blown alone to promote the solidification process of the alloy, reduce shrinkage holes, and improve the microstructure of the alloy. The addition of the refining agent helps to refine the grains and improve the mechanical properties and corrosion resistance of the alloy.

[0044] (3) The preparation method of the present invention divides vacuum consumable arc melting into arc starting, melting, and heat shrinkage compensation stages. A higher voltage during arc starting helps to form a stable arc, providing a good start for the subsequent melting process. During the melting stage, by precisely controlling the arc heating zone, a stable melting rate can be maintained, so that the CuCr electrode rods are melted evenly and component segregation is reduced. During the heat shrinkage compensation stage, the supply current of the power supply is gradually weakened, which can reduce the generation of defects such as shrinkage cavities and looseness. In this stage, the melted CuCr can be properly shrinkage compensated to make the CuCr ingot denser and improve the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a 100X metallographic observation picture of the CuCr electric contact material prepared by the present invention. DETAILED DESCRIPTION

[0046] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0047] Embodiment 1: A method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker, comprising the following steps:

[0048] S1. Consumable electrode rod loading furnace:

[0049] A consumable electrode rod with a Cr content of 54.18wt% was placed in a smelting furnace, and the single-side gap between the copper mold and the electrode rod was controlled to be 20mm;

[0050] The preparation method of the consumable electrode rod is as follows:

[0051] Electrolytic copper powder and high-purity degassed chromium powder are mixed according to the ratio for 3.5 hours to obtain copper-chromium mixed powder, and the copper-chromium mixed powder is loaded into a rubber sleeve mold for powdering. The powdering method is as follows: hold the rubber sleeve tightly with both hands, firstly powder it 9 times in the forward direction, each time the rubber sleeve is powdered, the height of the bottom of the rubber sleeve from the ground is 35 cm, after the forward powdering is completed, the rubber sleeve is radially sealed with a rubber plug, and then powdered 9 times in the reverse direction; after the powdering is completed, it is pressed in a cold isostatic press at a pressure of 200 MPa and a holding time of 8 minutes to obtain an electrode rod, and finally the electrode rod is placed in a vacuum sintering furnace and sintered at a temperature of 850° C. for 23 hours to obtain a consumable electrode rod;

[0052] Turn on the refrigerator in the smelting furnace, adjust the cooling water pressure to 3 bar, the helium pressure to 3 bar, and control the inlet water temperature at 20°C;

[0053] Close the furnace door and evacuate to 4.8×10 -3 mbar, when the pressure rise rate reaches 0.0081mbar / min, inert gas is filled into the smelting furnace to 90mbar;

[0054] S2, vacuum consumable arc starting:

[0055] Each time the arc is struck, 30g of arc-starting material is taken. The arc-starting material is oxygen-free copper wire with a diameter of 2mm and a length of 15mm. The distance between the arc-starting material and the end face of the consumable electrode rod is 25mm. The arc-starting current is 2.5KA, the arc-starting voltage is 23V, the droplet rate is 1.2g / s, the arc stabilization current is 25A, and the droplet control is switched after 4.5min.

[0056] S3, Vacuum consumable arc melting:

[0057] After switching to droplet control, vacuum consumable arc melting begins, with a melting current of 3KA, a melting voltage of 28V, a droplet rate of 6g / s, a stable arc current of 18A, and a melting time of 15min;

[0058] After the vacuum consumable arc melting is completed, the obtained copper mold is placed in a water cooling jacket and cooled to 25°C to obtain a smelted electric contact;

[0059] S4, Vacuum consumable arc heat compensation:

[0060] The smelting electric contact obtained in S3 was subjected to vacuum consumable arc heat shrinking, with a melting current of 2KA, a melting voltage of 28V, a droplet rate of 1.5g / s, a stable arc current of 23A, and a heat shrinking of 4min;

[0061] S5. Vacuum consumable arc cooling:

[0062] The heat-compensated electric contact obtained in S4 is placed in a water-cooling jacket and cooled for 15 minutes, and then taken out of the furnace to obtain a CuCr electric contact; in step S3 and step S5, in the water-cooling jacket, cooling water enters from the bottom of the water-cooling jacket, and flows out from the water outlet at the upper end and spreads to the surroundings, the water pressure is 0.4 MPa, and the cooling water flow rate is 250 L / min.

[0063] Example 2: This example is different from Example 1 in that electrolytic copper powder and high-purity degassed chromium powder are mixed for 2 hours at a ratio of 53 wt% Cr content to obtain copper-chromium mixed powder.

