Composite materials, methods of making and using the same

Abstract

The present application relates to the technical field of tantalum carbide material, and provides a composite material and a preparation method and application thereof, the preparation method of the composite material comprises the following steps: (1) the surface of the substrate is subjected to plasma oxidation treatment to obtain an oxidized substrate; (2) a first deposition is carried out on the surface of the oxidized substrate in the presence of a first gas system for depositing tantalum carbide to obtain a first preform containing a tantalum carbide coating; (3) a second deposition is carried out on the surface of the first preform in the presence of hafnium carbide particles and a second gas system for depositing tantalum carbide to obtain a second preform containing a hafnium carbide-tantalum carbide coating; (4) the second preform is subjected to heat treatment to obtain the composite material. The coating on the surface of the composite material prepared by the method is tough and dense, and the substrate has strong bonding force with the coating on the surface thereof.

Description

Technical Field

[0001] This invention relates to the technical field of tantalum carbide materials, specifically to a composite material and its preparation method. Background Technology

[0002] The extreme operating conditions faced by solid rocket propulsion systems pose a severe challenge to ultra-high temperature materials, especially against the backdrop of rapid development in the aerospace field. Carbon-based materials are renowned for their high specific strength, excellent thermal conductivity, suitable thermal shock resistance, and good mechanical properties at high temperatures. These characteristics make them highly favored in the aerospace industry, particularly in rocket nozzles, nose tips, and leading edges of gas turbine engine components. However, carbon-based materials are easily oxidized in high-temperature oxidizing environments and suffer from poor tolerance to ammonia gas and insufficient wear resistance, leading to latent degradation. This makes them increasingly unable to meet increasingly stringent usage requirements, severely limiting their application potential at high temperatures.

[0003] On the other hand, tantalum carbide (TaC) ceramics have a high melting point of 3880℃, extremely high hardness (Mohs hardness of 9-10), and a relatively high thermal conductivity (22 W·m). -1 ·K -1 It has high flexural strength (340-400 MPa) and a small coefficient of thermal expansion (6.6 × 10⁻⁶). -6 K -1 Furthermore, TaC exhibits excellent thermochemical stability and superior physical properties. Therefore, TaC coatings are widely used in various fields such as aerospace thermal protection, single crystal growth, energy electronics, and medical devices. Compared to bare graphite or SiC-coated graphite, TaC coatings demonstrate superior chemical corrosion resistance, making them particularly suitable for growing GaN or AlN single crystals in MOCVD equipment and SiC single crystals in PVT equipment, significantly improving the quality of the grown single crystals. However, the bonding force between a single tantalum carbide coating and carbon-based materials is relatively weak, making it prone to cracking and leading to product failure. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a composite material and its preparation method. The composite material prepared by this method has a tough and dense coating on the surface of the substrate, and there is a strong bonding force between the substrate and the coating on its surface.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a composite material, the method comprising the following steps:

[0006] (1) Plasma oxidation treatment is performed on the surface of the substrate to obtain an oxidized substrate;

[0007] (2) In the presence of a first gas system for depositing tantalum carbide, a first deposition is performed on the surface of an oxidized substrate to obtain a first preform containing a tantalum carbide coating.

[0008] (3) A second deposition is performed on the surface of the first preform in the presence of hafnium carbide particles and a second gas system for depositing tantalum carbide to obtain a second preform containing a hafnium carbide-tantalum carbide coating;

[0009] (4) The second preform is heat-treated to obtain the composite material.

[0010] A second aspect of the present invention provides a composite material, wherein the composite material is prepared by the preparation method described in the first aspect.

[0011] The third aspect of the present invention provides the application of the composite material described in the second aspect as a high-temperature resistant material.

[0012] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0013] In this invention, a thin layer of TaC is deposited first, and then HfC powder is added at the same time as the TaC layer is deposited to create a heterogeneous nucleation environment, which promotes the mutual solubility of HfC and TaC. A dense and tough HfC-TaC layer is obtained by deposition at a lower temperature. With a certain period of heat treatment, the porosity, cracks and defects on the coating surface can be greatly reduced, thereby improving the bonding performance between the coating and the substrate, and improving the high temperature resistance and ablation resistance of the composite material.

