Arc extinguishing nozzle of composite coating and preparation method of arc extinguishing nozzle

Abstract

The invention discloses an arc extinguishing nozzle with a composite coating and a preparation method of the arc extinguishing nozzle with the composite coating, and the arc extinguishing nozzle with the composite coating comprises the following components in parts by mass: 40-60 parts of polytetrafluoroethylene; 15 to 25 parts of boron nitride; 10 to 20 parts of graphene modified titanium dioxide; 5 to 10 parts of rare earth doped zinc oxide; 0.5-2 parts of a dispersant; according to the arc extinguishing nozzle with the composite coating, components such as graphene modified titanium dioxide and rare earth doped zinc oxide are creatively added, so that the ablation resistance, the mechanical strength and the insulating property of the arc extinguishing nozzle are remarkably improved, and the arc extinguishing nozzle can better adapt to high-voltage and large-current complex working conditions; according to the arc extinguishing nozzle with the composite coating, the nano boron nitride-silicon carbide composite powder, the rare earth oxide modified aluminum oxide powder and the organic-inorganic hybrid binder are added, so that the wear resistance, the arc ablation resistance and the bonding strength with a base material of the coating are remarkably improved, and the service life of the arc extinguishing nozzle is prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of arc extinguishing devices in high-voltage electrical equipment, and particularly relates to an arc extinguishing nozzle with a composite coating and a preparation method thereof. BACKGROUND

[0002] In high-voltage electrical equipment (such as high-voltage circuit breakers and disconnectors), the function of the arc extinguishing nozzle is to extinguish the electric arc by spraying gas flow to protect the equipment from arc ablation. Traditional arc extinguishing nozzles mostly use a single polymer (such as polytetrafluoroethylene) or a simple inorganic filler composite system, which has the following defects:

[0003] Insufficient ablation resistance: under the action of a large current arc, the material is prone to thermal decomposition or melting, resulting in damage to the nozzle structure;

[0004] Low mechanical strength: after long-term bearing of gas flow impact and mechanical vibration, cracks or deformation are prone to occur;

[0005] Unstable insulation performance: the insulation resistance decreases significantly at high temperatures, which easily leads to secondary discharge;

[0006] Poor coating adhesion: the surface coating is prone to peeling off from the substrate, resulting in failure of the overall performance and short service life (usually less than 3000 operation cycles).

[0007] Therefore, an arc extinguishing nozzle with a composite coating and a preparation method thereof are designed. SUMMARY

[0008] In view of the above problems, the application provides an arc extinguishing nozzle with a composite coating and a preparation method thereof, which effectively solves the problems in the above background.

[0009] To achieve the above purpose, the application provides the following technical scheme: an arc extinguishing nozzle with a composite coating, which comprises the following components in mass fraction:

[0010] Polytetrafluoroethylene: 40-60 parts;

[0011] Boron nitride: 15-25 parts;

[0012] Graphene-modified titanium dioxide: 10-20 parts;

[0013] Rare earth-doped zinc oxide: 5-10 parts;

[0014] Dispersing agent: 0.5-2 parts.

[0015] Preferably, the preparation method of the graphene-modified titanium dioxide is as follows:

[0016] S1, preparation of graphene oxide: according to the mass volume ratio of graphite powder, concentrated sulfuric acid, potassium permanganate 1g:5mL:3g, graphite powder, concentrated sulfuric acid, potassium permanganate is added to the reaction kettle, stirring at low temperature of 0-5℃ for 2-3 hours, then slowly heating to 35-40℃, continue to react for 12-15 hours; after the reaction is finished, according to the mass volume ratio of graphite powder and deionized water 1g:20mL, add deionized water dilution, and according to the volume ratio of graphite powder and hydrogen peroxide 1g:0.5mL, drop hydrogen peroxide solution until the solution color turns to golden yellow, centrifugal, washing, drying to get graphene oxide;

[0017] S2, preparation of titanium dioxide nanoparticles: using sol-gel method, according to the volume ratio of tetrabutyl titanate, ethanol, water, hydrochloric acid 2:5:1:0.2, tetrabutyl titanate is slowly added to the mixed solution of ethanol, water and hydrochloric acid, stirring at room temperature with the speed of 200-300r / min for 3-4 hours, forming a uniform sol; the sol is aged at 60-80℃ for 24 hours, and the gel is obtained, then the gel is ground into powder, and calcined at 500-600℃ for 2-3 hours to obtain titanium dioxide nanoparticles;

[0018] S3, graphene modified titanium dioxide composite: according to the mass volume ratio of graphene oxide and deionized water 1g:20mL, graphene oxide is dispersed in deionized water, and ultrasonic treatment for 30-60 minutes to make it uniformly dispersed; then according to the mass ratio of graphene oxide and titanium dioxide nanoparticles 1:3, add titanium dioxide nanoparticles, stirring at 50-60℃ for 6-8 hours, while nitrogen protection; after the reaction is finished, according to the volume ratio of graphene oxide and hydrazine hydrate 1g:2mL, add hydrazine hydrate to reduce graphene oxide to graphene and composite with titanium dioxide, after centrifugal, washing, drying to get graphene modified titanium dioxide.

[0019] Preferably, the preparation method of the rare earth doped zinc oxide is as follows:

[0020] S1, mix the zinc oxide powder and cerium nitrate evenly, the doping amount of rare earth salt is 1%-5% of the mass of zinc oxide;

[0021] S2, add the mixed powder into the ball mill, ball mill at the speed of 300-400r / min for 8-10 hours, so that the rare earth ions are uniformly distributed on the surface of zinc oxide particles;

[0022] S3, sinter the ball milled powder at 800-1000℃ for 3-5 hours, promote the diffusion of rare earth ions into the zinc oxide lattice, and form stable rare earth doped zinc oxide.

