A tungsten-copper-graphene core-shell structure powder, a preparation method thereof, an electric contact material and a preparation method thereof

Abstract

A tungsten-copper-graphene core-shell structure powder, its preparation method, an electric contact material and its preparation method belong to the technical field of electrical engineering materials, and overcome the defect that tungsten carbide is formed by the reaction of graphene and tungsten in the prior art. The tungsten-copper-graphene core-shell structure powder of the present invention sequentially includes a core, a first coating layer and a second coating layer from the inside to the outside; the material of the core is tungsten; the material of the first coating layer is copper; the material of the second coating layer is graphene. By forming a core-shell structure, the present invention uses copper to isolate between tungsten and graphene, avoiding the generation of tungsten carbide, while improving the conductivity of the material and improving the wettability between the two phases of tungsten and graphene.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical engineering materials, and particularly relates to a tungsten-copper-graphene core-shell structure powder and a preparation method thereof, an electrical contact material and a preparation method thereof. Background Art

[0002] At present, SF6 circuit breakers dominate the 110 kV and above high-voltage, extra-high voltage and ultra-high voltage power transmission and transformation systems in China. However, its reliability problem has become a bottleneck in the upgrade of China's power grid industry. Research shows that the tungsten content directly affects the anti-arc ablation ability of copper-tungsten contacts. When the tungsten content is 60%-80%, the ablation amount of the contacts in SF6 medium is the lowest. Therefore, the electrical contact material of SF6 high-voltage circuit breakers mainly uses CuW80 alloy at present, but it is difficult to meet the performance requirements of arc erosion resistance and mechanical wear under the conditions of extra-high voltage and large current.

[0003] Graphene-modified copper-tungsten electrical contacts can achieve performance improvement, but it is often accompanied by the reaction of graphene with tungsten to form tungsten carbide, resulting in a decrease in the conductivity of the electrical contact material. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that graphene reacts with tungsten to form tungsten carbide in the prior art, so as to provide a tungsten-copper-graphene core-shell structure powder and a preparation method thereof, an electrical contact material and a preparation method thereof.

[0005] For this reason, the present invention provides the following technical solutions.

[0006] In the first aspect, the present invention provides a tungsten-copper-graphene core-shell structure powder, which sequentially includes a core, a first coating layer and a second coating layer from the inside to the outside;

[0007] The material of the core is tungsten;

[0008] The material of the first coating layer is copper;

[0009] The material of the second coating layer is graphene.

[0010] Further, the chemical composition of the tungsten-copper-graphene core-shell structure powder, by mass percentage, includes: carbon 0.0001-0.15%, copper 18-22%, and the balance is tungsten. Preferably, the carbon content is 0.05-0.10%, for example, 0.08%.

[0011] Further, the particle size of the core is 50-60 μm.

[0012] In the second aspect, the present invention provides a preparation method of a tungsten-copper-graphene core-shell structure powder, including:

[0013] Copper is plated on the surface of spherical tungsten powder to form spherical copper-coated tungsten powder;

[0014] Graphene is grown on the surface of the copper-coated tungsten powder to obtain spherical core-shell structured powder with tungsten, copper, and graphene from the inside out in sequence.

[0015] Furthermore, the particle size of the spherical tungsten powder is 50 - 60 μm;

[0016] And / or, the graphene is monolayer graphene.

[0017] Furthermore, electroplating is used to plate copper on the surface of the spherical tungsten powder.

[0018] Furthermore, chemical vapor deposition is used to grow graphene on the surface of the copper-coated tungsten powder.

[0019] Furthermore, the plating solution for the electroplating method includes 40 - 150 g / L of CuSO4·7H2O, 20 - 120 g / L of NH2CH2CH2NH2, 10 - 55 g / L of (NH4)4SO4, and 10 - 55 g / L of Na2SO4·10H2O.

[0020] Furthermore, the specific process of the chemical vapor deposition method is: carbon source and reducing gas are introduced to grow graphene, and the growth temperature is 1100 - 1300 °C.

