A high-temperature stealth coating with adjustable wave-absorbing performance and a preparation method thereof

Abstract

A high-temperature stealth coating with adjustable wave absorption performance and a preparation method thereof belong to the technical field of high-temperature wave absorbing material preparation, and solve the problem of low wave absorption performance of existing high-temperature coatings. The method of the present invention comprises: step 1, pre-treating the metal substrate by micro-arc oxidation to pre-form a phosphate coating on the surface of the metal substrate; step 2, mixing and stirring high-temperature ceramic aggregate, phosphate adhesive, curing agent and Co-based high-temperature absorber according to a preset mass fraction to prepare a coating; step 3, applying the coating to the pre-treated surface of the metal substrate, standing and hardening at room temperature, transferring to a high-temperature furnace for heat preservation, and obtaining a high-temperature stealth coating on the surface of the metal substrate after the coating is completely cured. The present invention is suitable for the preparation of high-temperature stealth coatings.

Description

Technical Field

[0001] The present application relates to the technical field of high-temperature absorbing material preparation, and in particular to a method for preparing a high-temperature stealth coating. Background Art

[0002] The rapid development of radar technology poses severe challenges to the survivability of weapon and equipment systems. Absorbing coatings, as the basis of electromagnetic wave control, can effectively reduce the radar reflection cross-sectional area of ​​equipment systems. However, the operating temperature of special parts of supersonic weapons and equipment reaches 700°C, and room temperature radar absorbing materials can hardly meet the demand. It is urgent to develop high-performance high-temperature radar absorbing materials.

[0003] At present, high-temperature absorbing coatings generally use SiC, Ti3SiC2, Ti3AlC2 and carbon materials as high-temperature absorbers. These materials have excellent temperature resistance and chemical stability, but their non-magnetic properties lead to the lack of ferromagnetic loss and can only attenuate electromagnetic waves through dielectric loss, and their electromagnetic absorption bandwidth is relatively narrow. In addition, the stealth coating prepared by physical coating method generally uses resin as the high-temperature matrix material. The maximum service temperature of the prepared coating does not exceed 300°C, and cracking is very likely to occur between the coating and the matrix in a high-temperature environment, which also limits the improvement of the high-temperature coating's absorbing performance. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of low microwave absorption performance of existing high-temperature coatings, and to provide a method for preparing a high-temperature stealth coating with adjustable microwave absorption performance.

[0005] The present invention is achieved through the following technical solutions. On the one hand, the present invention provides a method for preparing a high-temperature stealth coating with adjustable wave absorbing performance, the method comprising:

[0006] Step 1, pre-treating the metal substrate by micro-arc oxidation to form a phosphate coating on the surface of the metal substrate;

[0007] Step 2, mixing and stirring the high temperature ceramic aggregate, the phosphate adhesive, the curing agent and the Co-based high temperature absorbent according to a preset mass fraction to prepare a coating;

[0008] Step 3: Apply the coating to the pretreated surface of the metal substrate, let it stand at room temperature to harden, transfer it to a high-temperature furnace for insulation, and obtain a high-temperature stealth coating on the surface of the metal substrate after the coating is completely cured.

[0009] Furthermore, before step 1, the method further includes: polishing the metal substrate to remove a surface oxide layer.

[0010] Furthermore, the metal substrate is specifically one of a Ti-based substrate, a Fe-based substrate and an Al-based substrate.

[0011] Furthermore, the micro-arc oxidation method specifically includes: the concentration of the aluminum phosphate electrolyte is 0.3-0.7 mol / L, the current density is 3-7 A / dm 2 , the reaction time is 10 to 60 minutes.

[0012] Furthermore, the method for setting the preset mass fraction specifically includes: the mass fraction of the high-temperature ceramic aggregate is 0-40%; the mass fraction of the phosphate adhesive is 30-50%; the mass fraction of the curing agent is 5-10%; the mass fraction of the Co-based high-temperature absorbent is 20-60%.

