High-temperature heat dissipation ceramic composition for aerospace sandwich panels and its preparation method

Abstract

This invention relates to a ceramic slurry composition and its preparation method, and more specifically, to a high-temperature heat-dissipating ceramic composition for aerospace sandwich panels and its preparation method. The slurry formed by this ceramic composition exhibits excellent thermal conductivity and thermal diffusion, effectively preventing cracks and porosity in aerospace sandwich panels caused by ultra-high temperatures.

Description

Technical Field

[0001] This invention relates to a ceramic slurry composition and its preparation method, and more specifically, to a high-temperature heat dissipation ceramic composition for aerospace sandwich panels and its preparation method. Background Technology

[0002] Silicon carbide (SiC) ceramics exhibit a range of superior properties, including high flexural strength, good oxidation and corrosion resistance, excellent wear resistance, and high-temperature resistance. These properties make SiC the preferred material for thermal protection structures in aerospace vehicles. SiC materials can withstand high heat flux environments at temperatures up to 1000°C without cracking or delamination. This is due to the high thermal conductivity of the SiC matrix at ultra-high temperatures, making SiC composites ideal for advanced thermal protection systems in hypersonic aircraft. However, research on laminating solid carbon / carbon structures has focused on improving the material's inherent heat transfer properties, but these materials are brittle and difficult to process. Three-dimensional braided sandwich structures of SiC composite ceramics increase volume and weight, thus reducing overall heat dissipation efficiency.

[0003] To address the aforementioned issues, using carbon fiber reinforced SiC lattice sandwich composites to partially or completely replace traditional aircraft materials can significantly reduce aircraft weight while enhancing their high-temperature resistance and oxidation resistance (Polymers and Polymer Composites. 2022; 30. doi: 10.1177 / 09673911221098729 Additive manufacturing of carbon fiber reinforced SiC ceramic panels combines the advantages of efficient heat transfer and dissipation, providing thermal conductivity far superior to traditional ceramic matrix composites. It also achieves a high heat dissipation surface area and a lightweight structure, thereby improving the heat dissipation efficiency and reliability of thermally protected ceramic panels. However, mechanical and environmentally induced cracks and porosity are almost inevitable at high temperatures; furthermore, although the thermal conductivity of carbon fiber reinforced SiC composite ceramics is improved, it still does not reach the thermal conductivity of metallic composites. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature heat dissipation ceramic composition for aerospace sandwich panels to solve the above-mentioned problems in the prior art. The slurry formed by the ceramic composition of this invention should have excellent thermal conductivity and thermal diffusion, so that aerospace sandwich panels can effectively prevent cracks and pores caused by ultra-high temperature.

[0005] According to a first aspect of the present invention, the present invention provides a high-temperature heat dissipation ceramic composition for aerospace sandwich panels, comprising diamond and SiC.

[0006] Preferably, the SiC is a mixture of 200-500nm SiC and 600-2000nm SiC.

[0007] Preferably, by weight percentage:

[0008]

[0009] The sum of all components in the composition is 100%.

[0010] Preferably, the weight ratio of 200-500nm SiC to 600-2000nm SiC is 4:5.

[0011] Preferably, by mass percentage: 40% SiC of 200-500nm, 50% SiC of 600-2000nm, 6% silicon-coated diamond, and 4% γ-aminopropyltriethoxysilane.

[0012] In the above composition, silicon carbide serves as the ceramic powder matrix, which provides a shaped framework after sintering the slurry; γ-aminopropyltriethoxysilane is used to couple the organic polymer resin and the inorganic ceramic filler; and diamond further enhances the thermal conductivity and heat dissipation efficiency of the slurry. The combination of these components and the aforementioned percentage ranges of each component were determined through extensive experimentation. These combinations and percentage ranges enable the coating formed by the coating composition of the present invention to possess the aforementioned highly efficient heat dissipation advantages.

