A diamond / aluminum composite material with a nano-gradient interface and a preparation method thereof

Abstract

The present invention relates to the technical field of composite materials, and solves the technical problem that it is difficult to prepare a diamond / aluminum composite material with a tightly bonded interface while ensuring high thermal conductivity in the prior art. In particular, it relates to a diamond / aluminum composite material with a nano-gradient interface and a preparation method thereof. The present invention introduces a carburizing method on the basis of the magnetron sputtering method, and realizes the in-situ generation of new phases in each modified layer from the outermost metal element layer to the diamond surface through adsorption and diffusion, promotes the transformation of the metal modified elements on the diamond particle surface into carbides, and constructs a nano-gradient interface carbide layer. While the nano-scale interface layer improves the interface bonding between diamond and aluminum, it minimizes the introduced interface thermal resistance to the greatest extent. The present invention combines magnetron sputtering deposition with the carburizing method to prepare a nano-gradient multi-carbide interface layer with precisely controllable thickness, enhances the degree of interfacial diffusion reaction between diamond and aluminum, weakens the interfacial phonon scattering, and can give full play to the high thermal conductivity of diamond particles more fully.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a diamond / aluminum composite material with a nano-gradient interface and a preparation method thereof. Background Art

[0002] The heat flux density of new electronic devices has increased significantly, especially the heat flux density of the core chip has increased from the traditional 200 - 300 W / cm 2 to 2000 W / cm 2 developing. The ultra-high heat flux density has greatly reduced the service life of the core chip. How to achieve efficient heat dissipation while meeting the requirement of lightweight has become an urgent problem to be solved. The thermal conductivity of diamond is as high as 2000 W / cm 2 , which is 8 - 10 times that of aluminum and is the substance with the highest thermal conductivity in nature. Moreover, it has a small density (3.52 g / cm 3 ) and a very low coefficient of thermal expansion. The composite material composed of diamond particles and aluminum has an ultra-high thermal conductivity, and the coefficient of thermal expansion can be adjusted to match chip materials, etc. However, the wettability between diamond and aluminum is poor, and it is difficult to prepare a diamond / aluminum composite material with a tightly bonded interface. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a diamond / aluminum composite material with a nano-gradient interface and a preparation method thereof, which solves the technical problem that it is difficult to prepare a diamond / aluminum composite material with a tightly bonded interface under the premise of ensuring high thermal conductivity in the prior art.

[0004] To solve the above technical problems, the present invention provides the following technical solution: A diamond / aluminum composite material with a nano-gradient interface is formed by plating a metal target on the surface of diamond particles with a particle size range of 100 - 1000 μm to form a diamond / aluminum composite material with a nano-gradient multi-carbide interface layer;

[0005] The metal target includes, but is not limited to, one or more of W, Mo, Zr, B, and Ti substances, and the coating thickness range of a single metal target is 50 nm - 1000 nm.

[0006] Further, the nano-gradient multi-carbide interface layer is a multi-layer gradient metal carbide thin film.

[0007] This technical solution also provides a preparation method for preparing a diamond / aluminum composite material. The preparation method includes the following steps:

[0008] S1. Design a nano-interface gradient using the phonon mismatch model and calculate the interface thermal conductance;

[0009] S2. Clean the surface of diamond particles with acetone and alcohol solutions;

[0010] S3. Place the cleaned diamond particles in a dual-target or triple-target magnetron sputtering device, and deposit a metal target on the surface of the diamond particles according to the designed nano-interface gradient and the calculated result of the interface thermal conductivity in step S1 to construct a nano-gradient interface coating structure;

[0011] S4. Perform carburizing treatment on the diamond particles in step S3 to form a multi-layer gradient metal carbide film on the surface;

[0012] S5. Take the diamond particles in step S4 and form a mixed system of diamond particles with aluminum or aluminum alloy, and finally prepare a diamond / aluminum composite material by a solid-phase or liquid-phase forming method.

