An antioxidant coating for high-temperature protection of the niobium silicide alloy surface, its preparation and application

Abstract

The present invention relates to the field of metal surface engineering technology, and in particular to an anti-oxidation coating for high-temperature protection of the surface of niobium silicon alloy, and its preparation and application. The anti-oxidation coating of the present invention comprises a Mo5Si3-MoSi2 multiphase coating on the surface of the niobium silicon alloy and micron SiO2 particles and nano SiO2 particles in situ dispersed in the Mo5Si3-MoSi2 multiphase coating. The anti-oxidation coating of the present invention is formed by high-temperature in-situ growth, and the coating thickness is controllable, the microstructure is uniform and dense, and it has excellent high-temperature oxidation resistance and crack resistance, thereby achieving high-temperature thermal protection of niobium silicon alloy; at the same time, the coating preparation method is simple and low-cost, and can be applied in large-scale industry.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface engineering, and in particular to an anti-oxidation coating for high-temperature protection of a niobium silicon alloy surface, and a preparation and application thereof. Background Art

[0002] Niobium-silicon alloys offer advantages such as a high melting point, low density, excellent high-temperature mechanical properties, and good machinability, making them an ideal alternative to nickel-based superalloys for high-temperature structural hot-end components in aerospace engines, weapon thrusters, and other high-temperature applications above 1200°C. However, the niobium-based oxides formed during the high-temperature oxidation process of niobium-silicon alloys are non-protective and easily detach, resulting in poor oxidation resistance, which severely limits their engineering applications. High-temperature protective coatings are currently recognized as the most practical method for improving the oxidation resistance of niobium-silicon alloys. Among various coatings, MoSi2 coatings have a high melting point and low density. During the high-temperature oxidation process, they form a continuous, dense, and self-healing SiO2 protective film on their surface, making them ideal coating materials for high-temperature protection of niobium-silicon alloys. However, several key issues exist in the application of MoSi2 coatings, resulting in insufficient high-temperature protection capabilities. First, the MoSi2 coating has low toughness and is prone to cracking during use, which weakens the coating's antioxidant properties. Second, the significant difference in thermal expansion coefficients between the SiO2 protective film and the MoSi2 coating results in excessive residual stress in the SiO2 protective film, which is prone to peeling during cooling and thus loses its antioxidant capacity. Third, the current method for preparing MoSi2 coatings primarily involves depositing a Mo layer followed by high-temperature embedding and infiltration of Si. This method is complex and has low controllability of the coating's microstructure and thickness. In summary, to effectively improve the antioxidant properties of MoSi2 coatings, it is necessary to increase the MoSi2 coating's fracture toughness (to improve crack resistance), reduce the MoSi2 coating's thermal expansion coefficient (to reduce residual stress in the SiO2 protective film), and develop a coating preparation method with simple processes and controllable coating microstructure and thickness, ultimately enabling the reliable application of niobium-silicon alloys in engineering. Summary of the Invention

[0003] In order to solve the above problems, the purpose of the present invention is to provide an antioxidant coating for high-temperature protection of the surface of niobium silicon alloy and its preparation and application. The antioxidant coating for high-temperature protection of the surface of niobium silicon alloy of the present invention (also referred to as "anti-oxidation coating") includes a Mo5Si3-MoSi2 multiphase coating on the surface of niobium silicon alloy and micron SiO2 particles and nano SiO2 particles in situ dispersed in the Mo5Si3-MoSi2 multiphase coating. The antioxidant coating of the present invention is formed by high-temperature in-situ growth, the coating thickness is controllable, the microstructure is uniform and dense, and it has excellent high-temperature oxidation resistance and crack resistance, thereby achieving high-temperature thermal protection of niobium silicon alloy; at the same time, the coating preparation method is simple and low-cost, and can be applied in large-scale industry.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] The first object of the present invention is to provide an oxidation-resistant coating for high-temperature protection of the surface of a niobium-silicon alloy, comprising a Mo5Si3-MoSi2 composite coating on the surface of the niobium-silicon alloy and micron-SiO2 particles and nano-SiO2 particles in situ dispersed in the Mo5Si3-MoSi2 composite coating.

