A method for efficiently preparing high-strength and high-conductivity copper-based composite wire

Abstract

The present application relates to a kind of high efficient preparation high-strength high-conductivity copper-based composite wire method, through high-purity citric acid or citrate one-step generation zero-dimensional GQDs load in two-dimensional GN surface multi-dimensional reinforcing phase, using stirring ball mill preparation kilogram-level GQDs@GN / Cu composite powder, then through pre-pressing and microwave sintering equipment preparation composite bar, finally using cold extrusion extrusion into wire material of cylindrical bar, the yield strength and tensile strength of the GQDs@GN / Cu composite wire material prepared by the method are 274MPa and 314MPa respectively, and the conductivity is as high as 95.3%IACS;The present application has short preparation time, simple process, low production cost, high yield, good reinforcing effect, and is suitable for mass production.

Description

TECHNICAL FIELD

[0001] The application relates to a method for efficiently preparing a high-strength and high-conductivity copper-based composite wire and belongs to the technical field of composite material preparation. BACKGROUND

[0002] Graphene (GN) is a material with excellent electrical conductivity, thermal conductivity and mechanical properties, and is therefore widely used in reinforced metal matrix composites. However, the interface bonding between GN and the copper matrix (Cu) is weak, lacking chemical bonding, which leads to GN failing to achieve effective load transfer and also increases the interface scattering of electrons, thereby causing the deterioration of the electrical conductivity and mechanical properties of the Cu-based composite material. In order to solve this problem, graphene quantum dots (GQDs) as a new reinforcing phase material have become a research hotspot.

[0003] GQDs refer to single-layer or multi-layer graphene fragments with functional groups on the edges or internal defects of graphene, and have unique quantum confinement effects and edge effects. The oxygen-containing function of GQDs provides active oxygen atoms, which can generate copper oxide (CuO x ) at the interface between GQDs and Cu to enhance the interface bonding of the composite material. From existing research reports, it is found that GQDs have excellent electrical conductivity and good interface bonding with Cu, making the GQDs / Cu composite material exhibit excellent electrical conductivity. Therefore, loading zero-dimensional GQDs on the surface of two-dimensional GN (GQDs@GN) can enhance the interface bonding between the Cu matrix and GN, and thus realize high strength and high conductivity of the Cu-based composite material.

[0004] The preparation methods of GN generally include mechanical exfoliation, oxidation-reduction, SiC epitaxial growth and chemical vapor deposition. The preparation methods of GQDs include the "bottom-up method" and the "top-down method". However, the process of separately preparing GQDs and GN is complex, high in cost, and the acid and alkali reagents in the preparation process will cause environmental pollution. In addition, loading GQDs on the surface of GN by the existing method cannot guarantee the uniform distribution of GQDs on GN, and cannot effectively enhance the interface bonding between GN and the Cu matrix. Therefore, it is necessary to develop a rapid, high-yield and uniform distribution method for preparing GQDs@GN. SUMMARY

[0005] In view of the problems in the prior art, the application provides a one-step method for preparing a large amount of multi-dimensional GQDs@GN hybrid, and the method is applied to batch production of high-strength and high-conductivity Cu-based composite wire, the GQDs@GN powder with high purity, high quality and uniform quality can be prepared by using a microwave high-temperature vacuum atmosphere furnace or a plasma sintering furnace, the method is simple, fast and low in cost, and no harmful acid or alkali reagent is needed, in addition, the method can ensure uniform distribution of GQDs on the surface of GN, effectively enhance the interface bonding between GN and the Cu matrix, and the GQDs@GN / Cu composite material shows excellent electrical conductivity and mechanical properties, so that the GQDs@GN material can be widely applied to production of high-strength and high-conductivity Cu-based composite wire.

[0006] The application uses high-purity citric acid or citrate as a carbon source to generate a large amount of GQDs@GN in one step, and uses a horizontal cylindrical rotary device ball mill to prepare kilogram-level GQDs@GN / Cu composite powder, the composite powder is pre-pressed and sintered by a microwave to prepare GQDs@GN / Cu composite rod, and the composite rod is cold extruded into high-strength and high-conductivity wire.

