Ablation in-situ antioxidant composite heat pipe type heat dissipation protection structure and manufacturing method

Abstract

The application provides an ablation in-situ oxidation-resistant composite heat pipe type heat dissipation and protection structure and a manufacturing method. The ablation in-situ oxidation-resistant composite heat pipe type heat dissipation and protection structure comprises a heat pipe type heat dissipation and protection structure and a composite material structure layer of ceramic powder / resin / metal dot array supported on the surface of the heat pipe type heat dissipation and protection structure. The heat pipe type heat dissipation and protection structure comprises a metal shell, a fluid transport channel and a capillary core structure. The capillary core structure is arranged on the inner surface of the metal shell and surrounds a closed steam flow cavity. The fluid transport channel is arranged in the metal shell and is connected with the capillary core structure. The composite material structure layer of ceramic powder / resin / metal dot array is prepared by taking the metal dot array porous layer and the ceramic powder as reinforcing materials and taking the resin as a base material and is used as a protective layer of the heat pipe type heat dissipation and protection structure. The composite of the composite material structure layer of ceramic powder / resin / metal dot array and the heat pipe type heat dissipation and protection structure enables the heat pipe type high-temperature heat dissipation and protection structure to be used in an oxygen-containing environment at 1650 DEG C for a long time.

Description

Technical Field

[0001] This invention belongs to the technical field of aerodynamic thermal protection systems in aerospace engineering, and specifically relates to an ablation in-situ anti-oxidation composite heat pipe thermal protection structure and its manufacturing method. This thermal protection structure is suitable for extreme thermal environments with extremely high heat flux density aerodynamic heating, and can be applied to areas with extremely high peak aerodynamic heating heat flux density and extremely uneven heat flux distribution, such as the nose cone and leading edge of aircraft, the leading edge of engine air intake, overflow port, and fuel injection support plate. Background Technology

[0002] When high-speed aerospace vehicles fly through the Earth's atmosphere, the intense collisions and friction between their high-speed solid surfaces and atmospheric gas molecules cause a rapid increase in gas temperature. This heat is continuously transferred to the vehicle's surface, generating aerodynamic heating. To prevent the high temperatures caused by aerodynamic heating from damaging the vehicle's structural safety, specialized materials or structures are typically designed on the vehicle's surface to control the impact of surface heat transfer, thus ensuring the safety of the vehicle's internal structure. This is also known as the vehicle's thermal protection system. Heat pipe-type thermal protection structures are based on the principle of heat pipe operation, molding the thermal protection components into an integrated vacuum-sealed cavity structure with an embedded capillary core structure, working fluid, and reinforcing structure. Under pneumatic heating, the condensed working fluid inside the heat-resistant structure undergoes a phase change, and the vapor structure circulates within the closed cavity. In the lower temperature region, the working fluid liquefies and condenses, and under the combined action of the capillary structure and vapor pressure, the liquid working fluid is transported to the high-temperature region, where it undergoes another phase change due to heating. The working fluid utilizes the capillary structure's cycle of "gas phase change - gas vapor movement - liquefaction and condensation - capillary transport - gas phase change" within the closed cavity to achieve heat transport within the heat-resistant structure. However, existing heat pipe-type high-temperature conductive heat-resistant structures use nickel-based superalloys, niobium-based superalloys, molybdenum-based, or tungsten-based refractory alloys as shell materials. Limited by the high-temperature mechanical properties and oxidation resistance of these shell materials, current heat pipe-type high-temperature conductive heat-resistant structures are still difficult to use for extended periods in an oxygen-rich environment at 1650℃. Summary of the Invention

[0003] In order to overcome the shortcomings of the existing technology, the inventors have conducted intensive research and provided an ablation in-situ anti-oxidation composite heat pipe thermal protection structure and manufacturing method. By combining a composite material structure layer composed of ceramic powder / resin / metal lattice with a heat pipe thermal protection structure, the heat pipe high-temperature thermal protection structure can be used for a long time in an oxygen-containing environment at 1650℃.

[0004] The technical solution provided by this invention is as follows:

[0005] In a first aspect, an ablation in-situ anti-oxidation composite heat pipe thermal protection structure is provided, comprising a heat pipe thermal protection structure and a composite material structure layer composed of ceramic powder / resin / metal lattice supported on its surface.

[0006] The heat pipe-type heat-resistant structure includes a metal shell, fluid transport channels, and a capillary structure. The capillary structure is disposed on the inner surface of the metal shell and is used for the condensation, adsorption, and reflux of the working fluid vapor. The inner side of the capillary structure forms a closed vapor flow cavity. The fluid transport channels are opened inside the metal shell and are connected to the capillary structure to form the working fluid transport channels of the heat pipe-type heat-resistant structure.

[0007] The composite material structure layer composed of ceramic powder / resin / metal lattice uses a porous metal lattice layer and ceramic powder as reinforcing materials, and preferably phenolic resin as the matrix material, to serve as a protective layer for a heat pipe-type heat-conducting and heat-insulating structure.

[0008] Secondly, a method for manufacturing an ablation-in-situ anti-oxidation composite heat pipe thermal protection structure includes the following steps:

[0009] The metal structure in the composite heat pipe thermal protection structure is formed, and the heat pipe working fluid is filled.