[0013] According to a second aspect of the present invention, the present invention provides a method for preparing a high-temperature heat-dissipating ceramic composition for aerospace sandwich panels, comprising the following steps:

[0014] (a) Drying SiC, preferably drying SiC at 110°C for 24 hours;

[0015] (b) Prepare a mixed solution of anhydrous ethanol and deionized water, preferably a mixed solution of an appropriate amount of anhydrous ethanol and deionized water with a volume ratio of 1:1.5.

[0016] (c) Add SiC powder to the mixture solution and then ultrasonically stir to disperse it evenly; preferably, add SiC powder to the mixture solution and then ultrasonically stir for 30 minutes to ensure uniform dispersion of the powder.

[0017] (d) Add γ-aminopropyltriethoxysilane to the dispersion solution.

[0018] (e) The solution is heated and stirred; preferably, the solution is magnetically stirred in an oil bath at 50°C for 4 hours.

[0019] (f) Centrifuge the suspension to achieve solid-liquid separation, wash the separated solid, dry it, grind it, sieve it, and then dry it for later use; preferably, centrifuge the suspension to achieve solid-liquid separation, wash the separated solid, dry it in a hot air drying oven at 100°C, grind it, sieve it through a 200-mesh sieve, and then dry it for later use.

[0020] (g) Add the powder and diamond to the photosensitive resin as described in (f) to form a slurry (such as longitudinal cubic ANYCUBIC photosensitive resin) and stir.

[0021] Preferably, the volume fraction of powder in the ceramic slurry is 45% to 60%.

[0022] Preferably, the optimal mass ratio of 200-500nm SiC to 600-2000nm SiC is 4:5.

[0023] The ceramic composition of the present invention can be formed using conventional digital light processing, and the slurry exhibits excellent and efficient heat dissipation after sintering. Attached Figure Description

[0024] Figure 1 The diagram shows the thermal conductivity and thermal diffusivity of the ceramic in the example.

[0025] Figure 2 The image shows the microstructure of the microstructure using SEM. Detailed Implementation

[0026] In the following embodiments, the heat transfer characteristics of the structure are represented by thermal conductivity (W / m·K), where a higher value indicates faster heat transfer; and by thermal diffusivity (mm²). 2 / s) represents the heat dissipation characteristics of the structure. The higher this value, the better the heat dissipation.

[0027] Aerospace sandwich panels are composite structures consisting of two layers of high-strength thin panels and a lightweight core material in between. The ceramic matrix composite material of these panels possesses a range of excellent properties, including high flexural strength, good oxidation resistance, good corrosion resistance, good wear resistance, and high-temperature resistance, making them the preferred material for thermal protection structures in aerospace vehicles. Two types of sandwich panels are available: trapezoidal compact structure (TC) sandwich panels and standard hexagonal honeycomb (HC) sandwich panels, with pore sizes ranging from 1 to 4 mm. They are primarily used in nozzles, combustion chambers, turbine stators, and other hot sections of aircraft engines such as the M882, F100PW229, CFM565B, F135, GEnx, and LEAPX.

[0028] Example 1

[0029] At room temperature and pressure, SiC was dried at 110°C for 24 hours according to the mass percentages in Table 1 below to prepare a mixed solution of anhydrous ethanol and deionized water with a volume ratio of 1:1.5. SiC powder was added to the mixed solution, and then ultrasonically stirred for 30 minutes to ensure uniform dispersion of the powder. γ-aminopropyltriethoxysilane was then added, and the solution was magnetically stirred in a 50°C oil bath for 4 hours. The suspension was centrifuged to achieve solid-liquid separation. The separated solid was washed, dried in a 100°C hot air drying oven, ground, sieved through a 200-mesh sieve, and then dried for later use. Then, silicon-coated diamond powder and SiC powder were mixed with commercial resin (ANYCUBIC photosensitive resin) according to the mass percentages in Table 1 to form a slurry and stirred for half an hour. The volume fraction of the material powders (i.e., SiC and silicon-coated diamond) in the formed slurry was 46 vol.%.

