Modified copper-chromium alloy contact material, preparation method, electrical contact and application thereof

Abstract

The invention provides a modified copper-chromium alloy contact material, a preparation method, an electrical contact and application of the modified copper-chromium alloy contact material, and the modified copper-chromium alloy contact material comprises the following components in percentage by weight: 43-55.4% of copper, 0.03-0.07% of tantalum pentoxide and the balance of chromium and inevitable impurities. According to the modified copper-chromium alloy contact material disclosed by the invention, under the synergistic matching adjustment of a formula system taking tantalum pentoxide as a reinforcing phase and a preparation process, the synergistic improvement of force, electricity, frictional wear resistance and arc ablation resistance is realized, the modified copper-chromium alloy contact material has excellent comprehensive performance, and the conductivity of the modified copper-chromium alloy contact material disclosed by the invention is greater than or equal to 42.3% IACS (20 DEG C), and the conductivity of the modified copper-chromium alloy contact material is greater than or equal to 42.3% IACS (20 DEG C). The conductivity (Ms / m) is greater than or equal to 24.5, the hardness (HB) is greater than or equal to 102, and the arc ablation resistance is improved by greater than or equal to 25%. And the requirements of ablation wear and service reliability of the electric contact of the arc extinguish chamber of the vacuum circuit breaker applied to the voltage class of 72.5 kV and above are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical materials, and particularly provides a modified copper-chromium alloy contact material, a preparation method, an electrical contact and application thereof. BACKGROUND

[0002] As a core component of the arc-extinguishing chamber of a circuit breaker, the material comprehensive performance of the electrical contact directly determines the breaking capacity, operation reliability and service life of the circuit breaker. During the use of a vacuum circuit breaker, arc discharge occurs between the moving and static contacts, and the arc column energy is concentrated on the contact surface to form a local high-temperature zone (up to several thousand degrees Celsius), which causes the alloy contact material to melt, vaporize and diffuse, and results in significant ablation and wear.

[0003] The copper-chromium alloy is generally used as the arc contact material of the active vacuum circuit breaker, which can meet the basic requirements under conventional working conditions due to its high voltage resistance and low electrical ablation performance. However, under the harsh conditions of 72.5 kV and above higher voltage levels (the highest is currently 252 kV), the CuCr50 alloy still has technical bottlenecks. The copper-chromium contact prepared by traditional powder metallurgy, infiltration and arc smelting has random Cr phase distribution (segregation degree > 15%), which causes the breakdown field strength to fluctuate in the range of ± 30%, and when the large current is broken (> 63 kA), the Cr phase preferentially evaporates to form micro-pits, triggers local field strength distortion (the measured field strength gradient is more than 200 kV / mm 2 ), and causes arc reignition. When the CuCr alloy is nano-sized to refine the grain size to 1 μm, the breakdown voltage can be increased by 20%, but under high voltage levels, the risk of arc reignition caused by the aggregation of cathode spots still exists, which affects the safe and reliable operation of the vacuum circuit breaker, and increases the overall maintenance and operation cost of the circuit breaker. SUMMARY

[0004] The present application aims to solve the problems of easy ablation and wear of the contact material of the active 72.5 kV and above voltage level vacuum circuit breaker arc-extinguishing chamber and insufficient service reliability.

[0005] The present application is achieved by adopting the following technical solutions:

[0006] The present application provides a modified copper-chromium alloy contact material, which comprises, by weight percentage, copper 43%-55.4%, tantalum pentoxide 0.03%-0.07%, and the balance of chromium and inevitable impurities.

[0007] Preferably, the total content of impurities in the alloy contact material is ≤0.3%, and the content of iron in the alloy contact material is ≤0.01%.

[0008] Based on the same inventive concept, the application further provides a preparation method of the modified copper-chromium alloy contact material, comprising: powder mixing treatment: chromium powder, tantalum pentoxide powder and copper powder are weighed according to the proportion of the modified copper-chromium alloy contact material, the copper powder comprises mixed copper powder and infiltrated copper powder; the chromium powder, the tantalum pentoxide powder and the mixed copper powder are ground and mixed to obtain a mixed powder; green compact sintering: the mixed powder is loaded into a mold and formed by pressing, and then vacuum sintering is performed to obtain a sintered compact; infiltration treatment: the infiltrated copper powder and the sintered compact are vacuum infiltrated to obtain an infiltrated alloy body; annealing treatment: the infiltrated alloy body is placed in a transverse static magnetic field and annealed in a hydrogen atmosphere; surface treatment: a chromium thin film layer is deposited on the surface of the infiltrated alloy body after annealing by magnetron sputtering; mechanical heat treatment: the infiltrated alloy body with the deposited chromium thin film layer is repeatedly heated and cooled to obtain the alloy contact material.

