Anti-graphitization copper-based alloy-diamond composite material and preparation method thereof

Abstract

The invention discloses an anti-graphitization copper-based alloy-diamond composite material and a preparation method thereof, and relates to the technical field of preparation of copper-based composite materials. The modified diamond particles are prepared by constructing a gradient nano-twin layer with gradually decreased radial twin density on the surface of the diamond particles and generating an amorphous carbon buffer layer on the outermost layer of the nano-twin layer in situ; and then the modified diamond particles are compounded into a copper-based alloy matrix, the copper-based alloy-diamond composite material is prepared, and the heat conduction performance of the copper-based alloy-diamond composite material and the anti-graphitization effect of the copper-based alloy-diamond composite material under high-temperature sintering are jointly improved. The copper-based alloy-diamond composite material can be widely applied to the fields of aerospace heat management parts, high-power electronic device heat dissipation modules, heat conduction structural parts under the high-temperature working condition and the like.

Description

Technical Field

[0001] This application relates to the field of copper-based composite material preparation technology, and in particular to a graphitization-resistant copper-based alloy-diamond composite material and its preparation method. Background Technology

[0002] Copper-based alloy-diamond composites benefit from the excellent machinability of the copper-based alloy matrix and the high W / (m²) of diamond. Diamond's theoretical thermal conductivity (K) plays a crucial role in high-end thermal management applications such as 5G base station heat dissipation modules, high-power LED packaging, and integrated circuit chip cooling. However, in the conventional high-temperature sintering process, due to the significant differences in physical and chemical properties between diamond and copper-based alloy matrices, several technical challenges remain: on the one hand, poor interfacial wettability and mismatch in thermal expansion coefficients can easily lead to insufficient interfacial bonding strength; on the other hand, at high temperatures, carbon atoms in diamond undergo rearrangement, resulting in graphitization transformation, which causes a sharp drop in the thermal conductivity and deterioration of mechanical properties of the composite material, becoming a major obstacle to industrial applications. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a graphitization-resistant copper-based alloy-diamond composite material and its preparation method. By constructing a gradient nanotwin layer with decreasing radial twin density on the surface of diamond particles, and generating an amorphous carbon buffer layer in situ on the outermost layer of the twin layer, and then compositing the modified diamond particles into a copper-based alloy matrix, a copper-based alloy-diamond composite material is obtained. This achieves a combined improvement in the thermal conductivity and graphitization resistance of the copper-based alloy-diamond composite material under high-temperature sintering.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] In a first aspect, this application provides a graphitization-resistant copper-based alloy-diamond composite material, the composite material comprising copper-based alloy matrix powder and modified diamond particles; the modified diamond particles are prepared by sequentially depositing a gradient nanotwin layer and an amorphous carbon buffer layer on the surface of the diamond particles from bottom to top; the gradient nanotwin layer is radially decreasing along the surface of the diamond particles; the amorphous carbon buffer layer is generated in situ on the outer layer of the gradient nanotwin layer.

[0006] This application utilizes a gradient nanotwin layer and an amorphous carbon buffer layer constructed on the surface of diamond particles. The radial decrease in twin density within the gradient nanotwin layer and the further deposition of amorphous carbon in the amorphous carbon buffer layer not only prevent the diffusion and rearrangement of carbon atoms in the diamond during high-temperature processing and suppress graphitization during the preparation process, but also maintain the high thermal conductivity and good mechanical properties of the resulting copper-based alloy-diamond composite material. Furthermore, both layers together constitute a transition phase, alleviating problems such as thermal stress concentration and thermal expansion coefficient mismatch at the interface between the diamond particles and the copper-based alloy matrix during high-temperature preparation. In addition, the combination of these two elements enhances the interfacial wettability and bonding force between the copper-based alloy matrix and the diamond particles, promoting interfacial adhesion.

[0007] In one possible implementation, the copper-based alloy matrix powder comprises copper, chromium, and tin; the mass ratio of copper, chromium, and tin is (97.2-99.3):(0.5-2.0):(0.2-0.8).

