CN114164355B

CN114164355B - Graphene reinforced metal composite material and preparation method and application thereof

Info

Publication number: CN114164355B
Application number: CN202111520885.4A
Authority: CN
Inventors: 梁益龙; 何冠宇; 杨玉龙; 罗平西
Original assignee: Guizhou University
Current assignee: Guizhou University
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2022-07-12
Anticipated expiration: 2041-12-13
Also published as: CN114164355A

Abstract

The invention belongs to the technical field of alloys, and particularly relates to a graphene reinforced metal composite material as well as a preparation method and application thereof. The invention provides a graphene reinforced metal composite material, which comprises a metal matrix and a reinforcing phase; the reinforcing phase comprises a graphene outer shell and metal particles within the graphene outer shell; the metal matrix is copper or hard alloy; the metal matrix and the metal particles are made of the same material. The graphene reinforced metal composite material provided by the invention has excellent comprehensive performance, wherein the graphene reinforced copper-based metal material has high strength, high plasticity and excellent conductivity, and the graphene reinforced hard alloy material has high hardness and excellent wear resistance.

Description

Graphene reinforced metal composite material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of alloys, and particularly relates to a graphene reinforced metal composite material and a preparation method and application thereof.

Background

The properties of alloy materials are often difficult to balance. For example, copper-based composites often have strength, plasticity, and electrical conductivity mismatches, and the high hardness and high fracture toughness of cemented carbides continue to conflict (H, E, outer. physical and chemical nature of segmented carbides [ J ]. International Materials Reviews,1979,24(1): 149-). 173). Graphene is a two-dimensional carbon nanomaterial, has attracted attention due to its excellent electrical, thermal and mechanical properties, and is an ideal reinforcing material for metal matrix composites. However, although graphene has been successfully used as a reinforcing phase in the fields of polymers and ceramics, the reinforcing effect of graphene in the metal field is affected due to the serious agglomeration and poor interface bonding property with the metal matrix.

For example, the graphene reinforced copper-based composite material usually increases the strength and reduces the plasticity and conductivity at the same time, because graphene and copper are difficult to be effectively combined and uniformly dispersed, the graphene and copper matrix can be combined through physical adhesion to a certain extent by ball milling treatment, but the structure of graphene is seriously damaged by high-energy ball milling, and effective adhesion cannot be achieved by low-speed ball milling. In addition, the problem of poor combination of graphene and a metal interface can be effectively solved by using metal nanoparticle loaded modified graphene, but the process involves complex chemical reaction and has the problem of uncontrollable graphene loading, and a large amount of impurities attached to nanoparticles subjected to chemical reduction can influence the performances of the obtained copper-based composite material such as conductivity and the like. The existing copper-based material containing graphene cannot give consideration to both strong plasticity and high conductivity.

For another example, in a graphene-reinforced cemented carbide-based composite material, the improvement of toughness is accompanied by the decrease of strength and hardness, and studies have shown that when the grain size of tungsten carbide is reduced to nanometer level, the strength and hardness of the cemented carbide are significantly improved, and the toughness is also improved to a certain extent, which breaks the trend that the toughness is decreased along with the increase of hardness of the traditional cemented carbide, but the nano tungsten carbide has high sintering activity, is very easy to generate coarsening in the sintering process, and the performance of the coarsening cemented carbide is not good (k.jia, t.e.fischer, b.galis.microstructure, hardnes and hardness of Nanostructured and composite [ J ]. Nanostructured Materials,1998,10(5): 875-891). In view of the problem of contradiction between strength, hardness and toughness of cemented carbide, researchers have conducted a lot of research, and although many preparation methods have been proposed, it is difficult to improve the strength, hardness and toughness of cemented carbide simultaneously because the addition of graphene is difficult to achieve a good dispersion effect, the binding force with the cemented carbide matrix is not sufficient, and the abnormal growth of nano tungsten carbide cannot improve the mechanical properties of cemented carbide in a controllable manner (Hezaveh Taraneh, mozami-Goudarzi Mohammad, Kazemi Arghavan. effects of GNP on the mechanical properties and sizing wear of WC-10 wt% Co-centered carbide [ J ]. Ceramics International,2021,47(13): 18020-. The existing hard alloy material containing graphene cannot give consideration to both high hardness and high wear resistance.

Disclosure of Invention

In view of this, the present invention provides a graphene reinforced metal composite material, which has excellent comprehensive properties.

In order to achieve the purpose of the invention, the invention provides the following technical scheme:

the invention provides a graphene reinforced metal composite material, which comprises a metal matrix and a reinforcing phase; the reinforcing phase comprises a graphene outer shell and metal particles within the graphene outer shell; the metal matrix is copper or hard alloy; the metal matrix and the metal particles are made of the same material.

Preferably, the content of graphene in the graphene reinforced metal composite material is 0.1-0.5 wt.%.

Preferably, the content of the metal particles in the graphene reinforced metal composite material is 10-50 wt.%.

Preferably, the size of the reinforcing phase is 0.05-15 μm, and the size of the metal matrix is 0.5-20 μm.

The invention also provides a preparation method of the graphene reinforced metal composite material, which comprises the following steps when the metal matrix is copper:

mixing graphene oxide with opposite charges and copper particles, and performing electrostatic adsorption on the graphene oxide and the copper particles to form an enhanced phase precursor;

mixing the enhanced phase precursor and a copper matrix, and sintering to obtain the graphene enhanced metal composite material;

when the metal matrix is hard alloy, the method comprises the following steps:

mixing graphene with opposite charges with hard alloy particles, and forming a reinforced phase by electrostatic adsorption of the graphene and the hard alloy particles;

and mixing the reinforcing phase and the hard alloy matrix, and sintering to obtain the graphene reinforced metal composite material.

Preferably, when the metal matrix is copper, the oppositely charged graphene oxide and the copper particles are negatively charged graphene oxide and positively charged copper particles, respectively;

the positively charged copper particles are cetyl trimethyl ammonium bromide modified copper particles.

Preferably, when the metal matrix is a cemented carbide, the oppositely charged graphene and cemented carbide particles are positively charged graphene and negatively charged cemented carbide particles, respectively;

the positively charged graphene is hexadecyl trimethyl ammonium bromide modified graphene; the hard alloy particles with negative electricity are sodium dodecyl sulfate modified hard alloy particles.

Preferably, when the metal matrix is copper, the size of the copper particles is 0.5-2 μm, and the size of the copper matrix is 5-20 μm; when the metal matrix is made of hard alloy, the size of the hard alloy particles is 0.05-2 mu m, and the size of the hard alloy matrix is 0.5-10 mu m.

