Resin-based composite slurry, carbon-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of resin slurry, in particular to resin-based composite slurry, a carbon-based composite material and a preparation method of the carbon-based composite material. The resin-based composite slurry comprises the following components in percentage by mass: 14%-24% of graphite powder, 6%-10% of liquid resin and 70%-80% of an organic solvent, and the average particle size of the graphite powder is 80-150 meshes. The slurry disclosed by the invention can be used for a protective layer of a carbon / carbon composite material under optimized components and proportions, and the protective layer has a flat and smooth surface, does not have a chapping phenomenon, is excellent in binding force with the surface of a matrix, and can prevent fiber falling of the carbon-based composite material in a thermal field use process.

Description

Technical Field

[0001] The present invention relates to the technical field of resin slurries, and particularly to a resin-based composite slurry, a carbon-based composite material and a preparation method thereof. Background Art

[0002] The photovoltaic hot field is the core equipment for the growth of crystalline silicon. Its main function is to provide a stable temperature field to promote the uniform growth of crystalline silicon. With the rapid development of the photovoltaic industry, the demand for high-quality crystalline silicon materials is also increasing continuously, which makes the demand for photovoltaic hot fields also show a high-speed growth trend.

[0003] In the early stage, high-purity and high-strength isostatic graphite materials were mainly used in the hot field system. However, due to the relatively poor high-temperature resistance performance, large thermal expansion coefficient of graphite materials, and the complex preparation process and high cost of high-purity and high-strength isostatic graphite materials, which are not conducive to large-scale production, etc., graphite materials have gradually been unable to adapt to the development trend of the hot field system. Carbon-based composite materials have advantages such as high cost performance and strong safety, and it has become a trend to replace graphite as the hot field material. Carbon-based composite materials are high-performance composite materials formed by carbon fiber or its fabric reinforcing the carbon matrix. They have excellent mechanical properties, thermal stability and chemical stability. However, the problem that fiber shedding occurs during the use of carbon-based composite materials in the hot field, which affects the product purity, has always troubled researchers. Summary of the Invention

[0004] Based on this, the present invention provides a resin-based composite slurry, which can prevent fiber shedding during the use of carbon-based composite materials in the hot field after curing.

[0005] The present invention is realized through the following technical solutions:

[0006] A resin-based composite slurry, in terms of mass percentage, includes the following components:

[0007] Graphite powder 14% - 24%,

[0008] Liquid resin 6% - 10% and

[0009] Organic solvent 70% - 80%;

[0010] The average particle size of the graphite powder is 80 mesh - 150 mesh.

[0011] In some embodiments, in terms of mass percentage, the slurry includes the following components:

[0012] Graphite powder 14% - 16%,

[0013] Liquid resin 8% - 10% and

[0014] Organic solvent 75 - 78%.

[0015] In some of these embodiments, the average particle size of the graphite powder is 100 mesh.

[0016] In some of these embodiments, the liquid resin is phenolic resin.

[0017] In some of these embodiments, the solid content of the phenolic resin is 70% - 90%.

[0018] In some of these embodiments, the viscosity of the phenolic resin is 1000 mPa·s - 2000 mPa·s.

[0019] In some of these embodiments, the number average molecular weight of the phenolic resin is 500 - 1000.

[0020] In some of these embodiments, the organic solvent includes one or more of ethanol, methanol, acetone, isopropanol, petroleum ether, cyclohexane, and chloroform.

[0021] A carbon-based composite material includes a carbon / carbon composite material and a protective layer coated on the surface of the carbon / carbon composite material, and the raw material of the protective layer includes the resin-based composite slurry described in any of the above embodiments.

[0022] A method for preparing a carbon-based composite material includes the following steps:

[0023] Apply the resin-based composite slurry described in the above embodiments to the surface of the carbon / carbon composite material, and perform curing treatment and carbonization treatment.

[0024] In some of these embodiments, the curing temperature is 280°C - 350°C.

[0025] In some of these embodiments, the curing time is 2.5 h - 4 h.

[0026] In some of these embodiments, the carbonization temperature is 900°C - 1200°C.