[0013] Furthermore, the high-temperature ceramic aggregate is a mixture of one or more of Al2O3, TiO2, SiO2, SiC, Si3N4, AlN, cordierite and mullite, and the particle size is 1nm~80μm; the phosphate adhesive is any one of aluminum phosphate adhesive, zirconium phosphate adhesive, silicone phosphate adhesive, boron phosphate adhesive and magnesium phosphate adhesive; the curing agent is one of Al2O3, ZnO, CuO, Fe2O3 and Cr2O3, and the particle size is 1nm~80μm; the Co-based high-temperature absorbent is a mixture of one or more of spherical particles, flaky particles and rod-shaped particles, and the particle size ranges from 200nm to 30μm.

[0014] Furthermore, the transferring to a high temperature furnace for heat preservation specifically includes: transferring to a 300-600° C. high temperature furnace for a heat preservation time of 1-8 hours.

[0015] On the other hand, the present invention also provides a high-temperature stealth coating based on the method for preparing a high-temperature stealth coating with adjustable absorbing performance as described above, wherein the high-temperature stealth coating is composed of a three-part structure, specifically including: a bottom layer is a metal substrate; a transition layer is a phosphate coating; and a surface layer is a composite coating including a phosphate adhesive, a ceramic aggregate, a curing agent and a Co-based absorber.

[0016] Furthermore, the transition layer is obtained by micro-arc oxidation and has a thickness of 0.5 to 80 μm.

[0017] Furthermore, the surface layer is obtained by a physical coating method and has a thickness of 1 to 10 mm.

[0018] Beneficial effects of the present invention:

[0019] Firstly, the present invention uses phosphate as the high-temperature coating matrix material, and its mechanical properties and thermal shock resistance have been verified in the field of high-temperature coatings.

[0020] Secondly, the introduction of Co-based high-temperature absorbers into the phosphate coating can make the high-temperature coating have high-temperature stealth properties.

[0021] Thirdly, based on the regulation of the types and mass fractions of various phases in the coating, as well as the regulation of the size and morphological characteristics of the Co-based high-temperature absorber, the high-temperature stealth performance of the coating can be regulated.

[0022] The high-temperature stealth coating preparation technology has a simple process, and the prepared coating is tightly bonded to the substrate and is not easy to fall off. The phosphate / Co composite coating has both ferromagnetic and dielectric electromagnetic loss mechanisms, and its high-temperature stealth performance is greatly improved, and its effective absorption can be adjusted in a wide range.

[0023] The invention is suitable for the preparation of high-temperature stealth coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 This is the typical morphology of the phosphate / Co high-temperature stealth coating of the present invention;

[0026] Figure 2 Schematic diagram of electromagnetic properties of the phosphate / Co composite coating of the present invention;

[0027] Figure 3 This is a diagram showing the wave absorption performance of the 2 mm thick phosphate / Co composite coating of the present invention in the X-band. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0029] Embodiment 1: A method for preparing a high-temperature stealth coating with adjustable wave absorbing performance, the method comprising:

[0030] Step 1, pre-treating the metal substrate by micro-arc oxidation to form a phosphate coating on the surface of the metal substrate;

[0031] Step 2, mixing and stirring the high temperature ceramic aggregate, the phosphate adhesive, the curing agent and the Co-based high temperature absorbent according to a preset mass fraction to prepare a coating;

[0032] Step 3: Apply the coating to the pretreated surface of the metal substrate, let it stand at room temperature to harden, transfer it to a high-temperature furnace for insulation, and obtain a high-temperature stealth coating on the surface of the metal substrate after the coating is completely cured.

[0033] In this embodiment, firstly, this embodiment uses phosphate as the high-temperature coating matrix material, and its mechanical properties and thermal shock resistance have been verified in the field of high-temperature coatings.

[0034] Secondly, the introduction of Co-based high-temperature absorbers into the phosphate coating can make the high-temperature coating have high-temperature stealth properties.

[0035] Thirdly, based on the regulation of the types and mass fractions of various phases in the coating, as well as the regulation of the size and morphological characteristics of the Co-based high-temperature absorber, the high-temperature stealth performance of the coating can be regulated.

