A core-shell structure nanowire toughened plasma sprayed ZrC-SiC coating and a preparation method thereof

Abstract

The application discloses a kind of core-shell structure nanowire toughening plasma sprayed ZrC-SiC coating and its preparation method, comprising the following steps: 1) the pretreatment of C / C composite material;2) the surface of C / C composite material is prepared SiC@SiO2 nanowire layer, obtains the C / C composite material of surface growth SiC@SiO2 nanowire;3) the surface of the C / C composite material of surface growth SiC@SiO2 nanowire is coated PyC layer, obtains the C / C composite material of surface growth SiC@SiO2@PyC nanowire;4) the surface of the C / C composite material of surface growth SiC@SiO2@PyC nanowire is sprayed ZrC-SiC coating, obtains core-shell structure nanowire toughening plasma sprayed ZrC-SiC coating, the coating and its preparation method can solve the problem that plasma sprayed ceramic coating is big and coating-matrix interface bonding force is poor.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, and relates to a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating and its preparation method. Background Technology

[0002] Carbon / carbon (C / C) composites, carbon-based composites reinforced with carbon fibers, possess characteristics such as low density, low thermal expansion, and excellent high-temperature mechanical properties, making them considered one of the most ideal thermal structural materials. However, their strong oxidation sensitivity in high-temperature (>500℃) aerobic environments limits their application. Ultra-high temperature ceramics (UHTC), as effective coating materials, can provide strong oxidation / ablation protection for C / C composites due to their high melting point and chemical stability. Among them, ZrC-SiC coating is a common coating system and is considered an ideal thermal protective coating material for C / C composites. Thermal spraying methods, represented by plasma spraying and flame spraying, offer high coating deposition efficiency, significant thermal impact on the substrate, and unlimited spray size, making them common methods for preparing thermal protective coatings on C / C composite surfaces. However, the thermal expansion coefficients of thermally sprayed ceramic coatings differ significantly from those of the substrate, and the adhesion between the coating and the substrate is poor. Under airflow erosion conditions, the coating is prone to cracking or even peeling, thus losing its protective effect, becoming a major challenge restricting the application of thermally sprayed coatings.

[0003] To address the poor adhesion of thermally sprayed coatings, one-dimensional nanomaterials are typically incorporated into ceramic coatings to enhance their toughening properties, alleviate interfacial thermal stress, mitigate coating brittleness, and improve bonding strength. SiC nanowires are widely used due to their high strength, high hardness, high oxidation resistance, and excellent physicochemical compatibility with C / C composites. Energy dissipation mechanisms such as nanowire pulling and microcrack deflection are utilized to improve the elastic modulus and fracture toughness of the coating; the pinning effect of nanowires at the interface enhances the interfacial bonding between the ceramic coating and the C / C composite material.

[0004] However, during the plasma spraying process for preparing ceramic coatings, nanowires are difficult to withstand the strong flame erosion, resulting in poor adhesion between the coating and the substrate. Therefore, the nanowires still need to be protected. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating and its preparation method. This coating and its preparation method can solve the problems of high brittleness and poor coating-substrate interface bonding of plasma-sprayed ceramic coatings.

[0006] To achieve the above objectives, this invention discloses a method for preparing a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating, comprising the following steps:

[0007] 1) Pretreatment of C / C composite materials;

[0008] 2) A SiC@SiO2 nanowire layer was prepared on the surface of the C / C composite material to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface;

[0009] 3) Coat the surface of the C / C composite material on which SiC@SiO2 nanowires are grown to a PyC layer to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0010] 4) A ZrC-SiC coating is sprayed onto the surface of a C / C composite material on which SiC@SiO2@PyC nanowires are grown, to obtain a core-shell structure nanowire toughened plasma-sprayed ZrC-SiC coating.

[0011] In step 2), a SiC@SiO2 nanowire layer is prepared on the surface of the C / C composite material by thermal evaporation, resulting in a C / C composite material with SiC@SiO2 nanowires grown on its surface.

