CN113073221B - Graphene modification method of metal - Google Patents

Abstract

The present invention provides a metal graphene modification method, which comprises the steps of: providing metal powder, graphene powder and an adhesive, wherein the metal powder includes a plurality of metal particles, the graphene powder includes a plurality of graphene microplatelets, and each graphene microplatelet Including connected several graphene molecules, each graphene molecule connects a stearic acid functional group with a mixed-layer orbital sp3 bond; the metal powder and the graphene powder adhesive are mixed and rubbed to generate heat so that each stearic acid functional group is connected. Each mixed-layer orbital sp3 bond is endothermic and then breaks, and each graphene molecule is bonded to other graphene molecules by the broken mixed-layer orbital sp3 bond, so that the graphene molecule coats each metal particle; sintering the metal particle makes the metal particle It is fused into a metal body and the graphene molecules form a three-dimensional network and are combined in the metal body.

Description

Graphene modification method of metal

technical field

The invention relates to a graphene metal composite material, in particular to a graphene modification method of a metal.

Background technique

At present, the preparation and application of silicon carbide and alumina reinforced copper matrix composites have become mature, but their comprehensive performance and actual needs are still a long way off, while graphene has excellent mechanical properties, thermal properties and electrical properties. One of the most ideal reinforcements for thermally conductive composites. However, the research on graphene-enhanced copper-aluminum matrix composites is still in its infancy, and related research work is urgently needed. How to uniformly disperse graphene into the copper-aluminum matrix and at the same time form a good contact interface between graphene and metal is a key problem in research.

Furthermore, in the existing modification technology, a tackifier is generally added to organic materials to increase the viscosity of the material to fix different organic materials; inorganic materials are generally ionic in solution and have broken bonds, so generally adding a thickener is added. Chain agent, fixing different inorganic materials by bonding. However, the properties of organic materials and inorganic materials are quite different, and there is currently no good fixing method between organic materials and inorganic materials. Therefore, organic graphene and inorganic metals are not easily combined uniformly.

In view of this, the inventor of the present invention has devoted himself to the study of the above-mentioned prior art and cooperated with the application of theories, trying his best to solve the above-mentioned problems, which is the goal of the present inventor's improvement.

SUMMARY OF THE INVENTION

The invention provides a graphene modification method of metal, which can evenly distribute graphene in metal.

The present invention provides a method for modifying metal graphene, which comprises the following steps: providing metal powder, graphene powder and an adhesive, wherein the metal powder includes a plurality of metal particles, the adhesive includes a wax material, and the graphene powder includes a plurality of graphene microplates , each graphene microplatelet comprises several graphene molecules that are connected, each graphene molecule comprises six carbon atoms connected in a ring, and one of the carbon atoms of each graphene molecule connects a stearic acid with a mixed-layer orbital sp3 bond Functional group, the adhesive comprises a coupling agent of 0.5-2% by weight and a dispersant of 5-20% by weight, the coupling agent is one of titanate and organic chromium complex, and the dispersant is methyl amyl alcohol , one of polyacrylamide and fatty acid polyethylene glycol ester; mix metal powder and graphene powder adhesive into a powder raw material, and mix and friction to generate heat to connect each mixed layer orbital sp3 of each stearic acid functional group After the bond absorbs heat, it is broken, and after the stearic acid functional group is separated from each graphene molecule, each graphene molecule is bonded to other graphene molecules by the broken mixed-layer orbital sp3 bond, so that the graphene molecule coats each metal particle; Sintering the metal particles makes the metal particles fuse into a metal body, and the graphene molecules form a three-dimensional network and are combined in the metal body.

In the graphene modification method of the present invention, the initial embryo comprises uniformly mixed metal particles and graphene micro-flakes, and each graphene micro-flake is coated with a solid adhesive to bond the metal particles.

