Carbon fiber composite hard felt and preparation method and application thereof

Abstract

The present application relates to a kind of carbon fiber composite hard felt and its preparation method and application.Carbon fiber composite hard felt includes the asphalt-based composite hard felt layer and PAN-based composite hard felt layer in turn superposed;The asphalt-based composite hard felt layer includes at least one asphalt-based carbon fiber hard felt and at least one graphite paper, the asphalt-based carbon fiber hard felt and the graphite paper are alternately arranged.The preparation method of carbon fiber composite hard felt includes the following steps: S1, carbon fiber composite hard felt preform is sequentially cured and once graphitized, obtains carbon fiber composite hard felt precursor;S2, protective layer is arranged in the carbon fiber composite hard felt precursor, sequentially cured and twice graphitized.The carbon fiber composite hard felt of the present application can be used as the heat insulating material in vacuum high-pressure furnace, with the characteristics of high pressure resistance, airflow scouring resistance, good heat insulation performance, and long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to a carbon fiber composite hard felt and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of national defense, metallurgy, wind power and other fields, vacuum high-pressure gas quenching has been increasingly used for vacuum heat treatment of molds, precision alloys, copper-nickel and other materials. With the increasingly wide application of vacuum high-pressure gas quenching furnaces, the demand for heat insulation materials in the furnace is also increasing rapidly, and the performance requirements for heat insulation materials are also increasing.

[0003] For example, the existing PAN-based carbon fiber has relatively strong ablation resistance in a high-temperature furnace, is cheap, but has poor flexibility, generates a large amount of dust, and has a relatively large thermal conductivity in a high-temperature zone.

[0004] Therefore, there is a need for an excellent heat insulation material with high pressure resistance, airflow scouring resistance, good heat insulation performance and long service life for use in a vacuum high-pressure gas quenching furnace. SUMMARY

[0005] The present application provides a carbon fiber composite hard felt and a preparation method and application thereof to overcome the technical defects of poor flexibility, large dust generation and relatively large thermal conductivity in a high-temperature zone of the existing fiber felt. The carbon fiber composite hard felt has high pressure resistance, airflow scouring resistance, good heat insulation performance and long service life.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a carbon fiber composite hard felt, which comprises a pitch-based composite hard felt layer and a PAN-based composite hard felt layer stacked in sequence;

[0008] The pitch-based composite hard felt layer comprises at least one layer of pitch-based carbon fiber hard felt and at least one layer of graphite paper, and the pitch-based carbon fiber hard felt and the graphite paper are arranged alternately;

[0009] The PAN-based composite hard felt layer comprises at least one layer of PAN-based carbon fiber hard felt and at least one layer of graphite paper, and the PAN-based composite hard felt layer and the graphite paper are arranged alternately;

[0010] The side of the pitch-based composite hard felt layer close to the PAN-based composite hard felt layer is pitch-based carbon fiber hard felt, and the side of the PAN-based composite hard felt layer close to the pitch-based composite hard felt layer is graphite paper;

[0011] The side of the pitch-based composite hard felt layer away from the PAN-based composite hard felt layer is provided with a protective layer, and the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer is provided with a protective layer.

[0012] In the present application, the thickness ratio of the pitch-based composite hard felt layer to the PAN-based composite hard felt layer is preferably at least 2:1.

[0013] In the present application, the thickness of the pitch-based composite hard felt layer can be 80-100 mm.

[0014] In the pitch-based composite hard felt layer, the thickness of each layer of pitch-based carbon fiber hard felt can independently be 8-10 mm. Preferably, in the pitch-based composite hard felt layer, the thickness of each layer of pitch-based carbon fiber hard felt is the same. In the pitch-based composite hard felt layer, the thickness of the graphite paper can be 0.2-0.7 mm, for example 0.3 mm.

[0015] In the present application, the thickness of the PAN-based composite hard felt layer can be 10-24 mm.

[0016] In the PAN-based composite hard felt layer, the thickness of each layer of PAN-based carbon fiber hard felt can independently be 5-8 mm. Preferably, in the PAN-based composite hard felt layer, the thickness of each layer of PAN-based carbon fiber hard felt is the same.

[0017] In the PAN-based composite hard felt layer, the thickness of the graphite paper can be 0.2-0.7 mm, for example 0.3 mm.

[0018] In the present application, the thickness of the graphite paper in the pitch-based composite hard felt layer and the thickness of the graphite paper in the PAN-based composite hard felt layer can be the same or different.

[0019] In the present application, the carbon content of the carbon fiber composite hard felt can be not less than 99 wt%. The carbon content refers to the percentage of carbon elements in the material, which is tested according to the standard GB / T31292-2014.

[0020] In the present application, the carbon content of each layer of pitch-based carbon fiber hard felt can independently be not less than 99 wt%.

[0021] Preferably, in the pitch-based composite hard felt layer, the carbon content of each layer of pitch-based carbon fiber hard felt is the same.

[0022] In the present application, the carbon in the pitch-based carbon fiber hard felt can include pitch-based carbon fiber and pyrolytic carbon attached to the pitch-based carbon fiber. The mass of the pyrolytic carbon can be 1-10 wt% of the mass of the pitch-based carbon fiber hard felt, for example 5 wt%.

[0023] In the present application, the carbon content of each layer of PAN-based carbon fiber hard felt can independently be not less than 99 wt%.

[0024] Preferably, the carbon content of each layer of the PAN-based carbon fiber hard felt in the PAN-based composite hard felt layer is the same.

[0025] In the present application, the carbon in the PAN-based carbon fiber hard felt can include PAN-based carbon fiber and pyrolytic carbon attached to the PAN-based carbon fiber. The mass of the pyrolytic carbon can be 1-10 wt% of the mass of the PAN-based carbon fiber hard felt, for example 5 wt%.

[0026] In the present application, the density of the carbon fiber composite hard felt can be 0.16-0.30 g / cm 3 , for example 0.20 g / cm 3 .

[0027] In the present application, the density of the pitch-based composite hard felt layer is preferably 0.18-0.20 g / cm 3 , for example 0.18 g / cm 3 .

[0028] In the present application, the number of layers of the pitch-based carbon fiber hard felt in the pitch-based composite hard felt layer is preferably at least 2 layers.

[0029] In the present application, the density of the PAN-based composite hard felt layer is preferably 0.16-0.18 g / cm 3 , for example 0.18 g / cm 3 .

[0030] In the present application, the areal density of each layer of the graphite paper in the pitch-based composite hard felt layer and the PAN-based composite hard felt layer can be independently 200-400 g / m 2 , for example 400 g / m 2 . Preferably, the areal density of each layer of the graphite paper in the pitch-based composite hard felt layer and the PAN-based composite hard felt layer is the same.

[0031] In the present application, the material of each layer of the graphite paper in the pitch-based composite hard felt layer and the PAN-based composite hard felt layer can be independently flake graphite. Preferably, the material of each layer of the graphite paper in the pitch-based composite hard felt layer and the PAN-based composite hard felt layer is flake graphite.

[0032] In the present application, the graphite paper has high heat dissipation efficiency, can eliminate the hot spot area of the product, and make the entire product heat field uniform; and the graphite paper has the characteristics of sealing gas, and in combination with the heat insulation materials (pitch-based carbon fiber hard felt and PAN-based carbon fiber hard felt), can achieve the effect of high pressure resistance.

[0033] In the present application, the thermal conductivity of the carbon fiber composite hard felt can be no more than 0.45 W / m·K, for example 0.41 W / m·K. The thermal conductivity measurement method is tested according to the flat plate steady state method.

[0034] In the present application, the thermal conductivity of each layer of the pitch-based carbon fiber hard felt can be independently 0.1-0.5 W / m·K.

