High-temperature-resistant carbon fiber reinforced phenolic resin composite material and preparation method thereof

Abstract

The invention provides a high-temperature-resistant carbon fiber reinforced phenolic resin composite material and a preparation method thereof. The preparation method comprises the following steps: firstly, carrying out high-temperature oxidation treatment on carbon fibers; secondly, carrying out surface modification on the carbon fibers by using a chemical modifier; then mixing the modified carbon fiber, an antioxidant and a dispersing agent to prepare slurry; performing vacuum filtration on the prepared slurry, and drying to obtain a carbon fiber blank; preparing a phenolic resin infiltration solution, and impregnating the carbon fiber blank with the phenolic resin infiltration solution; and finally, carrying out mold pressing and curing to obtain the high-temperature-resistant carbon fiber reinforced phenolic resin composite The preparation method is simple in required equipment, convenient to operate, stable in process, high in production efficiency and suitable for large-scale industrial production. According to the high-temperature-resistant carbon fiber reinforced phenolic resin composite material prepared by the preparation method, the bonding property between the carbon fiber and the phenolic resin is improved, certain toughness and strength are provided, and meanwhile, the high-temperature-resistant carbon fiber reinforced phenolic resin composite material has the advantages of ablation resistance, good oxidation resistance in a high-temperature environment and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and particularly relates to a high-temperature resistant carbon fiber reinforced phenolic resin composite material and a preparation method thereof. Background Art

[0002] Carbon fiber is a high-performance fiber with a high carbon content (more than 90%). It has excellent properties such as high strength, high modulus, high temperature resistance, chemical corrosion resistance, low resistance, high thermal conductivity, and low thermal expansion. It is widely used as a reinforcing material due to its light weight and high strength, significantly improving the strength of materials such as resins, metals, ceramics, and cement. Among them, carbon fiber reinforced phenolic resin composites play a key role in thermal protection systems due to their excellent mechanical properties and anti-ablation properties.

[0003] However, the surface chemical activity of carbon fiber is relatively low, showing an inert state and lacking chemically active functional groups. This characteristic leads to poor adhesion between carbon fiber and composite matrix, which in turn limits the overall performance of carbon fiber composites. Therefore, it is necessary to find effective surface treatment methods to improve the surface properties of carbon fiber and enhance its bonding with the matrix material, so as to give full play to the advantages of carbon fiber composites. And with the increasing demand for the adaptation of the new generation of spacecraft to the high-speed and high-heat flux density external environment, the ablation resistance of existing carbon fiber reinforced phenolic resin composites is still facing challenges and needs to be further strengthened to meet more stringent operating conditions. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a high-temperature resistant carbon fiber reinforced phenolic resin composite material and a preparation method thereof. The preparation method is easy to operate, has a controllable process, high production efficiency, and is suitable for large-scale industrial production; the high-temperature resistant carbon fiber reinforced phenolic resin composite material prepared by the preparation method has excellent mechanical properties and anti-ablation properties.

[0005] A method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material comprises the following steps:

[0006] (1) placing the chopped carbon fibers in a high-temperature furnace for high-temperature oxidation treatment, then soaking them in an ethanol solution containing a silane coupling agent, then taking them out, washing them with ethanol, and drying them to obtain dry chopped carbon fibers;

[0007] (2) mixing the dried chopped carbon fiber, antioxidant, dispersant and water, and then mixing them by ultrasonic and mechanical stirring, and then vacuum filtering and drying to obtain a carbon fiber embryo;

[0008] (3) The carbon fiber embryo is immersed in a phenolic resin impregnation liquid prepared from ethanol, phenolic resin, boric acid, and a curing agent, and after the impregnation, the embryo is placed in a mold for molding and curing to obtain the high temperature resistant carbon fiber reinforced phenolic resin composite material.

[0009] In the above step (1):

[0010] Preferably, the chopped carbon fiber is one of polyacrylonitrile-based carbon fiber, asphalt-based carbon fiber, and viscose-based carbon fiber, and more preferably polyacrylonitrile-based carbon fiber.

[0011] Preferably, the length of the chopped carbon fibers is 3 to 10 mm.

[0012] Preferably, the temperature of the high temperature oxidation treatment is 300-500° C., and the time is 0.5-2 hours. More preferably, the temperature of the high temperature oxidation treatment is 400° C., and the time is 1 hour.

[0013] Preferably, the silane coupling agent is one of KH550, KH560 and KH570.

