An antioxidant carbon-carbon material and a method for preparing the same

Abstract

The present application relates to a kind of anti-oxidation carbon-carbon material and its preparation method, carbon fiber preform is pretreated, then is immersed in mother liquor, and is carried out vacuum impregnation;After impregnation mother liquor, spin dry is placed in impregnation liquid and is impregnated;After impregnation, it is taken out and is solidified, carbonized;Impregnation-solidification-carbonization is repeated until the density of carbon fiber preform reaches the requirement, then is graphitized.The present application utilizes inorganic oxide reinforcement, and is impregnated by liquid phase impregnation method, and can quickly obtain oxidation-resistant carbon-carbon material, simultaneously has the advantages such as high density, high safety factor, simple operation, no harmful pollution by-products, etc., is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, and specifically relates to an antioxidant carbon material and its preparation method. Background Technology

[0002] Carbon / carbon composites are carbon matrix composites reinforced with carbon fibers and their fabrics. They have a low density (<2.0 g / cm³). 3 With its advantages of high strength, high specific modulus, high thermal conductivity, low coefficient of expansion, good friction performance, good thermal shock resistance, and high dimensional stability, it is one of the few alternative materials for applications above 1600℃, with a maximum theoretical temperature as high as 2600℃. Therefore, it is considered one of the most promising high-temperature materials and has been widely used in aerospace, automotive industry, medical and other fields, such as rocket engine nozzles and throat liners, space shuttle nose caps and wing leading edge thermal protection systems, braking devices, etc.

[0003] Because the main component of the material is elemental carbon, which oxidizes at temperatures exceeding 500 degrees Celsius (the exact rate varies slightly depending on the oxygen content and the type of carbon), carbon-carbon materials differ from metallic materials. Metals, even after rusting, do not lose strength within a certain range and do not require immediate replacement. However, carbon-carbon materials are different; oxidation destroys their fibrous structure, causing a sharp drop in strength. Furthermore, unlike the rusting of metals, oxidation spreads rapidly after it occurs, ultimately leading to a loss of structural strength. For example, carbon ceramic discs used in supercars and racing cars, despite having stronger oxidation resistance than carbon-carbon materials, can still be damaged under continuous high temperatures and intense friction. According to the Aston Martin team, when the disc loses approximately 1.15% of its weight, its strength is insufficient for use, necessitating replacement.

[0004] For the reasons mentioned above, although carbon / carbon composite materials exhibit many excellent properties in high-temperature environments, their high-temperature oxidation has always been a limitation that cannot be ignored, especially for carbon materials used in oxidizing atmospheres, which leads to a sharp decline in their performance. Poor oxidation resistance has always restricted the further development of their application range, and their high melting point and high strength characteristics cannot be effectively utilized. Corresponding oxidation protection measures must be taken.

[0005] Currently, silicon carbide is a common antioxidant coating material, exhibiting good physicochemical compatibility with carbon-carbon composite matrices and effectively isolating oxygen from direct contact with the matrix. However, a single silicon carbide coating is prone to peeling and lacks sufficient airtightness, failing to provide long-term effective protection for carbon-carbon composites. For example, CN108530110A involves preparing a SiC layer via chemical vapor deposition followed by plasma spraying of a ceramic coating. CN118164785A and CN115784760A similarly involve first forming a SiC inner coating on the C / C sample surface before preparing the antioxidant layer. Existing technologies are complex and inefficient, thus necessitating the development of a preparation method to improve the antioxidant properties of carbon-carbon materials. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing antioxidant carbon materials, which rapidly produces the desired carbon materials while achieving the objective in a safe and environmentally friendly manner.

[0007] A method for preparing an antioxidant carbon fiber material includes the following steps: pretreating a carbon fiber preform, then immersing it in a mother liquor and performing vacuum impregnation; removing the carbon fiber preform, removing excess mother liquor, and then impregnating it in an impregnation solution; removing it after impregnation and then curing and carbonizing it; repeating the impregnation-curing-carbonization process until the density of the carbon fiber preform reaches the required level, followed by graphitization treatment. The mother liquor is composed of a mixture of polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silicon powder, and polyacrylic acid resin solution; the impregnation solution is composed of a mixture of magnesium oxide, zinc oxide, zirconium oxide, boron trioxide, polyvinyl alcohol, and cellulose solution. Preferably, the vacuum impregnation time in the mother liquor is 30 minutes; each impregnation in the impregnation solution lasts 20-30 seconds.

[0008] Carbon fiber preforms are obtained by weaving or needle punching carbon fibers and then shaping them.

