High-strength and high-toughness heat-conducting cordierite ceramic and preparation method thereof

Abstract

The application provides a high-strength and high-toughness heat-conducting cordierite ceramic and a preparation method thereof, and belongs to the technical field of ceramics. The preparation method comprises the following steps: preparing silicon carbide nanofibers, preparing boron nitride nanofibers, preparing mixed powders, forming and post-treating. In the step of preparing the mixed powders, magnesium oxide, aluminum oxide and silicon oxide powder are uniformly mixed, mixed fibers are added, and after uniform stirring, ball milling treatment is performed, the ball milling time is 6-8h, the ball-to-material ratio is 5-10:1, the ball milling rotating speed is 200-300rpm, and after the ball milling is completed, drying is performed to obtain the mixed powders. The cordierite ceramic prepared by the application has high strength and toughness, good heat-conducting performance, excellent chemical resistance and stability.

Description

Technical Field

[0001] This invention belongs to the field of ceramic technology, specifically relating to a high-strength and high-toughness thermally conductive cordierite ceramic and its preparation method. Background Technology

[0002] With the rapid development of semiconductor technology, electronic devices are constantly evolving towards smaller size, higher performance and greater power density. During their operation, a large amount of heat is generated. If it cannot be dissipated in a timely and effective manner, the chip's operating temperature will rise sharply. Excessive temperature will seriously affect the performance, reliability and lifespan of semiconductor devices.

[0003] Traditional metal heat dissipation materials such as copper and aluminum, although they have high thermal conductivity, have a large coefficient of thermal expansion, resulting in poor thermal matching with semiconductor chips. This can easily generate large thermal stress at the interface, affecting heat dissipation performance and chip stability. While ordinary ceramic materials have certain advantages in some aspects, their overall heat dissipation performance is insufficient to meet the ever-increasing heat dissipation requirements of semiconductor devices.

[0004] Cordierite ceramics have great application potential in the field of semiconductor heat dissipation due to their unique low coefficient of thermal expansion, high mechanical strength, good chemical stability and certain thermal conductivity. However, the existing cordierite ceramic heat dissipation structure and preparation process still need to be further optimized to improve its heat dissipation efficiency and overall performance.

[0005] Chinese patent CN115959894A discloses a method for preparing a high-elastic-modulus dense cordierite ceramic material, which has high density, low coefficient of thermal expansion and high elastic modulus. The low thermal expansion can ensure that the dimensional accuracy of the moving platform is not affected by the fluctuation of ambient temperature and the temperature change caused by the processing, while the high modulus can ensure that the moving platform will not deform even when subjected to large external forces, thereby ensuring the working accuracy of the moving platform.

[0006] While the cordierite ceramic material disclosed in this patent possesses high elastic modulus and low coefficient of thermal expansion, making it suitable for precision moving platforms, its toughness and thermal conductivity are poor. Its thermal conductivity relies primarily on the matrix material itself, making it difficult to meet the rapid heat dissipation requirements of high-power semiconductor devices. Furthermore, the product manufactured using this patent exhibits high interfacial thermal resistance, limiting its application in the semiconductor heat dissipation field.

[0007] Chinese patent CN105452191A discloses a method for firing cordierite bodies, wherein the green body is heated to a low firing temperature in a firing atmosphere sufficient to reduce the content of organic materials and to remove chemically bound water essentially from hydrated alumina; and the green body is heated to a high firing temperature in a firing atmosphere sufficient to reduce the content of organic materials before removing chemically bound water essentially from clay.

[0008] This patent mainly focuses on the removal of organic materials and the dehydration process of clay during firing, aiming to prevent the green body from cracking. The cordierite ceramics produced are porous and suitable for filters or catalyst carriers. However, they do not have high thermal conductivity, high toughness, and high mechanical strength, and cannot meet the requirements of semiconductor devices for efficient heat dissipation and structural stability.

