Preparation method of CuCr alloy and application of CuCr alloy in arc extinguish chamber contact

Abstract

The invention relates to a preparation method of a CuCr alloy and application of the CuCr alloy in an arc extinguish chamber contact, and belongs to the technical field of alloy materials. According to the preparation method of the CuCr alloy, the Cu powder and the Cr powder are subjected to wet grinding, then the Cu powder and the Cr powder are sealed in the cavity of the pure copper container in a vacuum mode, oscillation hot pressing sintering is utilized, the gas content of the CuCr alloy can be reduced, the alloy density can be improved, meanwhile, the mixing degree of a Cu phase and a Cr phase is improved, and therefore the high-performance CuCr alloy is obtained. The CuCr alloy prepared by the preparation method of the CuCr alloy is high in structure density, fine in grain, low in gas content and excellent in insulating property, can completely meet the structure property requirement of a vacuum arc extinguish chamber on a CuCr contact, can be used for manufacturing the vacuum series product arc extinguish chamber CuCr contact, and effectively ensures that the operation reliability of the vacuum series product is improved.

Description

Technical Field

[0001] The invention relates to a preparation method of a CuCr alloy and application of the CuCr alloy in an arc extinguishing chamber contact, belonging to the technical field of alloy materials. Background Art

[0002] The CuCr series of high-strength and high-conductivity alloys not only have good electrical conductivity, but also have excellent mechanical properties. Therefore, they are widely used in industrial production fields such as machinery, electricity, and transportation. In the field of high-voltage switches, CuCr alloy materials are widely used in vacuum switch arc extinguishing chambers due to their excellent mechanical and electrical properties. They are responsible for long-term flow and fault current cutting functions and are key components that determine the electrical performance of vacuum circuit breakers. However, the preparation methods for large-sized high-Cr content CuCr contacts for voltage levels of 126kV and above are currently only infiltration and arc melting. Among them, the steps of the infiltration method are as follows: cold pressing Cr powder into a billet, sintering and heat preservation, and then cooling to obtain a sintered Cr block, placing a Cu block on top of the sintered Cr block, and then placing the Cr block and the Cu block in a vacuum furnace at a temperature of 1300°C for infiltration, heat preservation for 2 hours, and then cooling with the furnace to obtain a CuCr alloy. The arc melting method can refer to the method in Chinese patent document CN106350683A, which specifically includes the following steps: select qualified Cu powder and Cr powder and mix them according to the proportion, use cold isostatic pressing to press them into rods, and then sinter them into alloy ingots by self-consumable melting. However, the materials prepared by these two methods have problems such as coarse grains and high gas content. The high gas content of the contact material can easily cause the vacuum degree of the arc extinguishing chamber to deteriorate and the insulation capacity to decrease after standing. In addition, the contact for high voltage level has a large diameter and low production efficiency, which seriously restricts the test and delivery cycle of the arc extinguishing chamber.

