High thermal conductive ceramic spring and preparation method thereof

Abstract

This invention provides a high thermal conductivity ceramic spring and its preparation method, relating to the field of ceramic springs. The preparation method of the high thermal conductivity ceramic spring includes the following steps: preparing a molding slurry, injection molding, hot isostatic pressing sintering, and annealing. The high thermal conductivity ceramic spring and its preparation method of this invention can effectively improve the thermal conductivity of the high thermal conductivity ceramic spring while increasing its density and fracture toughness, thereby improving its compression performance and resilience; and avoids the adverse effects caused by adding large amounts of organic binders during the ceramic spring preparation process. This invention also provides a high thermal conductivity ceramic spring prepared using the aforementioned method.

Description

Technical Field

[0001] This invention relates to the field of ceramic springs, and in particular to a high thermal conductivity ceramic spring and its preparation method. Background Technology

[0002] Springs, as commonly used mechanical parts, are widely used in various mechanical equipment and sealing devices for purposes such as damping vibrations and shocks, storing energy, controlling motion, and measuring force. Currently, metal springs have excellent thermal conductivity but are not heat-resistant, and are prone to failure under prolonged high-temperature conditions. Ordinary ceramic springs possess high-temperature resistance, effectively avoiding failure in harsh working environments, but their poor thermal conductivity fails to meet the urgent heat dissipation requirements in semiconductor manufacturing, power electronic devices, and nuclear reactor components. Therefore, there is an urgent need to develop ceramic spring products with high thermal conductivity to meet the application requirements of third-generation semiconductors and nuclear energy technologies.

[0003] Meanwhile, existing ceramic springs suffer from defects such as poor density and fracture toughness, directly affecting the improvement of compression and rebound performance and significantly limiting the further expansion of their application range. Furthermore, the existing ceramic spring manufacturing process also suffers from the problem of excessive organic binder addition, which not only affects the mechanical properties of the ceramic spring but also its thermal conductivity, with heat accumulation limiting the improvement of its temperature resistance.

[0004] Based on this, a method for preparing a high thermal conductivity ceramic spring is provided, which can effectively improve the thermal conductivity of the high thermal conductivity ceramic spring, while increasing the density and fracture toughness of the ceramic spring, thereby improving the compression performance and rebound performance of the ceramic spring; and avoid the adverse effects caused by adding a large amount of organic binder during the preparation of the ceramic spring, which has important technical significance and research value. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a method for preparing a high thermal conductivity ceramic spring. This method effectively improves the thermal conductivity of the high thermal conductivity ceramic spring while simultaneously increasing its density and fracture toughness, thereby enhancing its compression and rebound properties. It also avoids the adverse effects caused by the excessive addition of organic binders during the preparation process. This invention also provides a high thermal conductivity ceramic spring prepared using the aforementioned method.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high thermal conductivity ceramic spring includes the following steps: preparing a molding slurry, injection molding, hot isostatic pressing sintering, and annealing.

[0008] The method for preparing the molding slurry is to mix silicon nitride powder, silicon carbide whiskers, diamond micro powder coated with silica sol, and polysiloxane, and then knead them to obtain the molding slurry.

[0009] The injection molding method involves injecting molding slurry into a spring mold, then heating and solidifying it in a vacuum environment, and finally demolding to obtain a ceramic spring blank.

[0010] The hot isostatic pressing sintering method involves hot isostatic pressing a ceramic spring blank in an inert gas environment to obtain a sintered ceramic spring body.

[0011] The annealing process involves adjusting the annealing temperature to 1400-1460℃ without cooling after hot isostatic pressing sintering, and then holding the annealing temperature to obtain a high thermal conductivity ceramic spring.

[0012] Preferably, in the preparation of the molding slurry, the mass ratio of silicon nitride powder, silicon carbide whiskers, silica sol-coated diamond micro powder, and polysiloxane is 80-90:20-30:10-30:30-50.