[0010] A siloxane is added to a phenolic resin, and the siloxane-modified phenolic resin is mixed with ceramic powder to obtain a modified phenolic resin / ceramic powder slurry.

[0011] The heat pipe-type venting metal structure is placed in a sealed bag and placed in an RTM device. The modified phenolic resin / ceramic powder mixture is injected into the heat pipe-type venting metal structure through the vacuum-assisted resin transfer molding (VARTM) process.

[0012] After the VARTM process is completed, the entire vacuum bag is placed into a cold isostatic pressing (CIP) machine for cold isostatic pressing treatment.

[0013] After cold isostatic pressing, the composite resin is cured.

[0014] After the composite material has cured, the vacuum bag is removed, and the surface is repaired or machined to obtain an ablation in-situ anti-oxidation composite heat pipe thermal protection structure.

[0015] The ablation-in-situ anti-oxidation composite heat pipe thermal protection structure and manufacturing method provided by the present invention have the following beneficial effects:

[0016] (1) The present invention provides an ablation-in-situ anti-oxidation composite heat pipe-type heat-conducting thermal protection structure and its manufacturing method. A porous lattice structure is integrally formed on the metal shell of the heat pipe-type heat-conducting thermal protection structure. A flowable ceramic powder composite modified phenolic resin slurry is prepared and injected into the porous lattice structure through vacuum-assisted resin heat transfer molding and cold isostatic pressing, forming a composite structure with an outer layer of ceramic powder / resin / metal lattice and an inner layer of heat pipe-type heat-conducting thermal protection. When the outer ceramic powder / resin / metal lattice composite material is pneumatically heated, the modified phenolic resin generates silicon-oxygen-carbon ceramic products, which, under the action of the added ceramic powder in a high-temperature oxidizing atmosphere, form a high-temperature resistant multi-element oxide surface, thereby achieving in-situ high-temperature anti-oxidation. Furthermore, the pyrolysis carbonization products and ceramic powder form a composite matrix with a certain microporous structure, improving the thermal expansion compatibility with the metal skeleton and increasing the structural damage tolerance with ceramic oxidation products, overcoming the problem of thermal expansion incompatibility in traditional mechanically connected anti-oxidation shells. This heat protection structure is suitable for extreme thermal environments with extremely high heat flux density aerodynamic heating. It can be applied to areas with extremely high peak aerodynamic heating heat flux density, such as the nose cone and leading edge of aircraft, the leading edge of engine air intake, overflow port, and fuel injection support plate.

[0017] (2) Based on the respective advantages of the pulsating heat pipe and the vapor chamber heat pipe, the present invention carries out a collaborative design. It utilizes the rapid start-up characteristics of the pulsating heat pipe to accelerate the start-up process of the overall ventilating structure, and utilizes the high heat transfer power characteristics of the vapor chamber heat pipe to improve the ultimate heat transfer capacity of the overall ventilating structure. This achieves a synergistic improvement in the start-up capacity and heat transfer capacity of the heat pipe-type ventilating thermal protection structure. In particular, the rapid start-up performance of the ventilating structure effectively improves the thermal adaptability of the overall ventilating structure under high heat flux density thermal shock load conditions, thereby improving the non-ablative thermal protection capability of the thermal protection system of high-speed aerospace vehicles. Attached Figure Description

[0018] Figure 1 The appearance of the ablation in-situ anti-oxidation composite heat pipe thermal protection structure (spherical cone shape schematic diagram);

[0019] Figure 2 A cross-sectional view of an ablation-resistant in-situ anti-oxidation composite heat pipe thermal protection structure (schematic diagram of the shape of a ball and cone);

[0020] Figure 3 Cross-sectional view of the ablation-resistant in-situ anti-oxidation composite heat pipe thermal protection structure (spherical cone shape schematic diagram);

[0021] Figure 4 Cross-sectional view of the in-situ ablation anti-oxidation composite heat pipe thermal protection structure before resin slurry injection (spherical cone shape schematic diagram);

[0022] Figure 5This is a layout diagram of a pulsed heat pipe flow channel (without composite material structural layers);

[0023] Figure 6 Enlarged view of the pulsating heat pipe flow channel layout (without composite material structural layers);

[0024] Figure 7 It consists of a pulsed-vapor cavity composite heat pipe type heat conduction and thermal protection structure (without composite material structural layer);

[0025] Figure 8 Flowchart for the fabrication of an ablation-in-situ anti-oxidation composite heat pipe thermal protection structure;

[0026] Figure 9 This refers to the molding process of composite materials consisting of ceramic powder, resin, and metal lattices.

[0027] Explanation of icon numbers

[0028] 1: Composite material structural layer; 1-1: Metal lattice porous layer; 2: Metal shell; 3: Fluid transport channel; 4: Capillary wick structure; 5: Steam flow cavity; 6: Pulsating heat pipe channel; 7: Pulsating heat pipe channel distribution route; 10: Ablation in-situ anti-oxidation composite heat pipe thermal protection structure. Detailed Implementation

[0029] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0030] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0031] This invention provides an ablation-in-situ anti-oxidation composite heat pipe thermal protection structure. Figure 1 Using a spherical cone shape as a schematic diagram, the appearance of the ablation in-situ anti-oxidation composite heat pipe thermal protection structure 10 is shown. The molded product is an integrated structure.

