A high-temperature resistant, oxidation-resistant, and X-band fully absorbable SiBCN-ZrO2 ceramic composite material and its preparation method.

Abstract

This invention belongs to the field of microwave absorbing materials technology, and discloses a SiBCN-ZrO2 ceramic composite material with high temperature resistance, oxidation resistance, and full X-band absorption, as well as its preparation method. First, SiBCN and ZrO2 polymer liquid-phase precursors are uniformly mixed, followed by low-temperature curing and high-temperature pyrolysis heat treatment, ultimately obtaining a SiBCN-ZrO2 ceramic composite material with ZrO2 uniformly distributed in an amorphous SiBCN matrix. This ceramic composite material has an effective absorption bandwidth of 4.2 GHz in the X-band, compared to 3.65 GHz for pure PDC-SiBCN ceramic, demonstrating an improved effective absorption bandwidth that covers the entire X-band, and also improving oxidation resistance. The preparation process of the SiBCN-ZrO2 ceramic composite material prepared by this invention is simple and can effectively improve the insufficient dielectric loss capacity of PDC-SiBCN ceramic as a microwave absorbing material, enhancing the overall high-temperature resistance and oxidation resistance of the material.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials technology, specifically relating to a SiBCN-ZrO2 ceramic composite material that is resistant to high temperature and oxidation and has full absorption in the X-band, and its preparation method. Background Technology

[0002] Radar-absorbing materials have extremely wide applications in stealth technology. High-temperature stealth technology is one of the key technologies for modern aircraft to reach high Mach numbers, and it is a very important technology to improve the survivability and penetration capability of aircraft. The application of radar-absorbing materials is one of the important ways to achieve radar stealth functionality. In the hot-end parts of aircraft, such as the surface of hypersonic aircraft, the nose cone of cruise missiles, and the leading edge of wings, the operating temperature is high and they are in dynamic thermal environments such as oxidation, resulting in strong radar wave reflection. As the Mach number of aircraft increases, the requirements for the ability to withstand harsh high-temperature environments for these components become increasingly stringent, requiring stealth materials to have excellent high-temperature radar absorption, oxidation resistance, and thermal shock resistance. PDC-SiBCN, as a high-temperature resistant ceramic, still has excellent thermal, chemical, and mechanical stability when it withstands temperatures as high as 2000~2200 ℃ in an inert atmosphere. However, it is still amorphous at high temperatures and has poor radar absorption performance. Therefore, it is urgent to improve the radar absorption performance and high-temperature oxidation resistance of PDC-SiBCN-based ceramics.

[0003] Reference 1, "Luo C, Tang Y, Jiao T, et al. High-temperature stable and metal-free electromagnetic wave-absorbing SiBCN ceramics derived from carbon-rich hyperbranched polyborosilazanes [J]. ACS Applied Materials & Interfaces, 2018, 10(33): 28051-28061," discloses the acquisition of high-temperature stable, metal-free, and electromagnetic wave-absorbing SiBCN ceramics with high electromagnetic wave absorption efficiency through structural design and pyrolysis of carbon-rich branched polyborosilazanes with pendant phenyl groups. The results show that the ceramics pyrolyzed from the benzene-ring-containing pre-ceramic precursor have a high carbon content and a large amount of sp2 carbon, and generate crystalline carbon (graphite carbon and tubular carbon) in situ, which has considerable conductivity and therefore good electromagnetic wave absorption performance. The electromagnetic wave absorption efficiency and effective absorption bandwidth (EAB, reflection coefficient (RC)) of the ceramics can be adjusted by the heat treatment temperature. The ceramic, stable at 1320 °C, exhibits the best electromagnetic wave absorption performance, with a minimum RC of -71.80 dB and an EAB of 3.65 GHz. However, its electromagnetic wave absorption bandwidth is relatively narrow, and the in-situ generated sp...2 Carbon has poor high-temperature resistance and oxidation resistance, resulting in limited practical application capabilities.

