High performance diamond / silicon carbide composite and method of making same

Abstract

The present invention relates to a high performance diamond / silicon carbide composite material and a method for preparing the same. The high performance diamond / silicon carbide composite material comprises 10-20 wt% of a silicon carbide matrix phase and 60-70 wt% of diamond particle phase dispersed in the silicon carbide matrix phase.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide composite material preparation technology, specifically relating to a high-performance diamond / silicon carbide composite material and its preparation method. Background Technology

[0002] Diamond / silicon carbide composites have been widely used in electronic packaging and high-performance heat dissipation due to their excellent thermal conductivity, low coefficient of thermal expansion, and superior mechanical properties. However, diamond / silicon carbide composites prepared by traditional methods have certain limitations in their microstructure, resulting in poor performance in properties such as bonding strength and coefficient of thermal expansion, which cannot meet the requirements for higher performance. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a method for preparing high-performance diamond / silicon carbide composite materials using submicron-sized diamond powder as a carbon source through pressureless liquid-phase infiltration. By precisely controlling the amount and particle size of diamond micropowder, the thermal conductivity, mechanical properties, and thermal stability of the composite material are significantly improved, thereby meeting the needs of high-end application fields.

[0004] In a first aspect, the present invention provides a high-performance diamond / silicon carbide composite material, wherein the high-performance diamond / silicon carbide composite material comprises: 10-20 wt% silicon carbide matrix phase and 60-70 wt% diamond particle phase dispersed in the silicon carbide matrix phase.

[0005] Preferably, the high-performance diamond / silicon carbide composite material has a thermal conductivity of ≥600 W / m·K at 25℃, more preferably ≥658 W / m·K; and a coefficient of thermal expansion of 2.4-2.6 × 10⁻⁶ at 50-400℃. -6 K -1 ; Bending strength ≥380MPa, preferably ≥435MPa.

[0006] Secondly, the present invention provides a method for preparing the above-mentioned high-performance diamond / silicon carbide composite material, the method comprising the following steps: (1) Mix diamond particles, diamond micro powder and binder solution to obtain raw material mixture slurry; (2) The raw material mixture slurry is granulated and molded to obtain a composite material preform; (3) The composite material preform is degreased to obtain a porous composite material preform; (4) The porous preform of the composite material is subjected to silicon infiltration treatment to obtain the high-performance diamond / silicon carbide composite material.

[0007] Preferably, in step (1), the diamond particles have a particle size of 50-400 μm.

[0008] Preferably, in step (1), the diamond micropowder has a particle size of 0.1-2 μm, more preferably 0.1-0.9 μm, and even more preferably 0.5 μm; and a specific surface area > 20 m². 2 / g.

[0009] Preferably, in step (1), the adhesive solution contains at least one of phenolic resin and epoxy resin, and the solvent is ethanol; preferably, the adhesive content in the adhesive solution is controlled to be 35-50% by mass and the solvent content is 50-65% by mass.

[0010] Preferably, in step (1), based on the total mass of the diamond particles, diamond micro powder and binder as 100%, the mass percentage of diamond particles is 80-94%, the mass percentage of diamond micro powder is 5-15%, and the mass percentage of binder is 1-10%; more preferably, the mass percentage of diamond particles is 90%, the mass percentage of diamond micro powder is 5%, and the mass percentage of binder is 5%.

[0011] Preferably, in step (1), the diamond particles, diamond micro powder and binder solution are mixed by ball milling, with a ball milling speed of 200-600 rpm and a ball milling time of 8-10 h.

[0012] Preferably, in step (3), the degreasing treatment is performed by keeping the composite material blank at 700-1200℃ for 0.5-2h in a vacuum environment.

[0013] Preferably, in step (4), the silicon infiltration process is carried out in a vacuum environment of 1-3 MPa, and the silicon particles used in the silicon infiltration process have a purity of ≥90%; the silicon infiltration process is carried out at a temperature of 1500-1700℃ for 1-3 hours.

