Ceramic composite material spring and preparation method thereof

Abstract

The present invention belongs to the technical field of high-temperature resistant springs, and discloses a ceramic composite material spring and a preparation method thereof. The preparation method is as follows: using chemical vapor deposition to deposit silicon carbide on the surface of a spring mold to obtain a stabilized spring mold; after weaving a plurality of strands of silicon carbide fibers into a fiber braid, the fiber braid is embedded in the stabilized spring mold to obtain a spring braid; using chemical vapor deposition to sequentially deposit an interface phase layer and a ceramic matrix layer inside and on the surface of the spring braid, a rare earth co-infiltration layer is further coated by embedding infiltration; after preparing a surface reinforcement layer, the surface is polished to obtain a ceramic composite material spring. The preparation process of the present invention has low operating difficulty, realizes the organic combination of various material components in the spring, improves the bonding strength between the fiber and each layer, and makes the ceramic composite material spring of the present invention have good stability in a neutron irradiation environment and can withstand an inert or aerobic environment of 1350°C for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature resistant springs, and in particular to a ceramic composite material spring and a preparation method thereof. Background Art

[0002] Nuclear reactor control technology is a key technology for ensuring the safe and stable operation of nuclear reactors and is a research priority and hotspot in various countries. Control rods are the core components that control the start and shutdown of the reactor. As the control rods move axially along the core, a spring array is required to cushion their motion and prevent hard collisions between structural components, which could damage the core. For example, in a typical helium-xenon reactor, the core structure is exposed to high temperatures ranging from 700°C to 1300°C during operation. This places high demands and challenges on the springs' neutron radiation resistance, high temperature resistance, long-term performance stability, and resilience.

[0003] Existing heat-resistant stainless steels X35CrMo17 and X30WCrV53 can withstand temperatures up to 400°C, while high-temperature alloys InconelX750 and InconelX718 can withstand temperatures up to 600°C, and high-temperature alloy Nimonic90 can withstand temperatures up to 700°C. However, when operating at temperatures exceeding 900°C, the strength of these high-temperature alloys significantly decreases, causing springs made from them to have reduced performance or even lose their resilience, thus limiting their application in nuclear reactors.

[0004] In order to solve the above technical problems, those skilled in the art have proposed to improve the performance of spring materials by introducing carbon fiber reinforcements. In the prior art, when introducing carbon fiber reinforcements, the materials are prepared by using a precursor conversion process and a carbon fiber braiding method. Among them, the precursor conversion process first uses an investment molding process to prepare a spring preform, densifies it by a precursor conversion process, and deposits a SiC anti-oxidation coating by a CVD process to prepare a unidirectional carbon fiber reinforced silicon carbide. Although this preparation method can achieve the performance of a carbon fiber reinforced silicon carbide ceramic matrix composite spring to a certain extent, the preparation method is complex and difficult to operate. In addition, the spring prepared is prone to degradation and damage in the neutron irradiation environment of a nuclear reactor or other aerobic environment, resulting in a spring service life that does not meet the requirements of engineering use. The above-mentioned carbon fiber braiding method refers to braiding multiple strands of carbon fiber into a carbon fiber rope, and then depositing silicon carbide material on the surface of the formed carbon fiber rope by a vapor deposition method to achieve a composite of carbon fiber and silicon carbide. However, the spring formed by this method is prone to fiber unraveling and matrix shedding under large deformation conditions, and also has the problem of insufficient neutron irradiation resistance and oxidation resistance. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a ceramic composite material spring and a preparation method thereof.

[0006] The ceramic composite material spring and its preparation method of the present invention are achieved through the following technical solutions:

[0007] The present invention provides a method for preparing a ceramic composite material spring, comprising the following steps:

[0008] Step 1, select the mold:

[0009] Select the corresponding spring mold according to the required spring structure.

[0010] It should be noted that in order to ensure that the spring mold used in the present invention can achieve the actual required spring structure, the present invention preferably obtains a mold model with a corresponding structure through three-dimensional software design based on the geometric parameters of the required spring, and then obtains the corresponding spring mold through mechanical processing.

[0011] In some preferred embodiments of the present invention, graphite is used as the raw material and mechanically processed to produce a graphite spring mold. The graphite material maintains excellent physical and chemical stability during subsequent high-temperature processing steps and exhibits good physical and chemical compatibility with the materials used to make the spring body, ensuring precise composition and geometric dimensions of the spring material.

[0012] Step 2: Stabilization of the spring mold:

[0013] In an atmosphere containing a silicon carbide source, a silicon carbide ceramic layer is deposited on the surface of the spring mold by using a chemical vapor deposition method to obtain a stabilized spring mold.

[0014] It should be noted that, before embedding the spring preparation raw materials, the present invention first uses chemical vapor deposition technology to stabilize the spring mold, so as to remove impurities in the spring mold through stabilization treatment and improve the quality of the subsequently formed spring finished product.

[0015] Moreover, the present invention performs chemical vapor deposition in an atmosphere containing a silicon carbide source, so that the silicon carbide source can produce silicon carbide during the chemical vapor deposition process. The produced silicon carbide adheres and deposits on the surface of the spring mold to form a silicon carbide ceramic layer in situ on the surface of the spring mold. The formed silicon carbide ceramic layer can not only prevent the components of the spring mold itself from entering the spring finished product, but also help to improve the quality of the subsequently formed spring finished product; moreover, the formed silicon carbide ceramic layer can also improve the physical and chemical compatibility between the spring mold and the fiber braid, so that the fiber braid can adapt to the thermal mismatch between the mold and the braid in all subsequent thermal processes, and can realize self-release of internal stress during the cooling process of the thermal process, thereby reducing the process difficulty and preparation cost.

[0016] In some preferred embodiments of the present invention, when depositing a silicon carbide ceramic layer on the surface of the spring mold, the process conditions of the chemical vapor deposition treatment are:

[0017] Under a pressure of 20 Pa to 150 Pa, the spring mold is heated to 1200° C. to 1300° C. and maintained at this temperature for 4 to 8 hours. An atmosphere containing a silicon carbide source is then introduced and deposited for 4 to 12 hours, allowing the silicon carbide source to be converted into silicon carbide during vapor deposition and deposited on the spring mold, forming a silicon carbide ceramic layer on the surface of the spring mold. The introduction of the silicon carbide source is stopped, and the temperature is maintained for 1 to 2 hours to reduce stress within the workpiece and prevent thermal deformation of the spring mold. The mold is then cooled to room temperature, forming a silicon carbide ceramic layer on the surface of the spring mold, thereby obtaining a stabilized spring mold.

[0018] In some more preferred embodiments of the present invention, trichloromethylsilane is used as the silicon carbide source, that is, the atmosphere containing the silicon carbide source used in the present invention is a mixture of trichloromethylsilane, hydrogen, and argon, wherein hydrogen is a carrier gas and argon is a diluent gas for dilution. This allows the trichloromethylsilane to diffuse uniformly and decompose in situ to form silicon carbide at 1200°C to 1300°C under the synergistic effect of hydrogen and argon, thereby ensuring that a silicon carbide ceramic layer can be formed on the surface of the spring mold. In some more preferred embodiments of the present invention, the flow ratio of trichloromethylsilane, hydrogen, and argon is 1:3 to 5:10 to 12. Within this range, the ability of trichloromethylsilane to penetrate into the spring mold is optimal, the rate of generating silicon carbide ceramics is good, and the microstructure of the generated silicon carbide ceramics is optimal, which can ensure the comprehensive mechanical, physical, and chemical properties of the material.

