A zirconium carbide-silicon carbide coating on a carbon-carbon composite material and a method of making the same

Abstract

The application discloses a kind of C / C composite material surface ZrC-SiC coating and preparation method thereof, it is related to C / C composite material surface coating preparation technical field.The method includes the following steps: C / C composite material is sequentially cleaned with distilled water and alcohol, then drying;Carry out micro-oxidation;Buried in coating powder, heat, heat preservation, and C / C composite material surface ZrC-SiC coating is prepared.The application simultaneously introduces two kinds of ceramics by precursor conversion method and in-situ reaction method, only needs once high-temperature heat treatment, compared with multiple high-temperature heat treatment, greatly reduce the damage of C / C composite material itself, shorten the test cycle, also reduce cost.The application directly uses PZC in surface coating technology, provides a new idea for its application in the field of high-temperature resistant and ablation-resistant C / C composite material.The application solves the problems of complex coating preparation process, long cycle and high energy consumption in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of surface coatings of C / C composite materials, and in particular to a ZrC-SiC coating on the surface of a C / C composite material and a preparation method thereof. Background Art

[0002] Carbon / carbon (C / C) composites offer superior properties such as low density, high specific strength, high thermal conductivity, and low thermal expansion coefficient. Most notably, their strength increases with increasing temperature, rather than decreasing. Consequently, C / C composites are widely used in high-tech fields such as aviation, aerospace, and the military. However, C / C composites rapidly oxidize above 400°C, causing a significant degradation in various properties. This susceptibility to oxidation severely limits their application. Furthermore, in high-temperature aerospace environments, C / C composites not only experience oxidation but also withstand the impact and impact of high-velocity airflow and particles, placing even more stringent demands on their performance. Therefore, improving their high-temperature resistance and ablation resistance is a hot topic and a challenge for research both domestically and internationally.

[0003] Surface coating technology is one of the effective means to improve the high temperature resistance and ablation resistance of C / C composite materials. At present, the methods for preparing C / C composite material coatings mainly include: chemical vapor deposition method, brushing method, supersonic atmospheric plasma spraying method and in-situ reaction method. Among them, the in-situ reaction method is simple to operate for preparing coatings, has no strict requirements on the shape of the sample, and the prepared coating has a uniform phase distribution, high interface bonding strength with the substrate, and good ablation resistance. However, in the process of preparing the inner coating and the outer coating in the existing technology, the C / C composite material needs to withstand multiple high temperature environments, and high temperature will damage the carbon fiber and cause permanent damage to the mechanical properties of the C / C composite material itself. In addition, separation and peeling problems are prone to occur between the inner coating and the outer coating. Therefore, there is an urgent need for a new surface coating preparation method. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a ZrC-SiC coating on the surface of a C / C composite material and a preparation method thereof, so as to solve the problems of complex coating preparation process, long cycle and high energy consumption in the prior art.

[0005] The present invention solves the above technical problems with the following technical solutions: Provided is a method for preparing a ZrC-SiC coating on the surface of a C / C composite material, comprising the following steps:

[0006] (1) The C / C composite material was washed with distilled water and alcohol in sequence, and then dried to obtain a pretreated C / C composite material;

[0007] (2) micro-oxidizing the pretreated C / C composite material obtained in step (1) to obtain a C / C composite material with a rough surface;

[0008] (3) burying the rough surface C / C composite material obtained in step (2) in the coating powder, heating it to 2000-2200°C, and keeping it warm for 1.5-2.5 hours to obtain a ZrC-SiC coating on the surface of the C / C composite material;

[0009] Wherein, in step (3), the coating powder is prepared by the following method: zirconium carbide ceramic precursor powder and SiC powder are mixed in a mass ratio of (46-72): (28-54), and ball milled to obtain the coating powder;

[0010] The zirconium carbide ceramic precursor powder is prepared by the following method: adding a ZrOCl2·8H2O solution dropwise to a polyvinyl alcohol solution, reacting, concentrating, and drying to obtain the zirconium carbide ceramic precursor powder.

[0011] On the basis of the above technical solution, the present invention can also be improved as follows:

[0012] Furthermore, in step (1), the density of the C / C composite material is 1.7-1.8 g / cm 3 .