[0009] Preferably, a 3D high-energy ball mill is used in the powder mixing treatment step, the ball milling rate of the ball mill is 1000 r / min-1200 r / min, the total ball milling time is 12 h-15 h, and the ball milling is paused for 15 min every 1 h.

[0010] Preferably, the ball mill is filled with argon, and the ball milling medium of the ball mill uses zirconia ceramic balls and anhydrous ethanol, and the ball-to-charge mass ratio of the ball mill is 8:1.

[0011] Preferably, the mixed copper powder accounts for 18.8%-21.2% of the total mass of the raw materials of the alloy contact material.

[0012] Preferably, the purity of the chromium powder and the copper powder is ≥99.8%, and the purity of the tantalum pentoxide powder is ≥99.9%.

[0013] Preferably, the average particle size of the chromium powder is 5 μm-10 μm; and / or the average particle size of the copper powder is 2 μm-5 μm; and / or the average particle size of the tantalum pentoxide powder is ≤1 μm.

[0014] Preferably, an isostatic pressing forming machine is used in the green compact sintering step, the mixed powder is loaded into a mold and ultrasonically vibrated for 10 min-20 min, the green compact pressure is 500 Mpa-600 Mpa, and the pressure holding time is 180 s-300 s to prepare a green body.

[0015] Preferably, a vacuum sintering furnace is used in the green compact sintering step, the green body is degassed by heating, the degassing temperature is 320℃-350℃, and the degassing time is 23 min-28 min; then the green body is sintered in a vacuum degree of 0.3×10 -2 Pa-0.8×10 -2Pa, the sintering temperature is 1250-1300℃, and the sintering time is 1.5-2h.

[0016] Preferably, the step of solution treatment is performed in a solution treatment furnace, and the vacuum degree of the solution treatment furnace is 0.3×10 -2 Pa-0.8×10 -2 Pa, the solution treatment temperature is 1200-1250℃, and the solution treatment time is 1.2-1.8h.

[0017] Preferably, the step of annealing treatment is performed at an annealing temperature of 820-880℃, and the annealing time is 1.2-2.5h, the magnetic field strength of the transverse static magnetic field is 0.5-1.5T, and the direction of the transverse static magnetic field is perpendicular to the direction of the current flowing through the solution treated alloy body.

[0018] Preferably, the step of surface treatment is performed by using a magnetron sputtering coating machine, the sputtering power of the coating machine is 100-300W, the sputtering pressure is 0.3-1.0Pa, the target-substrate distance is 50-100mm, the substrate temperature is 100-300℃, and the sputtering time is 2-4h.

[0019] Preferably, the step of mechanical heat treatment is performed by repeating the heating and cooling for 2-4 times, the heating temperature is 900-950℃, the heating time is 2-4h, the cooling temperature is 450-500℃, and the holding time is 2-4h.

[0020] Based on the same inventive concept, the application further provides an electric contact made of the modified copper-chromium alloy contact material, and the electric contact is applied to a vacuum circuit breaker with a voltage level of no less than 72.5kV.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] The application provides a modified copper-chromium alloy contact material, which comprises, in percentage by weight: copper 43-55.4%, tantalum pentoxide 0.03-0.07%, and the balance being chromium and inevitable impurities.

