Carbon / carbon plate and preparation method thereof

Abstract

The invention provides a carbon / carbon plate and a preparation method thereof. The preparation method comprises the following steps: shearing leftover materials of a carbon fiber preform to obtain sheared fibers; the length of the cut fibers is 20 mm to 30 mm; mixing the shear fibers with a resin solution to obtain a mixture; carrying out mold pressing treatment on the mixture to obtain a preformed green body; the density of the preformed green body is 0.8 g / cm < 3 > to 0.9 g / cm < 3 >; and sequentially carrying out resin transfer molding forming treatment and carbonization treatment on the preformed green body to obtain the carbon / carbon plate. The carbon / carbon plate prepared through the method has the advantages of being high in bending strength, small in porosity, large in density and the like, and the recycling rate of the carbon fiber preform leftover materials is increased.

Description

Technical Field

[0001] The present application relates to the technical field of carbon composite materials, and in particular to a carbon / carbon sheet and a preparation method thereof. Background Art

[0002] Carbon / carbon sheets are mainly used to manufacture thermal field components in photovoltaic thermal field systems, such as thermal field components of single crystal furnaces. These components include lower insulation cover, insulation tube support ring, plate guard, fasteners, etc., which play a vital role in the single crystal growth process. The high strength and high temperature resistance of carbon / carbon sheets ensure the stability and durability of components in high temperature environments, thereby improving the quality and efficiency of single crystal growth.

[0003] Traditional technology records that waste carbon powder generated during the production of carbon fiber composite materials is used to prepare carbon / carbon plates, so as to make full use of carbon powder waste and reduce the company's production costs; however, the final carbon / carbon plates have low strength and are prone to deformation and corrosion when applied to photovoltaic thermal fields, resulting in a reduced service life.

[0004] Therefore, it is necessary to further improve the traditional carbon / carbon sheet. Summary of the invention

[0005] Based on this, one or more embodiments of the present application provide a carbon / carbon sheet having high bending strength, low porosity and high density and a method for preparing the same.

[0006] According to a first aspect of the present application, a method for preparing a carbon / carbon sheet is provided, comprising the following steps:

[0007] The carbon fiber preform leftovers are sheared to obtain sheared fibers; the length of the sheared fibers is 20 mm to 30 mm;

[0008] mixing the sheared fibers with a resin solution to obtain a mixture;

[0009] The mixture is subjected to a molding process to obtain a preformed body; the density of the preformed body is 0.8 g / cm3 to 0.9 g / cm3;

[0010] The preformed body is subjected to resin transfer molding treatment and carbonization treatment in sequence to obtain a carbon / carbon plate.

[0011] In some embodiments, the resin solution includes 2 wt % to 3 wt % of phenolic resin and 97 wt % to 98 wt % of solvent.

[0012] In some embodiments, the phenolic resin includes an alcohol-soluble boron phenolic resin.

[0013] In some embodiments, the viscosity of the phenolic resin is 200 mPa·s to 300 mPa·s.

[0014] In some of the embodiments, the mass ratio of the sheared fibers to the resin solution is 2:(7-9).

[0015] In some embodiments, the temperature of the molding treatment is 70° C. to 90° C., and the time is 1 h to 2 h.

[0016] In some embodiments, the carbonization treatment is carried out at a temperature of 1000° C. to 1050° C. and for a time of 2 h to 4 h.

[0017] In some embodiments, the resin transfer molding process comprises the following steps:

[0018] Preheating the resin and the preform respectively;

[0019] Under vacuum conditions with a vacuum degree greater than -0.095 MPa, the preformed body is pressurized and infused with the resin to obtain an impregnated body;

[0020] The infiltrate is cured and formed.

[0021] In some embodiments, the preparation method satisfies at least one of the following characteristics:

[0022] (1) The preheating temperature of the resin is 80°C to 90°C;

[0023] (2) The preheating temperature of the preformed body is 80°C to 90°C;

[0024] (3) The curing temperature is 170°C to 190°C, and the curing time is 1.5h to 2.5h.

