ZrB2 / ZrC composite ceramic wave-absorbing material and preparation method thereof

Abstract

The application relates to a ZrB2 / ZrC composite ceramic wave-absorbing material and a preparation method thereof, and belongs to the field of wave-absorbing materials. The material comprises ZrB2 and ZrC; the ZrB2 is connected with each other to form a space net structure; and the outer wall of the ZrB2 is coated with granular ZrC crystals to form a rough surface. The method is characterized in that ZrB2 is prepared by using a polymer conversion method; ZrC liquid-phase precursors are impregnated into the polymer conversion ZrB2 as a matrix; after sufficient impregnation, solidification is carried out; and after the solidified sample is heat treated, the polymer conversion ZrB2 / ZrC composite material is obtained. The ZrB2 / ZrC ceramic wave-absorbing material prepared by the application has a minimum reflection loss of -64.64 dB, and an effective absorption bandwidth of 6.94 GHz when the material thickness is 4.33 mm.

Description

TECHNICAL FIELD

[0001] The application particularly relates to a ZrB2 / ZrC composite ceramic wave-absorbing material and a preparation method thereof, and belongs to the field of wave-absorbing materials. BACKGROUND

[0002] With the continuous development of radar detection technology, stealth technology for countering radar technology has become the focus of research of various countries in order to gain an advantage in modern warfare. At present, stealth technology mainly reduces the reflection of radar waves on weapon equipment through two ways of adopting a unique shape design and using wave-absorbing materials. However, the change of the shape structure will affect the aerodynamic performance of the aircraft and reduce the actual combat capability. Therefore, electromagnetic wave-absorbing materials become important materials for realizing the stealth of aircraft under multi-spectrum detection conditions. The wave-absorbing materials convert electromagnetic energy into other forms of energy and dissipate it, thereby achieving the purpose of stealth in electromagnetic wave detection. When flying at high speed, the hot end components of the aircraft are in an extremely high temperature environment, which requires the wave-absorbing materials to not only have good electromagnetic wave absorption performance, but also have good high-temperature resistance.

[0003] At present, the research on electromagnetic wave-absorbing materials mainly focuses on magnetic materials, carbon-based materials and ceramic composite materials. However, the original magnetism of the magnetic material will suddenly disappear and the magnetic permeability will sharply decrease when the temperature exceeds the Curie temperature, resulting in a decrease in the wave-absorbing capacity of the material; at the same time, metal materials usually have a large density, which limits the application in the field of aviation and aerospace; carbon-based materials begin to oxidize when the temperature is higher than 400 DEG C, and the oxidation of the material will cause a significant decrease in the wave-absorbing performance, so the anti-oxidation ability of the wave-absorbing material needs to be considered in the application in high-temperature environments. In comparison, ceramic wave-absorbing composite materials have good thermal stability and chemical stability, and are an ideal choice for wave-absorbing materials in high-temperature harsh environments.

[0004] ZrB2 and ZrC are typical super-high-temperature ceramics, have high melting points, corrosion resistance, oxidation resistance and other characteristics, and are widely used in the hot end parts of aircrafts, and also have high electrical conductivity, and are an ideal choice for high-temperature wave-absorbing materials. However, the current research on ZrB2 and ZrC mainly focuses on their oxidation resistance and ablation performance. The research on the electromagnetic properties of ZrB2 and ZrC is limited to using them as an added phase of other ceramics to improve the electromagnetic wave absorption properties, and there is a lack of relevant research on the electromagnetic properties of ZrB2 and ZrC ceramics themselves, which makes it difficult to broaden the application of ZrB2 and ZrC in the field of high-temperature wave-absorbing materials. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a ZrB2 / ZrC composite ceramic wave-absorbing material and a preparation method thereof.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect, the present application provides a ZrB2 / ZrC composite ceramic wave-absorbing material, comprising ZrB2 and ZrC; the ZrB2 is connected to each other to form a space net structure; the ZrB2 outer wall coats the granular ZrC crystal to form a rough surface.

[0008] Preferably, the micro-morphology of the ZrB2 is tubular.

