CN111139424A - Stainless steel wet hydrogen preparation method for improving thermal emissivity and application - Google Patents
Stainless steel wet hydrogen preparation method for improving thermal emissivity and application Download PDFInfo
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- C23C4/134—Plasma spraying
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- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
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Abstract
The invention discloses a preparation method and application of stainless steel wet hydrogen for improving a thermal emissivity, and belongs to the technical field of coating materials. The method comprises the following steps: s1: matrix treatment, S2 spray powder preparation, S3: preparing a coating; according to the invention, the double coating is sprayed on the surface of the stainless steel substrate, so that the bonding force and the wear resistance of the coating and the surface of the coating are improved, and the heat dissipation capacity of the inner surface of the tube shell is greatly improved, meanwhile, the hollow graphene with a three-dimensional structure is added in the first coating, so that the heat dissipation capacity of the inner surface of the stainless steel tube shell is improved, the graphene has extremely high heat conductivity, the heat radiation coefficient of the coating can be greatly improved, a plurality of grooves are formed on the surface of the second coating by performing laser etching on the surface of the second coating, the surface area of the second coating is increased, the heat conduction and heat dissipation performance of the coating is accelerated, the heat radiation coefficient is further improved, and the heat radiation coefficient of the coating is up to 0.93-0.96.
Description
Technical Field
The invention belongs to the technical field of coating materials, and particularly relates to a preparation method and application of stainless steel wet hydrogen for improving a thermal emissivity.
Background
The rotating anode X-ray tube is a high vacuum electric vacuum device, the working principle is that high voltage (generally 125-150kV) is added to the two ends of the anode and the cathode of the X-ray tube, electron beams emitted by a cathode bombard an anode target surface under the action of a high vacuum high-voltage electric field to generate X-rays, only a small part of the electron kinetic energy bombarded to the anode surface is converted into the X-rays, about 98% of the electron kinetic energy is converted into heat energy through a complex energy conversion process, and the temperature of the target plate is rapidly increased. Since the X-ray tube is a vacuum device, the thermal conduction within the tube is rather undesirable. If the heat generated by the target disk is not dissipated in time, the electric vacuum performance of the ray tube is influenced, the vacuum degree in the ray tube is reduced, the imaging definition is reduced, and the service life of the ray tube is influenced. Therefore, in the prior art, a black chromium coating is plated on a target disk of a rotary anode X-ray tube, and a metal coating is sprayed on the surface of the target disk by using a thermal spraying technology, so that the aim of improving the thermal emissivity of the target disk and helping the target disk to quickly dissipate heat is fulfilled.
In order to timely conduct a large amount of heat generated by the rotary anode X-ray tube during working to an insulating medium oil layer outside the vacuum tube, the metal coating is sprayed on the inner surface of the tube sleeve, so that the purpose of improving the thermal emissivity of the tube sleeve is achieved.
The working temperature of the surface of the anode rotor can reach 600-700 ℃, so that the metal coating is required to resist high temperature; in order to dissipate the heat, the coating must have a high thermal emissivity and the metal coating must be strong and non-peeling to the substrate of the inner surface of the pipe sleeve.
Therefore, it is necessary to prepare pipe sleeves coated with a high emissivity metal coating to meet practical production requirements.
Disclosure of Invention
Aiming at the problems, the invention provides a preparation method and application of stainless steel wet hydrogen for improving the thermal emissivity.
