Graphene reinforced copper-based electrical contact material and preparation method thereof

Abstract

The invention provides a graphene reinforced copper-based electrical contact material and a preparation method thereof. The electrical contact material comprises the following raw materials in percentage by mass: 15-35% of tungsten powder, 1-10% of chromium powder, 1-5% of molybdenum powder, 0.1-1% of cerium oxide powder, 0.5-2% of copper-based graphene powder and the balance of copper powder. According to the graphene reinforced copper-based electrical contact material and the preparation method thereof, surface copper-based treatment is carried out on graphene, so that the problems that the interface infiltration between graphene and copper is poor and the copper is easy to oxidize are effectively solved, and the obtained electrical contact material has excellent mechanical property, conductivity, oxidation resistance and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic and electrical materials, and in particular to a graphene-enhanced copper-based electrical contact material and a preparation method thereof. Background Art

[0002] Electrical contacts, also known as contacts or joints, are very critical contact elements in instruments and electrical appliances. They are mainly responsible for connecting or disconnecting circuits and load currents. Ideal electrical contact materials must have good physical properties, mechanical properties, electrical contact properties, chemical properties, and processing and manufacturing properties. Currently, the most commonly used electrical contact materials are silver and silver-based composite materials, such as silver-oxide, silver-nickel, silver-copper, silver-cadmium, silver-carbon, silver-tungsten and other alloys. This type of material uses a large amount of silver; it is easy to generate oxides such as silver oxide and tungsten oxide when breaking, causing temperature rise; it is easy to sulfide and wear, and its life as an electrical contact material fluctuates greatly. At the same time, since the annual output of silver is very limited and the price is extremely expensive, the cost of contact materials is very high. Therefore, it is of great significance to find cheap metals with good conductivity that can replace silver to prepare electrical contact materials.

[0003] Copper has a similar conductivity to silver and is inexpensive, so it may become a substitute for silver in contact materials. Although copper has excellent electrical, thermal and corrosion resistance properties, when copper is used as a weak electrical contact material, its surface is easily oxidized, and the conductivity of copper oxide is very low. The contact resistance value increases with the generation of oxide, causing the material to emit a lot of heat during operation, resulting in very poor reliability of the electrical contact switch and difficult to guarantee its service life. Therefore, it is difficult for copper and general copper alloys to meet the comprehensive performance requirements of electrical contact materials.

[0004] At present, the hardness and arc erosion resistance of electrical contact materials can be improved by adding multiple components to form a reinforcement phase. As a new type of nanomaterial, graphene has the advantages of high specific strength, high thermal conductivity and high electrical conductivity, and its application in the field of electronics and electrical engineering is increasingly valued. Graphene's various superior physical and chemical properties make it possible to become a composite material reinforcement phase material with outstanding functions. It can be used as a reinforcement material for metals to improve the strength and thermal stability of metals. However, as a non-metallic material, graphene has the disadvantage of poor wettability with metal materials, and its poor interface bonding with metals affects the performance of the material. Therefore, it is particularly important to solve the problem of easy oxidation of copper and the interface bonding between the copper matrix and the non-metallic reinforcement phase.

[0005] There are many methods for preparing copper-based electrical contact materials. For example, the patent publication (CN110484803A) discloses a mixed dispersion-enhanced copper-tungsten-chromium electrical contact material. Since the graphene is not surface-treated, the interface bonding between the graphene and the copper matrix is ​​inevitably poor. The patent publication (CN105609159A) discloses a copper-plated graphene-enhanced copper-based electrical contact material and a preparation method thereof. Although the graphene is copper-plated by magnetron sputtering, the cost of magnetron sputtering is high, and it is difficult to mass-produce. In addition, there are problems such as uneven coating and poor bonding. Summary of the invention

[0006] Based on the technical problems existing in the background technology, the present invention proposes a graphene-enhanced copper-based electrical contact material and a preparation method thereof. By subjecting the graphene to surface copper-based treatment, the problems of poor interface wetting between graphene and copper and easy oxidation of copper are effectively solved, so that the obtained electrical contact material has excellent mechanical, conductive and anti-oxidation properties.

[0007] The invention provides a graphene-enhanced copper-based electrical contact material, wherein the raw materials thereof comprise, by mass percentage, 15-35% of tungsten powder, 1-10% of chromium powder, 1-5% of molybdenum powder, 0.1-1% of cerium oxide powder, 0.5-2% of copper-based graphene powder, and the remainder of copper powder.