[0025] According to a second aspect of the present application, a carbon / carbon plate is provided, which is prepared by the method for preparing the carbon / carbon plate according to any one of claims 1 to 9.

[0026] Compared with the traditional technology, this application has the following beneficial effects:

[0027] The present application performs shearing on the leftovers of carbon fiber preforms, and mixes the obtained sheared fibers with a length of 20 mm to 30 mm with a resin solution. After the sheared fibers of the above lengths are mixed, a complex and tightly interwoven structure is formed, and the gaps between the fibers are small; after the sheared fibers are mixed with the resin solution, a molding process is performed to make the density of the preformed body within a specific range, so that after the preformed body is molded and carbonized, a carbon / carbon sheet with high bending strength, low porosity and high density can be obtained. At the same time, the present application improves the recycling rate of the leftovers of carbon fiber preforms. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present application, etc. can be purchased from the market or can be prepared by existing methods.

[0030] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0031] In the present application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical distribution is considered continuous within the above numerical interval, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical range, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints. In this article, it is equivalent to directly listing each integer, such as t is an integer selected from 1-10, indicating that t is any integer selected from the integer group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges included therein.

[0032] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0033] In traditional technology, waste carbon powder generated during the production of carbon fiber composite materials is mixed with chopped fibers and phenolic resin powder, and then hot-pressed to produce carbon / carbon sheets. The length of the chopped fibers is only 2mm~3mm, which makes it difficult to form an interwoven structure. The gaps between the fibers are large and the connectivity is poor, and the powdered resin is difficult to evenly penetrate and fill these gaps, so the porosity of the carbon / carbon sheet is large. In addition, the specific surface area of ​​the short fibers is relatively small, and the adsorption and fixation ability of the resin material is also weak, which makes it easy for the resin to detach from the pores during subsequent processing due to shrinkage and other reasons after filling the pores, causing the pores to reappear.

[0034] Based on this, some embodiments of the present application provide a method for preparing a carbon / carbon sheet, including S10 to S40.

[0035] S10: shearing the leftovers of the carbon fiber preform to obtain sheared fibers; the length of the sheared fibers is 20 mm to 30 mm;

[0036] S20: mixing the sheared fibers with a resin solution to obtain a mixture;

[0037] S30: The mixture is subjected to compression molding to obtain a preformed body; the density of the preformed body is 0.8 g / cm 3 ~0.9g / cm 3 ;

[0038] S40: performing resin transfer molding and carbonization treatment on the preformed body in sequence to obtain a carbon / carbon sheet.

[0039] As an example, the length of the cut fiber can be 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, or any value within the range formed by any two of the above point values.

[0040] Further, the length of the cut fiber is 25 mm to 30 mm. Further, the length of the cut fiber is 25 mm to 28 mm.

[0041] After mixing, the sheared fibers of the above lengths can form a complex and tightly interwoven structure with small gaps between the fibers, which can provide better adsorption and penetration channels for the impregnated material, and help the impregnated material to fill the pores evenly. At the same time, the long fibers have a large specific surface area and have a good adsorption effect on the resin material, which can make the resin material more firmly attached to the fiber surface and fill the pores. In this way, in the subsequent curing process, the impregnated material is less likely to be separated due to shrinkage and other reasons.

[0042] As an example, the density of the preform may be 0.8 g / cm 3、0.81g / cm 3 , 0.82g / cm 3 , 0.83g / cm 3 、0.84g / cm 3 , 0.85g / cm 3 , 0.86g / cm 3 , 0.87g / cm 3 , 0.88g / cm 3 , 0.89g / cm 3 , 0.9g / cm 3 , or any value within the range formed by any two of the above point values.

[0043] Furthermore, the density of the preform is 0.85 g / cm 3 ~0.9g / cm 3 .

