1. A preparation method of a graphene quantum dot reinforced aluminum matrix composite is characterized by comprising the following steps: the method comprises the steps of taking commercially available graphene oxide as a raw material, preparing three-dimensional network graphene through a hydrothermal reaction, etching by nitric acid, evaporating, neutralizing and drying to obtain the light brown graphene quantum dot.

2. The preparation method of the graphene quantum dot material according to claim 1, wherein: the two-step method for preparing the graphene quantum dots comprises the steps of firstly preparing graphene oxide into three-dimensional network graphene and then preparing the graphene quantum dots.

3. The method for preparing three-dimensional network graphene according to claims 1 and 2, wherein: mixing commercially available graphene oxide and ultrapure water according to the proportion of 0.5-2.0 mg/mL, ultrasonically dispersing for 20-50 min, and then adding a pH regulator ammonia water (accounting for 3-5% of the volume fraction) and a reducing agent hydrazine hydrate (accounting for 2-4% of the volume fraction). And transferring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and keeping the temperature of 180-200 ℃ for 9-12 hours to obtain the three-dimensional network graphene.

4. The preparation method of the graphene quantum dot material according to claims 1 and 2, characterized in that: etching the three-dimensional network graphene for 20-24 hours at 150-170 ℃ by concentrated nitric acid; continuing heating at 150-170 ℃ for 10-30 min to volatilize the concentrated nitric acid; and finally neutralizing and drying to obtain the graphene quantum dot reinforced material.

5. The preparation method of the graphene quantum dot reinforced aluminum matrix composite is characterized by comprising the following steps: the self-made graphene quantum dot is used as a reinforcing material, Al powder is used as a matrix material, and an ethanol phase stirring evaporation mixing method and a discharge plasma sintering technology are adopted to prepare the graphene quantum dot reinforced aluminum matrix composite.

6. The preparation method of the graphene quantum dot reinforced aluminum matrix composite material according to claim 5, characterized by comprising the following steps: preparing a GQD reinforcing material into 0.5-5.0 g/L alcoholic solution, then adding industrial Al powder, heating and stirring at 60-80 ℃, and evaporating an ethanol solvent for 3-6 hours to obtain a mixed solid; wherein the mass fraction of GQDs is 0.2-5%.

7. The preparation method of the graphene quantum dot reinforced aluminum matrix composite material according to claim 5, characterized by comprising the following steps: the parameters of the table type discharge plasma sintering furnace are that under a vacuum environment, the temperature is 550-650 ℃, the heating rate is 100-150 ℃/min, the heat preservation time is 5-10 min, and axial pressure of 30-40 MPa is applied during sintering.

8. The preparation method of the graphene quantum dot reinforced aluminum matrix composite material according to claim 5, characterized by comprising the following steps: and after sintering, naturally cooling for 2-4 h under a vacuum condition.

9. The graphene quantum dot reinforced aluminum matrix composite material obtained by the synthesis method of any one of claims 1 to 8, which is characterized in that: the tensile strength of the material is 235-296 Mpa.

10. The graphene quantum dot reinforced aluminum matrix composite material of claim 9, which is applied to the fields of transportation, electronic manufacturing and architectural decoration.

Background

In recent years, the conventional aluminum alloy material has been replaced by advanced materials such as graphene reinforced Aluminum Matrix Composite (AMC), mainly because AMC has a series of excellent physical and mechanical properties. As a gainCommon additives for the strong phase include ceramic reinforcements, such as B₄C. SiC and Al₂O₃And the like. Nowadays, many new reinforcing additives, such as carbon nanotubes and graphene, are emerging in the form of new carbon nanomaterials. Among them, graphene has characteristics of large specific surface area, high young's modulus, excellent electrical and thermal conductivity, and the like, and is considered as one of ideal reinforcing materials for aluminum matrix composites. However, due to van der waals force between graphene nanosheets and high surface area and surface energy, graphene is easy to agglomerate, so that dispersibility is poor, and the agglomerated graphene can serve as a crack initiation point, so that strength of the composite material is reduced. In addition, the strength and the plasticity of the aluminum matrix composite are related to the size of the reinforcing material, and the smaller the size of the reinforcing material is, the more obvious the reinforcing effect is. The graphene with certain structural rigidity is difficult to be decomposed into small blocks and is difficult to be uniformly dispersed on the surface of aluminum powder.