[0019] Step 3: Preparation of spring braid:

[0020] A plurality of strands of silicon carbide fibers are combined and braided to obtain a fiber braid; the fiber braid is embedded in the stabilized spring mold and fixed to obtain a spring braid.

[0021] The present invention does not specifically limit the number of strands of silicon carbide fibers, and may be selected according to actual needs. For example, in some preferred embodiments of the present invention, the number of strands of silicon carbide fibers is 2 to 6.

[0022] In some preferred embodiments of the present invention, when performing weaving processing, the present invention preferably adopts any one of the weaving methods of three-dimensional four-directional, three-dimensional six-directional and two-dimensional circumferential for weaving processing, and the warp and weft weaving angles during weaving processing are 17°~38°, so that in the spring braid formed by weaving, the fiber bundles in the cross section of the spring braid are hooked with each other, and when the spring is subjected to axial tensile and compressive loads, the fibers in the cross section can constrain each other, effectively improving the torsional stiffness of the spring cross section, thereby macroscopically improving the axial stiffness of the spring, and avoiding microstructural damage, falling off, peeling and other phenomena of the spring under large deformation conditions.

[0023] In some preferred embodiments of the present invention, in order to avoid the spring braid from moving in the stabilized spring mold during subsequent processing, resulting in the formed spring structure being inconsistent with the actual required structure, after the fiber braid is embedded in the stabilized spring mold, graphite bolts or bow clamps are used to fix the two ends of the fiber braid to the two ends of the stabilized spring mold.

[0024] Step 4, deposition of the interfacial phase layer:

[0025] In an atmosphere containing a boron nitride source, a layer of boron nitride is deposited inside and on the surface of the spring braid as an interface phase layer by using a chemical vapor deposition method to obtain a modified spring braid.

[0026] It should be noted that the present invention first uses chemical vapor deposition technology to deposit a layer of boron nitride inside and on the surface of the spring braid, that is, a layer of boron nitride is attached and deposited on the surface of the fiber monofilaments and fiber bundles inside the fiber braid, so that the formed boron nitride layer serves as an interface phase layer, thereby effectively improving the mechanical properties such as toughness and strength of the spring material, coordinating the torsional deformation of the cross-sectional fibers when the spring is stretched or compressed, and being able to effectively withstand neutron irradiation and oxidizing environments, thereby greatly improving the long-term stability of the spring during use.

[0027] In some preferred embodiments of the present invention, during the deposition of the interface phase layer, the temperature is raised to 680°C to 840°C under a pressure of 100 Pa to 3000 Pa and then maintained at this temperature for 4 to 8 hours, equivalent to a furnace heat treatment process to reduce stress within the workpiece and ensure that the workpiece does not undergo thermal deformation. Subsequently, an atmosphere containing a boron nitride source is introduced and deposited for 24 to 36 hours, allowing the boron nitride source to form boron nitride during the vapor deposition process. The formed boron nitride is deposited within and on the surface of the spring braid to form an interface phase layer. By performing the above steps once or twice according to the different performance requirements of the spring, workpieces with different mechanical properties can be obtained, namely, a modified spring braid.

[0028] In some more preferred embodiments of the present invention, ammonia and boron trichloride are used together as boron nitride sources. Specifically, the boron nitride source atmosphere employed in the present invention is a mixed gas composed of argon, hydrogen, ammonia, and boron trichloride. The ammonia and boron trichloride react during the deposition process to produce boron nitride, thereby forming an interfacial phase layer within and on the surface of the spring braid. Furthermore, the flow ratios of argon, hydrogen, ammonia, and boron trichloride are in the range of 1:5-8:10-15:10-15. Within this range, the ammonia and boron trichloride achieve optimal penetration into the workpiece, a faster rate of silicon nitride ceramic formation, and an optimal microstructure, ensuring the material's comprehensive mechanical, physical, and chemical properties.

[0029] Step 5, deposition of ceramic matrix layer:

[0030] The modified spring braid is subjected to chemical vapor deposition treatment in an atmosphere containing a silicon carbide source to deposit a ceramic matrix layer on the surface of the interface phase layer, and then demoulding is performed to obtain a spring blank.

[0031] It should be noted that the present invention further deposits a layer of silicon carbide as a ceramic matrix layer on the surface of the interface phase layer, so that the formed ceramic matrix layer and the boron nitride are bonded through heterogeneous materials to form an interface with moderate bonding strength, which plays a role in transferring load, increasing toughness, improving strength, and alleviating fiber oxidation.

[0032] In some preferred embodiments of the present invention, when depositing the ceramic matrix layer, the temperature is raised to 1000°C to 1200°C under a pressure of 500Pa to 3000Pa and then maintained at this temperature for 1 to 2 hours. An atmosphere containing a silicon carbide source is then introduced and deposited for 52 to 64 hours, allowing the silicon carbide source to form silicon carbide during vapor deposition. The silicon carbide gradually adheres to the surface of the interface phase layer, thereby forming the ceramic matrix layer. The introduction of trichloromethylsilane is then stopped, the temperature is maintained for another 1 to 2 hours, and the temperature is then lowered to room temperature. Depending on the performance requirements of the spring, the above steps are performed 4 to 8 times to achieve uniform formation of silicon carbide ceramics on the surface and interior of the spring, followed by demolding to obtain a spring blank with uniform performance.

[0033] In some more preferred embodiments of the present invention, trichloromethylsilane is used as the silicon carbide source, that is, the atmosphere containing the silicon carbide source used in the present invention is a mixture of trichloromethylsilane, hydrogen, and argon, wherein hydrogen is a carrier gas and argon is a diluent gas for dilution, so that the trichloromethylsilane can be uniformly diffused and decomposed in situ to form silicon carbide at 1000°C to 1200°C under the synergistic effect of hydrogen and argon, thereby ensuring that a layer of silicon carbide can be formed on the surface of the interface phase layer, and the formed silicon carbide layer serves as the ceramic matrix layer. In some more preferred embodiments of the present invention, the flow ratio of trichloromethylsilane, hydrogen, and argon is 1:5-15:15-25. Within this range, the ability of trichloromethylsilane to penetrate into the interface phase layer is optimal, the rate of generating silicon carbide ceramics is good, the microstructure of the generated silicon carbide ceramics is optimal, and the comprehensive mechanical, physical, and chemical properties of the material can be guaranteed.

[0034] Step 6, formation of rare earth co-infiltration layer:

[0035] The spring blank is subjected to embedding infiltration treatment by adopting an embedding infiltration method, so as to form a rare earth co-infiltration layer on the surface of the ceramic matrix layer, thereby obtaining a stabilized spring blank.

[0036] It should be noted that, in the present invention, a rare earth co-infiltration layer is formed on the surface of the ceramic base layer, so that the formed rare earth co-infiltration layer can enhance the bonding strength with the ceramic layer.

[0037] In some preferred embodiments of the present invention, the raw materials for preparing the embedding agent used in the embedding infiltration treatment are composed of the following components, calculated by mass percentage: SiC 10% to 25%, CeO2 1% to 5%, Y2O3 4% to 6%, La2O3 0.5% to 2%, and the balance is Al2O3, totaling 100%.