[0008] In the present invention, a copper-based graphene powder is prepared by a liquid phase in-situ reduction method. After being used in a copper-based electrical contact material, graphene and copper can be combined by molecular-level interaction forces to obtain a relatively good copper-graphene interface, and the mechanical properties and antioxidant properties are significantly improved while maintaining excellent conductive properties.

[0009] Preferably, the particle size of the tungsten powder and the molybdenum powder is 1-10 μm, and the particle size of the chromium powder is 10-50 μm.

[0010] Preferably, the copper powder is electrolytic copper powder or atomized copper powder, and the particle size is 40-80 μm.

[0011] Preferably, the cerium oxide powder is loaded on the surface of graphene, which is obtained by aminating graphene and then hydrothermally reacting it with a cerium salt;

[0012] Preferably, the graphene amination is specifically carried out by subjecting graphene oxide to a condensation reaction with ethylenediamine and then to a reduction reaction.

[0013] In the present invention, when cerium oxide powder is loaded on the surface of graphene, the graphene oxide is first condensed with ethylenediamine and reduced to graft amino groups on the graphene surface. After that, when the graphene oxide is hydrothermally reacted with cerium salt, an affinity effect is formed between cerium ions in the cerium salt and the amino groups, thereby cerium ions are evenly distributed on the graphene surface. After the hydrothermal reaction, highly active cerium oxide nanoparticles can be loaded on the graphene surface to ensure the mechanical and electrical improvement effects on copper-based electrical contact materials.

[0014] In the present invention, cerium oxide powder is loaded on the graphene surface, which can not only activate the graphene surface and improve the interface bonding force between the graphene and the copper matrix, but also promote the formation of carbides at the interface, thereby playing a pinning strengthening role, thereby further improving the mechanical properties of the obtained electrical contact material.

[0015] Preferably, the copper-based graphene powder is obtained by grafting polyvinyl imidazole onto the surface of graphene and then performing a reduction reaction with a copper salt;

[0016] Preferably, the graphene surface is grafted with polyvinyl imidazole by esterifying and condensing graphene oxide with 2-bromoisobutyryl bromide, and then polymerizing with 1-vinylimidazole.

[0017] Preferably, the reducing agent of the reduction reaction is at least one of ascorbic acid, formaldehyde or hydrazine hydrate;

[0018] Preferably, the reduction reaction is carried out at a temperature of 100-150° C. and for a time of 6-12 h.

[0019] In the present invention, when a copper-based graphene powder is prepared by a liquid phase reduction method, polyvinyl imidazole is pre-grafted on the graphene surface. When a liquid phase reduction reaction is carried out with a copper salt, on the one hand, the complexing effect of polyvinyl imidazole on copper ions is utilized to provide abundant binding sites for subsequent loading of copper on the graphene surface. On the other hand, the good dispersion effect of polyvinyl imidazole is utilized to promote the reduction of the copper salt to form spherical nano copper particles, which are uniformly grown on the graphene surface. The finally obtained copper-based graphene powder has a complete structure, high activity, and is free of the introduction of other impurities such as copper oxide and cuprous oxide.

[0020] In the present invention, the loading of copper nanoparticles on the copper-based graphene powder not only greatly enhances the interfacial bonding force between the graphene and the copper matrix in the later powder metallurgy forming process, but also significantly improves the minimum tensile strength between the grain boundaries of the obtained copper-based electrical contact material. At the same time, the enhancement of the interfacial bonding force also weakens the electron interface scattering effect, thereby improving the conductive performance.

[0021] The present invention also provides a method for preparing the above-mentioned graphene-enhanced copper-based electrical contact material, comprising the following steps:

[0022] S1, mixing tungsten powder, chromium powder, molybdenum powder, cerium oxide powder, copper-based graphene powder and copper powder and ball milling to obtain a mixed powder;

[0023] S2. The mixed powder is compression molded and then sintered at high temperature to obtain the graphene-enhanced copper-based electrical contact material.

[0024] Preferably, in step S1, the rotation speed of the ball mill is 100-500 r / min, and the time is 1-3 h.

[0025] Preferably, in step S2, the compression molding pressure is 600-800 MPa.

[0026] Preferably, in step S2, the high temperature sintering is performed at a temperature of 1000-1300° C. and for a time of 1-2 h.