The graphene modification method of the present invention further comprises: heating the powder raw material to melt into a liquid mixed raw material, the liquid mixed raw material comprising metal powder, liquid adhesive and graphene powder; injecting the liquid mixed raw material into a mold for injection molding And solidify into a preliminary embryo; and remove the adhesive in the preliminary embryo to form a dewaxed semi-finished product, first perform solvent dewaxing on the preliminary embryo to remove part of the adhesive, so that a gap is formed inside the dewaxed semi-finished product, and then thermal dewaxing is performed. The temperature of the wax is between 140°C and 170°C, wherein the dewaxed semi-finished product is sintered in step f to fuse the metal particles into a metal body.

The graphene modification method of the present invention sinters and dewaxes semi-finished products in a nitrogen or hydrogen thermal sintering manner.

In the graphene modification method of the present invention, in the solvent dewaxing, the initial embryo is immersed in a solution to dissolve the adhesive. Its thermal dewaxing heat treats the embryo to vaporize the adhesive.

In the graphene modification method of the present invention, the metal particles are sintered in a vacuum hot pressing sintering manner.

In the graphene modification method of the present invention, the metal body is aluminum or copper.

The metal graphene modification method of the present invention, each metal particle is a dendritic electrolytic copper particle. Powder raw materials are mixed by planetary stirring. The weight percentage of graphene powder in the powder raw material is less than 5%.

To sum up, the graphene modification method of the metal according to the present invention adds graphene when the metal powder and the adhesive are mixed, and after kneading and granulation, a mixture of the metal, the adhesive and the graphene is formed. After the wax, the metal powder is combined with the graphene in the sintering stage to improve its heat transfer coefficient.

Description of drawings

The above objects, features and advantages of the present invention will become more apparent from the detailed description of the preferred embodiments of the present invention shown in the accompanying drawings. The same reference numerals refer to the same parts throughout the drawings, and the drawings have not been intentionally drawn to scale, the emphasis being placed on illustrating the gist of the present invention.

Fig. 1 is the flow chart of the graphene modification method of the metal of the preferred embodiment of the present invention;

Fig. 2 is the schematic diagram of the powder raw material in the graphene modification method of the metal of the preferred embodiment of the present invention;

Fig. 3 is the schematic diagram of the injection molding step in the metal graphene modification method of the preferred embodiment of the present invention;

Fig. 4 is the schematic diagram of the initial embryo in the graphene modification method of the metal of the preferred embodiment of the present invention;

Fig. 5 is the schematic diagram of the dewaxed semi-finished product in the metal graphene modification method of the preferred embodiment of the present invention;

6 is a schematic diagram of a graphene metal composite material according to a preferred embodiment of the present invention;

7 is a schematic diagram of graphene;

Figure 8 is a schematic diagram of functionalized graphene.

Reference number:

10 powder raw materials

20 Liquid mixed raw materials

30 primary embryos

40 Dewaxed semi-finished products

50 finished products

100 Metal Particles

100a Metal Body

200 graphene microchips

300 Adhesives

400 molds

a~f steps.

Detailed ways

Referring to FIG. 1 to FIG. 6 , a preferred embodiment of the present invention provides a graphene metal composite material and a manufacturing method thereof. In this embodiment, the graphene modification method of the metal of the present invention at least comprises the following steps:

In step a, a metal powder, a graphene powder and a binder 300 (binder) are provided, wherein the metal powder is aluminum powder or copper powder. The metal powder includes a plurality of metal particles 100 (aluminum particles or copper particles, the copper particles are preferably dendritic electrolytic copper particles), the graphene powder includes a plurality of graphene microplatelets 200, and each graphene microplatelet 200 includes as shown in FIG. 7 Linked complex graphene molecules are shown. Referring to FIG. 1 , FIG. 7 and FIG. 8 , the graphene microplates (as shown in FIG. 7 ) are modified and connected with functional groups to become functionalized graphene (as shown in FIG. 8 ). In this embodiment, the functional group is preferably an oxygen-containing functional group, such as stearic acid, and the oxygen-containing functional group is bonded to one of the carbon atoms of graphene through a sp3 bond in the mixed-layer orbital domain. Each graphene molecule includes six carbon atoms that are cyclically connected, and as shown in FIG. 8 , one of the carbon atoms of each graphene molecule is connected to a functional group by a mixed-layer orbital sp3 bond. The adhesive 300 is mainly a wax material, which includes paraffin wax, microcrystalline wax or acrylic wax, etc., and is usually composed of low molecular weight thermoplastic polymers or oils. The adhesive 300 contains 0.5-2% by weight of titanate or organic chromium complex as a coupling agent for the fixing material. The adhesive 300 contains 5-20% by weight of a dispersant so that the material can be dispersed uniformly, and the dispersant can be methyl amyl alcohol, polyacrylamide or fatty acid polyethylene glycol ester.