[0035] Preferably, in the pitch-based composite hard felt layer, the thermal conductivity of each layer of pitch-based carbon fiber hard felt is the same.

[0036] In the present application, the thermal conductivity of each layer of the PAN-based carbon fiber hard felt can be independently 0.2-0.8 W / m·K.

[0037] Preferably, in the PAN-based composite hard felt layer, the thermal conductivity of each layer of PAN-based carbon fiber hard felt is the same.

[0038] In some preferred embodiments of the present application, the protective layer is a carbon fiber cloth. The carbon fiber cloth has the characteristics of resisting airflow scouring.

[0039] Among them, the carbon content of the carbon fiber cloth can be no less than 99wt%.

[0040] Among them, the thickness of the carbon fiber cloth can be 0.5-0.7mm, for example 0.7mm.

[0041] Among them, the areal density of the carbon fiber cloth can be 200-600g / m 2 , for example 500g / m 2 .

[0042] In some preferred embodiments of the present application, the protective layer is a carbon shell. The carbon shell can block the voids of the outermost layer of hard felt and reduce the reaction of impurity gas with carbon fiber.

[0043] Among them, the thickness of the carbon shell can be 0.8-1.5mm.

[0044] Among them, the mass of the carbon shell can be 1-10wt% of the mass of the carbon fiber composite hard felt, for example 5wt%.

[0045] In the present application, the protective layer on the side of the pitch-based composite hard felt layer away from the PAN-based composite hard felt layer can be the same as or different from the protective layer on the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer, and preferably the same. For example, both the protective layer on the side of the pitch-based composite hard felt layer away from the PAN-based composite hard felt layer and the protective layer on the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer are carbon fiber cloth, or both the protective layer on the side of the pitch-based composite hard felt layer away from the PAN-based composite hard felt layer and the protective layer on the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer are carbon shell.

[0046] In another preferred embodiment of the present application, the side of the pitch-based composite hard felt layer away from the PAN-based composite hard felt layer is graphite paper, and the graphite paper layer serves as a protective layer.

[0047] In another preferred embodiment of the present application, the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer is graphite paper, and the graphite paper layer serves as a protective layer.

[0048] In the present application, preferably, at least one end face of the carbon fiber composite hard felt is provided with a protective layer. The provision of a protective layer on the end face can improve the oxidation resistance of the end face and prevent the end face from being oxidized prematurely and affecting the service life of the entire product.

[0049] In some preferred embodiments of the present application, the protective layer is carbon fiber cloth or carbon shell. The carbon fiber cloth or carbon shell is as described above.

[0050] Preferably, both end faces of the carbon fiber composite hard felt are provided with protective layers, and the protective layers can be the same or different, and preferably the same. For example, both end faces of the carbon fiber composite hard felt are provided with carbon fiber cloth, or both end faces of the carbon fiber composite hard felt are provided with carbon shell.

[0051] In the present application, the ash content of the carbon fiber composite hard felt can be less than 20 ppm, for example, 13 ppm. The ash content refers to the mass percentage of impurities and ash remaining in the carbon fiber composite hard felt, which is detected according to the standard YB / T 5146. A high ash content can reduce the strength, modulus, electrical conductivity and corrosion resistance of the carbon fiber composite hard felt, thereby affecting the quality and service life of the product.

[0052] In the present application, the thickness direction pressure resistance of the carbon fiber composite hard felt can be ≥1.0 MPa, for example, 1.2 MPa.

[0053] In the present application, the bending strength of the carbon fiber composite hard felt can be ≥1.5 MPa, for example, 1.5 MPa.

[0054] In the present application, the bending strength is according to the standard JB / T8133.7-2013, and the compressive strength test standard is GB / T1431.

[0055] In the present application, the carbon fiber composite hard felt is preferably in a cylindrical shape, i.e., the carbon fiber composite hard felt is a carbon fiber composite hard felt cylinder, and the pitch-based composite hard felt layer is located on the inner side of the cylinder.

[0056] In a second aspect, the present application provides a preparation method of the carbon fiber composite hard felt, which comprises the following steps:

[0057] S1, sequentially subjecting a carbon fiber composite hard felt preform to primary curing and primary graphitization to obtain a carbon fiber composite hard felt precursor; wherein,

[0058] The carbon fiber composite hard felt preform comprises a pitch-based composite soft felt layer and a PAN-based composite soft felt layer which are sequentially stacked;

[0059] The pitch-based composite soft felt layer comprises at least one layer of pitch-based carbon fiber soft felt impregnated with glue and at least one layer of graphite paper, and the pitch-based carbon fiber soft felt impregnated with glue and the graphite paper are arranged alternately;

[0060] The PAN-based composite soft felt layer comprises at least one layer of PAN-based carbon fiber soft felt impregnated with glue and at least one layer of graphite paper, and the PAN-based carbon fiber soft felt impregnated with glue and the graphite paper are arranged alternately;

[0061] The side of the pitch-based composite soft felt layer close to the PAN-based composite soft felt layer is the pitch-based carbon fiber soft felt impregnated with glue, and the side of the PAN-based composite hard felt layer close to the pitch-based composite soft felt layer is the graphite paper;

[0062] S2, disposing a protective layer on the carbon fiber composite hard felt precursor, and sequentially subjecting it to secondary curing and secondary graphitization; wherein, the protective layer is disposed on the side of the pitch-based composite soft felt layer away from the PAN-based composite soft felt layer and the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer, respectively.

[0063] In the preparation method of the present application, the pitch-based carbon fiber soft felt impregnated with glue forms the pitch-based carbon fiber hard felt after steps S1 and S2, the PAN-based carbon fiber soft felt impregnated with glue forms the PAN-based carbon fiber hard felt after steps S1 and S2, and the graphite paper does not change after steps S1 and S2.

[0064] In the present application, in step S1, the areal density of each layer of the pitch-based carbon fiber soft felt can be independently 800-1400 g / m 2 , for example, 800 g / m 2Preferably, the areal density of each layer of the pitch-based carbon fiber soft felt is the same.

[0065] In the present application, in step S1, the thickness of each layer of the pitch-based carbon fiber soft felt can be independently 10-20mm, for example, 10mm, 15mm or 20mm. Preferably, the thickness of each layer of the pitch-based carbon fiber soft felt is the same.

[0066] In the present application, in step S1, the carbon content of each layer of the pitch-based carbon fiber soft felt can be independently ≥99.5wt%. Preferably, the carbon content of each layer of the pitch-based carbon fiber soft felt is the same.

[0067] In the present application, in step S1, the areal density of each layer of the PAN-based carbon fiber soft felt can be independently 1000-1200g / m 2 , for example, 1200g / m 2 . Preferably, the areal density of each layer of the PAN-based carbon fiber soft felt is the same.

[0068] In the present application, in step S1, the thickness of each layer of the PAN-based carbon fiber soft felt can be independently 5-10mm. Preferably, the thickness of each layer of the PAN-based carbon fiber soft felt is the same.

[0069] In the present application, in step S1, the carbon content of each layer of the PAN-based carbon fiber soft felt can be independently ≥99.5wt%. Preferably, the carbon content of each layer of the PAN-based carbon fiber soft felt is the same.

[0070] In the present application, in step S1, the impregnation sizing operation can be conventional in the art, in which the carbon fiber soft felt is impregnated in the impregnation sizing liquid and then squeezed to remove the excess impregnation sizing liquid. The impregnation sizing liquid in the impregnation sizing pitch-based carbon fiber soft felt forms the pyrolytic carbon attached to the pitch-based carbon fiber after steps S1 and S2; the impregnation sizing liquid in the impregnation sizing PAN-based carbon fiber soft felt forms the pyrolytic carbon attached to the PAN-based carbon fiber after steps S1 and S2.

