A composite electrical contact and method of making the same

Abstract

The application discloses a composite electric contact and a preparation method thereof. The preparation method comprises the following steps: mixing graphite powder and a binder to obtain a composite graphite material; mixing copper powder and a metal auxiliary material to obtain alloy powder; mixing the composite graphite material and the alloy powder to obtain mixed powder; performing hot-pressing forming treatment to obtain a formed blank; then, performing sintering, wherein the sintering temperature is first increased to 600-850 DEG C and kept for 1-4 hours, then increased to 900-1050 DEG C and kept for 1-4 hours, and then cooled to 30-90 DEG C by gas protection or vacuum protection, so as to obtain a contact blank; and processing the contact blank and a base to obtain the composite electric contact. The composite electric contact prepared by the method has excellent electric conductivity, high mechanical strength and good fatigue resistance, and is suitable for high-performance contact application in electrical switches, relays and other electrical equipment.

Description

Technical Field

[0001] This invention relates to the technical field of electrical contacts, and specifically to a composite electrical contact and its preparation method. Background Technology

[0002] Electrical contacts are key components in electrical equipment such as appliances, switches, relays, and contactors. Their main function is to reliably connect and disconnect circuits during the switching process. The material properties and structural form of electrical contacts directly affect the conductivity, operational reliability, and service life of electrical equipment.

[0003] Currently available electrical contact materials mostly use silver and silver-based alloys. Silver and silver-based materials have good electrical and thermal conductivity and are widely used in medium and low voltage electrical contact applications. High-melting-point metals such as tungsten and molybdenum are mostly used to withstand the cold forging of silver wires to prepare silver contacts. However, the above-mentioned traditional electrical contact materials are costly in practical use. Existing technologies typically introduce carbon-based materials into the metal matrix to reduce the surface temperature rise, suppress fusion welding, and improve contact separation performance. For example, by adding graphite or other carbon materials to the contact material, their good high-temperature resistance and self-lubricating properties can be utilized to slow down material loss during the switching process.

[0004] However, carbon-containing electrical contact materials on the market still have certain limitations. On the one hand, carbon materials lack sufficient dispersion and structural stability in the metal matrix, easily leading to local agglomeration or weak interfacial bonding, affecting the overall conductivity of the contacts. On the other hand, traditional carbon materials are mostly amorphous or structurally disordered, and under high-frequency switching and long-term operating conditions, they cannot withstand the impact of large current attraction and disconnection. Especially during current-carrying experiments (during disconnection), static and moving contacts will produce sparks as graphite and metal spheres detach, making it difficult to simultaneously achieve low contact resistance, good ablation resistance, and stable mechanical strength. Furthermore, existing electrical contact materials still have room for improvement in terms of manufacturing process complexity, material consistency, and long-term reliability.

[0005] Therefore, it is necessary to improve the materials and structural forms of electrical contacts in order to improve their resistance to arc erosion, wear resistance and stability of use while ensuring good conductivity, so as to meet the development needs of electrical equipment in terms of high reliability and long service life. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an electrical contact with excellent thermal and electrical conductivity, oxidation resistance, ablation resistance, and arc resistance, as well as a method for its preparation.

[0007] In a first aspect, the present invention discloses a method for preparing a composite electrical contact, comprising the following steps: S1. Graphite powder is mixed with a binder to obtain a composite graphite material; the binder is selected from at least one of phenolic resin, silicone resin, and asphalt; S2. Mix copper powder with metal additives to obtain alloy powder; S3. Mix the composite graphite material with the alloy powder to obtain a mixed powder; S4. The mixed powder is hot-pressed to obtain a molded blank; S5. The formed blank is sintered. During the sintering process, the temperature is first raised to 600-850℃ and held for 1-4 hours, then raised to 900-1050℃ and held for 1-4 hours, and then cooled to 30-90℃ to obtain the contact blank. By combining the contact blank with the base, a composite electrical contact is obtained.

[0008] In one optional embodiment, the mass ratio of graphite powder to binder in S1 is (70-90):(10-30); the mass ratio of copper powder to metal additives in S2 is (80-93):(7-20); and the mass ratio of composite graphite material to alloy powder in S3 is (10-30):(70-90).

[0009] In one optional embodiment, the metal additive is selected from at least one of silver powder, tin, titanium, tantalum powder, chromium powder, tungsten powder, and molybdenum powder.

