Iron-based wave-absorbing coating with high-visualization corrosion early warning function as well as preparation method and application of iron-based wave-absorbing coating
By introducing a bilayer structure of 1,10-phenanthroline and its derivatives and a white coating of gum arabic into the iron-based microwave absorbing coating, the problem of early detection of corrosion of iron-based microwave absorbing coatings in high humidity and high salt environments is solved, and highly visible corrosion early warning and microwave absorption performance recovery are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-07
AI Technical Summary
Existing iron-based microwave absorbing coatings are difficult to detect early in high humidity and high salt environments, leading to a decline in microwave absorption performance. Furthermore, existing early warning mechanisms have low contrast against dark backgrounds, making it difficult to identify corroded areas in the early stages.
A base coating with corrosion warning capability is formed by mixing an iron-based magnetic absorber with 1,10-phenanthroline and its derivatives. A water-soluble coating of gum arabic and white pigment is prepared on the surface to provide a high-contrast white developing background, which can be quickly identified and removed by washing with water after identification.
It achieves highly visible early warning of corrosion of iron-based absorbing coatings in the early stage, enhances the identification effect of corrosion areas, and does not affect the absorbing performance of the coating after the early warning is completed.
Smart Images
Figure CN121801403A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave absorbing materials technology, specifically relating to an iron-based microwave absorbing coating with highly visible corrosion early warning function, its preparation method, and its application. Background Technology
[0002] Ferrous magnetic absorbers possess advantages such as high magnetic permeability and low magnetic loss, making them a commonly used class of electromagnetic wave absorbers in the field of microwave absorbing materials. However, ferrous materials are prone to corrosion in high-humidity and high-salt environments, leading to a decline in their microwave absorption performance. Because ferrous magnetic absorbers are small in size and often encapsulated in resin during practical applications, corrosion is difficult to detect in its early stages. By the time obvious rust spots are observed, the material's microwave absorption performance has already been severely compromised. To prevent the dangerous situation of microwave absorption performance failure, it is necessary to establish an early warning mechanism to enable the early detection of corrosion in the microwave absorbing coating, allowing for timely repair.
[0003] To address the corrosion problem of iron-based materials, existing technologies have been studied from multiple perspectives: Corrosion resistance modification: This involves enhancing the corrosion resistance of the absorbent or coating itself through alloying, surface coating, or the introduction of corrosion inhibitors. These methods focus on passive protection, aiming to delay corrosion, but they cannot provide early, intuitive assessments of whether corrosion has occurred or where it has occurred.
[0004] Corrosion early warning mechanism: Early visualization of corrosion is achieved by introducing corrosion indicators into the material system. For example, 1,10-phenanthroline is deposited on the surface of an iron-based absorbent, utilizing its interaction with corrosion products such as Fe. 2+ The ability to generate orange-red complexes enables chemical colorimetric early warning of corrosion, representing a significant advancement from "passive protection" to "active early warning."
[0005] However, a long-neglected but crucial practical engineering problem has thus emerged: when these early warning absorbing materials are applied to equipment surfaces in the form of dark-colored coatings (such as black or dark gray), the contrast between the orange-red color signal generated by the early warning and the dark background is extremely low. This makes it difficult for the human eye to quickly and accurately identify and locate corrosion in its early stages (i.e., when the signal is weak) during inspections. This essentially undermines the "visualization" purpose of the early warning mechanism in engineering practice, allowing corrosion to progress undetected to later stages, causing irreversible performance damage.
[0006] On the other hand, if a permanent white or light-colored topcoat is applied directly to the surface of the warning coating to enhance the contrast, two new problems will arise: First, the additional dense coating may hinder the contact between the corrosive medium and the internal warning agent, delaying or even blocking the release of the warning signal; second, the introduction of the topcoat will change the electromagnetic structure of the coating system, causing unpredictable interference to the absorption performance of the underlying layer, which violates the original design intention of the absorption coating.