[0064] Example 3: This example is different from Example 1 in that electrolytic copper powder and high-purity degassed chromium powder are mixed for 5 hours at a ratio of 55 wt% Cr content to obtain copper-chromium mixed powder.

[0065] Example 4: This example is different from Example 1 in that the method of powdering is: hold the rubber sleeve tightly with both hands, first powder it in the forward direction 8 times, each time powdering, the bottom of the rubber sleeve is 20 cm above the ground, after the forward powdering is completed, use a rubber plug to seal the rubber sleeve radially, and then powder it in the reverse direction 8 times.

[0066] Example 5: This example is different from Example 1 in that the method of powdering is: hold the rubber sleeve tightly with both hands, first powder it in the forward direction 10 times, each time powdering, the bottom of the rubber sleeve is 50 cm above the ground, after the forward powdering is completed, use a rubber plug to seal the rubber sleeve radially, and then powder it in the reverse direction 10 times.

[0067] Example 6: This example is different from Example 1 in that the pressing is performed in a cold isostatic press with a pressure of 180 MPa and a holding time of 5 min.

[0068] Example 7: This example is different from Example 1 in that the pressing is performed in a cold isostatic press with a pressure of 220 MPa and a holding time of 10 min.

[0069] Example 8: This example is different from Example 1 in that the electrode rod is placed in a vacuum sintering furnace and sintered at 700° C. for 10 hours to obtain a consumable electrode rod.

[0070] Example 9: This example is different from Example 1 in that the electrode rod is placed in a vacuum sintering furnace and sintered at 1020° C. for 35 hours to obtain a consumable electrode rod.

[0071] Example 10: This example is different from Example 1 in that the single-side gap between the copper mold and the electrode rod is 10 mm, the refrigerator in the smelting furnace is turned on, the cooling water pressure is adjusted to 2 bar, the helium pressure is 2 bar, and the inlet water temperature is controlled at 16°C.

[0072] Example 11: This example differs from Example 1 in that the single-side gap between the copper mold and the electrode rod is 30 mm, the refrigerator in the smelting furnace is turned on, the cooling water pressure is adjusted to 4 bar, the helium pressure is 4 bar, and the inlet water temperature is controlled at 24°C.

[0073] Example 12: This example is different from Example 1 in that the furnace door is closed and the vacuum is drawn to 4.5×10 - 3 mbar, when the pressure rise rate reaches 0.005mbar / min, inert gas is filled into the smelting furnace to 80mbar.

[0074] Example 13: This example is different from Example 1 in that the furnace door is closed and the vacuum is drawn to 5×10 -3 mbar, when the pressure rise rate reaches 0.01 mbar / min, inert gas is filled into the smelting furnace to 100 mbar.

[0075] Example 14: The difference between this example and Example 1 is that 25 g of arc starting material is taken each time the arc is started. The arc starting material is an oxygen-free copper wire with a diameter of 1 mm and a length of 20 mm. The distance between the arc starting material and the end face of the consumable electrode rod is 20 mm.

[0076] Example 15: The difference between this example and Example 1 is that 35g of arc starting material is taken each time the arc is started. The arc starting material is an oxygen-free copper wire with a diameter of 3mm and a length of 10mm. The distance between the arc starting material and the end face of the consumable electrode rod is 30mm.

[0077] Example 16: This example is different from Example 1 in that the arc starting current is 2KA, the arc starting voltage is 20V, the droplet rate is 0.5g / s, the arc stabilization current is 20A, and it switches to droplet control after 4 minutes.

[0078] Example 17: This example is different from Example 1 in that the arc starting current is 3KA, the arc starting voltage is 25V, the droplet rate is 2g / s, the arc stabilization current is 30A, and it switches to droplet control after 5 minutes.

[0079] Example 18: This example is different from Example 1 in that the melting current is 2KA, the melting voltage is 25V, the droplet rate is 5g / s, the arc stabilization current is 15A, and the melting time is 10min.

[0080] Example 19: This example is different from Example 1 in that the melting current is 4KA, the melting voltage is 30V, the droplet rate is 10g / s, the arc stabilization current is 20A, and the melting time is 20min.

[0081] Example 20: This example is different from Example 1 in that the melting current is 1.5KA, the melting voltage is 23V, the droplet rate is 1g / s, the arc stabilization current is 20A, and the heat compensation is 2min.

[0082] Example 21: This example is different from Example 1 in that the melting current is 2.5KA, the melting voltage is 35V, the droplet rate is 2g / s, the arc stabilization current is 25A, and the heat compensation is 5min.

