A method for preparing high temperature resistant wave absorbing film

Abstract

The invention discloses a method for preparing a high-temperature resistant wave-absorbing film, and belongs to the field of material technology. Weigh an absorbent and a wave-transmitting substrate fiber, both of which are chopped fibers, and place them in a fiber disintegrator; weigh a binder and place it in the fiber disintegrator; set the rotation speed and dissociation time of the fiber disintegrator, add deionized water to the fiber disintegrator, and start the fiber disintegrator for dissociation; after the dissociation is completed, pour the mixed solution in the fiber disintegrator into a square paper sheet former, start the filtration program, and obtain a paper sheet; hot-press and dry the obtained paper sheet to remove excess water, and obtain a high-temperature resistant wave-absorbing film. The high-temperature resistant wave-absorbing film prepared by the invention has good high-temperature stability.

Description

Technical Field

[0001] The invention relates to a method for preparing a high temperature resistant wave absorbing film, and belongs to the technical field of materials. Background Art

[0002] With the demand for technological development, low detectability will be the development trend of future high-speed aircraft. Under the condition that the application of appearance stealth technology is restricted, absorbing materials are the most important and effective technical approach to suppress its strong radar scattering. Absorbing films have attracted widespread attention from researchers due to their portability, wide application scenarios, good absorbing performance, and adjustable dielectric properties. Under room temperature absorption application conditions, relevant research on absorbing films has made great progress, but in the field of high temperature resistant absorbing, there are no mature absorbing film products available. Therefore, the development of high temperature resistant absorbing films is very important for the development of high temperature stealth technology.

[0003] Absorbing materials usually used in high-temperature environments will use high-temperature resistant coatings to protect the internal absorbing materials to prevent them from being corroded and oxidized by high-temperature oxygen-containing environments. This approach has major disadvantages: first, the composite design of the double-layer structure increases the complexity of the process, and also makes it difficult to control the mechanical properties and other parameters of the final product; second, the high-temperature resistant coating itself has certain dielectric parameters, which will destroy the critical conditions of the material, making the impedance matching characteristics of the composite absorbing material worse, thereby affecting the absorbing performance. Therefore, it is still challenging to adopt a better absorbing material preparation scheme to obtain high-performance high-temperature resistant absorbing materials. Summary of the invention

[0004] The purpose of the present invention is to propose a method for preparing a high temperature resistant absorbing film based on the problems existing in the current high temperature resistant composite absorbing materials, using a high temperature resistant absorbent and a high temperature resistant absorbing substrate as raw materials, through a fiber dissociation operation and a wet papermaking process to prepare a high temperature resistant absorbing film.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a high temperature resistant wave absorbing film comprises the following steps:

[0007] 1) Weighing an absorbent and a wave-transmitting substrate fiber, both of which are short-cut fibers, and placing them in a fiber disintegrator;

[0008] 2) weighing a binder and placing it in the fiber separator;

[0009] 3) setting the rotation speed and dissociation time of the fiber dissociator, adding deionized water into the fiber dissociator, and starting the fiber dissociator for dissociation;

[0010] 4) After the dissociation is completed, the mixed solution in the fiber dissociator is poured into a square paper sheet former, and the filtration process is started to obtain a paper sheet;

[0011] 5) The obtained paper sheet is subjected to hot pressing and drying to remove excess water, thereby obtaining a high temperature resistant microwave absorbing film.

[0012] Preferably, the absorbent is selected from one of tungsten core silicon carbide fiber, silicon carbide-based composite fiber, boron nitride fiber, and aluminum nitride fiber.

[0013] Preferably, the wave-transmitting substrate fiber is selected from one of quartz fiber, glass fiber and alumina fiber.

[0014] Preferably, the mass ratio between the absorbent and the wave-transmitting substrate fiber is (1-10):10.

[0015] Preferably, the absorbent has a length of 5 to 10 mm, and the wave-transmitting substrate fiber has a length of 6 to 12 mm.

[0016] Preferably, the binder includes one or more of precipitated aramid fiber, polyvinyl alcohol, polyacrylate, and low-melting-point polypropylene fiber.

[0017] Preferably, the mass proportion of the binder in the total amount of the absorbent, the wave-transmitting substrate fiber and the binder is 5% to 15%.

[0018] Preferably, the rotation speed of the fiber disintegrator is set to 600-1000 r / min, and the disintegration time is set to 5-15 min.

[0019] Preferably, 3 to 5 L of deionized water are added to the fiber disintegrator.

[0020] Preferably, the temperature of the hot pressing drying is 90-120°C.

[0021] Preferably, the thickness of the high temperature resistant wave absorbing film is 0.1-0.2 mm.

