Anti-cracking carbon / carbon plate and preparation method thereof

Abstract

The invention provides an anti-cracking carbon / carbon plate and a preparation method thereof. Comprising the following steps: sequentially carrying out spraying treatment, hot-pressing curing and carbonization treatment on a carbon fiber prepreg to obtain a carbon / carbon plate; sequentially carrying out dipping curing and carbonization treatment on the carbon / carbon plate to obtain an anti-cracking carbon / carbon plate; the spraying treatment comprises the following steps: uniformly spraying a carbon nanotube ethanol solution on the surface of the carbon fiber prepreg, and standing until the ethanol solution on the surface of the carbon fiber prepreg is volatilized; the carbon nanotube ethanol solution is prepared by dispersing an ethanol solvent and carbon nanotubes; the mass ratio of ethanol in the carbon nanotube ethanol solution to resin in the carbon fiber prepreg is 5: 1; the mass ratio of the carbon nano tube in the carbon nano tube ethanol solution to the resin in the carbon fiber prepreg is (0.01-0.08): 1.

Description

Technical Field

[0001] The present application belongs to the technical field of carbon fiber material forming process, and relates to an anti-cracking carbon / carbon plate and a preparation method thereof. Background Art

[0002] Carbon / carbon sheets have the characteristics of light weight, high strength, good fatigue resistance, good vibration attenuation, no creep, low friction coefficient, good thermal conductivity, corrosion resistance, radio wave shielding, small thermal expansion coefficient, etc. They are widely used in aerospace, mobile shelters, biomedicine, industrial equipment parts, sporting goods and other fields. Lightweight, high-strength and high-temperature resistant carbon / carbon sheets are usually made of basic carbon fiber materials through needle punching, CVD deposition or liquid phase impregnation carbonization.

[0003] The liquid phase impregnation process is a commonly used densification process technology for carbon / carbon sheets. The liquid phase impregnation method is used to prepare C / C sheets, which usually includes the steps of impregnation of hot-pressed carbon sheets and high-temperature carbonization. During the impregnation process, the hot-pressed carbon sheets are embedded in asphalt or resin liquid and loaded into a pressurized impregnation device. The resin is impregnated and infiltrated into the interior of the hot-pressed sheets at a certain temperature and pressure to fill the pores. In the high-temperature carbonization step, the carbon sheet removed from the impregnation liquid is loaded into a vacuum furnace for high-temperature carbonization treatment to remove non-carbon atoms such as hydrogen, nitrogen, and oxygen, leaving pure carbon, completing a cycle of densification treatment for the carbon / carbon sheet. This process is repeated for multiple cycles until the carbon / carbon sheet reaches the required density.

[0004] However, during the high-temperature carbonization process, the impregnation liquid decomposes non-carbon atoms such as hydrogen, oxygen, and nitrogen at high temperature to produce a large amount of volatiles. The volume of the matrix shrinks greatly, and a large number of pores and voids are generated. The density of the prepared board tends to decrease. Even during the carbonization process, non-carbon atoms produce a large amount of volatiles that do not have time to dissipate, which can cause cracks between the carbon / carbon board layers. Summary of the invention

[0005] To solve at least one of the technical problems raised in the background technology, an embodiment of the present application provides an anti-cracking carbon / carbon plate and a preparation method thereof.

[0006] A method for preparing a crack-resistant carbon / carbon sheet material comprises the following steps: The carbon fiber prepreg is subjected to spraying treatment, hot pressing curing and carbonization treatment in sequence to obtain a carbon / carbon sheet; the carbon / carbon sheet is subjected to impregnation curing and carbonization treatment in sequence to obtain an anti-cracking carbon / carbon sheet; The spray treatment comprises: spraying the carbon nanotube ethanol solution uniformly on the surface of the carbon fiber prepreg, and then standing until the ethanol solution on the surface of the carbon fiber prepreg evaporates; The carbon nanotube ethanol solution is prepared by dispersing ethanol solvent and carbon nanotubes; The mass of ethanol in the carbon nanotube ethanol solution: the mass of resin in the carbon fiber prepreg is 5:1; The mass of carbon nanotubes in the carbon nanotube ethanol solution: the mass of resin in the carbon fiber prepreg is (0.01-0.08):1.

