An anti-ablation coating based on the morphological effect of rod-shaped yttrium oxide and its preparation method

Abstract

This application relates to the field of carbon-based material coating technology, and particularly to an anti-ablation coating based on the rod-shaped yttrium oxide morphology effect and its preparation method. The method includes the following steps: S1: Using yttrium salt as the yttrium source, rod-shaped Y₂O₃ powder is prepared by hydrothermal method and pH adjustment; S2: The rod-shaped Y₂O₃ powder is mixed with ZrC powder and SiC powder to obtain a composite powder; S3: The composite powder is coated onto the surface of a carbon substrate and sintered by spark plasma to prepare a Y₂O₃-modified ZrC-SiC anti-ablation coating. By synthesizing rod-shaped Y₂O₃ powder via hydrothermal method and introducing it into the ZrC-SiC coating, the rod-shaped Y₂O₃ exerts a synergistic effect of chemical and physical action during the ablation process. The chemical stabilization reduces defects caused by phase transitions, providing a structural basis for physical reinforcement; the physical reinforcement improves the structural integrity of the coating, allowing the chemical stabilization effect to continue.

Description

Technical Field

[0001] This application relates to the field of carbon-based material coating technology, and in particular to an anti-ablation coating based on the rod-shaped yttrium oxide morphology effect and its preparation method. Background Technology

[0002] Carbon-based materials possess low density, high melting point, and good thermal stability, making them promising candidates for use in ultra-high temperature hot-end components such as nose cones, wing edges, and rocket engine nozzles in hypersonic vehicles. However, carbon-based materials are easily oxidized to CO / CO2 in aerobic environments above 400 °C, leading to performance degradation and making it difficult to maintain long-term service in high-temperature aerobic environments.

[0003] Preparing ablation-resistant coatings on the surface of carbon-based materials is an effective way to improve their high-temperature stability. ZrC-SiC ceramic coatings are an important system in this regard: ZrC has a melting point as high as 3540 ℃, possesses high-temperature strength and high thermal conductivity; the SiO2 glass phase generated by SiC oxidation can flow at high temperatures and fill pores, forming a dense barrier layer with self-healing capabilities. However, as the service temperature extends above 1700 ℃, ZrC-SiC coatings face two problems: First, under high-temperature and low-oxygen partial pressure environments, SiC may transform from passive oxidation to active oxidation, generating gaseous SiO instead of dense SiO2, leading to the failure of the protective layer; second, the ZrO2 oxidation product undergoes a martensitic phase transformation from tetragonal to monoclinic during cooling, accompanied by a volume expansion of about 3% to 5%, and repeated phase transformations can easily cause the coating to crack or even peel off.

[0004] To address the aforementioned issues, researchers have attempted to modify ZrC-SiC coatings by introducing rare earth oxides. Y₂O₃, in particular, can improve the high-temperature ablation resistance of the coating to some extent by stabilizing the ZrO₂ crystal structure and reacting with SiO₂ to form a yttrium silicate glass layer with low oxygen permeability. However, the Y₂O₃ currently used for modifying ZrC-SiC coatings is mostly commercially available powder, which generally suffers from poor sintering activity, making it difficult to achieve densification of the ceramic coating. Furthermore, traditional coating preparation methods suffer from drawbacks such as long processing times, high temperatures, and demanding equipment requirements.

[0005] Therefore, how to obtain highly active Y2O3 powder to achieve densification of ZrC-SiC ceramic coatings and further improve the coatings' resistance to ablation in ultra-high temperature oxidizing environments is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application provides an anti-ablation coating based on the rod-shaped yttrium oxide morphology effect and its preparation method, which enables Y2O3 to simultaneously exert a synergistic effect of chemical phase transformation stabilization and physical enhancement in the ZrC-SiC anti-ablation coating, thereby improving the coating's anti-ablation performance.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: A method for preparing an ablation-resistant coating based on the morphological effect of rod-shaped yttrium oxide includes the following steps: S1: Using yttrium salt as the yttrium source, rod-shaped Y2O3 powder was prepared by adjusting the pH value through a hydrothermal method. S2: Mix rod-shaped Y2O3 powder with ZrC powder and SiC powder to obtain composite powder; S3: The composite powder is covered on the surface of the carbon matrix and then sintered by spark plasma to prepare a Y2O3 modified ZrC-SiC ablation-resistant coating.

