Device and method for preparing copper-tungsten gradient electrical contact material

Abstract

The invention discloses a copper-tungsten gradient electrical contact material preparation device and method, and belongs to the technical field of copper-tungsten contact material preparation. According to the method, copper-coated tungsten composite powder is adopted as a printing raw material, and the mass ratio of copper to tungsten is adjusted through the thickness of a copper coating layer. According to the prepared copper-tungsten gradient electrical contact material, copper and tungsten are evenly distributed, the peripheries of tungsten particles are evenly coated with a copper phase, the tungsten particles are good in continuity, and the situation that due to sedimentation of the tungsten particles, the organization distribution of regional copper and tungsten is not uniform is avoided. According to the method, 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 types of metal powder, the gradient copper-tungsten contact material is formed and manufactured in a 3D printing mode, and the copper-tungsten composite material with continuous transition from CuW90 to CuW80 to CuW70 to CuW60 to CuW50 is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of copper-tungsten contact material preparation, and relates to a device and method for preparing a copper-tungsten gradient electrical contact material. Background Art

[0002] With the continuous advancement of modern power technology, switchgear is developing towards higher voltage levels and larger current capacity. This trend has put forward more stringent performance requirements for copper-tungsten electrical contacts, which constitute one of the core components of switches. As a key component to ensure the stable operation of switchgear, contact parts are usually composed of two parts: the front end is a high-performance copper-tungsten contact, and the rear end is a copper-chromium alloy at the tail end that connects the conductor. With its excellent mechanical strength, extremely high melting point and excellent resistance to arc ablation, copper-tungsten contacts show extraordinary stability when subjected to high loads, high temperatures and frequent arcing. The tail copper-chromium alloy, with its high electrical conductivity, high thermal conductivity and good elastic modulus characteristics, ensures the smooth transmission of current and the effective dissipation of heat.

[0003] However, with the upgrading of application requirements, the traditional copper-tungsten electrical contact manufacturing process, such as mixed powder pressing sintering and infiltration process, can no longer meet the current high standards for contact material performance. Therefore, the combination of copper-tungsten contacts and tail copper-chromium alloys has gradually turned to more advanced welding or casting technology in order to obtain a more solid and reliable connection.

[0004] However, it is worth noting that there are significant physical and chemical differences between copper-tungsten contact materials and copper-chromium alloy materials, including differences in key performance indicators such as chemical composition, strength, thermal expansion coefficient, thermal conductivity, electrical conductivity, and elastic modulus. These differences bring huge challenges to the combination of the two, specifically: the bonding strength between the copper-tungsten contact and the copper-chromium tail is insufficient, and it is easy to fall off under harsh working conditions; the thermal stress distribution is uneven, resulting in local overheating or stress concentration, accelerating material aging; the overall thermal conductivity of the contact is limited, affecting the rapid transfer of heat, thereby shortening the service life of the contact, and in severe cases even causing the switch electrical equipment to fail, affecting the safe and stable operation of the power system. Summary of the invention

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

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

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

[0008] Furthermore, it also includes a powder collection box; the powder collection box has a plurality of independent storage units; a collection hole is opened 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 which are independently arranged in sequence; a first valve is arranged at the lower end of the first storage unit; a second valve is arranged at the lower end of the second storage unit; a third valve is arranged at the lower end of the third storage unit; a fourth valve is arranged at the lower end of the fourth storage unit; and a fifth valve is arranged at the lower end of the fifth storage unit.

[0010] In a second aspect, the present invention provides a method for preparing a copper-tungsten gradient electrical contact material, based on the above-mentioned copper-tungsten gradient electrical contact material preparation device, comprising the following steps:

[0011] Use 3D modeling software to build a 3D model of copper-tungsten gradient material parts;

[0012] The 3D model of the copper-tungsten gradient material part is sliced ​​using slicing and layering software to obtain the 2D scanning trajectory data of each layer;

[0013] Importing two-dimensional scanning trajectory data into electron beam selective melting molding equipment;

[0014] The pre-prepared copper-coated tungsten powders with different copper-tungsten ratios are respectively loaded into the respective storage units in the electron beam selective melting molding equipment;

