Lightweight ceramic bearing and manufacturing method thereof

Abstract

The invention relates to the field of bearings, in particular to a light ceramic bearing and a manufacturing method thereof.The light ceramic bearing comprises an inner ring, an outer ring, a retainer and ceramic balls, the inner ring and the outer ring are both made of C / C-SiC ceramic materials, and the C / C-SiC ceramic materials comprise hyperbranched polycarbosilane, divinyl benzene, xylene, carbon fibers, phenolic resin and silicon powder; the C / C-SiC ceramic material has a skeleton network structure formed by carbon fibers and a SiC matrix wrapping fiber bundles of the skeleton network structure, the SiC matrix is obtained by reaction and conversion of hyperbranched polycarbosilane and silicon powder permeating into the skeleton network structure and carbon, and pores of the SiC matrix are filled with free carbon; the manufacturing method comprises the following steps: preparing the bearing ring from the hyperbranched polycarbosilane, the divinyl benzene, the xylene, the carbon fiber and the silicon powder, and assembling the bearing by a cold charging method. The inner ring and the outer ring are made of C / C-SiC ceramic composite materials, the ceramic balls are made of Si3N4 ceramic materials, the retainer is made of polytetrafluoroethylene materials, and a bearing structure with complementary performance is formed.

Description

Technical Field

[0001] The present invention relates to the field of bearings, and in particular to a lightweight ceramic bearing and a manufacturing method thereof. Background Art

[0002] Bearings are essential components in modern mechanical equipment, and their performance directly determines the accuracy, efficiency, and service life of the entire machine. With the continuous advancement of high-end technologies in aerospace and other fields, increasingly stringent lightweighting requirements are being placed on core components like bearings to meet the demands of operating in extreme environments.

[0003] Traditional metal bearings have been widely used in the mechanical field due to their good toughness and excellent machinability, but they also have many inherent defects: on the one hand, the high density of metal materials makes it difficult to meet the requirements of lightweight components in the aerospace field; on the other hand, their strength and hardness are relatively limited, and they perform poorly in high temperature resistance, wear resistance and corrosion resistance, and cannot adapt to the increasingly complex working conditions in the development of modern science and technology and industrial production.

[0004] To overcome the shortcomings of traditional metal bearings, ceramic materials are gradually being used in the field of bearing manufacturing. Ceramic bearings have significant advantages such as low density, high strength and hardness, high temperature resistance, strong wear resistance, excellent corrosion resistance, and low operating noise. Therefore, the use of ceramic materials to manufacture bearings has become an important direction for the development of special bearings in the aerospace field. However, the commonly used traditional ceramic materials such as silicon nitride and silicon carbide still have obvious shortcomings when used in bearing manufacturing: these materials are brittle and have low toughness. They are prone to fracture under impact or alternating loads, and their density is difficult to further reduce. This limits the further application of ceramic bearings in fields such as aerospace that have extremely high requirements for lightweight and impact resistance. Summary of the Invention

[0005] In response to the above problems, the present invention proposes a lightweight ceramic bearing and a manufacturing method thereof. The specific technical solutions are as follows: A lightweight ceramic bearing comprises an inner ring, an outer ring, a retaining frame and ceramic balls. The inner ring and the outer ring are both made of C / C-SiC ceramic material, the ceramic balls are made of Si3N4 ceramic material, and the retaining frame is made of polytetrafluoroethylene material. The raw materials of the C / C-SiC ceramic material include hyperbranched polycarbosilane, divinylbenzene, xylene, carbon fiber, phenolic resin and silicon powder. The C / C-SiC ceramic material has a skeleton network structure composed of carbon fibers and a SiC matrix that wraps the fiber bundles of the network skeleton structure. The SiC matrix is ​​obtained by reacting hyperbranched polycarbosilane and silicon powder that have infiltrated the skeleton network structure with carbon, and the pores of the SiC matrix are filled with free carbon.

[0006] Furthermore, in the raw materials of the C / C-SiC ceramic material, the diameter of the carbon fiber is 7 μm; the solid content of the phenolic resin is ≥50%, and the free phenol content of the phenolic resin is ≤15%; the purity of the silicon powder is ≥99.8%, and the particle size of the silicon powder is 2-10 μm.

