A multilayer anticorrosive coating and its preparation method and application

Abstract

The present application relates to the technical field of anticorrosive coating, in particular to a kind of laminated anticorrosive coating and its preparation method and application, including Al2O3 transition bottom layer prepared by atomic layer deposition technology and periodic laminated structure, Al2O3 transition bottom layer is deposited on the surface of substrate, periodic laminated structure is deposited on the upside of Al2O3 transition bottom layer, and periodic laminated structure includes repeatedly and alternately deposited doped modified Al2O3 layer, doped modified TiO2 layer and third component layer, and the third component layer is ZrO2 or SiO2.The present application improves coating self-healing ability and electrochemical stability by rare earth / non-metallic element doping, introduces ZrO2 or SiO2 third component to strengthen chemical stability, thermal shock resistance and insulation performance, and adapts to corrosion medium penetration characteristics by asymmetric laminated structure, significantly improves the long-term stability and protection performance of metal substrate in complex corrosion environment such as salt spray, water vapor, high temperature alternation and photoelectric coupling.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, and in particular to a multilayer anti-corrosion coating, its preparation method, and its application. Background Technology

[0002] Aluminum alloys, due to their low density, high strength, good thermal conductivity, excellent processing performance, and recyclability, have become key engineering materials widely used in coastal and marine environments, playing an irreplaceable role in marine equipment, optoelectronic module housings, and ship structures. However, although aluminum alloys can naturally form a passivating oxide film in air to achieve a certain level of corrosion resistance, this oxide film is easily destroyed when exposed to chloride-rich aquatic environments (such as salt spray and seawater), exposing the substrate to corrosive media, accelerating the corrosion process, and severely affecting its service life and structural integrity.

[0003] To improve the durability of aluminum alloys in harsh environments, researchers have developed various surface protective coating technologies, including chemical vapor deposition (CVD), physical vapor deposition (PVD), self-assembled monolayers, organic azole compound films, electrochemically deposited films, and polymer or inorganic polymer coatings. These technologies aim to construct a barrier layer that prevents moisture, dissolved oxygen, and corrosive ions from penetrating the metal interface, thereby inhibiting the occurrence and development of corrosion reactions. However, they still suffer from problems such as difficulty in controlling film thickness, unstable interfacial adhesion, poor structural uniformity, and insufficient coverage on complex morphological surfaces. The protective effect is particularly limited for nanoscale precision devices or microstructure regions.

[0004] Atomic layer deposition (ALD) technology, as an emerging vapor deposition method, has shown significant advantages in the field of anti-corrosion coatings due to its excellent thickness control, superior uniformity, and atomic-level construction precision. ALD technology achieves uniform and dense film deposition on substrate surfaces by introducing precursor gases in a stepwise and alternating manner, resulting in a self-limiting reaction on the substrate surface. It maintains good coverage even in structures with high aspect ratios or complex morphologies. Furthermore, ALD metal oxide films (such as Al2O3 and TiO2) possess excellent chemical stability, density, and dielectric properties, effectively blocking corrosive media penetration and exhibiting good insulation and interfacial bonding capabilities.

[0005] Although single-component ALD oxide films can significantly improve the corrosion resistance of metals under certain conditions, corrosion pathways may still form in extreme environments (such as high salt spray, alternating humid conditions, etc.) due to film defects, local cracking, or stress concentration. While the composite layer structure of Al2O3 and TiO2 can achieve synergistic protection through the high density of the former and the stability and oxidation resistance of the latter, it still has limitations such as the inability to self-repair after local damage, susceptibility of electrochemical stability to light exposure, insufficient thermal shock resistance, and limited insulation performance. Furthermore, the symmetrical layer structure has weak adaptability to the penetration behavior of corrosive media at different depths. Summary of the Invention

[0006] The purpose of this invention is to provide a multilayer anti-corrosion coating, its preparation method and application. By doping with rare earth / non-metallic elements, the coating's self-healing ability and electrochemical stability are improved. The introduction of ZrO2 or SiO2 as a third component enhances chemical stability, thermal shock resistance and insulation performance. Furthermore, the asymmetric multilayer structure is adapted to the penetration characteristics of corrosive media, significantly improving the long-term stability and protective performance of metal substrates in complex corrosive environments such as salt spray, water vapor, high temperature alternation and photoelectric coupling.

[0007] To achieve the above objectives, the present invention provides a multilayer anti-corrosion coating comprising an Al2O3 transition substrate prepared by atomic layer deposition (ALD) and a periodic multilayer structure. The Al2O3 transition substrate is deposited on the substrate surface, and the periodic multilayer structure is deposited on the upper side of the Al2O3 transition substrate. The periodic multilayer structure comprises repeatedly and alternately deposited doped modified Al2O3 layers, doped modified TiO2 layers, and a third component layer, wherein the third component layer is ZrO2 or SiO2.

[0008] Preferably, the periodic stacked structure is an asymmetric composite stacked structure, including an inner layer, an intermediate layer, and an outer layer. The inner layer, from the inside out, includes a 3-7 nm doped and modified Al2O3 layer, a 3-7 nm doped and modified TiO2 layer, and a 1-3 nm third component layer. The intermediate layer, from the inside out, includes a 2-4 nm doped and modified Al2O3 layer, a 5-9 nm doped and modified TiO2 layer, and a 2-4 nm third component layer. The outer layer, from the inside out, includes a 1-3 nm doped and modified Al2O3 layer, a 6-10 nm doped and modified TiO2 layer, and a 4-6 nm third component layer.