[0012] The specific process of step 2) is as follows:

[0013] SiO powder was evenly spread at the bottom of the crucible. The C / C composite material obtained in step 1) was suspended above the SiO powder by molybdenum wire. The crucible was then placed in the constant temperature zone of a tube furnace. Ar was used as the protective gas. Under negative pressure, the temperature inside the tube furnace was raised from room temperature to 1250-1500℃. Then, a closed environment was constructed and the temperature was maintained for 10-60 minutes to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0014] In step 3), a PyC layer is coated onto the surface of the C / C composite material on which SiC@SiO2 nanowires are grown using chemical vapor deposition, to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0015] The specific process of step 3) is as follows:

[0016] The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) is placed in a constant temperature vertical tube furnace and heated to the preset temperature at a heating rate of 1 to 10°C. Then CH4 and Ar are introduced and the temperature is maintained for 1 to 5 hours to deposit the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0017] In step 4), a ZrC-SiC coating is sprayed onto the surface of the C / C composite material on which SiC@SiO2@PyC nanowires are grown using plasma spraying.

[0018] Step 4) is as follows:

[0019] ZrC powder, SiC powder, polyvinyl alcohol solution, deionized water, and anhydrous ethanol were ball-milled and mixed to obtain a slurry. The slurry was then spray-granulated and sprayed onto the surface of the C / C composite material on which SiC@SiO2@PyC nanowires were grown using supersonic plasma spraying to obtain a core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

[0020] The mass ratio of ZrC powder to SiC powder in the mixed slurry is (1-9):(1-9).

[0021] The ratio of the total mass of ZrC powder and SiC powder, the mass of PVA solution, the mass of deionized water, and the mass of anhydrous ethanol is (1-5):(1-5):1:1.

[0022] The core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating of the present invention is prepared based on the preparation method of the core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

[0023] The present invention has the following beneficial effects:

[0024] The shell-structured nanowire-toughened plasma-sprayed ZrC-SiC coating and its preparation method described in this invention combine high-hardness, high-elastic-modulus SiC nanowires with a high-toughness pyrolytic carbon (PyC) layer. This results in SiC nanowires possessing excellent mechanical properties while also exhibiting good toughness. When relative slippage occurs at the interface between the SiC nanowires, PyC, and the coating-substrate layer, which have different properties, the toughening effect of the nanomaterial is expected to be further improved, alleviating the interfacial thermal mismatch between the coating and the substrate. Simultaneously, the deposition of PyC can lock the SiC nanowires to the substrate surface, bridging the core-shell structure at the coating-substrate interface, further improving the interfacial bonding between the coating and the substrate, and solving the problem of poor coating-substrate interfacial adhesion. Furthermore, it should be noted that the SiC@SiO2@PyC nanowires prepared in this invention have a three-layer core-shell structure. The outermost layer of the nanowire is a PyC layer, the middle layer is a SiO2 layer, and the core is SiC. After tensile testing, the SiC@SiO2@PyC nanowire-toughened ZrC-SiC coating peeled off from the substrate at a maximum load of 4453.67 N. The bonded sample was a circle with a diameter of 25 mm, and the calculated bonding strength of the SiCnw / PyC-toughened ZrC-SiC coating reached 9.1 MPa. Therefore, the introduction of SiC@SiO2@PyC nanowires significantly improves the bonding strength between the thermally sprayed coating and the substrate through nanowire pull-out, crack deflection, and interface pinning. In addition, the preparation process of this invention is simple and controllable, highly designable, low in cost, and short in cycle, making it suitable for large-scale production of nanowire-toughened plasma-sprayed ceramic coatings and showing good application prospects. Attached Figure Description

[0025] Figure 1 Surface and cross-sectional morphology images of the nanowire layer;

[0026] Figure 2 TEM image of a single SiC@SiO2 nanowire;

[0027] Figure 3 SEM image of SiC@SiO2@PyC nanowires;

[0028] Figure 4 Cross-sectional morphology of ZrC-SiC coating toughened by SiC@SiO2@PyC nanowires;

[0029] Figure 5 Load-displacement curves obtained after tensile testing of ZrC-SiC coating toughened with SiC@SiO2@PyC nanowires. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0031] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0032] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0033] 1) Pretreatment of C / C composite materials;

[0034] Step 1) is as follows:

[0035] The C / C composite material was successively polished, cleaned and dried, then immersed in an ethanol solution of nickel nitrate for 5 to 30 minutes, and then placed in an oven at 30 to 70°C for drying.