[0013] Furthermore, the number of nano-interface layers of the designed nano-interface gradient in step S1 is greater than or equal to 2.

[0014] Furthermore, the metal target in step S3 includes but is not limited to one or more of W, Mo, Zr, B, and Ti substances, and the coating thickness range of a single metal target is 50 nm to 100 nm.

[0015] Furthermore, an ultrasonic vibration device is provided in the dual-target or triple-target magnetron sputtering device in step S3 to drive the diamond particles to vibrate during the sputtering process, and the vibration frequency is 200 - 300 Hz.

[0016] Furthermore, the carburizing treatment in step S4 includes a solid carburizing method or a salt bath method, where,

[0017] The solid carburizing method includes:

[0018] Select carbon black powder as the solid carbon source, place the magnetron-sputtered diamond particles in a graphite carburizing tank filled with carbon black powder, then place the carburizing tank in a tube furnace, introduce the protective gas argon, heat up to 800 - 1000 °C, keep warm for 3 - 10 h, and finally cool to room temperature;

[0019] Clean and separate the diamond particles;

[0020] The salt bath method includes:

[0021] Prepare a liquid carburizing agent;

[0022] Mix NaCl and KCl and add them to a crucible, heat up to 780 - 800 °C, wait for the salt to melt, gradually add sodium carbonate and diamond, then add the liquid carburizing agent in small amounts multiple times, heat up to 920 °C, keep warm for 3 - 10 h, and finally cool to room temperature;

[0023] Clean and separate the diamond particles.

[0024] Further, the preparation of the liquid carburizer includes:

[0025] Dissolve NaCl, KCl, Na2CO3, and (NH2)2CO in boiling water at 100°C in excess, add carbon powder and stir evenly, let stand for more than 24 hours, then put it into a box furnace for dry distillation and activation treatment. The treatment temperature is 800 - 900°C. After air-cooling to room temperature, take it out to obtain the liquid carburizer.

[0026] Further, in the step S5, the volume fraction of diamond particles in the mixed system is 40 - 60%, the volume fraction of aluminum or aluminum alloy is 40 - 60%, and the sum of the volume fractions of diamond and aluminum or aluminum alloy is 100%;

[0027] The particle size of the aluminum powder is 10 - 600 μm.

[0028] Further, the solid-phase forming method in the step S5 includes any one of spark plasma sintering method, vacuum hot pressing sintering method, powder metallurgy method, and injection molding method;

[0029] The liquid-phase forming method includes any one of infiltration method, high temperature and high pressure method, squeeze casting method, and hydraulic infiltration method.

[0030] By means of the above technical solutions, the present invention provides a diamond / aluminum composite material with a nano-gradient interface and a preparation method, which at least has the following beneficial effects:

[0031] 1. The present invention deposits interface modification elements on the surface of diamond particles by magnetron sputtering method and combines with an ultrasonic vibration device to achieve uniform plating of each element, which can effectively reduce the interface thermal resistance introduced due to interface bonding defects and improve the thermal conductivity of the diamond-aluminum composite material.

[0032] 2. The present invention introduces a carburizing method on the basis of the magnetron sputtering method, and realizes in-situ generation of new phases from the outermost metal element layer to each modification layer on the diamond surface through adsorption and diffusion, promotes the transformation of metal modification elements on the diamond particle surface into carbides, and constructs a nano-gradient interface carbide layer. While improving the interface bonding between diamond and aluminum, the introduced interface thermal resistance is minimized.