[0083] Example 22: The difference between this example and Example 1 is that, in the water-cooling jacket, cooling water enters from the bottom of the water-cooling jacket, flows out from the water outlet at the upper end and spreads to the surroundings, the water pressure is 0.3MPa, and the cooling water flow rate is 200L / min.

[0084] Example 23: The difference between this example and Example 1 is that, in the water-cooling jacket, cooling water enters from the bottom of the water-cooling jacket, flows out from the water outlet at the upper end and spreads to the surroundings, the water pressure is 0.5MPa, and the cooling water flow rate is 300L / min.

[0085] Embodiment 24: This embodiment differs from Embodiment 1 in that in steps S2, S3 and S4, an inert gas and / or a refining agent are rotatably sprayed into the vacuum consumable smelting furnace, and the method of rotatably spraying the inert gas and / or the refining agent is as follows:

[0086] In S2, the inert gas is sprayed by rotating alone, the nozzle speed is 225r / min, the inert gas flow rate is 2.5L / min, and the spraying time is 8min;

[0087] In S3, firstly, the inert gas is sprayed separately by rotation, the nozzle speed is 400r / min, the inert gas flow rate is 2L / min, until the melt mass reaches 75% of the total melt mass, and then the refining agent is sprayed by rotation, the addition amount of the refining agent is 0.2% of the total melt mass, and the spraying time is 3min;

[0088] In S4, the refining agent is sprayed in a rotating manner alone, the nozzle speed is 225 r / min, the amount of the refining agent added is 0.08% of the melt mass, and the spraying time is 8 min;

[0089] The inert gas is argon with a purity of 99.99%; the refining agent includes, by mass, 17.5 parts of sodium fluoroborate, 8 parts of sodium chloride, 6.5 parts of calcium carbonate and 0.5 parts of tri-tert-butyl phosphine tetrafluoroborate.

[0090] Example 25: This example differs from Example 24 in that, in S2, the inert gas is sprayed in a rotating manner alone, the nozzle speed is 150 r / min, the inert gas flow rate is 1.5 L / min, the spraying time is 5 min, the inert gas is nitrogen, and the purity of the nitrogen is 99.99%.

[0091] Example 26: The difference between this example and Example 24 is that in S2, the inert gas is sprayed separately in a rotating manner, the nozzle speed is 350r / min, the inert gas flow rate is 4.5L / min, the spraying time is 10min, and the inert gas is argon and nitrogen in a mass ratio of 1:1, and the purity of argon and nitrogen is 99.99%.

[0092] Example 27: The difference between this example and Example 24 is that in S3, the inert gas is firstly rotated and sprayed alone, the nozzle speed is 350r / min, and the inert gas flow rate is 1.5L / min.

[0093] Example 28: The difference between this example and Example 24 is that in S3, the inert gas is firstly rotated and sprayed alone, the nozzle speed is 450r / min, and the inert gas flow rate is 2.5L / min.

[0094] Example 29: This example differs from Example 24 in that the refining agent is rotated and sprayed until the mass of the melt reaches 80% of the total mass of the melt, the amount of the refining agent added is 0.1% of the total mass of the melt, and the spraying time is 2 minutes.

[0095] Example 30: This example differs from Example 24 in that the refining agent is rotated and sprayed until the mass of the melt reaches 70% of the total mass of the melt, the amount of the refining agent added is 0.3% of the total mass of the melt, and the spraying time is 5 minutes.

[0096] Example 31: This example is different from Example 24 in that, in S4, the refining agent is sprayed separately by rotation, the nozzle speed is 150r / min, the amount of the refining agent added is 0.05% of the melt mass, and the spraying time is 5min.

[0097] Example 32: This example is different from Example 24 in that, in S4, the refining agent is sprayed separately by rotation, the nozzle speed is 350 r / min, the amount of the refining agent added is 0.1% of the melt mass, and the spraying time is 10 min.

[0098] Example 33: This example is different from Example 24 in that the refining agent comprises, by mass, 15 parts of sodium fluoroborate, 6 parts of sodium chloride, 5 parts of calcium carbonate and 0.6 parts of tri-tert-butyl phosphine tetrafluoroborate.

[0099] Example 34: This example is different from Example 24 in that the refining agent comprises, by mass, 20 parts of sodium fluoroborate, 10 parts of sodium chloride, 8 parts of calcium carbonate and 0.4 parts of tri-tert-butyl phosphine tetrafluoroborate.