[0036] 2) A SiC@SiO2 nanowire layer was prepared on the surface of the C / C composite material by thermal evaporation, resulting in a C / C composite material with SiC@SiO2 nanowires grown on its surface;

[0037] Step 2) is as follows:

[0038] SiO powder was evenly spread at the bottom of the crucible. The C / C composite material obtained in step 1) was suspended above the SiO powder by molybdenum wire. The crucible was then placed in the constant temperature zone of a tube furnace. Ar was used as the protective gas, and the temperature inside the tube furnace was raised from room temperature to 1250-1500℃ under negative pressure. Then, a closed environment was constructed and the temperature was maintained for 10-60 minutes to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0039] 3) A PyC layer was coated on the surface of SiC@SiO2 nanowires using chemical vapor deposition to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0040] Step 3) is as follows:

[0041] The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) is placed in a constant temperature vertical tube furnace and heated to the preset temperature at a heating rate of 1 to 10°C. Then CH4 and Ar are introduced and the temperature is maintained for 1 to 5 hours to deposit the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0042] 4) A ZrC-SiC coating toughened with SiC@SiO2@PyC nanowires was prepared by plasma spraying.

[0043] Step 4) is as follows:

[0044] ZrC and SiC powders were ball-milled with polyvinyl alcohol (PVA) solution, deionized water and anhydrous ethanol to obtain a slurry. The slurry was then spray-granulated and sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying to obtain a core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

[0045] In step 1), the concentration of the nickel nitrate ethanol solution is 0.02–0.2 mol / L.

[0046] In step 2), the C / C substrate is suspended 1 to 7 cm above the SiO powder by molybdenum wire.

[0047] The preset temperature in step 3) is 800-1300℃.

[0048] In step 3), the flow rates of CH4 and Ar are 0.2–1.2 L / min and 0.6–3 L / min, respectively.

[0049] In step 4), the mass ratio of ZrC powder to SiC powder in the mixed slurry is (1-9):(1-9).

[0050] In step 4), the ratio of the total mass of ZrC powder and SiC powder, the mass of PVA solution, the mass of deionized water, and the mass of anhydrous ethanol is (1-5):(1-5):1:1.

[0051] In step 4), the plasma spraying power is 35-45kW, the argon flow rate is 70L / min, the hydrogen flow rate is 5L / min, the feeding rate is 5-6g / min, and the spraying distance is 80-120mm.

[0052] Example 1

[0053] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0054] 1) Grind, clean and dry the C / C composite material, then soak it in an ethanol solution of nickel nitrate with a concentration of 0.05 mol / L for 5 min, and then put it in a 50℃ oven for drying.

[0055] 2) Spread 4g of SiO powder evenly on the bottom of the crucible, and suspend the C / C substrate obtained in step 1) 1cm above the SiO powder using molybdenum wire. Then place the crucible in the constant temperature zone of a tube furnace, use Ar as a protective gas, and raise the furnace temperature from room temperature to 1300℃ at a heating rate of 5℃ / min under negative pressure. Then construct a closed environment, hold the temperature for 15min, and finally cool with the furnace to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0056] 3) The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to 1070°C at a heating rate of 7°C. CH4 and Ar were introduced, with the flow rates of CH4 and Ar set to 0.6 L / min and 2.4 L / min, respectively. The temperature was maintained for 1 h for deposition. After the furnace cooled to room temperature, the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface was obtained.

[0057] 4) ZrC powder and SiC powder are mixed in a mass ratio of 9:1 to form a mixed powder. The mixed powder, polyvinyl alcohol solution, deionized water and anhydrous ethanol are ball-milled in a mass ratio of 4:4:1:1 to prepare a mixed slurry. The mixed slurry is spray-granulated and then sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying. The spraying distance is controlled at 100 mm and the power is 50 kW to obtain a ZrC-SiC ceramic coating toughened by SiC@SiO2@PyC nanowires, namely a core-shell structure nanowire toughened plasma-sprayed ZrC-SiC coating.

[0058] Example 2

[0059] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0060] 1) Grind, clean and dry the C / C composite material, then soak it in an ethanol solution of nickel nitrate with a concentration of 0.05 mol / L for 10 min, and then put it in a 50℃ oven for drying.