[0013] The α-phase content of silicon nitride powder is >96 wt%;

[0014] The diameter of silicon carbide whiskers is 500-600 nm and the length is 10-15 μm.

[0015] Preferably, in the preparation of the molding slurry, the mixing temperature is 10-15℃, the mixing speed is 30-50 r / min, and the mixing time is 2-5 h.

[0016] Furthermore, in the preparation of the molding slurry, the method for preparing the silica sol-coated diamond micro powder is as follows: diamond micro powder is added to silica sol and mixed evenly, then vacuumed to a vacuum degree of 0.085-0.095 MPa at room temperature, and the vacuum is maintained for 10-15 hours. After separation, the solid is dried to obtain silica sol-coated diamond micro powder.

[0017] Preferably, in the preparation of the silica sol-coated diamond micro powder, the particle size of the diamond micro powder is 4-5 μm;

[0018] The solid content of silica sol is 15-25 wt%.

[0019] The weight ratio of diamond micron powder to silica sol is 3.5-4:10.

[0020] Preferably, in the injection molding process, the injection pressure is 30-50 MPa and the injection flow rate is 100-400 mL / min;

[0021] The heating rate for curing is 2-10℃ / min, the curing temperature is 800-900℃, and the curing holding time is 1-2h.

[0022] Furthermore, the hot isostatic pressing sintering method involves placing the ceramic spring blank in a hot isostatic pressing furnace, controlling the hot isostatic pressing sintering pressure to be 150-200 MPa, heating to 1700-1900℃ at a heating rate of 1-5℃ / min, and holding the temperature for sintering for 2-2.5 hours to obtain the ceramic spring sintered body.

[0023] Preferably, during the annealing process, the temperature change rate is 10-20℃ / min during the adjustment of the annealing temperature to 1400-1460℃.

[0024] Preferably, in the annealing process, the annealing pressure is controlled to be 50-100 MPa;

[0025] The holding and annealing time at 1400-1460℃ is 3-5 hours.

[0026] A high thermal conductivity ceramic spring prepared by the aforementioned method has a thermal conductivity of 150-158 W / (m·K) and a fracture toughness of 13.1-13.7 MPa·m. 1 / 2 .

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The method for preparing the high thermal conductivity ceramic spring of the present invention, on the one hand, uses silicon nitride powder, silicon carbide whiskers, diamond micro powder coated with silica sol, and polysiloxane to prepare the high thermal conductivity ceramic spring. By leveraging the intrinsic advantages of high thermal conductivity of diamond and silicon carbide whiskers, and the high fracture toughness of silicon nitride ceramics, and simultaneously using silica sol to coat the diamond micro powder to avoid high-temperature graphitization of the diamond micro powder during subsequent sintering, the intrinsic thermal conductivity of the ceramic spring is improved by all means. On the other hand, polysiloxane is used as a binder for molding, reducing the addition of organic binders and improving the density of the material; and polysiloxane can also be converted into silicon carbide after high-temperature sintering, further improving the thermal conductivity of the ceramic spring. Finally, after hot isostatic pressing sintering, annealing is performed, which can effectively realize the growth of grains and further optimize the thermal conductivity of the ceramic spring.

[0029] (2) The high thermal conductivity ceramic spring of the present invention has a thermal conductivity of 150-158 W / (m·K) and a fracture toughness of 13.1-13.7 MPa·m. 1 / 2 The density is >98.1%, the maximum compression rate of the spring is 25.0-25.5%, the spring rebound rate is 98.2-98.4%, and the maximum long-term operating temperature is 1500℃.

[0030] (3) The preparation method of the high thermal conductivity ceramic spring of the present invention has easy-to-obtain raw materials, simple process flow, easy-to-control preparation process, and is conducive to large-scale industrial production. Detailed Implementation

[0031] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] This invention provides a method for preparing a high thermal conductivity ceramic spring, comprising the following steps: preparing a molding slurry, injection molding, hot isostatic pressing sintering, and annealing.

