Composite contact and preparation method thereof

Abstract

The invention relates to a composite contact and a preparation method thereof. The composite contact comprises a contact layer, a transition layer and a core layer, wherein the contact layer is connected with the core layer through the transition layer; the material of the contact layer comprises a first copper-chromium material, the material of the transition layer comprises a second copper-chromium material, the material of the core layer comprises a third copper-chromium material, the copper content in the first copper-chromium material is 55-65% by mass, the copper content in the second copper-chromium material is 45-53% by mass, and the copper content in the third copper-chromium material is 38-43% by mass. Compared with a traditional homogeneous material, the composite contact can maintain excellent durability while having high conductivity, and the problem of local failure of the contact under high current load can be effectively reduced.

Description

Technical Field

[0001] This application relates to the field of metal matrix composite technology, and in particular to composite contacts and their preparation methods. Background Technology

[0002] As electrical equipment evolves towards higher power, miniaturization, and longer lifespan, electrical contact materials, as key functional components, must possess excellent conductivity, wear resistance, arc erosion resistance, and corrosion resistance. Traditional silver-based contact materials (such as Ag-CdO) offer good conductivity but suffer from cadmium toxicity and are prone to failure under high loads due to arc erosion. While pure copper contacts are low-cost and offer excellent conductivity, their wear resistance and oxidation resistance are poor, and prolonged use can lead to increased contact resistance due to a thickened surface oxide film, affecting equipment reliability. Therefore, developing novel environmentally friendly, high-performance composite contact materials has become a current research hotspot.

[0003] Copper-chromium alloys are one of the key materials in the field of high-voltage electrical contacts. Copper has excellent electrical conductivity, while chromium has excellent resistance to arc erosion and high voltage resistance. However, due to the individual properties of copper and chromium, it is difficult to obtain contacts that simultaneously possess both excellent electrical conductivity and arc resistance. Summary of the Invention

[0004] Therefore, it is necessary to provide a composite contact with excellent conductivity, resistance to arc erosion and mechanical strength, and a method for its preparation.

[0005] In a first aspect, this application provides a composite contact.

[0006] A composite contact includes a contact layer, a transition layer, and a core layer. The contact layer is connected to the core layer through the transition layer. The contact layer is made of a first copper-chromium material, the transition layer is made of a second copper-chromium material, and the core layer is made of a third copper-chromium material. By mass percentage, the first copper-chromium material contains 55% to 65% copper, the second copper-chromium material contains 45% to 53% copper, and the third copper-chromium material contains 38% to 43% copper.

[0007] In some embodiments, the thickness of the contact layer is 1 mm to 2 mm; and / or

[0008] The thickness of the transition layer is 1mm to 1.5mm; and / or

[0009] The thickness of the core layer is 1.5mm to 2mm.

[0010] In some embodiments, the first copper-chromium material, the second copper-chromium material, and the third copper-chromium material each independently include a copper source and a chromium source, wherein the D50 of the copper source is 10 μm to 30 μm, and the D50 of the chromium source is 5 μm to 15 μm.

[0011] In a second aspect, this application provides a method for preparing a composite contact.

[0012] A method for preparing a composite contact includes the following steps:

[0013] A first copper-chromium material, a second copper-chromium material, and a third copper-chromium material are obtained. By mass percentage, the copper content in the first copper-chromium material is 55%~65%, the copper content in the second copper-chromium material is 45%~53%, and the copper content in the third copper-chromium material is 38%~43%.

[0014] A brick-and-mortar structure is prepared by sequentially filling the mold with the third copper-chromium material, the second copper-chromium material, and the first copper-chromium material of a set thickness;

[0015] The composite contact is prepared by spark plasma sintering of the brick-mud structure.

[0016] In some embodiments, the discharge plasma sintering process includes:

[0017] Heat to 850℃~900℃ at a heating rate of 90℃ / min~110℃ / min, and hold for 5min~10min.

[0018] In some embodiments, during the discharge plasma sintering, the intermediate sintering temperature is set to 550°C to 650°C. When the sintering temperature is lower than the intermediate sintering temperature, the pressure is set to 8MPa to 15MPa. When the sintering temperature is higher than the intermediate sintering temperature, the pressure is set to 30MPa to 50MPa.