Preferably, when the metal matrix is copper, the sintering is: heating from room temperature to a first temperature at a first heating rate, preserving heat, cooling to a first cooling temperature at a first cooling rate after heat preservation, and cooling along with a furnace;

the first heating rate is 7-10 ℃/min, the first temperature is 850-920 ℃, and the heat preservation time is 1-1.5 h; the first cooling rate is 7-10 ℃/min, and the first cooling temperature is 100-200 ℃;

when the metal matrix is hard alloy, the sintering is as follows: heating from room temperature to the first temperature at the first heating rate, preserving heat, cooling to the first cooling temperature at the first cooling rate after preserving heat, and cooling along with the furnace;

the temperature rise rate of the first temperature is 7-10 ℃/min, the temperature of the first temperature is 1400-1460 ℃, and the heat preservation time is 1.5-2.5 h; the temperature reduction rate of the first temperature reduction is 7-10 ℃/min, and the temperature reduction temperature of the first temperature reduction is 100-200 ℃.

The invention also provides an application of the graphene reinforced metal composite material in the technical scheme or the graphene reinforced metal composite material obtained by the preparation method in the technical scheme, wherein when the metal matrix is copper, the application is in electronic packaging, electric switch and integrated circuit;

when the metal substrate is a cemented carbide, the application is in cutting tools, bearings, drilling tools, wire drawing dies, mining machinery and structural components.

In the invention, when the metal matrix is copper, the graphene coats the copper particles to form an enhanced phase, the enhanced phase enables the graphene and the copper matrix to generate an interface reaction, so that the interface combination is strengthened, the sintering gap can be filled, and the sintering density is improved; in the sintering process, the copper particles in the reinforcing phase are used as a flowing carrier to prevent the graphene from being pasted and agglomerated, so that the graphene is uniformly dispersed, the uniform dispersion of the reinforcing phase is further ensured, the uniformly distributed reinforcing phase prevents the reinforcing phase particles from growing up through a coating structure, and the strength and the plasticity of the graphene reinforced metal composite material are improved under the synergistic effects of load transfer and the like; the reinforcing phase constructs a communication bridge between large-size copper matrix grains, and the graphene on the surface of the reinforcing phase provides a rapid channel for electron transmission, so that the negative influence of grain refinement and sintering defects on the conductivity can be compensated, and the graphene reinforced metal composite material has high plasticity and improved conductivity.

When the metal matrix is hard alloy, the enhanced phase formed by coating the hard alloy particles with the graphene is introduced into the alloy matrix of the hard alloy material, the graphene plays a role of inhibiting the growth of crystal grains, the growth of nano-scale and micron-scale tungsten carbide crystal grains is effectively prevented in the sintering process, the hard alloy particles block the agglomeration of the graphene in the enhanced phase with a coating structure, the graphene is uniformly dispersed, the pores among the hard alloy particles are filled with the enhanced phase formed by the hard alloy particles and the graphene, the binder phase cobalt in the hard alloy is more uniformly distributed, and the refined crystal grains and the enhanced phase cooperatively promote the hardness of the composite material; moreover, the friction coefficient of the hard alloy containing the graphene is obviously reduced due to the lubricating effect of the graphene, and the friction coefficient of the hard alloy is also reduced due to the improvement of the hardness; the cobalt phase which is uniformly distributed makes the cobalt to be more difficult to separate from the matrix in the friction process, reduces the separation of the cobalt phase, namely reduces the possibility that the tungsten carbide grains form abrasive particles after separating from the matrix, further reduces the matrix material which is worn away by the abrasive particles, improves the wear resistance and fracture toughness of the composite material by cooperating with the lubricating action of the graphene, and realizes the purpose of synchronously improving the hardness, wear resistance and fracture toughness of the hard alloy.

The test result of the embodiment shows that when the alloy matrix is copper, the density of the graphene reinforced metal composite material is 95-97%, the hardness is 95-106.8 HV, the tensile strength is 191-245 MPa, the elongation is 31-59%, the yield strength is 52-119 MPa, and the conductivity is 84-95 IACS%. When the alloy matrix is made of hard alloy, the hardness of the graphene reinforced metal composite material is 1703-1882 HV, and the wear resistance is excellent.

Drawings

FIG. 1 is an AFM image of graphene oxide;

FIG. 2 is a thickness diagram of a white line portion of FIG. 1;

FIG. 3 is an SEM image of graphene oxide, copper matrix powder, copper particles, the copper-based material in comparative example 1, and the graphene reinforced metal composite obtained in example 1;

FIG. 4 is a graph of specimen dimensions in a tensile test;

FIG. 5 is a graph showing the density variation of a material under different graphene content conditions;

FIG. 6 is a graph showing hardness change curves of materials under different graphene content conditions;

FIG. 7 is a graph of conductivity of materials with different graphene contents;

fig. 8 is an SEM image of the graphene reinforced metal composite obtained in example 4;

fig. 9 is an SEM image of the graphene reinforced metal composite obtained in comparative example 6;

fig. 10 is an SEM image of the graphene reinforced metal composite obtained in comparative example 7;

FIG. 11 shows the hardness of the graphene-reinforced metal composite materials obtained in examples 4 to 6 and comparative examples 6 to 7

FIG. 12 is a friction coefficient chart of the graphene reinforced metal composite obtained in example 4 and comparative examples 6 to 7;

FIG. 13 is a graph of wear marks of the graphene reinforced metal composites obtained in example 4 and comparative examples 6 to 7.

Detailed Description

The invention provides a graphene reinforced metal composite material, which comprises a metal matrix and a reinforcing phase; the reinforcing phase comprises a graphene outer shell and metal particles within the graphene outer shell; the metal matrix is copper or hard alloy; the base body and the metal particles are made of the same material.

In the present invention, the graphene reinforced metal composite includes a metal matrix. In the present invention, the metal substrate is copper or cemented carbide. In the present invention, the chemical composition of the cemented carbide is a hard phase and a binder phase. In the present invention, the hard phase preferably comprises tungsten carbide; the binder phase preferably comprises cobalt. In the invention, when the metal matrix is copper, the graphene reinforced metal composite material is a graphene reinforced copper-based material; when the metal matrix is a hard alloy, the graphene reinforced metal composite material is a graphene reinforced hard alloy material.

In the present invention, the graphene reinforced metal composite includes a reinforcing phase; the reinforcing phase includes a graphene outer shell and metal particles within the graphene outer shell.

In the present invention, the metal matrix and the metal particles are made of the same material.

In the invention, the content of graphene in the graphene reinforced metal composite material is preferably 0.1-0.5 wt.%. Specifically, when the metal matrix is copper, the content of graphene in the graphene reinforced copper-based material is preferably 0.1 to 0.5 wt.%, and more preferably 0.1 to 0.3 wt.%. When the metal matrix is a hard alloy, the content of graphene in the graphene reinforced hard alloy material is preferably 0.1 to 0.5 wt.%, and more preferably 0.2 to 0.4 wt.%.

In the invention, the content of the metal particles in the graphene reinforced metal composite material is preferably 10-50 wt.%. Specifically, when the metal matrix is copper, the content of the metal particles in the graphene reinforced copper-based material is preferably 10 to 50 wt.%, and more preferably 10 to 30 wt.%. When the metal matrix is a hard alloy, the content of the metal particles in the graphene-reinforced hard alloy material is preferably 10 to 50 wt.%, and more preferably 10 to 30 wt.%.