[0009] In a second aspect, the present application provides a preparation method of the ZrB2 / ZrC composite ceramic wave-absorbing material, comprising the following steps:

[0010] S1: preparing ZrB2 by using a polymer conversion method;

[0011] S2: taking the polymer conversion ZrB2 as a substrate, impregnating a ZrC liquid precursor, and then performing solidification after sufficient impregnation; and performing heat treatment on the solidified sample to obtain a polymer conversion ZrB2 / ZrC composite material.

[0012] Preferably, the specific steps of preparing ZrB2 by using the polymer conversion method are as follows:

[0013] S11: cross-linking and solidifying the ZrB2 liquid precursor, grinding into powder, and then pressing into a shape;

[0014] S12: obtaining the polymer conversion ZrB2 after heat treatment and heating pyrolysis.

[0015] Preferably, the cross-linking and solidification condition in S11 is cross-linking and solidifying at 160-180℃ for 1-3h.

[0016] Preferably, the grinding in S11 is ball milling; and the ball milling condition is 200-300r / min.

[0017] Preferably, the heat treatment condition in S11 is heat treatment at 600-700℃ under Ar protection for 1-3h, and the temperature rising rate is 1-5℃ / min.

[0018] Preferably, the heating pyrolysis condition in S11 is pyrolysis at 1500-1600℃ for 1-3h.

[0019] Preferably, the solidification condition in S2 is solidification at 200-300℃ for 2h.

[0020] Preferably, the heat treatment condition in S2 is heat treatment at 1500-1600℃ for 2h.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The prepared polymer converted ZrB2 / ZrC composite material contains pores, is beneficial to electromagnetic wave absorption, and the micro-morphology of the composite material presents the morphology of ZrB2 crystal outer wall coating ZrC ceramic particles, ZrB2 is connected with each other, and the electrical conductivity loss of the material is increased; the ZrC particles attached to the outer wall of the ZrB2 tubular crystal introduce a large number of interfaces, increase the interfacial polarization loss, and improve the wave absorption performance of the composite material. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A scanning electron microscope image of the ZrB2 / ZrC composite material prepared for the embodiment 3 of the present application;

[0024] Figure 2 An electromagnetic wave reflection loss diagram of the ZrB2 / ZrC composite material prepared for the embodiment 3 of the present application in the 2-18GHz wave band. DETAILED DESCRIPTION

[0025] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0026] It should be understood that when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0027] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and do not intend to limit the present application. As used in the present application specification and the appended claims, unless otherwise clearly indicated by the context, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0028] It should be further understood that the term "and / or" used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0029] The various structural diagrams according to the disclosed embodiments of the present application are shown in the drawings. These diagrams are not drawn to scale, in which certain details are exaggerated for the purpose of clarity, and certain details may be omitted. The shapes of various regions, layers and the relative size and positional relationship therebetween shown in the drawings are only exemplary, and may deviate in actuality due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes and relative positions may be additionally designed according to actual needs by those skilled in the art.

[0030] The first object of the present application is to provide a ZrB2 / ZrC composite ceramic wave-absorbing material, comprising ZrB2 and ZrC; the ZrB2 are connected to each other to form a spatial reticular structure; the ZrB2 outer wall coats granular ZrC crystals to form a rough surface; wherein the micro-morphology of ZrB2 is tubular.

[0031] The spatial reticular structure formed by the mutual connection of ZrB2 significantly improves the electrical conductivity of the composite material. When electromagnetic waves enter the material, the mutually connected ZrB2 tubular structures can effectively guide the flow of current, thereby increasing the electrical conduction loss, so that the energy of electromagnetic waves is rapidly consumed. Secondly, the ZrC particles attached to the outer wall of the ZrB2 tubular crystals introduce a large number of interfaces. The presence of these interfaces enables the material to produce more polarization phenomena under the action of an electromagnetic field, thereby increasing the interfacial polarization loss. This enhancement of polarization loss significantly improves the wave-absorbing performance of the composite material.

[0032] The ZrB2 / ZrC composite material prepared by the present application also contains pores, which not only increase the specific surface area of the material and improve the interfacial activity of the material, but also provide more reflection and scattering paths for electromagnetic waves, further enhancing the electromagnetic wave absorption performance of the material.