[0014] Beneficial effects (1) Improve the thermal conductivity of the material to 658 W / m·K (at room temperature of 25℃); (2) Reduce the coefficient of thermal expansion of the composite material, controlling it to 2.4-2.6×10⁻⁶ within the range of 50-400℃. -6 K -1 ; (3) Optimize the microstructure to make the material more compact and reduce porosity; (4) Improve the mechanical properties of the material, including elastic modulus and flexural strength. Detailed Implementation

[0015] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0016] First, the present invention provides a high-performance diamond / silicon carbide composite material. The composition of the high-performance diamond / silicon carbide composite material may include: 10-20 wt% silicon carbide matrix phase, and 60-70 wt% diamond particle phase dispersed in the silicon carbide matrix phase.

[0017] In some embodiments, the high-performance diamond / silicon carbide composite material has a room temperature (25°C) thermal conductivity ≥600 W / m·K, preferably ≥658 W / m·K; and a coefficient of thermal expansion at 50-400°C of 2.4-2.6 × 10⁻⁶. -6 K -1 ; Bending strength ≥380MPa, preferably ≥435MPa.

[0018] The following is an exemplary description of a method for preparing the high-performance diamond / silicon carbide composite material provided by the present invention. The preparation method may include the following steps: (1) Mix diamond particles, diamond micro powder and binder solution to obtain raw material mixture slurry; (2) The raw material mixture slurry is granulated and molded to obtain a composite material preform; (3) The composite material preform is degreased to obtain a porous composite material preform; (4) The porous preform of the composite material is subjected to silicon infiltration treatment to obtain the high-performance diamond / silicon carbide composite material.

[0019] In some embodiments, in step (1), the diamond particles can have a particle size of 50-400 μm. The diamond particles ultimately exist as a reinforcing phase in the composite material, enhancing its thermal and mechanical properties. However, if the diamond particle size is too large, the flexural strength of the composite material will be significantly reduced; if the particle size is too small, the thermal conductivity of the composite material will not be significantly improved.

[0020] In some embodiments, in step (1), the particle size of the diamond micropowder can be 0.1-2 μm, preferably 0.1-0.9 μm, and more preferably 0.5 μm; the specific surface area can be >20 m². 2 / g.

[0021] By controlling the particle size and specific surface area of ​​diamond micropowder within a suitable range, its high crystal quality and highly ordered crystal structure can be guaranteed. The reaction expansion rate with liquid silicon is higher, which can effectively reduce the residual silicon content in the composite material, optimize the phase composition of the composite material, and thus promote the improvement of the mechanical properties and thermal conductivity of the composite material, and significantly improve the bonding strength and thermal stability of the composite material.

[0022] If the diamond powder particle size is too large, the surface area of ​​the carbon source particles will be small, resulting in fewer reaction interfaces with diamond / SiC, a slower reaction rate, and ultimately incomplete or excessively long reaction times, affecting the final properties of the composite material. If the diamond powder particle size is too small, its specific surface area will be large, causing the reaction to be too fast, resulting in coarse or excessive SiC phase, affecting the microstructure and properties of the material. Furthermore, excessively small carbon source particles may be difficult to distribute uniformly, leading to excessively strong or uneven local reactions, which in turn affects the structural stability and properties of the final material.

[0023] In some embodiments, in step (1), the adhesive solution may contain at least one of phenolic resin and epoxy resin, and the solvent may contain ethanol; preferably, the adhesive content in the adhesive solution may be controlled to be 35-50% by mass and the solvent content may be 50-65% by mass.

[0024] In some embodiments, in step (1), based on the total mass of the diamond particles, diamond powder and binder as 100%, the mass percentage of diamond particles can be 80-94%, the mass percentage of diamond powder can be 5-15%, and the mass percentage of binder can be 1-10%; preferably, the mass percentage of diamond particles is 90%, the mass percentage of diamond powder is 5%, and the mass percentage of binder is 5%.

[0025] By controlling the mass ratio of the three raw materials within the aforementioned range, optimal powder flowability and molding effect can be ensured. An excessively high proportion of diamond particles will affect the machinability of the composite material, making processing difficult, and will also affect the bonding strength between the diamond particles and the SiC matrix, thus impacting the mechanical properties of the composite material. Conversely, an excessively low proportion of diamond particles will lead to a reduction in the reinforcing phase content, hindering the improvement of composite material performance. An excessively high proportion of diamond micron powder will result in excessive SiC formation in the composite material, causing changes in the coefficient of thermal expansion and mechanical properties. An excessively low proportion of diamond micron powder will lead to incomplete reaction with Si, resulting in a higher content of harmful residual silicon phase in the composite material. An excessively high proportion of binder will result in poor powder flowability and decreased uniformity of the composite material. An excessively low proportion of binder will prevent the powder from being molded, affecting the final density and shape of the composite material.

