Fine-grained CuCr50 contact material and method for producing the same

Abstract

The application relates to the technical field of electric contact materials, and particularly discloses a fine-grain CuCr50 contact material and a preparation method thereof. The preparation method of the fine-grain CuCr50 contact material comprises the following steps: electrostatic spinning treatment is performed on a copper foil by using a chromium-containing spinning solution to obtain a spun copper foil; the spun copper foil is cold-pressed into a shape, and then hydrogen reduction and discharge plasma sintering treatment are sequentially performed to obtain the fine-grain CuCr50 contact material. According to the application, Cr fibers are generated on the surface of the copper foil through the electrostatic spinning technology, and the cold pressing, hydrogen reduction and discharge plasma sintering processes are combined to prepare the CuCr50 contact material which has a uniform fine-grain structure and excellent comprehensive performance, and the technical problems of the existing CuCr contact material, i.e., the coarse Cr phase grains and the poor mechanical and electrical properties of the CuCr contact material, are solved.

Description

Technical Field

[0001] This application relates to the field of electrical contact materials technology, and in particular to a fine-grained CuCr50 contact material and its preparation method. Background Technology

[0002] In medium- and high-voltage power systems, vacuum switches, circuit breakers, and contactors are core power control equipment, and the performance of their contact materials directly determines the equipment's operational reliability, breaking capacity, and service life. CuCr alloys, with their excellent electrical conductivity, resistance to arc erosion, resistance to welding, and reliable breaking capacity, have become the preferred material for the electrical contacts of such equipment. Among them, CuCr50 alloy with a chromium (Cr) mass fraction of approximately 50% is widely considered an ideal material for manufacturing electrical contacts for medium- and high-voltage vacuum switchgear due to its good match between electrical conductivity and arc resistance.

[0003] However, CuCr50 contact materials prepared using traditional methods generally suffer from the technical defect of coarse grains in the second phase (i.e., the Cr phase). This defect directly restricts the full realization of the excellent properties of the CuCr50 alloy, thereby affecting the operational stability of the electrical contacts and corresponding power equipment. Specifically, when an electric arc burns on the contact surface, the coarse Cr phase tends to result in fewer, larger, and unevenly distributed cathode spots, which tend to concentrate in the central region of the contact. This concentrated arc makes it difficult to precisely control the voltage drop on the contact surface, causing a sharp increase in local temperature, which in turn forms large ablation pits on the contact surface, accompanied by droplet splashing. This significantly exacerbates the erosion and loss of the contact material, ultimately leading to a substantial reduction in the electrical life and operational reliability of the electrical contacts, failing to meet the requirements of medium and high voltage power systems for long service life and high reliability.

[0004] To address the issue of coarse Cr phase grains, existing research has attempted to refine the grains using powder metallurgy and melt infiltration methods. However, these methods still have many limitations. They struggle to achieve a uniform and dense distribution of the Cr phase in the Cu matrix and suffer from difficulties in process control and high preparation costs. For example, in powder metallurgy, insufficient ball milling time can lead to inadequate grain refinement of the CuCr mixed powder, failing to effectively improve the coarse Cr phase defect. Furthermore, improper sintering process parameters can easily cause abnormal grain growth or insufficient densification of the contact material, thereby affecting the mechanical and electrical properties of the contact and failing to fundamentally solve the technical problem of coarse Cr phase grains in traditional CuCr50 contact materials. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a fine-grained CuCr50 contact material and its preparation method, so as to solve the technical problems of coarse Cr phase grains and poor mechanical and electrical properties of existing CuCr contact materials.

[0006] To achieve the above technical objectives, this application provides a method for preparing a fine-grained CuCr50 contact material, comprising the following steps:

[0007] Step S1: Electrospinning copper foil with chromium-containing spinning solution to obtain spun copper foil;

[0008] In step S2, the spun copper foil is cold-pressed into shape, and then subjected to hydrogen reduction and discharge plasma sintering treatments in sequence to obtain fine-grained CuCr50 contact material.