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

[0016] Close the first valve and open the second valve; allow the powder in the second storage unit to fall into the powder feeder, and complete the copper-tungsten composite material with the second ratio on the basis of the copper-tungsten composite material with the first ratio, with a molding height of h2;

[0017] Close the second valve and open the third valve; allow the powder in the third storage unit to fall into the powder feeder, and complete the copper-tungsten composite material with the third ratio on the basis of the copper-tungsten composite material with the second ratio, with a molding height of h3;

[0018] Close the third valve and open the fourth valve; allow the powder in the fourth storage unit to fall into the powder feeder, and complete the copper-tungsten composite material with the fourth ratio on the basis of the copper-tungsten composite material with the third ratio, with a molding height of h4;

[0019] The fourth valve is closed and the fifth valve is opened; the powder in the fifth storage unit is allowed to fall into the powder feeder, and the copper-tungsten composite material with the fifth ratio is completed on the basis of the copper-tungsten composite material with the fourth ratio, with a forming height of h5, and finally a copper-tungsten gradient composite material is obtained.

[0020] Furthermore, the preparation method of the copper-coated tungsten powder is: calculating the coating thickness of the copper-coated tungsten powder; and plating copper on the outside of the tungsten powder by chemical plating or electroplating.

[0021] Furthermore, the step of calculating the coating thickness of the copper-coated tungsten powder is specifically calculated by the formula:

[0022]

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

[0024]

[0025] In the formula, m Cu is the mass of coated copper; D is the average particle size of the copper powder after coating; ρ Cu is the density of copper, 8.9g / cm 3 ;

[0026]

[0027] Where a is the thickness of the copper layer of copper-clad tungsten powder.

[0028] Furthermore, the method also includes: collecting excess powder in the preparation process through a powder collection box, and putting the same type of powder into the same independent storage unit.

[0029] Furthermore, the average particle size of the copper-clad 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-clad tungsten powder includes CuW90, CuW80, CuW70, CuW60 and CuW50.

[0031] Furthermore, the copper-coated tungsten powder is replaced with copper-coated 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] The invention discloses a copper-tungsten gradient electrical contact material preparation device and method, using copper-coated tungsten powder to prepare a gradient copper-tungsten composite material, the prepared material copper and tungsten are evenly distributed, the copper phase is evenly coated around the tungsten particles, the tungsten particles have good continuity, and there will be no regional copper and tungsten tissue uneven distribution caused by the sedimentation of tungsten particles; realize the transition from CuW90 to CuW50, enhance the connection strength between the copper-tungsten contact and the tail copper-chromium, greatly reduce the accumulation of heat on the contact surface, and alleviate the erosion of the contact by the arc, so that the material has better electrical conductivity, thermal conductivity and mechanical properties, thereby improving the high-voltage breaking capacity and service life of the electrical contact parts. In addition, the invention uses an electron beam as a heat source, the heat source input is large, the energy utilization rate is high, the formed gradient copper-tungsten material has a low porosity, and the density can reach 99%, which can realize reliable connection between copper-tungsten materials of different proportions, and the product has good internal quality and does not require subsequent densification treatment.

[0034] Furthermore, the present invention can accurately calculate the coating thickness of the copper-coated tungsten powder and freely adjust the copper-tungsten ratio by changing the thickness of the copper coating layer, so as to complete tungsten-copper composite parts with complex structures. The gradient material performance design and the copper-tungsten ratio are flexible and controllable, which is suitable for the research and development of any new solutions and new products.

[0035] Furthermore, the printing raw materials of the present invention are not limited to copper-coated tungsten powder, but can also be replaced with copper-coated chromium powder, thereby realizing the preparation of copper-chromium gradient electrical contact materials. This flexibility makes the present invention applicable to the preparation needs of more types of electrical contact materials.