[0032] Figure 2 A cross-section of a spherical cone-shaped ablation in-situ anti-oxidation composite heat pipe thermal protection structure is presented. Figure 3 A cross-sectional diagram of a spherical cone-shaped ablation-resistant in-situ oxidation-resistant composite heat pipe-type thermal protection structure is given. (See diagram below.) Figure 2 and Figure 3 As shown, the ablation in-situ anti-oxidation composite heat pipe thermal protection structure includes a heat pipe thermal protection structure and a composite material structure layer 1 composed of ceramic powder / resin / metal lattice supported on its surface.

[0033] The heat pipe-type heat-resistant structure includes a metal shell 2, a fluid transport channel 3, and a capillary wick structure 4. The capillary wick structure 4 is disposed on the inner surface of the metal shell 2 and is used for the condensation, adsorption, and reflux of the working fluid vapor. The inner side of the capillary wick structure 4 forms a closed vapor flow cavity 5. The fluid transport channel 3 is opened inside the metal shell 2 and is connected to the capillary wick structure 4 to form the working fluid transport channel of the heat pipe-type heat-resistant structure.

[0034] The composite material structure layer 1, composed of ceramic powder / resin / metal lattice, is made with a porous metal lattice layer 1-1 and ceramic powder as reinforcing materials, and preferably phenolic resin as the matrix material. It serves as a protective layer for a heat pipe-type heat-conducting and heat-protecting structure, solving the problem that heat pipe-type high-temperature heat-conducting and heat-protecting structures cannot work for a long time in an oxygen-rich environment at 1650℃. Figure 4 A cross-sectional view of the in-situ anti-oxidation composite heat pipe thermal protection structure with spherical cone shape before resin slurry injection is given. The in-situ anti-oxidation composite heat pipe thermal protection structure with spherical cone shape before resin slurry injection includes the main structural units such as a metal lattice porous layer 1-1, a metal shell 2 of the heat pipe thermal protection structure, a fluid transport channel 3, and a capillary core structure 4.

[0035] In a preferred embodiment of the present invention, the capillary core structure 4 can be modeled using a lattice structure, requiring that the diameter of the lattice connecting rods is no greater than 0.2 mm, the nominal pore size is no greater than 0.25 mm, and the nominal porosity is no less than 43%.

[0036] The fluid transport channel 3 can have cross-sectional structures such as circular, rectangular (square), "D" type, and "Ω" type. Figure 3 and Figure 4 A schematic diagram of an "Ω"-shaped channel is provided. To ensure good capillary force, the maximum geometric dimension of the fluid transport channel 3 is less than 0.5 mm.

[0037] The thickness of the metal casing 2 of the heat pipe-type heat-insulating structure is no more than 2 mm. The vapor flow cavity 5, enclosed by the capillary wick structure 4 inside the metal casing 2, serves as the flow space for the gaseous working fluid in the vapor chamber heat pipe. Before startup, the vapor flow cavity 5 is in a vacuum state, typically with a vacuum level better than 10. -4 Pa; Due to the uneven heating of the metal shell 2, there are working fluid evaporation zones and working fluid condensation zones in different areas of the steam flow cavity. The capillary wick structure 4 improves the adsorption capacity of the gaseous working fluid in the condensation zone to condense into liquid working fluid, and the fluid transport channel 3 improves the transport capacity of the liquid working fluid from the condensation zone to the evaporation zone.

[0038] The working medium in the steam flow cavity 5, which is enclosed by the transport channel 3 and the capillary wick structure 4, can be selected according to the operating temperature: alkali metals and their alloys, alkaline earth metals and their alloys, mercury (Hg), lead (Pb), lead-bismuth alloy (PbBi), copper (Cu) and silver (Ag), etc.

[0039] In a preferred embodiment of the present invention, the metal lattice porous layer 1-1 in the composite material structural layer 1 has a lattice structure with a nominal porosity of not less than 40%, a maximum pore size of not more than 0.3 mm, a minimum pore size of not less than 0.1 mm, and the unit cell of the lattice structure is any one or more of the Bravais lattice structures.

[0040] The ceramic powder in the composite structural layer 1 is selected from at least one of transition metal carbides, transition metal borides, or transition metal nitrides, preferably with a particle size of less than 10 μm. The transition metal carbides include, but are not limited to, at least one of HfC, ZrC, or TaC; the transition metal borides include, but are not limited to, at least one of HfB2, ZrB2, or TiB2; and the transition metal nitride ceramics include, but are not limited to, at least one of TaN, HfN, TiN, or ZrN.

[0041] In the composite material structural layer 1, siloxane is added to the resin matrix to improve the compatibility between phenolic resin and ceramic powder. The siloxane can be selected from at least one of monomethyldimethoxysiloxane, 3-aminopropyltriethoxysilane or 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and the mass ratio of phenolic resin to siloxane is controlled at 20:1 to 15:1.

