A hypersonic vehicle hot end component and a preparation method and application thereof

Abstract

The application belongs to the technical field of ceramic matrix composite, and discloses a hypersonic aircraft hot end component and a preparation method and application thereof, and the method comprises the following steps: (1) printing a green body of the hypersonic aircraft hot end component to be prepared by taking ceramic-metal silicon-binder composite powder as raw materials; wherein the raw materials of the ceramic-metal silicon-binder composite powder comprise ceramic powder, metal silicon and organic binder; (2) after the green body is solidified, pressureless sintering is first carried out under the condition of nitrogen, then carbon precursor is infiltrated and reaction sintering is carried out, and then the hypersonic aircraft hot end component is obtained. By means of nitriding, uniformly distributed silicon nitride bonding phases and pyrolytic carbon are generated in the body, reaction sintering silicon infiltration converts the pyrolytic carbon into silicon carbide, the obtained material contains in-situ nitrided silicon nitride and secondary silicon carbide (beta-SiC) generated by reaction sintering silicon infiltration as bonding phases, and has more excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the technical field of ceramic matrix composite materials, and more specifically, relates to a hot-end component of a hypersonic vehicle, its preparation method and application. Background Technology

[0002] Silicon carbide (SiC) and its composites possess comprehensive qualities such as high temperature resistance, oxidation resistance, lightweight, and high wear resistance, making them important materials for hot-end components in the aerospace field and leading to their widespread application. However, the high hardness and brittleness of silicon carbide ceramic materials result in difficult, costly, and time-consuming blank processing. Moreover, limitations in equipment and forming processes have hindered the preparation of large-size, lightweight, and structurally complex high-quality silicon carbide composites using traditional methods. Common problems include complex forming processes, high costs, long manufacturing cycles, high consumption, and difficulty in quality control, which have become technical bottlenecks restricting their engineering applications.

[0003] In recent years, with the rapid development of additive manufacturing technology, it has been applied to the moldless forming of silicon carbide ceramic materials. Combined with post-processing, it has initially realized the rapid manufacturing of silicon carbide ceramic parts with complex structures. Unlike traditional preparation methods that involve molding / cold isostatic pressing, green body machining, and sintering, additive manufacturing involves discretizing the digital three-dimensional model of the blank into several two-dimensional planes. Using precision nozzles or lasers, based on layer information and driven by digital scanning control, silicon carbide raw material powder or slurry is stacked layer by layer through continuous physical layers to generate a solid blank. In recent years, there have been reports on the use of powder bed 3D printing technology to form complex structure ceramic parts. For example, patent CN107043259A discloses a method for forming dense silicon carbide parts by laser selective sintering of silicon carbide powder prepared by spray granulation, followed by pyrolysis and silicon infiltration sintering. The dense silicon carbide parts prepared by this technology contain a certain amount of free silicon. Free silicon is prone to reaction with oxygen at high temperatures (above 1400℃), which cannot meet the requirements of the hot-end components of reentry hypersonic vehicles for the material's resistance to oxidation and ablation. For example, patent CN200510020015.5 discloses a method for preparing silicon carbide ceramics by laser sintering rapid prototyping. It uses laser sintering technology to form silicon carbide powder, then melt-infiltrates metallic silicon and treats it with alkaline solution to obtain silicon carbide ceramics with complex shapes. However, the ceramic material prepared by this method lacks a binding phase, and the final product has low mechanical strength and poor performance. Considering that the hot-end components of hypersonic vehicles need to withstand the erosion of airflow with speeds up to Mach 10, this process is not suitable. Similarly, patent WO2018188436A1 discloses a method for preparing carbon fiber / phenolic resin composite powder based on solvent evaporation, 3D printing, first densification treatment followed by melt-infiltrating silicon, then high-temperature removal of Si and a second densification treatment to obtain the final C / C-SiC part. The first densification process requires sequential impregnation, curing, and carbonization, while the second densification process uses chemical vapor infiltration. Therefore, the process steps are complicated and the cycle is lengthy, making it unsuitable for rapid industrial production. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a hypersonic vehicle hot-end component, its preparation method, and its application. It utilizes nitriding to generate a uniformly distributed silicon nitride bonding phase and pyrolytic carbon within the blank, followed by reactive sintering and silicon infiltration to convert the pyrolytic carbon into silicon carbide. This results in a material containing silicon nitride generated by in-situ nitriding and secondary silicon carbide (β-SiC) generated by reactive sintering and silicon infiltration as bonding phases. Compared to materials using only Si3N4 or β-SiC as bonding phases, this material exhibits superior mechanical properties.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a hot-end component of a hypersonic vehicle is provided, the method comprising the following steps:

[0006] (1) A green blank of a hypersonic vehicle hot end component is obtained by printing ceramic-metal silicon-binder composite powder as raw material; wherein, the raw material of the ceramic-metal silicon-binder composite powder includes ceramic powder, metal silicon and organic binder;

[0007] (2) After the green blank is solidified, it is first sintered under nitrogen without pressure, then impregnated with carbon precursor and subjected to reaction sintering to obtain the hot end component of the hypersonic vehicle.

[0008] Furthermore, after reaction sintering, the free silicon in the obtained product is first removed, and then SiC fiber cloth is adhered to the surface to obtain the hypersonic vehicle hot end component.

[0009] Furthermore, methods for removing free silicon include alkaline treatment, acid etching, and high-temperature silicon removal.

[0010] Furthermore, using ceramic powder, metallic silicon, and organic binder as raw materials, the ceramic powder and organic binder are first mixed once, and then metallic silicon is added and mixed evenly a second time to obtain a ceramic-metallic silicon-binder composite powder.

[0011] Furthermore, the method of mixing ceramic powder and organic binder in one step is called coating method, and the method of mixing them in two steps after adding metallic silicon is called mechanical mixing method.

[0012] Furthermore, the ceramic powder includes one or more of silicon carbide, silicon nitride, and boron carbide, with an average sphericity greater than 1.3; the organic binder includes one or more of epoxy resin, phenolic resin, and polyimide.

[0013] Furthermore, the carbon precursor includes one or both of phenolic resin and bitumen.

[0014] Furthermore, the pressureless sintering temperature is greater than or equal to 1400℃, and the reaction sintering temperature is greater than or equal to 1500℃.

[0015] The present invention also provides a hot-end component for a hypersonic vehicle, which is prepared by the method described above for preparing a hot-end component for a hypersonic vehicle.

[0016] The present invention also provides an aircraft, the aircraft including a body and a hot-end component connected to the body, the hot-end component being the hypersonic aircraft hot-end component as described above.

[0017] In summary, compared with the prior art, the hypersonic vehicle hot-end component, its preparation method, and its application provided by the present invention have the following beneficial effects:

[0018] 1. This invention utilizes nitriding to generate a uniformly distributed silicon nitride bonding phase and pyrolytic carbon inside the green body, and reaction sintering siliconizing to convert the pyrolytic carbon into silicon carbide. The resulting material contains silicon nitride generated by in-situ nitriding and secondary silicon carbide (β-SiC) generated by reaction sintering siliconizing as bonding phases, which has superior mechanical properties compared to materials with only Si3N4 or β-SiC as bonding phases.

[0019] 2. By removing free silicon and introducing a certain amount of pores inside the material, the ablation problem of the material under high-temperature oxidation conditions is completely solved. Furthermore, the presence of micropores can absorb thermal stress and prevent excessive stress from damaging the material.

[0020] 3. The composite powder preparation process using a combination of coating and mechanical mixing methods ensures good flowability of the composite powder while ensuring that the binder only coats the surface of the ceramic powder. This allows the metallic silicon to fully react with nitrogen during the subsequent pressureless sintering process. The in-situ generated silicon nitride and the secondary silicon carbide generated by reaction sintering together form the binding phase, ensuring that the material can maintain good mechanical properties even after the removal of free silicon. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for preparing a hot-end component of a hypersonic vehicle provided by the present invention;

[0022] Figure 2 This is a schematic diagram of the internal phase distribution of the hot-end component of a hypersonic vehicle based on 3D printing, provided by the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Please see Figure 1 and Figure 2 This invention provides a method for preparing a hot-end component of a hypersonic vehicle, the method mainly comprising the following steps:

[0025] Step 1: Using ceramic powder, metallic silicon, and organic binder as raw materials, the ceramic powder and organic binder are first mixed once, and then metallic silicon is added and mixed evenly a second time to obtain ceramic-metallic silicon-binder composite powder.