[0026] In some embodiments, in step (1), the diamond particles, diamond micro powder and binder solution are mixed by ball milling, the ball milling speed is 200-600 rpm and the ball milling time is 8-10 h.

[0027] In some embodiments, in step (2), the molding method can be: placing the powder after granulation of the raw material mixture into a steel mold and pressing it at 45-60 MPa.

[0028] In some embodiments, in step (3), the degreasing process can be carried out by keeping the composite material preform at 700-1200℃ for 0.5-2h in a vacuum environment.

[0029] In some embodiments, in step (4), the silicon infiltration treatment is carried out under a vacuum environment of 1-3 MPa, and the silicon particles used in the silicon infiltration treatment have a purity of ≥90%; the temperature of the silicon infiltration treatment can be 1500-1700℃, and the time can be 1-3 hours. These melting and infiltration conditions help the silicon liquid enter the porous ceramic structure, promote the full reaction between the diamond micropowder and the silicon liquid, increase the silicon carbide content, and reduce the residual silicon content.

[0030] Excessive siliconizing temperature can lead to graphitization of the diamond particle surface, affecting the composite material's performance. Insufficient siliconizing temperature results in incomplete siliconizing, insufficient SiC formation, and a low SiC content. Excessive siliconizing time leads to excessive SiC formation, increasing material brittleness and reducing its impact resistance and toughness. Insufficient siliconizing time results in insufficient SiC formation, causing uneven structure in the composite material and affecting its thermal conductivity and mechanical properties.

[0031] Silicon infiltration is achieved by placing silicon particles above and below a multiphase ceramic preform. During infiltration, the silicon particles melt into molten silicon, which then enters the multiphase ceramic preform under the influence of capillary force and gravity to react. The molten silicon enters the preform, promoting a full reaction between the molten silicon and diamond micropowder to generate silicon carbide. This effectively reduces the residual silicon content within the diamond / silicon carbide composite material, thereby improving its mechanical and thermal properties.

[0032] Among them, diamond micro powder reacts with Si to form the highest expansion rate. Using diamond micro powder as a carbon source to prepare composite materials can generate more matrix SiC to fill the pores between diamond particles. Since there is an excess of Si liquid during reaction sintering, it will fill the remaining pores where matrix SiC has not been generated. Thus, the content of SiC phase is increased and the content of residual Si phase is reduced. High-performance diamond / silicon carbide composite materials are obtained from the perspective of microstructure and phase composition.

[0033] In summary, the preparation method provided by this invention innovatively introduces submicron-sized diamond powder, utilizing its higher reaction expansion rate with liquid silicon. Through a liquid-phase melting and infiltration reaction sintering process with silicon, the thermal conductivity, mechanical properties (including elastic modulus and flexural strength), and coefficient of thermal expansion of the composite material are significantly improved. The microstructure of the composite material is optimized, making the material more dense and reducing porosity. Moreover, the preparation method provided by this invention has the advantages of simple process and strong controllability.

[0034] The high-performance diamond / silicon carbide composite material obtained by the preparation method provided by this invention has excellent thermal conductivity and high flexural strength at room temperature, which can meet the needs of high-performance diamond / silicon carbide composite materials in fields such as electronic packaging, aerospace, and energy.

[0035] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0036] Example 1

[0037] The method for preparing the high-performance diamond / silicon carbide composite material provided in this embodiment includes the following steps: (1) Diamond particles, diamond micro powder with a particle size of 0.5 μm, and phenolic resin were wet-mixed in a ball mill at a mass ratio of 90:5:5 for 8 hours to obtain a raw material slurry. (2) The raw material mixture after ball milling is granulated to obtain a mixture powder, which is then placed in a mold and pressed at 50 MPa to obtain a composite material blank; (3) The pressed blank is degreased and kept at 1100℃ for 1.5h in a vacuum environment and cooled in the furnace to obtain a porous preform of composite material. (4) Place the preform in a graphite crucible, place silicon particles on the top and bottom, place the crucible in a vacuum sintering furnace for silicon infiltration treatment, the silicon infiltration temperature is 1600℃ and the vacuum degree is 3Mpa, and after silicon infiltration is completed, cool with the furnace to obtain the high-performance diamond / silicon carbide composite material.