[0014] Preferably, in the ethanol solution containing the silane coupling agent, the mass ratio of ethanol to the silane coupling agent is (100-300):1.

[0015] Preferably, the chopped carbon fibers are immersed in the ethanol solution containing the silane coupling agent at a temperature of 50 to 60° C. for 8 to 16 hours, more preferably at a temperature of 50° C. for 12 hours.

[0016] In the above step (2):

[0017] Preferably, the antioxidant is one or more of silicon carbide, zirconium boride, silicon dioxide, and zirconium silicide, and more preferably one of silicon carbide, zirconium boride, and silicon dioxide.

[0018] Preferably, the average particle size of the antioxidant is 1 to 10 μm, more preferably 3 to 7 μm.

[0019] Preferably, the dispersant is one of polyacrylamide and polyethyleneimine, and more preferably polyethyleneimine.

[0020] Preferably, in a slurry formed by mixing chopped carbon fibers, an antioxidant, a dispersant and water,

[0021] The mass concentration of the chopped carbon fibers is 0.5 to 5%, more preferably 2 to 4%.

[0022] Preferably, in the slurry formed by mixing the chopped carbon fibers, the antioxidant, the dispersant and water, the mass of the dispersant is 0.5 to 1.5% of the mass of the chopped carbon fibers, and more preferably 0.6 to 1%.

[0023] Preferably, in the slurry formed by mixing the chopped carbon fibers, the antioxidant, the dispersant and water, the mass of the antioxidant is 5 to 10% of the mass of the chopped carbon fibers.

[0024] Preferably, the ultrasonic time is 10 to 30 minutes, more preferably 15 to 25 minutes.

[0025] Preferably, the mechanical stirring time is 60 to 120 min, more preferably 60 to 80 min.

[0026] Preferably, the drying temperature after vacuum filtration is 60-80° C., and the drying time is 20-30 h.

[0027] In the above step (3):

[0028] Preferably, in the phenolic resin impregnation liquid, the curing agent is hexamethylenetetramine.

[0029] Preferably, in the phenolic resin impregnation solution, the mass ratio of ethanol, phenolic resin, boric acid, and curing agent is (40-60): (40-60): (2-5): (8-12), and more preferably 40:60:3:9.

[0030] Preferably, the molding strength is 1 to 3 MPa and the molding time is 4 to 8 hours.

[0031] Preferably, the curing temperature is 120-150° C., the curing pressure is 1-3 MPa, and the curing time is 6-10 hours. More preferably, the curing temperature is 120° C., the curing pressure is 1 MPa, and the curing time is 8 hours.

[0032] It is worth noting that the ethanol mentioned in this article refers to anhydrous ethanol.

[0033] The preparation method of the high temperature resistant carbon fiber reinforced phenolic resin composite material of the present invention comprises the following steps: firstly subjecting the carbon fiber to high temperature oxidation treatment; secondly, using a chemical modifier to perform surface modification on the carbon fiber; then mixing the modified carbon fiber, an antioxidant, and a dispersant to prepare a slurry; vacuum filtering and drying the prepared slurry to obtain a carbon fiber embryo; then preparing a phenolic resin impregnation liquid, and impregnating the carbon fiber embryo with the phenolic resin impregnation liquid; and finally performing molding and curing to obtain a high temperature resistant carbon fiber reinforced phenolic resin composite material. The preparation method has relatively simple equipment required for the preparation process, convenient operation, stable process, high production efficiency, and is suitable for large-scale industrial production.

[0034] The present invention also provides a high temperature resistant carbon fiber reinforced phenolic resin composite material, which is prepared by any of the above-mentioned methods for preparing the high temperature resistant carbon fiber reinforced phenolic resin composite material.

[0035] The high temperature resistant carbon fiber reinforced phenolic resin composite material prepared by the preparation method of the present invention improves the bonding between carbon fiber and phenolic resin, provides certain toughness and strength, and has the advantages of anti-ablation performance and good oxidation resistance in high temperature environment.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The preparation method of the high-temperature resistant carbon fiber reinforced phenolic resin composite material of the present invention first removes the sizing agent on the surface of the carbon fiber through high-temperature oxidation treatment, and at the same time increases the specific surface area and surface roughness of the treated carbon fiber, and also increases the types and quantities of oxygen-containing functional groups on the surface; then, a silane coupling agent is selected to chemically modify the carbon fiber, thereby improving the wettability between the carbon fiber and the matrix, and improving the interface adhesion between the carbon fiber and the matrix, so that when the composite material is subjected to force, the carbon fiber can effectively share the stress, which is beneficial to improving the comprehensive performance of the composite material; at the same time, since the functional groups are introduced into the surface of the carbon fiber, it is also beneficial to disperse the carbon fiber in water in subsequent treatment.

