A method for preparing high-quality graphene-copper composite material converted in situ

Abstract

The present invention discloses a method for preparing a high-quality graphene-copper composite material by in-situ conversion, belonging to the technical field of composite material preparation. The present invention comprises: (1) low-temperature chemical vapor deposition; (2) cold pressing; (3) high-temperature hydrogen annealing; and (4) densification sintering. In the graphene-copper composite material prepared by the present invention, the graphene has high crystallinity and does not negatively affect the copper substrate during the preparation process. Therefore, the graphene-copper composite material prepared by the present invention has excellent thermal and electrical conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material preparation, and relates to a method for preparing a high-quality graphene-copper composite material through in-situ conversion. Background Art

[0002] While maintaining the copper matrix's excellent electrical and thermal conductivity and corrosion resistance, copper-based composites improve the matrix's mechanical properties, such as strength, wear resistance, and fatigue resistance. They can further achieve high strength, high conductivity, and high stability, thus holding broad application prospects in key national fields such as electronic communications, integrated circuits, and aerospace. Generally speaking, the reinforcement often exhibits significantly higher performance than the matrix in certain aspects. Its unique structure and properties, as well as its interaction with the metal matrix, collectively influence the composite's overall performance.

[0003] Graphene is sp 2 The two-dimensional atomic crystal with a hexagonal honeycomb structure formed by densely packed carbon atoms has excellent mechanical, electrical, and thermal properties. Its Young's modulus can reach 1.0 TPa, the ideal strength is about 130 GPa, and the carrier mobility can reach 15000 cm 2 ·V -1 ·s -1 The thermal conductivity of single-layer graphene can reach up to 5300 W·m -1 ·K -1 ;Graphene's special planar two-dimensional structure, extremely high specific surface area, and excellent mechanical and functional properties enable it to be used to prepare various functional composite materials based on graphene.

[0004] Highly crystalline graphene has excellent intrinsic electrical, thermal, and mechanical properties, and can significantly improve the overall performance of copper-based composites. In recent years, the in situ synthesis of graphene using copper powder as a catalytic substrate to construct graphene-reinforced copper-based composites has become a research hotspot. The copper-catalyzed growth of highly crystalline graphene is highly dependent on a high-temperature environment above 1000°C. However, at such a high graphene growth temperature, it is difficult for copper powder to maintain its powder form. Therefore, researchers have attempted to use low-temperature catalytic technology to in situ construct graphene-copper composites. However, the results show that the low-temperature environment leads to a large accumulation of amorphous carbon, which limits the overall performance of the copper-based composites.

[0005] Therefore, it is necessary to provide a method for preparing high-quality graphene-copper composite materials by in-situ conversion, maintaining high crystallinity of graphene, reducing the amount of amorphous carbon accumulation, and maintaining relatively excellent comprehensive properties of copper-based composite materials. Summary of the Invention

[0006] To overcome the problems mentioned in the previous article, the present invention utilizes a novel low-temperature chemical vapor deposition (CVD) combined with pre-pressing technology to uniformly embed low-temperature synthesized amorphous graphene-like materials into a copper-based composite. High-temperature hydrogen annealing then transforms the amorphous graphene-like materials in the copper matrix into highly crystalline graphene. Further sintering yields a dense, high-quality graphene-copper composite, effectively improving the electrical and thermal conductivity of the copper-based composite.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] The preparation method comprises the following steps:

[0009] (1) Low-temperature chemical vapor deposition: polystyrene powder is placed in the upstream temperature zone, copper powder is placed in the downstream temperature zone, a mixture of hydrogen and argon is introduced, and the polystyrene powder and copper powder are heated at the same time to obtain a graphene-like / copper composite powder;

[0010] (2) cold pressing: pressing the graphene-like / copper composite powder obtained in step (1) into a non-dense graphene-like / copper composite block;

[0011] (3) high-temperature hydrogen annealing treatment: in a hydrogen and argon mixed gas atmosphere, the graphene-like / copper composite block obtained in step (2) is subjected to high-temperature annealing treatment to obtain a non-dense graphene-copper composite block;

[0012] (4) Densification sintering treatment: sintering the non-dense graphene-copper composite block obtained in step (3) to obtain a dense graphene-copper composite material.