[0023] A preparation method of a composite coating arc extinguishing nozzle, comprising the following steps:

[0024] S1, raw material mixing

[0025] The polytetrafluoroethylene powder, boron nitride powder, prepared graphene modified titanium dioxide, rare earth doped zinc oxide and dispersant are weighed according to the above mass fraction;

[0026] The weighed raw materials are added to a high-speed mixer and mixed at a speed of 300-500 r / min for 1-2 hours to fully and uniformly mix the components;

[0027] S2, forming

[0028] The mixed raw materials are placed in a mold, and a mold pressing forming method is used to form an arc extinguishing nozzle blank under a pressure of 10-20 MPa for 5-10 minutes;

[0029] S3, sintering

[0030] The blank is placed in a sintering furnace, heated to 360-380℃ at a heating rate of 5-10℃ / min, and kept at this temperature for 2-3 hours; then slowly cooled to room temperature at a cooling rate of 3-5℃ / min, and the sintering process is completed;

[0031] S4, coating slurry preparation

[0032] 10-20 parts of nano boron nitride-silicon carbide composite powder, 5-15 parts of rare earth oxide modified alumina powder, 3-8 parts of organic-inorganic hybrid binder, and 2-5 parts of graphite powder are placed in a ball mill tank, an appropriate amount of anhydrous ethanol is added as a dispersing medium, the ball-to-material ratio is 6:1, and the slurry is ball milled on a planetary ball mill at a speed of 250-350 r / min for 6-8 hours to fully mix and uniformly mix the various powders and form a uniform coating slurry;

[0033] S5, coating

[0034] The coating slurry is uniformly coated on the surface of the blank substrate by spraying, the spraying pressure is 0.2-0.4 MPa, the distance between the spray gun and the substrate surface is 15-20 cm, and the spraying thickness is controlled at 0.2-0.3 mm;

[0035] S6, drying and curing

[0036] The sprayed nozzle is placed in an oven and dried at 80-100℃ for 1-2 hours to completely volatilize the anhydrous ethanol, and then heated to 120-140℃ and kept for 1-2 hours to fully cure the organic-inorganic hybrid binder and form a firm composite coating;

[0037] S7, post-processing

[0038] The solidified nozzle is machined to meet the design requirements in size accuracy, and then is polished to make the coating surface roughness reach Ra 0.8-1.6 μm.

[0039] Preferably, in the S4, the preparation method of the nano boron nitride-silicon carbide composite powder is as follows:

[0040] ① Raw material preparation: take the nano boron nitride powder and the silicon carbide powder with a mass ratio of 1:1, and put them into the oven for drying at 100-120℃ for 2-3 hours to remove the water on the surface of the powder;

[0041] ② Ball milling mixing: put the dried nano boron nitride powder and the silicon carbide powder into the ball milling tank, add appropriate amount of anhydrous ethanol as a dispersion medium, and ball mill at a speed of 200-300 r / min for 8-10 hours on the planetary ball mill to fully mix and uniformly distribute the two kinds of powder;

[0042] ③ Drying treatment: pour the mixed slurry after ball milling into a culture dish, and put it into a vacuum drying oven for drying at 60-80℃ for 12-15 hours until the anhydrous ethanol is completely volatilized, to obtain the dried nano boron nitride-silicon carbide composite powder;

[0043] ④ Screening treatment: screen the dried composite powder through a 200-300 mesh screen to remove large particle impurities, to obtain the nano boron nitride-silicon carbide composite powder with uniform particle size.

[0044] Preferably, in the S4, the preparation method of the rare earth oxide modified alumina powder is as follows:

[0045] ① Raw material preparation: take the nano boron nitride powder and the silicon carbide powder with a mass ratio of 1:1, and put them into the oven for drying at 100-120℃ for 2-3 hours to remove the water on the surface of the powder;

[0046] ② Pre-sintering treatment: put the mixed powder into a high-temperature furnace, and heat it to 1200-1300℃ at a heating rate of 5-10℃ / min in air atmosphere, and keep it for 2-3 hours to make the rare earth oxide and the alumina react by solid phase reaction to form the rare earth oxide modified alumina;

[0047] ③ Ball milling and crushing: put the pre-sintered block material into a ball milling tank, add appropriate amount of deionized water as a dispersion medium, and ball mill at a speed of 300-400 r / min for 10-12 hours on the planetary ball mill to crush the block material into powder;

[0048] ④Drying and sieving: pour the milled slurry into a petri dish, place it in a vacuum drying oven and dry at 80-100 DEG C for 10-12 hours, then sieve through a 300-400 mesh screen to obtain the rare earth oxide modified alumina powder.

[0049] Preferably, the preparation method of the organic-inorganic hybrid binder in S4 is as follows:

[0050] ① Preparation of organic components: weigh an appropriate amount of epoxy resin and polyamide resin, and place them in a three-necked flask in a mass ratio of 2:1, heat and stir at 80-90 DEG C for 1-2 hours to fully mix and evenly distribute the two resins;

[0051] ② Preparation of inorganic components: weigh an appropriate amount of silica sol and alumina sol, and mix them evenly in a mass ratio of 1:1;

[0052] ③ Hybrid reaction: slowly add the inorganic components to the organic components, and stir at 60-70 DEG C for 3-4 hours to allow the organic components and inorganic components to undergo chemical crosslinking reaction, forming an organic-inorganic hybrid binder.

[0053] Compared with the prior art, the beneficial effects of the present application are:

[0054] 1、The composite coating arc extinguishing nozzle of the present application significantly improves the ablation resistance, mechanical strength and insulation performance of the arc extinguishing nozzle by innovatively adding graphene modified titanium dioxide, rare earth doped zinc oxide and other components, and can better adapt to complex working conditions of high voltage and large current;

[0055] 2、The composite coating arc extinguishing nozzle of the present application significantly improves the wear resistance, arc ablation resistance and bonding strength with the base material of the coating by adding nano boron nitride-silicon carbide composite powder, rare earth oxide modified alumina powder and organic-inorganic hybrid binder, prolonging the service life of the arc extinguishing nozzle;

[0056] 3、The nano boron nitride and silicon carbide in the nano boron nitride-silicon carbide composite powder can form a uniformly distributed hard phase in the coating, effectively resisting arc ablation and mechanical wear; the rare earth oxide modified alumina powder improves the density and high temperature stability of alumina, enhancing the bonding strength of the coating with the base material; the organic-inorganic hybrid binder combines the flexibility of organic binders and the high temperature stability of inorganic binders, further improving the performance of the coating. DETAILED DESCRIPTION

[0057] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments; based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0058] The present application provides an arc-extinguishing nozzle of composite coating, comprising the following components by mass fraction:

[0059] Polytetrafluoroethylene: 40-60 parts;

[0060] Boron nitride: 15-25 parts;

[0061] Graphene-modified titanium dioxide: 10-20 parts;

[0062] Rare earth-doped zinc oxide: 5-10 parts;

[0063] Dispersant: 0.5-2 parts.