The technical scheme of the invention is as follows: a stainless steel wet hydrogen preparation method for improving the thermal emissivity mainly comprises the following steps:
s1: substrate treatment
Carrying out ultrasonic treatment on the surface of a stainless steel substrate by using an acetone solution, cleaning and drying the surface of the stainless steel substrate subjected to ultrasonic treatment by using deionized water, and finally carrying out roughening treatment on the surface of the cleaned substrate;
s2 spray powder preparation
S21: wet hydrogen milling: preparing nickel alloy matrix powder by taking 2.3-3.5g of nickel sulfate hexahydrate, 20-22g of potassium sodium tartrate, 0.15-0.2g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution by utilizing a wet hydrogen thermal reduction technology;
s22: emulsifying and pulping: mixing 65-75% of nickel alloy matrix powder and 4.5-8.2% of TiO according to weight percentage2、3-5％Nb2O5、2-5％Fe2O3、1-3％MnO2Uniformly mixing the powder and the rest of the adhesive to obtain a mixture, adding deionized water which is 0.4-0.5 time of the weight of the mixture into the mixture, and performing ultrasonic dispersion to prepare mixed slurry I;
s23: spray drying: spray-drying the mixed slurry I in a spray-drying tower at the temperature of 180-220 ℃;
s24: spark plasma sintering: placing the spray-dried powder in a discharge plasma sintering furnace for sintering treatment for 2-3h, and finally cooling and opening the furnace along with the furnace to obtain a finished product I of spraying powder;
s3: preparation of the coating
S31 preparation of the first coating:
s311: preparing materials: according to the following steps: 1, adding hollow graphene into the mixture obtained in the step S22, preparing a mixed slurry II according to the subsequent steps of S12, and finally preparing a finished spraying powder II according to the methods of S23 and S24;
s312: coating: fixing the stainless steel substrate on a workbench, and spraying the finished product of the spraying powder II to the surface of the stainless steel substrate by utilizing physical vapor deposition to coat the surface of the stainless steel substrate with a first coating;
s32: preparing a second coating:
s321: plasma spraying: spraying the finished product of the spraying powder to the surface of the stainless steel substrate coated with the first coating by adopting a plasma spraying technology at the temperature of 120-140 ℃ to form the stainless steel substrate with double coatings, and then treating the surface of the second coating by utilizing a laser etching process.
Further, the wet hydrogen milling process in step S21 includes: adding water into 2.3-3.5g of nickel sulfate hexahydrate, 20-22g of potassium sodium tartrate, 0.15-0.2g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution to prepare 100mL of mixed solution, then heating the mixed solution to 85-95 ℃, finally placing the mixed solution in a high-pressure hydrogen reduction reaction kettle, introducing hydrogen with the pressure of 3-4.5MPa, heating to 150 ℃ and 170 ℃, reacting for 6-8h, collecting and washing and filtering sediments in the kettle, drying for 2-3h to obtain nickel alloy matrix powder, and preparing the powder taking the nickel alloy as the matrix by a wet hydrogen reduction method, wherein the control is carried out.
Further, the sintering pressure of the spark plasma sintering in the step S24 is 50-250MPa, the sintering temperature is 800-1500 ℃, the performance of the nickel alloy product is improved along with the increase of the sintering temperature, but the performance of the nickel alloy product is reduced when the sintering temperature reaches a certain value, because the sintering temperature is a function of the sintering time, namely the sintering temperature is high, the sintering time can be shortened, and vice versa, but the sintering temperature has an upper limit, although the sintering time is short, the crystal grains become larger and the alloy performance is deteriorated, therefore, the sintering temperature and the sintering time are not absolute, in the step S23, the good sintering temperature of the spark plasma sintering nickel alloy powder at 800-1500 ℃ is not reached, when the sintering temperature is lower than 800, the complete sintering is not reached, the heat is not sufficiently transferred to the inside of the nickel alloy product, so that the nickel alloy product is loose and not compact, the crystal grains in the sintered body are distributed unevenly, when the sintering temperature is higher than 1500 ℃, the crystal grains are enlarged, the alloy performance is deteriorated, and the phenomena of pores, crystal grain growth, crystal grain agglomeration and the like are generated, so that the hardness of the product is reduced.
Further, the roughening treatment in step S1 is to roughen the surface of the stainless steel substrate by using a suction sand blower, the sand used is brown corundum, and the roughening treatment is performed on the surface of the stainless steel substrate by using the brown corundum, so as to increase the surface roughness of the stainless steel substrate, thereby improving the bonding force between the stainless steel substrate and the coating, and thus improving the thermal radiation coefficient.
Further, the specific preparation process of the hollow graphene in step S311 is as follows:
(1) placing carbon particles with the particle size of 300-350 mu m into a fluidized bed, and carrying out fluidization treatment on the carbon particles by using a vulcanizing gas, wherein the vulcanizing gas is argon;
(2) putting tetramethylsilane into a constant-temperature heater to heat to form steam, and introducing acetylene into the steam to pyrolyze the steam to form carbon composite powder;
(3) the method comprises the following steps of carrying out vacuum heat treatment on the composite powder of carbon to obtain a high-purity vacuum graphene material, preparing graphene into a hollow three-dimensional structure in the above mode, uniformly distributing the graphene with the hollow three-dimensional structure on a first coating, and increasing the internal space of the first coating, so that the heat dissipation capacity of the inner surface of the stainless steel pipe shell is improved, and meanwhile, the graphene has extremely high heat conductivity and coefficient of thermal radiation, and the coefficient of thermal radiation of the coating can be greatly improved.