[0013] Preferably, in step (1), the upstream temperature zone and the downstream temperature are simultaneously heated to 300-800°C, kept warm for 90-180 minutes, and the heating rate is 10-30°C / min.

[0014] Preferably, in step (1), the mass ratio of polystyrene powder to copper powder is 0.8-20:1000.

[0015] Preferably, in steps (1) and (3), the flow ratio of hydrogen to argon is 1:1 to 10.

[0016] Preferably, in step (2), the pressing pressure is 3 to 100 MPa, and the holding time is 1 to 10 minutes.

[0017] Preferably, in step (3), the annealing temperature is 900-1070° C., and the holding time is 10-180 min.

[0018] Preferably, in step (4), the sintering method is spark plasma sintering or hot pressing sintering.

[0019] Preferably, the spark plasma sintering has a sintering temperature of 700-900° C., a holding time of 10-20 min, and a sintering pressure of 40-80 MPa.

[0020] Preferably, the sintering temperature of the hot pressing sintering is 800-1000° C., the holding time is 60-150 min, and the sintering pressure is 50-80 MPa.

[0021] Preferably, the polystyrene powder and copper powder have a purity of ≥99.99%, and a powder particle size of 1 to 100 μm.

[0022] The present invention first deposits a layer of amorphous carbon source on the surface of copper powder through low-temperature chemical vapor deposition. The amorphous carbon source is then uniformly added to a copper composite block through cold pressing. The pre-deposited amorphous carbon source in the copper block is then converted into highly crystalline graphene through high-temperature hydrogen annealing, resulting in a non-dense graphene-copper bulk material. Finally, a dense graphene-copper composite material is obtained through a sintering process. During the high-temperature hydrogen annealing process, hydrogen diffuses into the non-dense copper block. The etching effect of hydrogen on the amorphous carbon and the catalytic crystallization effect of the copper matrix on the amorphous carbon jointly promote the conversion of the amorphous carbon to graphene, ultimately achieving high crystallinity.

[0023] Beneficial effects of the present invention:

[0024] 1. The preparation method of the present invention effectively solves the contradiction between the high-temperature growth of high-crystallinity graphene and the easy agglomeration and adhesion of copper powder at high temperatures. That is, it ensures that the prepared graphene-copper composite material has graphene with high crystallinity and avoids the large accumulation of amorphous carbon. At the same time, it also ensures that the copper powder has a good powder morphology, ultimately making the composite material have better comprehensive performance.

[0025] 2. The graphene-copper composite material prepared by the present invention has excellent electrical and thermal properties. Its electrical conductivity can reach 100.6% IACS and its thermal conductivity can reach 433Wm -1 K -1 .

[0026] 3. The raw materials of the present invention are widely available and inexpensive, which is beneficial to reducing the production cost of the graphene-copper composite material. In addition, the prepared graphene-copper composite material is relatively stable and convenient to store. Therefore, the preparation method of the present invention is suitable for industrial promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the preparation method of the present invention;

[0028] Figure 2Graphs showing the test results of amorphous graphene synthesized by low-temperature chemical vapor deposition according to the present invention, wherein a is a scanning electron microscope image, b is a transmission electron microscope image, c is a Raman spectrum, and b1 is a selected area electron diffraction pattern;

[0029] Figure 3 These are the test results of high-crystallinity graphene obtained through high-temperature hydrogen annealing, where a is the transmission electron microscope image, b is the selected area electron diffraction pattern, and c is the Raman spectrum. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to specific embodiments.

[0031] In the examples and comparative examples of the present invention, chemical reagents not otherwise specified were all commercially available analytically pure for use in the experiments.

