Ablation-resistant high-strength carbon ceramic spray pipe and preparation method thereof

Abstract

The invention discloses an ablation-resistant high-strength carbon-ceramic spray pipe and a preparation method thereof.The preparation method comprises the steps that a carbon-carbon spray pipe preform is soaked in an impregnant composed of organic silicon resin and boron nitride, after soaking is completed, curing and cracking are conducted in sequence, then soaking, curing and cracking are conducted repeatedly and circularly, and a carbon-ceramic spray pipe blank is obtained; embedding the carbon-ceramic spray pipe blank in silicon powder for melting and siliconizing to obtain the carbon-ceramic spray pipe; the aperture ratio of the carbon-ceramic spray pipe is smaller than 2%, the density is high, oxidation ablation components can be prevented from infiltrating into a product, the continuous oxidation ablation degree can be relieved through a certain amount of SiO2 contained in the base body, the ablation resistance of the product can be further enhanced through a certain amount of BN contained in the base body, and the service life of the carbon-ceramic spray pipe is prolonged. A certain lubricating effect is exerted on the surface of the product to prevent high-speed flame jet from scouring the product; under the cooperation of the multiple aspects, the carbon-ceramic spray pipe can be applied to a harsh environment to stably play a role.

Description

Technical Field

[0001] This invention belongs to the field of aerospace rocket engine component technology, specifically relating to a carbon ceramic nozzle with high strength and resistance to ablation and its preparation method. Background Technology

[0002] Currently, rocket engine nozzles commonly use high-temperature alloys, ceramics, graphite, carbon-carbon composites, and a small amount of carbon-ceramic composites. During rocket engine operation, the flame jet in contact with the inner wall of the nozzle can reach temperatures as high as 3000°C. Conventional materials such as metals and high-temperature alloys often cannot withstand such high temperatures, ceramic materials have poor strength and are easily damaged after being subjected to rapid temperature changes; graphite and carbon-carbon materials will exhibit ablation, and the strength of graphite is also easily damaged after being subjected to rapid temperature changes; carbon-ceramic composites have the characteristics of high strength and high temperature resistance, but the carbon components such as carbon fibers in their composition are also prone to ablation, affecting their lifespan.

[0003] Therefore, improving the ablation resistance of carbon ceramic nozzles and enhancing material strength can significantly extend the service life of nozzles, which is the key to solving the current problems. Summary of the Invention

[0004] To address the problems of existing technologies, the first objective of this invention is to provide a method for preparing a carbon-ceramic nozzle with high ablation resistance and strength. The method provided by this invention is simple, controllable, and suitable for industrial production.

[0005] The second objective of this invention is to provide a carbon-ceramic nozzle prepared by the above-described method. The carbon-ceramic nozzle provided by this invention has an opening ratio of <2%, high density, and can prevent the infiltration of oxidizing and ablation components into the product interior. The presence of a certain amount of SiO2 in the matrix can alleviate the degree of continuous oxidizing and ablation, while the presence of a certain amount of BN can further enhance the product's resistance to ablation and provide a certain lubricating effect on the product surface to prevent the high-speed flame jet from eroding the product. Through the synergistic effect of these multiple aspects, the carbon-ceramic nozzle of this invention can function stably in harsh environments.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention discloses a method for preparing a carbon-ceramic nozzle with high strength and resistance to ablation. The carbon-ceramic nozzle preform is impregnated in an impregnating agent. After impregnation, it is cured and pyrolyzed in sequence. The impregnation-curing-pyrolysis cycle is repeated to obtain a carbon-ceramic nozzle blank. The carbon-ceramic nozzle blank is embedded in silicon powder and melt-infiltrated to obtain a carbon-ceramic nozzle.

[0008] The impregnating agent is composed of silicone resin (polysiloxane) and boron nitride, with a mass ratio of silicone resin to boron nitride of 5-10:1.

