Apparatus and method for preparing a copper-tungsten gradient electrical contact material

Abstract

The application discloses a copper-tungsten gradient electric contact material preparation device and method, and belongs to the technical field of copper-tungsten contact material preparation; the method adopts copper-coated tungsten composite powder as a printing raw material, and realizes the adjustment of the mass ratio of copper and tungsten through the thickness of the copper coating layer. The prepared copper-tungsten gradient electric contact material is uniform in copper and tungsten distribution, the copper phase is uniformly coated around the tungsten particles, the tungsten particles have good continuity, and the uneven distribution of the copper and tungsten in the region caused by the sedimentation of the tungsten particles will not occur. The method is characterized in that: an electron beam selective melting additive manufacturing equipment is utilized, copper-coated tungsten powder with different copper-tungsten ratios is loaded into a powder bin capable of independently containing different kinds of metal powder, a gradient copper-tungsten contact material is formed and manufactured in a 3D printing mode, and a copper-tungsten composite material continuously transiting from CuW90, CuW80, CuW70, CuW60 and CuW50 is realized.

Description

Technical Field

[0001] This invention belongs to the field of copper-tungsten contact material preparation technology, and relates to a copper-tungsten gradient electrical contact material preparation device and method. Background Technology

[0002] With the continuous advancement of modern power technology, switching devices are developing towards higher voltage levels and larger current capacities. This trend places more stringent performance requirements on copper-tungsten (CT) contacts, one of the core components of switching devices. As a key component ensuring the stable operation of switching devices, the contact part typically consists of two parts: a high-performance CT contact at the front end and a copper-chromium alloy tail connecting the conductor at the rear end. The CT contact, with its excellent mechanical strength, extremely high melting point, and outstanding resistance to arc erosion, exhibits remarkable stability under high loads, high temperatures, and frequent arcing. The copper-chromium alloy tail, with its high electrical conductivity, high thermal conductivity, and good elastic modulus, ensures smooth current transmission and effective heat dissipation.

[0003] However, with the upgrading of application requirements, traditional copper-tungsten electrical contact manufacturing processes, such as powder mixing, pressing, sintering, and melt infiltration processes, are no longer sufficient to meet the current high standards for contact material performance. Therefore, the bonding method between copper-tungsten contacts and the copper-chromium alloy tail is gradually shifting to more advanced welding or casting technologies in order to obtain a more robust and reliable connection.

[0004] However, it is worth noting that there are significant physicochemical differences between copper-tungsten contact materials and copper-chromium alloy materials, including differences in key performance indicators such as chemical composition, strength, coefficient of thermal expansion, thermal conductivity, electrical conductivity, and elastic modulus. These differences pose significant challenges to their bonding, specifically: insufficient bonding strength between the copper-tungsten contact and the copper-chromium tail, making it prone to detachment under harsh operating conditions; uneven distribution of thermal stress, leading to localized overheating or stress concentration, accelerating material aging; and limited overall thermal conductivity of the contact, affecting rapid heat transfer and thus shortening the contact's service life. In severe cases, this can even lead to switch failure, affecting the safe and stable operation of the power system. Summary of the Invention

[0005] The purpose of this invention is to provide a copper-tungsten gradient electrical contact material preparation device and method to solve the technical problems in the prior art, such as low connection strength between copper-tungsten contacts and copper-chromium tail, uneven distribution of thermal stress, poor thermal conductivity of contacts, and impact on the service life of contacts.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a copper-tungsten gradient electrical contact material preparation apparatus, comprising an electron beam selective melting and forming device located above a powder bed working plane, the electron beam selective melting and forming device having a plurality of storage units, each storage unit having a valve at its lower end; a powder feeder is placed below the electron beam selective melting and forming device, the powder feeder being located on the powder bed working plane; an electron gun is also arranged above the powder bed working plane; and a forming cylinder is arranged below the electron gun.

[0008] Furthermore, it also includes a powder collection box; the powder collection box has several independent storage units; a collection hole is provided on the working plane of the powder bed, and excess powder can enter the powder collection box below through the collection hole.