[0014] This invention incorporates HfC powder during the deposition of the TaC layer in a single deposition process, which effectively reduces the reaction temperature, allowing deposition to be carried out at around 1000°C. This significantly reduces production costs and saves time on heating and cooling.

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to those ranges or values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In this document, unless otherwise specified, data ranges include endpoints. Attached Figure Description

[0016] Figure 1 The image shown is a SEM image of the surface of the composite material prepared in Example 1 of the present invention.

[0017] Figure 2 The image shown is an XRD pattern of the surface of the composite material prepared in Example 1 of the present invention. Detailed Implementation

[0018] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0020] The first aspect of this invention provides a method for preparing a composite material, the method comprising the following steps:

[0021] (1) Plasma oxidation treatment is performed on the surface of the substrate to obtain an oxidized substrate;

[0022] (2) In the presence of a first gas system for depositing tantalum carbide, a first deposition is performed on the surface of an oxidized substrate to obtain a first preform containing a tantalum carbide coating.

[0023] (3) A second deposition is performed on the surface of the first preform in the presence of hafnium carbide particles and a second gas system for depositing tantalum carbide to obtain a second preform containing a hafnium carbide-tantalum carbide coating;

[0024] (4) The second preform is heat-treated to obtain the composite material.

[0025] The substrate can be at least one of carbon-based substrate, silicon-based substrate and SiC substrate. It can be a substrate or a substrate with a transition layer already attached (for example, the substrate can include a carbon-based substrate and a SiC coating attached to the carbon-based substrate).

[0026] In some embodiments, the substrate is a carbon-based substrate.

[0027] In some embodiments, the carbon-based substrate is graphite (such as isostatic graphite) or carbon fiber reinforced carbon.

[0028] In some embodiments, the coefficient of thermal expansion of the carbon-based substrate is 4 × 10⁻⁶. -6 / K-7.5×10 -6 / K, density is 1.7-2.2 g / cm³ 3 The porosity is 5-25%, and the grain size is less than 5μm.

[0029] In some embodiments, the method further includes pretreating the substrate before plasma oxidation treatment. Pretreatment can give the substrate surface a certain roughness and / or remove impurities from the substrate surface. Processes including, but not limited to, grinding, sandblasting, and plasma treatment can be used to give the substrate surface a certain roughness (Ra = 0.2 μm-2 μm) and high cleanliness, ensuring a tight bond between the coating and the substrate.

[0030] Impurities can be removed by cleaning the substrate, which can be done by washing with water, acid washing, rinsing, and / or immersion, using conventional methods in the art, as long as the impurities on the substrate surface are removed. It should be understood that after cleaning, the substrate can be dried before use in subsequent deposition processes. The drying method can be conventional, such as using a vacuum dryer or forced air drying (drying at 100-300℃ for more than 2 hours). Alternatively, an oxygen-containing atmosphere (oxygen concentration of, for example, 200ppm-500ppm) can be introduced to oxidize and remove or purge particles from the substrate surface.

[0031] Plasma oxidation is an effective method widely used in material surface modification technology. It utilizes high-energy reactive particles in plasma to bombard the material surface, altering its surface chemical composition, structure, and properties. Studies have found that compared to conventional oxidation methods, plasma oxidation can improve the adhesion between the substrate and the coating.

[0032] In plasma oxidation treatment, plasma is typically generated first, for example, through gas discharge in a plasma reaction chamber. The gas used to generate the plasma can be a conventional gas in the art, such as oxygen, and optionally an auxiliary gas (such as argon or helium). The resulting plasma can be used to treat substrates; for example, a graphite substrate to be treated can be placed in the plasma reaction chamber and exposed to the plasma. The high-energy reactive particles in the plasma bombard the surface of the graphite substrate, reacting with it to form an oxide layer. After the oxidation treatment is complete, the substrate can be washed with deionized water to remove reaction residues, and then dried in a drying oven.

[0033] Plasma oxidation treatment can be performed under conventional conditions in the art, as long as the oxidation effect can be achieved. In some embodiments, the conditions for plasma oxidation treatment include: a power of 120-180W (e.g., 120W, 130W, 140W, 150W, 160W, 170W, 180W), a discharge frequency of 10-15MHz (e.g., 10MHz, 11MHz, 12MHz, 13MHz, 14MHz, 15MHz), and a time of 5-20min (e.g., 5min, 10min, 15min, 20min).

