Method for preparing SiC wave-absorbing material by taking zirconium n-butoxide as raw material

Abstract

The invention discloses a method for preparing a SiC wave-absorbing material by taking zirconium n-butoxide as a raw material, and relates to a method for preparing the SiC wave-absorbing material. The invention aims to solve the problems of complex preparation process, high cost and insufficient bandwidth of the existing silicon carbide wave-absorbing material. The method comprises the following steps: 1, preparing a precursor; 2, high-temperature calcination; and 3, carbon removal treatment. The method is used for preparing the SiC wave-absorbing material by taking the zirconium n-butoxide as the raw material.

Description

Technical Field

[0001] The present invention relates to a method for preparing SiC absorbing material. Background Art

[0002] With the rapid development of modern communication, radar and electronic technologies, the electromagnetic environment has become increasingly complex. Absorbing materials play an important role in military stealth technology, electromagnetic interference suppression in the communication field, and electromagnetic shielding of electronic devices. Currently, common absorbing materials include carbon-based materials, magnetic materials, and silicon carbide materials. Among them, silicon carbide, as a high-performance ceramic material, has high hardness, high strength, and excellent high-temperature resistance. These excellent properties make it show great potential in the field of absorbing materials. However, the preparation process of traditional silicon carbide absorbing materials is complex, costly, and has insufficient bandwidth. Summary of the Invention

[0003] The present invention aims to solve the problems of complex preparation process, high cost, and insufficient bandwidth of existing silicon carbide absorbing materials, and further provides a method for preparing SiC absorbing material using zirconium n-butoxide as a raw material.

[0004] A method for preparing SiC absorbing material using zirconium n-butoxide as a raw material is carried out according to the following steps:

[0005] I. Preparation of precursor:

[0006] Drop zirconium n-butoxide into absolute ethanol to obtain a zirconium n-butoxide solution. Mix silicon powder, silicon dioxide, and carbon black evenly, then add the zirconium n-butoxide solution, and then add deionized water. Stir at room temperature and a rotation speed of 300 rpm to 500 rpm for 2 h to 3 h to obtain a gel or precipitate. Dry and grind the gel or precipitate into a powder to obtain the precursor;

[0007] II. High-temperature calcination:

[0008] Under an argon atmosphere, heat the precursor to 1450 °C to 1550 °C, and then under an argon atmosphere and at a temperature of 1450 °C to 1550 °C, perform high-temperature calcination for 100 min to 120 min. Finally, cool down under an argon atmosphere to obtain the calcined product;

[0009] III. Decarburization treatment:

[0010] Heat the calcined product to 650 °C to 700 °C, and then under a temperature of 650 °C to 700 °C, perform decarburization for 100 min to 120 min. Finally, cool down to complete the method for preparing SiC absorbing material using zirconium n-butoxide as a raw material.

[0011] The beneficial effects of the present invention are:

[0012] 1. Excellent wave absorption performance: The present invention provides a method for preparing silicon carbide composite powder using zirconium butoxide as a raw material. The obtained silicon carbide composite powder exhibits excellent wave absorption performance. In the frequency band of 8 GHz to 18 GHz, the minimum reflection loss reaches -12 dB to -15 dB, and the absorption bandwidth (reflection loss less than -10 dB) exceeds 5 GHz, showing broadband wave absorption characteristics. The present invention overcomes the defects of traditional silicon carbide wave absorption materials such as insufficient bandwidth and complex preparation. Through the design of the material microstructure, efficient impedance matching and excellent electromagnetic wave absorption performance are achieved. This material is suitable for radar stealth, electromagnetic shielding, and anti-interference fields of electronic devices. The preparation method has a simple process and is suitable for large-scale production.

[0013] 2. Realize the controllable synthesis of composition and structure: The present invention precisely controls the composition and structure in the SiC composite powder by adjusting reaction conditions (such as temperature, carbon-silicon ratio): by adjusting the calcination temperature, controlling the decomposition rate of zirconium butoxide to ensure the uniform generation of nano-zirconia particles; regulating the reaction process according to the atmosphere conditions (argon gas) to optimize the carbonization degree of SiC and the phase composition of zirconia; precisely adjusting the carbon-silicon ratio to control the precipitation amount and distribution state of zirconia particles, avoiding agglomeration or segregation phenomena. The innovation of this technology lies in the precise control of the key parameters in the synthesis process, overcoming the problems of uneven particle distribution and uncontrollable microstructure in traditional processes, and providing a scientific basis and technical support for the large-scale production of high-performance materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the reflection loss diagram of the ZrO2 / SiC composite powder prepared in Example 1;

