Micro-nano fiber with infrared and radar compatible stealth performance and application thereof

Abstract

The present application relates to the technical field of nanofiber, in particular to a kind of micro-nanofiber with infrared and radar compatible stealth performance and application thereof.The micro-nanofiber is made of tin-doped zinc oxide micro-nanofiber by electrospinning method combined with heat treatment, wherein the chemical composition of the tin-doped zinc oxide micro-nanofiber is Zn 1‑ x Sn x O, and the micro-morphology is hollow fiber string ball structure, wherein x=0.03-0.07, the fiber diameter is 100-400 nm, and the ball diameter is 800-1000 nm.The micro-nanofiber of the present application has both infrared and radar stealth performance, and can meet the requirements of current weapon equipment for multi-spectrum compatible stealth.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanofiber, in particular to a micro-nanofiber with infrared and radar compatible stealth performance and application thereof. BACKGROUND

[0002] Stealth technology is mainly to suppress the energy emission and detectable characteristic signal of the target, reduce the probability of being found, identified, tracked, located and attacked, and achieve the purpose of protecting itself from enemy attack. Modern stealth technology mainly includes radar stealth, infrared stealth, laser stealth, visible light stealth, etc., but the above single stealth means cannot meet the actual demand. In order to improve the combat capability and survivability of weapon equipment, infrared / radar compatible stealth material has become the focus of research in various countries in the world. SUMMARY

[0003] In view of the above technical problems, the present application provides a micro-nanofiber with infrared and radar compatible stealth performance and application thereof. The micro-nanofiber has superior low infrared emissivity and microwave absorption performance, which can meet the requirements of compatible stealth of weapon equipment at present stage.

[0004] To solve the above technical problems, the present application adopts the following technical scheme:

[0005] In the first aspect, the present application provides a micro-nanofiber with infrared and radar compatible stealth performance, which is made of tin-doped zinc oxide micro-nanofiber by electrospinning method combined with heat treatment, wherein the chemical composition of the tin-doped zinc oxide micro-nanofiber is Zn 1-x Sn x O, and the micro-morphology is hollow fiber string ball structure, wherein x=0.03-0.07, the fiber diameter is 100-400 nm, and the ball diameter is 800-1000 nm.

[0006] Alternatively, the chemical composition of the tin-doped zinc oxide micro-nanofiber is Zn 0.95 Sn 0.05 O.

[0007] In the present application, when x=0.05, the tin-doped zinc oxide micro-nano fiber has low infrared emissivity of 0.549 and 0.648 in the infrared wave band of 3-5 μm and 8-14 μm, respectively. Meanwhile, when x=0.05, the matching thickness of the tin-doped zinc oxide micro-nano fiber is 2 mm, the minimum reflection loss value at 8.6 GHz is-32.0 dB, the absorption frequency lower than-10 dB is 7.7-9.4 GHz (representing the frequency range capable of absorbing 90% energy electromagnetic waves), and the bandwidth is 1.7 GHz, indicating that the tin-doped zinc oxide micro-nano fiber has excellent microwave absorption performance (radar). In summary, the tin-doped zinc oxide micro-nano fiber of the present application has superior low infrared emissivity and microwave absorption performance, can meet the requirements of weapon equipment on compatible stealth at present, and is a new type of infrared / radar compatible stealth material.

[0008] In a second aspect, the present application further provides a preparation method of the above micro-nano fiber, comprising the following steps:

[0009] Step 1, zinc acetate and tin chloride are added into anhydrous ethanol and mixed uniformly, then a mixed solution of polyvinylpyrrolidone and N,N-dimethylformamide is added, and stirring is performed for at least 24 h to obtain a precursor solution;

[0010] Step 2, the precursor solution is prepared into a precursor fiber by an electrospinning method, and the parameters of the electrospinning are as follows: at room temperature, the voltage is 15-17 kV, the inner diameter of the needle is 0.5 mm, the solution advancing rate is 0.1-0.2 mm / min, and the distance between the needle and the receiver is 10-15 cm;

[0011] Step 3, the precursor fiber is dried, then heated to 600-700℃ at a heating rate of 10-20℃·min -1 -1 under air atmosphere, and calcined for at least 2 h, and then naturally cooled to room temperature.