[0009] Preferably, the Al2O3 transition layer is obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce aluminum precursor and oxidant, and then depositing it through multiple cycles.

[0010] Preferably, the doped and modified Al2O3 layer is obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce aluminum precursor and oxidant, and performing multiple cyclic depositions, inserting non-metallic element dopants and reacting with the oxidant during the cycle.

[0011] Preferably, the aluminum precursor is selected from at least one of trimethylaluminum, triethylaluminum, and triisopropylaluminum, the oxidant is oxygen, and the non-metallic element dopant is an F-containing precursor or an N gas source. The F-containing precursor is selected from at least one of aluminum trifluoroethoxide, aluminum trifluoroacetate, and titanium trifluoroacetate, and the N gas source is selected from at least one of ammonia, hydrazine, and tert-butylamine.

[0012] Preferably, the doped and modified TiO2 layer is obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce titanium precursor and oxidant in multiple cycles of deposition, and inserting rare earth element precursors and oxidant into the reaction cycle during the cycle.

[0013] Preferably, the titanium precursor is selected from at least one of titanium tetrachloride, titanium tetraisopropoxy, and titanium trifluoroacetate, and the rare earth element precursor is cerium hexafluoroacetylacetonate or yttrium tris(2,2,6,6-tetramethyl-3,5-heptadecanoate).

[0014] Preferably, the third layer is obtained by atomic layer deposition, in which argon gas is used as the carrier gas and alternately introduced into the zirconium precursor or silicon precursor and oxidant, and the deposition is carried out in multiple cycles; the zirconium precursor is tetra(ethoxy)zirconium and the silicon precursor is triethoxysilane.

[0015] The above-mentioned method for preparing a multilayer anti-corrosion coating includes the following steps:

[0016] S1. After grinding, polishing and ultrasonic cleaning of the substrate surface, place it in the plasma equipment reaction chamber and bombard the substrate surface with oxygen-containing plasma to obtain the substrate to be coated.

[0017] S2. Place the substrate to be coated into the plasma equipment reaction chamber, set the chamber temperature to 100-130℃, the argon carrier gas flow rate to 1500-2500 sccm, the purging time to 8-15s, the aluminum precursor flow rate to 900-950 sccm, the introduction time to 1-3s, and the oxidant flow rate to 800-1200 sccm, the introduction time to 1-3s. Algon gas, aluminum precursor and oxidant are alternately introduced, and Al2O3 transition underlayer is obtained by multiple cycles of deposition.

[0018] S3. Set the flow rate of the non-metallic element dopant to 900-950 sccm and the introduction time to 1-3s. Continue to circulate argon, aluminum precursor and oxidant on the Al2O3 transition layer and perform multiple cyclic depositions. During the cyclic process, insert the reaction cycle of the non-metallic element dopant and oxidant. After the deposition is completed, the doped modified Al2O3 layer is obtained.

[0019] S4. Set the flow rate of titanium precursor to 800-900 sccm and the inlet time to 1-3 s. Set the flow rate of rare earth element precursor to 800-900 sccm and the inlet time to 1-3 s. Cyclicly introduce argon, titanium precursor and oxidant into the doped and modified Al2O3 layer and perform multiple cyclic depositions. Insert the reaction cycle of rare earth element precursor and oxidant during the cycle. After the deposition is completed, the doped and modified TiO2 layer is obtained.

[0020] S5. Argon, zirconium precursor or silicon precursor and oxidant are circulated into the doped and modified TiO2 layer. The flow rate of zirconium precursor or silicon precursor is 800-1000 sccm and the circulation time is 1-4s. The third layer is obtained by repeated cyclic deposition.

[0021] S6. Repeat steps S3 to S5 to deposit a periodic stacked structure, finally obtaining a stacked anti-corrosion coating.

[0022] The above-mentioned layered anti-corrosion coating is applied to the surface coating of aluminum alloy components in marine equipment, optoelectronic equipment, precision electronics, and high-temperature working conditions.

[0023] Therefore, the present invention, employing the above-mentioned multilayer anti-corrosion coating, its preparation method, and its application, has the following beneficial effects:

[0024] (1) The present invention first deposits a 10 nm Al2O3 transition layer on the surface of an aluminum alloy substrate to increase the nucleation density by using atomic layer deposition technology, and then constructs a periodic stacked structure by alternating deposition of doped Al2O3, doped TiO2, ZrO2 or SiO2 layers to form multiple barriers, which can significantly delay the penetration path of corrosive media, and at the same time has good shielding effect and interface stability.

[0025] (2) This invention achieves breakthroughs in multiple properties such as self-healing, electrochemical stability, thermal shock resistance, and high insulation of the coating by doping with rare earth and non-metallic elements and introducing ZrO2 or SiO2 as a third component. It is suitable for high temperature, optoelectronic, and precision electronics scenarios and can be used in marine equipment, optoelectronic equipment, precision electronics, high temperature working conditions and other fields.

[0026] (3) The asymmetric layered structure of the present invention achieves functional zoning based on the permeation characteristics of corrosive media from the surface to the inside. The inner layer focuses on dense barrier and interface optimization, while the outer layer focuses on weather resistance and wear resistance, thus solving the problem of insufficient protection of traditional symmetrical structures.

[0027] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0029] This invention provides a multilayer anti-corrosion coating, comprising an Al2O3 transition substrate prepared by atomic layer deposition (ALD) and a periodic multilayer structure. The Al2O3 transition substrate is deposited on the substrate surface, and the periodic multilayer structure is deposited on the upper side of the Al2O3 transition substrate. The periodic multilayer structure includes repeatedly and alternately deposited doped modified Al2O3 layers, doped modified TiO2 layers, and a third component layer, wherein the third component layer is ZrO2 or SiO2.