[0003] Domestic and foreign research on the performance improvement of CuCr alloys mainly focuses on organizational structure research, preparation process parameter optimization and arc action mechanism, etc., and there are few studies on the process improvement of reducing the gas content of CuCr alloys, controlling impurities and improving the uniformity of two-phase distribution. Chinese patent document CN115948667A discloses a preparation method of tungsten nanoparticle-reinforced CuCr alloy. The preparation method disclosed in the patent document is to use CuO and Cr2O3 as raw materials, Al powder as a reducing agent, CaO as a slag-making agent, and KClO3 as a heating agent, and obtain a high-temperature mutually soluble CuCr alloy melt and alumina-based reduced smelting slag by self-propagation of aluminum heat; in the process of tempering and refining the alloy melt under electromagnetic induction slag protection, a mixture of high-energy ball milling activation pre-treated Mg powder and WO3 is sprayed into the high-temperature melt by stirring and spraying, and the dispersion addition of nano W particles is realized by in-situ reduction to enhance the performance of CuCr alloy. However, in actual use, the addition of W element is not conducive to the improvement of the insulation performance and breaking capacity of the vacuum interrupter, and other impurity elements are easily introduced into the preparation method. Chinese patent document CN118460978A discloses a surface alloy coating and treatment method of a copper-chromium contact material for a vacuum interrupter. The surface alloy coating disclosed in the patent document is a CuCrTa alloy coating coated on the surface of the contact substrate by magnetron sputtering, followed by annealing to control the size of its microstructure and the generation of intermetallic compound phases. However, the grain refinement and uniformity of the coating are limited to the surface of the CuCr alloy, and the alloy structure of the substrate still has the problems of coarse grains and high gas content. Chinese patent document CN118127499A discloses a method for preparing a high-conductivity CuCr alloy contact with a gradient composition structure by cold spraying process, but the cold spray coating is mechanically bonded to the substrate, with low bonding strength and high porosity. Using too high a gas content in a vacuum interrupter will reduce the insulation capacity, and contact collision will cause the coating to peel off and trigger discharge. Chinese patent document CN115354185A discloses a method for preparing high-purity and ultra-low gas content copper-chromium contacts. The preparation method disclosed in the patent document optimizes the material selection of furnace lining knotting and multiple feedings, and introduces metal Zr for deoxidation and impurity removal to prepare contact materials with extremely low gas content. However, the process flow is relatively complicated, and the introduction of metal Zr elements requires strict control of the dosage to ensure the purity of the CuCr material. The defects of the vacuum induction melting process itself cannot be overcome. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a CuCr alloy, which can solve the problems that the performance of the CuCr alloy is reduced and the amount of element addition is difficult to control when the W element or Zr element is introduced to prepare a CuCr alloy with a low gas content.

[0005] Another object of the present invention is to provide an application of a CuCr alloy in an arc extinguishing chamber contact, which can solve the problem that the vacuum degree of the arc extinguishing chamber is easily deteriorated when the CuCr alloy is currently used in the vacuum arc extinguishing chamber contact.

[0006] In order to achieve the above objectives, the technical solution adopted by the preparation method of the CuCr alloy of the present invention is:

[0007] A preparation method of a CuCr alloy comprises the following steps: firstly, wet-grinding raw metal powder and a liquid medium to obtain slurry; then, pouring the slurry into a pure copper container cavity under vacuum conditions, then removing the liquid medium in the slurry under vacuum conditions, and then sealing the slurry after the liquid medium is removed in the pure copper container cavity under vacuum conditions to obtain a pre-sintered body; finally, oscillating hot pressing sintering is performed on the pre-sintered body to obtain a sintered green body, and removing the copper layer on the surface of the sintered green body to obtain a CuCr alloy; the raw metal powder consists of Cu powder and Cr powder.

[0008] The preparation method of the CuCr alloy of the present invention can reduce the gas content of the CuCr alloy, improve the density of the alloy, and improve the mixing degree of the Cu phase and the Cr phase by wet grinding Cu powder and Cr powder, vacuum sealing the Cu powder and Cr powder in the cavity of a pure copper container, and sintering by oscillation hot pressing, thereby obtaining a high-performance CuCr alloy. The CuCr alloy prepared by the preparation method of the CuCr alloy of the present invention has high structural density, fine grains, low gas content, and excellent insulation performance, and can fully meet the structural performance requirements of the vacuum interrupter for the CuCr contact, and can be used for the manufacture of the CuCr contact of the vacuum series product interrupter, effectively ensuring the improvement of the operating reliability of the vacuum series product.

[0009] Preferably, the sintering temperature of the oscillating hot pressing sintering is 1200-1250° C., and the sintering time is 60-90 min.

[0010] Preferably, an oscillating pressure is applied during the oscillating hot pressing sintering process, the oscillation frequency is 8 to 15 Hz, the median oscillation pressure is 30 to 60 MPa, and the amplitude is 5 to 15 MPa.

[0011] Preferably, the mass ratio of Cu powder to Cr powder is (1-3):1.

[0012] Preferably, the average particle size of the Cu powder and the Cr powder is less than 10 μm.

[0013] Preferably, the mass ratio of the raw metal powder to the liquid medium is 1:(1-3).

[0014] Preferably, the liquid medium is ethanol.

[0015] Preferably, the method of removing the liquid medium in the slurry under vacuum and sealing the slurry after the liquid medium is removed in the cavity of a pure copper container under vacuum conditions is as follows: after pouring the slurry into the cavity of the pure copper container, adding solder between the pure copper container and the container cover, performing a first heating process under vacuum conditions to remove the liquid medium in the slurry, and then performing a second heating process to achieve brazing to seal the cavity of the pure copper container.