[0008] In this application, the composition and proportion of the copper-based alloy matrix powder can improve the interfacial bonding stability between the copper-based alloy matrix powder and the modified diamond particles, maintaining good formability while ensuring high thermal conductivity. Chromium, during high-temperature preparation, can react with carbon in the amorphous carbon buffer layer and gradient nanotwin layer to generate carbides such as Cr3C2, thereby enhancing the interfacial bonding strength between the copper-based alloy matrix powder and the modified diamond particles. The presence of tin can lower the processing temperature of the copper-based alloy matrix powder, thereby reducing the impact of high temperatures on the graphitization of the modified diamond particles and achieving an auxiliary effect in inhibiting graphitization.

[0009] In one possible implementation, the copper-based alloy matrix powder may also be replaced by aluminum-based alloy matrix powder or silver-based alloy matrix powder.

[0010] In one possible implementation, the aluminum-based alloy matrix powder comprises aluminum, titanium, and zirconium; the mass ratio of aluminum, titanium, and zirconium is (98.3-99.6):(0.3-1.2):(0.1-0.5).

[0011] In one possible implementation, the composition of the silver-based alloy matrix powder includes silver, indium, and gallium; the mass ratio of silver, indium, and gallium is (99.1-99.85):(0.1-0.6):(0.05-0.3).

[0012] In one possible implementation, the mass ratio of the copper-based alloy matrix powder to the modified diamond particles is (45-75):(25-55).

[0013] The mass ratio of copper-based alloy matrix powder and modified diamond particles provided in this application can ensure the thermal conductivity of the prepared copper-based alloy-diamond composite material, while avoiding the problems of excessive modified diamond particles causing agglomeration or insufficient copper-based alloy matrix powder failing to fill the gaps between modified diamond particles. This ensures the structural integrity and good mechanical properties of the prepared copper-based alloy-diamond composite material.

[0014] In one possible implementation, the copper-based alloy matrix powder has an average particle size of 1-50 μm, and the modified diamond particles have an average particle size of 100-200 μm.

[0015] In this application, the modified diamond particles have a larger particle size, serving as a thermally conductive framework; the copper-based alloy matrix powder has a smaller particle size and a larger specific surface area, resulting in a larger contact area with the modified diamond particles. Therefore, atomic diffusion is more complete during the molding process, and the interfacial bonding between the two is tighter. At the same time, the smaller particle size of the copper-based alloy matrix powder has better flowability, which can improve the mixing uniformity of the prepared copper-based alloy-diamond composite material and avoid performance fluctuations caused by too many or too few modified diamond particles in certain areas.

[0016] In one possible implementation, the thickness of the gradient nanotwin layer is 0.5–3 μm, and the twin density is 102. 6 -10 8 cm -2 The gradient slope is 0.3–0.8 μm. -1 The thickness of the amorphous carbon buffer layer is 2–3 nm.

[0017] Secondly, this application provides a method for preparing a graphitization-resistant copper-based alloy-diamond composite material, comprising the following steps:

[0018] S1. Place diamond particles in a nitric acid solution with a volume fraction of 5-10%, stir at 60-80℃ for 1-2 hours, wash with deionized water until the pH is 6.5-7.5, and then vacuum dry at 100-120℃ for 3-5 hours to obtain pretreated diamond particles.

[0019] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce the reaction gas, set the deposition temperature to 700-900℃ and the pressure to 1-5Pa, and deposit a gradient nanotwin layer on the surface of the diamond particles by gradient adjustment of the radio frequency power for a deposition time of 2-6 hours.

[0020] S3. Subsequently, the volume fraction of methane in the reaction gas was adjusted, the deposition temperature was lowered to 400-500℃, the pressure was maintained at 1-5Pa, and the temperature was kept for 0.5-1.5h. An amorphous carbon buffer layer was generated in situ on the outer layer of the gradient nanotwin layer, thus obtaining modified diamond particles.