[0007] Therefore, designing a novel coating structure that significantly enhances the visual recognition of corrosion early warning signals without compromising the core electromagnetic properties of the iron-based absorbing coating, and that is easy to remove after early warning identification without affecting the underlying function, has become a key technological bottleneck that must be overcome to promote the transformation of intelligent early warning stealth coatings from the laboratory to engineering applications. Currently, there is a lack of effective solutions that can systematically resolve these contradictions. Summary of the Invention
[0008] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides an iron-based microwave absorbing coating with highly visible corrosion early warning capabilities, its preparation method, and its application. The method first uses an iron-based magnetic absorber mixed with 1,10-phenanthroline and its derivatives as a filler, and then mixes it with resin to prepare an iron-based microwave absorbing coating with corrosion early warning capabilities. Once corrosion occurs in the iron-based microwave absorbing coating, the 1,10-phenanthroline and its derivatives react with the Fe produced during corrosion. 2+ Ions combine to form a red complex, which serves as an early warning system for corrosion. Then, gum arabic, white pigment, and water are mixed to prepare a water-soluble coating on the surface of the iron-based microwave-absorbing coating. This surface provides a clear contrast with the red complex, achieving a highly visible corrosion warning effect. It can also be easily removed using water solubility, thus not affecting the microwave-absorbing performance of the iron-based coating.
[0009] The technical solution of this invention is: an iron-based microwave absorbing coating with high visual corrosion early warning function, the coating having a double-layer composite structure, comprising: The wave-absorbing and early warning substrate, comprising an iron-based magnetic absorber, a resin matrix, and 1,10-phenanthroline or its derivative dispersed therein, is used to absorb electromagnetic waves and react with Fe upon corrosion. 2+ The reaction produces a red alert complex; A visually enhanced and removable surface layer is coated on top of the underlying layer. The surface layer is a water-soluble white coating formed by mixing and curing gum arabic, white pigment and deionized water. It is used to provide a high-contrast white background for the red warning complex and can be completely removed by washing after the warning recognition is completed, so as to restore the original electromagnetic wave absorption performance of the underlying layer. A further technical solution of the present invention is as follows: the iron-based magnetic absorber is selected from one of carbonyl iron, iron-silicon-aluminum alloy, iron-silicon-chromium alloy, iron-silicon alloy, iron-aluminum-boron alloy or amorphous alloy, iron-boron-phosphorus alloy or amorphous alloy, iron-nickel alloy, iron-nickel-molybdenum alloy, iron-chromium-nickel alloy, iron-cobalt-chromium alloy, and iron-cobalt-nickel-chromium alloy; the morphology of the iron-based magnetic absorber is spherical or flake-shaped, with a particle size of 3-40 μm. A further technical solution of the present invention is that the 1,10-phenanthroline or its derivatives are one or more of 1,10-phenanthroline, 1,10-phenanthroline-5-amine, or 1,10-phenanthroline monohydrate.
[0010] A further technical solution of the present invention is that the white pigment is titanium dioxide or zinc oxide powder, which has a spherical morphology and a particle size of 10-40 μm.
[0011] A further technical solution of the present invention is as follows: the resin matrix is epoxy resin, and the epoxy resin, curing agent, and diluent together constitute the bonding system of the bottom layer; the curing agent is polyamide 650, a medium viscosity brownish-yellow liquid; the diluent is prepared by mixing xylene and n-butanol in a mass ratio of 7:3, and both are colorless and transparent liquids.
[0012] A method for preparing the iron-based microwave absorbing coating includes the following steps: Step 1: Prepare the early warning absorbing coating: Mix 15-25 parts by weight of resin, 5-15 parts by weight of curing agent, and 5-15 parts by weight of diluent, and stir and disperse at 2500-3500 rpm for 10-20 minutes to obtain a premixed resin solution. Add 65-75 parts by weight of iron-based magnetic absorber and 2-5 parts by weight of 1,10-phenanthroline or its derivative to the premixed resin liquid, and continue stirring at 2500-3500 rpm for 10-20 minutes to obtain a uniform early warning microwave absorbing coating. Step 2: Fabrication of the absorbing and early warning sublayer: The warning and absorbing coating obtained in step 1 is applied to the surface of the substrate by spraying. The thickness of each spray is controlled. After step drying and curing, a cured coating with a thickness of 1 mm is finally formed, which is the bottom layer for absorbing and warning. Step 3: Prepare the visualization enhancement layer: Mix 5-10 parts by weight of gum arabic, 10-20 parts by weight of deionized water, and 5-10 parts by weight of white pigment, and stir well to obtain a water-soluble white paint. The water-soluble white coating is uniformly sprayed onto the surface of the microwave absorbing and early warning substrate obtained in step 2 to form a wet film with a thickness of 0.05 mm. Then, it is dried at 50-70°C for 10 minutes to cure into a film, thus obtaining a visually enhanced and removable surface layer, and finally obtaining an iron-based microwave absorbing coating with high visual corrosion early warning function.
