A high bonding strength, anti-oxidation and ablation composite coating for ceramic-based composite materials and a preparation method thereof

Abstract

The present invention relates to a high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials and a preparation method thereof. The high-bonding-strength, anti-oxidation and ablation composite coating comprises, from the ceramic-based composite material outward, a layer-shell-coated short-cut carbon fiber reinforced ultra-high-temperature ceramic bottom coating and a layer-shell-coated short-cut silicon carbide fiber reinforced ultra-high-temperature ceramic surface coating. The method comprises: pre-treating the ceramic-based composite material; sequentially preparing a layer-shell-coated short-cut carbon fiber reinforced ultra-high-temperature ceramic bottom coating and a layer-shell-coated short-cut silicon carbide fiber reinforced ultra-high-temperature ceramic surface coating on the surface of the pretreated ceramic-based composite material by a low-pressure plasma spraying method to prepare a high-bonding-strength, anti-oxidation and ablation composite coating. The composite coating prepared by the present invention has low porosity, high bonding strength, and excellent resistance to high-temperature oxidation and ablation. The present invention can prepare a high-temperature protective coating for ceramic-based composite materials with higher efficiency and lower cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of protective coatings, and in particular relates to a high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials and a preparation method thereof. Background Art

[0002] Carbon fiber-reinforced ceramic matrix composites (CMCs) combine the high strength and oxidation resistance of ceramics with the excellent mechanical properties of carbon fiber, and have broad application prospects in the aerospace field. However, the increasing operating temperatures of CMCs, coupled with the need for long-term service in high-temperature, oxidative, and ablation environments, pose challenges for CMCs, such as the susceptibility of carbon fiber to oxidation at higher temperatures and its poor ablation resistance. Relying solely on the CMC matrix alone is no longer sufficient to meet these performance requirements.

[0003] To improve the high-temperature oxidation and ablation resistance of ceramic-based composites, ceramic coatings are often applied to their surfaces to isolate them from air. While traditional coating preparation methods, such as chemical vapor deposition, brush coating, and plasma spraying, each have their advantages, they generally suffer from weak bonding strength between the coating and the substrate. This results in the coating easily detaching during thermal shock, rendering it ineffective in protecting the substrate.

[0004] Chinese patent application CN201610172208.0 discloses a ceramic fiber / whisker-reinforced composite thermal barrier coating and its preparation method. This method uses plasma spraying or laser cladding to prepare a ceramic fiber / whisker-reinforced oxide coating on the surface of an alloy substrate. Although ceramic fibers / whiskers can improve the fracture toughness of the oxide coating, the thermal expansion coefficient of the oxide coating differs significantly from that of the carbon fiber-reinforced ceramic matrix composite substrate of the present invention. This results in a significant thermal mismatch stress between the coating and the ceramic matrix composite substrate, reducing the coating's bonding strength and thermal shock life, thereby reducing the coating's protective effectiveness.

[0005] Chinese patent application CN202410645601.1 discloses a method for preparing a TaC ceramic coating. The method first grows silicon carbide nanowires on the surface of a substrate by chemical vapor deposition, and then deposits a TaC ceramic coating on the surface of the substrate by chemical vapor deposition to form a TaC coating toughened by silicon carbide nanowires. However, this method has certain limitations. Repeated heating and cooling processes will cause cracks in the TaC coating, affecting the coating quality. In addition, the chemical vapor deposition method has low efficiency and high cost in preparing the coating.

[0006] Chinese patent application CN202210003897.8 discloses a thermal protective coating prepared using a silicone rubber matrix, hollow ceramic powder, and an auxiliary reinforcing agent, and its preparation method. Because the silicone rubber matrix accelerates aging, cracking, and powdering at high temperatures, the slurry in this method is not suitable for preparing the coating using a thermal spraying method. Furthermore, the coating primarily relies on the hollow ceramic powder for thermal protection. Under conditions of higher temperatures and higher-speed airflow, the bonding strength between the hollow ceramic powders is insufficient, the coating is prone to peeling, and the coating has poor ablation resistance, making it unsuitable for ablation environments exceeding 1800°C.

[0007] Therefore, there is an urgent need to provide a high-bonding-strength anti-oxidation and ablation coating suitable for ceramic-based composite materials and a preparation method thereof, so as to significantly improve the anti-oxidation and ablation performance and service life of ceramic-based composite materials in extreme environments. Summary of the Invention

[0008] To address one or more technical problems existing in the prior art, the present invention provides a high-bonding-strength, oxidation-resistant, and ablation-resistant composite coating for ceramic-based composite materials and a method for preparing the same. The high-bonding-strength, oxidation-resistant, and ablation-resistant composite coating produced by the present invention exhibits low porosity, high bonding strength, and excellent resistance to high-temperature oxidation and ablation. The present invention enables the efficient and cost-effective production of high-temperature protective coatings for ceramic-based composite materials.

[0009] In the first aspect, the present invention provides a high-bonding-strength, anti-oxidation-ablation composite coating for ceramic-based composite materials, wherein the high-bonding-strength, anti-oxidation-ablation composite coating comprises, from the ceramic-based composite material outward, a layer-shell-coated ultra-high-temperature ceramic bottom coating reinforced with chopped carbon fibers and a layer-shell-coated ultra-high-temperature ceramic top coating reinforced with chopped silicon carbide fibers.

[0010] In a second aspect, the present invention provides a method for preparing the high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials according to the first aspect of the present invention, the method comprising the following steps:

[0011] (1) grinding, cleaning and drying the ceramic-based composite material to obtain a pretreated ceramic-based composite material;

[0012] (2) A layer-shell-coated short-cut carbon fiber reinforced ultra-high temperature ceramic bottom layer coating and a layer-shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic top layer coating are sequentially prepared on the surface of the pretreated ceramic-based composite material by a low-pressure plasma spraying method, thereby preparing the high bonding strength and anti-oxidation and ablation composite coating on the surface of the ceramic-based composite material.

[0013] In a third aspect, the present invention provides a high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials, which is prepared by the preparation method described in the second aspect of the present invention.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] (1) Although the prior art, such as Chinese patent application CN201610172208.0, discloses a fiber-reinforced oxide coating suitable for alloy surfaces and its preparation method, the coating has a single structure, limited functions, and relatively poor bonding strength, and the coating is not suitable for ceramic-based composite substrates with higher operating temperatures; the present invention designs an anti-oxidation and ablation composite coating with high bonding strength, wherein the bottom layer of the composite coating is an ultra-high temperature ceramic coating reinforced with chopped carbon fibers coated with a shell. The role of the chopped carbon fibers coated with the shell in the coating is to effectively improve the fracture toughness of the coating, reduce the thermal expansion coefficient of the coating, and deflect the crack propagation path in the coating. Therefore, the bottom layer is designed to alleviate the mismatch in thermal expansion coefficient between the coating and the ceramic-based composite substrate, reduce the thermal mismatch stress between the coating and the substrate, and improve the bonding strength of the coating. , thereby extending the thermal shock life of the coating; the surface layer of the composite coating is an ultra-high temperature ceramic coating reinforced with chopped silicon carbide fibers coated with a shell. The role of the chopped silicon carbide fibers in the coating is to improve the fracture toughness of the coating, while its oxidation product, silicon oxide, can enhance the self-healing effect of the coating under high-temperature oxidation and ablation conditions. Therefore, this surface layer is designed to improve the coating's resistance to high-temperature oxidation and high-temperature ablation. In addition, the present invention found that the interface between the shell and the chopped fibers (chopped carbon fibers and chopped silicon carbide fibers) deflects the crack propagation path, which can further avoid peeling of the coating under ablation environment, and is beneficial to enhancing the bonding strength between the coating and the substrate, and improving the high-temperature ablation resistance and oxidation resistance of the composite coating. The composite coating designed by the present invention can give full play to the synergistic effect, further ensuring that the coating has both high bonding strength and excellent anti-oxidation and ablation thermal properties.

[0016] (2) The prior art, such as Chinese patent application CN202410645601.1, discloses a method for preparing a TaC ceramic coating, but the preparation cost is relatively high and the coating preparation efficiency is low. The present invention prepares the high bonding strength and anti-oxidation and ablation composite coating for the first time by a low-pressure plasma spraying method. In the low-pressure plasma spraying preparation method, under a low-pressure and inert gas environment, the low-pressure plasma spraying method has the advantages of high spraying power, high jet temperature and fast speed, and has the advantages of high deposition efficiency and low cost. In addition, the spraying powder is melted more fully under the action of the high-energy plasma beam, and the coating porosity is lower, thereby avoiding the generation of internal defects in the coating and reducing the risk of the coating peeling along the defect position in a high-temperature ablation environment. At the same time, it also reduces the possibility of failure along the interface between the coating and the ceramic-based composite material substrate, and more effectively ensures that the composite coating has high bonding strength and excellent anti-oxidation and ablation performance. The method of the present invention has the advantages of high deposition efficiency, low cost and high coating density, and can realize the integrated preparation of the composite coating.

[0017] (3) The prior art, for example, Chinese patent application CN202210003897.8 discloses a method for preparing a thermal protective coating on a substrate using a slurry prepared using a silicone rubber matrix, hollow ceramic powder and an auxiliary reinforcing agent; however, due to the high viscosity of the silicone rubber matrix, it will accelerate aging, cracking and powdering at high temperatures. Therefore, the slurry in this method is not suitable for preparing a coating with high bonding strength by a thermal spraying method, and the coating prepared by the brushing method suitable for this slurry has a low bonding strength; in addition, the coating mainly relies on hollow ceramic powder to provide thermal protection. In a more severe high-temperature erosion environment, the erosion resistance of hollow ceramic powder is much lower than that of solid ceramic powder. Therefore, the coating of this method is very easy to peel off under higher temperature and more severe erosion environment, and the coating has poor ablation resistance; compared with this, the present invention uses a spray granulation powder that is more suitable for spraying for low-pressure plasma spraying, the coating has high bonding strength, the obtained coating is denser, and has better resistance to high-temperature erosion, and can provide excellent protection in a more severe high-temperature erosion environment.

