A CMC heat-resistant sleeve and a preparation method thereof

Abstract

This invention relates to the field of high-temperature protective materials technology, specifically to a CMC heat-resistant sleeve and its preparation method. The preparation method includes the following steps: S1; impregnating a ceramic-based composite fiber cloth in a sol of nano-ceramic particles to obtain a composite fiber cloth; S2: impregnating the composite fiber cloth with a silicone slurry, and after initial curing, coating the surface of the composite fiber cloth with the silicone slurry, followed by secondary curing, and then hot-pressing two composite fiber cloths together to obtain a CMC composite fiber cloth. The CMC heat-resistant sleeve is then prepared using this CMC composite fiber cloth. This preparation method uses a sol-gel method combined with a high-temperature in-situ sintering process to prepare the composite fiber cloth, then impregnates and coats it with a silicone slurry, and finally hot-presses and stacks them together to obtain the CMC heat-resistant sleeve. Its high-temperature resistance range reaches 1100~1400℃, it can withstand molten metal splashes for short periods, has excellent wear resistance, a long service life, maintains overall flexibility, is easy to install and disassemble, and is adaptable to different pipe diameters and bending parts.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protective materials technology, specifically to a CMC heat-resistant jacket and its preparation method. Background Technology

[0002] In high-temperature industrial environments such as steel mills and smelters, molten metal and its splashes generate thermal radiation and impacts exceeding 1000°C, leading to frequent damage to nearby cables (such as water-cooled cables), oil pipes, and electrical equipment. Existing technologies typically use aramid fibers, silicone, or high-silica glass fiber cloth to prepare heat-resistant sleeves for cables, oil pipes, or electrical equipment. For example, CN209591626U discloses a silicone high-temperature cable, using silicone as the heat-resistant sleeve for the cable. However, while high-silica glass fiber cloth is heat-resistant, it has poor abrasion resistance; aramid cloth or silicone, while abrasion-resistant, lacks sufficient high-temperature resistance (usually below 500°C). A single material cannot meet the long-term requirements of heat-resistant sleeves under the combined effects of high temperature and friction, resulting in short equipment lifespan, high maintenance costs, and significant safety hazards. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a CMC heat-resistant sleeve and its preparation method, which has both high temperature resistance and wear resistance.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing a CMC (ceramic matrix composite) heat-resistant jacket, comprising the following steps: S1; The ceramic-based composite fiber cloth is impregnated in a sol of nano-ceramic particles, and then subjected to heating, curing and sintering in sequence to obtain the composite fiber cloth; S2: The composite fiber cloth is impregnated with silicone slurry. After initial curing, silicone slurry is coated on the surface of the composite fiber cloth. After secondary curing, the two composite fiber cloths are stacked and hot-pressed to obtain CMC composite fiber cloth. CMC heat-resistant sleeve is prepared using CMC composite fiber cloth.

[0005] Another technical solution adopted in this invention is: a CMC heat-resistant jacket prepared by the above-mentioned CMC heat-resistant jacket preparation method.

[0006] The beneficial effects of this invention are as follows: The preparation method of this invention adopts a sol-gel method combined with a high-temperature in-situ sintering process to form a nano-scale ceramic composite coating on the surface of a traditional high-silica fiber cloth, which has low thermal conductivity, high fire resistance, and high wear resistance. Then, silicone slurry is impregnated on the composite fiber cloth and coated to form an integrated flexible sheet, which allows the silicone slurry to fully bond with the ceramic-based composite fiber cloth, improving the overall material's resistance to delamination and shearing, reducing the surface friction coefficient, and improving its waterproof, anti-oxidation, and anti-metal splashing capabilities. Finally, the two composite fiber cloths are stacked and hot-pressed to obtain a CMC composite fiber cloth. A CMC heat-resistant sleeve is prepared using the CMC composite fiber cloth. The CMC heat-resistant sleeve of this invention has a high temperature resistance range of 1100~1400℃, can withstand molten metal splashes for short periods, has excellent wear resistance, a long service life, maintains overall flexibility, is easy to install and disassemble, adapts to different pipe diameters and bending parts, and can be used to prepare heat-resistant sleeves. Detailed Implementation

[0007] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments.