[0009] Furthermore, the chromium-containing spinning solution includes a chromium source, a polymeric carrier, a polar aprotic solvent, and an alcoholic solvent; wherein the molar concentration of the chromium source in the chromium-containing spinning solution is 0.05–0.15 mol / L, the mass concentration of the polymeric carrier in the chromium-containing spinning solution is 30–80 g / L, and the volume ratio of the polar aprotic solvent to the alcoholic solvent is 1:1.5–3.5.

[0010] Furthermore, the chromium source includes at least one of chromium nitrate, chromium chloride, and chromium acetate; and / or, the polymeric carrier includes at least one of polyvinylpyrrolidone, polyacrylonitrile, and polyethylene oxide; and / or, the polar aprotic solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; and / or, the alcohol solvent includes at least one of anhydrous ethanol, isopropanol, and n-propanol.

[0011] Furthermore, the parameters for electrospinning are: DC voltage of 16–20 kV, injection rate of 0.5–1 mL / h, and receiving distance of 15–20 cm.

[0012] Furthermore, the spun copper foil includes a copper foil and a spun fiber membrane attached to the surface of the copper foil. The spun fiber membrane is prepared by electrospinning from a chromium-containing spinning solution, and the thickness of the spun fiber membrane is 50–250 μm.

[0013] Furthermore, the cold pressing step is as follows: after folding the spun copper foil, it is cold pressed under a pressure of 20-30 MPa.

[0014] Further, the hydrogen reduction steps are as follows: under a hydrogen atmosphere, the temperature is increased to 200-300℃ at a heating rate of 1-2℃ / min and held for 0.5-1.5h; then the temperature is increased to 500-700℃ at a heating rate of 1-3℃ / min and held for 2-4h.

[0015] Furthermore, the spark plasma sintering process involves holding the temperature and pressure at 950–1050℃ and 30–50MPa for 5–15 minutes.

[0016] Furthermore, before electrospinning, the copper foil is pretreated, which includes the following steps: cleaning the copper foil with organic solvent and water in sequence, and then drying it in an inert atmosphere.

[0017] This application provides a fine-grained CuCr50 contact material, which is obtained by a method for preparing fine-grained CuCr50 contact material. By mass percentage, the fine-grained CuCr50 contact material includes the following components: Cr 49.5% to 50.5%, with the balance being Cu; Cr is uniformly bonded to the Cu surface in the form of grains, with an average grain size ≤1μm.

[0018] In summary, this application provides a method for preparing a fine-grained CuCr50 contact material, comprising the following steps: electrospinning copper foil with a chromium-containing spinning solution to obtain spun copper foil; cold pressing the spun copper foil into shape, followed by hydrogen reduction and spark plasma sintering treatments to obtain the fine-grained CuCr50 contact material. This application utilizes electrospinning technology to generate Cr fibers on the surface of copper foil, combined with cold pressing, hydrogen reduction, and spark plasma sintering processes, to prepare a CuCr50 contact material with a uniform fine-grained structure and excellent mechanical and electrical properties. In particular, it possesses excellent conductivity, resistance to arc erosion, resistance to welding, and good breaking capacity, making it an ideal contact material for manufacturing medium- and high-voltage vacuum switches, circuit breakers, and contactors, with broad development and application prospects.

[0019] Compared with the prior art, the fine-grained CuCr50 contact material prepared in this application has significantly refined and uniformly distributed Cr phase grains on its surface, and its comprehensive electrical and mechanical properties are also effectively improved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a process flow diagram for preparing fine-grained CuCr50 contact material in Example 1 of the present invention;

[0022] Figure 2 This is a microstructure image of the spun fiber membrane on the surface of the chromium wire copper foil prepared in Example 1 of the present invention;

[0023] Figure 3 This is a microstructure image of the fine-grained CuCr50 contact material prepared in Example 1 of the present invention.

