Preparation method of V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material

Abstract

The present invention discloses a preparation method of a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material, including the preparation of a low-density carbon fiber preform, the loading of a catalyst, the deposition for preparing ultra-high temperature ceramic nanowires, obtaining a carbon fiber preform with in-situ grown V-shaped ultra-high temperature ceramic nanowires, and densification; by adjusting parameters such as temperature and pressure during the deposition process, the present invention can effectively control the microscopic morphology such as the diameter and growth direction of the ultra-high temperature ceramic nanowires; through an external powder precursor delivery device, the introduction sequence and content of the ultra-high temperature ceramic precursor can be accurately controlled, thereby effectively controlling the composition of the ultra-high temperature ceramic nanowires; the present invention can achieve the preparation of multi-component solid solution ultra-high temperature ceramic nanowires at a relatively low temperature (<1600 °C), and introduce ultra-high temperature ceramics with ultra-high melting points into the carbon fiber preform.

Description

Technical Field

[0001] The present invention belongs to the technology for preparing tough carbon-based composites, and relates to a method for preparing a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material. Background Art

[0002] Carbon-based composites have a series of excellent properties such as low density, high specific strength, and high retention rate of high-temperature mechanical properties. Especially, with the increase of temperature, the strength increases instead of decreasing, making it one of the best candidate materials for the thermal protection components such as the leading edge and nose cone of the new generation of aerospace aircraft wings. However, for sharp and thin-walled special-shaped components such as the leading edge of the wing, carbon fibers are extremely easy to be cut off during the machining process, resulting in a significant attenuation of mechanical properties and being difficult to meet the application requirements. In addition, in a high-temperature aerobic environment, carbon-based composites will rapidly oxidize and ablate, thus limiting their further application. In view of the above problems, in recent years, researchers have carried out a large number of studies, and it has been proved that introducing one-dimensional nanomaterials such as carbon nanotubes and carbon nanofibers into the carbon fiber preform can effectively improve the fracture toughness of carbon-based composites (J. Mater. Sci. Technol., 2013, 29(8), 711-714.). In addition, researchers have further introduced HfC ceramic nanowires that combine the excellent high-temperature properties of ultra-high temperature ceramics and the special geometric properties of one-dimensional nanomaterials (J. Eur. Ceram. Soc. 2021, 41(1): 73-83.). However, the morphologies of HfC nanowires prepared by the existing processes are all upright and randomly distributed inside the carbon matrix, resulting in that some HfC nanowires are difficult to play their toughening effect, and the bonding strength between the nanowires and the carbon matrix is poor, resulting in poor toughening effect and heat transfer effect of the composite material. Therefore, it is urgent to improve the technology for preparing tough carbon-based composites and solve the problem of insufficient high-temperature mechanical properties. Summary of the Invention

[0003] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0004] A method for preparing a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material, comprising the following steps:

[0005] Step 1, preparation of a low-density carbon fiber preform: Using the isothermal chemical vapor infiltration process, pre-deposit pyrolytic carbon on the surface of the carbon fiber preform to obtain a porous low-density carbon fiber preform;

[0006] Step 2, loading of the catalyst: Immerse the carbon fiber preform obtained in Step 1 in a catalyst solution and then put it into an oven to dry, to obtain a low-density carbon fiber preform containing the catalyst;

[0007] Step 3: Place the low-density carbon fiber preform containing the catalyst in the temperature zone of a tube resistance furnace. Prepare ultra-high temperature ceramic nanowires by low-pressure chemical vapor deposition. Place the carbon fiber preform containing the catalyst in a deposition mold.

[0008] Step 4: When the temperature in the furnace reaches the set temperature, introduce a chloride precursor, a carbon source, and H2 gas. Control the pressure in the furnace below 10 kPa. After a deposition time of 0.5 - 2 h, control the pressure in the furnace at 20 - 100 kPa and continue deposition for 0.5 - 2 h.

[0009] Step 5: After deposition, stop introducing the reaction gas, turn off the heating power supply and let it cool naturally. Take out the specimen to obtain a carbon fiber preform with in-situ grown V-shaped ultra-high temperature ceramic nanowires.

[0010] Step 6: Densify the carbon fiber preform with in-situ grown V-shaped ultra-high temperature ceramic nanowires obtained in Step 5 by using a low-pressure isothermal chemical vapor infiltration process. The specific method is as follows:

[0011] Place the preform within the temperature zone of a tube deposition furnace, evacuate to below 10 kPa, and hold the pressure for 15 - 30 min. Introduce Ar as a protective gas and increase the temperature in the furnace to 900 - 1400 °C at a heating rate of 5 - 10 °C / min. Introduce CH4 gas and control the flow ratio of Ar to CH4 to be 1:1 - 5:1. The deposition time is 70 - 150 h. After deposition, stop introducing CH4, turn off the power supply, and let it cool naturally to obtain a dense ultra-high temperature ceramic nanowire toughened carbon-based composite material.

