A composite coating and its preparation method

Abstract

This application relates to the field of composite coating technology, specifically to a composite coating and its preparation method. The composite coating includes: a hard layer stacked on top of each other and a nano-grass layer. Because the nano-grass layer is arranged in a three-dimensional manner, numerous micron or nano-sized pores and gaps are formed both between the nano-grasses and within the nano-grasses themselves. These pores and gaps can trap air, with air accounting for 60% to 90% of the nano-grass layer, thus reducing convective heat transfer caused by airflow. Furthermore, the nano-grass itself has a high specific surface area, irregular morphology, and interfacial differences, which also lengthens the heat conduction path and reduces heat conduction efficiency. Therefore, the nano-grass structure layer has excellent thermal insulation capabilities.

Description

Technical Field

[0001] This application relates to the field of composite coating technology, specifically to a composite coating and its preparation method. Background Technology

[0002] Composite coatings typically consist of multiple layers, but current composite coatings on the market have poor thermal insulation performance, failing to meet industry needs. Therefore, improving the thermal insulation performance of composite coatings has become an urgent technical problem to be solved. Summary of the Invention

[0003] This application provides a composite coating and its preparation method to address the current industry demand for thermal insulation functions that composite coatings cannot meet.

[0004] This application provides a composite coating comprising: a hard layer and a nano-grass layer disposed sequentially; wherein the air content in the nano-grass layer is 60% to 90%.

[0005] In one embodiment, the nanograss layer includes multiple nanograsses, and the multiple nanograss arrays are arranged on the surface of the hard layer.

[0006] In one embodiment, at least one of the following conditions is met: the average length of the nanograss in the nanograss layer is 200nm~1000nm; the average ratio of the length of the nanograss to the diameter of the root of the nanograss in the nanograss layer is 2~10; the average curvature of the nanograss in the nanograss layer is 0°~60°; and the average spacing between adjacent nanograsses in the nanograss layer is 100nm~1000nm.

[0007] In one embodiment, at least one of the following conditions is met: the average length of the nanograss in the nanograss layer is 400nm~700nm; the average ratio of the length of the nanograss to the diameter of the root of the nanograss in the nanograss layer is 4~6; the average curvature of the nanograss in the nanograss layer is 0°~30°; the average spacing between adjacent nanograsses in the nanograss layer is 400nm~700nm; and the air content in the nanograss layer is 70%~80%.

[0008] In one embodiment, at least one of the following is satisfied: a photothermal layer is disposed between the hard layer and the nanograss layer, and a plurality of nanograss arrays are arranged on the surface of the photothermal layer; a hydrophobic layer is disposed on the surface of the nanograss layer, and the nanograss layer is disposed between the hard layer and the hydrophobic layer; the hydrophobic layer is a monomolecular hydrophobic layer formed by modifying the surface of the nanograss layer with a modifier.

[0009] In one embodiment, at least one of the following is satisfied: the thickness of the hard layer is 1μm to 4μm; the thickness of the photothermal layer is 500nm to 2000nm; the thickness of the nanograss layer is 100nm to 1000nm; and the hard layer includes at least one of the following: a high-entropy alloy layer, diamond-like carbon, or CrSiCN.

[0010] In one embodiment, at least one of the following is satisfied: the material of the high-entropy alloy layer includes at least one of the following: WAlTiCrSi, CoCrFeNiCu, FeMnCoCr, TiZrHfVNb; the material of the photothermal layer includes at least one of the following: carbon-based photothermal material, metal photothermal material, semiconductor photothermal material, organic polymer photothermal material; the material of the nanograss layer includes at least one of the following: copper oxide, zinc oxide, titanium dioxide, polyvinyl alcohol; the modifier includes at least one of the following: fluorine-containing modifier, siloxane modifier, silane modifier.

[0011] In one embodiment, at least one of the following is satisfied: the carbon-based photothermal material includes at least one of the following: carbon nanotubes, graphene, carbon black; the metal photothermal material includes at least one of the following: gold nanoparticles, TiN, ZrN; the semiconductor photothermal material includes at least one of the following: TiO2, CuS, Ti2O3; the organic polymer photothermal material includes at least one of the following: polyaniline, polypyrrole, polydopamine.

[0012] In one embodiment, at least one of the following conditions is met: the material of the high-entropy alloy layer is WAlTiCrSi; the material of the photothermal layer is TiN; and the material of the nanograss layer is copper oxide.

[0013] In one embodiment, at least one of the following is satisfied: the fluorinated modifier includes at least one of the following: perfluorodecyltrimethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltriethoxysilane, perfluorododecyl mercaptan; the siloxane modifier is polydimethylsiloxane; and the silane modifier is vinyltriethoxysilane.

[0014] In one embodiment, the fluorinated modifier is perfluorodecyltrimethoxysilane.

[0015] In one embodiment, at least one of the following conditions is met: the thermal conductivity of the composite coating is 0.127 W / mk to 0.173 W / mk; the antibacterial rate of the composite coating is greater than 99%; the water contact angle of the composite coating is greater than 150° and the roll-off angle is less than 10°.