[0024] Figure 4 The image shows the arc erosion morphology of the fine-grained CuCr50 contact material prepared in Example 1 of this invention.

[0025] Figure 5 This is a microstructure image of the CuCr50 contact material prepared in Comparative Example 1 of this invention.

[0026] Figure 6 This is an arc erosion morphology diagram of the CuCr50 contact material prepared in Comparative Example 1 of this invention.

[0027] Figure 7 This is a microstructure image of the CuCr50 contact material prepared in Comparative Example 2 of this invention.

[0028] Figure 8 This is an arc erosion morphology diagram of the CuCr50 contact material prepared in Comparative Example 2 of this invention. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0030] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0032] The raw materials used in this invention are not particularly restricted in their source; they can be purchased on the market or prepared using conventional methods known to those skilled in the art.

[0033] This application provides a method for preparing a fine-grained CuCr50 contact material, including the following steps:

[0034] Step S1: Electrospinning copper foil with chromium-containing spinning solution to obtain spun copper foil;

[0035] In step S2, the spun copper foil is cold-pressed into shape, and then subjected to hydrogen reduction and discharge plasma sintering treatments in sequence to obtain fine-grained CuCr50 contact material.

[0036] It should be noted that this application, through a combination of electrospinning, hydrogen reduction, and spark plasma sintering processes, can refine the average size of the Cr phase grains to below 1 μm, and the Cr phase is uniformly distributed in the Cu matrix without macroscopic agglomeration. The fine-grained CuCr50 electrical contact material prepared in this application has a microhardness ≥160 HV, significantly higher than that of fine-grained materials prepared by traditional ball milling combined with spark plasma sintering (approximately 144.15 HV), which can effectively improve the mechanical wear resistance of the contact material and extend its service life. The mechanism of action is as follows: A Cr-containing fiber structure is prepared on the surface of copper foil using electrospinning. After hydrogen reduction, the Cr phase particles are nano- to submicron-sized and highly uniformly and dispersedly distributed in the matrix. This microstructure allows for smaller, more numerous, and more uniformly distributed cathode spots during arc combustion, which helps reduce arc voltage, promotes rapid and uniform arc movement, avoids local overheating, and thus ensures stable and reliable operation of the electrical contacts.

[0037] It should be noted that this application refines the average size of the Cr phase grains to below 1 μm through precise control of electrospinning, hydrogen reduction, and discharge plasma sintering processes. Furthermore, the Cr phase is uniformly distributed within the Cu matrix without macroscopic agglomeration. The resulting fine-grained CuCr50 contact material exhibits a microhardness ≥160 HV, significantly higher than fine-grained materials prepared by traditional ball milling combined with discharge plasma sintering (approximately 144.15 HV). This effectively improves the mechanical wear resistance of the contact material and extends its service life. The reason for this is that Cr-containing fibers are generated on the copper foil surface through electrospinning. After hydrogen reduction, the Cr phase particles reach the nanometer to submicron level and are highly uniformly and dispersedly distributed within the material. This structure results in small, numerous, and uniformly distributed cathode spots during arc combustion, reducing the arc voltage and promoting faster and more dispersed arc movement, effectively preventing localized overheating and ensuring stable contact operation.

[0038] In some embodiments, the chromium-containing spinning solution includes a chromium source, a polymeric carrier, a polar aprotic solvent, and an alcoholic solvent; wherein the molar concentration of the chromium source in the chromium-containing spinning solution is 0.05–0.15 mol / L, the mass concentration of the polymeric carrier in the chromium-containing spinning solution is 30–80 g / L, and the volume ratio of the polar aprotic solvent to the alcoholic solvent is 1:1.5–3.5.

[0039] In some embodiments, the chromium source includes at least one of chromium nitrate, chromium chloride, and chromium acetate; and / or, the polymeric carrier includes at least one of polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), and polyethylene oxide (PEO); and / or, the polar aprotic solvent includes at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP); and / or, the alcohol solvent includes at least one of anhydrous ethanol, isopropanol, and n-propanol.