[0038] In some preferred embodiments of the present invention, the embedding infiltration treatment is performed by the following steps:

[0039] The embedding agent is covered on the surface of the workpiece with a covering thickness of 0.5mm to 3mm to obtain an embedding mixture; the embedding mixture is heated to 1300℃ to 1450℃ under 5Pa to 150Pa, kept warm for 0.5h to 1.5h, and then cooled to room temperature to obtain the stabilized spring blank.

[0040] Step 7: Formation of surface strengthening layer:

[0041] The carbide powder is dispersed in an organic solvent to obtain a coating slurry; the coating slurry is applied to the surface of the stabilized spring blank, and after drying, a chemical vapor deposition method is used to transform the coating slurry into a surface reinforcement layer to obtain a spring semi-finished product.

[0042] It should be noted that the present invention uses a coating slurry whose main component is carbide powder as a surface reinforcement material. After applying the coating slurry to the surface of the stabilized spring blank, the coating slurry is solidified by drying, and then subjected to chemical vapor deposition treatment, so that the carbides in the solidified carbide powder form a surface reinforcement layer whose main component is a carbide layer on the surface of the rare earth co-carburization layer, so that the rare earth co-carburization layer is ceramicized by the formed carbide layer, and the bonding strength with the rare earth co-carburization layer is improved, so that the fatigue resistance and structural integrity of the formed spring product under high temperature conditions are greatly improved, and the rebound retention rate of the spring after being subjected to repeated tensile and compressive loads is significantly improved. At the same time, by preparing a ceramic reinforcement layer on the surface of the spring, the phenomena of slag falling, block falling, etc. that may occur during long-term use are eliminated.

[0043] In some preferred embodiments of the present invention, the carbide powder is one or more of silicon carbide powder, silicon carbide whiskers and zirconium carbide powder.

[0044] In some preferred embodiments of the present invention, the organic solvent is one or more of polycarbosilane, xylene and polypropylene alcohol.

[0045] In some preferred embodiments of the present invention, the usage ratio of the carbide powder to the organic solvent is 1 mg:5 mL to 25 mL, so as to obtain a slurry with moderate viscosity, achieve smooth penetration of the slurry in the subsequent coating process, and enhance the bonding strength between the surface reinforcement layer and the spring body.

[0046] In some preferred embodiments of the present invention, the sizing amount of the coating slurry is 30g / m 2 ~50g / m 2 .

[0047] In some preferred embodiments of the present invention, when preparing the surface strengthening layer, the chemical vapor deposition process conditions are as follows: under a pressure of 500Pa to 3000Pa, the temperature is raised to 1000°C to 1200°C and maintained at this temperature for 1 to 2 hours. An atmosphere containing a silicon carbide source is then introduced and deposited for 52 to 64 hours, allowing the silicon carbide source to form silicon carbide during the vapor deposition process. The silicon carbide gradually adheres to the surface of the rare earth co-carburized layer, thereby forming a ceramic matrix layer. The introduction of trichloromethylsilane is then stopped, the temperature is maintained for another 1 to 2 hours, and then the temperature is lowered to room temperature. Depending on the different performance requirements of the spring, the above steps are performed 4 to 8 times to further uniformly form the surface strengthening layer on the surface and internal rare earth co-carburized layer of the spring, thereby obtaining a spring semi-finished product with uniform performance.

[0048] In some more preferred embodiments of the present invention, trichloromethylsilane is used as the silicon carbide source, that is, the atmosphere containing the silicon carbide source used in the present invention is a mixture of trichloromethylsilane, hydrogen, and argon, wherein hydrogen is used as a carrier gas and argon is used as a diluent gas. This allows the trichloromethylsilane to diffuse uniformly and decompose in situ to form silicon carbide at 1000°C to 1200°C under the synergistic effect of hydrogen and argon, thereby ensuring that a silicon carbide ceramic layer can be formed on the surface of the rare earth co-carburized layer. In some more preferred embodiments of the present invention, the flow ratio of trichloromethylsilane, hydrogen, and argon is 1:5-15:15-25. Within this range, the ability of trichloromethylsilane to penetrate into the rare earth co-carburized layer is optimal, the rate of generating silicon carbide ceramics is good, and the microstructure of the generated silicon carbide ceramics is optimal, which can ensure the comprehensive mechanical, physical, and chemical properties of the material.

[0049] Step 8, polishing:

[0050] The semi-finished spring product is polished to obtain the ceramic composite material spring.

[0051] It should be noted that, in the present invention, the semi-finished spring is further polished to remove defects and impurities on the surface of the semi-finished spring to obtain the ceramic composite material spring.

[0052] In some preferred embodiments of the present invention, during the grinding process, a sandblaster or sandpaper is used for grinding, and the grinding process is performed until the surface is smooth and free of scum and burrs, which is considered to have achieved the removal of defects and impurities on the surface of the spring semi-finished product.

[0053] The present invention also provides a ceramic composite material spring prepared by the above preparation method.

[0054] It should be noted that the ceramic composite material spring prepared by the present invention uses continuous silicon carbide ceramic fiber as the spring matrix, on which are arranged an interface phase layer, a ceramic matrix layer, a rare earth co-infiltration layer and a surface reinforcement layer. The continuous silicon carbide ceramic fiber is obtained by twisting and three-dimensional multi-directional weaving, which can maintain good internal cross-sectional constraints under large deformation and fatigue conditions of the spring, thereby ensuring the rebound characteristics of the spring. The infiltrated rare earth components and silicon carbide ceramics are tightly combined with the fiber braid and the surface ceramic reinforcement layer to prevent the spring from cracking, peeling and other phenomena when used for a long time at high temperature. This makes the ceramic composite material spring prepared by the present invention have good stability in a neutron irradiation environment and can withstand an inert or aerobic environment of 1350°C for a long time.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The present invention first selects a corresponding spring mold according to the structure of the required spring. Then, the spring mold is subjected to chemical vapor deposition treatment to deposit a layer of silicon carbide ceramic layer on the surface of the spring mold. The silicon carbide ceramic layer prevents the components of the spring mold from entering the finished spring product, while improving the physical and chemical compatibility between the spring mold and the fiber braid, reducing the process difficulty and preparation cost. Then, a braiding method is used to weave several strands of silicon carbide fibers into a fiber braid, which is then embedded in the stabilized spring mold so that the fiber bundles in the obtained spring braid are interconnected. When the spring is subjected to axial tension and compression loads, the fibers in the cross section can constrain each other, effectively improving the torsional stiffness of the spring cross section, thereby macroscopically improving the axial stiffness of the spring and avoiding microstructural damage, block falling, peeling, and other phenomena under large deformation conditions. In an atmosphere containing a boron nitride source, the spring braid is subjected to a chemical vapor deposition process to deposit an interface phase layer inside and on the surface of the spring braid. The interface phase layer effectively improves the mechanical properties of the spring material, such as toughness and strength, coordinates the torsional deformation of the cross-sectional fibers when the spring is stretched or compressed, and can effectively withstand neutron irradiation and oxidizing environments, thereby significantly improving the long-term stability of the spring during use. In an atmosphere containing a silicon carbide source, the modified spring braid is then subjected to a chemical vapor deposition process to deposit a ceramic matrix layer on the surface of the interface phase layer. Then, a rare earth co-infiltration layer and a carbide layer are sequentially formed, so that the carbide layer ceramicizes the rare earth co-infiltration layer and improves the bonding strength with the rare earth co-infiltration layer. The fatigue resistance and structural integrity of the finished spring under high temperature conditions are greatly improved, and the spring's rebound retention rate after repeated tensile and compressive loads is significantly improved. At the same time, by preparing a ceramic reinforcement layer on the spring surface, the phenomenon of slag and chunking that may occur during long-term use is eliminated. Finally, defects and impurities on the surface of the semi-finished spring are removed by grinding to obtain the ceramic composite material spring.