[0013] Furthermore, in step (1), ultrasonic cleaning is performed with distilled water and alcohol in sequence.

[0014] Furthermore, in step (1), the product is dried at 70-100° C. for 12-24 hours.

[0015] Furthermore, in step (2), micro-oxidation is carried out at 850-950° C. for 4-6 minutes.

[0016] The beneficial effects of adopting the above further technical solution are: micro-oxidation treatment can roughen the surface of the C / C composite material, increase its specific surface area, and increase the contact area between the coating powder and the C / C composite material, which is conducive to the coating firmly covering the substrate.

[0017] Further, the temperature is increased to 850-950°C at a heating rate of 5-10°C / min.

[0018] Further, the temperature was increased to 850-950°C at a heating rate of 7.5°C / min.

[0019] Further, ball milling is performed at 300-500 r / min for 3-5 h.

[0020] Furthermore, the molar ratio of ZrOCl2·8H2O to polyvinyl alcohol is 1:(4.7-5.3).

[0021] Furthermore, in the ZrOCl2·8H2O solution, the molar ratio of ZrOCl2·8H2O to distilled water is 1:(150-190).

[0022] Furthermore, in the polyvinyl alcohol solution, the molar ratio of polyvinyl alcohol to distilled water is (4.7-5.3): (155-175).

[0023] Furthermore, the temperature of the polyvinyl alcohol solution is 80-90°C.

[0024] Further, the reaction is carried out at 80-90° C. for 2-8 hours.

[0025] Furthermore, rotary evaporator was used for rotary evaporation concentration.

[0026] Further, the mixture was kept at 70°C for 5 hours and then kept at 120°C for 5 hours to complete the drying process.

[0027] Furthermore, the polyvinyl alcohol solution was prepared by the following method: polyvinyl alcohol and distilled water were mixed, stirred and heated to 90° C., and kept warm for 1 hour to prepare the polyvinyl alcohol solution.

[0028] Furthermore, step (3) is performed in an argon atmosphere.

[0029] Furthermore, in step (3), the temperature is increased to 2000-2200°C at a heating rate of 5-10°C / min.

[0030] The present invention also provides a ZrC-SiC coating on the surface of a C / C composite material prepared by the preparation method of the ZrC-SiC coating on the surface of the C / C composite material.

[0031] The present invention has the following beneficial effects:

[0032] 1. SiC has a high melting point and high hardness, and exhibits excellent physical and chemical compatibility with C / C composites. Furthermore, the SiO2 formed upon oxidation has an extremely low oxygen diffusion coefficient, providing effective oxidation protection for C / C composites. ZrC also has a high melting point, high hardness, and high thermal conductivity. Furthermore, the ZrO2 formed upon oxidation not only has a high melting point but also low vapor pressure and thermal conductivity, providing excellent resistance to high-temperature oxidation and ablation. Therefore, ZrC-SiC was chosen as the coating system for C / C composites to achieve high-temperature and ablation resistance.

[0033] 2. Zirconium carbide ceramic precursors (PZC), as an emerging material, are becoming a key technology in the preparation of high-performance ZrC ceramics. Due to their high chemical activity, strong designability, controllable composition, and excellent forming properties, they hold broad application prospects in a wide range of fields, including aerospace, thin film materials, superhard tool materials, microelectronics, and nuclear energy storage materials. The application of PZC in the field of high-temperature and ablation-resistant C / C composites primarily focuses on matrix modification using the precursor impregnation and pyrolysis method. The precursor impregnation and pyrolysis process requires repeated impregnation-curing-pyrolysis cycles, significantly extending the process cycle and hindering rapid production and large-scale application. Furthermore, the process requires multiple high-temperature pyrolysis steps, resulting in high energy consumption and increased production costs. Furthermore, the direct application of PZC in surface coatings for C / C composites has rarely been reported.