[0013] A further technical solution of the present invention is: in step 2, the spraying method is compressed air spraying, the spraying pressure is 0.5MPa, the spraying distance is 15-25cm, and the spray gun moving speed is 30-40cm / s.
[0014] A further technical solution of the present invention is as follows: In step 2, the step-by-step drying and curing specifically involves: after each 0.1-0.2 mm wet film is sprayed, it is air-dried at room temperature for 10-20 minutes; after the total thickness reaches the target value, the sample is placed in an oven and kept at 80°C for 12 hours for complete curing. A further technical solution of the present invention is: in step 3, the drying temperature is 60°C and the drying time is 10 minutes.
[0015] An application of the iron-based microwave absorbing coating on the surface of coastal facilities, aerospace vehicles, or metal components that require both electromagnetic stealth and early corrosion monitoring.
[0016] Beneficial effects The beneficial effects of this invention are as follows: This invention constructs a two-layer composite structure of "wave-absorbing early warning bottom layer + water-soluble white reinforcing surface layer," fundamentally solving the core problem of low contrast between the early warning signal (orange-red) and the dark coating background in existing early warning absorbing coatings, making it difficult for the human eye to identify in the early stages. The white surface layer provides a high-contrast background for the red early warning signal, enabling even weak initial corrosion signals to be quickly and accurately located, thus elevating the practicality of the early warning mechanism to an engineering application level. Specific effects are analyzed below: 1. The corrosion early warning effect in this invention is provided by 1,10-phenanthroline and its derivatives. Specifically, 1,10-phenanthroline and its derivatives can react with Fe produced during corrosion. 2+ The reaction proceeds, producing a red complex. This reaction is highly sensitive and can therefore provide early warning of corrosion.
[0017] 2. To address the issue that the dark color of the iron-based microwave absorbing coating makes the red complex less recognizable, this invention prepares a white coating on the surface of the iron-based microwave absorbing coating. Compared to black or dark brown iron-based microwave absorbing coatings, white reflects almost all light, giving the red complex better contrast and effectively enhancing the visualization effect of corrosion early warning.
[0018] 3. The white surface layer is prepared using gum arabic and white pigment. Gum arabic is a natural tree sap, a highly branched macromolecule composed of complex polysaccharides. When it comes into contact with water, the numerous hydroxyl and carboxyl groups on its molecular chains form hydrogen bonds with water. The addition of water molecules causes gum arabic to change from a solid to a liquid colloid. When the water evaporates, the hydrogen bond network is disrupted, and the gum molecules re-aggregate, reforming into a solid state through intermolecular forces. Based on this principle, the surface layer prepared using gum arabic in this invention can be easily and quickly sprayed and formed. After assisting in early warning color development, it can be quickly removed with water without affecting the performance of the iron-based microwave absorbing coating. In addition, the numerous hydroxyl and carboxyl groups and other active groups contained in the gum arabic molecular chains can combine with the active groups on the surface of the pigment particles through physical and chemical bonds, giving the white pigment excellent dispersibility in the gum arabic resin, enhancing the uniformity of the surface layer color, and further strengthening the corrosion early warning effect. Attached Figure Description
[0019] Figure 1 The surface morphology of each embodiment and comparative example after a 10-minute salt spray test; Figure 2 The surface morphology of Example 1, Comparative Example 1, and Comparative Example 2 after a 30-minute salt spray test; Figure 3 The images are of Example 1 before (a) the application of the water-soluble coating, after (b) the application of the water-soluble coating, and after (c) the removal of the water-soluble coating 30 min after a salt spray test. Detailed Implementation
[0020] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.
[0021] 1,10-Phenanthroline and its derivatives can react with Fe 2+ It forms an orange-red complex, which is a commonly used iron ion indicator. If it reacts with the Fe generated during corrosion... 2+ By combining these methods, corrosion can be visualized, enabling early warning of corrosion. In the prior art, CN 119767657 B reports a case of using this mechanism for corrosion warning of iron-based magnetic absorbers. However, for iron-based coatings, the resulting film color is typically a dark black or brown, which makes Fe... 2+ The resulting red complexes are difficult to identify. Therefore, improvements to the iron-based microwave absorbing coating are needed to accurately locate the corrosion zone in its early stages.