[0030] In some specific embodiments of the present invention, the thickness of the Al2O3 transition layer is 10 nm. The Al2O3 transition layer can effectively improve the nucleation density of subsequent films and improve the surface morphology of the film, thereby obtaining a more uniform and dense overall film system, providing an excellent interface basis for subsequent stacked structure deposition.

[0031] The alternating deposition layered structure in this invention not only possesses excellent density and surface smoothness, but also exhibits significant protective capabilities after long-term immersion in corrosive media, thereby achieving efficient and durable anti-corrosion protection for metal substrates.

[0032] The third layer of this invention is ZrO2 or SiO2. ZrO2 has excellent chemical inertness and is not prone to chemical reaction in strong acid, strong alkali and high temperature environments. Moreover, its coefficient of thermal expansion is closer to that of aluminum alloy substrate, which can alleviate the internal stress of the coating caused by temperature changes and reduce the risk of thermal shock cracking. At the same time, it has high hardness, which can improve the wear resistance of the coating surface and avoid the corrosion hazards caused by mechanical damage. It is suitable for scenarios with alternating high temperatures and easy mechanical friction.

[0033] SiO2 has excellent insulation properties, which can effectively block electron transfer between the metal substrate and the external environment and inhibit electrochemical corrosion reactions. Moreover, its molecules can easily form stable Si-OM (M is a metal atom) chemical bonds with hydroxyl groups on the metal surface, which enhances the interfacial bonding between the coating and the substrate. Its dense silicon-oxygen tetrahedral structure can further reduce the corrosion ion penetration rate, making it suitable for electronic packaging scenarios with high insulation performance requirements.

[0034] Preferably, the substrate is an aluminum alloy substrate, the doped and modified Al2O3 layer is modified by doping with non-metallic elements, and the doped and modified TiO2 layer is modified by doping with rare earth elements.

[0035] In some specific embodiments of the present invention, the non-metallic element is N or F; the rare earth element is Ce or Y.

[0036] In this invention, Al2O3 is doped with non-metallic elements N or F to form stable Al-N and Ti-F bonds with Al, thereby enhancing the interfacial bonding between the coating and the substrate. At the same time, it reduces the number of hydroxyl groups on the coating surface, improves the insulation performance of the Al2O3 layer, reduces the electrolyte adsorption capacity, and enhances the hydrophobicity and chemical inertness of the coating.

[0037] By doping TiO2 with rare earth elements Ce or Y, Ce and Y can react with OH in the electrolyte in a corrosive environment. - O 2- They combine to form dense passivation films such as Ce(OH)3 and Y2O3; and their ionic radii are similar to those of TiO2 and Al2O3 lattice ions, making them easy to incorporate into the coating lattice through the ALD process to reduce lattice defects. When the coating develops microcracks or localized damage, Ce and Y ions migrate to the damaged area and undergo a chemical reaction to form a passivation film, blocking corrosion channels and achieving self-healing. At the same time, they can also inhibit electron transfer within the coating and reduce the electrochemical corrosion rate.

[0038] Preferably, the periodic stacked structure is an asymmetric composite stacked structure, including an inner layer, an intermediate layer, and an outer layer. The inner layer, from the inside out, includes a 3-7 nm doped and modified Al2O3 layer, a 3-7 nm doped and modified TiO2 layer, and a 1-3 nm third component layer. The intermediate layer, from the inside out, includes a 2-4 nm doped and modified Al2O3 layer, a 5-9 nm doped and modified TiO2 layer, and a 2-4 nm third component layer. The outer layer, from the inside out, includes a 1-3 nm doped and modified Al2O3 layer, a 6-10 nm doped and modified TiO2 layer, and a 4-6 nm third component layer.

[0039] The periodic stacked structure of this invention features a gradually thinning of the doped and modified Al2O3 layer from the inside out, a gradually thickening of the doped and modified TiO2 layer, and a continuous increase in the thickness of the third component layer. This closely adapts to the characteristics of the corrosive medium gradually penetrating from the surface to the inside, the outer layer being more susceptible to environmental impact, and the inner layer needing to ensure interface stability, ultimately achieving synergistic optimization of multi-dimensional protective performance.

[0040] Preferably, the Al2O3 transition layer is obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce aluminum precursor and oxidant, and then depositing it through multiple cycles.

[0041] Preferably, the doped and modified Al2O3 layer is obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce aluminum precursor and oxidant, and performing multiple cyclic depositions, inserting non-metallic element dopants and reacting with the oxidant during the cycle.

[0042] Preferably, the aluminum precursor is selected from at least one of trimethylaluminum, triethylaluminum, and triisopropylaluminum, the oxidant is oxygen, and the non-metallic element dopant is an F-containing precursor or an N gas source. The F-containing precursor is selected from at least one of aluminum trifluoroethoxide, aluminum trifluoroacetate, and titanium trifluoroacetate, and the N gas source is selected from at least one of ammonia, hydrazine, and tert-butylamine.

[0043] Preferably, the doped and modified TiO2 layer is obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce titanium precursor and oxidant in multiple cycles of deposition, and inserting rare earth element precursors and oxidant into the reaction cycle during the cycle.