[0034] 3. The present invention obtains a ZrC-SiC coating by simultaneously introducing ZrC ceramics and SiC ceramics through micro-oxidation treatment of the surface of the C / C composite material, a precursor conversion method, and an in-situ reaction method. The C / C composite material of the present invention comprises only one layer of coating. The good physicochemical compatibility of the SiC in the coating with the C / C composite material, as well as the rough surface of the C / C composite material, make the coating less likely to peel off. In the process of preparing the ZrC-SiC coating, PZC is first thermally decomposed to form ZrO2 and C, which then undergoes a carbothermal reduction reaction to form ZrC; wherein, a portion of the ZrO2 undergoes a carbothermal reduction reaction with the C / C composite material to form ZrC; finally, the ZrC and SiC are co-sintered to form the ZrC-SiC coating. The coating preparation process is a solid-phase reaction process.

[0035] 4. This invention utilizes micro-oxidation to create a rough layer on the surface of a C / C composite material. Using PZC (zirconium carbide ceramic precursor powder) as the ZrC raw material, the ZrC ceramic and SiC ceramic are simultaneously introduced through precursor conversion and in-situ reaction methods, ultimately producing a ZrC-SiC ceramic coating on the C / C composite surface. This invention directly utilizes PZC in surface coating technology, offering new insights into its application in the field of high-temperature resistance and ablation resistance of C / C composites.

[0036] 5. When the present invention adopts the precursor conversion method and the in-situ reaction method to simultaneously introduce two ceramics, only one high-temperature heat treatment is required. Multiple high-temperature heat treatments greatly reduce the damage to the C / C composite material itself, shorten the test cycle, and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a process flow chart of the present invention;

[0038] Figure 2 This is a macroscopic photograph of the ZrC-SiC coating prepared in Example 1 before ablation;

[0039] Figure 3 This is a macroscopic photograph of the ZrC-SiC coating after ablation prepared in Example 1;

[0040] Figure 4 This is the XRD spectrum of the ZrC-SiC coating prepared in Example 1 before ablation;

[0041] Figure 5 The XRD spectrum of the ZrC-SiC coating after ablation prepared in Example 1;

[0042] Figure 6 This is a microscopic morphology of the ZrC-SiC coating after ablation obtained in Example 1;

[0043] Figure 7 The surface temperature variation curve of the ZrC-SiC coating prepared in Example 1 during the ablation process;

[0044] Figure 8 Surface temperature variation curve of the ZrC-SiC coating prepared in Example 2 during the ablation process;

[0045] Figure 9 This is the surface temperature change curve of the ZrC-SiC coating prepared in Example 3 during the ablation process. DETAILED DESCRIPTION

[0046] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not intended to limit the scope of the invention. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0047] In the following examples and comparative examples, zirconium carbide ceramic precursor powder (PZC powder) was prepared by the following method:

[0048] According to the molar ratio of polyvinyl alcohol and distilled water of 5:165, the two were mixed, heated to 90°C while stirring, and kept warm for 1 hour to prepare a polyvinyl alcohol solution;

[0049] According to the molar ratio of ZrOCl2·8H2O to distilled water of 1:177, the mixture was stirred until dissolved to prepare ZrOCl2·8H2O solution;

[0050] The ZrOCl2·8H2O solution was added dropwise to a polyvinyl alcohol solution at 80°C (the molar ratio of ZrOCl2·8H2O to polyvinyl alcohol was 1:5), and the reaction was carried out at 80°C for 2 hours. The solution was concentrated using a rotary evaporator. The solution was dried at 70°C for 5 hours and then at 120°C for 5 hours to complete the drying process, thereby obtaining zirconium carbide ceramic precursor powder (PZC powder).

[0051] Example 1:

[0052] A ZrC-SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps: (See the process flow chart Figure 1 )

[0053] (1) Pretreatment: C / C composite material (density 1.75g / cm 3 ) were ultrasonically cleaned with distilled water and alcohol in sequence, and then dried at 90 °C for 18 h to obtain a pretreated C / C composite material;

[0054] (2) Construction of a rough layer: heating the tube furnace to an oxidation temperature of 900°C at a heating rate of 7.5°C / min, and micro-oxidizing the pretreated C / C composite material obtained in step (1) for 5 min to obtain a C / C composite material with a rough surface;

[0055] (3) Introduction of coating by precursor conversion method and in-situ reaction method:

[0056] The zirconium carbide ceramic precursor powder and SiC powder were mixed in a mass ratio of 63:37 and ball milled at 400 r / min for 4 h to prepare the coating powder.