[0022] White reflects more light than black, providing brightness and contrast for red complexes and effectively enhancing recognition. However, constructing a white resin-based coating on the surface can negatively impact the microwave absorption performance of the iron-based coating and may also block the release of red complexes. Gum arabic is a water-soluble natural sap with excellent compatibility with pigments. Using gum arabic to prepare a white coating on the iron-based coating surface can not only enhance the identification effect of corrosion warnings but also be easily removed with water, preventing any impact on the iron-based microwave absorbing coating itself. This mechanism can help us achieve a more effective and flexible corrosion warning system.
[0023] Based on the above analysis, the first aspect of the present invention provides an iron-based microwave absorbing coating with highly visible corrosion early warning function, as detailed below: This invention first uses a mixture of iron-based magnetic absorber and 1,10-phenanthroline and its derivatives as a filler, which is then mixed with resin and sprayed to obtain an iron-based microwave absorbing coating with corrosion early warning capability. Once this iron-based microwave absorbing coating corrodes, the 1,10-phenanthroline and its derivatives react with the Fe produced during corrosion. 2+ Ions combine to form a red complex, which serves as an early warning system for corrosion. Then, gum arabic, white pigment, and water are mixed to prepare a water-soluble coating for the iron-based microwave absorbing layer. This surface forms a clear contrast with the red complex, enhancing the visibility of corroded areas and strengthening the visualization of corrosion warnings. The water solubility of gum arabic allows this surface to be quickly removed with water without affecting the coating's microwave absorbing properties.
[0024] The iron-based microwave absorbing coating with high-visibility corrosion early warning function is a two-layer composite structure, comprising: The wave-absorbing and early warning substrate, comprising an iron-based magnetic absorber, a resin matrix, and 1,10-phenanthroline or its derivative dispersed therein, is used to absorb electromagnetic waves and react with Fe upon corrosion. 2+ The reaction produces a red alert complex; A visually enhanced and removable surface layer is coated on top of the underlying layer. This surface layer is a water-soluble white coating formed by mixing and curing gum arabic, white pigment, and water. It provides a high-contrast white background for the red warning complex and can be completely removed by washing after the warning recognition is completed, thereby restoring the original electromagnetic wave absorption performance of the underlying layer.
[0025] A second aspect of the present invention provides a method for preparing an iron-based microwave absorbing coating with high visibility corrosion early warning function, comprising the following steps: Step 1: Mix 15-25 parts by weight of resin, 5-15 parts by weight of curing agent, and 5-15 parts by weight of diluent. Disperse the mixture using a stirring disperser at 2500-3500 rpm for 10-20 minutes. Then add 65-75 parts by weight of iron-based magnetic absorber and 2-5 parts by weight of 1,10-phenanthroline and its derivatives. Continue stirring at 2500-3500 rpm for 10-20 minutes to obtain an iron-based microwave absorbing coating with corrosion early warning function.
[0026] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the surface of the aluminum alloy substrate by compressed air spraying. After the spraying is completed, the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0027] Step 3: Prepare a water-soluble coating on the surface of the iron-based microwave absorbing coating: Mix 5-10 parts by weight of gum arabic, 10-20 parts by weight of deionized water, and 5-10 parts by weight of white pigment, stir evenly, and spray onto the surface of the iron-based microwave absorbing coating obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 minutes to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0028] Preferably, the resin mentioned in step one is epoxy resin E-44, a transparent viscous liquid, and is selected from the products of Nantong Xingchen Synthetic Materials Co., Ltd. The curing agent is polyamide 650, a medium-viscosity brownish-yellow liquid, and is selected from the products of Zhenjiang Danbao Resin Co., Ltd.
[0029] Preferably, the diluent mentioned in step one is prepared by mixing xylene and n-butanol in a mass ratio of 7:3, both of which are colorless and transparent liquids. The diluent can adjust the viscosity of the coating and improve its workability.
[0030] Preferably, the iron-based magnetic absorber mentioned in step one is one of carbonyl iron, iron-silicon-aluminum alloy, iron-silicon-chromium alloy, iron-silicon alloy, iron-aluminum-boron alloy or amorphous alloy, iron-boron-phosphorus alloy or amorphous alloy, iron-nickel alloy, iron-nickel-molybdenum alloy, iron-chromium-nickel alloy, iron-cobalt-chromium alloy, iron-cobalt-nickel-chromium alloy, and iron-cobalt-nickel-chromium alloy, and is spherical or flake-shaped with a particle size of 3-40 μm.
[0031] Preferably, the 1,10-phenanthroline and its derivatives mentioned in step one are one or more of 1,10-phenanthroline, 1,10-phenanthroline-5-amine, and 1,10-phenanthroline monohydrate. 1,10-phenanthroline and its derivatives can react with Fe... 2+ The formation of red complexes by ions serves as an early warning of corrosion.