[0044] Preferably, the titanium precursor is selected from at least one of titanium tetrachloride, titanium tetraisopropoxy, and titanium trifluoroacetate, and the rare earth element precursor is cerium hexafluoroacetylacetonate or yttrium tris(2,2,6,6-tetramethyl-3,5-heptadecanoate).

[0045] Preferably, the third layer is obtained by atomic layer deposition, in which argon gas is used as the carrier gas and alternately introduced into the zirconium precursor or silicon precursor and oxidant, and the deposition is carried out in multiple cycles; the zirconium precursor is tetra(ethoxy)zirconium and the silicon precursor is triethoxysilane.

[0046] The above-mentioned method for preparing a multilayer anti-corrosion coating includes the following steps:

[0047] S1. After grinding, polishing and ultrasonic cleaning of the substrate surface, place it in the plasma equipment reaction chamber and bombard the substrate surface with oxygen-containing plasma to obtain the substrate to be coated.

[0048] S2. Place the substrate to be coated into the plasma equipment reaction chamber, set the chamber temperature to 100-130℃, the argon carrier gas flow rate to 1500-2500 sccm, the purging time to 8-15s, the aluminum precursor flow rate to 900-950 sccm, the introduction time to 1-3s, and the oxidant flow rate to 800-1200 sccm, the introduction time to 1-3s. Algon gas, aluminum precursor and oxidant are alternately introduced, and Al2O3 transition underlayer is obtained by multiple cycles of deposition.

[0049] S3. Set the flow rate of the non-metallic element dopant to 900-950 sccm and the introduction time to 1-3s. Continue to circulate argon, aluminum precursor and oxidant on the Al2O3 transition layer and perform multiple cyclic depositions. During the cyclic process, insert the reaction cycle of the non-metallic element dopant and oxidant. After the deposition is completed, the doped modified Al2O3 layer is obtained.

[0050] S4. Set the flow rate of titanium precursor to 800-900 sccm and the inlet time to 1-3 s. Set the flow rate of rare earth element precursor to 800-900 sccm and the inlet time to 1-3 s. Cyclicly introduce argon, titanium precursor and oxidant into the doped and modified Al2O3 layer and perform multiple cyclic depositions. Insert the reaction cycle of rare earth element precursor and oxidant during the cycle. After the deposition is completed, the doped and modified TiO2 layer is obtained.

[0051] S5. Argon, zirconium precursor or silicon precursor and oxidant are circulated into the doped and modified TiO2 layer. The flow rate of zirconium precursor or silicon precursor is 800-1000 sccm and the circulation time is 1-4s. The third layer is obtained by repeated cyclic deposition.

[0052] S6. Repeat steps S3 to S5 to deposit a periodic stacked structure, finally obtaining a stacked anti-corrosion coating.

[0053] In some specific embodiments of the present invention, in S1, grinding and polishing is to use sandpaper or a polishing machine to grind and polish the metal surface to remove the surface oxide layer and scratches until the surface roughness Ra ≤ 0.2 nm.

[0054] In some specific embodiments of the present invention, in S1, ultrasonic cleaning involves sequentially cleaning with deionized water, ethanol, and acetone under ultrasonic conditions of 400-600W for 3-8 minutes each, followed by drying at 80-90℃ for 3-8 minutes to remove surface dust, oil, and organic residues.

[0055] In some specific embodiments of the present invention, in S1, the plasma equipment reaction chamber is purged with an inert gas flow rate of 1500-2200 sccm for 40-80 seconds at a temperature of 120-180°C to remove residual impurities; then, it is bombarded with oxygen-containing plasma at a power of 1200-1600W for 50-70 seconds, and the bombardment is repeated 8-12 times; residual hydroxyl groups and adsorbed impurities on the substrate surface are removed by plasma etching, while active groups are introduced to improve the adhesion between the subsequent coating and the substrate. The inert gas is at least one of argon, helium, or neon.

[0056] In some specific embodiments of the present invention, in S2, the chamber is evacuated to ≤50Pa, and after standing for 30 minutes to reach thermal equilibrium, an aluminum precursor is introduced, and the cycle is repeated 100 times to obtain an Al2O3 transition underlayer with a thickness of 10nm.

[0057] The aforementioned multilayer anti-corrosion coatings are applied to the surface coatings of aluminum alloy components in marine equipment, optoelectronic equipment, precision electronics, and high-temperature environments.

[0058] Example 1

[0059] This invention provides a multilayer anti-corrosion coating, comprising a 10nm Al2O3 transition substrate and a periodic multilayer structure deposited on the upper side of the Al2O3 transition substrate. The periodic multilayer structure is an asymmetric composite multilayer structure, comprising an inner layer, an intermediate layer and an outer layer. The inner layer, intermediate layer and outer layer each comprise, from the inside to the outside, an F-doped modified Al2O3 layer, a Ce-doped modified TiO2 layer and a third component layer ZrO2. The parameters of each layer are shown in Table 1 below.

[0060] Table 1. Thickness of each layer in the periodic laminated structure of Example 1

[0061] ;

[0062] Example 2

[0063] This invention provides a multilayer anti-corrosion coating, comprising a 10nm Al2O3 transition substrate and a periodic multilayer structure deposited on the Al2O3 transition substrate. The periodic multilayer structure is an asymmetric composite multilayer structure, comprising an inner layer, an intermediate layer and an outer layer. The inner layer, intermediate layer and outer layer each comprise, from the inside to the outside, an F-doped modified Al2O3 layer, a Ce-doped modified TiO2 layer and a third component layer ZrO2. The parameters of each layer are shown in Table 2 below.