[0044] In some embodiments, the molding process includes the following steps: placing the mixture into a molding die for molding, and fixing the molding height. It can be understood that the density of the preform can be changed by controlling the total mass of the mixture placed in the molding die and limiting the total height of the mold so that the total volume remains unchanged.

[0045] It can be understood that controlling the density of the preform within the above range allows the shear fibers to be closely arranged, thereby improving the bending strength of the carbon / carbon sheet; at the same time, the porosity of the preform can be moderate, which facilitates the resin impregnation of the sheet in the subsequent molding process and improves the uniformity of the impregnation; and can reduce the stratification of the resin and the preform during the curing shrinkage process.

[0046] With the increasing application of products such as carbon / carbon crucibles in photovoltaic thermal fields, more and more scraps are produced in the preform stage. At present, the processing methods of carbon fiber preform scraps include crushing, chemical treatment, pyrolysis, incineration and recycling, etc., but the above-mentioned processing technology has a low reuse rate for carbon fiber and serious waste of resources. The present application uses the above-mentioned carbon fiber preform scraps to prepare carbon / carbon plates, which, on the one hand, realizes the rational use of resources and, on the other hand, reduces the production cost of carbon / carbon plates.

[0047] In some of the embodiments, in S10, a carbon fiber cutting machine is used to shear the carbon fiber.

[0048] In some embodiments, in S20, the resin solution includes 2 wt% to 3 wt% of phenolic resin and 96 wt% to 98 wt% of solvent. Further, the resin solution includes 2.5 wt% of phenolic resin and 97.5 wt% of solvent.

[0049] It should be noted that less resin solution is required to prepare the preform; however, the sheared fiber structure is fluffy, and a small amount of resin cannot be evenly dispersed in the sheared fiber, so a solvent is used to dissolve the resin so that it can completely impregnate the sheared fiber.

[0050] In some embodiments, the solvent includes alcohol; further, the mass concentration of the alcohol is ≥95%.

[0051] In some embodiments, the phenolic resin comprises an alcohol soluble boron phenolic resin.

[0052] In the present application, the alcohol-soluble boron phenolic resin refers to a boron-modified phenolic resin that is soluble in alcohol solvents. The alcohol-soluble boron phenolic resin of the present application can be selected from TA-04 produced by Shengquan Group.

[0053] Compared with other phenolic resins, the carbon / carbon sheet prepared by the alcohol-soluble boron phenolic resin in the present application has better heat resistance, instantaneous high temperature resistance and mechanical properties.

[0054] In some embodiments, the viscosity of the phenolic resin is 200 mPa·s to 300 mPa·s.

[0055] As an example, the viscosity of the phenolic resin can be 200mPa·s, 205mPa·s, 210mPa·s, 215mPa·s, 220mPa·s, 225mPa·s, 230mPa·s, 235mPa·s, 240mPa·s, 245mPa·s, 250mPa·s, 255mPa·s, 260mPa·s, 265mPa·s, 270mPa·s, 275mPa·s, 280mPa·s, 285mPa·s, 290mPa·s, 295mPa·s, 300mPa·s, or any value within the range formed by any two of the above point values.

[0056] In some embodiments, in S20, the mass ratio of the sheared fibers to the resin solution is 2:(7-9).

[0057] As an example, the mass ratio of sheared fiber to resin solution can be 2:7, 2:7.1, 2:7.2, 2:7.3, 2:7.4, 2:7.5, 2:7.6, 2:7.7, 2:7.8, 2:7.9, 2:8, 2:8.1, 2:8.2, 2:8.3, 2:8.4, 2:8.5, 2:8.6, 2:8.7, 2:8.8, 2:8.9, 2:9, or any value within the range formed by any two of the above ratios.

[0058] Furthermore, the mass ratio of the sheared fibers to the resin solution was 2:8.

[0059] Understandably, if the amount of the resin solution added is too little, the preform may not be formed due to insufficient amount of solution.