[0021] S4. Weigh out the copper-based alloy matrix powder and modified diamond particles according to the ratio, mechanically mix them at a rate of 300-500 rpm for 30-60 minutes, and then form them using powder metallurgy or hot isostatic pressing to obtain the graphitization-resistant copper-based alloy-diamond composite material.

[0022] In step S1, the pretreatment of diamond particles can improve the bonding force between the subsequently deposited gradient nanotwin layer and the surface of the diamond particles; in step S2, the deposition temperature of less than 1000℃ can deposit the gradient nanotwin layer while minimizing the graphitization of diamond particles caused by high temperature; in step S3, by adjusting the methane ratio and controlling the cooling rate of the deposition temperature, excessive stress concentration is avoided, thereby obtaining an amorphous carbon buffer layer with a tight interface with the gradient nanotwin layer.

[0023] In one possible implementation, in S2, the reactant gas is a mixture of methane and hydrogen, wherein the volume fraction of methane is 5-15%; the radio frequency power ranges from 100-300W; and the gradient adjustment rate of the radio frequency power is 20-50W / h.

[0024] In one possible implementation, in S3, the volume fraction of methane is adjusted to 20-30%; the deposition temperature decreases at a rate of 1-2 °C / min.

[0025] In one possible implementation, the parameters of the powder metallurgy process in S4 include: pressure 50-150 MPa, temperature 550-900℃, and holding time 2-4 h.

[0026] In one possible implementation, the parameters of the hot isostatic pressing process in S4 include: pressure 100-200MPa, temperature 600-950℃, and holding time 1-3h.

[0027] Beneficial technical effects:

[0028] This application describes a modified diamond particle fabrication process. The modified diamond particle is prepared by constructing a gradient nanotwin layer with decreasing radial twin density on the surface of diamond particles and generating an amorphous carbon buffer layer in situ on the outermost layer of this layer. The modified diamond particle is then composited into a copper-based alloy matrix to obtain a copper-based alloy-diamond composite material. The gradient nanotwin layer and the amorphous carbon buffer layer on the diamond particle surface work together. The radial decrease in twin density in the gradient nanotwin layer and the further deposition of amorphous carbon in the amorphous carbon buffer layer not only prevent the diffusion and rearrangement of carbon atoms in the diamond during high-temperature processing and inhibit graphitization during the preparation process, but also maintain the high thermal conductivity and good mechanical properties of the resulting copper-based alloy-diamond composite material. Furthermore, both layers together constitute a transition phase, alleviating problems such as thermal stress concentration and thermal expansion coefficient mismatch at the interface between the diamond particle and the copper-based alloy matrix during high-temperature preparation. The combined effect also improves the interfacial wettability and interfacial bonding force between the copper-based alloy matrix and the diamond particles, promoting interfacial bonding. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the modified diamond particles provided in this application.

[0030] Figure 2 This is a physical image of the graphitization-resistant copper-based alloy-diamond composite material prepared in Example 1 of this application.

[0031] Figure 3 This is a schematic diagram of the preparation process of the graphitization-resistant copper-based alloy-diamond composite material provided in this application.

[0032] Explanation of reference numerals in the attached figures: 1. Surface of diamond particles; 2. Gradient nanotwin layer; 3. Amorphous carbon buffer layer. Detailed Implementation

[0033] To facilitate understanding of the content described in this application, the technical solutions described herein are further explained below with reference to specific embodiments; however, this application is not limited thereto. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the protection scope of this application.

[0034] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0035] The following describes in detail, with reference to different embodiments, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material provided in this application, and the spraying process of the graphitization-resistant copper-based alloy-diamond composite material obtained in each embodiment.

[0036] Example 1

[0037] like Figure 3 As shown, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0038] S1. Place diamond particles in a 5% (v / v) nitric acid solution, stir at 80°C for 1 hour, wash with deionized water until pH 6.5, and then vacuum dry at 100°C for 5 hours to obtain pretreated diamond particles.

