Carbon aerogel composite material as well as preparation method and application thereof

Abstract

The invention relates to the field of composite materials, and discloses a carbon aerogel composite material as well as a preparation method and application thereof. The carbon aerogel composite material comprises a carbon foam skeleton and a carbon aerogel matrix attached to and not attached to the carbon foam skeleton, a precursor of the carbon aerogel matrix is phenolic resin; a precursor of the carbon foam framework comprises one or more of polyurethane foam, polyimide foam, melamine foam and phenolic foam. A carbon foam skeleton in the carbon aerogel composite material can play a powerful supporting role, and shrinkage and collapse of a carbon aerogel matrix are limited; the carbon foam skeleton and the granular carbon aerogel matrix can be synergistically pyrolyzed and shrunk, and meanwhile, residual thermal stress can be effectively and uniformly released along the carbon foam skeleton, so that brittle fracture of the carbon aerogel matrix can be effectively prevented; the room-temperature heat conductivity of the carbon aerogel composite material is as low as 0.037 W / m.K, and the carbon aerogel composite material has good heat insulation performance.

Description

Technical Field

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

[0002] Aerogel is a nanoporous solid material connected by colloidal particles, which has the advantages of low density, high specific surface area, high porosity, and low thermal conductivity. Because aerogel has a three-dimensional network structure of nanopores, it has broad application prospects in the fields of organic adsorption, catalyst carriers, electrochemical supercapacitors, and energy storage devices. Among the various types of aerogels currently studied, carbon aerogel has the highest thermal stability and can maintain its nanoporous structure intact at high temperatures above 2000°C in an inert atmosphere. At the same time, the specific extinction coefficient of carbon aerogel is much higher than that of other materials, which can effectively reduce its radiative heat conduction. Therefore, in thermal protection systems, carbon aerogel is a promising high-temperature insulation material. The preparation of carbon aerogel is usually made by drying and carbonizing organic aerogels such as resorcinol-formaldehyde, hydroquinone-formaldehyde, and melamine-formaldehyde.

[0003] However, the current challenge in preparing carbon aerogels is how to remove the solvent from the wet gel without destroying its complete three-dimensional network structure. During the solvent removal process, due to the strong surface tension between the solvent and the aerogel skeleton, the volume of the dried aerogel shrinks very severely and is prone to collapse. In addition, the inherent brittle and fragile properties of carbon aerogels will affect the structural integrity of the prepared carbon aerogels, because the residual thermal stress during the carbonization process will cause brittle cracking. Therefore, it is particularly important to develop a large-scale carbon aerogel with a complete structure.

[0004] In order to solve this problem, CN116675551A prepared a high-strength carbon aerogel composite material by using carbon fiber pre-oxidized yarn as a reinforcing material and biomass sugar carbon aerogel as a matrix material. However, due to the introduction of carbon fiber, the density of the carbon aerogel material is relatively high, which also leads to an increase in the thermal conductivity of the material, affecting its performance.

[0005] In view of the problems of easy drying shrinkage and carbonization cracking of carbon aerogels in the prior art, it is urgent to study a method for preparing carbon aerogel composite materials with excellent comprehensive performance. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of easy drying shrinkage and carbonization cracking of carbon aerogel in the prior art, and to provide a carbon aerogel composite material and its preparation method and application. The carbon foam skeleton in the carbon aerogel composite material can play a strong supporting role, limiting the shrinkage and collapse of the carbon aerogel matrix; the carbon foam skeleton and the granular carbon aerogel matrix can synergistically pyrolyze and shrink, and the residual thermal stress can be effectively released evenly along the carbon foam skeleton, which can effectively prevent the carbon aerogel matrix from brittle fracture; in addition, the carbon aerogel composite material has a room temperature thermal conductivity as low as 0.037W / m·K under the premise of meeting good mechanical properties, and has good thermal insulation performance.