[0071] In some embodiments of the present application, the impregnation sizing liquid can include a resin and a solvent.

[0072] The resin can be conventional in the art, and is preferably a phenolic resin. The phenolic resin can be a phenolic resin conventionally used in the art for impregnation of carbon fiber felt, and is preferably a thermosetting phenolic resin, for example, an amino phenolic resin.

[0073] The content of the resin can be 6wt%-60wt%, and is preferably 6wt%-11wt%, for example, 8wt% or 10wt%.

[0074] The solvent can be water, ethanol or isopropanol.

[0075] In the present application, the impregnation sizing solution of the impregnation sizing pitch-based carbon fiber soft felt and the impregnation sizing solution of the impregnation sizing PAN-based carbon fiber soft felt can be the same or different, preferably the same.

[0076] In the present application, in step S1, the impregnation amount of the impregnation sizing pitch-based carbon fiber soft felt can be 50wt%-200wt%, preferably 90wt%-110wt%, for example 100wt%. Wherein, the impregnation amount refers to the mass percentage of the impregnation sizing solution in the impregnation sizing pitch-based carbon fiber soft felt.

[0077] In the present application, in step S1, the impregnation amount of the impregnation sizing PAN-based carbon fiber soft felt can be 50wt%-200wt%, preferably 90wt%-110wt%, for example 100wt%. Wherein, the impregnation amount refers to the mass percentage of the impregnation sizing solution in the impregnation sizing PAN-based carbon fiber soft felt.

[0078] In the present application, in step S1, the implementation mode of the alternately arranged can be that the carbon fiber soft felt and the graphite paper are bonded and rolled. The rolling can be performed by means of a solid shaft.

[0079] In the present application, in step S1, the temperature of the first curing can be 100-200℃, for example 150℃.

[0080] In the present application, in step S1, the time of the first curing can be 3-10h, for example 10h.

[0081] In the present application, in step S1, the atmosphere of the first curing can be air.

[0082] In the present application, in step S1, the temperature of the first graphitization can be 2000-2400℃, for example 2400℃.

[0083] In the present application, in step S1, the time of the first graphitization can be 60-100h, for example 100h.

[0084] In the present application, in step S1, the vacuum degree of the first graphitization can be 200Pa or less.

[0085] In the present application, in step S1, the atmosphere of the first graphitization can be inert atmosphere, for example argon.

[0086] In the present application, in step S2, the temperature of the second curing can be 100-200℃, for example 200℃.

[0087] In the present application, the time for the secondary curing in step S2 can be 3-5h, for example, 5h.

[0088] In the present application, the temperature for the secondary graphitization in step S2 can be 2000-2400℃, for example, 2400℃.

[0089] In the present application, the time for the secondary graphitization in step S2 can be 60-100h, for example, 100h.

[0090] In the present application, the atmosphere for the secondary graphitization in step S2 can be inert atmosphere, for example, argon.

[0091] In the present application, the vacuum degree for the secondary graphitization in step S2 can be 200Pa or less.

[0092] In some embodiments of the present application, the protective layer is carbon fiber cloth. When the protective layer is carbon fiber cloth, the protective layer does not change after step S2.

[0093] In some embodiments of the present application, the protective layer is carbon shell. When the protective layer is carbon shell, the method for forming the carbon shell can be: in step S2, at least one of the side of the pitch-based composite soft felt layer away from the PAN-based composite soft felt layer and the side of the PAN-based composite hard felt layer away from the pitch-based composite hard felt layer is coated with a carbon coating layer, and then sequentially subjected to secondary curing and secondary graphitization to obtain the carbon shell.

[0094] The carbon coating layer can include the following components in mass percentage: 10wt%-50wt% of resin, 5wt%-15wt% of carbon black, 0.1wt%-0.5wt% of surfactant, and the balance of solvent.

[0095] The resin can be one or more of vinyl resin, epoxy resin, and phenolic resin.

[0096] The particle size of the carbon black can be 60-500 mesh.

[0097] The surfactant can be conventional in the art.

[0098] The solvent can be ethanol.

[0099] The coating amount of the carbon coating layer can be 500-2000g / m 2 .

[0100] In the present application, preferably, in step S2, the protective layer is also arranged on at least one end surface of the carbon fiber composite hard felt precursor.

[0101] In the present application, preferably, between the pitch-based composite soft felt layer and the PAN-based composite soft felt layer, between the impregnated and sized pitch-based carbon fiber soft felt and the graphite paper in the pitch-based composite soft felt layer, between the impregnated and sized PAN-based carbon fiber soft felt and the graphite paper in the PAN-based composite soft felt layer, between the carbon fiber composite hard felt precursor and the protective layer, an adhesive is used for bonding. By means of bonding, the carbon fiber composite hard felt can be prevented from cracking during use.

[0102] In some preferred embodiments of the present application, the adhesive comprises the following components by mass percentage: phenolic resin 30wt%-80wt%, for example 50wt%, carbon powder 5wt%-30wt%, for example 20wt%, and coupling agent 0.1wt%-0.5wt%, for example 0.3wt%, with the balance being solvent.

[0103] The solvent can be ethanol.

[0104] The phenolic resin can be a conventional phenolic resin used as an adhesive in the art, preferably a thermosetting phenolic resin, for example an amino phenolic resin.

[0105] The carbon powder can be carbon powder with a particle size of 500-1000 mesh and / or nano carbon powder.

[0106] The coupling agent can be a conventional high molecular coupling agent in the art, preferably a BYK series coupling agent, for example BYK-C8001, BYK-C8002 or BYK-C8013. The use of the coupling agent is advantageous for improving the mechanical strength.

[0107] The coating amount of the adhesive can be 200-1000g / m 2 , for example 200g / m 2 , 300g / m 2 , 500g / m 2 , 600g / m 2 or 800g / m 2 . The coating amount refers to the single-sided coating amount.

[0108] In a preferred embodiment of the present application, the coating amount of the adhesive between the impregnated and sized pitch-based carbon fiber soft felt and the graphite paper in the pitch-based composite soft felt layer is 300g / m 2 .

[0109] In a preferred embodiment of the present application, the coating amount of the adhesive between the impregnated and sized PAN-based carbon fiber soft felt and the graphite paper in the PAN-based composite soft felt layer is 300g / m 2 .

[0110] In a preferred embodiment of the present application, the coating amount of the adhesive between the carbon fiber composite hard felt precursor and the protective layer is 600g / m 2 .

[0111] In a third aspect, the present application provides a carbon fiber composite hard felt as described above for use as a heat insulation material in a vacuum high-pressure furnace. When used as a heat insulation material in a vacuum high-pressure furnace, the pitch-based composite hard felt layer is arranged close to the center of the vacuum high-pressure furnace.

[0112] In the above use, the pitch-based composite hard felt layer is arranged close to the center of the vacuum high-pressure furnace. The center of the vacuum high-pressure furnace is a high-temperature zone, and the area close to the furnace wall is a low-temperature zone. The pitch-based composite hard felt layer has excellent heat insulation performance and low thermal conductivity, so it is arranged in the high-temperature zone at the center of the vacuum high-pressure furnace. The PAN-based composite hard felt layer has good mechanical strength and relatively low price, but poor high-temperature heat insulation performance, so it is arranged in the low-temperature zone close to the furnace wall. In this way, the heat insulation effect is achieved, the mechanical strength of the entire product is improved, and the cost performance is relatively high.

[0113] In the present application, when used, the internal pressure of the vacuum high-pressure furnace can be 1-10MPa.