[0015] Figure 2 It is the surface scan diagram of the ZrO2 / SiC composite powder prepared in Example 1;

[0016] Figure 3 It is the XRD scan diagram of the ZrO2 / SiC composite powder prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] Detailed Description 1: A method for preparing SiC wave absorption material using zirconium butoxide as a raw material in this embodiment is carried out according to the following steps:

[0018] I. Preparation of the precursor:

[0019] Drop zirconium butoxide into absolute ethanol to obtain a zirconium butoxide solution. Mix silicon powder, silicon dioxide, and carbon black evenly, then add the zirconium butoxide solution, and then add deionized water. Stir at room temperature and a rotation speed of 300 rpm to 500 rpm for 2 h to 3 h to obtain a gel or precipitate. Dry and grind the gel or precipitate into a powder to obtain the precursor;

[0020] II. High-temperature calcination:

[0021] Under an argon atmosphere, the precursor is heated to 1450°C - 1550°C, and then under the conditions of an argon atmosphere and a temperature of 1450°C - 1550°C, it is calcined at high temperature for 100 min - 120 min, and finally cooled under an argon atmosphere to obtain the calcined product;

[0022] III. Decarburization treatment:

[0023] The calcined product is heated to 650°C - 700°C, and then under the condition of a temperature of 650°C - 700°C, decarburization is carried out for 100 min - 120 min, and finally cooled down, thus completing the method for preparing SiC absorbing material using zirconium butoxide as the raw material.

[0024] The beneficial effects of this embodiment are as follows:

[0025] 1. Excellent wave absorption performance: This embodiment provides a method for preparing silicon carbide composite powder using zirconium butoxide as the raw material, and the obtained silicon carbide composite powder exhibits excellent wave absorption performance. In the frequency band of 8 GHz - 18 GHz, the lowest reflection loss reaches -12 dB to -15 dB, and the absorption bandwidth (reflection loss less than -10 dB) exceeds 5 GHz, showing broadband wave absorption characteristics. This embodiment overcomes the defects of traditional silicon carbide absorbing materials such as insufficient bandwidth and complex preparation, and through the design of the material microstructure, realizes efficient impedance matching and excellent electromagnetic wave absorption performance. This material is applicable to the fields of radar stealth, electromagnetic shielding, and anti-interference of electronic devices, and the preparation method has a simple process and is suitable for large-scale production.

[0026] 2. Realize the controllable synthesis of composition and structure: In this embodiment, the precise control of the composition and structure in the SiC composite powder is achieved by adjusting the reaction conditions (such as temperature, carbon-silicon ratio): by adjusting the calcination temperature, controlling the decomposition rate of zirconium butoxide to ensure the uniform generation of nano-zirconia particles; regulating the reaction process according to the atmosphere conditions (argon) to optimize the carbonization degree of SiC and the phase composition of zirconia; precisely adjusting the carbon-silicon ratio to control the precipitation amount and distribution state of zirconia particles, avoiding agglomeration or segregation phenomena. The innovation of this technology lies in the precise control of the key parameters in the synthesis process, overcoming the problems of uneven particle distribution and uncontrollable microstructure in traditional processes, and providing a scientific basis and technical support for the large-scale production of high-performance materials.

[0027] Specific embodiment two: The difference between this embodiment and specific embodiment one is that the mass ratio of the silicon powder to the silicon dioxide in step one is 1:(2 - 2.14). Others are the same as specific embodiment one.

[0028] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that: in Step 1, the mass ratio of the silicon powder to the carbon black is 1:(1.68 - 1.72). Others are the same as Embodiment 1 or 2.

[0029] Embodiment 4: The difference between this embodiment and Embodiment 1 to 3 is that: in Step 1, the mass ratio of the silicon powder to the zirconium butoxide solution is 1:(0.68 - 6.83); the mass percentage content of zirconium butoxide in the zirconium butoxide solution in Step 1 is 35% - 45%. Others are the same as Embodiment 3.

[0030] Embodiment 5: The difference between this embodiment and Embodiment 1 to 4 is that: in Step 1, the zirconium butoxide is dropped into anhydrous ethanol at an addition rate of 10 g / min - 15 g / min; deionized water is added at an addition rate of 10 g / min - 15 g / min. Others are the same as Embodiment 1 to 4.