[0018] Figures in the specification

[0019] The drawings of the present invention are provided for illustrative purposes only, and the proportions and sizes of the layers in the drawings may not necessarily be consistent with the actual product.

[0020] Figure 1 Schematic diagram of the structure of the high bonding strength, anti-oxidation and ablation composite coating prepared on the surface of the ceramic-based composite material in some specific embodiments of the present invention;

[0021] In the figure: 1: Ceramic matrix composite material; 2: Ultra-high temperature ceramic base coating reinforced by chopped carbon fiber coated with a shell; 3: Ultra-high temperature ceramic surface coating reinforced by chopped silicon carbide fiber coated with a shell. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] In a first aspect, the present invention provides a high bonding strength anti-oxidation ablation composite coating for ceramic matrix composite materials (abbreviated as high bonding strength anti-oxidation ablation composite coating), for example, Figure 1As shown; the high bonding strength, anti-oxidation and ablation composite coating includes, from the ceramic-based composite material (ceramic-based composite material matrix) 1 to the outside, a layer-shell-coated short-cut carbon fiber reinforced ultra-high temperature ceramic bottom coating (abbreviated as bottom coating) 2 and a layer-shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic surface coating (abbreviated as surface coating) 3.

[0024] The present invention takes into account the large difference in thermal expansion coefficients between ultra-high temperature ceramics and ceramic-based composites. In the prior art, ultra-high temperature ceramic coatings prepared on the surface of ceramic-based composites all prematurely peel and fail at the coating / ceramic-based composite interface during service due to the large difference in thermal expansion coefficients. However, the thermal expansion coefficients of carbon fibers are similar to those of ultra-high temperature ceramic-based composites. Based on this, the present invention designs an ultra-high temperature ceramic coating reinforced with chopped carbon fibers coated with a shell as a base layer. The shell-coated chopped carbon fibers can improve the fracture toughness of the ultra-high temperature ceramic coating while mitigating the thermal expansion coefficient between the ultra-high temperature ceramic coating and the ceramic-based composite substrate, reducing the thermal mismatch stress at the interface between the ultra-high temperature ceramic coating and the ceramic-based composite, effectively preventing premature peeling of the coating / ceramic-based composite interface, and effectively improving the bonding strength between the coating and the ceramic-based composite substrate. In addition, the present invention uses shell-coated chopped carbon fibers instead of directly using chopped carbon fibers to reinforce the ultra-high temperature ceramic coating. This is because the present invention has discovered that the weak interface between the shell and the chopped carbon fibers can deflect cracks in the coating, further enhancing the bonding strength between the coating and the substrate. In addition, in order to further improve the high-temperature oxidation and ablation resistance of the ultra-high temperature ceramic coating, the present invention uses a shell-coated chopped silicon carbide fiber reinforced ultra-high temperature ceramic coating as the surface layer. The present invention found that while the shell-coated chopped silicon carbide fiber improves the fracture toughness of the ultra-high temperature ceramic material, the silicon oxide formed by its oxidation is liquid or semi-liquid at high temperature. This fluidity enables it to fill cracks or holes in the coating, further improving its high-temperature oxidation and ablation resistance. The interface between the shell and the chopped silicon carbide fiber can also deflect the crack expansion path, which can further avoid peeling of the coating in an ablation environment. Compared with directly using chopped silicon carbide fibers for reinforcement, it is more conducive to significantly improving the high-temperature ablation resistance and oxidation resistance of the composite coating.

[0025] According to some preferred embodiments, the shell material in the shell-coated chopped carbon fiber and / or the shell-coated chopped silicon carbide fiber is one or more of pyrolytic carbon (PyC), silicon carbide (SiC) and boron nitride (BN); of course, in the present invention, the shell material may not be limited to one or more of pyrolytic carbon (PyC), silicon carbide (SiC) and boron nitride (BN); in the present invention, the shell coating the chopped carbon fiber and the chopped silicon carbide fiber is prepared, for example, by chemical vapor deposition (CVD), and the thickness of the shell is, for example, 100 to 500 nm (for example, 100, 150, 200, 250, 300, 350, 400, 450 or 500 nm).

[0026] According to some preferred embodiments, the preparation of the shell-coated chopped carbon fiber is as follows: a shell with a thickness of 100 to 500 nm is deposited on the surface of the carbon fiber by chemical vapor deposition to obtain a shell-coated carbon fiber, and then the shell-coated carbon fiber is cut; the preparation of the shell-coated chopped silicon carbide fiber is as follows: a shell with a thickness of 100 to 500 nm is deposited on the surface of the silicon carbide fiber by chemical vapor deposition to obtain a shell-coated silicon carbide fiber, and then the shell-coated silicon carbide fiber is cut; in the present invention, for example, mechanical or water jet cutting equipment can be used to cut the shell-coated carbon fiber and the shell-coated silicon carbide fiber; the present invention does not specifically limit the process conditions for preparing the shell by chemical vapor deposition, and those skilled in the art can select as needed to achieve a shell that can achieve the target thickness.

[0027] According to some preferred embodiments, the shell-coated chopped carbon fiber and / or the shell-coated chopped silicon carbide fiber has a length of 1 μm to 10 μm (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 μm) and a diameter of 0.2 μm to 2 μm (for example, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8 or 2 μm).

[0028] According to some preferred embodiments, the ultra-high temperature ceramic in the ultra-high temperature ceramic base coating and / or the ultra-high temperature ceramic surface coating is one or more of high melting point carbides, borides and nitrides; preferably, the carbide is one or more of silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide and niobium carbide, the boride is one or more of zirconium boride, hafnium boride, tantalum boride, titanium boride and niobium boride, and the nitride is one or more of zirconium nitride, hafnium nitride, tantalum nitride, titanium nitride and niobium nitride.

[0029] According to some preferred embodiments, the shell-coated chopped carbon fiber reinforced ultra-high temperature ceramic bottom layer coating and the shell-coated chopped silicon carbide fiber reinforced ultra-high temperature ceramic surface layer coating are respectively formed on the surface of the ceramic-based composite material by low-pressure plasma spraying using shell-coated chopped carbon fiber reinforced ultra-high temperature ceramic powder and shell-coated chopped silicon carbide fiber reinforced ultra-high temperature ceramic powder as spraying materials; the shell-coated chopped carbon fiber reinforced ultra-high temperature ceramic powder is composited by shell-coated chopped carbon fiber and ultra-high temperature ceramic powder by spray granulation; The shell-coated chopped silicon carbide fiber reinforced ultra-high temperature ceramic powder is formed by spray granulation of shell-coated chopped silicon carbide fibers and ultra-high temperature ceramic powder; the present invention does not specifically limit the spray granulation method, and those skilled in the art can make a conventional selection; in the present invention, the shell-coated chopped carbon fibers and shell-coated chopped silicon carbide fibers are respectively compounded with ultra-high temperature ceramic powder by a spray granulation method to form shell-coated chopped carbon fiber reinforced ultra-high temperature ceramic powder and shell-coated chopped silicon carbide fiber reinforced ultra-high temperature ceramic powder suitable for low-pressure plasma spraying.

[0030] According to some preferred embodiments, the median particle size D50 of the shell-coated chopped carbon fiber reinforced ultrahigh temperature ceramic powder and / or the shell-coated chopped silicon carbide fiber reinforced ultrahigh temperature ceramic powder is 5 to 50 μm (for example, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 μm).

[0031] According to some preferred embodiments, in the shell-coated chopped carbon fiber reinforced ultrahigh temperature ceramic base coating, the mass ratio of the shell-coated chopped carbon fiber to the ultrahigh temperature ceramic is (0.2-9):1; in the shell-coated chopped silicon carbide fiber reinforced ultrahigh temperature ceramic surface coating, the mass ratio of the shell-coated chopped silicon carbide fiber to the ultrahigh temperature ceramic is (0.2-9):1; specifically, in the shell-coated chopped carbon fiber reinforced ultrahigh temperature ceramic powder and the shell-coated chopped silicon carbide fiber reinforced ultrahigh temperature ceramic powder of the present invention, the mass ratio of the shell-coated chopped carbon fiber to the ultrahigh temperature ceramic powder is 1: The mass ratio of the shell-coated chopped silicon carbide fiber to the ultrahigh temperature ceramic powder is 1:5 to 9:1 (for example, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1) to match the anti-oxidation and ablation performance at different service temperatures, thereby enhancing the mechanical properties and anti-ablation performance of the coating.

[0032] According to some preferred embodiments, the thickness of the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic bottom layer coating and / or the layer shell coated short silicon carbide fiber reinforced ultra-high temperature ceramic surface layer coating is 50 to 500 μm (for example, 50, 100, 150, 200, 250, 300, 350, 400, 450 or 500 μm); specifically, in order to ensure that the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic bottom layer coating can maximize the alleviation of the mismatch of thermal expansion coefficients between ultra-high temperature ceramics and ceramic-based composite materials, it is preferred that the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic bottom layer The thickness of the coating is 50 to 500 μm (for example, 50, 100, 150, 200, 250, 300, 350, 400, 450 or 500 μm); in order to ensure that the shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic surface coating has excellent anti-oxidation and ablation properties and prevent the oxidation and ablation failure of the ceramic-based composite material under high temperature, preferably, the thickness of the shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic surface coating is 50 to 500 μm (for example, 50, 100, 150, 200, 250, 300, 350, 400, 450 or 500 μm).