In the present invention, the size of the reinforcing phase is preferably 0.05 to 15 μm. Specifically, when the metal matrix is copper, the size of the reinforcing phase is more preferably 0.5-15 μm, and still more preferably 1-11 μm. When the metal matrix is a hard alloy, the size of the reinforcing phase is more preferably 0.05-15 μm, still more preferably 0.5-10 μm, and further preferably 1-8 μm.

In the invention, the size of the metal matrix is preferably 0.5-20 μm. Specifically, when the metal matrix is copper, the size of the metal matrix is more preferably 5-20 μm, and is further preferably 8-15 μm. When the metal matrix is made of hard alloy, the size of the metal matrix is more preferably 0.5-10 μm, and is further preferably 1-8 μm.

when the metal matrix is hard alloy, the method comprises the following steps:

mixing oppositely charged graphene and hard alloy particles, and performing electrostatic adsorption on the graphene and the hard alloy particles to form a reinforced phase;

and mixing the reinforced phase and the hard alloy matrix, and sintering to obtain the graphene reinforced metal composite material.

When the metal matrix is copper, graphene oxide with opposite charges and copper particles are mixed, and the graphene oxide and the copper particles are electrostatically adsorbed to form an enhanced phase precursor.

In the present invention, when the metal matrix is copper, the oppositely charged graphene oxide and copper particles are negatively charged graphene oxide and positively charged copper particles, respectively; the positively charged copper particles are preferably cetyltrimethylammonium bromide modified copper particles.

In the present invention, when the metal matrix is copper, the preparation method of the enhanced phase precursor preferably includes the steps of:

mixing the copper particles with hexadecyl trimethyl ammonium bromide to obtain copper particles with positively charged surfaces;

dispersing the copper particles with the positively charged surfaces in alcohol to obtain alcohol dispersion liquid of the copper particles with the positive charges;

and mixing the alcohol dispersion liquid of the positively charged copper particles and the graphene oxide aqueous dispersion liquid for electrostatic adsorption to obtain the enhanced phase precursor of the copper particles coated by the graphene oxide.

The invention mixes the copper particles and cetyl trimethyl ammonium bromide to obtain the copper particles with positive electricity on the surface.

In the present invention, the particle size of the copper particles is preferably 0.5 to 2 μm, more preferably 0.6 to 1.5 μm, and still more preferably 0.7 to 1.2 μm.

In the present invention, the mass ratio of the copper particles to cetyltrimethylammonium bromide (CTAB) is preferably (10 to 50): (0.1 to 0.5), more preferably (20 to 30): (0.2-0.3). In the present invention, the cetyltrimethylammonium bromide is preferably used in the form of an alcoholic cetyltrimethylammonium bromide solution; the mass percentage concentration of the cetyl trimethyl ammonium bromide in the cetyl trimethyl ammonium bromide alcohol solution is preferably 0.02-1.5%, and more preferably 0.1-1.3%. In the present invention, the mixing of the copper particles and cetyltrimethylammonium bromide is preferably stirring, more preferably magnetic stirring; the stirring speed is not particularly limited in the invention, and the speed known to those skilled in the art can be adopted; the stirring time is preferably 2-3 h. After stirring, the solid product obtained is preferably dried in the present invention to obtain copper particles with positively charged surfaces. In the present invention, the drying temperature is preferably 40 to 50 ℃.

After the copper particles with the positively charged surfaces are obtained, the copper particles with the positively charged surfaces are dispersed in alcohol to obtain alcohol dispersion liquid of the copper particles with the positively charged surfaces.

The content ratio of the copper particles with positively charged surfaces to the alcohol is not particularly limited, and the copper particles with positively charged surfaces can be dispersed in the alcohol; the content of ethanol in the alcohol is not particularly limited in the present invention, and the content of ethanol in the alcohol known to those skilled in the art may be used.

In the present invention, the method of dispersion is preferably stirring; the stirring time is preferably 0.5-2 h, and more preferably 1-2 h; the stirring rate is not particularly limited in the present invention, and may be a stirring rate well known to those skilled in the art.

In the invention, the average sheet diameter of the graphene oxide is preferably 1-15 μm, and more preferably 1.5-10 μm; the number of layers is preferably 1 to 100.

After the alcohol dispersion liquid of the positively charged copper particles is obtained, the alcohol dispersion liquid of the positively charged copper particles and the aqueous dispersion liquid of the graphene oxide are mixed for electrostatic adsorption, and the enhanced phase precursor of the copper-coated graphene oxide particles is obtained.

In the present invention, the preparation method of the graphene oxide aqueous dispersion is preferably: and placing the graphene oxide in deionized water for ultrasonic stripping to obtain the graphene oxide aqueous dispersion. The invention has no special site for the proportional relation between the graphene oxide and the deionized water, and aims to uniformly disperse the graphene oxide in the deionized water. In the invention, the time of ultrasonic stripping is preferably 2-3 h; the speed of the ultrasonic wave is preferably 40-50 kHz.

In the present invention, the mixing of the alcohol dispersion of positively charged copper particles and the aqueous dispersion of graphene oxide is preferably performed by adding the aqueous dispersion of graphene oxide to the alcohol dispersion of positively charged copper particles. In the present invention, the method of mixing the alcohol dispersion of positively charged copper particles and the aqueous dispersion of graphene oxide is preferably stirring; the stirring time is preferably 0.5-1 h; the stirring rate is not particularly limited in the present invention, and may be a stirring rate well known to those skilled in the art. According to the invention, through stirring, the graphene oxide electrostatically adsorbs positively charged copper particles to form an enhanced phase precursor.

In the invention, the time of electrostatic adsorption is preferably 0.5-1 h. In the present invention, the electrostatic adsorption is preferably performed under stirring conditions.

After obtaining the reinforcement precursor, mixing the reinforcement precursor and the copper matrix, and sintering to obtain the graphene reinforced metal composite material.

The invention preferably mixes the enhanced phase precursor and the copper matrix, dries, and sinters the enhanced phase precursor-copper matrix powder.

In the invention, the size of the copper matrix is preferably 5-20 μm, more preferably 8-15 μm, and still more preferably 9-14 μm.

In the present invention, the sintering apparatus is preferably a vacuum hot-pressing furnace. In an embodiment of the invention, the vacuum autoclave is preferably manufactured by Shanghai Haoyue electric furnace technology, Inc., and is preferably of the type VVPgr-15-2000. In the present invention, the sintering mold is preferably a graphite mold.