[0007] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a carbon aerogel composite material, wherein the carbon aerogel composite material includes a carbon foam skeleton, and a carbon aerogel matrix attached to and not attached to the carbon foam skeleton; the precursor of the carbon aerogel matrix is ​​a phenolic resin; the precursor of the carbon foam skeleton includes one or more of polyurethane foam, polyimide foam, melamine foam and phenolic foam.

[0008] A second aspect of the present invention provides a method for preparing the aforementioned carbon aerogel composite material, wherein the preparation method comprises:

[0009] (1) contacting an organic resin, a curing agent, and a solvent to prepare an organic resin solution;

[0010] (2) placing the organic porous foam in a mold, and then impregnating the organic resin solution into the organic porous foam at low pressure;

[0011] (3) sealing the mold to carry out sol-gel reaction and then cooling to room temperature;

[0012] (4) opening the mold and drying the aerogel obtained in step (3) to obtain an organic aerogel composite material with foam skeleton reinforcement;

[0013] (5) Placing the organic aerogel composite material in an inert atmosphere for heat treatment to obtain a carbon aerogel composite material.

[0014] A third aspect of the present invention provides an application of the aforementioned carbon aerogel composite material in the field of thermal insulation.

[0015] Through the above technical solution, the technical solution of the present invention has the following beneficial effects:

[0016] (1) The carbon aerogel composite material of the present invention has a porous structure, and is composited with a carbon aerogel matrix and a lightweight carbon foam skeleton. Its macroscopic and microscopic morphologies are controllable, its density is low, and its preparation method is simple, the cost is low, and its processability is strong;

[0017] (2) In the carbon aerogel composite material of the present invention, the carbon foam skeleton strongly supports the structure of the carbon aerogel matrix, thereby limiting the shrinkage and collapse of the carbon aerogel matrix;

[0018] (3) In the carbon aerogel composite material of the present invention, during the high-temperature pyrolysis process, the carbon foam skeleton and the carbon aerogel matrix particles can synergistically pyrolyze and shrink, and at the same time, the residual thermal stress can be effectively released evenly along the carbon foam skeleton, which can effectively prevent the carbon aerogel matrix from brittle fracture.

[0019] (4) The carbon aerogel composite material of the present invention has a porous network structure, the pore diameter of which is smaller than the free path of gas molecules, thereby limiting the convective heat transfer of gas molecules and effectively preventing the surface heat from being transferred to the inside. The room temperature thermal conductivity is as low as 0.037 W / m·K, thereby improving the thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the microscopic morphology of the carbon foam skeleton in Example 2 of the present invention;

[0021] Figure 2 This is the microscopic morphology of the carbon aerogel composite material prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0022] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0023] As mentioned above, the first aspect of the present invention provides a carbon aerogel composite material, wherein the carbon aerogel composite material comprises a carbon foam skeleton, and a carbon aerogel matrix attached to and not attached to the carbon foam skeleton;

[0024] The precursor of the carbon aerogel matrix is ​​phenolic resin; the precursor of the carbon foam skeleton includes one or more of polyurethane foam, polyimide foam, melamine foam and phenolic foam.

[0025] The inventors of the present invention have found through research that the present invention adjusts the pore size of the carbon aerogel composite material by adjusting the proportion of the organic resin and the pyrolysis temperature, so that the carbon aerogel composite material has a porous network structure. On the one hand, the pore diameter is smaller than the free path of the gas molecules, thereby limiting the convective heat transfer of the gas molecules, effectively preventing the surface heat from being transferred to the inside, and the room temperature thermal conductivity is as low as 0.037W / m·K, thereby improving the thermal insulation performance; on the other hand, in the carbon aerogel composite material of the present invention, the carbon foam skeleton strongly supports the structure of the carbon aerogel matrix, limits the shrinkage and collapse of the carbon aerogel matrix, and effectively reduces the density of the carbon aerogel composite material.

[0026] Furthermore, during the high-temperature pyrolysis process, the carbon foam skeleton and the carbon aerogel matrix particles can synergistically pyrolyze and shrink, and the residual thermal stress can be effectively released evenly along the carbon foam skeleton, thereby effectively preventing the carbon aerogel matrix from brittle fracture.