[0016] This application also provides a method for preparing a composite coating, the method comprising: depositing a nanograss precursor layer on the surface of a hard layer; oxidizing the nanograss precursor layer to generate a nanograss layer on the surface of the hard layer, thereby obtaining a composite coating.

[0017] In one embodiment, depositing a nanograss precursor layer on a hard layer surface includes: depositing the nanograss precursor layer on the hard layer surface by physical vapor deposition.

[0018] In one embodiment, the parameters for the physical vapor deposition of the nanograss precursor layer include: temperature of 80°C to 100°C, vacuum of 0.4Pa to 0.6Pa, power of 4kW to 6kW, and sputtering time of 250s to 350s.

[0019] This application provides a composite coating comprising: a hard layer and a nano-grass layer stacked together. Because the nano-grass layer is arranged in a three-dimensional manner, numerous micron or nano-sized pores and gaps are formed both between the nano-grasses and within the nano-grasses themselves. These pores and gaps trap air, with air comprising 60% to 90% of the nano-grass layer, thus reducing convective heat transfer caused by airflow. Furthermore, the nano-grass itself possesses a high specific surface area, irregular morphology, and interfacial differences, which also lengthen the heat conduction path and reduce heat conduction efficiency. Therefore, the nano-grass structure layer exhibits excellent thermal insulation capabilities. Since the hard layer itself possesses good hardness and wear resistance, the entire composite coating combines hardness, wear resistance, and thermal insulation properties. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a structural diagram of a high-entropy alloy composite coating according to an embodiment of this application. Figure reference numerals: 1-rigid layer; 2-photothermal layer; 3-nanograss layer; 4-hydrophobic layer; 5-substrate. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0022] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0023] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0024] This application provides a composite coating, such as Figure 1 As shown, the composite coating includes: a hard layer 1 and a nano-grass layer 3 stacked together; the air content in the nano-grass layer is 60%~90%.

[0025] Because the nanograss layer is arranged in a three-dimensional manner, numerous micron or nano-sized pores and gaps are formed both between the nanograsses and within the nanograsses themselves. These pores and gaps trap air, which accounts for 60% to 90% of the nanograss layer, thus reducing convective heat transfer caused by airflow. Furthermore, the nanograss itself has a high specific surface area, irregular morphology, and interfacial differences, which also lengthen the heat conduction path and reduce heat conduction efficiency. Therefore, the nanograss structure layer has excellent thermal insulation capabilities. Since the hard layer itself has good hardness and wear resistance, the entire composite coating combines hardness, wear resistance, and thermal insulation properties.

[0026] In one embodiment, the nanograss layer includes multiple nanograsses arranged in an array on the surface of a rigid layer. This design ensures better thermal insulation of the composite coating and facilitates the subsequent formation of a hydrophobic layer on its surface. The nanograsses typically grow vertically or obliquely on the substrate, exhibiting nanoscale protrusions resembling grass leaves.

[0027] In one embodiment, the average length of the nanograss in the nanograss layer is 200nm~1000nm. The length range of the nanograss can adjust the heat conduction path and reduce the heat conduction efficiency.

[0028] In one embodiment, the average spacing between adjacent nanograsses in the nanograss layer is 100nm~1000nm. This spacing can adjust the air content in the nanograss layer to 60%~90%, thereby reducing convective heat transfer caused by airflow.

[0029] In one embodiment, the ratio of the length of the nanograss to the diameter of its root in the nanograss layer averages 2 to 10. This ratio describes the slenderness of the nanograss. Nanograss structures within this range have excellent air content, which not only improves their superhydrophobic properties but also takes into account their mechanical properties, preventing breakage of the nanograss structure during use due to excessive slenderness.

[0030] In one embodiment, the average curvature (angle between the direction pointed to by the tip and the vertical direction) of the nanograss in the nanograss layer is 0° to 60°. This curvature describes the degree of bending of the nanograss. Nanograss structures within this range not only ensure the air content of the nanograss layer but also improve the superhydrophobic properties of the nanograss layer.

[0031] Specifically, the average length of the nanograss in the nanograss layer is 200nm, 400nm, 800nm, 1000nm, or any value within the above range; the average ratio of the length of the nanograss to the diameter of the root of the nanograss in the nanograss layer is 2, 5, 8, 10, or any value within the above range; the average curvature (angle between the direction pointed to by the tip and the vertical direction) of the nanograss in the nanograss layer is 0°, 30°, 50°, 60°, or any value within the above range; the average spacing between adjacent nanograsses in the nanograss layer is 100nm, 300nm, 500nm, 800nm, 1000nm, or any value within the above range; and the air content in the nanograss layer is 60%, 70%, 80%, 90%, or any value within the above range.

[0032] It should be noted that the length of the nanograss, the diameter of the nanograss root, the curvature of the nanograss, the average spacing between adjacent nanograsses, and the air content in the nanograss layer can all be obtained by measuring the electron microscope images of the nanograss structure using a ruler.