[0022] Based on the problems existing in the current high temperature resistant composite absorbing materials, the present invention comprehensively considers the simplicity of the preparation process of the absorbing materials and the feasibility of regulating the dielectric properties, and proposes a method for preparing a high temperature resistant absorbing film. The high temperature resistant absorbent and the high temperature resistant absorbing substrate are used as raw materials. Through the fiber dissociation operation, the absorbent fiber, the absorbing substrate fiber and the binder are first quickly dispersed, and then fully mixed to form a suspension. The wet sheeting process is further adopted to make the absorbent fiber uniformly dispersed in the absorbing substrate, avoiding the problem of large fluctuations in dielectric parameters caused by uneven distribution of the absorbent, and realizing the preparation of the high temperature resistant absorbing film. The obtained high temperature resistant absorbing film has good high temperature stability and can withstand a high temperature oxygen-containing environment of 800°C. By increasing the proportion of the high temperature resistant absorbing fiber in the wet sheeting raw material, the electromagnetic parameters of the regulated high temperature resistant absorbing film can be improved, and the loss capacity of the absorbing film can be enhanced, providing technical support for the research of high temperature resistant stealth materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The dielectric constant of the high temperature resistant wave absorbing film prepared in Example 1 in the S band is shown.

[0024] Figure 2 The dielectric constant of the high temperature resistant wave absorbing film prepared in Example 2 in the S band is shown.

[0025] Figure 3 The dielectric constant of the high temperature resistant wave absorbing film prepared in Example 3 in the S band is shown. DETAILED DESCRIPTION

[0026] In order to make the above features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings.

[0027] The present invention discloses a method for preparing a high temperature resistant wave absorbing film, which is prepared by a wet sheet-forming process and specifically comprises the following steps:

[0028] Step 1: Weigh a certain amount of absorbent and wave-transmitting substrate fiber and place them in a fiber disintegrator.

[0029] According to some embodiments, the length of the absorbent may be selected to be 5 to 10 mm, and the length of the wave-transmitting substrate fiber may be selected to be 6 to 12 mm.

[0030] According to some embodiments, the absorbent may be selected from other types of high temperature resistant and oxidation resistant short fibers other than short tungsten core silicon carbide fibers, such as silicon carbide-based composite fibers, boron nitride fibers, aluminum nitride fibers, etc. The absorbent is a short fiber, has typical dielectric polarization loss characteristics, and has good oxidation and corrosion resistance in a high temperature oxygen-containing environment. The mass ratio of the absorbent in all raw materials directly affects the dielectric parameters of the obtained high temperature resistant absorbing film. The higher the content ratio of the absorbent, the higher the dielectric parameters of the obtained high temperature resistant absorbing film, and the stronger its loss capacity.

[0031] According to some embodiments, the wave-transmitting substrate fiber may also be selected from other fibers with good stability, such as glass fiber, alumina fiber, etc. The wave-transmitting substrate fiber has good stability in an air environment below 1200° C. and will not undergo physical changes such as melting or other chemical reactions.

[0032] According to some embodiments, the mass ratio between the absorbent and the wave-transmitting substrate fiber is (1-10):10.

[0033] Those skilled in the art can select the specific types and content ratios of the absorbent and wave-transmitting substrate fibers according to specific practical needs.

[0034] Step 2: Weigh a certain amount of binder and place it in a fiber separator.

[0035] According to some embodiments, the binder includes one or more of precipitated aramid fiber, polyvinyl alcohol, polyacrylate, and low-melting-point polypropylene fiber; the choice of binder has little effect on the dielectric properties of the absorbing film, so the compatibility between the binder and the chopped fibers is mainly considered during selection.

[0036] According to some embodiments, the amount of binder used in all raw materials (including binder, absorbent, and wave-transmitting substrate fiber) is controlled to be 5% to 15% by mass, and can be adjusted according to the type of binder.

[0037] Step 3: Set the speed of the fiber disintegrator, add deionized water into the fiber disintegrator, and start the fiber disintegrator for dissociation; the dissociation standard is to obtain a homogeneously dispersed mixed solution. Based on this standard, the dissociation time can be extended or the speed of the disintegrator can be increased.

[0038] According to some embodiments, the rotation speed of the fiber disintegrator is 600-1000 r / min.

[0039] According to some embodiments, 3 to 5 L of deionized water are added to the fiber disintegrator.

[0040] According to some embodiments, the dissociation time is 5 to 15 min.

[0041] According to some embodiments, dispersants may be used to assist in dissociation for different fiber types.

[0042] Step 4: After the dissociation is completed, pour the mixed solution in the fiber dissociator into the square paper sheet former, start the filtration program, and obtain the paper sheet.

[0043] Step 5: The obtained paper sheet is subjected to hot pressing and drying to remove excess water, thereby obtaining a high temperature resistant absorbing film with uniform thickness distribution and certain toughness.

[0044] According to some embodiments, the temperature of hot press drying can be controlled at 90-120° C., which is adjusted according to the type of binder.

[0045] According to some embodiments, the obtained high temperature resistant wave absorbing film has a thickness of 0.1 to 0.2 mm.

