Preparation method of tantalum-based ceramic and silicon carbide composite thermal protection coating resistant to ultrahigh-temperature oxidation ablation

Abstract

The invention provides a preparation method of an ultrahigh-temperature oxidation ablation resistant tantalum-based ceramic and silicon carbide composite thermal protection coating, which comprises the following steps: (1) mixing a polymer binder and a solvent to form a solution, and carrying out ball-milling mixing on the solution, a tantalum-containing compound, silicon carbide, silicon and other components to prepare precursor slurry; (2) uniformly coating the surface of a carbon substrate with the slurry obtained in the step (1) by a dip-coating method, and drying; (3) realizing curing and pyrolysis of the coating through segmented heat treatment; and (4) the coating is subjected to vacuum siliconizing treatment, and the composite thermal protection coating is obtained. According to the tantalum-based ceramic and silicon carbide composite thermal protection coating prepared through the method, the ultrahigh-temperature oxidation resistance, ablation resistance, thermal shock resistance and heat insulation performance of the coating are remarkably improved. After the coating is ablated for 2400s under oxyacetylene flame at the temperature of 1650 DEG C, the integrity and excellent thermal protection effect of the coating can still be kept.

Description

Technical Field

[0001] The invention relates to the field of thermal protection materials, and in particular to a method for preparing a tantalum-based ceramic and silicon carbide composite thermal protection coating resistant to ultra-high temperature oxidation and ablation. Background Art

[0002] Hypersonic aircraft have great development potential in intelligence gathering, communication and transportation, and play an important strategic role in military, political and economic fields. When the aircraft is in operation, it will interact violently with the airflow, causing the corresponding hot end components to be subjected to huge shear forces and heat up rapidly. The engine lip cover, nose and tail tip can reach a temperature of up to 3000℃ under aerodynamic heating, which is the main threat to the failure of hot end components and the safety of aircraft service.

[0003] Carbon materials have excellent properties such as high melting point and low density, and they still maintain excellent mechanical properties at ultra-high temperatures. They are an extremely ideal high-temperature structural material. However, they are easily oxidized and easily ablated, which has a severe impact and damage on their structure and performance. Preparing a thermal protective coating with anti-oxidation, anti-ablation and heat insulation properties on the surface of carbon materials can reduce the ambient temperature and block direct contact with oxygen, which can achieve effective thermal protection for carbon materials.

[0004] Tantalum-based ceramics have high melting points, oxidation resistance, ablation resistance, and thermal shock resistance. They can maintain good physical properties in ultra-high temperature environments and can effectively prevent oxidation, decomposition, or shedding of materials, thereby improving the durability of thermal protective coatings. In addition, they have good thermal radiation absorption and emission properties, can play a heat-insulating role, and are extremely excellent thermal protective materials. However, they still face some application challenges, such as coating processing and preparation, performance optimization, and the development of multifunctional composite materials.

[0005] Chinese patent CN116332678A discloses a method for preparing a tantalum carbide coating on the surface of a carbon material. The method is to activate the carbon material on the surface, and then generate a silicon carbide nanowire transition layer and a tantalum carbide coating on the surface, which can effectively improve the high-temperature corrosion resistance of the carbon material. However, there are still differences in thermal expansion coefficients between the layered structures prepared by this method, and the preparation process requires multiple slurry coating and sintering, and the process route is relatively complicated. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating that is resistant to ultra-high temperature oxidation and ablation, which realizes the one-time forming of the tantalum-based ceramic / silicon carbide composite dual phase in the coating, and effectively improves the cracking and failure problems of the coating caused by differences in thermal expansion coefficients and the like. The coating reduces the temperature of the environment in which the carbon material is located and blocks its direct contact with oxygen, thereby achieving thermal protection for it and ensuring its excellent high-temperature performance. The thermal protective coating prepared by the present invention has excellent thermal protection properties of ultra-high temperature oxidation resistance, ablation resistance, thermal shock resistance, and heat insulation, and the process route is simple and easy to operate.