[0007] In one possible embodiment, the preparation method of the anti-cracking carbon / carbon plate material provided in the embodiment of the present application, the hot pressing curing includes: placing the carbon fiber prepreg into a hot pressing device, and under a pressure of 1 MPa, heating the temperature from room temperature to 80°C at a heating rate of 3°C / min, and keeping it warm for 1 hour; then under a pressure of 2 MPa, heating the temperature from 80°C to 120°C at a heating rate of 3°C / min, and keeping it warm for 2 hours; then under a pressure of 2 MPa, heating the temperature from 120°C to 160°C at a heating rate of 3°C / min, keeping it warm for 1 hour, and then naturally cooling it to room temperature.

[0008] In one possible embodiment, the preparation method of the anti-cracking carbon / carbon plate provided in the embodiment of the present application, the impregnation and curing includes: using an impregnation liquid to embed the carbon / carbon plate, setting the pressure to 2MPa and the temperature to room temperature under vacuum conditions, and performing an impregnation treatment for 2 hours; then taking the carbon / carbon plate out of the impregnation liquid, setting the pressure to 2MPa under vacuum conditions, raising the temperature from room temperature to 120°C within 1 hour, and keeping it warm for 0.5 hours; then raising the temperature to 140°C within 0.5 hours, and keeping it warm for 0.5 hours; then raising the temperature to 160°C within 0.5 hours, and keeping it warm for 0.5 hours; then raising the temperature to 180°C within 0.5 hours, keeping it warm for 2 hours for curing, and then naturally cooling to room temperature.

[0009] In one possible implementation manner, in the method for preparing anti-cracking carbon / carbon sheet provided in an embodiment of the present application, the impregnating liquid is furfural resin glue, and the furfural resin glue is prepared by mixing furfural resin and curing agent in a mass ratio of 100:0.4.

[0010] In one possible implementation manner, the method for preparing the anti-cracking carbon / carbon plate provided in the embodiment of the present application, the carbonization treatment comprises: heating to 900°C at a heating rate of 30°C / h~90°C / h in a vacuum furnace at room temperature, and then cooling naturally.

[0011] In one possible implementation manner, in the method for preparing the anti-cracking carbon / carbon sheet provided in the embodiment of the present application, the viscosity of the furfural resin is 40-100 mpa·s (25° C.) and the solid content is 75%.

[0012] In one possible implementation manner, in the method for preparing the anti-cracking carbon / carbon sheet provided in the embodiment of the present application, the process of sequentially performing impregnation curing and carbonization treatment on the carbon / carbon sheet is repeated multiple times.

[0013] In one possible implementation manner, in the method for preparing the anti-cracking carbon / carbon sheet material provided in the embodiment of the present application, the carbon fiber prepreg is a 12K plain weave carbon fiber prepreg, and the resin in the carbon fiber prepreg is a phenolic resin.

[0014] In one possible implementation, the method for preparing the anti-cracking carbon / carbon sheet material provided in the embodiment of the present application, the density of the carbon nanotubes is 2.1 g / cm 3 .

[0015] An anti-cracking carbon / carbon plate is prepared by the above preparation method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The carbon fiber preform surface is sprayed with an ethanol solution containing carbon nanotubes, and after standing and volatilizing, the carbon nanotubes are evenly dispersed on the surface of the carbon fiber prepreg, effectively improving the interfacial bonding between the carbon fiber prepregs; in the carbonization stage, the internal bonding force of the resin glue is effectively enhanced; and at the interface between the carbon fiber and the resin glue, it can play a certain "anchoring" role, making the carbon plate less likely to delaminate and crack during the carbonization stage, reducing the production time cost; In addition, the addition of nano-scale carbon nanotubes fills the gaps and voids between carbon plates during the carbonization process, which increases the residual carbon rate of carbon / carbon plates after high-temperature sintering and improves the overall density. The interlayer bonding of the treated carbon / carbon plates is improved; at the same time, the pores and voids of the carbon / carbon plates are significantly reduced, and their density is enhanced. DETAILED DESCRIPTION