[0038] The preparation method of the high-temperature resistant carbon fiber reinforced phenolic resin composite material of the present invention comprises the following steps: adding boric acid into a phenolic resin matrix, so that the phenolic resin forms BO bonds with large bond energy and good flexibility during the cross-linking and curing process, so that the heat resistance, instantaneous high temperature resistance and ablation resistance of the formed phenolic resin matrix are significantly improved compared with ordinary phenolic resins; in addition, the added boron or silicon antioxidant particles can form a flowing glassy substance at high temperature, which can seal the gap between the carbon fiber and the matrix, hinder the erosion of the inside of the composite material by oxygen, and effectively improve the ablation resistance of the composite material; and the antioxidant particles at high temperature have a certain adhesiveness, can play a role of physical bonding, and further improve the service life of the composite material.

[0039] The preparation method of the high temperature resistant carbon fiber reinforced phenolic resin composite material of the present invention has a simple preparation process, can greatly improve the anti-wire ablation performance of the composite material, has low cost, strong machinability, simple entire operation method, mild operating conditions, closely connected steps, and the prepared material has good performance.

[0040] The high temperature resistant carbon fiber reinforced phenolic resin composite material of the present invention has high bonding property between the carbon fiber and the phenolic resin matrix, good mechanical property and ablation resistance, and thus has a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1This is a process flow chart of Example 1 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments below; it is obvious that the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] Implementation 1

[0044] like Figure 1 As shown, a method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material comprises the following steps:

[0045] (1) 3 mm short-cut polyacrylonitrile-based carbon fibers were placed in a high-temperature furnace and treated at 400 °C for 1 h;

[0046] (2) Anhydrous ethanol and silane coupling agent KH550 are mixed uniformly in a mass ratio of 100:1 to form a solution, and the polyacrylonitrile-based short-cut carbon fibers after high-temperature treatment are placed therein and soaked at 50°C for 12 hours. After that, the soaked polyacrylonitrile-based carbon fibers are taken out and cleaned with anhydrous ethanol, and dried for later use;

[0047] (3) Add water to the dried polyacrylonitrile-based carbon fiber to prepare a 3% concentration solution, add 5% by mass of the polyacrylonitrile-based carbon fiber antioxidant silicon carbide (average particle size of 5 μm) and 0.8% of the dispersant polyethyleneimine, and subject to ultrasonic treatment for 20 minutes and mechanical stirring for 60 minutes to obtain a uniformly mixed slurry;

[0048] (4) vacuum filtering the slurry in step (3) to obtain a carbon fiber wet embryo, drying the carbon fiber wet embryo (80° C., 24 h) to obtain a carbon fiber embryo for standby use;

[0049] (5) Anhydrous ethanol, phenolic resin, boric acid, and hexamethylenetetramine are uniformly mixed in a mass ratio of 40:60:3:9 to prepare a phenolic resin impregnation solution ( Figure 1 The phenolic resin solution is shown in FIG. 1 ), and the dried carbon fiber embryo is impregnated with the prepared phenolic resin solution;

[0050] (6) The impregnated carbon fiber embryo is placed in a mold for molding and curing to obtain a high-temperature resistant carbon fiber reinforced phenolic resin composite material (carbon fiber / phenolic resin composite material); wherein the molding strength is 2 MPa and the time is 6 h; the curing temperature is 120 ° C, the curing pressure is 1 MPa, and the curing time is 8 h.

[0051] Implementation 2

[0052] A method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material comprises the following steps:

[0053] (1) Put 5 mm short-cut polyacrylonitrile-based carbon fiber into a high-temperature furnace and treat it at 400 °C for 1 h;

[0054] (2) Anhydrous ethanol and silane coupling agent KH560 are mixed uniformly in a mass ratio of 200:1 to form a solution, and the polyacrylonitrile-based short-cut carbon fibers after high-temperature treatment are placed therein and soaked at 50°C for 12 hours. After that, the soaked polyacrylonitrile-based carbon fibers are taken out and cleaned with anhydrous ethanol, and dried for later use;

[0055] (3) Add water to the dried polyacrylonitrile-based carbon fiber to prepare a 3% concentration solution, add 7% by mass of the polyacrylonitrile-based carbon fiber antioxidant zirconium boride (average particle size of 7 μm) and 0.8% of the dispersant polyethyleneimine, and subject to ultrasonic treatment for 20 minutes and mechanical stirring for 60 minutes to obtain a uniformly mixed slurry;