[0012] The preparation process of the micro-nano fiber of the present application is simple and has low economic cost, and the micro-nano fiber can be used as a functional filler in a coating to be coated on the surface of equipment and weapon, so that the equipment and weapon have infrared and radar compatible stealth performance, and the combat capability and survival capability of the equipment and weapon are greatly improved.

[0013] In the present application, the precursor fiber is heated to 600-700℃ at a heating rate of 10-20℃·min -1 -1, which can completely decompose the organic solvents and inorganic salts and impurities in the micro-nano fiber, so that the micro-nano fiber with excellent quality and in the form of hollow fiber string ball structure is obtained.

[0014] When the calcination temperature is too low (less than 600℃), the organic solvent and inorganic salt impurities in the micro-nano fiber are not completely decomposed, the obtained micro-nano fiber contains impurities, and the performance of the micro-nano fiber is affected.

[0015] When the calcination temperature is too high (greater than 700℃) and the heating rate is greater than 20℃·min -1 , the crystal grains of the micro-nano fiber are fused, the structure of the micro-nano fiber is damaged, the morphology of the hollow fiber string ball structure is changed, and therefore the calcination temperature is selected to be 600-700℃.

[0016] When the heating rate is less than 10℃·min -1 or greater than 20℃·min -1 , the morphology of the hollow string ball structure of the micro-nano fiber cannot be obtained or maintained, and therefore the heating rate is selected to be 10-20℃·min -1 .

[0017] Optionally, the zinc acetate is dihydrate zinc acetate; and the tin chloride is dihydrate tin chloride.

[0018] Optionally, the molar ratio of the dihydrate zinc acetate and the dihydrate tin chloride is (13-32):1, preferably (19-32):1.

[0019] The mass ratio of the N,N-dimethylformamide and the polyvinylpyrrolidone is (1-2):1, preferably 1:1.

[0020] The dihydrate zinc acetate and the dihydrate tin chloride account for 5%-10% of the mass of the precursor solution, preferably 5%.

[0021] Optionally, the inner diameter of the needle is 0.5mm; the solution advancing rate is 0.1-0.15mm / min, and the distance between the needle and the receiving plate is 12-15cm.

[0022] In a third aspect, the application further provides an equipment with infrared / radar compatible stealth performance, wherein a coating layer is coated on the surface of the equipment, and the micro-nano fiber obtained by the above method or the above micro-nano fiber is added as a functional filler in the coating layer, and the addition amount of the micro-nano fiber in the coating layer accounts for 4%-8% of the mass of the coating.

[0023] The micro-nano fiber is added as a functional filler in the coating layer on the surface of the equipment, so that the equipment has infrared and radar stealth performance, the combat capability and survival capability of the equipment are greatly improved, and the application has military strategic significance. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 XRD spectrum of Zn 0.95 Sn 0.05 O micro-nano fiber of Example 2;

[0025] Figure 2 Zn in Example 2 0.95 Sn 0.05 SEM images of O-micro nanofibers;

[0026] Figure 3 The reflection loss curve of the product obtained in Example 2 with a thickness of 2mm is shown. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] Example 1

[0029] This invention provides a method for preparing micro / nanofibers, comprising the following steps:

[0030] Step 1: Add analytical grade zinc acetate (CH3COO)2Zn·2H2O and analytical grade tin chloride SnCl2·2H2O in anhydrous ethanol at a molar ratio of 13:1 and mix thoroughly. Then add organic solution and stir for 24 hours to obtain precursor solution. In this case, (CH3COO)2Zn·2H2O and SnCl2·2H2O account for 5% of the mass of the precursor solution. The organic solution is obtained by mixing polyvinylpyrrolidone (PVP) and N,N-dimethylformamide in equal mass ratio.

[0031] Step 2: Add the precursor solution to the syringe and perform electrospinning under the following parameters: voltage 17 kV, needle inner diameter 0.5 mm, solution injection rate 0.1 mm / min, and distance between the needle and receiver 15 cm to obtain precursor fibers.