[0007] The application aims to achieve the following technical solutions:

[0008] A method for efficiently preparing high-strength and high-conductivity copper-based composite wire, and the specific steps are as follows:

[0009] (1) Preparation of GQDs@GN

[0010] High-purity citric acid or citrate is rapidly heated to a certain temperature in a thermal decomposition device for thermal decomposition, and after cooling to room temperature, the reaction product is dissolved in deionized water and centrifuged, the supernatant is dialyzed and freeze-dried to obtain a large amount of GQDs@GN powder;

[0011] (2) Preparation of GQDs@GN / Cu composite powder

[0012] The GQDs@GN powder is ultrasonically dispersed in anhydrous ethanol to obtain a GQDs@GN mixture, and the GQDs@GN mixture and Cu powder are mixed by a horizontal cylindrical rotary device ball mill, and then the uniformly mixed suspension is filtered and vacuum dried to obtain GQDs@GN / Cu composite powder;

[0013] (3) Pre-pressing and sintering

[0014] A four-column hydraulic press is used to press and form the kilogram-level GQDs@GN / Cu composite powder, and the obtained compact is placed in a microwave sintering equipment for microwave sintering and solidification treatment to obtain GQDs@GN / Cu composite rod;

[0015] (4) cold extrusion

[0016] The GQDs@GN / Cu composite rod is extruded into a wire by a cold extrusion hydraulic machine, that is, a copper-based composite wire with high strength and high conductivity.

[0017] Step (1) the citrate is ferric citrate, copper citrate and the like.

[0018] Step (1) the thermal decomposition device is a microwave high-temperature vacuum atmosphere furnace or a plasma device (such as a plasma sintering furnace, a vacuum plasma treatment machine and the like).

[0019] Step (1) the temperature of thermal decomposition is 200-400 DEG C, the time is 1-20 min, the temperature rising rate is 50-150 DEG C / min, and the vacuum degree pressure is less than 10 Pa.

[0020] Step (1) the reaction product after thermal decomposition is dialyzed by using a dialysis bag with a molecular weight of 1000-5000, the dialysis bag diameter and length are 70 mm and 5 m respectively, and the dialysis time is 24 h-72 h.

[0021] Step (2) the mass ratio of GQDs@GN powder to anhydrous ethanol is 1:1000-1:100, and when the GQDs@GN powder and anhydrous ethanol mixed solution is ultrasonically dispersed, an ultrasonic power of 300-960 W is used per 500 ml, and the ultrasonic time is 30-80 min, and 1-2 min is intermittently provided every 5-10 min.

[0022] Step (2) the mass ratio of GQDs@GN powder to copper powder is 0.2:100-1:100, the ball milling time is 5-10 h, the ball milling rotating speed is 350-500 r / min, the ball milling ratio is 10:1, the ball milling medium is anhydrous ethanol, and the ball milling atmosphere is Ar gas or N2 gas.

[0023] Step (3) the pressure for pressing forming is 100-200 MPa, and the pressure maintaining time is 10-30 min.

[0024] Step (3) the microwave sintering solidification treatment temperature is 550-850 DEG C, the holding time is 1-10 min, and the vacuum degree pressure is not more than 10 Pa.

[0025] Step (4) the extrusion pressure is 800-2000 MPa.

[0026] The beneficial effects of the present application are as follows:

[0027] (1) The present application uses environment-friendly high-purity citric acid or citrate as a carbon source, and generates a large amount of multi-dimensional GQDs@GN through thermal decomposition treatment in one step. In addition, a horizontal cylindrical rotating device ball mill and a four-column hydraulic machine are used to realize industrial production of the product. The sintering time of microwave sintering is short. The method is simple to operate, has a short preparation process, high yield, low production cost, and can be mass-produced. x In the sintering process of the GQDs@GN / Cu composite rod of the present application, the oxygen-containing functional groups of GQDs react with the Cu matrix to generate CuO BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 TEM (transmission electron microscope) image of GQDs@GN powder in step (1) of Example 1;

[0029] Figure 2 SEM (scanning electron microscope) image of GQDs@GN / Cu powder in step (2) of Example 1;

[0030] Figure 3 TEM image of GQDs@GN / Cu bulk composite material in step (3) of Example 1;

[0031] Figure 4 is a partial enlarged view of the middle box region of Figure 3 , and IFFT and FFT are performed on regions I and II;

[0032] Figure 5 Fracture surface SEM image of GQDs@GN / Cu bulk composite material in step (3) of Example 1;

[0033] Figure 6 TEM image of GQDs in step (1) of Comparative Example 1;

[0034] Figure 7 TEM image of GN in step (1) of Comparative Example 2. DETAILED DESCRIPTION

[0035] The present application will be described in detail below in conjunction with the drawings and specific embodiments. The specific methods in the application are conventional methods unless otherwise specified. The raw materials involved can be purchased commercially unless otherwise specified.

