A refractory metal skeleton reinforced hybrid resin-based ablation heat-resistant composite material and its preparation method

Abstract

This invention provides a refractory metal skeleton-reinforced hybrid resin-based ablation heat-resistant composite material and its preparation method. The method involves additive manufacturing of the refractory metal skeleton; adding siloxane to phenolic resin, and mixing the siloxane-modified phenolic resin with ceramic powder to obtain a ceramic-resin mixture slurry; placing a vacuum bag containing the refractory metal skeleton into an RTM (Resin Transfer Molding) device, and injecting the ceramic-resin mixture slurry into the refractory metal skeleton using a vacuum-assisted resin transfer molding (VARTM) process; after the VARTM process, placing the entire vacuum bag into a cold isostatic pressing (COP) device for COP treatment; after COP treatment, curing the composite resin; after curing the composite material, removing the vacuum bag, and machining the surface to obtain the refractory metal skeleton-reinforced hybrid resin-based ablation heat-resistant composite material.

Description

Technical Field

[0001] This invention belongs to the technical field of aerodynamic thermal protection systems in aerospace engineering, and specifically relates to a refractory metal skeleton reinforced hybrid resin-based ablation thermal protection composite material and its preparation method, which is suitable for thermal protection of high heat flux parts of aerospace high-speed aircraft in extreme environments. 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 effects of surface heat transfer, thus ensuring the safety of the vehicle's internal structure. This is also known as a spacecraft thermal protection system.

[0003] High-speed spacecraft such as spacecraft mostly use resin-based ablation thermal protection materials. During service, the resin in these materials undergoes pyrolysis upon heating, producing gaseous pyrolysis products that flow out from the outer surface, creating a mass ejection effect that reduces the net heat flux from aerodynamic heating. After pyrolysis, the resin in the protective material forms a carbonized residual structure. This residual structure, as a solid product of the pyrolysis reaction, is characterized by low yield and easy oxidation, resulting in a high ablation retreat rate at high temperatures. Summary of the Invention

[0004] The inventors have conducted intensive research and have provided a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material and its preparation method, which solves the problem of high ablation retreat rate of current typical resin-based ablation materials under high temperature conditions.

[0005] The technical solution provided by this invention is as follows:

[0006] In a first aspect, a method for preparing a refractory metal skeleton-reinforced hybrid resin-based ablation-resistant heat-resistant composite material includes the following steps:

[0007] Additive manufacturing of refractory metal skeletons;

[0008] A siloxane is added to a phenolic resin, and the siloxane-modified phenolic resin is mixed with ceramic powder to obtain a ceramic resin slurry.

[0009] A vacuum bag containing a refractory metal skeleton is placed into an RTM device, and a ceramic resin mixture slurry is injected into the refractory metal skeleton through a vacuum-assisted resin transfer molding (VARTM) process.

[0010] After the VARTM process is completed, the entire vacuum bag is placed into a cold isostatic pressing (CIP) machine for cold isostatic pressing treatment.

[0011] After the cold isostatic pressing process is completed, the composite resin is cured.

[0012] After the composite material has cured, the vacuum bag is removed, and the machined surface is corrected to obtain a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material.

[0013] Secondly, a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material is prepared by the preparation method of the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material described in the first aspect.

[0014] The refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material and its preparation method provided by the present invention have the following beneficial effects:

[0015] This invention provides a refractory metal skeleton-reinforced hybrid resin-based ablation-resistant heat-resistant composite material and its preparation method. It utilizes the ordered porous structure of a high-temperature refractory alloy as the skeleton, mixes carbide ceramic powder into phenolic resin to form a resin-ceramic slurry, injects the slurry into the ordered porous structure of the high-temperature refractory alloy using a resin transfer molding process, and then, after cold isostatic pressing, cures in an oven, and demolds to complete the material preparation. By incorporating carbide ceramic powder into the resin system, the material retains the mass ejection effect generated by resin pyrolysis, increases the yield of solid products after resin pyrolysis, and significantly improves the oxidation resistance of the pyrolysis products.

[0016] Furthermore, the porous framework of the refractory alloy provides excellent high-temperature support. When the modified phenolic resin is aerodynamically heated, it generates silicon-oxygen-carbon ceramic products, which, together with the added ceramic powder, form a high-temperature resistant multi-element oxide surface in situ under a high-temperature oxidizing atmosphere, thus achieving in-situ high-temperature oxidation resistance. Additionally, the pyrolysis carbonization products and ceramic powder form a composite matrix with a certain microporous structure, improving the thermal expansion compatibility with the metal framework and increasing the structural damage tolerance with ceramic oxidation products. This overcomes the problem of thermal expansion incompatibility in traditional mechanically connected anti-oxidation shells, enabling this heat-resistant composite material to significantly reduce the ablation retreat rate and improve high-temperature resistance. The refractory metal framework-reinforced hybrid resin-based ablation heat-resistant composite material can be applied to hot-end components of high-speed aerospace vehicles with conformal requirements, such as the nose cone, wings, rudders, and leading edges of ventral fins, suitable for extreme environmental thermal protection in high-heat-flux areas of high-speed aerospace vehicles. Attached Figure Description

[0017] Figure 1 This is a flowchart of a method for preparing a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to the present invention. Detailed Implementation

[0018] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0019] 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.