[0057] The preparation process of the present invention has low operating difficulty. Through weaving, infiltration, surface deposition and other processes, the organic combination of various material components in the spring is achieved, the bonding strength between the fibers and the layers is improved, and the mechanical properties of the spring are stabilized under high temperature, neutron irradiation environment and oxidizing atmosphere.

[0058] The present invention employs a technical process of first ceramicizing the fiber braid, preparing a rare earth co-infiltration layer, and then ceramicizing it. Because the rare earth co-infiltration layer infiltrated into the braid enhances its bonding strength with the ceramic layer, ceramicization significantly improves the spring's fatigue resistance and structural integrity under high-temperature conditions, significantly increasing the spring's rebound retention rate after repeated tensile and compressive loads. Simultaneously, by preparing a ceramic reinforcement layer on the spring surface, it eliminates the potential for slag and block shedding during prolonged use. The combination of these multiple processes effectively improves the spring's comprehensive performance, including high-temperature resistance, fatigue resistance, and long-term stability, extending its service life and reducing the risk of structural failure.

[0059] The present invention first implements a stabilization treatment process on the mold, and then adopts parameters with special braiding angles to prepare the braid. The organic combination of the two enables the fiber braid to adapt to the thermal mismatch between the mold and the braid in all subsequent thermal processes, and can achieve self-release of internal stress during the cooling process of the thermal process. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a process flow chart of the present invention.

[0061] Figure 2 This is a physical diagram of the spring according to embodiment 1 of the present invention. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0063] Example 1

[0064] This embodiment provides a ceramic composite spring, which is manufactured by the following steps:

[0065] Step 1, select the mold:

[0066] 1.1) In this example, a spring for a control rod buffer structure in a small gas-cooled nuclear reactor was fabricated. Based on the spring's geometric parameters (wire diameter of 3 mm, maximum outer diameter of 25 mm, pitch of 12 mm, and total height of 50 mm), a mold model with a spiral groove of corresponding dimensions was designed using 3D software.

[0067] 1.2) According to the obtained mold model, high-purity graphite is used as raw material, and mechanical processing is adopted to complete the mold processing to obtain a spring mold.

[0068] Step 2: Stabilization of the spring mold:

[0069] 2.1) Place the spring mold obtained in the above steps in a chemical vapor deposition furnace, heat it to 1200°C at a pressure of 20 Pa, and keep it at this temperature for 4 hours.

[0070] 2.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced with a flow ratio of trichloromethylsilane, hydrogen, and argon of 1:3:10, and the deposition was continued for 4 hours.

[0071] 2.3) Continue to maintain the temperature at 1200°C for 2 hours, then cool to room temperature to obtain a stabilized spring mold.

[0072] Step 3: Preparation of spring braid:

[0073] 3.1) After combining 6 strands of silicon carbide fibers, a three-dimensional four-directional braiding method was used with a warp and weft braiding angle of 17° to obtain a fiber braid.

[0074] 3.2) The fiber braid is embedded in situ along the spiral groove of the mold, and the two ends of the spiral braid are fixed to the two ends of the mold using graphite bolts to obtain a spring braid.

[0075] Step 4, deposition of the interfacial phase layer:

[0076] 4.1) Place the mold with the spring braid embedded in it in a chemical vapor infiltration furnace. Raise the temperature to 680°C at a pressure of 100 Pa and keep it at that temperature for 4 h.

[0077] 4.2) A mixed gas of argon, hydrogen, ammonia, and boron trichloride was introduced at a flow ratio of 1:5:10:10, and the deposition was continued for 24 h.

[0078] 4.3) The above 4.1) and 4.2) were regarded as one cycle, and this cycle was performed twice to form an interfacial phase layer with a thickness of 650 nm on the surface and inside of the fiber braid.

[0079] Step 5, deposition of ceramic matrix layer:

[0080] 5.1) Under a pressure of 500 Pa, heat to 1000°C and keep warm for 2 hours.

[0081] 5.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 for 52 h.

[0082] 5.3) Keep the temperature at 1000℃ for 2 h and then cool to room temperature.

[0083] 5.4) Treat 5.1), 5.2) and 5.3) as one loop and execute the loop 8 times.

[0084] 5.5) Remove the fiber braid from the mold to obtain a spring blank.

[0085] Step 6: Formation of rare earth co-infiltration layer:

[0086] 6.1) Weigh the appropriate amounts of SiC, CeO2, Y2O3, La2O3, and Al2O3 and mix them evenly according to the following mass percentages to prepare an embedding medium:

[0087] SiC 25%, CeO 25%, Y2O 34%, La2O 3 0.5%, and the balance is Al2O3.

[0088] 6.2) The embedding agent prepared in 6.1) was used to embed the spring blank prepared above to a thickness of 0.5 mm to obtain an embedding mixture.

[0089] 6.3) The embedding mixture obtained in 6.2) was heated to 1300°C at 150 Pa, maintained at this temperature for 1.5 hours, and then cooled to room temperature to obtain a stabilized spring blank.

[0090] Step 7: Formation of surface strengthening layer:

[0091] 7.1) Silicon carbide whiskers, polycarbosilane, and xylene are mixed in a mass ratio of 4:1:15 to obtain a coating slurry.

[0092] 7.2) The above coating slurry was mixed at 30 g / m 2 The sizing amount is evenly applied on the surface of the stabilized spring blank obtained above, and then placed in a fume hood to dry for 2 hours.

[0093] 7.3) Place the dried product from 7.2) in a chemical vapor deposition apparatus, raise the temperature to 1000°C at a pressure of 500 Pa, and maintain the temperature for 2 h.

[0094] 7.4) A mixture of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 and the deposition was continued for 52 h.

[0095] 7.5) Keep the temperature at 1000℃ for 2 h and then cool to room temperature.

[0096] 7.6) Take 7.3), 7.4) and 7.5) as one cycle, and perform this cycle 8 times to produce a semi-finished spring.

[0097] Step 8, polishing:

[0098] The burrs and attachments on the surface of the semi-finished spring obtained in the above steps are removed by a sandblasting machine to obtain a finished spring, that is, the ceramic composite material spring of this embodiment. Figure 2 shown.

[0099] Example 2

[0100] This embodiment provides a ceramic composite spring, which is manufactured by the following steps:

[0101] Step 1, select the mold:

[0102] 1.1) In this embodiment, in order to prepare a buffer spring for an aerospace engine accessory, a mold model with a spiral groove of corresponding dimensions was designed using 3D software based on the geometric parameters of the spring: wire diameter of 5 mm, maximum outer diameter of 22 mm, pitch of 8 mm, and total height of 33 mm.

[0103] 1.2) According to the obtained mold model, high-purity graphite is used as raw material, and mechanical processing is adopted to complete the mold processing to obtain a spring mold.

