TiB2 / SiO2 composite material and preparation method thereof

Abstract

The invention discloses a TiB2 / SiO2 composite material and a preparation method thereof, and relates to the technical field of new materials.The preparation method of the TiB2 / SiO2 composite material comprises the following steps that TiB2 is pretreated with a NaOH solution, then Na2SiO3. 9H2O and deionized water are mixed and then added into the pretreatment solution, the pH is adjusted to be 8.5, stirring is conducted for 2 h at the temperature of 85 DEG C, and the TiB2 / SiO2 composite material is obtained; and sequentially carrying out centrifugal filtration, washing and drying to obtain the product. The TiB2 / SiO2 powder product is prepared through a specific chemical solution process, the TiB2 / SiO2 powder product has excellent dielectric properties and can be used for manufacturing wave-absorbing materials and reducing reflection of electromagnetic waves, and TiB2 and SiO2 both have excellent oxidation resistance, so that the TiB2 / SiO2 powder product prepared through the method has greater application potential at high temperature.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, in particular to a TiB2 / SiO2 composite material and a preparation method thereof. Background Art

[0002] Titanium diboride (TiB2), as an ultra-high temperature ceramic material, is famous for its high melting point, high hardness, good corrosion resistance and oxidation resistance, as well as excellent high temperature electrical and mechanical properties. It has a wide range of applications in aerospace, high temperature structural materials, wear-resistant materials, electronic devices, and high temperature radar stealth.

[0003] There are many methods for optimizing the wave absorption performance of TiB2 in the prior art, which mainly modify the surface of nano-TiB2, change the surface composition of TiB2 to regulate impedance matching and dielectric loss performance, and effectively improve its wave absorption performance. For example, Chinese patent CN202311613311.0 discloses a method for preparing a TiB2-derived TiO2 nanoflower composite material, in which TiB2 nanoparticles and a certain amount of HF solution are added to an EDA aqueous solution, and the autoclave is sealed for hydrothermal reaction for 24 hours. After the reaction is completed, the precipitate is collected by centrifugation, washed and dried to obtain a blue solid powder. Calcined at 500℃-700℃ for 1h under a protective atmosphere, a blue TiB2-derived TiO2 nanoflower composite material is obtained; in this method, a heterogeneous interface can be formed between different phases in the material, causing interface polarization and improving the polarization loss capacity. However, the existing method still has limitations, and the wave absorption performance of the obtained product needs to be improved. Summary of the invention

[0004] In view of this, the present invention proposes a TiB2 / SiO2 composite material and a preparation method thereof, and uses TiB2 prepared by a specific method as a raw material to prepare a TiB2 / SiO2 composite material with better wave absorbing performance.

[0005] The present invention discloses a method for preparing a TiB2 / SiO2 composite material, comprising the following steps:

[0006] Step S1: pretreating TiB2 with 0.01 g / mL NaOH solution for 10 min;

[0007] Step S2: Na2SiO3·9H2O is mixed with deionized water and then added to the solution pretreated with TiB2 to obtain solution A;

[0008] Step S3: adjust the pH of solution A to 8.5 with dilute hydrochloric acid, stir at 85° C. for 2 h, and then centrifuge, filter, wash, and dry in sequence to obtain the product.

[0009] One embodiment of the present invention is that, in terms of molar ratio, the ratio of Na2SiO3·9H2O to TiB2 in step S2 is 0.01 to 0.07:1.

[0010] In one embodiment of the present invention, the drying temperature in step S3 is 60-90° C., and the drying time is 3-7 hours.

[0011] One embodiment of the present invention is that the preparation method of TiB2 in step S1 comprises the following steps:

[0012] Step 1: TiO2 and B4C are ball-milled at a speed of 150-500 r / min for 6-48 hours using anhydrous ethanol as a ball-milling aid and then dried;

[0013] Step 2: calcining the dried ball-milled powder at 1000-2000° C. for 0.5-3 h in an argon atmosphere;

[0014] Step 3: Collect the calcined product and perform ultrasonic washing with water and / or ethanol;

[0015] Step 4: Dry the product after ultrasonic washing.

[0016] Furthermore, in terms of mass ratio, the ratio of the raw materials to the grinding balls in step 1 is 1:3-7.