[0016] Preferably, the temperature of the first heating process is 300-400° C., and the insulation time is 30-35 min; the temperature of the second heating process is 595-605° C., and the insulation time is 15-18 min.

[0017] The technical solution adopted by the application of the CuCr alloy in the arc extinguishing chamber contact of the present invention is:

[0018] Application of CuCr alloy prepared by the method for preparing CuCr alloy as described above in arc extinguishing chamber contacts.

[0019] The CuCr alloy of the present invention has high density, fine grains and low gas content, and can fully meet the organizational performance requirements of the vacuum interrupter for the CuCr contacts, and can be used for the manufacture of CuCr contacts for the interrupter of vacuum series products, effectively ensuring the improvement of the operating reliability of the vacuum series products. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the process of preparing the CuCr alloy of Example 1 of the present invention;

[0021] Figure 2 This is a schematic structural diagram of a cylindrical pure copper container sealed by a lid in Example 1 of the present invention;

[0022] Figure 3 The microstructure photographs of the CuCr alloy material prepared by the infiltration method, arc melting method and this embodiment in the present invention. DETAILED DESCRIPTION

[0023] The preparation method of the CuCr alloy of the present invention is a pioneering invention. The preparation method of the CuCr alloy of the present invention can effectively remove the gas in the raw material and improve the density of the CuCr alloy through three steps of wet grinding, vacuum brazing and vacuum oscillation hot pressing sintering, thereby obtaining a CuCr alloy with high density, fine grains, low gas content and excellent insulation performance.

[0024] The technical solution of the present invention is described in detail below in conjunction with specific embodiments.

[0025] 1. The specific embodiment of the preparation method of the CuCr alloy of the present invention is as follows:

[0026] Example 1

[0027] The preparation method of the CuCr alloy of this embodiment is as follows: Figure 1 As shown, the specific steps include:

[0028] (1) Add raw metal powder to a grinding jar, then add grinding balls and ethanol, the mass ratio of grinding balls, raw metal powder and ethanol is 4:1:3, the raw metal powder is composed of Cu powder and Cr powder with a mass ratio of 1:1, Cu powder and Cr powder are both spherical, the purity is ≥99.6%, and the average particle size is <10μm; then place the grinding jar in a planetary ball mill, start grinding, first ball mill at a low speed of 100rpm for 1h, and then high-speed ball milling at a speed of 280rpm for 2h. During the wet grinding process, ethanol contacts the raw metal powder. As the grinding proceeds, the gas in the gaps of the raw metal powder is gradually replaced by ethanol, which can avoid gas residue in the metal matrix during sintering, thereby reducing the gas content.

[0029] (2) After the grinding is completed, transfer the grinding jar to a vacuum glove box, slowly open the valve on the grinding jar to avoid sudden fluctuations in pressure inside and outside the jar, take out the grinding balls in the grinding jar, pour the remaining CuCr slurry in the grinding jar into the cavity of a cylindrical pure copper container, and then add a paste of AlSiCuMg solder (liquidus temperature 560°C, solidus temperature 500°C) into the reserved gap between the contact position of the cylindrical pure copper container and the lid. The ratio of the volume of the CuCr slurry added to the cavity of the cylindrical pure copper container to the volume of the cavity of the cylindrical pure copper container is not less than 9:10, which can ensure the density of the material. In this embodiment, the wall thickness of the cylindrical pure copper container is 1 mm, and the ratio of the volume of the CuCr slurry added to the cavity of the cylindrical pure copper container to the volume of the cavity of the cylindrical pure copper container is 9:10. In this step, the vacuum degree in the vacuum glove box is 10 -4 Pa.