[0064] The preparation method of graphene-modified titanium dioxide in the present embodiment is as follows:

[0065] S1, preparation of graphene oxide: according to the mass-volume ratio of graphite powder, concentrated sulfuric acid and potassium permanganate 1g:5mL:3g, graphite powder, concentrated sulfuric acid and potassium permanganate are added to the reaction kettle, stirred at low temperature of 0-5℃ for 2-3 hours, then slowly heated to 35-40℃, and continue to react for 12-15 hours; after the reaction is completed, according to the mass-volume ratio of graphite powder and deionized water 1g:20mL, deionized water is added for dilution, and according to the volume ratio of graphite powder and hydrogen peroxide 1g:0.5mL, hydrogen peroxide solution is added dropwise until the solution color turns to golden yellow, centrifuged, washed and dried to obtain graphene oxide;

[0066] S2, preparation of titanium dioxide nanoparticles: using sol-gel method, according to the volume ratio of butyl titanate, ethanol, water and hydrochloric acid 2:5:1:0.2, butyl titanate is slowly added to the mixed solution of ethanol, water and hydrochloric acid, stirred at room temperature at a speed of 200-300r / min for 3-4 hours to form a uniform sol; the sol is aged at 60-80℃ for 24 hours to obtain a gel, then the gel is ground into powder and calcined at 500-600℃ for 2-3 hours to obtain titanium dioxide nanoparticles;

[0067] S3, preparation of graphene modified titanium dioxide: graphene oxide is dispersed in deionized water at a mass-volume ratio of 1 g:20 mL, and ultrasonic treatment is performed for 30-60 minutes to uniformly disperse the graphene oxide; then, titanium dioxide nanoparticles are added at a mass ratio of graphene oxide to titanium dioxide nanoparticles of 1:3, and stirring reaction is performed at 50-60°C for 6-8 hours while nitrogen is introduced; after the reaction is completed, hydrazine hydrate is added at a volume ratio of graphene oxide to hydrazine hydrate of 1 g:2 mL to reduce the graphene oxide to graphene and to form a graphene-titanium dioxide composite, and after centrifugation, washing, and drying, graphene modified titanium dioxide is obtained.

[0068] The preparation method of the rare earth doped zinc oxide of the present embodiment is as follows:

[0069] S1, zinc oxide powder and cerium nitrate are uniformly mixed, and the doping amount of the rare earth salt is 1%-5% of the mass of the zinc oxide;

[0070] S2, the mixed powder is added to a ball mill, and ball milling is performed at a rotation speed of 300-400 r / min for 8-10 hours to uniformly distribute the rare earth ions on the surface of the zinc oxide particles;

[0071] S3, the milled powder is sintered at 800-1000°C for 3-5 hours to promote the diffusion of the rare earth ions into the zinc oxide crystal lattice, and a stable rare earth doped zinc oxide is formed.

[0072] A preparation method of an arc extinguishing nozzle of a composite coating, comprising the following steps:

[0073] S1, raw material mixing

[0074] Polytetrafluoroethylene powder, boron nitride powder, graphene modified titanium dioxide prepared, rare earth doped zinc oxide, and dispersant are weighed according to the above mass fraction;

[0075] The weighed raw materials are added to a high-speed mixer and mixed at a rotation speed of 300-500 r / min for 1-2 hours to fully and uniformly mix the components;

[0076] S2, forming

[0077] The mixed raw materials are placed in a mold, and a mold pressing forming method is used to form an arc extinguishing nozzle blank under a pressure of 10-20 MPa for 5-10 minutes;

[0078] S3, sintering

[0079] The blank is placed in a sintering furnace, heated to 360-380°C at a heating rate of 5-10°C / min, and held at this temperature for 2-3 hours; then, slowly cooled to room temperature at a cooling rate of 3-5°C / min, and the sintering process is completed;

[0080] S4, coating slurry preparation

[0081] 10-20 parts of nano boron nitride-silicon carbide composite powder, 5-15 parts of rare earth oxide modified alumina powder, 3-8 parts of organic-inorganic hybrid binder, and 2-5 parts of graphite powder were put into a ball mill tank, an appropriate amount of anhydrous ethanol was added as a dispersion medium, the ball-to-material ratio was 6:1, and the slurry was ball milled on a planetary ball mill at a speed of 250-350 r / min for 6-8 hours to fully mix and uniformly disperse the powders, thereby forming a uniform coating slurry;

[0082] S5, coating application

[0083] The coating slurry was uniformly applied to the surface of the blank substrate by spraying, the spraying pressure was 0.2-0.4 MPa, the distance between the spray gun and the substrate surface was 15-20 cm, and the spraying thickness was controlled at 0.2-0.3 mm;

[0084] S6, drying and curing

[0085] The sprayed nozzle was placed in an oven and dried at 80-100℃ for 1-2 hours to completely volatilize the anhydrous ethanol, and then heated to 120-140℃ for 1-2 hours to fully cure the organic-inorganic hybrid binder and form a firm composite coating;

[0086] S7, post-processing

[0087] The cured nozzle was machined to meet the design requirements for dimensional accuracy, and then surface polished to achieve a coating surface roughness of Ra 0.8-1.6 μm.

[0088] In S4 of this embodiment, the preparation method of the nano boron nitride-silicon carbide composite powder is as follows:

[0089] ① Raw material preparation: nano boron nitride powder and silicon carbide powder with a mass ratio of 1:1 were weighed and placed in an oven at 100-120℃ for 2-3 hours to remove the water on the surface of the powders;

[0090] ② Ball milling: the dried nano boron nitride powder and silicon carbide powder were placed in a ball mill tank, an appropriate amount of anhydrous ethanol was added as a dispersion medium, the ball-to-material ratio was 5:1, and the slurry was ball milled on a planetary ball mill at a speed of 200-300 r / min for 8-10 hours to fully mix and uniformly disperse the powders;

[0091] ③ Drying treatment: the ball-milled mixed slurry was poured into a culture dish and placed in a vacuum drying oven at 60-80℃ for 12-15 hours until the anhydrous ethanol was completely volatilized, thereby obtaining the dried nano boron nitride-silicon carbide composite powder;

[0092] ④Screening treatment: after drying, the composite powder is screened through a 200-300 mesh screen to remove large particle impurities and obtain a nano boron nitride-silicon carbide composite powder with uniform particle size.

[0093] In S4 of this embodiment, the preparation method of the rare earth oxide modified alumina powder is as follows:

[0094] ①Raw material preparation: 95% by mass of alumina powder and 5% by mass of rare earth oxide yttrium oxide are weighed and mixed uniformly in a mixer;

[0095] ②Pre-sintering treatment: the mixed powder is placed in a high-temperature furnace and heated to 1200-1300℃ at a heating rate of 5-10℃ / min under air atmosphere, and heat preserved for 2-3 hours to make the rare earth oxide and alumina react in solid phase to form rare earth oxide modified alumina;

[0096] ③Ball milling: the pre-sintered block material is placed in a ball mill tank, and an appropriate amount of deionized water is added as a dispersion medium, with a ball-to-material ratio of 8:1, and ball milling is carried out on a planetary ball mill at a speed of 300-400r / min for 10-12 hours to pulverize the block material into powder;

[0097] ④Drying and screening: the ball-milled slurry is poured into a culture dish and placed in a vacuum drying oven at 80-100℃ for 10-12 hours, and then screened through a 300-400 mesh screen to obtain a rare earth oxide modified alumina powder.

