ZrC-ZrSi / SiC anti-oxidation coating on surface of carbon / carbon composite material and preparation method of ZrC-ZrSi / SiC anti-oxidation coating

Abstract

The invention provides a carbon / carbon composite material surface ZrC-ZrSi / SiC anti-oxidation coating and a preparation method thereof, and belongs to the technical field of material preparation.The method comprises the steps that a polished, cleaned and dried carbon / carbon composite material is placed in a constant-temperature area of a chemical vapor deposition furnace, a methyl trichlorosilane-H2-Ar system is used, a SiC coating is deposited on the surface of the carbon / carbon composite material, and a ZrC-ZrSi / SiC anti-oxidation coating is obtained; the uniform and compact SiC coating is obtained; the preparation method comprises the following steps: performing ultrasonic cleaning on a carbon / carbon composite material with a SiC coating, drying, placing in a constant-temperature area of a chemical vapor deposition furnace, placing Zr source powder in a low-temperature sublimation area of the chemical vapor deposition furnace, performing in-situ reaction on the SiC coating under negative pressure to obtain a ZrC-ZrSi coating, and positioning the ZrC-ZrSi coating on the SiC coating. According to the invention, ZrO2 generated in the oxidation process is utilized to reduce the fluidity of SiO2, improve the stability of an oxidation film, and avoid coating failure caused by airflow scouring of molten SiO2. The preparation temperature of the coating is low, the structure is compact, and meanwhile, the coating has excellent 1700 DEG C static and dynamic oxidation resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation, and particularly relates to a ZrC-ZrSi / SiC antioxidant coating on the surface of a carbon / carbon composite material and a preparation method thereof. Background Art

[0002] Due to advantages such as low density, low thermal expansion coefficient, high specific strength, high specific modulus, and the mechanical properties not decreasing but increasing with the increase of temperature, carbon / carbon (C / C) composite materials have become one of the materials with great development prospects in the field of ultra-high temperature thermal structure materials. However, C / C composite materials are extremely easy to oxidize in an aerobic environment at high temperatures (above 400 °C), and show extremely strong oxidation sensitivity with the increase of temperature. At present, the silicon-based ceramic coating technology is considered to be an important technology that can provide long-term effective thermal protection for C / C composite materials. Among them, the SiC coating prepared by chemical vapor deposition is considered to be an ideal antioxidant coating material because of its low preparation temperature, almost no mechanical damage to the substrate, controllable microstructure and uniformity, and the ability to generate SiO2 with crack healing effect at high temperatures.

[0003] However, in static and dynamic oxidation environments not lower than 1700 °C, the SiO2 formed by oxidation has a low viscosity and high fluidity, and is easily eroded and lost in the dynamic oxidation environment, resulting in its inability to provide effective protection for the C / C matrix. To address this problem, ultra-high temperature ceramic phases are often introduced into the SiC coating. The oxide skeletons (such as ZrO2, HfO2, etc.) formed by the oxidation of refractory metal elements (such as Zr, Hf, etc.) are used to slow down the erosion and loss of SiO2, and at the same time, the refractory metal elements are used to increase the viscosity of SiO2, improve the stability of SiO2, and thus improve the protective effect of the SiC coating on the matrix at high temperatures. In the literature "Q.M. Liu, J. Liu, X. G. Luan et al. Preparation of ZrC-SiC composite coatings by chemical vapor deposition and study of co-deposition mechanism[J]. Journal of Materials Science&Technology, 2019, 35(12):2942-2949.", a ZrC-SiC composite coating was prepared on the graphite surface by co-deposition using H2, Ar, CH4, ZrCl4, and MTS as raw materials through chemical vapor deposition. However, the coating growth mechanism involved in the co-deposition preparation of the coating is complex, with many influencing factors, and the regulation of deposition parameters is cumbersome and difficult. In the literature "X. Zhu, Y. Zhang, X. Qiang, et al. An oxidation protective coating prepared by SiC densifying HfB2-SiC skeleton for SiC-coated C / C composites at 1473, 1773, and 1973 K[J]. Corrosion Science, 2022, 207:110559.", a ceramic skeleton was first prepared by slurry brushing combined with high-temperature heat treatment, and then densified by CVD to prepare an HfB2-SiC coating. The results show that the introduction of HfB2 can improve the thermal protection effect of the coating, but the process steps are cumbersome, the heat treatment temperature is relatively high (about 1900 °C), and the controllability during the preparation of the ceramic skeleton is poor, and problems such as the coating cannot be densified due to the small pores in the ceramic skeleton, and the coating cannot provide effective protection for the matrix will occur.In Patent 1 "Chen Zhaoke, Xiong Xiang, Wang Xinshuang, Sun Wei, Wang Yalei, Huang Jie. Preparation method of ZrC-SiC coating on C / C composite material, ZL201510653315.0 [P]. 2017", the slurry brushing infiltration / dip coating-high temperature sintering method was used to prepare a ZrC-SiC coating on the surface of C / C composite material. That is, first, a Zr-Si-permeation aid-slag-forming agent ceramic slurry was brushed on the surface of C / C to prepare a pre-coating, and then high-temperature sintering was carried out in an argon atmosphere at 1990 °C - 2020 °C. However, the reaction temperature of this process is relatively high, and elements such as Zr / Si cause relatively large damage to the matrix during the infiltration process. In addition, the coating is prepared by the brushing process, and it is difficult to control the coating uniformity.