[0008] A method for preparing a CMC heat-resistant jacket includes the following steps: S1; The ceramic-based composite fiber cloth is impregnated in a sol of nano-ceramic particles, and then subjected to heating, curing and sintering in sequence to obtain the composite fiber cloth; S2: The composite fiber cloth is impregnated with silicone slurry. After initial curing, silicone slurry is coated on the surface of the composite fiber cloth. After secondary curing, the two composite fiber cloths are stacked and hot-pressed to obtain CMC composite fiber cloth. CMC heat-resistant sleeve is prepared using CMC composite fiber cloth.

[0009] As described above, the beneficial effects of this invention are as follows: The preparation method of this invention involves impregnating a ceramic-based composite fiber cloth in a sol containing nano-ceramic particles, and then curing it through gradient heating to form a continuous ceramic film on the fiber surface. After sintering, a "fiber-ceramic" composite structure is formed, which improves the hardness and wear resistance of the fiber surface while maintaining the fiber's flexibility and high-temperature resistance. Then, silicone slurry is sequentially impregnated onto the composite fiber cloth and initially cured, allowing the silicone slurry to fully penetrate the pores and fiber bundles of the ceramic-based composite fiber cloth, forming a three-dimensional "fiber-silicone" reinforced structure. The combination of internal fibers and silicone enhances the overall material's resistance to delamination and shearing. The silicone forms a thermal buffer layer inside the fiber, delaying the direct impact of high temperatures on the fiber. Finally, silicone is coated onto the surface of the composite fiber cloth and cured, forming a dense silicone film on the surface of the ceramic-based composite fiber cloth. This reduces the surface friction coefficient, prevents fiber ends from being exposed, seals surface micropores, and improves waterproof, anti-oxidation, and anti-metal splash capabilities. Combined with the impregnation step, this achieves comprehensive improvement both internally and externally. Finally, the two composite fiber cloths are stacked and hot-pressed to obtain CMC composite fiber cloth. CMC heat-resistant sleeves are prepared using CMC composite fiber cloth. The multi-layer structure further improves high-temperature resistance and wear resistance.

[0010] When a single layer of composite fiber cloth is impregnated with silicone, the surface silicone layer is easily squeezed into the fiber interior during hot pressing, making it difficult to form a continuous surface film; moreover, the single-layer structure has limited thickness, resulting in insufficient thermal insulation performance. When two layers are stacked, the middle silicone layer fuses under hot pressing to form a continuous adhesive layer, while the outer silicone film is compressed and densed, ensuring a smooth and wear-resistant surface and improving overall thermal insulation performance. Therefore, the two-layer stack offers superior performance.

[0011] Furthermore, by mass percentage, the sol comprises the following components: 40-50% tetraethyl orthosilicate, 15-25% tetrabutyl zirconate, 5-10% silicon carbide nanoparticles, 20-30% anhydrous ethanol, 5-10% deionized water, and 1-3% silane coupling agent.

[0012] As can be seen from the above description, tetraethyl orthosilicate is the silicon source used to form the SiO2 network; tetrabutyl zirconate is the zirconium source to improve temperature resistance; silicon carbide nanoparticles enhance wear resistance; and silane coupling agents can enhance the bond between the fiber and the coating.

[0013] Furthermore, the pH value of the sol is 2-3.

[0014] As can be seen from the above description, the pH value of the sol is adjusted to 2-3 to provide suitable acidic catalytic conditions for tetraethyl orthosilicate to control its hydrolysis rate, while inhibiting the excessively rapid precipitation of tetrabutyl zirconate, thereby obtaining a composite ceramic coating with uniform composition and dense structure.

[0015] Furthermore, the ceramic-based composite fiber cloth is subjected to plasma pretreatment and coupling agent treatment in sequence, and then impregnated in a sol of nano-ceramic particles.

