Preparation method of high thermal conductivity super hydrophobic radiation cooling coating on titanium alloy surface

Abstract

The invention discloses a preparation method of a high thermal conductivity super-hydrophobic radiation cooling coating on a titanium alloy surface, the method comprising: one, the metal nanoparticles having thermal conductivity superior to that of the titanium alloy are dispersed in an epoxy resin solution and mixed, then applied to the titanium alloy surface and cured to form a thermal coating; two, polydimethylsiloxane and epoxy resin are added to a solvent and stirred and then polytetrafluoroethylene particles are added, then applied to the thermal coating surface and cured to form a super-hydrophobic radiation cooling coating, and a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating is obtained on the titanium alloy surface. The present invention is by sequentially preparing a metal particle thermal coating and a super-hydrophobic radiation cooling coating having excellent thermal conductivity on the titanium alloy surface, high thermal conductivity, super-hydrophobicity and three functions of radiation cooling are compounded on the same coating, the coating has good environmental tolerance, is better in bonding strength with the titanium alloy, and the preparation process does not rely on special equipment, is easily achieved, and can be mass-produced.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of metal surface composite coatings, and specifically to a method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on a titanium alloy surface. Background Art

[0002] Titanium alloy has a series of excellent characteristics such as low density, high specific strength, good high and low temperature tolerance, good impact resistance, and good corrosion resistance. It is an important structural material in the aerospace field and is mainly used in parts such as aircraft body structure and fuselage. However, the thermal conductivity of titanium alloy itself is low. During high-speed flight, the surface temperature of the aircraft will rise rapidly. At the same time, long-term sunlight exposure will also cause the temperature of the titanium alloy body to rise continuously, which will eventually seriously affect the normal operation of the electronic components inside the aircraft, thereby hindering the normal flight of the aircraft. Therefore, a coating with both high thermal conductivity and radiative cooling properties is prepared on the surface of titanium alloy. On the one hand, the heat on the surface of the titanium alloy is conducted away by the high thermal conductivity coating. On the other hand, the radiative cooling coating uses the high reflectivity in the solar spectrum band (0.25μm~2.5μm) and the high emissivity in the thermal radiation band (2.5μm~25μm) to reflect the radiant heat of the solar energy from the source, preventing the titanium alloy surface from being heated by sunlight. At the same time, the heat of the titanium alloy itself can also be emitted in the form of infrared radiation. Combining the two functions of high thermal conductivity and radiation cooling performance is of great significance for effectively preventing the surface temperature of titanium alloy body structural parts from being too high, avoiding premature aging of titanium alloy components, and extending their service life.

[0003] In actual applications, when an aircraft is washed by rain during use, or when dust pollutants in the air fall onto the surface of the fuselage, it will have a significant impact on the thermal conductivity and radiation cooling performance of the coating surface, thereby shortening the service life of the coating. A super-hydrophobic surface refers to a surface on which a water droplet has a contact angle greater than 150° and is easy to roll. When dust pollutant particles in the air drop onto the coating surface, the surface pollutants can be carried away as the water droplets roll, exhibiting an excellent self-cleaning effect. Giving a super-hydrophobic function to a high thermal conductivity and radiation cooling coating, that is, preparing a coating with super-hydrophobicity, thermal conductivity and radiation cooling performance on the surface of a titanium alloy, is of great significance for effectively preventing the surface temperature of titanium alloy components from being too high during use and ensuring the normal operation of the aircraft.

[0004] To effectively control the temperature of aircraft structures and surfaces, current research focuses on coating titanium alloys with high infrared emissivity. This process dissipates heat from the titanium alloy substrate via infrared radiation, thereby achieving a cooling effect. However, a single high infrared emissivity coating has limited effect on titanium alloy surface temperature control. A coating that combines high thermal conductivity, superhydrophobicity, and radiative cooling properties has yet to be reported. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on a titanium alloy surface in view of the deficiencies in the above-mentioned prior art. The method is carried out by sequentially forming a metal particle thermal conductive coating with excellent thermal conductivity and a multi-stage microporous structure with super-hydrophobic radiation cooling performance on the titanium alloy surface, obtaining a high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface, and combining high thermal conductivity, super-hydrophobicity and radiation cooling properties into the same coating. The coating has good environmental tolerance and good bonding strength with the titanium alloy substrate, thereby solving the problem of poor thermal conductivity and heat dissipation performance of the current titanium alloy during use.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on the surface of a titanium alloy, characterized in that the method comprises the following steps:

[0007] Step 1: Dispersing metal nanoparticles with better thermal conductivity than titanium alloy into an epoxy resin solution, stirring and mixing with a magnetic stirrer to obtain a first dispersion, then coating the first dispersion on the surface of the titanium alloy and pre-curing it to form a thermal conductive coating;

[0008] Step 2: Add polydimethylsiloxane and epoxy resin to the solvent and stir evenly to obtain a blend, then add polytetrafluoroethylene particles and disperse them to obtain a second dispersion, and then apply the second dispersion to the surface of the thermal conductive coating formed in step 1, and perform a curing treatment to form a super-hydrophobic radiation cooling coating, thereby obtaining a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface.