[0032] Step 3: Place the precursor fibers in a constant temperature drying oven and dry at 90 ℃ for 12 h, then place them in an intelligent temperature-controlled box-type resistance furnace and dry at 20 ℃·min in an air atmosphere. -1 The temperature was increased to 600℃ at a heating rate, calcined for 2 hours, and then naturally cooled to room temperature to obtain Zn. 0.93 Co 0.07 O-micro / nanofiber.

[0033] Example 2

[0034] This invention provides a method for preparing micro / nanofibers, comprising the following steps:

[0035] Step 1, analytical pure zinc acetate (CH3COO)2Zn·2H2O and analytical pure tin chloride SnCl2·2H2O in a molar ratio of 19:1 were added to anhydrous ethanol and mixed uniformly, then an organic solution was added and stirred for 24 h to obtain a precursor solution, wherein (CH3COO)2Zn·2H2O and SnCl2·2H2O accounted for 8% of the mass of the precursor solution; the organic solution was obtained by mixing equal mass ratios of polyvinylpyrrolidone (PVP) and N,N-dimethylformamide.

[0036] Step 2, the precursor solution was added to a syringe, and electrospinning was carried out at a voltage of 16 kV, a needle inner diameter of 0.5 mm, a solution advancing rate of 0.15 mm / min, and a distance between the needle and the receiver of 12 cm to prepare precursor fibers.

[0037] Step 3, the precursor fibers were placed in a constant temperature drying oven and dried at 90 ℃ for 12 h, then placed in an intelligent temperature control box type resistance furnace, and heated to 650 ℃ at a heating rate of 15 ℃·min -1 -1 under an air atmosphere, calcined for 2 h, naturally cooled to room temperature, and Zn 0.95 Sn 0.05 O micro-nano fibers were obtained.

[0038] Example 3

[0039] The application provides a preparation method of micro-nano fibers, comprising the following steps:

[0040] Step 1, analytical pure zinc acetate (CH3COO)2Zn·2H2O and analytical pure tin chloride SnCl2·2H2O in a molar ratio of 32:1 were added to anhydrous ethanol and mixed uniformly, then an organic solution was added and stirred for 24 h to obtain a precursor solution, wherein (CH3COO)2Zn·2H2O and SnCl2·2H2O accounted for 10% of the mass of the precursor solution; the organic solution was obtained by mixing equal mass ratios of polyvinylpyrrolidone (PVP) and N,N-dimethylformamide.

[0041] Step 2, the precursor solution was added to a syringe, and electrospinning was carried out at a voltage of 15 kV, a needle inner diameter of 0.5 mm, a solution advancing rate of 0.2 mm / min, and a distance between the needle and the receiver of 10 cm to prepare precursor fibers.

[0042] Step 3, the precursor fibers were placed in a constant temperature drying oven and dried at 90 ℃ for 12 h, then placed in an intelligent temperature control box type resistance furnace, and heated to 700 ℃ at a heating rate of 10 ℃·min -1 -1 under an air atmosphere, calcined for 2 h, naturally cooled to room temperature, and Zn 0.97 Sn 0.03O micro-nanofibers.

[0043] Comparative Example 1

[0044] Cobalt-doped zinc oxide nanofibers with a chemical composition of Zn 0.96 Co 0.04 O, wherein analytical pure (CH3COO)2Zn·2H2O and CO(NO3)2·6H2O were used as raw materials, and the stoichiometric ratio required by Zn 0.96 Co 0.04 O was used to weigh an appropriate amount of raw materials for mixing. The mixture was dissolved in a mixed solvent of equal mass ratio of N,N-dimethylformamide (DMF) and polyvinylpyrrolidone (PVP), and magnetically stirred for 6 h to prepare a precursor solution, wherein the mass fractions of PVP and metal salt were 6.5% respectively. The precursor solution was loaded into a syringe with a stainless steel needle (type 23G), and Zn 0.96 Co 0.04 O / PVP fibers were prepared by electrospinning under the experimental conditions of a solution supply rate of 0.2 mL / h, a voltage of 20 kV, and a distance between the needle and the receiving plate of 20 cm.