[0009] Furthermore, the plurality of storage units include a first storage unit, a second storage unit, a third storage unit, a fourth storage unit, and a fifth storage unit arranged independently in sequence; a first valve is provided at the lower end of the first storage unit; a second valve is provided at the lower end of the second storage unit; a third valve is provided at the lower end of the third storage unit; a fourth valve is provided at the lower end of the fourth storage unit; and a fifth valve is provided at the lower end of the fifth storage unit.

[0010] Secondly, the present invention provides a method for preparing a copper-tungsten gradient electrical contact material, based on the aforementioned apparatus for preparing a copper-tungsten gradient electrical contact material, comprising the following steps:

[0011] A 3D model of a copper-tungsten gradient material part was created using 3D modeling software.

[0012] The three-dimensional model of the copper-tungsten gradient material part was sliced ​​using slicing and layering software to obtain the two-dimensional scanning trajectory data of each layer.

[0013] Import the two-dimensional scanning trajectory data into the electron beam selective melting and forming equipment;

[0014] Pre-prepared copper-clad tungsten powders with different copper-tungsten ratios are loaded into various storage units within the electron beam selective melting and forming equipment.

[0015] Open the first valve to allow the powder in the first storage unit to fall into the powder feeder. The first ratio of copper-tungsten composite material is completed by the electron beam generated by the electron gun, with a molding height of h1.

[0016] Close the first valve and open the second valve; so that the powder in the second storage unit falls into the powder feeder, and the copper-tungsten composite material with the second ratio is completed on the basis of the first ratio of copper-tungsten composite material, with a molding height of h2;

[0017] Close the second valve and open the third valve; so that the powder in the third storage unit falls into the powder feeder, and the copper-tungsten composite material with the third ratio is completed on the basis of the second ratio of copper-tungsten composite material, with a molding height of h3;

[0018] Close the third valve and open the fourth valve; so that the powder in the fourth storage unit falls into the powder feeder, and the copper-tungsten composite material with the fourth ratio is completed on the basis of the third ratio of copper-tungsten composite material, with a molding height of h4;

[0019] Close the fourth valve and open the fifth valve; this allows the powder in the fifth storage unit to fall into the powder feeder, and the copper-tungsten composite material with the fifth ratio is completed based on the fourth ratio of copper-tungsten composite material, with a molding height of h5, and finally the copper-tungsten gradient composite material is obtained.

[0020] Furthermore, the preparation method of the copper-coated tungsten powder is as follows: calculate the coating thickness of the copper-coated tungsten powder; and plate copper onto the tungsten powder through chemical plating or electroplating processes.

[0021] Furthermore, the specific calculation formula for the step of calculating the coating thickness of the copper-coated tungsten powder is as follows:

[0022]

[0023] In the formula, m w ρ is the mass of tungsten powder particles; d is the average particle size of the tungsten powder before copper coating; w The density of tungsten is 19.3 g / cm³. 3 n is the number of powder particles;

[0024]

[0025] In the formula, m Cu ρ represents the mass of copper coating; D represents the average particle size of the copper-coated powder; ρ represents the mass of copper coating. Cu The density of copper is 8.9 g / cm³. 3 ;

[0026]

[0027] In the formula, 'a' represents the thickness of the copper layer in the copper-coated tungsten powder.

[0028] Furthermore, it also includes: collecting excess powder during the preparation process through a powder collection box and placing similar powders into the same independent storage unit.

[0029] Furthermore, the average particle size of the copper-coated tungsten powder is 40 μm to 150 μm, and the purity of the tungsten powder is not less than 99.9%.

[0030] Furthermore, the copper-coated tungsten powder includes CuW90, CuW80, CuW70, CuW60, and CuW50.