[0009] The above-mentioned method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on the surface of a titanium alloy is characterized in that the metal nanoparticles in step one are copper nanoparticles, silver nanoparticles, gold nanoparticles or aluminum nanoparticles, and the particle size is 10nm to 500nm.

[0010] The above-mentioned method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on the surface of a titanium alloy is characterized in that the solvent in the epoxy resin solution in step one is tetrahydrofuran, the mass concentration of the epoxy resin solution is 0.1% to 1%, and the mass concentration of the metal nanoparticles in the first dispersion is 5% to 10%.

[0011] The above-mentioned method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on the surface of a titanium alloy is characterized in that in step one, the first dispersion is applied to the surface of the titanium alloy by dipping, spraying, dripping or spin coating, the temperature of the pre-curing treatment is 40°C to 80°C, the time is 20min to 80min, and the thickness of the thermal conductive coating is 50μm to 200μm.

[0012] The above-mentioned method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on the surface of a titanium alloy is characterized in that the solvent in step 2 is tetrahydrofuran, the mass concentration of polydimethylsiloxane in the blend is 1% to 3%, the mass concentration of epoxy resin is 0.1% to 1%, the particle size of the polytetrafluoroethylene particles is 50nm to 500nm, and the mass concentration of polytetrafluoroethylene particles in the second dispersion is 1% to 8%.

[0013] The above-mentioned method for preparing a high thermal conductivity super-hydrophobic radiation cooling coating on a titanium alloy surface is characterized in that the second dispersion in step 2 is applied to the surface of the thermal conductive coating formed in step 1 by spraying, and the curing treatment temperature is 80°C to 120°C, and the time is 60min to 150min.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The present invention first uses metal nanoparticles with excellent thermal conductivity to form a thermal conductive coating to improve the thermal conductivity of titanium alloy, and then uses a blend of polytetrafluoroethylene particles / polydimethylsiloxane / epoxy resin to form a super-hydrophobic radiation cooling coating on the thermal conductive coating, providing high reflectivity to sunlight and high emissivity in the thermal radiation band, achieving super-hydrophobic radiation cooling performance, and preparing a high thermal conductivity super-hydrophobic radiation cooling coating on the surface of titanium alloy.

[0016] 2. The super-hydrophobic radiation cooling coating prepared on the thermal conductive coating of the present invention has a multi-level microporous structure, which ensures that the thermal conductive coating at the bottom is not completely covered, taking into account the thermal conductivity efficiency and radiation cooling performance of the titanium alloy surface coating, and effectively solving the current problem of poor thermal conductivity and heat dissipation performance of titanium alloy during use.

[0017] 3. The polytetrafluoroethylene particles, polydimethylsiloxane and epoxy resin in the second dispersion liquid of the present invention for preparing the super hydrophobic radiation cooling coating on the thermal conductive coating have good environmental tolerance and are resistant to ultraviolet radiation, rain and climate change. At the same time, the second dispersion liquid matrix is an epoxy resin system, which has good bonding strength with the titanium alloy substrate, effectively ensuring the actual durability of the high thermal conductivity super hydrophobic radiation cooling coating, and has strong practical value.

[0018] 4. The preparation process of the present invention adopts coating processes commonly used in industry such as dipping, dripping, and spraying. This method is applicable to substrates of any shape, does not rely on special equipment, has a simple preparation process, and has low preparation cost. All operations can be carried out at room temperature, which is mild and can be produced on a large scale.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the high thermal conductivity super hydrophobic radiation cooling coating in the present invention.

[0021] Figure 2 Schematic diagram of the cross-sectional structure of the high thermal conductivity super-hydrophobic radiation cooling coating of the present invention.

