Preparation method of Ti-doped nano silicon carbide material

Abstract

The invention discloses a preparation method of a Ti-doped nano silicon carbide material, and belongs to the technical field of wave-absorbing materials. The invention aims to solve the problem of lack of simple solid-phase sintering for preparing titanium-doped silicon carbide in the prior art. The method comprises the following steps: 1, uniformly mixing titanium dioxide, silicon powder, silicon dioxide and carbon black; 2, sintering; and 3, removing carbon. The method is used for preparing the Ti-doped nano silicon carbide material.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave absorbing materials. Background Art

[0002] Early microwave absorbing materials mainly relied on metal reflection, having disadvantages such as large weight and wide frequency band. Due to the increasingly prominent problems of electromagnetic wave radiation and interference nowadays, higher requirements are put forward for electromagnetic compatibility and stealth technology. Silicon carbide materials have relatively high dielectric loss and can effectively convert electromagnetic wave energy into heat energy. Nano-silicon carbide has better microwave absorbing performance due to its high specific surface area and quantum effect. Titanium-doped silicon carbide has good microwave absorbing performance, but the existing technology lacks a simple solid-phase sintering method for preparing titanium-doped silicon carbide. Summary of the Invention

[0003] The present invention aims to solve the problem that there is a lack of a simple solid-phase sintering method for preparing titanium-doped silicon carbide in the prior art, and further provides a preparation method for a nano-silicon carbide material doped with Ti element.

[0004] A preparation method for a nano-silicon carbide material doped with Ti element is carried out according to the following steps:

[0005] I. Mix titanium dioxide, silicon powder, silicon dioxide and carbon black evenly to obtain a mixture;

[0006] II. Under an argon atmosphere, heat the mixture to 1400°C - 1550°C, and keep it at this temperature for 1 h - 5 h under the argon atmosphere and at a temperature of 1400°C - 1550°C, and then cool it down under the argon atmosphere to obtain the sintered mixture;

[0007] III. Under an air atmosphere, heat the sintered mixture to 600°C - 800°C, and keep it at this temperature for 2 h - 4 h under the air atmosphere and at a temperature of 600°C - 800°C, and then cool it down under the air atmosphere to obtain the nano-silicon carbide material doped with Ti element.

[0008] The beneficial effects of the present invention are as follows:

[0009] The present invention provides better microwave absorbing performance by doping and modifying elements to sinter nano-silicon carbide at high temperature. Through a one-step reaction to solid-phase synthesize nano-silicon carbide fibers, the performance of silicon carbide is optimized, and the generated nano-silicon carbide is in the 3C phase. This production method is simple to operate and has stable performance, realizing the simple solid-phase sintering for preparing titanium-doped silicon carbide. Description of the Drawings

[0010] Figure 1 XRD diagrams of the nano-silicon carbide materials doped with Ti element prepared in Examples 1 to 4;

[0011] Figure 2SEM image of the nano silicon carbide material doped with Ti element prepared in Example 1;

[0012] Figure 3 Absorbing wave performance diagram of the nano silicon carbide material doped with Ti element prepared in Example 1. Detailed implementation manners

[0013] Detailed implementation manner 1: A preparation method of a nano silicon carbide material doped with Ti element in this implementation manner is carried out according to the following steps:

[0014] 1. Mix titanium dioxide, silicon powder, silicon dioxide and carbon black evenly to obtain a mixture;

[0015] 2. Under an argon atmosphere, heat the mixture to 1400°C - 1550°C, and keep it warm for 1h - 5h under the argon atmosphere and at a temperature of 1400°C - 1550°C, and then cool it down under the argon atmosphere to obtain the sintered mixture;

[0016] 3. Under an air atmosphere, heat the sintered mixture to 600°C - 800°C, and keep it warm for 2h - 4h under the air atmosphere and at a temperature of 600°C - 800°C, and then cool it down under the air atmosphere to obtain the nano silicon carbide material doped with Ti element.

[0017] The beneficial effects of this implementation manner are:

[0018] In this implementation manner, nano silicon carbide is fired at high temperature by the method of element doping modification to provide better wave absorption performance. Nano silicon carbide fibers are synthesized by one-step reaction solid phase to optimize the performance of silicon carbide, and the generated nano silicon carbide is the 3C phase. This production method is simple to operate and has stable performance, realizing the preparation of titanium-doped silicon carbide by simple solid phase sintering.

[0019] Detailed implementation manner 2: The difference between this implementation manner and the first detailed implementation manner is that: the molar ratio of the silicon powder to the silicon dioxide in step 1 is 1:(0.5 - 1.5); the total molar number of the silicon powder and the silicon dioxide in step 1 and the molar ratio of the carbon black is 1:(1 - 2). Others are the same as the first detailed implementation manner.