[0009] Further, the mass ratio of polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silica powder, and polyacrylic acid resin in the mother liquor is 10:(0.8~1.1):(4.5~5.5):(4.5~5.5):(2.5~3.5):10. Preferably, the mass ratio of the components in the mother liquor is 10:1:5:5:3:10. In some preferred embodiments, the viscosity of the polyether-modified silicone oil is 500cs-1500cs; the polyacrylic acid resin solution is water-soluble with a viscosity of 7000cps.

[0010] Furthermore, the ratio of magnesium oxide, zinc oxide, zirconium oxide, boron trioxide, polyvinyl alcohol, and cellulose solution added to the impregnation solution is (4.5~5.5):(2.4~3.6):(1.8~2.2):(5.4~6.6):2:60. Preferably, the ratio of each component is 5:3:2:6:2:60. The cellulose is modified cellulose, including at least one of hydroxypropyl methylcellulose, water-soluble cellulose acetate, and hydroxyethyl cellulose. In some preferred embodiments, the mass concentration of the cellulose solution is 45%.

[0011] In some preferred embodiments, the pretreatment includes a degreasing process and an activation process; the degreasing process removes organic matter from the surface of the preform by high temperature or washing; the activation process involves placing the degreased preform in a plasma cleaner and cleaning it for 5 to 10 minutes.

[0012] Furthermore, the curing temperature is 150℃~180℃, and the curing time is 1~2 hours; the carbonization temperature is 1200℃~1300℃, and the carbonization time is 6~8 hours; the graphitization temperature is 1800℃~2000℃, and the graphitization time is 4~8 hours.

[0013] The present invention also discloses an antioxidant coating for carbon-carbon materials prepared by the above method.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] Compared to traditional carbon-carbon materials, the carbon-carbon materials prepared by the method of this invention have inherent anti-oxidation capabilities upon completion of preparation, eliminating the need for further anti-oxidation treatment, saving time, and without affecting the original strength of the carbon material, thus saving a significant amount of cost; however, the material is damaged during use.

[0016] The main raw materials in this method are metal oxides and cellulose, which are safer and cleaner than conventional methods using petroleum coke, asphalt, or natural gas using the CVI method. No toxic or harmful substances are produced during the production process, and all raw materials are non-toxic and harmless, making it more suitable for environmentally sensitive areas.

[0017] This method can quickly produce the desired carbon-carbon materials, effectively solving the drawbacks of existing methods for preparing carbon-carbon material products, expanding the application scale of the products, and reducing production costs. Attached Figure Description

[0018] Figure 1 This is a photograph of the sample after preparation.

[0019] Figure 2 for Figure 1 A photograph of the sample after the oxidation test.

[0020] Figure 3This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0021] The invention is illustrated through specific examples to provide a thorough understanding of the invention. However, the invention can be practiced in many ways other than those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The test materials used in this invention are all commercially available products.

[0022] In carbon-carbon composite materials, the meaning of "carbon" comes from two aspects: first, the carbon element contained in the preform itself, and second, the carbon transferred in through gaseous or liquid substances.

[0023] This invention provides a method for preparing an antioxidant carbon-based material, comprising the following steps: Weaving or needle-punching carbon fibers to obtain a preform according to the desired shape; degreasing the preform by high temperature or washing to remove organic matter from its surface; placing the degreased preform in a plasma cleaner for activation for 5-10 minutes; immersing the preform in a mother liquor and vacuum impregnating it to ensure the mother liquor fully wets the preform; removing the preform after full impregnation and centrifuging to remove excess mother liquor; immersing the preform in an impregnation solution; removing the preform after impregnation and curing it at 150℃-180℃; and carbonizing the cured preform in a rare gas protected high-temperature furnace at 1200℃-1300℃. The carbonization process converts cellulose into residual carbon and promotes chemical reactions between the inorganic components, completing sintering and achieving the protective purpose. After carbonization, the density of the preform is checked, and the impregnation-curing-carbonization process is repeated until the density is ≥2.0 g / cm³. 3 The preform, having reached the required density, is graphitized at 1800℃~2000℃. Graphitization improves the material's thermal stability and converts excess silicon into silicon carbide, further enhancing the product's oxidation resistance. After graphitization, the white crystals on the surface are removed using a metal brush to obtain the finished product.

[0024] In some preferred embodiments, the mother liquor comprises polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silica powder, and polyacrylic acid resin solution. The components are weighed and mixed sequentially in a weight ratio of 10:(0.8~1.1):(4.5~5.5):(4.5~5.5):(2.5~3.5):10 to prepare the mother liquor. Preferably, the weight ratio of polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silica powder, and polyacrylic acid resin in the mother liquor is 10:1:5:5:3:10. In some preferred embodiments, the viscosity of the polyether-modified silicone oil is 500 cs-1500 cs; the polyacrylic acid resin solution is water-soluble with a viscosity of 7000 cs.