[0007] A method for manufacturing a lightweight ceramic bearing, used to manufacture the above-mentioned ceramic bearing, comprises the following steps: S1. Hyperbranched polycarbosilane, divinylbenzene, and xylene are mixed by a combination of wet dispersion and dry mixing to prepare a liquid precursor mixture; S2. Prepare a fiber preform by taking carbon fibers and using a three-dimensional braiding machine with a circular braiding or spiral winding process, in an orthogonal braiding or multi-angle laying manner; S3, taking the bearing ring mold and trimming the fiber preform according to the mold size; S4, placing the fiber preform into a bearing ring mold, filling the mold with phenolic resin, and heating the mold to obtain a C / C composite material blank; S5, placing the C / C composite body in a vacuum pressure impregnation furnace, impregnating the liquid precursor mixture into the C / C composite body, and then placing the impregnated C / C composite body in a vacuum induction ultrahigh temperature sintering furnace for siliconization; S6, repeat S5, every time S5 is repeated three times, a high temperature pore opening and graphitization treatment of 1800°C for 3 to 6 hours is performed, and S5 is repeated 11 to 14 times in total to obtain a bearing ring; S7. The inner ring and outer ring are obtained through S1-S6. After grinding the inner ring and outer ring, the inner ring, outer ring, ceramic balls and retaining frame are assembled.

[0008] Furthermore, in S1, the hyperbranched polycarbosilane and divinylbenzene are prepared in a mass ratio of 59-62% of hyperbranched polycarbosilane, 20-24% of divinylbenzene, and 15-18% of xylene. The hyperbranched polycarbosilane and divinylbenzene are first dissolved in xylene as a solvent and wet mixed. Then, the xylene is evaporated and solvent-free dry mixing is performed to obtain a liquid precursor mixture.

[0009] Furthermore, in S2, the volume of the carbon fibers in the fiber preform is 30%-32% of the entire volume of the fiber preform.

[0010] Furthermore, in S4, the heating process is as follows: the temperature in the mold is raised to 80°C at a temperature rise rate of 1.5°C / min, and then maintained at 80°C for 60 minutes; then the temperature in the mold is raised to 120°C at a temperature rise rate of 1°C / min, and maintained at a pressure of 2-5 MPa for 30 minutes; then the temperature in the mold is further raised to 150°C at a temperature rise rate of 1°C / min, and maintained at a pressure of 20 MPa for 30 minutes to obtain a C / C composite material green body.

[0011] Furthermore, in S5, during the siliconizing process, the siliconizing temperature is 1700° C., the siliconizing holding time is 30 min, and the vacuum degree is 50 Pa.

[0012] Furthermore, during the siliconizing process, silicon powder is melted and infiltrated into the C / C composite body as a supplementary silicon source for the reaction of hyperbranched polycarbosilane to form a SiC matrix.

[0013] Furthermore, in S6, the pyrolytic carbon in the material is reconstructed by high-temperature pore opening treatment, so that the closed pores are transformed into open pores.

[0014] Furthermore, in S7, a CBN grinding wheel is used to grind the end face of the bearing ring, and a brown corundum grinding wheel is used to grind the inner diameter and outer diameter of the bearing ring; during assembly, the inner ring, outer ring, ceramic ball and retainer are assembled using the cold assembly method.

[0015] The beneficial effects of the present invention are: 1. The inner and outer rings are made of C / C-SiC ceramic composite materials, the ceramic balls are made of Si3N4 ceramic materials, and the cage is made of polytetrafluoroethylene materials, forming a bearing structure with complementary performance; C / C-SiC ceramics have a low density of about 2T / m 3 , which is only about 25% of traditional metal bearings and only about 60% of traditional ceramic bearings. It can significantly reduce the overall weight of the bearing and meet the lightweight needs in special environments; C / C-SiC ceramics can still maintain stable mechanical properties and friction coefficients above 1000°C, and its wear resistance is better than that of traditional metal bearings, extending the service life of the bearings. It can work stably in ultra-high temperature and ultra-low temperature environments, so that the bearings can be used in special environments such as spacecraft and space stations with ultra-high temperature, ultra-low temperature and extremely high lightweight requirements; C / C-SiC ceramic materials have pores. During the friction process, the gas or trace lubricant in the pores can play a self-lubricating role, reducing friction and wear, and reducing dependence on external lubrication. It is suitable for special scenarios such as spacecraft and space stations where lubrication is difficult or high cleanliness requirements are high.

