Carbon nanotube coating aging protection process
By combining gradient interface modification, a dual-structure inorganic protective layer, and a temperature-sensitive organic protective layer, the aging and failure problem of carbon nanotube coatings was solved, the interfacial bonding strength and resistance to multiple aging processes were improved, and the equipment life was extended.
Patent Information
- Application Number
- CN202511750291.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-01-16
AI Technical Summary
Carbon nanotube coatings face aging and failure issues in practical applications. They have weak interfacial adhesion and are easy to peel off. Traditional protective processes cannot resist the erosion of multiple aging factors at the same time, and existing processes lack systematic optimization, leading to water and oxygen penetration and performance degradation.
A combined process of gradient interface modification pretreatment, dual-structure inorganic protective layer and temperature-sensitive organic protective layer was adopted. A hydroxyl-fluorine gradient distribution was constructed by plasma composite treatment to form an interface-enhanced transition layer. A dense SiO2 underlayer and doped nano-boehmite zirconia sol were prepared by magnetron sputtering. Subsequent UV-thermal synergistic treatment promoted the formation of Si-OC covalent bonds at the inorganic-organic interface.
It significantly improves the bonding strength between the coating and the substrate and between layers, effectively resists water and oxygen erosion and ultraviolet radiation, controls the coating weight loss rate to within 2%, achieves salt spray resistance of more than 500 hours, maintains stable thermal conductivity and spectral absorption performance, and extends the service life of equipment.
Abstract
Description
Technical Field
[0001] This invention relates to the field of material protection technology, and in particular to an aging protection process for carbon nanotube coatings. Background Technology
[0002] Carbon nanotubes, with their excellent thermal and electrical conductivity, high specific surface area, and outstanding spectral absorption characteristics, have shown broad application prospects in energy conversion devices such as solar collectors. As a coating material, they can significantly improve the energy conversion efficiency of such devices. However, carbon nanotube coatings face significant aging failure issues in practical applications, severely limiting their large-scale promotion.
[0003] Carbon nanotubes have a strong chemical inertness on their surface, resulting in weak interfacial bonding with the substrate and subsequent protective layers. This makes them prone to peeling and cracking during service. In traditional protective processes, inorganic coatings can block water and oxygen penetration to some extent, but they are brittle and have poor impact resistance. Organic coatings, on the other hand, have limited UV resistance and are prone to degradation and powdering after long-term use, making it difficult to resist the erosion of multiple aging factors simultaneously.
[0004] Furthermore, existing processes lack systematic optimization of the interfacial bonding state, making it easy for micro-defects and gaps to form between layers. Corrosive media such as water and oxygen can easily penetrate into the carbon nanotube coating through these channels, accelerating its oxidative decomposition. This leads to a significant decrease in the coating's heat absorption efficiency and thermal conductivity, thereby shortening the service life of related equipment. Current aging protection technologies mostly focus on improving single protective functions, failing to build a complete system that considers both interfacial bonding strength and comprehensive protective performance, and thus cannot fundamentally solve the aging failure problem of carbon nanotube coatings. Summary of the Invention
[0005] The purpose of this invention is to provide a carbon nanotube coating aging protection process to solve the above-mentioned problems.
[0006] This invention provides a carbon nanotube coating aging protection process, comprising the following steps: S1. Gradient Interface Modification Pretreatment: The substrate with carbon nanotube coating is subjected to plasma composite treatment. The working gas is a mixture of argon, oxygen and carbon tetrafluoride in a volume ratio of 4:2:1. The power is controlled in stages to construct a hydroxyl-fluorine gradient distribution on the surface of carbon nanotubes. Then, the coating is immersed in an ethanol-water mixture containing amino carbon quantum dots and γ-aminopropyltriethoxysilane. After ultrasonic vibration, it is dried under nitrogen protection to form an interface-enhanced transition layer. S2. Preparation of dual-structure inorganic protective layer: SiO2 dense bottom layer is deposited on the surface of transition layer by magnetron sputtering, and then zirconium oxide sol doped with nano-boehmite is coated on the surface of dense bottom layer. After drying by blowing and infrared-assisted curing, a porous-dense composite inorganic layer is formed. S3. Construction of temperature-sensitive organic protective layer: A composite organic coating with polyvinyl fluoride-acrylate copolymer as the matrix and added phase change microcapsules and UV stabilizers is prepared. After coating by dip coating-infrared leveling composite process, an organic protective layer is formed by infrared leveling and gradient curing. S4. Interface-synergistic strengthening post-treatment: The composite coating is subjected to UV-thermal synergistic treatment in a vacuum environment, during which surface pressure is applied to promote the formation of Si-OC covalent bonds at the inorganic-organic interface, resulting in an aging-protective modified carbon nanotube coating.
[0007] Preferably, in step S1, the power of the plasma recombination treatment is 80W, 120W and 160W in stages, and each stage is maintained for 6-10 minutes, with a treatment temperature of 30-40℃.
[0008] Preferably, in step S1, the amount of aminated carbon quantum dots added is 1-2 wt% of the modified liquid and the particle size is 5-10 nm; the amount of γ-aminopropyltriethoxysilane added is 2-4 wt% of the modified liquid; the volume ratio of ethanol to water is 4:1; the ultrasonic vibration temperature is 35-45℃, the time is 30-50 min, and the power is 300 W; the drying temperature is 70-80℃ and the time is 1.5-2.5 h.