[0027] According to the present invention, preferably, the carbon foam skeleton is melamine foam.

[0028] According to the present invention, based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​92-99wt%, and the content of the carbon foam skeleton is 1-8wt%; preferably, based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​95-98wt%, and the content of the carbon foam skeleton is 2-5wt%. In the present invention, if the content of the carbon aerogel matrix is ​​too high, it will lead to the disadvantages of high thermal conductivity and excessive density of the composite material; if the content of the carbon aerogel matrix is ​​too low, it will lead to the disadvantage of deviation of the mechanical properties of the composite material.

[0029] According to the present invention, the preparation method of the phenolic resin comprises:

[0030] 1) contacting phenol, aldehyde and catalyst to carry out a first reaction to obtain a light yellow viscous liquid;

[0031] 2) adjusting pH and temperature to continue the second reaction;

[0032] 3) After the second reaction is completed, vacuum treatment is performed to obtain a phenolic resin.

[0033] According to the present invention, the phenol is selected from one or more of phenol, m-cresol and resorcinol, preferably phenol.

[0034] According to the present invention, the aldehyde is formaldehyde and / or furfural, preferably formaldehyde.

[0035] According to the present invention, the catalyst is oxalic acid and / or hydrochloric acid, preferably hydrochloric acid.

[0036] According to the present invention, the molar ratio of the phenol to the aldehyde is (0.5-2):1, preferably (1-2):1, and more preferably (1-1.5):1.

[0037] According to the present invention, the catalyst is used in an amount of 4-6% by mole, preferably 5-6% by mole, of the phenol.

[0038] According to the present invention, the conditions of the first reaction include: temperature of 65-75° C. and time of 0.5-2 h.

[0039] According to the present invention, the conditions of the second reaction include: temperature of 80-95° C., time of 2-4 h, and pH of 6.5-7.5.

[0040] According to the present invention, the average molecular weight of the phenolic resin is 500-1500Da, preferably 1000Da.

[0041] According to the present invention, the carbon aerogel composite material has a nanopore diameter of 50-200 nm and a density of 0.1-0.35 g / cm 3 , thermal conductivity ≥ 0.037 W / m·K at room temperature, compression strength ≤ 4.14 MPa; preferably, the carbon aerogel composite material has a nanopore diameter of 80-120 nm and a density of 0.11-0.21 g / cm 3 , the thermal conductivity at room temperature is 0.037-0.061 W / m·K, and the compressive strength is 0.34-4.14 MPa. In the present invention, it should be noted that the carbon aerogel composite material meets the above parameter limitations, and the carbon aerogel composite material can have better thermal insulation performance and better comprehensive performance under the condition of meeting the mechanical properties.

[0042] A second aspect of the present invention provides a method for preparing the aforementioned carbon aerogel composite material, wherein the preparation method comprises:

[0043] (1) contacting an organic resin, a curing agent, and a solvent to prepare an organic resin solution;

[0044] (2) placing the organic porous foam in a mold, and then impregnating the organic resin solution into the organic porous foam at low pressure;

[0045] (3) sealing the mold to carry out sol-gel reaction and then cooling to room temperature;

[0046] (4) opening the mold and drying the aerogel obtained in step (3) to obtain an organic aerogel composite material with foam skeleton reinforcement;

[0047] (5) Placing the organic aerogel composite material in an inert atmosphere for heat treatment to obtain a carbon aerogel composite material.

[0048] According to the present invention, the structure of the organic porous foam includes an open-cell foam structure or a closed-cell foam structure, and there is no specific limitation in the present invention; in addition, in the present invention, the density of the organic porous foam is 0.01-0.1 g / cm 3 .

[0049] According to the present invention, the curing agent is hexamethylenetetramine.

[0050] According to the present invention, the solvent is selected from one or more of n-butanol, isopropanol, ethanol and ethylene glycol.