[0004] Therefore, in order to effectively protect C / C composite materials in static and dynamic oxidation environments not lower than 1700 °C, it is necessary to prepare a multi-phase antioxidant coating with uniform and dense structure, low preparation temperature, less damage to the matrix, and simple and controllable process. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for preparing a ZrC-ZrSi / SiC antioxidant and ablation-resistant coating on the surface of carbon / carbon composite materials, which solves the problems such as insufficient density, high preparation temperature, complex preparation process, and difficult regulation of coating uniformity in the prior art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a method for preparing a ZrC-ZrSi / SiC antioxidant coating on the surface of carbon / carbon composite materials, comprising the following steps: Place the polished, cleaned and dried carbon / carbon composite material in the constant temperature zone of a chemical vapor deposition furnace, and use the methyltrichlorosilane-H2-Ar system to deposit a SiC coating on the surface of the carbon / carbon composite material to obtain a uniform and dense SiC coating; Ultrasonically clean and then dry the carbon / carbon composite material with a SiC coating; Place the dried carbon / carbon composite material with a SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and at the same time place the Zr source powder in the low-temperature sublimation zone of the chemical vapor deposition furnace. Use H2 as the reaction gas and Ar as the dilution gas to carry out an in-situ reaction on the SiC coating under negative pressure to obtain a ZrC-ZrSi coating, and the ZrC-ZrSi coating is located on the SiC coating; Ultrasonically clean and dry the carbon / carbon composite material with a ZrC-ZrSi coating and a SiC coating multiple times to obtain a ZrC-ZrSi / SiC antioxidant coating, and the ZrC-ZrSi / SiC antioxidant coating covers the surface of the carbon / carbon composite material.

[0007] Furthermore, during the deposition process of the SiC coating, the deposition temperature is 1100°C to 1300°C, the Ar flow rate is 200 to 600 mL / min, the H2 flow rate is 200 to 1500 mL / min, the MTS flow rate is 0.07 to 0.3 g / min, and the pressure inside the furnace is controlled at 6 - 10 kPa.

[0008] Furthermore, during the in-situ reaction process of the ZrC-ZrSi coating, the reaction temperature is 1100 - 1250°C.

[0009] Furthermore, during the in-situ reaction process of the ZrC-ZrSi coating, the Ar flow rate is 100 - 500 mL / min, and the H2 flow rate is 500 - 2000 mL / min.

[0010] Furthermore, the Zr source is ZrCl4, the purity of ZrCl4 is 99.9 wt%, the particle size is 300 mesh, and the pressure inside the furnace is controlled at 2 - 8 kPa.

[0011] Furthermore, after the in-situ reaction of the ZrC-ZrSi coating is completed, the furnace is cooled down with the furnace and an inert atmosphere is maintained.

[0012] The above method for preparing the ZrC-ZrSi / SiC antioxidant coating on the carbon / carbon composite material surface can also be used to prepare the HfC-HfSi / SiC antioxidant coating, the TaC-TaSi / SiC antioxidant coating, or the TiC-TiSi / SiC antioxidant coating.