[0061] 2) Spread 4g of SiO powder evenly on the bottom of the crucible, and suspend the C / C substrate obtained in step 1) 2cm above the SiO powder using molybdenum wire. Then place the crucible in the constant temperature zone of a tube furnace, use Ar as a protective gas, and raise the furnace temperature from room temperature to 1300℃ at a heating rate of 5℃ / min under negative pressure. Then construct a closed environment, hold the temperature for 20min, and finally cool with the furnace to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0062] 3) The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to 1070°C at a heating rate of 7°C. CH4 and Ar were introduced, with the flow rates of CH4 and Ar set to 0.6 L / min and 2.4 L / min, respectively. The temperature was maintained for 2 hours for deposition. After the furnace cooled to room temperature, the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface was obtained.

[0063] 4) ZrC powder and SiC powder are mixed in a mass ratio of 9:1 to form a mixed powder. The mixed powder, polyvinyl alcohol solution, deionized water and anhydrous ethanol are ball-milled in a mass ratio of 4:4:1:1 to prepare a mixed slurry. The mixed slurry is spray-granulated and then sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying. The spraying distance is controlled at 100 mm and the power is 50 kW to obtain a ZrC-SiC ceramic coating toughened by SiC@SiO2@PyC nanowires, namely a core-shell structure nanowire toughened plasma-sprayed ZrC-SiC coating.

[0064] Example 3

[0065] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0066] 1) Grind, clean and dry the C / C composite material, then soak it in an ethanol solution of nickel nitrate with a concentration of 0.1 mol / L for 5 min, and then put it in a 50℃ oven for drying.

[0067] 2) Spread 6g of SiO powder evenly on the bottom of the crucible, and suspend the C / C substrate obtained in step 1) 1cm above the SiO powder using molybdenum wire. Then place the crucible in the constant temperature zone of a tube furnace, use Ar as a protective gas, and raise the furnace temperature from room temperature to 1200℃ at a heating rate of 7℃ / min under negative pressure. Then construct a closed environment, hold for 15min, and finally cool with the furnace to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0068] 3) The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to 1070°C at a heating rate of 7°C. CH4 and Ar were introduced, with the flow rates of CH4 and Ar set to 0.6 L / min and 2.4 L / min, respectively. The temperature was maintained for 1 h for deposition. After the furnace cooled to room temperature, the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface was obtained.

[0069] 4) ZrC powder and SiC powder are mixed in a mass ratio of 9:1 to form a mixed powder. The mixed powder, polyvinyl alcohol solution, deionized water and anhydrous ethanol are ball-milled in a mass ratio of 4:4:1:1 to prepare a mixed slurry. The mixed slurry is spray-granulated and then sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying. The spraying distance is controlled at 100 mm and the power is 50 kW to obtain a ZrC-SiC ceramic coating toughened by SiC@SiO2@PyC nanowires, namely a core-shell structure nanowire toughened plasma-sprayed ZrC-SiC coating.

[0070] Comparative Example 1

[0071] This comparative example includes the following steps:

[0072] 1) Grind, clean and dry the C / C composite material, then soak it in an ethanol solution of nickel nitrate with a concentration of 0.1 mol / L for 10 min, and then put it in a 50℃ oven for drying.

[0073] 2) Spread 6g of SiO powder evenly on the bottom of the crucible, and suspend the C / C substrate obtained in step 1) 1cm above the powder with molybdenum wire. Then place the crucible in the constant temperature zone of a tube furnace, use Ar as a protective gas, and raise the furnace temperature from room temperature to 1300℃ at a heating rate of 5℃ / min under negative pressure. Then construct a closed environment, keep it at the temperature for 30min, and finally cool it with the furnace to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0074] 3) The C / C composite material obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to 1070°C at a heating rate of 7°C. CH4 and Ar were introduced at flow rates of 0.6 L / min and 2.4 L / min, respectively, and the temperature was maintained for 2 hours for deposition. After the furnace cooled to room temperature, a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface was obtained. Due to the excessive deposition of PyC, the nanowires exhibited large-area cross-binding, and the pores were blocked, making it impossible to form a three-dimensional network pore structure composed of nanowires.