[0056] (4) vacuum filtering the slurry in step (3) to obtain a carbon fiber wet embryo, drying the carbon fiber wet embryo (80° C., 24 h) to obtain a carbon fiber embryo for standby use;

[0057] (5) Anhydrous ethanol, phenolic resin, boric acid, and hexamethylenetetramine are uniformly mixed in a mass ratio of 40:60:3:9 to prepare a phenolic resin impregnation solution, and the dried carbon fiber embryo is impregnated with the prepared phenolic resin solution;

[0058] (6) The impregnated carbon fiber embryo is placed in a mold for molding and curing to obtain a high-temperature resistant carbon fiber reinforced phenolic resin composite material (carbon fiber / phenolic resin composite material); wherein the molding strength is 2 MPa and the time is 6 h; the curing temperature is 120 ° C, the curing pressure is 1 MPa, and the curing time is 8 h.

[0059] Implementation 3

[0060] A method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material comprises the following steps:

[0061] (1) 7 mm short-cut polyacrylonitrile-based carbon fibers were placed in a high-temperature furnace and treated at 400 °C for 1 h;

[0062] (2) Anhydrous ethanol and silane coupling agent KH570 are mixed uniformly in a mass ratio of 300:1 to form a solution, and the high-temperature treated polyacrylonitrile-based chopped carbon fibers are immersed in the solution at 50°C for 12 hours, and then the immersed polyacrylonitrile-based carbon fibers are taken out and cleaned with anhydrous ethanol, and dried for use;

[0063] (3) Add water to the dried polyacrylonitrile-based carbon fiber to prepare a 3% concentration solution, add 9% by mass of the polyacrylonitrile-based carbon fiber antioxidant silicon dioxide (average particle size of 3 μm) and 0.8% of the dispersant polyethyleneimine, and subject to ultrasonic treatment for 20 minutes and mechanical stirring for 60 minutes to obtain a uniformly mixed slurry;

[0064] (4) vacuum filtering the slurry in step (3) to obtain a carbon fiber wet embryo, drying the carbon fiber wet embryo (80° C., 24 h) to obtain a carbon fiber embryo for standby use;

[0065] (5) Anhydrous ethanol, phenolic resin, boric acid, and hexamethylenetetramine are uniformly mixed in a mass ratio of 40:60:3:9 to prepare a phenolic resin impregnation solution, and the dried carbon fiber embryo is impregnated with the prepared phenolic resin solution;

[0066] (6) The impregnated carbon fiber embryo is placed in a mold for molding and curing to obtain a high-temperature resistant carbon fiber reinforced phenolic resin composite material (carbon fiber / phenolic resin composite material); wherein the molding strength is 2 MPa and the time is 6 h; the curing temperature is 120 ° C, the curing pressure is 1 MPa, and the curing time is 8 h.

[0067] Comparative Example 1: Short chopped carbon fiber is not subjected to high temperature oxidation treatment and silane coupling agent modification

[0068] The preparation method of the high temperature resistant carbon fiber reinforced phenolic resin composite material of this comparative example is the same as that of Example 1, except that the high temperature treatment and modification of the chopped polyacrylonitrile-based carbon fibers in steps (1) and (2) are omitted, and the chopped polyacrylonitrile-based carbon fibers are directly used for the preparation of the high temperature resistant carbon fiber reinforced phenolic resin composite material in subsequent steps (3) to (6).

[0069] Comparative Example 2: No antioxidant added

[0070] The preparation method of the high temperature resistant carbon fiber reinforced phenolic resin composite material of this comparative example is the same as that of Example 1, except that in step (3), no antioxidant silicon carbide is added to the slurry.

[0071] Performance Testing:

[0072] The density, room temperature thermal conductivity (thermal conductivity coefficient), bending modulus and linear ablation rate of the high temperature resistant carbon fiber reinforced phenolic resin composite materials prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were tested respectively. The results are shown in Table 1.