[0033] The second object of the present application is to provide a preparation method of a ZrB2 / ZrC composite ceramic wave-absorbing material, comprising the following steps:

[0034] S1: preparing ZrB2 by using a polymer conversion method;

[0035] S2: using polymer-converted ZrB2 as a matrix, impregnating ZrC liquid-phase precursors, and performing solidification after sufficient impregnation; heat-treating the solidified sample to obtain a polymer-converted ZrB2 / ZrC composite material.

[0036] The solidification condition is 2h at 200-300℃, and the heat-treatment condition is 2h at 1500-1600℃.

[0037] In view of the fact that there is no relevant research on the electromagnetic performance of ZrB2 / ZrC, the application prepares ZrB2 / ZrC ultra-high temperature ceramics and studies the electromagnetic performance thereof. The application uses a polymer conversion method to prepare ZrB2, and uses a liquid-phase precursor impregnation and pyrolysis method to introduce ZrC into the ZrB2 as a matrix, and obtains ZrB2 / ZrC composite materials through high-temperature pyrolysis.

[0038] The specific steps for preparing ZrB2 by using the polymer conversion method are as follows:

[0039] S11: cross-linking and curing the ZrB2 liquid-phase precursor, grinding into powder and compression molding;

[0040] S12: obtaining polymer conversion ZrB2 after heat treatment and heating pyrolysis.

[0041] The polymer conversion method is a process for preparing ceramic matrix composites at a relatively low temperature, and the ZrB2-containing polymer precursor is uniformly mixed, and then the target ceramic product is obtained after cross-linking and curing and high-temperature pyrolysis. The liquid-phase precursor impregnation and pyrolysis method is a commonly used method for preparing ceramic materials. ZrC is introduced by immersing ZrC polymer liquid-phase precursor into the porous ZrB2 matrix, and the polymer conversion ZrB2 / ZrC composite material is obtained by removing organic impurities through high-temperature treatment after complete impregnation. After introducing ZrC into the ZrB2 matrix, the electric loss and the interfacial polarization loss of the composite material are enhanced, thereby improving the wave absorption performance thereof. In addition, the introduction of ZrC particles also increases the interfacial activity of the material, thereby further improving the performance thereof.

[0042] In S11, the cross-linking and curing conditions are as follows: cross-linking and curing at 160-180 DEG C for 1-3 h; the grinding is ball milling; the ball milling conditions are as follows: 200-300 r / min; the heat treatment conditions are as follows: heat treatment at 600-700 DEG C under Ar protection for 1-3 h, and the heating rate is 1-5 DEG C / min; and the heating pyrolysis conditions are as follows: pyrolysis at 1500-1600 DEG C for 1-3 h.

[0043] Example 1

[0044] First, the liquid ZrB2 precursor is placed in an oven for cross-linking and curing at 160 DEG C for 2 h to obtain a solid precursor, and then the solidified precursor is broken and ball milled in a planetary ball mill at 240 r / min to obtain a precursor powder. Subsequently, the precursor powder is compression molded into a circular ring sample with an inner diameter of 3 mm and an outer diameter of 12 mm on a tablet press, the pressure is 10 kN, and the pressure holding time is 2 min. The compression-molded sample is placed in a low-temperature tube furnace and heat treated at 600 DEG C under Ar protection for 2 h, and the heating rate is 5 DEG C / min. Finally, the heat-treated sample is pyrolyzed at 1500 DEG C in a high-temperature tube furnace for 2 h to obtain ZrB2 ceramics.

[0045] The ZrB2 as substrate after high temperature pyrolysis was immersed in the liquid ZrC precursor, and was placed in a vacuum tank, vacuumed to a pressure gauge less than -0.1, and then was left for 30 min to allow the precursor to fully enter the ZrB2 substrate. The immersed sample was cured at 200 ℃ for 2 h, and finally was heat treated at 1500 ℃ for 2 h to obtain the polymer converted ZrB2 / ZrC composite material.

[0046] The electromagnetic parameters of the sample were tested by using a vector network analyzer, and the minimum reflection loss value calculated from the measured dielectric constant was -62.48 dB, and the effective absorption bandwidth (<-10 dB) was 5.92 GHz.