[0017] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0018] The present application provides a method for preparing a crack-resistant carbon / carbon plate, comprising the following steps: First, the carbon fiber prepreg is subjected to spray treatment, hot pressing curing and carbonization treatment in sequence to obtain a carbon / carbon sheet; then, the carbon / carbon sheet is subjected to impregnation curing and carbonization treatment in sequence (impregnation curing and carbonization treatment are performed once or repeatedly) to obtain an anti-cracking carbon / carbon sheet, wherein: Spray treatment: After the carbon nanotube ethanol solution is evenly sprayed on the surface of the carbon fiber prepreg, it is allowed to stand until the ethanol solution on the surface of the carbon fiber prepreg evaporates, generally for 1 hour (25°C).

[0019] Specifically, the carbon nanotube ethanol solution is prepared by dispersing the carbon nanotubes with an ethanol solvent. The mass of ethanol in the carbon nanotube ethanol solution: the mass of the resin in the carbon fiber prepreg is 5:1. The mass of the carbon nanotubes in the carbon nanotube ethanol solution: the mass of the resin in the carbon fiber prepreg is (0.01-0.08):1.

[0020] Hot pressing curing: Place the carbon fiber prepreg in a hot pressing device, and under a pressure of 1Mpa, increase the temperature from room temperature to 80°C at a heating rate of 3°C / min, and keep it warm for 1 hour; then under a pressure of 2Mpa, increase the temperature from 80°C to 120°C at a heating rate of 3°C / min, and keep it warm for 2 hours; then under a pressure of 2Mpa, increase the temperature from 120°C to 160°C at a heating rate of 3°C / min, keep it warm for 1 hour, and then naturally cool it to room temperature.

[0021] Impregnation curing: The carbon / carbon sheet is embedded with an impregnation liquid, and the pressure is set to 2MPa and the temperature is room temperature under vacuum conditions for 2 hours of impregnation treatment; then the carbon / carbon sheet is taken out of the impregnation liquid, and the pressure is set to 2MPa under vacuum conditions, and the temperature is raised from room temperature to 120°C within 1 hour, and kept warm for 0.5 hours; then the temperature is raised to 140°C within 0.5 hours, and kept warm for 0.5 hours; then the temperature is raised to 160°C within 0.5 hours, and kept warm for 0.5 hours; then the temperature is raised to 180°C within 0.5 hours, and kept warm for 2 hours for curing, and then naturally cooled to room temperature. The impregnation liquid is furfural resin glue, and the furfural resin glue is prepared by mixing furfural resin and curing agent in a mass ratio of 100:0.4.

[0022] Carbonization treatment: In a vacuum furnace, at room temperature, the temperature is increased to 900°C at a rate of 30°C / h~90°C / h, and then naturally cooled.

[0023] Among the materials used above, carbon nanotubes are nanometer-sized with a density of 2.1 g / cm 3 ; The purity of ethanol solvent is 95%; the viscosity of furfural resin used for impregnation and curing is 40~100mpa·s (25℃), and the solid content is 75%; the carbon fiber prepreg is 12K plain phenolic resin carbon fiber with a surface density of 400g / cm 2 The above materials are all commercially available.

[0024] The embodiment of the present application uses a spraying method to treat the surface of the carbon fiber prepreg. Carbon nanotubes are added to an ethanol solution and sprayed onto the surface of the carbon fiber prepreg. After standing, the ethanol evaporates, so that the carbon nanotubes are evenly dispersed on the surface of the carbon fiber preform. The high specific surface area and high activation of carbon nanotubes can be evenly dispersed in the resin matrix to effectively adsorb the matrix molecular chains, form physical cross-linking points, and effectively enhance the internal binding force of the resin glue.