[0012] The present invention provides a method for preparing a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material. By adjusting the process parameters during low-pressure chemical vapor deposition, V-shaped ultra-high temperature ceramic nanowires are introduced into the carbon fiber preform to prepare a V-shaped ultra-high temperature ceramic nanowire modified carbon-based composite material.

[0013] This method uses chemical vapor deposition and has the following advantages: (1) By adjusting parameters such as temperature and pressure during the deposition process, the microscopic morphology such as the diameter and growth direction of ultra-high temperature ceramic nanowires can be effectively controlled; (2) By an external powder precursor delivery device, the introduction sequence and content of ultra-high temperature ceramic precursors can be precisely controlled, thereby effectively controlling the composition of ultra-high temperature ceramic nanowires; (3) The preparation of multi-component solid solution ultra-high temperature ceramic nanowires can be achieved at a relatively low temperature (<1600 °C), and ultra-high temperature ceramics with an ultra-high melting point (~4000 °C) are introduced into the carbon fiber preform. In addition, for the V-shaped ultra-high temperature ceramic nanowires obtained by this method, on the one hand, due to their unique geometric structure, a mechanical interlocking structure is constructed between the nanowires and the carbon matrix, which can improve the bonding strength between heterogeneous structures and increase the path of crack deflection during the external force loading process, thereby effectively improving the mechanical properties of the composite material; on the other hand, due to the high-temperature stability of their component composition, it can improve the ablation resistance of the composite material and enhance the stability service performance of the carbon-based composite material in extreme environments. Description of the Drawings

[0014] Figure 1 is a schematic diagram of the method of the present invention;

[0015] Figure 2 is a SEM photograph of the V-shaped HfC nanowires prepared in Example 1 of the present invention;

[0016] Figure 3 is a TEM photograph and surface scanning energy spectrum diagram of the V-shaped HfC nanowires prepared in Example 1 of the present invention;

[0017] Figure 4 is an XRD pattern of the V-shaped HfZrC nanowires prepared in Example 2 of the present invention;

[0018] Figure 5 is a microscopic morphology diagram of the V-shaped HfZrC nanowire toughened carbon-based composite material prepared in Example 3 of the present invention. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments.

[0020] Example 1:

[0021] A preparation method for a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material includes the following steps:

[0022] Step 1: Using the isothermal chemical vapor infiltration process, pre-deposit pyrolytic carbon on the surface of the carbon fiber preform to obtain a density of 0.7 g / cm3 Low-density carbon fiber preform;

[0023] Step 2: Immerse the low-density carbon fiber preform obtained in Step 1 in an ethanol solution of nickel nitrate, and then place it in an oven to dry, obtaining a low-density carbon fiber preform containing a catalyst;

[0024] Step 3: Place the low-density carbon fiber preform containing a catalyst obtained in Step 2 in a deposition mold and place it within the temperature range of a tubular resistance furnace. Evacuate to below 10 kPa, introduce Ar as a protective gas, and heat up to 1100 °C;

[0025] Step 4: When the temperature in the furnace reaches the set temperature, introduce HfCl4, CH4, and H2 gases, control the pressure in the furnace below 10 kPa. After a deposition time of 1 h, control the pressure in the furnace at 30 kPa and continue deposition for 1 h;

[0026] Step 5: After deposition, stop introducing the reaction gases, turn off the heating power supply and let it cool naturally, and take out the sample to obtain a carbon fiber preform with in-situ grown V-shaped HfC nanowires;

[0027] Step 6: Densify the carbon fiber preform with in-situ grown V-shaped HfC nanowires obtained in Step 5 by using a low-pressure isothermal chemical vapor infiltration process. The specific method is as follows: Place the preform within the temperature range of a tubular deposition furnace, evacuate to below 10 kPa, and maintain the pressure for 30 min; Introduce Ar as a protective gas, heat up the furnace temperature to 1000 °C at a heating rate of 7 °C / min, introduce CH4 gas, control the flow ratio of Ar to CH4 to be 4:1, and the deposition time is 100 h; After deposition, stop introducing CH4 and turn off the power supply to let it cool naturally, obtaining a dense V-shaped HfC nanowire toughened carbon-based composite material.