Further, the binder in step S22 is polyanionic cellulose, which is an advanced replacement product of carboxymethyl cellulose, and the polyanionic cellulose forms a transparent solution with a certain viscosity, has good heat resistance stability and salt resistance, and strong antibacterial property, and can be completely burned or volatilized below 300 ℃ in the subsequent spray drying process, and cannot become an impurity in the thermal spray coating.
Further, in step S312, when the surface of the stainless steel substrate is subjected to the physical vapor deposition treatment, the stainless steel substrate is preheated by the plasma flame flow, and the preheating temperature is controlled not to exceed 150 ℃, so that on one hand, moisture on the surface of the substrate can be removed, and the moisture is prevented from affecting the bonding force between the stainless steel substrate and the first coating, and on the other hand, the surface temperature of the stainless steel substrate is prevented from suddenly rising, so that cracks are generated on the surface of the coating, and the hardness, wear resistance and high temperature resistance of the surface of the coating are affected.
Furthermore, the stainless steel prepared by the wet hydrogen method can be applied to the inner surface of the tube shell of the X-ray tube, the inner surface of the tube shell made of the stainless steel is prepared by the wet hydrogen method, the thermal radiation coefficient of the inner surface of the tube shell can be improved, the problem that the tube shell of the existing X-ray tube is poor in heat dissipation and heat absorption effects is solved, and the service life of the X-ray tube is prolonged.
Further, the spraying process parameters of the plasma spraying technique in S321 are as follows: the spraying gas is a mixed gas of argon and hydrogen, and the flow rate of the mixed gas is 1.8-2.2m3The current is 700-900A, the powder feeding amount is 50-70g/min, and the spraying distance is 60-150 mm.
Further, in step S321, the specific process of the laser etching process includes:
(1) placing the stainless steel substrate coated with the double coating on a working platform of a laser etching machine and positioning;
(2) adjusting the height of a laser head of a laser etching machine to enable a laser focus to fall on the right upper end of the stainless steel substrate coated with the double coatings;
(3) adjusting the working parameters of a laser etching machine, carrying out laser etching on the surface of the stainless steel substrate coated with the double coating, wherein the laser power is 3-5W, the laser pulse frequency is 40-95kHz, and the laser etching linear speed is 800 plus materials 1300 mm/s.
The invention has the beneficial effects that: the invention not only improves the binding force and the wear resistance of the coating and the surface of the stainless steel substrate by spraying the double coatings on the surface of the stainless steel substrate, but also greatly improves the heat dissipation capacity of the inner surface of the tube shell so as to meet the use requirement, simultaneously, the heat penetrates through the hollow graphene and is dissipated from the inside by adding the hollow graphene with the three-dimensional structure into the first coating, not only improves the heat dissipation capacity of the inner surface of the stainless steel tube shell, but also the graphene has extremely high heat conductivity and heat dissipation coefficient, can greatly improve the heat dissipation coefficient of the coating, and the first coating made of the material communicated with the second coating and the surface of the stainless steel substrate is added on the surface of the second coating, so that a plurality of grooves are formed on the surface of the second coating while the integral wear resistance and high temperature resistance of the coating are improved, the surface area of the second coating is increased, and the heat conduction and dissipation performance of the coating is accelerated, further improves the emissivity coefficient, and leads the emissivity coefficient of the coating to be as high as 0.93-0.96.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following examples, but the scope of the present invention is not limited thereto.