[0019] In some embodiments, the preparation methods of the first copper-chromium material, the second copper-chromium material, and the third copper-chromium material each independently include:

[0020] The copper source and chromium source are mixed in proportion to form a mixture;

[0021] The mixture is subjected to cryogenic ball milling and then dried.

[0022] In some embodiments, the ball-to-material ratio of the cryogenic ball milling process is (8-12):1; and / or

[0023] The rotation speed of the cryogenic ball milling process is 200 rpm to 300 rpm; and / or

[0024] The cryogenic ball milling process takes 2 to 4 hours.

[0025] In some embodiments, the discharge plasma sintering of the brick-mud structure further includes the following step: monitoring the shrinkage rate of the brick-mud structure until the shrinkage rate of the brick-mud structure is ≥95%.

[0026] In some embodiments, the third copper-chromium material in the mold is pre-compacted before the second copper-chromium material is filled; and / or

[0027] Before filling the first copper-chromium material, the third copper-chromium material and the second copper-chromium material in the mold are pre-compacted.

[0028] The aforementioned composite contact comprises a contact layer, a transition layer, and a core layer with decreasing copper content. The high copper content ensures good conductivity in the surface contact layer, while the high chromium content enhances the arc erosion resistance of the core layer. Furthermore, the transition layer alleviates thermal stress in both the contact layer and the core layer, resulting in a composite contact with excellent integrity. Compared to traditional homogeneous materials, this composite contact maintains superior durability while possessing high conductivity, effectively reducing localized contact failure under high current loads. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0030] Figure 1 This is a flowchart illustrating the fabrication process of the composite contact in one embodiment of this application.

[0031] Figure 2 This is a microstructure diagram of the cross-section of the composite contact of Embodiment 1 of this application. Detailed Implementation

[0032] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0033] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In this application, "at least one" means one or more, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0036] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0037] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0038] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0039] In a first aspect, this application provides a composite contact that combines excellent conductivity, resistance to arc erosion, and mechanical strength.

[0040] For example, the composite contact includes a contact layer, a transition layer, and a core layer, with the contact layer connected to the core layer via the transition layer. The contact layer is made of a first copper-chromium material, the transition layer is made of a second copper-chromium material, and the core layer is made of a third copper-chromium material.

[0041] The copper content in the first copper-chromium material is 55% to 65% by mass percentage.

[0042] The copper content in the second copper-chromium material is 45% to 53% by mass percentage.

[0043] The copper content in the third copper-chromium material is 38% to 43% by mass percentage.

[0044] The aforementioned composite contact comprises a contact layer, a transition layer, and a core layer with decreasing copper content. The contact layer serves as the contact point of the composite contact, and its high copper content ensures excellent conductivity. The core layer serves as the mechanical interface of the composite contact, and its high chromium content enhances its resistance to arc erosion. Furthermore, the transition layer alleviates thermal stress in both the contact layer and the core layer, resulting in a composite contact with good integrity. Compared to traditional homogeneous materials, this composite contact maintains excellent durability while possessing high conductivity, effectively reducing localized failure issues under high current loads.

[0045] In this embodiment, the copper content in the first copper-chromium material can be, but is not limited to, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, or other values ​​within the range of 55% to 65%. Maintaining the above copper content helps to give the contact layer excellent conductivity.

[0046] In this embodiment, the copper content in the second copper-chromium material can be, but is not limited to, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, or other values ​​within the range of 45% to 53%. Maintaining the above copper content helps alleviate thermal stress in the contact layer and core layer, and avoids structural incompatibility due to excessive differences in content.

[0047] In this embodiment, the copper content in the third copper-chromium material can be, but is not limited to, 38%, 39%, 40%, 41%, 42%, 43%, or other values ​​within the range of 38% to 43%. Maintaining the above copper content can effectively improve the arc erosion resistance of the core layer.

[0048] Taking the first copper-chromium material as an example, in this embodiment, the chromium content in the first copper-chromium material can be considered equal to 100% copper content. However, it should be understood that, limited by the purity of the copper and chromium sources, the chromium content in the first copper-chromium material is theoretically not equal to 100% minus the copper content, and trace impurities still exist.