[0114] On the basis of not violating the common sense of the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain each preferred example of the present application.

[0115] The reagents and raw materials used in the present application are commercially available.

[0116] The positive progress effect of the present application is that:

[0117] The present application provides a carbon fiber composite hard felt. Based on the temperature distribution characteristics of the internal temperature of a vacuum high-pressure furnace, by compounding a pitch-based carbon fiber hard felt, a PAN-based carbon fiber hard felt, and a graphite paper in a specific way, the characteristics of different carbon fiber heat insulation materials and graphite paper are fully utilized, and the following effects are achieved at the same time: (1) good heat insulation performance; (2) high pressure resistance; (3) resistance to airflow scouring; (4) long service life; (5) relatively high cost performance. BRIEF DESCRIPTION OF DRAWINGS

[0118] Fig. 1 is a perspective view of the carbon fiber composite hard felt cylinder in Example 1;

[0119] Fig. 2 is a side view of the carbon fiber composite hard felt cylinder in Example 1;

[0120] Fig. 3 is a cross-sectional view of the carbon fiber composite hard felt cylinder in Example 1;

[0121] The carbon fiber cloth 1, the pitch-based carbon fiber hard felt 2, the graphite paper 3, and the PAN-based carbon fiber hard felt 4 are shown in the figure. DETAILED DESCRIPTION

[0122] The application will be further described in the following examples without limiting the application to the examples. The experimental methods in the following examples without specific conditions are selected according to the conventional methods and conditions or according to the commercial instructions.

[0123] The main raw materials and reagents used in the following examples and comparative examples are shown in Table 1:

[0124] Table 1

[0125]

[0126] In the following examples and comparative examples:

[0127] 1, the carbon content refers to the mass percentage of carbon element in the material, which is tested according to the standard GB / T31292-2014.

[0128] 2, the ash content refers to the mass percentage of impurities and ash in the carbon fiber composite hard felt, which is tested according to the standard YB / T 5146. The ash content refers to the weight percentage of impurities and ash in the carbon fiber. High ash content will reduce the strength, modulus, conductivity and corrosion resistance of carbon fiber, thereby affecting the quality and service life of the product. The specific calculation method is as follows:

[0129] Principle: the content of the sample burned to constant weight residue accounts for the mass of the sample

[0130]

[0131] In the formula:

[0132] W-ash content, mass fraction (ppm);

[0133] m0-sample mass, unit: gram (g);

[0134] m1-alumina boat mass, unit: gram (g);

[0135] m2-alumina boat and the mass of the residue after burning, unit: gram (g).

[0136] Example 1

[0137] The carbon fiber composite hard felt cylinder is prepared, including the following steps:

[0138] S1, preparation of carbon fiber composite hard felt precursor:

[0139] (1) Preparation of pitch-based composite soft felt layer:

[0140] ①Pitch-based carbon fiber soft felt was dipped in impregnation sizing liquid (10wt% of phenolic resin and the rest of water), and the excess impregnation sizing liquid was squeezed off, to obtain impregnation sizing pitch-based carbon fiber soft felt with impregnation amount of 110wt%;

[0141] ②The binder (phenolic resin 50wt%, carbon powder 20wt%, coupling agent 0.3wt%, and the rest of ethanol) was coated on both sides of graphite paper, and the single-sided coating amount was 300g / m 2 The impregnation sizing pitch-based carbon fiber soft felt was bonded to one side of the graphite paper through the binder;

[0142] ③The impregnation sizing pitch-based carbon fiber soft felt obtained in ① was rolled outside the solid shaft (diameter 780mm) until the outer diameter of the cylinder was 820mm;

[0143] ④The composite layer obtained in ② was further rolled outside the cylinder obtained in step ③, with the graphite paper on one side close to the cylinder, and the rolling was stopped when the outer diameter of the cylinder was 980mm.

[0144] (2) Preparation of PAN-based composite soft felt layer:

[0145] ①Pitch-based carbon fiber soft felt was dipped in impregnation sizing liquid (10wt% of phenolic resin and the rest of water), and the excess impregnation sizing liquid was squeezed off, to obtain impregnation sizing pitch-based carbon fiber soft felt with impregnation amount of 110wt%;

[0146] ②The binder (phenolic resin 50wt%, carbon powder 20wt%, coupling agent 0.3wt%, and the rest of ethanol) was coated on both sides of graphite paper, and the single-sided coating amount was 300g / m 2 The impregnation sizing pitch-based carbon fiber soft felt was bonded to one side of the graphite paper through the binder;

[0147] ③The composite layer obtained in step ② was further rolled outside the pitch-based composite soft felt layer obtained in step (1), with the graphite paper on one side close to the pitch-based composite soft felt layer, and the rolling was stopped when the outer diameter of the cylinder was 1020mm; to obtain a carbon fiber composite hard felt preform.

[0148] (3) Put the carbon fiber composite hard felt preform into a curing oven for primary curing, and then transfer it into a graphitization furnace for primary graphitization treatment. Then, according to the size requirement, machine it to the specification of D1000 / d800xH500 (here, the machining includes inner side machining, and removing the asphalt-based carbon fiber hard felt layer without graphite paper added in step S1-(1)-③ after subsequent curing and graphitization; and machining in the height direction), to obtain a carbon fiber composite hard felt. The primary curing temperature is 150℃, the time is 10h, and the atmosphere is air. The primary graphitization temperature is 2400℃, the time is 100h, and the atmosphere is argon.

[0149] S2, preparation of carbon fiber composite hard felt:

[0150] (1) Apply a binder (phenolic resin 50wt%, carbon powder 20wt%, coupling agent 0.3wt% and the balance of ethanol) to the inner and outer surfaces of the carbon fiber composite hard felt preform, with a single-sided coating amount of 600g / m 2 ; bond the carbon fiber cloth to the inner and outer surfaces of the carbon fiber composite hard felt preform through the binder to form a protective layer.

[0151] (2) Then, after secondary curing (200℃, 5h), simple trimming treatment and secondary graphitization (2400℃, 100h, atmosphere is argon), a carbon fiber composite hard felt cylinder is obtained, wherein the asphalt-based composite soft felt layer is converted into an asphalt-based composite hard felt layer, and the PAN-based composite soft felt layer is converted into a PAN-based composite hard felt layer.

[0152] The structure of the carbon fiber composite hard felt cylinder is shown in Figs. 1-3 , which includes an asphalt-based composite hard felt layer and a PAN-based composite hard felt layer stacked in order from the inside out; the asphalt-based composite hard felt layer includes, in order from the inside out, asphalt-based carbon fiber hard felt 2 (wherein the content of pyrolytic carbon is 5wt%), graphite paper 3 and asphalt-based carbon fiber hard felt 2 (wherein the content of pyrolytic carbon is 5wt%); the PAN-based composite hard felt layer includes, in order from the inside out, graphite paper 3 and PAN-based carbon fiber hard felt 4 (wherein the content of pyrolytic carbon is 5wt%); the inner and outer surfaces of the carbon fiber composite hard felt are respectively provided with carbon fiber cloth 1. It should be noted that, Figs. 1-3 this is only a schematic diagram and does not represent the actual number of layers in this embodiment, which is determined by the thickness of the layers and the outer diameter of the cylinder in each step.

[0153] Comparative Example 1

[0154] The main difference between this comparative example and Example 1 is that no graphite paper is used in this comparative example, and the specific steps are as follows:

[0155] S1, preparation of carbon fiber composite hard felt preform:

[0156] (1) Preparation of asphalt-based composite soft felt:

[0157] ① The asphalt-based carbon fiber soft felt is immersed in the impregnation sizing solution (10wt% of phenolic resin and the balance of water), and the excess impregnation sizing solution is squeezed off, to obtain the impregnation-sized asphalt-based carbon fiber soft felt with an impregnation amount of 110wt%.