Example 1
A stainless steel wet hydrogen preparation method for improving the thermal emissivity mainly comprises the following steps:
s1: substrate treatment
Carrying out ultrasonic treatment on the surface of a stainless steel substrate by using an acetone solution, cleaning and drying the surface of the stainless steel substrate subjected to ultrasonic treatment by using deionized water, and finally roughening the surface of the cleaned substrate by using a suction type sand blasting machine, wherein the used sand is brown corundum, and roughening treatment is carried out on the surface of the stainless steel substrate by using the brown corundum to increase the surface roughness of the stainless steel substrate, so that the binding force between the stainless steel substrate and a coating is improved, and the thermal radiation coefficient is improved;
s2 spray powder preparation
S21: wet hydrogen milling: preparing nickel alloy matrix powder by taking 2.3g of nickel sulfate hexahydrate, 20g of potassium sodium tartrate, 0.15g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution by utilizing a wet hydrogen thermal reduction technology;
s22: emulsifying and pulping: mixing 65 percent of nickel alloy matrix powder and 4.5 percent of TiO according to weight percentage2、3％Nb2O5、2％Fe2O3、1％MnO2Mixing the powder and the rest polyanionic cellulose uniformly to obtain a mixture, and mixingDeionized water which is 0.4 time of the weight of the mixture is added for ultrasonic dispersion to prepare mixed slurry I, polyanionic cellulose is an advanced updated product of carboxymethyl cellulose, the polyanionic cellulose can form a transparent solution with certain viscosity, has good heat resistance stability and salt resistance and strong antibacterial property, and can be completely burnt or volatilized below 300 ℃ in the subsequent spray drying process without becoming impurities in the thermal spraying coating;
s23: spray drying: spray drying the mixed slurry I in a spray drying tower at the temperature of 180 ℃;
s24: spark plasma sintering: the spray dried powder is placed in a discharge plasma sintering furnace for sintering treatment for 2h, wherein the sintering pressure of the discharge plasma sintering is 50MPa, the sintering temperature is 800 ℃, finally, the furnace is cooled and opened along with the furnace, and a finished product of the spray powder is obtained, the performance of a nickel alloy product is improved along with the increase of the sintering temperature, but the performance of the product begins to be reduced when the sintering temperature reaches a certain value, because the sintering temperature is a function of the sintering time, namely the sintering temperature is higher than the sintering temperature, the sintering time can be shortened, and vice versa, but the sintering temperature has an upper limit, and the sintering temperature is higher than the upper limit, although the sintering time is short, the crystal grains become larger, the alloy performance is deteriorated, so the sintering temperature and the sintering time are not absolute, in step S23, the better sintering temperature of the 800 discharge plasma sintering nickel alloy powder is realized, and when the sintering temperature is lower than 800, the complete sintering is not reached, heat is not fully transferred to the interior of the nickel alloy product, so that the sintered body is loose and not compact, and the crystal grains in the sintered body are distributed unevenly;
s3: preparation of the coating
S31 preparation of the first coating:
s311: preparing materials: according to the following steps: 1, adding hollow graphene into the mixture obtained in the step S22, preparing a mixed slurry II according to the subsequent steps of S12, and finally preparing a finished spraying powder II according to the methods of S23 and S24;
s312: coating: fixing the stainless steel substrate on a workbench, and spraying the finished product of the spraying powder II to the surface of the stainless steel substrate by utilizing physical vapor deposition to coat the surface of the stainless steel substrate with a first coating;
s32: preparing a second coating:
s321: plasma spraying: spraying the first spraying powder finished product to the surface of the stainless steel substrate coated with the first coating by adopting a plasma spraying technology at the temperature of 120 ℃ to form the stainless steel substrate with double coatings, and then treating the surface of the second coating by utilizing a laser etching process.
The stainless steel prepared by the wet hydrogen method can be applied to the inner surface of the tube shell of the X-ray tube, can improve the thermal radiation coefficient of the inner surface of the tube shell, solves the problem of poor heat dissipation and heat absorption effects of the tube shell of the traditional X-ray tube, and prolongs the service life of the X-ray tube.