[0042] During their research on heat pipe-type heat-conducting structures, the inventors discovered that these structures, based on the vapor chamber heat pipe principle, suffer from drawbacks such as long start-up times and weak adaptability to high heat flux density thermal shocks. Under high heat flux density heating conditions, delayed start-up can lead to ablation and damage to the structural shell. Therefore, the inventors have improved existing vapor chamber heat pipe-type heat-conducting structures by synergistically designing them using the advantages of both pulsating heat pipes and vapor chamber heat pipes. This approach accelerates the start-up process of the pulsating heat pipes and enhances the overall heat transfer capacity of the structure by utilizing the high heat transfer characteristics of the vapor chamber heat pipes. This achieves a synergistic improvement in the start-up and heat transfer capabilities of the heat pipe-type heat-conducting structure, further enhancing the non-ablative heat protection capability of thermal protection systems for high-speed aerospace vehicles.

[0043] like Figure 5 and Figure 6As shown, a pulsating heat pipe channel 6 is formed inside the metal shell 2 of the heat pipe-type heat-insulating structure. The pulsating heat pipe channel 6 and the fluid transport channel 3 are both arranged on the inner surface of the metal shell 2, forming a conductive layer. The pulsating heat pipe channel 6 is a closed pipe connected end to end. After the metal shell 2 is heated or receives heat transfer from the composite material structure layer 1, the working fluid in the pulsating heat pipe channel 6 circulates in the closed pipe, transporting heat to the flow area.

[0044] Preferably, the pulsating heat pipe flow channel distribution route 7 is evenly distributed across the inner surface of the metal shell 2 along a path that is as long as possible. The working fluid in the pulsating heat pipe flow channel 6 can be appropriately selected according to the operating temperature of the heat-conducting protective structure, such as thermally conductive metals, molten salts, alkali metals, alkaline earth metals, heavy metals, noble metals, or rare metals. The cross-section of the pulsating heat pipe flow channel 6 can be designed according to the wall constraints and flow characteristics, and can be circular, rectangular, "D"-shaped, or "Ω"-shaped. Figure 5 and Figure 6 The schematic diagram is a "D" shaped flow channel.

[0045] In this invention, the metal lattice porous layer 1-1 of the ablation in-situ anti-oxidation composite heat pipe-type heat-conducting thermal protection structure, together with the metal shell 2, fluid transport channel 3, capillary core structure 4, and optional pulsating heat pipe flow channel 6 of the heat pipe-type heat-conducting thermal protection structure, constitutes a heat pipe-type heat-conducting metal structure, which is formed by integrated additive manufacturing. The refractory metal spherical powder used in additive manufacturing is selected from molybdenum powder, tantalum powder, tungsten powder, molybdenum-rhenium alloy powder, tantalum-tungsten alloy powder, or tungsten-rhenium alloy powder, preferably with a particle size distribution range of 10-30 μm, an oxygen content of not more than 200 ppm, a loose density of about 30%-60% (e.g., 55%) of the theoretical density, a tap density of about 50%-75% (e.g., 66%) of the theoretical density, and a Hall flow rate (50g) of not more than 7.0 s.

[0046] The overall workflow of the ablation-in-situ anti-oxidation composite heat pipe thermal protection structure of the present invention, when it has a pulsating heat pipe flow channel, is as follows:

[0047] The metal shell 2 of the heat pipe-type heat-conducting and heat-protecting structure is wholly or partially subjected to heat transfer from the composite material structural layer 1. The working fluid in the pulsating heat pipe channel 6 begins to flow inside the pipe, simultaneously transporting heat to the flow area. The steam chamber heat pipe starts to operate under the heat transfer of the pulsating heat pipe channel and the composite material structural layer 1. Different regions within the steam flow chamber experience working fluid evaporation phase change, steam flow, and steam condensation. In the lower temperature region, the gaseous working fluid condenses in the capillary wick structure 4, which has enhanced adsorption capacity. Under the combined action of capillary force and gas pressure, the condensed working fluid is transported through the fluid transport channel 3 from the working fluid condensation region (lower temperature region) to the working fluid evaporation phase change region (higher temperature region). This cycle repeats until the composite pulsating / steam chamber heat pipe-type high-temperature heat-conducting and heat-protecting structure forms an approximately isothermal body, dissipating the input heat flow through full surface area radiation heat dissipation and reaching an equilibrium state, at which point the system reaches a stable operating state.

[0048] The present invention correspondingly provides a method for preparing an ablation in-situ anti-oxidation composite heat pipe thermal protection structure, such as... Figure 8 As shown, the main processes include three main steps: integrated additive manufacturing of heat pipe-type conductive metal structures, preparation of modified phenolic resin / ceramic powder mixed slurry, VARTM injection of mixed slurry into porous metal structures, and cold isostatic pressing densification of composite materials.

[0049] Step 1: Integrated additive manufacturing of heat pipe-type conductive metal structure

[0050] Step 1-1: Select a suitable additive manufacturing process, such as selective laser melting (SLM) or selective electron beam melting (EBSM), to complete the molding of the metal lattice porous layer 1-1, the heat pipe-type heat-resistant metal shell 2, the fluid transport channel 3, and the capillary core structure 4 in the heat pipe-type conductive metal structure. When the structure has a pulsating heat pipe channel 6, it is integrally molded with the above-mentioned metal structure. After molding, the surface powder is cleaned, and the surface is ultrasonically cleaned in ethanol solvent, then naturally air-dried in a cleanroom.