[0032] Example 1

[0033] In this embodiment, a graphene-copper composite material is prepared according to the following steps:

[0034] (1) Low-temperature chemical vapor deposition: 80 mg of polystyrene powder was placed in the upstream temperature zone of a dual-zone tubular furnace, and 20 g of copper powder was placed in the downstream temperature zone of the dual-zone tubular furnace. A mixture of high-purity hydrogen and high-purity argon was introduced into the furnace, wherein the high-purity hydrogen flow rate was 20 sccm and the high-purity argon flow rate was 150 sccm. The upstream and downstream temperature zones were simultaneously heated to 500°C within 30 minutes and kept warm for 90 minutes to obtain a graphene-like / copper composite powder.

[0035] (2) Cold pressing: about 20 g of the graphene-like / copper composite powder obtained in step (1) was placed in a cylindrical stainless steel mold and subjected to a cold pressing pressure of 3 MPa and a holding time of 1 min to obtain a non-dense graphene-like / copper composite block;

[0036] (3) High-temperature hydrogen annealing treatment: The non-dense graphene-like / copper composite block obtained in step (2) is placed in a tubular furnace, and a mixed gas of high-purity hydrogen and high-purity argon is introduced into the furnace for high-temperature annealing treatment, wherein the high-purity hydrogen flow rate is 20 sccm, the high-purity argon flow rate is 150 sccm, the annealing temperature is 1050°C, and the holding time is 35 min to obtain a non-dense graphene-copper composite block;

[0037] (4) Densification sintering treatment: The non-dense graphene-copper composite block obtained in step (3) was subjected to spark plasma sintering with a heating rate of 100°C / min, a sintering temperature of 750°C, a holding time of 10 min, and a sintering pressure of 50 MPa to obtain a dense high-quality graphene-copper composite block material with an electrical conductivity of 100.6% IACS and a thermal conductivity of 433 Wm -1 K-1 .

[0038] Comparative Example 1

[0039] In this comparative example, a graphene-copper composite material was prepared using the same method as in Example 1, except that the annealing temperature in this comparative example was 600° C. The electrical conductivity of the graphene-copper composite bulk material prepared in this comparative example was 91% IACS.

[0040] By comparing Example 1 with Comparative Example 1, it can be seen that the electrical conductivity of the composite material in Comparative Example 1 decreases significantly, mainly because a large amount of amorphous carbon accumulates at low temperatures, which has a negative impact on the performance of the composite material.

[0041] Example 2

[0042] In this embodiment, a graphene-copper composite material is prepared according to the following steps:

[0043] (1) Low-temperature chemical vapor deposition: 400 mg of polystyrene powder was placed in the upstream temperature zone of a dual-zone tubular furnace, and 40 g of copper powder was placed in the downstream temperature zone of the dual-zone tubular furnace. A mixture of high-purity hydrogen and high-purity argon was introduced into the furnace, wherein the high-purity hydrogen flow rate was 20 sccm and the high-purity argon flow rate was 200 sccm. The upstream and downstream temperature zones were simultaneously heated to 800°C within 50 minutes and kept warm for 120 minutes to obtain a graphene-like / copper composite powder.

[0044] (2) Cold pressing: about 40 g of the graphene-like / copper composite powder obtained in step (1) was placed in a cylindrical stainless steel mold and subjected to a cold pressing pressure of 20 MPa and a holding time of 10 min to obtain a non-dense graphene-like / copper composite block;

[0045] (3) High-temperature hydrogen annealing treatment: The non-dense graphene-like / copper composite block obtained in step (2) is placed in a tubular furnace, and a mixed gas of high-purity hydrogen and high-purity argon is introduced into the furnace for high-temperature annealing treatment, wherein the high-purity hydrogen flow rate is 30 sccm, the high-purity argon flow rate is 200 sccm, the annealing temperature is 1070°C, and the holding time is 60 min to obtain a non-dense graphene-copper composite block;

[0046] (4) Densification sintering treatment: The non-dense graphene-copper composite block obtained in step (3) was hot-pressed and sintered at a heating rate of 50°C / min, a sintering temperature of 800°C, a holding time of 60min, and a sintering pressure of 50MPa to obtain a dense, high-quality graphene-copper composite block material with an electrical conductivity of 98% IACS.