[0010] In one optional embodiment, the hot pressing process described in S4 involves a temperature of 160-200°C, a pressure of 30-50 MPa, and a holding time of 2-4 seconds.

[0011] In one optional embodiment, the hot pressing process in S4 is performed at a temperature of 170°C and a pressure of 30 MPa.

[0012] In one optional embodiment, the connection between the contact blank and the base is specifically achieved by: in step S4, performing the hot pressing treatment on the mixed powder and the base together to form an integral shape; or by welding the base to the contact blank obtained in step S5. Other common connection methods can also be selected, such as crimping, bonding, or riveting.

[0013] In an alternative embodiment, the sintering and cooling process described in S5 is carried out in a vacuum, an inert atmosphere, or a reducing atmosphere.

[0014] In one optional embodiment, the vacuum degree of the vacuum sintering is 10. -3 -10 -5 Pa.

[0015] In one optional embodiment, the pressure of the inert atmosphere sintering or reducing atmosphere sintering is 0.1-1 MPa.

[0016] Secondly, the present invention also discloses a composite electrical contact prepared by the above-described preparation method.

[0017] The technical solution of this invention has the following advantages: (1) This invention introduces a binder into a graphite powder and metal powder system, and through hot pressing and oxygen-free high-temperature sintering, the binder undergoes pyrolysis and transforms into a carbonaceous structure during sintering, thereby forming a stable multiphase composite system between the metal phase and the graphite phase. This composite system avoids the problem of loose bonding between phases in traditional graphite-metal materials, which is beneficial to the stability of the overall material structure. The material obtained in this way is not prone to structural loosening or particle shedding under on / off conditions, can maintain a relatively stable electrical contact state, and has good anti-arc properties, anti-ablation properties, and electrical conductivity, while also enhancing its mechanical strength.

[0018] (2) The preparation method adopted in this invention has a clear process flow and is easy to produce; at the same time, by introducing graphite phase and carbon structure, it is beneficial to reduce the amount of precious metals used while meeting the requirements of electrical contact, thereby reducing production costs. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a side sectional view of the quadrilateral electrical contacts obtained in Embodiments 1-2 of the present invention; Figure 2 This is a top view of the quadrilateral metal base used in Embodiments 1-2 of the present invention; Figure 3 This is a top view of the circular metal base used in Embodiment 3 of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Contact blank; 2. Quadrilateral metal base; 3. Circular metal base. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0023] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0024] With the tightening supply and demand of silver and copper resources and the continuous rise in prices, this invention, through optimization of material system and structural design, can save approximately 30%–60% of the copper usage in a single traditional electrical contact point, while reducing the silver content by approximately 60%–95%. Compared with traditional electrical contact point materials, this invention significantly improves performance while effectively reducing material costs.

[0025] In the preparation process, resin or asphalt is used to coat the composite graphite alloy powder and metal powder particles, forming an in-situ carbonization coating layer during subsequent high-temperature sintering. This inhibits the uncontrolled oxidation of the carbon and metal phases under high-temperature conditions, ensuring the formation of an ordered structure and maintaining good electrical conductivity. After high-temperature sintering, the material forms a carbon-based ordered structure with an increased sp² carbon ratio and aromatic lamellar size, enhancing the delocalization of π electrons and forming a continuous carbon-based conductive network at the microscale. This improves the material's arc resistance, ablation resistance, and electrical conductivity, while also enhancing its mechanical strength and density, thus significantly improving the overall performance of electrical contacts.

[0026] To improve the anti-welding adhesion performance and conductivity of electrical contact points, resin or asphalt is added as a binder after graphite powder and metal powder are mixed. The mixture is then heated and pressed at 160–200°C, which softens the binder under temperature and pressure and allows it to flow rapidly, filling the gaps between the powder particles and between the powder and the metal substrate. Subsequently, the mixture is cured and shaped to improve the density of the molded body and prevent micro-rebound after demolding.