[0033] In one embodiment, when the average length of the nanograss in the nanograss layer is 400nm~700nm; the ratio of the length of the nanograss to the diameter of the root of the nanograss in the nanograss layer is 4~6 on average; the average curvature of the nanograss in the nanograss layer is 0°~30°; and the average spacing between adjacent nanograsses in the nanograss layer is 400nm~700nm, the air content in the nanograss layer is 70%~80%, ensuring that the nanograss layer has better heat insulation function.

[0034] In one embodiment, the composite coating further includes: a photothermal layer 2 disposed between the hard layer 1 and the nanograss layer 3, wherein multiple nanograss arrays are arranged on the surface of the photothermal layer, such as... Figure 1 As shown in the image. This photothermal layer possesses excellent photothermal conversion capabilities, enabling rapid heating to inactivate bacteria. It can be applied in the field of antibacterial applications, achieving an antibacterial rate of up to 99%.

[0035] In one embodiment, the composite coating further includes a hydrophobic layer 4 disposed on the surface of the nanograss layer 3, wherein the nanograss layer 3 is disposed between the hard layer 1 and the hydrophobic layer 4. The hydrophobic layer is a monomolecular hydrophobic layer formed by modifying the surface of the nanograss layer with a modifier. In this embodiment, the composite coating exhibits superhydrophobic properties (contact angle > 150°, roll-off angle < 10°) through the synergistic effect of the nanograss layer and the hydrophobic layer. Detailed analysis follows: 1. Monomolecular hydrophobic layers provide a basis for low surface energy substrates.

[0036] Modifiers (such as perfluorodecyltrimethoxysilane, polydimethylsiloxane, etc.) bind to the active groups (such as hydroxyl, carboxyl, etc.) on the surface of the nanograss layer through chemical bonds (such as silicon-oxygen bonds, covalent bonds), forming a tightly packed monolayer. The key characteristic of this monolayer is its extremely low surface energy. According to thermodynamic principles, liquids tend to spread (wet) on high surface energy surfaces and contract (non-wet) on low surface energy surfaces. Therefore, the low surface energy monolayer fundamentally reduces the adhesion of water molecules to the surface of the nanograss layer.

[0037] 2. The nanograss layer provides a micro-nano multi-level rough structure.

[0038] The nanograss layer itself is composed of a large number of nanoscale grass-like protrusions. Its surface is not smooth, but has nanoscale protrusions and gaps, which is equivalent to a micro-nano rough structure. The function of this structure is that when water molecules come into contact with the surface, they cannot completely fill the nano gaps. Instead, they capture a layer of stationary air film in the gaps, forming a three-phase contact mode of water-air-solid, rather than a two-phase contact of water-solid on a smooth surface.

[0039] Therefore, when water molecules land on the surface of this composite coating, they are supported by the protrusions of the nano-grass. The air trapped between the nano-grass particles forms a continuous air cushion, separating the water molecules from the solid surface of the nano-grass layer. In other words, the water molecules only come into contact with the tips of the nano-protrusions (the parts covered by the monomolecular hydrophobic layer). At the same time, the low surface energy monomolecular hydrophobic layer further weakens the interaction between the water molecules and the tips of the protrusions, causing the surface tension of the water molecules to dominate and shrink their shape into spherical droplets, ultimately achieving superhydrophobicity.

[0040] Of course, the composite coating can include both the photothermal layer 2 and the hydrophobic layer 4.

[0041] In one embodiment, the hard layer material includes: high-entropy alloy, diamond-like carbon, and CrSiCN.

[0042] High-entropy alloys exhibit good strength and high-temperature resistance through multiple mechanisms such as grain refinement and solid solution strengthening. Diamond-like carbon (DLC) is an amorphous carbon-based thin film material with carbon (C) as its core component. Some types are doped with elements such as hydrogen (H), nitrogen (N), and silicon (Si). Its structure lies between diamond (sp³ hybridized carbon) and graphite (sp² hybridized carbon), thus combining the excellent properties of both. Therefore, its high hardness, low friction, and corrosion resistance can be used to improve the performance of the substrate. For example, hydrogen-free DLC is composed of pure carbon with a high sp³ hybridization ratio, exhibiting the highest hardness and good temperature resistance. CrSiCN is a multi-component hard material composed of chromium (Cr), silicon (Si), carbon (C), and nitrogen (N). Through the solid solution effect of Si and C elements, it can refine grains, inhibit crack initiation and propagation, and significantly improve the coating's hardness and wear resistance.

[0043] In one embodiment, the thickness of the hard layer is 1μm to 4μm. According to process debugging experiments, if the thickness exceeds this range, the material's performance cannot meet expectations; if the thickness is below this range, a marginal effect occurs, resulting in insignificant performance improvement but a significant increase in time component costs, material costs, and energy costs. Therefore, this hard layer thickness range not only ensures the hardness of the composite coating but also saves costs and processing time.