[0158] ② The binder (50wt% of phenolic resin, 20wt% of carbon powder and 0.3wt% of coupling agent) is coated on both sides of the impregnation-sized asphalt-based carbon fiber soft felt, and the single-sided coating amount is 300g / m 2 .

[0159] ③ The impregnation-sized asphalt-based carbon fiber soft felt is rolled outside the solid shaft (diameter of 780mm) until the outer diameter of the cylinder is 980mm.

[0160] (2) Preparation of PAN-based composite soft felt:

[0161] ① The PAN-based carbon fiber soft felt is immersed in the impregnation sizing solution (10wt% of phenolic resin and the balance of water), and the excess impregnation sizing solution is squeezed off, to obtain the impregnation-sized PAN-based carbon fiber soft felt with an impregnation amount of 110wt%.

[0162] ② The binder (50wt% of phenolic resin, 20wt% of carbon powder and 0.3wt% of coupling agent) is coated on both sides of the impregnation-sized PAN-based carbon fiber soft felt, and the single-sided coating amount is 300g / m 2 .

[0163] ③ The impregnation-sized PAN-based carbon fiber soft felt is continuously rolled until the outer diameter of the cylinder is 1020mm, to obtain the carbon fiber composite hard felt preform.

[0164] (3) The carbon fiber composite hard felt preform is placed in a curing box for primary curing, and then transferred into a graphitization furnace for primary graphitization treatment, to obtain the carbon fiber composite hard felt precursor; wherein the primary curing temperature is 150℃, the time is 10h, and the atmosphere is air; the primary graphitization temperature is 2400℃, the time is 100h, and the atmosphere is argon.

[0165] S2, Preparation of carbon fiber composite hard felt:

[0166] (1) The binder is coated on the inner and outer surfaces of the carbon fiber composite hard felt precursor, and the single-sided coating amount is 300g / m

[0167] (2) Then, after secondary curing (200°C, 5h), secondary graphitization (2400°C, 100h, atmosphere: argon), a carbon fiber composite hard felt cylinder is obtained. According to the size requirements, it is machined to the specification D1000 / d800xH500.

[0168] The structure of the carbon fiber composite hard felt cylinder includes pitch-based carbon fiber hard felt (in which the content of pyrolytic carbon is 5wt%) and PAN-based carbon fiber hard felt (in which the content of pyrolytic carbon is 5wt%); the inner and outer surfaces of the carbon fiber composite hard felt are respectively provided with carbon fiber cloth.

[0169] Comparative Example 2

[0170] The main difference from Example 1 is that in this comparative example, the carbon fibers are all pitch-based carbon fibers, and the specific steps are as follows:

[0171] S1, preparation of carbon fiber composite hard felt precursor:

[0172] (1) Preparation of pitch-based composite soft felt layer:

[0173] ① The pitch-based carbon fiber soft felt is immersed in the impregnation sizing solution (10wt% phenolic resin and the balance of water), and the excess impregnation sizing solution is squeezed out, to obtain the impregnation sizing pitch-based carbon fiber soft felt with an impregnation amount of 110wt%;

[0174] ② The binder (phenolic resin 50wt%, carbon powder 20wt% and coupling agent 0.3wt%, the balance is ethanol) is coated on both sides of the graphite paper, and the single-sided coating amount is 300g / m 2 ; the impregnation sizing pitch-based carbon fiber soft felt is adhered to one side of the graphite paper through the binder;

[0175] ③ The impregnation sizing pitch-based carbon fiber soft felt obtained in ① is wound outside the solid shaft (diameter 780mm) to a cylinder outer diameter of 820mm;

[0176] ④ The composite layer obtained in ② is further wound outside the cylinder obtained in step ③, with the graphite paper side close to the cylinder, and wound to a cylinder outer diameter of 1020mm; to obtain a carbon fiber composite hard felt preform.

[0177] (2) Put the carbon fiber composite hard felt preform into a curing box for primary curing, and then transfer it into a graphitization furnace for primary graphitization treatment. Then, according to the size requirement, machine it to the specification of D1000 / d800xH500 (the machining here includes inside machining, and removes the asphalt-based carbon fiber hard felt layer without graphite paper added in step S1-(1)-③ after subsequent curing and graphitization; also includes machining in the height direction), to obtain a carbon fiber composite hard felt preform; wherein the primary curing temperature is 150℃, the time is 10h, and the atmosphere is air; the primary graphitization temperature is 2400℃, the time is 100h, and the atmosphere is argon.

[0178] S2, preparation of carbon fiber composite hard felt:

[0179] (1) Apply a binder (phenolic resin 50wt%, carbon powder 20wt%, coupling agent 0.3wt% and the balance of ethanol) to the inner and outer surfaces of the carbon fiber composite hard felt preform, with a single-sided coating amount of 600g / m 2 ; bond the carbon fiber cloth to the inner and outer surfaces of the carbon fiber composite hard felt preform through the binder to form a protective layer.

[0180] (2) Then, after secondary curing (200℃, 5h), simple trimming treatment and secondary graphitization (2400℃, 100h, atmosphere is argon), a carbon fiber composite hard felt cylinder is obtained, wherein the asphalt-based composite soft felt layer is converted into an asphalt-based composite hard felt layer.

[0181] The carbon fiber composite hard felt cylinder structure includes an asphalt-based carbon fiber hard felt (wherein the content of pyrolytic carbon is 5wt%), and carbon fiber cloth is arranged on the inner and outer surfaces of the carbon fiber composite hard felt.

[0182] Comparative Example 3

[0183] The main difference from Example 1 is that in this comparative example, the carbon fibers are all PAN-based carbon fibers, and the specific steps are as follows:

[0184] S1, preparation of carbon fiber composite hard felt preform:

[0185] (1) Preparation of PAN-based composite soft felt layer:

[0186] ① Dip the PAN-based composite soft felt in a sizing solution (10wt% of phenolic resin and the balance of water), and squeeze off the excess sizing solution, to obtain an asphalt-based carbon fiber soft felt with a sizing amount of 110wt%;

[0187] ② Apply a binder (phenolic resin 50wt%, carbon powder 20wt% and coupling agent 0.3wt%, with the balance of ethanol) to both sides of the graphite paper, with a single-sided coating amount of 300g / m2 ; the impregnated and sized PAN-based composite soft felt is adhered to one side of the graphite paper by an adhesive;

[0188] ③The impregnated and sized PAN-based composite soft felt obtained in ① is rolled outside a solid shaft (diameter 780 mm) to a cylindrical outer diameter of 820 mm;

[0189] ④The composite layer obtained in ② is further rolled outside the cylinder obtained in ③, with the graphite paper side close to the cylinder, to a cylindrical outer diameter of 1020 mm; a carbon fiber composite hard felt preform is obtained.

[0190] (2) The carbon fiber composite hard felt preform is placed in a curing oven for primary curing, and then transferred to a graphitization furnace for primary graphitization treatment, and then machined to a specification of D1000 / d800xH500 according to the size requirement (the machining here includes inside machining, and removal of the PAN-based carbon fiber hard felt layer without graphite paper obtained after subsequent curing and graphitization in step S1-(1)-③; and machining in the height direction), to obtain a carbon fiber composite hard felt precursor; wherein the primary curing temperature is 150°C, the time is 10h, and the atmosphere is air; the primary graphitization temperature is 2400°C, the time is 100h, and the atmosphere is argon.