[0009] Preferably, in step S2, the magnetron sputtering power is 180-220W, the argon atmosphere pressure is 0.5Pa, the deposition temperature is 100-120℃, and the thickness of the SiO2 dense underlayer is 30-50nm.
[0010] Preferably, in step S2, the nano-boehmite is AlOOH and the amount added is 8-12% of the solid content of the zirconia sol; the solid content of the zirconia sol is 10-15 wt%.
[0011] Preferably, in step S2, the temperature of the forced-air drying is 60℃ and the time is 1h; the wavelength of the infrared-assisted curing is 3-5μm, the power is 200-300W, the temperature is 130-150℃, and the time is 40-60min; the thickness of the porous-dense composite inorganic layer is 150-250nm.
[0012] Preferably, in step S3, the solid content of the polyvinyl fluoride-acrylate copolymer is 30-40 wt%; the amount of phase change microcapsules added is 10-15 wt% of the matrix, the core material is a dodecanol-tetradecyl alcohol complex, the wall material is polymethyl methacrylate, and the particle size is 1-3 μm; the amount of UV stabilizer added is 8-12 wt% of the matrix, and it is composed of nano-TiO2. SiO2 core-shell particles are compounded with UV-531 at a mass ratio of 2:1.
[0013] Preferably, in step S3, the dipping rate is 5-8 cm. The infrared leveling wavelength is 2-4 μm, the power is 150 W, and the time is 3-5 min; the gradient curing is carried out at 70℃ for 1.5 h, at 90℃ for 2 h, and at 110℃ for 1 h; the thickness of the organic protective layer is 250-400 nm.
[0014] Preferably, in step S4, the vacuum level of the vacuum environment is 5-10 Pa; the ultraviolet wavelength of the ultraviolet-thermal synergistic treatment is 254 nm, and the power is 80-120 mW. cm 2 The heating temperature is 120-140℃, the holding time is 40-60min, and the applied surface pressure is 0.05-0.1MPa.
[0015] Preferably, the carbon nanotube coating is a multi-walled carbon nanotube with a diameter of 20-50 nm and a length of 5-20 μm, prepared by electrophoretic deposition with a coating thickness of 2-6 μm, and the substrate is aluminum alloy, quartz or polyimide.
[0016] Therefore, this invention employs the aforementioned carbon nanotube coating aging protection process. Through a specific ratio of argon, oxygen, and carbon tetrafluoride plasma composite treatment, a hydroxyl-fluorine gradient distribution is formed on the surface of the carbon nanotubes. Then, through the synergistic modification of aminated carbon quantum dots and γ-aminopropyltriethoxysilane, a highly efficient interface-enhanced transition layer is constructed. Subsequent UV-thermal synergistic treatment further promotes the formation of stable Si-OC covalent bonds at the inorganic-organic interface, significantly improving the bonding strength between the coating and the substrate and between layers. After long-term aging tests, the coating tensile strength retention rate can still reach more than 85%, effectively avoiding peeling problems caused by insufficient bonding strength during service. The dual-structure inorganic protective layer provides excellent water and oxygen shielding. The dense SiO2 underlayer prepared by magnetron sputtering blocks the direct penetration of water and oxygen, while the zirconium oxide sol coating doped with nano-boehmite further enhances the shielding performance through a layered barrier effect. In the temperature-sensitive organic protective layer, phase change microcapsules effectively mitigate the effects of temperature fluctuations, and the compounded UV absorber efficiently absorbs ultraviolet light. Through their synergistic effect, the coating can simultaneously resist multiple aging factors such as water and oxygen corrosion and ultraviolet radiation. After long-term aging tests, the coating's weight loss rate is controlled within 2%, and its salt spray resistance reaches over 500 hours without corrosion. Simultaneously, this process enhances protective performance without compromising the excellent thermal conductivity and endothermic properties of carbon nanotubes, and the multi-layered protective structure does not adversely affect the coating's spectral absorption performance, ensuring the stable preservation of the coating's core functions and effectively suppressing the decline in energy conversion efficiency during service. In addition, the plasma treatment, magnetron sputtering, dip coating and other technologies used in the process are all mature material preparation methods. The parameters are set reasonably and are easy to control on a large scale. They can be adapted to a variety of commonly used substrates, and the coating thickness is controllable. They have good process adaptability and practical application value, and can significantly extend the service life of related equipment.
[0017] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation
[0018] To better understand the above technical solutions, a detailed description of the specific implementation methods will be provided below. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0019] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.
[0020] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.
[0021] This invention provides a carbon nanotube coating aging protection process, comprising the following steps: S1. Gradient Interface Modification Pretreatment: The substrate with carbon nanotube coating is subjected to plasma composite treatment. The working gas is a mixture of argon, oxygen and carbon tetrafluoride in a volume ratio of 4:2:1. The power is controlled in stages to construct a hydroxyl-fluorine gradient distribution on the surface of carbon nanotubes. Then, the coating is immersed in an ethanol-water mixture containing amino carbon quantum dots and γ-aminopropyltriethoxysilane. After ultrasonic vibration, it is dried under nitrogen protection to form an interface-enhanced transition layer. S2. Preparation of dual-structure inorganic protective layer: SiO2 dense bottom layer is deposited on the surface of transition layer by magnetron sputtering, and then zirconium oxide sol doped with nano-boehmite is coated on the surface of dense bottom layer. After drying by blowing and infrared-assisted curing, a porous-dense composite inorganic layer is formed. S3. Construction of temperature-sensitive organic protective layer: A composite organic coating with polyvinyl fluoride-acrylate copolymer as the matrix and added phase change microcapsules and UV stabilizers is prepared. After coating by dip coating-infrared leveling composite process, an organic protective layer is formed by infrared leveling and gradient curing. S4. Interface-synergistic strengthening post-treatment: The composite coating is subjected to UV-thermal synergistic treatment in a vacuum environment, during which surface pressure is applied to promote the formation of Si-OC covalent bonds at the inorganic-organic interface, resulting in an aging-protective modified carbon nanotube coating.