[0006] In one embodiment of the present invention, the thickness of the anti-oxidation coating for high-temperature protection of the niobium silicon alloy surface is 150 μm to 300 μm.

[0007] In one embodiment of the present invention, in the oxidation-resistant coating for high-temperature protection of the surface of niobium silicon alloy, the volume fraction of Mo5Si3 is 45% to 60%, the volume fraction of MoSi2 is 35% to 50%, and the volume fraction of SiO2 is 5% to 15%.

[0008] In one embodiment of the present invention, the size of the micron SiO2 particles is less than 2 microns, and the size of the nano-SiO2 particles is less than 100 nanometers.

[0009] A second object of the present invention is to provide a method for preparing an anti-oxidation coating for high-temperature protection of the surface of a niobium-silicon alloy, which specifically comprises the following steps:

[0010] Multi-scale MoSi2 powder is sprayed onto the surface of niobium silicon alloy through atmospheric plasma and subjected to high-temperature heat treatment to form an anti-oxidation coating on the surface of niobium silicon alloy for high-temperature protection of the surface of niobium silicon alloy.

[0011] In one embodiment of the present invention, the multi-scale MoSi2 powder is obtained by ball milling and mixing MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns.

[0012] In one embodiment of the present invention, during the ball milling process, the ball-to-material ratio is 5 to 10:1, the ball milling speed is 100 rpm to 200 rpm, and the ball milling time is 12 h to 24 h. During each hour of ball milling, the milling is stopped for 30 minutes to prevent the temperature from being too high.

[0013] In one embodiment of the present invention, the multi-scale MoSi2 powder is composed of a mixture of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns.

[0014] In one embodiment of the present invention, the volume ratio of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns is 5% to 10%:80% to 85%:10% to 15%.

[0015] In one embodiment of the present invention, during the atmospheric plasma coating spraying process, the voltage is 150-180V, the current is 350A-400A, the argon flow rate is 100L / min-120L / min, the hydrogen flow rate is 15L / min-20L / min, the powder carrier gas flow rate is 3L / min-6L / min, the spray gun moving speed is 600mm / s-800mm / s, and the spraying distance is 100mm-120mm.

[0016] In one embodiment of the present invention, during the high-temperature heat treatment process, the temperature is 1200°C to 1300°C, the holding time is 4h to 10h, the heating rate is 5°C / min, the cooling rate is 5°C / min, the treatment atmosphere is high-purity argon, and the gas flow rate is 500mL / min.

[0017] A third object of the present invention is to provide a niobium-silicon alloy having a surface coated with an anti-oxidation coating for high-temperature protection of the niobium-silicon alloy surface.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The 1-10 micron MoSi2 powder in the multi-scale MoSi2 spray powder in the anti-oxidation coating of the present invention has a high specific surface area and can absorb more oxygen atoms in the air during the spray melting process, thereby increasing the oxygen content in the coating; the 10-100 micron MoSi2 powder in the multi-scale MoSi2 spray powder is to improve the fluidity of the powder and ensure stable powder feeding during the spraying process; the 100-250 micron MoSi2 powder in the multi-scale MoSi2 spray powder is to prevent the melted powder from sticking to the gun barrel and affecting the stability of the spray flame. By using the multi-scale MoSi2 spray powder provided above, it is possible to ensure that the coating prepared by atmospheric plasma spraying has a uniform structure and controllable thickness.

[0020] The present invention utilizes high-temperature heat treatment to induce the adsorbed oxygen in the MoSi2 coating to react with the MoSi2, resulting in the in-situ growth of low-expansion micron-SiO2 particles and nano-SiO2 particles. Simultaneously, a Mo5Si3-MoSi2 complex structure is formed within the coating, thereby producing an anti-oxidation coating for high-temperature surface protection of niobium-silicon alloys. The Mo5Si3-MoSi2 complex structure and the multi-stage strengthening of the SiO2 particles increase the fracture toughness of the anti-oxidation coating and enhance its crack resistance. Furthermore, the SiO2 particles have a low coefficient of thermal expansion, effectively reducing the overall thermal expansion coefficient of the anti-oxidation coating, thereby reducing the thermal stress of the SiO2 protective film during cooling and enhancing the film's resistance to spalling.

