CN115636684B - Preparation method of carbon fiber heat-insulating hard felt - Google Patents
Preparation method of carbon fiber heat-insulating hard felt Download PDFInfo
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Abstract
The invention provides a preparation method of a carbon fiber heat-insulating hard felt, which comprises the following steps: fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber; chopping the pre-oxidized fiber, mixing with a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid; or cutting the pre-oxidized fiber, mixing with a binder and a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid; filtering out the liquid in the dispersion liquid, drying, pressurizing and curing, and then performing heat treatment to obtain the composite material; the pressure of the press curing is 0.1MPa or more and 1MPa or less.
Description
Technical Field
The invention relates to the field of rigid carbon fiber materials and preparation methods, in particular to a preparation method of a carbon fiber heat-insulating hard felt.
Background
The low-density rigid carbon fiber material is a low-density carbon/carbon composite material obtained by taking carbon fibers as a framework, taking high-carbon-residue-rate precursors such as resin, asphalt and the like as an adhesive and carbonizing at a high temperature. The material has the characteristics of low density, high porosity, low thermal conductivity, good high-temperature stability and the like, and is an excellent heat preservation and insulation material. The carbon fiber heat-insulating hard felt is a low-density rigid carbon fiber material. It is not only suitable for manufacturing the substrate of light heat-insulating and ablation-resistant heat-protecting material, but also widely used as the heat-insulating material of vacuum or non-oxidizing atmosphere high-temperature equipment represented by a single crystal growth furnace, an epitaxial growth furnace and the like. In addition, the activated carbon fiber heat-insulating hard felt can be also prepared into filter adsorption materials such as molecular sieves and the like.
The common low-density carbon fiber heat-insulating hard felt can be mainly divided into two types, namely lamination curing molding and wet compression molding. The lamination curing molding is mainly realized by using a soft carbon felt dipping compression molding process. However, the carbon fiber hard felt manufactured by the dip molding process has the defects of high energy consumption, low strength among carbon fiber hard felt layers, easiness in cracking, low service life, high binder content, poor oxidation resistance and the like. The wet compression molding is mainly to prepare uniform dispersion slurry by using chopped carbon fibers, a binder, a dispersing agent and the like, and obtain a blank body through processes of drying, solidification, carbonization and the like by using a vacuum suction filtration or filter pressing molding method. The carbon fiber hard felt obtained by the method has the advantages of good integrity, difficult layering, large density adjustable range and strong designability. Uniform dispersion of the chopped carbon fibers and firm bonding between the fibers are critical to achieving high performance product quality. The poor dispersibility of the carbon fiber in the solution system is mainly due to the fact that the carbon fiber is small in diameter, large in surface area and easy to aggregate, and meanwhile, the carbon fiber is small in surface active group and low in surface activity, so that the dispersion performance of the carbon fiber is affected. Thus, there is a method of adding an organic solvent and a binder compatible with the organic solvent to the system. However, the method for adding the organic solvent has relatively single effect, has certain harm or hidden danger to the environment and safety, and can easily cause certain influence on the strength of the product and the uniformity of the heat insulation performance due to the gravity action of the liquid bonding system during carbonization.
In view of this, a new solution is needed to solve the above technical problems.
Disclosure of Invention
The invention aims to provide a low-density rigid carbon fiber material, which adopts isotropic pitch-based pre-oxidized fibers as raw material fibers, and the abundant surface functional groups of the isotropic pitch-based pre-oxidized fibers are favorable for realizing uniform dispersion of fibers in space, so that the heat-insulating pitch-based carbon fiber felt with adjustable thickness and density can be obtained; the method has the advantages of simple preparation process, safety, environmental protection, excellent heat insulation effect, strong designability, stable quality, high cost performance and capability of meeting the requirement of large-scale production.
In order to achieve the above purpose, the invention adopts the following technical means:
a preparation method of a carbon fiber heat-insulating hard felt comprises the following steps:
fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber;
chopping the pre-oxidized fiber, mixing with a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid; or alternatively
Chopping the pre-oxidized fiber, mixing with a binder and a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid;
filtering out the liquid in the dispersion liquid, drying, pressurizing and curing, and then performing heat treatment to obtain the composite material;
the pressure of the press curing is 0.1MPa or more and 1MPa or less.
The outer diameter of the asphalt fiber is 7-60 mu m;
the length of the asphalt fiber after being cut is 0.5-10 mm;
the pitch fiber is an isotropic pitch fiber.