[0030] (3) Place the cylindrical pure copper container with a lid and CuCr slurry in a vacuum brazing furnace. Before heating the furnace, pump the furnace to 10 -3 Pa cold vacuum, and then start heating, first raise the temperature of the vacuum furnace to 400℃, the heating rate is 25℃ / min, the holding time is 35min, so that the anhydrous ethanol in the CuCr slurry is fully volatilized, and the furnace is evacuated to 10 -5 Pa, and then continue to heat the vacuum furnace to 605℃, with a heating rate of 20℃ / min and a holding time of 18min, so that the solder is fully melted to fill the reserved gap between the cylindrical pure copper container and the lid. After the solder solidifies, the cylindrical pure copper container and the lid are in a completely sealed state. The structural diagram of the cylindrical pure copper container sealed by the lid is shown in Figure 2 shown.

[0031] (4) The cylindrical pure copper container sealed by the lid is placed in the mold of the oscillating hot press machine for oscillating hot pressing sintering. During the oscillating hot pressing sintering process, the vacuum degree in the oscillating hot press mold is maintained at 10 -5 Pa or more, after sintering, cool to room temperature with the furnace. During oscillating hot pressing sintering, the sintering temperature is 1250℃, the heating rate is 10℃ / min, the sintering time is 90min, and an oscillating pressure with a sinusoidal waveform is applied during sintering. The oscillation frequency is 15Hz, the median oscillation pressure is 50MPa, and the amplitude is 10MPa. The CuCr alloy material is prepared by oscillating hot pressing sintering process. Under oscillating pressure, the particle rearrangement and volume shrinkage are accelerated in the early stage of sintering, and a higher packing density is obtained; in the middle and late stages of sintering, the rotation, slip and plastic flow of the grains increase, which can accelerate the densification rate, effectively inhibit grain growth, and improve the density and two-phase uniformity of the CuCr alloy.

[0032] (5) Take out the sintered green body from the mold of the oscillating hot press, and use a lathe to turn off the pure Cu on the outer layer of the sintered green body to obtain a low-gas-content fine-grained CuCr alloy material. The microstructure of the low-gas-content fine-grained CuCr alloy material was analyzed by scanning electron microscopy. The results showed that the average grain size of the CuCr alloy material was 4 μm, the oxygen content was ≤0.05wt%, the nitrogen content was ≤0.004wt%, the conductivity was ≥19MS / m, and the density was ≥7.9g / cm3 measured by a high-precision metal material density meter. 3 The average grain sizes of CuCr alloy materials with the same composition prepared by infiltration and arc melting are 56μm and 43μm, respectively, the oxygen content is 0.09wt% and 0.085wt%, the nitrogen content is 0.0065wt% and 0.006wt%, respectively, the conductivity is 16MS / m and 17.5MS / m, respectively, and the density is 7.65g / cm 3 and 7.7 g / cm 3 The microstructure photos of the CuCr alloy materials prepared by the infiltration method, arc melting method and this embodiment are shown in FIG. Figure 3 As shown, Figure 3 From left to right in the figure are microstructure photographs of CuCr alloy materials prepared by the infiltration method, arc melting method and this embodiment.

[0033] Example 2

[0034] The preparation method of the CuCr alloy of this embodiment specifically comprises the following steps:

[0035] (1) Add raw metal powder into a grinding jar, and then add grinding balls and ethanol, the mass ratio of grinding balls, raw metal powder and ethanol is 2:1:1, the raw metal powder is composed of Cu powder and Cr powder with a mass ratio of 2:1, the Cu powder and Cr powder are both spherical, the purity is ≥99.6%, and the average particle size is <10μm; then place the grinding jar in a planetary ball mill, start grinding, first ball mill at a low speed of 100rpm for 1h, and then high-speed ball mill mixing at a speed of 280rpm for 2h.

[0036] (2) After the grinding is completed, transfer the grinding jar to a vacuum glove box, slowly open the valve on the grinding jar to avoid sudden fluctuations in pressure inside and outside the jar, take out the grinding balls in the grinding jar, pour the remaining CuCr slurry in the grinding jar into the cavity of the cylindrical pure copper container, and then add paste AlSiCuMg solder (liquidus temperature 560°C, solidus temperature 500°C) into the reserved gap between the cylindrical pure copper container and the lid. The wall thickness of the cylindrical pure copper container is 1 mm, and the ratio of the volume of the CuCr slurry to the volume of the cylindrical pure copper container cavity is 9:10. In this step, the vacuum degree in the vacuum glove box is 10 -4 Pa.