[0191] S2, preparation of a carbon fiber composite hard felt:

[0192] (1) An adhesive (phenolic resin 50wt%, carbon powder 20wt%, coupling agent 0.3wt% and the balance of ethanol) is coated on the inner and outer surfaces of the carbon fiber composite hard felt precursor, and the single-sided coating amount is 600g / m 2 ; the carbon fiber cloth is adhered to the inner and outer surfaces of the carbon fiber composite hard felt precursor by an adhesive to form a protective layer.

[0193] (2) Then, after secondary curing (200°C, 5h), simple trimming treatment and secondary graphitization (2400°C, 100h, argon atmosphere), a carbon fiber composite hard felt cylinder is obtained, and the PAN-based composite soft felt layer is converted into a PAN-based composite hard felt layer.

[0194] The structure of the carbon fiber composite hard felt cylinder includes a PAN-based carbon fiber hard felt (wherein the content of pyrolytic carbon is 5wt%), and carbon fiber cloth is arranged on the inner and outer surfaces of the carbon fiber composite hard felt, respectively.

[0195] Effect implementation example 1: test of bending strength and thickness direction pressure resistance strength

[0196] Test object: carbon fiber composite hard felt cylinders in example 1 and comparative examples 1-3.

[0197] Test method: The bending strength is tested according to the standard JB / T8133.7-2013, and the compressive strength is tested according to the standard GB / T1431.

[0198] Effect Example 2: Thermal conductivity test

[0199] Test object: The carbon fiber composite hard felt cylinder in Example 1 and Comparative Examples 1-3.

[0200] Test method: The thermal conductivity is tested according to the flat plate steady state method, and the temperature range for testing the thermal conductivity is 800-2000℃. The specific test method principle is as follows:

[0201] The heat conduction Q through the flat plate in one-dimensional steady state is proportional to the temperature difference Δt of the two sides of the flat plate, the thickness h of the flat plate, and the thermal conductivity λ.

[0202] The stable heat conduction through the thin-walled flat plate is:

[0203] Q = (λ*Δt*S) / h, unit: W

[0204] If the temperature difference Δt of the two sides of the flat plate is Δt = 1 / 2(T R +T L ), the thickness h of the flat plate, the heat conduction area S perpendicular to the heat flow direction, and the heat flow Q through the flat plate are determined, then the thermal conductivity can be obtained according to the following formula:

[0205] λ = (Q*h) / (Δt*S), unit: W / (m·K)

[0206] The thermal conductivity obtained by the above formula is the thermal conductivity of the material at the average temperature at that time, and the average temperature is

[0207] Δt = 1 / 2(T R +T L ), unit: K

[0208] Under different temperature and temperature difference conditions, the corresponding λ can be obtained, and the relationship curve can be obtained.

[0209] The test results in Effect Example 1 and Comparative Examples 1-3 are shown in Table 2.

[0210] Table 2

[0211]

[0212]

[0213] In Table 2, the density of the carbon fiber composite hard felt cylinder is slightly greater than the density of the pitch-based composite hard felt layer and the density of the PAN-based composite hard felt layer, because when the carbon fiber cloth is attached to both sides of the carbon fiber composite hard felt precursor, a high-density adhesive and carbon fiber cloth are introduced.

[0214] Example 1

[0215] The carbon fiber composite hard felt in Example 1 is used as a heat insulation material in a vacuum high-pressure furnace. In use, the protective layer (carbon fiber cloth) of the pitch-based composite hard felt layer is close to the center of the vacuum high-pressure furnace, and the protective layer (carbon fiber cloth) of the PAN-based composite hard felt layer is close to the furnace wall.

[0216] When the pressure of the high-pressure gas is 10 MPa, the carbon fiber composite hard felt does not crack during the process of filling the high-pressure gas, has a small amount of dust, and has good resistance to gas flow erosion. The carbon fiber composite hard felt can be used in a vacuum high-pressure furnace for more than 3 years.

[0217] In Comparative Example 1, there is no graphite paper, and the material is porous. The pressure retention performance in the furnace is poor, and the pressure in the furnace during the process of filling the high-pressure gas cannot meet the requirements of equipment use, making it difficult to put into use.

[0218] In Comparative Example 2, the performance is basically equivalent to Example 1, but the price of the pitch-based carbon fiber soft felt is 1 time higher than that of the PAN-based carbon fiber soft felt. Under the condition that the overall performance is basically equivalent, the cost performance of Example 1 is higher.

[0219] In Comparative Example 3, the PAN-based carbon fiber has a large thermal conductivity, and the equipment has a large power consumption. In addition, the PAN-based carbon fiber is prone to cracking during the process of filling the high-pressure gas, and the amount of dust is large, which makes it impossible for the carbon fiber composite hard felt in Comparative Example 3 to be used in a vacuum high-pressure furnace for a long time.

Claims

1. A carbon fiber composite rigid felt, characterized in that, It consists of a layer of bitumen-based composite rigid felt and a layer of PAN-based composite rigid felt stacked sequentially; The carbon fiber composite hard felt has a carbon content of not less than 99 wt%, where carbon content refers to the mass percentage of carbon element in the material; the ash content of the carbon fiber composite hard felt is less than 20 ppm, where ash content refers to the mass percentage of impurities and ash remaining in the carbon fiber composite hard felt. The asphalt-based composite rigid felt layer comprises at least two layers of asphalt-based carbon fiber rigid felt and at least one layer of graphite paper, wherein the asphalt-based carbon fiber rigid felt and the graphite paper are alternately arranged; The PAN-based composite rigid felt layer comprises at least one layer of PAN-based carbon fiber rigid felt and at least one layer of graphite paper, wherein the PAN-based composite rigid felt layer and the graphite paper are alternately arranged; The side of the asphalt-based composite hard felt layer closest to the PAN-based composite hard felt layer is asphalt-based carbon fiber hard felt, and the side of the PAN-based composite hard felt layer closest to the asphalt-based composite hard felt layer is graphite paper. A protective layer is provided on the side of the asphalt-based composite hard felt layer away from the PAN-based composite hard felt layer.

2. The carbon fiber composite rigid felt according to claim 1, characterized in that, The thickness of the bitumen-based composite hard felt layer is 80-100 mm; And / or, the thickness of the PAN-based composite rigid felt layer is 10-24 mm; And / or, in the bitumen-based composite rigid felt layer, the thickness of each bitumen-based carbon fiber rigid felt layer is independently 8-10 mm; And / or, in the PAN-based composite rigid felt layer, the thickness of each PAN-based carbon fiber rigid felt layer is independently 5-8 mm; And / or, in the bitumen-based composite hard felt layer, the thickness of the graphite paper is 0.2-0.7 mm; And / or, in the PAN-based composite rigid felt layer, the thickness of the graphite paper is 0.2-0.7 mm; And / or, the thickness ratio of the bitumen-based composite rigid felt layer to the PAN-based composite rigid felt layer is at least 2:

1.

3. The carbon fiber composite rigid felt according to claim 2, characterized in that, In the asphalt-based composite rigid felt layer, the thickness of each layer of asphalt-based carbon fiber rigid felt is the same; And / or, in the PAN-based composite rigid felt layer, the thickness of each PAN-based carbon fiber rigid felt layer is the same; And / or, in the bitumen-based composite hard felt layer, the thickness of the graphite paper is 0.3 mm; And / or, in the PAN-based composite rigid felt layer, the thickness of the graphite paper is 0.3 mm.