In step b, the metal powder, graphene powder and adhesive 300 provided in step a are subjected to mixing and granulation processing to obtain a powder raw material 10 . The kneading and granulation system uniformly mixes the metal powder, the graphene powder and the adhesive 300 , so that the metal particles 100 and the graphene micro-flakes 200 in the powder raw material 10 can be dispersed in the dispersant and are respectively coated by the adhesive 300 . Specifically, due to the considerable difference in specific gravity between graphene and metal, it is necessary to mix and mix in a planetary manner while stirring in different directions so that the graphene microflakes 200 can be evenly distributed in the powder raw material 10 . Moreover, the weight percent of graphene powder in the powder raw material is preferably less than 5% to avoid agglomeration. The functionalized graphene improves the dispersibility of the graphene microplatelets 200 in the metal powder and the adhesive 300 in step b. Because a certain amount of functional groups enter the graphene microsheets 200, the graphene microsheets 200 will have the same charge. When the graphene microsheets 200 have functional groups, electrostatic repulsion will be generated between the same charges, making the graphene microsheets 200. 200 are mutually repelled and separated and can be uniformly dispersed in the dispersant and the adhesive 300. During the kneading process of step b, the friction of the functionalized graphene microplates 200 generates heat energy to cause the sp3 bond of the mixed-layer orbital domain containing oxygen-containing functional groups to endothermically break, and the oxygen-containing functional groups are separated. Therefore, the carbon atoms originally bound by the oxygen-containing functional groups can immediately re-bond with the sp3 bonds of the mixed-layer orbitals broken by the carbon atoms in other graphene microsheets 200, thereby making the graphene microsheets 200 connected to be planar and including Each metal particle 100 is coated to form a sphere.

Specifically, in the present invention, a coupling agent is added to the mixture of graphene and metal to assist the bonding of organic graphene and inorganic metal, and a dispersing agent is added to disperse graphene to avoid agglomeration. Furthermore, the inorganic material is generally in the ionic state in the mixture and has a bonding force, and the coupling agent can also assist the dispersing agent to disperse the inorganic material. Both titanates and organic chromium complexes have the characteristics of strong peripheral electronic bonding, which can enhance the bonding strength between graphene and metals. Furthermore, titanates have the advantage of light weight, while organic chromium complexes have side effects. chain and more bonds can be formed. Different dispersants are used for graphene materials in different states. Methyl amyl alcohol is added to solid materials as dispersants, polyacrylamide is added to liquid materials as dispersants, and fatty acid polyethylene glycol esters are added to gaseous materials as dispersants.

The sintered metal particles 100 can be sintered by vacuum hot pressing. In the vacuum hot pressing sintering method, in the sintering step f following step b, the liquid mixed raw material 20 is injected into a mold 400 as shown in FIG. 20 The metal particles 100 of aluminum or copper can be sintered by pressing and sintering in a vacuum at 700° C. for 1 hour. Lower temperature sintering is facilitated by the die 400 pressurizing the liquid mixed raw material 20 to increase its density.

The metal particles 100 are sintered by vacuum hot-pressing sintering so that the metal particles 100 are melted and combined into a metal body 100a, and the adhesive 300 is vaporized and eliminated at the same time. The adhesive 300 is used, so the structure will not be damaged during heat treatment, and the graphene micro-sheets 200 are evenly distributed in the metal body 100a. The selected metal particles 100 are different (aluminum or copper), and the sintered metal body 100a can be aluminum or copper. Thereby, the finished product 50 of the graphene-metal composite material of the present invention is produced as shown in FIG. 6 .