[0027] In some of these embodiments, the carbonization time is 50 h - 65 h.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a resin-based composite slurry, which comprises graphite powder, liquid resin and organic solvent. Among them, the liquid resin, as a binder, can effectively disperse the graphite powder evenly and bond it to the surface of the matrix material. The organic solvent can adjust the viscosity of the liquid resin. Further, the particle size of the graphite powder is limited to 80-150 mesh. The graphite with such a particle size range has a large specific surface area, making the combination between the graphite and the matrix tight. The above-mentioned slurry can be used for the protective layer of carbon / carbon composites. The protective layer has a flat and smooth surface, will not crack, and has a good bonding force with the matrix surface, which can prevent the fiber from falling off during the use of the carbon-based composite material in a thermal field. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Phase structure of the surface coating prepared in Example 6;

[0031] Figure 2 Structure of the peeling substance of the surface coating prepared in Example 6;

[0032] Figure 3 Combined sectional view of the coating and the matrix prepared in Example 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0035] When using "including", "having", and "comprising" described herein, it is intended to cover non-exclusive inclusion. Unless a clear limiting term is used, such as "only", "consisting of", etc., another component / component can also be added.

[0036] In the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features.

[0037] The terms "preferably", "more preferably", "more preferably", "even more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain cases. However, in the same or other cases, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention. That is, in the present invention, "preferably", "more preferably", "more preferably", "even more preferably", etc. are only used to describe embodiments or examples with better effects, but do not constitute a limitation on the protection scope of the present invention.

[0038] In the present invention, "further", "even further", "especially", etc. are used for descriptive purposes to indicate differences in content, but should not be construed as a limitation on the protection scope of the present invention.

[0039] When a numerical range is disclosed in the present invention, the above range is considered continuous and includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. And only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individually disclosed point or single numerical value itself can be used as a lower limit or an upper limit and combined with any other point or single numerical value or combined with other lower limits or upper limits to form a range not explicitly recited.

[0040] If there is no special instruction, all steps of the present invention can be carried out in sequence or randomly. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c) in sequence, or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0041] Unless otherwise mentioned, terms in the singular form can include the plural form and should not be understood as having a quantity of one.

[0042] The temperature parameters in the present invention, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument.

[0043] The weights of the relevant components mentioned in the embodiments of the specification of the present invention not only can refer to the specific contents of each component, but also can represent the proportional relationship of the weights between each component. Therefore, as long as the contents of the relevant components in the embodiments of the specification of the present invention are enlarged or reduced in proportion, they are within the scope disclosed in the embodiments of the specification of the present invention. Specifically, the weights described in the embodiments of the specification of the present invention can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0044] In the present invention, for the unit of the data range, if there is only a unit after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 800~850 nm means that the units of the left endpoint "800" and the right endpoint "850" are both nm (nanometer).

[0045] In the present invention, "above" or "below" both include the number itself. For example, below 1 means less than or equal to 1 (≤1), and above 1 means greater than or equal to 1 (≥1).

[0046] In order to solve the problem that fiber shedding occurs during the use of the carbon-based composite material in the thermal field, which affects the product purity, and at the same time further improve the antioxidant performance and high-temperature resistance of the carbon-based composite material, adding a coating to the surface of the carbon-based composite material is an effective method.

[0047] The existing preparation processes for surface coatings of carbon-based composites include the following: chemical vapor deposition (CVD) method, embedding method, sol-gel method, thermal spraying method, liquid-phase reaction method, etc. Although the chemical vapor deposition (CVD) process is easy to achieve commercial production, it has disadvantages such as low deposition rate, long preparation cycle, and complex process. Moreover, this process generally needs to be carried out under vacuum or protective atmosphere, and has high requirements for the airtightness of the equipment, so the preparation cost of the coating is relatively high. The embedding method also has problems that chemical reactions are likely to occur during the embedding process, damaging the fibers, thus impairing the mechanical properties of the carbon / carbon composites. It is very difficult to control the uniformity of the coating. The reaction-generated coating is not completely dense, and cracks are easily generated in the coating during the cooling process. Most of the raw materials used in the sol-gel method are organic compounds, with poor environmental friendliness, and the prepared coating is prone to cracking; the coating is relatively thin, etc. The thermal spraying method has the disadvantages of relatively high porosity of the coating, weak interfacial bonding between the coating and the substrate, and being prone to peeling or cracking during high-temperature thermal cycling. The liquid-phase reaction method requires a large amount of protective gas during the coating preparation process; moreover, only when the liquid-phase material has good wettability with the carbon substrate or the inner coating can the prepared coating obtain a uniform and dense structure, and at the same time, good bonding between the coating and the substrate and between the coatings can be ensured.

