Method for improving directional heat-conducting property of thermal protection material

Abstract

According to the method for improving the directional heat conduction performance of the thermal protection material, the graphene heat conduction film with heat conduction anisotropy is introduced into the anti-ablation material, the surface heat conduction coefficient of the base material is increased, heat dissipation of a local overheat area of the material is accelerated, and therefore the service life of the anti-ablation composite material is prolonged. And meanwhile, the longitudinal low thermal conductivity of the graphene film is utilized, so that the heat insulation characteristic of an ablation-resistant material can be reserved. According to the method, a multi-layer composite mode is adopted, an anti-ablation phenolic resin material, high-strength ceramic fibers and a high-thermal-conductivity graphene film are fused, the interface bonding force is increased through fiber interpenetration, and meanwhile, the anti-ablation composite material is formed in a resin transfer molding mode. By utilizing the heat conduction anisotropy of the graphene film and designing the composite material structure, the effects of axial heat conduction and radial heat insulation of the back wall heat insulation material are realized, so that the temperature of the back surface of the material is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of carbon / carbon composite material manufacturing, and in particular to a method for improving the directional heat conduction performance of a heat protection material. Background Art

[0002] As one of the key components of a solid rocket engine, the back wall insulation layer is crucial to the engine's performance and operating safety. The back wall insulation layer can effectively protect the nozzle shell from damage caused by the high temperature heat generated when the engine is working. At present, the insulation material of solid rocket engines is mainly high-silicon phenolic resin molding material, which has a thermal conductivity of about 0.5W (mK), and can effectively isolate the engine heat at a lower heat flux density and a shorter working time. However, with the development of high-mobility tactical missile technology, the widespread use of high-energy propellants, and the increase in engine operating time, the high-temperature and high-pressure thermal environment to which the nozzle is subjected is becoming increasingly harsh, and the existing back wall insulation material is prone to carbonization failure, which will seriously affect the normal operation of the engine.

[0003] Polyphosphazene elastomer is a new generation of thermal insulation material with good anti-migration and low characteristic signal. As the corresponding polyphosphazene, the United States announced the application of aromatic polyphosphazene in rocket engine nozzles and internal insulation coatings at the end of the 20th century. However, the main principle of thermal insulation of existing back wall insulation materials is to absorb heat through carbonization and prevent heat from being transmitted to the nozzle shell. The main principle of thermal insulation of existing back wall insulation materials is to absorb heat through its own carbonization and prevent heat from being transmitted to the nozzle shell. This type of material cannot meet the development needs of future long-duration, multi-pulse solid engines. Summary of the invention

[0004] Based on the above problems, the present invention proposes a method for improving the directional heat conduction performance of thermal protection materials to solve the problems of poor performance of the back wall insulation materials of solid rocket engine nozzles, and realize the integration of heat insulation and temperature uniformity of the back wall layer materials.

[0005] In order to solve the above technical problems, one of the objects of the present invention is to provide a method for improving the directional thermal conductivity of thermal protection materials. A multilayer composite method is adopted to integrate anti-ablation phenolic resin materials, high-strength ceramic-based fiber materials, and ablation-resistant and high-thermal conductivity graphene thermal conductive films. The interfacial bonding strength is increased by interlacing fibers, and resin transfer molding is used to prepare anti-ablation graphene / quartz fiber / phenolic composite materials.

[0006] Furthermore, the specific steps are as follows:

[0007] S1: Prepare graphene film, use graphene thermal conductive film to shape anti-ablation composite material, use two kinds of graphene particles of large and small sizes as raw materials, and use wet method to self-assemble highly oriented and dense continuous graphene film;

[0008] S2: Graphene thermal conductive film and fiber cloth composite, firstly carry out numerical simulation of the needle punching process, simulate the web needle punching technology by virtual fiber technology, extract the fiber displacement change in the needle punching area, obtain the detailed geometric characteristics of local fiber deflection by function fitting, and use molecular dynamics method to simulate the thermal transport properties of graphene. Then, use the needle punching process to alternately stack quartz fiber felt and graphene thermal conductive film, and needle punch layer by layer to prepare quartz fiber felt / graphene thermal conductive film 3D needle punched preforms with different needle punching densities.

[0009] S3: Research and analysis of anti-ablation materials and graphene thermal conductive film / fiber cloth composite technology. The specific heat, anisotropic thermal conductivity and thermal diffusivity of three-dimensional needle-punched preforms were experimentally measured using a thermal constant analyzer to clarify the variation of anisotropic thermal conductivity with needle-punching density, and graphene / quartz fiber / phenolic composite materials were prepared using resin transfer molding technology.