[0051] According to the present invention, the concentration of the organic resin in the organic resin solution is 10-30 wt %. In the present invention, it should be noted that the organic resin solution refers to an organic resin solution prepared by dissolving the organic resin in the above-mentioned solvent.

[0052] According to the present invention, the amount of the curing agent is 10-25% of the mass of the organic resin.

[0053] According to the present invention, in step (2), the pressure of the low-pressure impregnation is ≤0.5 MPa, preferably 0.2-0.5 MPa.

[0054] According to the present invention, the mold is not particularly limited, and may preferably be a stainless steel mold.

[0055] According to the present invention, in step (3), the conditions of the sol-gel reaction include: temperature of 80-140° C. and time of 24-48 h.

[0056] According to the present invention, in step (4), the drying conditions include: at normal pressure, the temperature is 20-120°C, and the time is 24-48h. In the present invention, during the normal pressure drying process, the ultra-light organic porous carbon foam skeleton can provide support to offset the surface tension caused by solvent evaporation, thereby effectively inhibiting volume shrinkage and shape change. The organic porous carbon foam skeleton and the organic carbon aerogel matrix can synergistically crack and shrink, and the residual thermal stress can be effectively released uniformly along the skeleton, thereby effectively preventing the carbon aerogel matrix from brittle fracture.

[0057] According to the present invention, in step (5), the heat treatment conditions include: a temperature of 600-1200° C., preferably a temperature of 800-1000° C., and a time of 2-4 hours.

[0058] In the present invention, the carbon aerogel composite material prepared by the method of the present invention has the characteristics of light weight, high strength, low thermal conductivity, large size and complete structure; with carbon aerogel nanoparticles as the matrix, the construction of the nano-network structure is realized through sol-gel phase separation and high-temperature pyrolysis, and it has a typical carbon foam-reinforced three-dimensional nanoparticle network structure.

[0059] A third aspect of the present invention provides an application of the aforementioned carbon aerogel composite material in the field of thermal insulation.

[0060] The present invention will be described in detail below through examples.

[0061] In the following examples and comparative examples:

[0062] Thermal conductivity parameters were measured using the GB / T 10295-88 method;

[0063] The compressive strength parameters were measured using the GB / T 34559-2017 method;

[0064] The melamine foam is a commercial product sold by BASF under the brand name Basotect.

[0065] Example 1

[0066] This embodiment is intended to illustrate the carbon aerogel composite material prepared by the method of the present invention.

[0067] Preparation of phenolic resin:

[0068] 1) Add phenol, formaldehyde and hydrochloric acid into a reactor and react at 70° C. for 1 hour, wherein the molar ratio of phenol to formaldehyde is 1:1 and the molar amount of hydrochloric acid is 5% of that of phenol to obtain a light yellow viscous liquid;

[0069] 2) Adjust the temperature to 90°C and continue the reaction for 3 hours, and adjust the pH to 7;

[0070] 2) vacuumizing after the reaction is completed to obtain a phenolic resin;

[0071] Results The average molecular weight of the prepared phenolic resin was 1000 Da.

[0072] Preparation of carbon aerogel composites:

[0073] (1) Phenolic resin and isopropanol are weighed separately, added into a stirring tank, mechanically stirred until completely dissolved, and finally hexamethylenetetramine is added, and stirring is continued for 1 hour to obtain a phenolic resin impregnation solution, wherein the mass ratio of phenolic resin, isopropanol, and hexamethylenetetramine is 10:90:2; that is, the concentration of phenolic resin (organic resin) in the isopropanol solution of phenolic resin (organic resin solution) is 10wt%, and the amount of hexamethylenetetramine (curing agent) added is 20% of the phenolic resin (organic resin);

[0074] (2) The density is 10kg / m 3 The melamine foam is spread flat in a stainless steel mold of 20 cm×20 cm×2 cm, so that the melamine foam just fills the cavity in the mold, and the phenolic resin solution prepared above is slowly injected into the melamine foam at room temperature 25° C. and pressure 0.2 MPa until the impregnation liquid can completely penetrate the melamine foam;

[0075] (3) The mold is then sealed and placed in an oven at 80°C for 24 hours of sol-gel reaction and aging. The molded sample is then dried at room temperature and pressure for 24 hours.