[0039] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 5%, hydrogen volume fraction 95%), set the deposition temperature to 900℃ and the pressure to 1 Pa, and gradually adjust the RF power within a gradient range of 100-300 W at a rate of 20 W / h to deposit a 0.5 μm thick layer with a twin density of 10 on the surface of the diamond particles. 6 cm -2 The gradient slope is 0.3 μm -1 The deposition time for the gradient nanotwin layer 2 was 2 hours;

[0040] S3. Subsequently, the volume fraction of methane was adjusted to 20%, and the hydrogen gas integral was 80%. The deposition temperature was reduced to 400℃ at a rate of 2℃ / min, and the pressure was maintained at 1Pa for 0.5h. An amorphous carbon buffer layer 3 with a thickness of 2nm was generated in situ on the outer layer of the gradient nanotwinned layer 2, thus obtaining modified diamond particles with an average particle size of 100μm. Its structure is as follows. Figure 1 As shown;

[0041] S4. Weigh out copper-based alloy matrix powder and modified diamond particles at a mass ratio of 45:55, mechanically mix at 500 rpm for 30 minutes, and then form using powder metallurgy (process parameters include: pressure 150 MPa, temperature 550℃, holding time 2 h) to obtain a graphitization-resistant copper-based alloy-diamond composite material. The physical sample is shown below. Figure 2 As shown;

[0042] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 97.2:2.0:0.8.

[0043] Example 2

[0044] like Figure 3 As shown, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0045] S1. Place diamond particles in a 10% (v / v) nitric acid solution, stir at 60°C for 2 hours, wash with deionized water until pH 7.5, and then vacuum dry at 120°C for 3 hours to obtain pretreated diamond particles.

[0046] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 15%, hydrogen volume fraction 85%), set the deposition temperature to 700℃ and the pressure to 5Pa, and gradually adjust the RF power within a gradient range of 100-300W at a rate of 50W / h to deposit a 3μm thick layer with a twin density of 10 on the surface of the diamond particles. 8 cm -2 The gradient slope is 0.8 μm -1 The gradient nanotwin layer 2 was deposited over a time of 6 hours.

[0047] S3. Subsequently, the volume fraction of methane was adjusted to 30%, and the hydrogen gas integral was 70%. The deposition temperature was reduced to 500℃ at a rate of 1℃ / min, and the pressure was maintained at 5Pa for 1.5h. An amorphous carbon buffer layer 3 with a thickness of 3nm was generated in situ on the outer layer of the gradient nanotwinned layer 2, thus obtaining modified diamond particles with an average particle size of 200μm. Its structure is as follows. Figure 1 As shown;

[0048] S4. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 75:25, mechanically mix them at a rate of 300 rpm for 60 min, and then form them using powder metallurgy (process parameters include: pressure 50 MPa, temperature 900 ℃, and holding time 4 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0049] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 99.3:0.5:0.2.

[0050] Example 3

[0051] like Figure 3 As shown, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0052] S1. Place diamond particles in an 8% (v / v) nitric acid solution, stir at 80°C for 1.2 h, wash with deionized water until pH 7.0, and then vacuum dry at 100°C for 4 h to obtain pretreated diamond particles.

[0053] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 10%, hydrogen volume fraction 90%), set the deposition temperature to 700℃ and the pressure to 5Pa, and gradually adjust the RF power within a gradient range of 100-300W at a rate of 35W / h to deposit a 2.5μm thick layer with a twin density of 5×10⁻⁶ on the surface of the diamond particles. 7 cm -2 The gradient slope is 0.5 μm -1 The gradient nanotwin layer 2 was deposited over a time of 5 hours.

