Graphene modified electrical contact material and preparation method thereof

Abstract

The application relates to the technical field of electric contact materials, and particularly discloses a graphene modified electric contact material and a preparation method thereof, which comprises the following steps: preparing a polydopamine-graphene suspension; adding a copper-containing solution into the polydopamine-graphene suspension to prepare polydopamine / copper modified graphene material; ball-milling and mixing the polydopamine / copper modified graphene material, aluminum powder, zirconium powder, copper powder and tungsten powder according to the mass percentage of 1-4%, 0.03-0.2%, 0.3-0.8% and 15-20% respectively to obtain a mixture; and performing pressure forming and sintering on the mixture to obtain the graphene modified electric contact material. In the preparation method, the dispersibility and wettability of the graphene are improved by modifying the graphene, the copper, tungsten, aluminum, zirconium and modified graphene are compounded, and the comprehensive performance of the electric contact material, such as the mechanical property, the electrical conductivity and the ablation resistance, is improved by the comprehensive action of the components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical contact materials, and particularly relates to a graphene modified electrical contact material and a preparation method thereof. BACKGROUND

[0002] The electrical contact is one of the core components of electrical switches and instruments, and plays a role in breaking and connecting the circuit and load current. The contact material is required to have good electrical conductivity, thermal conductivity, low and stable contact resistance, high resistance to erosion, high resistance to welding, and good mechanical strength.

[0003] The tungsten-copper electrical contact material has excellent arc erosion resistance and welding resistance, good arc breaking performance, good electrical conductivity and thermal conductivity, good high-temperature strength, and certain plasticity, and is a commonly used electrical contact material. In modern power systems, as the capacity and voltage level of the power grid continue to increase, the performance requirements for the electrical contact material, which is a key component of the switch device, are becoming higher and higher. The existing copper-tungsten (Cu-W) composite material has the following problems in actual application: under the condition of frequent arc breaking, the copper phase on the surface of the contact forms metal droplets due to the high temperature of the arc, which leads to continuous material loss and accumulation of microstructure defects, seriously affecting the mechanical strength and electrical life of the contact; due to the difference in physical properties between copper and tungsten, it is difficult to prepare a more dense and uniform microstructure copper-tungsten composite material, and the like, which makes it difficult for the traditional copper-tungsten composite material to meet the performance requirements of the electrical contact in modern power systems.

[0004] Graphene is a single-layer two-dimensional honeycomb crystal structure of carbon material formed by sp 2 hybrid orbitals of carbon atoms, and has excellent mechanical properties, electrical properties and thermal conductivity. The electrical contact material modified by graphene can greatly improve the arc erosion resistance and friction and wear resistance compared with the copper-tungsten alloy electrical contact. In the preparation process of the graphene reinforced copper-based composite material, there is a significant problem of interface compatibility. Specifically, the agglomeration tendency of the graphene sheet layer formed by the strong van der Waals force is much higher than the mechanical adhesion energy between the graphene and the copper matrix, and this thermodynamic driving force leads to the tendency of graphene to aggregate rather than uniform dispersion, which leads to the aggregation of graphene in the metal matrix (such as copper and tungsten) and uneven dispersion, which limits the reinforcement effect and affects the electrical conductivity and mechanical strength. In addition, the wetting between copper and graphene is poor, and no chemical reaction occurs between the two in the solid state, so that the interface can only rely on weak mechanical and van der Waals forces, and the interface bonding between graphene and the metal matrix is insufficient, which is prone to microcracks under high temperature or arc impact, affecting the arc erosion resistance. SUMMARY

[0005] In view of the above defects, the application provides a preparation method of graphene modified electric contact material, which can improve the dispersibility and interface bonding of graphene, and improve the mechanical properties, electrical conductivity and ablation resistance of the electric contact material, and the specific technical scheme is as follows:

[0006] A preparation method of graphene modified electric contact material, comprising the following steps:

[0007] (1) Disperse graphene oxide into deionized water, ultrasonic treatment, adjust the pH value to 7.5-8.5, and obtain a graphene oxide suspension; add hydrochloric acid dopamine for reaction, and obtain a polydopamine-graphene suspension;

[0008] (2) Add a copper-containing solution into the polydopamine-graphene suspension, the copper-containing solution contains copper salt, complexing agent, stabilizer and reducing agent, stir and react, centrifuge, wash, and vacuum dry to obtain a polydopamine / copper modified graphene material;

[0009] (3) According to the mass percentage, 1-4% of the polydopamine / copper modified graphene material obtained in step (2), 0.03-0.2% of aluminum powder, 0.3-0.8% of zirconium powder, 15-20% of copper powder, and the balance of tungsten powder are ball-mixed to obtain a mixture;

[0010] (4) The mixture is pressure-formed, and then sintered to obtain the graphene modified electric contact material.

[0011] The technical scheme of the application is based on the following technical principle: first, the graphene is modified by polydopamine, dopamine has a certain reducing property, and can reduce graphene oxide during the polymerization process, the polydopamine structure contains a large number of active groups such as amino and phenolic hydroxyl groups, which can chelate copper ions and anchor them on the graphene sheet, and then reduce to obtain a polydopamine / copper modified graphene material, which is used for preparing an electric contact material, which can improve the dispersibility and surface activity of the graphene material, improve the interface bonding between graphene and copper, and thus improve the performance of the electric contact material; on the other hand, polydopamine decomposes and releases a small amount of ammonia gas at high temperature, and the reaction forms N-doped carbon material with good electrical conductivity and wettability, and a small amount of ammonia gas can promote the conversion of aluminum into aluminum nitride dispersed phase, and further improve the mechanical properties of the electric contact material.

[0012] Preferably, in the above preparation method of graphene modified electric contact material, in step (1), the concentration of the graphene oxide suspension is 1-2 mg / mL, the mass ratio of graphene oxide to hydrochloric acid dopamine is 1:0.5-2, the reaction temperature is 50-80 DEG C, and the reaction time is 12-28 h.

[0013] Preferably, in the preparation method of the graphene modified electrical contact material, in the step (2), the copper salt in the copper-containing solution is copper chloride, the concentration of the copper salt is 0.03-0.05 mol / L, the complexing agent is ethylenediaminetetraacetic acid, the concentration of the complexing agent is 0.03-0.05 mol / L, the stabilizer is boric acid, the concentration of the stabilizer is 0.1-0.25 mol / L, and the reducing agent is dimethylamine borane, and the concentration of the reducing agent is 0.1-0.3 mol / L.

[0014] Preferably, in the preparation method of the graphene modified electrical contact material, the mass ratio of the graphene oxide to the copper salt is 1:8-15.

[0015] Preferably, in the preparation method of the graphene modified electrical contact material, in the step (3), the ball milling mixing is as follows: the polydopamine / copper modified graphene material, aluminum powder and copper powder are first ball milled under a nitrogen or argon protective atmosphere, the ball milling speed is 300-500 r / min, and the ball milling time is 1-3 h; then the tungsten powder and the zirconium powder are added, and the ball milling is performed again under a nitrogen or argon protective atmosphere, the ball milling speed is 300-500 r / min, and the ball milling time is 3-5 h. First, the aluminum powder and the copper powder are ball milled with the polydopamine / copper modified graphene material to promote the uniform dispersion of the aluminum powder, the copper powder and the polydopamine / copper modified graphene material, and then the tungsten powder and the zirconium powder are added for mixing. The zirconium powder improves the surface wettability between the copper and the tungsten, improves the overall sintering density of the electrical contact material, and thus improves the performance of the electrical contact material.

[0016] Preferably, in the preparation method of the graphene modified electrical contact material, in the step (4), the mixture is pressed into a green body under a pressure of 300-400 MPa.