[0044] Specifically, the thickness of the hard layer is 1μm, 2μm, 3μm, 4μm or any value within the above range.

[0045] In one embodiment, the thickness of the photothermal layer is 500nm~2000nm. According to the results of process debugging experiments, if the thickness exceeds this range, the material performance cannot meet expectations; if the thickness is below this range, a marginal effect will occur, resulting in a situation where the performance improvement is not significant, but the time component, consumable costs, and energy costs increase significantly. Therefore, this range of photothermal layer thickness can not only ensure the antibacterial performance of the composite coating, but also save costs and processing time.

[0046] Specifically, the thickness of the photothermal layer is 500nm, 1000nm, 1500nm, 2000nm or any value within the above range.

[0047] In one embodiment, the thickness of the nanograss layer is 100nm~1000nm. According to the results of process debugging experiments, if the thickness exceeds this range, the material performance cannot meet expectations; if the thickness is below this range, a marginal effect will occur, resulting in a situation where the performance improvement is not significant, but the time component, consumable costs, and energy costs increase significantly. Therefore, this range of nanograss layer thickness can not only ensure the hydrophobic properties of the composite coating, but also reduce the photothermal properties of the composite coating, thereby having better thermal insulation performance.

[0048] Specifically, the thickness of the nanograss layer is 100nm, 400nm, 800nm, 1000nm or any value within the above range.

[0049] In one embodiment, the high-entropy alloy layer comprises at least one of the following materials: WAlTiCrSi, CoCrFeNiCu, FeMnCoCr, and TiZrHfVNb. This material composition allows for better bonding with the substrate used in preparing the composite coating, while also possessing good mechanical properties.

[0050] Specifically, the material of the high-entropy alloy layer is WAlTiCrSi. The elemental composition of WAlTiCrSi high-entropy alloy gives it better comprehensive mechanical properties, wear resistance, oxidation resistance and corrosion resistance. At the same time, the high-entropy alloy composed of this element can form an amorphous structure without defects such as grain boundaries and dislocations, and can maintain the stability of the structure in high temperature, friction and corrosion environments to reduce the risk of local failure.

[0051] In one embodiment, the photothermal layer is made of at least one of the following: carbon-based photothermal materials, metallic photothermal materials, semiconductor photothermal materials, and organic polymer photothermal materials. These materials all possess photothermal effects that enable rapid heating, thereby inactivating bacteria and ultimately achieving an antibacterial effect, while also exhibiting good mechanical properties and low cost.

[0052] Among them, carbon-based photothermal materials include carbon nanotubes, graphene, carbon black, etc.; metal photothermal materials include gold nanoparticles, TiN, ZrN, etc.; semiconductor photothermal materials include TiO2, CuS, Ti2O3, etc.; and organic polymer photothermal materials include polyaniline, polypyrrole, polydopamine, etc.

[0053] The principle behind the photothermal effect of carbon-based photothermal materials is as follows: after the conjugated electron system in these materials absorbs photons, the electrons transition to an excited state and then return to the ground state through non-radiative relaxation, converting energy into lattice thermal vibration energy, thus achieving photothermal conversion. The principle behind the photothermal effect of metallic photothermal materials is as follows: free electrons on the surface of metal particles oscillate with the electric field generated by light, absorb photon energy, and then transfer the energy to the lattice through electron-phonon scattering, generating heat, thus achieving photothermal conversion. The principle behind the photothermal effect of semiconductor photothermal materials is as follows: when the incident photon energy is greater than the band gap of these materials, valence band electrons transition to the conduction band, generating electron-hole pairs. Photogenerated charge carriers (electrons and holes) transfer energy into lattice vibrations through non-radiative recombination methods such as phonon emission, achieving photothermal conversion. The principle behind the photothermal effect of organic polymer materials is as follows: through the conjugated structure or donor-acceptor structure of these materials, photon energy is absorbed, triggering electron transitions. Subsequently, the excited state energy is released as heat energy through molecular skeleton vibration and rotation, achieving photothermal conversion.

[0054] Specifically, the photothermal layer is made of TiN. TiN possesses excellent photothermal conversion performance; it also exhibits superior comprehensive mechanical properties and corrosion resistance; its preparation is simple and low-cost, facilitating large-scale production. In one embodiment, the material of the nanograss layer includes at least one of the following: copper oxide, zinc oxide, titanium dioxide, and polyvinyl alcohol. The crystals of this type of material exhibit anisotropy, meaning that the crystal growth rate in one direction is much faster than in other directions, thus facilitating the formation of nanograss structures during growth.

[0055] Specifically, the material of the nanograss layer is copper oxide. The preparation of copper oxide nanograss structure is simple and inexpensive. At the same time, there are a large number of hydroxyl groups on the surface of copper oxide nanograss, which can better combine with the modifier to form a hydrophobic layer with low surface energy.