[0027] This invention employs segmented heating and sintering of the molded preform. First, it is held at approximately 600-800°C to allow the resin or asphalt to fully pyrolyze and release volatile components, avoiding defects such as blistering and cracking caused by gas retention due to rapid heating. Then, the temperature is further increased to 1050°C and held to promote further rearrangement and ordering of the carbonized carbon structure, thereby carbonizing the resin or asphalt and forming an ordered carbon phase structure. This carbon phase acts as a link between the graphite powder and the metal powder skeleton within the material, constructing a continuous and stable electrical and thermal conductivity pathway. Simultaneously, its structural characteristics endow the material with good solid lubrication and resistance to arc erosion, effectively reducing the risk of welding adhesion at electrical contacts during operation. Furthermore, this carbon phase can further reduce the material's porosity, improving overall mechanical strength and structural stability.

[0028] The graphite powder used in this invention is of the type Natural Flake Graphite-399, sourced from Qingdao Oul Graphite Co., Ltd.

[0029] The asphalt / resin used in this invention is FB88 high-temperature resin for metal graphite brushes (phenolic resin), sourced from Bengbu Tianyu High-Temperature Resin Materials Co., Ltd.

[0030] The metal additives used in this invention are: silver powder, tin, titanium, tantalum powder, chromium powder, tungsten powder, and molybdenum powder, which are from Nangong Zhongmai Metal Materials Co., Ltd.

[0031] The resistance testing method used in this invention is as follows: the HG2511 DC low resistance tester from Kexiang Instruments & Meters is used for measurement.

[0032] The Vickers hardness test method used in this invention is as follows: measurement is performed using a Vickers hardness tester with a manual turret, model HV-10 / 30 / 50, manufactured by Horiyo Precision Measuring Instruments Co., Ltd.

[0033] The bending strength test method used in this invention is as follows: measurement is performed using a Puyan PY-HLDY-1 1000N (manual model).

[0034] The greenhouse thermal conductivity test method used in this invention is as follows: measurement is performed using a Shenzhen Yusheng Instruments & Meters DT1310 high-precision industrial thermometer.

[0035] Example 1 This embodiment provides a method for preparing a composite electrical contact, including the following steps: (1) Preparation of composite graphite materials Weigh out 80% graphite powder and 20% binder by mass percentage, wherein the binder is FB88 resin diluted with ethanol. Add the graphite powder and FB88 resin to a mixing device and stir for 1 hour. During the mixing process, slowly raise the temperature, controlling the resin mixing temperature at 100°C, so that the FB88 resin uniformly coats the surface of the graphite powder under heating. Continue heating and stirring to remove moisture or solvent from the mixture, then discharge and allow it to cool naturally. After cooling, pulverize the resulting material to obtain the composite graphite material.

[0036] (2) Preparation of alloy powder Weigh out 87% electrolytic copper powder and 12% metallic auxiliary material by mass percentage, wherein the metallic auxiliary material is tungsten powder. Add the copper powder and tungsten powder to a drum mixer and mix for 2 hours to ensure uniform mixing, thereby obtaining alloy powder.

[0037] (3) Preparation of mixed powder The composite graphite material (20%) and alloy powder (80%) are added to a drum mixer and mixed for 2 hours to obtain a uniformly mixed powder.

[0038] (4) Hot pressing The molding die is heated to 170°C, and then the mixed powder is added to the die for hot pressing. The molding pressure is 30 MPa, and the holding time is 3 seconds. The mixed powder is then molded under the action of heating and pressure to obtain a molded blank.

[0039] (5) Oxygen-free sintering The formed blank is placed in a sintering furnace for sintering in a nitrogen atmosphere at a pressure of 0.5 MPa. The sintering temperature is raised to 800°C and held for 2 hours, then slowly raised to 1050°C and held for 2 hours. Subsequently, it is cooled to 50°C under gas protection or vacuum protection to obtain the contact blank 1.

[0040] (6) Base welding The contact blank 1 can be welded to a base of any shape. The contact blank 1 is welded to a quadrilateral metal base 2. Figure 2 This is a top view of the quadrilateral metal base used in this embodiment, showing the composite electrical contact, denoted as Sample 1. Figure 1 This is a side cross-sectional view of the quadrilateral electrical contact obtained in this embodiment.

[0041] The performance of sample 1 was tested, and the results are as follows: The relay contact resistance is within 1.5mΩ. Vickers hardness (HV): 110HV. Bending strength: 230MPa (three-point bending test, specimen 3x4x36mm, loading rate 1mm / min).

[0042] The results of 7000 electrical fatigue tests on a magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: the corrosion amount of the moving and stationary contacts was 110mg, the contacts did not stick during the opening and closing process, and the contact temperature did not exceed 85 degrees.