[0031] Furthermore, the copper-clad tungsten powder is replaced with copper-clad chromium powder to achieve the preparation of copper-chromium gradient electrical contact material.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention discloses a device and method for preparing copper-tungsten gradient electrical contact materials. The method uses copper-coated tungsten powder to prepare a gradient copper-tungsten composite material. The prepared material exhibits uniform copper and tungsten distribution, with the copper phase uniformly coating the tungsten particles. The tungsten particles have good continuity, preventing regional uneven distribution of copper and tungsten due to particle sedimentation. It achieves a transition from CuW90 to CuW50, enhancing the connection strength between the copper-tungsten contact and the copper-chromium tail section, significantly reducing heat accumulation on the contact surface, mitigating arc erosion, and giving the material better electrical conductivity, thermal conductivity, and mechanical properties. This, in turn, improves the high-voltage breaking capacity and service life of the electrical contact components. Furthermore, this invention uses an electron beam as a heat source, resulting in a large heat input and high energy utilization. The formed gradient copper-tungsten material has low porosity and a density of up to 99%, enabling reliable connections between copper-tungsten materials of different proportions. The product has good internal quality and requires no subsequent densification treatment.

[0034] Furthermore, by precisely calculating the coating thickness of the copper-coated tungsten powder, the copper-tungsten ratio can be freely adjusted by varying the thickness of the copper coating. This allows for the creation of complex tungsten-copper composite material parts with gradient material performance design and flexible control over the copper-tungsten ratio, making it suitable for the development of any new scheme or product.

[0035] Furthermore, the printing raw material of this invention is not limited to copper-clad tungsten powder; it can also be replaced with copper-clad chromium powder, thereby realizing the preparation of copper-chromium gradient electrical contact materials. This flexibility allows this invention to be applied to a wider range of electrical contact material preparation needs.

[0036] Furthermore, this invention employs a powder collection box to classify and collect excess powders of the same type. The powder collection box consists of different independent storage units. By moving the powder collection box horizontally, excess powder can fall into the designated independent storage units through the powder collection holes, thereby reducing the consumption of powder materials caused by the inability to separate different powders after mixing. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention;

[0039] Figure 2 This is a schematic diagram illustrating the preparation of the gradient copper-tungsten material of the present invention.

[0040] Wherein: 1-Powder feeder; 2-Powder; 3-First storage unit; 4-Second storage unit; 5-Third storage unit; 6-Fourth storage unit; 7-Fifth storage unit; 8-First valve; 9-Second valve; 10-Third valve; 11-Fourth valve; 12-Fifth valve; 13-Electron gun; 14-Electron beam; 15-Copper-tungsten gradient composite material; 16-Forming cylinder; 17-Powder collection box; 18-Collection hole; 19-Independent storage unit. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0043] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0044] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0045] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0046] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0047] To address the problems existing in the manufacturing processes of copper-tungsten contacts and gradient copper-tungsten composite materials, this paper provides a gradient copper-tungsten composite material preparation technology that can achieve different copper-tungsten ratios, enabling a transition from CuW90 to CuW50. This enhances the connection strength between the copper-tungsten contact and the copper-chromium tail, significantly reduces heat accumulation on the contact surface, mitigates arc erosion of the contact, and thus improves the high-voltage breaking capacity and service life of the electrical contact components.

[0048] The present invention will now be described in further detail with reference to the accompanying drawings:

[0049] See Figure 1This invention discloses a copper-tungsten gradient electrical contact material preparation device, including an electron beam selective melting and forming device located above the powder bed working plane. The electron beam selective melting and forming device has several storage units, each with a valve at its lower end. A powder feeder 1 is placed below the electron beam selective melting and forming device, positioned on the powder bed working plane. An electron gun 13 is also arranged above the powder bed working plane. A forming cylinder 16 is arranged below the electron gun 13. This embodiment utilizes the electron beam selective melting and forming device to load copper-clad tungsten powder with different copper-tungsten ratios into powder hoppers capable of independently holding different types of metal powders. The valves allow the copper-clad tungsten powder to fall onto the powder bed working plane. The powder feeder 1 then moves the powder 2 from the powder bed working plane to below the electron gun 13, forming a gradient copper-tungsten contact material through 3D printing. This achieves a continuous transition of copper-tungsten composite materials from CuW90, CuW80, CuW70, CuW60, and CuW50. Figure 2 As shown.