[0023] The tantalum pentoxide (Ta2O5) has a very high melting point and excellent thermal stability, and is uniformly dispersed in the copper-chromium (CuCr) matrix as a reinforcing phase. At high arc temperatures, the tantalum pentoxide can inhibit matrix recrystallization and grain growth by pinning grain boundaries, maintain microstructure stability, hinder dislocation movement, improve high-temperature creep resistance, delay material deformation and flow, increase material hardness, and significantly reduce mechanical wear rate. The tantalum pentoxide can also consume arc energy by endothermic decomposition reaction in the arc effect, reduce local temperature peak, reduce carrier scattering, improve electron migration efficiency, and enhance the anti-ablation performance. DETAILED DESCRIPTION

[0024] In order to make the skilled in the art better understand the technical solutions of the present application, the preferred embodiments of the present application are described below in combination with the best embodiments of specific applications. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0025] In the following examples, the experimental methods or test methods are conventional methods unless otherwise specified, and the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0026] The application provides a modified copper-chromium alloy contact material, which comprises, in percentage by weight: copper 43-55.4%, tantalum pentoxide 0.03-0.07%, and the balance being chromium and inevitable impurities.

[0027] The total impurity content in the alloy contact material is less than or equal to 0.3%, and the impurity iron content in the alloy contact material is less than or equal to 0.01%. The total impurity content is controlled to ensure the electrical conductivity and mechanical properties.

[0028] The application further provides a preparation method of the modified copper-chromium alloy contact material.

[0029] S1: mixing powder treatment: the chromium powder, the tantalum pentoxide powder and the copper powder are weighed according to the above-mentioned proportion of the modified copper-chromium alloy contact material, the copper powder includes the mixed copper powder and the copper powder to be infiltrated, the chromium powder, the tantalum pentoxide powder and the mixed copper powder are ground and mixed to obtain a mixed powder.

[0030] In the S1 step, a 3D high-energy ball mill is used and argon is filled to prevent the mixed powder from being oxidized, the ball milling is carried out at room temperature, the ball milling speed of the ball mill is 1000r / min-1200r / min, the total ball milling time is 12h-15h, and the ball mill is stopped for 15min every 1h. Zirconia ceramic balls and anhydrous ethanol are used as the ball milling medium of the ball mill, and the ball-to-charge mass ratio of the ball mill is 8:1. The mixed copper powder accounts for 18.8%-21.2% of the total mass of the raw materials of the alloy contact material. The raw materials are uniformly distributed in the copper-chromium matrix through 3D high-energy ball milling.

[0031] The purity of the chromium powder and the copper powder in the raw materials is greater than or equal to 99.8% (mass percent), the purity of the tantalum pentoxide powder is greater than or equal to 99.9% (mass percent), the total impurity content in the copper-chromium alloy contact material is less than or equal to 0.3%, and the impurity iron content in the alloy contact material is less than or equal to 0.01%. The average particle size of the chromium powder is 5-10μm, the average particle size of the copper powder is 2-5μm, and the average particle size of the tantalum pentoxide powder is less than or equal to 1μm. Finally, the copper-tungsten alloy material is realized to be uniform and dense in microstructure, the relative density is greater than 99.0%, and there is no obvious defect such as crack and hole in the internal part.

[0032] S2: pressing and sintering: the mixed powder is loaded into a mold to be formed into a green body, and then vacuum sintering is performed to obtain a sintered body;

[0033] In the S2 step, an isostatic pressing machine and a vacuum sintering furnace are used for processing. First, the mixed powder is loaded into a tungsten steel mold and ultrasonic vibration is performed for 10-20min, and the loose relative density is 40%-50%. Then, the green body is pressed under the conditions of a pressing pressure of 500-600Mpa and a pressure holding time of 180-300s, and the green body density is 50%-60% of the theoretical density.

[0034] After pressing, the green body is placed in a vacuum sintering furnace. The green body is first subjected to a degassing operation at a degassing temperature of 320-350℃ for 23-28min. Then, the vacuum degree is controlled to be in the range of 0.3*10 -2Pa-0.8x10 -2 Pa, sintering temperature is 1250-1300℃, sintering time is 1.5-2h, and the sintered body is obtained by cooling to room temperature in the furnace.

[0035] It should be noted that the tantalum pentoxide powder is uniformly dispersed in the matrix as a reinforcing phase particle during sintering, which inhibits the recrystallization and grain growth of the matrix by pinning the grain boundary migration at high temperature, maintains the microstructure stability, improves the high-temperature creep resistance by hindering the dislocation movement, delays the material deformation and material flow, improves the material hardness, and significantly reduces the mechanical wear rate.