[0013] The present invention can also provide a ZrC-ZrSi / SiC antioxidant coating obtained based on the above method for preparing the ZrC-ZrSi / SiC antioxidant coating on the carbon / carbon composite material surface.

[0014] Furthermore, the thickness of the ZrC-ZrSi / SiC antioxidant coating is 2.5 - 8 μm.

[0015] The ZrC-ZrSi / SiC antioxidant coating on the carbon / carbon composite material surface obtained by the above method for preparing the ZrC-ZrSi / SiC antioxidant coating on the carbon / carbon composite material surface is used for antioxidant protection of the C / C matrix serving in an oxidation environment not lower than 1700°C.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention proposes a preparation method of a ZrC-ZrSi / SiC anti-oxidation and ablation coating, which is applicable to the preparation of other transition metal (such as Hf, Ta, Ti) modified SiC coatings and refractory metal carbide interfacial layers (HfC, TaC, TiC) on the surface of SiC fibers; By the in-situ reaction method, that is, using the transition metal source to diffuse into the constant temperature zone to chemically react with the SiC coating to prepare a ZrC-ZrSi coating with a certain thickness. This method can in-situ react with the SiC coating at a relatively low temperature (<1300 °C) to generate a dense and uniform ZrC-ZrSi composite coating. The preparation process causes little damage to the substrate, there is no chloride residue in the substrate, the process and operation are simple, and the deposition parameters are easy to control. The prepared coating presents a two-layer coating structure, with a dense and uniform SiC coating inside and a ZrC-ZrSi composite coating with a certain thickness outside, and its main function is to stabilize the generated SiO2. Through experiments with Zr, the thickness of the outer ZrC-ZrSi composite coating can be adjusted by controlling the reaction temperature, H2 flow rate, and reaction time. This coating has a good protective effect on C / C composites at 1700 °C, and at the same time has a good stabilizing effect on SiO2. After 432 h in a static air oxidation environment at 1700 °C, the weight loss rate is about 2%, while for the SiC coating, the weight loss rate reaches about 8% after 144 h. After oxidizing for 60 s in a dynamic oxidation environment at 1700 °C, the surface structure of the ZrC-ZrSi / SiC coating is complete, without obvious erosion marks, and the coating slightly increases in weight and thickness, with the mass increase rate and linear increase rate being 0.155 mg / s and 0.08 μm / s respectively, while for the SiC coating after oxidizing for 60 s, a large amount of SiO2 on the surface is eroded, and the mass loss rate and linear loss rate are 0.08 mg / s and 0.07 μm / s respectively. The introduction of Zr can significantly improve the protective performance of the SiC coating on the C / C substrate in static and dynamic oxidation environments at 1700 °C. The main reason is that the ZrO2 particles generated on the coating surface during the oxidation process can play a pinning role on the vitreous oxide film, and at the same time, the diffusion of Zr elements into SiO2 can improve the stability of SiO2. Description of the Drawings

[0017] Figure 1 It is the XRD pattern of the ZrC-ZrSi / SiC coating. As can be seen from the figure, the coating mainly contains three phases of ZrC, ZrSi, and SiC, indicating that Zr elements are introduced into the SiC coating.

[0018] Figure 2These are SEM images of the surface (a) and cross-section (b) of the ZrC-ZrSi / SiC coating. It can be seen from the surface that the coating surface mainly consists of ZrC and ZrSi, where ZrC is embedded in ZrSi. From the cross-section SEM photo, it can be seen that the SiC surface layer has been transformed into a uniform and dense ZrC-ZrSi layer.

[0019] Figure 3 These are the macroscopic surface morphologies of the unmodified CVD-SiC coating and the ZrC-ZrSi / SiC coating before and after dynamic oxidation; (a, b) unmodified CVD-SiC coating; (c, d) ZrC-ZrSi / SiC coating. It can be seen from the figure that after 60 s of oxidation in a dynamic oxidation environment at 1700 °C, the SiO2 glass film on the surface of the SiC coating is consumed, revealing the gray SiC layer, and ZrO2 is generated on the surface of the ZrC-ZrSi / SiC coating, and there is no obvious consumption trace of the oxide film.