[0034] In some embodiments, the mass ratio of C to O elements on the graphite (substrate) surface is 10-20, for example, 10, 12, 14, 16, 18, or 20.

[0035] In some embodiments, the C and O elements on the graphite surface exist in the forms of CC, C-OH, and COC.

[0036] In some embodiments, the graphite surface contains 82-92 wt% CC (e.g., 82 wt%, 85 wt%, 88 wt%, 90 wt%, 92 wt%), 5-12 wt% C-OH (e.g., 5 wt%, 7 wt%, 9 wt%, 10 wt%, 12 wt%), and 1-7 wt% COC (e.g., 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%).

[0037] In some embodiments, the mass ratio of C to O elements on the surface of the oxidized substrate is 14 or less (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14), preferably 1-12.

[0038] In some embodiments, the C and O elements on the surface of the oxidized substrate exist in the forms of CC, C-OH, COC, and -COOH.

[0039] In some embodiments, the content of CC on the surface of the oxidized substrate is 65-85 wt% (e.g., 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%), the content of C-OH is 8-18 wt% (e.g., 8 wt%, 10 wt%, 12 wt%, 14 wt%, 16 wt%, 18 wt%), the content of COC is 2-15 wt% (e.g., 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%), and the content of -COOH is 2-10 wt% (e.g., 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%).

[0040] In some embodiments, the first and second deposition methods are each independently CVD deposition, and the equipment used can be a CVD vapor deposition furnace. The substrate is first placed horizontally in the deposition reaction chamber, the furnace door is closed, the reaction chamber is evacuated to a vacuum below 200 Pa, and then the temperature is increased to the deposition temperature at a rate of 2°C / min-10°C / min. The first and second depositions can be carried out continuously, that is, the deposition process is uninterrupted.

[0041] In some embodiments, the first gas system and the second gas system each independently include a Ta source, a C source, a reducing gas, and a diluting gas.

[0042] In some embodiments, the Ta source gas comprises at least one of TaF5, TaCl5, and TaBr5. The Ta source gas can be obtained by sublimation of Ta source powder or particles. The Ta source powder can be obtained by grinding (e.g., ball milling) Ta source solid particles in an inert atmosphere (e.g., argon). Preferably, the particle size Dv50 of the Ta source powder can be less than 1 mm, such as 100 μm, 200 μm, 400 μm, 500 μm, 600 μm, 800 μm, or 900 μm.

[0043] In some embodiments, the C source gas includes at least one of CH4, C2H4, C2H6, C3H6, and C3H8.

[0044] In some embodiments, the reducing gas is hydrogen.

[0045] In some embodiments, the diluent gas can be an inert gas, that is, one that does not react with other components, such as argon (Ar) or helium (He).

[0046] In some embodiments, the particle size Dv50 of hafnium carbide particles is 2-8 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm. When the particle size Dv50 of hafnium carbide particles is within this range, the density of the coating and the adhesion between the substrate and the coating can be further improved, while providing more nucleation sites and enhancing density. HfC powder can be ball-milled to this range, and Dv50 can be measured using a laser particle size analyzer.

[0047] In some embodiments, the molar ratio of tantalum and carbon in the first gas system and the second gas system is independently 1:0.5-1 (e.g., 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1).

[0048] In some embodiments, during the second deposition process, the molar ratio of hafnium to tantalum is 1:5-10.

[0049] In some embodiments, the molar ratio of tantalum and reducing gas in the first gas system and the second gas system is independently 1:0.5-5 (e.g., 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5).

[0050] In some embodiments, the molar ratio of tantalum to dilution gas in the first gas system and the second gas system is independently 1:50-100 (e.g., 1:50, 1:60, 1:70, 1:80, 1:90, 1:100).

[0051] In some embodiments, the flow rate of the tantalum source in the first gas system and the second gas system is independently 20-60 g / min (e.g., 20 g / min, 30 g / min, 40 g / min, 50 g / min, 60 g / min).

[0052] In some embodiments, the HfC flow rate is 3-10 g / min (e.g., 3 g / min, 5 g / min, 7 g / min, 9 g / min, 10 g / min).