[0016] 2. The fiber preform is made by annular weaving or spiral winding process, which has higher structural strength and is beneficial to improving the service performance of ceramic bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 The fiber preform of the present invention; Figure 2 This is the fracture microscopic morphology of the ceramic composite material of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions of the present invention will be described clearly and completely below in conjunction with embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, but not all of the embodiments.

[0020] In a first aspect, the present invention provides a lightweight ceramic bearing comprising an inner ring, an outer ring, a retainer and ceramic balls, wherein the inner ring and the outer ring are both made of C / C-SiC ceramic material, the ceramic balls are made of Si3N4 ceramic material, and the retainer is made of polytetrafluoroethylene material; the raw materials of the C / C-SiC ceramic material include hyperbranched polycarbosilane (Tri-ImPCS), divinylbenzene (DVB), xylene (xylene), carbon fiber, phenolic resin and silicon powder; the C / C-SiC ceramic material exhibits a typical "fiber-interface-matrix" tertiary structure, wherein the carbon fiber constitutes the skeleton network structure of the ceramic material, the hyperbranched polycarbosilane and silicon powder infiltrated into the skeleton network structure react with the carbon to convert the SiC matrix to wrap the fiber bundle, and the residual free carbon fills the pores of the SiC matrix. The pores in ceramic materials are mainly divided into three categories: the first is the macropores (10-50μm) between fiber bundles, which are determined by the weaving structure; the second is the micropores (1-5μm) in the matrix, which are formed by the cracking and shrinkage of the precursor; and the third is the interfacial nanopores (<500nm), which are caused by the mismatch of thermal expansion coefficients.

[0021] Furthermore, in the raw materials for the C / C-SiC ceramic material, the carbon fibers have a diameter of 7 μm; the solid content of the phenolic resin is ≥50%, and the free phenol content of the phenolic resin is ≤15%; the purity of the silicon powder is ≥99.8%, and the particle size of the silicon powder is 2-10 μm. Furthermore, the hyperbranched polycarbosilane is ball-milled into a powder and passed through a 100-mesh sieve.

[0022] In a second aspect, the present invention provides the following three embodiments of a method for manufacturing the lightweight ceramic bearing.

[0023] Example 1: A method for manufacturing a lightweight ceramic bearing, comprising the following steps: S1. Mixing hyperbranched polycarbosilane (62%), divinylbenzene (23%), and xylene (15%) by weight using a combination of wet dispersion and dry mixing to form a uniform liquid precursor mixture. The resulting mixed solution has a viscosity of 600-800 MPa·s at a temperature of 40-60°C. Xylene is used as a solvent to dissolve the hyperbranched polycarbosilane and divinylbenzene, adjust the viscosity of the hyperbranched polycarbosilane / divinylbenzene system, ensure uniform dispersion during mixing, and ensure reaction uniformity.

[0024] Specifically, when performing wet dispersion and dry mixing operations, wet dispersion is first performed to dissolve the hyperbranched polycarbosilane and divinylbenzene in a xylene solvent, and then fully dispersed by stirring, ultrasound, etc. to form a uniform solution, ensuring that the components are evenly distributed at the microscopic level; then dry mixing is performed to evaporate the solvent xylene at a certain temperature, so that the remaining hyperbranched polycarbosilane and divinylbenzene are further mixed evenly to obtain a uniform liquid precursor mixture.

[0025] S2. Take high-strength carbon fiber and use a three-dimensional braiding machine to adopt a circular braiding or spiral winding process, and use multi-angle (±45°) laying to prepare a fiber preform. The volume of the carbon fiber in the fiber preform is 30% of the total volume of the fiber preform. The fiber preform is sprayed with low-viscosity epoxy resin to prevent it from loosening and deformation.

[0026] S3. Take the bearing ring mold and trim the fiber preform according to the mold size. If splicing is required, use overlapping and ensure that the fibers are continuous at the joints.

[0027] S4. Apply a release agent to the inner surface of the mold, place the fiber preform into the bearing ring mold, spray low-viscosity epoxy resin, and then fill the mold with phenolic resin and heat the mold to obtain a C / C composite material green body. Specifically, the heating process is as follows: increase the temperature in the mold to 80°C at a temperature rise rate of 1.5°C / min, and then keep it warm at 80°C for 60 minutes; then increase the temperature in the mold to 120°C at a temperature rise rate of 1°C / min, and keep it warm at a pressure of 2-5MPa for 30 minutes; then increase the temperature in the mold to 150°C at a temperature rise rate of 1°C / min, and keep it warm at a pressure of 20MPa for 30 minutes to obtain a C / C composite material green body.