[0020] Figure 4 These are the photos of the specimens with spalling of the reaction layer (a) and without the reaction layer (b). It can be seen from Figure (a) that after reacting for 4 h at 1300 °C, the coating cracked and peeled off, corresponding to Comparative Example 5; it can be seen from Figure (b) that when the H2 content is low, the surface of the coating is hardly reacted and the color remains gray, the same as the color of the SiC coating. Specific embodiments

[0021] The present invention will be further described in combination with the embodiments and the drawings: Example 1: Place the polished, cleaned and dried C / C composite material in the constant temperature zone of a chemical vapor deposition furnace, then evacuate to 7 kPa and perform a pressure holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1150 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during the heating period. After reaching the temperature, introduce H2 with a flow rate of 1000 mL / min and MTS with a flow rate of 0.1 g / min. After the deposition is completed, turn off H2 and MTS, turn off the power supply, keep the Ar flow rate at 200 mL / min and cool down with the furnace. After cooling to room temperature, the C / C composite material with a SiC coating can be obtained.

[0022] Weigh approximately 25 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with a SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Subsequently, evacuate to 3 kPa and conduct a pressure-holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1200 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 1000 mL / min and deposit for 2 h at 1200 °C. After the heat preservation ends, turn off H2, turn off the power supply, keep the Ar flow rate at 200 mL / min and cool down with the furnace. After cooling to room temperature, take out the sample, ultrasonically clean the deposited sample in deionized water multiple times, and then place the sample in an oven at 70 °C for drying treatment to finally obtain a ZrC-ZrSi / SiC coating ( Figure 2 ).

[0023] Example 2: Place the polished, cleaned, and dried C / C composite material in the constant temperature zone of a chemical vapor deposition furnace. Subsequently, evacuate to 6 kPa and conduct a pressure-holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1200 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 400 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 800 mL / min and MTS with a flow rate of 0.2 g / min. After the deposition ends, turn off H2 and MTS, turn off the power supply, keep the Ar flow rate at 400 mL / min and cool down with the furnace. After cooling to room temperature, a C / C composite material with a SiC coating can be obtained.

[0024] Weigh approximately 40 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with a SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Subsequently, evacuate to 4 kPa and conduct a pressure-holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1250 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 300 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 1200 mL / min and react for 6 h at 1250 °C. After the heat preservation ends, turn off H2, turn off the power supply, keep the Ar flow rate at 300 mL / min and cool down with the furnace. After cooling to room temperature, take out the sample, ultrasonically clean the deposited sample in deionized water multiple times, and then place the sample in an oven at 70 °C for drying treatment to finally obtain a ZrC-ZrSi / SiC coating.

[0025] Example 3: Place the polished, cleaned, and dried C / C composite material in the isothermal zone of a chemical vapor deposition furnace. Then evacuate to 10 kPa and conduct a pressure-holding test to check the airtightness of the equipment. If the airtightness is good, increase the temperature of the isothermal zone to 1100 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 1200 mL / min and MTS with a flow rate of 0.07 g / min. After the deposition is completed, turn off H2 and MTS, turn off the power supply, keep the Ar flow rate at 200 mL / min, and cool down with the furnace. After cooling to room temperature, a C / C composite material with a SiC coating can be obtained.

[0026] Weigh approximately 20 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with a SiC coating in the isothermal zone of the chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Then evacuate to 5 kPa and conduct a pressure-holding test to check the airtightness of the equipment. If the airtightness is good, increase the temperature of the isothermal zone to 1100 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 1500 mL / min and react at 1100 °C for 2 h. After the heat preservation is completed, turn off H2, turn off the power supply, keep the Ar flow rate at 200 mL / min, and cool down with the furnace. After cooling to room temperature, take out the sample, ultrasonically clean the deposited sample in deionized water multiple times, and then place the sample in an oven at 70 °C for drying treatment to finally obtain a ZrC-ZrSi / SiC coating.