[0028] Example 2:

[0029] A preparation method of a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material, comprising the following steps:

[0030] Step 1: Adopt an isothermal chemical vapor infiltration process to pre-deposit pyrolytic carbon on the surface of a carbon fiber preform, obtaining a low-density carbon fiber preform with a density of 1.0 g / cm 3 Low-density carbon fiber preform;

[0031] Step 2: Immerse the low-density carbon fiber preform obtained in Step 1 in an ethanol solution of nickel nitrate, and then place it in an oven to dry, obtaining a low-density carbon fiber preform containing a catalyst;

[0032] Step 3: Place the low-density carbon fiber preform containing the catalyst within the temperature zone of a tube resistance furnace, and prepare HfZrC nanowires using low-pressure chemical vapor deposition. The specific method is as follows: Place the low-density carbon fiber preform containing the catalyst in a deposition mold, evacuate to below 10 kPa, introduce Ar as a protective gas, and heat up to 1200 °C;

[0033] Step 4: When the temperature in the furnace reaches the set temperature, introduce gases such as HfCl4, ZrCl4, CH4, and H2, control the pressure in the furnace below 10 kPa. After a deposition time of 1 h, control the pressure in the furnace at 50 kPa and continue deposition for 1 h;

[0034] Step 5: After deposition, stop introducing the reaction gases, turn off the heating power supply and let it cool naturally, and take out the specimen to obtain a carbon fiber preform with in-situ grown V-shaped HfZrC nanowires;

[0035] Step 6: Densify the carbon fiber preform with in-situ grown V-shaped HfZrC nanowires obtained in Step 5 using the low-pressure isothermal chemical vapor infiltration process. The specific method is as follows: Place the preform within the temperature zone of a tube deposition furnace, evacuate to below 10 kPa, and maintain the pressure for 30 min; Introduce Ar as a protective gas, increase the temperature in the furnace to 1000 °C at a heating rate of 10 °C / min, introduce CH4 gas, control the flow ratio of Ar to CH4 at 4:1, and the deposition time is 120 h; After deposition, stop introducing CH4 and turn off the power supply to let it cool naturally, and obtain a dense V-shaped HfZrC nanowire toughened carbon-based composite material.

[0036] Example 3:

[0037] A method for preparing a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material, comprising the following steps:

[0038] Step 1: Using the isothermal chemical vapor infiltration process, pre-deposit pyrolytic carbon on the surface of the carbon fiber preform to obtain a low-density carbon fiber preform with a density of 1.0 g / cm 3 low-density carbon fiber preform;

[0039] Step 2: Immerse the low-density carbon fiber preform obtained in Step 1 in an ethanol solution of nickel nitrate and then place it in an oven to dry, obtaining a low-density carbon fiber preform containing a catalyst;

[0040] Step 3: Place the low-density carbon fiber preform containing the catalyst obtained in Step 2 within the temperature zone of a tube resistance furnace, and prepare HfZrC nanowires using low-pressure chemical vapor deposition. The specific method is as follows: Place the low-density carbon fiber preform containing the catalyst in a deposition mold, evacuate to below 10 kPa, introduce Ar as a protective gas, and heat up to 1200 °C;

[0041] Step 4: When the temperature in the furnace reaches the set temperature, gases such as HfCl4, ZrCl4, CH4, and H2 are introduced. The pressure in the furnace is controlled below 10 kPa. After a deposition time of 1 h, the pressure in the furnace is controlled at 70 kPa, and the deposition continues for 2 h.

[0042] Step 5: After the deposition is completed, the reaction gases are stopped from being introduced, the heating power supply is turned off, and the temperature is allowed to drop naturally. The sample is taken out to obtain a carbon fiber preform with in-situ grown V-shaped HfZrC nanowires.

[0043] Step 6: The carbon fiber preform with in-situ grown V-shaped HfZrC nanowires obtained in Step 5 is densified by using a low-pressure isothermal chemical vapor infiltration process. The specific method is as follows: The preform is placed within the temperature range of the tube furnace. The vacuum is pumped to below 10 kPa, and the pressure is maintained for 20 min. Ar is introduced as a protective gas, and the temperature in the furnace is raised to 1100 °C at a heating rate of 10 °C / min. CH4 gas is introduced, and the flow rate ratio of Ar to CH4 is controlled at 5:1. The deposition time is 150 h. After the deposition is completed, CH4 is stopped from being introduced, the power supply is turned off, and the temperature is allowed to drop naturally to obtain a dense V-shaped HfZrC nanowire toughened carbon-based composite material.