[0054] S3. Subsequently, the volume fraction of methane was adjusted to 25%, and the hydrogen gas integral was 75%. The deposition temperature was reduced to 450℃ at a rate of 2℃ / min, and the pressure was maintained at 5Pa for 1 hour. An amorphous carbon buffer layer 3 with a thickness of 2.5nm was generated in situ on the outer layer of the gradient nanotwinned layer 2, thus obtaining modified diamond particles with an average particle size of 150μm. Its structure is as follows. Figure 1 As shown;

[0055] S4. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 60:40, mechanically mix them at a rate of 400 rpm for 35 min, and then form them by hot isostatic pressing (process parameters include: pressure 200 MPa, temperature 600 ℃, and holding time 2 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0056] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 98.5:1.2:0.3.

[0057] Example 4

[0058] like Figure 3 As shown, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0059] S1. Place diamond particles in a 6% (v / v) nitric acid solution and stir at 70°C for 1.8 h. After washing with deionized water until the pH reaches 6.8, dry under vacuum at 110°C for 3.5 h to obtain pretreated diamond particles.

[0060] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 7%, hydrogen volume fraction 93%), set the deposition temperature to 800℃ and the pressure to 2Pa, and gradually adjust the RF power within a gradient range of 100-300W at a rate of 25W / h to deposit a 1.5μm thick layer with a twin density of 3×10⁻⁶ on the surface of the diamond particles. 6 cm-2 The gradient slope is 0.4 μm -1 The gradient nanotwin layer 2 was deposited over a time of 3.5 hours.

[0061] S3. Subsequently, the volume fraction of methane was adjusted to 22%, and the hydrogen gas integral was 78%. The deposition temperature was reduced to 500℃ at a rate of 1℃ / min, and the pressure was maintained at 2Pa ​​for 0.8h. An amorphous carbon buffer layer 3 with a thickness of 2.8nm was generated in situ on the outer layer of the gradient nanotwinned layer 2, thus obtaining modified diamond particles with an average particle size of 120μm. Its structure is as follows. Figure 1 As shown;

[0062] S4. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 50:50, mechanically mix them at a rate of 300 rpm for 50 min, and then form them using powder metallurgy (process parameters include: pressure 120 MPa, temperature 650 ℃, and holding time 3 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0063] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 98.0:1.5:0.5.

[0064] Example 5

[0065] like Figure 3 As shown, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0066] S1. Place diamond particles in a 9% (v / v) nitric acid solution, stir at 80°C for 1.5 h, wash with deionized water until pH 7.2, and then vacuum dry at 100°C for 4.5 h to obtain pretreated diamond particles.

[0067] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 13%, hydrogen volume fraction 87%), set the deposition temperature to 750℃ and the pressure to 3Pa, and gradually adjust the RF power within a gradient range of 100-300W at a rate of 40W / h to deposit a 2μm thick layer with a twin density of 8×10⁻⁶ on the surface of the diamond particles. 7 cm -2 The gradient slope is 0.7 μm -1 The gradient nanotwin layer 2 was deposited over a time of 4.5 hours.

[0068] S3. Subsequently, the volume fraction of methane was adjusted to 28%, and the hydrogen gas integral was 72%. The deposition temperature was reduced to 400℃ at a rate of 1.5℃ / min, and the pressure was maintained at 3Pa for 1.2h. An amorphous carbon buffer layer 3 with a thickness of 2nm was generated in situ on the outer layer of the gradient nanotwinned layer 2, thus obtaining modified diamond particles with an average particle size of 180μm. Its structure is as follows. Figure 1 As shown;

[0069] S4. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 70:30, mechanically mix them at a rate of 450 rpm for 40 min, and then form them by hot isostatic pressing (process parameters include: pressure 100 MPa, temperature 950 ℃, and holding time 1 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0070] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 99.0:0.7:0.3.

[0071] Example 6

[0072] like Figure 3 As shown, a method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0073] S1. Place diamond particles in a 7% (v / v) nitric acid solution, stir at 60°C for 2 hours, wash with deionized water until pH 7.0, and then vacuum dry at 120°C for 4 hours to obtain pretreated diamond particles.