[0022] To further optimize the above technical solution, in step S1, the power of plasma recombination treatment is 80W, 120W and 160W in stages, and each stage is maintained for 6-10 minutes, with a treatment temperature of 30-40℃.
[0023] To further optimize the above technical solution, in step S1, the amount of aminated carbon quantum dots added is 1-2 wt% of the modified liquid and the particle size is 5-10 nm; the amount of γ-aminopropyltriethoxysilane added is 2-4 wt% of the modified liquid; the volume ratio of ethanol to water is 4:1; the ultrasonic vibration temperature is 35-45℃, the time is 30-50 min, and the power is 300 W; the drying temperature is 70-80℃ and the time is 1.5-2.5 h.
[0024] To further optimize the above technical solution, in step S2, the magnetron sputtering power is 180-220W, the pressure of the argon atmosphere is 0.5Pa, the deposition temperature is 100-120℃, and the thickness of the SiO2 dense underlayer is 30-50nm.
[0025] To further optimize the above technical solution, in step S2, the nano boehmite is AlOOH and the amount added is 8-12% of the solid content of the zirconia sol; the solid content of the zirconia sol is 10-15 wt%.
[0026] To further optimize the above technical solution, in step S2, the temperature of the forced-air drying is 60℃ and the time is 1h; the wavelength of the infrared-assisted curing is 3-5μm, the power is 200-300W, the temperature is 130-150℃, and the time is 40-60min; the thickness of the porous-dense composite inorganic layer is 150-250nm.
[0027] To further optimize the above technical solution, in step S3, the solid content of the polyvinyl fluoride-acrylate copolymer is 30-40 wt%; the amount of phase change microcapsules added is 10-15 wt% of the matrix, with the core material being a dodecanol-tetradecyl alcohol complex, the wall material being polymethyl methacrylate, and the particle size being 1-3 μm; the amount of UV stabilizer added is 8-12 wt% of the matrix, and it is composed of nano-TiO2. SiO2 core-shell particles are compounded with UV-531 at a mass ratio of 2:1.
[0028] To further optimize the above technical solution, in step S3, the dipping rate is 5-8 cm. The infrared leveling wavelength is 2-4 μm, the power is 150 W, and the time is 3-5 min; the gradient curing is carried out at 70℃ for 1.5 h, at 90℃ for 2 h, and at 110℃ for 1 h; the thickness of the organic protective layer is 250-400 nm.
[0029] To further optimize the above technical solution, in step S4, the vacuum level of the vacuum environment is 5-10 Pa; the ultraviolet wavelength of the ultraviolet-thermal synergistic treatment is 254 nm, and the power is 80-120 mW. cm 2 The heating temperature is 120-140℃, the holding time is 40-60min, and the applied surface pressure is 0.05-0.1MPa.
[0030] To further optimize the above technical solution, the carbon nanotube coating is a multi-walled carbon nanotube with a diameter of 20-50 nm and a length of 5-20 μm. It is prepared by electrophoretic deposition and has a coating thickness of 2-6 μm. The substrate is aluminum alloy, quartz or polyimide.
[0031] To provide a clearer and more detailed description of the carbon nanotube coating aging protection process provided in the embodiments of the present invention, the following description will be based on specific embodiments.
[0032] Example 1 The substrate used in this embodiment is an aluminum alloy with dimensions of 50mm × 50mm × 2mm. After removing the oxide scale by polishing the substrate surface with 1000-grit sandpaper, it is ultrasonically cleaned in acetone solution for 20 minutes, then dried in an 80℃ forced-air drying oven for later use. The carbon nanotube coating consists of multi-walled carbon nanotubes with a diameter of 30nm and a length of 10μm, prepared on the surface of the aluminum alloy substrate by electrophoretic deposition, with a coating thickness controlled to 4μm. The raw materials used include 8nm amino-coated carbon quantum dots, γ-aminopropyltriethoxysilane, 99.9% pure argon, oxygen, carbon tetrafluoride gas, 99.9% pure SiO2 target material, AlOOH-type nano-boehmite, 12wt% solid content zirconium oxide sol, 35wt% solid content polyvinyl fluoride-acrylate copolymer, a core material of dodecanol-tetradecyl alcohol complex, a wall material of polymethyl methacrylate with a particle size of 2μm, and nano-TiO2. The equipment used for SiO2 core-shell particles and UV-531 anti-ultraviolet agent includes a plasma treatment instrument, a 300W ultrasonic cleaner, a nitrogen-protected oven, a magnetron sputtering device, a forced-air drying oven, an infrared curing device with a wavelength of 3-5μm, a hot air circulating oven, and a vacuum ultraviolet-thermal synergistic treatment device.