[0020] Detailed implementation manner 3: The difference between this implementation manner and one of the first or second detailed implementation manners is that: the titanium dioxide in step 1 is one or a combination of anatase and rutile; the mass percentage of titanium dioxide in the mixture in step 1 is 0.1% - 15%. Others are the same as the first or second detailed implementation manner.

[0021] Embodiment 4: The difference between this embodiment and any one of Embodiments 1 to 3 is as follows: In step one, the particle size of the titanium dioxide is 5 nm to 20 nm; the particle size of the silicon powder is 1 μm to 20 μm; the particle size of the silicon dioxide is 300 nm to 700 nm; the particle size of the carbon black is 20 nm to 100 nm. Others are the same as in Embodiment 3.

[0022] Embodiment 5: The difference between this embodiment and any one of Embodiments 1 to 4 is as follows: In step one, the so-called mixing evenly is specifically under the conditions of a rotation speed of 100 r / min to 300 r / min and a ball-to-material mass ratio of 1:(1 to 3), and ball milling for 2 h to 6 h. Others are the same as in Embodiments 1 to 4.

[0023] Embodiment 6: The difference between this embodiment and any one of Embodiments 1 to 5 is as follows: In step two, under an argon atmosphere, first heat up to 450 °C to 550 °C within 80 min to 120 min, then heat up to 700 °C to 900 °C within 20 min to 50 min, then heat up to 950 °C to 1100 °C within 30 min to 60 min, and finally heat up to 1400 °C to 1550 °C within 180 min to 220 min. Others are the same as in Embodiments 1 to 5.

[0024] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is as follows: In step two, the so-called cooling is specifically under an argon atmosphere, first cool down to 950 °C to 1100 °C within 180 min to 220 min, then cool down to 200 °C to 400 °C within 120 min to 160 min, and finally cool down naturally. Others are the same as in Embodiments 1 to 6.

[0025] Embodiment 8: The difference between this embodiment and any one of Embodiments 1 to 7 is as follows: In step three, under an air atmosphere, first heat up to 40 °C to 60 °C, then heat up at a rate of 5 °C / min to 10 °C / min to 400 °C to 500 °C, and then heat up at a rate of 3 °C / min to 5 °C / min to 600 °C to 800 °C. Others are the same as in Embodiments 1 to 7.

[0026] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is as follows: In step three, under an air atmosphere, first cool down at a rate of 3 °C / min to 5 °C / min to 400 °C to 500 °C, then cool down at a rate of 5 °C / min to 10 °C / min to 40 °C to 60 °C, and finally cool down naturally. Others are the same as in Embodiments 1 to 8.

[0027] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is that the flow rates of the argon atmosphere in Step 2 and the air atmosphere in Step 3 are both 20 mL / min to 100 mL / min. Others are the same as those in Embodiments 1 to 9.

[0028] The following examples are used to verify the beneficial effects of the present invention:

[0029] Example 1:

[0030] A method for preparing a Ti-doped nano-silicon carbide material is carried out according to the following steps:

[0031] I. Under the conditions of a rotation speed of 200 r / min and a ball-to-material mass ratio of 1:1, titanium dioxide, silicon powder, silicon dioxide, and carbon black are ball-milled for 4 h to obtain a mixture;

[0032] II. Under an argon atmosphere, the mixture is heated to 1500 °C, and under the argon atmosphere and at a temperature of 1500 °C, it is kept warm for 120 min, and then cooled under the argon atmosphere to obtain a sintered mixture;

[0033] III. Under an air atmosphere, the sintered mixture is heated to 700 °C, and under the air atmosphere and at a temperature of 700 °C, it is kept warm for 120 min, and then cooled under the air atmosphere to obtain a Ti-doped nano-silicon carbide material.

[0034] The molar ratio of the silicon powder to the silicon dioxide in Step I is 1:1; the total molar ratio of the silicon powder and the silicon dioxide to the carbon black in Step I is 1:2.

[0035] The titanium dioxide in Step I is anatase; the mass percentage of titanium dioxide in the mixture in Step I is 1%;

[0036] The average particle size of the titanium dioxide in Step I is 10 nm; the average particle size of the silicon powder in Step I is 5 μm; the average particle size of the silicon dioxide in Step I is 500 nm; the average particle size of the carbon black in Step I is 100 nm.

[0037] In Step II, under the argon atmosphere, it is first heated to 500 °C within 100 min, then heated to 800 °C within 30 min, then heated to 1000 °C within 40 min, and finally heated to 1500 °C within 200 min.

[0038] The cooling in Step II is specifically carried out under the argon atmosphere. First, it is cooled to 1000 °C within 200 min, then cooled to 300 °C within 140 min, and finally cooled naturally.

