Method for preparing diamond-copper composite material through binder jet 3D printing

Abstract

The invention discloses a method for preparing a diamond / copper composite material through binder jet 3D printing, which comprises the following steps: adding nano metal powder into a binder solution to form a suspension, adding a dispersing agent and a surfactant into the suspension, and stirring to form a nano metal suspension binder; printing a diamond green body by using the nano-metal suspension binder and diamond powder; curing and degreasing the diamond green body, and sintering to obtain a prefabricated part; and a pure copper solution is taken to be pressurized and infiltrated into the prefabricated part, and the diamond / copper composite material is obtained. The metal carbide layer is prepared on the surface of the diamond through an adhesive spraying technology, so that the problems of large interface energy and poor wettability of copper and the diamond are solved, meanwhile, the state of the carbide layer is optimized, the heat-conducting property of the material is improved, a plating process is avoided, and the process steps are simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of diamond composite materials, and in particular to a method for preparing a diamond / copper composite material by using binder jet 3D printing. Background Art

[0002] Diamond / copper composite materials have broad application prospects in the fields of electronic packaging, heat dissipation devices, aerospace, etc. due to their excellent thermal conductivity and mechanical properties. However, the high interface energy and poor wettability between diamond and copper seriously reduce its thermal conductivity, and the current solutions, namely the two methods of copper matrix alloying and diamond surface metallization, have complex processes, poor state of the carbide layer, and the inability to accurately control the thickness of the carbide layer. In recent years, the development of 3D printing technology has provided a new way for the preparation of composite materials, especially the binder jetting method has shown unique advantages in the preparation of complex shapes and high-precision parts. Therefore, it is of great practical significance to propose a new method for regulating the interface of diamond / copper materials in combination with binder jetting 3D printing technology.

[0003] The patent with application number 202310515507.X discloses a method for preparing diamond / copper composite materials combined with binder jet 3D printing technology. Although the tungsten plating method in this patent can also improve the wettability between diamond and copper, the thickness and uniformity of the tungsten plating layer are difficult to accurately control. The coating process is relatively complex and costly, and it is difficult to find the optimal coating thickness. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, the first purpose of the present invention is to propose a method for preparing a diamond / copper composite material by using a binder jet 3D printing, by preparing a new type of nano-metal suspension binder, using a binder jet 3D printing technology to print a diamond green body, and then by curing and degreasing to make the nano-metal particles evenly deposited on the surface of the diamond particles, followed by sintering treatment to make the nano-metal particles react with diamond to form a metal carbide layer, and finally pressurizing and infiltrating copper to obtain a dense molded part. In addition, the problem of large interface energy and poor wettability between copper and diamond is solved, the plating process is avoided, the process steps are simplified, the irregular diamond particles are suitable, the state of the carbide layer is optimized, and the thickness of the surface metal carbide layer is controlled by changing the mass fraction of the nano-metal in the binder, so that the composite material achieves the best thermal conductivity effect. At the same time, the 3D printing technology can improve the processability and designability of the material, and is suitable for the near-net molding of the material.

[0006] Therefore, according to one aspect of the present invention, the present invention provides a method for preparing a diamond / copper composite material by using a binder jet 3D printing. According to an embodiment of the present invention, the method comprises: adding nano-metal powder to a binder solution to form a suspension, adding a dispersant and a surfactant to the suspension and stirring to form a nano-metal suspension binder; using the nano-metal suspension binder and diamond powder to print a diamond green body; curing and degreasing the diamond green body and then sintering it to obtain a preform; taking a pure copper solution and pressurizing and infiltrating it into the preform to obtain a diamond / copper composite material.

[0007] According to the method for preparing diamond / copper composite materials by binder jet 3D printing according to an embodiment of the present invention, a nano-metal suspension binder is configured, and a metal carbide layer is prepared on the surface of the diamond by binder jetting technology, which solves the problem of large interface energy and poor wettability between copper and diamond, avoids the plating process, simplifies the process steps, optimizes the state of the carbide layer, and controls the thickness of the surface metal carbide layer by changing the mass fraction of the nano-metal in the binder, so that the composite material achieves the best thermal conductivity effect.

