KR102621975B1 - Ceramic composite for Radar absorbing at high temperature and the manufacturing method thereof - Google Patents

Abstract

The present disclosure relates to a ceramic composite for absorbing high-temperature radio waves and a method of manufacturing the same, and more specifically, to its application to an aircraft for low observable purposes. The ceramic composite and its manufacturing method according to the present disclosure are manufactured by impregnating SiC-based fabric with a polysiloxane resin having a reactive group, and can manufacture a composite that satisfies the mechanical properties of strength and lightness for flight purposes while maintaining dielectric properties even at high temperatures. there is.

Description

Ceramic composite for radar absorbing at high temperature and the manufacturing method thereof}

The present disclosure relates to a ceramic composite for absorbing high-temperature radio waves and a method of manufacturing the same, and to applying the ceramic composite to an aircraft for low observable purposes.

As weapon systems develop, low-observable aircraft such as stealth fighters are receiving a lot of attention, and various research and development efforts are being conducted accordingly. The core of stealth technology is to evade the enemy's detection network by constructing the aircraft with structural materials that absorb or scatter radar signals transmitted by the enemy.

Stealth technology has evolved from the initial shape design and electromagnetic wave scattering shape design to shape design using radar absorbing materials, coating the surface of the aircraft with electromagnetic wave absorbing paint, or using insulating polymer and mixed magnetic and non-magnetic fillers.

In the case of radar absorbing structural material (RAS) used in stealth aircraft, room temperature glass fiber reinforced polymer composites were previously applied to the aircraft as an electromagnetic wave absorbing structure, but the disadvantage is that the dielectric properties are lost at a temperature of 200 to 300 degrees and the ability to absorb radio waves is lost. This exists. This has led to research and development of radio wave absorbing structural materials that maintain dielectric properties even at high temperatures. Since the high temperature radio wave absorbing structural materials are applied to aircraft, there is a technical difficulty in that they must be lightweight materials that maintain mechanical structural properties at the same time. am.

The need for structural materials for absorbing high-temperature radio waves is especially evident in cases such as engine exhaust areas of airplanes that are exposed to high-temperature gas environments. Recently, research has been actively conducted on heat-resistant composites reinforced with ceramic fibers as a suitable material for this purpose. there is.

The present disclosure seeks to provide a ceramic composite for absorbing high-temperature radio waves that maintains dielectric properties even at high temperatures and satisfies mechanical properties such as strength and lightness for flight purposes and a method of manufacturing the same.

In detail, the aim is to provide a ceramic composite with excellent radio wave absorption ability at high temperature and improved mechanical properties so that it can be applied as a structural material in places such as the exhaust area of an aircraft with a low observable purpose, and a method of manufacturing the same.

In addition, the aim is to provide a stealth aircraft with excellent low-observability capabilities by applying the ceramic composite and its manufacturing method of the present disclosure to the structure of an aircraft.

The ceramic composite according to the present disclosure is a ceramic composite for absorbing high-temperature radio waves. The composite is manufactured by molding a SiC-based fabric prepreg impregnated with a polysiloxane resin having a reactive group, and the SiC-based fabric contains Si, O, C, and Zr. It is a ceramic composite, a fabric containing elements.

In the ceramic composite according to the present disclosure, the polysiloxane resin having the reactive group may contain 1 to 49 vol% of SiC filler based on 100 vol% of the resin.

In the ceramic composite according to the present disclosure, the reactive group of the polysiloxane resin may include an unsaturated group, and the unsaturated group may be selected from one or more of a vinyl group, an allyl group, or an acrylate group.

In the ceramic composite according to the present disclosure, the SiC-based fabric may include a boron nitride coating layer on the surface.

In the ceramic composite according to the present disclosure, the ceramic composite made of SiC-based fabric prepreg including the boron nitride coating layer has a tensile strength of 50 to 150 Mpa, a real part of the complex permittivity at 10 GHz of 5 to 35, and an imaginary part of 2. It can be from 20 to 20.

In the ceramic composite according to the present disclosure, the ceramic composite may be further subjected to a process of additional impregnation and heat treatment with a polysiloxane resin having a reactive group one or more times, and the polysiloxane resin having a reactive group in the additional impregnation process is a SiC filler. It may not include .