[0051] Steps 1-2: After drying, the heat pipe-type heat-conducting metal structure is checked for sealing using a gas leak detection method. The requirement is that there should be no gas leakage within the inner cavity of the heat pipe-type heat-conducting heat-resistant metal shell 2 under an air or nitrogen pressure of 1.5 MPa. If a leak occurs, the leak point is marked, and the leak is repaired using an electron beam scanning surface densification method. If the cavity sealing performance meets the requirements, further high-temperature vacuum degassing treatment is performed on the vapor flow cavity 5 enclosed by the fluid transport channel 3, the capillary core structure 4, and the pulsating heat pipe channel 6. The vacuum degassing temperature is not lower than 700℃, and the vacuum degree inside the high-temperature furnace during treatment is not lower than 10. -4 Pa.

[0052] Steps 1-3: After the heat pipe-type conductive metal structure is degassed at high temperature, the heat pipe is filled with high-temperature working fluid, including the filling of working fluid in the steam flow cavity 5 formed by the fluid transport channel 3 and the capillary core structure 4, and the filling of the corresponding working fluid in the pulsating heat pipe channel 6.

[0053] The amount of working fluid filled in the steam flow cavity 5, enclosed by the fluid transport channel 3 and the capillary structure 4, is determined jointly by the volumes of the capillary structure 4 and the fluid transport channel 3. After filling with the working fluid under high vacuum conditions, the cavity is sealed; the vacuum level during filling is not lower than 10. -4 Under high vacuum conditions, the pumping time of the molecular pump shall not be less than 4 hours.

[0054] Steps 1-4: After the working fluid is filled, the heat pipe-type conductive metal structure must undergo high-temperature wetting treatment. The wetting treatment temperature shall not be lower than 1.2 times the melting point temperature of the filling working fluid, and the high-temperature wetting time shall not be less than 8 hours.

[0055] Steps 1-5: After the heat pipe-type conductive metal structure is filled, a static heating environment start-up test can be conducted. Induction heating, radiant heating, or resistance heating can be used as the heat source. One side of the heat pipe-type conductive metal structure (approximately 1 / 3 of the total length) is designated as the heating section, the middle insulating section (approximately 1 / 3 of the total length) is insulated with a low thermal conductivity material (such as quartz fiber felt), and the other side (approximately 1 / 3 of the total length) is designated as the radiative heat dissipation condensation section. The start-up performance of the heat pipe-type conductive metal structure is tested. The temperatures of the heating section, the middle insulating section, and the radiative heat dissipation condensation section are monitored respectively. After the temperature of the heating section rises to the target operating temperature and is maintained for a certain time (e.g., at least 15 minutes), if the temperature difference between the middle insulating section and the radiative heat dissipation condensation section and the heating section does not exceed 10% of the temperature of the heating section, the start-up performance of the heat pipe-type conductive metal structure is considered good, and the next step can be carried out; otherwise, the heat pipe-type conductive metal structure is considered to have failed, and the structure preparation must be restarted from [Step 1-1].

[0056] Steps 1-6: After the performance test is passed, the heat pipe-type ventilated metal structure is cleaned and dried for later use.

[0057] Step 2, Preparation of modified phenolic resin / ceramic powder slurry

[0058] A siloxane is added to phenolic resin, and the siloxane-modified phenolic resin is mixed with ceramic powder. The mixture is then ball-milled using a planetary ball mill to obtain a modified phenolic resin / ceramic powder slurry. Preferably, the viscosity of the modified phenolic resin / ceramic powder slurry is measured, and the viscosity is adjusted using anhydrous ethanol to maintain it at 0.5–1.5 Pa·s at room temperature (25°C). After viscosity adjustment, the mixture is placed in a tank for VARTM molding of the composite material.

[0059] In this step, a suitable phenolic resin for VARTM molding is selected, requiring a solid phenolic content of not less than 60%. Commonly used resins include barium phenolic resin and boron phenolic resin. A siloxane is added to the phenolic resin to improve the compatibility between the phenolic resin and the ceramic powder. The siloxane can be selected from at least one of monomethyldimethoxysiloxane, 3-aminopropyltriethoxysilane, or 3-(2,3-epoxypropoxy)propyltrimethoxysilane, with the mass ratio of phenolic resin to siloxane controlled between 20:1 and 15:1.

[0060] In this step, the ceramic powder is selected from at least one of transition metal carbides, transition metal borides, or transition metal nitrides, preferably with a particle size of less than 10 μm. Transition metal carbides include, but are not limited to, at least one of HfC, ZrC, or TaC; transition metal borides include, but are not limited to, at least one of HfB2, ZrB2, or TiB2; transition metal nitride ceramics include, but are not limited to, at least one of TaN, HfN, TiN, or ZrN. These can be used individually or in combination, such as a mass ratio of HfC, ZrC, and TaC of 1:1:1; a mass ratio of HfB2, ZrB2, and TiB2 of 1:1:1; a mass ratio of TaN, HfN, and ZrN of 1:1:1; or a mass ratio of HfC, HfB2, and TaN of 2:1:1, etc.