[0036] Furthermore, the present invention uses a powder collection box to classify and collect excess powders of the same type, and the powder collection box is composed of different independent storage units. By moving the powder collection box horizontally, excess powder can pass through the powder collection hole and fall into the designated independent storage unit, which can reduce the consumption of powder materials caused by the inability to separate different powders after mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

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

[0039] Figure 2 Schematic diagram of the preparation of the gradient copper-tungsten material of the present invention.

[0040] Among them: 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 DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

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

[0045] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which 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 is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In view of the problems existing in the existing copper-tungsten contacts and the existing gradient copper-tungsten composite material manufacturing process, a gradient copper-tungsten composite material preparation technology is provided, which can achieve different copper-tungsten ratios, realize the transition from CuW90 to CuW50, enhance the connection strength between the copper-tungsten contact and the tail copper-chromium, greatly reduce the accumulation of heat on the contact surface, alleviate the erosion of the contact by the arc, and thus improve the high-voltage breaking capacity and service life of the electrical contact parts.

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0049] See also Figure 1, an embodiment of the present invention discloses a copper-tungsten gradient electrical contact material preparation device, including an electron beam selective melting molding device located above a powder bed working plane, the electron beam selective melting molding device having a plurality of storage units, each storage unit being provided with a valve at the lower end; a powder feeder 1 is placed below the electron beam selective melting molding device, the powder feeder 1 being located on the powder bed working plane; an electron gun 13 is also provided above the powder bed working plane; a molding cylinder 16 is provided below the electron gun 13. This embodiment utilizes an electron beam selective melting molding device to load copper-coated tungsten powders with different copper-tungsten ratios into a powder bin that can independently hold different types of metal powders, and the copper-coated tungsten powder is made to fall onto the powder bed working plane through a valve, and the powder feeder 1 is used to move the powder 2 on the powder bed working plane to below the electron gun 13, and the gradient copper-tungsten contact material is manufactured by 3D printing to achieve a copper-tungsten composite material with a continuous transition from CuW90, CuW80, CuW70, CuW60, and CuW50, such as Figure 2 shown.

[0050] In a feasible embodiment of the present invention, the device further comprises 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 pass through the powder collection hole 18 and fall into the designated independent storage unit 19. The plurality of storage units comprise 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 which are independently arranged 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] The embodiment of the present invention discloses a method for preparing a copper-tungsten gradient electrical contact material. Based on the above-mentioned device for preparing a copper-tungsten gradient electrical contact material, the method comprises the following steps:

[0052] Step 1, using 3D modeling software to establish a 3D model of a copper-tungsten gradient material part;

[0053] Step 2, slicing the three-dimensional model of the copper-tungsten gradient material part established in step 1 using slicing and layering software to obtain two-dimensional scanning trajectory data of each layer;

[0054] Step 3, importing the two-dimensional scanning trajectory data of step 2 into the electron beam selective melting molding equipment;

[0055] Step 4, respectively loading the pre-prepared copper-coated tungsten powders with different copper-tungsten ratios into the respective storage units in the electron beam selective melting molding equipment;

[0056] Step 5, opening the first valve 8, so that the powder in the first storage unit 3 falls into the powder feeder 1, and the electron beam 14 generated by the electron gun 13 completes the copper-tungsten composite material of the first ratio, and the molding height is h1;

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

[0058] Step 7, close the second valve 9, 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 copper-tungsten composite material with the second ratio obtained in step 6, and the forming height is h3;

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

[0060] Step 9, close the fourth valve 11, open the fifth valve 12; make the powder in the fifth storage unit 7 fall into the powder feeder 1, and complete the copper-tungsten composite material with the fifth ratio based on the copper-tungsten composite material with the fourth ratio obtained in step 8, with a molding height of h5.

[0061] Step 10, taking out the formed copper-tungsten gradient composite material 15 from the forming cylinder 16 and cleaning the powder.

[0062] In a 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 prepared by any method of chemical plating and electroplating, and the mass purity of the tungsten powder is not less than 99.9%. The coating thickness of the copper-coated tungsten powder is calculated as follows:

[0063] Assuming that tungsten powder is a sphere with uniform particles, the copper layer is uniformly coated on the tungsten powder after copper plating and is still a uniform sphere. The copper layer thickness of copper-coated tungsten powder is calculated as follows:

[0064]

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

[0066]

[0067] m Cu is the mass of coated copper, D is the average particle size of the copper powder after coating, ρ Cu Copper density is 8.9g / cm 3 .