The mass ratio of the binder to the pre-oxidized fiber in the dispersion liquid is 0.25-1: 1, a step of;
the mass ratio of the dispersant to the pre-oxidized fiber is 0-0.05: 1, a step of;
the mass ratio of the liquid medium to the pre-oxidized fiber is 20-100: 1.
the dispersing agent comprises at least one of methyl cellulose, sodium carboxymethyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, polyacrylamide or polyvinyl alcohol.
The binder is selected from one of phenolic resin, asphalt, furan resin, urea resin, epoxy resin, vinyl ester resin, polyethylene, polypropylene, ethylene propylene copolymer, polyamide, polystyrene or acrylic resin;
the binder satisfies Dv50∈ (1, 10); and is also provided with
Satisfaction of the binder Dv97 e (7, 36); and is also provided with
The binder satisfies a Dv97/Dv50 of less than 7.
The temperature of the pressurizing and curing is 150-280 ℃;
the time of the pressurizing and curing is 0.5-2 h.
The temperature of the heat treatment is 1000-2800 ℃;
the heating rate of the heat treatment is 0.1-50 ℃/min.
The density of the carbon fiber heat-insulating hard felt is 0.1-0.3 g/cm 3 ；
The thermal conductivity of the carbon fiber heat-insulating hard felt is less than or equal to 0.3W/(m.K).
Compared with the prior art, the invention has the following technical effects:
the invention adopts the non-carbonized isotropic asphalt-based pre-oxidized fiber as the raw material, and the functional groups (carboxyl, hydroxyl and the like) with rich surfaces have certain hydrophilicity, so that the non-carbonized isotropic asphalt-based pre-oxidized fiber has better dispersibility in water or polar solvent, and is favorable for realizing uniform dispersion of fibers in space.
The method provided by the invention realizes the density and layered distribution degree of the material by adjusting the pressure, and can obtain the carbon fiber felt with adjustable thickness and density, which is beneficial to meeting different application requirements.
According to the invention, the strength, the heat preservation and the uniformity of the low-density carbon/carbon composite material heat preservation material are further improved and the comprehensive performance is improved by adjusting the proportion of the isotropic pitch-based pre-oxidized fiber dispersion liquid and the molding solidification and carbonization process conditions thereof.
The preparation technology of the rigid carbon fiber heat-insulating hard felt provided by the invention has the advantages of simple process, safety, environmental protection, excellent heat insulation effect, strong designability, stable quality and high cost performance, and can meet the requirement of large-scale production.
Drawings
In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described.
FIG. 1 shows an infrared spectrum of pitch-based carbon fibers, pitch-based pre-oxidized fibers, and pitch fiber precursors;
fig. 2 shows a schematic drawing of a sample of carbon fiber mat test samples.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
The invention provides a preparation method of a carbon fiber heat-insulating hard felt, which comprises the following steps:
fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber; chopping the pre-oxidized fiber, mixing with a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid; or cutting the pre-oxidized fiber, mixing with a binder and a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid; filtering out the liquid in the dispersion liquid, drying, pressurizing and solidifying, and performing heat treatment to obtain the final product.
The invention adopts the asphalt pre-oxidized fiber as the raw material to prepare the carbon fiber heat-preserving hard felt, and can improve the performance of the prepared carbon fiber heat-preserving hard felt. Carbonization of the pre-oxidized fibers is typically performed by heating the pre-oxidized fibers to 1400-1600 ℃ under vacuum or high purity inert atmosphere to remove non-carbon elements such as C, H, N from the pre-oxidized fibers and thereby carbonize the fibers. The preoxidized fiber generates a series of complex physical and chemical changes in the carbonization process, dehydration and dehydrogenation reactions occur among molecules, and main chain, side chain and terminal groups are decomposed to release and remove H 2 O、NH 3 、CO、CO 2 、N 2 And small molecules, and the diameter and density of the fiber can change significantly during carbonization. It can be seen from fig. 1 that the functional groups of the pre-oxidized fibers are relatively close to the binder pitch feedstock, while the carbonized fibers have been progressively freed from non-carbon atoms and functional groups, the surface being rendered inert.