The sintered metal particles 100 may also be cold-pressed and hot-sintered. It includes two steps of cold pressing (c-e) and sintering (f). The cold pressing step includes the following two steps.

In step c, following step b, the powder raw material 10 is heated to melt into a liquid mixed raw material 20; the liquid mixed raw material 20 includes metal powder, liquid adhesive 300 and graphene powder.

In step d, following step c, as shown in FIG. 3 , the liquid mixed raw material 20 is injected into a mold 400 and solidified by cold equalization forming to form a green part as shown in FIG. 4 ; The metal particles 100 and the graphene micro-sheets 200 are uniformly mixed, and each graphene micro-sheet 200 is coated with a solid adhesive 300 to bond the metal particles 100 .

As shown in FIG. 5 , in step e, following step d, the preliminary embryo 30 is subjected to a debinding process to remove the adhesive 300 in the preliminary embryo 30 to form a dewaxed semi-finished product 40 (brown part). The dewaxing method may be thermal debinding (thermal debinding) or solvent dewaxing (watery/solvent debinding). The thermal dewaxing system performs heat treatment on the primary embryo 30, uses an inert gas as a flowing medium, and increases the temperature to crack and vaporize the adhesive 300, which is carried out by the medium. The vacuum dewaxing system uses high temperature and high vacuum to evaporate the adhesive 300, and then take it out by distillation molecules. The solvent dewaxing system uses a solvent to dissolve the adhesive 300 . Among them, thermal dewaxing and solvent dewaxing can be performed in parallel. First, solvent dewaxing is performed on the preliminary embryo 30 to remove part of the adhesive 300, so that a gap is formed inside the dewaxed semi-finished product 40, and then thermal dewaxing is performed, which is conducive to the passage of high-temperature gas through the gap. The remaining adhesive 300 is decomposed and discharged. In step e, the temperature of the thermal dewaxing step is preferably lower than the melting point of the metal particles 100 and higher than the melting point or boiling point of the adhesive 300, and the ambient temperature is heated to 140°C to 170°C, because the graphene microplates 200 do not melt. And its boiling point is much higher than that of the metal particles 100 and the adhesive 300, so the structure will not be damaged during heat treatment.

In the sintering step f, following step e, the dewaxed semi-finished product 40 is sintered by nitrogen or hydrogen thermal sintering to melt the metal particles 100 and combine with each other to form a metal body 100a. When the metal particles 100 are copper, the ambient working temperature is heated to 1050° C. After sintering for 1 hour, when the metal particles 100 are aluminum, the ambient working temperature is heated to 600° C. and sintered for 1 hour. Since the graphene microplatelets 200 do not melt and have a much higher boiling point than the metal particles 100 and the adhesive 300, the structure will not be damaged during heat treatment, and the graphene microplatelets 200 are evenly distributed in the metal body 100a. The metal body 100a is aluminum or copper. Thereby, the finished product 50 of the graphene-metal composite material of the present invention is produced as shown in FIG. 6 .

Referring to FIG. 6 , the finished graphene-metal composite material 50 of the present invention is made by the aforementioned manufacturing method. The graphene-metal composite material of the present invention comprises a metal body 100a and a plurality of graphene microplates embedded in the metal body 100a 200. The metal body 100a is made of aluminum or copper, and the graphene microplates 200 are evenly distributed in the metal body 100a.