[0007] A method for preparing a tantalum-based ceramic and silicon carbide composite thermal protection coating resistant to ultra-high temperature oxidation and ablation, comprising the following steps:

[0008] (1) Preparing a precursor slurry: dissolving a polymer binder in a solvent, stirring the solution on a magnetic stirrer for 2 to 4 hours, and then ball-milling the tantalum-containing compound, silicon carbide, and silicon with the solution to obtain a precursor slurry with a certain viscosity;

[0009] (2) Pulling sample preparation: The precursor slurry obtained in step (1) is uniformly coated on the surface of the carbon substrate by an immersion pulling method to obtain a precursor coating;

[0010] (3) Heat treatment: the precursor coating obtained in step (2) is placed in a muffle furnace at 50°C to 300°C for 30 min to 150 min to ensure that the polymer binder is fully cured; then placed in a tubular furnace at 800°C to 1200°C with an inert gas for 60 min to 240 min to pyrolyze and carbonize the polymer substance inside the coating, and cooled to obtain a pyrolyzed coating;

[0011] (4) The pyrolysis coating obtained in step (3) is placed in a siliconizing device, and then placed in a vacuum induction heating furnace at 1500°C to 2100°C for siliconizing treatment. The tantalum-based coating is pinned to the substrate by diffusion and penetration of silicon to form a tantalum-based ceramic / silicon carbide composite dual phase, thereby obtaining a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation.

[0012] Furthermore, step (2) specifically includes: immersing the carbon substrate in the precursor slurry, controlling its rising speed to be 50 μm / s to 500 μm / s, and drying and shaping it at room temperature after it completely floats out of the liquid surface, and the drying time is 1 to 3 hours.

[0013] Furthermore, the polymer binder includes one or a mixture of phenolic resin, epoxy resin, polyester resin, etc.

[0014] Furthermore, the solvent includes one or a mixture of methanol, ethanol, propanol, acetone, and deionized water.

[0015] Furthermore, the weight ratio of the polymer binder to the solvent is 1 to 10:10.

[0016] Furthermore, the tantalum-containing compound includes one or a mixture of several rare earth tantalates such as yttrium tantalate, lanthanum tantalate, samarium tantalate, gadolinium tantalate, terbium tantalate, dysprosium tantalate, holmium tantalate, erbium tantalate, and thulium tantalate.

[0017] Furthermore, during the ball milling process in step (1), the mass fraction of the tantalum-containing compound is 15-70%, the mass fraction of silicon carbide is 15-70%, the mass fraction of silicon is 15-70%, and the weight ratio of the total solid phase to the polymer binder solution is 1:1-6.

[0018] Furthermore, the rotation speed of the ball mill in step (1) is 800-2000 rpm / min, and the duration of the ball milling is 10-30 min.

[0019] Furthermore, the carbon substrate is one of graphite, C / C composite material, C / Cf composite material, carbon fiber fabric, carbon fiber resin-based composite material, and glassy carbon.

[0020] Furthermore, the inert atmosphere of the heat treatment in step (3) is one of argon, nitrogen, helium and neon.

[0021] The technical effects of the present invention are embodied in:

[0022] 1. The present invention provides a new idea for preparing thermal barrier coatings. By designing a composite structure of tantalum-based ceramics and silicon carbide, the resulting composite thermal barrier coating has excellent thermal barrier properties of ultra-high temperature anti-oxidation, anti-ablation, thermal shock resistance and heat insulation. After the coating is ablated for 2400s under an oxyacetylene flame at 1650°C, it can still maintain the integrity and thermal protection effect of the coating.

[0023] 2. The present invention uses the immersion and pulling technology combined with the siliconizing method to prepare the thermal barrier coating, which can stably control the preparation process parameters, and the process is simple, low-cost, can be applied to the surface of complex parts, and has strong repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to an embodiment of the present invention;

[0025] Figure 2 is a SEM cross-sectional photograph of the composite coating of Example 1;

[0026] Figure 3 is a SEM cross-sectional photograph of the composite coating of Example 2;

[0027] Figure 4 is a SEM cross-sectional photograph of the composite coating of Example 3;

[0028] Figure 5 This is a SEM surface photograph of the tantalum-based ceramic and silicon carbide composite thermal protection coating obtained in the present invention;

[0029] Figure 6 The graph is a temperature curve of the ultra-high temperature ablation surface and back side of the tantalum-based ceramic and silicon carbide composite thermal protection coating obtained in the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Embodiment 1:

[0032] like Figure 1 As shown, first, phenolic resin was dissolved in ethanol at a mass ratio of 1:10, and stirred at 600 rpm / min for 6 hours on a magnetic stirrer to form a uniform solution. A mixed powder of yttrium tantalate (50wt.%), silicon carbide (30wt.%), and silicon (20wt.%) was added, and the mixture was mixed at a weight ratio of 1:4 between the solid phase material and the binder solution, and ball milled in a ball mill at 1000 rpm / min for 40 minutes to obtain a precursor slurry with appropriate viscosity. Then, Φ20mm×5mm graphite was selected as the carbon substrate, and the graphite substrate was immersed in the precursor slurry. The immersion pulling method was used to control the rising speed to 300μm / s until it completely floated out of the liquid surface, and then dried at room temperature for 2 hours to fix the shape, and the precursor coating was obtained. After that, the sample was placed in a muffle furnace and kept at 120°C for 90 minutes to fully solidify the phenolic resin, and then transferred to a tubular furnace with argon gas, kept at 800°C for 90 minutes to complete the pyrolysis and carbonization of the polymer inside the coating and cooled to room temperature. Finally, the sample was placed in a self-made siliconizing device and kept at 2000°C for 60 minutes in a vacuum induction heating furnace for siliconizing treatment. After cooling to room temperature, a tantalum-based ceramic and silicon carbide composite thermal protection coating was finally obtained.

[0033] Embodiment 2:

[0034] like Figure 1As shown, first, phenolic resin was dissolved in ethanol at a mass ratio of 2:10, and stirred at 600 rpm / min for 6 hours on a magnetic stirrer to form a uniform solution. Add mixed powders of yttrium tantalate (50wt.%), silicon carbide (30wt.%), and silicon (20wt.%), and mix them in a weight ratio of 1:4 between the solid phase and the binder solution, and ball milled in a ball mill at 1000 rpm / min for 40 minutes to obtain a precursor slurry with appropriate viscosity. Then, Φ20mm×5mm graphite was selected as the carbon substrate, and the graphite substrate was immersed in the precursor slurry. The immersion and pulling method was used to control the rising speed to 300μm / s until it completely floated out of the liquid surface, and then dried at room temperature for 2 hours to fix the shape, and the precursor coating was obtained. After that, the sample was placed in a muffle furnace and kept at 120°C for 90 minutes to fully solidify the phenolic resin, and then transferred to a tubular furnace with argon gas, kept at 800°C for 90 minutes to complete the pyrolysis and carbonization of the polymer inside the coating and cooled to room temperature. Finally, the sample was placed in a self-made siliconizing device and kept at 2000°C for 60 minutes in a vacuum induction heating furnace for siliconizing treatment. After cooling to room temperature, a tantalum-based ceramic and silicon carbide composite thermal protection coating was finally obtained.

[0035] Embodiment 3:

[0036] like Figure 1 As shown, first, phenolic resin was dissolved in ethanol at a mass ratio of 4:10, and stirred at 600 rpm / min for 6 hours on a magnetic stirrer to form a uniform solution. A mixed powder of yttrium tantalate (50wt.%), silicon carbide (30wt.%), and silicon (20wt.%) was added, and mixed in a weight ratio of 1:4 between the solid phase and the binder solution, and ball milled in a ball mill at 1000 rpm / min for 40 minutes to obtain a precursor slurry with appropriate viscosity. Then, Φ20mm×5mm graphite was selected as a carbon substrate, and the graphite substrate was immersed in the precursor slurry. The immersion and pulling method was used to control the rising speed to 300μm / s until it completely floated out of the liquid surface, and then dried at room temperature for 2 hours to fix the shape, and a precursor coating was obtained. After that, the sample was placed in a muffle furnace and kept at 120°C for 90 minutes to fully solidify the phenolic resin, and then transferred to a tubular furnace with argon gas, kept at 800°C for 90 minutes to complete the pyrolysis and carbonization of the polymer inside the coating and cooled to room temperature. Finally, the sample was placed in a self-made siliconizing device and kept at 2000°C for 60 minutes in a vacuum induction heating furnace for siliconizing treatment. After cooling to room temperature, a tantalum-based ceramic and silicon carbide composite thermal protection coating was finally obtained.