[0027] The present invention provides a graphene-enhanced copper-based electric contact material and a preparation method thereof. In the copper-based electric contact material, copper is selected as a matrix, which is cheap and abundant in resources compared with silver. Tungsten powder, chromium powder, molybdenum powder and cerium oxide powder are added to the copper matrix at the same time, thereby improving the arc erosion resistance and fusion welding resistance of the electric contact material. Copper-based graphene is added, and copper nanoparticles are loaded on the graphene through an in-situ chemical reduction reaction, so that copper nanoparticles can be used as a medium for increasing the interaction force between graphene and copper powder, so that the interface force between copper powder and graphene is significantly improved, and the obtained electric contact material also obtains excellent comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of the grafted poly(ethylene imidazole) graphene described in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The technical solutions of the present invention are described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0030] Example 1

[0031] This embodiment provides a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0032] (1) Preparation of copper-based graphene powder:

[0033] Add flake graphite (average particle size of 25 μm) and sodium nitrate to concentrated sulfuric acid, the mass ratio of flake graphite to sodium nitrate is 1:0.2, after stirring and reacting for 1 hour in an ice bath, add potassium permanganate, the mass ratio of flake graphite to potassium permanganate is 1:0.8, after stirring and reacting for 2 hours in an ice bath, add hydrogen peroxide (concentration of 5 wt%) for reduction, filter, wash with water, and dry to obtain graphene oxide;

[0034] The graphene oxide is added to dichloromethane for ultrasonic dispersion, 2-bromoisobutyryl bromide and triethylamine are added, the mass ratio of graphene oxide, 2-bromoisobutyryl bromide and triethylamine is 1:0.1:0.5, the reaction is stirred for 6 hours under nitrogen protection, hydrogen is introduced, the temperature is raised to 90° C. and the reaction is stirred for 4 hours, filtered, washed, and dried to obtain brominated graphene; the brominated graphene and 1-vinylimidazole, cuprous bromide, and pentamethyldiethylenetriamine are added to N,N-dimethylformamide, the mass ratio of brominated graphene to 1-vinylimidazole, cuprous bromide, and pentamethyldiethylenetriamine is 1:0.5:0.05:0.1, the temperature is raised to 40° C. under nitrogen protection and the reaction is stirred for 3 hours, filtered, washed, and dried to obtain grafted polyvinyl imidazole graphene;

[0035] The grafted polyimidazolyl graphene is added into deionized water for uniform ultrasonic dispersion, copper acetate and ascorbic acid are added, the mass ratio of the grafted polyimidazolyl graphene, copper acetate and ascorbic acid is 1:1.5:1, after uniform stirring and dispersion, sodium hydroxide solution (concentration of 1 mol / L) is added to adjust the pH to 11, hydrothermally react at 120° C. for 6 h, filter, wash and dry to obtain the copper-based graphene powder;

[0036] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0037] 25wt% of tungsten powder (average particle size of 3.5μm), 5wt% of chromium powder (average particle size of 42μm), 3wt% of molybdenum powder (average particle size of 3μm), 0.5wt% of cerium oxide powder (average particle size of 0.5μm), 65.5wt% of electrolytic copper powder (average particle size of 67μm) and 1wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 300r / min for 2h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0038] The mixed powder is transferred to a graphite mold and compression molded at 700 MPa to obtain a green body; the green body is sintered at a high temperature of 1200°C for 1.5 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0039] Example 2

[0040] This embodiment provides a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0041] (1) Preparation of copper-based graphene powder refers to Example 1;

[0042] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0043] 15wt% of tungsten powder (average particle size of 3.5μm), 10wt% of chromium powder (average particle size of 42μm), 1wt% of molybdenum powder (average particle size of 3μm), 1wt% of cerium oxide powder (average particle size of 0.5μm), 72.5wt% of electrolytic copper powder (average particle size of 67μm) and 0.5wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 100r / min for 3h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0044] The mixed powder is transferred to a graphite mold and compression molded at 600 MPa to obtain a green body; the green body is sintered at a high temperature of 1300°C for 1 hour under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0045] Example 3

[0046] This embodiment provides a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0047] (1) Preparation of copper-based graphene powder refers to Example 1;

[0048] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0049] 35wt% of tungsten powder (average particle size of 3.5μm), 1wt% of chromium powder (average particle size of 42μm), 5wt% of molybdenum powder (average particle size of 3μm), 0.1wt% of cerium oxide powder (average particle size of 0.5μm), 56.9wt% of electrolytic copper powder (average particle size of 67μm) and 2wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 500r / min for 1h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0050] The mixed powder is transferred to a graphite mold and compression molded at 800 MPa to obtain a green body; the green body is sintered at a high temperature of 1000°C for 2 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0051] Example 4