[0040] In some embodiments, the parameters for electrospinning are: DC voltage of 16-20 kV, injection rate of 0.5-1 mL / h, receiving distance of 15-20 cm, and needle type of 25G.

[0041] In some embodiments, the spun copper foil includes a copper foil and a spun fiber membrane attached to the surface of the copper foil. The spun fiber membrane is prepared by electrospinning from a chromium-containing spinning solution, and the thickness of the spun fiber membrane is 50–250 μm.

[0042] In some embodiments, the cold pressing step is as follows: after folding the spun copper foil, it is cold pressed under a pressure of 20-30 MPa.

[0043] In some embodiments, the hydrogen reduction step is as follows: under a hydrogen atmosphere, the temperature is increased to 200-300°C at a heating rate of 1-2°C / min and held for 0.5-1.5 h; then the temperature is increased to 500-700°C at a heating rate of 1-3°C / min and held for 2-4 h.

[0044] In some embodiments, the spark plasma sintering process involves holding the temperature and pressure at 950–1050°C and 30–50 MPa for 5–15 minutes.

[0045] In some embodiments, the copper foil is pretreated before electrospinning. The pretreatment includes the following steps: cleaning the copper foil with an organic solvent and water in sequence, and then drying it in an inert atmosphere.

[0046] In some specific embodiments, the pretreatment process of the copper foil is as follows: the copper foil is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 to 20 minutes each; after cleaning, it is dried with high-purity nitrogen or argon, or placed in a high vacuum environment at 50 to 60°C for drying; wherein, the thickness of the copper foil can be 18 to 70 μm.

[0047] This application provides a fine-grained CuCr50 contact material, which is obtained by a method for preparing fine-grained CuCr50 contact material. By mass percentage, the fine-grained CuCr50 contact material includes the following components: Cr 49.5% to 50.5%, with the balance being Cu. Cr is uniformly bonded to the Cu surface in the form of grains, with an average grain size ≤1μm.

[0048] In some preferred embodiments, the average grain size is 100–200 nm.

[0049] It should be noted that the fine-grained CuCr50 contact material has a smooth and clean surface, a uniform and dense internal structure, no pores or obvious defects, and achieves good metallurgical bonding with the substrate, with no interface contamination, ensuring the structural stability and reliability of the material.

[0050] The applicant further provides the following specific embodiments to describe the present invention. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0051] The test items and test methods involved in this application are as follows:

[0052] Morphology testing: The morphology of the material was observed and analyzed using a scanning electron microscope;

[0053] Density test: Based on Archimedes' principle, the density of the contact material was measured using a density meter (model: MH-300G, manufacturer: Shanghai Shuju Instrument Technology Co., Ltd.);

[0054] Conductivity testing: The conductivity of the contact material was measured using an eddy current conductivity meter (model: FD-102, manufacturer: Xiamen Fuste Electronic Technology Co., Ltd.).

[0055] Hardness test: The contact material was tested at room temperature using a Vickers hardness tester (model: MH-3, manufacturer: Jitai Scientific Instruments). The load applied during the test was 100g and the loading time was 3s.

[0056] Arc performance test: The arc performance of fine-grained CuCr50 contact material was tested under simulated actual working conditions of 50Hz and 15kA.

[0057] Anti-ablation performance test: After conducting an arc ablation test on the fine-grained CuCr50 contact material, observe whether large-area melting, cracking and splashing phenomena appear on its surface morphology.

[0058] Example 1

[0059] See Figure 1 This embodiment provides a fine-grained CuCr50 contact material, comprising the following preparation steps:

[0060] Step S1, copper foil pretreatment and preparation of chromium-containing spinning solution: 2g of copper foil with a thickness of 35μm was selected and ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10min each. After cleaning, the copper foil was dried with high-purity nitrogen to obtain a clean copper foil. 3g of chromium nitrate, 15g of polyvinylpyrrolidone, 80mL of N,N-dimethylformamide and 180mL of anhydrous ethanol were mixed and magnetically stirred for 12h to obtain the chromium-containing spinning solution.