In the ceramic composite according to the present disclosure, the ceramic composite in which the process of additional impregnation and heat treatment with a polysiloxane resin having a reactive group is further performed one or more times may include a boron nitride coating layer on the surface of the SiC-based fabric.

In the ceramic composite according to the present disclosure, the polysiloxane resin having the reactive group may include a platinum-based catalyst.

In the ceramic composite according to the present disclosure, two or more impregnated SiC-based fabric prepregs may be stacked and molded by pressing and heating.

In the ceramic composite according to the present disclosure, the ceramic composite as described above may have a density of 1.5 to 3 g/cc; Tensile strength may be 50 to 150Mpa; The frequency indicating the radio wave absorption ability may have a radio wave absorption ability of -10 dB or less in the range of 8 GHz to 13 GHz.

The method for manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure includes the steps of (A) impregnating a polysiloxane resin having a reactive group with a SiC-based fabric containing Si, O, C, and Zr as elements to prepare a prepreg; (B) laminating two or more of the SiC-based fabric prepregs and pressurizing and heating them to produce a molded product.

In the method of manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure, the polysiloxane resin having the reactive group may contain 1 to 49 vol% of SiC filler based on 100 vol% of the resin.

In the method of manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure, the reactive group of the polysiloxane resin may include an unsaturated group, and the unsaturated group may be selected from one or two or more of a vinyl group, an allyl group, or an acrylate group. there is.

In the method of manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure, the step of applying a boron nitride coating to the surface of the SiC-based fabric may be further included before step (A).

In the method of manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure, after step (B), the step of additionally impregnating and heat-treating the molded product in a polysiloxane resin having a reactive group at least once is further included. The polysiloxane resin having a reactive group in the additional impregnation process may not contain a SiC filler.

In the method of manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure, after step (B), the step of additionally impregnating and heat-treating the molded product in a polysiloxane resin having a reactive group one or more times ( It may further include the step of applying a boron nitride coating to the surface of the SiC-based fabric before step A).

In the method for manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure, the polysiloxane resin having the reactive group may include a platinum-based catalyst.

The aircraft structure according to the present disclosure may include a ceramic composite for absorbing high temperature radio waves as described above.

The aircraft structure according to the present disclosure can be manufactured using the above-described method of manufacturing a ceramic composite for absorbing high-temperature radio waves.

Through the ceramic composite for absorbing high-temperature radio waves and its manufacturing method according to the present disclosure, it is possible to provide a low-observable material with improved mechanical properties and excellent radio wave absorption ability compared to the prior art.

By applying the ceramic composite for absorbing high-temperature radio waves according to the present disclosure to a stealth vehicle, it is possible to provide a stealth vehicle that effectively absorbs radio waves even under ultra-high temperature conditions, such as in the exhaust port of an engine, and avoids an enemy's detection net.

Figure 1 is a graph of the complex permittivity real part result of Evaluation Example 3.
Figure 2 is a graph of the complex permittivity imaginary part result of Evaluation Example 3.
Figure 3 is a graph of the dielectric loss results of Evaluation Example 3.
Figure 4 is a graph of the radio wave absorption ability results of Evaluation Example 3.

Hereinafter, the ceramic composite for absorbing high-temperature radio waves and its manufacturing method of the present disclosure will be described in detail.

The terms used in this disclosure are general terms that are currently widely used as much as possible while considering the function of the present invention, but this may vary depending on the intention or precedent of a technician working in the related field, the emergence of new technology, etc. Unless otherwise defined, the technical and scientific terms used may have meanings commonly understood by those skilled in the art in the technical field to which this invention belongs.

In the present disclosure and the appended claims, terms such as “include” or “have” mean the presence of features or components described in the specification, and, unless specifically limited, one or more other features or This does not exclude the possibility of additional components.

As used in this disclosure and the appended claims, singular expressions include plural expressions, unless the context clearly dictates the singular. Additionally, plural expressions include singular expressions, unless the context clearly specifies plural expressions.