[0028] S5. Place the C / C composite body in a vacuum pressure impregnation furnace, and impregnate the liquid precursor mixture into the C / C composite body under a certain pressure; then place the impregnated C / C composite body in a vacuum induction ultra-high temperature sintering furnace for siliconization, so that the C / C composite body is cross-linked, solidified and cracked at high temperature, and the hyperbranched polycarbosilane in the liquid precursor reacts with carbon to form a SiC matrix, thereby obtaining C / C-SiC ceramics; the parameters selected during the siliconization process are as follows: siliconization temperature 1700°C, siliconization holding time 30min, and vacuum degree 50Pa.

[0029] Among them, hyperbranched polycarbosilane is used as a SiC precursor, and its branched structure can increase the cross-linking density, thereby obtaining a higher ceramic yield after cracking. During the high-temperature siliconization process, it reacts with carbon to form a SiC matrix, providing the ceramic with properties such as hardness and wear resistance. Its good fluidity and high ceramic yield are conducive to the preparation process. Divinylbenzene is used as a cross-linking agent to undergo a hydrosilylation reaction with the Si-H bonds in the hyperbranched polycarbosilane to form a three-dimensional network structure, inhibiting the escape of cracked volatiles, and promoting the cross-linking reaction between the hyperbranched polycarbosilane and other components during the mixing process, thereby helping to form a stable network structure and enhancing the overall performance of the ceramic material.

[0030] During the siliconization stage, silicon powder replenishes the silicon source and silicon vacancies created by the cracking of hyperbranched polycarbosilane, ensuring a complete carbonization reaction (3C+Si→SiC+2C). This makes the resulting SiC matrix denser and more uniform, improving the density and performance of the ceramic. Furthermore, silicon powder with a purity of ≥99.8% and a particle size of 2-10μm allows molten silicon to penetrate into micropores. The appropriate purity and particle size facilitate uniform diffusion and reaction during the siliconization process, reducing residual porosity and further ensuring the quality of the ceramic.

[0031] S6. Each time S5 is completed, one "impregnation-curing-cracking" cycle is completed; every three "impregnation-curing-cracking" cycles, a 6-hour high-temperature pore opening and graphitization treatment is performed at 1800°C. If less than three "impregnation-curing-cracking" cycles are completed, no high-temperature pore opening and graphitization treatment is performed; a total of 14 "impregnation-curing-cracking" cycles and 4 high-temperature pore opening and graphitization treatments are performed to obtain a bearing ring based on C / C-SiC ceramics. During the preparation process, there will be some closed pores or incompletely connected structures inside the ceramic material. Through high-temperature treatment, the pyrolytic carbon can be reconstructed, and some closed pores can be transformed into open pores (the pore diameter is expanded by 15-20%), so that these pores are connected to each other or to the outside world, which is conducive to the liquid precursor mixture entering the pores during the impregnation process, and forming a structure filled with free carbon in the pores, which helps to improve the self-lubricating performance; through high-temperature graphitization of the carbon matrix, the chaotic layer carbon structure can be transformed into ordered graphite crystals, which can improve thermal conductivity (40%) and oxidation resistance.

[0032] S7. The inner ring and outer ring are made through S1-S6, and the inner ring and outer ring are ground. The end face of the bearing ring is ground with a CBN grinding wheel, and the inner diameter and outer diameter of the bearing ring are ground with a brown corundum grinding wheel; the inner ring, outer ring, ceramic ball and retainer are assembled by cold assembly method to ensure that the clearance of the ceramic bearing meets the design requirements.

[0033] Example 2: A method for manufacturing a lightweight ceramic bearing, comprising the following steps: S1. Hyperbranched polycarbosilane (61%), divinylbenzene (23%), and xylene (16%) are mixed by a combination of wet dispersion and dry mixing to form a uniform liquid precursor mixture; the resulting mixed solution has a viscosity of 600-800 MPa·s at a temperature of 40-60° C.