[0008] Further, the yttrium source is Y(NO3)3·6H2O, and step S1 includes: S101: Dissolve Y(NO3)3·6H2O in deionized water to obtain Y(NO3)3·6H2O solution; S102: Add ammonia to the Y(NO3)3·6H2O solution to adjust the pH to 8~9; S103: The precursor is obtained by hydrothermal reaction at 170~190 ℃ for 7~9 h, followed by separation, washing and drying. S104: Rod-shaped Y2O3 powder is obtained by calcining the precursor.

[0009] Further, in step S102, the pH is adjusted to 9.

[0010] Furthermore, in step S2, the content of rod-shaped Y2O3 powder is 5~15 vol%.

[0011] Further, in step S2, the rod-shaped Y2O3 powder is mixed with ZrC powder and SiC powder by ball milling. The ball milling speed is 300~360 r / min and the ball milling time is 8~12 h.

[0012] Furthermore, in step S3, the spark plasma sintering is carried out under a vacuum atmosphere, with a heating rate of 80~120 ℃ / min, a sintering temperature of 1650~1750 ℃, an axial pressure of 45~55 MPa, and a holding time of 8~12 min.

[0013] Furthermore, step S3 also includes: Polish the surface of the carbon substrate with sandpaper, ultrasonically clean it with anhydrous ethanol for 20-40 minutes, and then dry it.

[0014] This application also provides the preparation method described above for preparing an ablation-resistant coating based on the rod-shaped yttrium oxide morphology effect.

[0015] This application also provides the application of the anti-ablation coating based on the rod-shaped yttrium oxide morphology effect as described above in high-temperature hot-end components.

[0016] In summary, the beneficial effects of this application include: 1. This application synthesizes rod-shaped Y2O3 powder via a hydrothermal method. When introduced into a ZrC-SiC coating, the rod-shaped Y2O3 exhibits a synergistic effect of both chemical and physical action during the ablation process: In terms of chemical action, Y³… + Solid solution is incorporated into the ZrO2 lattice to form yttrium oxide-stabilized zirconium oxide (YO). 15 Zr0. 85 O1. 93 This cubic solid solution stabilizes the crystal structure of ZrO2 during high and low temperature cycling, reducing volume expansion caused by phase transformation and resulting defects such as porosity and cracks. In terms of physical effects, rod-shaped Y2O3 in the coating plays a role in toughening, grain boundary pinning, and reducing thermal conductivity. Toughening facilitates crack deflection and bridging, reducing brittle fracture of the coating during thermal shock; grain boundary pinning helps inhibit grain growth, improving the thermal stability of the coating; and reducing thermal conductivity helps concentrate heat on the coating surface, reducing heat transfer to the carbon matrix. The chemical and physical effects are exerted simultaneously by the same component, not simply a superposition of functions. Chemical stabilization reduces defects caused by phase transformation, providing a structural basis for physical reinforcement; physical reinforcement improves the structural integrity of the coating, allowing the chemical stabilization effect to continue.

[0017] 2. Under the same Y₂O₃ content, the coating using rod-shaped Y₂O₃ exhibits better ablation resistance than the coating using flake-shaped Y₂O₃. Experimental data shows that the mass ablation rate of the 5 vol% rod-shaped Y₂O₃ coating (5YZSB) is 0.083 × 10⁻⁶. - ³ g / s, linear ablation rate -1.95×10 - ³ mm / s; while the mass ablation rate of the 5 vol% flake Y₂O₃ coating (5YZSP) was 0.545 × 10⁻⁶ mm / s. - ³ g / s, linear ablation rate 1.58 × 10 - ³ mm / s. The mass ablation rate and linear ablation rate of the rod-shaped Y₂O₃ coating were both lower than those of the lamellar Y₂O₃ coating, indicating that the rod-shaped morphology has a positive effect on improving the ablation resistance of the coating.