[0033] 3. The present invention designs a nano-gradient interface structure based on the phonon mismatch model theory, and uses a combination of magnetron sputtering deposition and carburizing method to prepare a nano-gradient multi-carbide interface layer with precisely controllable thickness, enhances the degree of interface diffusion reaction between diamond and aluminum, weakens the interface phonon scattering, and can give full play to the high thermal conductivity of diamond particles. Description of the Drawings

[0034] The accompanying drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0035] Figure 1 Schematic diagram of the ultrasonic magnetron sputtering equipment adopted by the present invention;

[0036] Figure 2 Microstructure diagram of the double-layer carbide diamond / aluminum composite material of the present invention;

[0037] Figure 3 Schematic diagram of the fracture morphology of the diamond / aluminum composite material prepared in the first embodiment of the present invention under an electron microscope;

[0038] Figure 4 Schematic diagram of the fracture morphology of the diamond / aluminum composite material prepared in the first comparative example of the present invention under an electron microscope;

[0039] In the figure: 1. Target; 2. Sample stage; 3. Resonator; 4. Rotating shaft; 5. Vacuum pump; 6. Ultrasonic generator. Detailed implementation manners

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Driven by the performance requirements of high-integration equipment such as new military radars, 5G, and energy vehicles, chips and module-level devices are developing towards functional integration, miniaturization of size, compactness of structure, and high power density. The heat flux density of new electronic devices has increased significantly. In particular, the heat flux density of the core chip has increased from the traditional 200 - 300 W / cm 2 to 2000 W / cm 2 . The ultra-high heat flux density has significantly reduced the service life of the core chip. How to achieve efficient heat dissipation while meeting lightweight requirements has become an urgent problem to be solved. The thermal conductivity of diamond is as high as 2000 W / cm 2 , which is 8 - 10 times that of aluminum and the substance with the highest thermal conductivity in nature. Moreover, it has a small density (3.52 g / cm 3 ) and a very low coefficient of thermal expansion. The composite material composed of diamond particles and aluminum has an ultra-high thermal conductivity, and its coefficient of thermal expansion can be adjusted to match that of chip materials, etc. However, the wettability between diamond and aluminum is poor, making it difficult to prepare a diamond / aluminum composite material with a tightly bonded interface.

[0042] In the existing technology, in order to improve the interface bonding, a single-layer carbide is mostly prepared on the surface of diamond powder. However, the improvement effect of the single-layer carbide film on the composite material interface is limited. In view of the above problems, based on the acoustic mismatch model (AMM), the present invention proposes a diamond / aluminum composite material with a nano-gradient interface and a preparation method thereof.

[0043] Please refer to Figure 1 - Figure 2 , in this embodiment, a diamond / aluminum composite material with a nano-gradient interface and a preparation method thereof are proposed. The diamond / aluminum composite material is a diamond / aluminum composite material with a nano-gradient multi-carbide interface layer formed by plating a metal target on the surface of diamond particles with a particle size range of 100-1000 μm. The metal target includes but is not limited to one or more of W, Mo, Zr, B, and Ti substances, and the coating thickness range of a single metal target is 50 nm-1000 nm.

[0044] In the present invention, several different implementation manners are provided for the preparation method of the diamond / aluminum composite material. Among them, two different methods are adopted for the carburizing treatment process, namely the solid carburizing method and the salt bath method, so as to realize the preparation of the high-thermal-conductivity diamond / aluminum composite material. For the specific preparation method, please refer to Embodiments 1 to 6. Embodiment 1

[0045] This embodiment includes the following steps:

[0046] Step 1: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove surface oil stains.

[0047] Step 2: Place the cleaned diamond particles in a magnetron sputtering device, use tungsten target and titanium target, under the conditions of a sputtering pressure of 5×10 -3 Pa and a sputtering power of 500 W. After sputtering with the tungsten target for 10 min, switch to sputtering with the titanium target for 10 min to obtain a tungsten and titanium coating thickness of 50 nm each, and the total coating thickness on the surface of the diamond particles is 100 nm.

[0048] Step 3: Place the magnetron-sputtered diamond particles in a graphite carburizing tank filled with carbon black powder, then place the carburizing tank in a tube furnace, introduce the protective gas argon, heat up to 900 °C, keep warm for 3 h, and then cool to room temperature with the furnace.