Example 2
A stainless steel wet hydrogen preparation method for improving the thermal emissivity mainly comprises the following steps:
s1: substrate treatment
Carrying out ultrasonic treatment on the surface of a stainless steel substrate by using an acetone solution, cleaning and drying the surface of the stainless steel substrate subjected to ultrasonic treatment by using deionized water, and finally roughening the surface of the cleaned substrate by using a suction type sand blasting machine, wherein the used sand is brown corundum, and roughening treatment is carried out on the surface of the stainless steel substrate by using the brown corundum to increase the surface roughness of the stainless steel substrate, so that the binding force between the stainless steel substrate and a coating is improved, and the thermal radiation coefficient is improved;
s2 spray powder preparation
S21: wet hydrogen milling: preparing nickel alloy matrix powder by taking 2.8g of nickel sulfate hexahydrate, 21g of potassium sodium tartrate, 0.18g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution by utilizing a wet hydrogen thermal reduction technology;
s22: emulsifying and pulping: preparing the materials according to the weight percentage, taking 70 percent of nickel alloy matrix powder and 6.8 percent of TiO2、4％Nb2O5、4％Fe2O3、2％MnO2Mixing the powder and the rest polyanionic cellulose uniformly to obtain a mixture, and adding 0 weight of the mixture45 times of deionized water is subjected to ultrasonic dispersion to be prepared into mixed slurry I, polyanionic cellulose is an advanced updating product of carboxymethyl cellulose, the polyanionic cellulose can form a transparent solution with certain viscosity, and the solution has good heat resistance stability and salt resistance and strong antibacterial property, and can be completely burnt or volatilized below 300 ℃ in the subsequent spray drying process, so that the solution cannot become impurities in the thermal spraying coating;
s23: spray drying: spray drying the mixed slurry I in a spray drying tower at the temperature of 200 ℃;
s24: spark plasma sintering: the spray dried powder is placed in a discharge plasma sintering furnace for sintering treatment for 2.5h, wherein the sintering pressure of the discharge plasma sintering is 100MPa, the sintering temperature is 1000 ℃, and finally the furnace is cooled and opened to obtain a spray powder finished product I, the performance of a nickel alloy product is improved along with the increase of the sintering temperature, but the performance of the product begins to be reduced when the sintering temperature reaches a certain value, because the sintering temperature is a function of the sintering time, namely the sintering temperature is higher than the sintering time and can be shortened, and vice versa, but the sintering temperature has an upper limit, and the sintering temperature is higher than the upper limit, so that the crystal grains are enlarged and the alloy performance is deteriorated although the sintering time is short, therefore, the sintering temperature and the sintering time are not absolute, in step S23, the better sintering temperature of the 1000 ℃ discharge plasma sintering nickel alloy powder is achieved, and when the sintering temperature is lower than 800, the complete sintering is not achieved, the heat is not fully transferred to the inside of the nickel alloy product, so that the sintered body is loose and not compact, the crystal grains in the sintered body are distributed unevenly, when the sintering temperature is higher than 1500 ℃, the crystal grains are enlarged, the alloy performance is deteriorated, and the phenomena of pores, crystal grain growth, crystal grain agglomeration and the like are generated, so that the hardness of the product is reduced;
s3: preparation of the coating
S31 preparation of the first coating:
s311: preparing materials: according to the following steps: 1, adding hollow graphene into the mixture obtained in the step S22, preparing a mixed slurry II according to the subsequent steps of S12, and finally preparing a finished spraying powder II according to the methods of S23 and S24;
s312: coating: fixing the stainless steel substrate on a workbench, and spraying the finished product of the spraying powder II to the surface of the stainless steel substrate by utilizing physical vapor deposition to coat the surface of the stainless steel substrate with a first coating;
s32: preparing a second coating:
s321: plasma spraying: spraying the first spraying powder finished product to the surface of the stainless steel substrate coated with the first coating by adopting a plasma spraying technology at the temperature of 130 ℃ to form the stainless steel substrate with double coatings, and then treating the surface of the second coating by utilizing a laser etching process.
The stainless steel prepared by the wet hydrogen method is used for preparing the inner surface of the tube shell made of the stainless steel material by the wet hydrogen method, so that the thermal radiation coefficient of the inner surface of the tube shell can be improved, the problem that the tube shell of the existing X-ray tube is poor in heat dissipation and heat absorption effects is solved, and the service life of the X-ray tube is prolonged.