[0034] The method for preparing the molding slurry is as follows: silicon nitride powder, silicon carbide whiskers, diamond micro powder coated with silica sol, and polysiloxane are mixed, and the mixing mass ratio is controlled at 80-90:20-30:10-30:30-50; then the mixing temperature is controlled at 10-15℃, the mixing speed is controlled at 30-50 r / min, and the mixing is carried out for 2-5 hours to obtain the molding slurry.

[0035] In the prepared molding slurry, the α-phase content of silicon nitride powder is >96wt%.

[0036] In the preparation of the molding slurry, the silicon carbide whiskers have a diameter of 500-600 nm and a length of 10-15 μm.

[0037] The silica sol-coated diamond micropowder in the preparation of the molding slurry is prepared by the following method: diamond micropowder with a particle size of 4-5 μm is added to silica sol with a solid content of 15-25 wt%, and the weight ratio of diamond micropowder to silica sol is controlled to be 3.5-4:10; after mixing evenly, the mixture is evacuated to a vacuum degree of 0.085-0.095 MPa at room temperature and kept under vacuum for 10-15 h. The solid is then separated and dried at 115-125℃ for 3-5 h to obtain silica sol-coated diamond micropowder.

[0038] The injection molding method is as follows: control the injection pressure to be 30-50MPa and the injection flow rate to be 100-400mL / min, inject the molding slurry into a split spiral mold made of boron nitride, hold the pressure for 15-30min, place the mold containing the molding slurry in a tube furnace, evacuate to a vacuum degree of 0.09-0.099MPa, heat to 800-900℃ at a heating rate of 2-10℃ / min, hold for heat preservation and curing for 1-2h, cool and remove the mold to obtain a ceramic spring blank.

[0039] The hot isostatic pressing (HIP) sintering method involves placing the ceramic spring blank in a hot isostatic pressing furnace, completely replacing the air in the furnace with an inert gas (nitrogen or argon), controlling the inert gas pressure (i.e., the HIP sintering pressure) at 150-200 MPa, and maintaining the pressure. Then, the temperature is increased to 1700-1900℃ at a heating rate of 1-5℃ / min, and sintered at that temperature for 2-2.5 hours to obtain the sintered ceramic spring body.

[0040] The annealing process is as follows: after hot isostatic pressing sintering, no cooling is performed. The inert gas pressure (i.e., annealing pressure) in the hot isostatic pressing furnace is adjusted to 50-100 MPa and maintained. Then, the temperature is lowered to 1400-1460℃ at a cooling rate of 10-20℃ / min. After holding the temperature for annealing for 3-5 hours, the temperature is cooled to obtain a high thermal conductivity ceramic spring.

[0041] In the preparation method of the high thermal conductivity ceramic spring of the present invention, on the one hand, silicon nitride powder, silicon carbide whiskers, diamond micropowder coated with silica sol, and polysilicon carbide are used to prepare the high thermal conductivity ceramic spring. This leverages the intrinsic advantages of high thermal conductivity of diamond and silicon carbide whiskers, and the high fracture toughness of silicon nitride ceramics. Simultaneously, silica sol is used to coat the diamond micropowder to prevent high-temperature graphitization of the diamond micropowder during subsequent sintering. These methods synergistically improve the intrinsic thermal conductivity of the ceramic spring. On the other hand, polysilicon carbide is used as a molding binder, reducing the addition of organic binders and increasing the material density. Furthermore, polysilicon carbide can be converted into silicon carbide after high-temperature sintering, further improving the thermal conductivity of the ceramic spring. Finally, annealing after hot isostatic pressing effectively promotes grain growth, further optimizing the thermal conductivity of the ceramic spring.

[0042] This invention also provides a high thermal conductivity ceramic spring, prepared using the above-described method; the high thermal conductivity ceramic spring has a thermal conductivity of 150-158 W / (m·K) and a fracture toughness of 13.1-13.9 MPa·m. 1 / 2 .

[0043] The present invention will be further described below with reference to some specific embodiments.