[0032] Preferably, the process and parameters of the air compression spraying in step two are as follows: pour the paint into the W-71 spray gun, adjust the spraying pressure to 0.5 MPa, the spraying distance to 15-20 cm, and the spray gun moving speed to 30-40 cm / s, and spray evenly on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, dry the sample at room temperature for 10-15 min, and then repeat the above spraying process until the thickness of the obtained coating reaches 1 mm.
[0033] Preferably, the gum arabic mentioned in step three is a white or colorless powder solid, and is selected from the product of Tianjin Zhiyuan Chemical Reagent Co., Ltd. Gum arabic contains a large number of active groups such as hydroxyl and carboxyl groups, which can combine with the active groups on the surface of pigment particles through physical and chemical bonds, giving the pigment excellent dispersibility in the arabic resin and enhancing the uniformity of the surface layer color. Simultaneously, these hydroxyl and carboxyl groups can undergo strong hydration with water molecules through hydrogen bonds, causing the gum arabic to dissolve. This allows the surface layer to be easily washed away with water, thus not affecting the absorption performance of the iron-based microwave absorbing coating.
[0034] Preferably, the white pigment mentioned in step three is titanium dioxide or zinc oxide powder, with a spherical morphology and a particle size of 10-40 μm. The pigment particles can be stably dispersed in gum arabic and form a white surface layer. White can reflect almost all light, giving the red complex better contrast and effectively enhancing the visualization effect of corrosion early warning.
[0035] The present invention will now be described in detail with reference to embodiments and comparative examples: Example 1: Step 1: Mix 20 parts by weight of epoxy resin E-44, 10 parts by weight of curing agent polyamide 650, and 10 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 minutes using a stirring disperser. Then add 70 parts by weight of carbonyl iron and 5 parts by weight of 1,10-phenanthroline, and continue stirring at 3000 rpm for 20 minutes to obtain an iron-based microwave absorbing coating with corrosion warning function.
[0036] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0037] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 20 parts by weight of deionized water, and 10 parts by weight of titanium dioxide, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60°C for 10 minutes to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0038] Example 2: Step 1: Mix 23 parts by weight of epoxy resin E-44, 12 parts by weight of curing agent polyamide 650, and 15 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 minutes using a stirring disperser. Then add 65 parts by weight of iron-silicon-aluminum alloy, 3 parts by weight of 1,10-phenanthroline, and 2 parts by weight of 1,10-phenanthroline-5-amine. Continue stirring at 2500 rpm for 15 minutes to obtain an iron-based microwave absorbing coating with corrosion warning function.
[0039] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0040] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 8 parts by weight of gum arabic, 16 parts by weight of deionized water, and 8 parts by weight of zinc oxide powder, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60°C for 10 minutes to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0041] Example 3: Step 1: Mix 20 parts by weight of epoxy resin E-44, 10 parts by weight of curing agent polyamide 650, and 10 parts by weight of diluent. Disperse the mixture at 3500 rpm for 15 min using a stirring disperser. Then add 70 parts by weight of iron-silicon-chromium alloy and 3 parts by weight of 1,10-phenanthroline-monohydrate, and continue stirring at 3000 rpm for 20 min to obtain an iron-based microwave absorbing coating with corrosion early warning function.
[0042] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0043] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 15 parts by weight of deionized water, and 5 parts by weight of titanium dioxide, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60°C for 10 minutes to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0044] Example 4: Step 1: Mix 20 parts by weight of epoxy resin E-44, 10 parts by weight of curing agent polyamide 650, and 10 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 minutes using a stirring disperser. Then add 70 parts by weight of iron-silicon alloy and 4 parts by weight of 1,10-phenanthroline-5-amine, and continue stirring at 3000 rpm for 20 minutes to obtain an iron-based microwave absorbing coating with corrosion early warning function.
[0045] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0046] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 5 parts by weight of gum arabic, 15 parts by weight of deionized water, and 10 parts by weight of zinc oxide powder, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 min to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0047] Example 5: Step 1: Mix 15 parts by weight of epoxy resin E-44, 8 parts by weight of curing agent polyamide 650, and 10 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 min using a stirring disperser. Then add 75 parts by weight of iron-nickel alloy and 5 parts by weight of 1,10-phenanthroline, and continue stirring at 2500 rpm for 25 min to obtain an iron-based microwave absorbing coating with corrosion warning function.