[0010] S4: Test and verify the performance of graphene / quartz fiber / phenolic composite materials.

[0011] Furthermore, the specific steps of preparing the graphene film in S1 are:

[0012] S11: Improve the structural density of the membrane material. Use large and small graphene particles as raw materials to prepare a highly oriented, highly dense continuous graphene film by wet self-assembly. Use small-sized graphene particles as filling materials to fill the interlayer gaps and contact gaps generated when large-sized graphene particles are assembled into a membrane layer by layer, thereby improving the structural density of the membrane material.

[0013] S12: Prepare graphene thick film by secondary molding method, and screen out the best secondary molding preparation method through the performance advantages and disadvantages of graphene thick film prepared by different secondary molding methods, so as to achieve effective overlapping and bonding of multi-layer graphene films and prepare high thermal conductivity graphene thick film without interface delamination.

[0014] Furthermore, the secondary molding method is swelling bonding, graphene oxide bonding or metal ion bonding.

[0015] Furthermore, the S2 carries out numerical simulation of the needling process, and the specific steps are as follows:

[0016] S21: Use virtual fiber technology to simulate the web needle punching technology, extract the fiber displacement changes in the needle punching area, and then obtain the detailed geometric characteristics of the local fiber deflection by function fitting;

[0017] S22: This algorithm can be used to generate a random fiber network, and then the fiber network model is compressed until it is densified so that its fiber volume content reaches the state of the real web layer. Based on the principle of equivalent bending stiffness, an equivalent spring constraint is applied to each fiber, and then the web layer model is obtained after compression;

[0018] S23: Based on the fiber damage simulation, the damage state of the fiber bundle and the damage state of the graphene film under different needle puncture states are obtained;

[0019] S24: The web needle punching technique is simulated by virtual fiber technology, and the fiber displacement change in the needle punching area is extracted, and the detailed geometric characteristics of the local fiber deflection are obtained by function fitting;

[0020] S25: Based on the fiber damage simulation, the damage state of the fiber bundle and the damage state of the graphene film under different needle puncture states are obtained;

[0021] S26: Molecular dynamics method is used to simulate the thermal transport properties of graphene.

[0022] Furthermore, the S5 test performance includes density test, porosity test, bending performance test, thermal conductivity test, thermal expansion coefficient test and high temperature mechanical test.

[0023] Furthermore, the S1 highly oriented large-particle graphene serves as the main material and main structural unit of the high thermal conductivity film material to ensure the thermal conductivity and mechanical properties of the material; the small-particle graphene serves as a filling material to fill the interlayer gaps and interface gaps generated when the large-particle graphene layers are assembled into a film, thereby improving the structural density of the film material.

[0024] The above one or more technical solutions of the present invention have at least one or more of the following technical effects:

[0025] Based on the advantages of heat protection, heat insulation, temperature uniformity, strong shear resistance, low linear ablation rate and high carbonization rate, the present invention can be widely used in the thermal protection system of aircraft in the future. The thermal protection system accounts for a large proportion of the aircraft and is an important guarantee for the safety and reliability of the aircraft. The selection of this composite material will solve the current technical pain points in the industry from several aspects: improving the tolerance temperature; long-term oxidation resistance; thermal shock resistance; application as the main load-bearing structure; and significant weight reduction.

[0026] The present invention utilizes the thermal conductivity anisotropy of the graphene film and designs a composite material structure to achieve the effects of axial heat conduction and radial heat insulation of the back wall insulation material, thereby effectively reducing the temperature of the back side of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : Graphene film preparation process flow chart of the present invention;

[0028] Figure 2 : Schematic diagram of composite material laying and needle punching process. Specific implementation plan

[0029] Introducing thermally anisotropic graphene films into thermal protection materials increases the in-plane thermal conductivity of the material, accelerating the heat dissipation of the local heated area of ​​the insulation layer material, thereby improving the directional thermal conductivity of the material. In addition, the graphene film has a low longitudinal thermal conductivity, which is conducive to achieving the thermal insulation performance of the material. The present invention will adopt a multi-layer composite method to integrate phenolic resin materials and high-strength ceramic-based fiber materials into the preform of the composite material, ultimately achieving the goal of high thermal insulation.