[0021] Compared with traditional MoSi2 coatings, the anti-oxidation coating provided by the present invention for high-temperature protection of niobium silicon alloy surfaces has excellent crack resistance and good SiO2 protective film anti-peeling ability. In addition, the preparation process is simple, the coating structure and thickness are controllable, and it can be applied in large-scale industrial areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The particle size distribution diagram of multi-scale MoSi2 powder obtained by laser particle size analyzer test;

[0023] Figure 2 These are optical microscope photographs and scanning electron microscope photographs of the anti-oxidation coating for high-temperature protection of the niobium-silicon alloy surface prepared in Example 1; (a) is an optical microscope photograph of the niobium-silicon alloy substrate without the anti-oxidation coating; (b) is an optical microscope photograph of the niobium-silicon alloy with the anti-oxidation coating; (c) is a scanning electron microscope photograph of a cross-section of the anti-oxidation coating; and (d) is a partial magnified view of (c);

[0024] Figure 3 This is a surface scanning electron micrograph of the oxidation-resistant coating for high-temperature protection of the niobium-silicon alloy surface prepared in Example 1 after oxidation at 1300°C for 100 hours; (a) is a low-magnification surface scanning electron micrograph; (b) is a partial enlarged view of (a);

[0025] Figure 4 A scanning electron microscope photograph of a cross section of the oxidation-resistant coating for high-temperature protection of niobium-silicon alloy surface prepared in Example 2 after oxidation at 1400°C for 100 hours;

[0026] Figure 5 A scanning electron microscope photograph of the cross section of the oxidation-resistant coating for high-temperature protection of the niobium silicon alloy surface prepared in Example 3 after oxidation at 1500° C. for 100 hours. DETAILED DESCRIPTION

[0027] The present invention provides an oxidation-resistant coating for high-temperature protection of the surface of a niobium-silicon alloy, comprising a Mo5Si3-MoSi2 multiphase coating on the surface of the niobium-silicon alloy and micron SiO2 particles and nano SiO2 particles in situ dispersed in the Mo5Si3-MoSi2 multiphase coating.

[0028] In one embodiment of the present invention, the thickness of the anti-oxidation coating for high-temperature protection of the niobium silicon alloy surface is 150 μm to 300 μm.

[0029] In one embodiment of the present invention, in the oxidation-resistant coating for high-temperature protection of the surface of niobium silicon alloy, the volume fraction of Mo5Si3 is 45% to 60%, the volume fraction of MoSi2 is 35% to 50%, and the volume fraction of SiO2 is 5% to 15%.

[0030] In one embodiment of the present invention, the size of the micron SiO2 particles is less than 2 microns, and the size of the nano-SiO2 particles is less than 100 nanometers.

[0031] The present invention provides a method for preparing an anti-oxidation coating for high-temperature protection of a niobium-silicon alloy surface, which specifically comprises the following steps:

[0032] Multi-scale MoSi2 powder is sprayed onto the surface of niobium silicon alloy through atmospheric plasma and subjected to high-temperature heat treatment to form an anti-oxidation coating on the surface of niobium silicon alloy for high-temperature protection of the surface of niobium silicon alloy.

[0033] In one embodiment of the present invention, the multi-scale MoSi2 powder is obtained by ball milling and mixing MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns.

[0034] In one embodiment of the present invention, during the ball milling process, the ball-to-material ratio is 5 to 10:1, the ball milling speed is 100 rpm to 200 rpm, and the ball milling time is 12 h to 24 h. During each hour of ball milling, the milling is stopped for 30 minutes to prevent the temperature from being too high.

[0035] In one embodiment of the present invention, the multi-scale MoSi2 powder is composed of a mixture of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns.

[0036] In one embodiment of the present invention, the volume ratio of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns is 5% to 10%:80% to 85%:10% to 15%.