[0074] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 11%, hydrogen volume fraction 89%), set the deposition temperature to 850℃ and the pressure to 4Pa, and gradually adjust the RF power within a gradient range of 100-300W at a rate of 30W / h to deposit a 1.5μm thick layer with a twin density of 6×10⁻⁶ on the surface of the diamond particles. 7 cm -2 The gradient slope is 0.6 μm -1 The gradient nanotwin layer 2 was deposited over a time of 5 hours.

[0075] S3. Subsequently, the volume fraction of methane was adjusted to 26%, and the hydrogen gas integral was 74%. The deposition temperature was reduced to 500℃ at a rate of 1℃ / min, and the pressure was maintained at 4Pa for 1 hour. An amorphous carbon buffer layer 3 with a thickness of 3nm was generated in situ on the outer layer of the gradient nanotwinned layer 2, thus obtaining modified diamond particles with an average particle size of 150μm. Its structure is as follows. Figure 1 As shown;

[0076] S4. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 55:45, mechanically mix them at a rate of 350 rpm for 60 min, and then form them by hot isostatic pressing (process parameters include: pressure 200 MPa, temperature 600 ℃, and holding time 2 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0077] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 98.8:0.9:0.3.

[0078] Comparative Example 1

[0079] A method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0080] S1. Place diamond particles in a 5% (v / v) nitric acid solution, stir at 80°C for 1 hour, wash with deionized water until pH 6.5, and then vacuum dry at 100°C for 5 hours to obtain pretreated diamond particles.

[0081] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction 5%, hydrogen volume fraction 95%), set the deposition temperature to 900℃ and the pressure to 1 Pa, and gradually adjust the RF power within a gradient range of 100-300 W at a rate of 20 W / h to deposit a 0.5 μm thick layer with a twin density of 10 on the surface of the diamond particles. 6 cm -2 The gradient slope is 0.3 μm -1 A gradient nanotwin layer 2 was deposited for 2 hours, resulting in modified diamond particles with an average particle size of 100 μm.

[0082] S3. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 45:55, mechanically mix them at a rate of 500 rpm for 30 min, and then form them using powder metallurgy (process parameters include: pressure 150 MPa, temperature 550 ℃, and holding time 2 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0083] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 97.2:2.0:0.8.

[0084] Comparative Example 2

[0085] A method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0086] S1. Place diamond particles in an 8% (v / v) nitric acid solution, stir at 80°C for 1.2 h, wash with deionized water until pH 7.0, and then vacuum dry at 100°C for 4 h to obtain pretreated diamond particles.

[0087] S2. Place the pretreated diamond particles in a plasma-enhanced chemical vapor deposition (PECVD) apparatus, introduce a mixture of methane and hydrogen (methane volume fraction of 25% and hydrogen volume fraction of 75%), set the deposition temperature to 450℃, the pressure to 5Pa, and hold for 1h. An amorphous carbon buffer layer 3 with a thickness of 2.5nm is generated in situ on the surface 1 of the pretreated diamond particles, thus obtaining modified diamond particles with an average particle size of 150μm.

[0088] S3. Weigh copper-based alloy matrix powder and modified diamond particles in a mass ratio of 60:40, mechanically mix them at a rate of 400 rpm for 35 min, and then form them by hot isostatic pressing (process parameters include: pressure 200 MPa, temperature 600 ℃, and holding time 2 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0089] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 98.5:1.2:0.3.

[0090] Comparative Example 3

[0091] A method for preparing a graphitization-resistant copper-based alloy-diamond composite material includes the following steps:

[0092] S1. Place diamond particles in a 7% (v / v) nitric acid solution, stir at 60°C for 2 hours, wash with deionized water until pH 7.0, and then vacuum dry at 120°C for 4 hours to obtain pretreated diamond particles.