[0020] This invention provides a method for preparing a refractory metal skeleton-reinforced hybrid resin-based ablation-resistant heat-resistant composite material, such as... Figure 1 As shown, the process can be divided into four main steps: design and preparation of refractory metal skeleton, design and preparation of ceramic resin slurry, vacuum assisted resin transfer molding (VARTM) of resin slurry and refractory metal skeleton, cold isostatic pressing, and demolding and shaping.

[0021] I. Design and fabrication of refractory metal frameworks

[0022] Based on the refractory metal skeleton model and metal powder material, an additive manufacturing method is selected to complete the additive manufacturing of the refractory metal skeleton; after the refractory metal skeleton is cleaned and dusted, it is placed in a vacuum bag and waits for the resin slurry to be injected.

[0023] In this step, refractory metal spherical powders suitable for additive manufacturing are selected, with a particle size distribution range of 10–50 μm. Selectable materials include molybdenum powder, tantalum powder, tungsten powder, molybdenum-rhenium alloy powder, tantalum-tungsten alloy powder, or tungsten-rhenium alloy powder.

[0024] In this step, the refractory metal skeleton model is a lattice structure model. The lattice structure model is completed according to the skeleton strength and porosity requirements. The porosity of the lattice structure model is required to be no less than 40%, the maximum pore size is no greater than 0.3 mm, and the minimum pore size is no less than 0.1 mm. The unit cell of the lattice structure model can be simple cubic, face-centered cubic, body-centered cubic, etc., covering 14 Bravais lattice structures.

[0025] II. Design and Preparation of Ceramic Resin Mixture Slurry

[0026] 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 ceramic resin slurry. Preferably, the viscosity of the ceramic resin slurry is measured and adjusted using anhydrous ethanol to maintain the viscosity 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The mass ratio of phenolic resin to ceramic powder is controlled between 1:0.05 and 1:0.10.

[0031] III. Vacuum-Assisted Resin Transfer Molding (VARTM) and Cold Isostatic Pressing of Ceramic Resin Mixtures with Refractory Metal Skeletons

[0032] The vacuum bag containing the refractory metal skeleton is inserted into the RTM equipment. The inlet and airtightness are checked, and the pressure inside the vacuum bag reaches 10. -1 After holding the pressure at 0.1 MPa for at least 30 minutes, the modified ceramic resin mixture is then injected into the refractory metal skeleton. The preferred injection pressure is 0.1 MPa to 0.6 MPa, and the holding time is 10 to 30 minutes. If the pressure is insufficient or the holding time is not long enough, material defects such as voids may occur.

[0033] After the VARTM process is completed, the vacuum bag is removed and the entire assembly is placed in a cold isostatic pressing (CIP) apparatus to further promote the infiltration of the ceramic resin mixture into the micropores of the refractory metal framework. The preferred CIP pressure is 50 MPa to 60 MPa, and the holding time is 10 to 30 minutes. Insufficient pressure or holding time can easily lead to material defects such as voids.

[0034] 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: keep at 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 keep at 90℃ for 1h, 120℃ for 2h, and 160℃ for 2h, with the temperature rise rate controlled at 0.5℃ / min.

[0035] IV. Demolding and Shaping

[0036] After the composite material has cured, the vacuum bag is removed, and the surface is machined to obtain a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material.

[0037] Example

[0038] Example 1

[0039] Using Ta-10W refractory alloy as the skeleton and HfC and ZrC mixed ceramic powder doped with siloxane-modified boron phenolic resin as the matrix, a Ta-10W refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material is formed as an example to introduce the application and implementation method of the present invention.

[0040] I. Design and fabrication of refractory metal frameworks

[0041] Select Ta-10W refractory metal spherical powder with a particle size distribution range of 10-50 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 Hall flow rate (50g) 6.8s.

[0042] Based on the requirements for skeleton strength and porosity, the lattice structure model was completed. The unit cell of the lattice structure is a simple cubic (SC) + body-centered cubic (BCC) structure with a lattice constant of 0.7 mm, a lattice connecting rod diameter of 0.2 mm, a nominal pore size of 0.25 mm, and a nominal porosity of 43%.

[0043] Based on the lattice structure model and the Ta-10W refractory alloy, selective laser melting (SLM) was used to form the refractory metal skeleton. After dust removal and cleaning, the formed refractory metal skeleton was placed in a vacuum bag to await resin slurry injection.

[0044] II. Design and Preparation of Ceramic Resin Mixture Slurry

[0045] The ceramic powder selected is a mixture of HfC and ZrC powders with a molar ratio of 3:1, and the particle size of both HfC and ZrC powders is below 10μm.

[0046] 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 300–400 rpm for 8 hours. After removing the powder, it was dried using a rotary evaporator to obtain the mixed HfC / ZrC powder.