[0033] The process is as follows: S1, Gradient Interface Modification Pretreatment Stage: The aluminum alloy substrate with carbon nanotube coating is placed in a plasma treatment instrument. After closing the equipment door, a mixed gas of argon, oxygen, and carbon tetrafluoride is introduced, with a volume ratio of 4:2:1. The substrate bias voltage is adjusted to -100V, and the total gas flow rate is controlled at 40 sccm. The plasma treatment power is adjusted in stages to 80W, 120W, and 160W, with each power stage maintained for 8 minutes. The temperature inside the equipment is maintained at 35℃ during the treatment. After plasma treatment, a modification solution is prepared. The modified solution contains 1.5wt% aminocarbon quantum dots and 3wt% γ-aminopropyltriethoxysilane. The solvent is a mixture of ethanol and water with a volume ratio of 4:1. The plasma-treated coating is immersed in this modification solution and ultrasonically vibrated at 300W for 40 minutes at 40℃. After removal, it is placed in a nitrogen-protected oven and dried at 75℃ for 2 hours to form an interface-enhanced transition layer.
[0034] S2. In the preparation stage of the dual-structure inorganic protective layer, a dense SiO2 underlayer was deposited on the surface of the transition layer using magnetron sputtering. The sputtering power was set to 200W, the argon atmosphere pressure to 0.5Pa, the deposition temperature to 110℃, the target-substrate distance to 9cm, and the deposition rate to 1.5nm. min, until a dense underlayer with a thickness of 40nm is formed. Then, nano-boehmite is added to the zirconia sol at an amount of 10% of the solid content of the zirconia sol. After stirring evenly, it is coated on the surface of the SiO2 dense underlayer. After coating, it is first dried in a 60℃ forced-air drying oven for 1 hour, and then placed in an infrared curing device for infrared-assisted curing. The curing wavelength is 4μm, the power is 250W, the curing temperature is 140℃, and the curing time is 50min, finally forming a porous-dense composite inorganic layer with a thickness of 200nm.
[0035] S3. In the construction stage of the temperature-sensitive organic protective layer, a composite organic coating is first prepared, using polyvinyl fluoride-acrylate copolymer as the matrix, into which 12wt% phase change microcapsules and 10wt% UV stabilizer are added. The UV stabilizer is composed of nano-TiO2. SiO2 core-shell particles and UV-531 were mixed at a mass ratio of 2:1, and after being stirred and dispersed evenly, they were coated onto the surface of the composite inorganic layer using a dip-coating-infrared leveling composite process at a dip-coating rate of 6 cm. After being removed, it undergoes infrared leveling treatment with a leveling wavelength of 3μm, a power of 150W, and a leveling time of 4min. Then, it is placed in a hot air circulating oven for gradient curing, and is kept at 70℃ for 1.5h, 90℃ for 2h, and 110℃ for 1h in sequence to form an organic protective layer with a thickness of 300nm.
[0036] S4. In the post-treatment stage of interface synergistic enhancement, the substrate with the composite coating is placed in a vacuum ultraviolet-thermal synergistic treatment device, and the vacuum is evacuated to a vacuum degree of 8 Pa. The ultraviolet irradiation and heating devices are turned on, with an ultraviolet wavelength of 254 nm and an irradiation power of 100 mW. cm 2 Simultaneously heat to 130℃ and hold for 50 minutes, during which a surface pressure of 0.08 MPa is applied, with a heating rate of 4℃. The cooling rate is controlled at 1℃. min promotes the formation of Si-OC covalent bonds at the inorganic-organic interface, ultimately yielding an aging-protective modified carbon nanotube coating.
[0037] The coating was subjected to performance testing, with xenon lamp aging test conditions of 0.51W irradiance. m 2 At 340 nm and a blackboard temperature of 65 °C, after 1000 hours of testing, the coating showed a weight loss rate of 1.5% and a tensile strength retention rate of 88%. The salt spray test was conducted using a 5% NaCl solution at 35 °C for 550 hours, after which no rust was observed on the coating surface. The thermal conductivity and spectral absorption properties of the coating showed no significant attenuation compared to the unprotected carbon nanotube coating, maintaining its excellent core functional characteristics.
[0038] Example 2 The substrate used in this embodiment is a quartz substrate with dimensions of 40mm × 40mm × 1.5mm. The substrate was ultrasonically cleaned with anhydrous ethanol for 15 minutes and then dried in an oven at 100℃ for later use. The carbon nanotube coating is a multi-walled carbon nanotube with a diameter of 25nm and a length of 8μm, prepared by electrophoretic deposition, with a coating thickness of 3μm. The raw materials used include 6nm amino-coated carbon quantum dots, γ-aminopropyltriethoxysilane, 99.9% pure argon, oxygen, carbon tetrafluoride gas, 99.9% pure SiO2 target material, AlOOH-type nano-boehmite, 10wt% solid content zirconium oxide sol, 30wt% solid content polyvinyl fluoride-acrylate copolymer, a core material of dodecanol-tetradecyl alcohol complex, a wall material of polymethyl methacrylate with a particle size of 1.5μm, and nano-TiO2. The SiO2 core-shell particles and UV-531 UV stabilizer were used, and the equipment used was the same as in Example 1.