[0098] In S4 of this embodiment, the preparation method of the organic-inorganic hybrid binder is as follows:

[0099] ①Preparation of organic components: an appropriate amount of epoxy resin and polyamide resin are weighed and placed in a three-necked flask in a mass ratio of 2:1, heated and stirred at 80-90℃ for 1-2 hours to fully mix the two resins uniformly;

[0100] ②Preparation of inorganic components: an appropriate amount of silica sol and alumina sol are weighed and mixed uniformly in a mass ratio of 1:1;

[0101] ③Hybrid reaction: the inorganic components are slowly added to the organic components, and stirred at 60-70℃ for 3-4 hours to make the organic components and inorganic components undergo chemical cross-linking reaction to form an organic-inorganic hybrid binder.

[0102] Example 1:

[0103] An arc-extinguishing nozzle of a composite coating layer comprises the following components by mass fraction:

[0104] Polytetrafluoroethylene: 40 parts;

[0105] Boron nitride: 15 parts;

[0106] Graphene modified titanium dioxide: 10 parts;

[0107] Rare earth doped zinc oxide: 5 parts;

[0108] Dispersant: 0.5 parts.

[0109] The preparation method of graphene modified titanium dioxide of the present embodiment is as follows:

[0110] S1, preparation of graphene oxide: according to the mass-volume ratio of graphite powder, concentrated sulfuric acid and potassium permanganate 1g:5mL:3g, graphite powder, concentrated sulfuric acid and potassium permanganate are added to the reaction kettle, stirred at low temperature of 0℃ for 2 hours, then slowly heated to 35℃, continue to react for 12 hours; after the reaction is completed, according to the mass-volume ratio of graphite powder and deionized water 1g:20mL, add deionized water for dilution, and according to the volume ratio of graphite powder and hydrogen peroxide 1g:0.5mL, drop hydrogen peroxide solution until the solution color turns to golden yellow, centrifuge, wash and dry to obtain graphene oxide;

[0111] S2, preparation of titanium dioxide nanoparticles: using sol-gel method, according to the volume ratio of tetrabutyl titanate, ethanol, water and hydrochloric acid 2:5:1:0.2, tetrabutyl titanate is slowly added to the mixed solution of ethanol, water and hydrochloric acid, stirred at room temperature at a speed of 200r / min for 3 hours to form a uniform sol; the sol is aged at 60℃ for 24 hours to obtain a gel, then the gel is ground into powder and calcined at 500℃ for 2 hours to obtain titanium dioxide nanoparticles;

[0112] S3, composite of graphene modified titanium dioxide: according to the mass-volume ratio of graphene oxide and deionized water 1g:20mL, graphene oxide is dispersed in deionized water and ultrasonic treated for 30 minutes to make it uniformly dispersed; then according to the mass ratio of graphene oxide and titanium dioxide nanoparticles 1:3, add titanium dioxide nanoparticles and stir at 50℃ for 6 hours while nitrogen is introduced; after the reaction is completed, according to the volume ratio of graphene oxide and hydrazine hydrate 1g:2mL, add hydrazine hydrate to reduce graphene oxide to graphene and composite with titanium dioxide, after centrifugation, washing and drying, graphene modified titanium dioxide is obtained.

[0113] The preparation method of rare earth doped zinc oxide of the present embodiment is as follows:

[0114] S1, mix zinc oxide powder and rare earth salt cerium nitrate uniformly, the doping amount of rare earth salt is 1% of the mass of zinc oxide;

[0115] S2, add the mixed powder to the ball mill and mill at a speed of 300r / min for 8 hours to make the rare earth ions uniformly distributed on the surface of zinc oxide particles;

[0116] S3, sintering the milled powder at 800℃ for 3 hours to promote diffusion of rare earth ions into the zinc oxide lattice and form stable rare earth doped zinc oxide.

[0117] A method for preparing an arc-extinguishing nozzle with a composite coating, comprising the following steps:

[0118] S1, mixing raw materials

[0119] The polytetrafluoroethylene powder, boron nitride powder, prepared graphene-modified titanium dioxide, rare earth doped zinc oxide, and dispersant are weighed according to the above mass fraction;

[0120] The weighed raw materials are added to a high-speed mixer and mixed at a speed of 300 r / min for 1 hour to fully and uniformly mix the components;

[0121] S2, forming

[0122] The mixed raw materials are placed in a mold, and a mold pressing method is used to form an arc-extinguishing nozzle blank under a pressure of 10 MPa for 5 minutes;

[0123] S3, sintering

[0124] The blank is placed in a sintering furnace, heated to 360℃ at a rate of 5℃ / min, and held at this temperature for 2 hours; then slowly cooled to room temperature at a rate of 3℃ / min, completing the sintering process;

[0125] S4, coating slurry preparation

[0126] 10 parts of nano boron nitride-silicon carbide composite powder, 5 parts of rare earth oxide modified alumina powder, 3 parts of organic-inorganic hybrid binder, and 2 parts of graphite powder are placed in a ball mill tank, and an appropriate amount of anhydrous ethanol is added as a dispersing medium. The ball-to-material ratio is 6:1, and the planetary ball mill is operated at a speed of 250 r / min for 6 hours to fully mix and uniformly mix the various powders, forming a uniform coating slurry;

[0127] S5, coating

[0128] The coating slurry is uniformly coated on the surface of the blank substrate using a spraying method, with a spraying pressure of 0.2 MPa, a distance between the spray gun and the substrate surface of 15 cm, and a spraying thickness controlled at 0.2 mm;

[0129] S6, drying and curing

[0130] The sprayed nozzle is placed in an oven and dried at 80℃ for 1 hour to completely evaporate the anhydrous ethanol, and then heated to 120℃ and held for 1 hour to fully cure the organic-inorganic hybrid binder, forming a firm composite coating;

[0131] S7, post-processing

[0132] After the solidification of the nozzle, mechanical processing is performed to make the size accuracy meet the design requirements, and then surface polishing treatment is performed to make the coating surface roughness reach Ra 0.8 μm.

[0133] In S4 of the embodiment, the preparation method of the nano boron nitride-silicon carbide composite powder is as follows:

[0134] ① Raw material preparation: take the nano boron nitride powder and the silicon carbide powder with a mass ratio of 1:1, and put them into an oven for drying at 100°C for 2 hours to remove the water on the surface of the powder;

[0135] ② Ball milling mixing: put the dried nano boron nitride powder and the silicon carbide powder into a ball milling tank, add an appropriate amount of anhydrous ethanol as a dispersion medium, and ball mill at a speed of 200 r / min for 8 hours on a planetary ball mill to fully mix and uniformly disperse the two powders;

[0136] ③ Drying treatment: pour the mixed slurry after ball milling into a culture dish and put it into a vacuum drying oven for drying at 60°C for 12 hours until the anhydrous ethanol is completely volatilized, to obtain the dried nano boron nitride-silicon carbide composite powder;

[0137] ④ Screening treatment: screen the dried composite powder through a 200-mesh screen to remove large particle impurities, to obtain the nano boron nitride-silicon carbide composite powder with uniform particle size.