[0075] 4) ZrC powder and SiC powder were mixed in a mass ratio of 9:1 to form a mixed powder. Then, the mixed powder, polyvinyl alcohol solution, deionized water and anhydrous ethanol were ball-milled in a mass ratio of 4:4:1:1 to prepare a mixed slurry. The mixed slurry was spray-granulated and then sprayed onto the surface of the substrate material obtained in step 3) using supersonic plasma spraying. The spraying distance was controlled at 120 mm and the power was 40 kW to obtain a ZrC-SiC ceramic coating toughened with SiC@SiO2@PyC nanowires. The obtained coating had many large pores and the nanowire layer was not completely filled and covered, resulting in low bonding strength between the coating and the substrate.

[0076] Example 4

[0077] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0078] 1) Pretreatment of C / C composite materials;

[0079] Step 1) is as follows:

[0080] The C / C composite material was successively polished, cleaned and dried, then immersed in an ethanol solution of nickel nitrate for 20 minutes, and then placed in a 50℃ oven for drying.

[0081] 2) A SiC@SiO2 nanowire layer was prepared on the surface of the C / C composite material by thermal evaporation, resulting in a C / C composite material with SiC@SiO2 nanowires grown on its surface;

[0082] Step 2) is as follows:

[0083] SiO powder was evenly spread at the bottom of the crucible. The C / C composite material obtained in step 1) was suspended above the SiO powder by molybdenum wire. The crucible was then placed in the constant temperature zone of a tube furnace. Ar was used as the protective gas, and the temperature inside the tube furnace was raised from room temperature to 1300℃ under negative pressure. Then, a closed environment was constructed and the temperature was maintained for 20 minutes to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0084] 3) A PyC layer was coated on the surface of SiC@SiO2 nanowires using chemical vapor deposition to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0085] Step 3) is as follows:

[0086] The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to the preset temperature at a heating rate of 5°C. Then CH4 and Ar were introduced and the temperature was maintained for 2 hours to deposit the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0087] 4) A ZrC-SiC coating toughened with SiC@SiO2@PyC nanowires was prepared by plasma spraying.

[0088] Step 4) is as follows:

[0089] ZrC and SiC powders were ball-milled with polyvinyl alcohol (PVA) solution, deionized water and anhydrous ethanol to obtain a slurry. The slurry was then spray-granulated and sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying to obtain a core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

[0090] In step 1), the concentration of the nickel nitrate ethanol solution is 0.1 mol / L.

[0091] In step 2), the C / C substrate is suspended 6 cm above the SiO powder by a molybdenum wire.

[0092] The preset temperature in step 3) is 1000℃.

[0093] In step 3), the flow rates of CH4 and Ar are 1 L / min and 2 L / min, respectively.

[0094] In step 4), the mass ratio of ZrC powder to SiC powder in the mixed slurry is 2:7.

[0095] In step 4), the ratio of the total mass of ZrC powder and SiC powder, the mass of PVA solution, the mass of deionized water, and the mass of anhydrous ethanol is 3:2:1:1.

[0096] In step 4), the plasma spraying power is 40kW, the argon flow rate is 70L / min, the hydrogen flow rate is 5L / min, the feeding rate is 5.5g / min, and the spraying distance is 100mm.

[0097] Example 5

[0098] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0099] 1) Pretreatment of C / C composite materials;

[0100] Step 1) is as follows:

[0101] The C / C composite material was successively polished, cleaned and dried, then immersed in an ethanol solution of nickel nitrate for 30 minutes, and then placed in a 70℃ oven for drying.

[0102] 2) A SiC@SiO2 nanowire layer was prepared on the surface of the C / C composite material by thermal evaporation, resulting in a C / C composite material with SiC@SiO2 nanowires grown on the surface;

[0103] Step 2) is as follows:

[0104] SiO powder was evenly spread at the bottom of the crucible. The C / C composite material obtained in step 1) was suspended above the SiO powder by molybdenum wire. The crucible was then placed in the constant temperature zone of a tube furnace. Ar was used as the protective gas, and the temperature inside the tube furnace was raised from room temperature to 1500℃ under negative pressure. Then, a closed environment was constructed and the temperature was maintained for 10-60 minutes to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0105] 3) A PyC layer was coated on the surface of SiC@SiO2 nanowires using chemical vapor deposition to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0106] Step 3) is as follows:

[0107] The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to the preset temperature at a heating rate of 10°C. Then CH4 and Ar were introduced and the temperature was maintained for 5 hours to deposit the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0108] 4) A ZrC-SiC coating toughened with SiC@SiO2@PyC nanowires was prepared by plasma spraying.