Example 3
A stainless steel wet hydrogen preparation method for improving the thermal emissivity mainly comprises the following steps:
s1: substrate treatment
Carrying out ultrasonic treatment on the surface of a stainless steel substrate by using an acetone solution, cleaning and drying the surface of the stainless steel substrate subjected to ultrasonic treatment by using deionized water, and finally roughening the surface of the cleaned substrate by using a suction type sand blasting machine, wherein the used sand is brown corundum, and roughening treatment is carried out on the surface of the stainless steel substrate by using the brown corundum to increase the surface roughness of the stainless steel substrate, so that the binding force between the stainless steel substrate and a coating is improved, and the thermal radiation coefficient is improved;
s2 spray powder preparation
S21: wet hydrogen milling: taking 3.5g of nickel sulfate hexahydrate, 22g of potassium sodium tartrate, 0.2g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution, and preparing nickel alloy matrix powder by utilizing a wet hydrogen thermal reduction technology;
s22: emulsifying and pulping: mixing 75% of nickel alloy matrix powder and 8.2% of TiO according to weight percentage2、5％Nb2O5、5％Fe2O3、3％MnO2The powder and the balance of polyanionic cellulose are uniformly mixed to obtain a mixture, deionized water which is 0.4-0.5 time of the weight of the mixture is added into the mixture for ultrasonic dispersion to prepare mixed slurry I, the polyanionic cellulose is a high-grade replacement product of carboxymethyl cellulose, the polyanionic cellulose can form a transparent solution with certain viscosity, has good heat resistance stability and salt resistance and strong antibacterial property, and can be completely burnt or volatilized below 300 ℃ in the subsequent spray drying process without becoming impurities in the thermal spraying coating;
s23: spray drying: spray drying the mixed slurry I in a spray drying tower at 220 ℃;
s24: spark plasma sintering: the spray dried powder is placed in a discharge plasma sintering furnace for sintering treatment for 3h, wherein the sintering pressure of the discharge plasma sintering is 250MPa, the sintering temperature is 1500 ℃, finally, the furnace is cooled and opened along with the furnace, and a finished product of the spray powder is obtained, the performance of a nickel alloy product is improved along with the increase of the sintering temperature, but the performance of the product begins to be reduced when the sintering temperature reaches a certain value, because the sintering temperature is a function of the sintering time, namely the sintering temperature is higher than the sintering temperature, the sintering time can be shortened, and vice versa, but the sintering temperature has an upper limit, and the sintering temperature is higher than the upper limit, although the sintering time is short, the crystal grains become larger, the alloy performance is deteriorated, so the sintering temperature and the sintering time are not absolute, in step S23, the better sintering temperature of the discharge plasma sintering nickel alloy powder at 1500 ℃ is achieved, and when the sintering temperature is lower than 800, the complete sintering is not achieved, the heat is not fully transferred to the inside of the nickel alloy product, so that the sintered body is loose and not compact, the crystal grains in the sintered body are distributed unevenly, when the sintering temperature is higher than 1500 ℃, the crystal grains are enlarged, the alloy performance is deteriorated, and the phenomena of pores, crystal grain growth, crystal grain agglomeration and the like are generated, so that the hardness of the product is reduced;
s3: preparation of the coating
S31 preparation of the first coating:
s311: preparing materials: according to the following steps: 1, adding hollow graphene into the mixture obtained in the step S22, preparing a mixed slurry II according to the subsequent steps of S12, and finally preparing a finished spraying powder II according to the methods of S23 and S24;
s312: coating: fixing the stainless steel substrate on a workbench, and spraying the finished product of the spraying powder II to the surface of the stainless steel substrate by utilizing physical vapor deposition to coat the surface of the stainless steel substrate with a first coating;
s32: preparing a second coating:
s321: plasma spraying: spraying the first spraying powder finished product to the surface of the stainless steel substrate coated with the first coating by adopting a plasma spraying technology at the temperature of 140 ℃ to form the stainless steel substrate with double coatings, and then treating the surface of the second coating by utilizing a laser etching process.
The stainless steel prepared by the wet hydrogen method is used for preparing the inner surface of the tube shell made of the stainless steel material by the wet hydrogen method, so that the thermal radiation coefficient of the inner surface of the tube shell can be improved, the problem that the tube shell of the existing X-ray tube is poor in heat dissipation and heat absorption effects is solved, and the service life of the X-ray tube is prolonged.
Example 4
This embodiment is substantially the same as embodiment 2 except that:
the specific process of wet hydrogen milling in step S21 is: preparing 100mL of mixed solution by adding water into 3.5g of nickel sulfate hexahydrate, 22g of potassium sodium tartrate, 0.2g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution, heating the mixed solution to 90 ℃, finally placing the mixed solution in a high-pressure hydrogen reduction reaction kettle, introducing hydrogen with the pressure of 4MPa, heating to 160 ℃, reacting for 7 hours, collecting and washing sediments in the kettle, filtering, drying for 2.5 hours to obtain nickel alloy matrix powder, preparing powder taking a nickel alloy as a matrix by a wet hydrogen reduction mode, and controlling.