[0053] In some embodiments, the conditions of the first deposition result in a tantalum carbide coating thickness of 0.1-0.2 μm (e.g., 0.1 μm, 0.15 μm, 0.2 μm).

[0054] In some embodiments, the conditions for the first deposition include: a deposition temperature of 1050-1300°C (e.g., 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C), a pressure of 1 kPa-5 kPa (e.g., 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa), and a time of 10-30 min (e.g., 10 min, 15 min, 20 min, 25 min, 30 min).

[0055] The end time of the first deposition can be counted as the time when HfC is introduced. At the end of the first deposition, TaC grains are in the seed state under high temperature conditions. After adding HfC powder, it is beneficial for HfC to dissolve TaC and can also greatly reduce the nucleation energy of TaC, which is more conducive to nucleation and improves the density of the composite coating, enhancing the toughness and high temperature resistance of the coating.

[0056] In some embodiments, the conditions of the second deposition are such that the thickness of the hafnium carbide-tantalum carbide coating is 20-40 μm (e.g., 20 μm, 25 μm, 30 μm, 35 μm, 40 μm).

[0057] In some embodiments, the conditions for the second deposition include: a deposition temperature of 1050-1300°C (e.g., 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C), a pressure of 1 kPa-5 kPa (e.g., 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa), and a time of 2 h-4 h (e.g., 2 h, 2.5 h, 3 h, 3.5 h, 4 h).

[0058] In some embodiments, the heat treatment conditions include: a temperature of 1100-1500°C (e.g., 1100°C, 1200°C, 1300°C, 1400°C, 1500°C), a pressure of 3 kPa-7 kPa (e.g., 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa), and a time of 2 h-4 h (e.g., 2 h, 2.5 h, 3 h, 3.5 h, 4 h). By heat treating the coating, lattice distortion caused by solid solution is eliminated, internal stress is reduced, and thus, porosity, cracks, etc., in the coating can be further reduced.

[0059] After obtaining the final product, a vacuum cooling operation can be performed. The specific operation method can be the conventional operation method in this field. For example, after the last deposition, the furnace can be evacuated to below 200 Pa, and the temperature can be gradually reduced to room temperature at a cooling rate of 2-10℃ / min. Then, Ar or N2 is introduced at a rate of 20-200L / min to adjust the pressure to atmospheric pressure, and then the furnace can be opened to take out the product.

[0060] A second aspect of the present invention provides a composite material, wherein the composite material is prepared by the preparation method described in the first aspect.

[0061] In some embodiments, the composite material comprises a substrate (containing oxygen on its surface) and a composite coating located on the surface of the substrate, the composite coating comprising a TaC coating adjacent to the substrate and an HfC-TaC coating located on the other side of the TaC coating.

[0062] The hafnium carbide-tantalum carbide coating has a dense surface, without micropores that could cause coating failure, and has relatively large grains. In some embodiments, the average grain size of the HfC-TaC coating surface is 15-40 μm (e.g., 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm).

[0063] In this invention, the grain size can be obtained by observing the coating surface with an optical microscope or a scanning electron microscope and measuring and calculating it using ImageJ software.

[0064] In some embodiments, the composite coating contains 36-46 at% Ta (e.g., 36 at%, 38 at%, 40 at%, 42 at%, 44 at%, 46 at%), 5-12 at% Hf (e.g., 5 at%, 7 at%, 9 at%, 10 at%, 11 at%, 12 at%), and 40-55 at% C (e.g., 40 at%, 45 at%, 50 at%, 55 at%). Here, at% refers to atomic percentage.

[0065] In some embodiments, the thickness of the HfC-TaC coating is 10-40 μm (e.g., 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm).

[0066] In some embodiments, the thickness of the TaC coating is less than 0.5 μm (e.g., 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm).

[0067] In some embodiments, the thickness of the composite coating is 10-40 μm (e.g., 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm).

[0068] In this invention, the method for determining the content of each element is energy-dispersive X-ray spectroscopy, which involves taking points in the coating area for spot scanning and obtaining the content of each element.

[0069] For parameters regarding the thickness of each coating, please refer to the first aspect.

[0070] The third aspect of the present invention provides the application of the composite material described in the second aspect as a high-temperature resistant material.