[0048] To solve one or more of the above technical problems, the present invention prepares a coating slurry through an optimized ratio. The coating slurry can prepare a carbon-based composite material coating with good effects through a simple process. The surface of the coating is uniform, the thickness is appropriate, the bonding strength with the surface is relatively high, and the phenomenon of fiber protrusion will not occur.

[0049] The technical solution of the present invention is as follows:

[0050] A resin-based composite slurry, in terms of mass percentage, includes the following components:

[0051] Graphite powder 14% - 24%,

[0052] Liquid resin 6% - 10% and

[0053] Organic solvent 70% - 80%;

[0054] The average particle size of the graphite powder is 80 mesh - 150 mesh.

[0055] In some examples, in terms of mass percentage, the slurry includes the following components:

[0056] Graphite powder 14% - 16%,

[0057] Liquid resin 8% - 10% and

[0058] Organic solvent 75% - 78%.

[0059] In some of these examples, the average particle size of the graphite powder is 100 mesh.

[0060] The resin-based composite slurry of the present invention comprises graphite powder, liquid resin and an organic solvent. Among them, the liquid resin acts as a binder, which can effectively disperse the graphite powder evenly and bond it to the surface of the matrix material. The organic solvent can adjust the viscosity of the liquid resin, making the prepared slurry easier to apply and operate. Further, the particle size of the graphite powder is defined as 80 - 150 mesh, preferably 100 mesh. In such a particle size range, the specific surface area of graphite is large, and the combination between graphite and the matrix is tight.

[0061] In some of these examples, the liquid resin is phenolic resin.

[0062] In some of these examples, the solid content of the phenolic resin is 70% - 90%.

[0063] In some of these examples, the viscosity of the phenolic resin is 1000 mPa·s - 2000 mPa·s.

[0064] In some of these examples, the number average molecular weight of the phenolic resin is 500 - 1000.

[0065] In some of these examples, the organic solvent comprises one or more of ethanol, methanol, acetone, isopropanol, petroleum ether, cyclohexane and chloroform.

[0066] In some of these examples, the organic solvent is ethanol, and the ethanol is an ethanol solution with a concentration of more than 95%.

[0067] In some specific examples, the organic solvent is a 97% ethanol solution.

[0068] The present invention uses a high-concentration ethanol solution as the organic solvent. On the one hand, the ethanol solution, as a diluent, can dilute the concentration of the composite slurry, making it easier to apply on the surface of the carbon-based composite material and ensuring the uniformity of the coating. Through the dilution effect of ethanol, the interfacial compatibility between the liquid phenolic resin and the graphite powder can also be improved, thereby enhancing the adhesion between the coating and the carbon-based composite material. Moreover, during the baking process, the high-concentration ethanol will volatilize rapidly, leaving a cured resin and graphite powder mixture, thus forming a solid coating.

[0069] A carbon-based composite material comprises a carbon / carbon composite material and a protective layer coated on the surface of the carbon / carbon composite material. The raw material of the protective layer comprises the resin-based composite slurry described in any of the above examples.

[0070] A method for preparing a carbon-based composite material comprises the following steps:

[0071] Apply the resin-based composite slurry described in the above embodiments to the surface of the carbon / carbon composite material, and perform curing treatment and carbonization treatment.

[0072] In some examples, the slurry coating method includes one of brush coating with a brush, brush coating with cotton cloth, and dipping the substrate in the slurry.

[0073] In some examples, the curing temperature is 280°C to 350°C.

[0074] In some examples, the curing time is 2.5 h to 4 h.

[0075] It can be understood that in the curing treatment step of the present invention, the carbon-based composite material substrate to be cured can be heated to the curing temperature within 1 h, and the heating method is not limited.

[0076] The curing treatment of the present invention does not require an inert protective atmosphere. Under the above curing temperature and curing time conditions, the alcohol in the composite slurry can be quickly volatilized, the combination between the slurry and the substrate surface is closer, and finally the cured protective layer has no disadvantages of easy stickiness and easy erasability.

[0077] In some examples, the carbonization temperature is 900°C to 1200°C.

[0078] In some examples, the carbonization time is 50 h to 65 h.

[0079] It can be understood that in the carbonization treatment process of the present invention, vacuum pumping or an inert atmosphere is adopted to protect the coating from oxidation, and under the above conditions, methane and CO decomposed during the carbonization of the resin can also be adsorbed.