[0016] As can be seen from the above description, plasma pretreatment can activate the surface of ceramic matrix composite fiber cloth, introduce hydroxyl groups, and enhance the bonding force between nano-ceramic particles and ceramic matrix composite fiber cloth; coupling agent treatment can further enhance the bonding force between the two.

[0017] Furthermore, the plasma pretreatment power is 480~520W, and the time is 3~5 min.

[0018] Furthermore, the specific steps of the coupling agent treatment are as follows: the plasma-pretreated ceramic matrix composite fiber cloth is impregnated in an ethanol solution of the coupling agent.

[0019] As can be seen from the above description, the chemical bonding ability between the enhanced fiber and the silicone layer is achieved by treating the surface with a silane coupling agent.

[0020] Furthermore, the sol impregnation temperature in S1 is 20~25℃ (room temperature), and the time is 60~120 min.

[0021] As can be seen from the above description, a lower impregnation temperature prevents the sol from gelling too early, and a longer impregnation time ensures full penetration.

[0022] Furthermore, the curing process in S1 is a gradient heating process.

[0023] As can be seen from the above description, gradient heating can prevent material cracking.

[0024] Furthermore, both the S1 impregnation sol and the S2 impregnation silica gel slurry were subjected to vacuum treatment.

[0025] As can be seen from the above description, vacuum assistance can ensure complete filling of internal pores.

[0026] Furthermore, the specific steps of sintering are as follows: heating to 580~620℃ at a heating rate of 2~5℃ / min for sintering.

[0027] As can be seen from the above description, gradient heating is used for curing to avoid thermal stress; then sintering is carried out at the ceramicization temperature to form a continuous ceramic film on the fiber surface.

[0028] Furthermore, by weight, the silicone slurry comprises the following components: 100 parts methyl vinyl silicone rubber, 30-40 parts fumed silica, and 20-30 parts ceramic powder.

[0029] As can be seen from the above description, methyl vinyl silicone rubber is used as the matrix material, fumed silica is used as a reinforcing filler, and ceramic powder can improve the temperature resistance.

[0030] Furthermore, by weight, the silica gel slurry also includes the following components: 0.5 to 1 part catalyst, 2 to 3 parts crosslinking agent, 0.1 to 0.3 parts acetylene cyclohexanol inhibitor and 1 to 2 parts silane coupling agent.

[0031] As can be seen from the above description, the catalyst is used to catalyze sulfidation, the acetylene cyclohexanol inhibitor can control the sulfidation rate, and the addition of silane coupling agent enhances the fiber-silica bond.

[0032] Furthermore, the viscosity of the silica gel slurry is 3000~8000 mPa·s As described above, when the viscosity of the silica gel slurry is below 3000 mPa·s, significant slurry loss occurs after impregnation, resulting in insufficient silica gel content in the fiber cloth and a decline in the mechanical properties of the composite material. When the viscosity is above 8000 mPa·s, the slurry struggles to penetrate the fiber bundles, adhering only to the surface, leading to ineffective internal fiber coating and reduced interfacial bonding strength. Therefore, 3000–8000 mPa·s is the preferred range to ensure both effective impregnation and composite material performance.

[0033] Furthermore, the silicone coating thickness in S2 is 0.1~0.2mm.

[0034] As can be seen from the above description, if the silicone coating thickness is too thin, it is difficult to form a dense silicone film.

[0035] Furthermore, the silicone-coated composite fiber cloth in S2 can be single-sided or double-sided.

[0036] As described above, single-sided coating refers to coating only the inner surface (adhesive layer) or only the outer surface (surface layer). Coating 0.1–0.2 mm of silicone onto the inner surface (the contacting surface) of the two composite fiber cloths allows for bonding the two layers during hot pressing; coating 0.1–0.2 mm of silicone onto the outer surface (the exposed surface of the finished product) forms a dense, smooth surface film, imparting surface properties such as wear resistance, water resistance, and low friction.