[0017] Preferably, in the preparation method of the graphene modified electrical contact material, in the step (4), the sintering is as follows: pre-sintering is first performed at 700-900 ℃ for 2-4 h under an argon atmosphere, and then final sintering is performed at 1200-1400 ℃ for 1-2 h. The pre-sintering at 700-900 ℃ for 2-4 h is beneficial to promote the decomposition of the polydopamine at high temperature to release a small amount of ammonia gas, form N-doped carbon material, and promote the conversion of aluminum into aluminum nitride dispersed phase, so as to improve the mechanical and electrical properties of the graphene modified electrical contact material.

[0018] Preferably, in the preparation method of the graphene modified electrical contact material, the particle size of the copper powder is 5-10 μm, the particle size of the tungsten powder is 2-5 μm, the particle size of the aluminum powder is 3-8 μm, and the particle size of the zirconium powder is 5-15 μm.

[0019] Preferably, in the preparation method of the graphene modified electrical contact material, the graphene oxide is single-layer graphene oxide, the flake diameter is 0.5-5 microns, and the thickness is 0.8-1.2 microns.

[0020] In another aspect, the present application also provides a graphene modified electrical contact material prepared by the above preparation method.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The preparation method of the graphene modified electrical contact material improves the dispersibility and wettability of graphene by modifying the graphene, and improves the comprehensive performance of the electrical contact material, such as the mechanical properties, electrical conductivity and ablation resistance, by compounding copper, tungsten, aluminum, zirconium and modified graphene.

[0023] 2. The preparation method of the graphene modified electrical contact material first modifies the graphene with polydopamine, which contains a large number of active groups such as amino and phenolic hydroxyl groups in the structure, can chelate copper ions to anchor them on the graphene sheet, and reduces to obtain a polydopamine / copper modified graphene material, which can improve the dispersibility and surface activity of the graphene material, improve the interface bonding between the graphene and copper, and thus improve the performance of the electrical contact material. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0025] Figure 1 The photo of the graphene modified electrical contact material test piece prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0026] The specific embodiments of the present application will be described in detail below, but it should be understood that the protection scope of the present application is not limited by the specific embodiments. Unless otherwise defined, all professional terms used in the following are the same as those commonly understood by those skilled in the art. The professional terms used in this paper are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0027] The particle size of the copper powder used below is 5-10 μm, the particle size of the tungsten powder is 2-5 μm, the particle size of the aluminum powder is 3-8 μm, the particle size of the zirconium powder is 5-15 μm, and the purity is above 99.5%.

[0028] Example 1

[0029] A preparation method of a graphene modified electrical contact material, comprising the following steps:

[0030] (1) Disperse graphene oxide into deionized water, and perform ultrasonic treatment, wherein the ultrasonic oscillation power is 800 W, the ultrasonic oscillation time is 1 h, the ultrasonic frequency is 40 KHz, and the pH value is adjusted to 8.5, to obtain a graphene oxide suspension with a concentration of 1.5 mg / mL; add hydrochloric acid dopamine to perform reaction, wherein the mass ratio of graphene oxide to hydrochloric acid dopamine is 1:1, the reaction temperature is 60°C, and the reaction time is 28 h, to obtain a polydopamine-graphene suspension;

[0031] (2) Add a copper-containing solution into the polydopamine-graphene suspension, wherein the copper-containing solution is a mixed aqueous solution of copper chloride, ethylenediaminetetraacetic acid, boric acid and dimethylamine borane, the concentration of copper chloride is 0.05 mol / L, the concentration of ethylenediaminetetraacetic acid is 0.05 mol / L, the concentration of boric acid is 0.2 mol / L, the concentration of dimethylamine borane is 0.15 mol / L, and the mass ratio of graphene oxide to copper chloride is 1:10; perform stirring reaction at room temperature and a rotating speed of 500 r / min for 2 h, centrifuge to obtain a precipitate, wash with deionized water, and then perform vacuum drying at 60°C, to obtain a polydopamine / copper modified graphene material; the polydopamine / copper modified graphene material prepared in this embodiment comprises, in terms of mass percentage, 21.8% of polydopamine-graphene and 78.2% of copper;