[0060] In some embodiments, in S30, the temperature of the molding treatment is 70° C. to 90° C., and the time is 1 h to 2 h.

[0061] As an example, the temperature of the molding process can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, or any value within the range formed by any two of the above point values.

[0062] Furthermore, the temperature of the molding process is 80°C.

[0063] As an example, the time of the molding treatment can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, or any value within the range formed by any two of the above point values.

[0064] Furthermore, the molding treatment time is 2 hours.

[0065] In some embodiments, in S40, the temperature of the carbonization treatment is 1000° C. to 1050° C., and the time is 2 h to 4 h.

[0066] As an example, the temperature of the carbonization treatment can be 1000°C, 1005°C, 1010°C, 1015°C, 1020°C, 1025°C, 1030°C, 1035°C, 1040°C, 1045°C, 1050°C, or any value within the range formed by any two of the above point values.

[0067] As an example, the time of carbonization treatment can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h, 4h, or any value within the range formed by any two of the above point values.

[0068] In some embodiments, the resin transfer molding process in S40 includes S41 to S43.

[0069] S41: preheating the resin and the preform respectively;

[0070] S42: Under vacuum conditions with a vacuum degree greater than -0.095 MPa, the preformed body is pressurized and infused with resin to obtain an impregnated body;

[0071] S43: Curing and molding the infiltrate.

[0072] In some embodiments, the preheating temperature of the resin in S41 is 80°C~90°C; as an example, the preheating temperature of the resin solution can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, or any value within the range formed by any two of the above point values.

[0073] In some embodiments, the type of resin in S41 is the same as the type of resin contained in the resin solution. Further, the resin in S41 includes phenolic resin. Further, the phenolic resin includes alcohol-soluble boron phenolic resin. Further, the viscosity of the phenolic resin is 200mPa·s to 300mPa·s.

[0074] It should be noted that the resin in S41 is pure resin that is not mixed with a solvent.

[0075] In some embodiments, the preheating temperature of the preform in S41 is 80°C~90°C; as an example, the preheating temperature of the preform can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, or any value within the range formed by any two of the above point values.

[0076] In some embodiments, the vacuum degree in S42 is greater than -0.095 MPa. It can be understood that the above specific vacuum conditions are more conducive to the resin being infiltrated into the preform.

[0077] It can be understood that in S42, the preheated preformed body is infiltrated with the preheated resin solution;

[0078] In some embodiments, the curing temperature in S43 is 170° C. to 190° C., and the curing time is 1.5 h to 2.5 h.

[0079] As an example, the curing temperature can be 170°C, 171°C, 172°C, 173°C, 174°C, 175°C, 176°C, 177°C, 178°C, 179°C, 180°C, 181°C, 182°C, 183°C, 184°C, 185°C, 186°C, 187°C, 188°C, 189°C, 190°C, or any value within the range formed by any two of the above point values.

[0080] Furthermore, the curing temperature is 180°C to 190°C.

[0081] As an example, the curing time can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, or any value within the range formed by any two of the above point values.

[0082] Furthermore, the curing time is 2h~2.5h.

[0083] Understandably, resin transfer molding (RTM process) enables the resin to fully infiltrate the preformed body, thereby obtaining a carbon / carbon sheet with low porosity and high strength. In addition, the molding cycle of the RTM process is relatively short. Once the mold is ready, the resin injection and curing process can be completed in a short time, which can achieve mass production and improve production efficiency.

[0084] The carbon / carbon sheet prepared by the above method of the present application has the advantages of high bending strength, small porosity and high density; and the above preparation method has the advantages of fast and high efficiency.

[0085] Some embodiments of the present application also provide a carbon / carbon plate material, which is prepared using the above-mentioned carbon / carbon plate material preparation method.

[0086] The carbon / carbon sheet material can be used to prepare lower insulation covers, insulation tube support rings, plate retaining sheets and fasteners of photovoltaic thermal field systems, and can also be used to prepare heating elements, load-bearing components and the like of photovoltaic equipment.