[0064] Table 2. Thickness of each layer in the periodic laminated structure of Example 2

[0065] ;

[0066] Example 3

[0067] This invention provides a multilayer anti-corrosion coating, comprising a 10nm Al2O3 transition substrate and a periodic multilayer structure deposited on the Al2O3 transition substrate. The periodic multilayer structure is an asymmetric composite multilayer structure, comprising an inner layer, an intermediate layer and an outer layer. The inner layer, intermediate layer and outer layer each comprise, from the inside to the outside, an F-doped modified Al2O3 layer, a Ce-doped modified TiO2 layer and a third component layer ZrO2. The parameters of each layer are shown in Table 3 below.

[0068] Table 3. Thickness of each layer in the periodic laminated structure of Example 3

[0069] ;

[0070] Example 4

[0071] Example 2 describes a method for preparing a multilayer anti-corrosion coating, which includes the following steps:

[0072] Substrate Pretreatment (S1): A 6061 aluminum alloy sheet (50mm×50mm×2mm) was selected as the substrate. It was polished sequentially using 400-grit, 800-grit, and 1200-grit sandpaper to remove surface oxide scale and scratches until the surface roughness Ra ≤ 0.2nm. Then, under ultrasonic conditions at 500W power, it was sequentially cleaned with deionized water, anhydrous ethanol, and acetone for 5 minutes each, followed by drying in an 85℃ forced-air drying oven for 5 minutes. The substrate was then placed in the reaction chamber of a plasma-enhanced ALD (Alternating Current Laser) device, heated to 150℃, purged with 2000 sccm of argon gas for 60 seconds, and the plasma power was set to 1400W. Oxygen plasma (flow rate 500 sccm) was introduced to generate oxygen plasma, which bombarded the substrate surface for 60 seconds. This operation was repeated 10 times to obtain the substrate to be coated.

[0073] Al2O3 transition underlayer deposition (S2): The substrate to be coated was placed in the plasma reaction chamber, the chamber temperature was set to 110℃, and the vacuum was evacuated to 10 Pa. The substrate was allowed to stand for 30 min to reach thermal equilibrium. Argon was used as the carrier gas, and the aluminum precursor and oxidant were alternately introduced sequentially. The argon carrier gas flow rate was set to 2000 sccm, and the purging time was 10 s. The aluminum precursor used was trimethylaluminum (TMA, purity 99.999%), with a flow rate of 920 sccm and a purging time of 1.5 s. The oxidant was oxygen (purity 99.999%), with a flow rate of 1000 sccm and a purging time of 1.2 s. A single cycle consisted of: TMA introduction - argon purging - oxygen introduction - argon purging, for a total of 100 cycles, resulting in an Al2O3 transition underlayer with a thickness of approximately 10 nm.

[0074] Inner layer deposition (S3-S5, first cycle S3-S5):

[0075] Deposition of doped modified Al2O3 layer (S3): Based on the Al2O3 transition layer, the chamber temperature, vacuum level and carrier gas parameters are kept constant; the cycling parameters of TMA and oxygen are the same as in S2. Every 30 TMA-oxygen cycles, an F-containing precursor (aluminum trifluoroethoxide, purity 99.99%)-oxygen reaction cycle is inserted (aluminum trifluoroethoxide flow rate 900 sccm, inlet time 1.1s; oxygen flow rate 1000 sccm, inlet time 1.2s); a total of 50 cycles (including 1 F-doping cycle) are performed to deposit a modified Al2O3 layer with a thickness of about 5 nm and an F doping concentration of 1.5%.

[0076] Deposition of the doped and modified TiO2 layer (S4): Titanium tetrachloride (TiCl4, purity 99.999%) was used as the titanium precursor, with a flow rate of 850 sccm and a passage time of 2.1 s; oxygen flow rate was 1000 sccm and a passage time of 1.8 s; the rare earth element precursor was cerium hexafluoroacetylacetone (Ce(hfac)3, purity 99.99%), with a flow rate of 860 sccm and a passage time of 1.3 s. Deposition process: TiCl4 was introduced... 4- Argon purging-oxygen introduction-argon purging is the basic cycle, with Ce(hfac) inserted once every 20 basic cycles. 3- Oxygen reaction cycle (Ce(hfac) introduced) 3- Argon purging-oxygen introduction-argon purging); a total of 55 cycles (including 2 Ce doping cycles) were performed to deposit a modified TiO2 layer with a thickness of about 5 nm and a Ce doping concentration of 1%.

[0077] The third ZrO2 layer (S5) was deposited using tetra(ethoxy)zirconium (Zr(OC2H5)4, purity 99.99%) as the zirconium precursor, with a flow rate of 880 sccm and a purging time of 1.5 s; the oxygen flow rate was 1000 sccm and the purging time was 1.8 s; the chamber temperature was maintained at 120℃ (slightly higher than the baseline temperature to enhance the reactivity of the Zr precursor), and the argon carrier gas and purging parameters remained unchanged; the process was repeated 15 times to deposit a ZrO2 layer with a thickness of approximately 2 nm.

[0078] Intermediate layer deposition (second cycle S3-S5)

[0079] Depositing a doped Al2O3 layer (S3): The cycling parameters are the same as those for the inner modified Al2O3 layer. A total of 30 cycles are performed (including 1 F doping cycle) to deposit an Al2O3 layer with a thickness of about 3 nm and an F doping concentration of 1.2%, which serves as a transition between the intermediate layer and the inner layer and maintains the overall compactness of the coating.