[0076] (4) Then place it in an oven at 50°C for 12 h, and then in an oven at 80°C for 12 h, at which point the sample is almost completely dry;

[0077] (5) It was then placed in a box furnace for heat treatment at 800°C for 2 h to prepare a carbon aerogel composite material.

[0078] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​95wt%, and the content of the carbon foam skeleton is 5wt%.

[0079] In addition, the average diameter of the nanopores of the carbon aerogel composite material is 120nm and the density is 0.11g / cm 3 , the room temperature thermal conductivity is 0.037W / m·K, the compressive strength is 0.34MPa; and the carbon aerogel composite material is not easy to shrink during drying and does not crack during carbonization.

[0080] Example 2

[0081] This embodiment is intended to illustrate the carbon aerogel composite material prepared by the method of the present invention.

[0082] A phenolic resin was prepared in the same manner as in Example 1.

[0083] Preparation of carbon aerogel composites:

[0084] (1) Phenolic resin and isopropanol are weighed separately, added into a stirring tank, and mechanically stirred until completely dissolved, and finally hexamethylenetetramine is added, and stirring is continued for 1 hour to obtain a phenolic resin impregnation solution, wherein the mass ratio of phenolic resin, isopropanol, and hexamethylenetetramine is 15:85:3; that is, the concentration of phenolic resin (organic resin) in the isopropanol solution of phenolic resin (organic resin solution) is 15wt%, and the amount of hexamethylenetetramine (curing agent) added is 20% of the phenolic resin (organic resin).

[0085] (2) The density is 10kg / m 3 The melamine foam is spread flat in a stainless steel mold of 20 cm×20 cm×2 cm, so that the melamine foam just fills the cavity in the mold, and the melamine foam is slowly impregnated with the above-prepared phenolic resin solution at room temperature 25° C. and pressure 0.2 MPa until the impregnation liquid can completely infiltrate the melamine foam;

[0086] (3) The mold is then sealed and placed in an oven at 80°C for 24 hours of sol-gel reaction and aging. The molded sample is then dried at room temperature and pressure for 24 hours.

[0087] (4) Then place it in an oven at 50°C for 12 h, and then in an oven at 80°C for 12 h, at which point the sample is almost completely dry;

[0088] (5) It was then placed in a box furnace for heat treatment at 800°C for 2 h to prepare a carbon aerogel composite material.

[0089] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​96.5wt%, and the content of the carbon foam skeleton is 3.5wt%.

[0090] In addition, the average diameter of the nanopores of the carbon aerogel composite material is 92nm and the density is 0.17g / cm 3 , the room temperature thermal conductivity is 0.049W / m·K, the compressive strength is 2.40MPa; and the carbon aerogel composite material is not easy to shrink during drying and does not crack during carbonization.

[0091] The microstructure of carbon foam and carbon aerogel composites is shown in Figure 2. Figure 1 and 2 shown.

[0092] Figure 1 is the microscopic morphology of the carbon foam skeleton in Example 2 of the present invention; Figure 1It can be seen that the carbon foam skeleton presents an obvious open-cell structure, and the structures are connected by a common "prism (skeleton)" to form a three-dimensional mesh open-cell structure. The unit body of the foam skeleton is a four- to six-membered ring structure, and the average pore size is about 100μm.

[0093] Figure 2 is the microscopic morphology of the carbon aerogel composite material prepared in Example 2 of the present invention; Figure 2 It can be seen that some carbon aerogel particles are attached to the carbon foam skeleton, and the other part is filled in the gaps in the carbon foam skeleton, and they are interconnected to form a carbon aerogel with a three-dimensional network structure.

[0094] Example 3

[0095] This embodiment is intended to illustrate the carbon aerogel composite material prepared by the method of the present invention.