[0018] 3. The introduction of rod-shaped Y2O3 is beneficial to improving the interfacial bonding between the coating and the carbon substrate. Cross-sectional SEM observation results show that there is obvious debonding between the ZS coating without added Y2O3 and the carbon substrate, with cracks and pores at the interface; while after introducing rod-shaped Y2O3, the difference in thermal expansion between the coating and the substrate is improved, the coating structure tends to be denser, and oxygen diffusion channels are effectively reduced.

[0019] 4. Rod-shaped Y₂O₃ promotes the fusion bonding of ceramic particles during ablation, resulting in a more continuous and dense protective film on the coating surface after ablation. Microscopic morphological observation after ablation shows that the ZS coating without added Y₂O₃ forms numerous dense cracks and many pores between particles on the ablated surface; after introducing rod-shaped Y₂O₃, the cracks on the coating surface become finer, the surface smoothness of the particles increases, and the degree of fusion bonding is improved, which helps to reduce oxygen diffusion channels and thus improves the coating's ablation resistance. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 A flowchart illustrating a method for preparing an anti-ablation coating based on the morphological effect of rod-shaped yttrium oxide, provided for this application; Figure 2 This is a flowchart illustrating the preparation method of Example 1 of this application; Figure 3 The XRD pattern of Y2O3 powder provided in this application; Figure 4 The images are SEM images of Y2O3 powder provided in this application; where a and b are the sheet-like Y2O3 powder (pH=7) prepared in Comparative Examples 2-4, and c and d are the rod-like Y2O3 powder (pH=9) prepared in Examples 1-3. Figure 5 XRD pattern of the Y2O3-ZrC-SiC coating provided in this application; Figure 6 The surface SEM images of the Y2O3-ZrC-SiC coating provided in this application are shown below; where a is the ZS coating (Comparative Example 1), b is the 5YZSP coating (Comparative Example 2), c is the 10YZSP coating (Comparative Example 3), d is the 15YZSP coating (Comparative Example 4), e is the 5YZSB coating (Example 2), f is the 10YZSB coating (Example 1), g is the 15YZSB coating (Example 3), h is the energy dispersive spectral analysis of each point of the 15YZSP coating, i is the energy dispersive spectral analysis of the 15YZSP coating, and j is the energy dispersive spectral analysis of the 15YZSB coating. Figure 7The cross-sectional SEM images of the Y2O3-ZrC-SiC coating provided in this application are shown below; where a is the ZS coating (Comparative Example 1), b is the 5YZSP coating (Comparative Example 2), c is the 10YZSP coating (Comparative Example 3), d is the 15YZSP coating (Comparative Example 4), e is the 5YZSB coating (Example 2), f is the 10YZSB coating (Example 1), g is the 15YZSB coating (Example 3), and h is the 10YZSB coating (Example 1). Figure 8 The ablation rate curve of the Y2O3-ZrC-SiC coating provided in this application; where a is the linear ablation rate and b is the mass ablation rate; Figure 9 The macroscopic surface morphology of the Y2O3-ZrC-SiC coating after ablation provided in this application; Figure 10 XRD patterns of the ablated surfaces of the Y2O3-ZrC-SiC coating provided in this application; where a is the YZSP coating (Comparative Examples 2-4) and b is the YZSB coating (Examples 1-3). Figure 11 The ablation temperature curves of the Y2O3-ZrC-SiC coating provided in this application; where a is the YZSP coating (Comparative Examples 2-4) and b is the YZSB coating (Examples 1-3). Figure 12 SEM morphology and energy dispersive spectroscopy analysis of the ablation surface of the Y2O3-ZrC-SiC coating provided in this application; wherein, a1~a2 is the ZS coating (Comparative Example 1), b1~b2 is the 5YZSP coating (Comparative Example 2), c1~c2 is the 10YZSP coating (Comparative Example 3), d1~d2 is the 15YZSP coating (Comparative Example 4), e1~e2 is the 5YZSB coating (Example 2), f1~f2 is the 10YZSB coating (Example 1), g1~g2 is the ablation transition zone of the 15YZSB coating (Example 3), h1~h2 is the ablation center zone of the 15YZSB coating (Example 3), i is the energy dispersive spectroscopy of each region, j is the energy dispersive spectroscopy of the 15YZSP coating, and k is the energy dispersive spectroscopy of the 15YZSP coating. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions of this application will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] Reference Figure 1 This application provides a method for preparing an ablation-resistant coating based on the morphological effect of rod-shaped yttrium oxide, comprising the following steps: S1: Using yttrium salt as the yttrium source, rod-shaped Y2O3 powder was prepared by adjusting the pH value through a hydrothermal method. S2: Mix rod-shaped Y2O3 powder with ZrC powder and SiC powder to obtain composite powder; S3: The composite powder is covered on the surface of the carbon matrix and then sintered by spark plasma to prepare a Y2O3 modified ZrC-SiC ablation-resistant coating.