[0049] In some embodiments, the thickness of the contact layer is 1mm to 2mm. Optionally, the thickness of the contact layer can be, but is not limited to, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or other values ​​within the range of 1mm to 2mm.

[0050] In some embodiments, the thickness of the transition layer is 1 mm to 1.5 mm. Optionally, the thickness of the transition layer can be, but is not limited to, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, or other values ​​within the range of 1 mm to 1.5 mm.

[0051] In some embodiments, the thickness of the core layer is 1.5mm to 2mm. Optionally, the thickness of the core layer can be, but is not limited to, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or other values ​​within the range of 1.5mm to 2mm.

[0052] In some embodiments, the first copper-chromium material, the second copper-chromium material, and the third copper-chromium material each independently include a copper source and a chromium source.

[0053] In some embodiments, the copper source includes copper powder. Optionally, the copper source is electrolytic copper powder with a purity greater than 99.9%.

[0054] In some embodiments, the chromium source includes chromium powder. Optionally, the chromium source is atomized chromium powder with a purity greater than 99.5%.

[0055] In some embodiments, the D50 of the copper powder is 10 μm to 30 μm. Optionally, the D50 of the copper powder can be, but is not limited to, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, or other values ​​within the range of 10 μm to 30 μm. Keeping the copper powder within the above-mentioned particle size range is more conducive to forming a conductive network structure with good continuity.

[0056] In some embodiments, the D50 of the chromium powder is 5 μm to 15 μm. Optionally, the D50 of the chromium powder can be, but is not limited to, 5 μm, 10 μm, 15 μm, or other values ​​within the range of 5 μm to 15 μm. Maintaining the chromium powder within the above-mentioned particle size range helps to improve the uniform dispersion of the chromium powder in the composite material.

[0057] In some embodiments, the D50 ratio of chromium powder to copper powder is 1:(1.5~2). Optionally, the D50 ratio of chromium powder to copper powder can be, but is not limited to, values ​​within the range of 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, or 1:(1.5~2). Maintaining the above-mentioned particle size relationship between chromium powder and copper powder further facilitates the formation of a well-integrated contact layer, transition layer, and core layer during sintering.

[0058] Traditional copper-chromium contact materials are mostly prepared using mechanical mixing or melt infiltration processes. However, when preparing structures with gradient chromium content, uneven chromium phase distribution and weak interfacial bonding are common problems. This leads to localized chromium phase enrichment or flaking during arc erosion, affecting device reliability. Furthermore, while powder metallurgy combined with hot pressing sintering can achieve gradient composites, high-temperature, long-term sintering easily causes chromium particle coarsening and copper phase oxidation, and insufficient interlayer diffusion, resulting in poor integrity and performance of the final composite contact.

[0059] Based on this, the second aspect of this application provides a method for preparing a composite contact with high gradient interface bonding, good density and integrity, so as to further improve the conductivity, arc erosion resistance and mechanical strength of the composite contact.

[0060] For example, please see Figure 1 , Figure 1 This is a flowchart illustrating the fabrication process of the composite contact according to one embodiment of this application. The fabrication method of the composite contact includes the following steps:

[0061] S1. Obtain a first copper-chromium material, a second copper-chromium material, and a third copper-chromium material, wherein the copper content in the first copper-chromium material is 55%~65%, the copper content in the second copper-chromium material is 45%~53%, and the copper content in the third copper-chromium material is 38%~43%;

[0062] S2. Fill the mold with a set thickness of third copper-chromium material, second copper-chromium material and first copper-chromium material in sequence to prepare a brick-mortar structure;

[0063] S3. Perform spark plasma sintering on the brick-mud structure to prepare composite contacts.

[0064] The above method is based on spark plasma sintering to sinter brick and mud structures with a gradient distribution of copper content. By activating the particle surface with pulsed current, densification and nanoscale interface bonding can be achieved in a short time at low temperature. Compared with traditional sintering methods, it helps to form composite contacts with high interface bonding strength and good integrity.

[0065] In some embodiments, the spark plasma sintering process includes:

[0066] Heat to 850℃~900℃ at a heating rate of 90℃ / min~110℃ / min, and hold for 5min~10min.

