FeSiAl / SiO2 composite wave-absorbing coating and preparation method thereof

Abstract

The invention provides a FeSiAl / SiO2 composite wave-absorbing coating and a preparation method thereof. The FeSiAl / SiO2 composite wave-absorbing coating comprises the following components in parts by mass: 60-70 parts of FeSiAl, 5-10 parts of ethyl silicate and 3-5 parts of a binder, wherein the binder is obtained by reaction of graphene oxide, silicon dioxide, a silane coupling agent, vinyl silicone oil, hydroxyl acrylate, a functional monomer, epoxy resin, polyether polyol and isocyanate. According to the invention, the surface of FeSiAl is firstly coated with SiO2, and the SiO2 is mixed with the binder containing graphene oxide and other materials, so that the obtained coating not only has good wave-absorbing performance, but also is higher in stability and strength and good in adhesive force, and meanwhile, the preparation method is simple and lower in cost, overcomes the defects in the prior art, and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave absorbing materials, and particularly relates to a FeSiAl / SiO 2 composite absorbing coating and a preparation method thereof. Background Art

[0002] With the rapid development of electronic products and communication devices, electromagnetic waves and the electromagnetic energy they radiate have also increased rapidly. Electromagnetic pollution has become the fourth major pollution after air pollution, water pollution, and noise pollution, posing a greater risk to the safety and health of the environment and the human body. Therefore, the current industry has invested a lot of resources to deal with the harm caused by electromagnetic waves, and there have been many reports on research results of various absorbing materials.

[0003] FeSiAl absorbing material is a material that can effectively absorb incident electromagnetic waves and reduce electromagnetic interference, which can improve the stability and reliability of equipment. Some studies have shown that ball-milling flaking treatment of FeSiAl material can further improve the low-frequency absorbing performance of FeSiAl absorbing material. In communication devices, FeSiAl absorbing material can be used to reduce the reflection and scattering of electromagnetic waves, and reduce the impact of electromagnetic radiation on the surrounding environment and the human body. At the same time, it can also improve the signal receiving and transmitting efficiency of communication devices. FeSiAl absorbing material can also be used as a magnetic core material and plays an important role in power electronic devices. Due to its excellent electromagnetic properties, FeSiAl absorbing material is also used in the preparation of sensor materials.

[0004] There are also studies reported in CN105304308A, CN110719727A, etc. that coating insulating media such as phosphate, silica, and PVA on the surface of FeSiAl material can further improve the insulation and antioxidant properties of the material and improve the electromagnetic properties. However, whether it is a conventional FeSiAl absorbing material or a modified FeSiAl absorbing material, when applied to a coating, there are still defects such as insufficient adhesion to the substrate, poor coating stability, complex coating preparation process, and high cost. Therefore, such products still cannot meet the actual application requirements and are difficult to be promoted.

[0005] In summary, it is necessary to develop a new technical solution to solve the problems existing in the prior art. Summary of the Invention

[0006] The present invention provides a FeSiAl / SiO 2 composite absorbing coating. First, SiO is coated on the surface of FeSiAl 2, and is mixed with a binder containing materials such as graphene oxide. The resulting coating not only has good microwave absorption performance, but also has high stability, strength, and good adhesion. At the same time, the preparation method is simple and the cost is low, overcoming the deficiencies in the prior art and having good application prospects.

[0007] An object of the present invention is to provide a FeSiAl / SiO 2 composite microwave absorption coating, and the raw materials of the FeSiAl / SiO 2 composite microwave absorption coating include components in the following parts by mass:

[0008] 60-70 parts of FeSiAl

[0009] 5-10 parts of tetraethyl orthosilicate

[0010] 3-5 parts of binder;

[0011] Wherein,

[0012] the binder is obtained by reacting graphene oxide, silicon dioxide, silane coupling agent, vinyl silicone oil, acrylic hydroxy ester, functional monomer, epoxy resin, polyether polyol and isocyanate.

[0013] Furthermore, the preparation method of the binder includes the following steps:

[0014] S1. Mix graphene oxide, silicon dioxide and silane coupling agent, and after heating and reacting, obtain intermediate product 1;

[0015] S2. Mix vinyl silicone oil, acrylic hydroxy ester, functional monomer and initiator, and after heating and reacting, obtain intermediate product 2;

[0016] S3. Mix polyether polyol, isocyanate and chain extender, and after heating and reacting, obtain intermediate product 3;

[0017] S4. Mix the intermediate product 1, intermediate product 2, epoxy resin, intermediate product 3 and catalyst, and after heating and reacting, obtain the binder.

[0018] Furthermore, the mass ratio of the graphene oxide to the silicon dioxide is (2-4):1.