[0036] The raw materials and equipment used in the examples are as follows:

[0037] High-purity citric acid: purity 99.5%, Shanghai Maikelin Technology Co., Ltd.;

[0038] High purity iron citrate: purity 99.5%, Shanghai Maikelin Technology Co., Ltd;

[0039] High purity copper citrate: purity 99.5%, Shanghai Maikelin Technology Co., Ltd;

[0040] Copper powder: purity 99.9%, particle size 45-50 μm, Shanghai Naoen Nanometer Technology Co., Ltd;

[0041] Anhydrous ethanol: purity 99.9%, Shanghai Maikelin Technology Co., Ltd;

[0042] Dialysis bag: molecular weight: 500-1000, length: 5 m, width: 70 mm, Shanghai Yibai Polymer Trading Co., Ltd;

[0043] Microwave high-temperature vacuum atmosphere furnace: INNOV-AS-04M1600, Hunan Yuanchuang Gaoke Industrial Technology Co., Ltd;

[0044] Horizontal cylindrical rotary device ball mill: ZD-GMJ-01, Taisheng Chemical Machinery Co., Ltd;

[0045] Vacuum plasma processor: CRF-VPO-8L-S, Chengfeng Wisdom Manufacturing Co., Ltd;

[0046] Ultrasonic cleaning machine: SM-800D, Nanjing Shunma Instrument and Equipment Co., Ltd;

[0047] Freeze dryer: LGJ-100F, Beijing Songyuan Huaxing Technology Development Co., Ltd;

[0048] Hydraulic press: YQ32-315T, Shandong Zhongzhuang Numerical Control Machine Tool Co., Ltd;

[0049] Cold extrusion hydraulic press: 315T, Tengzhou Kave Machinery Equipment Co., Ltd;

[0050] Scanning electron microscope: Nova Nano-450, Philips-FEI, Netherlands;

[0051] Transmission electron microscope: Tecnai G2-TF30, FEI, USA;

[0052] Mechanical property characterization of the GQDs@GN / Cu composite material prepared in the examples: tensile test was carried out at room temperature by using a universal testing machine (AG-Xplus 50KN), wherein the tensile rate was 0.2 mm / min.

[0053] Example 1

[0054] A method for efficiently preparing a high-strength and high-conductivity copper-based composite wire, the specific steps are as follows:

[0055] (1) Preparation of GQDs@GN

[0056] 1.0 kg of high-purity iron citrate was rapidly heated to 200°C in a microwave high-temperature vacuum atmosphere furnace at a heating rate of 50°C / min, and the thermal decomposition time was 1 min. The vacuum degree was less than 10 Pa. After the furnace was cooled to room temperature, the generated product was dissolved in deionized water and centrifuged. The clear liquid after centrifugal treatment was poured into a dialysis bag with a molecular weight of 1000, a diameter of 70 mm and a length of 5 m. The dialysis time was 24 h. Finally, the GQDs@GN liquid in the dialysis bag was freeze-dried to obtain a large amount of GQDs@GN powder;

[0057] (2) Preparation of GQDs@GN / Cu composite powder

[0058] 100 g of GQDs@GN powder was dispersed by ultrasonic treatment in 100 L of anhydrous ethanol. The ultrasonic power was 300 W, and the ultrasonic time was 30 min, with 1 min of stop every 5 min. The obtained GQDs@GN mixed liquid was mixed with 50 kg of Cu powder using a horizontal cylindrical rotary device ball mill. The ball milling time was 5 h, the ball milling speed was 350 r / min, the ball-to-material ratio was 10:1, and the ball milling atmosphere was Ar gas. Then the uniformly mixed suspension was filtered and vacuum dried at a drying temperature of 60°C for 6 h under a vacuum degree pressure of 10 Pa to obtain a kilogram-level GQDs@GN / Cu composite powder;

[0059] (3) Pre-pressing and sintering

[0060] The GQDs@GN / Cu composite powder was placed in a four-column hydraulic press for pre-pressing, with a pressure of 100 MPa and a pressure holding time of 10 min. The pressed block was placed in a microwave high-temperature vacuum atmosphere furnace and heated to 550°C under a vacuum degree of less than 10 Pa, and the holding time was 1 min to obtain a GQDs@GN / Cu composite rod.