[0023] In step S1, by controlling the pH value during the hydrothermal reaction, Y2O3 crystals are oriented to grow along a specific crystal direction, resulting in Y2O3 powder with a rod-like morphology. During subsequent sintering and high-temperature service, the rod-shaped Y2O3 utilizes its one-dimensional structure to exert a synergistic effect of toughening, grain boundary pinning, reducing thermal conductivity, and stabilizing the ZrO2 crystal form.

[0024] In step S2, the rod-shaped Y2O3 powder is ball-milled and mixed with ZrC powder and SiC powder in a certain proportion to make the components uniformly dispersed and form a composite powder.

[0025] In step S3, spark plasma sintering (SPS) technology is used to achieve rapid densification of the coating at a lower temperature and in a shorter time, while maintaining the morphological characteristics of the rod-shaped Y2O3.

[0026] Specifically, the following embodiments and comparative examples are provided: Example 1 This embodiment preferably provides a method for preparing an ablation-resistant coating based on the rod-shaped yttrium oxide morphology effect, referring to... Figure 2 Specifically, it includes: (1) Preparation of rod-shaped Y2O3 powder 9.575 g of Y(NO3)3·6H2O was weighed and dissolved in 50 mL of deionized water. The solution was stirred and mixed thoroughly to prepare a 0.5 mol / L Y(NO3)3·6H2O solution. Ammonia was added dropwise to the solution using a forward titration method while continuously stirring to adjust the pH to 9. After stirring for 30 min to ensure complete homogenization, the solution was transferred to a polytetrafluoroethylene-lined reactor, with a filling degree of approximately 70%. The reactor was sealed and subjected to a hydrothermal reaction at 180 °C for 8 h. After the reaction, the reactor was allowed to cool naturally to room temperature. The precursor precipitate was collected by centrifugation and washed three times each with deionized water and anhydrous ethanol, followed by drying at 80 °C for 24 h. The dried precursor was placed in an alumina crucible and heated to 700 °C in a muffle furnace at a heating rate of 5 °C / min. The mixture was calcined for 2 h and then cooled to room temperature in the furnace to obtain rod-shaped Y2O3 powder.

[0027] (2) Carbon matrix pretreatment A graphite sheet (20 mm in diameter, 4 mm in thickness, 1.8 g / cm³ in density, and 99.9% purity) was used as the carbon matrix. Its surface was polished with 300-grit diamond sandpaper to remove impurities and oil. The polished graphite sheet was then placed in anhydrous ethanol and ultrasonically cleaned for 30 min at room temperature, followed by drying at 110 ℃ for 5 h to obtain the pretreated carbon matrix.

[0028] (3) Preparation of composite powder ZrC and SiC powders were used as the matrix ceramic powders, with a ZrC to SiC volume ratio of 80:20. Rod-shaped Y₂O₃ powder was added to the ZrC-SiC matrix powder at a ratio of 10 vol%. Anhydrous ethanol was used as the solvent, and the mass ratio of milling balls, powder, and solvent was controlled at 2:1:1. The mixture was ball-milled for 10 h at 360 r / min using a planetary ball mill. After milling, the slurry was dried at 70 ℃ for 24 h, ground, and then passed through a 200-mesh sieve to obtain the Y₂O₃-ZrC-SiC composite powder.

