A method for integrating a woven high-temperature broadband stealth grid structure wave-absorbing material

Abstract

The application discloses a method for integrally weaving high-temperature wide-band stealth grid structure wave-absorbing material, and belongs to the technical field of high-speed aircraft stealth. In the application, silicon carbide fiber bundles with different resistivities are used as warp yarns and weft yarns, a three-dimensional weaving shallow-interlaced bending structure is adopted, 5-15 warp yarns and 5-15 weft yarns are woven into a group, the resistivity of the outer circle warp yarns and weft yarns is controlled to be smaller than that of the inner warp yarns and weft yarns, a grid structure is formed on the resistivity arrangement of the warp-weft interlaced plane, meanwhile, a three-layer structure is woven, the resistivity in the thickness direction is arranged from high to low, and a gradient structure is formed, the above weaving is repeated, and a high-temperature wide-band stealth grid structure wave-absorbing material preform with in-plane grid mixed weaving and out-of-plane gradient mixed weaving is obtained. The application realizes the integration of ceramic-based interference type wave-absorbing material, and has the advantages of high-temperature resistance, good anti-aging performance and high strength.

Description

TECHNICAL FIELD

[0001] The application relates to a method for integrally weaving a high-temperature broadband stealth grid structure wave-absorbing material, and belongs to the technical field of high-speed aircraft stealth. BACKGROUND

[0002] Wave-absorbing material technology has become an important technical approach to improving the radar stealth performance of contemporary weapon equipment. As a very important reinforcing fiber in the ceramic matrix composite material system, silicon carbide fiber not only has excellent properties such as high temperature resistance, high modulus and high strength, but also has a wide range of electrical performance control, and can adjust the wave-absorbing performance of silicon carbide fiber according to the sintering temperature, so as to serve as different functional phases in the wave-absorbing material. Therefore, silicon carbide fiber has become an important research object of high-temperature wave-absorbing structural materials. In order to realize broadband wave-absorbing function, a multilayer electrical performance matching design scheme is often used for high-temperature wave-absorbing structural materials; for three-dimensional weaving process, it is not easy to realize the interlayer distribution of different electrical performance fibers due to the through characteristics of the fibers in the thickness direction.

[0003] The interference type wave-absorbing material has the advantages of simple structure, strong designability of wave-absorbing performance, wide absorption frequency band and strong frequency selectivity. The existing interference type wave-absorbing material is usually composed of an electrically conductive interference body and a polymer-based wave-transparent material, and has problems of poor high temperature resistance, poor aging resistance, low strength and short service life, and is difficult to serve in various harsh environments for a long time. Ceramic materials have the advantages of high strength, corrosion resistance, high temperature resistance and aging resistance, but the preparation of ceramic matrix composites is difficult and the process is complex, which greatly limits the research progress of ceramic matrix interference type wave-absorbing materials. SUMMARY

[0004] [TECHNICAL PROBLEM]

[0005] The existing interference type wave-absorbing material has problems of poor high temperature resistance, poor aging resistance, low strength and short service life.

[0006] The ceramic matrix material has good performance, but the preparation process is too complex.

[0007] [TECHNICAL SCHEME]

[0008] In order to solve the above problems, the application selects silicon carbide fibers with different electrical properties to reasonably match and integrally weave a special structure of a preform; at the same time, the warp and weft yarns of each layer are reasonably distributed to form an overall woven heterogeneous structure of "in-plane grid mixed weaving" and "out-of-plane gradient mixed weaving", which can improve the wave-absorbing performance and improve the mechanical properties.