[0037] (3) Place the cylindrical pure copper container with a lid and CuCr slurry in a vacuum brazing furnace. Before heating the furnace, pump the furnace to 10 -3 Pa cold vacuum, and then start heating, first raise the temperature of the vacuum furnace to 300℃, the heating rate is 20℃ / min, the heat preservation time is 30min, so that the anhydrous ethanol in the CuCr slurry is fully volatilized, and the furnace is evacuated to 10 -5 Pa, and then continue to heat the vacuum furnace to 595°C, with a heating rate of 15°C / min and a holding time of 15min, so that the solder can fully melt and fill the reserved gap between the cylindrical pure copper container and the lid. After the solder solidifies, the cylindrical pure copper container and the lid are in a completely sealed state.

[0038] (4) The cylindrical pure copper container sealed by the lid is placed in the mold of the oscillating hot press machine for oscillating hot pressing sintering. During the oscillating hot pressing sintering process, the vacuum degree in the oscillating hot press mold is maintained at 10 -5 Pa, after sintering, it is cooled to room temperature with the furnace. During oscillation hot pressing sintering, the sintering temperature is 1200℃, the heating rate is 10℃ / min, the sintering time is 60min, and an oscillating pressure with a sinusoidal waveform is applied during the sintering process. The oscillation frequency is 8Hz, the median oscillation pressure is 30MPa, and the amplitude is 5MPa.

[0039] (5) Take out the sintered green body from the mold of the oscillating hot press, and use a lathe to turn off the pure Cu on the outer layer of the sintered green body to obtain a low-gas-content fine-grained CuCr alloy material. The microstructure of the low-gas-content fine-grained CuCr alloy material was analyzed by scanning electron microscopy. The results showed that the average grain size of the CuCr alloy material was 3 μm, the oxygen content was ≤0.045wt% and the nitrogen content was ≤0.004wt% measured by an oxygen, nitrogen and hydrogen analyzer, the conductivity was ≥19MS / m measured by a conductivity analyzer, and the density was ≥8.1g / cm measured by a high-precision metal material density meter. 3 .

[0040] Example 3

[0041] The preparation method of the CuCr alloy of this embodiment specifically comprises the following steps:

[0042] (1) Add raw metal powder into a grinding jar, then add grinding balls and ethanol, the mass ratio of grinding balls, raw metal powder and ethanol is 3:1:2, the raw metal powder is composed of Cu powder and Cr powder with a mass ratio of 3:1, the Cu powder and Cr powder are both spherical, the purity is ≥99.6%, and the average particle size is <10μm; then place the grinding jar in a planetary ball mill, start grinding, first ball mill at a low speed of 100rpm for 1h, and then high-speed ball mill mixing at a speed of 280rpm for 2h.

[0043] (2) After the grinding is completed, transfer the grinding jar to a vacuum glove box, slowly open the valve on the grinding jar to avoid sudden fluctuations in pressure inside and outside the jar, take out the grinding balls in the grinding jar, pour the remaining CuCr slurry in the grinding jar into the cavity of the cylindrical pure copper container, and then add paste AlSiCuMg solder (liquidus temperature 560°C, solidus temperature 500°C) into the reserved gap between the cylindrical pure copper container and the lid. The wall thickness of the cylindrical pure copper container is 1 mm, and the ratio of the volume of the CuCr slurry to the volume of the cylindrical pure copper container cavity is 9:10. In this step, the vacuum degree in the vacuum glove box is 10 -4 Pa.

[0044] (3) Place the cylindrical pure copper container with a lid and CuCr slurry in a vacuum brazing furnace. Before heating the furnace, pump the furnace to 10 -3 Pa cold vacuum, and then start heating, first raise the vacuum furnace to 350℃, the heating rate is 23℃ / min, the holding time is 34min, so that the anhydrous ethanol in the CuCr slurry is fully volatilized, and the furnace is evacuated to 10 -5Pa, and then continue to heat the vacuum furnace to 600 ° C, with a heating rate of 18 ° C / min and a holding time of 17 min, so that the solder can fully melt and fill the reserved gap between the cylindrical pure copper container and the lid. After the solder solidifies, the cylindrical pure copper container and the lid are in a completely sealed state.