[0049] Step 4: Separate the diamond particles and carbon powder with a sieve and clean the diamond particles.

[0050] Step Five: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0051] Step Six: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum pumping system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min; when the temperature reaches 600 °C, keep the temperature and pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold it to obtain the diamond / aluminum composite material.

[0052] The thermal conductivity of the diamond / aluminum composite material prepared by the above steps reaches 573 W / (m·K), and the flexural strength reaches 314 MPa. Example Two

[0053] This example includes the following steps:

[0054] Step One: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove the surface oil stain.

[0055] Step Two: Place the cleaned diamond particles in a magnetron sputtering device. Using tungsten target and titanium target, under the conditions of sputtering pressure of 5×10 -3 Pa and sputtering power of 500 W, after sputtering with tungsten target for 20 min, switch to sputtering with titanium target for 20 min to obtain a tungsten and titanium coating thickness of 100 nm each, and the total coating thickness on the surface of the diamond particles is 200 nm.

[0056] Step Three: Place the magnetron-sputtered diamond particles in a graphite carburizing tank filled with carbon black powder, then place the carburizing tank in a tube furnace, introduce the protective gas argon, heat up to 900 °C, keep the temperature for 3 h, and then cool to room temperature with the furnace.

[0057] Step Four: Separate the diamond particles and carbon powder with a sieve and clean the diamond particles.

[0058] Step Five: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0059] Step 6: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min. When the temperature reaches 600 °C, keep the temperature and pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold it to obtain the diamond / aluminum composite material.

[0060] The diamond / aluminum composite material prepared through the above steps has a thermal conductivity of 524 W / (m·K) and a flexural strength of 293 MPa. Example 3

[0061] This example includes the following steps:

[0062] Step 1: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove the surface oil stain.

[0063] Step 2: Place the cleaned diamond particles in a magnetron sputtering device. Using a chromium target and a boron target, under the conditions of a sputtering pressure of 5×10 -3 Pa and a sputtering power of 500 W, after sputtering with the chromium target for 10 min, switch to sputtering with the boron target for 10 min to obtain a chromium and boron coating thickness of 50 nm each, and a total coating thickness on the surface of the diamond particles of 100 nm.

[0064] Step 3: Place the magnetron-sputtered diamond particles in a graphite carburizing tank filled with carbon black powder, then place the carburizing tank in a tube furnace, introduce the protective gas argon, heat up to 900 °C, keep the temperature for 3 h, and then cool down to room temperature with the furnace.

[0065] Step 4: Separate the diamond particles and carbon powder with a sieve and clean the diamond particles.

[0066] Step 5: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0067] Step 6: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min. When the temperature reaches 600 °C, keep the temperature and pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold it to obtain the diamond / aluminum composite material.

[0068] The thermal conductivity of the diamond / aluminum composite material prepared through the above steps reaches 504 W / (m·K), and the flexural strength reaches 288 MPa. Example 4

[0069] This example includes the following steps:

[0070] Step 1: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove the surface oil.

[0071] Step 2: Place the cleaned diamond particles in a magnetron sputtering device. Using a tungsten target and a titanium target, under the conditions of a sputtering pressure of 5×10 -3 Pa and a sputtering power of 500 W, after sputtering with the tungsten target for 10 min, switch to sputtering with the titanium target for 10 min to obtain a tungsten and titanium coating thickness of 50 nm each, and a total coating thickness on the surface of the diamond particles of 100 nm.

[0072] Step 3: Dissolve salts such as NaCl, KCl, Na2CO3, and (NH2)2CO in boiling water at 100 °C with an excess amount, add carbon powder and stir evenly, let it stand for more than 24 h, then put it into a box furnace for dry distillation and activation treatment. The treatment temperature is 800 - 900 °C, and after air cooling to room temperature, take it out.