[0009] Further research by technicians revealed that existing cordierite ceramics are mostly used in low thermal expansion and thermal shock resistant applications, such as catalyst supports and filters. However, their thermal conductivity is poor, and their mechanical strength and toughness fail to meet the heat dissipation requirements of semiconductors. Some studies have attempted to add a single reinforcing phase, but it is difficult to achieve a synergistic improvement in thermal conductivity, strength, and toughness. Existing technologies do not disclose the simultaneous introduction of silicon carbide nanofibers and boron nitride nanofibers into cordierite ceramic matrices to achieve high strength, high toughness, and thermal conductivity. During the research and development process, the engineers found that the nanofibers have poor dispersibility and are prone to agglomeration, resulting in uneven reinforcement and thus failing to effectively exert the reinforcing properties of the fibers. Furthermore, the resulting ceramic products have poor thermal conductivity and poor chemical stability. Therefore, providing a cordierite ceramic and its preparation method, using silicon carbide nanofibers and boron nitride nanofibers as reinforcing phases, improving the dispersibility of nanofibers while enhancing the compatibility between nanofibers and the cordierite ceramic matrix, enhancing the strength and toughness of the product, and improving thermal conductivity and chemical stability are technical problems that urgently need to be solved in the existing technology. Summary of the Invention

[0010] To address the problems of existing technologies, this invention provides a high-strength and high-toughness thermally conductive cordierite ceramic and its preparation method. The method involves introducing silicon carbide and boron nitride nanofibers into the cordierite ceramic formulation system to improve fiber dispersibility and enhance compatibility with the cordierite ceramic matrix. This improves the ceramic's toughness and thermal conductivity while simultaneously enhancing its mechanical strength and stability to adapt to complex semiconductor operating environments.

[0011] To address the aforementioned technical problems, the present invention adopts the following technical solution: A method for preparing high-strength and high-toughness thermally conductive cordierite ceramics includes the following steps: preparing silicon carbide nanofibers, preparing boron nitride nanofibers, preparing mixed powders, molding, and post-treatment. The specific operations are as follows: 1. Preparation of silicon carbide nanofibers Polycarbosilane was dissolved in DMF solvent, and polyvinylpyrrolidone was added. The mixture was stirred at room temperature for 10-12 hours to obtain a spinning precursor solution. The spinning precursor solution was spun using electrospinning, with the voltage controlled at 15-20 kV, the propulsion rate of the spinning precursor solution at 0.5-0.8 mL / s, the distance from the needle tip to the collector at 12-15 cm, and the spinning temperature at 20-25 °C. After spinning, the mixture was dried at 50-80 °C for 8-12 hours, and then heated to 800-1200 °C at a rate of 2-3 °C / min and held for 2-3 hours to obtain silicon carbide nanofibers. The mass ratio of polycarbosilane, DMF, and polyvinylpyrrolidone is 5-10:78-87:8-12.

[0012] The silicon carbide nanofibers have a length of 5-15 μm and a fiber diameter of 200-300 nm.

[0013] 2. Preparation of boron nitride nanofibers Polyborane was dissolved in DMF solvent, polyvinylpyrrolidone was added, and the mixture was stirred at room temperature for 10-12 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning, with the voltage controlled at 15-20 kV, the pushing speed of the spinning precursor solution at 0.5-0.8 mL / s, the distance from the needle tip to the collector at 12-15 cm, and the spinning temperature at 20-25 ℃. After spinning, the solution was dried at 50-80 ℃ for 8-12 h, and then heated to 800-1200 ℃ at a rate of 2-3 ℃ / min and held for 2-3 h to obtain boron nitride nanofibers. The mass ratio of the polyborazine, DMF, and polyvinylpyrrolidone is 5-10:78-87:8-12.

[0014] The boron nitride nanofibers have a length of 5-15 μm and a fiber diameter of 200-300 nm.

[0015] 3. Preparation of mixed powder Magnesium oxide, aluminum oxide, and silicon oxide powders are mixed evenly, mixed fibers are added, and after stirring evenly, ball milling is performed for 6-8 hours, with a ball-to-material ratio of 5-10:1 and a ball milling speed of 200-300 rpm. After ball milling, the mixture is dried to obtain a mixed powder. The mass ratio of magnesium oxide powder, aluminum oxide powder, and silicon oxide powder is 12-15:33-37:48-55; The amount of the mixed fiber is 10-20 wt% of the mixed powder; The mixed fibers are silicon carbide nanofibers and boron nitride nanofibers, with a mass ratio of silicon carbide nanofibers to boron nitride nanofibers of 1:1.