[0036] Embodiment 2: This embodiment further defines the method for preparing a high-temperature stealth coating with adjustable wave absorbing performance described in Embodiment 1. In this embodiment, the operations before step 1 are further defined, specifically including:

[0037] Before step 1, the method further includes: polishing the metal substrate to remove a surface oxide layer.

[0038] In this embodiment, the metal substrate is polished to obtain a clean active surface to ensure the effective implementation of the micro-arc oxidation surface treatment process and obtain a high-quality phosphate surface coating, thereby improving the bonding strength between the high-temperature coating and the metal substrate.

[0039] Embodiment 3: This embodiment further limits the method for preparing a high-temperature stealth coating with adjustable wave absorbing performance described in Embodiment 1. In this embodiment, the metal substrate is further limited, specifically including:

[0040] The metal substrate is one of a Ti-based substrate, a Fe-based substrate and an Al-based substrate.

[0041] In this embodiment, the metal substrate applicable to this embodiment is not limited, that is, any one of the three substrates in this embodiment can be selected to complete the preparation of the high-temperature stealth coating.

[0042] Embodiment 4: This embodiment further limits the method for preparing a high-temperature stealth coating with adjustable wave absorbing performance described in Embodiment 1. In this embodiment, the micro-arc oxidation method is further limited, specifically including:

[0043] The micro-arc oxidation method specifically includes: the concentration of aluminum phosphate electrolyte is 0.3-0.7 mol / L, the current density is 3-7 A / dm 2 , the reaction time is 10 to 60 minutes.

[0044] In this embodiment, the surface pretreatment using the micro-arc oxidation method can effectively achieve better bonding between the coating obtained in step 2 and the substrate, and its thickness is very thin, generally only tens of microns.

[0045] Embodiment 5: This embodiment further limits the method for preparing a high-temperature stealth coating with adjustable wave absorbing performance described in Embodiment 1. In this embodiment, the method for setting the preset mass fraction is further limited, specifically including:

[0046] The method for setting the preset mass fraction specifically includes: the mass fraction of the high-temperature ceramic aggregate is 0-40%; the mass fraction of the phosphate adhesive is 30-50%; the mass fraction of the curing agent is 5-10%; and the mass fraction of the Co-based high-temperature absorbent is 20-60%.

[0047] In this embodiment, the microstructure of the high-temperature coating can be regulated by adjusting the mass fraction of each phase, thereby achieving regulation of its mechanical properties and electromagnetic properties.

[0048] Embodiment 6: This embodiment further limits the method for preparing a high-temperature stealth coating with adjustable wave absorbing performance described in Embodiment 5. In this embodiment, the high-temperature ceramic aggregate, phosphate adhesive, curing agent and Co-based high-temperature absorber are further limited, specifically including:

[0049] The high-temperature ceramic aggregate is a mixture of one or more of Al2O3, TiO2, SiO2, SiC, Si3N4, AlN, cordierite and mullite, and the particle size is 1nm~80μm; the phosphate adhesive is any one of aluminum phosphate adhesive, zirconium phosphate adhesive, silicone phosphate adhesive, boron phosphate adhesive, and magnesium phosphate adhesive; the curing agent is one of Al2O3, ZnO, CuO, Fe2O3, Cr2O3, and the particle size is 1nm~80μm; the Co-based high-temperature absorbent is a mixture of one or more of spherical particles, flaky particles and rod-shaped particles, and the particle size ranges from 200nm to 30μm.

[0050] In this embodiment, the dielectric constants of the selected high-temperature ceramic aggregate, phosphate adhesive and curing agent are all moderate, which makes the impedance matching characteristics of the high-temperature coating relatively excellent, and these materials are inexpensive and easy to obtain. By regulating the size and morphology of the Co-based high-temperature absorber, its intrinsic electromagnetic properties can be finely regulated. In addition, by regulating the type, size, and morphology of each phase in the high-temperature coating, the absorbing performance of the high-temperature coating can be regulated.