In order to ensure that the fiber and the binder are well bonded, the pre-oxidized fiber adopted by the invention has more functional groups to participate in the reaction compared with the carbon fiber, and the surface functional groups can form a firm bonding effect with the binder, so that the strength of the prepared carbon fiber heat-insulating hard felt can be increased. In addition, the dispersion effect in the solvent is greatly improved due to the abundant functional groups on the surface of the pre-oxidized fiber, the dispersibility of the fiber is improved, and the uniformity of the prepared carbon fiber heat-insulating hard felt is also greatly improved.
The uniformity of a filter cake obtained by wet forming of the chopped pre-oxidized fiber is obviously improved. The main problem compared to carbon fiber products is that the filter cake undergoes a larger shrinkage during the subsequent carbonization process due to the removal of non-carbon elements and small molecular components, it being noted that in the present invention the binder has consolidated the fibers into a stable mat, and in the subsequent carbonization shrinkage the shrinkage of the fibers is limited by the shrinkage of the binder and other fibers, so that the shrinkage of the overall product is not consistent with the pre-oxidized fibers and the conventional pre-oxidized mat (without binder) variation, and is relatively slow. Thus, this relatively slow process results in less shrinkage, which is advantageous for uniform preparation of carbon fiber insulation stiff mats.
Compared with the inherent thought of preparing the carbon fiber heat-insulating hard felt by taking a carbon fiber finished product as a raw material in the prior art, the invention selects the pre-oxidized fiber as the initial raw material fiber, adopts the carbon fiber preparation process in the process of preparing the carbon fiber heat-insulating hard felt, and realizes carbonization of the fiber and felt formation of the fiber.
Specifically, the pressure of the press curing is 0.1MPa or more and 1MPa or less. Too much pressure can result in excessive bulk density of the product or risk of breakage of the fibers due to too much pressure, too little pressure can result in insufficient intimate contact between the fibers and thus poor mechanical properties of the product.
Specifically, the outer diameter of the asphalt fiber is 7-60 mu m; larger fiber diameters do not readily allow for complete pre-oxidation; the smaller fiber diameter easily causes transition oxidation of the fibers so as to lose additional carbon elements in the subsequent carbonization process to form defects, thereby affecting the mechanical properties of the carbon fiber felt;
specifically, the length of the asphalt fiber after being cut is 0.5-10 mm; too short fibers can reduce the mechanical properties of the carbon fiber mat and too long fibers can be detrimental to the dispersion of the fibers.
Specifically, the pitch fiber is an isotropic pitch fiber. The microcrystalline structure in the isotropic asphalt fiber has small size and disordered arrangement, which is more beneficial to heat preservation (the heat conductivity coefficient of the material is small)
Specifically, the mass ratio of the binder to the pre-oxidized fiber in the dispersion liquid is 0.25-1: 1, a step of; the poor bonding effect is easily caused by the too small mass ratio of the bonding agent, so that the mechanical property of the product is influenced; the excessive mass ratio of the binder is easy to cause uneven dispersion of the binder, so that the cracked carbon of the binder is agglomerated, and the heat preservation performance and uniformity of the product are reduced.
Specifically, the mass ratio of the dispersant to the pre-oxidized fiber is 0-0.05: 1, a step of; a small amount of dispersant can help to disperse the fibers and binder, and excessive dispersant addition can result in a significant increase in system viscosity that is detrimental to subsequent filtration processes.
Specifically, the mass ratio of the liquid medium to the pre-oxidized fiber is 20-100: 1. when the liquid medium is too small in proportion, the dispersion of the fiber and the binder is not facilitated, and when the liquid medium is too large in proportion, the production efficiency is reduced, and the production cost is indirectly improved.
Specifically, the dispersing agent comprises at least one of methyl cellulose, sodium carboxymethyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, polyacrylamide or polyvinyl alcohol. The addition of the dispersing agent can improve the surface tension between the binder and the fiber and the liquid medium, is favorable for forming a uniform dispersion system among the binder and the fiber, ensures that the binder and the fiber are not easy to settle and agglomerate, and provides a sufficient time window for the filtration process after dispersion. Preferably, the above-mentioned dispersing agent can promote the dispersion of the carbon fibers.
Specifically, the binder is selected from one of phenolic resin, asphalt, furan resin, urea resin, epoxy resin, vinyl ester resin, polyethylene, polypropylene, ethylene propylene copolymer, polyamide, polystyrene or acrylic resin; the binder is easy to crush through airflow crushing equipment, and the carbonaceous bonding points formed after carbonization of the binder have strong bonding strength, so that fibers are tightly bonded, and the mechanical property of the carbon fiber felt is improved.