[0022] Description of Reference Numerals

[0023] 1—Titanium alloy; 2—Thermal conductive coating; 3—Super hydrophobic radiation cooling coating. DETAILED DESCRIPTION

[0024] like Figure 1 and Figure 2 As shown, the high thermal conductivity super hydrophobic radiation cooling coating of the present invention includes a thermal conductive coating 2 and a super hydrophobic radiation cooling coating 3 sequentially prepared on the surface of a titanium alloy 1.

[0025] Example 1

[0026] This embodiment includes the following steps:

[0027] Step 1: polish the surface of the titanium alloy with 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence until the surface is smooth, and then wash it in an ultrasonic cleaner with anhydrous ethanol and purified water for 12 minutes at an ultrasonic power of 100 W, and then take it out and blow dry it with a hair dryer to obtain the pretreated titanium alloy;

[0028] An epoxy resin prepolymer and a curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3:1, and the mixture is stirred thoroughly with a magnetic stirrer to obtain an epoxy resin solution with a mass concentration of 1%. Copper nanoparticles with a particle size of 50 nm are dispersed in the epoxy resin solution, and the mixture is stirred and mixed thoroughly with a magnetic stirrer to obtain a first dispersion liquid with a mass concentration of 5% copper nanoparticles. The pretreated titanium alloy is then placed in the first dispersion liquid and allowed to stand at room temperature for 30 minutes for full immersion. The alloy is then placed in an environment of 40° C. for precuring for 80 minutes, thereby forming a copper nanoparticle / epoxy resin thermal conductive coating with a thickness of 50 μm to 200 μm on the surface of the titanium alloy. The thermal conductive coating is in a semi-cured state, which is conducive to the adhesion of subsequent coatings.

[0029] Step 2, epoxy resin prepolymer and polyimide resin are added to tetrahydrofuran in a mass ratio of 3: 1, polydimethylsiloxane prepolymer and curing agent vinyl resin are added to tetrahydrofuran in a mass ratio of 10: 1, and the mixture is fully stirred by a magnetic stirrer to obtain a blend, wherein the mass concentration of polydimethylsiloxane in the blend is 1%, and the mass concentration of epoxy resin is 0.1%, and then polytetrafluoroethylene particles having a particle size of 100 nm are added and dispersed to obtain a second dispersion having a mass concentration of 1% of polytetrafluoroethylene particles, and the second dispersion is then loaded into a spray gun, and the distance between the spray gun nozzle and the surface of the thermal conductive coating is controlled to be 20 cm, and the second dispersion is sprayed onto the surface of the thermal conductive coating layer by layer, and cured. The curing temperature is 80 ° C, and the time is 150 min to form a super-hydrophobic radiation cooling coating, thereby obtaining a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface.

[0030] The particle size of the copper nanoparticles used in step 1 of this embodiment can also be 500 nm, and the copper nanoparticles can also be replaced by gold nanoparticles or aluminum nanoparticles. The coating method of the first dispersion can also be spin coating; the particle size of the polytetrafluoroethylene particles used in step 2 can also be 50 nm, 200 nm or 500 nm.

[0031] Example 2

[0032] This embodiment includes the following steps:

[0033] Step 1: polish the surface of the titanium alloy with 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence until the surface is smooth, and then wash it in an ultrasonic cleaner with anhydrous ethanol and purified water for 12 minutes at an ultrasonic power of 100 W, and then take it out and blow dry it with a hair dryer to obtain the pretreated titanium alloy;

[0034] An epoxy resin prepolymer and a curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3:1, and the mixture is stirred thoroughly with a magnetic stirrer to obtain an epoxy resin solution with a mass concentration of 0.1%. Copper nanoparticles with a particle size of 50 nm are then dispersed into the epoxy resin solution, and the mixture is stirred and mixed thoroughly with a magnetic stirrer to obtain a first dispersion liquid with a mass concentration of 10% copper nanoparticles. The pretreated titanium alloy is then placed in the first dispersion liquid and allowed to stand at room temperature for 30 minutes for full immersion, and then placed in an environment of 80°C for precuring for 20 minutes to form a copper nanoparticle / epoxy resin thermal conductive coating with a thickness of 50 μm to 200 μm on the surface of the titanium alloy, wherein the thermal conductive coating is in a semi-cured state, which is conducive to the adhesion of subsequent coatings.