[0048] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0049] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 15 parts by weight of deionized water, and 8 parts by weight of titanium dioxide, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 min to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0050] Example 6: Step 1: Mix 25 parts by weight of epoxy resin E-44, 13 parts by weight of curing agent polyamide 650, and 15 parts by weight of diluent. Disperse the mixture at 3000 rpm for 25 min using a stirring disperser. Then add 65 parts by weight of iron-nickel-molybdenum alloy, 1 part by weight of 1,10-phenanthroline, and 4 parts by weight of 1,10-phenanthroline-monohydrate. Continue stirring at 2500 rpm for 15 min to obtain an iron-based microwave absorbing coating with corrosion warning function.
[0051] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0052] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 15 parts by weight of deionized water, and 8 parts by weight of zinc oxide powder, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 min to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0053] Example 7: Step 1: Mix 22 parts by weight of epoxy resin E-44, 11 parts by weight of curing agent polyamide 650, and 15 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 min using a stirring disperser. Then add 75 parts by weight of iron-chromium-nickel alloy and 5 parts by weight of 1,10-phenanthroline, and continue stirring at 3500 rpm for 25 min to obtain an iron-based microwave absorbing coating with corrosion early warning function.
[0054] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0055] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 10 parts by weight of deionized water, and 5 parts by weight of titanium dioxide, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 min to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0056] Example 8: Step 1: Mix 25 parts by weight of epoxy resin E-44, 15 parts by weight of curing agent polyamide 650, and 15 parts by weight of diluent. Disperse the mixture at 2500 rpm for 20 min using a stirring disperser. Then add 70 parts by weight of iron-cobalt-chromium alloy, 2 parts by weight of 1,10-phenanthroline-5-amine, and 3 parts by weight of 1,10-phenanthroline-monohydrate. Continue stirring at 3000 rpm for 20 min to obtain an iron-based microwave absorbing coating with corrosion warning function.
[0057] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0058] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 15 parts by weight of deionized water, and 10 parts by weight of zinc oxide powder, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 min to obtain an iron-based microwave absorbing coating with high visibility corrosion early warning function.
[0059] Comparative Example 1: Step 1: Mix 20 parts by weight of epoxy resin E-44, 10 parts by weight of curing agent polyamide 650, and 10 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 minutes using a stirring disperser. Then add 70 parts by weight of carbonyl iron and continue stirring at 3000 rpm for 20 minutes to obtain an iron-based microwave absorbing coating.
[0060] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining the iron-based microwave absorbing coating.
[0061] Step 3: Prepare a water-soluble coating on the iron-based microwave absorbing coating surface: Mix 10 parts by weight of gum arabic, 20 parts by weight of deionized water, and 10 parts by weight of titanium dioxide, stir evenly, and spray onto the iron-based microwave absorbing coating surface obtained in Step 2. The spraying pressure, distance, and speed are the same as in Step 2. The coating thickness is approximately 0.05 mm. Then, place it in an oven and dry it rapidly at 60 ℃ for 10 min to obtain the iron-based microwave absorbing coating with a water-soluble coating.
[0062] Comparative Example 2: Step 1: Mix 20 parts by weight of epoxy resin E-44, 10 parts by weight of curing agent polyamide 650, and 10 parts by weight of diluent. Disperse the mixture at 3000 rpm for 20 minutes using a stirring disperser. Then add 70 parts by weight of carbonyl iron and 5 parts by weight of 1,10-phenanthroline, and continue stirring at 3000 rpm for 20 minutes to obtain an iron-based microwave absorbing coating with corrosion warning function.
[0063] Step 2: Subsequently, a 1 mm thick microwave absorbing coating is prepared on the substrate surface using compressed air spraying: The iron-based microwave absorbing coating prepared in Step 1 is poured into a W-71 spray gun, the spraying pressure is adjusted to 0.5 MPa, the spraying distance to 20 cm, and the spray gun moving speed to 30 cm / s, and the coating is evenly sprayed on the substrate surface in an S-shaped path; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 min, and then the above spraying process is repeated until the thickness of the coating reaches 1 mm. Then the sample is placed in an oven and kept at 80 ℃ for 12 h to cure the coating on the substrate surface, thus obtaining an iron-based microwave absorbing coating with corrosion early warning function.
[0064] Thus, the modified iron-based microwave absorbing coatings provided in the embodiments and comparative examples of this invention have been prepared.