[0037] "Double-sided coating" refers to coating both the inner and outer surfaces, which not only ensures the strong adhesion of the two layers of fiber cloth, but also forms a continuous and dense silicone film on the surface of the finished product.

[0038] Furthermore, the temperature of the superimposed hot pressing in S2 is 160~180℃, the pressure is 5~10 MPa, and the time is 15~20min.

[0039] As can be seen from the above description, the CMC heat-resistant jacket is formed after being stacked and hot-pressed.

[0040] Another technical solution adopted in this invention is: a CMC heat-resistant jacket prepared by the above-mentioned CMC heat-resistant jacket preparation method.

[0041] As can be seen from the above description, the CMC heat-resistant sleeve of the present invention has a high temperature resistance range of 1100~1400℃, can withstand molten metal splashes for a short period of time, has excellent wear resistance, and a long service life; it maintains overall flexibility, is easy to install and disassemble, and can be cut and sewn into a sleeve-like structure according to usage requirements to cover cables or pipelines, adapting to different pipe diameters and bending parts, and can be used to prepare heat-resistant sleeves.

[0042] Some of the raw materials used in the following examples and comparative examples are as follows: Ceramic-based composite fiber cloth: The cloth used is BWT1300-92 type ceramic-based composite fiber cloth manufactured by Changshu Yaoxing Fiberglass Insulation Products Co., Ltd., with an SiO2 content of 96%, a fiber diameter of 4μm, and a unit area mass of 1120±50 g / m². 2 Thickness 1.3mm, width 920mm; Ceramic powder: XZ-TC01-3 type high temperature resistant ceramic powder produced by Xiangzheng Chemical Technology Co., Ltd., with an average particle size of 100nm and a melting point of 2108℃; Fumed silica: SG-200 type fumed silica produced by Yichang Nanbo Silicon Materials Co., Ltd., with a specific surface area of ​​200 m². 2 / g, SiO2 content is 99.8%; Hydrogen-containing silicone oil crosslinking agent: Zew-203model2 high-hydrogen silicone oil produced by Shenzhen Zhuoerwei Technology Co., Ltd., with a hydrogen content >1.58% and a viscosity of 35 mm. 2 / s (25℃).

[0043] All materials used in the following examples and comparative examples are from the same batch from the same manufacturer. Heat-resistant sleeves were prepared by cutting and attaching Velcro in the following examples and comparative examples.

[0044] Embodiment 1 of the present invention is a method for preparing a CMC heat-resistant jacket, the specific steps of which are as follows: S1: Preparation of sol: The composition of the sol is shown in Table 1. Hydrochloric acid is added to the sol until its pH is 2. Pretreatment of ceramic matrix composite fiber cloth: plasma treatment at 500W for 4 min, then impregnation in 2wt% KH-550 ethanol solution for 10 min, and drying at 80℃; The pretreated ceramic matrix composite fibers were immersed in a sol at 23°C for 90 min. The immersed ceramic matrix composite fibers were then vacuumed at -0.08 MPa for 30 min, and then cured at 80°C for 2 h and 120°C for 1 h. The cured material was heated to 600°C at a heating rate of 3°C / min and sintered for 2 h. After naturally cooling to room temperature, the composite fiber cloth was obtained. Table 1

[0045] S2: The composite fiber cloth was impregnated with silicone slurry at 28℃ for 45 min. The composition of the silicone slurry is shown in Table 2. After impregnation, the composite fiber cloth was vacuumed at -0.08 5MPa for 20 min, and then cured at 120℃ for 30 min and 150℃ for 20 min. Next, a silicone slurry with a thickness of 0.15 mm was coated on both sides of the composite fiber cloth and cured at 120℃ for 20 min and 180℃ for 30 min. The two coated composite fiber cloths were stacked and hot-pressed at 170℃ and 8 MPa for 18 min, and then placed in an oven at 200℃ for 2 h to obtain CMC composite fiber cloth. CMC heat-resistant sleeve was prepared using CMC composite fiber cloth.