[0004] Reference 2, "Liu H, Zhang Y, Liu X, et al. Additive manufacturing of nanocellulose / polyborosilazane derived CNFs-SiBCN ceramic metamaterials for ultra-broadband electromagnetic absorption[J]. Chemical Engineering Journal, 2022, 433: 133743," discloses a method combining additive manufacturing technology and polymer-derived ceramic processes to prepare defect-rich carbon nanofibers (CNFs) modified SiBCN ceramic-based metamaterials. Defect-rich CNFs were generated in situ by introducing nanocellulose into the pre-ceramic bulk through thermal decomposition. With a cellulose content of 6.0 wt% and an annealing temperature of 1200 ℃, the real and imaginary parts of the dielectric constant reached 17.0 and 7.0, respectively. Cole-Cole diagrams show that CNFs-SiBCN ceramics exhibit strong polarization capabilities due to their defect-rich structure. At a thickness of 1.8 mm, the minimum RC reached −20.0 dB, and the EAB reached 2.85 GHz. However, CNFs lose their fiber structure under oxidation conditions at 400 ℃, and their effective absorption bandwidth is narrow at room temperature, which limits their application in the field of high-temperature oxidation absorption. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a SiBCN-ZrO2 ceramic composite material with high temperature resistance, oxidation resistance, and full X-band absorption, and its preparation method. The present invention can solve the problem of narrow absorption bandwidth of PDC-SiBCN and improve its high temperature resistance and oxidation resistance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-temperature resistant, oxidation-resistant, and X-band fully absorbable SiBCN-ZrO2 ceramic composite material includes the following steps:

[0008] Liquid polyborosilazane and polyacetylacetone zirconium are mixed evenly to obtain mixture A; the volume ratio of liquid polyborosilazane and polyacetylacetone zirconium is (1~2):1;

[0009] The mixture A was cured in a protective atmosphere to obtain a cured block.

[0010] The solidified block is processed into powder to obtain powder of pre-made ceramic sheet SiBCN-ZrO2;

[0011] The SiBCN-ZrO2 preformed ceramic sheet powder is pressed into shape to obtain the preformed ceramic sheet;

[0012] The preformed ceramic sheet was subjected to high-temperature pyrolysis heat treatment in a protective atmosphere to obtain the high-temperature resistant, oxidation-resistant, and X-band fully absorbed SiBCN-ZrO2 ceramic composite material.

[0013] Preferably, liquid polyborosilazane and polyacetylacetonate zirconium are mixed evenly by mechanical stirring at 55~65°C to obtain mixture A.

[0014] Preferably, when the mixture A is cured in a protective atmosphere, the curing temperature is 200~300℃ and the curing time is 1~3h.

[0015] Preferably, after the solidified block is processed into powder, it is sieved to obtain 100-400 mesh pre-made ceramic sheet SiBCN-ZrO2 powder.

[0016] Preferably, the solidified block is processed into powder by ball milling. During ball milling, the rotation speed is 40~60 rpm and the time is 5~12 hours.

[0017] Preferably, when the SiBCN-ZrO2 preformed ceramic sheet is pressed into shape, the pressure is 5~15kPa.

[0018] Preferably, when the preform ceramic sheet is subjected to high-temperature pyrolysis heat treatment in a protective atmosphere, the preform ceramic sheet is heated to 1100~1300℃ at a heating rate of 2~5℃ / min, and then held at that temperature for 1~3h. After the holding period, it is cooled with the furnace to obtain the high-temperature resistant, oxidation-resistant, and X-band fully absorbed SiBCN-ZrO2 ceramic composite material.

[0019] Preferably, argon is used as the protective atmosphere.

[0020] The present invention also provides a high-temperature resistant, oxidation-resistant, and X-band fully absorbable SiBCN-ZrO2 ceramic composite material, which is prepared by the above preparation method.

[0021] Preferably, the SiBCN-ZrO2 ceramic composite material with high temperature resistance, oxidation resistance and full absorption in the X-band has a minimum reflection coefficient (RC) of -34.8dB and an effective absorption bandwidth (EAB) of 4.2GHz.

[0022] The present invention has the following beneficial effects:

[0023] This invention involves uniformly mixing a liquid precursor of SiBCN (i.e., liquid polyborosilazane) and a liquid precursor of ZrO2 (i.e., polyzirconium acetylacetonate), and then preparing a SiBCN-ZrO2 ceramic composite material through low-temperature crosslinking and high-temperature pyrolysis. This composite material uses PDC-SiBCN ceramic as the matrix, combined with ZrO2, to form a composite containing amorphous BN, Si3N4, SiO2, and sp... 2 A multiphase ceramic composite material of carbon and ZrO2. The addition of the ZrO2 phase enhances the dielectric loss capability of PDC-SiBCN, and the presence of various amorphous phases increases the impedance matching between the material and electromagnetic wave free space, thereby improving the overall electromagnetic wave absorption capability of the material. At the same pyrolysis temperature, the minimum reflection coefficient of ZrO2-enhanced PDC-SiBCN is -34.8 dB, and compared with 2.85 GHz for CNFs-doped SiBCN, the effective absorption bandwidth (EAB) of this invention is increased to 4.2 GHz. In addition, the SiBCN-ZrO2 composite ceramic prepared by this invention not only has an effective absorption bandwidth across the entire X-band, but also possesses excellent high-temperature resistance and oxidation resistance, showing promising application prospects. Attached Figure Description