[0033] According to some preferred embodiments, the ultra-high temperature ceramic base coating and / or the ultra-high temperature ceramic surface coating further contain yttrium aluminum garnet powder, and the volume fraction of yttrium aluminum garnet powder in the ultra-high temperature ceramic base coating and / or the ultra-high temperature ceramic surface coating is 4-8% (for example, 4%, 5%, 6%, 7% or 8%); in the present invention, preferably, the particle size of the yttrium aluminum garnet powder is 1-3 μm; the present invention finds that adding small-particle yttrium aluminum garnet powder during the spraying process of the ultra-high temperature ceramic base coating and / or the ultra-high temperature ceramic surface coating can better fill the ultra-high temperature ceramic and shell. The pores and defects between the coated chopped fibers are improved to improve the density and bonding strength of the coating; on the other hand, since the position of oxygen ions in the yttrium aluminum garnet lattice is relatively fixed and the yttrium aluminum garnet has poor ability to transport oxygen ions, it can prevent oxygen from being transported from the defect position of the coating to the interior of the coating, thereby optimizing the oxidation resistance of the coating; in addition, since the melting point of yttrium aluminum garnet is about 1950°C, when used at temperatures exceeding 2000°C, the molten yttrium aluminum garnet can further fill microcracks and prevent further expansion of the cracks, which enables the coating to maintain stable anti-ablation performance in extremely high temperature environments, thereby further improving the service life and reliability of the material.

[0034] In the present invention, preferably, the volume fraction of yttrium aluminum garnet powder in the ultrahigh temperature ceramic base coating and / or the ultrahigh temperature ceramic top coating is 4-8%. The present invention has found that although the addition of yttrium aluminum garnet powder to the ultrahigh temperature ceramic base coating and / or the ultrahigh temperature ceramic top coating is beneficial for further improving the high-temperature oxidation and ablation resistance and bonding strength of the high-bonding strength, anti-oxidation and ablation composite coating, controlling the amount of yttrium aluminum garnet powder is very important. The possible reason is that the addition of an appropriate amount of yttrium aluminum garnet powder further blocks the diffusion of oxygen, thereby improving the oxidation resistance of the coating and extending the service life of the coating at high temperatures. If the volume fraction of yttrium aluminum garnet powder is low, the effect of improving the oxidation resistance of the coating and healing microcracks is not significant. If the volume fraction of yttrium aluminum garnet powder is too high, the brittleness of the coating will increase. The large difference in thermal expansion coefficient between yttrium aluminum garnet and ultrahigh temperature ceramic will lead to excessive thermal mismatch stress, thereby reducing the bonding strength and impact resistance of the coating, and in turn leading to deterioration of the coating performance.

[0035] In the present invention, the shell-coated short-cut carbon fiber reinforced ultra-high temperature ceramic bottom layer coating and the shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic surface layer coating are obtained for the first time by the low-pressure plasma spraying method; in the low-pressure plasma spraying preparation method, the low-pressure plasma spraying method has the advantages of high spraying power, high jet temperature, and fast speed, and has the advantages of high deposition efficiency and low cost; the low-pressure, inert gas coating preparation environment can effectively avoid the oxidation of the sprayed powder and improve the purity of the coating; in addition, the powder melts more fully under the action of the high-energy plasma beam, and the coating porosity is lower, which avoids the generation of internal defects in the coating and reduces the risk of peeling of the coating along the defect position in a high-temperature ablation environment. At the same time, it also reduces the possibility of failure along the interface between the coating and the ceramic-based composite material matrix, and more effectively ensures that the composite coating has high bonding strength and excellent anti-oxidation and ablation properties.

[0036] Therefore, in a second aspect, the present invention provides a method for preparing the high bonding strength, anti-oxidation and ablation composite coating for ceramic matrix composite materials according to the first aspect of the present invention, the method comprising the following steps:

[0037] (1) grinding, cleaning, and drying the ceramic-based composite material (ceramic-based composite material matrix) to obtain a pretreated ceramic-based composite material; specifically, pretreating the ceramic-based composite material: after grinding the ceramic-based composite material, ultrasonically cleaning it in an organic solvent for 10 to 15 minutes, and then drying it in an oven to obtain a pretreated ceramic-based composite material;

[0038] (2) A layer of ultra-high temperature ceramic base coating reinforced by shell-coated short carbon fibers and an ultra-high temperature ceramic surface coating reinforced by shell-coated short silicon carbide fibers are sequentially prepared on the surface of the pretreated ceramic-based composite material by a low-pressure plasma spraying method, thereby preparing the high-bonding strength anti-oxidation and ablation composite coating (abbreviated as a high-bonding strength anti-oxidation and ablation composite coating) on ​​the surface of the ceramic-based composite material; in the present invention, specifically, the pretreated ceramic-based composite substrate is fixed on the workbench of the vacuum chamber of the low-pressure plasma spraying equipment; a layer of ultra-high temperature ceramic base coating reinforced by shell-coated short carbon fibers is first prepared on the surface of the pretreated ceramic-based composite material by using a low-pressure plasma spraying technology to improve the fracture toughness of the coating and reduce the thermal expansion coefficient, thereby improving the bonding strength between the coating and the substrate; on top of the ultra-high temperature ceramic base coating, a layer of ultra-high temperature ceramic surface coating reinforced by shell-coated short silicon carbide fibers is continuously prepared by a low-pressure plasma spraying technology to further enhance the coating's resistance to high-temperature ablation and long-term oxidation, thereby preparing the high-bonding strength anti-oxidation and ablation composite coating on the surface of the ceramic-based composite material.

[0039] The high-bonding strength, anti-oxidation and ablation composite coating described in the present invention uses ultra-high temperature ceramic powder reinforced with shell-coated short-cut carbon fibers and shell-coated short-cut silicon carbide fibers as spraying materials, and utilizes low-pressure plasma spraying technology to sequentially prepare a base layer and a surface layer on the surface of the ceramic-based composite material, thereby significantly improving the high-temperature ablation resistance and oxidation resistance of the coating. At the same time, the weak interface between the shell and the fiber is utilized to deflect cracks in the coating, thereby further enhancing the bonding strength between the coating and the substrate, and further improving the high-temperature oxidation and ablation resistance of the coating. The method of the present invention has the advantages of high deposition efficiency, low cost, and high coating density, and can realize the integrated preparation of high-bonding strength, anti-oxidation and ablation composite coatings.

[0040] According to some preferred embodiments, the ceramic matrix composite material is a carbon fiber reinforced silicon carbide ceramic matrix composite material (C / SiC ceramic matrix composite material) or a carbon fiber reinforced ultrahigh temperature ceramic matrix composite material; the density of the ceramic matrix composite material is 1.8 to 5.0 g / cm 3 (e.g., 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or 5.0 g / cm 3 ); the polishing is performed using sandpaper; the cleaning is ultrasonic cleaning in acetone and / or ethanol for 10 to 15 minutes; and / or the drying temperature is 100 to 150°C.

[0041] According to some specific embodiments, the ceramic-based composite material is pretreated before spraying, and the pretreatment steps are: first, the surface of the ceramic-based composite material is polished, and then the polished ceramic-based composite material is cleaned in an organic solvent, and then placed in an oven for drying. This is beneficial to remove impurities on the surface of the ceramic-based composite material and improve the bonding strength between the coating and the substrate; preferably, the surface of the ceramic-based composite material is polished with 400# (400#), 800# (800#), and 1000# (1000#) sandpaper in sequence, and then ultrasonically cleaned in an organic solvent such as acetone or ethanol for 10 to 15 minutes (for example, 10, 11, 12, 13, 14 or 15 minutes), and then dried in an oven at 100 to 150°C (for example, 100, 110, 120, 130, 140 or 150°C).

[0042] According to some preferred embodiments, during the low-pressure plasma spraying process, plasma jet heating is used to make the surface temperature of the pretreated ceramic-based composite material 600-1000°C (for example, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C) to increase the spreading range of the droplets after the powder melts on the substrate, improve the bonding strength between the coating and the substrate, and reduce the porosity and defects of the coating.

[0043] According to some preferred embodiments, during the low-pressure plasma spraying process, the absolute pressure in the spraying chamber (vacuum chamber of the spraying equipment) is 1×10 2 ~2×10 3 Specifically, in the process of preparing the coating by low-pressure plasma spraying, the pressure in the vacuum chamber of the spraying equipment is first reduced to 1-10 Pa (e.g., 1, 2, 4, 6, 8 or 10 Pa), and then argon is filled into the vacuum chamber to make the absolute pressure in the vacuum chamber 1×10 2 ~2×10 3 Pa (e.g. 1×10 2 , 4×10 2 , 8×10 2 , 1.2×10 3 , 1.6×10 3 or 2×10 3 Pa).

[0044] According to some preferred embodiments, in the process of preparing the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic bottom layer coating and / or the layer shell coated short silicon carbide fiber reinforced ultra-high temperature ceramic surface layer coating, argon and helium are used as plasma gases, the flow rate of argon is 20-50 L / min (for example, 20, 25, 30, 35, 40, 45 or 50 L / min), the flow rate of helium is 10-40 L / min (for example, 10, 15, 20, 25, 30, 35 or 40 L / min), the spraying distance is 400-1000 mm (for example, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 or 1000 mm), and the speed of the turntable is 200-3000 mm. The arc voltage of the low-pressure plasma spraying equipment is 20 to 40 V (20, 25, 30, 35 or 40 V), and the arc current is 800 to 1600 A (for example, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500 or 1600 A). The powder feeding rate of the shell-coated chopped carbon fiber reinforced ultrahigh temperature ceramic powder and / or the shell-coated chopped silicon carbide fiber reinforced ultrahigh temperature ceramic powder is 10 to 20 g / min (for example, 10, 12, 14, 16, 18 or 20 g / min). In the present invention, argon is used as the powder feeding carrier gas during powder feeding.

[0045] According to some specific embodiments, the method for preparing the high bonding strength anti-oxidation and ablation composite coating of the present invention comprises the following steps:

[0046] (a) Pretreatment of the ceramic matrix composite substrate surface: The surface of the ceramic matrix composite substrate was polished using 400, 800, and 1000 sandpaper in sequence, ultrasonically cleaned in an organic solvent such as acetone or ethanol for 10 to 15 minutes, and then dried in an oven at 100 to 150°C to obtain a pretreated ceramic matrix composite.