[0039] The process is as follows: S1, Gradient interface modification pretreatment stage: Argon, oxygen, and carbon tetrafluoride mixed gas (volume ratio 4:2:1) are introduced into the plasma processor. The substrate bias voltage is -80V, the total gas flow rate is 35sccm, and the power is adjusted in stages to 80W, 120W, and 160W, each stage lasting 6 minutes, with a treatment temperature of 30℃. The amount of aminated carbon quantum dots added to the modification solution is 1wt%, the amount of γ-aminopropyltriethoxysilane added is 2wt%, and the volume ratio of ethanol to water is 4:1. After immersing the coating in the modification solution, it is ultrasonically vibrated at 300W power for 30 minutes at 35℃. After removal, it is dried at 70℃ for 1.5 hours under nitrogen protection to form an interface-enhanced transition layer.
[0040] S2. In the preparation stage of the dual-structure inorganic protective layer, during the magnetron sputtering deposition of the dense SiO2 underlayer, the sputtering power was 180W, the argon atmosphere pressure was 0.5Pa, the deposition temperature was 100℃, the target-substrate distance was 8cm, and the deposition rate was 1nm. The bottom layer thickness is 30nm. The amount of nano-boehmite added is 8% of the solid content of zirconium oxide sol. After coating, it is dried at 60℃ for 1h and then cured with infrared assisted curing (wavelength 3μm, power 200W, temperature 130℃, time 40min) to form a porous-dense composite inorganic layer with a thickness of 150nm.
[0041] S3, the construction stage of the temperature-sensitive organic protective layer, the amount of phase change microcapsules added to the composite organic coating is 10wt%, and the amount of UV stabilizer added is 8wt% (nano TiO2). The SiO2 core-shell particles to UV-531 were coated using a 2:1 mass ratio. A dip-coating-infrared leveling composite process was employed, with a dip-coating rate of 5 cm / min, an infrared leveling wavelength of 2.5 μm, a power of 150 W, and a time of 3 min. Gradient curing was then performed at 70℃. 1.5h, 90℃ 2 hours, 110℃ An organic protective layer with a thickness of 250 nm is formed in 1 hour.
[0042] S4. Post-processing stage for interface co-enhancement: vacuum degree 5 Pa, ultraviolet wavelength 254 nm, power 80 mW. cm 2 Simultaneously heat to 120℃, hold for 40 minutes, apply a surface pressure of 0.05MPa, and increase the temperature at a rate of 3℃. min, cooling rate 1℃ min promotes the formation of Si-OC covalent bonds at the inorganic-organic interface.
[0043] Performance test results show that after 1000 hours of xenon lamp aging test, the coating weight loss rate is 1.2% and the tensile strength retention rate is 90%; after 580 hours of salt spray test, there is no corrosion; the spectral absorption performance of the coating is suitable for the application scenarios of quartz substrate, and the core functions are stable.
[0044] Example 3 The substrate used in this embodiment is a 50mm × 50mm × 2mm polyimide substrate. After ultrasonic cleaning with acetone for 20 minutes, the substrate was dried at 80℃ for later use. The carbon nanotube coating is a multi-walled carbon nanotube with a diameter of 40nm and a length of 15μm, prepared by electrophoretic deposition, with a coating thickness of 5μm. The raw materials used include 9nm amino-coated carbon quantum dots, γ-aminopropyltriethoxysilane, 99.9% pure argon, oxygen, carbon tetrafluoride gas, 99.9% pure SiO2 target material, AlOOH-type nano-boehmite, 15wt% solids zirconium oxide sol, 40wt% solids polyvinyl fluoride-acrylate copolymer, a core material of dodecanol-tetradecyl alcohol complex, a 2.5μm polymethyl methacrylate phase change microcapsules as the wall material, and nano-TiO2. The equipment used for SiO2 core-shell particles and UV-531 UV stabilizer is the same as that used in Example 1.
[0045] The process is as follows: S1, Gradient interface modification pretreatment stage: During plasma treatment, the substrate bias voltage is -120V, the total gas flow rate is 45sccm, and the power is adjusted in stages to 80W, 120W, and 160W, with each stage lasting 10 minutes. The treatment temperature is 40℃. The amount of aminated carbon quantum dots added to the modification solution is 2wt%, the amount of γ-aminopropyltriethoxysilane added is 4wt%, the volume ratio of ethanol to water is 4:1, the ultrasonic vibration temperature is 45℃ and the time is 50 minutes, and the solution is dried at 80℃ for 2.5 hours under nitrogen protection to form an interface-enhanced transition layer.
[0046] S2. Preparation stage of the dual-structure inorganic protective layer: magnetron sputtering power 220W, deposition temperature 120℃, target-substrate distance 10cm, deposition rate 2nm. The SiO2 dense underlayer thickness was 50 nm. The amount of nano-boehmite added was 12% of the solid content of zirconium oxide sol. Infrared assisted curing was performed at a wavelength of 5 μm, a power of 300 W, a temperature of 150 °C, and a time of 60 min, forming a porous-dense composite inorganic layer with a thickness of 250 nm.
[0047] S3, the construction stage of the temperature-sensitive organic protective layer, with a phase change microcapsule addition of 15wt%, an anti-UV agent addition of 12wt%, and a dipping rate of 8cm. After 5 minutes of infrared leveling at a wavelength of 4μm, a power of 150W, and a time of 5 minutes, a gradient curing process was performed to form an organic protective layer with a thickness of 400nm.