[0030] The obtained slurry was 3D printed using a photopolymerization molding machine (ADT-3D-ZP-Printer-Pro-67-35). A digital light processing (DLP) projector projected the sliced ​​model layer by layer onto the slurry composition. Each layer of the projected image solidified into a thin layer in a very thin area of ​​the resin layer. The molding stage moved to the next layer, and the process was repeated until the entire print was completed. After printing, the sample was immersed in an ultrasonic cleaner filled with anhydrous ethanol for 2 minutes. The green body was then thermally decomposed in an argon atmosphere at 800°C at a heating and cooling rate of 1°C / min for 2 hours. Organic matter was then removed to obtain an inorganic porous intermediate composed of decomposed carbon and diamond. Subsequently, a reactive melt infiltration process was used to densify the intermediate, in which molten silicon infiltrated into the intermediate and reacted with carbon and diamond to gradually form in-situ generated SiC, filling the pores. The reactive melt infiltration process was carried out in a vacuum environment with a vacuum level of 10. - 3 Pa. The temperature was increased at a rate of 10 °C / min until it reached 1500 °C, and then held for 0.5 hours. Subsequently, the temperature was decreased to 900 °C at a rate of 5 °C / min. Finally, the material was cooled to room temperature to prepare the diamond / SiC composite material.

[0031] The thermal conductivity and thermal diffusivity of the diamond / SiC composite ceramic material were tested from 400℃ to 1000℃ after sintering, and the test results are listed in Table 1.

[0032] Comparative Example 1

[0033] At room temperature and pressure, SiC was dried at 110°C for 24 hours according to the mass percentages in Table 1 below to prepare a mixed solution of anhydrous ethanol and deionized water with a volume ratio of 1:1.5. SiC powder was added to the mixed solution, and then ultrasonically stirred for 30 minutes to ensure uniform dispersion of the powder. γ-aminopropyltriethoxysilane was then added, and the solution was magnetically stirred in a 50°C oil bath for 4 hours. The suspension was centrifuged to achieve solid-liquid separation. The separated solid was washed, dried in a 100°C hot air drying oven, ground, sieved through a 200-mesh sieve, and then dried for later use. Carbon fiber and SiC powder were then mixed with commercial resin (ANYCUBIC photosensitive resin) according to the mass percentages in Table 1 to form a slurry, which was stirred for half an hour. The volume fraction of the material powders (silicon carbide and carbon fiber) in the formed slurry was 46 vol.%. After sintering, the thermal conductivity and thermal diffusivity of the ceramic from 400°C to 1000°C were tested, and the test results are listed in Table 1.

[0034] Comparative Example 2

[0035] At room temperature and pressure, SiC was dried at 110°C for 24 hours according to the mass percentages in Table 1 below to prepare a mixed solution of anhydrous ethanol and deionized water with a volume ratio of 1:1.5. SiC powder was added to the mixture solution, and then ultrasonically stirred for 30 minutes to ensure uniform dispersion. γ-aminopropyltriethoxysilane was then added, and the solution was magnetically stirred in a 50°C oil bath for 4 hours. The suspension was centrifuged to achieve solid-liquid separation. The separated solid was washed, dried in a 100°C hot air drying oven, ground, sieved through a 200-mesh sieve, and then dried for future use. SiC powder was then added to commercial resin (ANYCUBIC photosensitive resin) according to the mass percentages in Table 1 to form a slurry, which was stirred for half an hour. The volume fraction of the SiC ceramic slurry was 46 vol.%. After sintering, the thermal conductivity and thermal diffusivity of the ceramic from 400°C to 1000°C were tested, and the test results are listed in Table 1.

[0036] The test data of thermal conductivity and thermal diffusivity of the sintered ceramic samples of each embodiment and comparative example in Table 1 below show that, in terms of both individual performance and overall performance, the ceramic slurry composition of the present invention is significantly superior to the slurry composition of the comparative example.