[0045] After drying, the precursor fibers prepared by electrospinning were placed in an intelligent temperature-controlled resistance furnace and calcined at a heating rate of 1℃·min -1 -1 to 600℃ for 2h, and then cooled to room temperature with the furnace, to obtain the target product Zn 0.96 Co 0.04 O nanofibers. For details, see the paper ([1] Wang X, Zhao F, Wang J. Electrospinning of Zn 1-x Co x O nanofibers and their wave-absorbing properties [J]. Journal of the Chinese Ceramic Society, 2020, 48(02): 161-168. DOI:10.14062 / j.issn.0454-5648.20190376).

[0046] Comparative Example 2

[0047] Sn 0.84 Sm 0.08 Sb 0.08 O2 micro-nanofibers, using SnCl2·2H2O, Sm(NO3)3·6H2O, and SbCl3 as raw materials, according to Sn 0.84 Sm 0.08 Sb 0.08A solution A was prepared by dissolving the raw materials in anhydrous ethanol in stoichiometric ratio. A solution B was prepared by dissolving polyvinylpyrrolidone (PVP) in equal mass of N,N-dimethylformamide (DMF). Solution A and B were then mixed and stirred for 12 hours to obtain a precursor solution C. The precursor solution C was then transferred into a syringe with a stainless steel needle for electrospinning. The electrospinning parameters were as follows: temperature 25°C, humidity 50% RH, voltage 20 kV, needle type 21G, distance between needle and collector 20 cm, solution feeding rate 0.1 mL / h, and collector rotation rate 140 r / min.

[0048] The precursor nanofibers were first dried in a vacuum drying oven at 100°C for 12 hours, and then calcined in a temperature-controlled electric resistance furnace at a rate of 1°C·min -1 -1 to 600°C for 2 hours, and then cooled to room temperature to obtain the target product Sn 0.84 Sm 0.08 Sb 0.08 O2 micro-nanofibers. See the paper ([2] Xia Yuanjia, Zhao Fang, Li Zhizun, et al. Preparation of Sn 1-x-y Sm x Sb y O2 micro-nanofibers and their infrared and laser compatible stealth properties [J / OL]. Chinese Journal of Rare Earths).

[0049] Comparative Example 3

[0050] In this comparative example, the molar ratio of (CH3COO)2Zn·2H2O to SnCl2·2H2O was 10:1, and the rest of the preparation method and raw material amount were the same as in Example 2.

[0051] Comparative Example 4

[0052] In this comparative example, the molar ratio of (CH3COO)2Zn·2H2O to SnCl2·2H2O was 35:1, and the rest of the preparation method and raw material amount were the same as in Example 2.

[0053] Comparative Example 5

[0054] In this comparative example, the electrospinning voltage was 18 kV, the solution feeding rate was 0.3 mL / h, and the distance between the needle and the collector was 18 cm, and the rest of the preparation method and raw material amount were the same as in Example 2.

[0055] Comparative Example 6

[0056] In this comparative example, the heating rate was 3°C·min -1 -1, and the rest of the preparation method and raw material amount were the same as in Example 2.

[0057] Comparative Example 7

[0058] Comparative Example 7 has a heating rate of 50℃·min -1 The remaining preparation method and raw material dosage are the same as Example 2.

[0059] Comparative Example 8

[0060] Zn 0.96 Ce 0.04 O nanofibers, using analytical pure (CH3COO)2Zn·2H2O solution and Ce(NO3)3·6H2O solution as raw materials, according to the molecular formula Zn 0.96 Ce 0.04 O required stoichiometric ratio of raw materials is weighed and mixed. The mixture is dissolved in a mixed solvent of equal mass ratio of N,N-dimethylformamide (DMF) and polyvinylpyrrolidone (PVP), and magnetically stirred for 6h to prepare a precursor solution.

[0061] The precursor solution is loaded into a syringe with a stainless steel needle (type 23G), and the precursor Zn 0.96 Ce 0.04 O / PVP fibers are prepared by electrospinning under the experimental conditions of a solution supply rate of 0.2mL / h, a voltage of 20kV, and a distance between the needle and the receiving plate of 20cm.

[0062] After drying the precursor fibers prepared by the above electrospinning, they are placed in an intelligent temperature-controlled box-type resistance furnace, and heated to 600℃ at a heating rate of 1℃·min -1 0.96 Ce 0.04 O nanofibers. For details, see the paper ([3] Wang Xin-kun, Zhao Fang, Wang Jian-jiang. Electrospinning preparation of Zn 1-x Ce x O nanofibers and their infrared radar compatible stealth performance [J]. Materials Review, 2019, 33(S2): 83-88).