[0047] (b) Fixing the pretreated ceramic matrix composite material on a rotating table in a vacuum chamber of a low-pressure plasma spraying device; before spraying, evacuating the vacuum chamber of the low-pressure plasma spraying device to 1-10 Pa, and then filling it with argon gas to 1×10 2 ~2×10 3 Pa.

[0048] (c) The surface of the pretreated ceramic matrix composite material is heated to 600-1000°C using a plasma jet.

[0049] (d) First, a shell-coated short-cut carbon fiber reinforced ultrahigh temperature ceramic powder with a median particle size (D50) of 5 to 50 μm is loaded into a powder feeder of a low-pressure plasma spraying device and deposited onto the surface of a ceramic-based composite material matrix by a low-pressure plasma spraying method to prepare a shell-coated short-cut carbon fiber reinforced ultrahigh temperature ceramic base coating with a thickness of about 50 to 500 μm.

[0050] (e) Subsequently, the shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic powder with a median particle size (D50) of 5 to 50 μm is loaded into the powder feeder of the low-pressure plasma spraying equipment, and is deposited on the shell-coated short-cut carbon fiber reinforced ultra-high temperature ceramic base coating of the ceramic-based composite material matrix by a low-pressure plasma spraying method to prepare a shell-coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic top coating with a thickness of about 50 to 500 μm, and the spraying is terminated to obtain the high bonding strength and anti-oxidation and ablation composite coating on the surface of the ceramic-based composite material.

[0051] (f) After the ceramic matrix composite substrate and its coating are cooled to below 400° C., the vacuum chamber pressure is restored to atmospheric pressure, and finally the ceramic matrix composite material on which the high bonding strength, anti-oxidation and ablation composite coating is deposited is taken out.

[0052] In a third aspect, the present invention provides a high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials, which is prepared by the preparation method described in the second aspect of the present invention.

[0053] According to some preferred embodiments, the bonding strength of the high bonding strength anti-oxidation ablation composite coating is not less than 50 MPa; the porosity of the high bonding strength anti-oxidation ablation composite coating is less than 10%; the linear ablation rate of the high bonding strength anti-oxidation ablation composite coating in the oxyacetylene ablation test at a coating surface temperature of 2000°C is less than 1×10 -3 mm / s.

[0054] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these examples. The present invention may also have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, and such corresponding changes and modifications shall fall within the scope of protection of the claims appended hereto.

[0055] Example 1

[0056] ① Pretreated ceramic matrix composite material: the size is 30mm (diameter) × 5mm (thickness), and the density is 1.88g / cm 3The carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC) was used as the matrix, and the matrix surface was polished with 400#, 800# and 1000# sandpaper in sequence, then ultrasonically cleaned in acetone for 10 minutes, and finally dried in an oven at 120℃ to obtain a pretreated ceramic matrix composite.

[0057] ② Prepare the spraying material: Use the CVD method to prepare a PyC shell with a thickness of 300nm on the surface of the carbon fiber to obtain PyC shell-coated carbon fiber, and prepare a SiC shell with a thickness of 300nm on the surface of the silicon carbide fiber to obtain SiC shell-coated silicon carbide fiber; then use a mechanical cutting device to cut the PyC shell-coated carbon fiber and SiC shell-coated silicon carbide fiber to obtain PyC shell-coated short carbon fiber with a length of 5μm and a diameter of 0.8μm, and obtain SiC shell-coated short silicon carbide fiber with a length of 8μm and a diameter of 1μm. Use the spray granulation method to obtain PyC shell-coated short carbon fiber reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder, wherein the mass ratio of PyC shell-coated short carbon fiber to HfC ultra-high temperature ceramic powder is 1:3, and the powder median particle size (D50) is 20μm. The spray granulation method was used to obtain HfC ultrahigh temperature ceramic powder reinforced with SiC layer shell-coated chopped silicon carbide fibers, wherein the mass ratio of SiC layer shell-coated chopped silicon carbide fibers to HfC ultrahigh temperature ceramic powder was 1:4, and the median particle size (D50) of the powder was 25 μm.

[0058] ③ Preparation of the bottom coating by low-pressure plasma spraying: The pretreated ceramic matrix composite substrate obtained in step ① was fixed on the rotating table of the vacuum chamber of the low-pressure plasma spraying equipment; before spraying, the vacuum chamber was evacuated to 5 Pa and then filled with argon gas to an absolute pressure of 8×10 2 Pa. The surface of the pretreated ceramic matrix composite substrate was heated to 800°C using a plasma jet. Argon and helium were used as plasma gases (argon flow rate 30 L / min, helium flow rate 20 L / min), the spraying distance was 600 mm, the turntable speed was 10 r / min, the arc voltage was 30 V, and the arc current was 1000 A. After the plasma beam stabilized, the powder feeder containing the PyC layer-shell-coated short carbon fiber reinforced HfC ultra-high temperature ceramic powder obtained in step ② was opened. The powder feeding rate was 12 g / min, and the deposition time was 2 min. A PyC layer-shell-coated short carbon fiber reinforced HfC ultra-high temperature ceramic base coating with a thickness of 200 μm was prepared.

[0059] ④ Preparation of the surface coating by low-pressure plasma spraying: keeping the absolute pressure in the vacuum chamber unchanged, the surface coating was prepared with the same plasma gas ratio, spraying distance and turntable speed as in step ③, arc voltage of 30V, and arc current of 1100A. After the plasma beam stabilized, the powder feeder containing the SiC layer shell-coated short-cut silicon carbide fiber-reinforced HfC ultra-high temperature ceramic powder obtained in step ③ was opened, the powder feeding rate was 15g / min, the deposition time was 1.5min, and a SiC layer shell-coated short-cut silicon carbide fiber-reinforced HfC ultra-high temperature ceramic bottom coating with a thickness of 150μm was prepared on the basis of the PyC layer shell-coated short-cut carbon fiber-reinforced HfC ultra-high temperature ceramic bottom coating, thereby obtaining the high bonding strength and anti-oxidation and ablation composite coating on the surface of the C / SiC ceramic-based composite material.

[0060] ⑤ Cooling and taking out: After the vacuum chamber is cooled to room temperature, the atmospheric pressure is restored and the C / SiC ceramic matrix composite material with the high bonding strength anti-oxidation and ablation composite coating is taken out.

[0061] Performance Testing: The present invention tested the bonding strength of the high-bonding-strength, anti-oxidation-ablation composite coating described in this embodiment using an electronic universal material testing machine, and the result was 60 MPa. The overall porosity of the high-bonding-strength, anti-oxidation-ablation composite coating in this embodiment was calculated using an image method based on the cross-sectional micromorphology of the coating to be 8%. The C / SiC ceramic-based composite material with the high-bonding-strength, anti-oxidation-ablation composite coating was subjected to an oxyacetylene ablation test in accordance with the GJB 323 standard. The coating surface temperature was 2000°C, and the test time was 600 seconds. The linear ablation rate of the high-bonding-strength, anti-oxidation-ablation composite coating was measured to be 0.8×10 -3 mm / s.

[0062] Example 2

[0063] Example 2 is basically the same as Example 1, except that:

[0064] In step ③, the arc voltage is 35 V, the arc current is 1200 A, and the other process parameters are the same, and a PyC layer shell with a thickness of 190 μm and a short carbon fiber reinforced HfC ultra-high temperature ceramic base coating is prepared.

[0065] In step ④, the arc voltage is 35 V, the arc current is 1300 A, and the other process parameters are the same, and a SiC layer shell with a thickness of 140 μm and a short-cut silicon carbide fiber-reinforced HfC ultra-high temperature ceramic surface coating is prepared.

[0066] The bonding strength, porosity and ablation resistance of the high bonding strength anti-oxidation and ablation composite coating prepared in this embodiment were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0067] Example 3

[0068] Example 3 is basically the same as Example 1, except that:

[0069] In step ③, using the same process parameters and a deposition time of 3 min, a PyC layer shell with a thickness of 300 μm and a chopped carbon fiber reinforced HfC ultra-high temperature ceramic base coating was prepared.

[0070] In step ④, using the same process parameters and a deposition time of 3 min, a 300 μm thick SiC shell-coated chopped silicon carbide fiber-reinforced HfC ultra-high temperature ceramic surface coating was prepared.

[0071] The bonding strength, porosity and ablation resistance of the high bonding strength anti-oxidation and ablation composite coating prepared in this embodiment were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0072] Example 4

[0073] Example 4 is basically the same as Example 1, except that:

[0074] In step ②, a spray granulation method is used to obtain a PyC shell-coated short carbon fiber reinforced zirconium carbide (ZrC) ultrahigh temperature ceramic powder, wherein the length of the PyC shell-coated short carbon fiber is 6 μm and the diameter is 1 μm, the mass ratio of the PyC shell-coated short carbon fiber to the ZrC ultrahigh temperature ceramic powder is 1:3, and the powder median particle size (D50) is 22 μm. A SiC shell-coated short silicon carbide fiber reinforced zirconium boride (ZrB2) ultrahigh temperature ceramic powder is obtained by spray granulation, wherein the length of the SiC shell-coated short silicon carbide fiber is 8 μm and the diameter is 1.2 μm, the mass ratio of the SiC shell-coated short silicon carbide fiber to the ZrB2 ultrahigh temperature ceramic powder is 1:4, and the powder median particle size (D50) is 27 μm.

[0075] In step ③, using the same process parameters and a deposition time of 2 min, a PyC layer shell with a thickness of 180 μm and a ZrC ultrahigh temperature ceramic base coating reinforced with chopped carbon fibers was prepared.