[0047] Example 3

[0048] In this embodiment, a graphene-copper composite material is prepared according to the following steps:

[0049] (1) Low-temperature chemical vapor deposition: 200 mg of polystyrene powder was placed in the upstream temperature zone of a dual-zone tubular furnace, and 20 g of copper powder was placed in the downstream temperature zone of the dual-zone tubular furnace. A mixture of high-purity hydrogen and high-purity argon was introduced into the furnace, wherein the high-purity hydrogen flow rate was 50 sccm and the high-purity argon flow rate was 300 sccm. The upstream and downstream temperature zones were simultaneously heated to 600°C within 30 minutes and kept warm for 100 minutes to obtain a graphene-like / copper composite powder;

[0050] (2) Cold pressing: about 20 g of the graphene-like / copper composite powder obtained in step (1) was placed in a cylindrical stainless steel mold and subjected to a cold pressing pressure of 10 MPa and a holding time of 10 min to obtain a non-dense graphene-like / copper composite block;

[0051] (3) High-temperature hydrogen annealing treatment: the non-dense graphene-like / copper composite block obtained in step (2) is placed in a tubular furnace, and a mixed gas of high-purity hydrogen and high-purity argon is introduced into the furnace for high-temperature annealing treatment, wherein the high-purity hydrogen flow rate is 100 sccm, the high-purity argon flow rate is 400 sccm, the annealing temperature is 1000°C, and the holding time is 40 min to obtain a non-dense graphene-copper composite block;

[0052] (4) Densification sintering treatment: The non-dense graphene-copper composite block obtained in step (3) was subjected to spark plasma sintering with a heating rate of 100°C / min, a sintering temperature of 800°C, a holding time of 10 min, and a sintering pressure of 50 MPa to obtain a dense, high-quality graphene-copper composite block material with an electrical conductivity of 99% IACS.

[0053] Example 4

[0054] In this embodiment, a graphene-copper composite material is prepared according to the following steps:

[0055] (1) Low-temperature chemical vapor deposition: 8 mg of polystyrene powder was placed in the upstream temperature zone of a dual-temperature zone tubular furnace, and 10 g of copper powder was placed in the downstream temperature zone of the dual-temperature zone tubular furnace. A mixture of high-purity hydrogen and high-purity argon was introduced into the furnace, wherein the high-purity hydrogen flow rate was 100 sccm and the high-purity argon flow rate was 100 sccm. The upstream and downstream temperature zones were simultaneously heated to 300°C within 30 minutes and kept warm for 180 minutes to obtain a graphene-like / copper composite powder;

[0056] (2) Cold pressing: about 10 g of the graphene-like / copper composite powder obtained in step (1) was placed in a cylindrical stainless steel mold and subjected to a cold pressing pressure of 100 MPa and a holding time of 5 min to obtain a non-dense graphene-like / copper composite block;

[0057] (3) High-temperature hydrogen annealing treatment: the non-dense graphene-like / copper composite block obtained in step (2) is placed in a tubular furnace, and a mixed gas of high-purity hydrogen and high-purity argon is introduced into the furnace for high-temperature annealing treatment, wherein the flow rate of high-purity hydrogen is 100 sccm, the flow rate of high-purity argon is 100 sccm, the annealing temperature is 900°C, and the holding time is 180 min to obtain a non-dense graphene-copper composite block;

[0058] (4) Densification sintering treatment: The non-dense graphene-copper composite block obtained in step (3) was hot-pressed and sintered at a heating rate of 50°C / min, a sintering temperature of 1000°C, a holding time of 150 min, and a sintering pressure of 80 MPa to obtain a dense, high-quality graphene-copper composite block material. The properties of the graphene-copper composite block material prepared in this example were similar to those in Example 2.