4. The carbon fiber composite rigid felt according to claim 1, characterized in that, The carbon content of each layer of the pitch-based carbon fiber rigid felt is independently not less than 99 wt%; And / or, the carbon content of each layer of the PAN-based carbon fiber rigid felt is independently not less than 99 wt%; And / or, the carbon in the pitch-based carbon fiber rigid felt includes pitch-based carbon fibers and pyrolyzed carbon adhering to the pitch-based carbon fibers; And / or, the carbon in the PAN-based carbon fiber rigid felt includes PAN-based carbon fibers and pyrolyzed carbon attached to the PAN-based carbon fibers; And / or, the carbon fiber composite rigid felt has a carbon content of 99.8 wt%, where carbon content refers to the percentage of carbon element by mass in the material; And / or, the density of the bitumen-based composite rigid felt layer is 0.18-0.20 g / cm³. 3 ; And / or, the density of the PAN-based composite rigid felt layer is 0.16-0.18 g / cm³. 3 ; And / or, the density of the carbon fiber composite rigid felt is 0.16-0.30 g / cm³. 3 ; And / or, in the bitumen-based composite rigid felt layer and the PAN-based composite rigid felt layer, the areal density of each layer of graphite paper is independently 200-400 g / m³. 2 ; And / or, in the bitumen-based composite hard felt layer and the PAN-based composite hard felt layer, the material of each layer of graphite paper is independently flake graphite; And / or, the thermal conductivity of each layer of the pitch-based carbon fiber rigid felt is independently 0.1-0.5 W / m·K; And / or, the thermal conductivity of each layer of the PAN-based carbon fiber rigid felt is independently 0.2-0.8 W / m·K; And / or, the thermal conductivity of the carbon fiber composite rigid felt does not exceed 0.45 W / m·K; And / or, the ash content of the carbon fiber composite hard felt is 13 ppm, where ash content refers to the mass percentage of impurities and ash remaining in the carbon fiber composite hard felt. And / or, the thickness direction compressive strength of the carbon fiber composite rigid felt is ≥1.0 MPa; And / or, the flexural strength of the carbon fiber composite rigid felt is ≥1.5 MPa; And / or, the carbon fiber composite rigid felt is cylindrical, and the bitumen-based composite rigid felt layer is located inside the cylinder.

5. The carbon fiber composite rigid felt according to claim 4, characterized in that, In the asphalt-based composite rigid felt layer, the carbon content of each layer of asphalt-based carbon fiber rigid felt is the same; And / or, in the PAN-based composite rigid felt layer, the carbon content of each PAN-based carbon fiber rigid felt layer is the same; And / or, in the pitch-based carbon fiber rigid felt, the mass of the pyrolyzed carbon is 1-10 wt% of the mass of the pitch-based carbon fiber rigid felt; And / or, in the PAN-based carbon fiber rigid felt, the mass of the pyrolyzed carbon is 1-10 wt% of the mass of the PAN-based carbon fiber rigid felt; And / or, the density of the carbon fiber composite rigid felt is 0.20 g / cm³. 3 ; And / or, in the bitumen-based composite hard felt layer and the PAN-based composite hard felt layer, the areal density of each layer of graphite paper is the same; And / or, in the bitumen-based composite hard felt layer and the PAN-based composite hard felt layer, the material of each layer of graphite paper is flake graphite; And / or, in the bitumen-based composite rigid felt layer, each layer of bitumen-based carbon fiber rigid felt has the same thermal conductivity; And / or, in the PAN-based composite rigid felt layer, each layer of PAN-based carbon fiber rigid felt has the same thermal conductivity; And / or, the thermal conductivity of the carbon fiber composite rigid felt is 0.41 W / m·K; And / or, the thickness direction compressive strength of the carbon fiber composite rigid felt is 1.2 MPa.

6. The carbon fiber composite rigid felt according to claim 5, characterized in that, In the pitch-based carbon fiber rigid felt, the mass of the pyrolyzed carbon is 5 wt% of the mass of the pitch-based carbon fiber rigid felt; And / or, in the PAN-based carbon fiber rigid felt, the mass of the pyrolyzed carbon is 5 wt% of the mass of the PAN-based carbon fiber rigid felt.

7. The carbon fiber composite rigid felt according to claim 1, characterized in that, The protective layer on the side of the bitumen-based composite rigid felt layer away from the PAN-based composite rigid felt layer is the same as the protective layer on the side of the PAN-based composite rigid felt layer away from the bitumen-based composite rigid felt layer. And / or, the side of the bitumen-based composite rigid felt layer away from the PAN-based composite rigid felt layer is graphite paper, which serves as a protective layer. And / or, the side of the PAN-based composite rigid felt layer away from the bitumen-based composite rigid felt layer is graphite paper, which serves as a protective layer. And / or, at least one end face of the carbon fiber composite rigid felt is provided with a protective layer; And / or, the protective layer is carbon fiber cloth or carbon shell.

8. The carbon fiber composite rigid felt according to claim 7, characterized in that, The carbon fiber composite rigid felt has a protective layer on both ends; And / or, the carbon fiber cloth has a carbon content of not less than 99 wt%; And / or, the thickness of the carbon fiber cloth is 0.5-0.7 mm; And / or, the areal density of the carbon fiber cloth is 200-600 g / m². 2 ; And / or, the thickness of the carbon shell is 0.8-1.5 mm; And / or, the mass of the carbon shell is 1-10 wt% of the mass of the carbon fiber composite rigid felt.

9. The carbon fiber composite rigid felt according to claim 8, characterized in that, The two end faces of the carbon fiber composite rigid felt are provided with the same protective layer; And / or, the areal density of the carbon fiber cloth is 500 g / m². 2 ; And / or, the mass of the carbon shell is 5 wt% of the mass of the carbon fiber composite rigid felt.

10. A method for preparing carbon fiber composite rigid felt according to any one of claims 1-9, characterized in that, It includes the following steps: S1. The carbon fiber composite rigid felt preform is subjected to one curing and one graphitization process sequentially to obtain the carbon fiber composite rigid felt precursor; wherein... The carbon fiber composite rigid felt preform includes a pitch-based composite soft felt layer and a PAN-based composite soft felt layer stacked sequentially. The asphalt-based composite soft felt layer includes at least one layer of asphalt-based carbon fiber soft felt impregnated with mortar and at least one layer of graphite paper, wherein the asphalt-based carbon fiber soft felt impregnated with mortar and the graphite paper are alternately arranged. The PAN-based composite soft felt layer includes at least one layer of PAN-based carbon fiber soft felt impregnated with mortar and at least one layer of graphite paper, wherein the PAN-based carbon fiber soft felt impregnated with mortar and the graphite paper are alternately arranged. The side of the asphalt-based composite soft felt layer closest to the PAN-based composite soft felt layer is an asphalt-based carbon fiber soft felt impregnated with adhesive, and the side of the PAN-based composite hard felt layer closest to the asphalt-based composite soft felt layer is graphite paper. S2. A protective layer is provided on the carbon fiber composite hard felt precursor, and it is subsequently subjected to secondary curing and secondary graphitization; wherein, the protective layer is respectively provided on the side of the asphalt-based composite soft felt layer away from the PAN-based composite soft felt layer and on the side of the PAN-based composite hard felt layer away from the asphalt-based composite hard felt layer.