[0046] Table 2

[0047] Embodiment 2 of the present invention is a method for preparing a CMC heat-resistant jacket, the specific steps of which are as follows: S1: Preparation of sol: The composition of the sol is shown in Table 3. Hydrochloric acid was added to the sol until its pH was 2. Pretreatment of ceramic matrix composite fiber cloth: plasma treatment at 480W for 5 min, then impregnation in 2wt% KH-550 ethanol solution for 10 min, and drying at 80℃; The pretreated ceramic matrix composite fibers were immersed in a sol at 20°C for 120 min. The immersed ceramic matrix composite fibers were then vacuumed at -0.08 MPa for 30 min, and then cured at 80°C for 2 h and 120°C for 1 h. The cured material was heated to 580°C at a heating rate of 2°C / min and sintered for 2 h. After naturally cooling to room temperature, the composite fiber cloth was obtained. Table 3

[0048] S2: The composite fiber cloth was impregnated with silicone slurry at 25℃ for 60 min. The composition of the silicone slurry is shown in Table 4. After impregnation, the composite fiber cloth was vacuumed at -0.08 5MPa for 20 min, and then cured at 120℃ for 30 min and 150℃ for 20 min. Next, a silicone slurry with a thickness of 0.1 mm was coated on both sides of the composite fiber cloth and cured at 120℃ for 20 min and 180℃ for 30 min. The two coated composite fiber cloths were stacked and hot-pressed at 160℃ and 5 MPa for 20 min, and then placed in an oven at 200℃ for 2 h to obtain CMC composite fiber cloth. CMC heat-resistant sleeve was prepared using CMC composite fiber cloth.

[0049] Table 4

[0050] Embodiment 3 of the present invention is a method for preparing a CMC heat-resistant jacket, the specific steps of which are as follows: S1: Preparation of sol: The composition of the sol is shown in Table 5. Hydrochloric acid was added to the sol until its pH was 3. Pretreatment of ceramic matrix composite fiber cloth: plasma treatment at 520W for 3 min, then impregnation in 2wt% KH-550 ethanol solution for 10 min, and drying at 80℃; The pretreated ceramic matrix composite fibers were immersed in a sol at 25°C for 60 min. The immersed ceramic matrix composite fibers were then vacuumed at -0.08 MPa for 30 min, and then cured at 80°C for 2 h and 120°C for 1 h. The cured material was heated to 620°C at a heating rate of 5°C / min and sintered for 2 h. After naturally cooling to room temperature, the composite fiber cloth was obtained. Table 5

[0051] S2: The composite fiber cloth was impregnated with silicone slurry at 30℃ for 30 min. The composition of the silicone slurry is shown in Table 6. After impregnation, the composite fiber cloth was vacuumed at -0.08 5MPa for 20 min, and then cured at 120℃ for 30 min and 150℃ for 20 min. Next, a silicone slurry with a thickness of 0.2 mm was coated on one side of the composite fiber cloth and cured at 120℃ for 20 min and 180℃ for 30 min to form a silicone layer. The silicone layers of the two composite fiber cloths were brought into contact with each other and hot-pressed together at 180℃ and 10 MPa for 15 min. Then, they were placed in an oven at 200℃ for 2 h to obtain CMC composite fiber cloth. CMC heat-resistant sleeves were prepared using CMC composite fiber cloth.

[0052] Table 6

[0053] Comparative Example 1 of the present invention is: a method for preparing a heat-resistant jacket, the specific steps of which are as follows: A ceramic-based composite fiber cloth was coated with a silicone slurry with a thickness of 0.15 mm on both sides (formulation shown in Table 7), and cured at 120℃ for 20 min and 180℃ for 30 min. The two coated ceramic-based composite fiber cloths were then stacked and hot-pressed at 170℃ and 8 MPa for 18 min, and then placed in an oven at 200℃ for 2 h to obtain a composite fiber cloth. A heat-resistant jacket was prepared using the composite fiber cloth.