[0009] The carbon-ceramic nozzle provided by this invention uses a resin composed of organosilicon resin and boron nitride to densify the carbon-carbon nozzle preform. By introducing organosilicon resin, a certain amount of SiO2 can be obtained. At high temperatures, SiO2 softens and automatically fills cracks and ablation cavities, which can alleviate the degree of continuous oxidation and ablation. The introduced boron nitride micro powder has extremely high oxidation resistance, wear resistance and lubricity, which can further enhance the product's ablation resistance and play a certain lubricating role on the product surface to prevent the high-speed flame jet from eroding the product. Finally, high-temperature melting infiltration can improve the density of the product and attach a dense SiSiC film to the surface of the product.

[0010] In this invention, the contents of organosilicon resin and boron nitride need to be effectively controlled. The resin content affects the boron nitride content. A high boron nitride content will reduce the permeability of the silicon melt during the subsequent melt infiltration process, while a low boron nitride content will have a certain impact on the product's resistance to oxidation and ablation. At the same time, if the resin content is reduced, the resin + boron nitride slurry will become more viscous, making it difficult and less effective for the slurry to penetrate into the pores inside the carbon-carbon nozzle.

[0011] In a preferred embodiment, the carbon-carbon nozzle preform is obtained by first heat-treating a carbon fiber preform and then performing chemical vapor deposition on a carbon matrix, wherein the carbon fiber preform is a three-dimensional woven carbon fiber component.

[0012] In this invention, a three-dimensionally woven carbon fiber preform is used, which has high strength.

[0013] More preferably, the density of the carbon fiber preform is 0.50-0.60 g / cm³. 3 The preferred value is 0.53-0.57 g / cm³. 3 The carbon fiber preform achieves optimal performance when its density is controlled within this range. If the density is too low, the strength of the final carbon-ceramic nozzle will be reduced, while if the density is too high, it will affect the uniformity of subsequent vapor-deposited carbon and impregnation processes, thus also reducing the performance of the final carbon-ceramic nozzle.

[0014] In a further preferred embodiment, the heat treatment is carried out under a protective atmosphere, and the heat treatment temperature is 1800-2200℃, preferably 1950-2050℃.

[0015] Further preferred, the temperature during chemical vapor deposition is 1050-1150℃, preferably 1090-1110℃, and the pressure is 1-2 kPa, preferably 1.2-1.5 kPa; the mixed atmosphere introduced has a volume ratio of natural gas:propane:nitrogen = 2-4:1:2, preferably 3:1:2.

[0016] In this invention, natural gas and propane are used together as carbon source gases, which not only results in fast deposition speed but also uniform deposition. At the same time, the use of a mixture of natural gas and propane not only effectively reduces production costs and improves product quality, but also makes it easier to form a rough carbon layer structure after deposition that is more conducive to impregnation and melting, resulting in a carbon ceramic nozzle with better performance.

[0017] However, the content of natural gas and propane in the carbon source gas needs to be controlled within the range of this invention. If the natural gas content is low, the carbon deposition rate will be slow and the production cycle will be long. If the natural gas content is high, it will easily cause a large density gradient in different areas of the product. At the same time, the utilization rate of natural gas will be reduced. In addition, if a large amount of incompletely utilized natural gas is generated, more tar-like substances will be generated in the equipment pipeline, which will greatly increase the difficulty of equipment cleaning and maintenance. Furthermore, if the temperature or pressure is too low, it will also lead to low natural gas utilization and a long production cycle. If the temperature is too high, carbon black will easily block the surface of the product, resulting in a large density gradient in different areas of the product. High pressure will easily cause product density gradient and increase the difficulty of equipment maintenance and cleaning.

[0018] In a preferred embodiment, the density of the carbon-carbon nozzle preform is 0.8-1.0 g / cm³. 3 The preferred value is 0.85-0.95 g / cm³. 3 .

[0019] In a preferred embodiment, the impregnating agent, by mass ratio, is silicone resin:boron nitride = 7-8:1.

[0020] In a preferred embodiment, the boron nitride particle size is 0.5-2.0 μm, preferably 0.5 μm. In this invention, controlling the boron nitride particle size within the range specified herein ensures effective impregnation at a lower cost.

[0021] In a preferred embodiment, the pyrolysis temperature is 900-1300℃, more preferably 1100-1200℃. This preferred temperature not only ensures the pyrolysis process proceeds fully but also saves energy.