[0008] In addition, the method according to the above embodiment of the present invention may also have the following additional technical features: According to an embodiment of the present invention, the adhesive solution is an anhydrous ethanol solution of polyvinyl pyrrolidone or a deionized water solution of polyvinyl alcohol, and the mass fraction of the adhesive solution is 5-7wt%.

[0009] According to an embodiment of the present invention, the mass fraction of the nano metal powder in the binder solution is 6-18wt%.

[0010] According to an embodiment of the present invention, the nano metal powder is one of Cr, Ti, Zr, W and Mo.

[0011] According to an embodiment of the present invention, 0.5-2 g of dispersant is added to every 100 g of the nano metal powder.

[0012] According to an embodiment of the present invention, the added mass of the surfactant is 0.2% of the mass of the suspension.

[0013] According to an embodiment of the present invention, the average particle size of the diamond powder is 50-200 microns.

[0014] According to an embodiment of the present invention, the average particle size of the nano metal powder is 20-50 nm.

[0015] According to an embodiment of the present invention, the specific process of curing and degreasing the diamond green embryo is: the diamond green embryo powder is moved into an oven and heated to 60-130° C. for 1.5-2 hours to completely cure the binder and de-powder the binder; the de-powdered sample is heated from room temperature to 200-500° C. at a rate of 5-10° C. / min, and then kept warm for 30-60 minutes.

[0016] According to an embodiment of the present invention, the specific process of the sintering treatment is: after curing and degreasing the diamond green embryo, put it into a vacuum furnace, fill it with protective gas, heat it to 700-1100°C for 0.5-2h, and the heating rate is 120-300°C / h.

[0017] According to an embodiment of the present invention, the specific process of taking the pure copper solution for pressure infiltration into the preform is: placing the preform in a vacuum environment, heating and raising the temperature, and in a vacuum and pressurized state, the pure copper solution containing molten copper powder is pressure infiltrated into the porous preform. The mass ratio of the copper powder to the diamond is 63:46-18:7.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 Flow chart of a method for preparing diamond / copper composite materials using binder jet 3D printing. DETAILED DESCRIPTION

[0020] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0021] According to one aspect of the present invention, the present invention provides a method for preparing a diamond / copper composite material using binder jet 3D printing. Figure 1 According to an embodiment of the present invention, the method includes: S100 with nano-metal suspension binder According to an embodiment of the present invention, nano metal powder is added to a binder solution to form a suspension, and a dispersant and a surfactant are added to the suspension and stirred to form a nano metal suspension binder.

[0022] In some embodiments of the present invention, there are multiple choices for the type of nano metal powder. It can be understood that the nano metal powder can be one of Cr, Ti, Zr, W, and Mo. These nano metal elements are elements that react easily with carbon on the diamond surface, while other metal powders are not easy to form a carbide layer. It should also be noted that the average particle size of the nano metal powder can be 20-50nm. By controlling the particle size of the nano metal powder, a metal film with a thickness of 100-900 nanometers can be produced on the diamond surface. A particle size of 30nm or less can improve the uniformity of the metal film, so the average particle size of the nano metal powder is controlled at 20-50nm.

[0023] In addition, according to an embodiment of the present invention, the binder solution can be an anhydrous ethanol solution of polyvinyl pyrrolidone or a deionized water solution of polyvinyl alcohol. It can be understood that when the binder solution is prepared, a polyvinyl pyrrolidone (PVP) powder with a mass fraction of 5-7wt% is dissolved in anhydrous ethanol or a polyvinyl alcohol (PVA) powder with a mass fraction of 5-7wt% is dissolved in deionized water to prepare a premixed solution. The binder solution selects an anhydrous ethanol solution of polyvinyl pyrrolidone or a deionized water solution of polyvinyl alcohol. Both have good wettability and adhesion, are easy to decompose during the degreasing process and will not remain in the parts, and the nano metal powder is easily dispersed in the above two binder solutions, which is convenient for preparing a suspension binder. In this embodiment, the mass concentration of the premixed solution is controlled at 5-7wt% because too low a mass fraction may cause the printing to be unformed or the preform to have low strength, and too high a mass fraction may cause degreasing difficulties, block the nozzle, and affect the dispersion of the nano metal powder. It should also be noted that the present invention specially develops and formulates a nano-metal suspension binder, in which the nano-metal powder and binder and other ingredients not only help the bonding of diamond and copper, but also react with diamond in the subsequent processing to form a metal carbide layer, thereby optimizing the interface performance; the binder design of the present application is more targeted, not only can it realize 3D printing molding, but also can play an important role in subsequent processing, enhance the interface bonding between diamond and copper, and improve the thermal conductivity and overall performance of the composite material.