[0031] Embodiment 6: The difference between this embodiment and Embodiment 1 to 5 is that: in Step 1, the mass ratio of the silicon powder to the deionized water is 1:(8.99 - 17.98). Others are the same as Embodiment 1 to 5.

[0032] Embodiment 7: The difference between this embodiment and Embodiment 1 to 6 is that: in Step 2, the temperature increase is specifically carried out in an argon atmosphere. Within 80 min - 100 min, the precursor is first heated to 450°C - 500°C, then within 30 min - 35 min, heated to 800°C - 850°C, then within 30 min - 40 min, heated to 1000°C - 1100°C, and finally within 180 min - 200 min, heated to 1450°C - 1500°C. Others are the same as Embodiment 1 to 6.

[0033] Embodiment 8: The difference between this embodiment and Embodiment 1 to 7 is that: in Step 2, the temperature decrease is specifically carried out in an argon atmosphere. Within 180 min - 200 min, it is first cooled to 950°C - 1000°C, then within 130 min - 140 min, cooled to 270°C - 300°C, and finally naturally cooled to room temperature. Others are the same as Embodiment 1 to 7.

[0034] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is that: in Step 3, the temperature increase is specifically to first increase the temperature to 45°C to 55°C, and then increase the temperature at a rate of 8°C / min to 12°C / min to 450°C to 500°C, and then increase the temperature at a rate of 3°C / min to 6°C / min to 650°C to 700°C. Others are the same as those in Embodiments 1 to 8.

[0035] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is that: in Step 3, the temperature decrease is specifically to decrease the temperature at a rate of 3°C / min to 6°C / min to 450°C to 500°C, and then decrease the temperature at a rate of 8°C / min to 12°C / min to 45°C to 55°C, and finally cool naturally to room temperature. Others are the same as those in Embodiments 1 to 9.

[0036] The following examples are used to verify the beneficial effects of the present invention:

[0037] Example 1:

[0038] A method for preparing SiC wave-absorbing material using zirconium butoxide as raw material, which is carried out according to the following steps:

[0039] I. Preparation of precursor:

[0040] Zirconium butoxide was added dropwise to absolute ethanol at an addition rate of 12.5 g / min to obtain a zirconium butoxide solution. Silicon powder, silica and carbon black were mixed evenly, then the zirconium butoxide solution was added, and then deionized water was added at an addition rate of 13.32 g / min. Stir at room temperature and a rotation speed of 400 rpm for 3 h to obtain a gel. Dry the gel at 60°C for 23 h and grind it into powder to obtain the precursor;

[0041] The mass ratio of the silicon powder to the silica is 1:2.139; the mass ratio of the silicon powder to the carbon black is 1:1.7107; the mass ratio of the silicon powder to the zirconium butoxide solution is 1:6.83; the mass percentage content of zirconium butoxide in the zirconium butoxide solution is 40%; the mass ratio of the silicon powder to the deionized water is 1:17.98;

[0042] II. High-temperature calcination:

[0043] Under an argon atmosphere, the precursor was heated to 1500°C, and then under an argon atmosphere and at a temperature of 1500°C, high-temperature calcination was carried out for 120 min, and finally cooled under an argon atmosphere to obtain the calcined product;

[0044] III. Decarbonization treatment:

[0045] Heat the calcined product to 700 °C, then remove carbon for 120 min at 700 °C, and finally cool down to obtain the ZrO2 / SiC composite powder.

[0046] The heating in step 2 is specifically carried out in an argon atmosphere. Within 100 min, the precursor is first heated to 500 °C, then within 30 min, heated to 800 °C, then within 40 min, heated to 1000 °C, and finally within 200 min, heated to 1500 °C.

[0047] The cooling in step 2 is specifically carried out in an argon atmosphere. Within 200 min, first cool down to 1000 °C, then within 140 min, cool down to 300 °C, and finally cool naturally to room temperature.

[0048] The heating in step 3 is specifically carried out by first heating to 50 °C, then at a heating rate of 10 °C / min, heating to 500 °C, and then at a heating rate of 5 °C / min, heating to 700 °C.

[0049] The cooling in step 3 is specifically carried out at a cooling rate of 5 °C / min to cool down to 500 °C, then at a cooling rate of 10 °C / min to cool down to 50 °C, and finally cool naturally to room temperature.