[0022] In a preferred embodiment, the number of impregnation-curing-pyrolysis cycles is 2-4. The number of impregnation-curing-pyrolysis cycles refers to the total number of impregnation, curing, and pyrolysis cycles performed.

[0023] In a preferred embodiment, the density of the carbon-ceramic nozzle blank is 1.20-1.50 g / cm³. 3 The preferred value is 1.30-1.40 g / cm³. 3 The density of the carbon-ceramic nozzle blank should be controlled within the above-mentioned range, with uniform pore distribution and appropriate SiO2 and BN content. Excessive density and SiO2 content will cause corrosion of the fiber matrix during high-temperature melting and infiltration, resulting in a decline in mechanical properties.

[0024] In a preferred embodiment, the temperature of the molten silicon infiltration is 1500-1700℃, the time is 0.1-1.0h, and the pressure is <1KPa.

[0025] In this invention, the carbon-ceramic nozzle blank needs to be embedded in silicon powder for melt silicon infiltration, which is beneficial for the silicon liquid to penetrate into the interior of the carbon-ceramic nozzle matrix and can obtain a carbon-ceramic nozzle with higher density. If the traditional method is used, the blank is laid flat on silicon powder and melt silicon infiltration is carried out by the silicon liquid penetrating upward. However, the introduced boron nitride has a certain impact on the penetration reaction of the silicon liquid and reduces the silicon infiltration effect.

[0026] In this invention, the melting temperature needs to be effectively controlled. A lower melting temperature and a shorter time will result in a lot of residue, while a higher melting temperature and a longer time will cause excessive consumption of SiO2 in the carbon ceramic nozzle matrix. Since SiO2 also reacts with C, controlling the melting time and temperature within the range of this invention can ensure a suitable SiO2 content.

[0027] In a further preferred embodiment, the temperature of the molten silicon infiltration is 1550-1600℃, the time is 0.2-0.3h, and the pressure is <1KPa.

[0028] In a preferred embodiment, the density of the carbon-ceramic nozzle is 2.20-2.40 g / cm³. 3 The preferred value is 2.25-2.40 g / cm³. 3 The porosity is less than 2%. The high density ensures the compactness of the carbon ceramic nozzle, prevents the penetration of oxidizing and ablating components into the product interior, and improves the service life of the carbon ceramic nozzle.

[0029] The present invention also provides a carbon ceramic nozzle prepared by the above preparation method.

[0030] The carbon ceramic nozzle provided by this invention has a compressive strength > 400 MPa, a flexural strength > 180 MPa, and a tensile strength > 120 MPa.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The carbon ceramic nozzle of the present invention has high strength and is not easy to crack or be damaged.

[0033] (2) The economic benefits of using silicone resin are far superior to some conventional precursors (such as PCS / PMS), and the impregnation material is easier to prepare.

[0034] (3) Impregnation with silicone resin can obtain a certain amount of SiO2. At high temperature, SiO2 softens and automatically fills cracks and ablation holes, which can alleviate the degree of continuous oxidation and ablation.

[0035] (4) The impregnated boron nitride micro powder has extremely high antioxidant, wear resistance and lubricity, which can further enhance the product's resistance to ablation and play a certain lubricating role on the product surface to prevent the high-speed flame jet from scouring the product.

[0036] (5) High-temperature melting infiltration attaches a dense SiSiC film to the surface of the product, which enhances the ablation resistance. Attached Figure Description

[0037] Figure 1 A physical image of the carbon ceramic nozzle prepared in Example 1. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments and comparative examples.