[0021] In the third aspect, the present invention provides a preparation method for an electric contact material, including: hot pressing the tungsten-copper-graphene core-shell structured powder and then performing hot isostatic pressing treatment.

[0022] Furthermore, the hot pressing conditions are: temperature 400 - 500 °C, pressure 200 - 300 MPa, and pressure holding time 3 - 5 min.

[0023] Furthermore, the hot isostatic pressing conditions are: temperature 400 - 500 °C, pressure 300 - 400 MPa, and pressure holding time 5 - 10 min.

[0024] In the fourth aspect, the present invention provides an electric contact material prepared according to the above preparation method.

[0025] The technical solution of the present invention has the following advantages:

[0026] 1. The tungsten-copper-graphene core-shell structured powder of the present invention includes a core, a first coating layer, and a second coating layer from the inside out in sequence; the material of the core is tungsten; the material of the first coating layer is copper; the material of the second coating layer is graphene. By forming the core-shell structure, copper is used to isolate between tungsten and graphene, avoiding the formation of tungsten carbide, while improving the conductivity of the material and the wettability between the tungsten and graphene phases.

[0027] 2. The electric contact material of the present invention is prepared by hot pressing tungsten-copper-graphene core-shell structure powder and then performing hot isostatic pressing treatment. For the electric contact material used in the arc contacts of extra-high voltage line electrical appliances, the electric contact material of the present invention can effectively improve the arc erosion resistance.

[0028] The electric contact material of the present invention can be applied to high-voltage large-capacity SF6 circuit breakers above 252 KV to solve the reliability and life problems of their arc contacts, and can also be used for manufacturing electric contact elements of electric energy conversion devices in strong arc erosion environments such as electromagnetic railgun rails and pantograph slides of high-speed trains. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It is the XRD pattern of the electric contact material in Example 1;

[0031] Figure 2 It is the XRD pattern of the electric contact material in Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following embodiments are provided to better further understand the present invention, which are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other prior arts and being the same as or similar to the present invention falls within the protection scope of the present invention.

[0033] For those embodiments in which specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0034] Example 1

[0035] This embodiment provides a preparation method for an electric contact, including the following steps:

[0036] 1. Take 500 g of spherical tungsten powder with a particle size of 50 - 60 μm, and perform pretreatment on the spherical tungsten powder: to reduce the agglomeration of the powder during preparation and storage, disperse the spherical tungsten powder in an OP-10 aqueous solution under ultrasonic action for 10 min.

[0037] 2. Copper is electroplated on the surface of spherical tungsten powder to obtain spherical copper-coated tungsten powder: The spherical tungsten powder is added to the plating solution, and the spherical tungsten powder is suspended in the plating solution by mechanical stirring, so that the tungsten powder is in full contact with the plating solution, realizing uniform and stable coating of the tungsten powder. The plating solution includes 50 g / L of CuSO4·7H2O, 60 g / L of NH2CH2CH2NH2, 30 g / L of (NH4)4SO4, and 30 g / L of Na2SO4·10H2O. The solvent of the plating solution is deionized water.

[0038] 3. Graphene is grown on the surface of the copper-coated tungsten powder by fluidized bed chemical vapor deposition. The carbon source for the chemical vapor deposition is methane, the reducing gas is hydrogen, and the growth temperature is 1200 °C.

[0039] The chemical composition of the tungsten-copper-graphene core-shell structure powder prepared in this example, by mass percentage, includes: 0.08% carbon, 20% copper, and the balance is tungsten.

[0040] 4. Hot pressing: The tungsten-copper-graphene core-shell structure powder prepared in step 3 is kept under pressure at 400 °C and 200 MPa for 3 min.

[0041] 5. Hot isostatic pressing: The product of step 4 is kept under pressure at 400 °C and 400 MPa for 5 min to obtain the electrical contact material.

[0042] 6. The electrical contact material is machined into an electrical contact.

