Method for enhancing mechanical property of graphene copper nano composite material by using molecular-level mixing process

Abstract

The invention discloses a method for enhancing the mechanical property of a graphene / copper nano composite material through a molecular-level mixing process and a spark plasma sintering (SPS) process. The method aims at solving the problems that the binding force between a graphene sheet and a metal matrix is weak, and graphene is prone to damage in the high-temperature machining process. Functional groups are attached to the graphene sheets, chemical bonds are formed between the graphene and the copper through chemical reactions, and the bonding strength of the graphene and the copper is remarkably improved. In addition, the invention also provides a system for preparing the nano composite material, and the system comprises a chemical treatment unit, a mixing unit and a sintering unit.

Description

Technical Field

[0001] The invention relates to a method for enhancing the mechanical properties of a graphene / copper nanocomposite material by using a molecular-level mixing process, in particular to improving the elastic modulus, yield strength and adhesion energy of the nanocomposite material by improving the bonding strength between graphene and copper at the molecular level. Background Art

[0002] Graphene, a two-dimensional layered material composed of carbon atoms, has attracted much attention due to its excellent mechanical and electrical properties. However, there are two main problems when applying graphene to metal-based nanocomposites: the poor bonding between graphene flakes and metals, and the easy decomposition or damage of graphene when the processing temperature is relatively high. These problems limit the application of graphene in improving the mechanical properties of metal composites. Summary of the invention

[0003] The present invention proposes a molecular-level mixing process and spark plasma sintering (SPS) process to study the strengthening effect of graphene in a metal matrix. This method avoids the dispersion and thermal damage problems of graphene flakes, and improves the bonding strength between graphene and copper by attaching functional groups to the graphene flakes and forming chemical bonds between the graphene and the composite matrix. Technical Solution

[0004] The present invention provides a method for enhancing the mechanical properties of a graphene / copper nanocomposite material by using a molecular-level mixing process, comprising the following steps: a. attaching functional groups to graphene sheets; b. forming a chemical bond between graphene and copper ions through a chemical reaction; c. The metal powder is solidified using a spark plasma sintering (SPS) process to form a graphene / copper nanocomposite.

[0005] As a preferred embodiment, the functional group includes at least one of a hydroxyl group, an epoxy group, a carbonyl group and a carboxyl group.

[0006] As a preferred embodiment, the chemical reaction comprises mixing graphene oxide (GO) and copper ions in an aqueous solution, and then oxidizing the mixture using a NaOH solution to form a GO / copper oxide (CuO) nanocomposite powder.

[0007] As a preferred embodiment, the SPS process includes rapidly heating and cooling the nanocomposite powder under conditions below the graphene decomposition temperature.

[0008] The present invention also provides a graphene / copper nanocomposite material obtained by the method, wherein the graphene flakes are uniformly dispersed in the copper matrix, and a chemical bond exists between the graphene and the copper.

[0009] The obtained graphene / copper nanocomposite material was tested, wherein the elastic modulus of the graphene / copper nanocomposite material was 130-135 GPa, and the yield strength was 280-285 MPa. Compared with pure copper products, the elastic modulus and yield strength were higher by more than 30% and 80%.

[0010] The present invention also provides a system for preparing graphene / copper nanocomposite materials by molecular-level mixing process and spark plasma sintering (SPS) process, comprising: a. A chemical treatment unit for attaching functional groups on graphene sheets; b. a mixing unit for forming a chemical bond between graphene and copper ions; c. Sintering unit for solidifying metal powder by SPS process.

[0011] The chemical treatment unit is configured to mix graphene oxide (GO) and copper ions in an aqueous solution, and oxidize the mixture using a NaOH solution to form a GO / copper oxide (CuO) nanocomposite powder. DETAILED DESCRIPTION

[0012] The specific process is described in detail below.