[0059] Example 5

[0060] In this embodiment, a graphene-copper composite material is prepared according to the following steps:

[0061] (1) Low-temperature chemical vapor deposition: 20 mg of polystyrene powder was placed in the upstream temperature zone of a two-zone tubular furnace, and 1 g of copper powder was placed in the downstream temperature zone of the two-zone tubular furnace. A mixture of high-purity hydrogen and high-purity argon was introduced into the furnace, with a high-purity hydrogen flow rate of 30 sccm and a high-purity argon flow rate of 300 sccm. The upstream and downstream temperature zones were simultaneously heated to 600°C within 20 minutes and kept warm for 120 minutes to obtain a graphene-like / copper composite powder.

[0062] (2) Cold pressing: about 1 gram of the graphene-like / copper composite powder obtained in step (1) was placed in a cylindrical stainless steel mold and subjected to a cold pressing pressure of 80 MPa and a holding time of 3 minutes to obtain a non-dense graphene-like / copper composite block;

[0063] (3) High-temperature hydrogen annealing treatment: The non-dense graphene-like / copper composite block obtained in step (2) is placed in a tubular furnace, and a mixed gas of high-purity hydrogen and high-purity argon is introduced into the furnace for high-temperature annealing treatment, wherein the flow rate of high-purity hydrogen is 30 sccm, the flow rate of high-purity argon is 300 sccm, the annealing temperature is 1070°C, and the holding time is 10 min to obtain a non-dense graphene-copper composite block;

[0064] (4) Densification Sintering Treatment: The non-dense graphene-copper composite bulk obtained in step (3) was subjected to spark plasma sintering at a heating rate of 100°C / min, a sintering temperature of 900°C, a holding time of 20 min, and a sintering pressure of 80 MPa to obtain a dense, high-quality graphene-copper composite bulk material. The properties of the graphene-copper composite bulk material prepared in this example were similar to those in Example 3.

[0065] Example 6

[0066] In this embodiment, a graphene-copper composite material is prepared according to the following steps:

[0067] (1) Low-temperature chemical vapor deposition: 80 mg of polystyrene powder was placed in the upstream temperature zone of a dual-zone tubular furnace, and 20 g of copper powder was placed in the downstream temperature zone of the dual-zone tubular furnace. A mixture of high-purity hydrogen and high-purity argon was introduced into the furnace, wherein the high-purity hydrogen flow rate was 20 sccm and the high-purity argon flow rate was 150 sccm. The upstream and downstream temperature zones were simultaneously heated to 500°C within 30 minutes and kept warm for 90 minutes to obtain a graphene-like / copper composite powder.

[0068] (2) Cold pressing: about 20 g of the graphene-like / copper composite powder obtained in step (1) was placed in a cylindrical stainless steel mold and subjected to a cold pressing pressure of 3 MPa and a holding time of 1 min to obtain a non-dense graphene-like / copper composite block;

[0069] (3) High-temperature hydrogen annealing treatment: The non-dense graphene-like / copper composite block obtained in step (2) is placed in a tubular furnace, and a mixed gas of high-purity hydrogen and high-purity argon is introduced into the furnace for high-temperature annealing treatment, wherein the high-purity hydrogen flow rate is 20 sccm, the high-purity argon flow rate is 150 sccm, the annealing temperature is 1050°C, and the holding time is 35 min to obtain a non-dense graphene-copper composite block;

[0070] (4) Densification sintering treatment: The non-dense graphene-copper composite block obtained in step (3) is subjected to spark plasma sintering with a heating rate of 100°C / min, a sintering temperature of 750°C, a holding time of 15 min, and a sintering pressure of 40 MPa to obtain a dense, high-quality graphene-copper composite block material. The performance of the graphene-copper composite block material prepared in this embodiment is similar to that of Example 1.