[0016] 4. Molding The mixed powder is loaded into a mold and cold isostatically pressed at a pressure of 200-300 MPa to obtain a green body. The green body is then placed in a high-temperature sintering furnace for sintering. The temperature is increased to 1200-1400℃ at a rate of 3-5℃ / min and held for 2-4 hours. After natural cooling to room temperature, a cordierite ceramic matrix containing the reinforcing phase is obtained.

[0017] 5. Post-processing A cordierite ceramic substrate containing the reinforcing phase is placed into the deposition chamber of a magnetron sputtering apparatus. A copper or aluminum target is coated with a metallized thermally conductive layer, and the vacuum level of the deposition chamber is controlled to be 2-4 × 10⁻⁴. -4 The deposition atmosphere was argon, with an argon flow rate of 20-30 sccm and a pressure of 0.5-1.0 Pa. The sputtering power was 100-200 W, the sputtering time was 30-60 min, and the thickness of the metallized thermally conductive layer was controlled to be 1-3 μm to obtain cordierite ceramics.

[0018] A high-strength and high-toughness thermally conductive cordierite ceramic was prepared using the aforementioned method.

[0019] This invention employs boron nitride fiber and silicon carbide fiber as fiber reinforcement phases. Specifically, polycarbosilane and polyboronazine are used as raw materials, and short fibers are obtained through electrospinning and high-temperature pyrolysis to control their effective aspect ratio, which is beneficial for load-bearing and force transmission. Magnesium oxide, silicon dioxide, and aluminum oxide are used as the cordierite system, and cordierite is obtained by high-temperature sintering. Silicon carbide fiber and boron nitride fiber are mixed and dispersed in a 1:1 ratio to form an interpenetrating network. Under the combined action of the two fibers, the mechanical strength and toughness of the ceramic can be effectively enhanced, the thermal conductivity can be significantly improved, and the stability of the ceramic product can be effectively enhanced. This allows the ceramic product to withstand various mechanical stresses and vibrations during the processing, packaging, and use of semiconductor devices, while promoting rapid heat transfer and dissipation. It is suitable for chemically corrosive environments such as acids and alkalis, as well as complex environments such as high-temperature water quenching. Combined with the metallized coating on the surface, the thermal conductivity between the ceramic product and the semiconductor chip is significantly improved, the interfacial thermal resistance is effectively reduced, and the heat from the chip can be quickly transferred to the ceramic matrix for heat dissipation, ensuring the overall stability of the ceramic product.

[0020] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. The cordierite ceramic prepared by this invention has a flexural strength of 245-253 MPa and a fracture toughness of 6.8-7.3 MPa·m. 1 / 2 The coefficient of thermal expansion at RT-600℃ is 0.5-0.8×10⁻⁶. -6 The thermal conductivity is 5.2-5.6 W / (m·K). 2. The cordierite ceramic prepared by this invention was immersed in a 5wt% HCl solution at 35°C for 24 hours, then dried. It was then immersed in a 5wt% NaOH solution at 35°C for 24 hours, dried, and the flexural strength was measured again to be 237-245 MPa, and the fracture toughness was 6.5-7.0 MPa·m. 1 / 2 ; 3. The cordierite ceramic prepared by this invention was placed in air and left to stand at 800°C for 12 hours, then immediately placed in deionized water at 20°C and left to stand for 12 hours. This process constituted one treatment cycle, and was repeated for 15 cycles. The flexural strength was then measured to be 233-242 MPa, and the fracture toughness was measured to be 6.4-7.0 MPa·m. 1 / 2 . Detailed Implementation

[0021] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments of the invention will be described first.

[0022] Example 1 1. Preparation of silicon carbide nanofibers Polycarbosilane was dissolved in DMF solvent, and polyvinylpyrrolidone was added. The mixture was stirred at room temperature for 11 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning with a controlled voltage of 18 kV, a pushing speed of 0.7 mL / s, a needle tip to collector distance of 13 cm, and a spinning temperature of 23 °C. After spinning, the mixture was dried at 65 °C for 10 h, and then heated to 1000 °C at a rate of 2.5 °C / min and held for 2.5 h to obtain silicon carbide nanofibers. The mass ratio of polycarbosilane, DMF, and polyvinylpyrrolidone is 8:82:10.