[0050] (1) Wave absorption performance:

[0051] Mix the ZrO2 / SiC composite powder prepared in Example 1 with paraffin and press it into a tablet. The mass percentage of the ZrO2 / SiC composite powder is 50%, and the thickness is 1.8 mm. Then, test the wave absorption performance of the prepared sample. Figure 1 is the reflection loss diagram of the ZrO2 / SiC composite powder prepared in Example 1; as can be seen from the figure, the ZrO2 / SiC composite powder has good wave absorption performance at about 10 GHz and within a certain frequency range nearby. In the frequency band of 8 GHz - 18 GHz, the lowest reflection loss reaches -12 dB to -15 dB, and the absorption bandwidth (reflection loss less than -10 dB) exceeds 5 GHz, which can effectively absorb electromagnetic waves and reduce reflection.

[0052] (2) Scanning electron microscope test:

[0053] Figure 2 is the surface scanning diagram of the ZrO2 / SiC composite powder prepared in Example 1; the scale indicates that the image was taken at a magnification of 10,000 times, showing micron-level features. As can be seen from the figure, the composite powder has a fine structure and micron-level features. The specific analysis is as follows:

[0054] ① shows the microstructure of the ZrO2 / SiC composite powder, especially the silicon carbide (SiC) powder treated by a specific process. The powder particles have an irregular and somewhat porous appearance. This is typical for ceramic composite powders, where the interaction between the zirconium precursor and silicon results in the formation of a structure with surface roughness or textural features. The branched structure shown in the SEM image represents the silicon carbide (SiC) crystals formed during this process.

[0055] ② The surface of the composite powder shows roughness and somewhat aggregated texture, indicating that sintering or chemical reactions occurred during the formation of SiC. This texture is due to the transformation of the precursor material into the ceramic phase.

[0056] ③ The image shows a combination of what appears to be more compact clusters and dispersed powder, which is characteristic of materials processing techniques such as sol-gel or pyrolysis for preparing composite powders. It can thus be determined that the zirconium-based precursor (C 16 H 36 O4Zr) is heat-treated in the presence of a carbon source to form SiC through a carbothermal reduction process.

[0057] ④ In the SEM image, the microstructure of the composite powder can be observed, especially the distribution of nanoscale zirconia (ZrO2) particles. After the decomposition of zirconium n-butoxide, uniformly distributed nanoscale zirconia particles are formed. Some distinct particles or crystallizations can be seen from the figure, and these structures represent the distribution of zirconia particles in the SiC matrix. Although there are certain differences in the particle sizes in the image, overall, their distribution is relatively uniform, in line with the characteristics of nanoscale zirconia particles mentioned in the existing literature.

[0058] (3) XRD test:

[0059] Figure 3 XRD scan of the ZrO2 / SiC composite powder prepared in Example 1; as can be seen from the figure, the ZrO2 / SiC composite powder prepared in Example 1 has good crystallinity and high phase purity, indicating that its atomic arrangement is regular, while reducing defects caused by impurities and enhancing the consistency and stability of the overall performance; in addition, the clear XRD pattern shows that the material structure is uniform and stable, with strong processability and application adaptability. The specific analysis is as follows:

[0060] ① As can be seen from the XRD pattern, the material shows multiple clear diffraction peaks, and the positions of the diffraction peaks are consistent with the standard diffraction peaks of SiC. In addition, the appearance of characteristic peaks of zirconia (ZrO2) (35.6°, 30.3°, and 60°) in the pattern proves that the material does contain the zirconia phase and the material has good crystallinity.

[0061] ② Calculate the grain sizes of SiC and zirconia phases using the Scherrer formula according to the widths of the diffraction peaks in the XRD pattern:

[0062]

[0063] Among them, D is the grain size, k is a constant (usually taken as 0.9), λ is the X-ray wavelength, β is the full-width at half-maximum of the diffraction peak, and θ is the diffraction angle. Select relatively clear zirconia diffraction peaks (such as 35.6° and 30.3°), measure the full-width at half-maximum (β) and substitute it into the formula to calculate the grain size. The size of the grain can help judge the crystallinity and mechanical properties of the material. After calculation, the grain size of zirconia is 47.6 nm, and the grain size of SiC can be calculated to be 29.5 nm using the same method.

[0064] ③ Use the XRD quantitative analysis method to estimate the relative contents of different phases. The relative contents of different phases in the material are estimated as follows: ZrO2 is 73.7%, and SiC is 26.3%. The peak positions of zirconia are clear, indicating its good distribution in the material. Combining the sharpness of the peaks and the low background noise, it is confirmed that the phase purity is high. A relatively high phase purity indicates that there are few impurities in the material.