[0027] Example 4: Place the polished, cleaned, and dried C / C composite material in the isothermal zone of a chemical vapor deposition furnace. Then evacuate to 8 kPa and conduct a pressure-holding test to check the airtightness of the equipment. If the airtightness is good, increase the temperature of the isothermal zone to 1300 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 150 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 1500 mL / min and MTS with a flow rate of 0.3 g / min. After the deposition is completed, turn off H2 and MTS, turn off the power supply, keep the Ar flow rate at 150 mL / min, and cool down with the furnace. After cooling to room temperature, a C / C composite material with a SiC coating can be obtained.

[0028] Weigh approximately 30 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with a SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Then evacuate to 2 kPa and conduct a pressure-holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1200 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 100 mL / min during heating. After reaching the temperature, introduce H2, with an H2 flow rate of 2000 mL / min, and react at 1200 °C for 3 h. After the heat preservation is completed, turn off H2, turn off the power supply, keep the Ar flow rate at 100 mL / min, and cool down with the furnace. After cooling to room temperature, take out the sample, ultrasonically clean the deposited sample in deionized water multiple times, and then place the sample in an oven at 70 °C for drying treatment to finally obtain a ZrC-ZrSi / SiC coating.

[0029] Example 5: Place the polished, cleaned, and dried C / C composite material in the constant temperature zone of a chemical vapor deposition furnace. Then evacuate to 6 kPa and conduct a pressure-holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1300 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 600 mL / min during heating. After reaching the temperature, introduce H2 with a flow rate of 200 mL / min and MTS with a flow rate of 0.1 g / min. After the deposition is completed, turn off H2 and MTS, turn off the power supply, keep the Ar flow rate at 600 mL / min, and cool down with the furnace. After cooling to room temperature, a C / C composite material with a SiC coating can be obtained.

[0030] Weigh approximately 30 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with a SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Then evacuate to 8 kPa and conduct a pressure-holding test on the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1150 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 500 mL / min during heating. After reaching the temperature, introduce H2, with an H2 flow rate of 500 mL / min, and react at 1150 °C for 4 h. After the heat preservation is completed, turn off H2, turn off the power supply, keep the Ar flow rate at 500 mL / min, and cool down with the furnace. After cooling to room temperature, take out the sample, ultrasonically clean the deposited sample in deionized water multiple times, and then place the sample in an oven at 70 °C for drying treatment to finally obtain a ZrC-ZrSi / SiC coating.

[0031] Example 6: To verify the applicability of the coating preparation process in the present invention, ZrCl4 in the in-situ reaction process was replaced with HfCl4, and the powder purity and particle size remained the same. The polished, cleaned, and dried C / C composite material was placed in the constant temperature zone of a chemical vapor deposition furnace. Subsequently, the furnace was evacuated to 10 kPa, and the airtightness of the equipment was checked by maintaining the pressure. If the airtightness was good, the temperature of the constant temperature zone was raised to 1150 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate was 200 mL / min during the heating process. After reaching the temperature, H2 with a flow rate of 1000 mL / min and MTS with a flow rate of 0.1 g / min were introduced. After the deposition was completed, H2 and MTS were turned off, the power was turned off, and the Ar flow rate was maintained at 200 mL / min while the furnace cooled down. After cooling to room temperature, the C / C composite material with a SiC coating could be obtained.

[0032] Weigh approximately 20 g of HfCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above-mentioned C / C composite material with a SiC coating in the constant temperature zone of the chemical vapor deposition furnace, and place the graphite crucible containing HfCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Subsequently, the furnace was evacuated to 5 kPa, and the airtightness of the equipment was checked by maintaining the pressure. If the airtightness was good, the temperature of the constant temperature zone was raised to 1150 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate was 200 mL / min during the heating process. After reaching the temperature, H2 was introduced, and the H2 flow rate was 1000 mL / min. The reaction was carried out at 1150 °C for 3 h. After the heat preservation was completed, H2 was turned off, the power was turned off, and the Ar flow rate was maintained at 200 mL / min while the furnace cooled down. After cooling to room temperature, the sample was taken out. The deposited sample was ultrasonically cleaned multiple times in deionized water, and then the sample was placed in an oven at 70 °C for drying treatment, and finally the HfC-HfSi / SiC coating was obtained.