[0024] According to an embodiment of the present invention, an ultrasonic disperser is used to add nano-metal powder to a premixed solution to form a suspension with a mass fraction of 6-18wt%. The inventors found that the thickness of the surface metal carbide layer can be controlled by changing the mass fraction of the nano-metal in the binder. The mass fraction of the nano-metal powder in the premixed solution is controlled at 6-18wt%. If it is too low, the metal nano-layer on the diamond surface will be incomplete or too thin. If the mass fraction is too high, the nozzle will be blocked or the nano-metal layer on the diamond surface will be too thick and uneven. If it is controlled at 6-18wt%, the metal nano-layer on the diamond surface will be kept between 100-900nm, so that the thermal conductivity effect is optimized. By adjusting the mass fraction of the nano-metal in the binder, the thickness of the metal carbide layer can be accurately controlled, so that the composite material can achieve the best thermal conductivity effect, and at the same time, the process steps are simplified, the production efficiency and product quality are improved, and the production cost is reduced.

[0025] In addition, according to an embodiment of the present invention, in order to promote the decomposition of agglomerates in the suspension and promote mixing, 0.5-2g dispersant is added to every 100g of nano metal powder, and the surfactant added in addition has a mass of 0.2% of the mass of the suspension, and then mechanical stirring is carried out for about 45min. It can be explained that the dispersant of the embodiment of the present invention can be a polyether copolymer, or other polymer dispersants, preferably a polyether copolymer. The surface dispersant of the embodiment of the present invention can be sodium dioctyl sulfosuccinate, or other surfactants, preferably sodium dioctyl sulfosuccinate. Finally, the suspension is degassed in a vacuum chamber to remove trapped bubbles to obtain a nano metal suspension binder.

[0026] S200 Printing Diamond Green Body According to an embodiment of the present invention, the nano-metal suspension binder and diamond powder are used to print diamond green compacts.

[0027] According to an embodiment of the present invention, the average particle size of the diamond powder is 50-200 microns.

[0028] S300 Diamond Green Body Solidification Debinding Sintering Process According to an embodiment of the present invention, the diamond green body is solidified and degreased and then sintered to obtain a preform.

[0029] According to an embodiment of the present invention, after the diamond green embryo is printed, it is necessary to perform curing degreasing and sintering treatment. First, curing degreasing is required, that is, after printing, the powder bed containing the diamond green embryo can be moved to an oven and heated to 60-130°C for 1.5-2 hours to completely cure the binder and depowder. Then degreasing is required in the air. In detail, the diamond green embryo after depowdering can be placed in a high-temperature heating device, which can be a muffle furnace. Starting from room temperature, the muffle furnace is raised to 200-500°C at a rate of 5-10°C / min, and then the sample is kept at this temperature for 30-60 minutes.

[0030] In addition, in some embodiments, the diamond green body needs to be sintered after solidification and degreasing so that the nano-metal particles can react with the diamond to form a metal carbide layer. Specifically, the solidified and degreased sample can be placed in a vacuum furnace, filled with protective gas and heated and sintered, maintaining the temperature at about 700-1100°C for 0.5-2h, and the heating rate is 120-300°C / h.

[0031] S400 pressure solution According to an embodiment of the present invention, a pure copper solution is pressurized and infiltrated into the preform to obtain a diamond / copper composite material. It is understood that the preform sample is placed in a vacuum environment, heated and heated, and in a vacuum and pressurized state, a pure copper solution containing molten copper powder is pressurized and infiltrated into the porous preform to obtain a dense diamond / copper composite material part.

[0032] In addition, it should be noted that the pure copper solution melted from the copper powder is infiltrated into the porous preform under pressure. The mass ratio of the copper powder to the diamond is 63:46-18:7.

[0033] The present invention is described below with reference to specific examples and comparative examples. It should be noted that these examples are merely illustrative and are not to be construed as limiting the present invention.