[0071] The composite material can be used as a semiconductor material and can be applied to fields such as single crystal growth, energy electronics, aerospace, semiconductors, and new energy vehicles.

[0072] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. The present invention will be described in detail below with reference to specific embodiments, which are used to understand rather than limit the present invention.

[0073] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0074] The present invention will now be described in detail with reference to specific embodiments, which are intended to understand rather than limit the invention.

[0075] The graphite sheet used in the following examples is a substrate, and its surface includes C and O elements in the form of CC, C-OH and COC. The mass ratio of C to O elements is 13.28, and the content of CC is 87.04 wt%, the content of C-OH is 8.8 wt%, and the content of COC is 4.09 wt%.

[0076] Example 1

[0077] (1) In a plasma reaction chamber, the surface of the graphite sheet is subjected to plasma oxidation. The plasma gas is oxygen. After the plasma treatment is completed, the graphite sheet is washed with deionized water to remove plasma reaction residue, and then the graphite sheet is dried in a drying oven. The conditions for plasma oxidation include: a processing power of 150W and plasma discharge at a discharge frequency of 13MHz for 10 minutes.

[0078] After plasma oxidation, the surface of the graphite sheet contains C and O elements in the form of CC, C-OH, COC and -COOH. The mass ratio of C to O elements is 4.18, and the content of CC is 74.31 wt%, the content of C-OH is 10.52 wt%, the content of COC is 10.58 wt%, and the content of -COOH is 6.59 wt%.

[0079] (2) Under Ar atmosphere, TaCl5 powder was ball-milled to make its powder particle size less than 500 μm; HfC powder was ball-milled to make its powder particle size Dv50 about 5 μm.

[0080] (3) Place the graphite substrate into the CVD deposition furnace, close the furnace door, evacuate the reaction chamber to a vacuum below 200 Pa, raise the temperature to 1200℃, control the pressure at 3 kPa, stabilize for 20 min, introduce Ar, then introduce TaCl5, H2, Ar and CH4 into the CVD deposition furnace, deposit for 20 min, then open the HfC powder pipeline to deposit the HfC-TaC coating for 3 h. The molar ratio of TaCl5, CH4, H2 and Ar is 1:0.6:2:80. The molar ratio of HfC to TaCl5 is 1:6.

[0081] (4) After deposition, the coating is heat-treated at 1300℃ and 5kPa pressure for 3h to obtain the composite material.

[0082] The TaC coating has a thickness of 0.15 μm, the HfC-TaC coating has a thickness of 33 μm, and the average grain size of the HfC-TaC coating surface is 18 μm. In the composite coating, the Ta content is 42 at%, the Hf content is 8 at%, and the C content is 50 at%. The SEM and XRD images of the coating surface are shown below. Figure 1 and Figure 2 As shown.

[0083] Example 2

[0084] (1) In a plasma reaction chamber, the surface of the graphite sheet is subjected to plasma oxidation. The plasma gas is oxygen. After the plasma treatment is completed, the graphite sheet is washed with deionized water to remove plasma reaction residue, and then the graphite sheet is dried in a drying oven. The conditions for plasma oxidation include: a processing power of 130W and plasma discharge at a discharge frequency of 15MHz for 5 minutes.

[0085] After plasma oxidation, the surface of the graphite sheet contains C and O elements in the form of CC, C-OH, COC, and -COOH. The mass ratio of C to O elements is 11.27, and the content of CC is 79.2 wt%, the content of C-OH is 14.93 wt%, the content of COC is 2.02 wt%, and the content of -COOH is 3.85 wt%.

[0086] (2) Under Ar atmosphere, TaCl5 powder was ball-milled to make its powder particle size less than 500 μm; HfC powder was ball-milled to make its powder particle size Dv50 about 3 μm.

[0087] (3) Place the graphite substrate into the CVD deposition furnace, close the furnace door, evacuate the reaction chamber to a vacuum below 200 Pa, raise the temperature to 1100℃, control the pressure at 1 kPa, stabilize for 20 min, introduce Ar, then introduce TaCl5, H2, Ar and CH4 into the CVD deposition furnace, deposit for 10 min, then open the HfC powder pipeline to deposit the HfC-TaC coating for 2.5 h. The molar ratio of TaCl5, CH4, H2 and Ar is 1:0.8:3:60. The molar ratio of HfC to TaCl5 is 1:8.