[0033] Comparative Example 1: The main difference between this comparative example and the foregoing embodiment is that the in-situ reaction temperature is relatively high, and the coating is prone to peeling during the in-situ generation process. The polished, cleaned, and dried C / C composite material was placed in the constant temperature zone of a chemical vapor deposition furnace. Subsequently, the furnace was evacuated to 3 kPa, and the airtightness of the equipment was checked by maintaining the pressure. If the airtightness was good, the temperature of the constant temperature zone was raised to 1150 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate was 200 mL / min during the heating process. After reaching the temperature, H2 with a flow rate of 1200 mL / min and MTS with a flow rate of 0.1 g / min were introduced. After the deposition was completed, H2 and MTS were turned off, the power was turned off, and the Ar flow rate was maintained at 200 mL / min while the furnace cooled down. After cooling to room temperature, the C / C composite material with a SiC coating could be obtained.

[0034] Weigh approximately 40 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with an SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Subsequently, evacuate to 3 kPa and conduct a pressure holding test to check the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1300 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during heating. After reaching the temperature, introduce H2, with an H2 flow rate of 1200 mL / min, and deposit for 4 h at 1300 °C. After the heat preservation ends, turn off H2, turn off the power supply, keep the Ar flow rate at 200 mL / min, and cool down with the furnace. After cooling to room temperature, take out the sample. The surface coating of the obtained sample is severely cracked and peeled off. Refer to Figure 4 (a).

[0035] Comparative Example 2: The main difference between this comparative example and the foregoing embodiment is that almost no reaction gas hydrogen is introduced during the in-situ reaction process, and almost no reaction layer appears in the coating after the reaction. Place the polished, cleaned, and dried C / C composite material in the constant temperature zone of a chemical vapor deposition furnace. Subsequently, evacuate to 3 kPa and conduct a pressure holding test to check the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1150 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during heating. After reaching the temperature, introduce H2 and MTS with flow rates of 1000 mL / min and 0.2 g / min respectively. After the deposition ends, turn off H2 and MTS, turn off the power supply, keep the Ar flow rate at 200 mL / min, and cool down with the furnace. After cooling to room temperature, a C / C composite material with an SiC coating can be obtained.

[0036] Weigh approximately 40 g of ZrCl4 powder with a particle size of 300 mesh and place the powder in a graphite crucible. Place the above C / C composite material with an SiC coating in the constant temperature zone of a chemical vapor deposition furnace, and place the graphite crucible containing ZrCl4 in the low-temperature sublimation zone of the chemical vapor deposition furnace. Subsequently, evacuate to 3 kPa and conduct a pressure holding test to check the airtightness of the equipment. If the airtightness is good, raise the temperature of the constant temperature zone to 1200 °C at a heating rate of 5 °C / min in an Ar atmosphere, and the Ar flow rate is 200 mL / min during heating. After reaching the temperature, introduce H2, with an H2 flow rate of 100 mL / min, and deposit for 2 h at 1200 °C. After the heat preservation ends, turn off H2, turn off the power supply, keep the Ar flow rate at 200 mL / min, and cool down with the furnace. After cooling to room temperature, take out the sample. Ultrasonically clean the sample in deionized water multiple times after the deposition ends, and then place the specimen in an oven at 70 °C for drying treatment. Almost no reaction layer is obtained in the obtained sample. Refer to Figure 4 (b).

[0037] In summary, the present invention provides a method for preparing a ZrC-ZrSi / SiC oxidation-resistant coating on the surface of a carbon / carbon composite material. First, a SiC coating is prepared on the surface of the carbon / carbon (C / C) composite material by chemical vapor deposition. Subsequently, a Zr compound is introduced onto the surface of the SiC coating by reactive chemical vapor deposition again, and a ZrSi composite coating with a set layer thickness is in-situ generated, that is, a ZrC-ZrSi / SiC oxidation-resistant coating is obtained. The fluidity of SiO2 is reduced by ZrO2 generated during the oxidation process, the stability of the oxide film is improved, and the failure of the coating caused by the erosion of molten SiO2 by the gas flow is avoided. The preparation temperature of the coating is low, the structure is dense, the process is simple and controllable, the applicability is strong, the cycle is short, and at the same time, the coating has excellent static and dynamic oxidation resistance at 1700 °C.