Specifically, the binder satisfies Dv50∈ (1, 10); and satisfaction of the binder Dv97 e (7, 36); and the binder satisfies Dv97/Dv50 of less than 7.Dv50 is a parameter used to characterize the particle size distribution of particles, i.e. 50% of the corresponding particle size in the volume distribution, whereas Dv50 of the particle size of the binder used in the present invention is 1-10 μm. Correspondingly, dv97 is between 7 and 36 μm. The particle size of the binder can obtain a relatively good effect in the above range. Too large particle size results in too small amount of binder particles, which is detrimental to the formation of a homogeneous system and thus to the adhesion, and too small particle size results in a uniform dispersion of the binder.
Specifically, the temperature of the pressurizing and curing is 150-280 ℃; when the temperature is too low, the binder does not melt or can not solidify, and when the temperature is too high, the binder is easy to solidify too quickly to sufficiently crosslink or start to degrade.
Specifically, the time of the pressure curing is 0.5-2 h. Too short a curing time can result in insufficient curing of the binder or insufficient melt flow to the interfaces between the fibers where the fibers overlap infiltrate, and too long a curing time can result in unnecessary energy and time consumption and poor performance due to potential transitional crosslinking.
Specifically, the temperature of the heat treatment is 1000-2800 ℃; the heat treatment aims to remove non-carbon elements in the binder, the fibers and the dispersing agent, more non-carbon elements remain when the temperature is too low, and the heat conductivity of the carbon fiber felt is increased when the temperature is too high, so that the carbon fiber felt is not beneficial to being used as a heat insulation felt.
Specifically, the heating rate of the heat treatment is 0.1-50 ℃/min. The low heating rate leads to the reduction of production efficiency and the rise of energy consumption cost; the heating rate is too fast, so that the failure of heating equipment is easy to cause, and the production cost is indirectly increased.
Specifically, the density of the carbon fiber heat-insulating hard felt is 0.1-0.3 g/cm 3 ；
Specifically, the thermal conductivity of the carbon fiber heat-insulating hard felt is less than or equal to 0.3W/(m.K).
The invention is further illustrated below with reference to specific examples.
Example 1
1. 50g of isotropic pitch-based pre-oxidized fiber having a diameter of 19 μm and a length of 0.5mm were put into a 3L beaker containing 1000g of deionized water; then 12.5g of isotropic pitch powder having a particle size Dv50 of 4.9 μm and Dv97 of 12.9 μm was charged; 2.5g PVP dispersant was then added; dispersing for 60min under the stirring action of 400rpm to obtain uniform slurry;
2. pouring the slurry into a die i for suction filtration, and drying the obtained filter cake in a drying oven at 80 ℃ for 12 hours;
3. then putting the die i containing the fiber filter cake into a hot press, applying 0.1Mpa pressure from the top of the die, heating the die, namely, carrying out first heat treatment, heating to 280 ℃ at a heating rate of 5 ℃/min, preserving heat for 0.5h, bonding at the lap joint of the fibers after the asphalt powder binder is melted and flowed, naturally cooling along with the die, solidifying the melted asphalt, and demoulding to obtain the asphalt fiber felt;
4. and (3) performing high-temperature heat treatment, namely secondary heat treatment, on the asphalt fiber felt, and heating to 2200 ℃ at a heating rate of 0.5 ℃/min to obtain the carbon fiber felt.
Example 2
1. 50g of isotropic pitch-based pre-oxidized fiber having a diameter of 32 μm and a length of 5mm were put into a 10L beaker containing 5000g of deionized water; then 12.5g of isotropic pitch powder having a particle size Dv50 of 3.2 μm and Dv97 of 12.1 μm was charged; then 1g of PEG dispersing agent is added; dispersing for 60min under the stirring action of 600rpm to obtain uniform slurry;
2. pouring the slurry into a die i for suction filtration, and drying the obtained filter cake in a drying oven at 80 ℃ for 12 hours;
3. then putting the mould i containing the fiber filter cake into a hot press, applying 0.5Mpa pressure from the top of the mould, heating the mould, namely, carrying out first heat treatment, heating to 280 ℃ at a heating rate of 5 ℃/min, preserving heat for 0.5h, bonding the isotropic asphalt powder adhesive at the lap joint of the fibers after melting and flowing, naturally cooling the mould along with molten asphalt, solidifying the molten asphalt, and demoulding to obtain asphalt fiber mats;
4. and (3) carrying out high-temperature heat treatment, namely secondary heat treatment, on the asphalt fiber felt, and heating to 1100 ℃ at a heating rate of 0.1 ℃/min to obtain the carbon fiber felt.