As a member of the Graphene material family, Graphene Quantum Dots (GQDs) are a novel carbon nanomaterial having a lateral dimension of less than 10nm and having 10 or fewer Graphene segments. Since the graphene quantum dots are miniature graphene segments, the electron motion of the graphene quantum dots is restricted in three spatial dimensions. Therefore, compared with a one-dimensional graphene sheet and a two-dimensional graphene band, the zero-dimensional GQDs have more obvious quantum confinement effect and sideband effect due to the size, so that the graphene quantum dots have more emerging chemical and physical properties. In short, the small size and easy dispersion of GQDs make them ideal reinforcing materials for aluminum matrix composites.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a method for preparing a graphene quantum dot reinforced aluminum matrix composite, wherein a self-made GQDs is used as a reinforcing material, an Al powder is used as a base material, and heating, stirring, evaporation, powder mixing and spark plasma sintering are employed to prepare the GQDs reinforced aluminum matrix composite. The second purpose of the invention is to provide the graphene quantum dot reinforced aluminum matrix composite material prepared by the method, and the material has good mechanical property and chemical stability. The invention also aims to provide application of the graphene quantum dot reinforced aluminum-based composite material in the field of composite materials, including but not limited to the fields of transportation and architectural decoration.

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

1. preparing graphene quantum dots: (1) transferring a mixed solution of commercially available graphene oxide, ammonia water and hydrazine hydrate into a high-pressure reaction kettle with a polytetrafluoroethylene lining for hydrothermal reaction to prepare three-dimensional network graphene; (2) and adding concentrated nitric acid into the three-dimensional network graphene, then refluxing and heating, and after the reaction is finished, evaporating, neutralizing, filtering and the like to obtain the light brown graphene quantum dots.

Preferably, the three-dimensional network-like graphene is prepared by the following method: mixing commercially available graphene oxide and ultrapure water according to the proportion of 0.5-2.0 mg/mL, ultrasonically dispersing for 20-50 min, and then adding a pH regulator ammonia water (accounting for 3-5% of the volume fraction) and a reducing agent hydrazine hydrate (accounting for 2-4% of the volume fraction). And transferring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and keeping the temperature of 180-200 ℃ for 9-12 hours to obtain the three-dimensional network graphene.

Preferably, the graphene quantum dot is prepared by the following method: weighing 0.01-0.05 g of three-dimensional network graphene, adding 10-20 mL of concentrated nitric acid, installing a spherical condensing device, keeping out of the sun, opening for ventilation, and carrying out oil bath at 150-170 ℃ for continuous stirring reaction for 20-24 h to obtain a light yellow graphene quantum dot dispersion liquid.

Preferably, the graphene quantum dots are purified by the following method: and after the reaction is finished, removing the condensing device, continuously heating the light yellow graphene quantum dot dispersion liquid at 150-170 ℃ for 10-30 min, evaporating the residual concentrated nitric acid, and cooling to obtain a crude graphene quantum dot product.

Preferably, the graphene quantum dots are refined by the following method: reformulating the crude product of the graphene quantum dots into an aqueous solution, and adjusting the pH value to be neutral by using NaOH; centrifuging for 5-10 min at 8000-10000 r/min by a centrifuge, and taking out the precipitate and drying.

Preferably, the drying is carried out in a blast drying oven at 70-90 ℃ for 4-8 h.

2. Dispersing GQDs reinforcing materials and Al powder with different mass ratios in a heating, stirring and evaporating mode; then, the mixed powder is filled into a cylindrical graphite die and placed in a table type discharge plasma sintering furnace for sintering; naturally cooling the graphite alkene carbon point reinforced aluminum matrix composite material in a vacuum environment.

Preferably, the mixed powder of the GQD reinforcing material and Al powder is prepared by the following method: preparing a GQD reinforcing material into 0.5-5.0 g/L alcoholic solution, then adding industrial Al powder, heating and stirring at 60-80 ℃, and evaporating an ethanol solvent for 3-6 hours to obtain a mixed solid; wherein the mass fraction of GQDs is 0.2-5%.

Preferably, the parameters of the table type discharge plasma sintering furnace are that under a vacuum environment, the temperature is 550-650 ℃, the heating rate is 100-150 ℃/min, the heat preservation time is 5-10 min, and axial pressure of 30-40 MPa is applied during sintering.

Preferably, after sintering, the graphene carbon-point reinforced aluminum-based material product with different properties can be obtained by natural cooling for 2-4 hours under the vacuum condition.