[0036] S3: vacuum infiltration treatment: the sintered body and the copper powder to be infiltrated are subjected to vacuum infiltration to obtain an infiltrated alloy body;

[0037] In this S3 step, the infiltration furnace is used for treatment, and after the surface of the sintered body is cleaned, the copper powder to be infiltrated is covered on the surface of the sintered body in the mold for vacuum infiltration treatment, and the vacuum degree of the infiltration furnace is 0.3x10 -2 Pa-0.8x10 - 2 Pa, the infiltration temperature is 1200-1250℃, the infiltration time of the infiltration treatment is 1.2-1.8h, and the infiltrated alloy body is obtained by cooling in the furnace.

[0038] It should be noted that the vacuum negative pressure infiltration process can significantly improve the infiltration performance of copper, so that the copper phase is uniformly distributed in the network around the chromium phase.

[0039] S4: annealing treatment: the infiltrated alloy body is placed in a transverse static magnetic field and annealed in a hydrogen atmosphere;

[0040] In this S4 step, the annealing furnace is used for treatment, and the infiltrated alloy body is placed in the annealing furnace in a hydrogen atmosphere, the annealing temperature is 820-880℃, the annealing time of the annealing treatment is 1.2-2.5h, and finally the furnace is cooled to room temperature. The magnetic field strength of the transverse static magnetic field is 0.5-1.5T, and the direction of the transverse static magnetic field is perpendicular to the direction of the current flowing through the infiltrated alloy body, i.e. the magnetic field type of the transverse magnetic field is perpendicular to the main axis of the material or the direction of the current.

[0041] The annealing treatment in the hydrogen atmosphere by using the annealing equipment not only helps to prevent the copper-chromium alloy material from being oxidized during the annealing process, but also helps to reduce the supersaturated solid solution chromium atoms in the copper matrix, refine the grain structure, and the dispersion of chromium particles helps to improve the electrical, mechanical properties and arc ablation resistance of the material.

[0042] A transverse static magnetic field is applied during annealing to arrange the chromium phase along the optimal arc resistance direction. When the chromium phase is arranged in a direction, a high-efficiency heat conduction channel can be formed to accelerate heat dissipation from the arc root area, thereby reducing the local molten pool depth. The chromium phase arranged in a direction optimizes the electron transmission path, reduces grain boundary scattering, and promotes the arc to expand along the arranged direction, thereby avoiding local concentrated ablation to form a deep pit.

[0043] S5 surface treatment: depositing a chromium film layer on the surface of the alloy body after annealing by magnetron sputtering;

[0044] In the S5 step, a magnetron sputtering coating machine is used, the sputtering power of the coating machine is 100 W-300 W, the sputtering pressure is 0.3 Pa-1.0 Pa, the target-substrate distance is 50 mm-100 mm, the substrate temperature is 100°C-300°C, the sputtering time is 2 h-4 h, and the thickness of the chromium film layer deposited by sputtering is 4 μm-20 μm.

[0045] It should be noted that arc ablation is the main cause of failure of alloy contact materials, that is, the molten alloy contact material will splash or flow under the action of arc force. By depositing a chromium film layer of a certain thickness on the surface of the alloy contact material, the molten layer can be better "anchored", and the spatter loss of the internal copper material can be reduced. At the same time, the strengthened interface can delay the speed of ablation expansion to the internal material or interlayer, prolong the contact life, enhance the arc ablation resistance, improve the ability of the interface area to resist arc high-temperature melting, spatter, evaporation and chemical corrosion (oxidation, sulfuration), and reduce material loss.

[0046] In addition, the infiltrated alloy body can be machined into a customized shape, and a chromium film layer can be deposited on the surface thereof.

[0047] S6 mechanical heat treatment: repeatedly heating and cooling the infiltrated alloy body with a deposited chromium film layer to obtain an alloy contact material.

[0048] In the S6 step, the number of repetitions of heating and cooling is 2-4 times, the heating temperature is 900°C-950°C, the heating time is 2 h-4 h, the cooling temperature is 450°C-500°C, and the holding time is 2 h-4 h.

[0049] It should be noted that single heat treatment is prone to work hardening, increased brittleness, or cracking. This step can effectively release the internal stress accumulated in the previous processing (such as stress relief annealing), reduce defects such as microcracks and pores, and avoid cracking or deformation of the contact material due to stress concentration during service. By adjusting the deformation amount, temperature and cooling rate at different stages, a performance gradient can be formed in the contact material, taking into account the arc ablation resistance and electrical efficiency, and providing overall performance of the contact material.