[0025] Moreover, at the interface between carbon fiber and resin glue, these physical cross-linking points can play a certain "anchoring" role, effectively improving the interfacial bonding performance between carbon fiber prepregs, making it difficult for carbon plates to delaminate and crack during the carbonization stage, and reducing production time costs. Similarly, the addition of nano-scale carbon nanotubes, while producing the same effect, increases the residual carbon rate of carbon / carbon plates after high-temperature sintering and improves the overall density.

[0026] The following is a further detailed description of the technical solution of the present invention in conjunction with the specific implementation modes: Example

[0027] A method for preparing a crack-resistant carbon / carbon plate comprises: firstly subjecting a carbon fiber preform to hot pressing curing and carbonization treatment to obtain a carbon / carbon plate, and then subjecting a carbon fiber preform to impregnation curing treatment and carbonization treatment.

[0028] The above-mentioned hot pressing curing process includes: under a pressure of 1MPa, the temperature is increased from room temperature to 80°C at a heating rate of 3°C / min, and kept warm for 1 hour; then under a pressure of 2Mpa, the temperature is increased from 80°C to 120°C at a heating rate of 3°C / min, and kept warm for 2 hours; then under a pressure of 2Mpa, the temperature is increased from 120°C to 160°C at a heating rate of 3°C / min, kept warm for 1 hour, and then naturally cooled to room temperature.

[0029] The above-mentioned impregnation curing treatment includes: using furfural resin glue (prepared by taking furfural resin and curing agent in a mass ratio of 100:0.4) to embed the carbon / carbon sheet, and setting the pressure to 2MPa, the temperature to room temperature, and the time for impregnation treatment under vacuum conditions for 2 hours. The carbon / carbon sheet is taken out of the impregnation liquid, and under vacuum conditions, the pressure is set to 2MPa, and the temperature is raised from room temperature to 120°C within 1 hour, and kept warm for 0.5h; then the temperature is raised to 140°C within 0.5h, and kept warm for 0.5h; then the temperature is raised to 160°C within 0.5h, and kept warm for 0.5h; then the temperature is raised to 180°C within 0.5h, and kept warm for 2h for curing, and then naturally cooled to room temperature.

[0030] The carbonization treatment process includes: under vacuum furnace conditions, heating the temperature from 25°C to 450°C at a heating rate of 25°C / h, and keeping the temperature constant for 3 hours; then heating the temperature to 600°C at a heating rate of 30°C / h, and keeping the temperature constant for 3 hours; then heating the temperature to 900°C at a heating rate of 40°C / h, and keeping the temperature constant for 1 hour; finally, naturally cooling to room temperature.

[0031] The complete treatment cycle is composed of impregnation curing and carbonization treatment. After the carbonization step, the next treatment cycle begins, and the impregnation is performed again through the impregnation step. This treatment is repeated 5 times. Example

[0032] A method for preparing a crack-resistant carbon / carbon sheet material, which is different from that of Example 1 in that: The carbonization treatment process includes: under vacuum furnace conditions, the temperature is increased from 25°C to 450°C at a heating rate of 50°C / h, and the temperature is kept constant for 1 hour; then the temperature is increased to 600°C at a heating rate of 50°C / h, and the temperature is kept constant for 1 hour; then the temperature is increased to 900°C at a heating rate of 50°C / h, and the temperature is kept constant for 1 hour; finally, the temperature is naturally cooled to room temperature.

[0033] It should be noted that the hot pressing curing process is the same as that in Example 1, and the number of complete treatment cycles of the impregnation curing treatment and the carbonization treatment is the same as that in Example 1. Example

[0034] A method for preparing a crack-resistant carbon / carbon sheet material, which is different from Example 2 in that: First, the carbon fiber prepreg is sprayed.