[0030] A method for improving the directional thermal conductivity of thermal protection materials is to introduce thermally anisotropic graphene thermal conductive films into anti-ablation materials, increase the thermal conductivity coefficient on the surface of the base material, accelerate the heat dissipation of the local overheating area of ​​the material, and thus extend the service life of the anti-ablation composite material. At the same time, the low longitudinal thermal conductivity of the graphene film can be used to retain the thermal insulation properties of the anti-ablation material. This method intends to use a multi-layer composite method to integrate anti-ablation phenolic resin materials, high-strength ceramic fibers, and high thermal conductivity graphene films. The interfacial bonding force is increased by interlacing the fibers, and the resin transfer molding method is used to form an anti-ablation composite material.

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the obtained embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0032] In order to solve the problem of poor performance of the back wall insulation material of the solid rocket engine nozzle, a high thermal insulation graphene / quartz fiber / phenolic composite material was invented. The present invention will achieve the goal of thermal insulation and temperature uniformity integration of the back wall material based on the composite process technology of graphene and quartz fiber. The specific technical solution implementation process is as follows:

[0033] Design method of graphene / quartz fiber / phenolic composites

[0034] In anti-ablation materials, the introduction of graphene thermal conductive films with various thermal conductivity anomalies can increase the thermal conductivity coefficient on the surface of the base material, accelerate the heat dissipation of the local overheating area of ​​the material, thereby extending the service life of the anti-ablation composite material. At the same time, the longitudinal thermal conductivity is low, which can retain the thermal insulation properties of the anti-ablation material. This method intends to adopt a multi-layer composite method, integrating anti-ablation phenolic resin materials, high-strength ceramic-based fiber materials, and ablation-resistant high-thermal conductivity graphene thermal conductive films, increase the interface bonding force by interlacing fibers, and use resin transfer molding to prepare anti-ablation composite materials. The effective combination of the three materials can give full play to their respective advantages, and ultimately achieve the material's high temperature resistance, long-duration application, and excellent antioxidant properties. The developed system can easily realize the switching of material functions, thereby bringing controllable advantages in performance, and can then be expanded to high-thermal conductivity structural composites and directional high-thermal conductivity graphene / carbon-carbon composite materials.

[0035] Step 1: Prepare graphene film

[0036] This step is aimed at the preparation of high-performance graphene thick films.

[0037] (1) Improve the structural density of the membrane material. Using graphene of large and small particle sizes as raw materials, a highly oriented, highly dense continuous graphene film is prepared by wet self-assembly. The small-sized graphene is used as a filling material to fill the interlayer gaps and contact gaps generated when the large-sized graphene is assembled layer by layer into a membrane, thereby improving the structural density of the membrane material.

[0038] (2) In order to solve the problem that the thermal conductivity of graphene film decreases with the increase of thickness, a secondary molding method is used to prepare graphene thick film. The performance of graphene thick film prepared by different secondary molding methods such as swelling bonding, graphene oxide bonding and metal ion bonding is compared, and the best secondary molding preparation method is screened to achieve effective overlapping bonding of multi-layer graphene films and prepare high thermal conductivity graphene thick film without interface delamination. The graphene film preparation process route is as follows: Figure 1 .

[0039] Step 2: Design the composite process of graphene thermal conductive film and fiber cloth

[0040] (1) Numerical simulation of the needle punching process

[0041] a) If Figure 2 As shown, the web needle punching technology is simulated by virtual fiber technology, and the fiber displacement changes in the needle punching area are extracted, and then the detailed geometric characteristics of the local fiber deflection are obtained by function fitting;

[0042] b) This algorithm can be used to generate a random fiber network, and then the fiber network model is compressed until it is densified so that its fiber volume content reaches the state of the real web layer. Based on the principle of equivalent bending stiffness, an equivalent spring constraint is applied to each fiber, and then the web layer model obtained after compression;

[0043] c) Based on the fiber damage simulation, the damage state of the fiber bundle and the damage state of the graphene film under different needle puncture states are obtained;

[0044] d) simulating the web needle punching technology through virtual fiber technology, extracting the fiber displacement change in the needle punching area, and then obtaining the detailed geometric characteristics of the local fiber deflection through function fitting;

[0045] e) Based on the fiber damage simulation, the damage state of the fiber bundle and the damage state of the graphene film under different needle puncture states are obtained;

[0046] f) Using molecular dynamics method to simulate the thermal transport properties of graphene;

[0047] (2) Conduct acupuncture process research

[0048] The quartz fiber felt and graphene thermal conductive film were alternately stacked and needle-punched layer by layer using a needle-punching process to prepare quartz fiber felt / graphene thermal conductive film 3D needle-punched preforms with different needle-punching densities.