[0061] If two or more ceramic powders are selected, weigh the determined ceramic powders according to the designed ceramic powder ratio and add them to the ethanol solvent. Then, use a planetary ball mill to mix them thoroughly to obtain well-dispersed multi-component ceramic powders.

[0062] The mass ratio of phenolic resin to ceramic powder is controlled between 1:0.05 and 1:0.10.

[0063] Step 3: Injecting the mixed slurry into a metal lattice porous layer and then cold isostatically pressing to densify the composite material.

[0064] Step 3-1: Place the heat pipe-type conductive metal structure obtained in Step 1 into a sealed bag, place it in the RTM device, check the inlet and airtightness, and ensure the pressure inside the vacuum bag reaches 10. -1 After holding the pressure at Pa for at least 30 minutes, the modified phenolic resin / ceramic powder mixture obtained in [Step 2] is then injected into the metal lattice porous layer 1-1 on the outside of the metal shell 2. Preferably, the injection pressure is 0.1 MPa to 0.6 MPa, and the holding time is 10 to 30 minutes. The injection process is as follows: Figure 9 As shown.

[0065] Step 3-2: After the VARTM process is completed, remove the vacuum bag and place the entire bag into a cold isostatic pressing (COP) apparatus to further promote the infiltration of the ceramic slurry into the micropores. The preferred COP pressure is 50 MPa to 60 MPa, and the holding time is 10 to 30 minutes.

[0066] Step 3-3: After cold isostatic pressing, remove the vacuum bag and place it in an oven for composite resin curing. The reference curing process is as follows: 80-90℃ for 0.5-1.0h, 120-130℃ for 1.5-2h, and 150-160℃ for 1.5-2.0h, with the temperature rise rate controlled at 0.2-1.0℃ / min; or 90℃ for 1h, 120℃ for 2h, and 160℃ for 2h, with the temperature rise rate controlled at 0.5℃ / min.

[0067] Steps 3-4: After the composite material layer consisting of ceramic powder / resin / metal lattice is cured, remove the vacuum bag, and perform surface correction or machining to obtain the ablation in-situ anti-oxidation composite heat pipe thermal protection structure.

[0068] Example

[0069] Example 1

[0070] by Figures 1 to 4 Taking the SR10, with a semi-cone angle of 7° and a height of 100mm as an example, a thermal protection structure for the nose cone is designed and fabricated to provide an ablation-in-situ anti-oxidation composite heat pipe thermal protection structure.

[0071]

Step 1

[0072] The metal lattice porous layer 1-1 has a lattice structure, with the lattice unit cell being a simple cubic (SC) + body-centered cubic (BCC) structure. The lattice constant is 0.7 mm, the diameter of the lattice connecting rod is 0.2 mm, the nominal pore size is 0.25 mm, and the nominal porosity is 43%. The capillary core structure 4 adopts the same lattice structure as the metal lattice porous layer 1-1.

[0073] The fluid transport channel 3 adopts an "Ω" shaped channel design, in which the diameter of the "Ω" shaped channel is 0.4 mm and the column height is 0.2 mm.

[0074] The total thickness of the heat pipe-type heat-resistant metal shell 2 is 2.0 mm.

[0075]

Step 2

[0076]

Step 3

[0077]

Step 4

[0078]

Step 5

Step 2

[0079]

Step 6

[0080]

Step 7

[0081] The HfC and ZrC mixed powders were poured into an ethanol solvent, maintaining a powder-to-grinding-ball-to-remaining-space volume ratio of approximately 1:1:1 in the ball mill jar. The mixture was then ball-milled using a planetary ball mill at 400 rpm for 8 hours. After removing the powder, the mixture was dried using a rotary evaporator to obtain the mixed HfC / ZrC powder.

[0082]

Step 8

[0083]

Step 9

[0084]

Step 10

[0085]

Step 11

[0086]

Step 12

[0087]

Step 13

[0088]

Step 14

[0089]

Step 15

[0090] Example 2

[0091] This embodiment designs and fabricates a rectangular cross-section pulsating-vapor cavity composite heat pipe type high-temperature conductive heat-insulating structure (without composite material structural layer), as shown in the figure. Figure 7 As shown, the pulsating-vapor chamber composite heat pipe high-temperature heat conduction and heat protection structure includes: a metal shell 2, a fluid transport channel 3, a capillary wick structure 4, and a pulsating heat pipe channel 6. The central space of the capillary wick structure 4 forms a vapor flow cavity 5. The distribution route of the pulsating heat pipe channel is designed as a continuous and tortuous path to improve the coverage of the entire metal shell 2.

[0092] The pulsed heat pipe channel 6 adopts a "D" shaped channel design, in which the diameter of the "D" shaped channel is 6mm and the column height is 2mm.

[0093] The working fluid for the pulsating heat pipe channel 6 is a NaK alloy with a mass ratio of 0.5:0.5. The working fluid is filled under vacuum conditions, with the vacuum level controlled to be better than 10. -4 Pa.