In addition, the numerical range used in the present disclosure includes the lower limit and the upper limit and all values within the range, the increments logically derived from the shape and width of the defined range, all doubly defined values, and the upper limit of the numerical range defined in different forms. and all possible combinations of the lower bounds. Unless otherwise specified in the present disclosure, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

The term "about" or the like used in the present disclosure and appended claims is used to encompass tolerance when tolerance exists.

The ceramic composite for high-temperature radio wave absorption according to the present disclosure is manufactured by molding a SiC-based fabric prepreg impregnated with a polysiloxane resin having a reactive group, and the SiC-based fabric is a fabric containing Si, O, C, and Zr as elements. .

The method for manufacturing a ceramic composite for high-temperature radio wave absorption according to the present disclosure includes the steps of (A) impregnating a SiC-based fabric containing Si, O, C, and Zr as elements into a polysiloxane resin having a reactive group to produce a SiC-based fabric prepreg; ; (B) It includes the step of laminating two or more SiC-based fabric prepregs and forming them by pressing and heating to produce a molded product.

According to one disclosure, the polysiloxane resin having the reactive group may contain 1 to 49 vol% of SiC filler based on 100 vol% of the resin.

The polysiloxane resin having the reactive group has excellent oxidation resistance even at a high temperature of 700°C, so it is suitable as a prepreg resin for impregnating SiC-based fabrics. By adding a SiC filler to the polysiloxane resin, high density when forming a ceramic composite is achieved. It can be achieved. By using a polysiloxane resin containing 1 to 49 vol% of SiC filler as shown in Table 1 below, it is possible to manufacture a ceramic composite appropriate for process suitability and dielectric properties. The real part of the complex dielectric constant of the fabricated ceramic composite for absorbing high temperature radio waves has a value of 11.70 to 30.78, and the imaginary part has a value of 2.83 to 18.78. Although not particularly limited thereto, it may be preferable to use a polysiloxane resin containing 1 to 20 vol% of SiC filler.

polysiloxane resin For absorbing high temperature radio waves
Ceramic composite dielectric properties Product SiC Filler(vol%) Viscosity(cP) complex ε _r ' ε _r ” tanδ SPR-212 0 12 to 26 Z-212-212(5) 14.25 11.72 0.82 SL-450 less than 50 Less than 10,000 Z-450-212(5) 30.78 18.56 0.60 SL-227 23 to 28 3,000 to 4,000 Z-227-212(5) 26.45 18.78 0.71 SL-290 1 to 20 less than 50 Z-290-212(5) 11.70 2.83 0.24

According to one disclosure, the reactive group of the polysiloxane resin having the reactive group may include an unsaturated group, and examples may include a vinyl group, an allyl group, and an acrylate group.

According to one disclosure, the SiC-based fabric of the ceramic composite may include a boron nitride coating layer on the surface, and in the manufacturing method of the ceramic composite, a boron nitride coating is applied to the surface of the SiC-based fabric before step (A). It may additionally include an application step.

According to one disclosure, the ceramic composite made of SiC-based fabric prepreg including the boron nitride coating layer may have a tensile strength of 50 to 150 Mpa, a real part of the complex permittivity at 10 GHz may be 5 to 35, and an imaginary part may be 2 to 20. there is.

The boron nitride coating is not limited to the coating method as long as boron nitride is coated, but for example, wet coating uses a coating solution in which Boric Acid and B and N of Urea are mixed at a molar ratio of 1:1 and nitrogen is used. SiC-based fabrics can be coated by heating in an atmosphere. Comparing the boron nitride coating with the PyC (pyrocarbon) coating, the tensile strength of the ceramic composite with the PyC coating applied to the SiC-based fabric surface increases to over 174 MPa, but the real and imaginary parts of the complex dielectric constant are also 109 and 144, respectively. increases. The radio wave absorption ability of this PyC-coated ceramic composite deteriorates to -1.4 dB around 10 GHz, making it unable to satisfy the radio wave absorption purpose. On the other hand, a ceramic composite in which a boron nitride coating is applied to the surface of a SiC-based fabric has improved tensile strength while maintaining dielectric properties favorable for radio wave absorption and has low dependence on frequency, making it desirable to be used as a structure for aircraft that requires radio wave absorption ability. do.