[0023] The silicon carbide nanofibers are 10 μm long and 250 nm in diameter.

[0024] 2. Preparation of boron nitride nanofibers Polyborane was dissolved in DMF solvent, polyvinylpyrrolidone was added, and the mixture was stirred at room temperature for 11 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning, with the voltage controlled at 18 kV, the pushing speed of the spinning precursor solution at 0.7 mL / s, the distance from the needle tip to the collector at 13 cm, and the spinning temperature at 23 °C. After spinning, the solution was dried at 65 °C for 10 h, and then heated to 1000 °C at a rate of 2.5 °C / min and held for 2.5 h to obtain boron nitride nanofibers. The mass ratio of polyborazine, DMF, and polyvinylpyrrolidone is 8:82:10.

[0025] The boron nitride nanofibers are 10 μm long and 250 nm in diameter.

[0026] 3. Preparation of mixed powder Magnesium oxide, aluminum oxide, and silicon oxide powders were mixed evenly, mixed fibers were added, and after stirring evenly, the mixture was ball-milled for 7 hours at a ball-to-material ratio of 7:1 and a ball-milling speed of 250 rpm. After ball milling, the mixture was dried to obtain a mixed powder. The mass ratio of magnesium oxide powder, aluminum oxide powder, and silicon oxide powder is 13:35:52; The amount of the mixed fiber is 15 wt% of the mixed powder; The mixed fibers are silicon carbide nanofibers and boron nitride nanofibers, with a mass ratio of silicon carbide nanofibers to boron nitride nanofibers of 1:1.

[0027] 4. Molding The mixed powder is loaded into a mold and cold isostatically pressed at a pressure of 250 MPa to obtain a green body. The green body is then placed in a high-temperature sintering furnace for sintering. The temperature is increased to 1300℃ at a rate of 4℃ / min and held for 3 hours. After natural cooling to room temperature, a cordierite ceramic matrix containing the reinforcing phase is obtained.

[0028] 5. Post-processing A cordierite ceramic matrix containing the reinforcing phase was placed into the deposition chamber of a magnetron sputtering apparatus. A copper target was coated with a metallized thermal conductive layer, and the vacuum level of the deposition chamber was controlled at 3 × 10⁻⁶. -4 The deposition atmosphere was argon, with an argon flow rate of 25 sccm and a pressure of 0.7 Pa. The sputtering power was 150 W, the sputtering time was 45 min, and the thickness of the metallized thermally conductive layer was controlled to be 2 μm to obtain cordierite ceramic.

[0029] Example 2 1. Preparation of silicon carbide nanofibers Polycarbosilane was dissolved in DMF solvent, polyvinylpyrrolidone was added, and the mixture was stirred at room temperature for 12 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning, with the voltage controlled at 20 kV, the pushing speed of the spinning precursor solution at 0.8 mL / s, the distance from the needle tip to the collector at 15 cm, and the spinning temperature at 25 °C. After spinning, the mixture was dried at 80 °C for 8 h, and then heated to 1200 °C at a rate of 3 °C / min and held for 3 h to obtain silicon carbide nanofibers. The mass ratio of polycarbosilane, DMF, and polyvinylpyrrolidone is 10:78:12.

[0030] The silicon carbide nanofibers are 15 μm long and 300 nm in diameter.

[0031] 2. Preparation of boron nitride nanofibers Polyborane was dissolved in DMF solvent, polyvinylpyrrolidone was added, and the mixture was stirred at room temperature for 12 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning, with the voltage controlled at 20 kV, the pushing speed of the spinning precursor solution at 0.8 mL / s, the distance from the needle tip to the collector at 15 cm, and the spinning temperature at 25 °C. After spinning, the solution was dried at 80 °C for 8 h, and then heated to 1200 °C at a rate of 3 °C / min and held for 3 h to obtain boron nitride nanofibers. The mass ratio of polyborazine, DMF, and polyvinylpyrrolidone is 10:78:12.

[0032] The boron nitride nanofibers are 15 μm long and 300 nm in diameter.