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

[0069]

[0070] Coating thickness:

[0071]

[0072] The copper layer thickness a of copper-clad tungsten powder can be calculated according to the required copper-tungsten content ratio.

[0073] This embodiment accurately calculates the coating thickness of the copper-coated tungsten powder and freely adjusts the copper-tungsten ratio by changing the thickness of the copper coating layer, so as to complete tungsten-copper composite parts with complex structures. The gradient material performance design and the copper-tungsten ratio are flexible and controllable, which is suitable for the research and development of any new solutions and new products.

[0074] The present invention proposes an innovative copper-tungsten composite contact material design, which adopts a unique gradient structure, and its composition gradually transitions from CuW90 (i.e., 90% tungsten content and 10% copper content) to CuW50 (i.e., 50% tungsten content and 50% copper content). This design cleverly utilizes the change of material composition to optimize the performance of the contact. CuW50 is used in the part where the contact contacts the tail. This ratio provides good conductivity and certain mechanical strength, ensuring the stability and reliability of the connection between the contact and the tail. CuW90 is used in the part where the moving and static contacts contact. This high tungsten content ratio significantly improves the hardness and wear resistance of the contact, thereby enhancing the durability and service life of the contact in harsh working environments. This gradient structure design effectively overcomes the problem of mismatching of the joint parts of two different component materials in traditional contact materials. Through the gradually transitioning component distribution, the thermal barrier and stress barrier of the joint surface are reduced, so that the contact can distribute and transfer heat more evenly when subjected to extreme conditions such as high temperature and high pressure, reducing the thermal stress and mechanical stress caused by differences in material properties.

[0075] In addition, this copper-tungsten gradient material also achieves thermal stress relief, giving full play to the intrinsic characteristics of tungsten and copper. The high copper side (or pure copper side) has good electrical and thermal conductivity, can quickly transfer current and heat, and ensure the normal operation of the contact. The high tungsten side (or pure tungsten side) has the characteristics of high strength, high melting point and low thermal expansion coefficient, and can maintain the stability and shape integrity of the contact under high temperature and high pressure environment. The copper-tungsten composite material transition layer in the middle plays a role in relieving internal stress, ensuring the structural stability and performance consistency of the entire contact material. At the same time, this copper-tungsten functional gradient material (FGM) also has high thermal conductivity. It can quickly transfer the heat generated by the arc to the tail of the contact, greatly reducing the accumulation of heat on the surface of the contact, thereby alleviating the erosion of the arc on the contact. This feature significantly improves the high-voltage breaking capacity and service life of the electrical contact parts, allowing the contact to work more stably when subjected to high voltage and high current impact, and reducing performance degradation and failure caused by arc erosion.

[0076] Preferably, the printing raw materials of the present invention are not limited to copper-coated tungsten powder, but can also be replaced with copper-coated chromium powder, so as to realize the preparation of copper-chromium gradient electrical contact materials. This flexibility enables the present invention to be applicable to the preparation needs of more types of electrical contact materials. At the same time, by adjusting the thickness of the copper coating layer, the present invention can also freely adjust the copper-tungsten ratio, so as to complete the preparation of tungsten-copper composite parts with complex structures. The flexible controllability of this gradient material performance design and the copper-tungsten ratio makes the present invention very suitable for the research and development and application of any new scheme and new product. In summary, the copper-tungsten gradient composite contact material design proposed in the embodiment 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 the contacts, but also meet the preparation needs of more types of electrical contact materials, and provide strong support for the development of power systems and related industries.

[0077] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A copper-tungsten gradient electrical contact material preparation device, characterized in that: The invention comprises an electron beam selective melting molding device located above a powder bed working plane, wherein the electron beam selective melting molding device has a plurality of storage units, and a valve is arranged at the lower end of each storage unit; a powder feeder (1) is placed below the electron beam selective melting molding device, and the powder feeder (1) is located on the powder bed working plane; an electron gun (13) is also arranged above the powder bed working plane; and a molding cylinder (16) is arranged below the electron gun (13).