According to one disclosure, the ceramic composite may be subjected to additional impregnation and heat treatment with polysiloxane resin having a reactive group one or more times. That is, the method for manufacturing the ceramic composite may further include the step of additionally impregnating and heat treating the molded product with a polysiloxane resin having a reactive group one or more times after step (B).

In addition, according to one disclosure, the polysiloxane resin having a reactive group in the additional impregnation and heat treatment process of the present disclosure may not include a SiC filler. In the case of a ceramic composite formed by laminating the above SiC-based fabric prepreg, densification may be necessary. Therefore, by performing the above additional impregnation and heat treatment process (PIP process) one or more times, density and strength can be increased while maintaining the dielectric properties of the ceramic composite. As the number of repetitions of the PIP process increases, the density and dielectric constant of the ceramic composite increase. The tensile strength at this time is determined by the characteristics of the fiber and is similar in size, but the flexural strength increases as the density increases. .

Therefore, it may be desirable to minimize the number of repetitions of the additional impregnation and heat treatment process within the range of achieving the target mechanical properties while satisfying the dielectric properties of the present disclosure. Accordingly, although there is no limitation in achieving the physical properties of the present disclosure, it may be appropriate to repeat the above additional impregnation and heat treatment process 1 to 5 times.

By improving the mechanical properties of the ceramic composite through the additional impregnation and heat treatment process as described above, the ceramic composite of the present disclosure is appropriately modified to suit the shape of a low-observable aircraft and a structure requiring radio wave absorption ability at high temperatures. You can control it.

According to one disclosure, in the ceramic composite of the present disclosure, the SiC-based fabric includes a boron nitride coating layer on the surface, and the process of additionally impregnating and heat treating the ceramic composite in a polysiloxane resin having a reactive group may be performed one or more times. there is.

In addition, according to one disclosure, the method of manufacturing the ceramic composite includes applying a boron nitride coating to the surface of the SiC-based fabric before step (A), and in addition, after step (B), the molded product is placed in a reactor. The eggplant may include the step of performing additional impregnation and heat treatment with polysiloxane resin one or more times.

According to one disclosure, the polysiloxane resin having the reactive group may include a platinum-based catalyst. By using a platinum-based catalyst, the molding time can be shortened and the molding temperature can be lowered while increasing the degree of cure without changing the dielectric properties. For example, if curing of the polysiloxane resin occurs between 200 and 400°C in the absence of a platinum-based catalyst, curing may occur between 90 and 200°C in the presence of a catalyst, and when the polysiloxane resin is cured at 250°C for 3 hours, platinum In the absence of a catalyst, curing is achieved at a level of about 70%, but in the presence of a catalyst, curing can be achieved at a level of 100%.

Therefore, by including a platinum-based catalyst in the polysiloxane resin having the above-mentioned reactive group, even if the molding process of the present disclosure is performed in an autoclave, the SiC-based fabric prepreg can be completely cured within 250°C, the maximum molding temperature of the autoclave. there is.

A polysiloxane resin containing a reactive group may be applied and impregnated on a SiC-based fabric, dried under non-curing conditions, and then laminated with the SiC-based fabric prepreg. According to one disclosure, the impregnated SiC-based fabric prepreg may be formed by stacking two or more pieces and pressing and heating. The molding process through pressurization and heating can be performed using a typical method used in the industry, and for example, it can be performed through a hot-press or autoclave process. It may also include a process of naturally cooling the molded ceramic composite and then heating it to a high temperature in a vacuum under a nitrogen atmosphere, thereby converting polysiloxane into silicon oxycarbide (SiOC).

According to one disclosure, the ceramic composite manufactured according to the present disclosure may have a density of 1.5 to 3 g/cc; Tensile strength may be 50 to 150 Mpa; The frequency indicating the radio wave absorption ability may be one having a radio wave absorption ability of -10 dB or less in the range of 8 GHz to 13 GHz. For example, a ceramic composite can exhibit excellent radio wave absorption ability equivalent to -14dB at 10GHz.