[0073] Among them, the thermal conductivity of high temperature resistant carbon fiber reinforced phenolic resin composites was tested using a Hot Disk TPS2500s heat flow instrument;

[0074] The bending modulus test of high temperature resistant carbon fiber reinforced phenolic resin composites is based on the "Test method for bending properties of three-dimensional braided fabrics and their resin-based composites" (GB / T 33621-2017);

[0075] The linear ablation rate of the high temperature resistant carbon fiber reinforced phenolic resin composite material was tested as follows: a sample with a size of Φ50×15mm was taken for oxyacetylene flame erosion (oxygen flow rate 1142L / h, acetylene flow rate 838L / h) ablation test, the distance between the sample and the nozzle was 20mm, and the ablation time was 10s.

[0076] Table 1 Performance data of high temperature resistant carbon fiber reinforced phenolic resin composite materials prepared in Examples 1 to 3 and Comparative Examples 1 and 2 It can be seen from Table 1 that the composite materials prepared in Examples 1 to 3 all have lower density and room temperature thermal conductivity, as well as good linear ablation rate and better mechanical properties (bending modulus), and have better comprehensive performance. Comparing the performance data of Example 1 and Comparative Example 1, it can be seen that the mechanical properties and ablation resistance of the composite material can be effectively improved after the carbon fiber is subjected to high-temperature oxidation treatment and silane coupling agent modification treatment. This is because after the carbon fiber is subjected to high-temperature treatment and modification, the carbon fiber and the matrix have better mechanical properties due to the physical and chemical combination. Comparing the performance data of Example 1 and Comparative Example 2, it can be seen that the addition of an antioxidant can greatly reduce the oxyacetylene linear ablation rate of the composite material, effectively improve the ablation resistance of the composite material; at the same time, it can also appropriately improve the mechanical properties (bending modulus) of the composite material.

[0077] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material, characterized in that: The following steps are involved: (1) placing the chopped carbon fibers in a high-temperature furnace for high-temperature oxidation treatment, then soaking them in an ethanol solution containing a silane coupling agent, then taking them out, washing them with ethanol, and drying them to obtain dry chopped carbon fibers; (2) mixing the dried chopped carbon fiber, antioxidant, dispersant and water, and then mixing them by ultrasonic and mechanical stirring, and then vacuum filtering and drying to obtain a carbon fiber embryo; (3) The carbon fiber embryo is immersed in a phenolic resin impregnation liquid prepared from ethanol, phenolic resin, boric acid, and a curing agent, and after the impregnation, the embryo is placed in a mold for molding and curing to obtain the high temperature resistant carbon fiber reinforced phenolic resin composite material.

2. The method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (1), the chopped carbon fiber is one of polyacrylonitrile-based carbon fiber, asphalt-based carbon fiber, and viscose-based carbon fiber; The length of the chopped carbon fibers is 3 to 10 mm.

3. The method for preparing the high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (1), the temperature of the high temperature oxidation treatment is 300 to 500° C. and the time is 0.5 to 2 h.

4. The method for preparing the high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: The silane coupling agent is one of KH550, KH560 and KH570.

5. The method for preparing the high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (1), in the ethanol solution containing the silane coupling agent, the mass ratio of ethanol to the silane coupling agent is (100-300):1; The immersion temperature of the chopped carbon fiber in the ethanol solution containing the silane coupling agent is 50-60° C., and the immersion time is 8-16 hours.

6. The method for preparing the high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (2), the antioxidant is one or more of silicon carbide, zirconium boride, silicon dioxide, and zirconium silicide; The average particle size of the antioxidant is 1 to 10 μm; The dispersant is one of polyacrylamide and polyethyleneimine.

7. The method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (2), in a slurry formed by mixing chopped carbon fibers, an antioxidant, a dispersant and water: The mass concentration of chopped carbon fiber is 0.5-5%; The mass of the dispersant is 0.5 to 1.5% of the mass of the chopped carbon fiber; The mass of the antioxidant is 5 to 10% of the mass of the chopped carbon fibers.

8. The method for preparing the high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (2), the ultrasonication time is 10 to 30 minutes; Mechanical stirring time is 60 to 120 minutes; The drying temperature after vacuum filtration is 60-80°C and the drying time is 20-30h.

9. The method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material according to claim 1, characterized in that: In step (3), the phenolic resin impregnation solution contains: The curing agent is hexamethylenetetramine; The mass ratio of ethanol, phenolic resin, boric acid and curing agent is (40-60): (40-60): (2-5): (8-12); The curing temperature is 120-150°C, the curing pressure is 1-3MPa, and the curing time is 6-10h.

10. A high temperature resistant carbon fiber reinforced phenolic resin composite material, characterized in that: The composite material is prepared by the method for preparing a high temperature resistant carbon fiber reinforced phenolic resin composite material according to any one of claims 1 to 9.

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