[0050] In one feasible embodiment of the present invention, the device further includes a powder collection box 17; the powder collection box 17 has a plurality of independent storage units 19; a collection hole 18 is provided on the working plane of the powder bed, and by horizontally moving the powder collection box 17, excess powder can fall into the designated independent storage unit 19 through the powder collection hole 18. The plurality of storage units include a first storage unit 3, a second storage unit 4, a third storage unit 5, a fourth storage unit 6, and a fifth storage unit 7 arranged independently in sequence; a first valve 8 is provided at the lower end of the first storage unit 3; a second valve 9 is provided at the lower end of the second storage unit 4; a third valve 10 is provided at the lower end of the third storage unit 5; a fourth valve 11 is provided at the lower end of the fourth storage unit 6; and a fifth valve 12 is provided at the lower end of the fifth storage unit 7.

[0051] This invention discloses a method for preparing copper-tungsten gradient electrical contact material, based on the aforementioned apparatus for preparing copper-tungsten gradient electrical contact material, comprising the following steps:

[0052] Step 1: Use 3D modeling software to create a 3D model of the copper-tungsten gradient material part;

[0053] Step 2: The three-dimensional model of the copper-tungsten gradient material part established in Step 1 is sliced ​​using slicing and layering software to obtain the two-dimensional scanning trajectory data of each layer.

[0054] Step 3: Import the two-dimensional scanning trajectory data from Step 2 into the electron beam selective melting and forming equipment;

[0055] Step 4: The pre-prepared copper-coated tungsten powders with different copper-tungsten ratios are loaded into the respective storage units in the electron beam selective melting and forming equipment.

[0056] Step 5: Open the first valve 8 to allow the powder in the first storage unit 3 to fall into the powder feeder 1. The first ratio of copper-tungsten composite material is completed by the electron beam 14 generated by the electron gun 13, and the molding height is h1.

[0057] Step 6: Close the first valve 8 and open the second valve 9; so that the powder in the second storage unit 4 falls into the powder feeder 1, and the copper-tungsten composite material with the second ratio is completed on the basis of the first ratio copper-tungsten composite material obtained in step 5, with a molding height h2;

[0058] Step 7: Close the second valve 9 and open the third valve 10; so that the powder in the third storage unit 5 falls into the powder feeder 1, and the copper-tungsten composite material with the third ratio is completed on the basis of the second ratio copper-tungsten composite material obtained in step 6, with a molding height h3;

[0059] Step 8: Close the third valve 10 and open the fourth valve 11; so that the powder in the fourth storage unit 6 falls into the powder feeder 1, and the copper-tungsten composite material with the fourth ratio is completed on the basis of the third ratio copper-tungsten composite material obtained in step 7, with a molding height of h4.

[0060] Step 9: Close the fourth valve 11 and open the fifth valve 12; so that the powder in the fifth storage unit 7 falls into the powder feeder 1, and the fifth copper-tungsten composite material is completed based on the fourth ratio of copper-tungsten composite material obtained in step 8, with a molding height of h5.

[0061] Step 10: Remove the molded copper-tungsten gradient composite material 15 from the molding cylinder 16 and clean off the powder.

[0062] In one feasible embodiment of the present invention, the copper-coated tungsten powder is CuW90, CuW80, CuW70, CuW60, and CuW50 with an average particle size of 40 μm to 150 μm. The copper-coated tungsten powder can be obtained by either chemical plating or electroplating, and the tungsten powder purity is not less than 99.9%. The calculation process for the coating thickness of the copper-coated tungsten powder is as follows:

[0063] Assuming the tungsten powder consists of uniformly sized spheres, and that the copper layer after copper plating is uniformly coated and still consists of uniform spheres, the thickness of the copper layer in the copper-coated tungsten powder plating can be calculated as follows:

[0064]

[0065] m w ρ is the mass of tungsten powder particles, d is the average particle size of the tungsten powder before copper coating, and ρ is the average particle size of the tungsten powder before copper coating. w The density of tungsten is 19.3 g / cm³. 3 .

[0066]

[0067] m Cu The mass of copper coating is given by ρ, where D is the average particle size of the copper-coated powder, and ρ is the average particle size of the copper-coated powder. Cu The density of copper is 8.9 g / cm³. 3 .