[0019] Furthermore, the mass ratio of the vinyl silicone oil, acrylic hydroxy ester and functional monomer is (10-20):(20-40):(1-5).

[0020] Furthermore, the mass ratio of the polyether polyol to the isocyanate is (1-3):1.

[0021] Further, the mass ratio of the intermediate product 1, intermediate product 2, intermediate product 3 and epoxy resin is (1 - 3):(5 - 15):(1 - 5):(1 - 5).

[0022] Further, the silane coupling agent is an amino silane coupling agent.

[0023] Further, the functional monomer is selected from monomers having acrylate units with multiple functional groups.

[0024] Another object of the present invention is to provide the above FeSiAl / SiO 2 preparation method of the composite wave - absorbing coating, and the preparation method of the FeSiAl / SiO 2 composite wave - absorbing coating comprises the following steps:

[0025] L1. Under the protection of inert gas, FeSiAl is added to a tubular furnace for heat treatment, then tetraethyl orthosilicate is added. After reaction, it is cooled to obtain FeSiAl / SiO 2 composite powder;

[0026] L2. The FeSiAl / SiO 2 composite powder and a binder are mixed and stirred evenly, and then coated on the surface of the substrate to obtain FeSiAl / SiO 2 composite wave - absorbing coating.

[0027] Further, the temperature of the heat treatment is 600 - 1000 °C.

[0028] Further, the mass ratio of Fe, Si, and Al in the FeSiAl is (80 - 90):(5 - 10):(3 - 6).

[0029] The present invention has the following beneficial effects:

[0030] The present invention provides a FeSiAl / SiO 2 composite wave - absorbing coating, with FeSiAl as the core and SiO 2 coated on the outer side as the shell layer, thereby improving the electromagnetic properties and stability of the composite material. At the same time, the present invention also uses a specific binder to be compounded with the FeSiAl / SiO 2 composite material to prepare a coating, further enhancing the comprehensive performance of the product. Among them, the binder first reacts graphene oxide and silica with a silane coupling agent to obtain an intermediate product introducing amino groups; and mixes and reacts vinyl silicone oil, hydroxyacrylate and a functional monomer to obtain an organosilicon - modified polyacrylic acid hydroxy ester with a branched structure; then reacts polyisocyanate and polyether, and then mixes and reacts the above components with epoxy resin to obtain a binder with a three - dimensional network structure. Silica and graphene oxide are introduced into this component, so it has SiO2 The FeSiAl / SiO of the shell 2 The composite material has good compatibility and affinity, and the bonding strength between the binder and the composite material is improved. In addition, graphene oxide can further increase the specific surface area and play the functions of electrical and magnetic loss, thereby enhancing the wave absorption ability. In addition, an organosilicon group is introduced into the binder, which helps to enhance the thermal stability, solvent resistance and film-forming property, and can further promote the improvement of strength and service life on the basis of the three-dimensional cross-linked structure. At the same time, a large number of active hydroxyl groups and epoxy groups in the binder can also promote the formation of an interpenetrating network structure, significantly improve the bonding strength, enhance the adhesion of the coating, and meet the performance requirements of practical applications. Detailed implementation manners

[0031] In order to more clearly illustrate the technical solutions of the present invention, the following examples are listed. Unless otherwise specified, the raw materials, reactions and post-treatment means appearing in the examples are common raw materials on the market and technical means well-known to those skilled in the art.

[0032] The terms "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain cases. However, in the same case or other cases, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0033] It should be understood that, unless otherwise indicated in any operating example or otherwise, all numbers representing the amounts of ingredients or otherwise used in the specification and claims should be understood to be modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that vary depending upon the desired properties sought to be obtained by the present invention.

[0034] The following raw materials are used in the examples of the present invention:

[0035] FeSiAl, flaky magnetic powder, with the mass ratio of Fe, Si, and Al being 85:9.6:5.4.

[0036] Graphene oxide, purchased from Aladdin.

[0037] Vinyl silicone oil, purchased from Shenzhen Jipeng Silicon Fluoride Materials Co., Ltd.

[0038] Polytetrahydrofuran ether glycol, PTMEG2000, purchased from Shenzhen Xianzhi Chemical Technology Co., Ltd.