[0009] The first object of the application is to provide a method for integrally weaving a high-temperature broadband stealth grid structure wave-absorbing material preform, which comprises the following steps:

[0010] (1) Preparation of silicon carbide fiber bundle:

[0011] Depositing pyrolytic carbon on the surface of the silicon carbide fiber bundle by chemical vapor deposition to achieve different thickness of carbon layer interface, and obtaining silicon carbide fiber bundles with different resistivity;

[0012] (2) Integrated weaving:

[0013] The silicon carbide fiber bundles with different resistivity are used as warp and weft, and a three-dimensional woven shallow-interlaced bending structure is adopted, 5-15 bundles of warp and 5-15 bundles of weft are woven into a group, the resistivity of the outer circle warp and weft is controlled to be smaller than that of the inner warp and weft, so that the interlaced surface of the warp and weft forms a grid structure in the resistivity arrangement; at the same time, a three-layer structure is woven, so that the resistivity in the thickness direction is arranged from high to low, forming a gradient structure; the above weaving is repeated to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material preform with in-plane grid mixed weaving and out-of-plane gradient mixed weaving.

[0014] In an embodiment of the present application, the chemical vapor deposition method of step (1) is specifically:

[0015] The silicon carbide fiber bundle is placed in the furnace, nitrogen gas is introduced for protection and heating, after the temperature is stabilized for 30 min, the nitrogen gas is stopped, propane gas is introduced, the power is cut off after the reaction time reaches the deposition time, the propane gas is stopped, the nitrogen gas is introduced to exhaust the propane gas, and the silicon carbide fiber bundle is taken out after cooling to room temperature in the nitrogen environment;

[0016] The chemical vapor deposition temperature is 1000℃, the pressure in the furnace is set to 10kPa, and the propane and nitrogen gas pressure ratio is 1:3; the chemical vapor deposition time is 10h-60h, and the carbon interface with a thickness of 0.2-2μm is formed.

[0017] In an embodiment of the present application, the resistivity of the silicon carbide fiber bundle of step (1) is 10 1 -10 6 Ω·cm, the fineness is 1-5 K, the single filament tensile strength is not less than 2.8GPa, and the bundle tensile strength is not less than 2.5GPa.

[0018] In an embodiment of the present application, the outer circle warp and weft of step (2) is 1-2 silicon carbide fiber bundles.

[0019] In an embodiment of the present application, each layer of the gradient structure of step (2) contains 1-3 layers of weft.

[0020] In an embodiment of the present application, the first layer of the gradient structure in step (2) is used as a matching layer, the outer circle warp and weft are selected from silicon carbide fiber bundles with a resistivity of 10 5 Ω·cm, and the inner warp and weft are selected from silicon carbide fiber bundles with a resistivity of 106 Ω·cm.

[0021] In one embodiment of the present application, the second layer of the gradient structure in step (2) is used as a loss layer, and the outer warp and weft yarns are selected from silicon carbide fiber bundles with a resistivity of 10 3 Ω·cm, and the inner warp and weft yarns are selected from silicon carbide fiber bundles with a resistivity of 10 4 Ω·cm.

[0022] In one embodiment of the present application, the warp density of the woven fabric in step (2) is 6-9 bundles / cm, and the weft density is 4-6 bundles / cm.

[0023] In one embodiment of the present application, the third layer of the gradient structure in step (2) is used as a reflection layer, and the outer warp and weft yarns are selected from silicon carbide fiber bundles with a resistivity of 10 1 Ω·cm, and the inner warp and weft yarns are selected from silicon carbide fiber bundles with a resistivity of 10 2 Ω·cm.

[0024] The second object of the present application is a high-temperature wide-frequency stealth grid structure wave-absorbing material preform prepared by the method of the present application.

[0025] In one embodiment of the present application, the weft yarns of the high-temperature wide-frequency stealth grid structure wave-absorbing material preform have 6-12 layers, and the preform has a thickness of 4-10 mm, a length of 100-1000 mm, and a width of 100-1000 mm.

[0026] The third object of the present application is to provide a method for preparing a high-temperature wide-frequency stealth grid structure wave-absorbing material, comprising the following steps:

[0027] immersing the high-temperature wide-frequency stealth grid structure wave-absorbing material preform in a polycarbosilane (PCS) solution, taking it out, heating and keeping warm, high-temperature pyrolysis, to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material.

[0028] In one embodiment of the present application, the high-temperature pyrolysis is for densification treatment.