[0094] The fluid transport channel 3 adopts an "Ω" shaped channel design, wherein the diameter of the "Ω" shaped channel is 0.4 mm and the column height is 0.2 mm.

[0095] The capillary core structure 4 is a lattice structure, with the unit cell being a simple cubic (SC) + body-centered (BCC) structure. The lattice constant is 0.7 mm, the diameter of the lattice connecting rod is 0.2 mm, the nominal pore size is 0.25 mm, and the nominal porosity is 43%.

[0096] The total thickness of the heat pipe-type heat-resistant metal shell 2 is 2.0 mm.

[0097] After the metal shell 2, fluid transport channel 3, capillary wick structure 4, and pulsating heat pipe channel 6 are uniformly shaped, the main body and sealing cover structure are integrally formed using SLM additive manufacturing technology. The main body and sealing cover are formed by electron beam welding. Spherical Mo powder is used for additive manufacturing, with a powder particle size distribution range of 10–30 μm, an oxygen content not exceeding 200 ppm, and a loose packing density of 9.2 g / cm³. 3 Tap density 11.1 g / cm³ 3 .

[0098] K working fluid is selected for the steam flow chamber 5; the working fluid is filled in a vacuum environment, and the vacuum degree is controlled to be better than 10 during filling. - 4 Pa.

[0099] The experiment was conducted under the action of a 100kW induction heating heat source. The results showed that, compared with the pulse-steam cavity composite heat pipe heat conduction heat protection structure of the present invention, the full start-up time of the heat protection structure was reduced from 50s to 32s.

[0100] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0101] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. An ablation-in-situ anti-oxidation composite heat pipe thermal protection structure, characterized in that, The composite material structure layer consisting of a heat pipe-type heat-insulating structure and a ceramic powder / resin / metal lattice supported on its surface (1); The heat pipe-type heat-resistant structure includes a metal shell (2), a fluid transport channel (3), and a capillary structure (4); the capillary structure (4) is disposed on the inner surface of the metal shell (2) for the condensation, adsorption, and reflux of the working fluid vapor, and the inner side of the capillary structure (4) forms a closed vapor flow cavity (5); the fluid transport channel (3) is provided inside the metal shell (2), and the fluid transport channel (3) is connected to the capillary structure (4) to form the working fluid transport channel of the heat pipe-type heat-resistant structure; The composite material structure layer (1) composed of ceramic powder / resin / metal lattice is made of metal lattice porous layer (1-1) and ceramic powder as reinforcing materials and resin as matrix material, and serves as the protective layer of heat pipe type heat-conducting and heat-resistant structure.

2. The ablation-in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 1, characterized in that, The metal lattice porous layer (1-1) in the composite material structural layer (1) is a lattice structure with a nominal porosity of not less than 40%, a maximum pore size of not more than 0.3 mm, a minimum pore size of not less than 0.1 mm, and the unit cell of the lattice structure is any one or more of the Bravais lattice structures.

3. The ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 1, characterized in that, The ceramic powder in the composite material structural layer (1) is selected from at least one of transition metal carbides, transition metal borides, or transition metal nitrides.

4. The ablation-in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 1, characterized in that, Siloxane is added to the resin matrix in the composite material structural layer (1).

5. The ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 4, characterized in that, The siloxane is selected from at least one of methyldimethoxysiloxane, 3-aminopropyltriethoxysilane, or 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

6. The ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 1, characterized in that, The capillary core structure (4) is a lattice structure. In the lattice structure, the diameter of the connecting rod is no greater than 0.2 mm, the nominal pore size is no greater than 0.25 mm, and the nominal porosity is no less than 43%.

7. The ablation-in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 1, characterized in that, The cross-section of the fluid transport channel (3) is circular, rectangular, "D"-shaped or "Ω"-shaped, and the maximum geometric dimension of the fluid transport channel (3) is less than 0.5 mm.

8. The ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 1, characterized in that, The metal shell (2) of the heat pipe type heat-insulating structure is also provided with a pulsating heat pipe channel (6). The pulsating heat pipe channel (6) and the fluid transport channel (3) are both arranged on the inner surface of the metal shell (2) to form a venting layer. The pulsating heat pipe channel (6) is a closed pipeline connected end to end. After the metal shell (2) is heated or receives heat transfer from the composite material structure layer (1), the working fluid in the pulsating heat pipe channel (6) circulates in the closed pipeline and transports heat to the flow area.

9. The ablation-in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 8, characterized in that, The metal lattice porous layer (1-1) together with the metal shell (2), fluid transport channel (3), and capillary wick structure (4) of the heat pipe type heat-conducting and heat-insulating structure constitutes a heat pipe type heat-conducting metal structure, or the metal lattice porous layer (1-1) together with the metal shell (2), fluid transport channel (3), capillary wick structure (4), and pulsating heat pipe channel (6) of the heat pipe type heat-conducting and heat-insulating structure constitutes a heat pipe type heat-conducting metal structure, which is formed by integrated additive manufacturing.

10. The ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 9, characterized in that, The refractory metal spherical powder used in the additive manufacturing is selected from molybdenum powder, tantalum powder, tungsten powder, molybdenum-rhenium alloy powder, tantalum-tungsten alloy powder, or tungsten-rhenium alloy powder.