According to one disclosure, an aircraft structure may include a ceramic composite according to the present disclosure. Additionally, an aircraft structure can be manufactured using the method for manufacturing a ceramic composite according to the present disclosure. Since the ceramic composite of the present disclosure and its manufacturing method have excellent radio wave absorption ability even at high temperatures, it can be applied as a structural material that absorbs radio waves in environments exposed to high temperatures, such as the exhaust port of a low-observable aircraft.

Hereinafter, the present disclosure will be described in more detail through the following specific examples.

(Example 1)

Platinum(0)-1,3-divinyl-1,1,3,3-tetramethyl-disiloxane complex catalyst (0.2%) on vinylmethylpoly(siloxane) resin (SL-290, starfire) containing SiC filler at a level of 20 vol% or less. A slurry containing platinum (wt% platinum) was added at 1 wt% and then applied to a silicon carbide (SiC) fabric (plain weave, 270 g/m ² ) containing Si, Zr, C, and O from which the sizing agent was removed. did.

Afterwards, the slurry-coated fabric was dried in an oven at 80°C for 2 minutes to prepare a prepreg impregnated with about 40% of the resin. Then, 15 sheets of prepreg were stacked and molded using hot-press equipment. Molding was accomplished by raising the temperature to 100°C and holding it for 15 minutes, then applying a pressure of 5MPa, raising the temperature to 180°C and holding it for 2 hours.

After molding, it was naturally cooled, placed in a vacuum furnace, heated to 850°C at a temperature increase rate of about 1°C/min under a nitrogen (N ₂ ) atmosphere, and maintained for 1 hour to complete the production of SiC _f /SiOC composite. .

The prepared SiC _f /SiOC composite was put into vinylmethylpoly(siloxane) resin (SPR-212, starfire) and impregnated by maintaining it in vacuum for 70 minutes and atmospheric pressure for 30 minutes, and then the impregnated composite was placed in a vacuum furnace in a nitrogen atmosphere. Transferred to , and then the PIP process was performed once by heating to 850°C at a temperature increase rate of about 1°C/min and then heat treating for 1 hour.

(Example 2)

It was prepared in the same manner as Example 1, except that the PIP process was repeated twice.

(Example 3)

It was prepared in the same manner as Example 1, except that the PIP process was repeated three times.

(Example 4)

It was prepared in the same manner as Example 1, except that the PIP process was repeated 5 times.

(Example 5)

It was prepared in the same manner as in Example 3, except that a BN (boron nitride) coating layer was formed on the surface of a silicon carbide (SiC) fabric containing Si, Zr, C, and O from which the sizing agent was removed, and then the slurry was applied. .

BN coating solution is made by mixing boric acid (99.5% purity, Deoksan Chemical) and urea (urea, 99% purity, Deoksan Chemical) with methanol and distilled water to achieve a concentration of 2M with a molar ratio of B and N of 1:1. Then, it was prepared by completely dissolving the urea at a temperature of 50°C.

The fabric was immersed in the coating solution for 15 minutes, dried at room temperature, and then heat-treated at 1300°C for 20 hours in a vacuum furnace in a mixed gas atmosphere of 96% nitrogen (N ₂ ) and 4% hydrogen (H ₂ ) to form a BN coating layer. formed.

(Example 6)

After stacking the prepreg, a SiC _f /SiOC composite was manufactured in the same manner as in Example 1, except that the autoclave method was applied instead of hot-press.

In the autoclave process, a release film was first placed on the top and bottom of the laminated prepreg, covered with a breather, and vacuum bagging was completed using a bagging film. Afterwards, the vacuum-baked prepreg laminate was placed in the autoclave, the temperature was raised to 80 °C and maintained for 15 minutes, and then a pressure of 0.5 MPa was applied, the temperature was raised to 140 °C and maintained for 90 minutes.

The examples were evaluated in the following evaluation examples.

For the tensile test, bending test, and dielectric property measurement in Evaluation Examples 1 and 2, the SiC _f /SiOC composite produced in the Examples, the tensile specimen, bending specimen, and waveguide specimen were all shaped with a diamond saw and then flattened with a grinder. It was produced by processing and then tested. First, the tensile test was conducted in three-point bending mode according to ASTM C1275 and ASTM C1161, and the universal testing machine (INSTRON 5882) was used. The density of the tensile and flexural specimens is calculated by checking the volume and weight of the specimen according to the geometric bulk density determination method of KS L ISO 18754. The dielectric constant was measured by manufacturing a waveguide specimen and using Keysight PNA N5222B VNA (Vector Network Analyzer) and measurement software N1500A. The complex permittivity real part, imaginary part, and dielectric loss at a frequency of 10 GHz were confirmed.