[0096] A phenolic resin was prepared in the same manner as in Example 1.

[0097] Preparation of carbon aerogel composites:

[0098] (1) Phenolic resin and isopropanol are weighed separately, added into a stirring tank, and mechanically stirred until completely dissolved, and finally hexamethylenetetramine is added, and stirring is continued for 1 hour to obtain a phenolic resin impregnation solution, wherein the mass ratio of phenolic resin, isopropanol, and hexamethylenetetramine is 20:80:4; that is, the concentration of phenolic resin (organic resin) in the isopropanol solution of phenolic resin (organic resin solution) is 20wt%, and the amount of hexamethylenetetramine (curing agent) added is 20% of the phenolic resin (organic resin).

[0099] (2) The density is 10kg / m 3 The melamine foam is spread flat in a stainless steel mold of 20 cm×20 cm×2 cm, so that the melamine foam just fills the cavity in the mold, and the melamine foam is slowly impregnated with the above-prepared phenolic resin solution at room temperature 25° C. and pressure 0.2 MPa until the impregnation liquid can completely infiltrate the melamine foam;

[0100] (3) The mold is then sealed and placed in an oven at 80°C for 24 hours of sol-gel reaction and aging. The molded sample is then dried at room temperature and pressure for 24 hours.

[0101] (4) Then place it in an oven at 50°C for 12 h, and then in an oven at 80°C for 12 h, at which point the sample is almost completely dry;

[0102] (5) It was then placed in a box furnace for heat treatment at 800°C for 2 h to prepare a carbon aerogel composite material.

[0103] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​98wt%, and the content of the carbon foam skeleton is 2wt%.

[0104] In addition, the average diameter of the nanopores of the carbon aerogel composite material is 80nm and the density is 0.21g / cm 3 , the room temperature thermal conductivity is 0.061W / m·K, the compressive strength is 4.14MPa; and the carbon aerogel composite material is not easy to shrink during drying and does not crack during carbonization.

[0105] Example 4

[0106] This embodiment is intended to illustrate the carbon aerogel composite material prepared by the method of the present invention.

[0107] A phenolic resin was prepared in the same manner as in Example 1.

[0108] Preparation of carbon aerogel composites:

[0109] (1) Phenolic resin and isopropanol are weighed separately, added into a stirring tank, and mechanically stirred until completely dissolved, and finally hexamethylenetetramine is added, and stirring is continued for 1 hour to obtain a phenolic resin impregnation solution, wherein the mass ratio of phenolic resin, isopropanol, and hexamethylenetetramine is 15:85:3; that is, the concentration of phenolic resin (organic resin) in the isopropanol solution of phenolic resin (organic resin solution) is 15wt%, and the amount of hexamethylenetetramine (curing agent) added is 20% of the phenolic resin (organic resin).

[0110] (2) The density is 10kg / m 3 The polyimide foam is spread flat in a stainless steel mold of 20 cm×20 cm×2 cm, so that the melamine foam just fills the cavity in the mold, and the melamine foam is slowly impregnated with the above-prepared phenolic resin solution at room temperature 25°C and a pressure of 0.2 MPa until the impregnation liquid can completely infiltrate the melamine foam;

[0111] (3) The mold is then sealed and placed in an oven at 80°C for 24 hours of sol-gel reaction and aging. The molded sample is then dried at room temperature and pressure for 24 hours.

[0112] (4) Then place it in an oven at 50°C for 12 h, and then in an oven at 80°C for 12 h, at which point the sample is almost completely dry;

[0113] (5) It was then placed in a box furnace for heat treatment at 800°C for 2 h to prepare a carbon aerogel composite material.

[0114] The prepared carbon aerogel composite material includes a carbon foam skeleton (polyimide foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​97wt%, and the content of the carbon foam skeleton is 3wt%.