[0043] The product obtained from Sample 1 has significantly improved hardness and bending resistance. It does not break during contact processing and riveting and is easy to process and rivet.

[0044] Example 2 (1) Preparation of composite graphite materials Weigh out 70% graphite powder and 30% binder by mass percentage, wherein the binder is silicone resin. Add the graphite powder and silicone resin to a drum and stir to mix. No heating is required during the mixing process. Dry mix for 2-3 hours at a speed of 200-250 r / min to obtain a composite graphite material.

[0045] (2) Preparation of alloy powder Weigh out 80% electrolytic copper powder and 20% metal auxiliary material by mass percentage, wherein the metal auxiliary material is tungsten powder. Add the copper powder and tungsten powder to a drum mixer and mix for 2 hours to ensure uniform mixing, thereby obtaining alloy powder.

[0046] (3) Preparation of mixed powder The composite graphite material (10%) and alloy powder (90%) are added to a drum mixer and mixed for 2 hours to obtain a uniformly mixed powder.

[0047] (4) Hot pressing The molding die is heated to 160°C, and then the mixed powder is added to the die for hot pressing. The molding pressure is 30 MPa, and the holding time is 2 seconds, so that the mixed powder is formed under heating and pressure to obtain a molded blank.

[0048] (5) Oxygen-free sintering The shaped preform is placed in a vacuum furnace for sintering at a vacuum level of 10. -3 Pa, the sintering temperature is raised to 600℃ and held for 1 hour, then slowly raised to 900℃ and held for 1 hour, and then cooled to 50℃ under gas protection or vacuum protection to obtain contact blank 1.

[0049] (6) Base welding The contact blank 1 can be welded to a base of any shape. The contact blank 1 is welded to a quadrilateral metal base 2. Figure 2 This is a top view of the quadrilateral metal base used in this embodiment, showing the composite electrical contact, denoted as sample 2. Figure 1 This is a side cross-sectional view of the quadrilateral electrical contact obtained in this embodiment.

[0050] The performance of sample 2 was tested, and the results are as follows: The relay contact resistance is within 1.4 mΩ. Vickers hardness (HV): 160 HV. Bending strength: 160 MPa (three-point bending test, specimen 3x4x36 mm, loading rate 1 mm / min).

[0051] The results of 7000 electrical fatigue tests on a magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: the corrosion amount of the moving and stationary contacts was 120mg, the contacts did not stick during the opening and closing process, and the contact temperature did not exceed 85 degrees.

[0052] The product obtained from Sample 2 has significantly improved hardness and bending resistance. It does not break during contact processing and riveting and is easy to process and rivet.

[0053] Example 3 (1) Preparation of composite graphite materials Weigh out 90% graphite powder and 10% binder (asphalt) by weight percentage, and soften the binder by heating to 100°C. Add the graphite powder and asphalt to a mixing device and stir for 1 hour. During the mixing process, slowly increase the temperature, controlling the asphalt mixture temperature at 180°C to ensure that the asphalt evenly coats the surface of the graphite powder under heating. Continue heating and stirring to remove moisture or solvents from the mixture, then discharge and allow it to cool naturally. After cooling, pulverize the resulting material to obtain a composite graphite material.

[0054] (2) Preparation of alloy powder Weigh out 93% electrolytic copper powder and 7% metallic auxiliary material by mass percentage, wherein the metallic auxiliary material is tungsten powder. Add the copper powder and tungsten powder to a drum mixer and mix for 0.5 hours to ensure uniform mixing and obtain alloy powder.

[0055] (3) Preparation of mixed powder The composite graphite material (30%) and alloy powder (70%) are added to a drum mixer and mixed for 0.5 hours to obtain a uniformly mixed powder.

[0056] (4) Hot pressing Heat the molding die to 200°C, then place the circular metal base 3 at the bottom of the mold cavity. Figure 3 This is a top view of the circular metal base used in this embodiment. The mixed powder is then added to the mold for hot pressing. The molding pressure is 50 MPa, and the heat and pressure holding time is 4 seconds, so that the mixed powder is formed under heating and pressure to obtain a molded blank.