[0029] In one embodiment of the present application, the immersion and high-temperature pyrolysis can be repeated multiple times.

[0030] In one embodiment of the present application, the polycarbosilane (PCS) solution is composed of toluene and polycarbosilane in a mass ratio of 1:1.

[0031] In one embodiment of the present application, the immersion is carried out at 20-30°C for 1-3 h.

[0032] In an embodiment of the present application, the heating and keeping warm is heating to 145-155 DEG C at a heating rate of 3-7 DEG C / min in an argon environment and keeping warm for 1-5 h.

[0033] In an embodiment of the present application, the high-temperature pyrolysis is heating at 1300-1500 DEG C for 1-2 h.

[0034] A fourth object of the present application is a high-temperature wide-frequency stealth grid structure wave-absorbing material prepared by the method of the present application.

[0035] In an embodiment of the present application, the high-temperature wide-frequency stealth grid structure wave-absorbing material has a density of 2.2 g / cm 3 -2.4 g / cm 3 , and a fiber volume fraction of 40-50%.

[0036] A fifth object of the present application is the use of the high-temperature wide-frequency stealth grid structure wave-absorbing material of the present application in the field of aerospace.

[0037] [Advantages]

[0038] (1) Compared with ordinary single-layer or multi-layer wave-absorbing materials, the high-temperature wide-frequency stealth grid structure wave-absorbing material of the present application uses silicon carbide fiber bundles with different resistivities to form a grid structure on a single layer, thereby improving the wave-absorbing capacity, and at the same time, a resistivity gradient arrangement is formed in the thickness direction, meeting the requirements of different functional phases; at the same time, the silicon carbide fibers have good high-temperature resistance and mechanical properties, and are subjected to multiple dense composite sintering with a low-density, high-strength silicon carbide matrix, so that the service temperature can reach 1500 DEG C or above, realizing the effect of "integrated woven ceramic-based interference type wave-absorbing material with good high-temperature resistance, anti-aging performance and high strength".

[0039] (2) The method of the present application can be applied to the manufacture of various high-temperature wave-absorbing materials, and has a wide application range; and can be used for industrial production.

[0040] (3) The high-temperature wide-frequency stealth grid structure wave-absorbing material prepared by the present application has an absolute value of the maximum absorption peak of 32.3 dB or more, four effective wave-absorbing frequency bands, a temperature resistance limit of 1500 DEG C or more, a bending strength of 155 MPa or more, and a bending strength retention rate of 60% or more. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A structure diagram of the high-temperature wide-frequency stealth grid structure wave-absorbing material preform of Example 1, wherein 1: matching layer; 2: loss layer; 3: reflection layer.

[0042] Figure 2A single-layer structure schematic diagram of the high-temperature wide-bandwidth stealth grid structure wave-absorbing material preform in Example 1. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present application are described below, and it should be understood that the embodiments are used to better explain the present application, and are not used to limit the present application.

[0044] Test method:

[0045] 1. High-temperature resistance test:

[0046] In a certain high-temperature sintering furnace, the material is continuously kept at a high temperature for 24 hours, and the average linear shrinkage rate of the material in the x, y, and z directions is less than 5%, which can be considered as the material can withstand the high temperature.

[0047] 2. Aging resistance test:

[0048] After being kept at 1500℃ for 24 hours, the bending strength of the material is tested, and compared with the bending strength before treatment, the strength retention rate is calculated.

[0049] 3. Wave-absorbing performance test:

[0050] The People's Republic of China Textile Industry Standard FZ / T01139-2017 “Textile Microwave Resistance Performance Test Method Rectangular Waveguide Method” is adopted.

[0051] 4. Strength performance test:

[0052] The People's Republic of China Standard GB / T659-2006 “Fine Ceramic Bending Strength Test Method” is adopted.

[0053] Raw materials used in the examples:

[0054] Silicon carbide fiber bundle: fineness 3K, single filament tensile strength not less than 2.8GPa, bundle filament tensile strength not less than 2.5GPa;

[0055] Polycarbosilane (PCS) solution: prepared by mixing toluene and polycarbosilane in a mass ratio of 1:1.