To sum up, in the metal graphene modification method of the present invention, the graphene powder is added when the metal powder and the adhesive 300 are mixed, and the metal particles 100, the graphene microplates 200 and the adhesive 300 are formed after the mixing and granulation. After the mixture is injection-molded and dewaxed, in the sintering stage, the graphene micro-sheets 200 in the finished product 50 that were originally arranged in a spherical shape and wrapped around the metal particles 100 form a three-dimensional network of connected spheres and are combined into the metal body 100a to improve the performance. The finished product has a heat transfer coefficient of 50. By increasing the heat transfer coefficient of the metal piece by means of graphene, compared with pure metal as a heat conduction medium, the present invention can configure a smaller graphene metal composite material as a heat conduction medium under the condition of the same total amount of heat conduction. Furthermore, in the present invention, by adding functional groups, the graphene microplates 200 are arranged in a relatively regular manner. Compared with the conventional random dispersion structure, the thermal energy is more uniformly dispersed in the finished product 50, and thus has better heat conduction efficiency.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Other equivalent changes using the patent spirit of the present invention shall all belong to the patent scope of the present invention.

Claims (9)

1. a metal graphene modification method, is characterized in that, comprises: a) providing a metal powder, a graphene powder and an adhesive, wherein the metal powder includes a plurality of metal particles, the adhesive includes a wax material, the graphene powder includes a plurality of graphene microplatelets, each of the graphite The graphene microplatelets comprise connected several graphene molecules, each graphene molecule comprises six carbon atoms connected in a ring, and one of the carbon atoms of each graphene molecule connects a stearic acid function with a mixed-layer orbital sp bond. base, the adhesive comprises a coupling agent of 0.5-2% by weight and a dispersant of 5-20% by weight, the coupling agent is one of titanate and organic chromium complex, the dispersant It is one of methyl amyl alcohol, polyacrylamide and fatty acid polyethylene glycol ester; b) Mixing the metal powder, the graphene powder and the adhesive into a powder raw material, and mixing friction to generate heat to make each of the mixed-layer orbital sp3 bonds connected by the stearic acid functional groups endothermic After being broken, the stearic acid functional group is separated from each of the graphene molecules, and each of the graphene molecules is bonded to other graphene molecules by the broken mixed-layer orbital sp3 bond to make the graphene molecule. Graphene molecules coat each of the metal particles; c) heating the powder raw material to melt into a liquid mixed raw material, and the liquid mixed raw material includes the metal powder, the liquid adhesive and the graphene powder; d) injecting the liquid mixed raw material into a mold for injection molding and solidifying into a primary embryo; e) removing the adhesive in the preliminary embryo to form a dewaxed semi-finished product, first perform solvent dewaxing on the preliminary embryo to remove part of the adhesive, make a gap inside the dewaxed semi-finished product, and then perform thermal dewaxing. The temperature of the wax is between 140°C and 170°C; f) sintering the metal particles so that the metal particles are fused into a metal body, and the graphene molecules form a three-dimensional network and are combined in the metal body; Wherein, in step f, the dewaxed semi-finished product is sintered to fuse the metal particles into the metal body, and the metal body is aluminum or copper. 2. the graphene modification method of metal as claimed in claim 1, is characterized in that, wherein in step d, described initial embryo comprises described metal particle and described graphene microplatelet of homogeneous mixing, and each described graphite The olefin platelets are coated with the solid adhesive to bind the metal particles. 3. The graphene modification method of metal as claimed in claim 1, wherein in step f, the dewaxed semi-finished product is sintered in a nitrogen or hydrogen thermal sintering mode. 4. The graphene modification method of metal according to claim 1, wherein in step e, the solvent dewaxing immerses the preliminary embryo in a solution to dissolve the adhesive. 5. The graphene modification method of metal as claimed in claim 1, wherein in step e, the thermal dewaxing heats the initial embryo to vaporize the adhesive. 6. The graphene modification method of metal according to claim 1, wherein in step f, the metal particles are sintered by vacuum hot pressing sintering. 7. The graphene modification method of metal according to claim 1, wherein each of the metal particles is a dendritic electrolytic copper particle. 8. the graphene modification method of metal as claimed in claim 1, is characterized in that, wherein said powder raw material forms with planetary stirring and mixing. 9. The graphene modification method of metal according to claim 1, wherein the weight percent of the graphene powder in the powder raw material is less than 5%.

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