[0061] (4) Cold extrusion

[0062] The GQDs@GN / Cu composite rod was extruded into a 2 mm diameter wire by a cold extrusion hydraulic press at an extrusion pressure of 2000 MPa, thereby obtaining a high-strength and high-conductivity copper-based composite wire.

[0063] Example 2

[0064] A method for efficiently preparing a high-strength and high-conductivity copper-based composite wire, the specific steps are as follows:

[0065] (1) Preparation of GQDs@GN

[0066] The 1.0 kg high-purity copper citrate is rapidly heated to 300°C in a microwave high-temperature vacuum atmosphere furnace, the heating rate is 100°C / min, the thermal decomposition time is 10 min, the vacuum degree is less than 10 Pa, and the generated product is dissolved in deionized water and centrifuged. The clear liquid after centrifugal treatment is poured into a dialysis bag with a molecular weight of 3000, the diameter and length of the dialysis bag are 70 mm and 5 m respectively, the dialysis time is 48 h, and finally the GQDs@GN liquid in the dialysis bag is freeze-dried to obtain a large amount of GQDs@GN powder;

[0067] (2) Preparation of GQDs@GN / Cu composite powder

[0068] The 100 g GQDs@GN powder is dispersed by ultrasonic treatment in 50 L anhydrous ethanol, the ultrasonic power is 630 W, the ultrasonic time is 50 min, and every 7 min is intermittent for 1.5 min. The obtained GQDs@GN mixed liquid is mixed with 20 kg Cu powder by using a horizontal cylindrical rotary device ball mill, the ball milling time is 8 h, the ball milling speed is 425 r / min, the ball-to-material ratio is 10:1, and the ball milling atmosphere is N2 gas. Then the uniformly mixed suspension is filtered and vacuum dried, the drying temperature is 60°C, the drying time is 6 h, the vacuum degree is less than 10 Pa, and a kilogram-level GQDs@GN / Cu composite powder is obtained;

[0069] (3) Pre-pressing and sintering

[0070] The GQDs@GN / Cu composite powder is placed in a four-column hydraulic press for pre-pressing, the pressure is 150 MPa, and the pressure holding time is 20 min. The pressed block is placed in a microwave high-temperature vacuum atmosphere furnace and heated to 750°C under a vacuum degree of not more than 10 Pa, and the holding time is 5 min. A GQDs@GN / Cu composite rod is obtained.

[0071] (4) Cold extrusion

[0072] The GQDs@GN / Cu composite rod is extruded into a 3 mm diameter wire by a cold extrusion hydraulic press, and the extrusion pressure is 1400 MPa. A high-strength and high-conductivity copper-based composite wire is obtained.

[0073] Example 3

[0074] A method for efficiently preparing a high-strength and high-conductivity copper-based composite wire, the specific steps are as follows:

[0075] (1) Preparation of GQDs@GN

[0076] 1.0 kg of high-purity citric acid was rapidly heated to 400 °C in a microwave high-temperature vacuum atmosphere furnace for thermal decomposition at a heating rate of 150 °C / min for 20 min under a vacuum of less than 10 Pa. After the furnace cooled to room temperature, the product was dissolved in deionized water and centrifuged. The clear liquid after centrifugation was poured into a dialysis bag with a molecular weight of 5000, the diameter and length of which were 70 mm and 5 m, respectively. The dialysis time was 72 h. Finally, the GQDs@GN solution in the dialysis bag was freeze-dried to obtain a large amount of GQDs@GN powder.

[0077] (2) Preparation of GQDs@GN / Cu composite powder

[0078] 100g of GQDs@GN powder was ultrasonically dispersed in 10L of anhydrous ethanol. The ultrasonic power was 960W and the ultrasonic time was 80min, with a 2min pause every 10min. The resulting GQDs@GN mixture was then mixed with 10kg of Cu powder using a horizontal cylindrical rotary ball mill for 10h. The ball milling speed was 500r / min, the ball-to-powder ratio was 10:1, and the ball milling atmosphere was Ar. The uniformly mixed suspension was then filtered and vacuum dried at 60℃ for 6h under a vacuum of less than 10Pa to obtain kilogram-scale GQDs@GN / Cu composite powder.