[0051] Embodiment 7: This embodiment further limits the method for preparing a high-temperature stealth coating with adjustable wave absorbing performance described in Embodiment 1. In this embodiment, the transfer to a high-temperature furnace for heat preservation is further limited, specifically including:

[0052] The transferring to a high temperature furnace for heat preservation specifically includes: transferring to a 300-600° C. high temperature furnace for a heat preservation time of 1-8 hours.

[0053] In this embodiment, the set insulation temperature and time can achieve a high-temperature stealth coating on the surface of the metal substrate after the coating is completely cured.

[0054] Embodiment 8: This embodiment is an example of a method for preparing a high-temperature stealth coating with adjustable wave absorbing performance as described above, specifically comprising:

[0055] Specific process for preparing phosphate / Co high temperature stealth coating:

[0056] a. Pretreatment of titanium substrate: Use sandpaper to polish the surface of a 180*180mm titanium substrate (Ti-6Al-4V, TC4) to remove surface impurities and oxide layer, and use micro-arc oxidation to pre-treat the surface of the substrate to form a dense aluminum phosphate film on the surface. The micro-arc oxidation method uses aluminum phosphate solution as the electrolyte, with a concentration of 50g / L and a current density of 4.0A / dm 2 , the micro-arc oxidation time is 30min;

[0057] b. The high temperature ceramic aggregate cordierite, aluminum dihydrogen phosphate adhesive, curing agent Al2O3 and spherical Co-based absorbent were mixed in a mass fraction of 20:50:10:20 and mechanically stirred to prepare a uniform coating;

[0058] c. Apply the mixed coating prepared in step 2 to the pretreated surface of the metal substrate, let it stand at room temperature for 2 hours to harden, then transfer it to a 500°C high-temperature furnace and keep it warm for 6 hours. After the coating is completely cured, a high-temperature stealth coating is obtained on the surface of the metal substrate.

[0059] Embodiment 9: This embodiment is a high-temperature stealth coating based on a method for preparing a high-temperature stealth coating with adjustable wave absorbing performance as described above. The structure of the high-temperature stealth coating is specifically as follows:

[0060] The high-temperature stealth coating consists of three parts: the bottom layer is a metal substrate; the transition layer is a phosphate coating obtained by micro-arc oxidation, with a thickness of 0.5 to 80 μm; the surface layer is a phosphate / Co-based composite coating, which is a composite coating including phosphate adhesive, ceramic aggregate, curing agent and Co-based absorber, obtained by physical coating method, with a thickness of 1 to 10 mm.

[0061] The high-temperature stealth coating of this embodiment uses phosphate as the high-temperature coating matrix material, and its mechanical properties and thermal shock resistance have been verified in the field of high-temperature coatings.

[0062] Secondly, the introduction of Co-based high-temperature absorbers into the phosphate coating can make the high-temperature coating have high-temperature stealth properties.

[0063] Thirdly, based on the regulation of the types and mass fractions of various phases in the coating, as well as the regulation of the size and morphological characteristics of the Co-based high-temperature absorber, the high-temperature stealth performance of the coating can be regulated.

[0064] The following is an explanation of the effects of the present invention:

[0065] like Figure 1 As shown, Figure 1 This is a typical morphology of phosphate / Co high-temperature stealth coating. The Co-based high-temperature absorber is randomly dispersed inside the phosphate matrix, and its size is 5 to 30 microns. The composite coating has a complete structure without obvious cracks. The coating is tightly bonded to the matrix, and the coating has high strength.

[0066] like Figure 2 As shown, Figure 2 The electromagnetic properties of phosphate / Co composite coatings are shown in the figure. The test frequency band is X-band (8.2-12.4 GHz) and the test temperature range is 20-400°C. At room temperature, the real part of the dielectric constant of the composite coating fluctuates around 8.5, and its imaginary part fluctuates around 1.0; the real part of the magnetic permeability fluctuates around 1.05, and the imaginary part of the magnetic permeability fluctuates around 0.14. As the temperature increases, the dielectric constant of the composite coating increases significantly, and shows an upward trend as the frequency increases; the real part of the magnetic permeability of the composite coating increases with the increase of temperature, but its imaginary part decreases with the increase of temperature. Among them, (a) is the real part of the dielectric constant, (b) is the imaginary part of the dielectric constant, (c) is the real part of the magnetic permeability, and (d) is the imaginary part of the magnetic permeability. The horizontal axes are all electromagnetic wave frequencies.