In the present invention, the mixing of the reinforcing phase precursor and the copper matrix is preferably mixing the reinforcing phase precursor and the copper matrix under a liquid dispersion condition; the liquid dispersion conditions are preferably used in the form of an aqueous dispersion of the reinforcing phase precursor. After the enhanced phase precursor and the copper matrix are mixed under the liquid state dispersion condition, the solid-liquid separation and drying are preferably carried out on the obtained solid-liquid system, and the obtained solid matter is the enhanced phase precursor-copper matrix powder. In the present invention, the solid-liquid separation is preferably suction filtration; the suction filtration is not particularly limited in the present invention, and may be a suction filtration known to those skilled in the art. In the present invention, the temperature of the drying is preferably 30 to 50 ℃. The invention leads the enhanced phase precursor to be uniformly dispersed in the gap of the copper matrix by forming the enhanced phase precursor-copper matrix powder.

In the present invention, when the metal substrate is copper, the method preferably further comprises, before sintering: vacuumizing the equipment chamber to less than or equal to 20Pa, introducing protective gas until the pressure of the equipment chamber is 0.02Pa, and repeating for at least 3 times; the protective gas is argon.

In the present invention, when the metal substrate is copper, the sintering is preferably: and raising the temperature from room temperature to a first temperature at a first temperature raising rate, preserving the heat, then lowering the temperature to a first temperature lowering temperature at a first temperature lowering rate, and cooling along with the furnace.

In the invention, the first heating rate is preferably 7-10 ℃/min, and more preferably 8-9 ℃/min; the first temperature is preferably 850-920 ℃, and more preferably 860-910 ℃; the heat preservation time is preferably 1-1.5 h, and more preferably 1-1.4 h; the first cooling rate is preferably 7-10 ℃/min, and more preferably 8-9 ℃/min; the first cooling temperature is preferably 100-200 ℃, and more preferably 110-200 ℃.

When the metal matrix is copper, the present invention preferably further comprises: and releasing gas from the furnace top when the pressure in the chamber of the sintering equipment reaches 0.02MPa, and discharging impurity gas released by CTAB pyrolysis and graphene oxide reduction in the powder sintering process.

In the invention, when the metal matrix is copper, the sintering is carried out under the condition of pressure maintaining; the pressure for maintaining the pressure is preferably 40-50 MPa.

When the alloy matrix is copper, the graphene oxide in the enhanced phase precursor-copper matrix powder is thermally reduced into graphene through sintering, and the shaping of the graphene enhanced metal composite material is completed.

When the metal matrix is hard alloy, the preparation method of the graphene reinforced metal composite material comprises the following steps:

According to the invention, graphene with opposite charges and hard alloy particles are mixed, and the graphene and the hard alloy particles are electrostatically adsorbed to form a reinforcing phase.

In the present invention, when the metal matrix is a cemented carbide, the graphene and cemented carbide particles with opposite charges are positively charged graphene and negatively charged cemented carbide particles, respectively; the positively charged graphene is preferably hexadecyl trimethyl ammonium bromide modified graphene; the negatively charged cemented carbide particles are preferably sodium dodecyl sulfate modified cemented carbide particles.

In the present invention, when the metal matrix is a cemented carbide, the preparation method of the reinforcing phase comprises the steps of:

mixing hard alloy particles with lauryl sodium sulfate, and dispersing the obtained hard alloy particles with negative electricity on the surface in water to obtain a dispersion liquid of the hard alloy particles with negative electricity;

mixing graphene and hexadecyl trimethyl ammonium bromide, and dispersing the obtained graphene with positively charged surface in water to obtain a positively charged graphene dispersion liquid;

and mixing the negative-charged hard alloy particle dispersion liquid and the positive-charged graphene dispersion liquid for electrostatic adsorption to obtain the reinforcing phase of the graphene-coated hard alloy particles.

According to the invention, hard alloy particles and lauryl sodium sulfate are mixed, and the obtained hard alloy particles with negative surfaces are dispersed in water to obtain a dispersion liquid of the hard alloy particles with negative surfaces.

In the present invention, the particle size of the cemented carbide particles is preferably 0.05 to 2 μm, more preferably 0.05 to 1 μm, and still more preferably 0.05 to 0.5 μm.

In the invention, the mass ratio of the hard alloy particles to the Sodium Dodecyl Sulfate (SDS) is preferably (1-10): 1, more preferably (5 to 10): 1. in the present invention, the sodium lauryl sulfate is preferably used in the form of a sodium lauryl sulfate alcohol solution; the mass percentage concentration of the sodium dodecyl sulfate in the sodium dodecyl sulfate alcohol solution is preferably 0.5-3%, and more preferably 0.6-2.5%. In the present invention, the mixing of the cemented carbide particles and sodium lauryl sulfate is preferably stirring, more preferably magnetic stirring; the stirring rate is not particularly limited in the present invention, and may be any rate known to those skilled in the art; the stirring time is preferably 1-3 h, and more preferably 1.5-2.5 h.

According to the invention, graphene and hexadecyl trimethyl ammonium bromide are mixed, and the obtained graphene with a positively charged surface is dispersed in water to obtain a positively charged graphene dispersion liquid.

In the invention, the average sheet diameter of the graphene is preferably 1-15 μm, and more preferably 1.5-10 μm; the number of layers is preferably 1 to 100.

In the invention, the mass ratio of the graphene to the hexadecyl trimethyl ammonium bromide is preferably (1-10): 1, more preferably (1-5): 1. in the present invention, the cetyltrimethylammonium bromide is preferably used in the form of a cetyltrimethylammonium bromide alcohol solution; the mass percentage concentration of the cetyl trimethyl ammonium bromide in the cetyl trimethyl ammonium bromide alcohol solution is preferably 0.02-1.5%, and more preferably 0.1-1.3%. In the invention, the mixing of the graphene and the hexadecyl trimethyl ammonium bromide is preferably stirring, and more preferably magnetic stirring; the stirring speed is not particularly limited in the invention, and the speed known to those skilled in the art can be adopted; the stirring time is preferably 1-3 h, and more preferably 1.5-2.5 h.

After the negative-charged hard alloy particle dispersion liquid and the positive-charged graphene dispersion liquid are obtained, the negative-charged hard alloy particle dispersion liquid and the positive-charged graphene dispersion liquid are mixed for electrostatic adsorption, and the reinforcing phase of the graphene-coated hard alloy particles is obtained.

In the present invention, the mixing of the negatively charged cemented carbide particle dispersion liquid and the positively charged graphene dispersion liquid is preferably performed by adding the positively charged graphene dispersion liquid to the negatively charged cemented carbide particle dispersion liquid. In the present invention, the method of mixing the negatively charged hard alloy particle dispersion liquid and the positively charged graphene dispersion liquid is preferably stirring; the stirring time is preferably 1-3 h, and more preferably 1-2 h; the stirring rate is not particularly limited in the present invention, and may be a stirring rate well known to those skilled in the art. According to the invention, the graphene-coated negatively-charged hard alloy particles form a reinforcing phase by stirring.

In the invention, the time of electrostatic adsorption is preferably 0.5-1 h. In the present invention, the electrostatic adsorption is preferably performed under stirring.

After the reinforcement is obtained, the reinforcement phase and the hard alloy matrix are mixed and sintered to obtain the graphene reinforced metal composite material.