[0087] The present application will be further described below in conjunction with specific examples and comparative examples, but they should not be construed as limiting the scope of protection of the present application. The raw materials involved in the following specific examples, unless otherwise specified, can all be sourced from commercial sources, the instruments used, unless otherwise specified, can all be sourced from commercial sources, and the processes involved, unless otherwise specified, are all conventionally selected by those skilled in the art.

[0088] Example 1

[0089] (1) Use a carbon fiber cutting machine to break up the carbon fiber preform scraps into shear fibers with a length of 20 mm.

[0090] (2) An alcohol-soluble boron phenolic liquid resin (Shengquan Group, TA-04) with a viscosity of 240 mPa·s was mixed with 95 wt % of alcohol in a mass ratio of 2.5:97.5 to obtain a resin solution.

[0091] (3) The sheared fibers in step (1) and the resin solution in step (2) are mixed evenly in a mass ratio of 2:8, and the mixture is placed in a molding die for molding. The pressing height is fixed, and the press is heated to 80°C and kept warm for 1 hour to obtain a preformed embryo. The density of the preformed embryo is 0.8 g / cm3 .

[0092] (4) The preform obtained in step (3) is placed in a mold for resin transfer molding, wherein the height of the mold cavity in the mold is the same as that of the molding mold in step (3). The mold is fastened with bolts and completely sealed, and then a resin transfer molding process is performed, which specifically includes the following steps:

[0093] (a) Add alcohol-soluble boron phenolic liquid resin with a viscosity of 240 mPa·s into a resin tank and preheat it to 85°C;

[0094] (b) preheating the mold containing the preformed embryo to 85° C.

[0095] (c) Connect the resin tank to the mold, close the valve of the resin inlet pipe to the mold, and start the vacuum pump at the same time to degas the mold system. The vacuum degree must reach above -0.095Mpa and be maintained for 30 minutes. Check that the vacuum degree does not drop by more than 0.005Mpa. Open the valve of the resin inlet pipe to the mold, use the vacuum pump and pressure tank to pour into the mold, and maintain the pressure of the pressure tank at 1MPa~3MPa. Maintain the temperature of the resin tank and RTM mold between 80℃~90℃; after a certain resin outlet has discharged resin, close the valve of the resin outlet pipe connected to it, and perform the same operation on other resin outlets until all resin outlets have finished discharging glue;

[0096] (d) After all resin outlets have discharged resin, turn off the vacuum pump and continue to pump in the resin for 30 minutes while maintaining the injection pressure;

[0097] (e) Turn on the vacuum pump, connect all the resin outlet pipes to it, start draining the resin, keep the pressure of the pressure tank at 1MPa~3MPa, and drain the resin for 30 minutes;

[0098] (f) After the resin is discharged, block all resin outlets again and turn off the vacuum pump. Maintain the pressure of the pressure tank at 3MPa~4Mpa for 30 minutes;

[0099] (g) Block the resin inlet pipeline, close the pressure tank valve, and open the resin tank pressure relief valve.

[0100] (h) disconnecting the resin tank from the RTM mold;

[0101] (i) The RTM mold was heated to 180°C and kept at this temperature for 2 h for curing.

[0102] (5) The plate formed by the resin transfer molding in step (4) is subjected to carbonization treatment at a carbonization temperature of 1050° C. for 2 h to obtain a carbon / carbon plate.

[0103] The bending strength of the carbon / carbon sheet was tested according to the national standard GBT40398.2-2021 "Test Methods for Carbon-Carbon Composite Carbon Materials", and the porosity and density of the carbon / carbon sheet were tested. The porosity of the carbon / carbon sheet prepared in Example 1 was 14% and the density was 1.35 g / cm 3 , the bending strength is 200Mpa.