[0017] Furthermore, in terms of molar ratio, the ratio of TiO2 to B4C in step 1 is 7:5 to 6.5.

[0018] Furthermore, the drying temperature in step 1 is 60-90° C., and the drying time is 3-7 hours.

[0019] And the TiB2 / SiO2 composite material prepared by the method.

[0020] The technical effects of the present invention are:

[0021] The present invention obtains a TiB2 / SiO2 powder product through a specific chemical solution process, which has excellent dielectric properties and can be used to manufacture absorbing materials, reduce the reflection of electromagnetic waves, and improve stealth performance. In addition, both TiB2 and SiO2 have excellent antioxidant properties, so that the TiB2 / SiO2 powder product prepared by the present invention has greater application potential at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 (a) is the XRD spectrum of TiB2 prepared in Example 2;

[0023] Figure 1 (b) is the XRD spectrum of TiB2 / SiO2 prepared in Example 2;

[0024] Figure 2 (a) is a microstructure diagram of TiB2 prepared in Example 2 at a size of 2 μm;

[0025] Figure 2 (b) is a microstructure diagram of TiB2 / SiO2 prepared in Example 2 at a size of 2 μm;

[0026] Figure 3 (a) is a test graph of the real part of the dielectric constant of the TiB2 / PDMS composite material composed of 70wt% of TiB2 prepared in Example 1 of the present invention and the TiB2 / SiO2 / PDMS composite material composed of 70wt% of TiB2 prepared in Example 1;

[0027] Figure 3 (b) is a test graph of the imaginary part of the dielectric constant of the TiB2 / PDMS composite material composed of 70wt% of TiB2 prepared in Example 1 of the present invention and the TiB2 / SiO2 / PDMS composite material composed of 70wt% of TiB2 prepared in Example 1;

[0028] Figure 3 (c) is a test graph of dielectric loss tangent of a TiB2 / PDMS composite material composed of 70 wt% TiB2 prepared in Example 1 of the present invention and a TiB2 / SiO2 / PDMS composite material composed of 70 wt% TiB2 prepared in Example 1;

[0029] Figure 4 (a) is a two-dimensional result diagram of reflection loss (RL) of a TiB2 / PDMS composite material composed of 70 wt% TiB2 prepared in Example 1 of the present invention;

[0030] Figure 4 (b) is a two-dimensional RL result diagram of the TiB2 / SiO2 / PDMS composite material with a content of 70 wt% of TiB2 / SiO2 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents, etc. used therein are all commercially available unless otherwise specified.

[0032] Example 1

[0033] TiO2 and B4C were weighed in a molar ratio of 7:5, and put into a ball mill together with grinding balls, and an appropriate amount of anhydrous ethanol was added for ball milling. The ball milling time was 24 hours, the ball milling speed was 300 r / min, the raw material and grinding ball mass ratio was 1:5, and the mass distribution of grinding balls according to size specifications was: large (8mm): medium (5mm): small (3mm) mass ratio of 2:5:3.

[0034] Then, the ball-milled powder was placed in a drying oven and dried at 80° C. for 5 h to obtain a dry mixed powder.

[0035] The dried mixed powder raw material was placed in a boron nitride crucible, and then placed in a tubular atmosphere furnace, and calcined at a calcination temperature of 1650° C. for 1 h to obtain a calcined product.

[0036] Collect the calcined product, evaporate it in deionized water at 90°C with magnetic stirring and add water in an appropriate amount, continue to evaporate it in a water bath with magnetic stirring, filter it when half of the deionized water has evaporated, add anhydrous ethanol and ultrasonically stir it for 30 minutes, then filter it again, repeat adding anhydrous ethanol and ultrasonically stir it for 30 minutes, finally filter it and dry it to obtain TiB2.

[0037] Take 1g of the TiB2 obtained above and pretreat it with 100mL of 0.01g / ml NaOH solution for 10min, then mix Na2SiO3·9H2O with deionized water to obtain a 2.6g / L Na2SiO3·9H2O deionized water mixed solution, take 100mL of the mixed solution and add it to the above TiB2 pretreated solution to obtain solution A, add dilute hydrochloric acid to adjust the solution pH to 8.5, and stir it magnetically at 85℃ for 2h. Then centrifuge, filter, wash and dry in sequence to obtain the TiB2 / SiO2 composite material.