[0050] Finally, the prepared modified copper-chromium alloy contact material has uniform copper binder phase distribution, so that the modified copper-chromium alloy contact material has excellent density, electrical conductivity, tensile strength, bending strength, hardness, friction and wear resistance, and arc ablation resistance. The electrical conductivity is greater than or equal to 42.3% IACS (20 DEG C), the electrical conductivity (Ms / m) is greater than or equal to 24.5, the hardness (HB) is greater than or equal to 102, and the arc ablation resistance is increased by greater than or equal to 25%.

[0051] The application also provides an electric contact made of the prepared modified copper-chromium alloy contact material, and the electric contact is applied to a vacuum circuit breaker with a voltage level of not less than 72.5 kV.

[0052] The electric contact can well meet the service requirements of the vacuum circuit breaker with a voltage level of 72.5 kV and above, and ensure safe and reliable operation of the vacuum circuit breaker.

[0053] Examples 1-5 and Comparative Example 1

[0054] Examples 1-5 of the application respectively select the raw material ratio and preparation process parameters of the modified copper-chromium alloy contact material in the above different ranges, and the difference between Examples 1-5 and Comparative Example 1 is that Comparative Example 1 uses CuW50 copper-chromium alloy raw material without tantalum pentoxide.

[0055] In Table 1, the total mass of raw materials is 1000g as a reference for proportioning.

[0056] Table 1

[0057]

[0058] Table 2 is a preparation parameter comparison table of Examples 1-5 and Comparative Example 1:

[0059] Table 2

[0060]

[0061]

[0062] It should be noted that some preparation parameters in Comparative Example 1 and Example 1 are the same, and details are shown in Table 2.

[0063] Test results

[0064] The alloy samples prepared in Examples 1-5 and Comparative Example 1 are tested for hardness, electrical conductivity, electrical conductivity, and arc ablation resistance.

[0065] Table 3 is a comparison table of the results of testing the performance of the alloy samples prepared in Examples 1-5 and Comparative Example 1. In Table 3, the requirements of GB / T 26867 standard for CuW50 are introduced to facilitate performance comparison and evaluation.

[0066] Table 3

[0067]

[0068] In the test of arc ablation resistance, the mass loss of the CuW50 alloy contact material without the addition of tantalum pentoxide in Comparative Example 1 in Table 3 is taken as the benchmark, denoted as 1. The arc ablation resistance of the modified copper-chromium alloy contact material doped with the composite trace reinforcing phase in Examples 1-5 in Table 3 is represented by the ratio of the mass loss of the sample of the same specification and model to the mass loss of the CuW50 alloy contact material in Comparative Example 1 after 200 opening and switching tests under the conditions of a simulated vacuum circuit breaker with an applied voltage of 20 kV and a current of 25 kA. It should be noted that the other test items are tested according to the conventional method unless otherwise specified.

[0069] As can be seen from Table 3, the modified copper-chromium alloy contact material doped with the composite trace reinforcing phase in Examples 1-5 has obvious advantages and performance improvement compared with Comparative Example 1, and the main performance indicators are superior to the performance requirements of the commonly used CuW50 alloy contact material for the active vacuum circuit breaker in GB / T 26867 “Technical Conditions for Copper-chromium Electrical Contact”. In particular, the conductivity of the modified copper-chromium alloy contact material is ≥ 42.3% IACS (20℃), the electrical conductivity (Ms / m) is ≥ 24.5, and the hardness (HB) is ≥ 102, while the arc ablation resistance is improved by ≥ 25%, which can well meet the application of the arc contact material in the 72.5 kV and above voltage grade vacuum circuit breaker.

[0070] The above are only examples of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application are included in the scope of the claims of the application to be granted.

Claims

1. A modified copper-chromium alloy contact material, characterized in that: Calculated by weight percentage, the alloy contact material includes: 43%-55.4% copper, 0.03%-0.07% tantalum pentoxide, and the balance being chromium and inevitable impurities thereof.

2. The modified copper-chromium alloy contact material according to claim 1, characterized in that: The total impurity content in the alloy contact material is ≤0.3%, and the impurity iron content in the alloy contact material is ≤0.01%.