[0046] Specific embodiments are listed below:

[0047] Example 1

[0048] Step 1: Weigh 1g of 8mm chopped tungsten core silicon carbide fiber and 10g of 6mm chopped quartz fiber and place them in a fiber disintegrator;

[0049] Step 2: Weigh 2 g of precipitated aramid fiber and place it in a fiber disintegrator;

[0050] Step 3: Set the speed of the fiber disintegrator to 800 r / min, the disintegration time to 10 min, add 4 L of deionized water into the fiber disintegrator, and start the fiber disintegrator;

[0051] Step 4: After the dissociation is completed, the mixed solution in the fiber dissociator is poured into the square paper sheet former, and the filtration process is started to obtain the paper sheet;

[0052] Step 5: The obtained paper sheet is hot-pressed and dried at 100° C. to remove excess moisture and prepare a high-temperature resistant absorbing film with a thickness of 0.1 mm.

[0053] The dielectric constant of the high temperature resistant absorbing film obtained in this embodiment in the S band is as follows: Figure 1 shown.

[0054] Example 2

[0055] Step 1: Weigh 3 g of 5 mm long chopped tungsten core silicon carbide fiber and 10 g of 12 mm long chopped quartz fiber and place them in a fiber disintegrator;

[0056] Step 2: Weigh 1.5 g of precipitated aramid fiber and place it in a fiber disintegrator;

[0057] Step 3: Set the speed of the fiber disintegrator to 600 r / min, the disintegration time to 15 min, add 3 L of deionized water into the fiber disintegrator, and start the fiber disintegrator;

[0058] Step 4: After the dissociation is completed, the mixed solution in the fiber dissociator is poured into the square paper sheet former, and the filtration process is started to obtain the paper sheet;

[0059] Step 5: The obtained paper sheet is hot-pressed and dried at 90° C. to remove excess moisture and prepare a high-temperature resistant wave-absorbing film with a thickness of 0.1 mm.

[0060] The dielectric constant of the high temperature resistant absorbing film obtained in this embodiment in the S band is as follows: Figure 2 shown.

[0061] Example 3

[0062] Step 1: Weigh 10 g of 10 mm long chopped tungsten core silicon carbide fiber and 10 g of 10 mm long chopped quartz fiber and place them in a fiber disintegrator;

[0063] Step 2: Weigh 1g of precipitated aramid fiber and place it in a fiber disintegrator;

[0064] Step 3: Set the speed of the fiber disintegrator to 1000 r / min, the disintegration time to 5 min, add 5 L of deionized water into the fiber disintegrator, and start the fiber disintegrator;

[0065] Step 4: After the dissociation is completed, the mixed solution in the fiber dissociator is poured into the square paper sheet former, and the filtration process is started to obtain the paper sheet;

[0066] Step 5: The obtained paper sheet is hot-pressed and dried at 120° C. to remove excess moisture and prepare a high-temperature resistant wave-absorbing film with a thickness of 0.2 mm.

[0067] The dielectric constant of the high temperature resistant absorbing film obtained in this embodiment in the S band is as follows: Figure 3 shown.

[0068] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A method for preparing a high temperature resistant wave absorbing film, characterized in that: The following steps are involved: 1) Weighing an absorbent and a wave-transmitting substrate fiber in a mass ratio of (1-10):10, wherein both the absorbent and the wave-transmitting substrate fiber are chopped fibers, and placing them in a fiber disintegrator; the absorbent is selected from one of tungsten core silicon carbide fiber, silicon carbide-based composite fiber, boron nitride fiber, and aluminum nitride fiber, and the wave-transmitting substrate fiber is selected from one of quartz fiber, glass fiber, and alumina fiber; 2) weighing a binder and placing it in the fiber separator; 3) setting the rotation speed and dissociation time of the fiber dissociator, adding deionized water into the fiber dissociator, and starting the fiber dissociator for dissociation; 4) After the dissociation is completed, the mixed solution in the fiber dissociator is poured into a square paper sheet former, and the filtration process is started to obtain a paper sheet; 5) The obtained paper sheet is subjected to hot pressing and drying to remove excess water, thereby obtaining a high temperature resistant microwave absorbing film.

2. The preparation method according to claim 1, characterized in that The length of the absorbent is 5 to 10 mm, and the length of the wave-transmitting substrate fiber is 6 to 12 mm.

3. The preparation method according to claim 1, characterized in that: The binder includes one or more of precipitated aramid fiber, polyvinyl alcohol, polyacrylate, and low-melting-point polypropylene fiber.

4. The preparation method according to claim 1 or 3, characterized in that: The mass proportion of the binder in the total amount of the absorbent, the wave-transmitting substrate fiber and the binder is 5% to 15%.

5. The preparation method according to claim 1, characterized in that: The rotation speed of the fiber disintegrator is set to 600-1000 r / min, and the disintegration time is set to 5-15 min.

6. The preparation method according to claim 1, characterized in that: Add 3 to 5 L of deionized water into the fiber disintegrator.

7. The preparation method according to claim 1, characterized in that: The temperature of the hot pressing drying is 90-120°C.

8. The preparation method according to claim 1, characterized in that: The thickness of the high temperature resistant wave absorbing film is 0.1-0.2 mm.

Images