[0038] Example 2

[0039] The implementation method of this embodiment is basically the same as that of Example 1, except that the molar ratio of TiO2 and B4C used to prepare TiB2 in this embodiment is 7:5.75, and the amount of TiB2 pretreated by NaOH is 2 g.

[0040] Example 3

[0041] The implementation method of this embodiment is basically the same as that of Example 1, except that the molar ratio of TiO2 and B4C used to prepare TiB2 in this embodiment is 7:6.5, and the amount of TiB2 pretreated by NaOH is 3g.

[0042] In order to better illustrate the technical effects of the present invention, performance evaluation of relevant embodiments is provided below.

[0043] 1. Product phase and microstructure analysis

[0044] Figure 1 (a) and (b) show the phase composition of the TiB2 product synthesized at 1650°C in Example 2 and the phase composition of the obtained TiB2 / SiO2 material. Figure 1 As shown in (a), under the condition of calcination temperature of 1650℃, the product synthesized by B4C thermal reduction method in argon atmosphere is mainly TiB2, and the 9 diffraction peaks of TiB2 product appear at 27.60°, 34.13°, 44.44°, 56.99°, 61.10°, 68.13°, 68.33°, 71.89° and 78.64°, respectively. These diffraction peaks correspond to the (001), (100), (101), (002), (110), (102), (111), (200) and (201) crystal planes of TiB2, respectively, with a typical hexagonal lattice structure (PDF#35~0741). The product synthesized at this temperature is pure TiB2 without impurities. Figure 1 (b) shows the phase composition of the TiB2 / SiO2 material prepared on the basis of TiB2 synthesized at 1650°C in Example 2. It can be clearly seen that the product contains only TiB2 and SiO2 phases without other impurities.

[0045] Figure 2 (a) and (b) mainly characterize the microstructure of TiB2 and TiB2 / SiO2 products by scanning electron microscopy (SEM). Figure 2 In (a), the TiB2 synthesized in Example 2 exhibits a short rod-like microstructure with a diameter of about 1 to 2 μm and a diameter range of 500 to 800 nm. The surface of the TiB2 product is smooth and clean, and the two ends of the short rod-like morphology have bifurcations. Figure 2 In (b), TiB2 still shows a short rod-like morphology with a smooth surface. At the same time, SiO2 particles with a size of 50 to 200 nm are attached to the surface of TiB2 to form a TiB2 / SiO2 composite material. SiO2 particles are evenly distributed in the TiB2 powder, which can introduce a large number of heterogeneous interfaces and defects between SiO2 and TiB2, further enhancing the polarization loss capacity in the TiB2 / SiO2 composite material.

[0046] 2. Dielectric Constant Characterization

[0047] The composite dielectric constant is widely considered to be a key factor in determining the electromagnetic wave absorption performance of dielectric materials. In order to perform performance tests on the TiB2 and TiB2 / SiO2 products prepared in the present invention, the present invention refers to the prior art to prepare TiB2 / PDMS and TiB2 / SiO2 / PDMS composite materials using the TiB2 and TiB2 / SiO2 obtained in Example 1 and polydimethylsiloxane (PDMS), and perform dielectric constant-related characterization and testing. The relevant results are shown in FIG. Figure 3 shown. Figure 3 The dielectric properties of 70wt% TiB2 / PDMS and 70wt% TiB2 / SiO2 / PDMS materials are shown in Fig. Figure 3 As shown in (a) and (b), the real part of the dielectric constant (ε') and the imaginary part of the dielectric constant (ε") of the two samples show similar variation trends in the range of 2 to 18 GHz. Figure 3 In (a), the ε' of both samples decreases significantly with increasing frequency, which is attributed to the inability of the dipole polarization to respond quickly to changes in the applied electric field. Figure 3 In (b) and (c), ε” and dielectric loss tangent (tanδ ε ) show obvious fluctuations in the range of 2 to 18 GH. The fluctuation of 70 wt% TiB2 / PDMS composite material is weaker than that of 70 wt% TiB2 / SiO2 / PDMS composite material. This may be attributed to the strong interface polarization loss caused by the numerous TiB2 / SiO2 heterogeneous interfaces. In addition, by comparing the dielectric properties of the two samples, it can be found that the ε', ε" and tanδ of the 70 wt% TiB2 / PDMS composite material are ε The values ​​are higher than those of 70wt% TiB2 / SiO2 / PDMS composite materials ε', ε" and tanδ ε This is because although the absorbent content of the two samples is the same, the TiB2 / SiO2 composite material contains a large amount of SiO2, which makes the TiB2 / PDMS composite material have a higher content of TiB2 and thus has a higher conductivity, proving that the composite material prepared in the present invention has excellent absorbing properties and can be used to prepare high-performance absorbing materials.