[0035] The spraying treatment process includes: weighing the ethanol solvent, the mass of ethanol: the mass of phenolic resin in the carbon fiber prepreg = 5:1. Weighing the carbon nanotubes, the mass of carbon nanotubes: the mass of phenolic resin in the carbon fiber prepreg = 0.02:1. Dispersing the ethanol solvent and the carbon nanotubes to obtain a carbon nanotube ethanol solution. Then, the carbon nanotube ethanol solution is evenly sprayed on the surface of the carbon fiber prepreg, and then left to stand at room temperature for one hour to volatilize the ethanol solvent, and then hot pressing curing, impregnation curing and carbonization treatment are performed.

[0036] It should be noted that the hot pressing curing process is the same as that in Example 2, the carbonization process is the same as that in Example 2, and the number of complete treatment cycles of the impregnation curing treatment and the carbonization treatment is the same as that in Example 2. Example

[0037] A method for preparing a crack-resistant carbon / carbon sheet material, which is different from that of Example 3 in that: In the spray treatment solution, the mass of carbon nanotubes is carbon nanotubes: the mass of phenolic resin in the carbon fiber prepreg = 0.05:1.

[0038] It should be noted that the hot pressing curing process is the same as that in Example 3, the carbonization process is the same as that in Example 3, and the number of complete treatment cycles of the impregnation curing treatment and the carbonization treatment is the same as that in Example 3. Example

[0039] A method for preparing a crack-resistant carbon / carbon sheet material, which is different from that of Example 3 in that: In the spray treatment solution, the content of carbon nanotubes is the mass of carbon nanotubes: the mass of phenolic resin in the carbon fiber prepreg = 0.08:1.

[0040] It should be noted that the hot pressing curing process is the same as that in Example 3, the carbonization process is the same as that in Example 3, and the number of complete treatment cycles of the impregnation curing treatment and the carbonization treatment is the same as that in Example 3. The carbon / carbon plates treated by the methods provided in Examples 1 to 5 were analyzed by macroscopic observation to observe the interlayer cracking of the carbon / carbon plates after carbonization.

[0041] Density was determined using the Archimedean method.

[0042] The above test analysis was performed on the carbon fiber preforms treated by the methods provided in Examples 1 to 5, and the results are shown in Table 1: Table 1 Results of Examples 1 to 5 sample Interlayer cracking Density after 5 treatment cycles Example 1 No cracking between layers <![CDATA[1.54g / cm 3 ]]> Example 2 Complete cracking between layers after hot pressing and carbonization Example 3 Partial cracking between layers after hot pressing and carbonization Example 4 No cracking between layers <![CDATA[1.65g / cm 3 ]]> Example 5 A small amount of cracking between layers after hot pressing and carbonization From the analysis of Table 1, it can be seen that after the carbon fiber preform is treated by the carbonization treatment method provided in Example 1, the prepared carbon / carbon sheet does not have interlayer cracking. However, after the same treatment method as Example 1 is used and only the carbonization treatment time is reduced, the carbon / carbon sheet obtained in Example 2 completely cracks between the layers. When the carbon fiber preform is sprayed with an ethanol solution with a lower carbon nanotube concentration, the carbon / carbon sheet obtained in Example 3 partially cracks between the layers under the carbonization treatment conditions of Example 2, indicating that the carbon nanotube powder has a positive effect on preventing interlayer cracking. Increasing the concentration of carbon nanotube powder, the carbon / carbon sheet obtained in Example 4 under reduced carbonization treatment conditions does not have interlayer cracking. When the concentration of carbon nanotubes is high, the carbon / carbon sheet obtained in Example 5 partially cracks, indicating that the carbon nanotube content increases, affecting the adhesion between the resins. It can be seen from the analysis of Examples 1 to 5 that the uniform doping of an appropriate amount of carbon nanotube powder is conducive to preventing interlayer cracking of the carbon / carbon sheet, effectively reducing the production time of the carbon / carbon sheet, and reducing production costs. Meanwhile, by comparing Examples 1 and 4, it is found that the addition of carbon nanotubes fills the gaps and holes generated in the carbon / carbon sheet during the carbonization process, thereby increasing the density of the carbon sheet.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, rather than to limit it. Although the present application has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solution described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. These modifications or replacements are within the scope of protection of the present invention.