[0047] Example 2

[0048] The liquid ZrB2 precursor was placed in an oven and crosslinked and cured at 170 ℃ for 2 h to obtain a solid precursor, and then the cured precursor was crushed and ball milled to obtain a precursor powder in a planetary ball mill at 240 r / min. Subsequently, a circular ring sample with an inner diameter of 3 mm and an outer diameter of 12 mm was pressed on a tablet press, the pressure was 10 kN, and the pressure holding time was 2 min. The pressed sample was placed in a low-temperature tube furnace and heat treated at 650 ℃ under Ar gas protection for 2 h, and the heating rate was 5 ℃ / min. Finally, the heat treated sample was pyrolyzed at 1550 ℃ for 2 h in a high temperature tube furnace to obtain ZrB2 ceramic.

[0049] The ZrB2 as substrate after high temperature pyrolysis was immersed in the liquid ZrC precursor, and was placed in a vacuum tank, vacuumed to a pressure gauge less than -0.1, and then was left for 30 min to allow the precursor to fully enter the ZrB2 substrate. The immersed sample was cured at 220 ℃ for 2 h, and finally was heat treated at 1550 ℃ for 2 h to obtain the polymer converted ZrB2 / ZrC composite material.

[0050] The electromagnetic parameters of the sample were tested by using a vector network analyzer, and the minimum reflection loss value calculated from the measured dielectric constant was -63.59 dB, and the effective absorption bandwidth was 6.52 GHz.

[0051] Example 3

[0052] The liquid ZrB2 precursor was placed in an oven and crosslinked and cured at 180 ℃ for 2 h to obtain a solid precursor, and then the cured precursor was crushed and ball milled to obtain a precursor powder in a planetary ball mill at 240 r / min. Subsequently, a circular ring sample with an inner diameter of 3 mm and an outer diameter of 12 mm was pressed on a tablet press, the pressure was 10 kN, and the pressure holding time was 2 min. The pressed sample was placed in a low-temperature tube furnace and heat treated at 700 ℃ under Ar gas protection for 2 h, and the heating rate was 5 ℃ / min. Finally, the heat treated sample was pyrolyzed at 1600 ℃ for 2 h in a high temperature tube furnace to obtain ZrB2 ceramic.

[0053] ZrB2 as the substrate after high temperature pyrolysis, immersed in the liquid ZrC precursor, placed in a vacuum tank, vacuum to the pressure gauge less than -0.1, then stand for 30 min, let the precursor into the ZrB2 matrix. The sample after immersion in 250 ℃ curing 2h, finally in 1600 ℃ heat treatment 2h to obtain polymer conversion ZrB2 / ZrC composite material. As shown in Figure 1 ZrB2 / ZrC composite material of the present application, the size of ZrB2 crystal is in the order of μm; the size of granular ZrC crystal is close to nm.

[0054] As shown in Figure 2 ZrB2 / ZrC composite material prepared in this embodiment in the 2-18GHz wave band of electromagnetic wave reflection loss diagram; using the vector network analyzer for electromagnetic parameter test, the minimum reflection loss value is-64.64dB, the effective absorption bandwidth is 6.94GHz, calculated from the measured dielectric constant.

[0055] Example 4

[0056] First, the liquid ZrB2 precursor is placed in an oven at 160 ℃ crosslinking curing 2h to obtain solid precursor, then the solidified precursor is broken and ball milled in a planetary ball mill at 200r / min to obtain precursor powder. Subsequently, the ring sample with an inner diameter of 3mm and an outer diameter of 12mm is pressed on the tablet press, the pressure is 10kN, and the pressure holding time is 2min. The pressed sample is placed in a low temperature tube furnace, and heat treated at 600 ℃ under Ar gas protection for 3h, the heating rate is 1 ℃ / min. Finally, the heat treated sample is pyrolyzed at 1600 ℃ in a high temperature tube furnace for 1h to obtain ZrB2 ceramic.

[0057] ZrB2 as the substrate after high temperature pyrolysis, immersed in the liquid ZrC precursor, placed in a vacuum tank, vacuum to the pressure gauge less than -0.1, then stand for 30 min, let the precursor into the ZrB2 matrix. The sample after immersion in 260 ℃ curing 2h, finally in 1520 ℃ heat treatment 2h to obtain polymer conversion ZrB2 / ZrC composite material.