Example 5
This example is substantially the same as example 4, except that:
the specific preparation process of the hollow graphene in step S311 is as follows:
(1) placing carbon particles with the particle size of 330 mu m into a fluidized bed, and fluidizing the carbon particles by utilizing a vulcanizing gas, wherein the vulcanizing gas is argon;
(2) putting tetramethylsilane into a constant-temperature heater to heat to form steam, and introducing acetylene into the steam to pyrolyze the steam to form carbon composite powder;
(3) the method comprises the following steps of carrying out vacuum heat treatment on the composite powder of carbon to obtain a high-purity vacuum graphene material, preparing graphene into a hollow three-dimensional structure in the above mode, uniformly distributing the graphene with the hollow three-dimensional structure on a first coating, and increasing the internal space of the first coating, so that the heat dissipation capacity of the inner surface of the stainless steel pipe shell is improved, and meanwhile, the graphene has extremely high heat conductivity and coefficient of thermal radiation, and the coefficient of thermal radiation of the coating can be greatly improved.
Example 6
This example is substantially the same as example 5 except that:
in step S312, when the surface of the stainless steel substrate is subjected to the physical vapor deposition treatment, the stainless steel substrate is preheated by the plasma flame flow, and the preheating temperature is controlled to be 150 ℃, so that on one hand, moisture on the surface of the substrate can be removed, and the moisture is prevented from affecting the binding force between the stainless steel substrate and the first coating, and on the other hand, the surface temperature of the stainless steel substrate is prevented from suddenly rising, so that cracks are generated on the surface of the coating, and the hardness, wear resistance and high temperature resistance of the surface of the coating are affected.
Example 7
The plasma spraying technique in step S321 has the following spraying process parameters: the spraying gas is a mixed gas of argon and hydrogen, and the flow rate of the mixed gas is 2.0m3The current is 800A, the powder feeding amount is 60g/min, and the spraying distance is 100 mm.
Example 8
In step S321, the specific process of the laser etching process is as follows:
(1) placing the stainless steel substrate coated with the double coating on a working platform of a laser etching machine and positioning;
(2) adjusting the height of a laser head of a laser etching machine to enable a laser focus to fall on the right upper end of the stainless steel substrate coated with the double coatings;
(3) the working parameters of the laser etching machine are adjusted, laser etching is carried out on the surface of the stainless steel substrate coated with the double coating, wherein the laser power is 3-5W, the laser pulse frequency is 80kHz, the laser etching linear speed is 1000mm/s, a plurality of grooves are formed on the surface of the stainless steel substrate coated with the double coating through the laser etching, the surface area of the second coating is increased, and the heat conduction and heat dissipation performance of the coating is accelerated.
Experimental example 1: research on influence of hollow graphene addition on finished product thermal emissivity
The relevant performance parameters of the stainless steel materials coated with high thermal radiation coatings prepared according to examples 1-8 of the present invention are shown in Table 1:
table 1: results of emissivity test of stainless steel material with high emissivity
The data in table 1 show that when no hollow graphene is added, the emissivity of the stainless steel material sprayed with the metal coating is significantly lower than the emissivity value when the hollow graphene is added, and thus it can be seen that the emissivity of the finished product is improved by adding the hollow graphene, and when the weight ratio of the hollow graphene to the mixture in step S22 is 10:1 and 18:1, the emissivity of the stainless steel material sprayed with the metal coating is lower than the weight ratio of 15:1, which indicates that too much or too little of the hollow graphene is added, and therefore, the optimal ratio of the weight ratio of the mixture to the hollow graphene in step S22 is 15: 1.
Experimental example 2: research on influence of rough treatment on surface of stainless steel material on finished product emissivity
The relevant performance parameters of the stainless steel materials coated with high thermal radiation coatings prepared according to examples 1-8 of the present invention are shown in Table 2:
table 2: results of emissivity test of stainless steel material with high emissivity
The data in table 2 show that when the surface of the stainless steel substrate is roughened, the surface area of the stainless steel substrate can be increased, so that the emissivity of the coating is improved, and when the surface of the stainless steel substrate is not roughened, the emissivity of the finished product is low, so that the finished product cannot be well cooled, and the production requirement cannot be met.