[0034] S2. Take high-strength carbon fiber and use a three-dimensional braiding machine to adopt a circular braiding or spiral winding process, and use orthogonal braiding (0° / 90°) to lay up the layers to prepare a fiber preform. The volume of the carbon fiber in the fiber preform is 31% of the total volume of the fiber preform. The fiber preform is sprayed with a low-viscosity epoxy resin to prevent it from loosening and deformation.

[0035] S3. Take the bearing ring mold and trim the fiber preform according to the mold size. If splicing is required, use overlapping and ensure that the fibers are continuous at the joints.

[0036] S4. Apply a release agent to the inner surface of the mold, place the fiber preform into the bearing ring mold, spray low-viscosity epoxy resin, and then fill the mold with phenolic resin and heat the mold to obtain a C / C composite material green body. Specifically, the heating process is as follows: increase the temperature in the mold to 80°C at a temperature rise rate of 1.5°C / min, and then keep it warm at 80°C for 60 minutes; then increase the temperature in the mold to 120°C at a temperature rise rate of 1°C / min, and keep it warm at a pressure of 2-5MPa for 30 minutes; then increase the temperature in the mold to 150°C at a temperature rise rate of 1°C / min, and keep it warm at a pressure of 20MPa for 30 minutes to obtain a C / C composite material green body.

[0037] S5. Place the C / C composite body in a vacuum pressure impregnation furnace and impregnate the liquid precursor mixture into the C / C composite body; then place the impregnated C / C composite body in a vacuum induction ultra-high temperature sintering furnace for siliconization, so that the C / C composite body is cross-linked, solidified and cracked at high temperature, and the hyperbranched polycarbosilane in the liquid precursor reacts with carbon to form a SiC matrix, thereby obtaining C / C-SiC ceramics; the parameters selected during the siliconization process are as follows: siliconization temperature of 1700°C, siliconization holding time of 30 minutes, and vacuum degree of 50Pa.

[0038] S6. Each time S5 is completed, one "impregnation-curing-cracking" cycle is completed; every three "impregnation-curing-cracking" cycles, a 6-hour high-temperature hole opening and graphitization treatment at 1800°C is performed; a total of 12 "impregnation-curing-cracking" cycles and 4 high-temperature hole opening and graphitization treatments are performed to obtain a bearing ring based on C / C-SiC ceramics.

[0039] S7. The inner ring and outer ring are made through S1-S6, and the inner ring and outer ring are ground. The end face of the bearing ring is ground with a CBN grinding wheel, and the inner diameter and outer diameter of the bearing ring are ground with a brown corundum grinding wheel; the inner ring, outer ring, ceramic ball and retainer are assembled by cold assembly method to ensure that the clearance of the ceramic bearing meets the design requirements.

[0040] Example 3: A method for manufacturing a lightweight ceramic bearing, comprising the following steps: S1. Hyperbranched polycarbosilane (59%), divinylbenzene (23%), and xylene (18%) are mixed by a combination of wet dispersion and dry mixing to form a uniform liquid precursor mixture; the resulting mixed solution has a viscosity of 600-800 MPa·s at a temperature of 40-60° C.

[0041] S2. Take high-strength carbon fiber and use a three-dimensional braiding machine to adopt a circular braiding or spiral winding process, and use multi-angle (±45°) laying to prepare a fiber preform. The volume of the carbon fiber in the fiber preform is 32% of the total volume of the fiber preform. The fiber preform is sprayed with a low-viscosity epoxy resin to prevent it from loosening and deformation.

[0042] S3. Take the bearing ring mold and trim the fiber preform according to the mold size. If splicing is required, use overlapping and ensure that the fibers are continuous at the joints.

[0043] S4. Apply a release agent to the inner surface of the mold, place the fiber preform into the bearing ring mold, spray low-viscosity epoxy resin, and then fill the mold with phenolic resin and heat the mold to obtain a C / C composite material green body. Specifically, the heating process is as follows: increase the temperature in the mold to 80°C at a temperature rise rate of 1.5°C / min, and then keep it warm at 80°C for 60 minutes; then increase the temperature in the mold to 120°C at a temperature rise rate of 1°C / min, and keep it warm at a pressure of 2-5MPa for 30 minutes; then increase the temperature in the mold to 150°C at a temperature rise rate of 1°C / min, and keep it warm at a pressure of 20MPa for 30 minutes to obtain a C / C composite material green body.