[0068] Calculated from equations (1) and (2):

[0069]

[0070] Coating thickness:

[0071]

[0072] The thickness 'a' of the copper layer in copper-coated tungsten powder can be determined based on the required copper-to-tungsten ratio.

[0073] This embodiment calculates the coating thickness of copper-coated tungsten powder precisely, and adjusts the copper-tungsten ratio freely by changing the thickness of the copper coating. This allows for the creation of complex tungsten-copper composite parts with gradient material performance design and flexible control of the copper-tungsten ratio, making it suitable for the research and development of any new scheme or product.

[0074] This invention proposes an innovative copper-tungsten composite contact material design. This material employs a unique gradient structure, with its composition gradually transitioning from CuW90 (90% tungsten and 10% copper) to CuW50 (50% tungsten and 50% copper). This design cleverly utilizes the change in material composition to optimize contact performance. CuW50 is used in the contact area between the contact and the tail, providing good conductivity and a certain mechanical strength, ensuring the stability and reliability of the contact-tail connection. In the contact area between the moving and stationary contacts, CuW90 is used. This high tungsten content significantly improves the contact's hardness and wear resistance, thereby enhancing its durability and service life in harsh working environments. This gradient structure design effectively overcomes the problem of mismatch at the interface of two different components in traditional contact materials. The gradually transitioning composition distribution reduces the thermal and stress barriers at the interface, allowing the contact to distribute and transfer heat more evenly under extreme conditions such as high temperature and high pressure, reducing thermal and mechanical stress caused by differences in material properties.

[0075] Furthermore, this copper-tungsten gradient material also achieves thermal stress mitigation, fully leveraging the intrinsic characteristics of both tungsten and copper. The high-copper side (or pure copper side) possesses excellent electrical and thermal conductivity, enabling rapid transfer of current and heat to ensure normal contact operation. The high-tungsten side (or pure tungsten side) features high strength, a high melting point, and a low coefficient of thermal expansion, maintaining contact stability and shape integrity under high temperature and pressure conditions. The intermediate copper-tungsten composite transition layer mitigates internal stress, ensuring the structural stability and performance consistency of the entire contact material. Simultaneously, this copper-tungsten functionally graded material (FGM) also exhibits high thermal conductivity. It rapidly transfers heat generated by the electric arc to the contact tail, significantly reducing heat accumulation on the contact surface and mitigating the erosive effect of the electric arc. This characteristic significantly improves the high-voltage breaking capacity and service life of electrical contact components, enabling the contacts to operate more stably under high voltage and high current impacts and reducing performance degradation and failure caused by electric arc erosion.

[0076] Preferably, the printing raw material of the present invention is not limited to copper-clad tungsten powder, but can also be replaced with copper-clad chromium powder, thereby realizing the preparation of copper-chromium gradient electrical contact materials. This flexibility allows the present invention to be applicable to the preparation needs of more types of electrical contact materials. Simultaneously, by adjusting the thickness of the copper cladding layer, the present invention can also freely adjust the copper-tungsten ratio, thereby completing the preparation of tungsten-copper composite parts with complex structures. This gradient material performance design and the flexible controllability of the copper-tungsten ratio make the present invention very suitable for the research and development and application of any new scheme or product. In summary, the copper-tungsten gradient composite contact material design proposed in the embodiments of the present invention has significant performance advantages and broad application prospects. It can not only overcome the problems existing in traditional contact materials and improve the stability and service life of contacts, but also meet the preparation needs of more types of electrical contact materials, providing strong support for the development of power systems and related industries.