[0035] Step 2, epoxy resin prepolymer and curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3: 1, polydimethylsiloxane prepolymer and curing agent vinyl resin are added to tetrahydrofuran in a mass ratio of 10: 1, and the mixture is fully stirred by a magnetic stirrer to obtain a blend, wherein the mass concentration of polydimethylsiloxane in the blend is 3%, the mass concentration of epoxy resin is 1%, and polytetrafluoroethylene particles having a particle size of 100 nm are subsequently added and dispersed to obtain a second dispersion having a mass concentration of 8% of polytetrafluoroethylene particles, and the second dispersion is then loaded into a spray gun, and the distance between the spray gun nozzle and the surface of the thermally conductive coating is controlled to be 20 cm, and the second dispersion is sprayed onto the surface of the thermally conductive coating layer by layer, and cured. The curing temperature is 120 ° C, and the time is 60 min to form a super-hydrophobic radiation cooling coating, thereby obtaining a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface.

[0036] The particle size of the copper nanoparticles used in step 1 of this embodiment can also be 500 nm, and the copper nanoparticles can also be replaced by gold nanoparticles or aluminum nanoparticles. The coating method of the first dispersion can also be spin coating; the particle size of the polytetrafluoroethylene particles used in step 2 can also be 50 nm, 200 nm or 500 nm.

[0037] Example 3

[0038] This embodiment includes the following steps:

[0039] Step 1: polish the surface of the titanium alloy with 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence until the surface is smooth, and then wash it in an ultrasonic cleaner with anhydrous ethanol and purified water for 12 minutes at an ultrasonic power of 100 W, and then take it out and blow dry it with a hair dryer to obtain the pretreated titanium alloy;

[0040] An epoxy resin prepolymer and a curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3:1, and the mixture is stirred thoroughly with a magnetic stirrer to obtain an epoxy resin solution with a mass concentration of 1%. Silver nanoparticles with a particle size of 20 nm are then dispersed into the epoxy resin solution, and the mixture is stirred and mixed uniformly with a magnetic stirrer to obtain a first dispersion liquid with a mass concentration of 5% silver nanoparticles. The first dispersion liquid is then loaded into a spray gun, and the distance between the spray gun nozzle and the titanium alloy surface is controlled to be 20 cm. The first dispersion liquid is sprayed onto the titanium alloy surface layer by layer, and the titanium alloy surface is further placed in an environment of 50° C. for pre-curing treatment for 30 minutes, thereby forming a silver nanoparticle / epoxy resin thermal conductive coating with a thickness of 50 μm to 200 μm on the titanium alloy surface. The thermal conductive coating is in a semi-cured state, which is conducive to the adhesion of subsequent coatings.

[0041] Step 2, epoxy resin prepolymer and curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3: 1, polydimethylsiloxane prepolymer and curing agent vinyl resin are added to tetrahydrofuran in a mass ratio of 10: 1, and the mixture is fully stirred by a magnetic stirrer to obtain a blend, wherein the mass concentration of polydimethylsiloxane in the blend is 2%, and the mass concentration of epoxy resin is 0.5%, and then polytetrafluoroethylene particles having a particle size of 100 nm are added and dispersed to obtain a second dispersion having a mass concentration of 5% of polytetrafluoroethylene particles, and the second dispersion is then loaded into a spray gun, and the distance between the spray gun nozzle and the surface of the thermal conductive coating is controlled to be 20 cm, and the second dispersion is sprayed onto the surface of the thermal conductive coating layer by layer, and cured. The curing temperature is 100 ° C, and the time is 120 min to form a super-hydrophobic radiation cooling coating, thereby obtaining a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface.

[0042] The particle size of the silver nanoparticles used in step 1 of this embodiment may also be 50 nm, 100 nm or 500 nm, and the particle size of the polytetrafluoroethylene particles used in step 2 may also be 50 nm, 200 nm or 500 nm.

[0043] Example 4

[0044] This embodiment includes the following steps:

[0045] Step 1: polish the surface of the titanium alloy with 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence until the surface is smooth, and then wash it in an ultrasonic cleaner with anhydrous ethanol and purified water for 12 minutes at an ultrasonic power of 100 W, and then take it out and blow dry it with a hair dryer to obtain the pretreated titanium alloy;

[0046] An epoxy resin prepolymer and a curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3:1, and the mixture is stirred thoroughly with a magnetic stirrer to obtain an epoxy resin solution with a mass concentration of 1%. Silver nanoparticles with a particle size of 20 nm are dispersed in the epoxy resin solution, and the mixture is stirred and mixed uniformly with a magnetic stirrer to obtain a first dispersion liquid with a mass concentration of 8% of the silver nanoparticles. The pretreated titanium alloy is placed in an environment of 50° C., and the first dispersion liquid is dripped onto the surface of the titanium alloy with a dropper. After the surface solvent evaporates, the first dispersion liquid is dripped again, and the dripping is repeated 3 to 5 times. The alloy is then placed in an environment of 50° C. for pre-curing treatment for 30 minutes, thereby forming a silver nanoparticle / epoxy resin thermal conductive coating with a thickness of 50 μm to 200 μm on the surface of the titanium alloy. The thermal conductive coating is in a semi-cured state, which is conducive to the adhesion of subsequent coatings.