[0057] The coating powder was placed in a graphite crucible, and then the rough surface C / C composite material obtained in step (2) was buried in the coating powder. The mixture was placed in a graphitization furnace, argon was introduced, and the temperature was increased to 2100°C at a heating rate of 7.5°C / min and kept at this temperature for 2h to obtain a ZrC-SiC coating on the surface of the C / C composite material.

[0058] Example 2:

[0059] A ZrC-SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0060] (1) Pretreatment: C / C composite material (density 1.8g / cm 3 ) were ultrasonically cleaned with distilled water and alcohol in sequence, and then dried at 100°C for 12 h to obtain a pretreated C / C composite material;

[0061] (2) Construction of a rough layer: heating the tube furnace to an oxidation temperature of 850°C at a heating rate of 5°C / min, and micro-oxidizing the pretreated C / C composite material obtained in step (1) for 6 minutes to obtain a C / C composite material with a rough surface;

[0062] (3) Introduction of coating by precursor conversion method and in-situ reaction method:

[0063] The zirconium carbide ceramic precursor powder and SiC powder were mixed in a mass ratio of 46:54 and ball milled at 300 r / min for 5 h to prepare the coating powder.

[0064] The coating powder was placed in a graphite crucible, and then the rough surface C / C composite material obtained in step (2) was buried in the coating powder. The mixture was placed in a graphitization furnace, argon was introduced, and the temperature was increased to 2200°C at a heating rate of 5°C / min. The temperature was kept at this temperature for 1.5 hours to obtain a ZrC-SiC coating on the surface of the C / C composite material.

[0065] Example 3:

[0066] A ZrC-SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0067] (1) Pretreatment: C / C composite material (density 1.7g / cm 3 ) were ultrasonically cleaned with distilled water and alcohol in sequence, and then dried at 70 °C for 24 h to obtain a pretreated C / C composite material;

[0068] (2) Construction of a rough layer: heating the tube furnace to an oxidation temperature of 950°C at a heating rate of 10°C / min, and micro-oxidizing the pretreated C / C composite material obtained in step (1) for 4 minutes to obtain a C / C composite material with a rough surface;

[0069] (3) Introduction of coating by precursor conversion method and in-situ reaction method:

[0070] The zirconium carbide ceramic precursor powder and SiC powder were mixed in a mass ratio of 72:28 and ball milled at 500 r / min for 3 h to prepare the coating powder.

[0071] The coating powder was placed in a graphite crucible, and then the rough surface C / C composite material obtained in step (2) was buried in the coating powder. The mixture was placed in a graphitization furnace, argon was introduced, and the temperature was increased to 2000°C at a heating rate of 10°C / min and kept at this temperature for 2.5h to obtain a ZrC-SiC coating on the surface of the C / C composite material.

[0072] Comparative Example 1:

[0073] A SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0074] In step (3), zirconium carbide ceramic precursor powder is not included, and the rest is the same as in Example 1.

[0075] Comparative Example 2:

[0076] A SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0077] In step (3), zirconium carbide ceramic precursor powder is not included, and the rest is the same as in Example 2.

[0078] Comparative Example 3:

[0079] A SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0080] In step (3), zirconium carbide ceramic precursor powder is not included, and the rest is the same as in Example 3.

[0081] Comparative Example 4:

[0082] A ZrC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0083] In step (3), no SiC powder is contained, and the rest is the same as in Example 1.

[0084] Comparative Example 5:

[0085] A ZrC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0086] In step (3), no SiC powder is contained, and the rest is the same as in Example 2.

[0087] Comparative Example 6:

[0088] A ZrC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0089] In step (3), no SiC powder is contained, and the rest is the same as in Example 3.

[0090] Comparative Example 7:

[0091] A ZrC-SiC coating on the surface of a C / C composite material, the preparation method of which comprises the following steps:

[0092] In step (3), zirconium carbide ceramic precursor powder and SiC powder are mixed in a mass ratio of 26:74, and the rest is the same as in Example 1.