[0026] The ceramic powder comprises one or more of silicon carbide, silicon nitride, and boron carbide, with an average sphericity greater than 1.3. The organic binder comprises one or more of epoxy resin, phenolic resin, and polyimide, preferably phenolic resin.

[0027] The loose relative density of the ceramic-silicon-binder composite powder is greater than 0.6, and the maximum particle size does not exceed 250 μm. The method for primary mixing of the ceramic powder and organic binder is a coating method, including thermal coating and solution coating. The method for secondary mixing with added silicon is a mechanical mixing method.

[0028] Step 2: Design a 3D model of the hot-end component of the hypersonic vehicle using CAD software, and 3D print a green body of the hypersonic vehicle hot-end component with the same structure as the 3D model using ceramic-metal silicon-binder composite powder.

[0029] The 3D printing methods used include, but are not limited to, powder bed-based 3D printing technologies such as selective laser sintering, electron beam forming, and binder jetting.

[0030] Step 3: After the green body is solidified, it is first sintered under nitrogen without pressure, and then impregnated with a carbide precursor and subjected to reaction sintering.

[0031] The pressureless sintering temperature is greater than or equal to 1400℃, and the carbon precursor includes one or both of phenolic resin and pitch. The reaction sintering temperature is greater than or equal to 1500℃.

[0032] Step four: After the reaction sintering densification of the semi-finished product, free silicon is first removed at high temperature, then SiC fiber cloth is attached to the surface, and finally the surface is corrected to obtain the hypersonic vehicle hot end component.

[0033] Methods for removing free silicon include alkaline treatment, acid etching, and high-temperature silicon removal.

[0034] This embodiment introduces pores by removing free silicon from the material, which acts as a buffer to alleviate stress concentration and prevent crack propagation. This not only solves the problem of conventional reaction-sintered silicon carbide being unresistant to oxidation and ablation, but also greatly improves the material's resistance to thermal shock.

[0035] The present invention also provides a hot-end component for a hypersonic vehicle, which is prepared by the method described above for preparing a hot-end component for a hypersonic vehicle.

[0036] The present invention also provides an aircraft, the aircraft including a body and a hot-end component connected to the body, the hot-end component being the hypersonic aircraft hot-end component as described above.

[0037] The present invention will be further described in detail below with reference to several embodiments.

[0038] Example 1

[0039] The method for preparing the hot-end component of a hypersonic vehicle provided in Embodiment 1 of the present invention mainly includes the following steps:

[0040] (a) Using silicon carbide powder, metallic silicon and epoxy resin as raw materials, the silicon carbide powder and epoxy resin are first mixed once, and then metallic silicon is added and mixed evenly to obtain silicon carbide-metallic silicon-epoxy resin composite powder.

[0041] (b) A three-dimensional model of the hot-end component of the hypersonic vehicle is constructed using CAD software. The silicon carbide-metallic silicon-epoxy resin composite powder prepared in the previous step is used as raw material for laser selective sintering 3D printing to obtain a green blank of the hot-end component of the hypersonic vehicle with the same structure as the three-dimensional model.

[0042] (c) After the hot end components of the hypersonic vehicle are cured, they are first sintered under nitrogen at 1400℃ for 3 hours without pressure, and then impregnated with asphalt and subjected to reaction sintering.

[0043] (d) The sample after reaction sintering densification is treated with alkaline solution to remove free silicon, and SiC fiber cloth is adhered to the surface to obtain the hot end component of the hypersonic vehicle based on 3D printing.

[0044] Example 2

[0045] The method for preparing the hot-end component of a hypersonic vehicle provided in Embodiment 2 of the present invention mainly includes the following steps:

[0046] (a) Using silicon carbide, boron nitride, metallic silicon, and polyimide as raw materials, silicon carbide, boron nitride, and polyimide are first mixed once, and then metallic silicon is added and mixed evenly to obtain silicon carbide-boron nitride-metallic silicon-polyimide composite powder.

[0047] (b) A three-dimensional model of the hot end component of the hypersonic vehicle is constructed using CAD software. The silicon carbide-boron nitride-metal silicon-polyimide composite powder prepared in the previous step is used as raw material for electron beam forming 3D printing to obtain a green blank of the hot end component of the hypersonic vehicle with the same structure as the three-dimensional model.

[0048] (c) After the hot end components of the hypersonic vehicle are cured, they are first sintered under nitrogen at 1500°C for 3 hours without pressure, and then impregnated with phenolic resin and subjected to reaction sintering.