In the invention, when the metal matrix is a hard alloy, the size of the metal matrix is preferably 0.5-10 μm, more preferably 0.8-8 μm, and still more preferably 1-5 μm. In the present invention, when the metal matrix is a cemented carbide, the chemical composition of the cemented carbide is a hard phase and a binder phase. In the present invention, the hard phase preferably comprises tungsten carbide; the binder phase preferably comprises cobalt. In the invention, the mass ratio of tungsten carbide to cobalt in the hard alloy is preferably (8-9): 1, more preferably (8.3 to 8.9): 1.

in the present invention, when the metal matrix is a cemented carbide, the sintering is preferably: and heating from room temperature to the I-th temperature at the I-th heating rate, preserving heat, cooling to the I-th cooling temperature at the I-th cooling rate after heat preservation, and cooling along with the furnace.

In the invention, the temperature rise rate I is preferably 7-10 ℃/min, and more preferably 8-9 ℃/min; the temperature of the first stage is preferably 1400-1460 ℃, and more preferably 1410-1450 ℃; the heat preservation time is preferably 1.5-2.5 h, and more preferably 1.6-2.4 h; the first cooling rate is preferably 7-10 ℃/min, and more preferably 8-9 ℃/min; the temperature of the first cooling temperature is 100-200 ℃, and more preferably 110-200 ℃.

In the invention, when the metal matrix is hard alloy, the sintering is carried out under the condition of pressure maintaining; the pressure for maintaining the pressure is preferably 20-50 MPa. In the invention, when the metal matrix is hard alloy, the sintering is carried out under the condition of protective gas; the protective gas is argon.

When the metal matrix is a hard alloy, the present invention preferably further comprises: releasing gas every 30min in the process of raising the temperature of the chamber to the temperature I; or releasing gas from the furnace top when the pressure in the chamber of the sintering equipment reaches 0.02MPa, and discharging impurity gas released by CTAB pyrolysis and graphene oxide reduction in the powder sintering process.

When the alloy matrix is made of hard alloy, the graphene reinforced metal composite material is shaped by sintering.

The invention also provides an application of the graphene reinforced metal composite material in the technical scheme or the graphene reinforced metal composite material prepared by the preparation method in the technical scheme.

In the present invention, when the alloy substrate is copper, the application is in electronic packaging, electrical switches and integrated circuits.

In the present invention, when the metal substrate is a cemented carbide, the application is in cutting tools, bearings, drilling tools, wire drawing dies, mining machinery and structural parts.

In order to further illustrate the present invention, the following describes a graphene reinforced metal composite material, a preparation method and applications thereof in detail with reference to examples, but they should not be construed as limiting the scope of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Mixing and stirring copper particles with the particle size of 0.7-1.2 mu m and an alcohol solution of cetyl trimethyl ammonium bromide for 2 hours, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particles with positive electricity on the surface; 24.975g of the copper particles with positively charged surfaces are dispersed in alcohol and stirred for 0.5h to obtain alcohol dispersion liquid of the copper particles with positive charges; placing 50mg of graphene oxide in deionized water, and ultrasonically stripping for 2 hours to obtain a graphene oxide aqueous dispersion; adding the graphene oxide aqueous dispersion into the positively charged copper particle alcohol dispersion, keeping stirring for 1h, and performing electrostatic adsorption to obtain a graphene oxide coated copper particle enhanced phase precursor;

dispersing the obtained enhanced phase precursor in water, mixing and stirring the obtained enhanced phase precursor water dispersion liquid and 24.975g of copper matrix powder with the particle size of 10-15 mu m for 1h, and drying the solid matter at 50 ℃ after suction filtration to obtain enhanced phase precursor-alloy matrix powder;

placing the obtained reinforcement precursor-metal matrix powder in a graphite mold, then placing the graphite mold in a vacuum autoclave cavity, vacuumizing the vacuum autoclave cavity until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow rate of 10L/min until the pressure in the cavity reaches 0.02MPa, stopping introducing argon, repeatedly vacuumizing and introducing argon for 3 times, heating from room temperature to 900 ℃ at the speed of 10 ℃/min, preserving heat for 1h, releasing primary gas from the furnace top when the pressure in the chamber reaches 0.02MPa in the heating process, discharging impurity gas released by CTAB pyrolysis and graphene oxide reduction in the powder sintering process, cooling to 200 ℃ at the cooling speed of 10 ℃/min after heat preservation is finished, and then cooling to room temperature along with the furnace, and keeping applying 40MPa of pressure to the graphite mold in the whole sintering process to obtain the graphene reinforced metal composite material.

Example 2

Mixing and stirring copper particles with the particle size of 0.7-1.2 mu m and an alcohol solution of cetyl trimethyl ammonium bromide for 2 hours, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particles with positive electricity on the surface; 24.925g of the copper particles with positively charged surfaces are dispersed in alcohol and stirred for 0.5h to obtain alcohol dispersion liquid of the copper particles with positively charged surfaces; placing 150mg of graphene oxide in deionized water, and ultrasonically stripping for 2 hours to obtain a graphene oxide aqueous dispersion; adding the graphene oxide aqueous dispersion into the positively charged copper particle alcohol dispersion, keeping stirring for 1h, and performing electrostatic adsorption to obtain a graphene oxide coated copper particle enhanced phase precursor;

dispersing the obtained enhanced phase precursor in water, mixing and stirring the obtained enhanced phase precursor water dispersion liquid and 24.925g of copper matrix powder with the particle size of 10-15 mu m for 1h, and drying the solid matter at 50 ℃ after suction filtration to obtain enhanced phase precursor-alloy matrix powder;

placing the obtained reinforcement precursor-metal matrix powder in a graphite mold, then placing the graphite mold in a vacuum autoclave cavity, vacuumizing the vacuum autoclave cavity until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow rate of 10L/min until the pressure in the cavity reaches 0.02MPa, stopping introducing argon, repeatedly vacuumizing and introducing argon for 3 times, heating the mixture from room temperature to 900 ℃ at the speed of 10 ℃/min, preserving heat for 1h, releasing primary gas from the furnace top when the pressure in the chamber reaches 0.02MPa in the heating process, discharging impurity gas released by CTAB pyrolysis and graphene oxide reduction in the powder sintering process, cooling to 200 ℃ at the cooling speed of 10 ℃/min after heat preservation is finished, and then cooling to room temperature along with the furnace, and keeping applying 40MPa of pressure to the graphite mold in the whole sintering process to obtain the graphene reinforced metal composite material.