3. The tensile strength of the graphene carbon dot reinforced aluminum-based material obtained by the preparation method is 235-296 Mpa, and the tensile strength performance of the graphene carbon dot reinforced aluminum-based material is improved by 4.9-32.6% compared with that of a raw material Al

4. The graphene carbon-point reinforced aluminum-based composite material is applied to the fields of transportation, architectural decoration and the like.

The invention has the beneficial effects that: the invention discloses a graphene quantum dot reinforced aluminum matrix composite. The graphene quantum dots are small in size, strong in dispersity and high in strengthening efficiency, and the performance can be greatly improved only by adding graphene with the mass fraction of less than 1%. Compared with the traditional reinforcement material, the low-dimensional nano-scale reinforcement material has the remarkable advantages that: (1) the nano particle reinforced aluminum-based composite material not only has improved strength, but also keeps good toughness plasticity or high-speed superplasticity. The fatigue resistance and the service performance of the aluminum matrix composite material are obviously improved, and the plastic processing formability is also greatly improved; (2) the addition of the nano particles can effectively inhibit the growth of aluminum matrix grains in the preparation process, so that the composite material has fine structure and improved mechanical property; (3) the nano particles are small in size, so that the particles are not easy to break, the structural defects of the nano particles are fewer, and the periphery of the nano particles has higher thermal misfit dislocation density. Therefore, the graphene quantum dot reinforced aluminum-based composite material has high market competitiveness and has huge application potential in the fields of transportation, electronic manufacturing, architectural decoration and the like.

Drawings

In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:

fig. 1 is a TEM structural diagram of a graphene quantum dot.

Fig. 2 is a flow chart of a preparation process of the graphene quantum dot reinforced aluminum matrix composite.

Detailed Description

The present invention is further described with reference to the following drawings and specific examples so that those skilled in the art can better understand the present invention and can practice the present invention, but the examples are not intended to limit the present invention.

Example 1

1. Preparation of graphene quantum dots

(1) Commercially available graphene oxide and ultrapure water are mixed according to the proportion of 0.5mg/mL, and ammonia water (accounting for 3% of volume fraction) and hydrazine hydrate (accounting for 3% of volume fraction) are added after ultrasonic dispersion is carried out for 30min to prepare a mixed solution.

(2) And transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 10 hours in a forced air drying oven at 180 ℃ to obtain the three-dimensional network graphene.

(3) 0.02g of the three-dimensional network graphene is weighed, mixed with 10mL of concentrated nitric acid, heated and refluxed, and continuously stirred at 160 ℃ for reaction for 20 hours.

(4) After the reaction is finished, removing the reflux device, and continuously stirring and heating at 160 ℃ for 20min to volatilize the concentrated nitric acid, thereby obtaining the crude product of the graphene quantum dots.

(5) The graphene quantum dot crude product is reconstituted into an aqueous solution, and then the pH value is adjusted to be neutral by NaOH; centrifuging at 10000r/min for 5min, and drying the precipitate in a forced air drying oven at 90 deg.C for 4h to obtain the final product.

2. The graphene quantum dot reinforced aluminum matrix composite material comprises the following substances in parts by weight: 100g of industrial aluminum powder and 0.2g of GQDs, wherein the mass fraction of the reinforcing material of the GQDs is about 0.2 percent.

(1) The GQD reinforcing material is prepared into 1.0g/L alcoholic solution, and 200mL of the alcoholic solution is ultrasonically mixed with 100g of industrial aluminum powder.

(2) Heating and stirring the above liquid, and evaporating ethanol solvent at 70 deg.C to obtain dry mixed solid.

(3) And (3) putting the uniformly mixed powder into a graphite mould matched with a desk type discharge plasma sintering furnace, and sintering. The sintering process parameters are 550 ℃ in a vacuum environment, and the heating rate is 125 ℃ for min-¹Keeping the temperature for 8min, and applying axial pressure of 30MPa during sintering;

(4) and after the sintering process is finished, naturally cooling to obtain the graphene quantum dot reinforced aluminum matrix composite.

Example 2

1. Preparation of graphene quantum dots

(1) Commercially available graphene oxide and ultrapure water are mixed according to the proportion of 0.5mg/mL, and ammonia water (accounting for 3% of volume fraction) and hydrazine hydrate (accounting for 3% of volume fraction) are added after ultrasonic dispersion is carried out for 30min to prepare a mixed solution.

(2) And transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 10 hours in a forced air drying oven at 180 ℃ to obtain the three-dimensional network graphene.