(Evaluation Example 1)

First, the results of evaluating the tensile test, bending test, and dielectric properties of the ceramic composites prepared in Examples 1 to 4 are shown in Table 2 below. As a result, as the number of repetitions of PIP increased, the density of the composite increased and the real part of the complex dielectric constant slightly increased, but the dielectric properties were maintained. From this, it was confirmed that an excellent high-temperature radio wave absorption ceramic composite that maintains radio wave absorption ability while achieving mechanical properties for flight purposes by densifying the composite through the PIP process was manufactured by the present disclosure.

item PIP
repeat
number Tensile specimen Flexible specimen Dielectric properties (at 10 GHz) density
(g/cc) robbery
(MPa) density
(g/cc) robbery
(MPa) ε _r ' ε _r ” tanδ Example 1 One 1.95 34.82 1.90 60.97 9.52 2.24 0.23 Example 2 2 2.03 35.60 1.99 60.92 9.77 2.15 0.22 Example 3 3 2.12 37.31 2.08 59.83 9.75 2.27 0.23 Example 4 5 2.22 39.19 2.17 71.21 10.46 2.21 0.21

(Evaluation Example 2)

The results of tensile testing and dielectric property evaluation of the ceramic composites prepared in Examples 3 and 5 are shown in Table 3 below. In the case of Example 5, which was manufactured in the same manner as Example 3 except for the BN coating, the tensile strength of the composite manufactured from the BN-coated SiC fabric was significantly increased. In addition, in Example 5, the complex dielectric constant real part value slightly increased, but there was no significant difference, resulting in maintaining the existing dielectric properties. From this, it was confirmed that an excellent high-temperature radio wave absorption ceramic composite that maintains radio wave absorption ability while achieving mechanical properties through BN coating was manufactured according to the present disclosure.

Tensile strength (MPa) Dielectric properties (based on 10 GHz) ε' ε" tanδ Example 3 37.31 9.75 2.27 0.23 Example 5 107.98 10.02 2.82 0.28

(Evaluation example 3)

The radio wave absorption ability of Example 5 was evaluated in the following manner, and the results of the real part, imaginary part, and dielectric loss of complex dielectric constant are shown in Figures 1, 2, and 3, and the radio wave absorption capacity calculated based on this is shown in Figure 4. indicated.

First, the complex permittivity was measured in the X-band frequency range of 8.2 to 12.4 GHz according to ASTM D5568 (Standard Test Method for Measuring Relative Complex Permittivity and Relative Magnetic Permeability of Solid Materials at Microwave Frequencies Using Waveguide). The complex dielectric constant can be expressed as ε _r ^* = ε _r ' - jε _r ", where ε _r ' represents the real part of the dielectric constant, ε _r " represents the imaginary part of the dielectric constant, and the dielectric loss (tanδ), which represents the microwave absorption ability, is tanδ= It is defined as ε _r "/ε _r '. A waveguide specimen was processed to fit the size of the corresponding frequency waveguide (22.86x10.16x3.0mm3 ⁾ , placed in a sample holder, and then connected to the Keysight PNA N522B, a vector network analyzer. Then, the scattering parameters were measured and calculated as complex permittivity using Keysight software N1500A.

Based on the complex permittivity measured above, the radio wave absorption capacity (Return Loss, RL) was calculated using the equation below.

Here, Z _in represents the input impedance between the air and the specimen, ε represents the complex permittivity, μ represents the complex permeability, f is the frequency, c is the speed of light, and d is the specimen thickness. Since the SiC _f /SiOC composite does not have magnetism, μ was assumed to be 1, and d was assumed to be 2.4 mm, the optimal thickness of the specimen. As a result, it showed the best radio wave absorption ability of -14.84dB at 10.25 GHz, and the EAB (Effective Absorption Bandwidth) of -10 dB or less was in the range of 9.275 to 11.375 GHz, showing an excellent bandwidth up to 2.1GHz.