[0034] Embodiment 1: A method for preparing a diamond / copper composite material by using a nano-metal of a binder prepared by Zr and jetting 3D printing the prepared binder is as follows: (1) The material is prepared using nano-metal Zr as a binder, and its average particle size is 30 nm.

[0035] The premix solution was prepared by dissolving 5wt% polyvinyl pyrrolidone (PVP) powder (as a binder) in anhydrous ethanol. The nano metal powder was added to the solution using an ultrasonic disperser to form a 6wt% suspension. In order to promote the decomposition of agglomerates and promote mixing, a polyether copolymer dispersant and 0.2wt% surfactant sodium dioctyl sulfonate succinate were added to the suspension, wherein 1g of polyether copolymer was added to every 100g of nano Zr powder, and the amount of sodium dioctyl sulfonate succinate added was 0.2wt% of the suspension, and then mechanical stirring was performed for 45min. Finally, the suspension was degassed in a vacuum chamber to remove trapped bubbles to obtain a nano metal suspension binder.

[0036] (2) Diamond green body was printed using binder jet 3D printing technology: a diamond green body with a bottom radius of 5 mm and a height of 1 mm was printed using a nano-metal suspension binder and diamond powder with an average particle size of 100 μm, where the binder saturation was set to 100%.

[0037] (3) Through curing and degreasing, the nano-metal particles are uniformly deposited on the surface of the diamond particles and fill the pores. After the diamond green body is printed, the powder bed is moved to an oven and heated to 80°C for 2 hours to completely cure the binder and de-powder. Degreasing is performed in air, and the de-powdered diamond green body is placed in a muffle furnace. Starting from room temperature, the muffle furnace is raised to 450°C at a rate of 5°C / min, and the sample is kept at 450°C for 40 minutes.

[0038] (4) Then, a sintering treatment is performed to make the nano-metal particles react with diamond to form a metal carbide layer to obtain a preform; specifically, the solidified and degreased sample is placed in a vacuum furnace, filled with protective gas and heated and sintered, maintaining the temperature at about 950°C for 1.5 hours, and the heating rate is 200 / h.

[0039] (5) Pressurized copper infiltration to obtain dense molded parts: The preform sample is placed in a vacuum environment, heated to 1200°C, and the pure copper solution melted by copper powder is infiltrated into the porous preform under vacuum pressure to obtain a dense cylindrical diamond / copper composite material. The mass ratio of copper powder to diamond is 63:46.

[0040] The performance of the cylindrical diamond / copper composite material obtained in Example 1 was tested, and the specific test results are as follows: The thermal conductivity of the diamond / copper composite material obtained in Example 1 can reach up to 690 W / (m·K).

[0041] Embodiment 2: This Example 2 is the same as Example 1, except that the mass fraction of Zr in the nanometal suspension in Example 1 is replaced with 8.5wt%. The thermal conductivity of the diamond / copper composite material obtained in Example 2 can reach up to 720W / (m·K).

[0042] Embodiment 3: This Example 3 is the same as Example 1, except that the mass fraction of Zr in the nanometal suspension in Example 1 is replaced by 12wt%. The thermal conductivity of the diamond / copper composite material obtained in Example 2 can reach up to 635W / (m·K).

[0043] In summary, the thermal conductivity of the composite material prepared by different nano metal mass fractions in embodiment 1-3 is different, and the mass fraction of nano metal in suspension has a significant effect on the thermal conductivity of diamond / copper composite material, wherein when the nano metal zirconium mass fraction is 8.5wt%, the thermal conductivity of the composite material reaches a maximum value substantially. Too low or too high mass fractions will cause thermal conductivity to decrease. Therefore, by changing the mass fraction of nano metal in the binder, the thickness of the surface metal carbide layer can be controlled so that the composite material reaches the best thermal conductivity.

[0044] Embodiment 4: A method for preparing a diamond / copper composite material by using Mo to prepare a nano-metal of a binder and using the prepared binder to jet 3D print is as follows: (1) The material is prepared using nano-metal Mo as a binder, and its average particle size is 50nm.

[0045] The premix solution was prepared by dissolving 6wt% polyvinyl alcohol (as a binder) in a deionized water solution. The nano metal powder was added to the solution using an ultrasonic disperser to form a 13wt% suspension. In order to promote the decomposition of agglomerates and promote mixing, 1g of polyether copolymer was added to the suspension for every 100g of nano Mo powder, and 0.2wt% of sodium dioctyl sulfosuccinate was added, and mechanical stirring was performed for 45min. Finally, the suspension was degassed in a vacuum chamber to remove trapped bubbles to obtain a nano metal suspension binder.