[0100] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and is intended to illustrate the practical application effect of the present invention.

[0101] Table 1 Material performance test data of Example 1

[0102]

[0103] Combining from Table 1 Figure 1 It can be seen that the CuCr electrical contact material prepared in Example 1 has low gas content and good hardness, density and electrical conductivity. When it is observed under a 100X microscope, the copper-chromium structure is evenly distributed, the chromium structure is distributed in granular form, and the average particle size of the chromium particles is ≤100um.

[0104] 1. Investigate the effects of the preparation of consumable electrode rods and furnace loading parameters on the hardness and conductivity of CuCr electrical contact materials.

[0105] Table 2 Hardness and conductivity of CuCr electrical contact materials in Examples 2 to 13

[0106]

[0107] It can be seen from the results in Table 2 that, compared with Example 1, too low or too high chromium content, too small or too large milling parameters, too small or too large cold isostatic pressing parameters, too small sintering parameters, too small or too large furnace refrigeration parameters, and too small or too large furnace gas pressure parameters will reduce the hardness and conductivity of the CuCr electrical contact material. In Example 9, the sintering temperature is higher and the time is longer, and the hardness is increased but the conductivity is reduced compared with Example 1. Therefore, from an economic point of view, the parameter effect of Example 1 is relatively better.

[0108] 2. Investigate the effects of vacuum consumable arc starting, melting, heat shrinkage and cooling parameters on the hardness and conductivity of CuCr electrical contact materials.

[0109] Table 3 Hardness and conductivity of CuCr electrical contact materials in Examples 14 to 23

[0110]

[0111]

[0112] It can be seen from the results in Table 3 that arc starting parameters that are too small or too large, smelting parameters that are too small or too large, heat compensation parameters that are too small or too large, and cooling parameters that are too small or too large will all reduce the hardness and conductivity of the CuCr electrical contact material compared to Example 1. Therefore, in general, the parameter effect of Example 1 is relatively better.

[0113] 3. Investigate the effect of rotary injection of inert gas and refining agent on the hardness and conductivity of CuCr electrical contact materials

[0114] Table 4 Hardness and conductivity of CuCr electrical contact materials in Examples 24 to 34 and Comparative Examples 1 to 4

[0115]

[0116] The difference between Comparative Example 1 and Example 24 is that only the inert gas is rotated and sprayed in each stage;

[0117] The difference between Comparative Example 2 and Example 24 is that only the refining agent is sprayed in rotation at each stage;

[0118] The difference between Comparative Example 3 and Example 24 is that the parameters of the rotary spraying in each stage are the same;

[0119] The difference between Comparative Example 4 and Example 24 is that the refining agent does not include tri-tert-butylphosphonium tetrafluoroborate;

[0120] From the results in Table 4, it can be seen that compared with Example 1, Examples 24 to 34 significantly improve the hardness and conductivity of the CuCr electrical contact material, while Control Example 1 lacks a refining agent, Control Example 2 lacks an inert gas, Control Example 3 lacks parameter adjustment at each stage, and Control Example 4 lacks tri-tert-butyl phosphine tetrafluoroborate, which significantly reduces the improvement of the hardness and conductivity of the CuCr electrical contact material compared with Examples 24 to 34, indicating that the components in the rotary spraying and the adjustment of each step have a certain effect on the improvement of the hardness and conductivity of the CuCr electrical contact material;

[0121] By comparing Examples 24 to 34, it can be seen that the parameters of the rotary blowing in the arc starting stage are too small or too large, the parameters in the smelting stage are too small or too large, the parameters of the refining agent added in the smelting stage are too small or too large, the parameters in the heat compensation stage are too small or too large, and the proportion of tri-tert-butyl phosphine tetrafluoroborate in the refining agent is too small or too large, which will reduce the improvement in the hardness and conductivity of the CuCr electrical contact material. Therefore, in comprehensive comparison, the parameter effect of Example 24 is relatively better.