[0109] Step 4) is as follows:

[0110] ZrC and SiC powders were ball-milled with polyvinyl alcohol (PVA) solution, deionized water and anhydrous ethanol to obtain a slurry. The slurry was then spray-granulated and sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying to obtain a core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

[0111] In step 1), the concentration of the nickel nitrate ethanol solution is 0.2 mol / L.

[0112] In step 2), the C / C substrate is suspended 7 cm above the SiO powder by a molybdenum wire.

[0113] The preset temperature in step 3) is 300℃.

[0114] In step 3), the flow rates of CH4 and Ar are 1.2 L / min and 3 L / min, respectively.

[0115] In step 4), the mass ratio of ZrC powder to SiC powder in the mixed slurry is 9:1.

[0116] In step 4), the ratio of the total mass of ZrC powder and SiC powder, the mass of PVA solution, the mass of deionized water, and the mass of anhydrous ethanol is 1:5:1:1.

[0117] In step 4), the plasma spraying power is 45kW, the argon flow rate is 70L / min, the hydrogen flow rate is 5L / min, the feeding rate is 6g / min, and the spraying distance is 120mm.

[0118] Example 6

[0119] The preparation method of the core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating of the present invention includes the following steps:

[0120] 1) Pretreatment of C / C composite materials;

[0121] Step 1) is as follows:

[0122] The C / C composite material was successively polished, cleaned and dried, then immersed in an ethanol solution of nickel nitrate for 5 minutes, and then placed in a 30°C oven for drying.

[0123] 2) A SiC@SiO2 nanowire layer was prepared on the surface of the C / C composite material by thermal evaporation, resulting in a C / C composite material with SiC@SiO2 nanowires grown on its surface;

[0124] Step 2) is as follows:

[0125] SiO powder was evenly spread at the bottom of the crucible. The C / C composite material obtained in step 1) was suspended above the SiO powder by molybdenum wire. The crucible was then placed in the constant temperature zone of a tube furnace. Ar was used as the protective gas, and the temperature inside the tube furnace was raised from room temperature to 1250℃ under negative pressure. Then, a closed environment was constructed and the temperature was maintained for 10 minutes to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

[0126] 3) A PyC layer was coated on the surface of SiC@SiO2 nanowires using chemical vapor deposition to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0127] Step 3) is as follows:

[0128] The C / C composite material with SiC@SiO2 nanowires grown on the surface obtained in step 2) was placed in a constant temperature vertical tube furnace and heated to the preset temperature at a heating rate of 1℃. Then CH4 and Ar were introduced and the temperature was maintained for 1h for deposition to obtain the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface.

[0129] 4) A ZrC-SiC coating toughened with SiC@SiO2@PyC nanowires was prepared by plasma spraying.

[0130] Step 4) is as follows:

[0131] ZrC and SiC powders were ball-milled with polyvinyl alcohol (PVA) solution, deionized water and anhydrous ethanol to obtain a slurry. The slurry was then spray-granulated and sprayed onto the surface of the C / C composite material with SiC@SiO2@PyC nanowires grown on the surface obtained in step 3) using supersonic plasma spraying to obtain a core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

[0132] In step 1), the concentration of the nickel nitrate ethanol solution is 0.02 mol / L.

[0133] In step 2), the C / C substrate is suspended 1 cm above the SiO powder by a molybdenum wire.

[0134] The preset temperature in step 3) is 800℃.

[0135] In step 3), the flow rates of CH4 and Ar are 0.2 L / min and 0.6 L / min, respectively.

[0136] In step 4), the mass ratio of ZrC powder to SiC powder in the mixed slurry is 1:9.

[0137] In step 4), the ratio of the total mass of ZrC powder and SiC powder, the mass of PVA solution, the mass of deionized water, and the mass of anhydrous ethanol is 5:1:1:1.

[0138] In step 4), the plasma spraying power is 35kW, the argon flow rate is 70L / min, the hydrogen flow rate is 5L / min, the feeding rate is 5g / min, and the spraying distance is 80mm.

[0139] Figure 1 The images show the surface and cross-sectional morphology of the nanowire layer. Figure 1 As can be seen, the nanowire layer is about 51 μm thick, and obvious catalyst particles can be observed at the tip of the nanowire, indicating that the growth mechanism of the nanowire mainly follows the gas-liquid-solid (VLS) mode.