[0067] In this embodiment, the heating rate can be, but is not limited to, 90℃ / min, 95℃ / min, 100℃ / min, 105℃ / min, 110℃ / min or other values ​​within the range of 90℃ / min to 110℃ / min.

[0068] In this embodiment, the sintering temperature can be, but is not limited to, 850°C, 875°C, 900°C, 925°C, 950°C, or other values ​​within the range of 850°C to 900°C.

[0069] In this embodiment, the heat preservation time can be, but is not limited to, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or other values ​​within the range of 5 min to 10 min.

[0070] Maintaining the process parameters of spark plasma sintering within the above range, especially maintaining the above heating rate, can effectively suppress grain growth and promote Cu / Cr interface diffusion, forming an interface with high density and high bonding strength.

[0071] In some embodiments, the filling thickness of the first copper-chromium material can be 1 mm to 2.5 mm.

[0072] In some embodiments, the filling thickness of the second copper-chromium material can be 1 mm to 2 mm.

[0073] In some embodiments, the filling thickness of the third copper-chromium material can be 1.5 mm to 2.5 mm.

[0074] In some embodiments, the vacuum level during spark plasma sintering is 1 Pa to 10 Pa. Optionally, the vacuum level during spark plasma sintering can be, but is not limited to, 1 Pa, 2 Pa, 3 Pa, 4 Pa, 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa, 10 Pa, or other values ​​within the range of 1 Pa to 10 Pa.

[0075] In some embodiments, during spark plasma sintering, the intermediate sintering temperature is set to 550℃~650℃. When the sintering temperature is lower than the intermediate sintering temperature, the pressure is set to 8MPa~15MPa; when the sintering temperature is higher than the intermediate sintering temperature, the pressure is set to 30MPa~50MPa. Studies have found that segmented pressurization at different temperature stages can effectively suppress grain growth, increase the shrinkage rate of the brick-clay structure, and thus obtain a high-density composite contact.

[0076] In some embodiments, the contact layer, transition layer, and core layer are cylinders of equal diameter. It can be understood that the contact layer, transition layer, and core layer are longitudinally connected to form a cylindrical composite contact.

[0077] In some embodiments, the process also includes cutting the composite contact. The longitudinal lines of the composite contact can be cut to specific sizes and shapes according to usage requirements.

[0078] In some embodiments, the preparation methods of the first copper-chromium material, the second copper-chromium material, and the third copper-chromium material each independently include:

[0079] The copper source and chromium source are mixed in proportion to form a mixture;

[0080] The mixture is subjected to cryogenic ball milling and then dried.

[0081] Research has shown that cryogenic ball milling can form a nanocrystalline structure on the surface of copper powder and allow chromium powder to be uniformly embedded in the copper matrix, forming a uniform copper-chromium material with a high specific surface area.

[0082] In some of these implementations, the drying method includes vacuum drying.

[0083] In some embodiments, the ball-to-material ratio for cryogenic ball milling is (8-12):1. Optionally, the ball-to-material ratio for cryogenic ball milling can be, but is not limited to, 8:1, 9:1, 10:1, 11:1, 12:1, or other values ​​within the range of (8-12):1.

[0084] In some embodiments, the rotational speed of the cryogenic ball milling process is 200 rpm to 300 rpm. Optionally, the rotational speed of the cryogenic ball milling process can be, but is not limited to, 200 rpm, 300 rpm, 400 rpm, or other values ​​within the range of 200 rpm to 300 rpm.

[0085] In some embodiments, the cryo-ball milling treatment time is 2 to 4 hours. Optionally, the cryo-ball milling treatment time can be, but is not limited to, 2 hours, 3 hours, 4 hours, or other values ​​within the range of 2 to 4 hours.

[0086] In some embodiments, the discharge plasma sintering of the brick-mud structure further includes the following step: monitoring the shrinkage rate of the brick-mud structure until the shrinkage rate of the brick-mud structure is ≥95%.

[0087] In some embodiments, the third copper-chromium material in the mold is pre-compacted before the second copper-chromium material is filled.

[0088] Before filling with the first copper-chromium material, the third and second copper-chromium materials in the mold are pre-compacted. It can be understood that the mold contains both the third and second copper-chromium materials before the first copper-chromium material is filled.