[0104] Example 2

[0105] The method is basically the same as Example 1, except that the density of the preform is different. Specifically, Example 2 changes the mass of the mixture put into the mold so that the density of the preform is 0.85 g / cm 3 .

[0106] Finally, the porosity of the carbon / carbon sheet obtained in Example 2 was 13.5% and the density was 1.37 g / cm 3 , the bending strength is 205Mpa.

[0107] Example 3

[0108] The method is basically the same as Example 1, except that the density of the preform is different. Specifically, Example 3 changes the mass of the mixture put into the mold so that the density of the preform is 0.9 g / cm 3 .

[0109] Finally, the porosity of the carbon / carbon sheet obtained in Example 3 was 12.7% and the density was 1.38 g / cm 3 , the bending strength is 205Mpa.

[0110] Example 4

[0111] It is basically the same as Example 1, except that the length of the cut fibers is different. Specifically, the length of the cut fibers in Example 4 is 25 mm.

[0112] Finally, the porosity of the carbon / carbon sheet obtained in Example 4 was 13.8% and the density was 1.34 g / cm 3 , the bending strength is 210Mpa.

[0113] Example 5

[0114] The method is basically the same as Example 1, except that the length of the cut fiber and the density of the preform are different. Specifically, the length of the cut fiber in Example 5 is 25 mm, and the density of the preform is 0.85 g / cm 3 .

[0115] Finally, the porosity of the carbon / carbon sheet obtained in Example 5 was 13.3% and the density was 1.37 g / cm3 , the bending strength is 218Mpa.

[0116] Example 6

[0117] The method is basically the same as Example 1, except that the length of the cut fibers and the density of the preform are different. Specifically, in Example 6, the length of the cut fibers is 25 mm, and the density of the preform is 0.9 g / cm 3 .

[0118] Finally, the porosity of the carbon / carbon sheet obtained in Example 6 was 13.5% and the density was 1.36 g / cm 3 , the bending strength is 225Mpa.

[0119] Example 7

[0120] It is basically the same as Example 1, except that the length of the cut fibers is different. Specifically, the length of the cut fibers in Example 7 is 30 mm.

[0121] Finally, the porosity of the carbon / carbon sheet obtained in Example 7 was 14.1% and the density was 1.32 g / cm 3 , the bending strength is 214Mpa.

[0122] Example 8

[0123] The method is basically the same as Example 1, except that the length of the cut fibers and the density of the preform are different. Specifically, in Example 8, the length of the cut fibers is 30 mm, and the density of the preform is 0.85 g / cm 3 .

[0124] Finally, the porosity of the carbon / carbon sheet obtained in Example 8 was 13.7% and the density was 1.34 g / cm 3 , the bending strength is 228Mpa.

[0125] Example 9

[0126] The method is basically the same as Example 1, except that the length of the cut fibers and the density of the preform are different. Specifically, in Example 9, the length of the cut fibers is 30 mm, and the density of the preform is 0.9 g / cm 3 .

[0127] Finally, the porosity of the carbon / carbon sheet obtained in Example 9 was 13.7% and the density was 1.35 g / cm 3 , the bending strength is 230Mpa.

[0128] Example 10

[0129] It is basically the same as Example 1, except that the type of phenolic resin is different; in Example 10, the alcohol-soluble boron phenolic liquid resin is replaced by a thermosetting phenolic resin in equal amounts.

[0130] Finally, the porosity of the carbon / carbon sheet obtained in Example 10 was 14.2% and the density was 1.36 g / cm 3 , the bending strength is 190Mpa.

[0131] Comparative Example 1

[0132] The method is basically the same as Example 1, except that the density of the preform is different. Specifically, in Comparative Example 1, the mass of the mixture put into the mold is changed to make the density of the preform to be 0.7 g / cm 3 .

[0133] Finally, the porosity of the carbon / carbon sheet prepared in Comparative Example 1 was 14.9% and the density was 1.35 g / cm 3 , the bending strength is 182Mpa.