[0093] S2. Weigh copper-based alloy matrix powder and pretreated diamond particles in a mass ratio of 55:45, mechanically mix them at a rate of 350 rpm for 60 min, and then form them by hot isostatic pressing (process parameters include: pressure 200 MPa, temperature 600 ℃, and holding time 2 h) to obtain graphitization-resistant copper-based alloy-diamond composite material.

[0094] The copper-based alloy matrix powder consists of copper, chromium, and tin; the mass ratio of copper, chromium, and tin is 98.8:0.9:0.3.

[0095] Thermal conductivity, coefficient of thermal expansion, and flexural strength were tested on the graphitization-resistant copper-based alloy-diamond composite materials prepared in each embodiment and comparative example to demonstrate their graphitization resistance effect. The test results are shown in Table 1 below.

[0096] Table 1. Test results of graphitization-resistant copper-based alloy-diamond composite materials prepared in each embodiment and comparative example.

[0097]

[0098] As shown in Table 1, the overall performance of the graphitization-resistant copper-based alloy-diamond composite materials prepared in Examples 1-6 is better than that of Comparative Examples 1-3.

[0099] The main reason is that this application constructs a gradient nanotwin layer 2 with decreasing radial twin density on the surface 1 of diamond particles, and generates an amorphous carbon buffer layer 3 in situ on the outermost layer of this twin layer to obtain modified diamond particles; then, the modified diamond particles are composited into a copper-based alloy matrix to obtain a copper-based alloy-diamond composite material. The gradient nanotwin layer 2 and the amorphous carbon buffer layer 3 on the surface 1 of the diamond particles work together. Through the radial decrease in twin density in the gradient nanotwin layer 2 and the further deposition of amorphous carbon in the amorphous carbon buffer layer 3, not only is the diffusion and rearrangement of carbon atoms in the diamond blocked under high-temperature processing, but the graphitization during the preparation process is also suppressed, thus maintaining the high thermal conductivity and good mechanical properties of the obtained copper-based alloy-diamond composite material. The two also together constitute a transition phase, alleviating problems such as thermal stress concentration and thermal expansion coefficient mismatch at the interface between the diamond particles and the copper-based alloy matrix during high-temperature preparation. Furthermore, the combination of the two enhances the interfacial wettability and interfacial bonding between the copper-based alloy matrix and the diamond particles, thus promoting the interfacial bonding between the two.

[0100] In contrast, in Comparative Example 1, no amorphous carbon buffer layer 3 was generated in situ on the outermost layer of the gradient nanotwin layer 2. Therefore, although the existing gradient nanotwin layer 2 can partially block the diffusion and rearrangement of carbon atoms in diamond under high-temperature processes and partially inhibit its graphitization during the preparation process, there are still problems with the interfacial wettability and interfacial bonding force between the copper-based alloy matrix and diamond particles, resulting in a decrease in the overall thermal conductivity and mechanical properties of the prepared copper-based alloy-diamond composite material.

[0101] In Comparative Example 2, no gradient nanotwin layer 2 was constructed between the modified diamond particles and the copper-based alloy matrix. Similarly, it was difficult to prevent the diffusion and rearrangement of carbon atoms in the diamond under high-temperature processes, and it was also difficult to suppress the graphitization during the preparation process. Furthermore, since the overall thickness of the gradient nanotwin layer 2 was greater than that of the amorphous carbon buffer layer 3, the overall thermal conductivity and mechanical properties of the copper-based alloy-diamond composite material lacking the gradient nanotwin layer 2 decreased to a greater extent than those in Comparative Example 1.

[0102] In Comparative Example 3, there was neither a gradient nanotwin layer 2 nor an amorphous carbon buffer layer 3. For the same reason, the overall thermal conductivity and mechanical properties of the prepared copper-based alloy-diamond composite material were the worst.