[0032] (3) According to mass percentage, take 2.5% of the polydopamine / copper modified graphene material, 0.08% of aluminum powder, 0.52% of zirconium powder, 17% of copper powder, and the rest of tungsten powder as raw materials; then perform ball milling of the polydopamine / copper modified graphene material, the aluminum powder and the copper powder under an argon protection atmosphere, wherein the ball milling rotating speed is 400 r / min and the ball milling time is 2 h; further add the tungsten powder and the zirconium powder, and perform ball milling again under the argon protection atmosphere, wherein the ball milling rotating speed is 400 r / min and the ball milling time is 4 h, to obtain a mixture;

[0033] (4) Perform compression molding of the mixture under a pressure of 350 MPa to obtain a green body; first perform pre-sintering by increasing the temperature to 800°C at a temperature increasing rate of 20°C / min and maintaining the temperature for 3 h, and then perform final sintering by increasing the temperature to 1300°C at a temperature increasing rate of 10°C / min and maintaining the temperature for 1.5 h, to obtain a graphene modified electrical contact material.

[0034] Example 2

[0035] A preparation method of a graphene modified electrical contact material, comprising the following steps:

[0036] (1) dispersing graphene oxide into deionized water, ultrasonic treatment, ultrasonic oscillation power is 800W, ultrasonic oscillation time is 1h, ultrasonic frequency is 40KHz, adjusting pH value to 8.5, obtaining a concentration of 1.5mg / mL of graphene oxide suspension; adding hydrochloric acid dopamine for reaction, the mass ratio of graphene oxide to hydrochloric acid dopamine is 1:2, the reaction temperature is 60℃, the reaction time is 28h, obtaining a polydopamine-graphene suspension;

[0037] (2) adding a copper-containing solution into the polydopamine-graphene suspension, the copper-containing solution is a mixed aqueous solution of copper chloride, ethylenediaminetetraacetic acid, boric acid and dimethylamine borane, the concentration of copper chloride is 0.05mol / L, the concentration of ethylenediaminetetraacetic acid is 0.05mol / L, the concentration of boric acid is 0.2mol / L, the concentration of dimethylamine borane is 0.15mol / L, the mass ratio of graphene oxide to copper chloride is 1:15; stirring at room temperature and a rotating speed of 500r / min for 2h, centrifuging, deionized water washing, vacuum drying at 60℃, obtaining a polydopamine / copper modified graphene material; the polydopamine / copper modified graphene material prepared in this embodiment comprises, in terms of mass percentage: polydopamine-graphene 23.1%, copper 76.9%;

[0038] (6) according to mass percentage, polydopamine / copper modified graphene material 4%, aluminum powder 0.2%, zirconium powder 0.3%, copper 15%, the balance is tungsten powder, weighing the raw materials; then the polydopamine / copper modified graphene material, aluminum powder and copper powder are ball milled under an argon protective atmosphere, the ball milling speed is 400r / min, the ball milling time is 2h; then tungsten powder and zirconium powder are added, and ball milling is carried out again under an argon protective atmosphere, the ball milling speed is 400r / min, the ball milling time is 4h, obtaining a mixture;

[0039] (4) the mixture is pressed into a green body under a pressure of 350MPa; under an argon atmosphere, first, the temperature is raised to 900℃ at a temperature rising rate of 20℃ / min and kept for 2h for pre-sintering, then the temperature is raised to 1300℃ at a temperature rising rate of 10℃ / min and kept for 1.5h for final sintering, obtaining a graphene modified electrical contact material.