[0054] Table 7

[0055] Comparative Example 2 of the present invention is: a method for preparing a heat-resistant jacket, the specific steps of which are as follows: The conventional ceramic fiber cloth of Shandong Luyang Energy-Saving Materials Co., Ltd. (LYGX-208A1 type) was used as the ceramic-based composite fiber cloth (classification temperature 1260℃, SiO2 content about 50%). A silicone slurry with a thickness of 0.15mm was coated on both sides of the ceramic-based composite fiber cloth (formulation shown in Table 8). The mixture was cured at 120℃ for 20min and 180℃ for 30min. The two coated ceramic-based composite fiber cloths were then stacked and hot-pressed at 170℃ and 8 MPa for 18min, and then placed in an oven at 200℃ for 2h to obtain the composite fiber cloth. The heat-resistant sleeve was prepared using the composite fiber cloth.

[0056] Table 8

[0057] The performance of the heat-resistant sleeves of Embodiment 1 and Comparative Example 1 of the present invention was tested, and the test results are shown in Table 9; the performance of the heat-resistant sleeves of Embodiment 1 and Comparative Example 2 of the present invention was tested, and the test results are shown in Table 10.

[0058] Table 9

[0059] Table 10

[0060] The fourth embodiment of the present invention is a CMC heat-resistant jacket prepared using the preparation method of the first embodiment.

[0061] In summary, the CMC heat-resistant jacket and its preparation method provided by this invention have the following advantages: 1. Based on conventional ceramic fiber cloth, a SiC-ZrO2 nano-ceramic coating is introduced through the sol-gel method to modify the fiber surface and enhance the chemical bonding with silica gel; 2. Vacuum impregnation ensures that the silicone penetrates into the internal pores of the fiber, and the surface coating forms a tightly sealed layer, forming a dual structure of "three-dimensional composite + surface reinforcement"; 3. It simultaneously achieves properties such as 1400℃ temperature resistance, 2000-cycle wear resistance, low coefficient of friction, and excellent electrical insulation, filling the gap in the field of high-temperature wear-resistant flexible protection materials.

[0062] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made using the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a CMC heat-resistant jacket, characterized in that, Includes the following steps: S1; The ceramic-based composite fiber cloth is impregnated in a sol of nano-ceramic particles, and then subjected to heating, curing and sintering in sequence to obtain the composite fiber cloth; S2: The composite fiber cloth is impregnated with silicone slurry. After initial curing, silicone slurry is coated on the surface of the composite fiber cloth. After secondary curing, the two composite fiber cloths are stacked and hot-pressed to obtain CMC composite fiber cloth. CMC composite fiber cloth is prepared using CMC composite fiber cloth. CMC heat-resistant sleeve is prepared using CMC composite fiber cloth.

2. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The sol comprises, by weight percentage, the following components: 40-50% tetraethyl orthosilicate, 15-25% tetrabutyl zirconate, 5-10% silicon carbide nanoparticles, 20-30% anhydrous ethanol, 5-10% deionized water, and 1-3% silane coupling agent.

3. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The pH value of the sol is 2-3.

4. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The ceramic-based composite fiber cloth is subjected to plasma pretreatment and coupling agent treatment in sequence, and then impregnated in a sol of nano-ceramic particles.

5. The method for preparing the CMC heat-resistant jacket according to claim 4, characterized in that, The specific steps of the coupling agent treatment are as follows: the plasma-pretreated ceramic matrix composite fiber cloth is impregnated in an ethanol solution of the coupling agent.

6. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The specific steps of the sintering are as follows: heating to 580-620℃ at a heating rate of 2-5℃ / min for sintering.

7. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The silicone slurry comprises the following components by weight: 100 parts methyl vinyl silicone rubber, 30-40 parts fumed silica, and 20-30 parts ceramic powder.

8. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The silicone coating thickness in S2 is 0.1~0.2mm.

9. The method for preparing the CMC heat-resistant jacket according to claim 1, characterized in that, The silicone-coated composite fiber cloth in S2 can be on one or both sides.

10. A CMC heat-resistant sleeve prepared by the method of any one of claims 1-9.

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