[0076] In step ④, using the same process parameters and a deposition time of 1.5 min, a SiC layer shell with a thickness of 140 μm and a ZrB2 ultra-high temperature ceramic surface coating reinforced with chopped silicon carbide fibers was prepared.

[0077] The bonding strength, porosity and ablation resistance of the high bonding strength anti-oxidation and ablation composite coating prepared in this embodiment were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0078] Example 5

[0079] Example 5 is basically the same as Example 1, except that:

[0080] In step ①, select the size of 30mm (diameter) × 5mm (thickness) and the density of 2.52g / cm 3 The C / ZrC-SiC carbon fiber reinforced ceramic matrix composite material is used as the matrix, and other pretreatment methods remain unchanged to obtain a pretreated ceramic matrix composite material.

[0081] In step ②, a spray granulation method is used to obtain a PyC shell-coated short carbon fiber reinforced tantalum nitride (TaN) ultrahigh temperature ceramic powder, wherein the length of the PyC shell-coated short carbon fiber is 10 μm and the diameter is 1.0 μm, the mass ratio of the PyC shell-coated short carbon fiber to the TaN ultrahigh temperature ceramic powder is 1:1, and the powder median particle size (D50) is 25 μm. A SiC shell-coated short silicon carbide fiber reinforced hafnium boride (HfB2) ultrahigh temperature ceramic powder is obtained by a spray granulation method, wherein the length of the SiC shell-coated short silicon carbide fiber is 8 μm and the diameter is 1 μm, the mass ratio of the SiC shell-coated short silicon carbide fiber to the HfB2 ultrahigh temperature ceramic powder is 1:1, and the powder median particle size (D50) is 30 μm.

[0082] In step ③, using the same process parameters and a deposition time of 2.2 min, a PyC layer shell with a thickness of 180 μm and a short carbon fiber reinforced TaN ultra-high temperature ceramic base coating was prepared.

[0083] In step ④, using the same process parameters and a deposition time of 1.7 min, a SiC layer shell with a thickness of 140 μm and a short-cut silicon carbide fiber-reinforced HfB2 ultra-high temperature ceramic surface coating was prepared.

[0084] The bonding strength, porosity and ablation resistance of the high bonding strength anti-oxidation and ablation composite coating prepared in this embodiment were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0085] Example 6

[0086] Example 6 is basically the same as Example 1, except that:

[0087] In step ②: using the CVD method, a boron nitride (BN) shell with a thickness of 300nm is prepared on the surface of the carbon fiber to obtain a BN shell-coated carbon fiber, and a SiC shell with a thickness of 300nm is prepared on the surface of the silicon carbide fiber to obtain a SiC shell-coated silicon carbide fiber; then, a mechanical cutting device is used to cut the BN shell-coated carbon fiber and the SiC shell-coated silicon carbide fiber to obtain a BN shell-coated short carbon fiber with a length of 5μm and a diameter of 0.8μm, and a SiC shell-coated short silicon carbide fiber with a length of 8μm and a diameter of 1μm. A spray granulation method is used to obtain BN shell-coated short carbon fiber reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder, wherein the mass ratio of BN shell-coated short carbon fiber to HfC ultra-high temperature ceramic powder is 1:3, and the median particle size (D50) of the powder is 20μm. The spray granulation method was used to obtain HfC ultrahigh temperature ceramic powder reinforced with SiC layer shell-coated chopped silicon carbide fibers, wherein the mass ratio of SiC layer shell-coated chopped silicon carbide fibers to HfC ultrahigh temperature ceramic powder was 1:4, and the median particle size (D50) of the powder was 25 μm.

[0088] In step ③: the pretreated ceramic matrix composite substrate obtained in step ① is fixed on the rotating table of the vacuum chamber of the low-pressure plasma spraying equipment; before spraying, the vacuum chamber is evacuated to 5 Pa and then filled with argon gas to an absolute pressure of 8×10 2 Pa. The surface of the pretreated ceramic matrix composite substrate was heated to 800°C by plasma jet heating. Argon and helium were used as plasma gases (argon flow rate 30 L / min, helium flow rate 20 L / min), the spraying distance was 600 mm, the turntable speed was 10 r / min, the arc voltage was 30 V, the arc current was 1000 A, and after the plasma beam was stabilized, the powder feeder containing the BN layer shell-coated short carbon fiber reinforced HfC ultra-high temperature ceramic powder obtained in step ② was opened at a powder feeding rate of 12 g / min to prepare a BN layer shell-coated short carbon fiber reinforced HfC ultra-high temperature ceramic base coating with a thickness of 200 μm.

[0089] In step ④: keeping the absolute pressure in the vacuum chamber unchanged, preparing the surface coating with the same plasma gas ratio, spraying distance and turntable speed as in step ③, an arc voltage of 30 V, and an arc current of 1100 A, and starting the powder feeder containing the SiC layer shell-coated chopped silicon carbide fiber-reinforced HfC ultra-high temperature ceramic powder obtained in step ③ after the plasma beam is stable, at a powder feeding rate of 15 g / min, and preparing a SiC layer shell-coated chopped silicon carbide fiber-reinforced HfC ultra-high temperature ceramic bottom coating with a thickness of 150 μm on the basis of the BN layer shell-coated chopped carbon fiber-reinforced HfC ultra-high temperature ceramic top coating, thereby obtaining the high bonding strength and anti-oxidation and ablation composite coating on the surface of the C / SiC ceramic-based composite material.

[0090] The bonding strength, porosity and ablation resistance of the high bonding strength anti-oxidation and ablation composite coating prepared in this embodiment were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0091] Example 7

[0092] Example 7 is basically the same as Example 1, except that:

[0093] ② Prepare the spraying material: Use the CVD method to prepare a PyC shell with a thickness of 300 nm on the surface of the carbon fiber to obtain PyC shell-coated carbon fiber, and prepare a SiC shell with a thickness of 300 nm on the surface of the silicon carbide fiber to obtain SiC shell-coated silicon carbide fiber; then use mechanical cutting equipment to cut the PyC shell-coated carbon fiber and the SiC shell-coated silicon carbide fiber to obtain PyC shell-coated chopped carbon fiber with a length of 5 μm and a diameter of 0.8 μm, and obtain SiC shell-coated chopped silicon carbide fiber with a length of 8 μm and a diameter of 1 μm. A spray granulation method is used to compound PyC layer-shell-coated chopped carbon fibers, hafnium carbide (HfC) ultrahigh temperature ceramic powder and yttrium aluminum garnet powder to obtain PyC layer-shell-coated chopped carbon fibers reinforced hafnium carbide (HfC) ultrahigh temperature ceramic powder, wherein the mass ratio of PyC layer-shell-coated chopped carbon fibers to HfC ultrahigh temperature ceramic powder is 1:3, the volume fraction of yttrium aluminum garnet powder in the PyC layer-shell-coated chopped carbon fibers reinforced hafnium carbide (HfC) ultrahigh temperature ceramic powder is 6%, and the median particle size (D50) of the powder is 17 μm. A spray granulation method is used to composite SiC layer-shell-coated chopped silicon carbide fiber, hafnium carbide (HfC) ultra-high temperature ceramic powder and yttrium aluminum garnet powder to obtain SiC layer-shell-coated chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder, wherein the mass ratio of SiC layer-shell-coated chopped silicon carbide fiber to HfC ultra-high temperature ceramic powder is 1:4, the volume fraction of yttrium aluminum garnet powder in the SiC layer-shell-coated chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder is 6%, and the powder median particle size (D50) is 21 μm.

[0094] The bonding strength, porosity and ablation resistance of the high bonding strength anti-oxidation and ablation composite coating prepared in this embodiment were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0095] Comparative Example 1

[0096] ① Pretreated ceramic matrix composite material: the size is 30mm (diameter) × 5mm (thickness), and the density is 1.88g / cm 3The carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC) was used as the matrix, and the matrix surface was polished with 400#, 800# and 1000# sandpaper in sequence, then ultrasonically cleaned in acetone for 10 minutes, and finally dried in an oven at 120℃ to obtain a pretreated ceramic matrix composite.

[0097] ② Prepare the spraying material: Use the spray granulation method to obtain short carbon fiber reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder, the short carbon fiber length is 5μm, the diameter is 0.8μm, the mass ratio of short carbon fiber to HfC ultra-high temperature ceramic powder is 1:3, and the median particle size (D50) of the powder is 20μm. Use the spray granulation method to obtain short silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder, the short silicon carbide fiber length is 8μm, the diameter is 1μm, the mass ratio of short silicon carbide fiber to HfC ultra-high temperature ceramic powder is 1:4, and the median particle size (D50) of the powder is 25μm.

[0098] ③ Preparation of a base coating by atmospheric plasma spraying: The pretreated ceramic matrix composite substrate obtained in step ① was fixed to the operating table of an atmospheric plasma spraying apparatus; the spraying pressure was atmospheric pressure. During spraying, argon was used as the plasma gas, hydrogen as the auxiliary gas, with an argon flow rate of 40 L / min, a hydrogen flow rate of 7.5 L / min, a spray distance of 800 mm, an arc voltage of 40 V, and an arc current of 700 A. After the plasma beam stabilized, a powder feeder containing the chopped carbon fiber-reinforced HfC ultrahigh temperature ceramic powder obtained in step ② was started at a powder feed rate of 15 g / min and a deposition time of 5 minutes to produce a 200 μm thick chopped carbon fiber-reinforced HfC ultrahigh temperature ceramic base coating.

[0099] ④ Preparation of the surface coating by atmospheric plasma spraying: Maintain the same plasma gas flow rate, auxiliary gas flow rate, and spraying distance as in step ③, the arc voltage is 42V, and the arc current is 750A to prepare the surface coating. After the plasma beam is stable, the powder feeder containing the chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder obtained in step ② is turned on, the powder feeding rate is 18 g / min, the deposition time is 4 min, and a chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic surface coating with a thickness of 150 μm is prepared on the basis of the chopped carbon fiber reinforced HfC ultra-high temperature ceramic base coating, thereby obtaining an antioxidant ablation composite coating on the surface of the C / SiC ceramic-based composite material.