[0025] In some preferred embodiments, the impregnation solution is prepared by adding magnesium oxide, zinc oxide, zirconium oxide, boron trioxide and polyvinyl alcohol to a cellulose solution.

[0026] Magnesium oxide, zinc oxide, zirconium oxide, boron trioxide, polyvinyl alcohol, and cellulose solution are added in a weight ratio of (4.5~5.5):(2.4~3.6):(1.8~2.2):(5.4~6.6):2:60. The preferred mass ratio of each component is 5:3:2:6:2:60. The cellulose solution is a modified cellulose solution, including at least one of hydroxypropyl methylcellulose, water-soluble cellulose acetate, and hydroxyethyl cellulose. Preferably, the mass concentration of the cellulose solution is 45%.

[0027] The main purpose of removing organic material from the surface of the preform is to increase the bonding force between the mother liquor and the fiber used subsequently, preventing the fiber from separating from the coating slurry during sintering and causing failure. During the preparation, weaving, and needle-punching of carbon fibers, contamination occurs, with a small amount of organic matter adhering to the fiber. This prevents the mother liquor from fully contacting the fiber, and the organic matter volatilizes during sintering, leaving pores.

[0028] The following embodiments will help researchers in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0029] Unless otherwise specified, the following test equipment is general-purpose and will not affect the final result.

[0030] Example 1

[0031] The materials and reagents used are as follows: carbon fiber preform (Ф400*35), polyether-modified silicone oil, iron oxide (AR), aluminum oxide (AR), titanium dioxide (AR), silica powder (AR), polyacrylic acid resin solution, magnesium oxide (AR), zinc oxide (AR), zirconium oxide (AR), boron trioxide (AR), polyvinyl alcohol (AR), and hydroxypropyl methylcellulose. The implementation steps are as follows:

[0032] 1. Use isopropanol to remove organic matter from the surface of the carbon fiber preform. After degreasing, place it in a plasma cleaner and clean for 5-10 minutes.

[0033] 2. Weigh out polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silicon powder, and polyacrylic acid resin solution in a weight ratio of 10:1:5:5:3:10, and mix them to prepare a mother liquor. Immerse the carbon fiber preform in the mother liquor, apply a vacuum until it is less than 5000 Pa, and immerse for 30 minutes. After the time is up, remove the carbon fiber preform and spin dry.

[0034] 3. Weigh magnesium oxide, zinc oxide, zirconium oxide, boron trioxide, polyvinyl alcohol, and cellulose solution according to a weight ratio of 5:3:2:6:2:60, and mix them to prepare an impregnation solution. Immerse the carbon fiber preform treated in step 2 in the impregnation solution for 20-30 seconds. After impregnation, remove the preform and cure it at 150℃-180℃ for 1-2 hours. Place the cured preform in a high-temperature furnace at 1200℃-1300℃ for carbonization for 6-8 hours.

[0035] 4. Repeat the impregnation-curing-carbonization process until the desired density is achieved, for example, density ≥ 2.0 g / cm³. 3 The carbonized preform is then graphitized at 1800℃~2000℃ for 4~8 hours.

[0036] After the process is completed, the sample is removed and its performance is tested.

[0037] After testing, the density of the precast body was found to be 0.45 g / cm³. 3 Increased to 1.88 g / cm³ 3 The sample surface is grayish-black and hard; after cutting, it can be observed that the entire sample has a dense structure, without defects or voids; the carbon fibers and pyrolytic carbon are firmly bonded, and under a microscope, fine crystal structures can be seen to be evenly distributed inside the sample, providing protection for the sample.

[0038] Comparative Example 1

[0039] Following the scheme of Example 1, three pieces of antioxidant carbon-carbon material were prepared (Table 1, Serial Numbers 1-3). Simultaneously, six other pieces of the same carbon-carbon material were taken, three of which were coated with a commercially available borate-based antioxidant coating (Table 1, Serial Numbers 4-6), and the other three were left untreated as a control group (Table 1, Serial Numbers 7-9). The nine samples were weighed and placed in a muffle furnace for calcination at 700°C for 8 hours. After calcination, the residual weight was measured again, and the residual weight percentage was calculated.

[0040] After experiments, the residual weight of the anti-oxidation carbon materials (items 1-3) was approximately 98%; the residual weight of the carbon materials with the anti-oxidation coating (items 4-6) was approximately 85%; the control group was completely pulverized and could not be measured. This demonstrates that the carbon materials prepared by this method can significantly reduce the erosion of carbon materials by oxidation and extend their service life.