[0039] The preparation method of the binder includes the following steps:

[0040] S1. Using ethanol and water with a volume ratio of 1:9 as the solvent, graphene oxide, silicon dioxide, and KH550 with a mass ratio of 4:1:5 were mixed, reacted at 65 °C for 12 h, then filtered, washed, and dried to obtain Intermediate Product 1;

[0041] S2. Using toluene as the solvent, vinyl silicone oil, 2-hydroxyethyl methacrylate, trimethylolpropane triacrylate, and benzoyl peroxide with a mass ratio of 10:20:1:0.6 were mixed evenly, reacted at 40 °C for 1 h, and the solvent was removed by vacuum distillation to obtain Intermediate Product 2;

[0042] S3. Under a nitrogen atmosphere, polytetrahydrofuran ether diol, diphenylmethane diisocyanate, and 1,4-butanediol with a mass ratio of 2:1:0.1 were mixed, reacted at 65 °C for 0.5 h to obtain Intermediate Product 3;

[0043] S4. The Intermediate Product 1, Intermediate Product 2, Intermediate Product 3, and E44 epoxy resin with a mass ratio of 2:15:5:5 were mixed, then stannous octoate accounting for 1% of the system mass was added, reacted at 50 °C for 2 h, and then dried and pulverized to obtain the binder.

[0044] Example 1

[0045] A FeSiAl / SiO 2 composite microwave absorbing coating, the raw materials of the FeSiAl / SiO 2 composite microwave absorbing coating include components in the following mass parts:

[0046] FeSiAl 60 parts

[0047] Ethyl silicate 6 parts

[0048] Binder 4 parts;

[0049] The preparation method of the above FeSiAl / SiO 2 composite microwave absorbing coating includes the following steps:

[0050] L1. According to the above mass parts, under Ar gas protection, FeSiAl was added to a tubular furnace and heated to 700 °C, then ethyl silicate was added to a liquid evaporator, heated and vaporized, and transported to the tubular furnace with Ar as the carrier gas for 1 h, and after cooling, FeSiAl / SiO 2 composite powder was obtained;

[0051] L2. The FeSiAl / SiO 2 composite powder and the binder were mixed, stirred evenly, heated and coated on the surface of the substrate at 140 - 150 °C, and cured to obtain a FeSiAl / SiO 2 composite microwave absorbing coating with a thickness of 0.5 mm.

[0052] Example 2

[0053] A FeSiAl / SiO 2 composite wave - absorbing coating, wherein the raw materials of the FeSiAl / SiO 2 composite wave - absorbing coating include the following components in parts by mass:

[0054] FeSiAl 65 parts

[0055] Ethyl silicate 6 parts

[0056] Binder 4.5 parts;

[0057] The preparation method of the above - mentioned FeSiAl / SiO 2 composite wave - absorbing coating comprises the following steps:

[0058] L1. According to the above parts by mass, under the protection of Ar gas, add FeSiAl to a tube furnace and heat it to 700 °C, then add ethyl silicate to a liquid evaporator, heat it to vaporize, and transport it to the tube furnace with Ar as the carrier gas for 1 h. After cooling, obtain FeSiAl / SiO 2 composite powder;

[0059] L2. Mix the FeSiAl / SiO 2 composite powder and the binder, stir evenly, heat and coat it on the surface of the substrate at 140 - 150 °C, and cure to obtain a FeSiAl / SiO 2 composite wave - absorbing coating with a thickness of 0.5 mm.

[0060] Example 3

[0061] A FeSiAl / SiO 2 composite wave - absorbing coating, wherein the raw materials of the FeSiAl / SiO 2 composite wave - absorbing coating include the following components in parts by mass:

[0062] FeSiAl 65 parts

[0063] Ethyl silicate 6 parts

[0064] Binder 4 parts;

[0065] The preparation method of the above - mentioned FeSiAl / SiO 2 composite wave - absorbing coating comprises the following steps:

[0066] L1. According to the above parts by mass, under the protection of Ar gas, add FeSiAl to a tube furnace and heat it to 700 °C, then add ethyl silicate to a liquid evaporator, heat it to vaporize, and transport it to the tube furnace with Ar as the carrier gas for 1 h. After cooling, obtain FeSiAl / SiO 2 composite powder;

[0067] L2. Mix the FeSiAl / SiO 2 composite powder and the binder, stir evenly, heat and coat on the surface of the substrate at 140 - 150 °C, and cure to obtain a FeSiAl / SiO 2 composite wave-absorbing coating with a thickness of 0.5 mm.

[0068] Comparative Example 1

[0069] A FeSiAl / SiO 2 composite wave-absorbing coating. The difference between this comparative example and Example 1 is that in step S4 of the preparation method of the binder, intermediate product 1 is deleted, and the other components and the preparation method are the same as those in Example 1.

[0070] Comparative Example 2

[0071] A FeSiAl / SiO 2 composite wave-absorbing coating. The difference between this comparative example and Example 1 is that in step S2 of the preparation method of the binder, vinyl silicone oil is deleted, and the other components and the preparation method are the same as those in Example 1.