[0138] In S4 of the embodiment, the preparation method of the rare earth oxide modified alumina powder is as follows:

[0139] ① Raw material preparation: take the alumina powder with a mass fraction of 95% and the rare earth oxide yttrium oxide with a mass fraction of 5%, and put them into a mixer for mixing;

[0140] ② Pre-sintering treatment: put the mixed powder into a high-temperature furnace, heat it to 1200°C at a heating rate of 5°C / min in an air atmosphere, and keep it at this temperature for 2 hours to make the rare earth oxide and the alumina react in solid phase to form the rare earth oxide modified alumina;

[0141] ③ Ball milling and crushing: put the pre-sintered block material into a ball milling tank, add an appropriate amount of deionized water as a dispersion medium, and ball mill at a speed of 300 r / min for 10 hours on a planetary ball mill to crush the block material into powder;

[0142] ④ Drying and screening: pour the slurry after ball milling into a culture dish, put it into a vacuum drying oven for drying at 80°C for 10 hours, and then screen it through a 300-mesh screen to obtain the rare earth oxide modified alumina powder.

[0143] The preparation method of the organic-inorganic hybrid binder in S4 of the embodiment is as follows:

[0144] ① Preparation of the organic component: an appropriate amount of epoxy resin and polyamide resin are weighed and put into a three-necked flask in a mass ratio of 2:1, heated and stirred at 80℃ for 1 hour, so that the two resins are fully mixed and uniform;

[0145] ② Preparation of the inorganic component: an appropriate amount of silica sol and alumina sol are weighed and mixed uniformly in a mass ratio of 1:1;

[0146] ③ Hybrid reaction: the inorganic component is slowly added to the organic component, and stirred at 60℃ for 3 hours, so that the organic component and the inorganic component undergo chemical crosslinking reaction to form an organic-inorganic hybrid binder.

[0147] Example 2:

[0148] An arc-extinguishing nozzle of a composite coating layer comprises the following components in mass fraction:

[0149] Polytetrafluoroethylene: 60 parts;

[0150] Boron nitride: 25 parts;

[0151] Graphene-modified titanium dioxide: 20 parts;

[0152] Rare earth-doped zinc oxide: 10 parts;

[0153] Dispersant: 2 parts.

[0154] The preparation method of the graphene-modified titanium dioxide in the embodiment is as follows:

[0155] S1, Preparation of graphene oxide: graphite powder, concentrated sulfuric acid, and potassium permanganate are added to a reaction kettle in a mass-volume ratio of 1g:5mL:3g, stirred at a low temperature of 5℃ for 3 hours, then slowly warmed to 40℃, and continue to react for 15 hours; after the reaction is completed, deionized water is added in a mass-volume ratio of 1g:20mL, and hydrogen peroxide solution is added dropwise in a volume ratio of 1g:0.5mL until the solution color turns golden yellow, and then centrifuged, washed, and dried to obtain graphene oxide;

[0156] S2, Preparation of titanium dioxide nanoparticles: using sol-gel method, according to the volume ratio of butyl titanate, ethanol, water, hydrochloric acid 2:5:1:0.2, butyl titanate is slowly added to the mixed solution of ethanol, water and hydrochloric acid, stirring at room temperature at 300r / min for 4 hours to form a uniform sol; the sol is aged at 80℃ for 24 hours to obtain a gel, then the gel is ground into powder, calcined at 600℃ for 3 hours to obtain titanium dioxide nanoparticles;

[0157] S3, Graphene modified titanium dioxide composite: according to the mass volume ratio of graphene oxide and deionized water 1g:20mL, graphene oxide is dispersed in deionized water and ultrasonic treated for 60 minutes to make it uniformly dispersed; then according to the mass ratio of graphene oxide and titanium dioxide nanoparticles 1:3, titanium dioxide nanoparticles are added, stirring at 60℃ for 8 hours, while nitrogen is introduced; after the reaction is completed, according to the volume ratio of graphene oxide and hydrazine hydrate 1g:2mL, hydrazine hydrate is added to reduce graphene oxide to graphene and composite with titanium dioxide, after centrifugation, washing and drying, graphene modified titanium dioxide is obtained.

[0158] The preparation method of the rare earth doped zinc oxide of the embodiment is as follows:

[0159] S1, mix zinc oxide powder and cerium nitrate evenly, the doping amount of rare earth salt is 5% of the mass of zinc oxide;

[0160] S2, add the mixed powder to the ball mill and mill at 400r / min for 10 hours to make the rare earth ions uniformly distributed on the surface of the zinc oxide particles;

[0161] S3, sinter the milled powder at 1000℃ for 5 hours to promote the diffusion of rare earth ions into the zinc oxide lattice and form stable rare earth doped zinc oxide.

[0162] A preparation method of an arc extinguishing nozzle of a composite coating, comprising the following steps:

[0163] S1, raw material mixing

[0164] The polytetrafluoroethylene powder, boron nitride powder, graphene modified titanium dioxide, rare earth doped zinc oxide and dispersant are weighed according to the above mass fraction;

[0165] Put the weighed raw materials into a high-speed mixer and mix at 500r / min for 2 hours to make the ingredients fully and uniformly mixed;

[0166] S2, forming

[0167] Put the mixed raw materials into a mold and use mold pressing method to form the blank of the arc extinguishing nozzle under the pressure of 20MPa for 10 minutes.

[0168] S3, sintering

[0169] Put the blank into the sintering furnace, and heat to 380℃ at a heating rate of 10℃ / min, and keep the temperature for 3 hours; then slowly cool to room temperature at a cooling rate of 5℃ / min, to complete the sintering process;

[0170] S4, coating slurry preparation

[0171] Put 20 parts of nano boron nitride-silicon carbide composite powder, 15 parts of rare earth oxide modified alumina powder, 8 parts of organic-inorganic hybrid binder, and 5 parts of graphite powder into a ball mill tank, add an appropriate amount of anhydrous ethanol as a dispersing medium, the ball-to-material ratio is 6:1, and ball mill on a planetary ball mill at a speed of 350r / min for 8 hours to fully mix and uniformly mix the various powders to form a uniform coating slurry;

[0172] S5, coating application

[0173] The coating slurry is uniformly applied to the surface of the blank substrate by spraying, the spraying pressure is 0.4MPa, the distance between the spray gun and the substrate surface is 20cm, and the spraying thickness is controlled at 0.3mm;

[0174] S6, drying and curing

[0175] Put the sprayed nozzle into an oven, dry at 100℃ for 2 hours to completely volatilize the anhydrous ethanol, then heat to 140℃ and keep the temperature for 2 hours to fully cure the organic-inorganic hybrid binder and form a firm composite coating;

[0176] S7, post-processing

[0177] Mechanically process the cured nozzle to achieve the required dimensional accuracy, and then perform surface polishing to achieve a coating surface roughness of Ra1.6μm.