[0040] Example 3

[0041] A preparation method of a graphene modified electrical contact material, comprising the following steps:

[0042] (7) dispersing graphene oxide into deionized water, ultrasonic treatment, ultrasonic oscillation power is 800W, ultrasonic oscillation time is 1h, ultrasonic frequency is 40KHz, adjusting pH value to 8.5, obtaining graphene oxide suspension with concentration of 1.5mg / mL; adding dopamine hydrochloride to react, mass ratio of graphene oxide to dopamine hydrochloride is 1:0.5, reaction temperature is 60℃, reaction time is 28h, obtaining polydopamine-graphene suspension;

[0043] (8) adding copper-containing solution into the polydopamine-graphene suspension, the copper-containing solution is a mixed aqueous solution of copper chloride, ethylenediaminetetraacetic acid, boric acid and dimethylamine borane, concentration of copper chloride is 0.05mol / L, concentration of ethylenediaminetetraacetic acid is 0.05mol / L, concentration of boric acid is 0.2mol / L, concentration of dimethylamine borane is 0.15mol / L, mass ratio of graphene oxide to copper chloride is 1:8; stirring at room temperature and rotating speed of 500r / min for 2h, centrifuging, deionized water washing, vacuum drying at 60℃, obtaining polydopamine / copper modified graphene material; the polydopamine / copper modified graphene material prepared in this embodiment comprises, in terms of mass percentage: polydopamine-graphene 20.5%, copper 79.5%;

[0044] (9) taking raw materials according to mass percentage: polydopamine / copper modified graphene material 1.5%, aluminum powder 0.03%, zirconium powder 0.8%, copper powder 18%, and the balance is tungsten powder; then ball milling the polydopamine / copper modified graphene material, aluminum powder and copper powder under argon protection atmosphere, ball milling rotating speed is 400r / min, ball milling time is 2h; then adding tungsten powder and zirconium powder, and ball milling again under argon protection atmosphere, ball milling rotating speed is 400r / min, ball milling time is 4h, obtaining a mixture;

[0045] (4) molding the mixture into a green body under a pressure of 350MPa; under argon atmosphere, first increasing temperature to 700℃ at a temperature increasing rate of 20℃ / min and keeping for 4h to pre-sinter, then increasing temperature to 1300℃ at a temperature increasing rate of 10℃ / min and keeping for 1.5h to final sintering, obtaining graphene modified electric contact material.

[0046] Comparative Example 1

[0047] A preparation method of graphene modified electric contact material, comprising the following steps:

[0048] (1) according to the mass percentage, graphene 0.5%, aluminum powder 0.08%, zirconium powder 0.52%, copper powder 19%, the balance of tungsten powder, the raw materials are weighed; then the graphene, aluminum powder and copper powder are ball milled under the protection of argon atmosphere, the ball milling speed is 400r / min, and the ball milling time is 2h; then the tungsten powder and zirconium powder are added, and the ball milling is carried out again under the protection of argon atmosphere, the ball milling speed is 400r / min, and the ball milling time is 4h, to obtain a mixture;

[0049] (4) the mixture is pressed into a green body under the pressure of 350MPa; under the argon atmosphere, first, the temperature is raised to 800℃ at a rate of 20℃ / min and kept for 3h for pre-sintering, then the temperature is raised to 1300℃ at a rate of 10℃ / min and kept for 1.5h for final sintering, to obtain the graphene modified electrical contact material.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is that step (4) is: the mixture is pressed into a green body under the pressure of 350MPa; under the argon atmosphere, the temperature is raised to 1300℃ at a rate of 10℃ / min and kept for 1.5h for final sintering, to obtain the graphene modified electrical contact material.

[0052] The electrical conductivity of the electrical contact materials prepared in the examples and comparative examples is tested according to GB / T 5586-2016 Electrical Contact Material Basic Performance Test Method.

[0053] The electrical contact materials of the examples and comparative examples are machined into electrical contacts, and the arc erosion resistance of the prepared electrical contacts is tested. The specific test process is: I=63kA, U=500kV pulse power source, the on / off cycle number is 22 times, the arc continuous action time of each time is 10ms, and then the total erosion amount is measured.

[0054] Table 1 Electrical contact material performance data

[0055]

[0056] For 35kV SF6 high-voltage circuit breaker, full-power breaking frequency test, the reference sample (CuW80 alloy material) has a frequency of only 12 times, and the sample of the present application can reach 20 times or more, which shows that the contact material provided by the present application can improve the reliability and service life of the electrical switch.