[0103] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0104] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A graphitized-resistant copper-based alloy-diamond composite material, characterized by, The composition includes a copper-based alloy base powder and modified diamond particles; the modified diamond particles are prepared by sequentially depositing a gradient nanotwin layer (2) and an amorphous carbon buffer layer (3) on the surface (1) of the diamond particles from bottom to top; the gradient nanotwin layer (2) is distributed radially decreasingly along the surface (1) of the diamond particles; and the amorphous carbon buffer layer (3) is generated in situ on the outer layer of the gradient nanotwin layer (2).

2. The graphitized-resistant copper-based alloy-diamond composite material of claim 1, wherein, The composition of the copper-based alloy base powder includes copper, chromium and tin; and the mass ratio of the copper, chromium and tin is (97.2-99.3):(0.5-2.0):(0.2-0.8).

3. The graphitized-resistant copper-based alloy-diamond composite material of claim 1, wherein, The mass ratio of the copper-based alloy base powder and the modified diamond particles is (45-75):(25-55).

4. The graphitized-resistant copper-based alloy-diamond composite material of claim 1, wherein, The average particle size of the copper-based alloy base powder is 1-50 μm, and the average particle size of the modified diamond particles is 100-200 μm.

5. The anti-graphitizing copper-based alloy-diamond composite of claim 1, wherein, The gradient nanotwinned layer (2) has a thickness of 0.5-3 μm, a twinning density of 10 6 -10 8 cm -2 -1, and a gradient slope of 0.3-0.8 μm -1 ; the amorphous carbon buffer layer (3) has a thickness of 2-3 nm.

6. A method of producing the graphitized-resistant copper alloy-diamond composite material according to any one of claims 1 to 5, characterized by, The method includes the following steps: S1, placing diamond particles in a nitric acid solution with a volume fraction of 5-10%, stirring at 60-80 ℃ for 1-2 h, washing with deionized water until the pH is 6.5-7.5, and then vacuum drying at 100-120 ℃ for 3-5 h to obtain pretreated diamond particles; S2, placing the pretreated diamond particles in a plasma-enhanced chemical vapor deposition device, introducing a reaction gas, setting the deposition temperature to 700-900 ℃, the pressure to 1-5 Pa, and the radio frequency power to be gradient-adjusted, depositing a gradient nanotwin layer (2) on the surface (1) of the diamond particles, and the deposition time being 2-6 h; S3, then adjusting the volume fraction of methane in the reaction gas, reducing the deposition temperature to 400-500 ℃, maintaining the pressure at 1-5 Pa, and generating an amorphous carbon buffer layer (3) in situ on the outer layer of the gradient nanotwin layer (2) for 0.5-1.5 h, to obtain modified diamond particles; S4, weighing the copper-based alloy base powder and the modified diamond particles in proportion, mechanically mixing at a speed of 300-500 rpm for 30-60 min, and then forming by a powder metallurgy process or a hot isostatic pressing process, to obtain a graphitized-resistant copper-based alloy-diamond composite material.

7. The method for preparing a graphitization-resistant copper-based alloy-diamond composite material according to claim 6, characterized in that, In the S2, the reaction gas is a mixture of methane and hydrogen, and the volume fraction of methane is 5-15%; the radio frequency power ranges from 100 W to 300 W; and the gradient adjustment rate of the radio frequency power is 20-50 W / h.

8. The method for preparing a graphitization-resistant copper-based alloy-diamond composite material according to claim 6, characterized in that, In the S3, the volume fraction of methane is adjusted to 20-30%; and the reduction rate of the deposition temperature is 1-2 ℃ / min.

9. The method for preparing a graphitization-resistant copper-based alloy-diamond composite material according to claim 6, characterized in that, In the S4, the parameters of the powder metallurgy process include a pressure of 50-150 MPa, a temperature of 550-900 ℃, and a holding time of 2-4 h.

10. The method for preparing a graphitization-resistant copper-based alloy-diamond composite material according to claim 6, characterized in that, In the S4, the parameters of the hot isostatic pressing process include a pressure of 100-200 MPa, a temperature of 600-950 ℃, and a holding time of 1-3 h.

Images