[0079] (3) Pre-pressing and sintering

[0080] GQDs@GN / Cu composite powder was placed in a four-column hydraulic press for pre-pressing at a pressure of 200 MPa for 30 min. The pressed block was then placed in a microwave high-temperature vacuum atmosphere furnace and heated to 850°C under a vacuum of no more than 10 Pa for 10 min to obtain GQDs@GN / Cu composite rods.

[0081] (4) Cold extrusion

[0082] GQDs@GN / Cu composite rods are extruded into wires with a diameter of 5mm using a cold extrusion hydraulic press at a pressure of 800MPa, thus obtaining high-strength and high-conductivity copper-based composite conductors.

[0083] Example 4

[0084] A method for efficiently preparing high-strength, high-conductivity copper-based composite wires, comprising the following specific steps:

[0085] (1) Preparation of GQDs@GN

[0086] 1.0 kg of high-purity citric acid was rapidly heated to 200°C in a vacuum plasma treatment machine for thermal decomposition, with a heating rate of 50°C / min, a thermal decomposition time of 1 min, and a vacuum degree of less than 10 Pa. After the vacuum plasma treatment machine cooled to room temperature, the generated product was dissolved in deionized water and centrifuged. The clear liquid after centrifugation was poured into a dialysis bag with a molecular weight of 1000, a diameter of 70 mm, and a length of 5 m. The dialysis time was 24 h. Finally, the GQDs@GN liquid in the dialysis bag was freeze-dried to obtain a large amount of GQDs@GN powder.

[0087] (2) Preparation of GQDs@GN / Cu composite powder

[0088] 100 g of GQDs@GN powder was dispersed by ultrasonic treatment in 100 L of anhydrous ethanol, with an ultrasonic power of 300 W and an ultrasonic time of 30 min, stopping every 5 min for 1 min. The obtained GQDs@GN mixture was mixed with 50 kg of Cu powder using a horizontal cylindrical rotary device ball mill, with a ball milling time of 5 h, a ball milling speed of 350 r / min, a ball-to-material ratio of 10:1, and an Ar gas ball milling atmosphere. Then, the uniformly mixed suspension was filtered and vacuum dried at a drying temperature of 60°C for 6 h under a vacuum degree pressure of 10 Pa, to obtain a kilogram-level GQDs@GN / Cu composite powder.

[0089] (3) Pre-pressing and sintering

[0090] The GQDs@GN / Cu composite powder was placed in a four-column hydraulic press for pre-pressing, with a pressure of 100 MPa and a pressure holding time of 10 min. The pressed block was placed in a microwave high-temperature vacuum atmosphere furnace and heated to 550°C under a vacuum degree of less than 10 Pa, with a holding time of 1 min, to obtain a GQDs@GN / Cu composite rod.

[0091] (4) Cold extrusion

[0092] The GQDs@GN / Cu composite rod was extruded into a 2 mm diameter wire by a cold extrusion hydraulic press at an extrusion pressure of 2000 MPa, to obtain a high-strength and high-conductivity copper-based composite wire.

[0093] Example 5

[0094] A method for efficiently preparing a high-strength and high-conductivity copper-based composite wire, with the specific steps as follows:

[0095] (1) Preparation of GQDs@GN

[0096] The 1.0 kg high-purity ferric citrate is rapidly heated to 300°C in a vacuum plasma processing machine for thermal decomposition, the heating rate is 100°C / min, the thermal decomposition time is 10 min, the vacuum degree is less than 10 Pa, and the generated product is dissolved in deionized water and centrifuged after the vacuum plasma processing machine is cooled to room temperature. Pour the clarified liquid after centrifugation into a dialysis bag with a molecular weight of 3000, the diameter and length of the dialysis bag are 70 mm and 5 m respectively, the dialysis time is 48 h, and finally the GQDs@GN liquid in the dialysis bag is freeze-dried to obtain a large amount of GQDs@GN powder;

[0097] (2) Preparation of GQDs@GN / Cu composite powder

[0098] The 100 g GQDs@GN powder is dispersed by ultrasonic treatment in 50 L anhydrous ethanol, the ultrasonic power is 630 W, the ultrasonic time is 50 min, and every 7 min is intermittent for 1.5 min. The obtained GQDs@GN mixed liquid is mixed with 20 kg Cu powder by using a horizontal cylindrical rotary device ball mill, the ball milling time is 8 h, the ball milling speed is 425 r / min, the ball-to-material ratio is 10:1, and the ball milling atmosphere is N2 gas. Then the uniformly mixed suspension is filtered and vacuum dried, the drying temperature is 60°C, the drying time is 6 h, the vacuum degree is less than 10 Pa, and a kilogram of GQDs@GN / Cu composite powder is obtained;