[0048] S4. Interface co-enhancement post-processing stage, vacuum degree 10Pa, ultraviolet power 120mW cm 2 Heating temperature 140℃, held for 60 min, surface pressure 0.1 MPa applied, heating rate 5℃. min, cooling rate 2℃ min.
[0049] Performance test results show that after 1000 hours of xenon lamp aging test, the coating weight loss rate is 1.8% and the tensile strength retention rate is 86%; after 530 hours of salt spray test, there is no rust; the coating is tightly bonded to the polyimide substrate and can still maintain stable performance under high temperature environment.
[0050] Example 4 The substrate used in this embodiment is an aluminum alloy with dimensions of 60mm × 60mm × 2.5mm, and the processing method is the same as in Example 1. The carbon nanotube coating is a multi-walled carbon nanotube with a diameter of 35nm and a length of 12μm, prepared by electrophoretic deposition, and the coating thickness is 4.5μm. The raw materials used include 7nm amino-coated carbon quantum dots, γ-aminopropyltriethoxysilane, 99.9% pure argon, oxygen, carbon tetrafluoride gas, 99.9% pure SiO2 target material, AlOOH type nano-boehmite, 13wt% solid content zirconium oxide sol, 38wt% solid content polyvinyl fluoride-acrylate copolymer, a core material of dodecanol-tetradecyl alcohol complex, a wall material of polymethyl methacrylate with a particle size of 1.8μm, and nano-TiO2. The equipment used for SiO2 core-shell particles and UV-531 UV stabilizer is the same as that used in Example 1.
[0051] The process is as follows: S1, Gradient interface modification pretreatment stage, plasma treatment power is maintained in stages for 7 min, substrate bias voltage is -90V, total gas flow rate is 38 sccm, and treatment temperature is 33℃. The amount of aminated carbon quantum dots added to the modification solution is 1.2wt%, the amount of γ-aminopropyltriethoxysilane added is 2.8wt%, ultrasonic vibration time is 35 min, temperature is 38℃, and drying is carried out at 72℃ for 2 h under nitrogen protection.
[0052] S2, in the preparation stage of the dual-structure inorganic protective layer, the magnetron sputtering deposition rate is 1.2 nm. The SiO2 dense underlayer thickness is 35nm, the amount of nano-boehmite added is 9% of the solid content of zirconium oxide sol, the infrared-assisted curing temperature is 135℃ and the time is 45min, and the composite inorganic layer thickness is 180nm.
[0053] S3, the construction stage of the temperature-sensitive organic protective layer, with 11wt% phase change microcapsules and 9wt% UV stabilizer, and a dipping rate of 6.5cm. The infrared leveling time was 3.5 min, and the thickness of the organic protective layer after gradient curing was 320 nm.
[0054] S4. Post-processing stage for interface co-enhancement enhancement: vacuum degree 7 Pa, UV power 90 mW. cm 2 The heating temperature was 125℃, held for 45 minutes, with a surface pressure of 0.06 MPa applied, and a heating rate of 3.5℃. min.
[0055] Performance tests show that after 1000 hours of xenon lamp aging test, the coating weight loss rate is 1.4% and the tensile strength retention rate is 89%; after 560 hours of salt spray test, there is no rust; the coating has balanced overall performance and is suitable for application requirements under various working conditions.
[0056] Comparative Example 1 This comparative example uses the same raw materials, equipment, and most process parameters as Example 1, except for the absence of the S1 gradient interface modification pretreatment step. The S2 step directly prepares the dual-structure inorganic protective layer on the surface of the original carbon nanotube coating. Specifically, an aluminum alloy substrate with a carbon nanotube coating, after being ultrasonically cleaned with acetone and dried, is directly placed into a magnetron sputtering apparatus to deposit a dense SiO2 underlayer. Subsequent steps S2, S3, and S4 are identical to those in Example 1. Performance test results show that after 1000 hours of xenon lamp aging, the coating weight loss rate is 4.8%, and the tensile strength retention rate is only 62%. After 400 hours of salt spray testing, significant peeling and corrosion appear at the coating edges. The main reason is the lack of gradient interface modification treatment, resulting in weak interfacial bonding between the carbon nanotube coating and the inorganic protective layer. Gaps easily form between the layers, allowing corrosive media such as water and oxygen to penetrate, accelerating the aging and failure of the coating.
[0057] Comparative Example 2 This comparative example uses the same raw materials, equipment, and most process parameters as Example 1, except that the S2 dual-structure inorganic protective layer is replaced with a single SiO2 dense layer. Specifically, the coating of zirconium oxide sol doped with nano-boehmite and the subsequent forced-air drying and infrared-assisted curing steps are omitted. The thickness of the SiO2 dense underlayer prepared by magnetron sputtering is adjusted to 240 nm. All other process steps remain the same as in Example 1. Performance test results show that after 1000 hours of xenon lamp aging, the coating weight loss rate is 3.2%, the tensile strength retention rate is 75%, and a small number of rust spots appear on the coating surface after 500 hours of salt spray testing. Its protective effect is inferior to that of Example 1. This is because although the single SiO2 dense layer has a certain water and oxygen barrier capacity, it lacks a porous-dense composite structure. The sheet-like barrier effect of the nano-boehmite is not fully utilized, and the water and oxygen permeation rate is higher than that of the dual-structure inorganic protective layer in Example 1, leading to faster coating aging.