[0088] (4) After deposition, the coating is heat-treated at 1150℃ and 4kPa pressure for 3.5h to obtain the composite material.

[0089] The TaC coating has a thickness of 0.1 μm, the HfC-TaC coating has a thickness of 25 μm, and the average grain size of the HfC-TaC coating surface is 12 μm. In the composite coating, the Ta content is 40 at%, the Hf content is 6 at%, and the C content is 54 at%.

[0090] Example 3

[0091] (1) In a plasma reaction chamber, the surface of the graphite sheet is subjected to plasma oxidation. The plasma gas is oxygen. After the plasma treatment is completed, the graphite sheet is washed with deionized water to remove plasma reaction residue, and then the graphite sheet is dried in a drying oven. The conditions for plasma oxidation include: a processing power of 170W and plasma discharge at a discharge frequency of 11MHz for 15min.

[0092] After plasma oxidation, the surface of the graphite sheet contains C and O elements in the form of CC, C-OH, COC, and -COOH. The mass ratio of C to O elements is 3.06, and the content of CC is 70.24 wt%, the content of C-OH is 10.54 wt%, the content of COC is 12.09 wt%, and the content of -COOH is 7.13 wt%.

[0093] (2) Under Ar atmosphere, TaCl5 powder was ball-milled to make its powder particle size less than 500 μm; HfC powder was ball-milled to make its powder particle size Dv50 about 7 μm.

[0094] (3) Place the graphite substrate into the CVD deposition furnace, close the furnace door, evacuate the reaction chamber to a vacuum below 200 Pa, raise the temperature to 1300℃, control the pressure at 5 kPa, stabilize for 20 min, introduce Ar, then introduce TaCl5, H2, Ar and CH4 into the CVD deposition furnace, deposit for 30 min, then open the HfC powder pipeline to deposit the HfC-TaC coating for 3.5 h. The molar ratio of TaCl5, CH4, H2 and Ar is 1:1:4:100. The molar ratio of HfC to TaCl5 is 1:10.

[0095] (4) After deposition, the furnace temperature is raised to 1450°C and the coating is heat-treated at 6 kPa pressure for 2.5 h to obtain the composite material.

[0096] The TaC coating has a thickness of 0.2 μm, the HfC-TaC coating has a thickness of 28 μm, and the average grain size of the HfC-TaC coating surface is 10 μm. In the composite coating, the content of Ta is 45 at%, the content of Hf is 10 at%, and the content of C is 45 at%.

[0097] Comparative Example 1

[0098] The procedure is performed according to the method described in Example 1, except that the graphite sheets are not subjected to plasma oxidation treatment.

[0099] Comparative Example 2

[0100] The procedure was performed according to the method described in Example 1, except that the graphite sheet was subjected to thermal oxidation instead of plasma oxidation. The oxidation conditions included heating the graphite to 600°C and oxidizing it for 10 minutes in an air atmosphere.

[0101] After thermal oxidation, the surface of the graphite sheet contains C and O elements in the form of CC, C-OH, COC, and -COOH. The mass ratio of C to O elements is 15, and the content of CC is 85wt%, the content of C-OH is 10wt%, the content of COC is 2wt%, and the content of -COOH is 1wt%.

[0102] Example 4

[0103] The procedure was performed according to the method described in Example 1, except that the plasma oxidation processing power was 100W.

[0104] After plasma oxidation, the surface of the graphite sheet contains C and O elements in the form of CC, C-OH, COC and -COOH. The mass ratio of C to O elements is 11.59, and the content of CC is 81 wt%, the content of C-OH is 16 wt%, the content of COC is 2 wt%, and the content of -COOH is 1 wt%.

[0105] Comparative Example 3

[0106] The operation is carried out according to the method described in Example 1, except that a TaC layer is not deposited on the surface of the graphite sheet after plasma oxidation treatment, but an HfC-TaC coating is directly deposited. That is, in step (3), the temperature is raised to 1200°C, the pressure is controlled at 3 kPa, Ar is introduced after stabilizing for 20 min, and then TaCl5, H2, Ar and CH4 are introduced into the CVD deposition furnace, while the HfC powder pipeline is turned on to deposit the HfC-TaC coating.