[0056] In one embodiment, the modifier includes at least one of the following: a fluorinated modifier, a siloxane modifier, or a silane modifier. Fluorinated modifiers have the lowest surface energy, imparting better hydrophobic properties to materials; they also exhibit stronger weather resistance and chemical corrosion resistance, leading to a wider range of applications. Siloxane modifiers are fluorine-free, making them relatively environmentally friendly; their performance is highly adjustable, and can be optimized by adjusting the molecular structure. Silane modifiers are also fluorine-free, making them relatively environmentally friendly; their cost is relatively low, facilitating large-scale use.

[0057] The fluorinated modifier includes at least one of the following: perfluorodecyltrimethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltriethoxysilane, and perfluorododecyl mercaptan; the siloxane modifier is polydimethylsiloxane; and the silane modifier is vinyltriethoxysilane.

[0058] These modifiers all have fixed and functional ends in their molecular structure. The internal fixed end is responsible for binding to the surface of the nano-grass (covalent bond or strong physical adsorption), while the external functional ends (perfluoroalkyl, methyl, vinyl) provide low surface energy properties. The binding is essentially achieved through chemical or physical action to achieve strong adhesion, rather than simple detachment, ensuring stable modification effects. Because the functional ends of these modifiers are external, these functional groups are all arranged outwards, and these groups are all low surface energy groups with extremely weak intermolecular forces. Liquids (water, oil) cannot effectively adsorb onto them, thus achieving a hydrophobic effect.

[0059] In one embodiment, the fluorinated modifier is perfluorodecyltrimethoxysilane. Perfluorodecyltrimethoxysilane has extremely low surface energy, thus giving the composite coating superhydrophobic properties. Simultaneously, the methoxy group in the perfluorodecyltrimethoxysilane molecule, after hydrolysis, generates a highly reactive silanol group, which can covalently bond with the hydroxyl groups on the surface of the nano-grass to form a strong hydrophobic layer. Furthermore, the hydrolysis efficiency is faster, resulting in higher modification efficiency, making it suitable for industrial production.

[0060] In one embodiment, the average thermal conductivity of the composite coating is 0.127 W / mk to 0.173 W / mk.

[0061] In one embodiment, the antibacterial rate of the composite coating is greater than 99%.

[0062] In one embodiment, the composite coating has a water contact angle greater than 150° and a roll-off angle less than 10°.

[0063] This application also provides a method for preparing a composite coating, specifically including: S1. Deposit a nanograss precursor layer on the surface of hard layer 1.

[0064] S2. The nanograss precursor layer is oxidized to form nanograss layer 3 on the surface of the hard layer, and then a composite coating is obtained.

[0065] Step S1 specifically includes: 1.1 Place the ion-cleaned substrate 5 into the furnace and evacuate the furnace to a depth of 3×10⁻⁶ m³ / h. -4 Pa ~ 6×10 -4 Pa, heated to 80℃~100℃; theoretically, the substrate can be any solid material that can be magnetron sputtered, but in practice, the adhesion between the film and the substrate needs to be considered. Therefore, based on this consideration, aluminum alloy and titanium alloy are used as substrates in this application.

[0066] 1.2. Ar is introduced into the furnace to maintain a vacuum of 0.4 Pa to 0.6 Pa for 8 to 10 seconds, and then the hard layer material power supply is turned on for sputtering to prepare the hard layer; wherein, the power of the hard layer material power supply is 4 kW to 6 kW, and the sputtering time of the hard layer material is 900 s to 1100 s. 1.3 Continue evacuation up to 3×10 -4 Pa ~ 6×10 -4 Pa, heated to 80℃~100℃, and then Ar was introduced to make the vacuum degree 0.4Pa~0.6Pa. The nanograss precursor layer material power supply was turned on for sputtering to prepare the nanograss precursor layer; wherein, the power of the nanograss precursor layer / material power supply was 4kW~6kW, and the sputtering time of the nanograss precursor layer material was 250s~350s.

[0067] Step S2 specifically includes: The workpiece after preparing the nanograss precursor layer was oxidized for 550-650 seconds using a 0.5 mol / L sodium hydroxide solution mixed with a 0.13 mol / L ammonium persulfate solution in a ratio of 0.9:1 to 1:1.1, followed by cleaning to obtain the nanograss layer.

[0068] It should be noted that the method for preparing nanograss structures in this application is not limited to the above-mentioned method. Other methods can also be used, such as preparing copper oxide nanograss structures by chemical oxidation, preparing zinc oxide nanograss structures by hydrothermal method, preparing titanium dioxide nanograss structures by anodic oxidation, etc.

[0069] In one embodiment, after step 1.2 of step S1, the process further includes preparing a photothermal layer 2, specifically including: Continue evacuating to 3×10 -4 Pa ~ 6×10 -4 Pa, heated to 80℃~100℃, then Ar and N2 are introduced to make the vacuum degree 0.4Pa~0.6Pa, and the power supply for the photothermal layer material is turned on for sputtering to prepare the photothermal layer; wherein, the power supply for the photothermal layer material is 9kW~11kW, and the sputtering time of the photothermal layer material is 250s~350s.