[0065] To characterize the corrosion warning capability of the modified iron-based microwave absorbing coating prepared in this invention, a neutral salt spray test was conducted on the coating according to GJB 150.11A-2009 standard, and the surface discoloration was observed. The surface morphology of each embodiment and comparative example after the 10-minute salt spray test is shown in the figures below. Figure 1 As shown; the surface morphology of Example 1, Comparative Example 1, and Comparative Example 2 after a 30-minute salt spray test is shown in the image. Figure 2 As shown.
[0066] Depend on Figure 1 It can be seen that after only 10 minutes of salt spray testing, all samples from each embodiment showed obvious red discoloration at the artificially scratched defects, indicating that the corrosion of the iron-based magnetic absorber occurred rapidly at the defects, generating Fe... 2+ It reacts with 1,10-phenanthroline and its derivatives to form a red complex. The depth and size of the red color in the samples of each embodiment differ, which is related to the intrinsic corrosion resistance of the absorbent. Comparing the embodiments with Comparative Example 1, it can be seen that the surface of the Comparative Example 1 sample without the addition of 1,10-phenanthroline and its derivatives remains white, and no red complex is formed, indicating that the corrosion warning capability of the modified iron-based microwave absorbing coating is provided by 1,10-phenanthroline and its derivatives. Comparing the embodiments with Comparative Example 2, it can be seen that the surface of the Comparative Example 2 sample without the water-soluble coating is not obviously red, indicating that the darker color of the iron-based microwave absorbing coating has a low contrast with the red complex, making the red complex not clearly visible and greatly affecting the visualization effect of corrosion warning.
[0067] Depend on Figure 2 It can be seen that after 30 minutes of salt spray testing, Example 1 compared to... Figure 1 After 10 minutes of salt spray testing, the increased red coverage area indicates a deepening of corrosion. (Compared to Example 1) Figure 1 No significant changes were observed on the surface of Comparative Example 2, demonstrating that the water-soluble coating exhibits good tolerance in salt spray environments, maintaining its morphology in the initial stages and providing support for colorimetric early warning. No red complexes were visible on the surface of Comparative Example 2, further confirming the effectiveness of the white water-soluble coating in enhancing corrosion early warning identification compared to the results of Example 1. Simultaneously, no obvious corrosion traces were observed on the surface of Comparative Example 2, indicating that the corrosion of the iron-based absorbing coating was still in its early stages during the 10-minute and 30-minute salt spray tests. This demonstrates that our modified iron-based absorbing coating can achieve a significant early warning effect in the early stages of corrosion.
[0068] To characterize the electromagnetic wave absorption capability of the prepared absorbing coating, the reflection loss of the coating was tested using the bow-shaped method according to GJB 2038-94 standard. Minimum reflection loss (RL) minThe effective absorption bandwidth (EAB) when the loss is <-10 dB is shown in Table 1.
[0069] Table 1. Minimum reflection loss and effective absorption bandwidth of each embodiment and comparative example.
[0070] As shown in Table 1, the iron-based absorbing coatings in each embodiment and comparative example all exhibit excellent microwave absorption performance. Comparing Example 1 and Comparative Examples 1 and 2, it can be found that their microwave absorption performance is not significantly different, proving that the water-soluble coating and the added 1,10-phenanthroline and its derivatives have little effect on the microwave absorption performance of the iron-based absorbing coating, and the microwave absorption performance of the coating is mainly provided by the iron-based magnetic absorber.
[0071] To characterize the removability of the water-soluble coating in the modified iron-based microwave absorbing coating prepared in this invention, photographs were taken of Example 1 before spraying the water-soluble coating, after spraying the water-soluble coating, and after a 30-minute salt spray test to remove the water-soluble coating. Figure 3 As shown.
[0072] Depend on Figure 3 As can be seen, in Example 1, the color contrast before and after spraying the water-soluble coating is obvious. After spraying the water-soluble coating, the original black color is completely covered by white, proving that the water-soluble coating has good hiding power. After removing the water-soluble coating, no white residue can be seen on the surface, and the surface is completely restored to its state before spraying, proving the excellent removability of the water-soluble coating.
[0073] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.