[0047] Step 2, the epoxy resin prepolymer and the curing agent polyimide resin are added to tetrahydrofuran in a mass ratio of 3: 1, and the polydimethylsiloxane prepolymer and the curing agent vinyl resin are added to tetrahydrofuran in a mass ratio of 10: 1, and the mixture is fully stirred by a magnetic stirrer to obtain a blend, wherein the mass concentration of polydimethylsiloxane in the blend is 2%, and the mass concentration of the epoxy resin is 0.5%, and then polytetrafluoroethylene particles having a particle size of 100 nm are added and dispersed to obtain a second dispersion having a mass concentration of 8% of polytetrafluoroethylene particles, and the second dispersion is then loaded into a spray gun, and the distance between the spray gun nozzle and the surface of the thermal conductive coating is controlled to be 20 cm, and the second dispersion is sprayed onto the surface of the thermal conductive coating layer by layer, and cured. The curing temperature is 120 ° C, and the time is 120 min to form a super-hydrophobic radiation cooling coating, thereby obtaining a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface.

[0048] The particle size of the silver nanoparticles used in step 1 of this embodiment may also be 50 nm, 100 nm or 500 nm, and the particle size of the polytetrafluoroethylene particles used in step 2 may also be 50 nm, 200 nm or 500 nm.

[0049] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a high thermal conductivity super hydrophobic radiation cooling coating on a titanium alloy surface, characterized in that: The method comprises the following steps: Step 1: Dispersing metal nanoparticles with better thermal conductivity than titanium alloy into an epoxy resin solution, stirring and mixing with a magnetic stirrer to obtain a first dispersion, then coating the first dispersion on the surface of the titanium alloy and pre-curing it to form a thermal conductive coating; Step 2: Add polydimethylsiloxane and epoxy resin to the solvent and stir evenly to obtain a blend, then add polytetrafluoroethylene particles and disperse them to obtain a second dispersion, and then apply the second dispersion to the surface of the thermal conductive coating formed in step 1, and perform a curing treatment to form a super-hydrophobic radiation cooling coating, thereby obtaining a micro-nano composite high thermal conductivity super-hydrophobic radiation cooling coating on the titanium alloy surface.

2. The method for preparing a high thermal conductivity super hydrophobic radiation cooling coating on a titanium alloy surface according to claim 1, wherein: The metal nanoparticles in step 1 are copper nanoparticles, silver nanoparticles, gold nanoparticles or aluminum nanoparticles, and have a particle size of 10 nm to 500 nm.

3. The method for preparing a high thermal conductivity super hydrophobic radiation cooling coating on a titanium alloy surface according to claim 1, wherein: The solvent in the epoxy resin solution in step 1 is tetrahydrofuran, the mass concentration of the epoxy resin solution is 0.1% to 1%, and the mass concentration of the metal nanoparticles in the first dispersion is 5% to 10%.

4. The method for preparing a high thermal conductivity super hydrophobic radiation cooling coating on a titanium alloy surface according to claim 1, wherein: In step one, the first dispersion is applied to the titanium alloy surface by dipping, spraying, dripping or spin coating. The pre-curing treatment temperature is 40°C to 80°C, the time is 20min to 80min, and the thickness of the thermal conductive coating is 50μm to 200μm.

5. The method for preparing a high thermal conductivity super hydrophobic radiation cooling coating on a titanium alloy surface according to claim 1, wherein: The solvent in step 2 is tetrahydrofuran, the mass concentration of polydimethylsiloxane in the blend is 1% to 3%, the mass concentration of epoxy resin is 0.1% to 1%, the particle size of the polytetrafluoroethylene particles is 50nm to 500nm, and the mass concentration of the polytetrafluoroethylene particles in the second dispersion is 1% to 8%.

6. The method for preparing a high thermal conductivity super hydrophobic radiation cooling coating on a titanium alloy surface according to claim 1, wherein: In step 2, the second dispersion is applied to the surface of the thermal conductive coating formed in step 1 by spraying. The curing temperature is 80° C. to 120° C., and the curing time is 60 min to 150 min.

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