[0029] (4) Preparation of anti-ablation coating Weigh 1 g of the above composite powder and spread it completely and evenly on the surface of the pretreated graphite sheet. Place the graphite sheet coated with the composite powder into a graphite mold lined with carbon paper, with the powder coating facing upwards. Place the mold into the cavity of a spark plasma sintering furnace (SPS) and heat it to 1700 °C at a heating rate of 100 °C / min under a vacuum atmosphere, holding it at 50 MPa for 10 min. After sintering, cool it to room temperature with the furnace, demold the sample, and polish the coating surface with 300-4000 grit sandpaper to obtain the ablation-resistant coating of Example 1 (denoted as 10YZSB).

[0030] Testing showed that the coating prepared in this embodiment had a thickness of approximately 400–500 μm. The coating and carbon substrate had good interfacial bonding, and no obvious defects such as debonding, cracks, or pores were observed. The coating surface was dense, and the ZrC, SiC, and Y2O3 phases were uniformly distributed.

[0031] Example 2 The preparation method in this embodiment differs from that in Example 1 in that the content of rod-shaped Y2O3 powder in step S3 is 5 vol%. The remaining steps and process parameters are the same as in Example 1. The resulting sample is denoted as 5YZSB.

[0032] Example 3 The preparation method of this embodiment differs from that of Example 1 in that the content of rod-shaped Y2O3 powder in step S3 is 15 vol%. The remaining steps and process parameters are the same as in Example 1. The obtained sample is denoted as 15YZSB.

[0033] Comparative Example 1 The preparation method of this comparative example differs from that of Example 1 in that Y₂O₃ powder is not added in step S3, and the volume ratio of ZrC to SiC remains 80:20. The remaining steps and process parameters are the same as in Example 1. The resulting sample is denoted as ZS.

[0034] Comparative Example 2 The preparation method of this comparative example differs from that of Example 1 in that: in step S1, the pH value of the solution is adjusted to 7, and after hydrothermal reaction, flake-like Y2O3 powder is obtained; in step S3, the content of flake-like Y2O3 powder is 5 vol%. The remaining steps and process parameters are the same as in Example 1. The obtained sample is denoted as 5YZSP.

[0035] Comparative Example 3 The preparation method of this comparative example differs from that of Example 1 in that: in step S1, the pH value of the solution is adjusted to 7, and after hydrothermal reaction, flake-like Y2O3 powder is obtained; in step S3, the content of flake-like Y2O3 powder is 10 vol%. The remaining steps and process parameters are the same as in Example 1. The obtained sample is denoted as 10YZSP.

[0036] Comparative Example 4 The preparation method of this comparative example differs from that of Example 1 in that: in step S1, the pH value of the solution is adjusted to 7, and after hydrothermal reaction, flake-like Y2O3 powder is obtained; in step S3, the content of flake-like Y2O3 powder is 15 vol%. The remaining steps and process parameters are the same as in Example 1. The obtained sample is denoted as 15YZSP.

[0037] Furthermore, performance tests and analyses were conducted on the above embodiments and comparative examples: 1. Powder characterization: X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed on the rod-shaped Y2O3 powder prepared in Example 1 and the sheet-shaped Y2O3 powder prepared in Comparative Example 2.

[0038] XRD analysis results show (refer to) Figure 3 The Y2O3 powders obtained by hydrothermal synthesis at pH=7 and pH=9 and calcination at 700 ℃ were all cubic Y2O3 with good crystallinity, consistent with the JCPDS standard card (PDF#43-1036). The diffraction peak intensity of Y2O3 increased synchronously with increasing pH value, indicating that increasing pH value helps to generate Y2O3 powder with higher crystallinity.

[0039] SEM analysis results show (refer to) Figure 4 Y2O3 powder synthesized under pH=7 exhibits a hexagonal plate-like structure; Y2O3 powder synthesized under pH=9 exhibits a hexagonal prism-like structure, growing along the c-axis.

[0040] 2. Characterization of coating microstructure XRD and SEM analyses were performed on the coatings prepared in each embodiment and comparative example.