[0093] Test example

[0094] 1. Linear Ablation Rate

[0095] The C / C composite surface coatings prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to a linear ablation rate test. The specific test method is as follows: According to the provisions of GJB323A-96, the coatings were tested for ablation resistance using an oxyacetylene flame. The gases used for the oxyacetylene flame test were O2 and C2H2, and the flame heat flux density was 2.38 MW / m 2The sample (Φ28×8mm) was placed vertically to the oxyacetylene flame, with a distance of 10mm between the sample and the nozzle tip and a nozzle tip diameter of 2mm. The ablation time was 60s. During the ablation process, the surface temperature of the sample was measured by an infrared thermometer. The thickness change rate (linear ablation rate) before and after ablation of the sample was used to evaluate its ablation resistance, and the calculation formula was: R d = (d0-d t ) / t; where R d is the sample line ablation rate, μm / s; d0 is the original thickness of the sample, μm; d t is the thickness of the sample after ablation, μm; t is the ablation time, s. The results are shown in Table 1.

[0096] Table 1 Linear ablation rates of Examples 1-3 and Comparative Examples 1-7

[0097]

[0098] As shown in Table 1, the linear ablation rate of the ZrC-SiC coating on the surface of the C / C composite material prepared in Example 1 is 0.861 μm / s, which is 49% lower than the linear ablation rate of the SiC coating on the surface of the C / C composite material in Comparative Example 1 under the same process of 1.702 μm / s.

[0099] The linear ablation rate of the ZrC-SiC coating on the surface of the C / C composite material prepared in Example 2 is 1.227 μm / s, which is 31% lower than the linear ablation rate of the SiC coating on the surface of the C / C composite material in Comparative Example 2 under the same process of 1.789 μm / s.

[0100] The linear ablation rate of the ZrC-SiC coating on the surface of the C / C composite material prepared in Example 3 is 1.400 μm / s, which is 26% lower than the linear ablation rate of the SiC coating on the surface of the C / C composite material prepared in Comparative Example 3 under the same process of 1.903 μm / s.

[0101] The ZrC coatings on the surfaces of the C / C composite materials prepared in Comparative Examples 4, 5 and 6 failed to completely cover the composite matrix, and the coatings were porous and easily peeled off. Therefore, the oxyacetylene ablation test could not be performed.

[0102] When the ZrC-SiC coating on the C / C composite material prepared in Comparative Example 7 was subjected to a 30-second oxyacetylene ablation test, the linear ablation rate reached 1.567 μm / s, exceeding the 60-second linear ablation rate of Examples 1-3 of this application. The composite substrate was exposed, and the coating had failed.

[0103] 2. The characteristics of the products obtained in Examples 1-3 are basically the same. Taking Example 1 as an example, the following tests are performed:

[0104] 1. Macroscopic photos of the ZrC-SiC coating on the surface of the C / C composite material prepared in Example 1 before and after ablation were observed. The results are shown in Figure 2-Figure 3 .

[0105] Depend on Figure 2 It can be seen that before ablation, the ZrC-SiC coating evenly and completely covers the surface of the C / C composite material without obvious cracks and pores.

[0106] Depend on Figure 3 It can be seen that after ablation, a large area of ​​discontinuous white matter appeared on the surface of the sample, and no obvious carbon matrix was exposed, indicating that the coating effectively protected the C / C composite material.

[0107] 2. The XRD spectra of the ZrC-SiC coating on the surface of the C / C composite material prepared in Example 1 before and after ablation were tested. The results are shown in Figure 4-Figure 5 .

[0108] Depend on Figure 4 It can be seen that before ablation, ZrC and SiC can be detected on the surface of the sample, but no C is detected, indicating that the C / C composite material has been completely covered by the ZrC-SiC coating.

[0109] Depend on Figure 5 After ablation, the surface phases of the sample are ZrO2, SiO2, and ZrSiO4. ZrC and SiC oxidize to form ZrO2 and SiO2, respectively; some ZrO2 reacts with SiO2 to form ZrSiO4. The embedding of ZrSiO4 within ZrO2 and SiO2 enhances the coating's ablation resistance. Furthermore, the absence of carbon indicates that the coating has not failed.