[0043] Example 2

[0044] This example provides a method for preparing an electrical contact, including the following steps:

[0045] 1. Take 500 g of spherical tungsten powder with a particle size of 50 - 60 μm, and disperse the spherical tungsten powder in an OP-10 aqueous solution under ultrasonic action for 10 min.

[0046] 2. Copper is electroplated on the surface of spherical tungsten powder to obtain spherical copper-coated tungsten powder: The spherical tungsten powder is added to the plating solution, and the spherical tungsten powder is suspended in the plating solution by mechanical stirring, so that the tungsten powder is in full contact with the plating solution, realizing uniform and stable coating of the tungsten powder. The plating solution includes 50 g / L of CuSO4·7H2O, 60 g / L of NH2CH2CH2NH2, 30 g / L of (NH4)4SO4, and 30 g / L of Na2SO4·10H2O. The solvent of the plating solution is deionized water.

[0047] 3. Graphene is grown on the surface of the copper-coated tungsten powder by fluidized bed chemical vapor deposition. The carbon source for the chemical vapor deposition is methane, the reducing gas is hydrogen, and the growth temperature is 1200 °C.

[0048] The chemical composition of the tungsten-copper-graphene core-shell structure powder prepared in this example, in mass percentage, includes: carbon 0.08%, copper 18%, and the balance is tungsten.

[0049] 4. Powder hot pressing: The tungsten-copper-graphene core-shell structure powder prepared in step 3 is kept under pressure at 500 °C and 200 MPa for 5 minutes.

[0050] 5. Hot isostatic pressing: The product of step 4 is kept under pressure at 500 °C and 300 MPa for 10 minutes to obtain the electrical contact material.

[0051] 6. The electrical contact material is machined into an electrical contact.

[0052] Example 3

[0053] This example provides a method for preparing an electrical contact, including the following steps:

[0054] 1. Take 500 g of spherical tungsten powder with a particle size of 50 - 60 μm, and disperse the spherical tungsten powder in an OP-10 aqueous solution under ultrasonic action for 10 minutes.

[0055] 2. Copper is plated on the surface of the spherical tungsten powder by electroplating to obtain spherical copper-coated tungsten powder: The spherical tungsten powder is added to the plating solution, and the spherical tungsten powder is suspended in the plating solution by mechanical stirring, so that the tungsten powder is in full contact with the plating solution, realizing uniform and stable coating of the tungsten powder. The plating solution includes 50 g / L of CuSO4·7H2O, 60 g / L of NH2CH2CH2NH2, 30 g / L of (NH4)4SO4, and 30 g / L of Na2SO4·10H2O, and the solvent of the plating solution is deionized water.

[0056] 3. Graphene is grown on the surface of the copper-coated tungsten powder by fluidized bed chemical vapor deposition. The carbon source for the chemical vapor deposition is methane, the reducing gas is hydrogen, and the growth temperature is 1200 °C.

[0057] The chemical composition of the electrical contact material prepared in this example, in mass percentage, includes: carbon 0.08%, copper 22%, and the balance is tungsten.

[0058] 4. Powder forming: The tungsten-copper-graphene core-shell structure powder prepared in step 3 is kept under pressure at 450 °C and 250 MPa for 4 minutes.

[0059] 5. Hot isostatic pressing: The product of step 4 is kept under pressure at 450 °C and 350 MPa for 8 minutes to obtain the electrical contact material.

[0060] 6. The electrical contact material is machined into an electrical contact.

[0061] Comparative Example 1

[0062] This comparative example provides a method for preparing an electrical contact, comprising the following steps:

[0063] 1. Mix copper powder, tungsten powder (with a particle size of 50 - 60 μm) and graphene to obtain a mixed powder. By mass percentage, it contains 0.08% carbon, 20% copper, and the balance is tungsten.

[0064] 2. Keep the mixed powder from step 1 under pressure at 400 °C and 200 MPa for 3 minutes.

[0065] 3. Hot isostatic pressing: Keep the product from step 2 under pressure at 400 °C and 400 MPa for 5 minutes to obtain the electrical contact material.