[0056] Example 1

[0057] A method for preparing an integrated woven high-temperature wide-bandwidth stealth grid structure wave-absorbing material preform, comprising the following steps:

[0058] (1) Preparation of silicon carbide fiber bundle:

[0059] Propane as a deposition carbon source, nitrogen as auxiliary gas; the silicon carbide fiber bundle is put into the furnace, nitrogen is introduced, the pressure in the furnace is set to 10 kPa, heated to 1000℃ at 10℃ / min, after the temperature is stable for 30 min, stop introducing nitrogen, introduce propane gas, the gas pressure ratio of propane and nitrogen is set to 1:3, after the reaction time reaches the deposition time, cut off the power, stop introducing propane gas, introduce nitrogen to exhaust propane gas, cool to room temperature under nitrogen environment, then take out the silicon carbide fiber bundle;

[0060] The resistivity of the silicon carbide fibers sintered under different deposition times is shown in Table 1;

[0061] Table 1

[0062]

[0063] (2) Integrated weaving:

[0064] A three-dimensional woven shallow intersection bending structure is adopted, the warp density is 8 bundles / cm, the weft density is 6 bundles / cm, each layer is a group of 5 bundles of warp yarns and 5 bundles of weft yarns interwoven to form a grid structure, and the weft yarn layer is 6 layers, and 2 layers of weft yarns are taken as a group as a matching layer, a loss layer and a reflection layer respectively;

[0065] The first and fifth bundles of warp and weft yarns on the outer ring of the matching layer grid structure are selected to have a silicon carbide fiber bundle resistivity of 10 5 Ω·cm, and the second, third and fourth bundles of warp and weft yarns in the inner part are selected to have a silicon carbide fiber bundle resistivity of 10 6 Ω·cm;

[0066] The first and fifth bundles of warp and weft yarns on the outer ring of the loss layer grid structure are selected to have a silicon carbide fiber bundle resistivity of 10 3 Ω·cm, and the second, third and fourth bundles of warp and weft yarns in the inner part are selected to have a silicon carbide fiber bundle resistivity of 10 4 Ω·cm;

[0067] The first and fifth bundles of warp and weft yarns on the outer ring of the reflection layer grid structure are selected to have a silicon carbide fiber bundle resistivity of 10 1 Ω·cm, and the second, third and fourth bundles of warp and weft yarns in the inner part are selected to have a silicon carbide fiber bundle resistivity of 10 2 Ω·cm;

[0068] Repeat the above weaving to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material preform with in-plane grid mixed weaving and out-of-plane gradient mixed weaving; wherein the preform has a thickness of 4 mm, a length of 100 mm and a width of 100 mm.

[0069] Example 2

[0070] A method for preparing a high-temperature wide-frequency stealth grid structure wave-absorbing material, comprising the following steps:

[0071] The high-temperature wide-frequency stealth grid structure wave-absorbing material preform of Example 1 was immersed in a polycarbosilane (PCS) solution at 25℃ for 1h, taken out, heated to 150℃ at a temperature increasing rate of 5℃ / min in an argon environment and kept for 3h, and then pyrolyzed at 1400℃ for 1h to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material.

[0072] Example 3

[0073] The warp density was adjusted to 6 ends / cm and the weft density was adjusted to 4 ends / cm in step (2) of Example 1, and other conditions were the same as in Examples 1 and 2 to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material.

[0074] Example 4

[0075] The weft yarn layer was adjusted to 9 layers in step (2) of Example 1, and 3 layers of weft yarns were taken as a group as a matching layer, a loss layer and a reflection layer, respectively, and other conditions were the same as in Examples 1 and 2 to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material.

[0076] Comparative Example 1

[0077] In step (2) of Example 1, the matching layer warp and weft yarns were both selected to be silicon carbide fiber bundles with a resistivity of 10 5 Ω·cm, the loss layer warp and weft yarns were both selected to be silicon carbide fiber bundles with a resistivity of 10 3 Ω·cm, and the reflection layer warp and weft yarns were both selected to be silicon carbide fiber bundles with a resistivity of 10 1 Ω·cm.