[0077] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing copper-tungsten gradient electrical contact material, based on a copper-tungsten gradient electrical contact material preparation device, wherein the copper-tungsten gradient electrical contact material preparation device includes an electron beam selective melting and forming device located above the working plane of the powder bed, the electron beam selective melting and forming device having a plurality of storage units, each storage unit having a valve at its lower end; a powder feeder (1) is placed below the electron beam selective melting and forming device, the powder feeder (1) being located on the working plane of the powder bed; an electron gun (13) is also provided above the working plane of the powder bed; a forming cylinder is provided below the electron gun (13). (16); the plurality of storage units include a first storage unit (3), a second storage unit (4), a third storage unit (5), a fourth storage unit (6), and a fifth storage unit (7) arranged independently in sequence; a first valve (8) is provided at the lower end of the first storage unit (3); a second valve (9) is provided at the lower end of the second storage unit (4); a third valve (10) is provided at the lower end of the third storage unit (5); a fourth valve (11) is provided at the lower end of the fourth storage unit (6); and a fifth valve (12) is provided at the lower end of the fifth storage unit (7); characterized in that, The method includes the following steps: A 3D model of a copper-tungsten gradient material part was created using 3D modeling software. The three-dimensional model of the copper-tungsten gradient material part was sliced ​​using slicing and layering software to obtain the two-dimensional scanning trajectory data of each layer. Import the two-dimensional scanning trajectory data into the electron beam selective melting and forming equipment; Pre-prepared copper-clad tungsten powders with different copper-tungsten ratios are loaded into various storage units within the electron beam selective melting and forming equipment. Open the first valve (8) so that the powder in the first storage unit (3) falls into the powder feeder (1) and the first copper-tungsten composite material with the first ratio is completed by the electron beam (14) generated by the electron gun (13) and the molding height h1; Close the first valve (8) and open the second valve (9); so that the powder in the second storage unit (4) falls into the powder feeder (1), and the copper-tungsten composite material with the second ratio is completed on the basis of the first ratio of copper-tungsten composite material, with a molding height of h2; Close the second valve (9) and open the third valve (10); so that the powder in the third storage unit (5) falls into the powder feeder (1), and the copper-tungsten composite material with the third ratio is completed on the basis of the second ratio of copper-tungsten composite material, with a molding height of h3; Close the third valve (10) and open the fourth valve (11); so that the powder in the fourth storage unit (6) falls into the powder feeder (1), and the copper-tungsten composite material with the fourth ratio is completed on the basis of the third ratio of copper-tungsten composite material, with a molding height of h4; Close the fourth valve (11) and open the fifth valve (12); so that the powder in the fifth storage unit (7) falls into the powder feeder (1), and the copper-tungsten composite material with the fifth ratio is completed on the basis of the fourth ratio of copper-tungsten composite material, with a molding height of h5, and finally the copper-tungsten gradient composite material (15) is obtained. The preparation method of the copper-coated tungsten powder is as follows: calculate the coating thickness of the copper-coated tungsten powder; plate copper on the outside of the tungsten powder by chemical plating or electroplating process; The specific calculation formula for the step of calculating the coating thickness of copper-coated tungsten powder is as follows: In the formula, For tungsten powder particles; The average particle size of the tungsten powder before copper coating; The density of tungsten is 19.3 g / cm³. 3 ; This refers to the number of powder particles; In the formula, For the quality of the coated copper; The average particle size of the copper-coated powder. The density of copper is 8.9 g / cm³. 3 ; In the formula, The thickness of the copper layer in the copper-coated tungsten powder is given.

2. The method for preparing a copper-tungsten gradient electrical contact material according to claim 1, characterized in that, The device also includes a powder collection box (17); the powder collection box (17) has several independent storage units (19); a collection hole (18) is provided on the working plane of the powder bed, and excess powder can enter the powder collection box (17) below through the collection hole (18).

3. The method for preparing a copper-tungsten gradient electrical contact material according to claim 1, characterized in that, Also includes: Excess powder during the preparation process is collected through a powder collection box (17), and powders of the same type are placed in the same independent storage unit (19).

4. The method for preparing a copper-tungsten gradient electrical contact material according to claim 1, characterized in that, The average particle size of the copper-coated tungsten powder is 40μm to 150μm, and the purity of the tungsten powder is not less than 99.9%.

5. The method for preparing a copper-tungsten gradient electrical contact material according to claim 1, characterized in that, The copper-coated tungsten powder includes CuW90, CuW80, CuW70, CuW60, and CuW50.

6. The method for preparing a copper-tungsten gradient electrical contact material according to claim 1, characterized in that, The copper-clad tungsten powder was replaced with copper-clad chromium powder to prepare a copper-chromium gradient electrical contact material.

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