[0080] Depositing a doped modified TiO2 layer (S4): The basic cycling parameters of TiCl4 and oxygen remain unchanged. One Ce(hfac)3-oxygen cycle is inserted every 20 basic cycles, for a total of 77 cycles (including 3 Ce doping cycles). A TiO2 layer with a thickness of about 7 nm and a Ce doping concentration of 1.1% is deposited to enhance the synergistic ability of the intermediate layer in terms of self-healing and corrosion resistance.

[0081] The third component layer (S5) of ZrO2 was deposited: the cycling parameters of Zr(OC2H5)4 and oxygen remained unchanged, and a total of 22 cycles were performed to deposit a ZrO2 layer with a thickness of about 3 nm. This enhanced the thermal shock resistance and chemical stability of the intermediate layer and helped to cope with the mid-term penetration of corrosive media.

[0082] Surface layer deposition (third cycle S3-S5)

[0083] Depositing a doped modified Al2O3 layer (S3): The cycling parameters are the same as those for the inner modified Al2O3 layer, and the layer is cycled 20 times (including one F doping cycle, which reduces the proportion of outer Al2O3 and increases the content of TiO2 and ZrO2). An Al2O3 layer with a thickness of about 2 nm and an F doping concentration of 1.2% is deposited as a connection between the outer layer and the middle layer.

[0084] Deposition of doped and modified TiO2 layer (S4): The basic cycling parameters of TiCl4 and oxygen remain unchanged, and Ce(hfac) is inserted once every 15 basic cycles. 3- The oxygen cycle was repeated 126 times (including 8 Ce-doped cycles) to deposit a TiO2 layer with a thickness of approximately 8 nm and a Ce doping concentration of 1.8%. The higher TiO2 content improves the coating's weather resistance (resistance to UV aging), and the higher Y doping concentration enhances the self-healing efficiency after surface damage.

[0085] The third ZrO2 layer (S5) was deposited: Zr(OC2H5)4 and oxygen were cycled 35 times with constant parameters, resulting in a ZrO2 layer with a thickness of approximately 5 nm. The increased thickness of the outer ZrO2 layer, with its high hardness (Mohs hardness of approximately 8.5), improves the wear resistance of the coating surface, reduces the risk of corrosion caused by mechanical scratches, and enhances thermal shock resistance, adapting to the diurnal temperature variations in high-temperature marine conditions.

[0086] The preparation methods of the multilayer anti-corrosion coating in Examples 1 and 3 are the same as those in Example 2, except that the number of cycles is set according to different deposition thicknesses.

[0087] Example 5

[0088] This invention provides a multilayer anti-corrosion coating, comprising a 10nm Al2O3 transition substrate and a periodic multilayer structure deposited on the upper side of the Al2O3 transition substrate. The periodic multilayer structure is an asymmetric composite multilayer structure, comprising an inner layer, an intermediate layer and an outer layer. The inner layer, intermediate layer and outer layer each comprise, from the inside to the outside, an N-doped modified Al2O3 layer, a Y-doped modified TiO2 layer and a third component layer SiO2. The parameters of each layer are shown in Table 4 below.

[0089] Table 4. Thickness of each layer in the periodic stacked structure of Example 4

[0090] ;

[0091] Example 6

[0092] The difference from Example 4 is that in the deposited doped Al2O3 layer (S3), the F-containing precursor is replaced with an N gas source; in the deposited doped TiO2 layer (S4), the rare earth element precursor cerium hexafluoroacetylacetonate is replaced with tris(2,2,6,6-tetramethyl-3,5-heptadecanoic acid)yttrium (Y(thd)3, purity 99.99%); and in the deposited ZrO2 third component layer (S5), the zirconium precursor tetra(ethoxy)zirconium is replaced with triethoxysilane (Si(C2H5O)3H, purity 99.99%). All other aspects are the same as in Example 4.

[0093] Comparative Example 1

[0094] Compared with Example 2, there is no third component layer. It includes a 10nm Al2O3 transition bottom layer and a periodic stacked structure deposited on the top side of the Al2O3 transition bottom layer. The periodic stacked structure is an asymmetric composite stacked structure, including an inner layer, an intermediate layer and an outer layer. The inner layer, intermediate layer and outer layer all include an F-doped modified Al2O3 layer and a Ce-doped modified TiO2 layer from the inside to the outside. The parameters of each layer are shown in Table 5 below.

[0095] Table 5. Thickness of each layer in the periodic laminated structure of Comparative Example 1

[0096] ;

[0097] Comparative Example 2

[0098] Compared to Example 2, it has a symmetrical stacked structure, including a 10nm Al2O3 transition bottom layer and a periodic stacked structure deposited on the top side of the Al2O3 transition bottom layer. The periodic stacked structure includes three layers with the same structure. Each layer includes, from the inside to the outside, a 3nm F-doped modified Al2O3 layer, a 5nm Ce-doped modified TiO2 layer, and a 3nm third component layer ZrO2.

[0099] Comparative Example 3

[0100] Compared with Example 2, the undoped modification includes a 10nm Al2O3 transition substrate and a periodic stacked structure deposited on the Al2O3 transition substrate. The periodic stacked structure is an asymmetric composite stacked structure, including an inner layer, an intermediate layer and an outer layer. The inner layer, intermediate layer and outer layer each include an Al2O3 layer, a TiO2 layer and a third component layer ZrO2 from the inside to the outside. The parameters of each layer are shown in Table 6 below.