[0038] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a ZrC-ZrSi / SiC anti-oxidation coating on the surface of a carbon / carbon composite material, characterized in that, It includes the following steps: Place the polished, cleaned and dried carbon / carbon composite material in the constant temperature zone of a chemical vapor deposition furnace. Use the methyltrichlorosilane-H2-Ar system to deposit a SiC coating on the surface of the carbon / carbon composite material to obtain a uniform and dense SiC coating; Ultrasonically clean the carbon / carbon composite material with a SiC coating and then dry it; Place the dried carbon / carbon composite material with a SiC coating in the constant temperature zone of the chemical vapor deposition furnace. At the same time, place the Zr source powder in the low-temperature sublimation zone of the chemical vapor deposition furnace. Use H2 as the reaction gas and Ar as the dilution gas to carry out in-situ reaction on the SiC coating under negative pressure to obtain a ZrC-ZrSi coating. The ZrC-ZrSi coating is located on the SiC coating; Carry out multiple ultrasonic cleanings and drying on the carbon / carbon composite material with a ZrC-ZrSi coating and a SiC coating to obtain a ZrC-ZrSi / SiC oxidation-resistant coating. The ZrC-ZrSi / SiC oxidation-resistant coating covers the surface of the carbon / carbon composite material.

2. The preparation method of the ZrC-ZrSi / SiC antioxidant coating on the surface of the carbon / carbon composite material according to claim 1, wherein During the deposition process of the SiC coating, the deposition temperature is 1100°C to 1300°C, the Ar flow rate is 200 to 600 mL / min, the H2 flow rate is 200 to 1500 mL / min, the MTS flow rate is 0.07 to 0.3 g / min, and the pressure in the furnace is controlled at 6 - 10 kPa.

3. The preparation method of the ZrC-ZrSi / SiC antioxidant coating on the surface of the carbon / carbon composite material according to claim 1, characterized in that During the in-situ reaction process of the ZrC-ZrSi coating, the reaction temperature is 1100 to 1250°C.

4. The preparation method of the ZrC-ZrSi / SiC antioxidant coating on the surface of the carbon / carbon composite material according to claim 1, characterized in that, During the in-situ reaction process of the ZrC-ZrSi coating, the Ar flow rate is 100 to 500 mL / min, and the H2 flow rate is 500 to 2000 mL / min.

5. The preparation method of the ZrC-ZrSi / SiC antioxidant coating on the surface of the carbon / carbon composite material according to claim 1, characterized in that, The Zr source is ZrCl4, the purity of ZrCl4 is 99.9 wt%, the particle size is 300 mesh, and the pressure in the furnace is controlled at 2 to 8 kPa.

6. The preparation method of the ZrC-ZrSi / SiC antioxidant coating on the surface of the carbon / carbon composite material according to claim 1, characterized in that, After the in-situ reaction of the ZrC-ZrSi coating is completed, cool the furnace with the furnace and maintain an inert atmosphere.

7. Use of the method for preparing the ZrC-ZrSi / SiC antioxidant coating on the surface of the carbon / carbon composite material according to any one of claims 1-6, characterized in that, By replacing the reaction raw materials, it is used to prepare HfC-HfSi / SiC oxidation-resistant coating, TaC-TaSi / SiC oxidation-resistant coating or TiC-TiSi / SiC oxidation-resistant coating.

8. A ZrC-ZrSi / SiC antioxidant coating, characterized in that, Obtained based on the method for preparing the ZrC-ZrSi / SiC oxidation-resistant coating on the surface of the carbon / carbon composite material according to any one of claims 1 - 6.

9. The ZrC-ZrSi / SiC oxidation-resistant coating according to claim 8, wherein The thickness of the ZrC-ZrSi / SiC oxidation-resistant coating is 2.5 - 8 μm.

10. Use of the ZrC-ZrSi / SiC antioxidant coating on the surface of a carbon / carbon composite material obtained by the method for preparing a ZrC-ZrSi / SiC antioxidant coating on the surface of a carbon / carbon composite material according to any one of claims 1-7, characterized in that, As an antioxidant protection for the C / C matrix serving in an oxidation environment not lower than 1700 °C.

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