Example 3
1. 50g of isotropic pitch-based pre-oxidized fiber having a diameter of 11 μm and a length of 10mm were put into a 5L beaker containing 2500g of deionized water; then 25g of a phenol resin powder having a particle diameter Dv50 of 2.8 μm and a Dv97 of 11.2 μm was charged; adding 0.5g of PAM dispersing agent; dispersing for 120min under the stirring action of 500rpm to obtain uniform slurry;
2. pouring the slurry into a die i for suction filtration, and drying the obtained filter cake in a drying oven at 90 ℃ for 10 hours;
3. then putting the die i containing the fiber filter cake into a hot press, applying 0.5Mpa pressure from the top of the die, heating the die, namely, carrying out first heat treatment, heating to 150 ℃ at a heating rate of 5 ℃/min, and preserving heat for 2 hours, so that the phenolic resin powder binder is bonded and solidified at the lap joint of the fibers after melt flowing, and demoulding after natural cooling along with the die to obtain the asphalt fiber felt;
4. and (3) performing high-temperature heat treatment, namely secondary heat treatment, on the asphalt fiber felt, and heating to 2800 ℃ at a heating rate of 20 ℃/min to obtain the carbon fiber felt.
Example 4
1. 50g of isotropic pitch-based pre-oxidized fiber having a diameter of 28 μm and a length of 3mm were put into a 5L beaker containing 2500g of deionized water; then 25g of a phenol resin powder having a particle diameter Dv50 of 6.9 μm and a Dv97 of 21.4 μm was charged; adding 0.5g of CTAB dispersant; dispersing for 180min under the stirring action of 400rpm to obtain uniform slurry;
2. pouring the slurry into a die i for suction filtration, and drying the obtained filter cake in a drying oven at 90 ℃ for 10 hours;
3. then putting the die i containing the fiber filter cake into a hot press, applying 0.2Mpa pressure from the top of the die, heating the die, namely, carrying out first heat treatment, heating to 150 ℃ at a heating rate of 5 ℃/min, and preserving heat for 2 hours, so that the phenolic resin powder binder is bonded and solidified at the lap joint of the fibers after melt flowing, and demoulding after natural cooling along with the die to obtain the asphalt fiber felt;
4. and (3) performing high-temperature heat treatment, namely secondary heat treatment, on the asphalt fiber felt, and heating to 2800 ℃ at a heating rate of 30 ℃/min to obtain the carbon fiber felt.
Example 5
1. 50g of isotropic pitch-based pre-oxidized fiber having a diameter of 60 μm and a length of 1mm were put into a 10L beaker containing 5000g of deionized water; then 50g of a phenol resin powder having a particle diameter Dv50 of 9.8 μm and a Dv97 of 35.2 μm was charged; adding 0.5g of PAM dispersing agent; dispersing for 180min under the stirring action of 400rpm to obtain uniform slurry;
2. pouring the slurry into a die i for suction filtration, and drying the obtained filter cake in a drying oven at 90 ℃ for 10 hours;
3. then putting the mould i containing the fiber filter cake into a hot press, applying 0.2Mpa pressure from the top of the mould, heating the mould, namely, carrying out first heat treatment, heating to 280 ℃ at a heating rate of 5 ℃/min, preserving heat for 0.5h, bonding the isotropic asphalt powder adhesive at the lap joint of the fibers after melting and flowing, naturally cooling the mould along with molten asphalt, solidifying the molten asphalt, and demoulding to obtain asphalt fiber mats;
4. and (3) performing high-temperature heat treatment, namely secondary heat treatment, on the asphalt fiber felt, and heating to 2600 ℃ at a heating rate of 50 ℃/min to obtain the carbon fiber felt.