[0024] Figure 1(a) is a scanning electron microscope image of the SiBCN-ZrO2 ceramic composite material obtained in Example 1 of the present invention;

[0025] Figure 1(b) is a scanning electron microscope image of the SiBCN-ZrO2 ceramic composite material described in Example 2 of the present invention;

[0026] Figure 1(c) is a scanning electron microscope image of the SiBCN-ZrO2 ceramic composite material obtained in Example 3 of the present invention;

[0027] Figure 2 This is a transmission electron microscope image of the SiBCN-ZrO2 ceramic composite material obtained in Example 3 of the present invention;

[0028] Figure 3 The microwave absorption performance diagram of the SiBCN-ZrO2 ceramic composite material prepared in Example 3 of this invention is shown.

[0029] Figure 4 Thermogravimetric analysis (TGA) diagrams of the SiBCN-ZrO2 ceramic composite materials obtained in Examples 1-3 (corresponding to S1, S2 and S3) of this invention under oxidation conditions of 20~1400℃. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] Most carbon materials used as microwave absorbers face oxidation failure in high-temperature environments. Zirconia, as an oxide ceramic material, not only possesses high-temperature stability but also exhibits excellent performance in oxidizing environments. This invention selects ZrO2 ceramic as a reinforcing phase for microwave absorption and oxidation resistance in PDC-SiBCN ceramic, aiming to improve the microwave absorption bandwidth and high-temperature oxidation resistance of PDC-SiBCN ceramic.

[0032] This invention provides a high-temperature resistant, oxidation-resistant SiBCN-ZrO2 ceramic composite material with full X-band absorption and its preparation method. First, SiBCN and ZrO2 polymer liquid-phase precursors are uniformly mixed, followed by low-temperature curing and high-temperature pyrolysis heat treatment to finally obtain the SiBCN-ZrO2 composite ceramic material. The SiBCN-ZrO2 ceramic composite material prepared by this invention not only improves the insufficient loss capacity and narrow effective absorption bandwidth of PDC-SiBCN ceramics as microwave absorbing materials, but also enhances the overall high-temperature resistance and oxidation resistance of the material.

[0033] Specifically, the preparation method of the SiBCN-ZrO2 ceramic composite material of the present invention, which is resistant to high temperature and oxidation and exhibits full absorption in the X-band, includes the following steps:

[0034] Step 1: Select liquid polyborosilazane (PSNB) and polyzirconium acetylacetonate (PZO) as precursors for polymer conversion ceramics. Mix PSNB and PZO in a volume ratio of (1~2):1 mechanically. During mechanical mixing, stir magnetically at 55~65℃ for 2~4h until the mixture is homogeneous to obtain mixture A. Use a heat treatment furnace with resistance wire as the heating element to cure mixture A at 200~300℃ for 1~3h in an argon atmosphere to obtain a cured block.

[0035] Step 2: Use a planetary ball mill to ball mill the solidified block obtained in Step 1. During ball milling, the rotation speed is 40~60 rpm and the time is 5~12 hours. Sieve the ball-milled powder to obtain SiBCN-ZrO2 pre-fabricated ceramic sheet powder with a uniform distribution of 100~400 mesh.

[0036] Step 3: Transfer the SiBCN-ZrO2 ceramic powder prepared in Step 2 into a stainless steel mold with a cavity size of 35×20×60mm, and use a dry press to press the powder into a preform ceramic sheet of a fixed size at a pressure of 5~15kPa. After demolding, the preform ceramic sheet is obtained.

[0037] Step 4: The pressed preform ceramic sheet is placed in a heat treatment furnace with resistance wire as the heating element. In a flowing Ar atmosphere, the furnace temperature is raised from room temperature to 1100-1300℃ at a heating rate of 2-5℃ / min and held for 1-3 hours. The power is turned off and the material is allowed to cool naturally to room temperature to obtain the heat-treated SiBCN-ZrO2 ceramic composite material.

[0038] Example 1:

[0039] The preparation method of the high-temperature resistant, oxidation-resistant, and X-band fully absorbable SiBCN-ZrO2 ceramic composite material in this embodiment includes the following steps:

[0040] (1) Mix PSNB and PZO liquid phase precursors in a volume ratio of 1:1, heat and stir at 60°C for 3 hours on a magnetic stirrer, and then transfer the uniformly mixed liquid phase precursor into a heat treatment furnace with resistance wire as the heating element. In an Ar atmosphere, solidify the precursor solution at 280°C for 2 hours.