(3) 0.02g of the three-dimensional network graphene is weighed, mixed with 10mL of concentrated nitric acid, heated and refluxed, and continuously stirred at 160 ℃ for reaction for 20 hours.

(4) After the reaction is finished, removing the reflux device, and continuously stirring and heating at 160 ℃ for 20min to volatilize the concentrated nitric acid, thereby obtaining the crude product of the graphene quantum dots.

(5) The graphene quantum dot crude product is reconstituted into an aqueous solution, and then the pH value is adjusted to be neutral by NaOH; centrifuging at 10000r/min for 5min, and drying the precipitate in a forced air drying oven at 90 deg.C for 4h to obtain the final product.

2. The graphene quantum dot reinforced aluminum matrix composite material comprises the following substances in parts by weight: 100g of industrial aluminum powder and 0.5g of GQDs, wherein the mass fraction of the reinforcing material of the GQDs is about 0.5 percent.

(1) The GQD reinforcing material is prepared into 2.5g/L alcoholic solution, and 200mL of the alcoholic solution is ultrasonically mixed with 100g of industrial aluminum powder.

(2) Heating and stirring the above liquid, and evaporating ethanol solvent at 70 deg.C to obtain dry mixed solid.

(3) And (3) putting the uniformly mixed powder into a graphite mould matched with a desk type discharge plasma sintering furnace, and sintering. The sintering process parameters are 550 ℃ in a vacuum environment, and the heating rate is 125 ℃ for min-¹Keeping the temperature for 8min, and applying axial pressure of 30MPa during sintering;

(4) and after the sintering process is finished, naturally cooling to obtain the graphene quantum dot reinforced aluminum matrix composite.

Example 3

1. Preparation of graphene quantum dots

(1) Commercially available graphene oxide and ultrapure water are mixed according to the proportion of 0.5mg/mL, and ammonia water (accounting for 3% of volume fraction) and hydrazine hydrate (accounting for 3% of volume fraction) are added after ultrasonic dispersion is carried out for 30min to prepare a mixed solution.

(2) And transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 10 hours in a forced air drying oven at 180 ℃ to obtain the three-dimensional network graphene.

(3) 0.02g of the three-dimensional network graphene is weighed, mixed with 10mL of concentrated nitric acid, heated and refluxed, and continuously stirred at 160 ℃ for reaction for 20 hours.

(4) After the reaction is finished, removing the reflux device, and continuously stirring and heating at 160 ℃ for 20min to volatilize the concentrated nitric acid, thereby obtaining the crude product of the graphene quantum dots.

(5) The graphene quantum dot crude product is reconstituted into an aqueous solution, and then the pH value is adjusted to be neutral by NaOH; centrifuging at 10000r/min for 5min, and drying the precipitate in a forced air drying oven at 90 deg.C for 4h to obtain the final product.

2. The graphene quantum dot reinforced aluminum matrix composite material comprises the following substances in parts by weight: 100g of industrial aluminum powder and 1.0g of GQDs, wherein the mass fraction of the reinforcing material of the GQDs is about 1.0 percent.

(1) The GQD reinforcing material is prepared into 5.0g/L alcoholic solution, and 200mL of the alcoholic solution is ultrasonically mixed with 100g of industrial aluminum powder.

(2) Heating and stirring the above liquid, and evaporating ethanol solvent at 70 deg.C to obtain dry mixed solid.

(3) And (3) putting the uniformly mixed powder into a graphite mould matched with a desk type discharge plasma sintering furnace, and sintering. The sintering process parameters are 550 ℃ in a vacuum environment, and the heating rate is 125 ℃ for min-¹Keeping the temperature for 8min, and applying axial pressure of 30MPa during sintering;

(4) and after the sintering process is finished, naturally cooling to obtain the graphene quantum dot reinforced aluminum matrix composite.

Comparative example 1

Compared with the embodiments 1 to 3, the difference is that no graphene quantum dot reinforcing material is added, namely only Al is added.

(1) And (3) putting the Al powder into a graphite die matched with a table type discharge plasma sintering furnace, and sintering. The sintering process parameters are 550 ℃ in a vacuum environment, and the heating rate is 125 ℃ for min-¹Keeping the temperature for 8min, and applying axial pressure of 30MPa during sintering;

(2) and after the sintering process is finished, naturally cooling to obtain the comparative Al material.

Then, the tensile strength of the products prepared in examples 1 to 3 and comparative example 1 was measured, and the results are shown in Table 1.

The tensile strengths of the products of Table 1, examples 1-3 and comparative example 1 are as follows:

the above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.