[0101] Table 6. Thickness of each layer in the periodic laminated structure of Comparative Example 3

[0102] ;

[0103] Comparative Example 4

[0104] Compared with Example 2, only Al2O3 layer and TiO2 layer are used, including a 10nm Al2O3 transition bottom layer and a periodic stacked structure deposited on the upper side of the Al2O3 transition bottom layer. The periodic stacked structure includes three layers with the same structure, each layer including a 3nm Al2O3 layer and a 7nm TiO2 layer from the inside to the outside.

[0105] The anti-corrosion coatings prepared in Examples 2 and 5, and Comparative Examples 1-4 were subjected to performance tests. The test items and standards are as follows:

[0106] Basic corrosion resistance: Referring to GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", a neutral salt spray test was conducted in a 3.5wt% NaCl solution (pH=7.0, temperature 35℃). After immersion for 21 days, electrochemical impedance spectroscopy (EIS, frequency range 10) was measured using an electrochemical workstation (CHI660E). -2 ~10 5 Corrosion current density (Hz) was calculated by comparing the Tafel polarization curves with the Hz values. The results are shown in Table 7.

[0107] Table 7. Experimental data of the anti-corrosion coatings of Example 2 and Comparative Examples 1-4 after 21-day salt spray test.

[0108] ;

[0109] Thermal shock resistance: Referring to GB / T9989.2-2015 "Determination of Chemical Corrosion Resistance of Enamel", 50 cycles of thermal cycling were performed between -40℃ (low temperature chamber) and 120℃ (high temperature chamber) (each extreme temperature held for 30 min, transfer time ≤10 s). After cycling, EIS and surface morphology (SEM, Zeiss Sigma 300) were measured. The results are shown in Table 8.

[0110] Table 8. Experimental data of the anti-corrosion coatings of Example 2 and Comparative Examples 1-4 after 50 cycles of thermal cycling.

[0111] ;

[0112] Self-healing performance: Artificial scratches with a width of 8μm±1μm were created on the coating surface using a blade. The surface was then immersed in a 3.5wt% NaCl solution for 21 days. The healing of the scratches was observed by SEM, and the EIS change rate of the scratched area was tested (Δ|Z|=(initial|Z|-21 days|Z|) / initial|Z|×100%). The results are shown in Table 9.

[0113] Table 9. Experimental data of anti-corrosion coatings from Examples 2 and Comparative Examples 1-4 after immersion in scratches for 21 days.

[0114] ;

[0115] Insulation performance: Referring to GB / T1410-2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", the volume resistivity of the coating was tested using an insulation resistance tester (TH2683). The insulation resistance retention rate (η = 72h insulation resistance / initial insulation resistance × 100%) was tested after placing the sample in an environment of 50℃ and 60%RH for 72 hours. The results are shown in Table 10.

[0116] Table 10 Insulation performance data of the anti-corrosion coatings of Example 5, Comparative Example 1, and Comparative Examples 3-4

[0117] ;

[0118] As shown in Tables 7 to 10, compared with Comparative Example 1, after introducing ZrO2, the |Z| value of the 21-day salt spray test was significantly improved, and the corrosion current density was significantly reduced, indicating that the high chemical inertness of ZrO2 prolonged the penetration path of the corrosive medium; after 50 thermal cycles, the impedance reduction rate decreased from 45% to 12%, and the critical load change rate was optimized from -32% to -8%, verifying that ZrO2, by matching the thermal expansion coefficient of aluminum alloy (ZrO2: 10×10), effectively reduced the corrosion current density. -6 / ℃, 6061 aluminum alloy: 23.6×10 -6 / ℃) alleviated thermal stress and reduced the risk of cracking. Comparative Example 5 and Comparative Example 1: SiO2 reduced the volume resistivity from 2.3×10 13 Ω·cm increased to 1.5×10 16 The insulation resistance retention rate increased from 68% to 92% in Ω·cm, proving that the silicon-oxygen tetrahedral structure of SiO2 can effectively block electron transfer and meet the insulation requirements of precision electronics.

[0119] Comparing Example 2 with Comparative Example 2: The asymmetric periodic layered structure significantly improved the |Z| value and significantly reduced the corrosion current density in the 21-day salt spray test; after thermal cycling, the crack width decreased from 0.8~1.5μm to ≤0.5μm. This is because the inner layer of thick Al2O3 in Example 2 of this invention enhances the interface density, while the outer layer of thick ZrO2 strengthens the surface damage resistance, adapting to the characteristics of corrosive media penetrating from the surface to the interior and the outer layer being more impacted, thus solving the problem of uneven protection between the inner and outer layers of the symmetrical structure.

[0120] Comparative Example 2 and Comparative Example 3: F doping of Al2O3 (forming Al-F bonds) reduces surface hydroxyl groups, Ce doping of TiO2 (generating Ce(OH)3 passivation film) increases the scratch healing area ratio from 15% to 92%, and reduces the EIS change rate from 82% to 23%; the 21-day salt spray test |Z| value increases by 3.8 times, proving that doping can synergistically improve corrosion resistance through self-healing and densification.

[0121] Comparative Example 5 and Comparative Example 3: N-doped Al₂O₃ (forming Al-N bonds) reduces the volume resistivity from 8.7 × 10⁻⁶ to 8.7 × 10⁻⁶. 12 Ω·cm increased to 1.5×10 16 The breakdown voltage increased from 2.8kV to 8.5kV, Ω·cm, indicating that N doping enhances photoelectric stability and insulation.

[0122] This invention prepares an asymmetric multilayer coating by doping and modifying Al2O3 and TiO2 in combination with a third component. The coating is significantly superior to comparative examples 1-4 in terms of basic corrosion resistance, thermal shock resistance, self-healing, and insulation performance. It can effectively solve the corrosion problem of aluminum alloys in complex environments such as high salt spray, alternating high temperature, and photoelectric coupling, and has the potential for industrial application.