[0033] 3. Preparation of mixed powder Magnesium oxide, aluminum oxide, and silicon oxide powders were mixed evenly, mixed fibers were added, and after stirring evenly, the mixture was ball-milled for 8 hours at a ball-to-material ratio of 10:1 at a speed of 300 rpm. After ball milling, the mixture was dried to obtain a mixed powder. The mass ratio of magnesium oxide powder, aluminum oxide powder, and silicon oxide powder is 15:37:55; The amount of the mixed fiber is 20 wt% of the mixed powder; The mixed fibers are silicon carbide nanofibers and boron nitride nanofibers, with a mass ratio of silicon carbide nanofibers to boron nitride nanofibers of 1:1.

[0034] 4. Molding The mixed powder is loaded into a mold and cold isostatically pressed at a pressure of 300 MPa to obtain a green body. The green body is then placed in a high-temperature sintering furnace for sintering. The temperature is increased to 1400℃ at a rate of 5℃ / min and held for 4 hours. After natural cooling to room temperature, a cordierite ceramic matrix containing the reinforcing phase is obtained.

[0035] 5. Post-processing A cordierite ceramic matrix containing the reinforcing phase was placed into the deposition chamber of a magnetron sputtering apparatus. An aluminum target was coated with a metallized thermally conductive layer, and the vacuum level of the deposition chamber was controlled at 4 × 10⁻⁶. -4 The deposition atmosphere was argon, with an argon flow rate of 30 sccm and a pressure of 1.0 Pa. The sputtering power was 200 W, the sputtering time was 60 min, and the thickness of the metallized thermally conductive layer was controlled to be 3 μm to obtain cordierite ceramics.

[0036] Example 3 1. Preparation of silicon carbide nanofibers Polycarbosilane was dissolved in DMF solvent, polyvinylpyrrolidone was added, and the mixture was stirred at room temperature for 10 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning, with the voltage controlled at 15 kV, the pushing speed of the spinning precursor solution at 0.5 mL / s, the distance from the needle tip to the collector at 12 cm, and the spinning temperature at 20 °C. After spinning, the mixture was dried at 50 °C for 12 h, and then heated to 800 °C at a rate of 2 °C / min and held for 2 h to obtain silicon carbide nanofibers. The mass ratio of polycarbosilane, DMF, and polyvinylpyrrolidone is 5:87:8.

[0037] The silicon carbide nanofibers have a length of 5 μm and a fiber diameter of 200 nm.

[0038] 2. Preparation of boron nitride nanofibers Polyborane was dissolved in DMF solvent, polyvinylpyrrolidone was added, and the mixture was stirred at room temperature for 10 h to obtain a spinning precursor solution. The spinning precursor solution was spun by electrospinning, with the voltage controlled at 15 kV, the pushing speed of the spinning precursor solution at 0.5 mL / s, the distance from the needle tip to the collector at 12 cm, and the spinning temperature at 20 °C. After spinning, the solution was dried at 50 °C for 12 h, and then heated to 800 °C at a rate of 2 °C / min and held for 2 h to obtain boron nitride nanofibers. The mass ratio of polyborazine, DMF, and polyvinylpyrrolidone is 5:87:8.

[0039] The boron nitride nanofibers have a length of 5 μm and a fiber diameter of 200 nm.

[0040] 3. Preparation of mixed powder Magnesium oxide, aluminum oxide, and silicon oxide powders were mixed evenly, mixed fibers were added, and after stirring evenly, the mixture was ball-milled for 6 hours at a ball-to-material ratio of 5:1 and a ball-milling speed of 200 rpm. After ball milling, the mixture was dried to obtain a mixed powder. The mass ratio of magnesium oxide powder, aluminum oxide powder, and silicon oxide powder is 12:33:48; The amount of the mixed fiber is 10 wt% of the mixed powder; The mixed fibers are silicon carbide nanofibers and boron nitride nanofibers, with a mass ratio of silicon carbide nanofibers to boron nitride nanofibers of 1:1.

[0041] 4. Molding The mixed powder is loaded into a mold and cold isostatically pressed at a pressure of 200 MPa to obtain a green body. The green body is then placed in a high-temperature sintering furnace for sintering. The temperature is increased to 1200°C at a rate of 3°C / min and held for 2 hours. After natural cooling to room temperature, a cordierite ceramic matrix containing the reinforcing phase is obtained.