[0104] Step 2: Stabilization of the spring mold:

[0105] 2.1) The spring mold obtained in the above steps was placed in a chemical vapor deposition furnace, heated to 1300°C at a pressure of 150 Pa, and then kept at this temperature for 8 hours.

[0106] 2.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:12 for 12 h.

[0107] 2.3) Continue to maintain the temperature at 1300°C for 1 hour, then cool to room temperature to obtain a stabilized spring mold.

[0108] Step 3: Preparation of spring braid:

[0109] 3.1) After combining two strands of silicon carbide fibers, a three-dimensional four-directional braiding method is used with a warp and weft braiding angle of 38° to obtain a fiber braid.

[0110] 3.2) The fiber braid is embedded in situ along the spiral groove of the mold, and graphite bolts are used to fix the two ends of the spiral braid to the two ends of the mold to obtain a spring braid.

[0111] Step 4, deposition of the interfacial phase layer:

[0112] 4.1) Place the mold with the spring braid embedded in it in a chemical vapor infiltration furnace. Raise the temperature to 840°C at a pressure of 3000 Pa and keep it at that temperature for 8 h.

[0113] 4.2) A mixture of argon, hydrogen, ammonia, and boron trichloride was introduced at a flow rate ratio of 1:8:15:15 for 36 hours to form an interfacial phase layer with a thickness of 350 nm on the surface and inside the fiber braid.

[0114] Step 5, deposition of ceramic matrix layer:

[0115] 5.1) Under a pressure of 3000 Pa, heat to 1200°C and keep warm for 1 hour.

[0116] 5.2) A mixture of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:15:25 for 64 h.

[0117] 5.3) Keep the temperature at 1200℃ for 1 hour and then cool to room temperature.

[0118] 5.4) Treat 5.1), 5.2) and 5.3) as one loop and execute the loop four times.

[0119] 5.5) Remove the fiber braid from the mold to obtain a spring blank.

[0120] Step 6: Formation of rare earth co-infiltration layer:

[0121] 6.1) Weigh the appropriate amounts of SiC, CeO2, Y2O3, La2O3, and Al2O3 and mix them evenly according to the following mass percentages to prepare an embedding medium:

[0122] SiC 10%, CeO21%, Y2O36%, La2O32%, and the balance is Al2O3.

[0123] 6.2) The embedding agent prepared in 6.1) was used to embed the spring blank prepared above to a thickness of 3 mm to obtain an embedding mixture.

[0124] 6.3) The embedding mixture obtained in 6.2) was heated to 1450°C at 5 Pa, maintained at this temperature for 0.5 h, and then cooled to room temperature to obtain a stabilized spring blank.

[0125] Step 7: Formation of surface strengthening layer:

[0126] 7.1) Silicon carbide powder, zirconium carbide powder, polycarbosilane, and xylene are mixed in a mass ratio of 2:4:1:12 to obtain a coating slurry.

[0127] 7.2) The above coating slurry was mixed at 50 g / m 2 The sizing amount is evenly applied on the surface of the stabilized spring blank obtained above, and then placed in a fume hood to dry for 24 hours.

[0128] 7.3) Place the dried product from 7.2) in a chemical vapor deposition apparatus, raise the temperature to 1200°C at a pressure of 3000 Pa, and hold for 1 h.

[0129] 7.4) A mixture of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:15:25 and the deposition was continued for 64 h.

[0130] 7.5) Keep the temperature at 1200℃ for 1 hour and then cool to room temperature.

[0131] 7.6) Take 7.3), 7.4) and 7.5) as one cycle, and perform this cycle 4 times to prepare the surface reinforcement layer and obtain a semi-finished spring.

[0132] Step 8, polishing:

[0133] A sandblasting machine is used to remove burrs and attachments on the surface of the semi-finished spring obtained in the above steps to obtain a finished spring, namely the ceramic composite material spring of this embodiment.

[0134] Example 3

[0135] This embodiment provides a ceramic composite spring, which is manufactured by the following steps:

[0136] Step 1, select the mold:

[0137] 1.1) In this embodiment, in order to prepare a buffer spring for an aerospace engine accessory, a mold model with a spiral groove of corresponding dimensions was designed using 3D software based on the geometric parameters of the spring: wire diameter of 5 mm, maximum outer diameter of 22 mm, pitch of 8 mm, and total height of 33 mm.

[0138] 1.2) According to the obtained mold model, high-purity graphite is used as raw material, and mechanical processing is adopted to complete the mold processing to obtain a spring mold.

[0139] Step 2: Stabilization of the spring mold:

[0140] 2.1) Place the spring mold obtained in the above steps in a chemical vapor deposition furnace, heat it to 1250°C at a pressure of 80 Pa, and keep it at this temperature for 6 hours.

[0141] 2.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced with a flow ratio of trichloromethylsilane, hydrogen, and argon of 1:4:11, and the deposition was continued for 8 h.

[0142] 2.3) Maintaining the temperature at 1250°C for 1.5 hours, and then cooling to room temperature to obtain a stabilized spring mold.

[0143] Step 3: Preparation of spring braid:

[0144] 3.1) After four strands of silicon carbide fibers are combined, a three-dimensional four-directional braiding method is used with a warp and weft braiding angle of 27° to obtain a fiber braid.

[0145] 3.2) The fiber braid is embedded in situ along the spiral groove of the mold, and graphite bolts are used to fix the two ends of the spiral braid to the two ends of the mold to obtain a spring braid.

[0146] Step 4, deposition of the interfacial phase layer:

[0147] 4.1) Place the mold with the spring braid embedded in it in a chemical vapor infiltration furnace. Raise the temperature to 760°C at a pressure of 1500 Pa and keep it at that temperature for 6 h.

[0148] 4.2) A mixed gas of argon, hydrogen, ammonia, and boron trichloride was introduced at a flow rate ratio of 1:7:13:13 and the mixture was deposited for 30 hours to form an interfacial phase layer on the surface and inside the fiber braid.

[0149] Step 5, deposition of ceramic matrix layer:

[0150] 5.1) Under a pressure of 1700 Pa, heat to 1100°C and keep warm for 1.5 hours.

[0151] 5.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:10:20 and the deposition was continued for 58 h.

[0152] 5.3) Keep the temperature at 1100°C for 1.5 hours and then cool to room temperature.

[0153] 5.4) Treat 5.1), 5.2) and 5.3) as one loop and execute the loop 6 times.

[0154] 5.5) Remove the fiber braid from the mold to obtain a spring blank.

[0155] Step 6, formation of rare earth co-infiltration layer:

[0156] 6.1) Weigh the appropriate amounts of SiC, CeO2, Y2O3, La2O3, and Al2O3 and mix them evenly according to the following mass percentages to prepare an embedding medium:

[0157] SiC 17.5%, CeO23%, Y2O35%, La2O31%, and the balance is Al2O3.

[0158] 6.2) The embedding agent prepared in 6.1) was used to embed the spring blank prepared above to a thickness of 1.5 mm to obtain an embedding mixture.

[0159] 6.3) The embedding mixture obtained in 6.2) was heated to 1370°C at 80 Pa, maintained at this temperature for 1 hour, and then cooled to room temperature to obtain a stabilized spring blank.