[0044] The schematic diagram of the method of the present invention is as Figure 1 shown, Figure 2 The SEM photograph of the synthesized HfC nanowires in Example 1 can be seen. It can be seen that there are obvious bends in the synthesized nanowires, that is, they show a V-shaped structure. Figure 3 The TEM photograph and the corresponding surface scanning energy spectrum diagram of the synthesized HfC nanowires in Example 1 can be seen. It can be seen that the diameter of the nanowires is about 60 nm, and the HfC nanowires show obvious lattice fringes. The surface scanning energy spectrum shows that the Hf element and the C element are evenly distributed. Figure 4 The XRD pattern of the synthesized V-shaped HfZrC nanowires in Example 2 can be seen. It can be clearly seen from the figure that the sharp diffraction peaks are all of the HfZrC phase, indicating that the synthesized nanowires are relatively pure. Figure 5 The fracture morphology diagram of the V-shaped HfZrC nanowire toughened carbon-based composite material can be seen. It can be seen that there is obvious nanowire pull-out.

[0045] The above has described the present invention and its implementation manners. This description is not restrictive. Generally speaking, if those of ordinary skill in the art are inspired by it and without departing from the purpose of the present invention, without creative design, the structural manners and embodiments similar to the technical solution are all within the protection scope of the present invention.

Claims

1. A preparation method of a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material, characterized in that, It includes the following steps: Step 1: Preparation of low-density carbon fiber preform: Using the isothermal chemical vapor infiltration process, pre-deposit pyrolytic carbon on the surface of the carbon fiber preform to obtain a porous low-density carbon fiber preform; Step 2: Loading of catalyst: Immerse the carbon fiber preform obtained in Step 1 in the catalyst solution and then dry it in an oven to obtain a low-density carbon fiber preform containing the catalyst; Step 3: Place the low-density carbon fiber preform containing the catalyst obtained in Step 2 in the temperature zone of a tube resistance furnace, and use low-pressure chemical vapor deposition to prepare ultra-high temperature ceramic nanowires. Place the carbon fiber preform containing the catalyst in the deposition mold; Step 4: When the temperature in the furnace reaches the set temperature, introduce the chloride precursor, carbon source, and H2 gas, control the pressure in the furnace below 10 kPa, after the deposition time of 0.5 - 2 h, control the pressure in the furnace at 20 - 100 kPa, and continue the deposition for 0.5 - 2 h; Step 5: After the deposition is completed, stop introducing the reaction gas, turn off the heating power supply and let it cool naturally, and take out the sample to obtain a carbon fiber preform with in-situ grown V-shaped ultra-high temperature ceramic nanowires; Step 6: Use the low-pressure isothermal chemical vapor infiltration process to densify the carbon fiber preform with in-situ grown V-shaped ultra-high temperature ceramic nanowires obtained in Step 5. The specific method is as follows: Place the preform within the temperature zone of a tube deposition furnace, evacuate to below 10 kPa, and keep the pressure for 15 - 30 min; Introduce Ar as the protective gas, and increase the temperature in the furnace to 900 - 1400 °C at a heating rate of 5 - 10 °C / min, introduce CH4 gas, control the flow ratio of Ar to CH4 to be 1:1 - 5:1, and the deposition time is 70 - 150 h; After the deposition is completed, stop introducing CH4 and turn off the power supply to let it cool naturally, and obtain a dense ultra-high temperature ceramic nanowire toughened carbon-based composite material; In Step 4, the chloride precursor is introduced into the furnace by controlling an external powder feeding device.

2. The preparation method of a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material according to claim 1, characterized in that: In Step 1, the density of the carbon fiber preform is 0.7 to 1.1 g / cm 3 .

3. The preparation method of the V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material according to claim 1, wherein: In Step 2, the catalyst solution includes an ethanol solution or an aqueous solution of Ni metal salt.

4. The preparation method of the V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material according to claim 1, characterized in that: In Step 3, the low-density carbon fiber preform containing the catalyst is placed within the temperature zone of the tube resistance furnace in the deposition mold, evacuated to below 10 kPa, introduce Ar as the protective gas, and increase the temperature to 1000 - 1600 °C.

5. The preparation method of a V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material according to claim 1, characterized in that: In Step 4, the carbon source is a small molecule hydrocarbon, including one or more mixtures of CH4, C2H6, C2H4, and C2H6.

6. The preparation method of the V-shaped ultra-high temperature ceramic nanowire toughened carbon-based composite material according to claim 1, characterized in that: In Step 4, the chloride precursor is a refractory metal chloride, including one or more of HfCl4 and ZrCl4; the ultra-high temperature ceramic nanowire is a refractory metal carbide, including one or more of HfC and ZrC.

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