Example 6
1. 50g of isotropic pitch-based pre-oxidized fiber having a diameter of 7 μm and a length of 10mm were put into a 3L beaker containing 1500g of deionized water; then, 20g of a phenol resin powder having a particle diameter Dv50 of 1.3 μm and a Dv97 of 9.1 μm was charged; 2.5g PVP dispersant was then added; dispersing for 60min under the stirring action of 600rpm to obtain uniform slurry;
2. pouring the slurry into a die i for suction filtration, and drying the obtained filter cake in a drying oven at 100 ℃ for 6 hours;
3. then putting the die i containing the fiber filter cake into a hot press, applying 1Mpa pressure from the top of the die, heating the die, namely performing first heat treatment, heating to 150 ℃ at a heating rate of 5 ℃/min, and preserving heat for 2 hours, so that the phenolic resin powder binder is bonded and solidified at the lap joint of the fibers after being melted and flowing, and demoulding after naturally cooling the die to obtain the asphalt fiber felt;
4. and (3) performing high-temperature heat treatment, namely secondary heat treatment, on the asphalt fiber felt, and heating to 2800 ℃ at a heating rate of 50 ℃/min to obtain the carbon fiber felt.
Example 7
The difference between this example and example 1 is that no PVP dispersant was added in step 1, the rest of the procedure being the same as in example 1;
comparative example 1
The difference between this comparative example and example 1 is that the fibers used in step 1 are isotropic pitch-based fibers that are not fully pre-oxidized, the remainder of the procedure being the same as in example 1;
comparative example 2
The difference between this comparative example and example 1 is that the fibers used in step 1 are mesophase pitch-based pre-oxidized fibers, the remaining steps being the same as in example 1;
comparative example 3
The difference between this comparative example and example 1 is that the fibers used in step 1 are isotropic pitch-based carbon fibers, the remainder of the procedure being the same as in example 1;
comparative example 4
The difference between this comparative example and comparative example 3 is that no PVP dispersant was added in step 1, and the rest was the same as comparative example 3;
the carbon fiber felts provided in examples 1 to 7 and comparative examples 1 to 4 were tested, and the tests included:
1. the sampling mode is shown in fig. 2, the number of the samples is not less than 7, so that the average value and standard deviation of the test results are calculated and obtained, and the uniformity of the samples is judged by the standard deviation obtained by sampling tests of different parts of the prepared samples;
2. calculating the density of the carbon fiber felt according to the ratio of the mass to the volume of the carbon fiber felt, wherein the mass is measured by an analytical balance, and the volume is calculated after the size is measured by a micrometer;
3. the heat conductivity coefficient of the carbon fiber felt in the Z direction is tested by adopting a Hot Disk TPS2500s heat flow meter, and the diameter is 25mm and the thickness is 2mm;
4. the compressive strength of the carbon fiber felt in the Z direction is tested by adopting a CTM2500 universal material testing machine, and the size of a test sample is 10 x 10mm 3 The test rate is 1mm/min;
the test results are shown in Table 1
As can be seen from the data results shown in examples 1-7, the reasonable lower heat treatment temperature, shorter fiber length and lower molding pressure are used, so that the rigidity of the carbon fiber felt can be met, the heat insulation performance of the carbon fiber felt can be highlighted, and the standard deviation of the data shows that the prepared sample has higher sample uniformity; furthermore, as can be seen from the data, an increase in molding pressure can significantly increase the bulk density of the carbon fiber mat.
As can be seen from the data shown in examples 1 and 7, the addition of the dispersant is beneficial to the uniformity of the carbon fiber felt produced;
from the data of example 1 and comparative example 1, it is found that when the non-completely pre-oxidized isotropic pitch-based pre-oxidized fiber is selected as the raw material, the preparation of the carbon fiber mat with low density is not favored;
as can be seen from the data of example 1 and comparative example 2, when mesophase pitch-based pre-oxidized fibers are selected as the raw materials, the carbon fiber felt thereof exhibits a higher thermal conductivity, thus being unfavorable for preparing a carbon fiber felt having excellent heat insulation properties;
as can be seen from the data of example 1 and comparative example 3, compared with pitch-based carbon fibers, the isotropic pitch-based pre-oxidized fibers were selected as the raw materials, which is significantly advantageous for uniformity of the prepared carbon fiber mat;