[0070] In one embodiment, after step S2, the process further includes: modifying the nanograss layer to form a hydrophobic layer 4 on the surface of the nanograss layer, thereby obtaining a high-entropy alloy composite coating. For example, the surface of the nanograss layer is modified using a modifier to form a hydrophobic layer on the surface of the nanograss layer.

[0071] To enable those skilled in the art to better understand this application, the following detailed description, in conjunction with specific embodiments, further illustrates the application. Obviously, the described embodiments are merely some, not all, of the embodiments described. It should be understood that the specific embodiments are only used to explain the application, and are not intended to limit the scope of the application.

[0072] Example 1 A method for preparing a composite coating, comprising: 1. Place the ion-cleaned substrate into the furnace and evacuate the furnace to a temperature of 5×10⁻⁶. -4 Pa, heated to 90℃.

[0073] 2. Ar is introduced into the furnace to maintain a vacuum of 0.5 Pa for 10 s, and then the hard layer material power supply is turned on for sputtering to prepare the hard layer; wherein, the power of the hard layer material sputtering power supply is 4kW, and the sputtering time of the hard layer material is 900s.

[0074] 3. Continue evacuation up to 5×10 -4 Pa, heated to 90℃, and then Ar and N2 were introduced to make the vacuum degree 0.5Pa. The power supply for sputtering of the photothermal layer material was turned on to prepare the photothermal layer. The power supply for sputtering the photothermal layer material was 9kW and the sputtering time was 250s.

[0075] 4. Continue evacuation up to 5×10 -4Pa, heated to 90℃, and then Ar was introduced to make the vacuum degree 0.5 Pa. The power supply for sputtering of the nanograss layer material was turned on to prepare the nanograss precursor layer. The power supply for sputtering the nanograss precursor layer material was 4kW and the sputtering time was 250s.

[0076] 5. The workpiece after preparing the nanograss precursor layer was oxidized for 600 seconds using a 1:1 mixture of 0.5 mol / L sodium hydroxide solution and 0.13 mol / L ammonium persulfate solution, and then cleaned. The nanograss layer was obtained by oxidizing the nanograss precursor layer.

[0077] 6. After modifying the nano-grass layer with a modifier to form a hydrophobic layer, a high-entropy alloy composite coating is obtained after removing the substrate.

[0078] The substrate is an aluminum alloy; the hard layer material is WAlTiCrSi (the mass fractions of W, Ai, Ti, Cr, and Si are 36%, 15%, 11%, 25%, and 13%, respectively); the photothermal layer material is TiN; the nanograss layer material is copper oxide (the average length of the nanograss is 453 nm, the average ratio of the length of the nanograss to the diameter of the nanograss root is 6.9, the average curvature of the nanograss bend is 32°, the average spacing between adjacent nanograsses is 638 nm, and the air content in the nanograss layer is 85%); and the modifier is perfluorodecyltrimethoxysilane.

[0079] Example 2 The difference from Example 1 is that the substrate is a titanium alloy.

[0080] Example 3 The difference from Example 1 is that the high-entropy alloy layer material is CoCrFeNiCu.

[0081] Example 4 The difference from Example 1 is that the high-entropy alloy layer material is TiZrHfVNb.

[0082] Example 5 The difference from Example 1 is that the photothermal layer material is graphene.

[0083] Example 6 The difference from Example 1 is that the photothermal layer material is TiO2.

[0084] Example 7 The difference from Example 1 is that the photothermal layer material is polypyrrole.

[0085] Example 8 The difference from Example 1 is that the nanograss layer material is zinc oxide (the average length of the nanograss is 316 nm, the average ratio of the length of the nanograss to the diameter of the nanograss root is 2.9, the average curvature of the nanograss is 41°, the average spacing between adjacent nanograsses is 458 nm, and the air content in the nanograss layer is 76%).

[0086] Example 9 The difference from Example 1 is that the nanograss layer material is titanium dioxide (the average length of the nanograss is 235 nm, the average ratio of the length of the nanograss to the diameter of the nanograss root is 2.7, the average curvature of the nanograss is 9°, the average spacing between adjacent nanograsses is 401 nm, and the air content in the nanograss layer is 81%).

[0087] Example 10 The difference from Example 1 is that the modifier is perfluorooctyltrimethoxysilane.

[0088] Example 11 The difference from Example 1 is that the modifier is polydimethylsiloxane.

[0089] Example 12 The difference from Example 1 is that the power supply for the high-entropy alloy layer material is 6kW, and the sputtering time for the high-entropy alloy layer material is 1100s.

[0090] Example 13 The difference from Example 1 is that the power supply for the photothermal layer material is 11kW and the sputtering time for the photothermal layer material is 350s.

[0091] Example 14 The difference from Example 1 is that the power supply for the nanograss layer material is 6kW, the sputtering time for the nanograss layer material is 350s (the average length of the nanograss is 983nm, the average ratio of the length of the nanograss to the diameter of the nanograss root is 9.8, the average curvature of the nanograss is 53°, the average spacing between adjacent nanograsses is 116nm, and the air content in the nanograss layer is 63%).