[0160] Step 7: Formation of surface strengthening layer:

[0161] 7.1) Silicon carbide powder, zirconium carbide powder, polycarbosilane, and xylene are mixed in a mass ratio of 2:4:1:12 to obtain a coating slurry.

[0162] 7.2) The above coating slurry was mixed at 40g / m 2 The sizing amount is evenly applied on the surface of the stabilized spring blank obtained above, and then placed in a fume hood to dry for 24 hours.

[0163] 7.3) Place the dried product from 7.2) in a chemical vapor deposition apparatus, raise the temperature to 1100°C at a pressure of 1700 Pa, and maintain the temperature for 1.5 h.

[0164] 7.4) A mixture of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:10:20 and the deposition was continued for 58 h.

[0165] 7.5) Keep at 1100°C for 1.5 h and then cool to room temperature.

[0166] 7.6) Take 7.3), 7.4) and 7.5) as one cycle, and perform this cycle 6 times to prepare the surface reinforcement layer and obtain a semi-finished spring.

[0167] Step 8, polishing:

[0168] A sandblasting machine is used to remove burrs and attachments on the surface of the semi-finished spring obtained in the above steps to obtain a finished spring, namely the ceramic composite material spring of this embodiment.

[0169] Comparative Example 1

[0170] This comparative example provides a ceramic composite spring, which is prepared by the following steps:

[0171] Step 1, select the mold:

[0172] 1.1) The geometric parameters of this comparative spring are: wire diameter 3 mm, maximum outer diameter 25 mm, pitch 12 mm, total height 50 mm. A mold model with a spiral groove of corresponding dimensions was designed using 3D software.

[0173] 1.2) According to the obtained mold model, high-purity graphite is used as raw material, and mechanical processing is adopted to complete the mold processing to obtain a spring mold.

[0174] Step 2: Stabilization of the spring mold:

[0175] 2.1) Place the spring mold obtained in the above steps in a chemical vapor deposition furnace, heat it to 1200°C at a pressure of 20 Pa, and keep it at this temperature for 4 hours.

[0176] 2.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced with a flow ratio of trichloromethylsilane, hydrogen, and argon of 1:3:10, and the deposition was continued for 4 hours.

[0177] 2.3) Continue to maintain the temperature at 1200°C for 2 hours, then cool to room temperature to obtain a stabilized spring mold.

[0178] Step 3: Preparation of spring braid:

[0179] 3.1) After combining 6 strands of carbon fiber, a three-dimensional four-directional braiding method is used with a warp and weft braiding angle of 22° to obtain a fiber braid.

[0180] 3.2) The fiber braid is embedded in situ along the spiral groove of the mold, and the two ends of the spiral braid are fixed to the two ends of the mold using graphite bolts to obtain a spring braid.

[0181] Step 4, deposition of the interfacial phase layer:

[0182] 4.1) Place the mold with the spring braid embedded in it in a chemical vapor infiltration furnace. Raise the temperature to 680°C at a pressure of 100 Pa and keep it at that temperature for 4 h.

[0183] 4.2) Using propane as the carbon source, a mixture of argon and propane was introduced with a flow ratio of 4:1 and the deposition was continued for 24 h.

[0184] 4.3) The above 4.1) and 4.2) are regarded as one cycle, and this cycle is performed twice to produce a layer of pyrolytic carbon on the surface and inside of the fiber braid, forming an interface phase layer.

[0185] Step 5, deposition of ceramic matrix layer:

[0186] 5.1) Under a pressure of 500 Pa, heat to 1000°C and keep warm for 2 hours.

[0187] 5.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 for 52 h.

[0188] 5.3) Keep the temperature at 1000℃ for 2 h and then cool to room temperature.

[0189] 5.4) Treat 5.1), 5.2) and 5.3) as one loop and execute the loop 6 times.

[0190] 5.5) Remove the fiber braid from the mold to obtain a semi-finished spring.

[0191] Step 6, polishing:

[0192] A sandblasting machine is used to remove burrs and attachments on the surface of the semi-finished spring obtained in the above steps to obtain a finished spring, namely the ceramic composite material spring of this comparative example.

[0193] Comparative Example 2

[0194] This comparative example provides a ceramic composite spring, which is prepared by the following steps:

[0195] Step 1, select the mold:

[0196] 1.1) This comparative example uses 3D software to design a mold model with a spiral groove of corresponding dimensions based on the geometric parameters of the spring: wire diameter of 3 mm, maximum outer diameter of 25 mm, pitch of 12 mm, and total height of 50 mm.

[0197] 1.2) According to the obtained mold model, high-purity graphite is used as raw material, and mechanical processing is adopted to complete the mold processing to obtain a spring mold.

[0198] Step 2: Stabilization of the spring mold:

[0199] 2.1) Place the spring mold obtained in the above steps in a chemical vapor deposition furnace, heat it to 1200°C at a pressure of 20 Pa, and keep it at this temperature for 4 hours.

[0200] 2.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced with a flow ratio of trichloromethylsilane, hydrogen, and argon of 1:3:10, and the deposition was continued for 4 hours.

[0201] 2.3) Continue to maintain the temperature at 1200°C for 2 hours, then cool to room temperature to obtain a stabilized spring mold.

[0202] Step 3: Preparation of spring braid:

[0203] 3.1) After combining one strand of silicon carbide fiber, a three-dimensional four-directional braiding method is used with a warp and weft braiding angle of 15° to obtain a fiber braid.

[0204] 3.2) The fiber braid is embedded in situ along the spiral groove of the mold, and the two ends of the spiral braid are fixed to the two ends of the mold using graphite bolts to obtain a spring braid.

[0205] Step 4, deposition of the interfacial phase layer:

[0206] 4.1) Place the mold with the spring braid embedded in it in a chemical vapor infiltration furnace. Raise the temperature to 680°C at a pressure of 100 Pa and keep it at that temperature for 4 h.

[0207] 4.2) A mixed gas of argon, hydrogen, ammonia, and boron trichloride was introduced at a flow ratio of 1:5:10:10, and the deposition was continued for 24 h.

[0208] 4.3) The above 4.1) and 4.2) were regarded as one cycle, and this cycle was performed twice to form an interfacial phase layer with a thickness of 650 nm on the surface and inside of the fiber braid.

[0209] Step 5, deposition of ceramic matrix layer:

[0210] 5.1) Under a pressure of 500 Pa, heat to 1000°C and keep warm for 2 hours.

[0211] 5.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 for 52 h.

[0212] 5.3) Keep the temperature at 1000℃ for 2 h and then cool to room temperature.

[0213] 5.4) Treat 5.1), 5.2) and 5.3) as one loop and execute the loop 9 times.

[0214] 5.5) Remove the fiber braid from the mold to obtain a spring blank.

[0215] Step 6: Formation of surface strengthening layer:

[0216] 6.1) Silicon carbide whiskers, polycarbosilane, and xylene are mixed in a mass ratio of 4:1:15 to obtain a coating slurry.

[0217] 6.2) The above coating slurry was mixed at 75g / m 2 The sizing amount is evenly applied on the surface of the spring blank obtained above, and then placed in a fume hood to dry for 2 hours.

[0218] 6.3) Place the dried product from 6.2) in a chemical vapor deposition apparatus, raise the temperature to 1000°C at a pressure of 500 Pa, and maintain the temperature for 2 h.

[0219] 6.4) A mixture of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 and the deposition was continued for 52 h.