[0047] Barium phenolic resin with a solid phenolic content of not less than 65% was selected, and 3-aminopropyltriethoxysilane organosilicon was added to the phenolic resin. The mass ratio of barium phenolic resin to siloxane was controlled at 20:1 to obtain modified phenolic resin.

[0048] The phenolic resin modified with siloxane was mixed with the ceramic HfC / ZrC powder that had been dispersed by ball milling. The mass ratio of the modified phenolic resin to the HfC / ZrC powder was 17:1. After secondary ball milling in a planetary ball mill, a slurry of the modified resin and ceramic powder was obtained.

[0049] The viscosity of the resin slurry was measured and adjusted using anhydrous ethanol to maintain the viscosity at 1.5 Pa·s at room temperature (25°C). After the viscosity was adjusted, the slurry was loaded into the resin storage tank of the RTM equipment.

[0050] III. Vacuum-Assisted Resin Transfer Molding (VARTM) and Cold Isostatic Pressing of Ceramic Resin Mixtures with Refractory Metal Skeletons

[0051] The sealed bag containing the Ta-10W refractory metal skeleton is placed into the RTM equipment. The inlet and airtightness are checked, and the pressure inside the vacuum bag reaches 10. -1 After applying pressure at 0.6 MPa, maintain vacuum for 30 minutes, then inject the slurry of modified ceramic resin and ceramic powder from the storage tank into the refractory metal framework.

[0052] After the VARTM injection process is completed, the vacuum bag is removed and the whole thing is placed in a cold isostatic pressing equipment to further promote the infiltration of ceramic slurry into the micropores. The cold isostatic pressing pressure is 50MPa and the pressure is held for 15 minutes.

[0053] After cold isostatic pressing, the vacuum bag is removed and placed in an oven for composite material curing. The curing process is as follows: 90℃ for 1 hour, 120℃ for 2 hours, and 160℃ for 2 hours, with the temperature rise rate controlled at 0.5℃ / min.

[0054] IV. Demolding and Shaping

[0055] After the composite material has cured, the vacuum bag is removed, and the surface is machined to obtain the Ta-10W refractory metal skeleton reinforced mixed HfC / ZrC phenolic resin-based ablation heat-resistant composite material.

[0056] A Ta-10W refractory metal skeleton-reinforced hybrid HfC / ZrC phenolic resin-based ablation heat-resistant composite material was obtained at a heat flux density of 3MW / m². 2 Under the conditions of an electric arc wind tunnel test with an enthalpy of 10 MJ / kg, the linear ablation rate of the material at high temperature is approximately 10. -3 μm / s, the linear ablation rate of the comparative carbon phenolic composite material is approximately 10 μm / s. -2 μm / s, the linear ablation rate of the material at high temperature is significantly reduced.

[0057] 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.

[0058] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for preparing a refractory metal skeleton-reinforced hybrid resin-based ablation-resistant heat-resistant composite material, characterized in that, Includes the following steps: Additive manufacturing of refractory metal skeletons; A siloxane is added to a phenolic resin, and the siloxane-modified phenolic resin is mixed with ceramic powder to obtain a ceramic resin slurry; the siloxane is selected from at least one of methyldimethoxysiloxane, 3-aminopropyltriethoxysilane, or 3-(2,3-epoxypropoxy)propyltrimethoxysilane; the ceramic powder is selected from at least one of transition metal carbides, transition metal borides, or transition metal nitrides. A vacuum bag containing a refractory metal skeleton is placed into an RTM device, and a ceramic resin mixture slurry is injected into the refractory metal skeleton through a vacuum-assisted resin transfer molding (VARTM) process. 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 the cold isostatic pressing process is completed, the composite resin is cured. After the composite material has cured, the vacuum bag is removed, and the machined surface is corrected to obtain a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material.

2. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of additive manufacturing of the refractory metal skeleton, the refractory metal skeleton is a lattice structure with a 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 method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of additive manufacturing of the refractory metal skeleton, 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.

4. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of adding siloxane to phenolic resin, the mass ratio of phenolic resin to siloxane is controlled at 20:1 to 15:

1.

5. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of adding siloxane to phenolic resin, the solid phenolic content of the phenolic resin is not less than 60%.

6. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of mixing the phenolic resin modified with siloxane with ceramic powder to obtain a ceramic resin slurry, the ceramic powder has a particle size of less than 10 μm.

7. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of mixing the phenolic resin modified with siloxane and ceramic powder to obtain a ceramic resin slurry, 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 a well-dispersed multi-component ceramic powder. 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.

8. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, In the step of injecting the ceramic resin mixture into the refractory metal skeleton through the vacuum-assisted resin transfer molding (VARTM) process, the injection pressure is 0.1 MPa to 0.6 MPa, and the holding time is 10 min to 30 min.

9. The method for preparing the refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material according to claim 1, characterized in that, 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.

10. A refractory metal skeleton reinforced mixed resin-based ablation-resistant heat-resistant composite material, characterized in that, The composite material is prepared by the method described in any one of claims 1 to 9, which is a refractory metal skeleton reinforced mixed resin-based ablation heat-resistant composite material.

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