Claims (9)
1. A stainless steel wet hydrogen preparation method for improving the thermal emissivity is characterized by mainly comprising the following steps:
s1: substrate treatment
Carrying out ultrasonic treatment on the surface of a stainless steel substrate by using an acetone solution, cleaning and drying the surface of the stainless steel substrate subjected to ultrasonic treatment by using deionized water, and finally carrying out roughening treatment on the surface of the cleaned substrate;
s2 spray powder preparation
S21: wet hydrogen milling: preparing nickel alloy matrix powder by taking 2.3-3.5g of nickel sulfate hexahydrate, 20-22g of potassium sodium tartrate, 0.15-0.2g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution by utilizing a wet hydrogen thermal reduction technology;
s22: emulsifying and pulping: mixing 65-75% of nickel alloy matrix powder and 4.5-8.2% of TiO according to weight percentage2、3-5％Nb2O5、2-5％Fe2O3、1-3％MnO2Uniformly mixing the powder and the rest of the adhesive to obtain a mixture, adding deionized water which is 0.4-0.5 time of the weight of the mixture into the mixture, and performing ultrasonic dispersion to prepare mixed slurry I;
s23: spray drying: spray-drying the mixed slurry I in a spray-drying tower at the temperature of 180-220 ℃;
s24: spark plasma sintering: placing the spray-dried powder in a discharge plasma sintering furnace for sintering treatment for 2-3h, and finally cooling and opening the furnace along with the furnace to obtain a finished product I of spraying powder;
s3: preparation of the coating
S31 preparation of the first coating:
s311: preparing materials: according to the following steps: 1, adding hollow graphene into the mixture obtained in the step S22, preparing a mixed slurry II according to the subsequent steps of S12, and finally preparing a finished spraying powder II according to the methods of S23 and S24;
s312: coating: fixing the stainless steel substrate on a workbench, and spraying the finished product of the spraying powder II to the surface of the stainless steel substrate by utilizing physical vapor deposition to coat the surface of the stainless steel substrate with a first coating;
s32: preparing a second coating:
s321: plasma spraying: spraying the finished product of the spraying powder to the surface of the stainless steel substrate coated with the first coating by adopting a plasma spraying technology at the temperature of 120-140 ℃ to form the stainless steel substrate with double coatings, and then treating the surface of the second coating by utilizing a laser etching process.
2. The method for preparing stainless steel wet hydrogen for improving the emissivity as claimed in claim 1, wherein the wet hydrogen milling in step S21 comprises: adding water into 2.3-3.5g of nickel sulfate hexahydrate, 20-22g of potassium sodium tartrate, 0.15-0.2g of sodium hydroxide and 4.8mL of 85% hydroxylamine solution to prepare 100mL of mixed solution, heating the mixed solution to 85-95 ℃, finally placing the mixed solution in a high-pressure hydrogen reduction reaction kettle, introducing hydrogen with the pressure of 3-4.5MPa, heating to 150-170 ℃, reacting for 6-8h, collecting and washing sediments in the kettle, filtering, and drying for 2-3h to obtain the nickel alloy matrix powder.
3. The method as claimed in claim 1, wherein the sintering pressure of the spark plasma sintering in step S24 is 50-250MPa, and the sintering temperature is 800-1500 ℃ to obtain the first finished product of the spray powder.
4. The method for producing wet hydrogen for stainless steel with improved emissivity of claim 1, wherein said roughening treatment in step S1 is performed by roughening the surface of stainless steel substrate with suction sand blaster, wherein the sand is brown corundum.
5. The method for preparing stainless steel wet hydrogen for improving emissivity of claim 1, wherein the hollow graphene in step S311 is prepared by the following steps:
(1) placing carbon particles with the particle size of 300-350 mu m into a fluidized bed, and carrying out fluidization treatment on the carbon particles by using a vulcanizing gas, wherein the vulcanizing gas is argon;
(2) putting tetramethylsilane into a constant-temperature heater to heat to form steam, and introducing acetylene into the steam to pyrolyze the steam to form carbon composite powder;
(3) and carrying out vacuum heat treatment on the carbon composite powder to obtain the high-purity vacuum graphene material.
6. The method for preparing stainless steel wet hydrogen for improving emissivity of claim 1, wherein said binder in step S22 is polyanionic cellulose.
7. The method as claimed in claim 1, wherein the preheating temperature is controlled not to exceed 150 ℃ by preheating the stainless steel substrate with plasma flame stream during the physical vapor deposition treatment of the surface of the stainless steel substrate in step S312.
8. The method for preparing stainless steel wet hydrogen for improving the emissivity as claimed in claim 1, wherein the spraying parameters of the plasma spraying technique in the S321 are as follows: the spraying gas is a mixed gas of argon and hydrogen, and the flow rate of the mixed gas is 1.8-2.2m3/h，The current is 700-900A, the powder feeding amount is 50-70g/min, and the spraying distance is 60-150 mm.
9. Use of a wet hydrogen production method for stainless steel with improved emissivity of heat according to any of claims 1 to 8, wherein the stainless steel produced by the wet hydrogen production method is used on the inner surface of the envelope of an X-ray tube.
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