[0107] Comparative Example 4

[0108] The procedure was performed according to the method described in Example 1, except that HfCl4 was used instead of HfC when depositing the HfC-TaC coating. Specifically, in step (3), the temperature was raised to 1500℃, the pressure was controlled at 1 kPa, and Ar was introduced after stabilizing for 20 min. Then, TaCl5, H2, Ar and CH4 were introduced into the CVD deposition furnace. After deposition for 20 min, the HfCl4 pipeline was turned on to deposit the HfC-TaC coating for 5 h. After deposition, the coating was heat-treated at 1600℃ and 5 kPa for 3 h to obtain the composite material.

[0109] Example 5

[0110] The procedure was performed according to the method described in Example 1, except that TaCl5, H2, Ar and CH4 were introduced into the CVD deposition furnace, and after deposition for 40 minutes, the HfC powder pipeline was turned on to deposit an HfC-TaC coating.

[0111] Example 6

[0112] The procedure was performed according to the method described in Example 1, except that TaCl5, H2, Ar and CH4 were introduced into the CVD deposition furnace, and after 5 minutes of deposition, the HfC powder pipeline was turned on to deposit an HfC-TaC coating.

[0113] Example 7

[0114] The procedure was performed according to the method described in Example 1, except that in step (3), the temperature was raised to 1500℃, the pressure was controlled at 6 kPa, and Ar was introduced after stabilizing for 20 min. Then, TaCl5, H2, Ar, and CH4 were introduced into the CVD deposition furnace. After deposition for 30 min, the HfC powder pipeline was turned on to deposit an HfC-TaC coating for 5 h. After deposition, the coating was heat-treated at 1600℃ and 8 kPa for 3 h to obtain the composite material.

[0115] Example 8

[0116] The procedure was performed according to the method described in Example 1, except that in step (3), the temperature was raised to 800°C, the pressure was controlled at 1 kPa, and Ar was introduced after stabilizing for 20 minutes. Then, TaCl5, H2, Ar, and CH4 were introduced into the CVD deposition furnace. After deposition for 10 minutes, the HfC powder pipeline was turned on to deposit the HfC-TaC coating for 2 hours. After deposition, the coating was heat-treated at 900°C and 2 kPa for 3 hours to obtain the composite material.

[0117] Example 9

[0118] The procedure was performed according to the method described in Example 1, except that the molar ratio of HfC to TaCl5 was 1:12.

[0119] In the composite coating, the content of Ta is 53 at, the content of Hf is 3 at, and the content of C is 44 at.

[0120] Example 10

[0121] The procedure was performed according to the method described in Example 1, except that the molar ratio of HfC to TaCl5 was 1:3.

[0122] The composite coating contains 49 att of Ta, 4 att of Hf, and 47 att of C.

[0123] Example 11

[0124] The procedure was performed according to the method described in Example 1, except that the particle size Dv50 of HfC was 9 μm.

[0125] Example 12

[0126] The procedure was performed according to the method described in Example 1, except that the particle size Dv50 of HfC was 1.5 μm.

[0127] Example 13

[0128] The method described in Example 1 was followed, except that the molar ratio of TaCl5, CH4, H2, and Ar was 1:0.6:5:80. In the composite coating, the content of Ta was 51 at%, the content of Hf was 4 at%, and the content of C was 35 at%.

[0129] Example 14

[0130] The method described in Example 1 was followed, except that the molar ratio of TaCl5, CH4, H2, and Ar was 1:0.6:1:80. In the composite coating, the content of Ta was 38 at%, the content of Hf was 5 at%, and the content of C was 57 at%.

[0131] Comparative Example 5

[0132] The procedure was performed according to the method described in Example 1, except that no heat treatment was performed after deposition. In the composite coating, the content of Ta was 49 at%, the content of Hf was 4 at%, and the content of C was 45 at%.

[0133] Test case

[0134] The performance of the composite materials prepared in the examples and comparative examples was evaluated using the following methods.