[0099] (3) Pre-pressing and sintering

[0100] The GQDs@GN / Cu composite powder is placed in a four-column hydraulic machine for pre-pressing, the pressure is 150 MPa, and the pressure holding time is 20 min. The pressed block is placed in a microwave high-temperature vacuum atmosphere furnace and heated to 750°C under a vacuum degree of not more than 10 Pa, and the holding time is 5 min to obtain a GQDs@GN / Cu composite rod;

[0101] (4) Cold extrusion

[0102] The GQDs@GN / Cu composite rod is extruded into a 3 mm diameter wire by a cold extrusion hydraulic machine, and the extrusion pressure is 1400 MPa, thereby obtaining a high-strength and high-conductivity copper-based composite wire.

[0103] Example 6

[0104] A method for efficiently preparing a high-strength and high-conductivity copper-based composite wire, the specific steps are as follows:

[0105] (1) Preparation of GQDs@GN

[0106] 1.0 kg of high-purity copper citrate was rapidly heated to 400°C in a vacuum plasma treatment machine for thermal decomposition, the heating rate was 150°C / min, the thermal decomposition time was 20 min, the vacuum degree was less than 10 Pa, and the generated product was dissolved in deionized water and centrifuged after the vacuum plasma treatment machine was cooled to room temperature. The clear liquid after centrifugation was poured into a dialysis bag with a molecular weight of 5000, the diameter and length of the dialysis bag were 70 mm and 5 m respectively, the dialysis time was 72 h, and finally the GQDs@GN liquid in the dialysis bag was freeze-dried to obtain a large amount of GQDs@GN powder;

[0107] (2) Preparation of GQDs@GN / Cu composite powder

[0108] 100 g of GQDs@GN powder was dispersed by ultrasonic treatment in 10 L of anhydrous ethanol, the ultrasonic power was 960 W, the ultrasonic time was 80 min, and every 10 min was stopped for 2 min; the obtained GQDs@GN mixed liquid was mixed with 10 kg of Cu powder using a horizontal cylindrical rotary device ball mill, the ball milling time was 10 h, the ball milling speed was 500 r / min, the ball-to-material ratio was 10:1, and the ball milling atmosphere was Ar gas. Then the uniformly mixed suspension was filtered and vacuum dried, the drying temperature was 60°C, the drying time was 6 h, the vacuum degree was less than 10 Pa, and a kilogram of GQDs@GN / Cu composite powder was obtained;

[0109] (3) Pre-pressing and sintering

[0110] The GQDs@GN / Cu composite powder was placed in a four-column hydraulic press for pre-pressing, the pressure was 200 MPa, and the pressure holding time was 30 min. The pressed block was placed in a microwave high-temperature vacuum atmosphere furnace and heated to 850°C under a vacuum degree of not more than 10 Pa, and the holding time was 10 min to obtain a GQDs@GN / Cu composite rod;

[0111] (4) Cold extrusion

[0112] The GQDs@GN / Cu composite rod was extruded into a 5 mm diameter wire by a cold extrusion hydraulic press, and the extrusion pressure was 800 MPa, thereby obtaining a high-strength and high-conductivity copper-based composite wire.

[0113] Comparative Example 1

[0114] (1) Preparation of GQDs

[0115] 1.0 kg of iron citrate was heated to 150℃ at a heating rate of 5℃ / min in a tube furnace, the heat decomposition time was 30 min, the vacuum degree was less than 10 Pa, and the tube furnace was naturally cooled to room temperature. The generated product was dissolved in deionized water and centrifuged, and the clarified liquid after centrifugation was poured into a dialysis bag with a molecular weight of 500, a diameter of 70 mm and a length of 5 m. The dialysis time was 10 h, and finally the GQDs liquid in the dialysis bag was freeze-dried to obtain a large amount of GQDs powder;

[0116] (2) Preparation of GQDs / Cu composite powder

[0117] 100 g of GQDs powder was dispersed by ultrasonic treatment in 5 L of anhydrous ethanol, the ultrasonic power was 200 W, the ultrasonic time was 20 min, and every 15 min was stopped for 5 min. The obtained GQDs liquid was mixed with 5 kg of Cu powder using a horizontal cylindrical rotary device ball mill, the ball milling time was 12 h, the ball milling speed was 300 r / min, the ball-to-material ratio was 10:1, and the ball milling atmosphere was Ar gas. Then the uniformly mixed suspension was filtered and vacuum dried, the drying temperature was 60℃, the drying time was 6 h, the vacuum degree was 80 Pa, and the GQDs / Cu composite powder was obtained;