[0080] The present invention coats the slurry after sufficient stirring on the surface of the substrate material or dips the substrate in the slurry to form a coating. After curing at a certain temperature, heat treatment is carried out under vacuum conditions or a high-temperature inert atmosphere (such as a nitrogen atmosphere). The advantages of the coating method of the present invention are simple, convenient, fast, low cost, and the structure can be artificially controlled. Each layer can be very thin, and it is easy to realize multi-layer and multi-gradient coatings.

[0081] The embodiments of the present invention will be described in detail below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following examples, the guidance given in the present invention is preferably referred to, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0082] In the following specific embodiments, for the measurement parameters of the raw material components, there may be slight deviations within the weighing accuracy range without special instructions. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0083] The raw materials used in the following specific embodiments are as follows:

[0084] Graphite powder (Qingdao Huatai Lubrication Sealing Technology Co., Ltd.)

[0085] Phenolic resin (Jinan Shengquan Group Co., Ltd., EXP0322)

[0086] Carbon matrix material: carbon-carbon crucible;

[0087] All other reagents are commercially available conventional analytical pure reagents.

[0088] Example 1

[0089] Slurry preparation: Mix 15% graphite powder, 77% organic solvent, and 8% liquid phenolic resin by mass to form a uniform slurry;

[0090] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 100 mesh.

[0091] Coating the slurry: Apply the above slurry evenly to the surface of the carbon matrix material sample with a brush.

[0092] Coating curing: Place the carbon matrix material sample with the slurry coated on its surface evenly in an oven. Without an inert protective atmosphere, heat the oven temperature from room temperature to 300 °C, and the curing time is 3 h.

[0093] Coating carbonization: Send the baked carbon matrix material sample to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0094] Test the performance of the carbonized coating.

[0095] Example 2

[0096] Slurry preparation: Mix 15% graphite powder, 79% organic solvent, and 6% liquid phenolic resin by mass to form a uniform slurry;

[0097] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 100 mesh.

[0098] Coating the slurry: Apply the above slurry evenly to the surface of the carbon matrix material sample with a brush.

[0099] Coating curing: The carbon matrix material specimens with the surface coated with slurry are evenly placed in an oven. Without an inert protective atmosphere, the oven temperature is heated from room temperature to 300 °C, and the curing time is 3 h.

[0100] Coating carbonization: The baked carbon matrix material specimens are sent to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0101] Perform performance testing on the carbonized coating.

[0102] Example 3

[0103] Slurry preparation: Mix 15% graphite powder, 75% organic solvent, and 10% liquid phenolic resin by mass percentage into a uniform slurry;

[0104] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 100 mesh.

[0105] Coating the slurry: Evenly brush the above slurry onto the surface of the carbon matrix material specimen with a brush.

[0106] Coating curing: The carbon matrix material specimens with the surface coated with slurry are evenly placed in an oven. Without an inert protective atmosphere, the oven temperature is heated from room temperature to 300 °C, and the curing time is 3 h.

[0107] Coating carbonization: The baked carbon matrix material specimens are sent to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0108] Perform performance testing on the carbonized coating.

[0109] Example 4

[0110] Slurry preparation: Mix 15% graphite powder, 77% organic solvent, and 8% liquid phenolic resin by mass percentage into a uniform slurry;

[0111] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 80 mesh.

[0112] Coating the slurry: Evenly brush the above slurry onto the surface of the carbon matrix material specimen with a brush.

[0113] Coating curing: The carbon matrix material specimens with the surface coated with slurry are evenly placed in an oven. Without an inert protective atmosphere, the oven temperature is heated from room temperature to 300 °C, and the curing time is 3 h.

[0114] Coating carbonization: The baked carbon matrix material sample is sent to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0115] Perform performance testing on the carbonized coating.

[0116] Example 5

[0117] Slurry preparation: Mix 15% graphite powder, 77% organic solvent, and 8% liquid phenolic resin by mass percentage to form a uniform slurry;

[0118] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 120 mesh.

[0119] Coating the slurry: Uniformly brush the above slurry onto the surface of the carbon matrix material sample with a brush.

[0120] Coating curing: Evenly place the carbon matrix material sample with the slurry coated on its surface into an oven. Without an inert protective atmosphere, heat the oven temperature from room temperature to 300 °C, and the curing time is 3 h.

[0121] Coating carbonization: The baked carbon matrix material sample is sent to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0122] Perform performance testing on the carbonized coating.