[0058] Comparative Example 3 This comparative example uses the same raw materials, equipment, and most process parameters as Example 1, except that the S3 temperature-sensitive organic protective layer is replaced with a common polyvinyl fluoride-acrylate coating, i.e., phase change microcapsules and UV stabilizers are not added. All other process steps are the same as in Example 1. Performance tests show that after 1000 hours of xenon lamp aging, the coating weight loss rate is 4.2%, and the tensile strength retention rate is 70%. After 480 hours of salt spray testing, the coating surface shows chalking and slight corrosion. This is mainly because the lack of temperature regulation from the phase change microcapsules and UV shielding from the compounded UV stabilizers makes the coating prone to degradation under the synergistic effect of temperature fluctuations and UV irradiation, resulting in a significant decrease in its anti-aging ability.
[0059] Comparative Example 4 This comparative example uses the same raw materials, equipment, and most process parameters as Example 1, except for the missing S4 interface synergistic strengthening post-treatment step. That is, the final coating is obtained directly after the S3 temperature-sensitive organic protective layer is prepared. All other process steps are identical to Example 1. Performance test results show that after 1000 hours of xenon lamp aging, the coating weight loss rate is 3.5%, and the tensile strength retention rate is 72%. After 520 hours of salt spray testing, the coating exhibits localized peeling. This is because the lack of UV-thermal synergistic treatment and surface pressure application prevented the formation of stable Si-OC covalent bonds at the inorganic-organic interface, resulting in insufficient interlayer bonding. This makes the coating prone to interlayer separation during long-term service, leading to the failure of the protective system.
[0060] As can be seen from the test results of Examples 1-4, regardless of whether aluminum alloy, quartz, or polyimide substrate is used, and regardless of how the parameters such as carbon nanotube coating thickness, raw material addition amount, and processing temperature and time are reasonably adjusted within the limited range, the final modified carbon nanotube coating exhibits excellent anti-aging performance and stable core functions. After 1000h xenon lamp aging test, the weight loss rate of the coating in all examples was controlled between 1.2% and 1.8%, the tensile strength retention rate reached 86%-90%, and the salt spray resistance test showed no rust-free time exceeding 530h. Moreover, the thermal conductivity and spectral absorption performance of the coating did not show significant attenuation. This fully demonstrates that the process of the present invention has strong adaptability to different substrates, flexible parameter control, and can achieve comprehensive aging protection without destroying the inherent excellent properties of carbon nanotubes.
[0061] The test results of Comparative Examples 1-4 were lower than those of the Examples. Comparative Example 1, lacking the S1 gradient interface modification pretreatment, had a weak interfacial bond between the carbon nanotubes and the protective layer, resulting in a tensile strength retention rate of only 62% after aging and a significant decrease in salt spray resistance. Comparative Example 2, which replaced the S2 dual-structure inorganic protective layer with a single dense SiO2 layer, lost the sheet barrier effect of nano-boehmite, leading to accelerated water and oxygen permeation rates and a significant increase in coating weight loss and corrosion risk. Comparative Example 3, which did not add phase change microcapsules and UV stabilizers, could not resist the synergistic corrosion of temperature fluctuations and UV irradiation, and the coating was prone to degradation and powdering. Comparative Example 4, lacking the S4 interface synergistic strengthening posttreatment, failed to form stable covalent bonds at the inorganic-organic interface, resulting in insufficient interlayer bonding and localized peeling after long-term service.
[0062] Therefore, this invention employs the aforementioned carbon nanotube coating aging protection process. Through a specific ratio of argon, oxygen, and carbon tetrafluoride plasma composite treatment, a hydroxyl-fluorine gradient distribution is formed on the surface of the carbon nanotubes. Then, through the synergistic modification of aminated carbon quantum dots and γ-aminopropyltriethoxysilane, a highly efficient interface-enhanced transition layer is constructed. Subsequent UV-thermal synergistic treatment further promotes the formation of stable Si-OC covalent bonds at the inorganic-organic interface, significantly improving the bonding strength between the coating and the substrate and between layers. After long-term aging tests, the coating tensile strength retention rate can still reach more than 85%, effectively avoiding peeling problems caused by insufficient bonding strength during service. The dual-structure inorganic protective layer provides excellent water and oxygen shielding. The dense SiO2 underlayer prepared by magnetron sputtering blocks the direct penetration of water and oxygen, while the zirconium oxide sol coating doped with nano-boehmite further enhances the shielding performance through a layered barrier effect. In the temperature-sensitive organic protective layer, phase change microcapsules effectively mitigate the effects of temperature fluctuations, and the compounded UV absorber efficiently absorbs ultraviolet light. Through their synergistic effect, the coating can simultaneously resist multiple aging factors such as water and oxygen corrosion and ultraviolet radiation. After long-term aging tests, the coating's weight loss rate is controlled within 2%, and its salt spray resistance reaches over 500 hours without corrosion. Simultaneously, this process enhances protective performance without compromising the excellent thermal conductivity and endothermic properties of carbon nanotubes, and the multi-layered protective structure does not adversely affect the coating's spectral absorption performance, ensuring the stable preservation of the coating's core functions and effectively suppressing the decline in energy conversion efficiency during service. In addition, the plasma treatment, magnetron sputtering, dip coating and other technologies used in the process are all mature material preparation methods. The parameters are set reasonably and are easy to control on a large scale. They can be adapted to a variety of commonly used substrates, and the coating thickness is controllable. They have good process adaptability and practical application value, and can significantly extend the service life of related equipment.