[0049] (d) The sample after reaction sintering densification is subjected to high-temperature Si removal method to remove free silicon, and SiC fiber cloth is adhered to the surface to obtain the hot end component of the hypersonic vehicle based on 3D printing.

[0050] Example 3

[0051] The method for preparing the hot-end component of a hypersonic vehicle provided in Embodiment 3 of the present invention mainly includes the following steps:

[0052] (a) Using silicon nitride, boron nitride, metallic silicon, and phenolic resin as raw materials, silicon nitride, boron nitride, and phenolic resin are first mixed once, and then metallic silicon is added and mixed evenly to obtain silicon nitride-boron nitride-metallic silicon-phenolic resin composite powder.

[0053] (b) A three-dimensional model of the hot-end component of the hypersonic vehicle is constructed using CAD software. The silicon nitride-boron nitride-metal silicon-phenolic resin composite powder prepared in the previous step is used as raw material for binder jet 3D printing to obtain a green blank of the hot-end component of the hypersonic vehicle with the same structure as the three-dimensional model.

[0054] (c) After the hot end components of the hypersonic vehicle are cured, they are first sintered under nitrogen at 1600°C for 3 hours without pressure, and then impregnated with a mixture of phenolic resin and asphalt and subjected to reaction sintering.

[0055] (d) After the sample is densified by reaction sintering, free silicon is removed by acid etching, and then SiC fiber cloth is adhered to the surface to obtain the hot end component of the hypersonic vehicle based on 3D printing.

[0056] To better demonstrate that the hypersonic vehicle hot-end component prepared in this embodiment has good mechanical properties, performance tests and comparisons were conducted on the hypersonic vehicle hot-end component prepared in this embodiment and the hypersonic vehicle hot-end component prepared by existing methods, as detailed in Table 1.

[0057] Table 1 Performance Test Data

[0058]

[0059] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of making a hypersonic vehicle hot end component, the method comprising: The method comprises the following steps: (1) printing a green body of a hypersonic aircraft hot end component to be prepared by using a ceramic-metal silicon-binder composite powder as raw material; wherein the raw material of the ceramic-metal silicon-binder composite powder comprises ceramic powder, metal silicon and organic binder; the ceramic powder comprises one or more than two of silicon carbide, silicon nitride and boron carbide; (2) after the green body is solidified, it is first sintered under pressureless condition in a nitrogen atmosphere, then impregnated with a carbon precursor and subjected to reaction sintering, thereby obtaining the hypersonic aircraft hot end component, and the obtained material contains in-situ nitrided silicon nitride and reaction sintering silicon-impregnated secondary silicon carbide as a binding phase; after reaction sintering, the obtained product is first subjected to free silicon removal, and then a SiC fiber cloth is adhered to the surface to obtain the hypersonic aircraft hot end component; ceramic powder, metal silicon and organic binder are used as raw material, the ceramic powder is first mixed with the organic binder, then the metal silicon is added for secondary mixing to obtain the ceramic-metal silicon-binder composite powder; the method for first mixing the ceramic powder with the organic binder is a coating method, and the method for secondary mixing after adding the metal silicon is a mechanical mixing method.

2. The method of making a hypersonic vehicle hot section component of claim 1, wherein: The method for removing free silicon comprises lye treatment, acid etching and high-temperature Si removal.

3. The method of making a hypersonic vehicle hot section component of claim 1, wherein: The average sphericity of the ceramic powder is greater than 1.3; the organic binder comprises one or more than two of epoxy resin, phenolic resin and polyimide.

4. The method of making a hypersonic vehicle hot section component of claim 1, wherein: The carbon precursor comprises one or more than two of phenolic resin and pitch.

5. The method of manufacturing a hypersonic vehicle hot section component according to any one of claims 1 to 4, wherein: The temperature of pressureless sintering is greater than or equal to 1400℃, and the temperature of reaction sintering is greater than or equal to 1500℃.

6. A hypersonic vehicle hot end component, characterized by: The hot end component is prepared by using the preparation method of the hypersonic aircraft hot end component according to any one of claims 1-5.

7. An aircraft characterised by: The aircraft comprises a body and a hot end component connected to the body, and the hot end component is the hypersonic aircraft hot end component according to claim 6.

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