[0052] This embodiment provides a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0053] (1) Preparation of copper-based graphene powder refers to Example 1;

[0054] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0055] 25wt% of tungsten powder (average particle size of 3.5μm), 5wt% of chromium powder (average particle size of 42μm), 3wt% of molybdenum powder (average particle size of 3μm), 0.5wt% of cerium oxide powder, 65.5wt% of electrolytic copper powder (average particle size of 67μm) and 1wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 300r / min for 2h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0056] The cerium oxide powder is loaded on the surface of graphene and is specifically prepared by the following method:

[0057] Add flake graphite (average particle size of 25 μm) and sodium nitrate to concentrated sulfuric acid, the mass ratio of flake graphite to sodium nitrate is 1:0.2, after stirring and reacting for 1 hour in an ice bath, add potassium permanganate, the mass ratio of flake graphite to potassium permanganate is 1:1.2, after stirring and reacting for 2 hours in an ice bath, add hydrogen peroxide (concentration of 5 wt%) for reduction, filter, wash with water, and dry to obtain graphene oxide;

[0058] The graphene oxide is added to N-methylpyrrolidone and ultrasonically dispersed uniformly, ethylenediamine is added, and the mass ratio of graphene oxide to ethylenediamine is 1:0.1, the temperature is raised to 80° C. and stirred for reaction for 4 hours, hydrogen is introduced, the temperature is raised to 90° C. and stirred for reaction for 6 hours, and the mixture is filtered, washed, and dried to obtain amino graphene;

[0059] The amination graphene is added to deionized water for ultrasonic dispersion, cerium nitrate and ammonia water are added, the mass ratio of the amination graphene, cerium nitrate and ammonia water is 1:15:1, hydrothermally reacted at 180° C. for 24 hours, filtered, washed and dried to obtain cerium oxide powder supported on the surface of graphene;

[0060] The mixed powder is transferred to a graphite mold and compression molded at 700 MPa to obtain a green body; the green body is sintered at a high temperature of 1200°C for 1.5 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0061] Comparative Example 1

[0062] This comparative example proposes a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0063] 25wt% of tungsten powder (average particle size of 3.5μm), 5wt% of chromium powder (average particle size of 42μm), 3wt% of molybdenum powder (average particle size of 3μm), 0.5wt% of cerium oxide powder (average particle size of 0.5μm), 65.5wt% of electrolytic copper powder (average particle size of 67μm) and 1wt% of flake graphite powder (average particle size of 25μm) were mixed and added into a ball mill, and ball milled at a speed of 300r / min for 2h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0064] The mixed powder is transferred to a graphite mold and compression molded at 700 MPa to obtain a green body; the green body is sintered at a high temperature of 1200°C for 1.5 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0065] Comparative Example 2

[0066] This comparative example proposes a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0067] (1) Preparation of copper-based graphene powder:

[0068] Add flake graphite (average particle size of 25 μm) and sodium nitrate to concentrated sulfuric acid, the mass ratio of flake graphite to sodium nitrate is 1:0.2, after stirring and reacting for 1 hour in an ice bath, add potassium permanganate, the mass ratio of flake graphite to potassium permanganate is 1:0.8, after stirring and reacting for 2 hours in an ice bath, add hydrogen peroxide (concentration of 5 wt%) for reduction, filter, wash with water, and dry to obtain graphene oxide;

[0069] The graphene oxide is added to dichloromethane and ultrasonically dispersed uniformly, hydrogen is introduced, the temperature is raised to 90° C., and the mixture is stirred and reacted for 4 hours, filtered, washed, and dried to obtain reduced graphene oxide;

[0070] The reduced graphene oxide is added to deionized water and ultrasonically dispersed uniformly, copper acetate and ascorbic acid are added, and the mass ratio of the reduced graphene oxide, copper acetate and ascorbic acid is 1:1.5:1. After stirring and dispersing uniformly, a sodium hydroxide solution (concentration of 1 mol / L) is added to adjust the pH to 11, and a hydrothermal reaction is carried out at 120° C. for 6 h, and then filtered, washed and dried to obtain the copper-based graphene powder;