[0220] 6.5) Keep the temperature at 1000°C for 2 h and then cool to room temperature.

[0221] 6.6) Take 6.3), 6.4) and 6.5) as one cycle, and perform this cycle 8 times to produce a semi-finished spring.

[0222] Step 7, polishing:

[0223] A sandblasting machine is used to remove burrs and attachments on the surface of the semi-finished spring obtained in the above steps to obtain a finished spring, namely the ceramic composite material spring of this comparative example.

[0224] Comparative Example 3

[0225] This comparative example provides a ceramic composite spring, which is prepared by the following steps:

[0226] Step 1, select the mold:

[0227] 1.1) This comparative example uses 3D software to design a mold model with a spiral groove of corresponding dimensions based on the geometric parameters of the spring: wire diameter of 3 mm, maximum outer diameter of 25 mm, pitch of 12 mm, and total height of 50 mm.

[0228] 1.2) According to the obtained mold model, high-purity graphite is used as raw material, and mechanical processing is adopted to complete the mold processing to obtain a spring mold.

[0229] Step 2: Stabilization of the spring mold:

[0230] 2.1) Place the spring mold obtained in the above steps in a chemical vapor deposition furnace, heat it to 1200°C at a pressure of 20 Pa, and keep it at this temperature for 4 hours.

[0231] 2.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced with a flow ratio of trichloromethylsilane, hydrogen, and argon of 1:3:10, and the deposition was continued for 4 hours.

[0232] 2.3) Continue to maintain the temperature at 1200°C for 2 hours, then cool to room temperature to obtain a stabilized spring mold.

[0233] Step 3: Preparation of spring braid:

[0234] 3.1) After combining four strands of silicon carbide fibers, a three-dimensional four-directional braiding method is used with a warp and weft braiding angle of 22° to obtain a fiber braid.

[0235] 3.2) The fiber braid is embedded in situ along the spiral groove of the mold, and the two ends of the spiral braid are fixed to the two ends of the mold using graphite bolts to obtain a spring braid.

[0236] Step 4, deposition of the interfacial phase layer:

[0237] 4.1) Place the mold with the spring braid embedded in it in a chemical vapor infiltration furnace. Raise the temperature to 680°C at a pressure of 100 Pa and keep it at that temperature for 4 h.

[0238] 4.2) Using propane as the carbon source, a mixture of argon and propane was introduced with a flow ratio of 4:1 and the deposition was continued for 24 h.

[0239] 4.3) The above 4.1) and 4.2) are regarded as one cycle, and the cycle is performed twice to form an interface phase layer of a pyrolytic carbon layer on the surface and inside of the fiber braid.

[0240] Step 5, deposition of ceramic matrix layer:

[0241] 5.1) Under a pressure of 500 Pa, heat to 1000°C and keep warm for 2 hours.

[0242] 5.2) A mixed gas of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 for 52 h.

[0243] 5.3) Keep the temperature at 1000℃ for 2 h and then cool to room temperature.

[0244] 5.4) Treat 5.1), 5.2) and 5.3) as one loop and execute the loop three times.

[0245] 5.5) Remove the fiber braid from the mold to obtain a spring blank.

[0246] Step 6: Formation of surface strengthening layer:

[0247] 6.1) Silicon carbide whiskers, polycarbosilane, and xylene are mixed in a mass ratio of 4:1:15 to obtain a coating slurry.

[0248] 6.2) The above coating slurry was mixed at a rate of 10 g / m 2 The sizing amount is evenly applied on the surface of the stabilized spring blank obtained above, and then placed in a fume hood to dry for 2 hours.

[0249] 6.3) Place the dried product from 6.2) in a chemical vapor deposition apparatus, raise the temperature to 1000°C at a pressure of 500 Pa, and maintain the temperature for 2 h.

[0250] 6.4) A mixture of trichloromethylsilane, hydrogen, and argon was introduced at a flow ratio of 1:5:15 and the deposition was continued for 52 h.

[0251] 6.5) Keep the temperature at 1000°C for 2 h and then cool to room temperature.

[0252] 6.6) Take 6.3), 6.4) and 6.5) as one cycle, and perform this cycle 8 times to produce a semi-finished spring.

[0253] Step 7, polishing:

[0254] A sandblasting machine is used to remove burrs and attachments on the surface of the semi-finished spring obtained in the above steps to obtain a finished spring, namely the ceramic composite material spring of this comparative example.

[0255] In order to facilitate the distinction between the above-mentioned embodiments and comparative examples, the main parameters of the preparation methods of the above-mentioned embodiments 1 to 3 and comparative examples 1 to 3 are summarized as shown in Table 1.

[0256] Table 1 Main parameters of the preparation methods of Examples 1-3 and Comparative Examples 1-3

[0257]

[0258] Experimental part

[0259] (1) Stiffness test

[0260] The present invention refers to the test method in GJB 6476 "Test method for compression properties of continuous fiber reinforced ceramic matrix composite materials at room temperature" and tests the stiffness of the ceramic composite springs of Examples 1 to 3 and Comparative Examples 1 to 3, respectively. The test results are shown in Table 2.

[0261] Table 2 Stiffness test results of ceramic composite springs

[0262] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 stiffness 28N / mm 33N / mm 25N / mm 2.2N / mm 15N / mm 21N / mm

[0263] The test results in Table 1 show that the stiffness of Examples 1-3 is significantly improved compared to the carbon fiber-reinforced carbon-based composite spring of Comparative Example 1. The stiffness of the ceramic composite spring of Example 1 is 28 N / mm, that of the ceramic composite spring of Example 2 is 33 N / mm, and that of the ceramic composite spring of Example 3 is 25 N / mm. Comparing the stiffness of Example 1 with Comparative Examples 1-3 shows that Example 1 exhibits significantly improved stiffness compared to Comparative Examples 1-3.

[0264] (2) Spring rebound performance test

[0265] The present invention refers to the test method in GJB 6476 "Test Method for Room-Temperature Compression Performance of Continuous Fiber Reinforced Ceramic Matrix Composites" and conducts room-temperature compression performance tests on the ceramic composite springs of Examples 1 to 3 and Comparative Examples 1 to 3. After repeated compression to the maximum height 1000 times and unloading, the length of the spring is tested. The degree of change in spring length, i.e., the spring's rebound retention rate, is used to evaluate the spring's rebound performance. The obtained spring rebound retention rate results are summarized in Table 3.

[0266] The spring rebound retention rate = the length of the spring after the test / the original length of the spring × 100%.

[0267] Table 3 Rebound performance test results of ceramic composite springs

[0268] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 stiffness 28N / mm 33N / mm 25N / mm 2.2N / mm 15N / mm 21N / mm Rebound retention rate 98％ 97％ 99％ 88％ 95％ 96％

[0269] The test results in Table 3 show that the rebound performance of Examples 1-3 is significantly improved compared to the carbon fiber-reinforced carbon-based composite spring of Comparative Example 1. The rebound retention rate of the ceramic composite spring of Example 1 is 98%, that of the ceramic composite spring of Example 2 is 97%, and that of the ceramic composite spring of Example 3 is 99%. Furthermore, a comparison of the rebound performance of Example 1 with Comparative Examples 1-3 shows that the rebound performance of Example 1 is significantly improved compared to Comparative Examples 1-3.