[0078] Other conditions were the same as in Examples 1 and 2 to obtain a composite material.

[0079] Comparative Example 2

[0080] In step (2) of Example 1, the matching layer, the loss layer and the reflection layer were all taken as a group to form a grid structure with a surface of 5 warp yarns and 5 weft yarns interwoven continuously, the first and fifth warp and weft yarns on the outer ring were selected to be silicon carbide fiber bundles with a resistivity of 10 4 Ω·cm, and the second, third and fourth warp and weft yarns in the inner part were selected to be silicon carbide fiber bundles with a resistivity of 10 1 Ω·cm.

[0081] Other conditions were the same as in Examples 1 and 2 to obtain a composite material.

[0082] Comparative Example 3

[0083] In Example 2, the polycarbosilane (PCS) solution was replaced by polymethylsilane, and the specific operation was as follows:

[0084] The high-temperature broadband stealth grid structure wave-absorbing material preform of Example 1 is immersed in a polymethylsilane solution at 25℃ for 1h, and the polymethylsilane solution is prepared by mixing divinylbenzene and polymethylsilane at a mass ratio of 1:5.

[0085] Other conditions are the same as in Example 2, and a composite material is obtained.

[0086] Comparative Example 4

[0087] The grid structure in step (2) of Example 1 is adjusted to a strip-shaped spacing structure.

[0088] The specific weaving is as follows:

[0089] The weft yarn of the matching layer uses carbonized silicon fiber bundles with resistivity of 10 5 Ω·cm and 10 6 Ω·cm are alternately inserted, and the warp yarn uses carbonized silicon with resistivity of 10 6 Ω·cm.

[0090] The weft yarn of the loss layer uses carbonized silicon fiber bundles with resistivity of 10 3 Ω·cm and 10 4 Ω·cm are alternately inserted, and the warp yarn uses carbonized silicon with resistivity of 10 4 Ω·cm.

[0091] The weft yarn of the reflection layer uses carbonized silicon fiber bundles with resistivity of 10 1 Ω·cm and 10 2 Ω·cm are alternately inserted, and the warp yarn uses carbonized silicon with resistivity of 10 2 Ω·cm.

[0092] Other conditions are the same as in Examples 1 and 2, and a composite material is obtained.

[0093] Comparative Example 5

[0094] The carbonized silicon fiber in Example 1 is adjusted to Nicalon carbonized silicon fiber with different resistivity, and is woven in the same resistivity arrangement as in Example 1.

[0095] Other conditions are the same as in Examples 1 and 2, and a composite material is obtained.

[0096] The composite materials obtained in the examples and comparative examples are tested for performance, and the test structure is shown in Table 2:

[0097] As can be seen from Table 2:

[0098] (1) The composite materials prepared in Examples 2-4 have excellent high-temperature resistance, reaching 1600℃; have multiple effective wave-absorbing frequency bands, high maximum absorption peaks, and excellent wave-absorbing performance; and have a bending strength of 155MPa and a bending strength retention rate of more than 60%.

[0099] (2) Compared with Example 2 and Comparative Examples 1 and 2, the wave-absorbing performance of the grid structure or the gradient structure alone greatly decreases;

[0100] (3) Compared with Example 2 and Comparative Example 3, the effective wave-absorbing frequency range is reduced and the bending strength greatly decreases when polymethylsilane is used to replace polycarbosilane (PCS) solution;

[0101] (4) Compared with Example 2 and Comparative Example 4, the effective wave-absorbing frequency range is reduced, the maximum absorption peak is lowered, and the wave-absorbing performance greatly decreases when the strip interval structure is used;

[0102] (5) Compared with Example 2 and Comparative Example 5, the effective wave-absorbing frequency range is reduced, the maximum absorption peak is lowered, and the wave-absorbing performance greatly decreases when Nicalon silicon carbide fibers with different resistivities are used; and the bending strength also greatly decreases.