[0063] Verification Example 1

[0064] 1. In order to better illustrate the characteristics of the tin-doped zinc oxide micro-nanofibers prepared by the present application, the tin-doped zinc oxide micro-nanofibers prepared in Example 2 are analyzed by XRD and SEM.

[0065] Figure 1 The XRD spectrum of the Zn 0.95 Sn 0.05 O micro-nanofibers of Example 2; from Figure 1 ​It can be seen that diffraction peaks are observed at (100), (002), (101), (102), (110) and (103), which are consistent with JCPDS card No. 36-1451, and no other diffraction peaks are observed in the spectrum, indicating that the product is pure, and the chemical composition of the product is Zn 0.95 Sn 0.05 O, and the impurity content is below the detection limit.

[0066] Figure 2 Zn 0.95 Sn 0.05 O micro-nano fibers, wherein a, b, c and d are SEM photos at different magnifications. From the SEM photos, it can be seen that the morphology of the Zn Figure 2 Sn 0.95 Sn 0.05 O micro-nano fibers is micro-nano hollow fiber string ball structure, the fiber diameter is 100-400 nm, and the ball diameter is 800-1000 nm. The Zn 0.95 Sn 0.05 O micro-nano fibers form a three-dimensional conductive network by cross-linking the hollow fiber string ball structures, which can effectively reduce the resistivity and thermal conductivity to reduce the amount of infrared radiation, so that the Zn 0.95 Sn 0.05 O micro-nano fibers have lower infrared emissivity; at the same time, the hollow fiber string ball structure of the Zn 0.95 Sn 0.05 O micro-nano fibers also causes multiple reflections of incident electromagnetic waves, thereby producing resonance loss, enhancing the attenuation of incident electromagnetic waves, so that the Zn 0.95 Sn 0.05 O micro-nano fibers have good electromagnetic wave absorption performance.

[0067] 2, The products obtained in Examples 1-3 and Comparative Examples 2-8 were analyzed for infrared emissivity, and the results are shown in Table 1.

[0068] Table 1 Infrared emissivity of products obtained in Examples 1-3 and Comparative Examples 2-8 in the infrared waveband of 3-5 μm and 8-14 μm

[0069]

[0070] As can be seen from Table 1, compared with the infrared emissivity of the products obtained in Comparative Examples 2-8, the products obtained in Examples 1-3 have lower infrared emissivity.

[0071] 3, The wave absorption performance of the products obtained in Example 2 and Comparative Examples 1 and 8 was analyzed, and the results are shown in Table 2.

[0072] Table 2 Reflectance loss values of products obtained in Example 2 and Comparative Examples 1 and 8 at a matching thickness of 2 mm

[0073]

[0074] As can be seen from Table 2, the product obtained in Example 2 has a lower reflection loss value compared with the reflection loss values of the products obtained in Comparative Examples 1 and 8.

[0075] Figure 3 The reflection loss curve of the product obtained in Example 2 is matched at a thickness of 2 mm. Figure 3 It can be seen that, at a matched thickness of 2 mm, the Zn 0.95 Sn 0.05 The minimum reflection loss of the Zn 0.95 Sn 0.05 O micro-nano fiber is -32.0 dB at 8.6 GHz, and the absorption frequency below -10 dB is 7.7-9.4 GHz (representing the frequency range capable of absorbing 90% of electromagnetic waves), and the bandwidth is 1.7 GHz. It shows that the Zn

[0076] The tin-doped zinc oxide micro-nano fiber of the present application has superior low infrared emissivity and microwave absorption performance, which may be because: the hollow fiber string ball structure of the Zn 0.95 Sn 0.05 O micro-nano fiber is crosslinked with each other to form a three-dimensional conductive network, which can effectively reduce the resistivity and thermal conductivity to reduce the amount of infrared radiation, so that the Zn 0.95 Sn 0.05 O micro-nano fiber has lower infrared emissivity; at the same time, the hollow fiber string ball structure of the Zn 0.95 Sn 0.05 O micro-nano fiber also causes multiple reflections of incident electromagnetic waves, thereby producing resonance loss, enhancing the attenuation of incident electromagnetic waves, so that the Zn 0.95 Sn 0.05 O micro-nano fiber has good electromagnetic wave absorption performance.