[0061] Step S2: Using the cleaned copper foil as a receiving device, electrospinning is performed on the surface of the copper foil using a chromium-containing spinning solution. The parameters for electrospinning are: DC voltage 18kV, injection rate 0.75mL / h, receiving distance 18cm, and the needle used for spinning is 25G. Finally, a chromium wire copper foil with a surface spinning fiber film thickness of about 100μm is obtained.

[0062] Step S3: The chromium wire copper foil is repeatedly folded, placed into a mold with a diameter of 20 mm, and cold-pressed under a stress of 25 MPa. Then, hydrogen reduction treatment is carried out: under a hydrogen atmosphere, the temperature is raised to 250°C at a heating rate of 1°C / min and held for 1 hour, then raised to 600°C at a heating rate of 2°C / min and held for 3 hours. The furnace is then cooled to obtain CuCr material.

[0063] Step S4: The CuCr material is loaded into a graphite mold and placed in a spark plasma sintering furnace. It is kept at 1000℃ and 40MPa for 10 minutes and then cooled with the furnace to obtain fine-grained CuCr50 contact material.

[0064] Microstructure testing: such as Figure 2 As shown, the chromium-containing spun fiber membrane produced by electrospinning exhibits good continuity and uniformity; for example... Figure 3 As shown, the contact material contains only two phases, Cu and Cr, with no other impurities introduced, resulting in high purity. The Cr phase transforms into near-spherical grains, which are uniformly distributed on the Cu surface. Calculations show that the average size of the near-spherical grains is approximately 100–200 nm, thus solving the core defect of coarse Cr phase grains in traditional CuCr50 contact materials.

[0065] Physical performance testing: The contact material has a hardness of 160.29 HV, possessing excellent mechanical properties and effectively resisting mechanical losses under the action of electric arc; its electrical conductivity is 21.9 MS / m, which can meet the requirements of medium and high voltage vacuum switchgear for the conductivity of electrical contacts; its relative density is as high as 99.2%, with a high degree of densification, which can effectively avoid problems such as arc concentration and erosion caused by internal pores in the material, laying the foundation for its excellent electrical performance.

[0066] Arc performance test: The arc performance of the fine-grained CuCr50 contact material was tested under simulated actual working conditions of 50Hz and 15kA. The results showed that the cathode spot movement speed of the contact material reached 16.57m / s. Due to the uniformity and small size of the Cr phase grains in this embodiment, the cathode spot is evenly dispersed and not easily pinned. Although the movement speed is slightly lower, the overall arc behavior is more stable and the ablation is less. At the same time, its arc voltage drop is only 23.5V, which is significantly lower than that of traditional CuCr50 contact materials (Comparative Example 1 and Comparative Example 2). The voltage drop control effect is excellent, which can effectively reduce the occurrence of local overheating and further improve the contact material's resistance to arc erosion.

[0067] Ablation resistance test: After arc ablation test, the morphology of fine-grained CuCr50 contact material is characterized as follows: Figure 4 As shown, the surface of the contact material is generally flat after ablation, with no obvious large-sized ablation pits and less droplet splashing, indicating that it has excellent ablation resistance, which can effectively reduce material erosion and loss under the action of electric arc, thereby extending the electrical life of the electrical contacts, improving the reliability of equipment operation, and fully meeting the usage requirements of medium and high voltage power systems.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing CuCr50 contact material, including the following steps:

[0070] Step S1: Take Cu powder and Cr powder with a purity of 99.9% and an average particle size of 80 μm, and mix them at a mass ratio of 1:1 to obtain a mixed powder;

[0071] Step S2: The mixed powder is placed into a high-energy ball mill of model MSK-SFM-3-II with a ball-to-material ratio of 15:1. Anhydrous ethanol is added as a process control agent. The mixture is ball-milled at 900 r / min for 12 hours to obtain fine-grained CuCr50 composite powder.