[0118] (3) Pre-pressing and sintering

[0119] The GQDs / Cu composite powder was placed in a hydraulic press for pre-pressing, the pressure was 80 MPa, and the pressure holding time was 5 min. The pressed block was placed in a microwave high-temperature vacuum atmosphere furnace and heated to 500℃ under a vacuum degree of not more than 10 Pa, and the holding time was 15 min. The GQDs / Cu composite rod was obtained;

[0120] (4) Cold extrusion

[0121] The GQDs / Cu composite rod was extruded into a wire with a diameter of 8 mm by a cold extrusion hydraulic press, and the extrusion pressure was 500 MPa.

[0122] Comparative Example 2

[0123] (1) Preparation of GN

[0124] 1.0 kg of citric acid was heated to 500℃ at a heating rate of 10℃ / min in a tube furnace, the holding time was 60 min, the vacuum degree was less than 10 Pa, and the tube furnace was naturally cooled to room temperature. The generated product was dissolved in deionized water and centrifuged, and the clarified liquid after centrifugation was poured into a dialysis bag with a molecular weight of 14000, a diameter of 70 mm and a length of 5 m. The dialysis time was 10 h, and finally the GN liquid in the dialysis bag was freeze-dried to obtain a powder of GN;

[0125] (2) Preparation of GN / Cu composite powder

[0126] 100 g of GN powder was dispersed by ultrasonic treatment in 150 L of anhydrous ethanol, the ultrasonic power was 200 W, the ultrasonic time was 100 min, and it was stopped every 20 min for 1 min. The obtained GN liquid was mixed with 60 kg of Cu powder by using a horizontal cylindrical rotary device ball mill, the ball milling time was 3 h, the ball milling speed was 600 r / min, the ball-to-material ratio was 10:1, and the ball milling atmosphere was N2. Then, the uniformly mixed suspension was filtered and vacuum dried, the drying temperature was 60°C, the drying time was 6 h, the vacuum degree was less than 10 Pa, and GN / Cu composite powder was obtained.

[0127] (3) Pre-pressing and sintering

[0128] The GN / Cu composite powder was placed in a hydraulic press for pre-pressing, the pressure was 300 MPa, and the pressure holding time was 50 min. The pressed block was placed in a microwave high-temperature vacuum atmosphere furnace, heated to 900°C under a vacuum degree of 10 Pa, and held for 15 min to obtain a GN / Cu composite rod.

[0129] (4) Cold extrusion

[0130] The GN / Cu composite rod was extruded into a 1.5 mm diameter wire by a cold extrusion hydraulic press, and the extrusion pressure was 2500 MPa.

[0131] The weight of 1 kg of GQDs@GN generated by thermal decomposition of citric acid or citrate in Example 1, Example 2, Example 3, Example 4, Example 5 and Example 6 is shown in Table 1.

[0132] The mechanical properties of the composite blocks prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were tested, and the test results are shown in Table 2.

[0133] Table 1

[0134]

[0135] Table 2

[0136]

[0137] Figure 1 The TEM (Transmission Electron Microscope) image of GQDs@GN in Example 1 step (1) is shown in the figure. It can be seen that the iron citrate is thermally decomposed to generate wrinkled sheet-shaped GQDs@GN. This characteristic indicates that the number of layers is small.

[0138] Figure 2The SEM (scanning electron microscope) image of the GQDs@GN composite powder in step (2) of Example 1 shows that the GQDs@GN are uniformly dispersed in the copper matrix and form a tight bond with the matrix.

[0139] Figure 3 The TEM image of the GQDs@GN / Cu bulk composite material in step (3) of Example 1 shows that there is no obvious crack and hole at the interface between the GQDs@GN and the copper matrix.

[0140] Figure 4 The local enlarged view of the middle box region of Figure 3 , and the IFFT and FFT are performed on the I and II regions. It can be seen from the figure that CuO is generated in situ at the interface of the GQDs@GN composite material, which further constructs a strong interface.

[0141] Figure 5 The fracture surface SEM image of the GQDs@GN / Cu bulk composite material in step (3) of Example 1 shows that there are broken GQDs@GN Figure 5 a) and bridged GQDs@GN Figure 5 b) on the surface of the GQDs@GN / Cu, which indicates that the GQDs@GN can achieve effective load transfer.