[0089] In some embodiments, the pre-compaction pressure can be 5 MPa to 10 MPa. Pre-compaction can eliminate loose pores, which helps to reduce the porosity of subsequent sintering processes.

[0090] The present application will be further described in detail below with reference to specific embodiments.

[0091] In the following specific embodiments, unless otherwise specified, the raw materials used are all commercially available products; the instruments used are all commercially available products; and the processes used are all conventionally selected by those skilled in the art unless otherwise specified.

[0092] Example 1

[0093] This embodiment provides a composite contact.

[0094] The composite contact in this embodiment consists of a contact layer, a transition layer, and a core layer. The contact layer is connected to the core layer through the transition layer. The thickness of the contact layer is 1.8 mm, the thickness of the transition layer is 1.6 mm, and the thickness of the core layer is 1.8 mm. The copper content of the contact layer is 60%, the copper content of the transition layer is 50%, and the copper content of the core layer is 40%.

[0095] The method for preparing the composite contact in this embodiment is as follows:

[0096] Electrolytic copper powder with a D50 of 20 μm and atomized chromium powder with a D50 of 10 μm were mixed in ratios of 6:4, 5:5, and 4:6 to form mixtures.

[0097] A planetary high-energy cryogenic ball mill was used to cryogenically ball mill the mixture separately. Anhydrous ethanol was used as the medium, the ball-to-material ratio was 10:1, the rotation speed was 250 rpm, and the cryogenic ball milling was carried out for 3 hours. After vacuum drying at 60℃ for 1 hour, a first copper-chromium material with a copper content of 60%, a second copper-chromium material with a copper content of 50%, and a third copper-chromium material with a copper content of 40% were obtained, respectively.

[0098] A 2mm third copper-chromium material, a 1.8mm second copper-chromium material, and a 2mm first copper-chromium material are sequentially filled into a graphite mold. The second copper-chromium material and the first copper-chromium material are then filled in. The filler in the graphite mold is pre-compacted at a pressure of 8MPa to form a brick-mud structure.

[0099] Composite contacts were obtained by spark plasma sintering of brick and mortar structures. The vacuum level was set at 5 Pa, the heating rate at 100 °C / min, the sintering temperature at 880 °C, and the holding time at 8 min. An intermediate sintering temperature was set at 600 °C. When the temperature was below the intermediate sintering temperature, the pressure was maintained at 10 MPa; when the temperature was above or equal to the intermediate sintering temperature, the pressure was maintained at 40 MPa.

[0100] Example 2

[0101] This embodiment provides a composite contact.

[0102] The composite contact in this embodiment differs from that in Embodiment 1 in that:

[0103] During spark plasma sintering, the heating rate is 100℃ / min, the sintering temperature is 900℃, the holding time is 10min, and the intermediate sintering temperature is set at 600℃. When the temperature is lower than the intermediate sintering temperature, the pressure is maintained at 10MPa, and when the temperature is greater than or equal to the intermediate sintering temperature, the pressure is maintained at 50MPa.

[0104] Example 3

[0105] This embodiment provides a composite contact.

[0106] The composite contact in this embodiment differs from that in Embodiment 1 in that:

[0107] During spark plasma sintering, the heating rate is 60℃ / min.

[0108] Example 4

[0109] This embodiment provides a composite contact.

[0110] The composite contact in this embodiment differs from that in Embodiment 1 in that:

[0111] During spark plasma sintering, the holding time is 20 minutes.

[0112] Example 5

[0113] This embodiment provides a composite contact.

[0114] The composite contact in this embodiment differs from that in Embodiment 1 in that:

[0115] During spark plasma sintering, a pressure of 40 MPa is maintained throughout the process.

[0116] Test case

[0117] Performance tests were conducted on the composite contact of the examples. Density was determined using the Archimedes method, gradient hardness was tested using a microhardness tester, resistivity was determined using the four-probe method, and erosion rate was tested using an electric arc test (10kA, 100 cycles). The test results are shown in Table 1. XRD analysis of the composite contact of Example 1 showed no Cu oxidation peaks. TEM analysis of the composite contact of Example 1 revealed a 50nm thick Cu-Cr diffusion structure at the interface between the transition layer, contact layer, and core layer, indicating a tight interface. The microstructure of the cross-section of the composite contact of Example 1 was observed; optical microscope images are shown below. Figure 2 .