[0073] Step 4: Mix NaCl and KCl and add them to a crucible. Heat it to 780 - 800 °C. After the salt melts, gradually add sodium carbonate and diamond, and then add the liquid carburizer in small amounts multiple times. Heat it to 920 °C, keep it warm for 3 - 10 h, and finally cool it to room temperature.

[0074] Step 5: Dissolve, filter, and separate the diamond particles from the molten salt, and ultrasonically clean the diamond.

[0075] Step 6: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix them for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0076] Step 7: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum pumping system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min; when the temperature reaches 600 °C, keep it warm and under pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold it to obtain the diamond / aluminum composite material.

[0077] The thermal conductivity of the diamond / aluminum composite material prepared through the above steps reaches 566 W / (m·K), and the flexural strength reaches 291 MPa. Example 5

[0078] This embodiment includes the following steps:

[0079] Step 1: Clean diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove surface oil stains.

[0080] Step 2: Place the cleaned diamond particles in a magnetron sputtering device. Using a tungsten target and a titanium target, under the conditions of a sputtering gas pressure of 5×10 -3 Pa and a sputtering power of 500 W, after sputtering with the tungsten target for 20 min, switch to sputtering with the titanium target for 20 min, obtaining a tungsten and titanium coating thickness of 100 nm each, and a total coating thickness on the surface of the diamond particles of 200 nm.

[0081] Step 3: Dissolve salts such as NaCl, KCl, Na2CO3, and (NH2)2CO in boiling water at 100°C in excess, add carbon powder and stir evenly, let it stand for more than 24 h, put it into a box furnace for dry distillation and activation treatment, with a treatment temperature of 800 - 900°C, take it out after air cooling to room temperature.

[0082] Step 4: Mix NaCl and KCl and add them to a crucible. Heat up to 780 - 800°C. After the salts melt, gradually add sodium carbonate and diamond, and then add the liquid carburizer in small amounts multiple times. Heat up to 920°C and keep it warm for 3 - 10 h, and finally cool to room temperature.

[0083] Step 5: Dissolve, filter, and separate the diamond particles from the molten salt, and ultrasonically clean the diamond.

[0084] Step 6: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0085] Step 7: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply pressure up to 40 MPa, turn on the vacuum pumping system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50°C / min; when the temperature reaches 600°C, keep it warm and under pressure for 40 min, then stop heating. When the furnace temperature drops below 100°C, take out the mold and demold to obtain a diamond / aluminum composite material.

[0086] The thermal conductivity of the diamond / aluminum composite material prepared through the above steps reaches 517 W / (m·K), and the flexural strength reaches 278 MPa. Example 6

[0087] This embodiment includes the following steps:

[0088] Step 1: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove surface oil stains.

[0089] Step 2: Place the cleaned diamond particles in a magnetron sputtering device. Using a chromium target and a boron target, under the conditions of a sputtering pressure of 5×10 -3 Pa and a sputtering power of 500 W, after sputtering with the chromium target for 10 min, switch to sputtering with the boron target for 10 min to obtain a chromium and boron coating thickness of 50 nm each, and a total coating thickness of 100 nm on the surface of the diamond particles.

[0090] Step 3: Dissolve salts such as NaCl, KCl, Na2CO3, and (NH2)2CO in boiling water at 100 °C in excess, add carbon powder and stir evenly, let stand for more than 24 h, then put it into a box furnace for dry distillation and activation treatment. The treatment temperature is 800 - 900 °C, and take it out after air cooling to room temperature.

[0091] Step 4: Mix NaCl and KCl and add them to a crucible. Heat up to 780 - 800 °C. After the salts melt, gradually add sodium carbonate and diamond, and then add the liquid carburizer in small amounts and multiple times. Heat up to 920 °C, keep the temperature for 3 - 10 h, and finally cool to room temperature.

[0092] Step 5: Dissolve, filter, and separate the diamond particles from the molten salt, and ultrasonically clean the diamond.