Example 3

Mixing and stirring copper particles with the particle size of 0.7-1.2 mu m and an alcohol solution of cetyl trimethyl ammonium bromide for 2 hours, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particles with positive electricity on the surface; 24.875g of the copper particles with positively charged surfaces are dispersed in alcohol and stirred for 0.5h to obtain alcohol dispersion liquid of the copper particles with positively charged surfaces; placing 250mg of graphene oxide in deionized water, and ultrasonically stripping for 2 hours to obtain a graphene oxide aqueous dispersion; adding the graphene oxide aqueous dispersion into the positively charged copper particle alcohol dispersion, keeping stirring for 1h, and performing electrostatic adsorption to obtain a graphene oxide coated copper particle enhanced phase precursor;

dispersing the obtained enhanced phase precursor in water, mixing and stirring the obtained enhanced phase precursor water dispersion liquid and 24.875g of copper matrix powder with the particle size of 10-15 mu m for 1h, and drying the solid matter at 50 ℃ after suction filtration to obtain enhanced phase precursor-alloy matrix powder;

Comparative example 1

Mixing and stirring copper particles with the particle size of 0.1-1 mu m and an alcohol solution of cetyl trimethyl ammonium bromide for 2 hours, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particles with positive electricity on the surface; dispersing 49.95g of the copper particles with the positively charged surfaces in alcohol, and stirring for 0.5h to obtain a positively charged copper alcohol dispersion liquid; placing 50mg of graphene oxide in deionized water, and ultrasonically stripping for 2 hours to obtain a graphene oxide aqueous dispersion; adding the graphene oxide aqueous dispersion into the positively charged copper alcohol dispersion, and keeping stirring for 1h to obtain enhanced phase precursor-copper powder;

placing the obtained enhanced phase precursor-copper powder in a graphite mold, then placing the graphite mold in a vacuum hot-pressing furnace chamber, vacuumizing the vacuum hot-pressing furnace chamber until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow rate of 10L/min, stopping introducing argon until the pressure in the chamber reaches 0.02MPa, repeating vacuumizing and introducing argon for 3 times, heating the chamber to 900 ℃ from the room temperature at the speed of 10 ℃/min, keeping the temperature for 1h, releasing gas from the furnace top when the pressure in the chamber reaches 0.02MPa in the heating process, discharging impurity gas released by CTAB pyrolysis and graphene oxide reduction in the powder sintering process, cooling the chamber to 200 ℃ at the cooling speed of 10 ℃/min after the heat preservation is finished, then cooling the chamber to the room temperature, and keeping the pressure of 40MPa on the graphite mold in the whole sintering process to obtain the graphene enhanced copper-based material.

Comparative example 2

Mixing and stirring copper particles with the particle size of 0.1-1 mu m and an alcohol solution of hexadecyl trimethyl ammonium bromide for 2 hours, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particles with positive electricity on the surface; dispersing 49.85g of the copper particles with the positively charged surfaces in alcohol, and stirring for 0.5h to obtain a positively charged copper alcohol dispersion liquid; placing 150mg of graphene oxide in deionized water, and ultrasonically stripping for 2 hours to obtain a graphene oxide aqueous dispersion; adding the graphene oxide aqueous dispersion into the positively charged copper alcohol dispersion, and keeping stirring for 1h to obtain enhanced phase precursor-copper powder;

Comparative example 3

Mixing and stirring copper particles with the particle size of 0.1-1 mu m and an alcohol solution of hexadecyl trimethyl ammonium bromide for 2 hours, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particles with positive electricity on the surface; dispersing 49.75g of the copper particles with the positively charged surfaces in alcohol, and stirring for 0.5h to obtain a positively charged copper alcohol dispersion liquid; placing 250mg of graphene oxide in deionized water, and ultrasonically stripping for 2 hours to obtain a graphene oxide aqueous dispersion; adding the graphene oxide aqueous dispersion into the positively charged copper alcohol dispersion, and keeping stirring for 1h to obtain enhanced phase precursor-copper powder;

placing the obtained enhanced phase precursor-copper powder in a graphite mold, then placing the graphite mold in a vacuum hot-pressing furnace chamber, vacuumizing the vacuum hot-pressing furnace chamber until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow of 10L/min, stopping introducing argon until the pressure in the chamber reaches 0.02MPa, repeating vacuumizing and introducing argon for 3 times, heating from the room temperature to 900 ℃ at the speed of 10 ℃/min, keeping the temperature for 1h, releasing gas from the furnace top when the pressure in the chamber reaches 0.02MPa in the heating process, discharging impurity gas released by CTAB pyrolysis and graphene oxide reduction in the powder sintering process, cooling to 200 ℃ at the cooling rate of 10 ℃/min after keeping the temperature, then cooling to the room temperature along with the furnace, and keeping the pressure of 40MPa on the graphite mold in the whole sintering process to obtain the graphene reinforced copper-based material.

Comparative example 4

Dispersing 25g of copper particles with the particle size of 0.7-1.2 mu m in alcohol, and keeping stirring for 0.5h to obtain copper particle dispersion liquid; adding 25g of copper matrix powder with the particle size of 10-15 mu m into the obtained copper particle dispersion liquid, stirring for 1h, and drying the obtained solid substance at 50 ℃ after suction filtration to obtain copper particle-copper powder;

placing the obtained copper particles-copper powder in a graphite mold, then placing the graphite mold in a vacuum hot-pressing furnace chamber, vacuumizing the vacuum hot-pressing furnace chamber until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow rate of 10L/min, stopping introducing argon until the pressure in the chamber reaches 0.02MPa, repeating vacuumizing and introducing argon for 3 times, heating from the room temperature to 900 ℃ at the speed of 10 ℃/min, keeping the temperature for 1h, cooling to 200 ℃ at the cooling rate of 10 ℃/min after the heat preservation is finished, then cooling to the room temperature along with the furnace, and keeping the pressure of 40MPa on the graphite mold in the whole sintering process to obtain the copper-based material.

Comparative example 5

Pure copper.

The atomic force microscopy test is performed on the graphene oxide, and the obtained AFM test result is shown in fig. 1 and fig. 2, wherein fig. 1 is an AFM image of the graphene oxide, and fig. 2 is a thickness diagram of a white line part in fig. 1. As can be seen from FIGS. 1 and 2, the graphene oxide sheet layer is transparent like a gauze, and the sheet diameter is 2-5 μm.

Scanning electron microscope tests were performed on graphene oxide, copper matrix powder, copper particles, the copper-based material in comparative example 1, and the graphene-reinforced metal composite material obtained in example 1, and the obtained SEM image is shown in fig. 3, (a) is graphene oxide, (b) is copper matrix powder, (c) is copper particles, (d) is the copper-based material in comparative example 1, (e) is the graphene-reinforced metal composite material obtained in example 1, and (f) is a partial enlarged view of (e). As can be seen from fig. 3, the graphene oxide sheets are transparent like a gauze; the Cu is in an irregular stacked tree shape and has a uniform size; the appearance of the copper particles is regular spherical, and no obvious agglomeration tendency exists; in the comparative example 1, graphene in the copper-based material is not shrunk to be a coating structure, but is embedded and stacked on the surface of copper matrix powder in a sheet mode to form a graphene oxide-copper powder aggregate, so that air holes and defects are easily formed in the sintering process; graphene oxide and copper particles in the graphene reinforced metal composite material obtained in the embodiment 1 form an effective coating structure, the graphene oxide is coated on the copper particles in a shrinkage shape, no large graphene oxide is scattered and accumulated on the graphene reinforced metal composite material, and meanwhile, the reinforcing phase precursor coating small balls are uniformly dispersed in gaps of large-size copper matrix powder, so that the uniform dispersion of the graphene oxide is promoted, sintering gaps are filled in the sintering process, and the sintering density of the graphene reinforced metal composite material is improved.