[0044] Example 1

[0045] This embodiment provides a method for preparing a high thermal conductivity ceramic spring, specifically as follows:

[0046] (1) Preparation of molding slurry

[0047] Silicon nitride powder, silicon carbide whiskers, silica sol-coated diamond micro powder, and polysiloxane were mixed, with the mixing mass ratio controlled at 80:20:10:30. Then, the mixing temperature was controlled at 10℃ and the mixing speed at 50r / min, and the mixing was carried out for 5 hours to obtain the molding slurry.

[0048] The α-phase content of the silicon nitride powder is 96.3 wt%.

[0049] The silicon carbide whiskers have a diameter of 500 nm and a length of 12 μm.

[0050] Diamond micropowder coated with silica sol was prepared by the following method: diamond micropowder with a particle size of 4 μm was added to silica sol with a solid content of 20 wt%, and the weight ratio of diamond micropowder to silica sol was controlled at 3.5:10. After mixing evenly, the mixture was evacuated to a vacuum degree of 0.085 MPa at room temperature and kept under vacuum for 10 h. The solid was then separated and dried at 115 °C for 3 h to obtain the diamond micropowder coated with silica sol.

[0051] (2) Injection molding

[0052] The grouting pressure was controlled at 30 MPa and the grouting flow rate was 100 mL / min. The grout was injected into a split spiral mold made of boron nitride and held under pressure for 30 min. The mold containing the grout was then placed in a tube furnace and evacuated to a vacuum degree of 0.09 MPa. The temperature was increased to 800°C at a heating rate of 2°C / min. After holding the temperature and curing for 2 h, the mold was removed after cooling to obtain the ceramic spring blank.

[0053] (3) Hot isostatic pressing sintering

[0054] The ceramic spring blank is placed in a hot isostatic pressing furnace, and the air in the furnace is completely replaced with an inert gas (nitrogen or argon). The inert gas pressure (i.e., the hot isostatic pressing sintering pressure) is controlled at 150 MPa and maintained. Then, the temperature is raised to 1700℃ at a heating rate of 3.5℃ / min and held for sintering for 2.5 hours to obtain the sintered ceramic spring body.

[0055] (4) Annealing treatment

[0056] After hot isostatic pressing sintering, without cooling, the inert gas pressure (i.e. annealing pressure) in the hot isostatic pressing furnace is adjusted to 50 MPa and maintained; then, the temperature is lowered to 1400℃ at a cooling rate of 10℃ / min, held for annealing for 3 hours, and then cooled to obtain a high thermal conductivity ceramic spring.

[0057] This embodiment also provides a high thermal conductivity ceramic spring prepared using the aforementioned method. Testing showed that the high thermal conductivity ceramic spring of this embodiment has a thermal conductivity of 150 W / (m·K) and a fracture toughness of 13.1 MPa·m. 1 / 2 The density is 98.1%, the maximum compression ratio (the percentage of the compressed length to its original free length) is 25.0%, the spring rebound rate (the percentage of the spring fully recovered after being fully compressed and held for 30 minutes to its original free length) is 98.2%, and the maximum long-term operating temperature is 1500℃.

[0058] Example 2

[0059] This embodiment provides a method for preparing a high thermal conductivity ceramic spring, specifically as follows:

[0060] (1) Preparation of molding slurry

[0061] Silicon nitride powder, silicon carbide whiskers, silica sol-coated diamond micro powder, and polysiloxane were mixed, with the mixing mass ratio controlled at 86:25:17:42. Then, the mixing temperature was controlled at 13℃ and the mixing speed at 40r / min, and the mixing was carried out for 4 hours to obtain the molding slurry.

[0062] The α-phase content of the silicon nitride powder is 96.3 wt%.

[0063] The silicon carbide whiskers have a diameter of 500 nm and a length of 12 μm.