[0093] Step 6: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0094] Step 7: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum pumping system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min; when the temperature reaches 600 °C, keep the temperature and pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold to obtain a diamond / aluminum composite material.

[0095] The thermal conductivity of the diamond / aluminum composite material prepared through the above steps reaches 566 W / (m·K), and the flexural strength reaches 291 MPa. Comparative Example 1

[0096] This comparative example includes the following steps:

[0097] Step 1: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove surface oil stains.

[0098] Step 2: Weigh the cleaned diamond particles, titanium powder, and tungsten oxide powder, and mix them in a molar ratio of 5:1:1 respectively. Put them into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0099] Step 3: Place the ball-milled powder in a tubular furnace, evacuate to 0.1 Pa, heat it to 1050 °C at a rate of 5 °C / min, hold for 20 min, and then cool it to room temperature with the furnace.

[0100] Step 4: Separate the diamond particles from the titanium powder and tungsten oxide powder with a sieve, and clean the diamond particles.

[0101] Step 5: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0102] Step 6: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply pressure up to 40 MPa, turn on the vacuum system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min; when the temperature reaches 600 °C, hold the pressure and temperature for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold to obtain the diamond / aluminum composite material.

[0103] The thermal conductivity of the diamond / aluminum composite material prepared by the above steps is 329 W / (m·K), and the flexural strength is 132 MPa. Comparative Example 2

[0104] This comparative example includes the following steps:

[0105] Step 1: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove surface oil stains.

[0106] Step 2: Weigh the cleaned diamond particles, molybdenum powder, and tungsten oxide powder, and mix them in a molar ratio of 5:1:1 respectively. Put them into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0107] Step 3: Place the ball-milled powder in a tubular furnace, evacuate to 0.1 Pa, heat it to 1050 °C at a rate of 5 °C / min, hold for 20 min, and then cool it to room temperature with the furnace.

[0108] Step 4: Separate the diamond particles from the molybdenum powder and tungsten oxide powder with a sieve, and clean the diamond particles.

[0109] Step Five: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0110] Step Six: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min; when the temperature reaches 600 °C, keep the temperature and pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold it to obtain the diamond / aluminum composite material.

[0111] The diamond / aluminum composite material prepared by the above steps has a thermal conductivity of 312 W / (m·K) and a flexural strength of 115 MPa. Comparative Example 3

[0112] This comparative example includes the following steps:

[0113] Step One: Clean the diamond particles with a particle size of 100 μm using acetone and alcohol solution to remove the surface oil.

[0114] Step Two: Weigh the cleaned diamond particles, titanium powder and tungsten oxide powder, and mix them in a molar ratio of 5:1:1 respectively, then put them into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0115] Step Three: Place the ball-milled powder in a tubular furnace, evacuate to 0.1 Pa, heat it to 1000 °C at a rate of 5 °C / min, keep the temperature for 40 min, and then cool it to room temperature with the furnace.

[0116] Step Four: Separate the diamond particles from the titanium powder and tungsten oxide powder using a sieve, and clean the diamond particles.

[0117] Step Five: Put the cleaned diamond particles and aluminum powder with a particle size of 10 μm into a ball mill and mix for 2 h. The rotation speed of the ball mill is 100 r / min, and the forward and reverse rotation times are both 1 h.

[0118] Step Six: Load the uniformly mixed powder into a graphite mold, then place the mold into the cavity of a spark plasma sintering furnace, apply a pressure of 40 MPa, turn on the vacuum system to remove the residual gas between the particles. When the vacuum degree in the furnace is less than 0.1 MPa, start heating at a rate of 50 °C / min; when the temperature reaches 600 °C, keep the temperature and pressure for 40 min, then stop heating. When the furnace temperature drops below 100 °C, take out the mold and demold it to obtain the diamond / aluminum composite material.

[0119] The thermal conductivity of the diamond / aluminum composite material prepared by the above steps is 363 W / (m·K), and the flexural strength is 128 MPa.