[0058] Example 5

[0059] First, the liquid ZrB2 precursor was cross-linked and cured in an oven at 160℃ for 3 hours to obtain a solid precursor. Then, the cured precursor was crushed and ball-milled, followed by further ball milling in a planetary ball mill at 260 r / min to obtain precursor powder. Subsequently, it was pressed into ring samples with an inner diameter of 3 mm and an outer diameter of 12 mm using a tablet press, at a pressure of 10 kN and a holding time of 2 min. The pressed samples were then placed in a low-temperature tube furnace and heat-treated at 650℃ under Ar gas protection for 2 hours, with a heating rate of 2℃ / min. Finally, the heat-treated samples were pyrolyzed in a high-temperature tube furnace at 1500℃ for 3 hours to obtain ZrB2 ceramics.

[0060] Using high-temperature pyrolysis ZrB2 as the matrix, it was immersed in a liquid ZrC precursor and placed in a vacuum chamber. The chamber was evacuated until the pressure gauge reading was below -0.1, and then allowed to stand for 30 minutes to allow the precursor to fully penetrate the ZrB2 matrix. The impregnated sample was cured at 280℃ for 2 hours, and finally heat-treated at 1540℃ for 2 hours to obtain a polymer-converted ZrB2 / ZrC composite material.

[0061] Example 6

[0062] First, the liquid ZrB2 precursor was cross-linked and cured in an oven at 180℃ for 1 hour to obtain a solid precursor. Then, the cured precursor was crushed and ball-milled, followed by further ball milling in a planetary ball mill at 300 r / min to obtain precursor powder. Subsequently, it was pressed into ring samples with an inner diameter of 3 mm and an outer diameter of 12 mm using a tablet press, at a pressure of 10 kN and a holding time of 2 min. The pressed samples were then placed in a low-temperature tube furnace and heat-treated at 700℃ under Ar gas protection for 1 hour, with a heating rate of 3℃ / min. Finally, the heat-treated samples were pyrolyzed in a high-temperature tube furnace at 1550℃ for 3 hours to obtain ZrB2 ceramics.

[0063] Using high-temperature pyrolysis ZrB2 as the matrix, it was immersed in a liquid ZrC precursor and placed in a vacuum chamber. The chamber was evacuated until the pressure gauge reading was below -0.1, and then allowed to stand for 30 minutes to allow the precursor to fully penetrate the ZrB2 matrix. The impregnated sample was cured at 300℃ for 2 hours, and finally heat-treated at 1580℃ for 2 hours to obtain a polymer-converted ZrB2 / ZrC composite material.

[0064] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a ZrB2 / ZrC composite ceramic microwave absorbing material, characterized in that, Includes the following steps: S1: ZrB2 was prepared using a polymer conversion method; S2: Using polymer-converted ZrB2 as the matrix, impregnate ZrC liquid phase precursor, and cure after full impregnation; heat-treat the cured sample to obtain polymer-converted ZrB2 / ZrC composite material. The specific steps for preparing ZrB2 using the polymer conversion method are as follows: S11: Crosslink and solidify the ZrB2 liquid phase precursor, grind it into powder and press it into shape; S12: Polymer-converted ZrB2 is obtained after heat treatment and thermal pyrolysis; The cross-linking curing conditions described in S11 are: cross-linking curing at 160-180℃ for 1-3 hours; The heat treatment conditions described in S12 are: heat treatment at 600-700℃ under Ar gas protection for 1-3 h, with a heating rate of 1-5℃ / min; The heating pyrolysis conditions described in S12 are: pyrolysis at 1500-1600℃ for 1-3 hours; The curing conditions described in S2 are: curing at 200-300℃ for 2 hours; The heat treatment conditions described in S2 are: heat treatment at 1500-1600℃ for 2 hours; The ZrB2 / ZrC composite ceramic microwave absorbing material includes ZrB2 and ZrC; the ZrB2 particles are interconnected to form a spatial network structure; the outer wall of the ZrB2 particles is coated with granular ZrC crystals to form a rough surface.

2. The preparation method according to claim 1, characterized in that, The ZrB2 microstructure is tubular.

3. The preparation method according to claim 1, characterized in that, The grinding described in S11 is ball milling; the ball milling conditions are: 200-300 r / min.

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