Claims

1. A method for preparing a crack-resistant carbon / carbon sheet, characterized in that: These include: The carbon fiber prepreg is subjected to spraying treatment, hot pressing curing and carbonization treatment in sequence to obtain a carbon / carbon sheet; the carbon / carbon sheet is subjected to impregnation curing and carbonization treatment in sequence to obtain an anti-cracking carbon / carbon sheet; The spray treatment comprises: spraying the carbon nanotube ethanol solution uniformly on the surface of the carbon fiber prepreg, and then standing until the ethanol solution on the surface of the carbon fiber prepreg evaporates; The carbon nanotube ethanol solution is prepared by dispersing ethanol solvent and carbon nanotubes; The mass of ethanol in the carbon nanotube ethanol solution: the mass of resin in the carbon fiber prepreg is 5:1; The mass of carbon nanotubes in the carbon nanotube ethanol solution: the mass of resin in the carbon fiber prepreg is (0.01-0.08):

1.

2. The method for preparing the anti-cracking carbon / carbon sheet according to claim 1, characterized in that: The hot pressing curing comprises: placing the carbon fiber prepreg into a hot pressing device, and under a pressure of 1 MPa, heating the temperature from room temperature to 80°C at a heating rate of 3°C / min, and keeping the temperature for 1 hour; then, under a pressure of 2 MPa, heating the temperature from 80°C to 120°C at a heating rate of 3°C / min, and keeping the temperature for 2 hours; then, under a pressure of 2 MPa, heating the temperature from 120°C to 160°C at a heating rate of 3°C / min, keeping the temperature for 1 hour, and then naturally cooling to room temperature.

3. The method for preparing the anti-cracking carbon / carbon sheet according to claim 2, characterized in that: The impregnation curing comprises: using an impregnation liquid to bury the carbon / carbon plate, setting the pressure to 2MPa and the temperature to room temperature under vacuum conditions, and performing an impregnation treatment for 2 hours; then taking the carbon / carbon plate out of the impregnation liquid, setting the pressure to 2MPa under vacuum conditions, raising the temperature from room temperature to 120°C within 1 hour, and keeping it warm for 0.5 hours; then raising the temperature to 140°C within 0.5 hours, and keeping it warm for 0.5 hours; then raising the temperature to 160°C within 0.5 hours, and keeping it warm for 0.5 hours; then raising the temperature to 180°C within 0.5 hours, keeping it warm for 2 hours for curing, and then naturally cooling down to room temperature.

4. The method for preparing the anti-cracking carbon / carbon sheet according to claim 3, characterized in that: The impregnation liquid is furfural resin glue, and the furfural resin glue is prepared by mixing furfural resin and curing agent in a mass ratio of 100:0.

4.

5. The method for preparing the anti-cracking carbon / carbon sheet according to claim 3, characterized in that: The carbonization treatment comprises: heating the temperature in a vacuum furnace at room temperature at a rate of 30°C / h to 90°C / h to 900°C, and then cooling the temperature naturally.

6. The method for preparing the anti-cracking carbon / carbon sheet according to claim 4, characterized in that: The furfural resin has a viscosity of 40-100 mpa·s (25° C.) and a solid content of 75%.

7. The method for preparing the anti-cracking carbon / carbon sheet according to any one of claims 1 to 6, characterized in that: The process of sequentially performing impregnation, curing and carbonization treatment on the carbon / carbon plate is repeated multiple times.

8. The method for preparing the anti-cracking carbon / carbon sheet according to any one of claims 1 to 6, characterized in that: The carbon fiber prepreg is a 12K plain weave carbon fiber prepreg, and the resin in the carbon fiber prepreg is a phenolic resin.

9. The method for preparing the anti-cracking carbon / carbon sheet according to any one of claims 1 to 6, characterized in that: The density of the carbon nanotubes is 2.1 g / cm 3 .

10. A crack-resistant carbon / carbon sheet, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.