[0041] (2) The solidified precursor obtained in step (1) was ball-milled using a planetary ball mill at a speed of 40 rpm for 12 h. The ball-milled powder was then sieved to obtain SiBCN-ZrO2 pre-made ceramic sheets with a uniform distribution of 100-400 mesh.

[0042] (3) Pour the powder of the pre-made ceramic sheet SiBCN-ZrO2 into a mold with a cavity size of 35×20×60mm, and use a dry press to press the powder into a pre-made ceramic sheet of a fixed size at a pressure of 15kPa.

[0043] (4) The preformed ceramic surface is placed in a heat treatment furnace with resistance wire as the heating element. In a flowing Ar atmosphere, the furnace temperature is raised from room temperature to 1100℃ at a heating rate of 5℃ / min and held for 3h. The power is turned off and the surface is allowed to cool naturally to room temperature to obtain the heat-treated SiBCN-ZrO2 composite ceramic.

[0044] Referring to Figure 1(a), the scanning electron microscope image of the SiBCN-ZrO2 ceramic composite material obtained in this embodiment shows that the ceramic surface is dense and uniform; the thermogravimetric results of the SiBCN-ZrO2 ceramic composite material obtained in embodiment S1 under oxidation conditions of 20~1400℃ are as follows. Figure 4 As shown, the weight loss rate of the oxidized ceramic composite material is 16.3%.

[0045] Example 2:

[0046] The preparation method of the high-temperature resistant, oxidation-resistant, and X-band fully absorbable SiBCN-ZrO2 ceramic composite material in this embodiment includes the following steps:

[0047] (1) Mix PSNB and PZO liquid phase precursors in a volume ratio of 1:1, heat and stir at 55°C for 4 hours on a magnetic stirrer, and then transfer the uniformly mixed liquid phase precursor into a heat treatment furnace with resistance wire as the heating element. In an Ar atmosphere, solidify the precursor solution at 300°C for 1 hour.

[0048] (2) The solidified precursor obtained in (1) was ball-milled using a planetary ball mill at a speed of 50 rpm for 10 h. The ball-milled powder was then sieved to obtain SiBCN-ZrO2 pre-made ceramic sheets with a uniform distribution of 100-400 mesh.

[0049] (3) Pour the powder of the pre-made ceramic sheet SiBCN-ZrO2 into a mold with a cavity size of 35×20×60mm, and use a dry press to press the powder into a pre-made ceramic sheet of a fixed size with a pressure of 5kPa.

[0050] (4) The preformed ceramic surface is placed in a heat treatment furnace with resistance wire as the heating element. In a flowing Ar atmosphere, the furnace temperature is raised from room temperature to 1200℃ at a heating rate of 2℃ / min and held for 2h. The power is turned off and the material is allowed to cool naturally to room temperature to obtain the heat-treated SiBCN-ZrO2 composite ceramic.

[0051] Referring to Figure 1(b), the scanning electron microscope image of the SiBCN-ZrO2 ceramic composite material obtained in this embodiment shows that the ceramic surface is dense and uniform; the thermogravimetric results of the SiBCN-ZrO2 ceramic composite material obtained in S2 of this embodiment under oxidation conditions of 20~1400℃ are as follows. Figure 4 As shown, the weight loss rate of the oxidized ceramic composite material is 2.5%.

[0052] Example 3:

[0053] The preparation method of the high-temperature resistant, oxidation-resistant, and X-band fully absorbable SiBCN-ZrO2 ceramic composite material in this embodiment includes the following steps:

[0054] (1) Mix PSNB and PZO liquid phase precursors in a 1:1 ratio, heat and stir at 65°C for 2 hours on a magnetic stirrer, then transfer the uniformly mixed liquid phase precursors into a heat treatment furnace with resistance wire as the heating element, and solidify the precursor solution at 200°C for 3 hours in an Ar atmosphere.

[0055] (2) The solidified precursor obtained in (1) was ball-milled using a planetary ball mill at a speed of 60 rpm for 5 h. The ball-milled powder was then sieved to obtain SiBCN-ZrO2 pre-made ceramic sheets with a uniform distribution of 100-400 mesh.

[0056] (3) Pour the powder of the pre-made ceramic sheet SiBCN-ZrO2 into a mold with a cavity size of 35×20×60mm, and use a dry press to press the powder into a pre-made ceramic sheet of a fixed size at a pressure of 10kPa.