[0037] In one embodiment of the present invention, during the atmospheric plasma coating spraying process, the voltage is 150-180V, the current is 350A-400A, the argon flow rate is 100L / min-120L / min, the hydrogen flow rate is 15L / min-20L / min, the powder carrier gas flow rate is 3L / min-6L / min, the spray gun moving speed is 600mm / s-800mm / s, and the spraying distance is 100mm-120mm.

[0038] In one embodiment of the present invention, during the high-temperature heat treatment process, the temperature is 1200°C to 1300°C, the holding time is 4h to 10h, the heating rate is 5°C / min, the cooling rate is 5°C / min, the treatment atmosphere is high-purity argon, and the gas flow rate is 500mL / min.

[0039] The present invention provides a niobium-silicon alloy whose surface is coated with the anti-oxidation coating for high-temperature protection of the niobium-silicon alloy surface according to any one of claims 1 to 4.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0042] Example 1

[0043] This embodiment provides an anti-oxidation coating for high-temperature protection of the surface of niobium silicon alloy and a preparation method thereof.

[0044] 100 g of multi-scale MoSi2 powder (5% by mass of MoSi2 powder with a size of 1 to 10 microns, 80% by mass of MoSi2 powder with a size of 10 to 100 microns, and 15% by mass of MoSi2 powder with a size of 150 to 250 microns) was placed in a 500 ml stainless steel ball mill, and then stainless steel balls were added; the sealed stainless steel vacuum ball mill was fixed on a planetary ball mill for ball milling; the speed of the planetary ball mill was 200 rpm, the ball milling time was 24 hours, and the ball-to-material ratio was 5:1; and during the ball milling process, it was stopped for 30 minutes every hour to prevent the temperature from being too high, and finally a uniformly mixed multi-scale MoSi2 powder ( Figure 1 ).

[0045] The multi-scale MoSi2 powder is sprayed on the surface of the niobium silicon alloy by atmospheric plasma spraying, and combined with subsequent high-temperature heat treatment, an anti-oxidation coating with a thickness of 250 μm is obtained;

[0046] The spraying parameters are controlled as follows: voltage 180 V; current 400 A; argon flow rate 100 L / min; hydrogen flow rate 18 L / min; powder carrier gas flow rate 5 L / min; spray gun moving speed 800 mm / s; and spraying distance 120 mm.

[0047] The high-temperature heat treatment process parameters are controlled as follows: temperature 1200°C; holding time 10h; heating rate 5°C / min; cooling rate 5°C / min; treatment atmosphere is high-purity argon; gas flow rate 500mL / min.

[0048] The microstructure of the anti-oxidation coating prepared in this embodiment was characterized by optical microscopy and scanning electron microscopy. Figure 2 As shown. Figure 2 It can be seen that the coating is composed of Mo5Si3 and MoSi2 phases, has a uniform and dense structure, and low-expansion micro / nano-SiO2 particles are uniformly dispersed, indicating that this embodiment can achieve controllable preparation of Mo5Si3-MoSi2 multiphase coating and uniform dispersion of low-expansion micro / nano-SiO2 particles.

[0049] The anti-oxidation coating obtained in this example was placed in a high-temperature box furnace for anti-oxidation performance testing. It was kept at 1300°C in an air atmosphere for 100 hours and then air-cooled to room temperature within 20 minutes. The microstructure of the coating after oxidation was characterized using a scanning electron microscope. Figure 3 As shown. Figure 3 It can be seen that a uniform and continuous SiO2 protective film is formed on the surface of the coating, and no cracks or peeling of the SiO2 protective film are found, indicating that the antioxidant coating prepared in this embodiment has excellent antioxidant properties at 1300°C, including excellent crack resistance and good SiO2 protective film peeling resistance.

[0050] Example 2

[0051] This embodiment provides an anti-oxidation coating for high-temperature protection of the surface of niobium silicon alloy and a preparation method thereof.