[0110] 3. The microscopic morphology of the ZrC-SiC coating on the surface of the C / C composite material obtained in Example 1 after ablation was observed. The results are shown in FIG. Figure 6 . Figure 6 In the figure, (a), (b), and (c) are BSE (backscattered electron images in SEM) photos; (d) and (e) are SEM photos.

[0111] Depend on Figure 6 After ablation, the sample surface is characterized by a distribution of white and gray phases. The glassy gray phase is continuous, interspersed with small pores resulting from coating oxidation. The white phase is mostly distributed above the gray phase, with some scattered within it. No obvious exposed carbon matrix is ​​observed on the sample surface, indicating that the coating effectively protects the C / C composite.

[0112] 4. The surface temperature change curves of the ZrC-SiC coating on the surface of the C / C composite material prepared in Examples 1-3 during the ablation process were detected. The detection method is as follows: the surface temperature of the sample during the ablation process is measured with an infrared thermometer, the corresponding time is recorded and plotted. The results are shown in FIG. Figure 7-Figure 9 .

[0113] Depend on Figure 7 As can be seen, the sample surface temperature rises rapidly within the first 20 seconds of ablation; thereafter, the temperature rises more slowly. During the ablation process, the maximum surface temperature reaches 1994.3°C. This indicates that the sample surface can withstand high-temperature ablation environments of approximately 2000°C.

[0114] Depend on Figure 8 It can be seen that within the first 20 seconds of ablation, the sample surface temperature rises rapidly, then slowly rises to a stable temperature. During the ablation process, the maximum temperature of the sample surface reaches 2008.5°C.

[0115] Depend on Figure 9 It can be seen that within the first 15 seconds of ablation, the sample surface temperature rises rapidly; after that, the temperature remains stable. During the ablation process, the maximum temperature of the sample surface reaches 2192.8°C.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a ZrC-SiC coating on the surface of a C / C composite material, characterized in that: The following steps are involved: (1) The C / C composite material was washed with distilled water and alcohol in sequence, and then dried to obtain a pretreated C / C composite material; (2) micro-oxidizing the pretreated C / C composite material obtained in step (1) to obtain a C / C composite material with a rough surface; (3) burying the rough surface C / C composite material obtained in step (2) in the coating powder, heating it to 2000-2200°C, and keeping it warm for 1.5-2.5 hours to obtain a ZrC-SiC coating on the surface of the C / C composite material; Wherein, in step (3), the coating powder is prepared by the following method: zirconium carbide ceramic precursor powder and SiC powder are mixed in a mass ratio of (46-72): (28-54), and ball milled to obtain the coating powder; The zirconium carbide ceramic precursor powder is prepared by the following method: adding a ZrOCl2·8H2O solution dropwise to a polyvinyl alcohol solution, reacting, concentrating, and drying to obtain the zirconium carbide ceramic precursor powder; In step (2), micro-oxidation is carried out at 850-950°C for 4-6 minutes.

2. The method for preparing a ZrC-SiC coating on a C / C composite material according to claim 1, wherein: In step (1), the density of the C / C composite material is 1.7-1.8 g / cm 3 .

3. The method for preparing a ZrC-SiC coating on a C / C composite material according to claim 1, wherein: In step (1), drying is performed at 70-100°C for 12-24 hours.

4. The method for preparing a ZrC-SiC coating on a C / C composite material according to claim 1, wherein: Ball mill at 300-500 r / min for 3-5 hours.

5. The method for preparing a ZrC-SiC coating on a C / C composite material according to claim 1, wherein: Step (3) is carried out in an argon atmosphere.

6. The method for preparing a ZrC-SiC coating on a C / C composite material according to claim 1, wherein: In step (3), the temperature is increased to 2000-2200°C at a heating rate of 5-10°C / min.

7. A ZrC-SiC coating on the surface of a C / C composite material obtained by the method for preparing a ZrC-SiC coating on the surface of a C / C composite material according to any one of claims 1 to 6.

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