[0042] 5. Post-processing A cordierite ceramic matrix containing the reinforcing phase was placed into the deposition chamber of a magnetron sputtering apparatus. A copper target was coated with a metallized thermal conductive layer, and the vacuum level of the deposition chamber was controlled to be 2 × 10⁻⁶. -4 The deposition atmosphere was argon, with an argon flow rate of 20 sccm and a pressure of 0.5 Pa. The sputtering power was 100 W, the sputtering time was 30 min, and the thickness of the metallized thermally conductive layer was controlled to be 1 μm to obtain cordierite ceramics.

[0043] Comparative Example 1.1 The changes are based on Example 1, namely: The preparation steps of silicon carbide nanofibers are omitted; during the preparation of the mixed powder, silicon carbide nanofibers are replaced with boron nitride nanofibers in equal amounts. The cordierite ceramic matrix containing the reinforcing phase obtained by omitting the post-processing steps and forming steps is the cordierite ceramic product. The rest of the operations are exactly the same.

[0044] Comparative Example 1.2 The changes are based on Example 1, namely: The preparation steps of boron nitride nanofibers are omitted; during the preparation of the mixed powder, boron nitride nanofibers are replaced with an equal amount of silicon carbide nanofibers. The rest of the operations are exactly the same.

[0045] Performance testing 1. The cordierite ceramics prepared in Examples 1-3, Comparative Example 2.1, and Comparative Example 2.2 were tested for flexural strength, fracture toughness, coefficient of thermal expansion, and thermal conductivity, respectively. The test results are as follows:

[0046] 2. The cordierite ceramics obtained in Examples 1-3, Comparative Examples 2.1, and Comparative Example 2.2 were respectively placed in a 5wt% HCl solution, with the HCl solution completely submerging the cordierite ceramics. They were soaked at 35°C for 24 hours, then removed and dried at 90°C for 12 hours. Next, they were placed in a 5wt% NaOH solution, with the NaOH solution completely submerging the cordierite ceramics. They were soaked at 35°C for 24 hours, then removed and dried at 90°C for 12 hours. After naturally cooling to room temperature, the flexural strength and fracture toughness were tested again. The test results are as follows:

[0047] 3. The cordierite ceramics obtained in Examples 1-3, Comparative Examples 2.1, and Comparative Examples 2.2 were placed in air and allowed to stand at 800°C for 12 hours. Then, they were immediately placed in deionized water at 20°C and allowed to stand for 12 hours, ensuring the deionized water completely submerged the cordierite ceramics. After standing, they were removed and dried at 90°C for 12 hours, then allowed to cool naturally to room temperature. This process constituted one treatment cycle, and 15 cycles were performed consecutively. The flexural strength and fracture toughness were then tested again, and the results are as follows:

[0048] Based on the test results above, it can be seen that Comparative Example 2.1 only uses boron nitride fiber as a reinforcing phase, lacking silicon carbide fiber component, and does not have a metal layer coated on its surface. The strength and toughness of the boron nitride fiber itself are poor, resulting in a decrease in the bending strength and fracture toughness of the product. Although boron nitride fiber has good thermal conductivity, it lacks a metal layer coating, so the thermal conductivity of Comparative Example 2.1 still cannot reach the level of Example 1. The lack of synergy with silicon carbide fiber leads to a decrease in the overall performance of the product. After chemical corrosion and high-temperature water quenching treatment, the strength and toughness drop sharply. Comparative Example 2.2 omits boron nitride fiber. Although it has good mechanical properties, the interface between the single silicon carbide fiber and the cordierite matrix has limited thermal expansion matching, which increases the thermal expansion coefficient of the product. Although it has a metal layer for thermal conductivity on its surface, the internal thermal conductive skeleton is incomplete, resulting in a decrease in the thermal conductivity of the product. It cannot achieve the best match between mechanical properties and thermal conductivity, resulting in a decrease in overall performance.