[0057] (5) Oxygen-free sintering The shaped blank was placed in a sintering furnace for sintering in an argon atmosphere at a pressure of 1 MPa. The sintering temperature was raised to 850°C and held for 4 hours. Then, the temperature was slowly raised to 1050°C and held for 4 hours. Subsequently, it was cooled to 90°C under gas or vacuum protection to obtain a composite electrical contact. This electrical contact can replace the silver contacts of AC contactors and miniature circuit breakers. This is designated as sample 3.

[0058] The performance of sample 3 was tested, and the results are as follows: The relay contact resistance is within 1.5mΩ. Vickers hardness (HV): 100HV. Bending strength: 180MPa (three-point bending test, specimen 3x4x36mm, loading rate 1mm / min).

[0059] The results of 7000 electrical fatigue tests on a magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: the corrosion amount of the moving and stationary contacts was 130mg, the contacts did not stick during the opening and closing process, and the contact temperature did not exceed 85℃.

[0060] The product obtained from sample 3 has significantly improved hardness and bending resistance. It does not break during contact processing and riveting and is easy to process and rivet.

[0061] Comparative Example 1 The difference between this comparative example and Example 1 is that composite graphite powder is not used; only graphite powder is used. The comparative electrical contact obtained is designated as Sample 4.

[0062] The performance of sample 4 was tested, and the results are as follows: The magnetic latching relay has a contact resistance of less than 1.3 mΩ. Vickers hardness (HV): 70 HV. Bending strength: 120 MPa (three-point bending test, specimen 3x4x36 mm, loading rate 1 mm / min).

[0063] The results of 7000 electrical fatigue tests on a magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: a large number of electric sparks were ejected at the very first engagement and release of the moving and stationary contacts. During the 3-5 engagement and disengagement cycles, the contacts stuck together and the contact temperature exceeded 110℃.

[0064] The product prepared from sample 4 showed a significant decrease in hardness and bending resistance, and completely shattered during contact processing and riveting, resulting in powder fractures or disintegration of the contacts.

[0065] Comparative Example 2 The difference between this comparative example and Example 1 is that, in S5, when sintering the formed blank, the heating is not carried out in stages, but the high-temperature oxygen-free sintering is carried out directly at 950°C. The resulting composite electrical contact is recorded as Sample 5.

[0066] The performance of sample 5 was tested, and the results are as follows: The magnetic latching relay has a contact resistance of less than 2.5 mΩ. Its Vickers hardness (HV) is 55 HV. Its bending strength is 45 MPa (three-point bending test, specimen 3x4x36 mm, loading rate 1 mm / min).

[0067] The results of the 7000-cycle electrical fatigue test on the magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: the first contact of the moving and stationary contacts made a loud impact and breakage sound when they first engaged and disengaged. During the engagement and disengagement process, a large number of red sparks flew everywhere when the contacts collided with each other. The contact temperature rose rapidly to 80℃. The relay stopped working after 20-31 engagements due to excessive resistance and electrical sparks causing excessive wear.

[0068] Comparative Example 3 The difference between this comparative example and Example 1 is that when the molded blank is sintered in S5, the sintering temperature is 550°C, which is lower than the sintering temperature range of the present invention. The resulting composite electrical contact is denoted as Sample 6.

[0069] The performance of sample 6 was tested, and the results are as follows: The magnetic latching relay has a contact resistance of less than 2.1 mΩ. Its Vickers hardness (HV) is 70 HV. Its bending strength is 60 MPa (three-point bending test, specimen 3x4x36 mm, loading rate 1 mm / min).

[0070] The results of 7000 electrical fatigue tests on a magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: a large number of electric sparks were ejected at the very first engagement and release of the moving and stationary contacts. During the first 10-20 engagements, the contacts stuck together and the contact temperature rapidly exceeded 100℃.

[0071] Comparative Example 4 The difference between this comparative example and Example 1 is that furan resin is used as the binder, that is, the binder specified in this technical solution is not used. The resulting composite electrical contact is designated as Sample 7.

[0072] The performance of sample 7 was tested, and the results are as follows: The magnetic latching relay has a contact resistance of less than 1.8 mΩ. Its Vickers hardness (HV) is 65 HV. Its bending strength is 60 MPa (three-point bending test, specimen 3x4x36 mm, loading rate 1 mm / min).

[0073] The results of 7000 electrical fatigue tests on a magnetic latching relay testing machine with a voltage of 220V and a current of 90A were as follows: small electrical sparks were emitted from the moving and stationary contacts after the 5th to 10th engagement and disengagement. During the 50th to 60th engagement and disengagement, the sparks increased, eventually causing the contacts to stick together and the contact temperature to exceed 120℃.