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

3. A copper-tungsten gradient electrical contact material preparation device according to claim 1, characterized in that: The plurality of storage units comprise 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) which are independently arranged in sequence; a first valve (8) is arranged at the lower end of the first storage unit (3); a second valve (9) is arranged at the lower end of the second storage unit (4); a third valve (10) is arranged at the lower end of the third storage unit (5); a fourth valve (11) is arranged at the lower end of the fourth storage unit (6); and a fifth valve (12) is arranged at the lower end of the fifth storage unit (7).

4. A method for preparing a copper-tungsten gradient electrical contact material, characterized in that: A copper-tungsten gradient electrical contact material preparation device according to claim 3 comprises the following steps: Use 3D modeling software to build a 3D model of copper-tungsten gradient material parts; The 3D model of the copper-tungsten gradient material part is sliced ​​using slicing and layering software to obtain the 2D scanning trajectory data of each layer; Importing two-dimensional scanning trajectory data into electron beam selective melting molding equipment; The pre-prepared copper-coated tungsten powders with different copper-tungsten ratios are respectively loaded into the respective storage units in the electron beam selective melting molding equipment; Opening the first valve (8) allows the powder in the first storage unit (3) to fall into the powder feeder (1), and the electron beam (14) generated by the electron gun (13) completes the copper-tungsten composite material of the first proportion, with a molding height of h1; The first valve (8) is closed and the second valve (9) is opened; the powder in the second storage unit (4) falls into the powder feeder (1), and a copper-tungsten composite material with a second ratio is formed on the basis of the copper-tungsten composite material with the first ratio, with a forming height of h2; The second valve (9) is closed and the third valve (10) is opened; the powder in the third storage unit (5) falls into the powder feeder (1), and a copper-tungsten composite material with a third ratio is formed on the basis of the copper-tungsten composite material with the second ratio, with a forming height of h3; The third valve (10) is closed and the fourth valve (11) is opened; the powder in the fourth storage unit (6) falls into the powder feeder (1), and a copper-tungsten composite material with a fourth ratio is formed on the basis of the copper-tungsten composite material with a third ratio, with a forming height of h4; The fourth valve (11) is closed and the fifth valve (12) is opened; the powder in the fifth storage unit (7) falls into the powder feeder (1), and a copper-tungsten composite material with a fifth ratio is completed on the basis of the copper-tungsten composite material with the fourth ratio, with a molding height of h5, and finally a copper-tungsten gradient composite material (15) is obtained.

5. The method for preparing a copper-tungsten gradient electrical contact material according to claim 4, characterized in that: The preparation method of the copper-coated tungsten powder comprises: calculating the coating thickness of the copper-coated tungsten powder; and plating copper on the outside of the tungsten powder by chemical plating or electroplating.

6. The method for preparing a copper-tungsten gradient electrical contact material according to claim 5, characterized in that: The step of calculating the coating thickness of the copper-coated tungsten powder is specifically calculated as follows: In the formula, m w is the particle mass of tungsten powder; d is the average particle size of tungsten powder before copper coating; ρ w is the density of tungsten, 19.3g / cm 3 ; n is the number of powder particles; In the formula, m Cu is the mass of coated copper; D is the average particle size of the copper powder after coating; ρ Cu is the density of copper, 8.9g / cm 3 ; Where a is the thickness of the copper layer of copper-clad tungsten powder.

7. The method for preparing a copper-tungsten gradient electrical contact material according to claim 4, characterized in that: Also includes: Excess powder in 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).

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

9. The method for preparing a copper-tungsten gradient electrical contact material according to claim 4, characterized in that: The copper-clad tungsten powder includes CuW90, CuW80, CuW70, CuW60 and CuW50.

10. The method for preparing a copper-tungsten gradient electrical contact material according to claim 4, characterized in that: The copper-coated tungsten powder is replaced with copper-coated chromium powder to achieve the preparation of copper-chromium gradient electrical contact material.

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