[0064] Diamond micropowder coated with silica sol was prepared by the following method: diamond micropowder with a particle size of 4 μm was added to silica sol with a solid content of 20 wt%, and the weight ratio of diamond micropowder to silica sol was controlled at 3.9:10. After mixing evenly, the mixture was evacuated to a vacuum degree of 0.09 MPa at room temperature and kept under vacuum for 13 h. The solid was then separated and dried at 120 °C for 4.5 h to obtain diamond micropowder coated with silica sol.

[0065] (2) Injection molding

[0066] The grouting pressure was controlled at 45 MPa and the grouting flow rate was 300 mL / min. The grout was injected into a split spiral mold made of boron nitride and held under pressure for 25 min. The mold containing the grout was then placed in a tube furnace and evacuated to a vacuum degree of 0.095 MPa. The temperature was increased to 880°C at a heating rate of 5°C / min. After holding the temperature and curing for 2 h, the mold was removed after cooling to obtain the ceramic spring blank.

[0067] (3) Hot isostatic pressing sintering

[0068] The ceramic spring blank is placed in a hot isostatic pressing furnace, and the air in the furnace is completely replaced with an inert gas (nitrogen or argon). The inert gas pressure (i.e., the hot isostatic pressing sintering pressure) is controlled at 185 MPa and maintained. Then, the temperature is raised to 1850℃ at a heating rate of 4℃ / min and held for sintering for 2 hours to obtain the sintered ceramic spring body.

[0069] (4) Annealing treatment

[0070] After hot isostatic pressing sintering, without cooling, the inert gas pressure (i.e. annealing pressure) in the hot isostatic pressing furnace is adjusted to 80 MPa and maintained; then, the temperature is lowered to 1420℃ at a cooling rate of 10℃ / min, held for annealing for 4 hours, and then cooled to obtain a high thermal conductivity ceramic spring.

[0071] This embodiment also provides a high thermal conductivity ceramic spring prepared using the aforementioned method. Testing showed that the thermal conductivity of the high thermal conductivity ceramic spring in this embodiment is 158 W / (m·K), and its fracture toughness is 13.7 MPa·m. 1 / 2 The density is 98.6%, the maximum compression ratio of the spring (the percentage of the compressed length to its original free length) is 25.5%, the spring rebound rate (the percentage of the length fully recovered after the spring is fully compressed and held for 30 minutes to its original free length) is 98.4%, and the maximum long-term operating temperature is 1500℃.

[0072] Example 3

[0073] This embodiment provides a method for preparing a high thermal conductivity ceramic spring, specifically as follows:

[0074] (1) Preparation of molding slurry

[0075] Silicon nitride powder, silicon carbide whiskers, silica sol-coated diamond micro powder, and polysiloxane were mixed, with the mixing mass ratio controlled at 90:30:30:50. Then, the mixing temperature was controlled at 15℃ and the mixing speed at 50r / min, and the mixing was carried out for 3 hours to obtain the molding slurry.

[0076] The α-phase content of the silicon nitride powder is 96.3 wt%.

[0077] The silicon carbide whiskers have a diameter of 500 nm and a length of 12 μm.

[0078] Diamond micropowder coated with silica sol was prepared by the following method: diamond micropowder with a particle size of 4 μm was added to silica sol with a solid content of 20 wt%, and the weight ratio of diamond micropowder to silica sol was controlled at 4:10. After mixing evenly, the mixture was evacuated to a vacuum degree of 0.095 MPa at room temperature and kept under vacuum for 15 h. The solid was then separated and dried at 125 °C for 3.5 h to obtain diamond micropowder coated with silica sol.

[0079] (2) Injection molding

[0080] The grouting pressure was controlled at 50 MPa and the grouting flow rate was 400 mL / min. The grout was injected into a split spiral mold made of boron nitride and held under pressure for 20 min. The mold containing the grout was then placed in a tube furnace and evacuated to a vacuum degree of 0.095 MPa. The temperature was increased to 900°C at a heating rate of 6°C / min and held to cure for 1.5 h. After cooling, the mold was removed to obtain the ceramic spring blank.