[0092] Example 15 The difference from Example 1 is that the photothermal layer in step 3 is not present.

[0093] Example 16 The difference from Example 1 is that the hard layer material is hydrogen-free DLC.

[0094] Example 17 The difference from Example 1 is that the hard layer material is CrSiCN (the mass fractions of Cr, Si, C and N are 28%, 14%, 42% and 8% respectively, and the remaining 8% are impurities such as H and O).

[0095] Comparative Example 1 The difference from Example 1 is that the high-entropy alloy coating in step 2 is not present.

[0096] Comparative Example 2 The difference from Example 1 is that the photothermal layer, nanograss layer and hydrophobic layer in steps 3, 5 and 6 are not present.

[0097] Comparative Example 3 The difference from Example 1 is that the nanograss layer in step 5 is not included.

[0098] The differences between the composite coatings obtained in the above embodiments and comparative examples are shown in Table 1. The following performance tests were performed on the composite coatings obtained in all examples, and the test data are shown in Table 2.

[0099] 1. Antibacterial performance test method: After activation, the *E. coli* strain was added to liquid culture medium (3g beef extract, 10g peptone, 5g sodium chloride, 1000ml water) sterilized at 121℃ for 20 min, and incubated in a shaking incubator for 24 h. The cultured bacterial solution was then dropped onto the surface of a high-entropy alloy composite-coated sample and subjected to light / no light conditions for 10 min. The bacterial solution was then diluted with PBS buffer. The diluted bacterial solution was spread onto solid culture medium (3g beef extract, 10g peptone, 5g sodium chloride, 1000ml water, 15g agar powder) sterilized at 121℃ for 20 min, and incubated in a constant temperature incubator for 24 h. The colonies on the culture medium were counted, and the antibacterial rate was calculated using the following formula: R=(N b -N c ) / N b ×100%; Where R is the antibacterial rate, N b The number of colonies in the blank control group; N c This represents the colony count in the antibacterial sample group.

[0100] 2. Test methods for water contact angle and roll-off angle: The experimental environment was 23℃ and 45% relative humidity. The test liquid was deionized water with a volume of 5μL.

[0101] Water contact angle measurement: A droplet is slowly added to the surface of the composite coating. After the droplet stabilizes for about 30 seconds, the droplet profile is photographed using a contact angle measuring instrument, and the contact angle value is calculated by fitting. Five different positions are selected for measurement for each sample, and the average value is taken as the result.

[0102] Roll-off angle measurement: After the droplet is placed on the horizontally placed composite coating surface, the sample stage is slowly tilted and the minimum tilt angle at which the droplet begins to roll is recorded as the roll-off angle. Five different positions are selected for measurement for each sample, and the average value is taken as the result.

[0103] 3. Test method for thermal conductivity: The thermal conductivity of the composite coating was measured using the laser flare method (LFA). A short-pulse laser was used to heat the back side of the composite coating, while an infrared detector recorded the temperature rise curve of the front side. The thermal conductivity k was calculated, and the average thermal conductivity was calculated at three points for each sample. The formula is as follows: a = 0.1388 × L 2 / t 0.5 ; k=ɑ×ρ×c p ; Where α is the thermal diffusivity; L is the thickness; t 0.5 The time required for the front surface to heat up to half of its maximum value; ρ is the density; c p Specific heat capacity.

[0104] 4. Vibration abrasion resistance test method The composite coating was placed in a vibration abrasion tester, with a speed of 3000 RPM and a time of 1 hour. After removal, there were fewer than 4 locations where the coating had peeled off, and the area of ​​each peeling site was less than 1 mm². 2 That means OK; otherwise, it's NG.

[0105] 5. Salt spray test method The composite coating is placed in a salt spray test chamber with a 3.5% NaCl solution. The test temperature is set to 35℃, and the time is 24 hours. If no corrosion or discoloration is observed after removal, and the coating does not peel off after the 100-grid cross-cut test, it is considered OK; otherwise, it is NG (not acceptable).

[0106] Table 1 lists the differences between the composite coatings in the examples and comparative examples.

[0107] Table 2 Performance test data of each composite coating in the examples and comparative examples

[0108] As shown in Table 2, the high-entropy alloy layer endows the sample with excellent wear resistance and corrosion resistance, the photothermal layer provides excellent bactericidal properties, and the modified nanograss layer imparts superhydrophobicity. Simultaneously, the nanograss structure significantly reduces thermal conductivity, resulting in good thermal insulation. This composite film system, while possessing excellent mechanical properties and corrosion resistance, also exhibits photothermal antibacterial, superhydrophobic, antifouling, and thermal insulation functions, demonstrating promising application prospects in practical applications.

[0109] Although there is no photothermal layer in the composite coating of Example 15, the nanograss layer material is copper oxide. Copper ions have an antibacterial effect on bacteria, so it still has an antibacterial rate of 83%.