[0071] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0072] 25wt% of tungsten powder (average particle size of 3.5μm), 5wt% of chromium powder (average particle size of 42μm), 3wt% of molybdenum powder (average particle size of 3μm), 0.5wt% of cerium oxide powder (average particle size of 0.5μm), 65.5wt% of electrolytic copper powder (average particle size of 67μm) and 1wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 300r / min for 2h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0073] The mixed powder is transferred to a graphite mold and compression molded at 700 MPa to obtain a green body; the green body is sintered at a high temperature of 1200°C for 1.5 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0074] Comparative Example 3

[0075] This comparative example proposes a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0076] (1) Preparation of copper-based graphene powder:

[0077] Add flake graphite (average particle size of 25 μm) and sodium nitrate to concentrated sulfuric acid, the mass ratio of flake graphite to sodium nitrate is 1:0.2, after stirring and reacting for 1 hour in an ice bath, add potassium permanganate, the mass ratio of flake graphite to potassium permanganate is 1:0.8, after stirring and reacting for 2 hours in an ice bath, add hydrogen peroxide (concentration of 5 wt%) for reduction, filter, wash with water, and dry to obtain graphene oxide;

[0078] The graphene oxide is added to dichloromethane and ultrasonically dispersed uniformly, hydrogen is introduced, the temperature is raised to 90° C., and the mixture is stirred and reacted for 4 hours, filtered, washed, and dried to obtain reduced graphene oxide;

[0079] The reduced graphene oxide is added to deionized water and ultrasonically dispersed uniformly, copper acetate, ascorbic acid and polyvinyl imidazole (PVI) are added, and the mass ratio of the reduced graphene oxide, copper acetate, ascorbic acid and polyvinyl imidazole is 1:1.5:1:0.5. After stirring and dispersing uniformly, sodium hydroxide solution (concentration of 1 mol / L) is added to adjust the pH to 11, hydrothermally react at 120° C. for 6 h, filter, wash and dry to obtain the copper-based graphene powder;

[0080] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0081] 25wt% of tungsten powder (average particle size of 3.5μm), 5wt% of chromium powder (average particle size of 42μm), 3wt% of molybdenum powder (average particle size of 3μm), 0.5wt% of cerium oxide powder (average particle size of 0.5μm), 65.5wt% of electrolytic copper powder (average particle size of 67μm) and 1wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 300r / min for 2h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0082] The mixed powder is transferred to a graphite mold and compression molded at 700 MPa to obtain a green body; the green body is sintered at a high temperature of 1200°C for 1.5 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0083] Comparative Example 4

[0084] This comparative example proposes a method for preparing a graphene-enhanced copper-based electrical contact material, which specifically includes:

[0085] (1) Preparation of copper-based graphene powder refers to Example 1;

[0086] (2) Preparation of graphene-enhanced copper-based electrical contact materials:

[0087] 25wt% of tungsten powder (average particle size of 3.5μm), 5wt% of chromium powder (average particle size of 42μm), 3wt% of molybdenum powder (average particle size of 3μm), 0.5wt% of cerium oxide powder, 65.5wt% of electrolytic copper powder (average particle size of 67μm) and 1wt% of the above copper-based graphene powder were mixed and added into a ball mill, and ball milled at a speed of 300r / min for 2h, and the ball milling was carried out under argon protection to obtain a mixed powder;

[0088] The cerium oxide powder is loaded on the surface of graphene and is specifically prepared by the following method:

[0089] Add flake graphite (average particle size of 25 μm) and sodium nitrate to concentrated sulfuric acid, the mass ratio of flake graphite to sodium nitrate is 1:0.2, after stirring and reacting for 1 hour in an ice bath, add potassium permanganate, the mass ratio of flake graphite to potassium permanganate is 1:1.2, after stirring and reacting for 2 hours in an ice bath, add hydrogen peroxide (concentration of 5 wt%) for reduction, filter, wash with water, and dry to obtain graphene oxide;

[0090] The graphene oxide is added to N-methylpyrrolidone and ultrasonically dispersed uniformly, hydrogen is introduced, the temperature is raised to 90° C. and stirred for reaction for 6 hours, and the mixture is filtered, washed, and dried to obtain reduced graphene oxide;

[0091] The reduced graphene oxide is added to deionized water and ultrasonically dispersed uniformly, cerium nitrate and ammonia water are added, the mass ratio of the reduced graphene oxide, cerium nitrate and ammonia water is 1:15:1, hydrothermally reacted at 180° C. for 24 hours, filtered, washed, and dried to obtain cerium oxide powder supported on the surface of graphene;

[0092] The mixed powder is transferred to a graphite mold and compression molded at 700 MPa to obtain a green body; the green body is sintered at a high temperature of 1200°C for 1.5 hours under argon protection, and after cooling to room temperature, the temperature is increased to 600°C at a heating rate of 10°C / min, and after keeping warm for 2 hours, the graphene-enhanced copper-based electrical contact material is obtained.