[0081] (3) Hot isostatic pressing sintering

[0082] The ceramic spring blank is placed in a hot isostatic pressing furnace, and the air in the furnace is completely replaced with an inert gas (nitrogen or argon). The inert gas pressure (i.e., the hot isostatic pressing sintering pressure) is controlled at 200 MPa and maintained. Then, the temperature is raised to 1900℃ at a heating rate of 5℃ / min and held for sintering for 2 hours to obtain the sintered ceramic spring body.

[0083] (4) Annealing treatment

[0084] After hot isostatic pressing sintering, without cooling, the inert gas pressure (i.e. annealing pressure) in the hot isostatic pressing furnace is adjusted to 100 MPa and maintained; then, the temperature is lowered to 1460℃ at a cooling rate of 12℃ / min, held for annealing for 4 hours, and then cooled to obtain a high thermal conductivity ceramic spring.

[0085] This embodiment also provides a high thermal conductivity ceramic spring prepared using the aforementioned method. Testing showed that the thermal conductivity of the high thermal conductivity ceramic spring in this embodiment is 155 W / (m·K), and its fracture toughness is 13.6 MPa·m. 1 / 2 The density is 98.4%, the maximum compression ratio of the spring (the percentage of the compressed length to its original free length) is 25.2%, the spring rebound rate (the percentage of the spring's fully recovered length after being fully compressed and held for 30 minutes) is 98.2%, and the maximum long-term operating temperature is 1500℃.

[0086] Comparative Example 1

[0087] For clear comparison, Comparative Example 1 adopts the technical solution of Example 2, the difference being that: in the step of preparing the molding slurry, the diamond micro powder coated with silica sol is omitted, and the same weight parts of diamond micro powder are used to make up the weight parts of the original silica sol coated diamond micro powder.

[0088] The ceramic spring prepared in Comparative Example 1 was tested and found to have a thermal conductivity of 73 W / (m·K) and a fracture toughness of 12.0 MPa·m. 1 / 2 The density is 94.1%, the maximum compression ratio (the percentage of the compressed length to its original free length) is 20.2%, the spring rebound rate (the percentage of the spring fully recovered after being fully compressed and held for 30 minutes to its original free length) is 90.9%, and the maximum long-term operating temperature is 1400℃.

[0089] Comparative Example 2

[0090] For clear comparison, Comparative Example 2 adopts the technical solution of Example 2, the difference being that the annealing process is omitted.

[0091] The ceramic spring prepared in Comparative Example 2 was tested and found to have a thermal conductivity of 101 W / (m·K) and a fracture toughness of 7.2 MPa·m. 1 / 2 The density is 98.5%, the maximum compression ratio (the percentage of the compressed length to its original free length) is 21.7%, the spring rebound rate (the percentage of the spring fully recovered after being fully compressed and held for 30 minutes to its original free length) is 92.5%, and the maximum long-term operating temperature is 1400℃.

[0092] As can be seen, in the preparation of the high thermal conductivity ceramic springs in Examples 1-3, on the one hand, silicon nitride powder, silicon carbide whiskers, diamond micropowder coated with silica sol, and polysilicon carbide are used to prepare the high thermal conductivity ceramic springs. This leverages the intrinsic advantages of high thermal conductivity of diamond and silicon carbide whiskers, as well as the high fracture toughness of silicon nitride ceramics. Simultaneously, silica sol is used to coat the diamond micropowder to prevent high-temperature graphitization of the diamond micropowder during subsequent sintering. These methods synergistically improve the intrinsic thermal conductivity of the ceramic spring. On the other hand, polysilicon carbide is used as a binder for molding, reducing the addition of organic binders and increasing the material density. Furthermore, polysilicon carbide can be converted into silicon carbide after high-temperature sintering, further improving the thermal conductivity of the ceramic spring. Finally, annealing after hot isostatic pressing effectively promotes grain growth, further optimizing the thermal conductivity of the ceramic spring.