[0120] Flexural strength test

[0121] The thermal conductivity was tested in accordance with GB / T 39862-2021, and the flexural strength was tested in accordance with GB / T 232-2010.

[0122] In the present invention, a variety of different diamond / aluminum composite materials were obtained according to the preparation methods proposed in Examples 1 to 6. The thermal conductivity and flexural strength of the diamond / aluminum composite materials prepared in each example were tested, as shown in Table 1.

[0123] Table 1 Parameters of diamond / aluminum composite materials

[0124] Group Metal target Thickness of single metal coating Total thickness of surface coating Thermal conductivity Flexural strength Example 1 Tungsten, Titanium 50nm 100nm 573W / (m·K) 314MPa Example 2 Tungsten, Titanium 100nm 200nm 524W / (m·K) 293MPa Example 3 Chromium, Boron 50nm 100nm 504W / (m·K) 288MPa Example 4 Tungsten, Titanium 50nm 100nm 566W / (m·K) 291MPa Example 5 Tungsten, Titanium 100nm 200nm 517W / (m·K) 278MPa Example 6 Chromium, Boron 50nm 100nm 566W / (m·K) 291MPa Comparative Example 1 Titanium, Tungsten 50nm 100nm 329 W / (m·K) 132 MPa Comparative Example 2 Molybdenum, Tungsten 50nm 100nm 312 W / (m·K) 115 MPa Comparative Example 3 Titanium, Tungsten 100nm 200nm 363 W / (m·K) 128 MPa

[0125] As can be seen from Table 1, since the carburizing treatment adopted in Examples 1, 2, and 3 is the solid carburizing method, among which, when the metal target is tungsten or titanium and the thickness is 50 nm, the thermal conductivity of the prepared diamond / aluminum composite material reaches 573 W / (m·K), and the flexural strength reaches 314 MPa; when the thickness is 100 nm, the thermal conductivity of the prepared diamond / aluminum composite material reaches 524 W / (m·K), and the flexural strength reaches 293 MPa; when the metal target is chromium or boron and the thickness is 50 nm, the thermal conductivity of the prepared diamond / aluminum composite material reaches 504 W / (m·K), and the flexural strength reaches 288 MPa.

[0126] While the carburizing treatment adopted in Examples 4, 5, and 6 is the salt bath method, among which, when the metal target is tungsten or titanium and the thickness is 50 nm, the thermal conductivity of the prepared diamond / aluminum composite material reaches 566 W / (m·K), and the flexural strength reaches 291 MPa; when the thickness is 100 nm, the thermal conductivity of the prepared diamond / aluminum composite material reaches 517 W / (m·K), and the flexural strength reaches 278 MPa; when the metal target is chromium or boron and the thickness is 50 nm, the thermal conductivity of the prepared diamond / aluminum composite material reaches 566 W / (m·K), and the flexural strength reaches 291 MPa.

[0127] In summary, the diamond / aluminum composite materials prepared in multiple embodiments proposed in the present invention all have better thermal conductivity and flexural strength, and can effectively reduce the interfacial thermal resistance introduced due to interfacial bonding defects, improving the thermal conductivity of the diamond / aluminum composite material.

[0128] Interface bonding tightness test

[0129] The fracture morphology obtained after the bending strength test was characterized by a Hitachi SU8220 electron microscope. The fracture was magnified 500 times to compare the interfacial bonding state, such as Figure 3 and Figure 4 shown, where Figure 3 is the fracture morphology of the diamond / aluminum composite material prepared in Example 1 under the electron microscope, Figure 4 is the fracture morphology of the diamond / aluminum composite material prepared in Comparative Example 1 under the electron microscope. By comparison, it can be seen that the interfacial bonding density of the diamond / aluminum composite materials prepared in Examples 1 to 6 is higher, and the interfacial diffusion reaction degree between diamond and aluminum is effectively enhanced, the interfacial phonon scattering is weakened, and the high thermal conductivity of diamond particles can be more fully utilized.