[0041] XRD analysis results show (refer to) Figure 5 The main phases of each coating group were ZrC, SiC, and Y2O3, with no other impurity phases present. The diffraction peaks of each phase were sharp, indicating that the coating had good crystallinity. The content and microstructure of Y2O3 did not have a significant effect on the phase composition of the coating, but the intensity of the corresponding diffraction peaks gradually increased with the increase of Y2O3 content.

[0042] Surface SEM analysis results (refer to) Figure 6 The ZS coating (Comparative Example 1) has a relatively dense surface with no obvious pores or cracks, and is a dense composite coating structure formed by the accumulation of black phase (SiC) and white phase (ZrC). As the Y2O3 content increases, the distribution of each phase on the coating surface remains uniform.

[0043] The results of cross-sectional SEM analysis (refer to) Figure 7 The coating thicknesses of each group remained stable between 400 and 500 μm. Significant debonding was observed between the ZS coating (Comparative Example 1) and the carbon substrate, with cracks and pores present at the interface. These defects provided diffusion channels for oxygen during ablation. With the introduction of Y₂O₃, the difference in thermal expansion between the coating and the substrate was improved, and the coating structure gradually became denser, effectively reducing oxygen diffusion channels.

[0044] 3. Ablation resistance test The ablation resistance of each group of samples was tested using an OA-III type oxyacetylene ablation machine. The test method was in accordance with GJB323A-96 "Test Method for Ablation of Ablation Materials". The test parameters were: oxygen pressure 0.4 MPa, oxygen flow rate 0.24 L / s, acetylene pressure 0.095 MPa, acetylene flow rate 0.18 L / s, ablation time 60 s, and heat flux density 2380 kW / m².

[0045] The test results of mass ablation rate and linear ablation rate of each group of samples are as follows: Figure 8 As shown in Table 1: Table 1. Test results of mass ablation rate and linear ablation rate

[0046] Note in Table 1: Negative values ​​for mass ablation rate and linear ablation rate indicate that the sample gained weight or size during the ablation process due to the formation of an oxide protective layer.

[0047] As shown in Table 1, the mass ablation rate and linear ablation rate of the ZS coating are 0.432 × 10⁻⁶. - ³ g / s and 2.08 × 10 - ³ mm / s. After introducing 5 vol% rod-shaped Y₂O₃ (Example 2, 5YZSB), the mass ablation rate decreased to 0.083 × 10⁻⁶ mm / s. - ³g / s, the linear ablation rate decreased to -1.95×10 - ³ mm / s. After introducing 15 vol% rod-shaped Y₂O₃ (Example 3, 15YZSB), the mass ablation rate further decreased to -0.585 × 10⁻⁶ mm / s. - ³ g / s, linear ablation rate -1.12×10 - ³ mm / s. Compared with the same content of flake Y2O3 (5YZSP of Comparative Example 2 and 5YZSB of Example 2, 10YZSP of Comparative Example 3 and 10YZSB of Example 1, 15YZSP of Comparative Example 4 and 15YZSB of Example 3), the ablation resistance of rod-shaped Y2O3 modified coatings is better than that of flake-shaped Y2O3 modified coatings, indicating that the rod-shaped morphology has a positive effect on improving the ablation resistance of the coating.

[0048] 4. Surface analysis after ablation The macroscopic morphology observation results after ablation show (refer to) Figure 9 After ablation, all samples developed a white protective oxide layer on their surface. The presence of through-cracks on the ZS coating surface indicates a significant difference in thermal expansion coefficients between the oxide layer and the coating, making it prone to brittle fracture during thermal shock. With increasing Y₂O₃ content, the oxide layer tended to become more intact.

[0049] XRD analysis results after ablation (refer to) Figure 10 After ablation, the characteristic diffraction peaks of ZrC, SiC, and Y2O3 disappear, and are replaced by SiO2, ZrO2, ZrSiO4, and Y0. 15 Zr0. 85 O1. 93 The diffraction peaks indicate that a composite glass protective film has been formed on the coating surface. Y0. 15 Zr0. 85 O1. 93 The formation of Y³ + During the ablation process, solid solution enters the ZrO2 lattice to form yttrium-stabilized zirconium oxide (YSZ). This cubic solid solution can stabilize the crystal form of ZrO2 during high and low temperature cycling, reducing volume changes caused by phase transformation and defects such as pores and cracks.