[0072] Step S3: The fine-grained CuCr50 composite powder is annealed at 650°C under argon protection for 2 hours; then it is placed into a graphite mold and placed in a discharge plasma sintering furnace of model SPS-20T-10, and sintered at 1000°C and 40MPa pressure for 10 minutes to obtain a sintered blank.

[0073] Step S4: The sintered blank is machined into a standard contact sample by wire cutting. The standard contact sample has a diameter of 60 mm and a thickness of 4 mm.

[0074] Microstructure: such as Figure 5 As shown, the Cr phase transforms into irregularly shaped grains with poor uniformity of distribution; the average grain size is about 3 to 5 μm, and the defect of coarse Cr phase grains still exists.

[0075] Physical properties: Hardness is 144.15 HV, electrical conductivity is 22.3 MS / m, and relative density is 99.4%.

[0076] Arc performance: Under test conditions of 50Hz and 15kA current, the cathode spot moving speed of the contact material is 17.78m / s. However, due to the unevenness and large size of the Cr phase grains, the cathode spot is large and concentrated, which can easily cause local overheating and aggravate material corrosion. The arc voltage drop is as high as 27.4V.

[0077] Anti-ablation properties: such as Figure 6 As shown, after arc ablation, the surface of the contact material is rough, with large ablation pits and significant droplet solidification. Its ablation resistance is far inferior to that of the fine-grained CuCr50 contact material prepared in Example 1.

[0078] Comparative Example 2

[0079] This comparative example provides a method for preparing CuCr50 contact material, including the following steps:

[0080] Step 1: Take Cu powder and Cr powder with a purity of 99.9% and an average particle size of 80μm, and mix them at a mass ratio of 1:1 to obtain a mixed powder;

[0081] Step 2: Place the mixed powder into a high-energy ball mill of model MSK-SFM-3-II, set the ball-to-material ratio to 15:1, then add anhydrous ethanol as a process control agent, and ball mill at 900 r / min for 12 hours to obtain CuCr50 composite powder.

[0082] Step 3: The ball-milled CuCr50 composite powder is annealed at 650℃ under argon protection for 2 hours to remove internal stress; the annealed CuCr50 composite powder is loaded into a graphite mold and placed in an SPS-20T-10 discharge plasma sintering furnace, and sintered at 1000℃ and 40MPa pressure for 10 minutes to obtain a sintered blank.

[0083] Step 4: The sintered blank is processed into a substrate and a target by wire cutting. The diameter of the substrate and the target are both 60 mm and the thickness is 4 mm.

[0084] Step 5: Grind and polish the substrate and the target to remove the surface oxide layer and impurities. Then, use anhydrous ethanol and deionized water to ultrasonically clean for 10-15 minutes in sequence. After cleaning, dry with high-purity nitrogen.

[0085] Step 6, in 5×10 -5 In a high vacuum environment of Pa, the alloy target material is bombarded with ions to sputter and deposit the target atoms onto the substrate surface to form a thin film. During the deposition process, the substrate is kept at a rotation speed of 20-30 r / min / min, and the sputtering power is controlled at 80 W. After the sputtering deposition is completed, the CuCr50 contact material is obtained by in-situ vacuum annealing at 650 °C for 2 hours in the deposition chamber.

[0086] Microstructure: such as Figure 7 As shown, the contact material contains only two phases, Cu and Cr, with no other impurities introduced, resulting in good purity. The Cr phase is transformed into irregular grains with an average grain size of approximately 3–6 μm.

[0087] Physical properties: Hardness is 143.77 HV, electrical conductivity is 20.9 MS / m, and relative density is 99.0%.

[0088] Arc performance: Under the same test conditions of 50Hz and 15kA current, the cathode spot moving speed of the contact material is 17.78m / s, which is consistent with Comparative Example 1. However, due to the unevenness and large size of the Cr phase grains, the cathode spot is large and concentrated, which easily leads to excessive local temperature and poor arc control effect; the arc voltage drop is as high as 29.9V.