11. The method for preparing carbon fiber composite rigid felt according to claim 10, characterized in that, In step S1, the areal density of each layer of the pitch-based carbon fiber felt is independently 800-1400 g / m³. 2 ; And / or, in step S1, the thickness of each layer of the pitch-based carbon fiber felt is independently 10-20 mm; And / or, in step S1, the carbon content of each layer of the pitch-based carbon fiber felt is independently ≥99.5 wt%; And / or, in step S1, the areal density of each layer of the PAN-based carbon fiber felt is independently 1000-1200 g / m². 2 ; And / or, in step S1, the thickness of each layer of the PAN-based carbon fiber soft felt is independently 5-10 mm; And / or, in step S1, the carbon content of each layer of the PAN-based carbon fiber felt is independently ≥99.5 wt%; And / or, in step S1, the impregnation amount of the pitch-based carbon fiber soft felt is 50wt%-200wt%; wherein, the impregnation amount refers to the percentage of the impregnation adhesive in the pitch-based carbon fiber soft felt by mass. And / or, in step S1, the impregnation amount of the PAN-based carbon fiber soft felt is 50wt%-200wt%; wherein, the impregnation amount refers to the percentage of the mass of the impregnation adhesive in the PAN-based carbon fiber soft felt. And / or, the impregnation and coating operation is to impregnate the carbon fiber soft felt in the impregnation and coating solution and then squeeze out the excess impregnation and coating solution; And / or, in step S1, the alternating arrangement is implemented by bonding carbon fiber soft felt and graphite paper together and then rolling them up.

12. The method for preparing carbon fiber composite rigid felt according to claim 11, characterized in that, In step S1, the areal density of each layer of pitch-based carbon fiber felt is the same. And / or, in step S1, the thickness of each layer of the pitch-based carbon fiber felt is independently 15 mm. And / or, in step S1, the thickness of each layer of pitch-based carbon fiber felt is the same. And / or, in step S1, the carbon content of each layer of pitch-based carbon fiber felt is the same. And / or, in step S1, the areal density of each layer of PAN-based carbon fiber soft felt is the same; And / or, in step S1, the thickness of each layer of PAN-based carbon fiber soft felt is the same; And / or, in step S1, the carbon content of each layer of PAN-based carbon fiber felt is the same; And / or, in step S1, the impregnation amount of the pitch-based carbon fiber soft felt is 90wt%-110wt%; wherein, the impregnation amount refers to the percentage of the impregnation adhesive in the pitch-based carbon fiber soft felt by mass. And / or, in step S1, the impregnation amount of the PAN-based carbon fiber soft felt is 90wt%-110wt%; wherein, the impregnation amount refers to the percentage of the mass of the impregnation adhesive in the PAN-based carbon fiber soft felt. And / or, in step S1, the impregnation coating solution includes resin and solvent; And / or, in step S1, the impregnation and coating solution of the pitch-based carbon fiber soft felt is the same as that of the PAN-based carbon fiber soft felt.

13. The method for preparing carbon fiber composite rigid felt according to claim 12, characterized in that, In step S1, the impregnation amount of the pitch-based carbon fiber soft felt is 100wt%; wherein, the impregnation amount refers to the percentage of the impregnation adhesive in the pitch-based carbon fiber soft felt by mass. And / or, in step S1, the impregnation amount of the PAN-based carbon fiber soft felt is 100wt%; wherein, the impregnation amount refers to the percentage of the mass of the impregnation adhesive in the PAN-based carbon fiber soft felt. And / or, in step S1, the resin is a phenolic resin; And / or, in step S1, the resin content is 6wt%-60wt%. And / or, in step S1, the solvent is water, ethanol, or isopropanol.

14. The method for preparing carbon fiber composite rigid felt according to claim 13, characterized in that, In step S1, the phenolic resin is a thermosetting phenolic resin; And / or, in step S1, the content of the resin is 6wt%-11wt%.

15. The method for preparing carbon fiber composite rigid felt according to claim 14, characterized in that, In step S1, the phenolic resin is an aminophenolic resin; And / or, in step S1, the content of the resin is 8 wt% or 10 wt%.

16. The method for preparing carbon fiber composite rigid felt according to claim 10, characterized in that, In step S1, the temperature for the first curing is 100-200℃; And / or, in step S1, the curing time for one time is 3-10 h; And / or, in step S1, the atmosphere for the primary curing is air; And / or, in step S1, the temperature of the primary graphitization is 2000-2400℃; And / or, in step S1, the time for one graphitization is 60-100 h; And / or, in step S1, the vacuum degree of the primary graphitization is below 200 Pa; And / or, in step S1, the atmosphere for the primary graphitization is an inert atmosphere; And / or, in step S2, the temperature of the secondary curing is 100-200℃; And / or, in step S2, the secondary curing time is 3-5 hours; And / or, in step S2, the temperature of the secondary graphitization is 2000-2400℃; And / or, in step S2, the secondary graphitization time is 60-100 h; And / or, in step S2, the atmosphere for the secondary graphitization is an inert atmosphere; And / or, in step S2, the vacuum degree of the secondary graphitization is below 200 Pa; And / or, in step S2, the protective layer is also disposed on at least one end face of the carbon fiber composite rigid felt precursor.

17. The method for preparing carbon fiber composite rigid felt according to claim 16, characterized in that, In step S1, the temperature for the first curing is 150°C; And / or, in step S1, the atmosphere for the primary graphitization is argon; And / or, in step S2, the atmosphere for the secondary graphitization is argon.

18. The method for preparing carbon fiber composite rigid felt according to claim 10, characterized in that, The asphalt-based composite soft felt layer and the PAN-based composite soft felt layer, the asphalt-based carbon fiber soft felt impregnated with adhesive and the graphite paper in the asphalt-based composite soft felt layer, the PAN-based carbon fiber soft felt impregnated with adhesive and the graphite paper in the PAN-based composite soft felt layer, and the carbon fiber composite hard felt precursor and the protective layer are all bonded together using adhesives.

19. The method for preparing carbon fiber composite rigid felt according to claim 18, characterized in that, The binder comprises the following components by weight percentage: 30wt%-80wt% phenolic resin, 5wt%-30wt% carbon powder, 0.1wt%-0.5wt% coupling agent, with the balance being solvent; And / or, the amount of adhesive applied is 200-1000 g / m². 2 The coating amount refers to the coating amount on one side only.

20. The method for preparing carbon fiber composite rigid felt according to claim 19, characterized in that, The phenolic resin content in the adhesive is 50 wt%. And / or, in the adhesive, the carbon powder content is 20 wt%; And / or, in the adhesive, the coupling agent content is 0.3 wt%; And / or, in the adhesive, the solvent is ethanol; And / or, in the adhesive, the phenolic resin is a thermosetting phenolic resin; And / or, in the binder, the carbon powder is carbon powder with a particle size of 500-1000 mesh and / or nano carbon powder; And / or, in the adhesive, the coupling agent is a BYK series coupling agent; And / or, the amount of adhesive applied is 300 g / m². 2 500 g / m 2 600 g / m 2 Or 800 g / m 2 The coating amount refers to the coating amount on one side; And / or, in the bitumen-based composite soft felt layer, between the impregnated bitumen-based carbon fiber soft felt and the graphite paper, the amount of adhesive applied is 300 g / m². 2 ; And / or, in the PAN-based composite soft felt layer, between the impregnated and sized PAN-based carbon fiber soft felt and the graphite paper, the amount of adhesive applied is 300 g / m². 2 ; And / or, the amount of adhesive applied between the carbon fiber composite rigid felt precursor and the protective layer is 600 g / m². 2 .

21. The method for preparing carbon fiber composite rigid felt according to claim 20, characterized in that, In the adhesive, the phenolic resin is an aminophenolic resin; And / or, in the adhesive, the coupling agent is BYK-C8001, BYK-C8002 or BYK-C8013.

22. An application of the carbon fiber composite rigid felt as described in any one of claims 1-9 as a heat insulation material in a vacuum high-pressure furnace.

23. The application of the carbon fiber composite rigid felt according to claim 22, characterized in that, When in use, the internal pressure of the vacuum high-pressure furnace is 1-10 MPa.

Images