[0050] Ablation temperature curve test results (refer to) Figure 11The results indicate that the center temperature of the ZS coating surface is approximately 2050 ℃. The introduction of yttrium oxide reduces the coating's thermal conductivity, concentrating heat on the coating surface and raising the surface temperature by approximately 200~400 ℃. This reduces heat transfer to the carbon matrix, which is beneficial for protecting the carbon matrix.

[0051] Microscopic morphology analysis results after ablation (refer to) Figure 12 The results showed that the ZS coating ablated surface formed numerous dense cracks, and the high-magnification morphology revealed that the surface was composed of a large number of irregularly shaped particles with numerous interparticle pores, failing to form a continuous and dense protective film. After introducing rod-shaped Y₂O₃, the cracks on the coating surface became finer, the surface smoothness of the particles increased, and the degree of fusion bonding improved, indicating that rod-shaped Y₂O₃ can promote the melting of ceramic particles, while simultaneously improving the melting process through Y³⁺. + Solid solution stabilizes the ZrO2 crystal structure, inhibits phase transformation, reduces the generation of defects such as cracks and pores, reduces oxygen diffusion channels, and improves the coating's resistance to ablation.

[0052] Based on the above properties, the ablation-resistant coating based on the rod-shaped yttrium oxide morphology effect prepared according to any of the methods in Examples 1 to 3 can be applied to the surface thermal protection of ultra-high temperature hot-end components. The aforementioned ultra-high temperature hot-end components include carbon structural material components that need to operate for a long time in a high-temperature oxygen environment, such as the nose cone and wing edges of hypersonic vehicles, rocket engine nozzles, throat liners, brake discs, heating elements, and high-temperature crucibles.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an ablation-resistant coating based on the morphological effect of rod-shaped yttrium oxide, characterized in that, Includes the following steps: S1: Using yttrium salt as the yttrium source, rod-shaped Y2O3 powder was prepared by adjusting the pH value through a hydrothermal method. S2: Mix rod-shaped Y2O3 powder with ZrC powder and SiC powder to obtain composite powder; S3: The composite powder is covered on the surface of the carbon matrix and then sintered by spark plasma to prepare a Y2O3 modified ZrC-SiC ablation-resistant coating.

2. The preparation method according to claim 1, characterized in that, The yttrium source is Y(NO3)3·6H2O, and step S1 includes: S101: Dissolve Y(NO3)3·6H2O in deionized water to obtain Y(NO3)3·6H2O solution; S102: Add ammonia to the Y(NO3)3·6H2O solution to adjust the pH to 8~9; S103: The precursor is obtained by hydrothermal reaction at 170~190 ℃ for 7~9 h, followed by separation, washing and drying. S104: Rod-shaped Y2O3 powder is obtained by calcining the precursor.

3. The preparation method according to claim 2, characterized in that, In step S102, the pH is adjusted to 9.

4. The preparation method according to claim 1, characterized in that, In step S2, the content of rod-shaped Y2O3 powder is 5~15 vol%.

5. The preparation method according to claim 1, characterized in that, In step S2, the rod-shaped Y2O3 powder is mixed with ZrC powder and SiC powder by ball milling. The ball milling speed is 300~360 r / min and the ball milling time is 8~12 h.

6. The preparation method according to claim 1, characterized in that, In step S3, the spark plasma sintering is carried out under a vacuum atmosphere, with a heating rate of 80~120 ℃ / min, a sintering temperature of 1650~1750 ℃, an axial pressure of 45~55 MPa, and a holding time of 8~12 min.

7. The preparation method according to claim 1, characterized in that, Step S3 also includes: Polish the surface of the carbon substrate with sandpaper, ultrasonically clean it with anhydrous ethanol for 20-40 minutes, and then dry it.

8. An ablation-resistant coating based on the rod-shaped yttrium oxide morphology effect is prepared by the preparation method according to any one of claims 1-7.

9. The application of the anti-ablation coating based on the rod-shaped yttrium oxide morphology effect as described in claim 8 in high-temperature hot-end components.

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