[0135] (1) Evaluation of thermal shock resistance

[0136] The sample to be tested was heated to 2000℃ at a heating rate of 10℃ / min and held at that temperature for 1 hour. Then, it was purged with argon gas at a rate of 100L / min and air-cooled to 500±20℃. The sample surface was then observed for obvious cracks. If no cracks were observed, the sample was placed in a thermal shock furnace for further heating. If cracks appeared, the test was stopped. This process was repeated until cracks appeared. The result was expressed as the number of cycles at which cracks appeared. For example, a cycle count of 45 indicates that cracking occurred after 45 cycles. The results are shown in Table 1.

[0137] (2) Fracture toughness evaluation

[0138] According to the indentation method, the polished composite material sample was tested using a Vickers hardness tester with a load of 100gf (≈0.98N). The fracture toughness was tested, and the test results are shown in Table 1.

[0139] Table 1

[0140]

[0141]

[0142] A comparison of Examples 1-4 with Comparative Examples 1 and 2 shows that plasma oxidation treatment of graphite sheets can significantly improve the thermal shock resistance and fracture toughness of the composite material, and under preferred treatment conditions, the performance of the composite material can be further improved.

[0143] The comparison of the examples and Comparative Examples 3 and 4 shows that the technical solution of the present invention, by first depositing a thin layer of TaC and then adding HfC powder during the deposition of the TaC layer, can significantly improve the thermal shock resistance and fracture toughness of the composite material. In particular, the first deposition of the thin TaC layer makes a greater contribution to the improvement of the composite material's performance. Data from Comparative Example 5 shows that without heat treatment, the thermal shock resistance of the material decreases significantly, which is related to the fact that heat treatment can eliminate some stress.

[0144] A comparison of Example 1 with Examples 5-14 shows that the preferred deposition conditions in this invention are beneficial for improving the performance of the composite material.

[0145] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite material, characterized in that, The method includes the following steps: (1) Plasma oxidation treatment is performed on the surface of the carbon-based substrate to obtain the oxidized substrate; The conditions for plasma oxidation treatment include: power of 120-180W, discharge frequency of 10-15 MHz, and time of 5-20min; (2) In the presence of a first gas system for depositing tantalum carbide, a first deposition is performed on the surface of the oxidized substrate to obtain a first preform containing a tantalum carbide coating; the thickness of the tantalum carbide coating is 0.1-0.2 μm. (3) A second deposition is performed on the surface of the first preform in the presence of hafnium carbide particles and a second gas system for depositing tantalum carbide to obtain a second preform containing a hafnium carbide-tantalum carbide coating; the thickness of the hafnium carbide-tantalum carbide coating is 20-40 μm; The first gas system and the second gas system each independently include a Ta source, a C source, a reducing gas, and a diluting gas; In the first gas system and the second gas system, the molar ratios of tantalum, carbon, reducing gas, and diluting gas are each independently 1:0.5-1:0.5-5:50-100; In the second deposition process, the molar ratio of hafnium to tantalum is 1:5-10; the particle size Dv50 of hafnium carbide is 2-8 μm. The conditions for the first deposition include: a deposition temperature of 1050-1300℃, a pressure of 1kPa-5kPa, and a time of 10-30min; The conditions for the second deposition include: a deposition temperature of 1050-1300℃, a pressure of 1kPa-5kPa, and a time of 2h-4h; (4) The second preform is heat-treated to obtain the composite material; The heat treatment conditions include: a temperature of 1100-1500℃, a pressure of 3kPa-7kPa, and a time of 2h-4h.

2. The method for preparing the composite material according to claim 1, characterized in that, The Ta source includes at least one of TaF5, TaCl5 and TaBr5; The C source includes at least one of CH4, C2H4, C2H6, C3H6, and C3H8; The reducing gas is H2; The diluent gas is Ar or He.

3. The method for preparing the composite material according to claim 1, characterized in that, The first and second deposition methods are each independently CVD deposition.

4. A composite material, characterized in that, The composite material is prepared by the method described in any one of claims 1-3.

5. The composite material according to claim 4, characterized in that, The composite material includes a substrate and a composite coating on the surface of the substrate, wherein the composite coating includes a TaC coating and an HfC-TaC coating; The average grain size of the HfC-TaC coating surface is 15-40 μm; In the composite coating, the content of Ta element is 36-46 at, the content of Hf element is 5-12 at, and the content of C element is 40-55 at.

6. The use of the composite material according to claim 4 or 5 as a high-temperature resistant material.

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