[0115] In addition, the carbon aerogel composite material has an average nanopore diameter of 84nm, a density of 0.15g / cm3, a room temperature thermal conductivity of 0.052W / m·K, and a compressive strength of 2.21MPa; and the carbon aerogel composite material is not easy to shrink during drying and does not crack during carbonization.

[0116] Example 5

[0117] A phenolic resin and carbon aerogel composite material was prepared in the same manner as in Example 2, except that in the preparation of the carbon aerogel composite material, in step (5), "placed in a box-type furnace at 800°C" was changed to "placed in a box-type furnace at 600°C".

[0118] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​96.7wt%, and the content of the carbon foam skeleton is 3.3wt%.

[0119] In addition, the average diameter of the nanopores of the prepared carbon aerogel composite material was 95 nm and the density was 0.16 g / cm 3 , the room temperature thermal conductivity is 0.039W / m·K, the compressive strength is 1.26MPa; and the carbon aerogel composite material is not easy to shrink during drying and does not crack during carbonization.

[0120] Example 6

[0121] A phenolic resin and carbon aerogel composite material was prepared in the same manner as in Example 2, except that in the preparation of the carbon aerogel composite material, in step (5), "placed in a box-type furnace at 800°C" was modified to "placed in a box-type furnace at 1200°C".

[0122] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​96.2wt%, and the content of the carbon foam skeleton is 3.8wt%.

[0123] In addition, the average diameter of the nanopores of the prepared carbon aerogel composite material was 85 nm and the density was 0.18 g / cm 3 , the room temperature thermal conductivity is 0.057W / m·K, the compressive strength is 3.02MPa; and the carbon aerogel composite material is not easy to shrink during drying, and has slight cracking during carbonization.

[0124] Comparative Example 1

[0125] A phenolic resin and carbon aerogel composite material was prepared in the same manner as in Example 2, except that in the preparation of the carbon aerogel composite material, in step (1), "the mass ratio of phenolic resin, isopropanol and hexamethylenetetramine is 15:85:3" was modified to "the mass ratio of phenolic resin, isopropanol and hexamethylenetetramine is 5:95:1".

[0126] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​90wt%, and the content of the carbon foam skeleton is 10wt%.

[0127] In addition, the average diameter of the nanopores of the prepared carbon aerogel composite material was 180 nm and the density was 0.07 g / cm 3 , the room temperature thermal conductivity is 0.021 W / m·K, the compressive strength is 0.11 MPa; and the carbon aerogel composite material is not easy to shrink during drying, and has slight cracking during carbonization.

[0128] Comparative Example 2

[0129] A phenolic resin and carbon aerogel composite material was prepared in the same manner as in Example 2, except that in the preparation of the carbon aerogel composite material, in step (1), "the mass ratio of phenolic resin, isopropanol and hexamethylenetetramine is 15:85:3" was modified to "the mass ratio of phenolic resin, isopropanol and hexamethylenetetramine is 50:50:10".

[0130] The prepared carbon aerogel composite material includes a carbon foam skeleton (melamine foam), and a carbon aerogel matrix (phenolic resin) attached and not attached to the carbon foam skeleton; and based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​99.1wt%, and the content of the carbon foam skeleton is 0.9wt%.

[0131] In addition, the average diameter of the nanopores of the prepared carbon aerogel composite material was 40 nm and the density was 0.55 g / cm 3, the room temperature thermal conductivity is 0.128W / m·K, the compressive strength is 6.95MPa; and the carbon aerogel composite material shrinks slightly during drying and carbonizes and cracks.

[0132] From the above results, it can be seen that the preferred embodiments 1-3 of the present invention have significantly better effects in terms of comprehensive performance such as low density, low thermal conductivity and high strength; in addition, although the sample in comparative example 1 has a lower room temperature thermal conductivity, its mechanical strength is too low and is not suitable for practical applications. The sample in comparative example 2 has a higher compressive strength, but its thermal conductivity is too high and is also not suitable for practical applications.