[0067] like Figure 3 As shown, Figure 3 The absorption performance of 2 mm thick phosphate / Co composite coating in X-band. When the service temperature of the coating is 400℃, the maximum absorption peak RL max The effective absorption bandwidth reaches 9.1dB, which is higher than 5dB and basically covers the entire X-band, showing excellent high-temperature electromagnetic stealth characteristics. The horizontal axis is the electromagnetic wave frequency.

Claims

1. A method for preparing a high-temperature stealth coating with adjustable wave absorbing performance, characterized in that: The method comprises: Step 1, pre-treating the metal substrate by micro-arc oxidation to form a phosphate coating on the surface of the metal substrate; Step 2, mixing and stirring the high temperature ceramic aggregate, the phosphate adhesive, the curing agent and the Co-based high temperature absorbent according to a preset mass fraction to prepare a coating; Step 3, applying the coating to the pretreated surface of the metal substrate, standing at room temperature for hardening, transferring to a high-temperature furnace for heat preservation, and obtaining a high-temperature stealth coating on the surface of the metal substrate after the coating is completely cured; The micro-arc oxidation method specifically includes: the concentration of the aluminum phosphate electrolyte is 0.3-0.7 mol / L, the current density is 3-7 A / dm2, and the reaction time is 10-60 min; The method for setting the preset mass fraction specifically includes: the mass fraction of the high temperature ceramic aggregate is 0-40%; the mass fraction of the phosphate adhesive is 30-50%; the mass fraction of the curing agent is 5-10%; the mass fraction of the Co-based high temperature absorbent is 20-60%; The high temperature ceramic aggregate is a mixture of one or more of Al2O3, TiO2, SiO2, SiC, Si3N4, AlN, cordierite and mullite, and the particle size is 1nm-80μm; the phosphate adhesive is any one of aluminum phosphate adhesive, zirconium phosphate adhesive, phosphate silicone adhesive, boron phosphate adhesive and magnesium phosphate adhesive; the curing agent is one of ZnO, CuO, Fe2O3 and Cr2O3, and the particle size is 1nm-80μm; the Co-based high temperature absorbent is a mixture of one or more of spherical particles, flaky particles and rod-shaped particles, and the particle size ranges from 200nm to 30μm; The transferring to a high temperature furnace for heat preservation specifically includes: transferring to a 300-600° C. high temperature furnace for a heat preservation time of 1-8 hours.

2. The method for preparing a high-temperature stealth coating with adjustable wave absorbing performance according to claim 1, characterized in that: Before step 1, the method further includes: polishing the metal substrate to remove a surface oxide layer.

3. The method for preparing a high-temperature stealth coating with adjustable wave absorbing performance according to claim 1, characterized in that: The metal substrate is specifically one of a Ti-based substrate, a Fe-based substrate and an Al-based substrate.

4. A high-temperature stealth coating according to any one of claims 1 to 3, wherein the method for preparing the high-temperature stealth coating with adjustable wave absorbing performance is characterized in that: The high-temperature stealth coating is composed of a three-part structure, specifically including: a bottom layer of a metal substrate; a transition layer of a phosphate coating; and a surface layer of a composite coating including a phosphate adhesive, a high-temperature ceramic aggregate, a curing agent and a Co-based high-temperature absorbent.

5. The high-temperature stealth coating according to claim 4, characterized in that: The transition layer is obtained by micro-arc oxidation and has a thickness of 0.5 to 80 μm.

6. The high-temperature stealth coating according to claim 4, characterized in that: The surface layer is obtained by a physical coating method and has a thickness of 1 to 10 mm.

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