[0100] ⑤ Cooling and removal: After the coating and substrate have cooled, remove the C / SiC ceramic matrix composite material with the anti-oxidation and ablation composite coating from the operating table.

[0101] The bonding strength, porosity and anti-ablation performance of the anti-oxidation ablation composite coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0102] Comparative Example 2

[0103] ① Pretreated ceramic matrix composite material: the size is 30mm (diameter) × 5mm (thickness), and the density is 1.88g / cm 3 The carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC) was used as the matrix, and the matrix surface was polished with 400#, 800# and 1000# sandpaper in sequence, then ultrasonically cleaned in acetone for 10 minutes, and finally dried in an oven at 120℃ to obtain a pretreated ceramic matrix composite.

[0104] ② Prepare spraying materials: Use HfC ultra-high temperature ceramic powder after spray granulation, with a median particle size (D50) of 20 μm.

[0105] ③ Preparation of coating by low-pressure plasma spraying: The pretreated ceramic matrix composite substrate obtained in step ① was fixed on the rotating table of the vacuum chamber of the low-pressure plasma spraying equipment; before spraying, the vacuum chamber was evacuated to 5 Pa and then filled with argon gas to an absolute pressure of 8×10 2 Pa. The surface of the pretreated ceramic matrix composite substrate was heated to 800°C using a plasma jet. Argon and helium were used as plasma gases (argon flow rate 30 L / min, helium flow rate 20 L / min), the spraying distance was 600 mm, the turntable speed was 10 r / min, the arc voltage was 30 V, and the arc current was 1000 A. After the plasma beam stabilized, the powder feeder containing the HfC ultrahigh temperature ceramic powder prepared in step ② was turned on at a powder feeding rate of 12 g / min and a deposition time of 3.5 min to prepare a 350 μm thick HfC ultrahigh temperature ceramic coating.

[0106] ④ Cooling and taking out: After the vacuum chamber is cooled to room temperature, the atmospheric pressure is restored and the C / SiC ceramic matrix composite material with the HfC ultrahigh temperature ceramic coating is taken out.

[0107] The bonding strength, porosity and ablation resistance of the HfC ultrahigh temperature ceramic coating prepared in this comparative example were tested using the same testing method as in Example 1. The performance test results are shown in Table 1.

[0108] Comparative Example 3

[0109] Comparative Example 3 is substantially the same as Comparative Example 2, except that:

[0110] ② Prepare the spraying material: Use the spray granulation method to obtain short-cut carbon fiber reinforced HfC ultra-high temperature ceramic powder, wherein the length of the short-cut carbon fiber is 5 μm, the diameter is 0.8 μm, the mass ratio of the short-cut carbon fiber to the HfC ceramic powder is 1:3, and the median particle size (D50) of the powder is 20 μm.

[0111] In step ③, the same process parameters were used, except that after the plasma beam was stabilized, the powder feeder containing the HfC ultra-high temperature ceramic powder reinforced with chopped carbon fibers in step ② was opened, and the deposition time was 3.5 min. A chopped carbon fiber reinforced HfC coating with a thickness of 350 μm was prepared.

[0112] The bonding strength, porosity and ablation resistance of the chopped carbon fiber reinforced HfC coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0113] Comparative Example 4

[0114] Comparative Example 4 is substantially the same as Comparative Example 2, except that:

[0115] ② Prepare the spraying material: Use the spray granulation method to obtain short-cut silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder, wherein the short-cut silicon carbide fiber has a length of 8 μm and a diameter of 1 μm, the mass ratio of the short-cut silicon carbide fiber to the HfC ceramic powder is 1:4, and the median particle size (D50) of the powder is 25 μm.

[0116] In step ③, the same process parameters are used, except that after the plasma beam is stabilized, the powder feeder containing the HfC ultra-high temperature ceramic powder reinforced with chopped silicon carbide fibers prepared in step ② is opened to prepare a 350 μm thick chopped silicon carbide fiber reinforced HfC coating.

[0117] The bonding strength, porosity and ablation resistance of the chopped silicon carbide fiber reinforced HfC coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0118] Comparative Example 5

[0119] Comparative Example 5 is substantially the same as Comparative Example 2, except that:

[0120] In step ①, select the size of 30mm (diameter) × 5mm (thickness) and the density of 2.52g / cm 3 The C / ZrC-SiC carbon fiber reinforced ceramic matrix composite material is used as the matrix, and other pretreatment methods remain unchanged to obtain a pretreated ceramic matrix composite material.

[0121] In step ②, a spray granulation method is used to obtain short-cut carbon fiber reinforced hafnium boride (HfB2) ultra-high temperature ceramic powder, wherein the length of the short-cut carbon fiber is 8 μm, the diameter is 1 μm, the mass ratio of the short-cut carbon fiber to the HfB2 ultra-high temperature ceramic powder is 1:1, and the median particle size (D50) of the powder is 30 μm.

[0122] In step ③, the same process parameters are used, except that after the plasma beam is stabilized, the powder feeder containing the ultra-high temperature ceramic powder of hafnium boride (HfB2) reinforced with chopped carbon fibers in step ② is opened, and the deposition time is 4 minutes to prepare a 370 μm thick chopped carbon fiber reinforced HfB2 coating.

[0123] The bonding strength, porosity and ablation resistance of the chopped silicon carbide fiber reinforced HfB2 coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0124] Comparative Example 6

[0125] ① Pretreated ceramic matrix composite material: the size is 30mm (diameter) × 5mm (thickness), and the density is 1.88g / cm 3 The carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC) was used as the matrix, and the matrix surface was polished with 400#, 800# and 1000# sandpaper in sequence, then ultrasonically cleaned in acetone for 10 minutes, and finally dried in an oven at 120℃ to obtain a pretreated ceramic matrix composite.

[0126] ② Prepare the spraying material: Use the spray granulation method to obtain short carbon fiber reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder, the short carbon fiber length is 5μm, the diameter is 0.8μm, the mass ratio of short carbon fiber to HfC ultra-high temperature ceramic powder is 1:3, and the median particle size (D50) of the powder is 20μm. Use the spray granulation method to obtain short silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder, the short silicon carbide fiber length is 8μm, the diameter is 1μm, the mass ratio of short silicon carbide fiber to HfC ultra-high temperature ceramic powder is 1:4, and the median particle size (D50) of the powder is 25μm.

[0127] ③ Preparation of the bottom coating by low-pressure plasma spraying: The pretreated ceramic matrix composite substrate obtained in step ① was fixed on the rotating table of the vacuum chamber of the low-pressure plasma spraying equipment; before spraying, the vacuum chamber was evacuated to 5 Pa and then filled with argon gas to an absolute pressure of 8×10 2Pa. The surface of the pretreated ceramic matrix composite substrate was heated to 800°C using a plasma jet. Argon and helium were used as plasma gases (argon flow rate of 30 L / min, helium flow rate of 20 L / min), the spraying distance was 600 mm, the turntable speed was 10 r / min, the arc voltage was 30 V, and the arc current was 1000 A. After the plasma beam stabilized, the powder feeder containing the chopped carbon fiber reinforced HfC ultra-high temperature ceramic powder prepared in step ② was opened at a powder feeding rate of 12 g / min to prepare a 200 μm thick chopped carbon fiber reinforced HfC ultra-high temperature ceramic base coating.

[0128] ④ Preparation of the surface coating by low-pressure plasma spraying: keeping the absolute pressure in the vacuum chamber unchanged, the surface coating was prepared with the same plasma gas ratio, spraying distance and turntable speed as in step ③, an arc voltage of 30 V, and an arc current of 1100 A. After the plasma beam stabilized, the powder feeder containing the chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder prepared in step ③ was turned on at a powder feeding rate of 15 g / min. A 150 μm thick chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic surface coating was prepared on the basis of the chopped carbon fiber reinforced HfC ultra-high temperature ceramic base coating, thereby obtaining an anti-oxidation and ablation composite coating on the surface of the C / SiC ceramic-based composite material.

[0129] ⑤ Cooling and taking out: After the vacuum chamber is cooled to room temperature, the atmospheric pressure is restored and the C / SiC ceramic-based composite material with the anti-oxidation and ablation composite coating is taken out.

[0130] The bonding strength, porosity and anti-ablation performance of the anti-oxidation ablation composite coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0131] Comparative Example 7

[0132] ① Pretreated ceramic matrix composite material: the size is 30mm (diameter) × 5mm (thickness), and the density is 1.88g / cm 3 The carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC) was used as the matrix, and the matrix surface was polished with 400#, 800# and 1000# sandpaper in sequence, then ultrasonically cleaned in acetone for 10 minutes, and finally dried in an oven at 120℃ to obtain a pretreated ceramic matrix composite.

[0133] ② Prepare the spraying material: Use the CVD method to prepare a PyC layer shell with a thickness of 300nm on the surface of the carbon fiber to obtain PyC layer shell coated carbon fiber; then use a mechanical cutting device to cut the PyC layer shell coated carbon fiber to obtain PyC layer shell coated chopped carbon fiber with a length of 5μm and a diameter of 0.8μm. Use the spray granulation method to obtain PyC layer shell coated chopped carbon fiber reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder, wherein the mass ratio of PyC layer shell coated chopped carbon fiber to HfC ultra-high temperature ceramic powder is 1:3, and the powder median particle size (D50) is 20μm. Use the spray granulation method to obtain short silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder, wherein the short silicon carbide fiber length is 8μm, the diameter is 1μm, the mass ratio of short silicon carbide fiber to HfC ultra-high temperature ceramic powder is 1:4, and the powder median particle size (D50) is 25μm.