[0133] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A carbon aerogel composite material, It is characterized in that The carbon aerogel composite material comprises a carbon foam skeleton, and a carbon aerogel matrix attached to and not attached to the carbon foam skeleton; The precursor of the carbon aerogel matrix is ​​phenolic resin; the precursor of the carbon foam skeleton includes one or more of polyurethane foam, polyimide foam, melamine foam and phenolic foam.

2. The composite material according to claim 1, in, Based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​92-99wt%, and the content of the carbon foam skeleton is 1-8wt%; Preferably, based on the total weight of the carbon aerogel composite material, the content of the carbon aerogel matrix is ​​95-98wt%, and the content of the carbon foam skeleton is 2-5wt%.

3. The composite material according to claim 1 or 2, in, The preparation method of the phenolic resin comprises: 1) contacting phenol, aldehyde and catalyst to carry out a first reaction to obtain a light yellow viscous liquid; 2) adjusting pH and temperature to continue the second reaction; 3) After the second reaction is completed, vacuum treatment is performed to obtain a phenolic resin.

4. The composite material according to claim 3, in, The phenol is selected from one or more of phenol, m-cresol and resorcinol; and / or, the aldehyde is formaldehyde and / or furfural; And / or, the catalyst is oxalic acid and / or hydrochloric acid.

5. The composite material according to claim 3, in, The molar ratio of the phenol to the aldehyde is (0.5-2):1; and / or, the catalyst is used in an amount of 4-6% by mole of the phenol; And / or, the conditions of the first reaction include: temperature of 65-75°C, time of 0.5-2h; And / or, the conditions of the second reaction include: temperature of 80-95° C., time of 2-4 h, and pH of 6.5-7.

5.

6. The composite material according to any one of claims 1 to 5, in, The average molecular weight of the phenolic resin is 500-1500Da.

7. The carbon aerogel composite material according to any one of claims 1 to 6, in, The carbon aerogel composite material has a nanopore diameter of 50-200 nm and a density of 0.1-0.35 g / cm 3 , thermal conductivity ≥ 0.037W / m·K at room temperature, compressive strength ≤ 4.14MPa; Preferably, the carbon aerogel composite material has a nanopore diameter of 80-120 nm and a density of 0.11-0.21 g / cm 3 The thermal conductivity at room temperature is 0.037-0.061W / m·K, and the compressive strength is 0.34-4.14MPa.

8. A method for preparing the carbon aerogel composite material according to any one of claims 1 to 7, It is characterized in that The preparation method comprises: (1) contacting an organic resin, a curing agent, and a solvent to prepare an organic resin solution; (2) placing the organic porous foam in a mold, and then impregnating the organic resin solution into the organic porous foam at low pressure; (3) sealing the mold to carry out sol-gel reaction and then cooling to room temperature; (4) opening the mold and drying the aerogel obtained in step (3) to obtain an organic aerogel composite material with foam skeleton reinforcement; (5) Placing the organic aerogel composite material in an inert atmosphere for heat treatment to obtain a carbon aerogel composite material.

9. The preparation method according to claim 8, in, The density of the organic porous foam is 0.01-0.1 g / cm 3 ; And / or, the curing agent is hexamethylenetetramine; And / or, the solvent is selected from one or more of n-butanol, isopropanol, ethanol and ethylene glycol.

10. The preparation method according to claim 8, in, The concentration of the organic resin in the organic resin solution is 10-30wt%; And / or, the amount of the curing agent used is 10-25% of the organic resin by mass.

11. The preparation method according to claim 8, in, In step (2), the pressure of the low-pressure impregnation is ≤0.5 MPa, preferably 0.2-0.5 MPa; And / or, in step (3), the conditions of the sol-gel reaction include: temperature of 80-140° C., time of 24-48 h; And / or, in step (4), the drying conditions include: temperature of 20-120° C., time of 24-48 h; And / or, in step (5), the heat treatment conditions include: temperature of 600-1200° C. and time of 2-4 h.

12. Use of the carbon aerogel composite material according to any one of claims 1 to 7 in the field of thermal insulation.

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