3. A method for preparing a modified copper-chromium alloy contact material, characterized in that: include: Powder mixing treatment: weighing chromium powder, tantalum pentoxide powder and copper powder according to the ratio of the modified copper-chromium alloy contact material according to any one of claims 1-2, wherein the copper powder includes copper powder to be mixed and copper powder to be dissolved and infiltrated; grinding and mixing the chromium powder, the tantalum pentoxide powder and the copper powder to be mixed to obtain a mixed powder; Greenhouse pressing and sintering: the mixed powder is placed in a mold, pressed and formed, and then vacuum sintered to obtain a sintered greenhouse; Infiltration treatment: subjecting the copper powder to be infiltrated and the sintered green body to vacuum infiltration to obtain an infiltration alloy body; Annealing treatment: placing the infiltrated alloy body in a transverse static magnetic field and annealing it in a hydrogen atmosphere; Surface treatment: depositing a chromium thin film layer on the surface of the infiltrated alloy body by magnetron sputtering after annealing; Mechanical heat treatment: repeatedly heating and cooling the infiltrated alloy body with the deposited chromium film layer to obtain the alloy contact material.

4. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: The powder mixing step uses a 3D high-energy ball mill with a milling rate of 1000 r / min-1200 r / min and a total milling time of 12 h-15 h, with a 15-min pause for every 1 h of milling.

5. The method for preparing the modified copper-chromium alloy contact material according to claim 4, characterized in that: The ball mill is filled with argon gas, and the ball milling media of the ball mill are zirconia ceramic balls and anhydrous ethanol. The ball-to-material mass ratio of the ball mill is 8:

1.

6. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: The copper powder to be mixed accounts for 18.8%-21.2% of the total mass of the raw materials of the alloy contact material.

7. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: The purity of the chromium powder and the copper powder is ≥99.8%, and the purity of the tantalum pentoxide powder is ≥99.9%.

8. The method for preparing the modified copper-chromium alloy contact material according to claim 7, characterized in that: The average particle size of the chromium powder is 5 μm-10 μm; and / or The average particle size of the copper powder is 2 μm to 5 μm; and / or The average particle size of the tantalum pentoxide powder is ≤1 μm.

9. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: In the step of sintering the green compact, an isostatic pressing machine is used. The mixed powder is placed in a mold and ultrasonically vibrated for 10-20 minutes. The green compact is prepared under a pressing pressure of 500-600 MPa and a holding time of 180-300 seconds.

10. The method for preparing the modified copper-chromium alloy contact material according to claim 9, characterized in that: The green compact is first heated and degassed at a temperature of 320°C to 350°C for a time of 23 min to 28 min. The green compact is then sintered at a vacuum degree of 0.3×10 -2 Pa-0.8×10 -2 Pa, the sintering temperature is 1250° C.-1300° C., and the sintering time is 1.5 h-2 h to obtain the sintered green body.

11. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: The infiltration treatment step uses an infiltration furnace, and the vacuum degree of the infiltration furnace is 0.3×10 -2 Pa-0.8×10 -2 Pa, the dissolution temperature is 1200°C-1250°C, and the dissolution time of the dissolution treatment is 1.2h-1.8h.

12. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: In the annealing step, the annealing temperature is 820°C-880°C, the annealing time is 1.2h-2.5h, the magnetic field strength of the transverse static magnetic field is 0.5T-1.5T, and the direction of the transverse static magnetic field is perpendicular to the direction of the current flowing through the infiltration alloy body.

13. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: A magnetron sputtering coating machine is used in the surface treatment step. The sputtering power of the coating machine is 100W-300W, the sputtering gas pressure is 0.3Pa-1.0Pa, the target-substrate distance is 50mm-100mm, the substrate temperature is 100℃-300℃, and the sputtering time is 2h-4h.

14. The method for preparing the modified copper-chromium alloy contact material according to claim 3, characterized in that: In the mechanical heat treatment step, the heating and cooling are repeated 2-4 times, the heating temperature is 900°C-950°C, the heating time is 2h-4h, the cooling temperature is 450°C-500°C, and the holding time is 2h-4h.

15. An electrical contact, characterized in that: The electrical contact is made of the modified copper-chromium alloy contact material according to any one of claims 1 to 2, and is used in a vacuum circuit breaker with a voltage level of not less than 72.5 kV.

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