[0134] ③ Preparation of the bottom coating by low-pressure plasma spraying: The pretreated ceramic matrix composite substrate obtained in step ① was fixed on the rotating table of the vacuum chamber of the low-pressure plasma spraying equipment; before spraying, the vacuum chamber was evacuated to 5 Pa and then filled with argon gas to an absolute pressure of 8×10 2 Pa. The surface of the pretreated ceramic matrix composite substrate was heated to 800°C using a plasma jet. Argon and helium were used as plasma gases (argon flow rate 30 L / min, helium flow rate 20 L / min), the spraying distance was 600 mm, the turntable speed was 10 r / min, the arc voltage was 30 V, and the arc current was 1000 A. After the plasma beam stabilized, the powder feeder containing the PyC layer-shell-coated short carbon fiber reinforced HfC ultra-high temperature ceramic powder obtained in step ② was opened at a powder feeding rate of 12 g / min to prepare a PyC layer-shell-coated short carbon fiber reinforced HfC ultra-high temperature ceramic base coating with a thickness of 200 μm.

[0135] ④ Preparation of the surface coating by low-pressure plasma spraying: keeping the absolute pressure in the vacuum chamber unchanged, the surface coating was prepared with the same plasma gas ratio, spraying distance and turntable speed as in step ③, arc voltage of 30V, and arc current of 1100A. After the plasma beam stabilized, the powder feeder containing the chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder in step ③ was turned on at a powder feeding rate of 15g / min. A 150μm thick chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic surface coating was prepared on the basis of the PyC layer shell-coated chopped carbon fiber reinforced HfC ultra-high temperature ceramic base coating, thereby obtaining an antioxidant ablation composite coating on the surface of the C / SiC ceramic-based composite material.

[0136] ⑤ Cooling and taking out: After the vacuum chamber is cooled to room temperature, the atmospheric pressure is restored and the C / SiC ceramic-based composite material with the anti-oxidation and ablation composite coating is taken out.

[0137] The bonding strength, porosity and anti-ablation performance of the anti-oxidation ablation composite coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0138] Comparative Example 8

[0139] ① Pretreated ceramic matrix composite material: the size is 30mm (diameter) × 5mm (thickness), and the density is 1.88g / cm 3 The carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC) was used as the matrix, and the matrix surface was polished with 400#, 800# and 1000# sandpaper in sequence, then ultrasonically cleaned in acetone for 10 minutes, and finally dried in an oven at 120℃ to obtain a pretreated ceramic matrix composite.

[0140] ② Prepare the spray material: Use a spray granulation method to obtain short carbon fiber reinforced hafnium carbide (HfC) ultrahigh temperature ceramic powder. The short carbon fiber length is 5μm and the diameter is 0.8μm. The mass ratio of short carbon fiber to HfC ultrahigh temperature ceramic powder is 1:3, and the median particle size (D50) of the powder is 20μm. Use the CVD method to prepare a SiC shell with a thickness of 300nm on the surface of silicon carbide fiber to obtain SiC shell-coated silicon carbide fiber. Then, use a mechanical cutting device to cut the SiC shell-coated silicon carbide fiber to obtain SiC shell-coated short silicon carbide fiber with a length of 8μm and a diameter of 1μm. Use a spray granulation method to obtain SiC shell-coated short silicon carbide fiber reinforced HfC ultrahigh temperature ceramic powder. The mass ratio of SiC shell-coated short silicon carbide fiber to HfC ultrahigh temperature ceramic powder is 1:4, and the median particle size (D50) of the powder is 25μm.

[0141] ③ Preparation of the bottom coating by low-pressure plasma spraying: The pretreated ceramic matrix composite substrate obtained in step ① was fixed on the rotating table of the vacuum chamber of the low-pressure plasma spraying equipment; before spraying, the vacuum chamber was evacuated to 5 Pa and then filled with argon gas to an absolute pressure of 8×10 2 Pa. The surface of the pretreated ceramic matrix composite substrate was heated to 800°C by plasma jet heating. Argon and helium were used as plasma gases (argon flow rate 30 L / min, helium flow rate 20 L / min), the spraying distance was 600 mm, the turntable speed was 10 r / min, the arc voltage was 30 V, the arc current was 1000 A, and after the plasma beam was stabilized, the powder feeder containing the chopped carbon fiber reinforced HfC ultra-high temperature ceramic powder in step ② was opened at a powder feeding rate of 12 g / min to prepare a chopped carbon fiber reinforced HfC ultra-high temperature ceramic base coating with a thickness of 200 μm.

[0142] ④ Preparation of the surface coating by low-pressure plasma spraying: keeping the absolute pressure in the vacuum chamber unchanged, the surface coating was prepared with the same plasma gas ratio, spraying distance and turntable speed as in step ③, an arc voltage of 30 V, and an arc current of 1100 A. After the plasma beam stabilized, the powder feeder containing the SiC layer shell-coated chopped silicon carbide fiber-reinforced HfC ultra-high temperature ceramic powder obtained in step ③ was turned on at a powder feeding rate of 15 g / min. On the basis of the chopped carbon fiber-reinforced HfC ultra-high temperature ceramic base coating, a SiC layer shell-coated chopped silicon carbide fiber-reinforced HfC ultra-high temperature ceramic surface coating with a thickness of 150 μm was prepared, thereby obtaining an anti-oxidation and ablation composite coating on the surface of the C / SiC ceramic-based composite material.

[0143] ⑤ Cooling and taking out: After the vacuum chamber is cooled to room temperature, the atmospheric pressure is restored and the C / SiC ceramic-based composite material with the anti-oxidation and ablation composite coating is taken out.

[0144] The bonding strength, porosity and anti-ablation performance of the anti-oxidation ablation composite coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0145] Comparative Example 9

[0146] Comparative Example 9 is substantially the same as Example 7, except that:

[0147] ② Prepare the spraying material: Use the CVD method to prepare a PyC shell with a thickness of 300 nm on the surface of the carbon fiber to obtain PyC shell-coated carbon fiber, and prepare a SiC shell with a thickness of 300 nm on the surface of the silicon carbide fiber to obtain SiC shell-coated silicon carbide fiber; then use mechanical cutting equipment to cut the PyC shell-coated carbon fiber and the SiC shell-coated silicon carbide fiber to obtain PyC shell-coated chopped carbon fiber with a length of 5 μm and a diameter of 0.8 μm, and obtain SiC shell-coated chopped silicon carbide fiber with a length of 8 μm and a diameter of 1 μm. A spray granulation method is used to compound PyC layer-shell-coated chopped carbon fibers, hafnium carbide (HfC) ultra-high temperature ceramic powder and yttrium aluminum garnet powder to obtain PyC layer-shell-coated chopped carbon fibers reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder, wherein the mass ratio of PyC layer-shell-coated chopped carbon fibers to HfC ultra-high temperature ceramic powder is 1:3, the volume fraction of yttrium aluminum garnet powder in the PyC layer-shell-coated chopped carbon fibers reinforced hafnium carbide (HfC) ultra-high temperature ceramic powder is 27%, and the powder median particle size (D50) is 10 μm. A spray granulation method is used to composite SiC layer-shell-coated chopped silicon carbide fiber, hafnium carbide (HfC) ultra-high temperature ceramic powder and yttrium aluminum garnet powder to obtain SiC layer-shell-coated chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder, wherein the mass ratio of SiC layer-shell-coated chopped silicon carbide fiber to HfC ultra-high temperature ceramic powder is 1:4, the volume fraction of yttrium aluminum garnet powder in the SiC layer-shell-coated chopped silicon carbide fiber reinforced HfC ultra-high temperature ceramic powder is 18%, and the powder median particle size (D50) is 13 μm.

[0148] The bonding strength, porosity and anti-ablation performance of the anti-oxidation ablation composite coating prepared in this comparative example were tested using the same test method as in Example 1. The performance test results are shown in Table 1.

[0149]

[0150]

[0151]

[0152] From the data in Table 1, it can be seen that the high bonding strength and oxidation-resistant ablation composite coating designed and prepared by the present invention has excellent bonding strength and high-temperature oxidation ablation resistance. The bonding strength of the layer-shell-coated short carbon fiber reinforced HfC / layer-shell-coated short silicon carbide fiber reinforced HfC composite coating prepared by the present invention is not less than 58 MPa, the porosity is less than 10%, and the oxyacetylene ablation rate at 2000°C is less than 1×10 -3mm / s. In Example 2, compared with Example 1, by increasing the current and voltage during spraying, that is, increasing the power of the plasma beam, the spray powder melts better in the beam, spreads more fully on the substrate, has a lower coating porosity, a higher coating bonding strength, and better anti-ablation performance. In Example 3, compared with Example 1, by extending the spraying time, the thickness of the composite coating is improved, and at the same time, the bonding strength and anti-ablation performance of the composite coating are not affected. In Example 4, compared with Example 1, the bottom layer is a PyC layer shell coated with chopped fiber reinforced ZrB2, and the surface layer is a SiC layer shell coated with chopped silicon carbide fiber reinforced ZrC coating, and other spraying parameters remain unchanged. Since the melting point of ZrB2 is lower than that of HfC, the powder is easier to melt in the beam, so the prepared coating has a lower porosity. Although the ablation resistance of ZrC is poorer than that of HfC, the presence of SiC shell coated with chopped silicon carbide fibers improves the oxidation resistance of ZrC. The ablation rate of the ZrC coating reinforced with SiC shell coated with chopped silicon carbide fibers is still lower than 1×10 - 3 mm / s. In Example 5, a relatively high-density carbon fiber reinforced ultra-high temperature ceramic matrix composite material is used as the matrix, the bottom layer is a PyC layer shell-coated short carbon fiber reinforced TaN material, and the surface layer is a SiC layer shell-coated short silicon carbide fiber reinforced HfB2. The performance results show that the composite coating proposed by the present invention and its preparation method are also applicable to boride and nitride ultra-high temperature ceramic materials. In Example 6, compared with Example 1, the bottom layer is a BN layer shell-coated short carbon fiber reinforced HfC, and the surface layer is a SiC layer shell-coated short silicon carbide fiber reinforced HfC. The bonding strength of the composite coating is still not less than 60MPa, the porosity is still less than 10%, and the oxyacetylene ablation rate at 2000°C is still less than 1×10 -3 mm / s; In Example 7, an appropriate amount of yttrium aluminum garnet powder is added to the base layer and the surface layer coating, which can further improve the bonding strength and anti-oxidation and ablation performance of the composite coating and reduce the porosity compared with Example 1.