The metallic materials of examples 1 to 3 and comparative examples 1 to 4 were subjected to a performance test in which,

the density is tested by adopting an Archimedes drainage method; hardness test is HV_0.1(ii) a The tensile property test adopts a non-national standard sample, the size diagram of the sample is shown in figure 4, the parameter unit in figure 4 is mm, and the thickness is 1.2 mm; the product of strength and elongation is the product of tensile strength and elongation; the conductivity adopts an eddy current method; the test results are shown in Table 1.

TABLE 1 Performance test of examples 1-3 and comparative examples 1-4

According to table 1, curves of density, hardness and conductivity of the material under different graphene content conditions are drawn, see fig. 5-7, fig. 5 is a graph of density change of the material under different graphene content conditions, fig. 6 is a graph of hardness change of the material under different graphene content conditions, and fig. 7 is a graph of conductivity of the material under different graphene content conditions; in FIGS. 5-7, rGO/Cu is the comparative example and SSCu @ rGO/Cu is the example. As can be seen from fig. 5 to 7, the performances of the graphene reinforced copper composite materials obtained in comparative examples 1 to 4 (comparative example 4 is a copper composite material with a graphene content of 0) basically show a decreasing trend with the increase of the graphene content, and the decreasing degree is large. Different from the variation trend of the graphene reinforced copper composite materials of comparative examples 1 to 4, the density of the graphene reinforced metal composite materials provided by examples 1 to 3 is higher than that of pure Cu, and other properties are increased and then decreased, and are basically at the same level as that of the pure Cu after being decreased to the lowest.

Example 4

34.895g of hard alloy particles with the particle size of 0.05-0.5 mu m and 1 wt.% of sodium dodecyl sulfate solution are mixed and stirred for 2 hours to obtain negative-charged hard alloy particle dispersion liquid; mixing 210mg of graphene and hexadecyl trimethyl ammonium bromide, and dispersing the obtained graphene with positively charged surfaces in water to obtain a positively charged graphene dispersion liquid; adding the positively charged graphene dispersion liquid into the negatively charged hard alloy particle dispersion liquid, mixing and stirring for 2 hours, performing electrostatic adsorption, performing suction filtration, and drying the obtained solid substance at 50 ℃ to obtain a reinforcing phase of the graphene-coated hard alloy particles;

mixing the obtained reinforcement phase with 34.895g of hard alloy matrix powder with the particle size of 1-5 mu m to obtain reinforcement precursor-alloy matrix powder;

placing the obtained reinforcement-metal matrix powder in a graphite mold, then placing the graphite mold in a vacuum hot-pressing furnace chamber, vacuumizing the vacuum hot-pressing furnace chamber until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow rate of 10L/min, stopping introducing argon until the pressure in the chamber reaches 0.02MPa, repeating vacuumizing and introducing argon for 3 times, heating the graphite mold from the room temperature to 1430 ℃ at the speed of 10 ℃/min, preserving the temperature for 100min, releasing gas once when the pressure in the chamber reaches 0.02MPa in the heating process, cooling the graphite mold to 200 ℃ at the cooling rate of 10 ℃/min after preserving the temperature, then cooling the graphite mold to the room temperature along with the furnace, and keeping the pressure of 30MPa applied to the graphite mold in the whole sintering process to obtain the graphene reinforced metal composite material.

Example 5

34.965g of hard alloy particles with the particle size of 0.05-0.5 mu m and 1 wt.% of sodium dodecyl sulfate solution are mixed and stirred for 2 hours to obtain negative-charged hard alloy particle dispersion liquid; mixing 70mg of graphene and hexadecyl trimethyl ammonium bromide, and dispersing the obtained graphene with the positively charged surface in water to obtain a positively charged graphene dispersion liquid; adding the positively charged graphene dispersion liquid into the negatively charged hard alloy particle dispersion liquid, mixing and stirring for 2 hours, performing electrostatic adsorption, performing suction filtration, and drying the obtained solid substance at 50 ℃ to obtain a reinforcing phase of the graphene-coated hard alloy particles;

mixing the obtained reinforcement phase with 34.965g of hard alloy matrix powder with the particle size of 1-5 mu m to obtain reinforcement precursor-alloy matrix powder;

Example 6

34.825g of hard alloy particles with the particle size of 0.05-0.5 mu m and 1 wt.% of sodium dodecyl sulfate solution are mixed and stirred for 2 hours to obtain negative-charged hard alloy particle dispersion liquid; mixing 350mg of graphene and hexadecyl trimethyl ammonium bromide, and dispersing the obtained graphene with the positively charged surface in water to obtain a positively charged graphene dispersion liquid; adding the positively charged graphene dispersion liquid into the negatively charged hard alloy particle dispersion liquid, mixing and stirring for 2 hours, performing electrostatic adsorption, performing suction filtration, and drying the obtained solid substance at 50 ℃ to obtain a reinforcing phase of the graphene-coated hard alloy particles;

mixing the obtained reinforcement phase with 34.825g of hard alloy matrix powder with the particle size of 1-5 mu m to obtain reinforcement precursor-alloy matrix powder;

Comparative example 6

Mixing 69.79g of hard alloy particles with the particle size of 0.05-0.5 mu m and 1 wt.% of lauryl sodium sulfate solution, stirring for 2 hours to obtain a negative-charged hard alloy particle dispersion liquid, mixing 210mg of graphene and hexadecyl trimethyl ammonium bromide, and dispersing the obtained graphene with the positive surface in water to obtain a positive-charged graphene dispersion liquid; adding the positively charged graphene dispersion liquid into the negatively charged micron hard alloy particle dispersion liquid, mixing and stirring for 2 hours, performing electrostatic adsorption, performing suction filtration, and drying the obtained solid substance at 50 ℃ to obtain graphene-hard alloy particles;

placing the obtained graphene-hard alloy particles in a graphite mold, then placing the graphite mold in a vacuum hot-pressing furnace chamber, vacuumizing the vacuum hot-pressing furnace chamber until the vacuum degree is less than or equal to 20Pa, starting to introduce argon from the bottom of the furnace body at the flow rate of 10L/min, stopping introducing the argon until the pressure in the chamber reaches 0.02MPa, repeating vacuumizing and introducing the argon for 3 times, heating the graphite mold from the room temperature to 1430 ℃ at the speed of 10 ℃/min, preserving the temperature for 100min, releasing primary gas when the pressure in the chamber reaches 0.02MPa in the heating process, cooling the graphite mold to 200 ℃ at the cooling speed of 10 ℃/min after preserving the temperature, then cooling the graphite mold to the room temperature along with the furnace, and keeping the pressure of 30MPa applied to the graphite mold in the whole sintering process to obtain the graphene reinforced metal composite material.