[0044] S5. Place the C / C composite body in a vacuum pressure impregnation furnace and impregnate the liquid precursor mixture into the C / C composite body; then place the impregnated C / C composite body in a vacuum induction ultra-high temperature sintering furnace for siliconization, so that the C / C composite body is cross-linked, solidified and cracked at high temperature, and the hyperbranched polycarbosilane in the liquid precursor reacts with carbon to form a SiC matrix, thereby obtaining C / C-SiC ceramics; the parameters selected during the siliconization process are as follows: siliconization temperature of 1700°C, siliconization holding time of 30 minutes, and vacuum degree of 50Pa.

[0045] S6. Each time S5 is completed, one "impregnation-curing-cracking" cycle is completed; every three "impregnation-curing-cracking" cycles, a 6-hour high-temperature hole opening and graphitization treatment at 1800°C is performed; a total of 11 "impregnation-curing-cracking" cycles, 3 high-temperature hole opening and graphitization treatments are performed to obtain a bearing ring based on C / C-SiC ceramics.

[0046] S7. The inner ring and outer ring are made through S1-S6, and the inner ring and outer ring are ground. The end face of the bearing ring is ground with a CBN grinding wheel, and the inner diameter and outer diameter of the bearing ring are ground with a brown corundum grinding wheel; the inner ring, outer ring, ceramic ball and retainer are assembled by cold assembly method to ensure that the clearance of the ceramic bearing meets the design requirements.

[0047] The ceramic bearings prepared in Examples 1-3 were subjected to performance tests according to conventional methods, and were subjected to target shooting experiments under the same conditions as conventional all-ceramic (Si3N4) bearings and metal (steel) bearings of the same specifications and sizes in the prior art. The test results are shown in Table 1.

[0048] Table 1 Performance indicators of lightweight all-ceramic bearings of Examples 1 to 3 As can be seen from Table 1, the lightweight all-ceramic bearings of the present invention have significantly lower density and significantly higher hardness than metal bearings; the lightweight all-ceramic bearings have significantly lower density and significantly higher fracture toughness than traditional all-ceramic (Si3N4).

[0049] Figure 1 Shown is a fiber preform with evenly distributed carbon fibers serving as the skeleton network for the ceramic composite. Figure 2 The figure shows the fracture microstructure of the ceramic composite material observed by electron microscope. Figure 2Figures (a), (b), and (c) were treated with the "impregnation-crosslinking-pyrolysis" process 9, 10, and 11 times, respectively. The carbon fibers are long columns, the SiC phase is a dark gray area, the free Si phase is a bright white area, and the pores are black. As shown in the accompanying figure, the pores (black areas) gradually decrease with increasing treatment cycles; fiber pullout decreases with increasing treatment cycles, indicating that the bond between the SiC matrix and the carbon fibers is improving and the carbon fibers are providing significant reinforcement and toughening. The dark gray SiC phase in Figures (b) and (c) shows little change, indicating that after 11 cycles, the preform's pores have been fully filled and carbonized and pyrolyzed, requiring a minimum of 11 cycles.

[0050] In addition, the inner and outer rings of the present invention are made of C / C-SiC ceramic composite materials, the ceramic balls are made of Si3N4 ceramic materials, and the cage is made of polytetrafluoroethylene materials, forming a bearing structure with complementary performance; C / C-SiC ceramics have a low density of about 2T / m 3 , only about 25% of traditional metal bearings and only about 60% of traditional ceramic bearings, significantly reducing the overall weight of the bearings and meeting lightweighting requirements in special environments. C / C-SiC ceramics maintain stable mechanical properties and friction coefficients above 1000°C, and their wear resistance surpasses that of traditional metal bearings, extending the bearing's service life and enabling stable operation in ultra-high and ultra-low temperature environments, such as spacecraft and space stations. The fiber preform is manufactured using a circular braiding or spiral winding process, resulting in higher structural strength and improving the service performance of ceramic bearings.

[0051] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A lightweight ceramic bearing comprising an inner ring, an outer ring, a retainer and ceramic balls, characterized in that: Both the inner and outer rings are made of C / C-SiC ceramic material, the ceramic balls are made of Si3N4 ceramic material, and the retainer is made of polytetrafluoroethylene material; the raw materials of C / C-SiC ceramic material include hyperbranched polycarbosilane, divinylbenzene, xylene, carbon fiber, phenolic resin and silicon powder; C / C-SiC ceramic material has a skeleton network structure composed of carbon fibers and a SiC matrix that wraps the fiber bundles of the network skeleton structure. The SiC matrix is ​​obtained by the reaction of hyperbranched polycarbosilane and silicon powder infiltrated into the skeleton network structure with carbon, and the pores of the SiC matrix are filled with free carbon.