[0065] ④ The intensities of the diffraction peaks in the XRD pattern reflect the crystallinity of the material. The crystallization peaks in the XRD pattern indicate that the crystal structure of the ZrO2 / SiC composite powder is relatively uniform and ordered.

Claims

1. A method for preparing SiC microwave absorbing material using zirconium butoxide as raw material, characterized in that It is carried out according to the following steps: I. Preparation of precursor: Drop zirconium butoxide into absolute ethanol to obtain a zirconium butoxide solution. Mix silicon powder, silicon dioxide and carbon black evenly, then add the zirconium butoxide solution, and then add deionized water. Stir for 2 h to 3 h at room temperature and a rotation speed of 300 rpm to 500 rpm to obtain a gel or precipitate. Dry and grind the gel or precipitate into powder to obtain the precursor; II. High-temperature calcination: Under an argon atmosphere, heat the precursor to 1450 °C to 1550 °C, and then carry out high-temperature calcination for 100 min to 120 min under an argon atmosphere and at a temperature of 1450 °C to 1550 °C. Finally, cool down under an argon atmosphere to obtain the calcined product; III. Decarburization treatment: Heat the calcined product to 650 °C to 700 °C, and then carry out decarburization for 100 min to 120 min at a temperature of 650 °C to 700 °C. Finally, cool down to complete the method for preparing the SiC wave-absorbing material using zirconium butoxide as the raw material.

2. The method for preparing SiC wave-absorbing material using zirconium butoxide as raw material according to claim 1, characterized in that The mass ratio of the silicon powder to the silicon dioxide described in step I is 1:(2 - 2.14).

3. The method for preparing the SiC wave-absorbing material using zirconium butoxide as a raw material according to claim 1, characterized in that The mass ratio of the silicon powder to the carbon black described in step I is 1:(1.68 - 1.72).

4. A method for preparing SiC microwave absorbing material using zirconium butoxide as raw material according to claim 1, characterized in that The mass ratio of the silicon powder to the zirconium butoxide solution described in step I is 1:(0.68 - 6.83); the mass percentage content of zirconium butoxide in the zirconium butoxide solution described in step I is 35% - 45%.

5. A method for preparing SiC microwave absorption material using zirconium butoxide as raw material according to claim 1, characterized in that In step I, drop zirconium butoxide into absolute ethanol at an addition rate of 10 g / min to 15 g / min; in step I, add deionized water at an addition rate of 10 g / min to 15 g / min.

6. A method for preparing SiC microwave absorption material using zirconium butoxide as raw material according to claim 1, characterized in that The mass ratio of the silicon powder to the deionized water described in step I is 1:(8.99 - 17.98).

7. A method for preparing SiC microwave absorbing material using zirconium butoxide as raw material according to claim 1, characterized in that The temperature increase described in step II is specifically carried out under an argon atmosphere. Within 80 min to 100 min, first heat the precursor to 450 °C to 500 °C, then within 30 min to 35 min, heat it to 800 °C to 850 °C, then within 30 min to 40 min, heat it to 1000 °C to 1100 °C, and finally within 180 min to 200 min, heat it to 1450 °C to 1500 °C.

8. A method for preparing SiC microwave absorption material using zirconium butoxide as raw material according to claim 1, characterized in that The temperature decrease described in step II is specifically carried out under an argon atmosphere. Within 180 min to 200 min, first cool it down to 950 °C to 1000 °C, then within 130 min to 140 min, cool it down to 270 °C to 300 °C, and finally naturally cool it to room temperature.

9. A method for preparing SiC microwave absorbing material using zirconium butoxide as raw material according to claim 1, characterized in that The temperature increase described in step III is specifically to first heat it to 45 °C to 55 °C, then at a heating rate of 8 °C / min to 12 °C / min, heat it to 450 °C to 500 °C, and then at a heating rate of 3 °C / min to 6 °C / min, heat it to 650 °C to 700 °C.

10. The method for preparing the SiC microwave absorption material using zirconium butoxide as a raw material according to claim 1, wherein The temperature decrease described in step III is specifically at a cooling rate of 3 °C / min to 6 °C / min, cool it down to 450 °C to 500 °C, then at a cooling rate of 8 °C / min to 12 °C / min, cool it down to 45 °C to 55 °C, and finally naturally cool it to room temperature.

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