Comparative example 7

34.895g of hard alloy particles with the particle size of 0.05-0.5 mu m and 1 wt.% of hexadecyl trimethyl ammonium bromide are mixed and stirred for 2 hours to obtain positively charged hard alloy particle dispersion liquid, and 210mg of graphene oxide is ultrasonically stripped in deionized water for 2 hours to obtain graphene oxide dispersion liquid; adding the graphene oxide dispersion liquid into the positively charged hard alloy particle dispersion liquid, mixing and stirring for 2h, performing electrostatic adsorption, performing suction filtration, and drying the obtained solid substance at 50 ℃ to obtain a reinforcing phase of the graphene-coated hard alloy particles;

Scanning electron microscope tests are carried out on the graphene reinforced metal composite materials obtained in example 4 and comparative examples 6-7, and the obtained SEM images are shown in figures 8-10, wherein figure 8 is the SEM image of the graphene reinforced metal composite material obtained in example 4, figure 9 is the SEM image of the graphene reinforced metal composite material obtained in comparative example 6, and figure 10 is the SEM image of the graphene reinforced metal composite material obtained in comparative example 7. As can be seen from fig. 8, the graphene-coated cemented carbide powder reinforced phase in the graphene reinforced metal composite material obtained in example 4 has a good structure, the graphene is not agglomerated, and the dispersion is very uniform; as can be seen from fig. 9, in the graphene reinforced metal composite material obtained in comparative example 6, the size of graphene is smaller than that of the micron hard alloy particles, and the graphene is spread and dispersed among the hard alloy powders; as can be seen from fig. 10, the graphene size in the graphene reinforced metal composite material obtained in comparative example 7 is 2 to 5 μm, which is much larger than that of the hard alloy particles, and only a few hard alloy particles are coated in the middle of the graphene.

The hardness of the graphene reinforced metal composite materials obtained in examples 4 to 6 and comparative examples 6 to 7 was tested by a microhardness machine under a load of 1KG, and the following results were obtained: the hardness of the graphene reinforced metal composite materials obtained in examples 4 to 6 and comparative examples 6 to 7 was 1882HV, 1703HV, 1782HV, 1482HV and 1665HV, respectively. The hardness graph is plotted against hardness as shown in figure 11. As can be seen from fig. 11, the graphene reinforced metal composite provided by the embodiment of the invention has high hardness.

The friction coefficients of the graphene reinforced metal composite materials obtained in the example 4 and the comparative examples 6 to 7 are tested, and the test method comprises the following steps: under the condition of dry friction, a silicon nitride friction pair is adopted, the load is 80N, the time is 30min, and the stroke is 5 mm. The test results are shown in FIG. 12. As can be seen from fig. 12, the friction coefficient of the cemented carbide powder and the graphene is the highest, and the friction coefficient of the cemented carbide coated with 0.3% of the graphene and the cemented carbide is the lowest, because the graphene can be used as a lubricating phase to reduce the friction force, and the size of the abrasive grains formed after the cemented carbide is separated from the matrix is small.

The wear marks of the graphene reinforced metal composite materials obtained in the examples 4-6 and the comparative examples 6-7 are tested, and the test method comprises the following steps: laser confocal microscopy. The test results are shown in fig. 13, and fig. 13 shows that the hard alloy powder in the comparative example 7 has smaller abrasive grains than that in the comparative example 6 after being removed from the grinding marks during the frictional wear process after being sintered, so that the friction coefficient is reduced, but the cobalt phase is more uniformly distributed and thinner after being sintered, and is more easily removed than that in the comparative example 6, but the hardness of the comparative example 7 is higher due to the finer tungsten carbide grains, and the wear amount is not much different from that of the comparative example 6 due to the combination of the two factors. The graphene in examples 4 to 6 is much smaller than the sintered reduced graphene oxide in comparative example 7, the coating structure enables the graphene to be dispersed more uniformly, the addition of the hard receiving powder enables the grain size of tungsten carbide to be smaller than that of the embodiment, and the graphene reinforced metal composite material obtained in example 4 has the lowest friction coefficient and the lowest abrasion loss.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A graphene reinforced metal composite material comprises a metal matrix and a reinforcing phase; the reinforcing phase comprises a graphene outer shell and metal particles within the graphene outer shell; the metal matrix is copper or hard alloy; the metal matrix and the metal particles are made of the same material;

the content of graphene in the graphene reinforced metal composite material is 0.1-0.3 wt.%;

the preparation method of the graphene reinforced metal composite material comprises the following steps:

when the metal matrix is copper, the method comprises the following steps:

when the metal matrix is hard alloy, the method comprises the following steps:

mixing positively charged graphene and negatively charged hard alloy particles, and performing electrostatic adsorption on the graphene and the hard alloy particles to form a reinforced phase;

2. The graphene-reinforced metal composite according to claim 1, wherein the content of the metal particles in the graphene-reinforced metal composite is 10 to 50 wt.%.

3. The graphene-reinforced metal composite according to claim 1, wherein the reinforcing phase has a size of 0.05 to 15 μm, and the metal matrix has a size of 0.5 to 20 μm.

4. The method for preparing the graphene reinforced metal composite material as claimed in any one of claims 1 to 3, wherein when the metal matrix is copper, the method comprises the following steps:

when the metal matrix is hard alloy, the method comprises the following steps:

5. The production method according to claim 4, wherein when the metal substrate is copper, the oppositely charged graphene oxide and copper particles are negatively charged graphene oxide and positively charged copper particles, respectively;

6. The method according to claim 4, wherein when the metal substrate is a cemented carbide, the positively charged graphene is cetyltrimethylammonium bromide modified graphene; the hard alloy particles with negative electricity are sodium dodecyl sulfate modified hard alloy particles.

7. The method according to claim 4, wherein when the metal matrix is copper, the size of the copper particles is 0.5 to 2 μm, and the size of the copper matrix is 5 to 20 μm; when the metal matrix is made of hard alloy, the size of the hard alloy particles is 0.05-2 mu m, and the size of the hard alloy matrix is 0.5-10 mu m.

8. The method according to claim 4, wherein when the metal matrix is copper, the sintering is: heating from room temperature to a first temperature at a first heating rate, preserving heat, cooling to a first cooling temperature at a first cooling rate after heat preservation, and cooling along with a furnace;

the first heating rate is 7-10 ℃/min, the first temperature is 850-920 ℃, and the heat preservation time is 1-1.5 h;

the first cooling rate is 7-10 ℃/min, and the first cooling temperature is 100-200 ℃;

9. The application of the graphene reinforced metal composite material of any one of claims 1 to 3 or the graphene reinforced metal composite material obtained by the preparation method of any one of claims 4 to 8, wherein when the metal matrix is copper, the application is in electronic packaging, electrical switches and integrated circuits;