[0153] Corresponding to the embodiment, in Comparative Example 1, a chopped carbon fiber reinforced HfC / chopped silicon carbide fiber reinforced HfC composite coating of the same thickness as in Example 1 was prepared by atmospheric plasma spraying. Due to the limitations of the atmospheric plasma spraying process itself, the beam has poor ability to heat the powder and poor powder spreading ability, resulting in a relatively large porosity of the prepared composite coating, and the coating bonding strength and ablation resistance are relatively poor. In Comparative Example 2, HfC spraying powder without chopped fiber reinforcement was used to prepare a pure HfC coating using low-pressure plasma spraying technology. After the chopped fibers were removed from the coating, the coating's bonding strength and ablation resistance were both reduced. In Comparative Example 3, chopped carbon fiber reinforced HfC powder without shell coating was used to prepare a chopped carbon fiber reinforced HfC single-layer coating using low-pressure plasma spraying technology. Compared with Comparative Example 2, the bonding strength between the coating and the substrate was improved, but the ablation resistance was still relatively poor. In Comparative Example 4, a single-layer coating of chopped silicon carbide fiber-reinforced HfC powder without a shell coating was prepared using low-pressure plasma spraying technology. The coating exhibited good ablation resistance but low bonding strength. In Comparative Example 5, a single-layer coating was prepared using chopped carbon fiber-reinforced HfB2 powder. Compared to Comparative Example 2, the bonding strength between the coating and the substrate was improved, but the ablation resistance was poor. This indicates that a single-layer coating can only optimize either the bonding strength or the oxidation resistance and ablation resistance of the ultra-high temperature ceramic material, and the overall improvement effect is significantly lower than that of the composite coating. In Comparative Examples 6 to 8, although a low-pressure plasma spraying process was adopted, the composite coatings were respectively composed of chopped carbon fiber reinforced HfC / chopped silicon carbide fiber reinforced HfC, chopped carbon fiber reinforced HfC / chopped silicon carbide fiber reinforced HfC coated with a PyC layer shell, and chopped silicon carbide fiber reinforced HfC / SiC layer shell coated with a chopped carbon fiber reinforced HfC. Such coating compositions result in lower bonding strength and / or antioxidant and ablation resistance of the composite coatings. In Comparative Example 9, the amount of small-particle yttrium aluminum garnet powder added to the base and surface coatings is excessive. Compared with Example 7, although the overall porosity of the composite coating is reduced, the bonding strength and antioxidant and ablation resistance of the coating are reduced, and the overall performance of the composite coating is reduced.

[0154] By comparing the data of the embodiments and the comparative examples, it can be clearly seen that the composite coating of ultra-high temperature ceramic bottom layer reinforced by chopped carbon fiber coated with a shell / ultra-high temperature ceramic surface layer reinforced by chopped silicon carbide fiber coated with a shell prepared by the present invention is significantly superior to traditional coatings in terms of bonding strength, porosity and ablation resistance. This composite coating not only improves the bonding strength with the ceramic-based composite material, but also improves the high-temperature oxidation and ablation resistance of the ceramic-based composite material.

[0155] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials, characterized by: The high bonding strength, anti-oxidation and ablation composite coating comprises, from the ceramic matrix composite material outward, a layer shell-coated short carbon fiber reinforced ultra-high temperature ceramic bottom coating and a layer shell-coated short silicon carbide fiber reinforced ultra-high temperature ceramic top coating; The shell material in the shell-coated chopped carbon fibers and the shell-coated chopped silicon carbide fibers is one or more of pyrolytic carbon, silicon carbide, and boron nitride; The ultra-high temperature ceramics in the ultra-high temperature ceramic bottom coating and the ultra-high temperature ceramic surface coating are one or more of carbides, borides and nitrides with high melting points.

2. The high bonding strength, anti-oxidation and ablation composite coating according to claim 1, characterized in that: The shell-coated chopped carbon fibers are prepared by depositing a shell with a thickness of 100 to 500 nm on the surface of the carbon fibers using a chemical vapor deposition method to obtain shell-coated carbon fibers, and then cutting the shell-coated carbon fibers. The shell-coated chopped silicon carbide fiber is prepared by depositing a shell with a thickness of 100 to 500 nm on the surface of the silicon carbide fiber using a chemical vapor deposition method to obtain the shell-coated silicon carbide fiber, and then cutting the shell-coated silicon carbide fiber.

3. The high bonding strength, anti-oxidation and ablation composite coating according to claim 2, characterized in that: The length of the shell-coated chopped carbon fibers and / or the shell-coated chopped silicon carbide fibers is 1 μm to 10 μm, and the diameter is 0.2 μm to 2 μm.

4. The high bonding strength, anti-oxidation and ablation composite coating according to claim 1, characterized in that: The carbide is one or more of silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide and niobium carbide; the boride is one or more of zirconium boride, hafnium boride, tantalum boride, titanium boride and niobium boride; the nitride is one or more of zirconium nitride, hafnium nitride, tantalum nitride, titanium nitride and niobium nitride.

5. The high bonding strength, anti-oxidation and ablation composite coating according to claim 1, characterized in that: The shell-coated short carbon fiber reinforced ultrahigh temperature ceramic bottom layer coating and the shell-coated short silicon carbide fiber reinforced ultrahigh temperature ceramic top layer coating are respectively formed on the surface of the ceramic matrix composite material by low-pressure plasma spraying using shell-coated short carbon fiber reinforced ultrahigh temperature ceramic powder and shell-coated short silicon carbide fiber reinforced ultrahigh temperature ceramic powder as spraying materials; The ultrahigh temperature ceramic powder reinforced by shell-coated chopped carbon fibers is compounded by shell-coated chopped carbon fibers and ultrahigh temperature ceramic powder through a spray granulation method; The ultra-high temperature ceramic powder reinforced by layer shell-coated chopped silicon carbide fibers is compounded by layer shell-coated chopped silicon carbide fibers and ultra-high temperature ceramic powder through a spray granulation method.

6. The high bonding strength, anti-oxidation and ablation composite coating according to claim 5, characterized in that: The median particle size D50 of the ultrahigh temperature ceramic powder reinforced by the shell-coated chopped carbon fibers and / or the ultrahigh temperature ceramic powder reinforced by the shell-coated chopped silicon carbide fibers is 5 to 50 μm.

7. The high bonding strength, anti-oxidation and ablation composite coating according to claim 1, characterized in that: In the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic bottom coating, the mass ratio of the layer shell coated short carbon fiber to the ultra-high temperature ceramic is (0.2-9):1; In the layer shell coated short-cut silicon carbide fiber reinforced ultra-high temperature ceramic surface coating, the mass ratio of the layer shell coated short-cut silicon carbide fiber to the ultra-high temperature ceramic is (0.2-9):1; The thickness of the layer shell-coated ultra-high temperature ceramic bottom layer coating reinforced by chopped carbon fibers and / or the layer shell-coated ultra-high temperature ceramic top layer coating reinforced by chopped silicon carbide fibers is 50-500 μm.

8. The method for preparing a high-bonding-strength, anti-oxidation and ablation composite coating for ceramic-based composite materials according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) Grinding, cleaning and drying the ceramic matrix composite material to obtain a pretreated ceramic matrix composite material; (2) A layer-shell-coated short carbon fiber reinforced ultrahigh temperature ceramic bottom layer coating and a layer-shell-coated short silicon carbide fiber reinforced ultrahigh temperature ceramic top layer coating are sequentially prepared on the surface of the pretreated ceramic matrix composite material by a low-pressure plasma spraying method, thereby preparing the high bonding strength and anti-oxidation and ablation composite coating on the surface of the ceramic matrix composite material.

9. The preparation method according to claim 8, characterized in that: The density of the ceramic matrix composite material is 1.8-5.0 g / cm 3 ; The polishing is performed using sandpaper; The cleaning is ultrasonic cleaning in acetone and / or ethanol for 10 to 15 minutes; and / or The drying temperature is 100-150°C.

10. The preparation method according to claim 8, characterized in that: During the low-pressure plasma spraying process, the surface temperature of the pretreated ceramic matrix composite material is 600-1000° C. by using a plasma jet heating method; During the low-pressure plasma spraying process, the absolute pressure in the spraying chamber is 1×10 2 ~2×10 3 Pa; In the process of preparing the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic bottom layer coating and / or the layer shell coated short silicon carbide fiber reinforced ultra-high temperature ceramic surface layer coating, argon and helium are used as plasma gases, the argon flow rate is 20~50L / min, the helium flow rate is 10~40L / min, the spraying distance is 400~1000mm, the rotation speed of the turntable is 0~20r / min, the arc voltage of the low-pressure plasma spraying equipment is 20~40V, the arc current is 800~1600A, and the powder feeding rate of the layer shell coated short carbon fiber reinforced ultra-high temperature ceramic powder and / or the layer shell coated short silicon carbide fiber reinforced ultra-high temperature ceramic powder is 10~20g / min.

11. The preparation method according to claim 8, characterized in that: The bonding strength of the high bonding strength anti-oxidation and ablation composite coating is not less than 50 MPa; The porosity of the high bonding strength anti-oxidation and ablation composite coating is less than 10%; The linear ablation rate of the high-bonding-strength, anti-oxidation and ablation composite coating in an oxyacetylene ablation test at a coating surface temperature of 2000°C is less than 1×10 -3 mm / s.

Images