[0057] (4) The preformed ceramic surface is placed in a heat treatment furnace with resistance wire as the heating element. In a flowing Ar atmosphere, the furnace temperature is raised from room temperature to 1300℃ at a heating rate of 4℃ / min and held for 1h. The power is turned off and the material is allowed to cool naturally to room temperature to obtain the heat-treated SiBCN-ZrO2 composite ceramic.

[0058] Referring to Figure 1(c), the scanning electron microscope image of the SiBCN-ZrO2 ceramic composite material obtained in this embodiment shows that the ceramic surface is relatively dense; see... Figure 2 As can be seen from the transmission electron microscope images of the SiBCN-ZrO2 ceramic composite material obtained in this embodiment, the zirconium oxide phase is uniformly distributed in the amorphous SiBCN matrix; see also Figure 3 As can be seen from the microwave absorption performance diagram of the SiBCN-ZrO2 ceramic composite material prepared in this embodiment, when the thickness is 3.8 mm, the effective microwave absorption bandwidth of this sample covers the entire X-band; the thermogravimetric results of the SiBCN-ZrO2 ceramic composite material obtained in S3 of this embodiment under oxidation conditions of 20~1400℃ are as follows. Figure 4 As shown, the weight gain of the oxidized ceramic composite material is 3.5%.

[0059] As can be seen from the results of the above embodiments of the present invention, the ceramic composite material has an effective absorption bandwidth of 4.2 GHz in the X-band, which is higher than that of pure PDC-SiBCN ceramic (3.65 GHz), covering the entire X-band, and its oxidation resistance is also improved.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high-temperature-resistant, oxidation-resistant and X-band fully-absorbed SiBCN-ZrO2 ceramic composite material, characterized in that, The method comprises the following steps: Mixing liquid polysilazane and polyacetylacetone zirconium uniformly to obtain mixture A; the volume ratio of the liquid polysilazane and polyacetylacetone zirconium is (1-2):1; Curing the mixture A in a protective atmosphere to obtain a cured block; After the cured block is processed into powder, sieving is performed to obtain 100-400 mesh powder of the preformed ceramic sheet SiBCN-ZrO2; The powder of the preformed ceramic sheet SiBCN-ZrO2 is pressed to obtain a preformed body ceramic sheet; The preformed body ceramic sheet is heated to 1100-1300℃ at a heating rate of 2-5℃ / min in a protective atmosphere, and high-temperature pyrolysis heat treatment is performed for 1-3h, and after the heat preservation is completed, the furnace is cooled to obtain the SiBCN-ZrO2 ceramic composite material which is high-temperature resistant, oxidation resistant and fully absorbed in the X wave band.

2. The preparation method of the SiBCN-ZrO2 ceramic composite material with high-temperature resistance, oxidation resistance and X-band full absorption according to claim 1, characterized in that, The liquid polysilazane and polyacetylacetone zirconium are mixed uniformly at 55-65℃ by mechanical stirring to obtain mixture A.

3. The preparation method of the SiBCN-ZrO2 ceramic composite material with high-temperature resistance, oxidation resistance and X-band full absorption according to claim 1, characterized in that, When the mixture A is cured in a protective atmosphere, the curing temperature is 200-300℃, and the curing time is 1-3h.

4. The preparation method of the SiBCN-ZrO2 ceramic composite material with high-temperature resistance, oxidation resistance and X-band full absorption according to claim 1, characterized in that, The cured block is processed into powder by ball milling, and when ball milling is performed, the rotation speed is 40-60rpm, and the time is 5-12h.

5. The preparation method of the SiBCN-ZrO2 ceramic composite material with high-temperature resistance, oxidation resistance and X-band full absorption according to claim 1, characterized in that, When the powder of the preformed ceramic sheet SiBCN-ZrO2 is pressed, the pressure is 5-15kPa.

6. The preparation method of the SiBCN-ZrO2 ceramic composite material with high-temperature resistance, oxidation resistance and X-band full absorption according to claim 1, characterized in that, The protective atmosphere is argon.

7. A SiBCN-ZrO2 ceramic composite material which is high-temperature resistant, oxidation resistant and fully absorbed in the X wave band, and is prepared by the preparation method of any one of claims 1-6.

8. The high-temperature oxidation resistant and X-band totally absorbing SiBCN-Zr02 ceramic composite according to claim 7, characterized in that, The reflectance of the SiBCN-ZrO2 ceramic composite material which is high-temperature resistant, oxidation resistant and fully absorbed in the X wave band is at least -34.8dB, and the effective absorption bandwidth is 4.2GHz.

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