[0037] Table 1

[0038]

[0039] Figure 1The results show that the thermal diffusivity of the three materials gradually decreases with increasing temperature, especially that of SiC at high temperatures. Therefore, the thermal conductivity of silicon carbide composites decreases at high temperatures, even though the thermal conductivity itself does not change significantly. The main reason is that as the test temperature increases, the phonon density increases, leading to more intense collisions. In the amorphous phase, the mean free path of phonons is shorter and significantly reduced, thus decreasing the diffusivity. Reducing the thermal diffusivity at high temperatures allows SiC composites to provide better insulation performance, preventing external heat from entering the internal region or transferring internal heat to the external environment. Therefore, reducing the thermal diffusivity can improve the thermal insulation effect and protect the stability of hypersonic flight systems.

[0040] Figure 2 The results show that the diamond / SiC structure has a smooth surface and good structure. Figure 2 a). The surface of carbon fiber / SiC is relatively smooth, but contains many pits, resulting in a relatively rough bond structure. Figure 2 b). Compared to the previous two materials, SiC exhibits relatively uneven formation, with a distinct layered structure observed. Figure 2 c). This layered structure, consistent with a molding precision of approximately 50 μm, may result in weaker adhesive strength. The layered structure is likely the primary cause of slower initial thermal conduction, particularly noticeable in the 90% infill Schoen Gyroid structure.

[0041] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high-temperature heat dissipation ceramic composition for aerospace sandwich panels, comprising diamond and SiC; The aforementioned high-temperature heat dissipation ceramic composition for aerospace sandwich panels comprises, by mass percentage: 30%~40% of SiC in the 200-500nm range. 40%~50% of SiC in the 600-2000 nm range Silicon-coated diamond 5%~10% γ-Aminopropyltriethoxysilane 3%~5% The sum of all components in the composition is 100%; The composition is mixed with a photosensitive resin to form a ceramic slurry, wherein the volume fraction of the composition in the ceramic slurry is 45%-60%. The method for preparing the ceramic slurry includes the following steps: (a) Drying SiC; (b) Prepare a mixed solution of anhydrous ethanol and deionized water; (c) Add SiC powder to the mixture solution and then ultrasonically stir to disperse it evenly; (d) Add γ-aminopropyltriethoxysilane to the dispersion solution; (e) The solution was heated and stirred; the solution was magnetically stirred in an oil bath at 50°C for 4 hours. (f) Centrifuge the suspension to achieve solid-liquid separation, wash, dry, grind, sieve, and then dry the separated solids for later use; (g) Add the powder and diamond to the photosensitive resin as described in (f) above to form a slurry and stir.

2. The high-temperature heat dissipation ceramic composition for aerospace sandwich panels according to claim 1, wherein the weight ratio of 200-500 nm SiC to 600-2000 nm SiC is 4:

5.

3. The high-temperature heat dissipation ceramic composition for aerospace sandwich panels according to any one of claims 1-2, wherein the mass percentages are: 40% SiC of 200-500 nm, 50% SiC of 600-2000 nm, 6% silicon-coated diamond, and 4% γ-aminopropyltriethoxysilane.

4. A method for preparing the high-temperature heat-dissipating ceramic composition for aerospace sandwich panels according to claim 1, comprising the following steps: (a) Dry SiC at 110°C for 24 hours; (b) Prepare a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 1:1.5; (c) Add SiC powder to the mixture solution and then ultrasonically stir for 30 minutes to ensure uniform dispersion of the powder; (d) Add γ-aminopropyltriethoxysilane to the dispersion solution; (e) The solution was heated and stirred; the solution was magnetically stirred in an oil bath at 50°C for 4 hours. (f) Centrifuge the suspension to achieve solid-liquid separation, wash the separated solid, dry it in a 100°C hot air drying oven, grind it, sieve it through a 200-mesh sieve, and then dry it for later use. (g) Add the powder and diamond to the photosensitive resin as described in (f) above to form a slurry and stir.

5. The method according to claim 4, wherein the slurry is formed by digital light processing and then sintered.

6. The method according to claim 5, wherein the slurry is formed by digital light processing, and then subjected to thermal decomposition and reactive melt infiltration sintering.

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