11. A method for preparing an ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to any one of claims 1 to 10, characterized in that, Includes the following steps: The metal structure in the composite heat pipe thermal protection structure is formed, and the heat pipe working fluid is filled. A siloxane is added to a phenolic resin, and the siloxane-modified phenolic resin is mixed with ceramic powder to obtain a modified phenolic resin / ceramic powder slurry. The heat pipe-type heat-conducting metal structure is placed in a sealed bag and placed in an RTM device. The modified phenolic resin / ceramic powder mixture is injected into the heat pipe-type heat-conducting metal structure through a vacuum-assisted resin transfer molding (VARTM) process. The metal lattice porous layer (1-1) together with the metal shell (2), fluid transport channel (3), and capillary structure (4) of the heat pipe-type heat-conducting and heat-resistant structure constitutes the heat pipe-type heat-conducting metal structure. Alternatively, the metal lattice porous layer (1-1) together with the metal shell (2), fluid transport channel (3), capillary structure (4), and pulsating heat pipe channel (6) of the heat pipe-type heat-conducting and heat-resistant structure constitutes the heat pipe-type heat-conducting metal structure. After the VARTM process is completed, the entire vacuum bag is placed into a cold isostatic pressing (CIP) machine for cold isostatic pressing treatment. After cold isostatic pressing, the composite resin is cured. After the composite material has cured, the vacuum bag is removed, and the surface is repaired or machined to obtain an ablation in-situ anti-oxidation composite heat pipe thermal protection structure.

12. The method for preparing the ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 11, characterized in that, In the step of forming the metal structure in the composite heat pipe type heat protection structure, the gas leak detection method is used to check the sealing of the formed heat pipe type heat protection metal structure. It is required that the heat pipe type heat protection structure metal shell (2) has no gas leakage under an air or nitrogen pressure of 1.5MPa. If a leak occurs, mark the leak point and repair it using an electron beam scanning surface densification method; if the cavity sealing performance meets the requirements, perform high-temperature vacuum degassing treatment on the steam flow cavity (5) enclosed by the fluid transport channel (3), the capillary core structure (4), and the pulsating heat pipe channel (6). The vacuum degassing temperature shall not be lower than 700℃, and the vacuum degree in the high-temperature furnace during the treatment shall not be lower than 10. -4 Pa.

13. The method for preparing the ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 11, characterized in that, The steps of filling the heat pipe working fluid include filling the working fluid in the steam flow cavity (5) formed by the fluid transport channel (3) and the capillary structure (4) and filling the corresponding working fluid in the pulsating heat pipe flow channel (6); wherein, the filling amount of the working fluid in the steam flow cavity (5) formed by the fluid transport channel (3) and the capillary structure (4) is determined together with the volume of the capillary structure (4) and the fluid transport channel (3).

14. The method for preparing the ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 11, characterized in that, After the step of filling the heat pipe with working fluid, the heat pipe-type conductive metal structure after filling with working fluid is further subjected to high-temperature wetting treatment. The wetting treatment temperature is not lower than 1.2 times the melting point temperature of the filling working fluid, and the high-temperature wetting time is not less than 8 hours.

15. The method for preparing the ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 11, characterized in that, After the step of filling the heat pipe with working fluid, the method further includes conducting a ground static heating environment start-up test to test the start-up performance of the heat pipe-type conductive metal structure. The heat pipe-type conductive metal structure is divided into three sections: a heating section on one side, an insulating middle section after heat treatment, and a radiative heat dissipation condensation section on the other side. The heating section is heated, and the temperatures of the heating section, the middle insulating section, and the radiative heat dissipation condensation section are monitored. After the temperature of the heating section reaches the target operating temperature and is maintained for a certain time, if the temperature difference between the middle insulating section and the radiative heat dissipation condensation section and the heating section does not exceed 10% of the temperature of the heating section, the heat pipe-type conductive metal structure is considered to have good start-up performance; otherwise, the heat pipe-type conductive metal structure is considered to have failed, and the structure preparation is restarted.

16. The method for preparing the ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 11, characterized in that, In the step of mixing the phenolic resin modified with siloxane and the ceramic powder, if two or more ceramic powders are selected, the determined ceramic powders are weighed according to the designed ceramic powder ratio and added to the ethanol solvent, and then fully mixed using a planetary ball mill to obtain well-dispersed multi-component ceramic powders. Phenolic resin modified with siloxane was mixed with multi-component ceramic powder and then ball-milled in a planetary ball mill to obtain a ceramic resin mixture slurry.

17. The method for preparing the ablation in-situ anti-oxidation composite heat pipe thermal protection structure according to claim 11, characterized in that, In the step of injecting the modified phenolic resin / ceramic powder mixture into the heat pipe-type conductive metal structure via vacuum-assisted resin transfer molding (VARTM), the injection pressure is 0.1 MPa to 0.6 MPa, and the holding time is 10 min to 30 min; and / or In the step of performing cold isostatic pressing, the cold isostatic pressing pressure is 50MPa to 60MPa, and the holding time is 10min to 30min.

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