[0089] Anti-ablation properties: such as Figure 8 As shown, after arc ablation, the surface of the contact material is slightly uneven, with small-area and shallow-depth ablation pits, and some droplet splashing occurs; its ablation resistance is better than that of Comparative Example 1, but far inferior to that of Example 1.

[0090] Table 1. Summary of the properties of contact materials prepared in Example 1, Comparative Example 1, and Comparative Example 2

[0091]

[0092] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a fine-grained CuCr50 contact material, characterized in that, Includes the following steps: Step S1: Electrospinning copper foil with chromium-containing spinning solution to obtain spun copper foil; Step S2 involves cold pressing the spun copper foil into shape, followed by hydrogen reduction and discharge plasma sintering treatments to obtain fine-grained CuCr50 contact material.

2. The method for preparing the fine-grained CuCr50 contact material according to claim 1, characterized in that, The chromium-containing spinning solution includes a chromium source, a polymer carrier, a polar aprotic solvent, and an alcohol solvent; The molar concentration of the chromium source in the chromium-containing spinning solution is 0.05–0.15 mol / L, the mass concentration of the polymer carrier in the chromium-containing spinning solution is 30–80 g / L, and the volume ratio of the polar aprotic solvent to the alcohol solvent is 1:1.5–3.

5.

3. The method for preparing fine-grained CuCr50 contact material according to claim 2, characterized in that: The chromium source includes at least one of chromium nitrate, chromium chloride, and chromium acetate; and / or, the polymeric carrier includes at least one of polyvinylpyrrolidone, polyacrylonitrile, and polyethylene oxide; and / or, the polar aprotic solvent includes at least one of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; and / or, the alcohol solvent includes at least one of anhydrous ethanol, isopropanol, and n-propanol.

4. The method for preparing the fine-grained CuCr50 contact material according to claim 1, characterized in that, The parameters for the electrospinning process are: DC voltage of 16-20 kV, injection rate of 0.5-1 mL / h, and receiving distance of 15-20 cm.

5. The method for preparing fine-grained CuCr50 contact material according to claim 1, characterized in that, The spun copper foil includes a copper foil and a spun fiber membrane attached to the surface of the copper foil. The spun fiber membrane is prepared by electrospinning from a chromium-containing spinning solution, and the thickness of the spun fiber membrane is 50-250 μm.

6. The method for preparing the fine-grained CuCr50 contact material according to claim 1, characterized in that, The cold pressing process involves folding the spun copper foil and then cold pressing it under a pressure of 20-30 MPa.

7. The method for preparing the fine-grained CuCr50 contact material according to claim 1, characterized in that, The hydrogen reduction steps are as follows: under a hydrogen atmosphere, the temperature is increased to 200-300℃ at a heating rate of 1-2℃ / min and held for 0.5-1.5h; then the temperature is increased to 500-700℃ at a heating rate of 1-3℃ / min and held for 2-4h.

8. The method for preparing the fine-grained CuCr50 contact material according to claim 1, characterized in that, The steps of the discharge plasma sintering treatment are as follows: heat and pressure are maintained at 950-1050℃ and 30-50MPa for 5-15 minutes.

9. The method for preparing the fine-grained CuCr50 contact material according to claim 1, characterized in that, Before the electrospinning process, the copper foil is pretreated, which includes the following steps: cleaning the copper foil with organic solvent and water in sequence, and then drying it in an inert atmosphere.

10. A fine-grained CuCr50 contact material, characterized in that, The fine-grained CuCr50 contact material is obtained by the preparation method of any one of claims 1 to 9; The fine-grained CuCr50 contact material comprises the following components by mass percentage: Cr 49.5% to 50.5%, with the balance being Cu; the Cr is uniformly bonded to the copper foil in the form of grains, and the average size of the grains is ≤1μm.

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