[0039] Example 1

[0040] (1) Three-dimensional weaving yielded a density of 0.55 g / cm³. 3 Carbon fiber nozzle preform;

[0041] (2) Under an argon atmosphere, the carbon fiber nozzle preform is subjected to high-temperature heat treatment at 2000℃;

[0042] (3) The preform nozzle after high-temperature heat treatment was densified to 0.91 g / cm³ by vapor deposition in a mixed atmosphere of natural gas, propane and nitrogen in a ratio of 3:1:2, at a temperature of 1100℃ and a pressure of 1.2-1.5 kPa. 3 Obtain a carbon nozzle;

[0043] (4) The carbon-carbon nozzle was continuously impregnated (impregnating agent, by mass ratio, silicone resin: 0.5μm boron nitride = 7.5:1), impregnated, cured, and pyrolyzed (at a temperature of 1200℃) for a total of 3 cycles, resulting in a density of 1.36 g / cm³. 3 Carbon ceramic nozzle substrate;

[0044] (5) The carbon ceramic nozzle substrate was embedded in silicon powder and melt-infiltrated at 1600℃ and pressure <0.5KPa for 0.2h to obtain a density of 2.31g / cm³. 3 A carbon ceramic nozzle with an orifice ratio of 0.68%.

[0045] In this embodiment, the carbon-ceramic nozzle has a tensile strength of 205.42 MPa, a flexural strength of 312.31 MPa, and an interlaminar shear strength of 48.50 MPa.

[0046] In this embodiment, the carbon ceramic nozzle was tested in a ground ignition experiment according to GJB 323A-96. The linear ablation rate was 1.51 μm / s and the mass ablation rate was 1.82 mg / s.

[0047] Example 2

[0048] The difference between this embodiment and embodiment 1 is that an impregnation pyrolysis cycle is added.

[0049] (1) Three-dimensional weaving yielded a density of 0.55 g / cm³. 3 Carbon fiber nozzle preform;

[0050] (2) Under an argon atmosphere, the carbon fiber nozzle preform is subjected to high-temperature heat treatment at 2000℃;

[0051] (3) The preform nozzle after high-temperature heat treatment was densified to 0.91 g / cm³ by vapor deposition in a mixed atmosphere of natural gas, propane and nitrogen in a ratio of 3:1:2, at a temperature of 1100℃ and a pressure of 1.2-1.5 kPa. 3 Obtain a carbon nozzle;

[0052] (4) The carbon-carbon nozzle was continuously impregnated (impregnating agent, by mass ratio, silicone resin: 0.5μm boron nitride = 7.5:1), impregnated, cured, and pyrolyzed (at a temperature of 1200℃) for a total of 4 cycles, resulting in a density of 1.46 g / cm³. 3 Carbon ceramic nozzle substrate;

[0053] (5) The carbon ceramic nozzle substrate was embedded in silicon powder and melt-infiltrated at 1600℃ and pressure <0.5KPa for 0.2h to obtain a density of 2.26g / cm³. 3 A carbon ceramic nozzle with an orifice ratio of 0.73%.

[0054] In this embodiment, the carbon ceramic nozzle has a tensile strength of 198.42 MPa, a flexural strength of 301.31 MPa, and an interlaminar shear strength of 42.50 MPa, which are slightly lower than those in Example 1.

[0055] In this embodiment, the carbon ceramic nozzle was tested according to GJB 323A-96 and the linear ablation rate was 1.73 μm / s, and the mass ablation rate was 2.05 mg / s.

[0056] Example 3

[0057] The difference between this embodiment and Embodiment 1 is that the melting and infiltration temperature is increased.

[0058] (1) Three-dimensional weaving yielded a density of 0.55 g / cm³. 3 Carbon fiber nozzle preform;

[0059] (2) Under an argon atmosphere, the carbon fiber nozzle preform is subjected to high-temperature heat treatment at 2000℃;

[0060] (3) The preform nozzle after high-temperature heat treatment was densified to 0.90 g / cm³ by vapor deposition in a mixed atmosphere of natural gas, propane and nitrogen in a ratio of 3:1:2, at a temperature of 1100℃ and a pressure of 1.2-1.5 kPa. 3 Obtain a carbon nozzle;

[0061] (4) The carbon-carbon nozzle was continuously impregnated (impregnating agent, by mass ratio, silicone resin: 0.5μm boron nitride = 7.5:1), impregnated, cured, and pyrolyzed (at a temperature of 1200℃) for a total of 3 cycles, resulting in a density of 1.35 g / cm³. 3 Carbon ceramic nozzle substrate;

[0062] (5) The carbon ceramic nozzle substrate was embedded in silicon powder and melt-infiltrated at 1700℃ and pressure <0.5KPa for 0.2h to obtain a density of 2.32g / cm³. 3 A carbon ceramic nozzle with an orifice ratio of 1.95%.