2. A lightweight ceramic bearing according to claim 1, characterized in that: In the raw materials of the C / C-SiC ceramic material, the diameter of the carbon fiber is 7 μm; the solid content of the phenolic resin is ≥50%, and the free phenol content of the phenolic resin is ≤15%; the purity of the silicon powder is ≥99.8%, and the particle size of the silicon powder is 2-10 μm.

3. A method for manufacturing a lightweight ceramic bearing, used to manufacture the ceramic bearing according to any one of claims 1-2, characterized in that: The following steps are involved: S1. Hyperbranched polycarbosilane, divinylbenzene, and xylene are mixed by a combination of wet dispersion and dry mixing to prepare a liquid precursor mixture; S2. Prepare a fiber preform by taking carbon fibers and using a three-dimensional braiding machine with a circular braiding or spiral winding process, in an orthogonal braiding or multi-angle laying manner; S3, taking the bearing ring mold and trimming the fiber preform according to the mold size; S4, placing the fiber preform into a bearing ring mold, filling the mold with phenolic resin, and heating the mold to obtain a C / C composite material blank; S5, placing the C / C composite body in a vacuum pressure impregnation furnace, impregnating the liquid precursor mixture into the C / C composite body, and then placing the impregnated C / C composite body in a vacuum induction ultrahigh temperature sintering furnace for siliconization; S6, repeat S5, every time S5 is repeated three times, a high temperature pore opening and graphitization treatment of 1800°C for 3 to 6 hours is performed, and S5 is repeated 11 to 14 times in total to obtain a bearing ring; S7. The inner ring and outer ring are obtained through S1-S6. After grinding the inner ring and outer ring, the inner ring, outer ring, ceramic balls and retaining frame are assembled.

4. The method for manufacturing a lightweight ceramic bearing according to claim 3, characterized in that: In S1, the hyperbranched polycarbosilane and divinylbenzene are prepared in a mass ratio of 59-62%, 20-24%, and 15-18% by weight. The hyperbranched polycarbosilane and divinylbenzene are first dissolved in xylene as a solvent and wet-mixed. The xylene is then evaporated and dry-mixed without a solvent to obtain a liquid precursor mixture.

5. The method for manufacturing a lightweight ceramic bearing according to claim 3, characterized in that: In S2, the volume of the carbon fibers in the fiber preform is 30%-32% of the entire volume of the fiber preform.

6. The method for manufacturing a lightweight ceramic bearing according to claim 3, characterized in that: In S4, the heating process is as follows: the temperature inside the mold is raised to 80°C at a temperature rise rate of 1.5°C / min, and then maintained at 80°C for 60 minutes; then the temperature inside the mold is raised to 120°C at a temperature rise rate of 1°C / min, and maintained at a pressure of 2-5 MPa for 30 minutes; then the temperature inside the mold is further raised to 150°C at a temperature rise rate of 1°C / min, and maintained at a pressure of 20 MPa for 30 minutes to obtain a C / C composite material green body.

7. The method for manufacturing a lightweight ceramic bearing according to claim 3, characterized in that: In S5, the siliconizing temperature during the siliconizing process is 1700°C, the siliconizing holding time is 30 minutes, and the vacuum degree is 50Pa.

8. The method for manufacturing a lightweight ceramic bearing according to claim 7, characterized in that: During the siliconization process, silicon powder is melted and infiltrated into the C / C composite body as a supplementary silicon source for the reaction of hyperbranched polycarbosilane to form a SiC matrix.

9. The method for manufacturing a lightweight ceramic bearing according to claim 3, characterized in that: In S6, the pyrolytic carbon in the material is reconstructed through high-temperature pore opening treatment, so that the closed pores are transformed into open pores.

10. The method for manufacturing a lightweight ceramic bearing according to claim 3, characterized in that: In S7, CBN grinding wheels are used to grind the end faces of the bearing rings, and brown corundum grinding wheels are used to grind the inner and outer diameters of the bearing rings; cold assembly is used for the inner and outer rings, ceramic balls and cages.

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