[0123] Example 6

[0124] The preparation process of Example 6 is basically the same as that of Example 1, except that in the step of coating the slurry in Example 6, a cotton cloth is used for coating.

[0125] Example 7

[0126] The preparation process of Example 7 is basically the same as that of Example 1, except that in the step of coating the slurry in Example 7, a spray gun is used for spraying.

[0127] Example 8

[0128] The preparation process of Example 8 is basically the same as that of Example 1, except that in the step of coating the slurry in Example 7, the carbon matrix material sample is immersed in the slurry.

[0129] Comparative Example 1

[0130] Slurry preparation: Mix 15% graphite powder, 80% organic solvent, and 5% liquid phenolic resin by mass percentage to form a uniform slurry;

[0131] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 100 mesh.

[0132] Coating the slurry: Uniformly coat the above-mentioned slurry on the surface of the carbon matrix material sample with a brush.

[0133] Coating curing: Uniformly place the carbon matrix material sample with the slurry coated on its surface into an oven. Under the condition of no inert protective atmosphere, heat the oven temperature from room temperature to 300 °C, and the curing time is 3 h.

[0134] Coating carbonization: Send the baked carbon matrix material sample to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0135] Perform performance testing on the carbonized coating.

[0136] Comparative Example 2

[0137] Slurry preparation: Mix 15% graphite powder, 74% organic solvent, and 11% liquid phenolic resin by mass to form a uniform slurry;

[0138] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 100 mesh.

[0139] Coating the slurry: Uniformly coat the above-mentioned slurry on the surface of the carbon matrix material sample with a brush.

[0140] Coating curing: Uniformly place the carbon matrix material sample with the slurry coated on its surface into an oven. Under the condition of no inert protective atmosphere, heat the oven temperature from room temperature to 300 °C, and the curing time is 3 h.

[0141] Coating carbonization: Send the baked carbon matrix material sample to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0142] Perform performance testing on the carbonized coating.

[0143] Comparative Example 3

[0144] Slurry preparation: Mix 15% graphite powder, 77% organic solvent, and 8% liquid phenolic resin by mass to form a uniform slurry;

[0145] Among them, the organic solvent is specifically a 97% ethanol solution, and the particle size of the graphite powder is 70 mesh.

[0146] Coating the slurry: Uniformly coat the above-mentioned slurry on the surface of the carbon matrix material sample with a brush.

[0147] Coating curing: The carbon matrix material specimens with slurry painted on the surface are evenly placed in an oven. Without an inert protective atmosphere, the oven temperature is heated from room temperature to 300 °C, and the curing time is 3 h.

[0148] Coating carbonization: The baked carbon matrix material specimens are sent to a high-temperature carbonization furnace that has been evacuated for carbonization. The carbonization temperature of the carbonization furnace is 950 °C, and the carbonization time is 53 h.

[0149] Perform performance testing on the carbonized coating.

[0150] Through the comparison between Example 1 and Comparative Example 1 above, it is found that the proportion of phenolic resin in Comparative Example 1 is 5%. After applying the slurry, it is found that the slurry has good fluidity. Although a film is also formed on the surface, the coating is thin, and the adhesion between the resin and the material surface is poor. In Comparative Example 1, the phenomenon of easy scratching and exposure of the matrix surface occurs in the coating. This is because the resin proportion is small, the slurry is thin, and the thickness of the coating after resin carbonization is thin, unable to effectively protect the problem of fiber shedding on the surface of the matrix material.

[0151] Through the comparison between Example 1 and Comparative Example 2 above, it is found that the proportion of phenolic resin in Comparative Example 2 is 11%. After applying the slurry, it is found that the slurry is relatively viscous and has poor fluidity. The slurry can be applied evenly, but the coating is thick, and the coating is prone to scratching during handling. Moreover, the phenomenon of cracking occurs in the coating after carbonization in the prepared coating. It is estimated that due to the large proportion of resin, the slurry is too viscous, the coating is thick, and cracking occurs due to shrinkage after resin carbonization.

[0152] Through the comparison between Example 1, Example 5 and Comparative Example 3 above, it is found that when the particle size of graphite powder is large, the specific surface area of graphite powder is small, and the combination between graphite and the matrix is not tight enough; when the particle size of graphite powder is small, the specific surface area is large and the bonding force is stronger, but the price of graphite powder is more expensive and the use performance is excessive, and it can be used as appropriate.