[0134] Comparative Example 2

[0135] The method is basically the same as Example 1, except that the length of the cut fibers is different. In Comparative Example 2, the length of the cut fibers is 10 mm.

[0136] Finally, the porosity of the carbon / carbon sheet obtained in Comparative Example 2 was 13% and the density was 1.33 g / cm 3 , the bending strength is 160Mpa.

[0137] Comparative Example 3

[0138] The method is basically the same as Example 1, except that: step (3) does not include the step of placing the mixture into a molding die for molding, but directly placing the mixture into a numerical transfer molding die. However, the mixture cannot be formed during the preparation process, and a carbon / carbon sheet cannot be obtained.

[0139] The length of the cut fibers, the density of the preforms, and the performance parameters of the carbon / carbon sheets in the above Examples 1 to 10 and Comparative Examples 1 to 2 are shown in the following table.

[0140] Table 1

[0141]

[0142] As can be seen from the table above, the density of the preform in Comparative Example 1 is only 0.7 g / cm 3The bending strength of the plate obtained by molding and carbonizing the blank is significantly reduced, and the porosity is large. In Comparative Example 2, the length of the sheared fiber is only 10 mm, and the porosity of the plate obtained by molding and carbonizing the blank is small, but the bending strength is low. In Comparative Example 3, the mixture is not molded, the mixture cannot be molded, and the plate cannot be obtained.

[0143] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0144] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a carbon / carbon sheet, characterized in that: The steps include: The carbon fiber preform leftovers are sheared to obtain sheared fibers; the length of the sheared fibers is 20 mm to 30 mm; mixing the sheared fibers with a resin solution to obtain a mixture; The mixture is subjected to compression molding to obtain a preformed body; the density of the preformed body is 0.8 g / cm 3 ~0.9g / cm 3 ; The preformed body is subjected to resin transfer molding treatment and carbonization treatment in sequence to obtain a carbon / carbon plate.

2. The method for preparing the carbon / carbon sheet according to claim 1, characterized in that: The resin solution includes 2wt% to 3wt% of phenolic resin and 97wt% to 98wt% of solvent.

3. The method for preparing the carbon / carbon sheet according to claim 2, characterized in that: The phenolic resin includes alcohol-soluble boron phenolic resin.

4. The method for preparing the carbon / carbon sheet according to claim 2, characterized in that: The viscosity of the phenolic resin is 200mPa·s to 300mPa·s.

5. The method for preparing the carbon / carbon sheet according to any one of claims 1 to 4, characterized in that: The mass ratio of the sheared fibers to the resin solution is 2:(7-9).

6. The method for preparing the carbon / carbon sheet according to any one of claims 1 to 4, characterized in that: The temperature of the molding treatment is 70° C. to 90° C., and the time is 1 h to 2 h.

7. The method for preparing the carbon / carbon sheet according to any one of claims 1 to 4, characterized in that: The temperature of the carbonization treatment is 1000° C. to 1050° C., and the time is 2 h to 4 h.

8. The method for preparing the carbon / carbon sheet according to any one of claims 1 to 4, characterized in that: The resin transfer molding process comprises the following steps: Preheating the resin and the preform respectively; Under vacuum conditions with a vacuum degree greater than -0.095 MPa, the preformed body is pressurized and infused with the resin to obtain an impregnated body; The infiltrate is cured and formed.

9. The method for preparing the carbon / carbon sheet according to claim 8, characterized in that: The preparation method meets at least one of the following characteristics: (1) The preheating temperature of the resin is 80°C to 90°C; (2) The preheating temperature of the preformed body is 80°C to 90°C; (3) The curing temperature is 170°C to 190°C, and the curing time is 1.5h to 2.5h.

10. A carbon / carbon sheet, characterized in that: The carbon / carbon sheet is prepared by the method for preparing the carbon / carbon sheet according to any one of claims 1 to 9.

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