[0123] 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 multilayer anti-corrosion coating, characterized in that: It includes an Al2O3 transition underlayer and a periodic stacked structure prepared by atomic layer deposition technology. The Al2O3 transition underlayer is deposited on the substrate surface, and the periodic stacked structure is deposited on the upper side of the Al2O3 transition underlayer. The periodic stacked structure includes a doped modified Al2O3 layer, a doped modified TiO2 layer and a third component layer that are repeatedly deposited alternately. The third component layer is ZrO2 or SiO2. The periodic stacked structure is an asymmetric composite stacked structure, including an inner layer, an intermediate layer, and an outer layer. The inner layer, from the inside out, consists of a 3-7 nm doped and modified Al2O3 layer, a 3-7 nm doped and modified TiO2 layer, and a 1-3 nm third component layer. The intermediate layer, from the inside out, consists of a 2-4 nm doped and modified Al2O3 layer, a 5-9 nm doped and modified TiO2 layer, and a 2-4 nm third component layer. The outer layer, from the inside out, consists of a 1-3 nm doped and modified Al2O3 layer, a 6-10 nm doped and modified TiO2 layer, and a 4-6 nm third component layer. The doped Al2O3 layer was obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce aluminum precursor and oxidant, and performing multiple cyclic depositions. During the cycle, non-metallic element dopants were inserted to react with the oxidant. The non-metallic element dopants were F-containing precursors or N gas sources. The doped and modified TiO2 layer was obtained by atomic layer deposition technology, using argon as the carrier gas to alternately introduce titanium precursor and oxidant in multiple cycles of deposition, and inserting rare earth element precursors and oxidant reactions in the cycle. The rare earth element precursors were cerium hexafluoroacetylacetone or tris(2,2,6,6-tetramethyl-3,5-heptadecanoic acid)yttrium.

2. The multilayer anti-corrosion coating according to claim 1, characterized in that: The Al2O3 transition layer was obtained by atomic layer deposition (ALD) using argon as the carrier gas, which was alternately introduced into the aluminum precursor and oxidant, and deposited through multiple cycles.

3. The multilayer anti-corrosion coating according to claim 1, characterized in that: The aluminum precursor is selected from at least one of trimethylaluminum, triethylaluminum, and triisopropylaluminum; the oxidant is oxygen; the F-containing precursor is selected from at least one of aluminum trifluoroethoxide, aluminum trifluoroacetate, and titanium trifluoroacetate; and the N gas source is selected from at least one of ammonia, hydrazine, and tert-butylamine.

4. The multilayer anti-corrosion coating according to claim 1, characterized in that: The titanium precursor is selected from at least one of titanium tetrachloride, titanium tetraisopropoxy, and titanium trifluoroacetate.

5. The multilayer anti-corrosion coating according to claim 1, characterized in that: The third layer was obtained by atomic layer deposition, using argon as the carrier gas and alternatingly introducing zirconium or silicon precursors and oxidants, through multiple cycles of deposition; the zirconium precursor was tetra(ethoxy)zirconium, and the silicon precursor was triethoxysilane.

6. A method for preparing a multilayer anti-corrosion coating as described in any one of claims 1-5, characterized in that: Includes the following steps: S1. After grinding, polishing and ultrasonic cleaning of the substrate surface, place it in the plasma equipment reaction chamber and bombard the substrate surface with oxygen-containing plasma to obtain the substrate to be coated. S2. Place the substrate to be coated into the plasma equipment reaction chamber, set the chamber temperature to 100-130℃, the argon carrier gas flow rate to 1500-2500 sccm, the purging time to 8-15s, the aluminum precursor flow rate to 900-950 sccm, the introduction time to 1-3s, and the oxidant flow rate to 800-1200 sccm, the introduction time to 1-3s. Algon gas, aluminum precursor and oxidant are alternately introduced, and Al2O3 transition underlayer is obtained by multiple cycles of deposition. S3. Set the flow rate of the non-metallic element dopant to 900-950 sccm and the introduction time to 1-3s. Continue to circulate argon, aluminum precursor and oxidant on the Al2O3 transition layer and perform multiple cyclic depositions. During the cyclic process, insert the reaction cycle of the non-metallic element dopant and oxidant. After the deposition is completed, the doped modified Al2O3 layer is obtained. S4. Set the flow rate of titanium precursor to 800-900 sccm and the inlet time to 1-3 s. Set the flow rate of rare earth element precursor to 800-900 sccm and the inlet time to 1-3 s. Cyclicly introduce argon, titanium precursor and oxidant into the doped and modified Al2O3 layer and perform multiple cyclic depositions. Insert the reaction cycle of rare earth element precursor and oxidant during the cycle. After the deposition is completed, the doped and modified TiO2 layer is obtained. S5. Argon, zirconium precursor or silicon precursor and oxidant are circulated into the doped and modified TiO2 layer. The flow rate of zirconium precursor or silicon precursor is 800-1000 sccm and the circulation time is 1-4s. The third layer is obtained by repeated cyclic deposition. S6. Repeat steps S3 to S5 to deposit a periodic stacked structure, finally obtaining a stacked anti-corrosion coating.

7. The application of a multilayer anti-corrosion coating as described in any one of claims 1-5, characterized in that: It is used in the surface coating of aluminum alloy components in marine equipment, optoelectronic equipment, precision electronics, and high-temperature environments.