Through the results of the above evaluation examples, it was confirmed that the ceramic composite according to the present disclosure exhibits excellent radio wave absorption ability and mechanical properties as a ceramic composite for high temperature radio wave absorption.

As described above, the present invention has been described with specific details, limited embodiments, and drawings, but these are provided only to aid the overall understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention belongs to Those skilled in the art can make various modifications and variations from this description.

Accordingly, the spirit of the present invention should not be limited to the described embodiments, and the scope of the patent claims described below as well as all modifications that are equivalent or equivalent to the scope of this patent claim shall fall within the scope of the spirit of the present invention. .

Claims (23)

A ceramic composite for absorbing high temperature radio waves,
The composite is a SiC-based fabric prepreg impregnated with a polysiloxane resin having a reactive group. It is manufactured by stacking a plurality of pieces and forming them by pressing and heating,
The SiC-based fabric is a ceramic composite that contains Si, O, C, and Zr as elements and includes a boron nitride coating layer on the surface. According to paragraph 1,
A ceramic composite in which the polysiloxane resin having the reactive group contains 1 to 49 vol% of SiC filler based on 100 vol% of the resin. According to paragraph 1,
A ceramic composite wherein the reactive group of the polysiloxane resin includes an unsaturated group. According to paragraph 3,
A ceramic composite wherein the unsaturated group is selected from one or more of a vinyl group, an allyl group, or an acrylate group. delete According to paragraph 1,
The ceramic composite made of SiC-based fabric prepreg including the boron nitride coating layer has a tensile strength of 50 to 150 Mpa, a real part of the complex dielectric constant at 10 GHz of 5 to 35, and an imaginary part of 2 to 20. According to paragraph 1,
The ceramic composite is one in which the process of additional impregnation and heat treatment with a polysiloxane resin having a reactive group is performed one or more times. In clause 7,
A ceramic composite in which the polysiloxane resin having a reactive group in the additional impregnation process does not include a SiC filler. delete According to paragraph 1,
A ceramic composite wherein the polysiloxane resin having the reactive group includes a platinum-based catalyst. delete The ceramic composite manufactured according to any one of claims 1 to 4, 6 to 8, or 10,
The density may be 1.5 to 3 g/cc;
Tensile strength may be 50 to 150 Mpa;
A ceramic composite having a radio wave absorption ability of -10 dB or less at a frequency of 8 GHz to 13 GHz. A method of manufacturing a ceramic composite for absorbing high temperature radio waves,
(A) preparing a prepreg by impregnating a SiC-based fabric containing Si, O, C, and Zr as elements into a polysiloxane resin having a reactive group; and
(B) manufacturing a molded product by laminating two or more SiC-based fabric prepregs and pressing and heating them,
A method of manufacturing a ceramic composite comprising: applying a boron nitride coating to the surface of the SiC-based fabric before step (A). According to clause 13,
A method of manufacturing a ceramic composite, wherein the polysiloxane resin having the reactive group contains 1 to 49 vol% of SiC filler based on 100 vol% of the resin. According to clause 13,
A method of manufacturing a ceramic composite, wherein the reactive group of the polysiloxane resin includes an unsaturated group. According to clause 15,
A method of producing a ceramic composite, wherein the unsaturated group is selected from one or more of a vinyl group, an allyl group, or an acrylate group. delete According to clause 13,
A method of manufacturing a ceramic composite, further comprising the step of further impregnating and heat-treating the molded product in a polysiloxane resin having a reactive group one or more times after step (B). According to clause 18,
A method of manufacturing a ceramic composite, wherein the polysiloxane resin having a reactive group in the additional impregnation process does not include a SiC filler. delete According to clause 13,
A method of manufacturing a ceramic composite, wherein the polysiloxane resin having the reactive group includes a platinum-based catalyst. An aircraft structure comprising the ceramic composite of any one of claims 1 to 4, 6 to 8, or 10. An aircraft structure manufactured including the ceramic composite manufacturing method of any one of claims 13 to 16, 18 to 19, or 21.