[0037] Figure 2-4The SEM cross-sectional images of the composite thermal protection coatings of different thicknesses obtained with different addition amounts of phenolic resin in the examples are shown. It can be seen from the figure that the obtained coatings are well bonded to the carbon substrate, and the thickness of the coatings can reach 96 μm and is evenly distributed.

[0038] Figure 5 This is a SEM surface image of the tantalum-based ceramic and silicon carbide composite thermal protection coating obtained in the present invention. As can be seen from the image, the coating surface is flat, without any cracks or holes, and the surface quality is good and uniform.

[0039] Figure 6 This is a temperature curve of the ultra-high temperature ablation surface and back of the tantalum-based ceramic and silicon carbide composite thermal protection coating obtained in the present invention. As can be seen from the figure, when the surface temperature is as high as 1650°C, the sample can withstand 2400s and still maintain good thermal insulation, and the back temperature is only 850°C. This shows the excellent anti-ablation, anti-oxidation and thermal insulation properties of the composite coating.

[0040] The tantalum-based ceramic and silicon carbide composite thermal protection coating prepared by the present invention significantly improves the ultra-high temperature oxidation resistance, ablation resistance, thermal shock resistance and thermal insulation performance of the coating. After the coating is ablated for 2400 seconds under an oxyacetylene flame at up to 1650°C, it can still maintain the integrity of the coating and the excellent thermal protection effect. The method of the present invention has simple process, low cost, is suitable for the surface of complex parts, and has good repeatability and practicality.

[0041] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation, characterized in that: The steps include: (1) Preparing a precursor slurry: dissolving a polymer binder in a solvent, stirring the solution on a magnetic stirrer for 2 to 4 hours, and then ball-milling the tantalum-containing compound, silicon carbide, and silicon with the solution to obtain a precursor slurry with a certain viscosity; (2) Pulling sample preparation: using the immersion pulling method to evenly apply the precursor slurry obtained in step (1) on the surface of the carbon substrate to obtain a precursor coating; (3) Heat treatment: the precursor coating obtained in step (2) is placed in a muffle furnace at 50°C to 300°C for 30 min to 150 min to ensure that the polymer binder is fully cured; then placed in a tubular furnace at 800°C to 1200°C with an inert gas for 60 min to 240 min to pyrolyze and carbonize the polymer substance inside the coating, and cooled to obtain a pyrolyzed coating; (4) The pyrolysis coating obtained in step (3) is placed in a siliconizing device, and then placed in a vacuum induction heating furnace at 1500°C to 2100°C for siliconizing treatment. The tantalum-based coating is pinned to the substrate by diffusion and penetration of silicon to form a tantalum-based ceramic / silicon carbide composite dual phase, thereby obtaining a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation.

2. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: Step (2) specifically includes: immersing the carbon substrate in the precursor slurry, controlling its rising speed to be 50 μm / s to 500 μm / s, and drying and shaping it at room temperature after it completely floats out of the liquid surface, and the drying time is 1 to 3 hours.

3. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The polymer binder includes one or a mixture of phenolic resin, epoxy resin, polyester resin, etc.

4. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The solvent includes one or a mixture of methanol, ethanol, propanol, acetone, and deionized water.

5. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The weight ratio of the polymer binder to the solvent is 1 to 10:

10.

6. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The tantalum-containing compound includes one or a mixture of rare earth tantalates such as yttrium tantalate, lanthanum tantalate, samarium tantalate, gadolinium tantalate, terbium tantalate, dysprosium tantalate, holmium tantalate, erbium tantalate, and thulium tantalate.

7. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: During the ball milling process of step (1), the mass fraction of the tantalum-containing compound is 15-70%, the mass fraction of silicon carbide is 15-70%, the mass fraction of silicon is 15-70%, and the weight ratio of the total solid phase to the polymer binder solution is 1:1-6.

8. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The rotation speed of the ball mill in step (1) is 800-2000 rpm / min, and the duration of the ball mill is 10-30 min.

9. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The carbon substrate is one of graphite, C / C composite material, C / Cf composite material, carbon fiber fabric, carbon fiber resin-based composite material, and glassy carbon.

10. The method for preparing a tantalum-based ceramic and silicon carbide composite thermal protective coating resistant to ultra-high temperature oxidation and ablation according to claim 1, characterized in that: The inert atmosphere of the heat treatment in step (3) is one of argon, nitrogen, helium and neon.

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