[0052] 50g of multi-scale MoSi2 powder (10% by mass of MoSi2 powder with a size of 1 to 10 microns, 80% by mass of MoSi2 powder with a size of 10 to 100 microns, and 10% by mass of MoSi2 powder with a size of 150 to 250 microns) was placed in a 500ml stainless steel ball mill, and then stainless steel balls were added; the sealed stainless steel vacuum ball mill was fixed on a planetary ball mill for ball milling; the rotation speed of the planetary ball mill was 100 rpm, the ball milling time was 12 hours, and the ball-to-material ratio was 10:1; and during the ball milling process, the milling was stopped for 30 minutes every hour to prevent the temperature from being too high, and finally a uniformly mixed multi-scale MoSi2 powder was obtained.

[0053] Multi-scale MoSi2 powder was sprayed on the surface of niobium silicon alloy by atmospheric plasma spraying, and combined with subsequent high-temperature heat treatment, an anti-oxidation coating with a thickness of 150μm was obtained.

[0054] The spraying parameters were controlled as follows: voltage 180 V; current 400 A; argon flow rate 100 L / min; hydrogen flow rate 18 L / min; powder carrier gas flow rate 5 L / min; spray gun moving speed 800 mm / s; and spraying distance 120 mm.

[0055] The high-temperature heat treatment process parameters are controlled as follows: temperature 1300°C; holding time 4h; heating rate 5°C / min; cooling rate 5°C / min; treatment atmosphere is high-purity argon; gas flow rate 500mL / min.

[0056] The low-expansion micro / nano-type oxidation-resistant coating for high-temperature protection of niobium-silicon alloy surfaces obtained in this example was placed in a high-temperature box furnace for oxidation resistance testing. The coating was kept at 1400°C in an air atmosphere for 100 hours and then cooled to room temperature within 20 minutes. The microstructure of the coating after oxidation was characterized using a scanning electron microscope. Figure 4 As shown. Figure 4 It can be seen that after the coating was oxidized at 1400°C for 100 hours, a uniform and continuous SiO2 protective film was formed on the surface, and no cracks or peeling of the SiO2 protective film were found, indicating that the anti-oxidation coating prepared in this embodiment has excellent anti-oxidation performance at 1400°C, including excellent crack resistance and good SiO2 protective film peeling resistance.

[0057] Example 3

[0058] This embodiment provides an anti-oxidation coating for high-temperature protection of the surface of niobium silicon alloy and a preparation method thereof.

[0059] 50g of multi-scale MoSi2 powder was placed in a 500ml stainless steel ball mill, followed by the addition of stainless steel balls. The multi-scale MoSi2 powder consisted of 5% by mass of MoSi2 powder with a size of 1-10 microns, 85% by mass of MoSi2 powder with a size of 10-100 microns, and 10% by mass of MoSi2 powder with a size of 150-250 microns. The sealed stainless steel vacuum ball mill was mounted on a planetary ball mill for milling at a speed of 150 rpm for 18 hours at a ball-to-material ratio of 8:1. During the milling process, the milling was paused for 30 minutes every hour to prevent overheating, resulting in a uniformly mixed multi-scale MoSi2 powder.

[0060] The multi-scale MoSi2 powder was applied to the surface of a niobium-silicon alloy using atmospheric plasma spraying. Combined with subsequent high-temperature heat treatment, a 300μm-thick, low-expansion micro / nanoscale, oxidation-resistant coating for high-temperature protection of the niobium-silicon alloy was obtained. Spraying parameters were controlled as follows: voltage 165V; current 400A; argon flow rate 120L / min; hydrogen flow rate 15L / min; powder carrier gas flow rate 6L / min; spray gun travel speed 600mm / s; spray distance 110mm. High-temperature heat treatment process parameters were controlled as follows: temperature 1250°C; holding time 8h; heating rate 5°C / min; cooling rate 5°C / min; treatment atmosphere high-purity argon; gas flow rate 500mL / min.

[0061] The anti-oxidation coating obtained in this example was placed in a high-temperature box furnace for anti-oxidation performance testing. It was kept at 1500°C in an air atmosphere for 100 hours and then air-cooled to room temperature within 20 minutes. The microstructure of the coating after oxidation was characterized using a scanning electron microscope. Figure 5 As shown. Figure 5 It can be seen that after the coating was oxidized at 1500°C for 100 hours, a uniform and continuous SiO2 protective film was formed on the surface, and no cracks or peeling of the SiO2 protective film were found, indicating that the anti-oxidation coating prepared in this embodiment has excellent anti-oxidation properties at 1500°C, including excellent crack resistance and good SiO2 protective film peeling resistance.