[0041] Table 1 Comparison Results of Examples

[0042]

[0043] Comparative Example 2 differs from Example 1 in that it was not impregnated with mother liquor.

[0044] The materials and reagents used are as follows: carbon fiber preform (Ф30*20), magnesium oxide (AR), zinc oxide (AR), zirconium oxide (AR), boron trioxide (AR), polyvinyl alcohol (AR), and hydroxypropyl methylcellulose. The implementation steps are as follows:

[0045] 1. Use isopropanol to remove organic matter from the surface of the carbon fiber preform. After degreasing, place it in a plasma cleaner and clean for 5-10 minutes.

[0046] 2. Weigh magnesium oxide, zinc oxide, zirconium oxide, boron trioxide, polyvinyl alcohol, and cellulose solution according to a mass ratio of 5:3:2:6:2:60, and mix them to prepare an impregnation solution; place the carbon fiber preform into the impregnation solution for impregnation.

[0047] 3. After impregnation, remove the preform and cure it at 150℃~180℃ for 1~2 hours. Place the cured preform in a high-temperature furnace at 1200℃~1300℃ for carbonization for 6~8 hours. Repeat the impregnation-curing-carbonization process until the density is ≥2.0 g / cm³. 3 The carbonized preform is then graphitized at 1800℃~2000℃ for 4~8 hours. After the process is completed, the sample is removed.

[0048] 4. After weighing, place it in a muffle furnace and calcine it at 700℃ for 8 hours. After calcination, measure the residual weight again and calculate the residual weight rate.

[0049] After antioxidant testing, its weight decreased from 26.4g to 22.99g, with a residual weight rate of approximately 87%. Without the mother liquor, its protective ability would be significantly affected, and it is not much different from conventional antioxidant coatings.

[0050] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art, such as changes in parameters such as reaction temperature, vaporization temperature, and gas flow rate, should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for preparing an antioxidant carbon material, characterized in that, Includes the following steps: After pretreatment, the carbon fiber preform is immersed in the mother liquor and then vacuum impregnated. After soaking in the mother liquor, spin dry and then place in the soaking solution for soaking; After impregnation, the carbon fiber preform is removed and cured and carbonized; the impregnation-curing-carbonization process is repeated until the density of the carbon fiber preform reaches the required level, after which it is graphitized. The mother liquor is prepared by mixing polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silicon powder, and polyacrylic acid resin solution, with the weight ratio of each component in the mother liquor being 10:(0.8~1.1):(4.5~5.5):(4.5~5.5):(2.5~3.5):10; the impregnation solution is prepared by mixing magnesium oxide, zinc oxide, zirconium oxide, boron oxide, polyvinyl alcohol, and cellulose solution, with the weight ratio of each component in the impregnation solution being (4.5~5.5):(2.4~3.6):(1.8~2.2):(5.4~6.6):2:

60.

2. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The viscosity of the polyether-modified silicone oil is 500cs-1500cs.

3. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The polyacrylic acid resin solution is water-soluble and has a viscosity of 7000 cps.

4. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The cellulose solution has a mass concentration of 45% and includes at least one of hydroxypropyl methylcellulose, water-soluble cellulose acetate, and hydroxyethyl cellulose.

5. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The weight ratio of polyether-modified silicone oil, iron oxide, aluminum oxide, titanium dioxide, silicon powder, and polyacrylic acid resin in the mother liquor is 10:1:5:5:3:

10.

6. The method for preparing an antioxidant carbon material according to claim 4, characterized in that, The weight ratio of magnesium oxide, zinc oxide, zirconium oxide, boron trioxide, polyvinyl alcohol, and cellulose solution added to the impregnation solution is 5:3:2:6:2:

60.

7. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The pretreatment includes a degreasing process and an activation process; the degreasing process removes organic matter from the surface of the preform by high temperature or washing; the activation process involves placing the degreased preform in a plasma cleaner and cleaning it for 5 to 10 minutes.

8. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The curing temperature is 150℃~180℃, and the curing time is 1~2 hours; the carbonization temperature is 1200℃~1300℃, and the carbonization time is 6~8 hours; the graphitization temperature is 1800℃~2000℃, and the graphitization time is 4~8 hours.

9. The method for preparing an antioxidant carbon material according to claim 1, characterized in that, The vacuum impregnation time is 30 minutes; each impregnation in the impregnation solution lasts for 20 to 30 seconds.

10. An antioxidant carbon material prepared by the method according to any one of claims 1 to 9.

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