[0048] 3. Reflection loss test

[0049] Figure 4(a) and (b) show the two-dimensional images of RL of 70wt% TiB2 / PDMS and 70wt% TiB2 / SiO2 / PDMS samples prepared on the basis of Example 1 at different frequencies and thicknesses. Compared with the electromagnetic wave absorption (EMWA) performance of the two samples, the EMWA characteristics of 70wt% TiB2 / SiO2 / PDMS are better than those of 70wt% TiB2 / PDMS. For the 70wt% TiB2 / PDMS composite material, when the frequency and thickness are 4.72GHz and 2mm respectively, its minimum reflection loss (RL min ) is -9.67dB, showing unsatisfactory EMWA performance. In contrast, when the frequency and thickness are 16.96GHz and 1.00mm, respectively, the RL of the 70wt% TiB2 / SiO2 / PDMS composite is min It reaches -25.51dB, and its effective absorption bandwidth (EAB) reaches 5.04GHz (RL<-10dB, 12.96~18GHz). The EMWA capability of TiB2 / SiO2 / PDMS composite material has been significantly improved. This is because TiB2 / SiO2 has excellent impedance matching and electromagnetic wave attenuation characteristics.

[0050] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a TiB2 / SiO2 composite material, characterized in that: The following steps are involved: Step S1: pretreating TiB2 with 0.01 g / mL NaOH solution for 10 min; Step S2: Na2SiO3·9H2O is mixed with deionized water and then added to the solution pretreated with TiB2 to obtain solution A; Step S3: adjust the pH of solution A to 8.5 with dilute hydrochloric acid, stir at 85° C. for 2 h, and then centrifuge, filter, wash, and dry in sequence to obtain the product.

2. The method for preparing a TiB2 / SiO2 composite material according to claim 1, characterized in that: In terms of molar ratio, the ratio of Na2SiO3·9H2O to TiB2 in step S2 is 0.01 to 0.07:

1.

3. The method for preparing a TiB2 / SiO2 composite material according to claim 1, characterized in that: The drying temperature in step S3 is 60-90° C., and the drying time is 3-7 hours.

4. The method for preparing a TiB2 / SiO2 composite material according to claim 1, characterized in that: The preparation method of TiB2 in step S1 comprises the following steps: Step 1: TiO2 and B4C are ball-milled at a speed of 150-500 r / min for 6-48 hours using anhydrous ethanol as a ball-milling aid and then dried; Step 2: calcining the dried ball-milled powder at 1000-2000° C. for 0.5-3 h in an argon atmosphere; Step 3: Collect the calcined product and perform ultrasonic washing with water and / or ethanol; Step 4: Dry the product after ultrasonic washing.

5. The method for preparing a TiB2 / SiO2 composite material according to claim 4, characterized in that: In terms of mass ratio, the ratio of the raw materials to the grinding balls in step 1 is 1:3-7.

6. The method for preparing a TiB2 / SiO2 composite material according to claim 4, characterized in that: In terms of molar ratio, the ratio of TiO2 to B4C in step 1 is 7:5 to 6.

5.

7. The method for preparing a TiB2 / SiO2 composite material according to claim 4, characterized in that: The drying temperature in step 1 is 60-90° C., and the drying time is 3-7 hours.

8. A TiB2 / SiO2 composite material, characterized in that: The method is prepared by any one of claims 1 to 7.

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