[0110] Finally, it should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the aforementioned element.

[0111] The above description, in conjunction with specific embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. Those skilled in the art to which this application pertains can make several simple deductions or substitutions without departing from the concept of this application.

Claims

1. A composite coating, characterized in that, The composite coating comprises: a hard layer and a nano-grass layer stacked together; The air content in the nanograss layer is 60% to 90%.

2. The composite coating according to claim 1, characterized in that, The nanograss layer includes multiple nanograsses, and the array of multiple nanograsses is arranged on the surface of the hard layer.

3. The composite coating according to claim 2, characterized in that, Meet at least one of the following: The average length of the nanograss in the nanograss layer is 200nm~1000nm; The ratio of the length of the nanograss to the diameter of its root in the nanograss layer is on average 2 to 10. The average curvature of the nanograss in the nanograss layer is 0°~60°; The average spacing between adjacent nanograss plants in the nanograss layer is 100nm~1000nm.

4. The composite coating according to claim 3, characterized in that, Meet at least one of the following: The average length of the nanograss in the nanograss layer is 400nm~700nm; The ratio of the length of the nanograss to the diameter of its root in the nanograss layer is on average 4 to 6. The average curvature of the nanograss in the nanograss layer is 0°~30°; The average spacing between adjacent nanograss plants in the nanograss layer is 400nm~700nm; The air content in the nanograss layer is 70% to 80%.

5. The composite coating according to claim 2, characterized in that, Meet at least one of the following: A photothermal layer is disposed between the hard layer and the nanograss layer, and a plurality of nanograss arrays are arranged on the surface of the photothermal layer; A hydrophobic layer is provided on the surface of the nanograss layer, and the nanograss layer is disposed between the hard layer and the hydrophobic layer; the hydrophobic layer is a monomolecular hydrophobic layer formed by modifying the surface of the nanograss layer with a modifier.

6. The composite coating according to claim 5, characterized in that, Meet at least one of the following: The thickness of the hard layer is 1μm~4μm; The thickness of the photothermal layer is 500nm~2000nm; The thickness of the nanograss layer is 100nm~1000nm; The hard layer material includes at least one of the following: high-entropy alloy layer, diamond-like carbon, and CrSiCN.

7. The composite coating according to claim 6, characterized in that, Meet at least one of the following: The material of the high-entropy alloy layer includes at least one of the following: WAlTiCrSi, CoCrFeNiCu, FeMnCoCr, TiZrHfVNb; The photothermal layer is made of at least one of the following materials: carbon-based photothermal materials, metal photothermal materials, semiconductor photothermal materials, and organic polymer photothermal materials; The material of the nanograss layer includes at least one of the following: copper oxide, zinc oxide, titanium dioxide, and polyvinyl alcohol; The modifier includes at least one of the following: fluorine-containing modifier, siloxane modifier, and silane modifier.

8. The composite coating according to claim 7, characterized in that, Meet at least one of the following: The carbon-based photothermal material includes at least one of the following: carbon nanotubes, graphene, and carbon black; The metal photothermal material includes at least one of the following: gold nanoparticles, TiN, and ZrN; The semiconductor photothermal material includes at least one of the following: TiO2, CuS, and Ti2O3; The organic polymer photothermal material includes at least one of the following: polyaniline, polypyrrole, and polydopamine.

9. The composite coating according to claim 7, characterized in that, Meet at least one of the following: The fluorinated modifier includes at least one of the following: perfluorodecyltrimethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltriethoxysilane, and perfluorododecyl mercaptan. The siloxane modifier is polydimethylsiloxane; The silane modifier is vinyltriethoxysilane.

10. The composite coating according to claim 9, characterized in that, The fluorine-containing modifier is perfluorodecyltrimethoxysilane.

11. The composite coating according to claim 5, characterized in that, Meet at least one of the following: The thermal conductivity of the composite coating is 0.127 W / mK to 0.173 W / mK; The antibacterial rate of the composite coating is greater than 99%; The composite coating has a water contact angle greater than 150° and a roll-off angle less than 10°.

12. A method for preparing a composite coating as described in any one of claims 1-11, characterized in that, The method includes: Deposit a nanograss precursor layer on the surface of a hard layer; The nanograss precursor layer is oxidized to form a nanograss layer on the surface of the hard layer, thus obtaining a composite coating.

13. The method according to claim 12, characterized in that, Depositing a nanograss precursor layer on a hard layer surface includes: depositing a nanograss precursor layer on a hard layer surface by physical vapor deposition.

14. The method according to claim 12, characterized in that, The parameters for the physical vapor deposition of the nanograss precursor layer include: temperature of 80℃~100℃, vacuum degree of 0.4Pa~0.6Pa, power supply of 4kW~6kW, and sputtering time of 250s~350s.

15. An application of a composite coating, characterized in that, The composite coating prepared by the method of any one of claims 1-11 or the composite coating prepared by any one of claims 12-14 is applied to at least one of the fields of electronics, medical, and aerospace.

Images