Claims
1. A steel-based microwave absorbing coating with highly visible corrosion early warning function, characterized in that, The coating has a two-layer composite structure, including: The wave-absorbing and early warning sublayer is composed of an iron-based magnetic absorber, a resin matrix, and 1,10-phenanthroline or its derivative dispersed therein. It is used to absorb electromagnetic waves and react with Fe in the event of corrosion. 2+ The reaction produces a red alert complex; A visually enhanced and removable surface layer is coated on top of the underlying layer. The surface layer is a water-soluble white coating formed by mixing and curing gum arabic, white pigment and deionized water. It is used to provide a high-contrast white background for the red warning complex and can be completely removed by washing after the warning recognition is completed, so as to restore the original electromagnetic wave absorption performance of the underlying layer.
2. The iron-based microwave absorbing coating with high visual corrosion early warning function according to claim 1, characterized in that: The iron-based magnetic absorber is selected from one of the following: carbonyl iron, iron-silicon-aluminum alloy, iron-silicon-chromium alloy, iron-silicon alloy, iron-aluminum-boron alloy or amorphous alloy, iron-boron-phosphorus alloy or amorphous alloy, iron-nickel alloy, iron-nickel-molybdenum alloy, iron-chromium-nickel alloy, iron-cobalt-chromium alloy, and iron-cobalt-nickel-chromium alloy; the morphology of the iron-based magnetic absorber is spherical or flake-shaped, with a particle size of 3-40 μm.
3. The iron-based microwave absorbing coating with high visual corrosion early warning function according to claim 1, characterized in that: The 1,10-phenanthroline or its derivatives are one or more of 1,10-phenanthroline, 1,10-phenanthroline-5-amine, or 1,10-phenanthroline monohydrate.
4. The iron-based microwave absorbing coating with high visual corrosion early warning function according to claim 1, characterized in that: The white pigment is titanium dioxide or zinc oxide powder, and its morphology is spherical with a particle size of 10-40 μm.
5. The iron-based microwave absorbing coating with high visual corrosion early warning function according to claim 1, characterized in that: The resin matrix is epoxy resin, and the epoxy resin, curing agent, and diluent together constitute the bonding system of the bottom layer; the curing agent is polyamide 650, a medium viscosity brownish-yellow liquid; the diluent is prepared by mixing xylene and n-butanol in a mass ratio of 7:3, and both are colorless and transparent liquids.
6. A method for preparing the iron-based microwave absorbing coating according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Prepare the early warning absorbing coating: Mix 15-25 parts by weight of resin, 5-15 parts by weight of curing agent, and 5-15 parts by weight of diluent, and stir and disperse at 2500-3500 rpm for 10-20 minutes to obtain a premixed resin solution. Add 65-75 parts by weight of iron-based magnetic absorber and 2-5 parts by weight of 1,10-phenanthroline or its derivative to the premixed resin liquid, and continue stirring at 2500-3500 rpm for 10-20 minutes to obtain a uniform early warning microwave absorbing coating. Step 2: Fabrication of the absorbing and early warning sublayer: The warning and absorbing coating obtained in step 1 is applied to the surface of the substrate by spraying. The thickness of each spray is controlled. After step drying and curing, a cured coating with a thickness of 1 mm is finally formed, which is the bottom layer for absorbing and warning. Step 3: Prepare the visualization enhancement layer: Mix 5-10 parts by weight of gum arabic, 10-20 parts by weight of deionized water, and 5-10 parts by weight of white pigment, and stir well to obtain a water-soluble white paint. The water-soluble white coating is uniformly sprayed onto the surface of the microwave absorbing and early warning substrate obtained in step 2 to form a wet film with a thickness of 0.05 mm. Then, it is dried at 50-70°C for 10 minutes to cure into a film, thus obtaining a visually enhanced and removable surface layer, and finally obtaining an iron-based microwave absorbing coating with high visual corrosion early warning function.
7. The preparation method according to claim 6, characterized in that: In step 2, the spraying method is compressed air spraying, the spraying pressure is 0.5MPa, the spraying distance is 15-25cm, and the spray gun moving speed is 30-40cm / s.
8. The preparation method according to claim 6, characterized in that: In step 2, the step-by-step drying and curing process is as follows: after each 0.1-0.2 mm wet film is sprayed, it is air-dried at room temperature for 10-20 minutes; after the total thickness reaches the target value, the sample is placed in an oven and kept at 80°C for 12 hours for complete curing.
9. The preparation method according to claim 6, characterized in that: In step 3, the drying temperature is 60℃ and the drying time is 10 minutes.
10. The application of the iron-based microwave absorbing coating according to any one of claims 1-5 on the surface of coastal facilities, aerospace vehicles, or metal components that require both electromagnetic stealth and early corrosion monitoring.