[0039] In step 3, under an air atmosphere, first heat up to 50 °C, then heat up to 500 °C at a rate of 10 °C / min, and then heat up to 700 °C at a rate of 5 °C / min.

[0040] In step 3, under an air atmosphere, first cool down to 500 °C at a rate of 5 °C / min, then cool down to 50 °C at a rate of 10 °C / min, and finally cool down naturally.

[0041] The flow rates of the argon atmosphere described in step 2 and the air atmosphere described in step 3 are both 50 mL / min.

[0042] Example 2: The difference between this example and Example 1 is that the mass percentage of titanium dioxide in the mixture described in step 1 is 0.5%. Others are the same as in Example 1.

[0043] Example 3: The difference between this example and Example 1 is that the mass percentage of titanium dioxide in the mixture described in step 1 is 5%. Others are the same as in Example 1.

[0044] Example 4: The difference between this example and Example 1 is that the mass percentage of titanium dioxide in the mixture described in step 1 is 10%. Others are the same as in Example 1.

[0045] Figure 1 XRD patterns of the Ti-doped nano-silicon carbide materials prepared for Examples 1 to 4; It can be seen from the figure that the prepared SiC is the 3C phase, and at the same time, the peaks shift, indicating the doping of titanium; when the titanium dosage in Examples 3 and 4 is excessive, anatase and rutile titanium dioxide appear.

[0046] Figure 2 SEM image of the Ti-doped nano-silicon carbide material prepared for Example 1; It can be seen from the figure that the material morphology is mostly silicon carbide fibers.

[0047] Figure 3 Absorbing performance graph of the Ti-doped nano-silicon carbide material prepared for Example 1; It can be seen from the figure that by testing the dielectric constant of the prepared silicon carbide by the coaxial method and fitting the data by software, when the thickness is 4 mm, at 5.1 GHz, the reflectivity is -19.88 dB, and the absorbing performance is the most excellent.

Claims

1. A method for preparing Ti-doped nano-silicon carbide material, characterized in that It is carried out in the following steps:

1. uniformly mixing titanium dioxide, silicon powder, silicon dioxide and carbon black to obtain a mixture; 2. In an argon atmosphere, the mixture is heated to 1400° C. to 1550° C., and kept at 1400° C. to 1550° C. for 1 h to 5 h, and then cooled in the argon atmosphere to obtain a sintered mixture; 3. In an air atmosphere, the sintered mixture is heated to 600°C to 800°C, and kept at 600°C to 800°C for 2h to 4h, and then cooled in an air atmosphere to obtain a nano-silicon carbide material doped with Ti element.

2. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that The molar ratio of the silicon powder to silicon dioxide in step one is 1:(0.5-1.5); the molar ratio of the total moles of silicon powder and silicon dioxide to carbon black in step one is 1:(1-2).

3. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that The titanium dioxide described in step 1 is one or a combination of anatase and rutile; the mass percentage of titanium dioxide in the mixture described in step 1 is 0.1% to 15%.

4. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that The particle size of the titanium dioxide described in step 1 is 5nm to 20nm; the particle size of the silicon powder described in step 1 is 1μm to 20μm; the particle size of the silicon dioxide described in step 1 is 300nm to 700nm; the particle size of the carbon black described in step 1 is 20nm to 100nm.

5. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that The uniform mixing described in step 1 is specifically performed by ball milling for 2h to 6h at a rotation speed of 100r / min to 300r / min and a ball-to-material mass ratio of 1:(1 to 3).

6. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that In step 2, under an argon atmosphere, the temperature is first raised to 450°C to 550°C within 80min to 120min, then raised to 700°C to 900°C within 20min to 50min, then raised to 950°C to 1100°C within 30min to 60min, and finally raised to 1400°C to 1550°C within 180min to 220min.

7. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that The cooling described in step 2 is specifically to cool down to 950°C to 1100°C within 180min to 220min under argon atmosphere, then cool down to 200°C to 400°C within 120min to 160min, and finally cool down naturally.

8. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that In step 3, under air atmosphere, the temperature is first raised to 40°C to 60°C, then raised to 400°C to 500°C at a rate of 5°C / min to 10°C / min, and then raised to 600°C to 800°C at a rate of 3°C / min to 5°C / min.

9. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that In step 3, under air atmosphere, the temperature is first lowered to 400°C to 500°C at a rate of 3°C / min to 5°C / min, then lowered to 40°C to 60°C at a rate of 5°C / min to 10°C / min, and finally cooled naturally.

10. The method for preparing a Ti-doped nano-silicon carbide material according to claim 1, characterized in that The flow rates of the argon atmosphere in step 2 and the air atmosphere in step 3 are both 20 mL / min to 100 mL / min.

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