Claims

1. A method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker, characterized in that: The following steps are involved: S1. Consumable electrode rod loading furnace: Putting a consumable electrode rod with a Cr content of 53-55wt% into a smelting furnace, and controlling the single-side gap between the copper mold and the electrode rod to be 10-30mm; Turn on the refrigerator in the smelting furnace, adjust the cooling water pressure to 2-4 bar, the helium pressure to 2-4 bar, and control the inlet water temperature to 16-24°C; Close the furnace door and evacuate to 5×10 -3 mbar or less, when the pressure rise rate reaches below 0.01 mbar / min, inert gas is filled into the smelting furnace to 80-100 mbar; S2, vacuum consumable arc starting: Each time the arc is started, 25-35g of arc starting material is taken, the distance between the arc starting material and the end face of the consumable electrode rod is 20-30mm, the arc starting current is 2-3KA, the arc starting voltage is 20-25V, the droplet rate is 0.5-2g / s, the arc stabilization current is 20-30A, and the droplet control is switched after 4-5min; S3, Vacuum consumable arc melting: After switching to droplet control, vacuum consumable arc melting begins, with a melting current of 2-4KA, a melting voltage of 25-30V, a droplet rate of 5-10g / s, a stable arc current of 15-20A, and a melting time of 10-20min; After the vacuum consumable arc melting is completed, the obtained copper mold is placed in a water cooling jacket and cooled to room temperature to obtain a smelted electric contact; S4, Vacuum consumable arc heat compensation: The smelting electric contact obtained in S3 is subjected to vacuum consumable arc heat shrinking, the smelting current is 1.5-2.5KA, the smelting voltage is 23-35V, the droplet rate is 1-2g / s, the arc stabilization current is 20-25A, and the heat shrinking is 2-5min; S5. Vacuum consumable arc cooling: The heat-compensated electric contact obtained in S4 is placed in a water-cooling jacket and cooled for 10 to 20 minutes before being taken out of the furnace to obtain a CuCr electric contact.

2. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 1, characterized in that: In step S1, the method for preparing the consumable electrode rod is: The electrolytic copper powder and the high-purity degassed chromium powder are mixed according to the said proportion for 2 to 5 hours to obtain the copper-chromium mixed powder, the copper-chromium mixed powder is loaded into a rubber sleeve mold for powdering, and after the powdering is completed, it is pressed in a cold isostatic press at a pressure of 180 to 220 MPa and a holding time of 5 to 10 minutes to obtain an electrode rod, and finally the electrode rod is placed in a vacuum sintering furnace and sintered at a temperature of 700 to 1020° C. for 10 to 35 hours to obtain a consumable electrode rod.

3. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 2, characterized in that: The powdering method is: hold the rubber sleeve tightly with both hands, first powder it in the forward direction 8 to 10 times, each time powdering, the height of the bottom of the rubber sleeve from the ground is 20 to 50 cm, after the forward powdering is completed, use a rubber plug to seal the rubber sleeve radially, and then powder it in the reverse direction 8 to 10 times.

4. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 1, characterized in that: In step S2, the arc starting material is oxygen-free copper wire with a diameter of 1 to 3 mm and a length of 10 to 20 mm.

5. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 1, characterized in that: In step S3 and step S5, in the water cooling jacket, cooling water enters from the bottom of the water cooling jacket, flows out from the water outlet at the upper end and spreads to the surroundings, the water pressure is 0.3-0.5MPa, and the cooling water flow rate is 200-300L / min.

6. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 1, characterized in that: In steps S2, S3 and S4, respectively, an inert gas and / or a refining agent is rotatably sprayed into the vacuum consumable smelting furnace. The method of rotatably spraying the inert gas and / or the refining agent is as follows: In S2, the inert gas is sprayed by rotating alone, the nozzle speed is 150-350 r / min, the inert gas flow rate is 1.5-4.5 L / min, and the spraying time is 5-10 min; In S3, the inert gas is firstly rotated and sprayed alone, the nozzle speed is 350-450r / min, the inert gas flow rate is 1.5-2.5L / min, until the melt mass reaches 70-80% of the total melt mass, and then the refining agent is rotated and sprayed, the addition amount of the refining agent is 0.1-0.3% of the total melt mass, and the spraying time is 2-5min; In S4, the refining agent is sprayed alone in a rotating manner, the nozzle speed is 150-350 r / min, the amount of the refining agent added is 0.05-0.1% of the melt mass, and the spraying time is 5-10 min.

7. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 6, characterized in that: The inert gas is one or more of argon or nitrogen, and the purity of argon and nitrogen is ≥99.99%.

8. The method for preparing a high-performance CuCr electrical contact material for a high-voltage vacuum circuit breaker according to claim 1, characterized in that: The refining agent comprises, by weight, 15 to 20 parts of sodium fluoroborate, 6 to 10 parts of sodium chloride, 5 to 8 parts of calcium carbonate and 0.4 to 0.6 parts of tri-tert-butylphosphonium tetrafluoroborate.

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