[0103] Table 2

[0104]

[0105] Although the present application has been disclosed with reference to the preferred embodiments, it is not intended to limit the application, and any person skilled in the art can make various modifications and improvements without departing from the spirit and scope of the application, and the protection scope of the present application should be defined by the claims.

Claims

1. A method for integrating a woven high-temperature broadband stealth grid structure wave-absorbing material preform, characterized in that, Comprising the following steps: (1) Preparation of silicon carbide fiber bundle: The pyrolytic carbon is deposited on the surface of the silicon carbide fiber bundle by chemical vapor deposition to realize the interface of carbon layer with different thickness, and the silicon carbide fiber bundle with different resistivity is obtained; wherein the chemical vapor deposition temperature is 1000 DEG C, the furnace pressure is set to 10 kPa, the pressure ratio of propane and nitrogen is 1:3; the chemical vapor deposition time is 10-60 h, the carbon interface with a thickness of 0.2-2 um is formed, and the resistivity of the silicon carbide fiber bundle is 10 1 -10 6 Ω·cm, the fineness is 1-5 K, the single filament tensile strength is not less than 2.8 GPa, and the bundle filament tensile strength is not less than 2.5 GPa; (2) Integrated weaving: Different resistivity silicon carbide fiber bundles are used as warp and weft yarns, and a three-dimensional woven shallow-interlaced bending structure is adopted, with 5-15 bundles of warp yarns and 5-15 bundles of weft yarns woven into a group. By controlling the resistivity of the outer circle warp and weft yarns to be smaller than that of the inner warp and weft yarns, a grid structure is formed in the resistivity arrangement of the warp and weft yarn interwoven surface. At the same time, a three-layer structure is woven, so that the resistivity in the thickness direction is arranged from high to low, forming a gradient structure. The above weaving is repeated to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material preform with in-plane grid mixed weaving and out-of-plane gradient mixed weaving.

2. The method of claim 1, wherein, The first layer of the gradient structure in step (2) is used as a matching layer, the outer warp yarn and weft yarn are selected from silicon carbide fiber bundles with a resistivity of 10 5 Ω·cm, and the inner warp yarn and weft yarn are selected from silicon carbide fiber bundles with a resistivity of 10 6 Ω·cm.

3. The method of claim 1, wherein, The second layer of the gradient structure in step (2) is used as a loss layer, the outer warp yarn and weft yarn are selected from silicon carbide fiber bundles with an electrical resistivity of 10 3 Ω·cm, and the inner warp yarn and weft yarn are selected from silicon carbide fiber bundles with an electrical resistivity of 10 4 Ω·cm.

4. The method of claim 1, wherein, The third layer of the gradient structure in step (2) is used as a reflecting layer, the warp yarn and weft yarn of the outer circle are selected from silicon carbide fiber bundles with an electrical resistivity of 10 1 Ω·cm, and the inner warp yarn and weft yarn are selected from silicon carbide fiber bundles with an electrical resistivity of 10 2 Ω·cm.

5. The method of claim 1, wherein, The warp density of the woven in step (2) is 6-9 bundles / cm, and the weft density is 4-6 bundles / cm.

6. The high-temperature wide-frequency stealth grid structure wave-absorbing material preform prepared by the method of any one of claims 1-5.

7. A method for preparing a high-temperature wide-band stealthy grating structure wave-absorbing material, characterized in that, Comprising the following steps: The high-temperature wide-frequency stealth grid structure wave-absorbing material preform of claim 6 is immersed in a polycarbosilane (PCS) solution, taken out, heated and kept warm, and pyrolyzed to obtain a high-temperature wide-frequency stealth grid structure wave-absorbing material.

8. The high-temperature wide-frequency stealth grid structure wave-absorbing material prepared by the method of claim 7.

9. The application of the high-temperature wide-frequency stealth grid structure wave-absorbing material of claim 8 in the field of aerospace.

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