[0130] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diamond / aluminum composite material with a nano-gradient interface, characterized in that, A diamond / aluminum composite material with a nano-gradient multi-carbide interface layer is formed by plating a metal target on the surface of diamond particles with a particle size range of 100 to 1000 μm; The metal target includes but is not limited to one or more of W, Mo, Zr, B, and Ti substances, and the coating thickness range of a single metal target plating is 50 nm to 1000 nm; The nano-gradient multi-carbide interface layer is a multi-layer gradient metal carbide thin film; The method for preparing the diamond / aluminum composite material includes the following steps: S1. Design a nano-interface gradient using the phonon mismatch model and calculate the interface thermal conductivity, where the number of nano-interface layers of the nano-interface gradient is greater than or equal to 2; S2. Clean the surface of diamond particles using acetone and alcohol solutions; S3. Place the cleaned diamond particles in a dual-target or triple-target magnetron sputtering device, and deposit a metal target on the surface of the diamond particles according to the nano-interface gradient designed in step S1 and the calculated result of the interface thermal conductivity to construct a nano-gradient interface coating structure; S4. Perform carburizing treatment on the diamond particles in step S3 to form a multi-layer gradient metal carbide thin film on the surface; S5. Take the diamond particles in step S4 and aluminum or aluminum alloy to form a mixed system of diamond particles, and finally prepare the diamond / aluminum composite material by solid-phase or liquid-phase forming method.

2. The diamond / aluminum composite material according to claim 1, wherein In the dual-target or triple-target magnetron sputtering device in step S3, there is an ultrasonic vibration device, which drives the diamond particles to vibrate during the sputtering process, and the vibration frequency is 200 to 300 Hz.

3. The diamond / aluminum composite material according to claim 1, wherein The carburizing treatment in step S4 includes solid carburizing method or salt bath method, where, The solid carburizing method includes: Select carbon black powder as the solid carbon source, place the magnetron-sputtered diamond particles in a graphite carburizing tank filled with carbon black powder, then place the carburizing tank in a tube furnace, introduce the protective gas argon, heat up to between 800 and 1000 °C, keep warm for 3 to 10 h, and finally cool to room temperature; Clean and separate the diamond particles; The salt bath method includes: Prepare a liquid carburizing agent; Mix NaCl and KCl and add them to a crucible, heat up to 780 - 800 °C, wait for the salt to melt, then gradually add sodium carbonate and diamond, and then add the liquid carburizing agent in small amounts and multiple times, heat up to 920 °C, keep warm for 3 to 10 h, and finally cool to room temperature; Clean and separate the diamond particles.

4. The diamond / aluminum composite material according to claim 3, wherein The preparation of the liquid carburizing agent includes: Dissolve NaCl, KCl, Na2CO3, and (NH2)2CO in boiling water at 100 °C in excess, add carbon powder and stir evenly, let it stand for more than 24 h, put it into a box furnace for dry distillation and activation treatment, the treatment temperature is 800 - 900 °C, take it out after air cooling to room temperature to obtain the liquid carburizing agent.

5. The diamond / aluminum composite material according to claim 1, wherein In step S5, the volume fraction of the diamond particles in the mixed system is 40 - 60%, the volume fraction of aluminum or aluminum alloy is 40 - 60%, and the sum of the volume fractions of diamond and aluminum or aluminum alloy is 100%; The particle size of the aluminum powder is 10 - 600 μm.

6. The diamond / aluminum composite material according to claim 1, characterized in that, The solid-phase forming method in step S5 includes any one of spark plasma sintering method, vacuum hot pressing sintering method, powder metallurgy method, and injection molding method; The liquid-phase forming method includes any one of the following: infiltration method, high-temperature and high-pressure method, squeeze casting method, and hydraulic infiltration method.

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