[0049] Step 3: Analysis of composite technology of anti-ablation materials and graphene thermal conductive film / fiber cloth

[0050] The specific heat, anisotropic thermal conductivity and thermal diffusivity of the three-dimensional needle-punched preform were experimentally measured using a thermal constant analyzer to clarify the variation of anisotropic thermal conductivity with needle-punching density, and the graphene / quartz fiber / phenolic composite material was prepared by resin transfer molding process.

[0051] Step 4: Test and verify the performance of graphene / quartz fiber / phenolic composite materials, including density, porosity testing, bending performance, thermal conductivity, thermal expansion coefficient, and high-temperature mechanical properties.

[0052] Thermophysical properties represented by thermal conductivity (W / (m·K)) and linear expansion coefficient (10-6 / ℃) are the main performance parameters of graphene / quartz fiber / phenolic composite materials, and are also indispensable data in the design of thermal insulation composite materials. Among them, thermal conductivity is the heat energy transferred by a unit thickness of material through a unit heat conduction surface per unit time under a unit temperature gradient. In this experiment, the LFA427 laser thermal conductivity meter was used to test the thermal conductivity of the sample. The sample size was Φ12.6mm×3mm. The thermal conductivity of the composite material was tested along the fiber direction of the non-wefted fabric (XY direction) and perpendicular to the direction (Z direction). During the test, high-purity helium (99.999%) was used as the protective gas, the heating rate was 20℃ / min, the test temperature range was 100~1900℃, and a measurement was performed every 200℃ during the test. Three data were collected for each measurement, and the average value was taken as the final result.

[0053] Thermal expansion is the phenomenon that the volume or length of an object changes with temperature. It reflects the thermal stability of the material size and indicates the average relative elongation of the material. This paper mainly tests the thermal expansion coefficient α of the material. The formula can be obtained

[0054]

[0055] In the formula: L0—original length of the sample (mm); L1—length of the sample at temperature t1 (mm); L2—length of the sample at temperature t2 (mm); t1—initial temperature of the sample (℃); t2—test temperature of the sample (℃).

[0056] This experiment uses a push rod test method to test the thermal expansion performance of the sample. The test equipment is a DIL-402E thermal expansion instrument, and the sample size is Φ6mm×10mm. During the test, high-purity helium (99.999%) is used as the protective gas, the heating rate is 5℃ / min, the test temperature range is 30~1300℃, and three samples are measured for each material.

[0057] Thermal conductivity, thermal expansion coefficient and test results are shown in the table below

[0058]

[0059] The high-strength composite technology of graphene thermal conductive film and quartz fiber, the needle-punched composite material is more excellent in interlayer performance compared to layered molding, and is simpler and cheaper than weaving molding. The pores of the preform formed by needle-punching are more uniform, and the densification is simpler, which is conducive to processing and production. It can still maintain excellent performance of stiffness and strength under high temperature environment, and has been widely used in aerospace, aviation and other fields. Based on this, the present invention first carried out a numerical simulation of the needle-punching process, and based on this, the quartz fiber felt and graphene thermal conductive film were staggered and stacked by needle-punching process, and needle-punched layer by layer to prepare quartz fiber felt / graphene thermal conductive film three-dimensional needle-punched preforms with different needle-punching densities, and the microstructure of the preform was tested and analyzed.

[0060] The present invention utilizes the thermal anisotropy of graphene film to achieve lateral heat transfer and longitudinal thermal insulation of composite materials. In the present invention, the thermal anisotropy of graphene film is introduced into the anti-ablation material to increase the thermal conductivity of the base material, so that the local overheating area of ​​the material is accelerated to dissipate heat, thereby extending the service life of the anti-ablation composite material. At the same time, the longitudinal thermal conductivity is low, and the thermal insulation properties of the anti-ablation material can be retained. The present invention will adopt a multi-layer composite method to integrate anti-ablation phenolic resin materials, high-strength ceramic fibers, and high thermal conductivity graphene films. The interfacial bonding force is increased by interlacing the fibers, and the resin transfer molding method is used to obtain an anti-ablation composite material. It can effectively achieve the goal of thermal insulation and temperature uniformity integration of the back wall layer material, and can significantly improve the performance and working safety of the solid rocket engine.

[0061] This achievement can be widely used in the solid rocket thermal protection components that are currently being finalized and developed. Facing the demand for fast, efficient and refined manufacturing processes, the project results can provide effective guarantees.