[0046] (2) Printing diamond green body using binder jet 3D printing technology: Use nano-metal suspension binder and diamond powder with an average particle size of 150 μm to print a cylindrical diamond green body with a bottom radius of 5 mm and a height of 1 mm. The binder saturation is set to 100%.

[0047] (3) Through curing and degreasing, the nano-metal particles are uniformly deposited on the surface of the diamond particles and fill the pores. After the diamond green body is printed, the powder bed is moved to an oven and heated to 75°C for 2 hours to completely cure the binder and de-powder. Degreasing is performed in air, and the de-powdered diamond green body is placed in a muffle furnace, starting from room temperature and rising to 300°C at a rate of 5°C / min. The sample is kept at 300°C for 50 minutes.

[0048] (4) Sintering treatment allows the nano-metal particles to react with diamond to form a metal carbide layer to obtain a preform; the solidified and degreased sample is placed in a vacuum furnace, filled with protective gas and heated for sintering, maintaining the temperature at about 700°C for 1.5 hours, and the heating rate is 200°C / h.

[0049] (5) Pressurized copper infiltration to obtain dense molded parts: The preform sample is placed in a vacuum environment and heated to 1200°C. Under vacuum and pressure, the pure copper solution melted by copper powder is infiltrated into the porous preform to obtain a dense cylindrical diamond / copper composite material. The mass ratio of copper powder to diamond is 12:7.

[0050] The performance of the cylindrical diamond / copper composite material obtained in Example 4 was tested, and the specific test results are as follows: The thermal conductivity of the diamond / copper composite material obtained in Example 4 can reach up to 656 W / (m·K).

[0051] It can be seen that when the nanometal is Zr or Mo, the prepared composite materials have higher thermal conductivity.

[0052] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a diamond / copper composite material by binder jet 3D printing, characterized in that: include: Adding nano-metal powder to a binder solution to form a suspension, adding a dispersant and a surfactant to the suspension and stirring to form a nano-metal suspension binder; Printing diamond green body by using the nano metal suspension binder and diamond powder; The diamond green body is solidified and degreased, and then sintered to obtain a preform; A pure copper solution is taken for pressure infiltration into the preform to obtain a diamond / copper composite material.

2. The method according to claim 1, characterized in that The binder solution is an anhydrous ethanol solution of polyvinyl pyrrolidone or a deionized water solution of polyvinyl alcohol; and / or, The mass fraction of the binder solution is 5-7wt%.

3. The method according to claim 1, characterized in that The mass fraction of the nano metal powder in the binder solution is 6-18 wt %.

4. The method according to claim 1 or 3, characterized in that: The nano metal powder is one of Cr, Ti, Zr, W and Mo.

5. The method according to claim 1, characterized in that Add 0.5-2 g of dispersant to every 100 g of the nano metal powder; and / or The added mass of the surfactant is 0.2% of the mass of the suspension.

6. The method according to claim 1, characterized in that The average particle size of the nano metal powder is 20-50 nm.

7. The method according to claim 1, characterized in that The average particle size of the diamond powder is 50-200 microns.

8. The method according to claim 1, characterized in that The specific process of curing and degreasing the diamond green embryo is as follows: The diamond green powder is moved to an oven and heated to 60-130° C. for 1.5-2 hours to completely cure the adhesive and remove the powder; The de-powdered sample was heated from room temperature to 200-500°C at a rate of 5-10°C / min and then kept at this temperature for 30-60min.

9. The method according to claim 1, characterized in that: The specific process of the sintering treatment is: after the diamond green body is solidified and degreased, it is placed in a vacuum furnace, filled with protective gas and heated to 700-1100° C. for 0.5-2 hours, with a heating rate of 120-300 / h.

10. The method according to claim 1, characterized in that The specific process of taking the pure copper solution for pressurized infiltration into the preform is: placing the preform in a vacuum environment, heating it up, and in the vacuum pressurized state, the pure copper solution containing molten copper powder is pressurized and infiltrated into the porous preform.

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