[0049] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0050] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, high-toughness, thermally conductive cordierite ceramic, characterized in that, The process includes steps such as preparing silicon carbide nanofibers, preparing boron nitride nanofibers, preparing mixed powders, molding, and post-processing. The silicon carbide nanofibers have a length of 5-15 μm and a fiber diameter of 200-300 nm. The boron nitride nanofibers have a length of 5-15 μm and a fiber diameter of 200-300 nm. The steps for preparing the mixed powder are as follows: magnesium oxide, aluminum oxide and silicon oxide powder are mixed evenly, mixed fibers are added, and after stirring evenly, ball milling is performed for 6-8 hours, the ball-to-material ratio is 5-10:1, the ball milling speed is 200-300 rpm, and after ball milling, the powder is dried to obtain the mixed powder. The post-processing step involves placing the cordierite ceramic substrate containing the reinforcing phase into the deposition chamber of a magnetron sputtering device, applying a metallized thermally conductive layer to a copper or aluminum target, and controlling the vacuum level of the deposition chamber to be 2-4 × 10⁻⁴. -4 The deposition atmosphere was argon, with an argon flow rate of 20-30 sccm and a pressure of 0.5-1.0 Pa. The sputtering power was 100-200 W, the sputtering time was 30-60 min, and the thickness of the metallized thermally conductive layer was controlled to be 1-3 μm to obtain cordierite ceramics.

2. The method for preparing a high-strength, high-toughness, thermally conductive cordierite ceramic according to claim 1, characterized in that, The steps for preparing silicon carbide nanofibers are as follows: dissolve polycarbosilane in DMF solvent, add polyvinylpyrrolidone, stir at room temperature for 10-12 h to obtain a spinning precursor solution, spin the spinning precursor solution by electrospinning, control the voltage at 15-20 kV, the pushing speed of the spinning precursor solution at 0.5-0.8 mL / s, the distance from the needle tip to the collector at 12-15 cm, the spinning temperature at 20-25 ℃, after spinning, dry at 50-80 ℃ for 8-12 h, and then heat to 800-1200 ℃ at a rate of 2-3 ℃ / min, and hold for 2-3 h to obtain silicon carbide nanofibers; The mass ratio of polycarbosilane, DMF, and polyvinylpyrrolidone is 5-10:78-87:8-12.

3. The method for preparing a high-strength, high-toughness, thermally conductive cordierite ceramic according to claim 1, characterized in that, The steps for preparing boron nitride nanofibers are as follows: dissolve polyborane in DMF solvent, add polyvinylpyrrolidone, stir at room temperature for 10-12 h to obtain a spinning precursor solution, spin the spinning precursor solution by electrospinning, control the voltage at 15-20 kV, the pushing speed of the spinning precursor solution at 0.5-0.8 mL / s, the distance from the needle tip to the collector at 12-15 cm, and the spinning temperature at 20-25 ℃. After spinning, dry at 50-80 ℃ for 8-12 h, and then heat to 800-1200 ℃ at a rate of 2-3 ℃ / min, and hold for 2-3 h to obtain boron nitride nanofibers. The mass ratio of the polyborazine, DMF, and polyvinylpyrrolidone is 5-10:78-87:8-12.

4. The method for preparing a high-strength, high-toughness, thermally conductive cordierite ceramic according to claim 1, characterized in that, In the step of preparing the mixed powder, the mass ratio of magnesium oxide powder, aluminum oxide powder, and silicon oxide powder is 12-15:33-37:48-55.

5. The method for preparing a high-strength, high-toughness, thermally conductive cordierite ceramic according to claim 1, characterized in that, In the step of preparing the mixed powder, the amount of mixed fiber is 10-20 wt% of the mixed powder. The mixed fibers are silicon carbide nanofibers and boron nitride nanofibers, with a mass ratio of silicon carbide nanofibers to boron nitride nanofibers of 1:

1.

6. The method for preparing a high-strength, high-toughness, thermally conductive cordierite ceramic according to claim 1, characterized in that, The molding step is as follows: the mixed powder is loaded into a mold and cold isostatically pressed at a pressure of 200-300 MPa to obtain a molded green body. The molded green body is then placed in a high-temperature sintering furnace for sintering. The temperature is increased to 1200-1400℃ at a rate of 3-5℃ / min and held for 2-4 hours. After natural cooling to room temperature, a cordierite ceramic matrix containing the reinforcing phase is obtained.

7. A high-strength, high-toughness, thermally conductive cordierite ceramic, characterized in that, It is prepared by any one of the preparation methods described in 1-6 above.

Images