[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A process for carbon nanotube coating weatherization, characterized by, The method comprises the following steps: S1, gradient interface modification pretreatment: the substrate with carbon nanotube coating is subjected to plasma composite treatment, the working gas is argon, oxygen and carbon tetrafluoride mixed gas with a volume ratio of 4:2:1, and the power is controlled in stages to build a gradient distribution of hydroxyl-fluorine group on the surface of the carbon nanotube; then the coating is immersed in an ethanol-water mixed solution containing amino-functionalized carbon quantum dots and gamma-aminopropyl triethoxysilane, and after ultrasonic oscillation, it is dried under nitrogen protection to form an interface enhanced transition layer; S2, preparation of double-structure inorganic protective layer: a dense SiO2 bottom layer is deposited on the surface of the transition layer by magnetron sputtering, and then a zirconium oxide sol doped with nano-boehmite is coated on the surface of the dense bottom layer, after air drying and infrared assisted curing, a porous-dense composite inorganic layer is formed; S3, construction of temperature-sensitive organic protective layer: a composite organic coating with polyvinyl fluoride-acrylate copolymer as the matrix, phase change microcapsules and ultraviolet resistant agent is prepared, and after coating by using the immersion coating-infrared leveling composite process, infrared leveling and gradient curing are performed to form an organic protective layer; S4, interface synergistic strengthening post-treatment: the composite coating is subjected to ultraviolet-heat synergistic treatment in a vacuum environment, and a surface pressure is applied during the treatment to promote the formation of Si-O-C covalent bonds at the inorganic-organic interface, thereby obtaining an aging protection modified carbon nanotube coating.
2. The carbon nanotube coating weatherization process of claim 1, wherein, In step S1, the power of the plasma composite treatment is 80W, 120W and 160W in stages, each stage is maintained for 6-10min, and the treatment temperature is 30-40℃.
3. The carbon nanotube coating weatherization process of claim 1, wherein, In step S1, the addition amount of the amino-functionalized carbon quantum dots is 1-2wt% of the modification liquid, and the particle size is 5-10nm; the addition amount of the gamma-aminopropyl triethoxysilane is 2-4wt% of the modification liquid; the volume ratio of ethanol to water is 4:1; the ultrasonic oscillation temperature is 35-45℃, the time is 30-50min, and the power is 300W; the drying temperature is 70-80℃, and the time is 1.5-2.5h.
4. The carbon nanotube coating weatherization process of claim 1, wherein, In step S2, the power of the magnetron sputtering is 180-220W, the pressure of the argon atmosphere is 0.5Pa, the deposition temperature is 100-120℃, and the thickness of the SiO2 dense bottom layer is 30-50nm.
5. The carbon nanotube coating weatherization process of claim 1, wherein, In step S2, the nano-boehmite is AlOOH and the addition amount is 8-12% of the solid content of the zirconium oxide sol; the solid content of the zirconium oxide sol is 10-15wt%.
6. The carbon nanotube coating weatherization process of claim 1, wherein, In step S2, the air drying temperature is 60℃, and the time is 1h; the infrared assisted curing wavelength is 3-5μm, the power is 200-300W, the temperature is 130-150℃, the time is 40-60min; and the thickness of the porous-dense composite inorganic layer is 150-250nm.
7. The carbon nanotube coating weatherization process of claim 1, wherein, In step S3, the solid content of the polyvinyl fluoride-acrylate copolymer is 30-40 wt%; the added amount of the phase change microcapsule is 10-15 wt% of the base, the core material thereof is a dodecanol-tetradecanol compound, the wall material thereof is polymethyl methacrylate, and the particle size thereof is 1-3 μm; the added amount of the anti-ultraviolet agent is 8-12 wt% of the base, and the anti-ultraviolet agent is a nano-TiO2 The SiO2core-shell particles are compounded with UV-531 at a mass ratio of 2:
1.
8. The carbon nanotube coating weatherization process of claim 1, wherein, In step S3, the dip coating rate is 5-8 cm min; the wavelength of the infrared flow level is 2-4 μm, the power is 150 W, and the time is 3-5 min; the gradient curing is 70 °C for 1.5 h, 90 °C for 2 h, and 110 °C for 1 h in turn; the thickness of the organic protective layer is 250-400 nm.
9. The carbon nanotube coating weatherization process of claim 1, wherein, In step S4, the vacuum degree of the vacuum environment is 5-10 Pa; the ultraviolet wavelength of the ultraviolet-heat synergic treatment is 254 nm, and the power is 80-120 mW cm 2 , the heating temperature is 120-140 ℃, the holding time is 40-60 min, and the applied surface pressure is 0.05-0.1 MPa.
10. The carbon nanotube coating weatherization process of claim 1, wherein, The carbon nanotube coating is a multi-walled carbon nanotube with a tube diameter of 20-50nm and a length of 5-20μm, which is prepared by electrophoretic deposition and has a coating thickness of 2-6μm; and the substrate is an aluminum alloy, quartz or polyimide.