[0063] In this embodiment, the carbon-ceramic nozzle has a tensile strength of 191.05 MPa, a flexural strength of 294.20 MPa, and an interlaminar shear strength of 40.24 MPa.

[0064] In this embodiment, the carbon ceramic nozzle was tested according to GJB 323A-96 and the linear ablation rate was 1.90 μm / s, and the mass ablation rate was 2.22 mg / s.

[0065] Comparative Example 1

[0066] Both the graphite and carbon-carbon nozzles suffered severe ablation and damage during ground ignition tests.

[0067] In contrast, carbon ceramic nozzles that underwent deposition and infiltration but were not impregnated with silicone resin and boron nitride also showed significant ablation after ignition tests.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that the concentration of boron nitride in the impregnating material is increased to silicone resin: boron nitride = 7.5:2.

[0070] The impregnation slurry in this comparative example is thick, making impregnation difficult and resulting in poor effects.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is that the melting temperature is increased to 1800°C.

[0073] In this comparative example, the density of the carbon ceramic nozzle is 2.32 g / cm³. 3The open area ratio is 5.31%; the tensile strength of the carbon-ceramic nozzle is 150.12 MPa, the flexural strength is 245.35 MPa, and the interlaminar shear strength is 30.58 MPa; after testing according to GJB 323A-96, the linear ablation rate of the carbon-ceramic nozzle is 4.5 μm / s, and the mass ablation rate is 4.09 mg / s.

[0074] The comparative carbon ceramic nozzle showed a significant improvement in orifice ratio and ablation rate, but a significant decrease in mechanical properties.

Claims

1. A method for preparing an ablation-resistant, high-strength carbon-ceramic nozzle, characterized in that: The carbon-carbon nozzle preform is immersed in an impregnating agent. After impregnation, it is cured and pyrolyzed in sequence. Then, the impregnation-curing-pyrolysis cycle is repeated to obtain a carbon-ceramic nozzle blank. The carbon-ceramic nozzle blank is embedded in silicon powder and melt-infiltrated to obtain a carbon-ceramic nozzle. The impregnating agent is composed of silicone resin and boron nitride, with a mass ratio of silicone resin to boron nitride of 5-10:

1.

2. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 1, characterized in that: The carbon-carbon nozzle preform is obtained by first heat-treating a carbon fiber preform and then performing chemical vapor deposition on a carbon matrix. The carbon fiber preform is a three-dimensional woven carbon fiber component.

3. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 2, characterized in that: The density of the carbon fiber preform is 0.50-0.60 g / cm³. 3 .

4. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 2, characterized in that: The heat treatment is carried out under a protective atmosphere at a temperature of 1800-2200℃. The temperature during chemical vapor deposition is 1050-1150℃, the pressure is 1-2 kPa, and the mixed atmosphere introduced is natural gas:propane:nitrogen = 2-4:1:2 by volume. The density of the carbon-carbon nozzle preform is 0.8-1.0 g / cm³. 3 .

5. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 1, characterized in that: The impregnating agent, by mass ratio, is silicone resin:boron nitride = 7-8:1; The boron nitride has a particle size of 0.5-2.0 μm.

6. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 1, characterized in that: The pyrolysis temperature is 900-1300℃; the number of impregnation-curing-pyrolysis cycles is 2-4.

7. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 1, characterized in that: The density of the carbon-ceramic nozzle blank is 1.20-1.50 g / cm³. 3 .

8. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 1, characterized in that: The temperature for molten silicon infiltration is 1500-1700℃, the time is 0.1-1.0h, and the pressure is <1KPa.

9. The method for preparing an ablation-resistant, high-strength carbon ceramic nozzle according to claim 1, characterized in that: The density of the carbon-ceramic nozzle is 2.20-2.40 g / cm³. 3 The open area ratio is less than 2%.

10. The carbon ceramic nozzle prepared by the preparation method according to any one of claims 1-10.

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