[0118] Table 1 Performance test results of the composite contact in the embodiment

[0119]

[0120] As shown in Table 1, the composite contact fabrication method of this application can obtain composite contacts with low resistivity and high relative density. The multilayer structure on the surface exhibits good compatibility, and the complementary properties of each layer enable the composite contact to possess high conductivity while maintaining excellent durability, effectively reducing the problem of localized contact failure under high current loads. Furthermore, Figure 2 This is a microstructure diagram of the cross-section of the composite contact in Embodiment 1 of this application. Figure 2 As can be seen, the cross-section has a uniformly gradient copper-chromium composite structure from top to bottom.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A composite contact, characterized in that, It includes a contact layer, a transition layer, and a core layer. The contact layer is connected to the core layer through the transition layer. The material of the contact layer includes a first copper-chromium material, the material of the transition layer includes a second copper-chromium material, and the material of the core layer includes a third copper-chromium material. By mass percentage, the copper content in the first copper-chromium material is 55%~65%, the copper content in the second copper-chromium material is 45%~53%, and the copper content in the third copper-chromium material is 38%~43%.

2. The composite contact according to claim 1, characterized in that, The thickness of the contact layer is 1mm~2mm; and / or The thickness of the transition layer is 1mm to 1.5mm; and / or The thickness of the core layer is 1.5mm to 2mm.

3. The composite contact according to claim 1 or 2, characterized in that, The first copper-chromium material, the second copper-chromium material, and the third copper-chromium material each independently include a copper source and a chromium source, wherein the D50 of the copper source is 10μm~30μm, and the D50 of the chromium source is 5μm~15μm.

4. A method for preparing a composite contact, characterized in that, Includes the following steps: A first copper-chromium material, a second copper-chromium material, and a third copper-chromium material are obtained. By mass percentage, the copper content in the first copper-chromium material is 55%~65%, the copper content in the second copper-chromium material is 45%~53%, and the copper content in the third copper-chromium material is 38%~43%. A brick-and-mortar structure is prepared by sequentially filling the mold with the third copper-chromium material, the second copper-chromium material, and the first copper-chromium material of a set thickness; The composite contact is prepared by spark plasma sintering of the brick-mud structure.

5. The method for preparing the composite contact according to claim 4, characterized in that, The spark plasma sintering process includes: Heat to 850℃~900℃ at a heating rate of 90℃ / min~110℃ / min, and hold for 5min~10min.

6. The method for preparing the composite contact according to claim 5, characterized in that, During the discharge plasma sintering process, the intermediate sintering temperature is set to 550℃~650℃. When the sintering temperature is lower than the intermediate sintering temperature, the pressure is set to 8MPa~15MPa. When the sintering temperature is higher than the intermediate sintering temperature, the pressure is set to 30MPa~50MPa.

7. The method for preparing the composite contact according to claim 4, characterized in that, The preparation methods of the first copper-chromium material, the second copper-chromium material, and the third copper-chromium material each independently include: The copper source and chromium source are mixed in proportion to form a mixture; The mixture is subjected to cryogenic ball milling and then dried.

8. The method for preparing the composite contact according to claim 7, characterized in that, The ball-to-material ratio of the cryogenic ball milling treatment is (8~12):1; and / or The rotation speed of the cryogenic ball milling process is 200 rpm to 300 rpm; and / or The cryogenic ball milling process takes 2 to 4 hours.

9. The method for preparing the composite contact according to any one of claims 4 to 8, characterized in that, The process of performing spark plasma sintering on the brick-mud structure further includes the following steps: monitoring the shrinkage rate of the brick-mud structure until the shrinkage rate of the brick-mud structure is ≥95%.

10. The method for preparing the composite contact according to any one of claims 4 to 8, characterized in that, Before filling the second copper-chromium material, the third copper-chromium material in the mold is pre-compacted; and / or Before filling the first copper-chromium material, the third copper-chromium material and the second copper-chromium material in the mold are pre-compacted.

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