[0153] Through the comparison between Example 1 and Examples 6 - 8 above, it is found that the coating surface prepared by spray gun in Example 7 is not dense, and the degree of combination with the material surface is insufficient, and the coating will fall off with a little friction; the coating surface obtained by the impregnation method in Example 8 is not dense, and the degree of combination with the material surface is insufficient; the coating surface brushed by the brush in Example 1 is dense and the bonding strength is also good, but there are more requirements for brushing. For example, the finer and denser the bristles of the brush, the better, and the more times of brushing, the better. If the number of brushing times is small, brush marks will appear on the coating surface, and sometimes bristles will fall on the coating surface; the coating surface brushed with cotton fabric in Example 6 has the best effect, the coating surface is uniform, the bonding strength is high, and a good coating effect can be obtained with relatively low requirements for brushing.

[0154] Figure 1 The phase structure of the surface coating prepared for Example 6; Figure 2The structure of the surface coating stripping substance prepared in Example 6; Figure 3 The bonding sectional view of the coating and the substrate prepared in Example 6. According to Figures 1 to 3 As shown, the protective coating prepared in Example 6 is connected densely and firmly, and is not easy to fall off; no carbon fiber is found on the surface of the protective coating, and the protective layer coverage rate reaches 99%; the thickness of the protective coating is relatively high, and no carbon fiber is found in the structure of the protective layer peeled off forcibly; the delamination structure between the protective coating and the fiber interface is obvious, and the fiber does not enter the middle of the protective layer.

[0155] In summary, the preferred solution of the present invention is to use a slurry prepared with 15% graphite powder, 77% organic solvent, and 8% liquid resin by mass percentage. The average particle size of the graphite powder is 100 mesh, the organic solvent is a 97% ethanol solution, and the best coating effect is obtained by dipping a cotton cloth in the slurry and brushing the surface. The coating surface is uniform, the thickness is moderate, the bonding strength with the surface is relatively high, and there is no phenomenon of fiber protrusion.

[0156] The preparation process of the slurry brushing method of the present invention is simple, the preparation period is short, the cost is low, and the environmental pollution is less. It is a relatively good method for preparing the surface protective coating of carbon-based composites.

[0157] The technical features of the above-mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered that the scope described in this specification is covered.

[0158] The above-mentioned embodiments only represent several implementation manners of the present invention, which are convenient for understanding the technical solutions of the present invention specifically and in detail, but should not be construed as limiting the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the appended claims of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the content of the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A resin-based composite slurry, characterized in that, Comprising the following components by mass percentage: Graphite powder 14% - 24%, Liquid resin 6% - 10% and Organic solvent 70% - 80%; The average particle size of the graphite powder is 80 mesh - 150 mesh.

2. The composite slurry according to claim 1, characterized in that, Comprising the following components by mass percentage: Graphite powder 14% - 16%, Liquid resin 8% - 10% and Organic solvent 75% - 78%.

3. The composite slurry according to claim 1 or 2, characterized in that, The average particle size of the graphite powder is 100 mesh.

4. The composite slurry according to claim 1 or 2, characterized in that, The liquid resin is phenolic resin.

5. The composite slurry according to claim 4, characterized in that, The phenolic resin satisfies one or more of the following (1) - (3): (1) The solid content is 70% - 90%; (2) The viscosity is 1000 mPa·s - 2000 mPa·s; (3) The number-average molecular weight is 500 - 1000.

6. The composite slurry according to claim 1 or 2, characterized in that, The organic solvent includes one or more of ethanol, methanol, acetone, isopropanol, petroleum ether, cyclohexane and chloroform.

7. A carbon-based composite material, characterized in that, Comprising a carbon / carbon composite material and a protective layer coated on the surface of the carbon / carbon composite material, and the raw material of the protective layer includes the resin-based composite slurry according to any one of claims 1 to 6.

8. A method for preparing a carbon-based composite material, characterized in that, Comprising the following steps: Applying the resin-based composite slurry according to any one of claims 1 to 6 to the surface of the carbon / carbon composite material, and performing curing treatment and carbonization treatment.

9. The preparation method according to claim 8, wherein The curing treatment satisfies one or more of the following (1) - (2): (1) The curing temperature is 280°C - 350°C; (2) The curing time is 2.5 h - 4 h.

10. The preparation method according to claim 8 or 9, characterized in that, The carbonization treatment satisfies one or more of the following (1) - (2): (1) The carbonization temperature is 900°C - 1200°C; (2) The carbonization time is 50 h - 65 h.

Images