as can be seen from the data of example 7 and comparative example 3, when isotropic pitch-based pre-oxidized fibers were selected as the raw materials, the uniformity of the prepared carbon fiber mat was superior to that of the carbon fiber mat prepared when pitch carbon fibers were used as the raw materials and the dispersing agent was used, even though the dispersing agent was not added to aid in dispersion;
as can be seen from the data of example 7 and comparative example 4, when the dispersant was not used, the uniformity of the carbon fiber mat prepared from the isotropic pitch-based pre-oxidized fiber was significantly better than that prepared from pitch carbon fiber.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (5)
1. The preparation method of the carbon fiber heat-insulating hard felt is characterized by comprising the following steps:
fully pre-oxidizing the asphalt fiber to obtain asphalt pre-oxidized fiber;
chopping the pre-oxidized fiber, mixing with a binder and a dispersing agent, and dispersing in a liquid medium to obtain a dispersion liquid;
filtering out the liquid in the dispersion liquid, drying, pressurizing and curing, and then performing heat treatment to obtain the composite material;
the pressure of the pressurizing and curing is more than or equal to 0.1MPa and less than or equal to 1MPa;
the density of the carbon fiber heat-insulating hard felt is 0.1-0.3 g/cm 3 ；
The thermal conductivity of the carbon fiber heat-insulating hard felt is less than or equal to 0.3W/(m.K);
the temperature of the heat treatment is 1000-2800 ℃;
the pitch fiber is an uncarbified isotropic pitch fiber;
the mass ratio of the binder to the pre-oxidized fiber in the dispersion liquid is 0.25-1: 1, a step of;
the binder is selected from phenolic resin or asphalt;
the adhesive meets Dv50∈ (1, 10); and is also provided with
The binder satisfies Dv97 e (7, 36) of the binder; and is also provided with
The binder meets the requirement that Dv97/Dv50 is less than 7;
the outer diameter of the asphalt fiber is 7-60 mu m;
the length of the asphalt fiber after being cut is 0.5-10 mm.
2. The method for preparing the carbon fiber heat-insulating hard felt according to claim 1, which is characterized in that:
the mass ratio of the dispersant to the pre-oxidized fiber is 0-0.05: 1, a step of;
the mass ratio of the liquid medium to the pre-oxidized fiber is 20-100: 1.
3. the method for preparing the carbon fiber heat-insulating hard felt according to claim 1, which is characterized in that:
the dispersant comprises methylcellulose, sodium carboxymethylcellulose, ethylcellulose, hydroxypropyl methylcellulose, and hydroxy
At least one of ethylcellulose, polyacrylamide or polyvinyl alcohol.
4. The method for preparing the carbon fiber heat-insulating hard felt according to claim 1, which is characterized in that:
the temperature of the pressurizing and curing is 150-280 ℃;
the time of the pressurizing and curing is 0.5-2 h.
5. The method for preparing the carbon fiber heat-insulating hard felt according to claim 1, which is characterized in that:
the temperature of the heat treatment is 1000-2800 ℃;
the heating rate of the heat treatment is 0.1-50 ℃/min.
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| CN104276805A (en) * | 2013-07-03 | 2015-01-14 | 辽源市亿达碳业有限公司 | Preparation method of hard carbon felt |
| CN106044742A (en) * | 2016-05-30 | 2016-10-26 | 湖南大学 | Method for preparing pitch-based carbon fiber self-bonding network material |
| CN113584940A (en) * | 2021-06-24 | 2021-11-02 | 浙江超探碳纤维科技有限公司 | Preparation method of carbon fiber paper |
| CN114164557A (en) * | 2021-12-30 | 2022-03-11 | 湖南东映特碳沥青材料有限公司 | Carbon fiber hard felt and preparation method thereof |
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| DE102009048422A1 (en) * | 2009-10-06 | 2011-04-07 | Sgl Carbon Se | Composite of carbon fiber soft felt and carbon fiber hard felt |
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| CN101628816A (en) * | 2008-07-17 | 2010-01-20 | 鞍山塞诺达碳纤维有限公司 | Method for manufacturing high-density rigid carbon-fiber heat-insulation material |
| CN104276805A (en) * | 2013-07-03 | 2015-01-14 | 辽源市亿达碳业有限公司 | Preparation method of hard carbon felt |
| CN104230368A (en) * | 2014-09-26 | 2014-12-24 | 辽宁奥亿达新材料有限公司 | Pitch-based carbon fiber nonwoven felt insulation board and manufacturing method thereof |
| CN106044742A (en) * | 2016-05-30 | 2016-10-26 | 湖南大学 | Method for preparing pitch-based carbon fiber self-bonding network material |
| CN113584940A (en) * | 2021-06-24 | 2021-11-02 | 浙江超探碳纤维科技有限公司 | Preparation method of carbon fiber paper |
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