[0142] Figure 6 The TEM image of the GQDs in step (1) of Comparative Example 1 shows that the iron citrate is thermally decomposed at low temperature to generate GQDs of nanometer size.

[0143] Figure 7 The TEM image of the GN in step (1) of Comparative Example 2 shows that the citric acid is thermally decomposed at high temperature to generate GN with many layers.

[0144] According to the results in Table 1 and Figure 1 , it can be seen that the high-quality, high-purity and mass-uniform GQDs@GN can be prepared in one step by using the pyrolysis device with rapid heating, rapid cooling and uniform heating. The method has high yield and simple preparation process.

[0145] According to the test results in Table 2, the strength of the GQDs@GN / Cu composite wire prepared in Example 1, Example 2, Example 3, Example 4, Example 5 and Example 6 is improved to different degrees compared with Comparative Example 1 and Comparative Example 2. This is because the GQDs@GN with fewer layers and uniform quality are successfully prepared by controlling the pyrolysis conditions of citric acid or citrate. During the microwave sintering process, the active oxygen atoms generated by the thermal decomposition of the oxygen-containing functional groups of the GQDs react with copper to form CuO x , and the CuO xThe enhanced interface wettability improves the interface bonding strength of the GQDs@GN / Cu composite wire, the strong interface bonding can fully exert the load transfer capacity of GN and reduce the interface electron scattering, furthermore, the GQDs have excellent and isotropic conductive performance, the GQDs loaded in the longitudinal direction of GN can become the electron transfer channel of the Cu matrix and GN in the longitudinal direction, further enhancing the conductive performance of the Cu composite wire, therefore, the multi-dimensional GQDs@GN prepared by the one-step method can realize the industrialized production of the high-strength and high-conductivity Cu composite wire.

[0146] To sum up, the above is only the preferred embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for efficiently preparing high-strength, high-conductivity copper-based composite wires, characterized in that, The specific steps are as follows: (1) High-purity citric acid or citrate is thermally decomposed in a thermal decomposition device. After cooling to room temperature, the reaction product is dissolved in deionized water, centrifuged, dialyzed and freeze-dried to obtain GQDs@GN powder. (2) GQDs@GN powder was ultrasonically dispersed in anhydrous ethanol. The resulting GQDs@GN mixture was added to Cu powder and ball-milled. The suspension was filtered and vacuum-dried to obtain GQDs@GN / Cu composite powder. (3) GQDs@GN / Cu composite powder is pressed into shape, and the pressed blank is microwave sintered to obtain GQDs@GN / Cu composite rod; (4) GQDs@GN / Cu composite rod is extruded into wire, which is a high-strength and high-conductivity copper-based composite wire.

2. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (1) The citrate is ferric citrate or copper citrate.

3. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (1) The thermal decomposition device is a microwave high-temperature vacuum atmosphere furnace or a plasma device.

4. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 3, characterized in that, Step (1) The thermal decomposition temperature is 200-400℃, the time is 1-20min, the heating rate is 50-150℃ / min, and the vacuum pressure is less than 10Pa.

5. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (1) Use a dialysis bag with a molecular weight of 1000-5000 for dialysis, and the dialysis time is 24-72 hours.

6. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (2) The mass ratio of GQDs@GN powder to anhydrous ethanol is 1:1000 to 1:

100. When ultrasonically dispersing, the ultrasonic power is 300 to 960W per 500 ml of solution, the ultrasonic time is 30 to 80 min, and there is an interval of 1 to 2 min every 5 to 10 min.

7. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (2) The mass ratio of GQDs@GN powder to Cu powder is 0.2:100 to 1:100, the ball milling time is 5 to 10 hours, the ball milling speed is 350 to 500 r / min, the ball-to-material ratio is 10:1, the ball milling medium is anhydrous ethanol, and the ball milling atmosphere is argon or nitrogen.

8. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, The pressure for pressing in step (3) is 100-200 MPa, and the holding time is 10-30 min.

9. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (3) The microwave sintering temperature is 550-850℃, the time is 1-10min, and the vacuum degree is less than 10Pa.

10. The method for efficiently preparing high-strength, high-conductivity copper-based composite wires according to claim 1, characterized in that, Step (4) The extrusion pressure is 800-2000 MPa.

Images