[0071] pass Figure 2 a and Figure 2 b It can be seen that the substance synthesized on the surface of the copper powder of the present invention has a similar but not identical morphology to typical graphene, which proves that the present invention synthesizes graphene-like substances on the surface of the copper powder by low-temperature chemical vapor deposition.

[0072] pass Figure 2 As can be seen from b1, there are no diffraction spots on the selected area electron diffraction pattern, indicating that the graphene-like material prepared in the intermediate process of the present invention is in an amorphous state, and the carbon atoms are arranged in a short-range order but a long-range disorder.

[0073] pass Figure 2c It can be seen that the Raman spectrum of the graphene-like material prepared in the intermediate process of the present invention is basically consistent with the Raman spectrum of the widely reported amorphous carbon, which once again shows that the graphene-like material is in an amorphous state.

[0074] pass Figure 3 a A typical transmission electron microscope image of graphene can be seen, proving that the present invention successfully prepared the graphene-copper composite material.

[0075] pass Figure 3 b Obvious hexagonal diffraction spots can be seen, proving that the graphene in the composite material prepared by the present invention has a high degree of crystallinity.

[0076] pass Figure 3 c shows a typical high-quality graphene Raman spectrum, where the lower intensity D peak also proves that the graphene defect program is smaller.

[0077] In summary, the method of the present invention can prepare a highly crystallized graphene-copper composite material without causing copper powder to agglomerate or adhere at high temperatures, thereby affecting the performance of the composite material. Therefore, the graphene-copper composite material prepared by the method of the present invention has high electrical conductivity and thermal conductivity, and good overall performance.

Claims

1. A method for preparing a high-quality graphene-copper composite material by in-situ conversion, characterized in that: The preparation method comprises the following steps: (1) Low-temperature chemical vapor deposition: polystyrene powder is placed in the upstream temperature zone, copper powder is placed in the downstream temperature zone, a mixture of hydrogen and argon is introduced, and the polystyrene powder and copper powder are heated at the same time to obtain a graphene-like / copper composite powder; (2) cold pressing: pressing the graphene-like / copper composite powder obtained in step (1) into a non-dense graphene-like / copper composite block; (3) high-temperature hydrogen annealing treatment: in a hydrogen and argon mixed gas atmosphere, the graphene-like / copper composite block obtained in step (2) is subjected to high-temperature annealing treatment to obtain a non-dense graphene-copper composite block; (4) Densification sintering treatment: sintering the non-dense graphene-copper composite block obtained in step (3) to obtain a dense graphene-copper composite material.

2. The preparation method according to claim 1, wherein: In the step (1), the upstream temperature zone and the downstream temperature are simultaneously heated to 300-800° C., kept warm for 90-180 minutes, and the heating rate is 10-30° C. / min.

3. The preparation method according to claim 1, wherein: In the step (1), the mass ratio of polystyrene powder to copper powder is 0.8-20:1000.

4. The preparation method according to claim 1, wherein: In the steps (1) and (3), the flow ratio of hydrogen to argon is 1:1-10.

5. The preparation method according to claim 1, wherein: In the step (2), the pressing pressure is 3 to 100 MPa, and the holding time is 1 to 10 minutes.

6. The preparation method according to claim 1, wherein: In the step (3), the annealing temperature is 900-1070° C., and the holding time is 10-180 minutes.

7. The preparation method according to claim 1, wherein: In the step (4), the sintering method is spark plasma sintering or hot pressing sintering.

8. The preparation method according to claim 7, characterized in that: The spark plasma sintering has a sintering temperature of 700-900° C., a heat preservation time of 10-20 minutes, and a sintering pressure of 40-80 MPa.

9. The preparation method according to claim 7, characterized in that: The sintering temperature of the hot pressing sintering is 800-1000° C., the holding time is 60-150 minutes, and the sintering pressure is 50-80 MPa.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The polystyrene powder and copper powder have purities of ≥99.99% and a powder particle size of 1 to 100 μm.

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