[0178] In S4 of this embodiment, the preparation method of the nano boron nitride-silicon carbide composite powder is as follows:

[0179] ① Raw material preparation: weigh 1:1 of nano boron nitride powder and silicon carbide powder, and dry them separately in an oven at 120℃ for 3 hours to remove the moisture on the surface of the powders;

[0180] ② Ball milling and mixing: put the dried nano boron nitride powder and silicon carbide powder into a ball mill tank, add an appropriate amount of anhydrous ethanol as a dispersing medium, the ball-to-material ratio is 5:1, and ball mill on a planetary ball mill at a speed of 300r / min for 10 hours to fully mix and uniformly mix the two powders;

[0181] ③ drying treatment: pour the mixed slurry after ball milling into a culture dish, put it into a vacuum drying oven and dry it at 80℃ for 15 hours until absolute ethanol is completely volatilized, to obtain dried nano boron nitride-silicon carbide composite powder;

[0182] ④ screening treatment: screen the dried composite powder through a 300 mesh screen to remove large particle impurities, to obtain nano boron nitride-silicon carbide composite powder with uniform particle size.

[0183] In S4 of this embodiment, the preparation method of the rare earth oxide modified alumina powder is as follows:

[0184] ① raw material preparation: weigh 95% by mass of alumina powder and 5% by mass of rare earth oxide yttrium oxide, and mix them evenly in a mixer;

[0185] ② pre-sintering treatment: put the mixed powder into a high-temperature furnace, heat it to 1300℃ at a heating rate of 10℃ / min in an air atmosphere, and keep it at this temperature for 3 hours, so that the rare earth oxide reacts with the alumina to form rare earth oxide modified alumina;

[0186] ③ ball milling: put the pre-sintered block material into a ball mill tank, add an appropriate amount of deionized water as a dispersing medium, and ball mill at a speed of 400r / min for 12 hours in a planetary ball mill, to crush the block material into powder;

[0187] ④ drying and screening: pour the slurry after ball milling into a culture dish, put it into a vacuum drying oven and dry it at 100℃ for 12 hours, and then screen it through a 400 mesh screen to obtain rare earth oxide modified alumina powder.

[0188] In S4 of this embodiment, the preparation method of the organic-inorganic hybrid binder is as follows:

[0189] ① organic component preparation: weigh an appropriate amount of epoxy resin and polyamide resin, and put them into a three-necked flask in a mass ratio of 2:1, heat and stir at 90℃ for 2 hours, so that the two resins are fully mixed and uniform;

[0190] ② inorganic component preparation: weigh an appropriate amount of silica sol and alumina sol, and mix them evenly in a mass ratio of 1:1;

[0191] ③ hybrid reaction: slowly add the inorganic component to the organic component, and stir at 70℃ for 4 hours to make the organic component and the inorganic component undergo chemical cross-linking reaction to form an organic-inorganic hybrid binder.

[0192] Example 3:

[0193] An arc-extinguishing nozzle of a composite coating layer comprises the following components by mass fraction:

[0194] Polytetrafluoroethylene: 50 parts;

[0195] Boron nitride: 20 parts;

[0196] Graphene-modified titanium dioxide: 15 parts;

[0197] Rare earth doped zinc oxide: 7.5 parts;

[0198] Dispersant: 1.3 parts.

[0199] The preparation method of graphene-modified titanium dioxide in this embodiment is as follows:

[0200] S1, preparation of graphene oxide: according to the mass-volume ratio of graphite powder, concentrated sulfuric acid and potassium permanganate 1g:5mL:3g, graphite powder, concentrated sulfuric acid and potassium permanganate are added to the reaction kettle, stirred at low temperature of 3℃ for 2.5 hours, then slowly heated to 37℃, continue to react for 13.5 hours; after the reaction is completed, according to the mass-volume ratio of graphite powder and deionized water 1g:20mL, add deionized water for dilution, and according to the volume ratio of graphite powder and hydrogen peroxide 1g:0.5mL, drop hydrogen peroxide solution until the solution color turns to golden yellow, centrifuge, wash and dry to obtain graphene oxide;

[0201] S2, preparation of titanium dioxide nanoparticles: according to the volume ratio of butyl titanate, ethanol, water and hydrochloric acid 2:5:1:0.2, butyl titanate is slowly added to the mixed solution of ethanol, water and hydrochloric acid, stirred at room temperature at a speed of 200-300r / min for 3.5 hours to form a uniform sol; the sol is aged at 70℃ for 24 hours to obtain a gel, then the gel is ground into powder and calcined at 550℃ for 2.5 hours to obtain titanium dioxide nanoparticles;

[0202] S3, composite of graphene-modified titanium dioxide: according to the mass-volume ratio of graphene oxide and deionized water 1g:20mL, graphene oxide is dispersed in deionized water and ultrasonically treated for 45 minutes to make it uniformly dispersed; then according to the mass ratio of graphene oxide and titanium dioxide nanoparticles 1:3, add titanium dioxide nanoparticles and stir at 55℃ for 7 hours while passing nitrogen protection; after the reaction is completed, according to the volume ratio of graphene oxide and hydrazine hydrate 1g:2mL, add hydrazine hydrate to reduce graphene oxide to graphene and composite with titanium dioxide, after centrifugation, washing and drying, graphene-modified titanium dioxide is obtained.

[0203] The preparation method of rare earth doped zinc oxide in this embodiment is as follows:

[0204] S1, mix zinc oxide powder and rare earth salt cerium nitrate uniformly, the doping amount of rare earth salt is 3% of the mass of zinc oxide;

[0205] S2, the mixed powder is added to a ball mill, and ball milling is performed at a rotating speed of 350 r / min for 9 hours, so that the rare earth ions are uniformly distributed on the surface of zinc oxide particles;

[0206] S3, the powder after ball milling is sintered at 900℃ for 4 hours, so as to promote the diffusion of the rare earth ions into the zinc oxide lattice and form stable rare earth doped zinc oxide.