[0062] The results of Examples 1-3 show that the antioxidant coating prepared by the present invention has excellent antioxidant properties at 1300-1500°C, including excellent crack resistance and good SiO2 protective film anti-peeling ability, and the preparation process is simple, the organizational structure and thickness are controllable, and it can be used in large-scale industrial applications.

[0063] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the explanations of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An anti-oxidation coating for high temperature protection of niobium silicon alloy surface, characterized in that: It includes a Mo5Si3-MoSi2 multiphase coating on the surface of a niobium silicon alloy and micron SiO2 particles and nano SiO2 particles in situ dispersed in the Mo5Si3-MoSi2 multiphase coating; Among them, the anti-oxidation coating for high-temperature protection of the niobium silicon alloy surface is prepared by the following method: Multi-scale MoSi2 powder is sprayed onto the surface of niobium silicon alloy through atmospheric plasma, and then subjected to high-temperature heat treatment to form an anti-oxidation coating on the surface of niobium silicon alloy for high-temperature protection of the surface of niobium silicon alloy; The multi-scale MoSi2 powder is composed of a mixture of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns.

2. The anti-oxidation coating for high temperature protection of niobium silicon alloy surface according to claim 1, characterized in that: The thickness of the anti-oxidation coating for high-temperature protection of the niobium silicon alloy surface is 150 μm to 300 μm.

3. The anti-oxidation coating for high temperature protection of niobium silicon alloy surface according to claim 1, characterized in that: In the anti-oxidation coating used for high-temperature protection of the surface of niobium silicon alloy, the volume fraction of Mo5Si3 is 45%~60%, the volume fraction of MoSi2 is 35%~50%, and the volume fraction of SiO2 is 5%~15%.

4. The anti-oxidation coating for high temperature protection of niobium silicon alloy surface according to claim 1, characterized in that: The size of micron SiO2 particles is less than 2 microns, and the size of nano SiO2 particles is less than 100 nanometers.

5. A method for preparing an anti-oxidation coating for high-temperature protection of a niobium-silicon alloy surface according to any one of claims 1 to 4, characterized in that: The specific steps include: Multi-scale MoSi2 powder is sprayed onto the surface of niobium silicon alloy through atmospheric plasma, and then subjected to high-temperature heat treatment to form an anti-oxidation coating on the surface of niobium silicon alloy for high-temperature protection of the surface of niobium silicon alloy; The multi-scale MoSi2 powder is composed of a mixture of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and MoSi2 powder with a scale of 100 microns to 250 microns.

6. The method for preparing an anti-oxidation coating for high-temperature protection of niobium silicon alloy surface according to claim 5, characterized in that: The volume ratio of MoSi2 powder with a scale of 1 micron to 10 microns, MoSi2 powder with a scale of 10 microns to 100 microns, and powder with a scale of 100 microns to 250 microns is 5% to 10%: 80% to 85%: 10% to 15%.

7. The method for preparing an anti-oxidation coating for high-temperature protection of a niobium-silicon alloy surface according to claim 5, characterized in that: During the atmospheric plasma coating spraying process, the voltage is 150-180 V, the current is 350A~400A, the argon flow rate is 100L / min~120L / min, the hydrogen flow rate is 15L / min~20L / min, the powder carrier gas flow rate is 3L / min~6L / min, the spray gun moving speed is 600mm / s~800mm / s, and the spraying distance is 100mm~120mm.

8. The method for preparing an anti-oxidation coating for high-temperature protection of niobium silicon alloy surface according to claim 5, characterized in that: During the high-temperature heat treatment process, the temperature is 1200°C~1300°C, the holding time is 4h~10h, the heating rate is 5°C / min, the cooling rate is 5°C / min, the treatment atmosphere is high-purity argon, and the gas flow rate is 500mL / min.

9. A niobium-silicon alloy coated with the anti-oxidation coating for high-temperature protection of the niobium-silicon alloy surface according to any one of claims 1 to 4.

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