[0270] (3) Performance stability test

[0271] The present invention tested the performance stability of the ceramic composite springs of Examples 1-3 and Comparative Examples 1-3, respectively. The testing method was as follows: the ceramic composite springs of Examples 1-3 and Comparative Examples 1-3 were aged 100 times, each aging treatment being carried out under the following conditions: first, maintaining the springs in a vacuum furnace at 1350°C for 1 hour, and then cooling them to room temperature in an air environment. The stiffness and mass of the ceramic composite springs of Examples 1-3 and Comparative Examples 1-3 after 100 aging cycles were then tested. The degree of change in the spring stiffness and mass, namely, the spring's post-aging stiffness retention rate and post-aging mass loss rate, were used to evaluate the spring's performance stability. The obtained post-aging stiffness retention rate and post-aging mass loss rate results are summarized in Table 4.

[0272] The stiffness retention rate after aging = stiffness of the spring after aging / original stiffness of the spring × 100%.

[0273] Mass loss rate after aging = 100% - (mass of the spring after aging / original mass of the spring) x 100%.

[0274] Table 4 Stiffness and mass test results of ceramic composite springs after 100 aging treatments

[0275] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Stiffness retention after aging 85％ 82％ 87％ 54％ 79％ 71％ Mass loss rate after aging 0.02％ 0.03％ 0.01％ 1.08％ 0.02％ 0.45％

[0276] The test results in Table 4 show that, for the carbon fiber-reinforced carbon-based composite material spring of Comparative Example 1, the stiffness retention rates after aging were significantly improved, and the mass loss rates after aging were significantly reduced, for Examples 1-3. Furthermore, a comparison of the stiffness retention rates and mass loss rates after aging of Example 1 with those of Comparative Examples 1-3 shows that, relative to Comparative Examples 1-3, the stiffness retention rates after aging of Example 1 were significantly improved, and the mass loss rates after aging were significantly reduced.

[0277] In summary, the selection of fiber materials and interface phase layers, and the forms of the ceramic matrix layer, rare earth co-infiltration layer, and surface reinforcement layer will all affect the stiffness, resilience, and performance stability of the spring. This also indicates that the improvement of the stiffness, resilience, and performance stability of the spring achieved by the present invention is not achieved by adjusting a single factor, but is achieved by the synergistic effect of various factors.

[0278] Obviously, the above embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing a ceramic composite spring, characterized in that: The following steps are involved: Select the corresponding spring mold according to the required spring structure; In an atmosphere containing a silicon carbide source, a silicon carbide ceramic layer is deposited on the surface of the spring mold by chemical vapor deposition to obtain a stabilized spring mold; Combining a plurality of strands of silicon carbide fibers and braiding them to obtain a fiber braid; embedding the fiber braid into the stabilized spring mold and fixing it to obtain a spring braid; In an atmosphere containing a boron nitride source, a layer of boron nitride is deposited as an interface phase layer inside and on the surface of the spring braid by chemical vapor deposition to obtain a modified spring braid; In an atmosphere containing a silicon carbide source, a ceramic matrix layer is deposited on the surface of the interface phase layer by chemical vapor deposition, and the mold is removed to obtain a spring blank; Using a rare earth mixture containing at least two rare earth oxides as an embedding agent, the spring blank is subjected to embedding infiltration treatment by an embedding infiltration method to form a rare earth co-infiltration layer on the surface of the ceramic matrix layer to obtain a stabilized spring blank; Dispersing carbide powder in an organic solvent to obtain a coating slurry; applying the coating slurry to the surface of the stabilized spring blank, drying, and then forming a carbide layer on the surface of the rare earth co-carburized layer by chemical vapor deposition in an atmosphere containing a silicon carbide source to serve as a surface reinforcement layer, thereby obtaining a semi-finished spring; Grinding the semi-finished spring product to remove surface defects and impurities to obtain the ceramic composite material spring; The coating slurry has a sizing amount of 30 g / m 2 ~50g / m 2 .

2. The preparation method according to claim 1, wherein The process parameters of the braiding process are: The number of strands of the silicon carbide fiber is 2 to 6; The weaving mode is any one of three-dimensional four-directional, three-dimensional six-directional and two-dimensional circumferential weaving modes; The warp and weft weaving angles are 17°~38°.

3. The preparation method according to claim 1, wherein When depositing the interface phase layer, the process conditions of chemical vapor deposition are: Under a pressure of 100 Pa to 3000 Pa, the temperature is raised to 680°C to 840°C and kept at this temperature for 4 to 8 hours; an atmosphere containing a boron nitride source is then introduced and deposited for 24 to 36 hours; Repeat the above steps 1 to 2 times, then cool to room temperature. The atmosphere containing the boron nitride source is a mixed gas consisting of argon, hydrogen, ammonia and boron trichloride; and the flow ratio of the argon, hydrogen, ammonia and boron trichloride is 1:5~8:10~15:10~15.

4. The preparation method according to claim 1, wherein When depositing the ceramic matrix layer, the process conditions of chemical vapor deposition are: Under a pressure of 500 Pa to 3000 Pa, the temperature is raised to 1000° C. to 1200° C. and then kept at this temperature for 1 to 2 hours. A mixed gas consisting of trichloromethylsilane, hydrogen, and argon is then introduced. After deposition for 52 to 64 hours, the introduction of trichloromethylsilane is stopped, the temperature is kept at this temperature for another 1 to 2 hours, and then the temperature is lowered to room temperature. Repeat the above steps 4 to 8 times, then demould. Wherein, the flow ratio of trichloromethylsilane, hydrogen and argon is 1:5~15:15~25.

5. The preparation method according to claim 1, wherein The raw materials for preparing the embedding agent used in the embedding infiltration treatment are composed of the following components by mass percentage: SiC 10%~25%, CeO2 1%~5%, Y2O3 4%~6%, La2O3 0.5%~2%, and the balance is Al2O3, totaling 100%.

6. The preparation method according to claim 1, wherein The embedding infiltration treatment is carried out by the following steps: Covering the workpiece surface with an embedding agent to a thickness of 0.5 mm to 3 mm to obtain an embedding mixture; The embedding mixture is heated to 1300° C. to 1450° C. at 5 Pa to 150 Pa, kept at this temperature for 0.5 h to 1.5 h, and then cooled to room temperature to obtain the stabilized spring blank.

7. The preparation method according to claim 1, wherein When depositing a silicon carbide ceramic layer on the surface of the spring mold, the process conditions of chemical vapor deposition are: Under a pressure of 20 Pa to 150 Pa, the spring mold is heated to 1200° C. to 1300° C. and kept at this temperature for 4 to 8 hours; a mixed gas consisting of trichloromethylsilane, hydrogen, and argon is then introduced. After deposition for 4 to 12 hours, the introduction of trichloromethylsilane is stopped, the mold is kept at this temperature for 1 to 2 hours, and then cooled to room temperature; Wherein, the flow ratio of trichloromethylsilane, hydrogen and argon is 1:3~5:10~12.

8. The preparation method according to claim 1, wherein The carbide powder is one or more of silicon carbide powder, silicon carbide whiskers and zirconium carbide powder; The organic solvent is one or more of polycarbosilane, xylene and polypropylene alcohol; The usage ratio of the carbide powder to the organic solvent is 1 mg:5 mL to 25 mL.

9. A ceramic composite spring prepared by the preparation method according to any one of claims 1 to 8.

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