[0207] A preparation method of an arc extinguishing nozzle of a composite coating, comprising the following steps:

[0208] S1, raw material mixing

[0209] Polytetrafluoroethylene powder, boron nitride powder, prepared graphene modified titanium dioxide, rare earth doped zinc oxide and dispersant are weighed according to the above mass fraction;

[0210] The weighed raw materials are added to a high-speed mixer and mixed at a rotating speed of 400 r / min for 1.5 hours, so that the components are fully and uniformly mixed;

[0211] S2, forming

[0212] The mixed raw materials are placed into a mold, and a mold pressing forming method is adopted to form an arc extinguishing nozzle blank under a pressure of 15 MPa for 8 minutes;

[0213] S3, sintering

[0214] The blank is placed into a sintering furnace, heated to 370℃ at a heating rate of 7℃ / min, and kept at this temperature for 2.5 hours; then slowly cooled to room temperature at a cooling rate of 4℃ / min, and the sintering process is completed;

[0215] S4, coating slurry preparation

[0216] 15 parts of nano boron nitride-silicon carbide composite powder, 10 parts of rare earth oxide modified alumina powder, 6 parts of organic-inorganic hybrid binder, and 3.5 parts of graphite powder are placed into a ball mill tank, an appropriate amount of anhydrous ethanol is added as a dispersing medium, the ball-to-material ratio is 6:1, and ball milling is performed on a planetary ball mill at a rotating speed of 300 r / min for 7 hours, so that the various powders are fully and uniformly mixed to form a uniform coating slurry;

[0217] S5, coating

[0218] The coating slurry is uniformly coated on the surface of the blank substrate by spraying, the spraying pressure is 0.3 MPa, the distance between the spray gun and the substrate surface is 17 cm, and the spraying thickness is controlled to be 0.3 mm;

[0219] S6, drying and curing

[0220] After spraying, the sprayed nozzle is placed in an oven, dried at 90℃ for 1.5 hours to completely volatilize the anhydrous ethanol, and then heated to 130℃ for 1.5 hours to fully cure the organic-inorganic hybrid binder to form a firm composite coating;

[0221] S7, post-processing

[0222] After curing, the nozzle is machined to achieve the required dimensional accuracy, and then surface polished to achieve a coating surface roughness of Ra1.2μm.

[0223] In S4 of this embodiment, the preparation method of the nano boron nitride-silicon carbide composite powder is as follows:

[0224] ① Raw material preparation: weigh the nano boron nitride powder and silicon carbide powder in a mass ratio of 1:1, and place them in an oven at 110℃ for 2.5 hours to remove the water on the surface of the powder;

[0225] ② Ball milling mixing: place the dried nano boron nitride powder and silicon carbide powder into a ball milling tank, add an appropriate amount of anhydrous ethanol as a dispersion medium, and ball mill at a speed of 250r / min for 9 hours on a planetary ball mill to fully mix and evenly distribute the two powders;

[0226] ③ Drying treatment: pour the mixed slurry after ball milling into a culture dish and place it in a vacuum drying oven at 70℃ for 13.5 hours until the anhydrous ethanol is completely volatilized, obtaining the dried nano boron nitride-silicon carbide composite powder;

[0227] ④ Screening treatment: screen the dried composite powder through a 250 mesh screen to remove large particle impurities, obtaining the nano boron nitride-silicon carbide composite powder with uniform particle size.

[0228] In S4 of this embodiment, the preparation method of the rare earth oxide modified alumina powder is as follows:

[0229] ① Raw material preparation: weigh the alumina powder with a mass fraction of 95% and 5% of the rare earth oxide yttrium oxide, and mix them evenly in a mixer;

[0230] ② Pre-sintering treatment: place the mixed powder in a high-temperature furnace, heat to 1250℃ at a rate of 7℃ / min in air atmosphere, and keep for 2.5 hours to make the rare earth oxide and alumina react in solid phase to form the rare earth oxide modified alumina;

[0231] ③ Ball milling and crushing: place the pre-sintered block material into a ball milling tank, add an appropriate amount of deionized water as a dispersion medium, and ball mill at a speed of 350r / min for 11 hours on a planetary ball mill to crush the block material into powder;

[0232] ④Drying and sieving: pour the milled slurry into a petri dish, place it in a vacuum drying oven at 90°C for 11 hours, and then sieve it through a 350-mesh sieve to obtain the rare earth oxide-modified alumina powder.

[0233] In S4 of this example, the preparation method of the organic-inorganic hybrid binder is as follows:

[0234] ①Preparation of organic component: weigh an appropriate amount of epoxy resin and polyamide resin, and place them in a three-necked flask in a mass ratio of 2:1. Heat and stir at 85°C for 1.5 hours to fully mix and homogenize the two resins;

[0235] ②Preparation of inorganic component: weigh an appropriate amount of silica sol and alumina sol, and mix them uniformly in a mass ratio of 1:1;

[0236] ③Hybrid reaction: slowly add the inorganic component to the organic component, and stir at 65°C for 3.5 hours to allow the organic component and the inorganic component to undergo chemical crosslinking reaction, forming the organic-inorganic hybrid binder.

[0237] It should be noted that the relational terms herein such as first and second, and the like, are used solely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0238] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An arc-extinguishing nozzle with a composite coating, characterized in that, The ingredients include the following parts by weight: Polytetrafluoroethylene: 40-60 parts; Boron nitride: 15-25 parts; Graphene-modified titanium dioxide: 10-20 parts; Rare earth-doped zinc oxide: 5-10 parts; Dispersant: 0.5-2 parts.

2. The arc-extinguishing nozzle with a composite coating according to claim 1, characterized in that, The preparation method of the graphene-modified titanium dioxide is as follows: S1. Preparation of graphene oxide: Graphene powder, concentrated sulfuric acid, and potassium permanganate were added to a reaction vessel at a mass-to-volume ratio of 1g:5mL:3g. The mixture was stirred and reacted at a low temperature of 0-5℃ for 2-3 hours, then the temperature was slowly increased to 35-40℃, and the reaction continued for 12-15 hours. After the reaction was completed, deionized water was added at a mass-to-volume ratio of 1g:20mL to dilute the mixture. Hydrogen peroxide solution was added dropwise at a volume ratio of 1g:0.5mL to graphene powder until the solution turned golden yellow. After centrifugation, washing, and drying, graphene oxide was obtained. S2. Preparation of titanium dioxide nanoparticles: Using the sol-gel method, tetrabutyl titanate, ethanol, water, and hydrochloric acid were slowly added dropwise to a mixed solution of ethanol, water, and hydrochloric acid at a volume ratio of 2:5:1:0.