[0057] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A method of making a graphene-modified electrical contact material, characterized by, The method comprises the following steps: (1) dispersing graphene oxide into deionized water, ultrasonic treatment, adjusting pH value to 7.5~8.5, obtaining graphene oxide suspension; adding dopamine hydrochloride for reaction, obtaining polydopamine-graphene suspension; (2) adding copper-containing solution into the polydopamine-graphene suspension, the copper-containing solution comprising copper salt, complexing agent, stabilizer and reducing agent, stirring and reacting, centrifuging, washing, vacuum drying, obtaining polydopamine / copper modified graphene material; (3) mixing polydopamine / copper modified graphene material 1~4%, aluminum powder 0.03~0.2%, zirconium powder 0.3~0.8%, copper powder 15~20% by mass percentage, and the rest being tungsten powder, obtaining mixture by ball milling; (4) pressure forming the mixture, then sintering, pre-sintering at 700~900℃ for 2~4h under argon atmosphere, then final sintering at 1200~1400℃ for 1~2h, obtaining graphene modified electrical contact material.

2. The method for preparing the graphene-modified electrical contact material according to claim 1, characterized in that, In the step (1), the concentration of graphene oxide suspension is 1~2mg / mL, the mass ratio of graphene oxide to dopamine hydrochloride is 1:0.5~2, the reaction temperature is 50~80℃, and the reaction time is 12~28h.

3. The method for preparing the graphene-modified electrical contact material according to claim 1, characterized in that, In the step (2), in the copper-containing solution, the copper salt is copper chloride, the concentration of copper salt is 0.03~0.05mol / L, the complexing agent is ethylenediaminetetraacetic acid, the concentration of complexing agent is 0.03~0.05mol / L, the stabilizer is boric acid, the concentration of stabilizer is 0.1~0.25mol / L, and the reducing agent is dimethylamine borane, the concentration of reducing agent is 0.1~0.3mol / L.

4. The method of claim 1, wherein the graphene-modified electrical contact material is prepared by a process comprising: providing a graphene material; and mixing the graphene material with a metal material to form a graphene- metal mixture. The mass ratio of graphene oxide to copper salt is 1:8~15.

5. The method of claim 1, wherein the graphene-modified electrical contact material is prepared by the steps of: providing a graphene layer on a substrate; and depositing a metal layer on the graphene layer. In the step (3), the ball milling comprises: firstly, ball milling the polydopamine / copper modified graphene material, aluminum powder and copper powder under nitrogen or argon protective atmosphere, the ball milling speed is 300~500r / min, and the ball milling time is 1~3h; then, adding tungsten powder and zirconium powder, and ball milling again under nitrogen or argon protective atmosphere, the ball milling speed is 300~500r / min, and the ball milling time is 3~5h.

6. The method of claim 1, wherein the graphene-modified electrical contact material is prepared by a process comprising: providing a graphene sheet; and depositing a metal layer on the graphene sheet. In the step (4), the mixture is formed into a blank under a pressure of 300~400MPa.

7. The method of claim 1, wherein the graphene-modified electrical contact material is prepared by a process comprising: providing a graphene material; and mixing the graphene material with a metal material to form a graphene- metal mixture. The particle size of copper powder is 5~10μm, the particle size of tungsten powder is 2~5μm, the particle size of aluminum powder is 3~8μm, and the particle size of zirconium powder is 5~15μm.

8. The method of claim 1, wherein the graphene-modified electrical contact material is prepared by a process comprising: providing a graphene material; and mixing the graphene material with a metal material to form a graphene- metal mixture. The graphene oxide is single-layer graphene oxide, the flake diameter is 0.5~5μm, and the thickness is 0.8~1.2μm.

9. A graphene-modified electrical contact material, characterized by, The graphene modified electrical contact material is prepared by the preparation method in any one of claims 1~8.

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