[0013] A) Preparation of graphene oxide (GO) First, 1 g of graphite was mixed with 40 mL of H2SO4 in an ice bath. Then, KMnO4 was slowly added as an oxidant. After the solution was uniform, deionized water was added as an oxygen source, followed by H2O2 to remove manganese ions. The residue in the solution was removed by vacuum filtration, rinsed with hydrochloric acid solution, and finally dried in a vacuum oven to obtain GO.

[0014] B) Preparation of RGO / Cu nanocomposite powder 75 mg of GO was dispersed in 500 ml of deionized water by ultrasonic treatment. Cu(CH3COO)2·H2O was dissolved in an appropriate amount of water and then added to the GO suspension and stirred. The mixed solution was heated to 80-90°C, followed by the addition of NaOH aqueous solution. The chemical reaction reduced the Cu ions to CuO to form GO / CuO nanocomposite powders. The powders were separated by centrifugation, rinsed with deionized water, and vacuum dried. They were then reduced at 400°C for 2-3 hours under a hydrogen atmosphere to form graphene / copper nanocomposite powders.

[0015] C) Curing RGO / Cu nanocomposite powder The RGO / Cu nanocomposite powder was pressed in a graphite mold. The powder was consolidated under an applied pressure and then subjected to spark plasma sintering (SPS) for 3 minutes under vacuum conditions. After curing, the RGO / Cu nanocomposite material was obtained.

[0016] D) Characterization of RGO / Cu nanocomposites AFM and SEM analysis showed that RGO was uniformly dispersed in the copper matrix without obvious agglomeration. The tight bonding between RGO flakes and copper particles indicated that the molecular-level mixing process successfully formed a strong interfacial bond between RGO and copper.

[0017] Tensile test results show that the elastic modulus and yield strength of the nanocomposite containing 2.5 volume percent RGO are 131 GPa and 284 MPa, respectively, which are about 30% and 80% higher than those of pure copper. This significant performance improvement is attributed to the high load transfer efficiency of RGO and the strong interface bonding between RGO and copper.

[0018] The DCB test results show that the adhesion energy between graphene and copper is 164 J / m 2 , which is much higher than the adhesion energy between pure copper and graphene. This high adhesion energy proves that the molecular-level mixing process and SPS process can significantly enhance the interfacial bonding strength between graphene and copper.

Claims

1. A method for enhancing the mechanical properties of graphene / copper nanocomposites using a molecular-level mixing process, comprising the following steps: a. attaching functional groups to graphene sheets; b. forming a chemical bond between graphene and copper ions through a chemical reaction; c. The metal powder is solidified using a spark plasma sintering (SPS) process to form a graphene / copper nanocomposite. 2 . The method according to claim 1 , wherein the functional group comprises at least one of a hydroxyl group, an epoxy group, a carbonyl group, and a carboxyl group.

3. The method of claim 1, wherein the chemical reaction comprises mixing graphene oxide (GO) and copper ions in an aqueous solution and then oxidizing the mixture using a NaOH solution to form a GO / copper oxide (CuO) nanocomposite powder.

4. The method of claim 1, wherein the SPS process comprises rapidly heating and cooling the nanocomposite powder under conditions below the graphene decomposition temperature.

5. A graphene / copper nanocomposite material, characterized in that: The nanocomposite material is prepared by the method of claim 1, wherein graphene flakes are uniformly dispersed in a copper matrix, and a chemical bond exists between graphene and copper.

6. The nanocomposite material according to claim 5, wherein the elastic modulus of the graphene / copper nanocomposite material is 130-135 GPa and the yield strength is 280-285 MPa.

7. A system for preparing graphene / copper nanocomposite materials by molecular mixing process and spark plasma sintering (SPS) process, comprising: a. A chemical treatment unit for attaching functional groups on graphene sheets; b. a mixing unit for forming a chemical bond between graphene and copper ions; c. Sintering unit for solidifying metal powder by SPS process.

8. The system of claim 7, wherein the chemical treatment unit is configured to mix graphene oxide (GO) and copper ions in an aqueous solution and oxidize the mixture using a NaOH solution to form a GO / copper oxide (CuO) nanocomposite powder.