[0074] This invention verifies the key technological contributions of composite graphite material structure and segmented sintering process through systematic comparison of examples and comparative examples. Examples 1-3 use a binder (FB88 resin, silicone resin or asphalt) to coat graphite powder to form a core-shell structure, followed by two-stage sintering (low-temperature pre-firing at 600-850℃ + high-temperature densification at 900-1050℃). The resulting composite electrical contacts have a hardness of over 100HV and a flexural strength of over 150 MPa, and can complete 7000 cycles of electrical fatigue testing under 220V / 90A conditions without adhesion. In contrast, after removing the adhesive coating in Comparative Example 1, the contact strength dropped to 120 MPa due to poor wettability at the graphite-copper interface, and it completely shattered during riveting; Comparative Example 2, which used direct high-temperature sintering (950℃), suffered thermal stress cracking, resulting in a hardness of only 55 HV, and it failed after more than 20 cycles; Comparative Example 3, which used low-temperature sintering (550℃), failed due to insufficient sintering, and it bonded after 10-20 cycles; Comparative Example 4, which used furan resin, failed due to overheating after 50-60 cycles due to residual carbon structural defects.

[0075] Examples and comparative cases demonstrate that the selectivity of the binder (forming a residual carbon phase that matches thermal expansion) and the necessity of staged heating (controlling the release of pyrolysis gases and carrying out metallurgical bonding step by step) in this technical solution have an inseparable synergistic effect. Specifically, the binder coating layer transforms into a carbon binder phase after sintering, maintaining the self-lubricating properties of graphite while providing a mechanical framework; staged sintering achieves controllable pyrolysis of the binder in a low-temperature stage and completes the carbonization of the binder in a high-temperature stage, avoiding porosity or segregation caused by a single heating. This integrated solution of "material structure design - process parameter matching" achieves a balance between conductivity and mechanical properties in composite electrical contacts, solving the industry problems of short lifespan, instability, and high cost of traditional graphite-copper contacts.

[0076] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a composite electrical contact, characterized in that, Includes the following steps: S1. Graphite powder is mixed with a binder to obtain a composite graphite material; the binder is selected from at least one of phenolic resin, silicone resin, and asphalt; S2. Copper powder is mixed with metal additives to obtain alloy powder; the metal additives are selected from at least one of silver powder, tin, titanium, tantalum powder, chromium powder, tungsten powder, and molybdenum powder. S3. Mix the composite graphite material with the alloy powder to obtain a mixed powder; S4. The mixed powder is hot-pressed to obtain a molded blank; S5. The formed blank is sintered. During the sintering process, the temperature is first raised to 600-850℃ and held for 1-4 hours, then raised to 900-1050℃ and held for 1-4 hours, and then cooled to 30-90℃ to obtain the contact blank. By combining the contact blank with the base, a composite electrical contact is obtained; The mass ratio of graphite powder to binder mentioned in S1 is 70-90:10-30; The mass ratio of copper powder to metal additives mentioned in S2 is 80-93:7-20; The mass ratio of composite graphite material to alloy powder in S3 is 10-30:70-90.

2. The method according to claim 1, characterized in that, The hot pressing process described in S4 involves a temperature of 160-200℃, a pressure of 30-50MPa, and a holding time of 2-4 seconds.

3. The method according to claim 2, characterized in that, The hot pressing process described in S4 is performed at a temperature of 170°C and a pressure of 30 MPa.

4. The method according to claim 1, characterized in that, The connection between the contact blank and the base is specifically as follows: In S4, the mixed powder and the base are subjected to the aforementioned hot pressing treatment to form a single integral shape; or... The base is welded to the contact blank prepared in S5.

5. The method according to claim 1, characterized in that, The sintering and cooling processes described in S5 are carried out in a vacuum environment, an inert atmosphere, or a reducing atmosphere.

6. The method according to claim 5, characterized in that, The sintering is carried out in a vacuum environment with a vacuum degree of 10. -3 -10 -5 Pa.

7. The method according to claim 5, characterized in that, The sintering is carried out in an inert atmosphere or a reducing atmosphere, with a pressure of 0.1-1 MPa.

8. A composite electrical contact prepared by the method according to any one of claims 1-7.

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