[0093] The density, electrical conductivity, hardness and oxidation resistance of the graphene-enhanced copper-based electrical contact materials obtained in the above examples and comparative examples were measured by referring to the following methods:

[0094] The density of the electrical contact material is measured and calculated using a hydrostatic balance and the Archimedes displacement method; the conductivity of the electrical contact material is tested using a digital conductivity meter; the Brinell hardness of the electrical contact material is tested using a Brinell hardness tester in accordance with the provisions of GB / T231.1-2009; the tensile strength of the electrical contact material is tested using an electronic universal testing machine in accordance with the provisions of GBT228.1-2010; the oxidation weight gain of the electrical contact material after oxidation in an atmospheric environment at 400°C for 20 hours is tested;

[0095] Table 1 Performance of the graphene-enhanced copper-based electrical contact materials described in Examples and Comparative Examples

[0096]

[0097]

[0098] It can be seen from the results in the above table that the electrical contact material of the present invention has excellent mechanical, electrical conductivity and anti-oxidation properties.

[0099] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A graphene-enhanced copper-based electrical contact material, characterized in that: The raw materials include, by mass percentage, 15-35% of tungsten powder, 1-10% of chromium powder, 1-5% of molybdenum powder, 0.1-1% of cerium oxide powder, 0.5-2% of copper-based graphene powder, and the balance is copper powder.

2. The graphene-enhanced copper-based electrical contact material according to claim 1, characterized in that: The particle sizes of the tungsten powder and the molybdenum powder are 1-10 μm, and the particle size of the chromium powder is 10-50 μm.

3. The graphene-enhanced copper-based electrical contact material according to claim 1 or 2, characterized in that: The copper powder is electrolytic copper powder or atomized copper powder, and the particle size is 40-80 μm.

4. The graphene-enhanced copper-based electrical contact material according to any one of claims 1 to 3, characterized in that: The cerium oxide powder is loaded on the surface of graphene, and is obtained by aminating the graphene and then performing a hydrothermal reaction with a cerium salt; Preferably, the graphene amination is specifically carried out by subjecting graphene oxide to a condensation reaction with ethylenediamine and then to a reduction reaction.

5. The graphene-enhanced copper-based electrical contact material according to any one of claims 1 to 4, characterized in that: The copper-based graphene powder is obtained by grafting poly(vinylimidazole) onto the surface of graphene and then performing a reduction reaction with copper salt; Preferably, the graphene surface is grafted with polyvinyl imidazole by esterifying and condensing graphene oxide with 2-bromoisobutyryl bromide, and then polymerizing with 1-vinylimidazole.

6. The graphene-enhanced copper-based electrical contact material according to claim 5, characterized in that: The reducing agent of the reduction reaction is at least one of ascorbic acid, formaldehyde or hydrazine hydrate; Preferably, the reduction reaction is carried out at a temperature of 100-150° C. and for a time of 6-12 h.

7. A method for preparing the graphene-enhanced copper-based electrical contact material according to any one of claims 1 to 6, characterized in that: The steps include: S1, mixing tungsten powder, chromium powder, molybdenum powder, cerium oxide powder, copper-based graphene powder and copper powder and ball milling to obtain a mixed powder; S2. The mixed powder is compression molded and then sintered at high temperature to obtain the graphene-enhanced copper-based electrical contact material.

8. The method for preparing the graphene-enhanced copper-based electrical contact material according to claim 7, characterized in that: In step S1, the ball milling speed is 100-500 r / min and the time is 1-3 h.

9. The method for preparing the graphene-enhanced copper-based electrical contact material according to claim 7 or 8, characterized in that: In step S2, the compression molding pressure is 600-800 MPa.

10. The method for preparing the graphene-enhanced copper-based electrical contact material according to any one of claims 7 to 9, characterized in that: In step S2, the high temperature sintering temperature is 1000-1300°C and the time is 1-2h.

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