[0045] (4) The cylindrical pure copper container sealed by the lid is placed in the mold of the oscillating hot press machine for oscillating hot pressing sintering. During the oscillating hot pressing sintering process, the vacuum degree in the oscillating hot press mold is maintained at 10 -5 Pa, after sintering, it is cooled to room temperature with the furnace. During oscillation hot pressing sintering, the sintering temperature is 1230℃, the heating rate is 10℃ / min, the sintering time is 75min, and an oscillating pressure with a sinusoidal waveform is applied during the sintering process. The oscillation frequency is 12Hz, the median oscillation pressure is 60MPa, and the amplitude is 15MPa.

[0046] (5) Take out the sintered green body from the mold of the oscillating hot press, and use a lathe to turn off the pure Cu on the outer layer of the sintered green body to obtain a low-gas-content fine-grained CuCr alloy material. The microstructure of the low-gas-content fine-grained CuCr alloy material was analyzed by scanning electron microscopy. The results showed that the average grain size of the CuCr alloy material was 2.5 μm, the oxygen content was ≤0.05wt% and the nitrogen content was ≤0.0035wt% as measured by an oxygen, nitrogen and hydrogen analyzer, the conductivity was ≥19.5MS / m as measured by a conductivity analyzer, and the density was ≥8g / cm as measured by a high-precision metal material density meter. 3 .

[0047] 2. The specific embodiments of the application of the CuCr alloy of the present invention in the arc extinguishing chamber contact are as follows:

[0048] In this embodiment, the CuCr alloy prepared by any of the preparation methods of the CuCr alloy in Embodiments 1-3 is used to prepare the vacuum interrupter contact.

Claims

1. A method for preparing a CuCr alloy, characterized in that: The following steps are involved: Firstly, the raw metal powder and the liquid medium are wet-grinded to obtain slurry; then, the slurry is poured into the cavity of a pure copper container under vacuum conditions, and then, the liquid medium in the slurry is removed under vacuum conditions, and then, the slurry after the liquid medium is removed is sealed in the cavity of the pure copper container under vacuum conditions to obtain a pre-sintered body; finally, the pre-sintered body is subjected to oscillation hot pressing sintering to obtain a sintered green body, and the copper layer on the surface of the sintered green body is removed to obtain a CuCr alloy; The raw metal powder consists of Cu powder and Cr powder.

2. The method for preparing the CuCr alloy according to claim 1, characterized in that: The sintering temperature of the oscillation hot pressing sintering is 1200-1250°C, and the sintering time is 60-90 minutes.

3. The method for preparing the CuCr alloy according to claim 1 or 2, characterized in that: During the oscillating hot pressing sintering process, an oscillating pressure is applied, the oscillation frequency is 8 to 15 Hz, the median oscillation pressure is 30 to 60 MPa, and the amplitude is 5 to 15 MPa.

4. The method for preparing the CuCr alloy according to claim 1, characterized in that: The mass ratio of Cu powder to Cr powder is (1-3):

1.

5. The method for preparing the CuCr alloy according to claim 1, characterized in that: The average particle size of Cu powder and Cr powder is less than 10 μm.

6. The method for preparing the CuCr alloy according to claim 1, characterized in that: The mass ratio of the raw metal powder to the liquid medium is 1:(1-3).

7. The method for preparing the CuCr alloy according to claim 1, characterized in that: The liquid medium is ethanol.

8. The method for preparing the CuCr alloy according to claim 1, characterized in that: The method for removing the liquid medium in the slurry under vacuum and sealing the slurry after the liquid medium is removed in the cavity of a pure copper container under vacuum conditions is as follows: after pouring the slurry into the cavity of the pure copper container, adding solder between the pure copper container and the container cover, performing a first heating process under vacuum conditions to remove the liquid medium in the slurry, and then performing a second heating process to achieve brazing to seal the cavity of the pure copper container.

9. The method for preparing the CuCr alloy according to claim 8, characterized in that: The temperature of the first heating process is 300-400° C., and the insulation time is 30-35 minutes; the temperature of the second heating process is 595-605° C., and the insulation time is 15-18 minutes.

10. Use of a CuCr alloy prepared by the method for preparing a CuCr alloy according to any one of claims 1 to 9 in an arc extinguishing chamber contact.

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