2. The solution was stirred at 200-300 r / min for 3-4 hours at room temperature to form a uniform sol. The sol was aged at 60-80℃ for 24 hours to obtain a gel. The gel was then ground into powder and calcined at 500-600℃ for 2-3 hours to obtain titanium dioxide nanoparticles. S3. Graphene-modified titanium dioxide composite: Graphene oxide was dispersed in deionized water at a mass-to-volume ratio of 1g:20mL and ultrasonically treated for 30-60 minutes to ensure uniform dispersion. Then, titanium dioxide nanoparticles were added at a mass ratio of 1:3 (graphene oxide to titanium dioxide nanoparticles), and the mixture was stirred at 50-60℃ for 6-8 hours under nitrogen protection. After the reaction, hydrazine hydrate was added at a volume ratio of 1g:2mL (graphene oxide to hydrazine hydrate) to reduce the graphene oxide back to graphene, which was then combined with titanium dioxide. After centrifugation, washing, and drying, graphene-modified titanium dioxide was obtained.

3. The arc-extinguishing nozzle with a composite coating according to claim 1, characterized in that, The method for preparing the rare earth-doped zinc oxide is as follows: S1. Mix zinc oxide powder with rare earth salt cerium nitrate evenly, with the amount of rare earth salt being 1%-5% of the mass of zinc oxide; S2. Add the mixed powder to a ball mill and ball mill at a speed of 300-400 r / min for 8-10 hours to make rare earth ions evenly distributed on the surface of zinc oxide particles. S3. Sinter the ball-milled powder at 800-1000℃ for 3-5 hours to promote the diffusion of rare earth ions into the zinc oxide lattice and form stable rare earth-doped zinc oxide.

4. A method for preparing a composite-coated arc-extinguishing nozzle, characterized in that, Includes the following steps: S1, Raw material mixing Weigh out the polytetrafluoroethylene powder, boron nitride powder, prepared graphene-modified titanium dioxide, rare earth-doped zinc oxide, and dispersant according to the above-mentioned mass proportions. Add the weighed raw materials to a high-speed mixer and mix at a speed of 300-500 r / min for 1-2 hours to ensure that all components are fully and evenly mixed. S2, Molding The mixed raw materials are placed into a mold and molded using a compression molding method. The pressure is maintained at 10-20MPa for 5-10 minutes to form a blank for the arc-extinguishing nozzle. S3, sintering The blank is placed in a sintering furnace and heated to 360-380℃ at a heating rate of 5-10℃ / min, and held at this temperature for 2-3 hours; then it is slowly cooled to room temperature at a cooling rate of 3-5℃ / min to complete the sintering process. S4. Preparation of coating slurry Place 10-20 parts of nano boron nitride-silicon carbide composite powder, 5-15 parts of rare earth oxide modified alumina powder, 3-8 parts of organic-inorganic hybrid binder, and 2-5 parts of graphite powder into a ball mill jar, add an appropriate amount of anhydrous ethanol as a dispersion medium, and the ball-to-powder ratio is 6:

1. Ball mill the powder in a planetary ball mill at a speed of 250-350 r / min for 6-8 hours to ensure that the powders are fully mixed and uniform, forming a uniform coating slurry. S5, Coating Application The coating slurry is uniformly applied to the surface of the substrate by spraying. The spraying pressure is 0.2-0.4 MPa, the distance between the spray gun and the substrate surface is 15-20 cm, and the spraying thickness is controlled at 0.2-0.3 mm. S6, Drying and Curing Place the sprayed nozzles in an oven and dry them at 80-100℃ for 1-2 hours to allow the anhydrous ethanol to evaporate completely. Then raise the temperature to 120-140℃ and keep it at that temperature for 1-2 hours to allow the organic-inorganic hybrid binder to fully cure and form a strong composite coating. S7, Post-processing The cured nozzle is machined to meet the design requirements in terms of dimensional accuracy, and then the surface is polished to achieve a surface roughness of Ra0.8-1.6μm.

5. The method for preparing a composite coating arc-extinguishing nozzle according to claim 4, characterized in that, The preparation method of the nano boron nitride-silicon carbide composite powder in step S4 is as follows: ① Raw material preparation: Weigh out nano boron nitride powder and silicon carbide powder with a mass ratio of 1:1, and dry them separately in an oven at 100-120℃ for 2-3 hours to remove moisture from the surface of the powder. ② Ball milling and mixing: Place the dried nano boron nitride powder and silicon carbide powder into a ball mill jar, add an appropriate amount of anhydrous ethanol as a dispersion medium, the ball-to-material ratio is 5:1, and ball mill on a planetary ball mill at a speed of 200-300 r / min for 8-10 hours to ensure that the two powders are fully and evenly mixed. ③ Drying treatment: Pour the ball-milled slurry into a petri dish and place it in a vacuum drying oven at 60-80℃ for 12-15 hours until the anhydrous ethanol is completely evaporated to obtain dried nano boron nitride-silicon carbide composite powder. ④ Sieving process: The dried composite powder is sieved through a 200-300 mesh sieve to remove large particle impurities and obtain nano boron nitride-silicon carbide composite powder with uniform particle size.

6. The method for preparing a composite coating arc-extinguishing nozzle according to claim 4, characterized in that, In step S4, the method for preparing rare earth oxide modified alumina powder is as follows: ① Raw material preparation: Weigh 95% alumina powder and 5% rare earth oxide yttrium oxide, and mix them evenly in a mixer; ② Pre-calcination treatment: The mixed powder is placed in a high-temperature furnace and heated to 1200-1300℃ at a heating rate of 5-10℃ / min in an air atmosphere. The temperature is held for 2-3 hours to allow the rare earth oxides and alumina to undergo a solid-phase reaction to form rare earth oxide modified alumina. ③ Ball milling: Put the pre-calcined lumpy material into a ball mill jar, add an appropriate amount of deionized water as a dispersion medium, the ball-to-material ratio is 8:1, and ball mill on a planetary ball mill at a speed of 300-400 r / min for 10-12 hours to crush the lumpy material into powder. ④ Drying and sieving: Pour the ball-milled slurry into a petri dish, place it in a vacuum drying oven and dry it at 80-100℃ for 10-12 hours, and then sieve it through a 300-400 mesh sieve to obtain rare earth oxide modified alumina powder.

7. The method for preparing a composite coating arc-extinguishing nozzle according to claim 4, characterized in that, In step S4, the organic-inorganic hybrid binder is prepared as follows: ①Preparation of organic components: Weigh appropriate amounts of epoxy resin and polyamide resin, and put them into a three-necked flask in a mass ratio of 2:

1. Heat and stir at 80-90℃ for 1-2 hours to ensure that the two resins are fully mixed. ② Inorganic component preparation: Weigh appropriate amounts of silica sol and aluminum sol, and mix them evenly in a mass ratio of 1:1; ③ Hybridization reaction: The inorganic component is slowly added to the organic component, and the mixture is stirred at 60-70℃ for 3-4 hours to allow the organic and inorganic components to undergo a chemical cross-linking reaction, forming an organic-inorganic hybrid binder.