[0140] Figure 2 The image shows a TEM image of a single SiC@SiO2 nanowire. It can be seen that the nanowire has a core-shell structure, with crystalline SiC inside and a disordered structure on the outside, which is amorphous SiO2.

[0141] Figure 3 The image shows a SEM image of SiC@SiO2@PyC nanowires. After PyC deposition, the SiCnws network structure remains intact with uniform pores, and the surface is uniformly covered with a PyC shell structure. Due to the PyC deposition, adjacent SiCnws tend to be connected by it, which can improve the cohesion of SiCnws themselves. At the same time, the PyC deposition also causes the diameter of SiCnws to increase slightly.

[0142] Figure 4 The cross-sectional morphology of the ZrC-SiC coating toughened by SiC@SiO2@PyC nanowires is shown. It can be seen that the sprayed droplets fully fill the nanowire layer, forming a coating with a thickness of about 280 μm.

[0143] Figure 5 The load-displacement curves of the ZrC-SiC coating toughened by SiC@SiO2@PyC nanowires were obtained after tensile testing. The coating peeled off from the substrate at a maximum load of 4453.67 N. The bonded sample was a circle with a diameter of 25 mm. The bond strength of the SiCnw / PyC toughened ZrC-SiC coating can be calculated to be 9.1 MPa.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating, characterized in that, Includes the following steps: 1) Pretreatment of C / C composite materials; 2) A SiC@SiO2 nanowire layer was prepared on the surface of the C / C composite material to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface; 3) Coat the surface of the C / C composite material on which SiC@SiO2 nanowires are grown to a PyC layer to obtain a C / C composite material with SiC@SiO2@PyC nanowires grown on the surface; 4) A ZrC-SiC coating is sprayed onto the surface of a C / C composite material on which SiC@SiO2@PyC nanowires are grown to obtain a core-shell structure nanowire toughened plasma-sprayed ZrC-SiC coating. In step 3), a PyC layer is coated onto the surface of the C / C composite material on which SiC@SiO2 nanowires are grown using chemical vapor deposition, resulting in a C / C composite material with SiC@SiO2@PyC nanowires grown on its surface. In step 2), a SiC@SiO2 nanowire layer is prepared on the surface of the C / C composite material using a thermal evaporation method, resulting in a C / C composite material with SiC@SiO2 nanowires grown on its surface. The specific process of step 2) is as follows: SiO powder was evenly spread at the bottom of the crucible. The C / C composite material obtained in step 1) was suspended above the SiO powder by molybdenum wire. The crucible was then placed in the constant temperature zone of a tube furnace. Ar was used as the protective gas. Under negative pressure, the temperature inside the tube furnace was raised from room temperature to 1250-1500℃. Then, a closed environment was constructed and the temperature was maintained for 10-60 minutes to obtain a C / C composite material with SiC@SiO2 nanowires grown on the surface.

2. The method for preparing a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating according to claim 1, characterized in that, In step 4), a ZrC-SiC coating is sprayed onto the surface of the C / C composite material on which SiC@SiO2@PyC nanowires are grown using plasma spraying.

3. The method for preparing a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating according to claim 1, characterized in that, Step 4) is as follows: ZrC powder, SiC powder, polyvinyl alcohol solution, deionized water, and anhydrous ethanol were ball-milled and mixed to obtain a slurry. The slurry was then spray-granulated and sprayed onto the surface of the C / C composite material on which SiC@SiO2@PyC nanowires were grown using supersonic plasma spraying to obtain a core-shell structured nanowire toughened plasma-sprayed ZrC-SiC coating.

4. The method for preparing a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating according to claim 3, characterized in that, The mass ratio of ZrC powder to SiC powder in the mixed slurry is (1~9):(1~9).

5. The method for preparing a core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating according to claim 3, characterized in that, The ratio of the total mass of ZrC powder and SiC powder, the mass of PVA solution, the mass of deionized water, and the mass of anhydrous ethanol is (1~5):(1~5):1:

1.

6. A core-shell structured nanowire-toughened plasma-sprayed ZrC-SiC coating, characterized in that, It was prepared according to the preparation method of the core-shell structured nanowire toughened plasma sprayed ZrC-SiC coating as described in any one of claims 1-5.

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