[0038] Test methods: Bending strength test refers to "GBT6569-2006 - Test method for bending strength of fine ceramics"; thermal expansion coefficient test refers to "QBT 1321-1991 Determination method for average linear thermal expansion coefficient of ceramic materials"; thermal conductivity test method refers to "GB / T 22588-2008 Measurement of thermal diffusivity or thermal conductivity by flash method" to measure thermal conductivity, then use the water displacement method to measure material density, calculate the corresponding theoretical specific heat capacity, and finally calculate material thermal conductivity using formula.

[0039] Testing showed that the thermal conductivity of the diamond / silicon carbide composite material prepared in this embodiment was 658 W / m·K at 25℃, which is 25% higher than that of traditional materials; the coefficient of thermal expansion at 50-400℃ was 2.468 × 10⁻⁶. -6 K -1 The flexural strength is 435 MPa.

[0040] The composite material prepared in Example 1 was subjected to a high-temperature durability test in a high-temperature furnace at 800°C for 100 hours. After the high-temperature durability test, the following tests were performed on the material: (1) Thermal conductivity: The thermal conductivity of the composite material remained at 658 W / m·K, showing good thermal stability; (2) Mechanical properties: The flexural strength of the composite material was 433 MPa, without significant attenuation, showing good mechanical properties. The above tests prove that the diamond / silicon carbide composite material prepared using 0.5 μm diamond powder has excellent high-temperature durability and is suitable for use in high-temperature applications.

[0041] Example 2

[0042] The preparation method of the high-performance diamond / silicon carbide composite material provided in this embodiment is the same as that in Example 1, with the main difference being: In step (1), the particle size of the diamond powder is 0.2 μm.

[0043] Tests showed that the thermal conductivity of the diamond / silicon carbide composite material prepared in this embodiment was 600 W / m·K at 25℃, and the flexural strength was 400 MPa.

[0044] Example 3

[0045] The preparation method of the high-performance diamond / silicon carbide composite material provided in this embodiment is the same as that in Example 1, with the main difference being: In step (1), the particle size of the diamond powder is 0.4 μm.

[0046] According to the test results, the thermal conductivity of the diamond / silicon carbide composite material prepared in this embodiment at 25℃ is 622W / m·K; the flexural strength is 418MPa.

[0047] Example 4

[0048] The preparation method of the high-performance diamond / silicon carbide composite material provided in this embodiment is the same as that in Example 1, with the main difference being: In step (1), the particle size of the diamond powder is 0.6 μm.

[0049] According to the test results, the thermal conductivity of the diamond / silicon carbide composite material prepared in this embodiment at 25℃ is 620W / m·K; the flexural strength is 400MPa.

[0050] Example 5

[0051] The preparation method of the high-performance diamond / silicon carbide composite material provided in this embodiment is the same as that in Example 1, with the main difference being: In step (1), the mass ratio of diamond particles, diamond micro powder with a particle size of 0.5 μm, and phenolic resin is 85:10:5.

[0052] According to the test results, the thermal conductivity of the diamond / silicon carbide composite material prepared in this embodiment at 25℃ is 628 W / m·K; the flexural strength is 400 MPa.

[0053] Example 6

[0054] The preparation method of the high-performance diamond / silicon carbide composite material provided in this embodiment is the same as that in Example 1, with the main difference being: In step (1), the mass ratio of diamond particles, diamond micro powder with a particle size of 0.5 μm, and phenolic resin is 80:15:5.

[0055] According to the test results, the thermal conductivity of the diamond / silicon carbide composite material prepared in this embodiment at 25℃ is 616 W / m·K; the flexural strength is 380 MPa.

[0056] Comparative Example 1

[0057] The method for preparing the composite material provided in this comparative example is the same as in Example 1, with the main difference being: In step (1), diamond powder is replaced with carbon fiber.