[0093] In Comparative Example 1, after replacing the original silica sol-coated diamond powder with conventional diamond micro powder, the high-temperature graphitization of the diamond micro powder during the subsequent sintering process could not be avoided. This directly led to a significant reduction in the thermal conductivity of the resulting ceramic spring, and also caused a significant deterioration in the density, maximum compression ratio, and resilience of the ceramic spring.

[0094] In Comparative Example 2, omitting the annealing process prevented further promotion of grain growth, resulting in a certain degree of reduction in the thermal conductivity of the ceramic spring. Simultaneously, the residual internal stress within the ceramic spring would cause stress accumulation at internal defects or grain boundaries when the spring was compressed, leading to a significant reduction in fracture toughness. Furthermore, it also caused a significant deterioration in the density, maximum compressibility, and resilience of the ceramic spring.

[0095] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0096] 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 thermal conductivity ceramic spring, characterized in that, Includes the following steps: Preparation of molding slurry, injection molding, hot isostatic pressing sintering, and annealing; The method for preparing the molding slurry is to mix silicon nitride powder, silicon carbide whiskers, diamond micro powder coated with silica sol, and polysiloxane, and then knead them to obtain the molding slurry. The mass ratio of silicon nitride powder, silicon carbide whiskers, silica sol-coated diamond micro powder, and polysiloxane is 80-90:20-30:10-30:30-50. The method for preparing the silica sol-coated diamond micro powder is as follows: diamond micro powder is added to silica sol and mixed evenly. Then, vacuum is applied at room temperature to a vacuum degree of 0.085-0.095 MPa. After maintaining the vacuum for 10-15 hours, the solid is separated and dried to obtain silica sol-coated diamond micro powder. The injection molding method involves injecting molding slurry into a spring mold, then heating and solidifying it in a vacuum environment, and finally demolding to obtain a ceramic spring blank. In the injection molding process, the curing temperature is 800-900℃, and the curing holding time is 1-2 hours. The hot isostatic pressing sintering method involves hot isostatic pressing a ceramic spring blank in an inert gas environment to obtain a sintered ceramic spring body. The hot isostatic pressing sintering temperature is 1700-1900℃, and the holding sintering time is 2-2.5h; The annealing process involves adjusting the annealing temperature to 1400-1460℃ without cooling after hot isostatic pressing sintering, and then holding the annealing temperature to obtain a high thermal conductivity ceramic spring.

2. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, In the prepared molding slurry, the α-phase content of silicon nitride powder is >96 wt%; The diameter of silicon carbide whiskers is 500-600 nm and the length is 10-15 μm.

3. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, In the preparation of the molding slurry, the mixing temperature is 10-15℃, the mixing speed is 30-50 r / min, and the mixing time is 2-5 h.

4. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, In the preparation of the silica sol-coated diamond micro powder, the particle size of the diamond micro powder is 4-5 μm; The solid content of silica sol is 15-25 wt%. The weight ratio of diamond micron powder to silica sol is 3.5-4:

10.

5. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, In the injection molding process, the injection pressure is 30-50MPa and the injection flow rate is 100-400mL / min; The heating rate for curing is 2-10℃ / min.

6. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, In the hot isostatic pressing sintering process, the ceramic spring blank is placed in a hot isostatic pressing furnace, and the hot isostatic pressing sintering pressure is controlled at 150-200MPa, and the heating rate is 1-5℃ / min.

7. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, During the annealing process, the temperature change rate is 10-20℃ / min when adjusting the annealing temperature to 1400-1460℃.

8. The method for preparing a high thermal conductivity ceramic spring according to claim 1, characterized in that, In the annealing process, the annealing pressure is controlled at 50-100 MPa; the holding annealing time at 1400-1460℃ is 3-5 hours.

9. A high thermal conductivity ceramic spring prepared by the preparation method according to any one of claims 1-8, characterized in that, The high thermal conductivity ceramic spring has a thermal conductivity of 150-158 W / (m·K) and a fracture toughness of 13.1-13.7 MPa·m. 1 / 2 .