[0077] In summary, the tin-doped zinc oxide micro-nano fiber of the present application has superior low infrared emissivity and microwave absorption performance, and can meet the current requirements of weapon equipment for compatible stealth, and is a new type of infrared / radar compatible stealth material.

[0078] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements or improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A micro / nanofiber with infrared and radar-compatible stealth properties, characterized in that, The micro / nanofibers are prepared by electrospinning a precursor solution to form precursor fibers, which are then heat-treated to produce tin-doped zinc oxide micro / nanofibers. The chemical composition of the tin-doped zinc oxide micro / nanofibers is Zn. 1-x Sn x O. The microstructure is a hollow fiber sphere structure, where x = 0.03 to 0.07, the fiber diameter is 100 to 400 nm, and the sphere diameter is 800 to 1000 nm. The precursor solution is prepared as follows: zinc acetate and tin chloride are added to anhydrous ethanol and mixed evenly, then a mixed solution of polyvinylpyrrolidone and N,N-dimethylformamide is added, and the mixture is stirred for at least 24 h, wherein the mass ratio of polyvinylpyrrolidone to N,N-dimethylformamide is 1:1~2; the heat treatment step is as follows: the precursor fiber is dried, and then subjected to heat treatment at 10~20 °C·min in an air atmosphere. -1 The temperature is increased to 600-700 °C at a heating rate, calcined for at least 2 hours, and then naturally cooled to room temperature.

2. The micro / nanofiber with infrared and radar-compatible stealth properties as described in claim 1, characterized in that, The chemical composition of the tin-doped zinc oxide micro / nanofibers is Zn. 0.95 Sn 0.05 O.

3. A method for preparing micro / nanofibers as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Add zinc acetate and tin chloride to anhydrous ethanol and mix well. Then add a mixed solution of polyvinylpyrrolidone and N,N-dimethylformamide and stir for at least 24 h to obtain the precursor solution. Step 2: The precursor solution is electrospinned to obtain precursor fibers. The electrospinning parameters are: at room temperature, voltage 15-17 kV, needle inner diameter 0.5 mm, solution propulsion rate 0.1-0.2 mm / min, and distance between needle and receiver 10-15 cm. Step 3: Dry the precursor fibers, and then heat them in air at 10–20 °C / min. -1 The temperature is increased to 600-700 °C at a heating rate, calcined for at least 2 hours, and then naturally cooled to room temperature to obtain the product.

4. The preparation method according to claim 3, characterized in that, The zinc acetate is zinc acetate dihydrate; the tin chloride is tin chloride dihydrate.

5. The preparation method according to claim 4, characterized in that, The molar ratio of zinc acetate dihydrate to tin chloride dihydrate is (13-32):1; The mass ratio of N,N-dimethylformamide to polyvinylpyrrolidone is (1-2):1; and / or The zinc acetate dihydrate and tin chloride dihydrate account for 5% to 10% of the mass of the precursor solution.

6. The preparation method according to claim 5, characterized in that, The molar ratio of zinc acetate dihydrate to tin chloride dihydrate is (19-32):1; The zinc acetate dihydrate and stannous chloride dihydrate constitute 5% of the precursor solution by mass; and / or The mass ratio of polyvinylpyrrolidone to N,N-dimethylformamide is 1:

1.

7. The preparation method according to claim 3, characterized in that, The needle has an inner diameter of 0.5 mm; the solution propulsion rate is 0.1–0.15 mm / min; and the distance between the needle and the receiving plate is 12–15 cm.

8. A piece of equipment with infrared / radar compatible stealth capabilities, characterized in that, The surface of the equipment is coated with a coating containing micro / nanofibers as described in claim 1 or 2, or micro / nanofibers obtained by the preparation method described in any one of claims 3-6, as a functional filler.

9. The equipment with infrared / radar compatible stealth capabilities as described in claim 8, characterized in that, In the coating, the amount of micro / nanofibers added accounts for 4% to 8% of the coating mass.

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