[0072] Test Example

[0073] Perform performance tests on the FeSiAl / SiO 2 composite wave-absorbing coatings prepared in Examples 1 - 3 and Comparative Examples 1 - 2.

[0074] Measure the absorption peak value and frequency bandwidth of the coating in the 1 - 10 GHz band; and measure the adhesion and salt spray resistance (240 h) of the coating according to GB / T 5210 and GB / T 1771.

[0075] The test results are shown in Table 1.

[0076] Table 1 Performance Test Results

[0077] Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Adhesion Grade 0 Grade 0 Grade 0 Grade 1 Grade 0 Salt spray resistance No rust No rust No rust Minor rust Obvious rust Absorption peak / dB -6 -6 -6 -5 -6 Frequency bandwidth / GHz 2 2 2 2 2

[0078] As can be seen from Table 1, the adhesion of the FeSiAl / SiO 2 composite wave-absorbing coatings prepared in Examples 1 - 3 can reach level 0, and at the same time, they have excellent weather resistance, a relatively high absorption peak value for electromagnetic waves, and a relatively wide frequency bandwidth. However, Comparative Examples 1 - 2 with changed binder materials result in a lower bonding strength between components, causing a significant decrease in the adhesion and weather resistance of the coating, and at the same time, the wave-absorbing performance also decreases, and the comprehensive performance is not ideal. In summary, the FeSiAl / SiO 2 composite wave-absorbing coating of the present invention has excellent performance, overcomes the defects existing in the prior art, and has good application prospects.

[0079] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

[0080] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A FeSiAl / SiO2 composite absorbing coating, characterized in that: The raw materials of the FeSiAl / SiO2 composite absorbing coating include the following components in parts by mass: FeSiAl 60-70 parts Ethyl silicate 5-10 parts 3-5 parts of binder; in, The binder is obtained by reacting graphene oxide, silicon dioxide, silane coupling agent, vinyl silicone oil, hydroxy acrylate, functional monomer, epoxy resin, polyether polyol and isocyanate.

2. The FeSiAl / SiO2 composite absorbing coating according to claim 1, characterized in that: The preparation method of the binder comprises the following steps: S1, mixing graphene oxide, silicon dioxide and a silane coupling agent, and heating the mixture for reaction to obtain an intermediate product 1; S2, mixing vinyl silicone oil, hydroxy acrylate, functional monomer and initiator, heating and reacting to obtain intermediate product 2; S3, mixing polyether polyol, isocyanate and chain extender, heating and reacting to obtain intermediate product 3; S4, mixing the intermediate product 1, the intermediate product 2, the epoxy resin, the intermediate product 3 and the catalyst, and heating them for reaction to obtain a binder.

3. The FeSiAl / SiO2 composite absorbing coating according to claim 2, characterized in that: The mass ratio of the graphene oxide to silicon dioxide is (2-4):

1.

4. The FeSiAl / SiO2 composite absorbing coating according to claim 2, characterized in that: The mass ratio of the vinyl silicone oil, hydroxy acrylate and functional monomer is (10-20):(20-40):(1-5).

5. The FeSiAl / SiO2 composite absorbing coating according to claim 2, characterized in that: The mass ratio of the polyether polyol to the isocyanate is (1-3):

1.

6. The FeSiAl / SiO2 composite absorbing coating according to claim 2, characterized in that: The mass ratio of the intermediate product 1, the intermediate product 2, the intermediate product 3 and the epoxy resin is (1-3):(5-15):(1-5):(1-5).

7. The FeSiAl / SiO2 composite absorbing coating according to claim 1, characterized in that: The silane coupling agent is an aminosilane coupling agent.

8. The method for preparing the FeSiAl / SiO2 composite radar absorbing coating according to any one of claims 1 to 7, characterized in that: The preparation method of the FeSiAl / SiO2 composite absorbing coating comprises the following steps: L1. Under the protection of inert gas, FeSiAl is added into a tube furnace for heat treatment, and then ethyl silicate is added. After the reaction, the mixture is cooled to obtain FeSiAl / SiO2 composite powder; L2. Mix the FeSiAl / SiO2 composite powder and a binder, stir evenly, and apply the mixture on the surface of a substrate to obtain a FeSiAl / SiO2 composite absorbing coating.

9. The method for preparing the FeSiAl / SiO2 composite microwave absorbing coating according to claim 8, characterized in that: The temperature of the heat treatment is 600-1000°C.

10. The method for preparing the FeSiAl / SiO2 composite microwave absorbing coating according to claim 8, characterized in that: The mass ratio of Fe, Si and Al in the FeSiAl is (80-90):(5-10):(3-6).