[0066] 4. Machining the electrical contact material into an electrical contact.

[0067] Test Example

[0068] 1) Figure 1 is the XRD pattern of the electrical contact material of Example 1, Figure 2 is the XRD pattern of the electrical contact material of Comparative Example 1. It can be seen from Figure 1 , Figure 2 that no tungsten carbide is formed in the electrical contact material prepared by the present invention.

[0069] 2) Test the conductivity of the electrical contacts prepared in the examples and comparative examples according to the basic performance test method of electrical contact materials GB / T 5586 - 2016.

[0070] 3) Test the arc erosion resistance of the electrical contacts prepared in the examples and comparative examples. The specific test process is: I = 63 kA, U = 500 kV pulse power supply, the on / off cycle is 22 times, the arc duration is 10 ms each time, and then measure its total erosion amount.

[0071] The test results are shown in Table 1.

[0072] Table 1 Electrical contact performance parameters

[0073]

[0074] It can be seen from Figure 1 and Table 1 that by forming a core - shell structure and using copper to isolate between tungsten and graphene, the present invention can avoid the formation of tungsten carbide and improve the conductivity of the material.

[0075] Other performance indicators of the electrical contact prepared by the present invention are as follows: density is 15 - 15.6 g / cm 3 ; hardness is HB220 - 240; flexural strength is 950 - 1100 MPa, and conductivity is 34 - 38% IACS.

[0076] The results of type tests on a 252 kV, 63 kA SF6 circuit breaker show that the life value of the standard sample (CuW80 alloy electrical contact) used for comparison can only reach 50-60% of the required value, while the samples provided by the present invention can all reach the required value of the life index (20 times of electrical life interruption in type tests). Compared with the comparison sample, the contact material provided by the present invention can improve the reliability and service life of electrical switches.

[0077] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing an electrical contact material, characterized in that: include: The tungsten-copper-graphene core-shell structure powder is hot pressed and then hot isostatic pressed; The tungsten-copper-graphene core-shell structure powder includes a core, a first coating layer and a second coating layer from the inside to the outside; The material of the core is tungsten; The first cladding layer material is copper; The second coating layer material is graphene; The chemical composition of the tungsten-copper-graphene core-shell structure powder, in terms of mass percentage, includes: 0.0001-0.08% carbon, 18-22% copper, and the balance tungsten; The preparation method of the tungsten-copper-graphene core-shell structure powder comprises: Copper is plated on the surface of spherical tungsten powder to form spherical copper-coated tungsten powder; Graphene is grown on the surface of copper-coated tungsten powder to obtain a spherical core-shell structure powder with tungsten, copper and graphene from the inside to the outside; Graphene was grown on the surface of copper-coated tungsten powder using chemical vapor deposition; The particle size of the core is 50 to 60 μm; The hot pressing forming conditions are: temperature 400-500°C, pressure 200-300MPa, and holding time 3-5min; The hot isostatic pressing conditions are: temperature 400-500° C., pressure 300-400 MPa, and holding time 5-10 min.

2. The method for preparing an electrical contact material according to claim 1, characterized in that: The graphene is single-layer graphene.

3. The method for preparing an electrical contact material according to any one of claims 1 to 2, characterized in that: Copper is plated on the surface of spherical tungsten powder by electroplating.

4. The method for preparing the electrical contact material according to claim 3, characterized in that: The plating solution of the electroplating method comprises 40-150 g / L of CuSO4·7H2O, 20-120 g / L of NH2CH2CH2NH2, 10-55 g / L of (NH4)4SO4, and 10-55 g / L of Na2SO4·10H2O.

5. The method for preparing an electrical contact material according to claim 1, characterized in that: The specific process of the chemical vapor deposition method is: introducing a carbon source and a reducing gas to grow graphene, and the growth temperature is 1100-1300°C.

6. An electrical contact material obtained according to the preparation method according to any one of claims 1 to 5.

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