[0058] Tests showed that the composite material prepared in this comparative example had a thermal conductivity of 598 W / m·K at 25℃ and a flexural strength of 398 MPa.

[0059] Comparative Example 2

[0060] The method for preparing the composite material provided in this comparative example is the same as in Example 1, with the main difference being: In step (1), diamond powder is replaced with carbon black.

[0061] The composite material prepared in this comparative example has a thermal conductivity of 589 W / m·K at 25℃ and a flexural strength of 386 MPa, as tested.

[0062] Comparative Example 3

[0063] The method for preparing the composite material provided in this comparative example is the same as in Example 1, with the main difference being: In step (1), diamond powder is replaced with boron carbide.

[0064] The composite material prepared in this comparative example has a thermal conductivity of 577 W / m·K at 25℃ and a flexural strength of 378 MPa, as tested.

[0065] Comparative Example 4

[0066] The method for preparing the composite material provided in this comparative example is the same as in Example 1, with the main difference being: In step (1), diamond powder was not used, and the mass ratio of diamond particles to phenolic resin was 95:5.

[0067] Tests showed that the composite material prepared in this comparative example had a thermal conductivity of 550 W / m·K at 25℃ and a flexural strength of 360 MPa. These properties are significantly lower than those of the diamond / silicon carbide composite materials prepared from diamond particles of two different particle sizes.

[0068] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A high-performance diamond / silicon carbide composite material, characterized in that, The high-performance diamond / silicon carbide composite material comprises: 10-20 wt% silicon carbide matrix phase and 60-70 wt% diamond particle phase dispersed in the silicon carbide matrix phase.

2. The high-performance diamond / silicon carbide composite material according to claim 1, characterized in that, The high-performance diamond / silicon carbide composite material has a thermal conductivity of ≥600 W / m·K at 25℃, preferably ≥658 W / m·K; and a coefficient of thermal expansion of 2.4-2.6 × 10⁻⁶ at 50-400℃. -6 K -1 ; Bending strength ≥380MPa, preferably ≥435MPa.

3. A method for preparing the high-performance diamond / silicon carbide composite material according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Mix diamond particles, diamond micro powder and binder solution to obtain raw material mixture slurry; (2) The raw material mixture slurry is granulated and molded to obtain a composite material preform; (3) The composite material preform is degreased to obtain a porous composite material preform; (4) The porous preform of the composite material is subjected to silicon infiltration treatment to obtain the high-performance diamond / silicon carbide composite material.

4. The preparation method according to claim 3, characterized in that, In step (1), the diamond particles have a particle size of 50-400 μm.

5. The preparation method according to claim 3 or 4, characterized in that, In step (1), the diamond micropowder has a particle size of 0.1-2 μm, preferably 0.1-0.9 μm, and more preferably 0.5 μm; and a specific surface area > 20 m². 2 / g.

6. The preparation method according to any one of claims 3-5, characterized in that, In step (1), the adhesive solution contains at least one of phenolic resin and epoxy resin as the adhesive and ethanol as the solvent. Preferably, the adhesive content in the adhesive solution is controlled to be 35-50% by mass and the solvent content is 50-65% by mass.

7. The preparation method according to any one of claims 3-6, characterized in that, In step (1), based on the total mass of the diamond particles, diamond micro powder and binder as 100%, the mass percentage of diamond particles is 80-94%, the mass percentage of diamond micro powder is 5-15%, and the mass percentage of binder is 1-10%; preferably, the mass percentage of diamond particles is 90%, the mass percentage of diamond micro powder is 5%, and the mass percentage of binder is 5%.

8. The preparation method according to any one of claims 3-7, characterized in that, In step (1), the diamond particles, diamond micro powder and binder solution are mixed by ball milling, with a ball milling speed of 200-600 rpm and a ball milling time of 8-10 h.

9. The preparation method according to any one of claims 3-8, characterized in that, In step (3), the degreasing process is performed by keeping the composite material preform at 700-1200℃ for 0.5-2 hours in a vacuum environment.

10. The preparation method according to any one of claims 3-9, characterized in that, In step (4), the silicon infiltration process is carried out in a vacuum environment of 1-3 MPa, and the silicon particles used in the silicon infiltration process have a purity of ≥90%; the silicon infiltration process temperature is 1500-1700℃ and the time is 1-3h.