[0062] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for improving the directional heat conduction performance of a thermal protection material, characterized in that: A multi-layer composite method is adopted to integrate anti-ablation phenolic resin materials, high-strength ceramic-based fiber materials, and ablation-resistant and high-thermal conductivity graphene thermal conductive films. The interfacial bonding strength is increased by interlacing fibers, and resin transfer molding is used to prepare anti-ablation graphene / quartz fiber / phenolic composite materials.

2. The method for improving the directional heat conduction performance of a heat protection material according to claim 1, characterized in that: The specific steps are as follows: S1: Prepare graphene film, use graphene thermal conductive film to shape anti-ablation composite material, use two kinds of graphene particles of large and small sizes as raw materials, and use wet method to self-assemble highly oriented and dense continuous graphene film; S2: Graphene thermal conductive film and fiber cloth composite, firstly carry out numerical simulation of the needle punching process, simulate the web needle punching technology by virtual fiber technology, extract the fiber displacement change in the needle punching area, obtain the detailed geometric characteristics of local fiber deflection by function fitting, and use molecular dynamics method to simulate the thermal transport properties of graphene. Then, use the needle punching process to alternately stack quartz fiber felt and graphene thermal conductive film, and needle punch layer by layer to prepare quartz fiber felt / graphene thermal conductive film 3D needle punched preforms with different needle punching densities. S3: Research and analysis of anti-ablation materials and graphene thermal conductive film / fiber cloth composite technology. The specific heat, anisotropic thermal conductivity and thermal diffusivity of three-dimensional needle-punched preforms were experimentally measured using a thermal constant analyzer to clarify the variation of anisotropic thermal conductivity with needle-punching density, and graphene / quartz fiber / phenolic composite materials were prepared using resin transfer molding technology. S4: Test and verify the performance of graphene / quartz fiber / phenolic composite materials.

3. The method for improving the directional heat conduction performance of a heat protection material according to claim 2, characterized in that: The specific steps of preparing the graphene film in S1 are: S11: Improve the structural density of the membrane material. Use large and small graphene particles as raw materials to prepare a highly oriented, highly dense continuous graphene film by wet self-assembly. Use small-sized graphene particles as filling materials to fill the interlayer gaps and contact gaps generated when large-sized graphene particles are assembled into a membrane layer by layer, thereby improving the structural density of the membrane material. S12: Prepare graphene thick film by secondary molding method, and screen out the best secondary molding preparation method through the performance advantages and disadvantages of graphene thick film prepared by different secondary molding methods, so as to achieve effective overlapping and bonding of multi-layer graphene films and prepare high thermal conductivity graphene thick film without interface delamination.

4. The method for improving the directional heat conduction performance of a heat protection material according to claim 3, characterized in that: The secondary molding method is swelling bonding, graphene oxide bonding or metal ion bonding.

5. The method for improving the directional heat conduction performance of a heat protection material according to claim 2, characterized in that: The S2 carries out numerical simulation of the needling process, and the specific steps are as follows: S21: Use virtual fiber technology to simulate the web needle punching technology, extract the fiber displacement changes in the needle punching area, and then obtain the detailed geometric characteristics of the local fiber deflection by function fitting; S22: This algorithm can be used to generate a random fiber network, and then the fiber network model is compressed until it is densified so that its fiber volume content reaches the state of the real web layer. Based on the principle of equivalent bending stiffness, an equivalent spring constraint is applied to each fiber, and then the web layer model is obtained after compression; S23: Based on the fiber damage simulation, the damage state of the fiber bundle and the damage state of the graphene film under different needle puncture states are obtained; S24: The web needle punching technique is simulated by virtual fiber technology, and the fiber displacement change in the needle punching area is extracted, and the detailed geometric characteristics of the local fiber deflection are obtained by function fitting; S25: Based on the fiber damage simulation, the damage state of the fiber bundle and the damage state of the graphene film under different needle puncture states are obtained; S26: Molecular dynamics simulation of graphene thermal transport properties.

6. The method for improving the directional heat conduction performance of a heat protection material according to claim 2, characterized in that: The S5 test performance includes density test, porosity test, bending performance test, thermal conductivity test, thermal expansion coefficient test and high temperature mechanical test.

7. The method for improving the directional heat conduction performance of a heat protection material according to claim 1, characterized in that: The S1 highly oriented large-particle graphene serves as the main material and main structural unit of the high thermal conductivity film material to ensure the thermal conductivity and mechanical properties of the material; the small-particle graphene serves as a filling material to fill the interlayer gaps and interface gaps generated when the large-particle graphene layers are assembled into a film, thereby improving the structural density of the film material.

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