CN110818431A - Zirconium-containing polyborosilazane precursor aerogel, silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel, and preparation method and application thereof - Google Patents

Abstract

The invention discloses zirconium-containing polyborosilazane precursor aerogel, silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel, and a preparation method and application thereof, wherein the preparation method combines hydrosilylation reaction and CO₂Supercritical drying, preparing highly porous zirconium-containing PBSN precursor ceramic aerogel by taking polyborosilazane and ZBO as precursors, and then synthesizing SiBCN-ZrO by a traditional precursor conversion method₂A ceramic aerogel. The microstructure and physical properties of the resulting samples were characterized by FT-IR, SEM and XRD, which showed that the introduction of zirconium increased the formation temperature and the maximum crystalline transition temperature of the SiBCN matrix. Zirconium-containing precursor aerogel and SiBCN-ZrO₂The ceramic aerogel has relatively good mesoporous structure, and SiBCN-ZrO has the structure at 1350 DEG C₂The specific surface area, pore volume and average pore diameter of the ceramic aerogel are 98.1204m²g^‑1,0.4832cm³g^‑1And 14.47nm, and the ceramic aerogel prepared after sintering is mainly composed of ZrO₂、β‑SiC、Si₃N₄A crystalline phase and an amorphous phase of SiBCN.

Description

Zirconium-containing polyborosilazane precursor aerogel, silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel, and preparation method and application thereof

Technical Field

The invention relates to the technical field of aerogel materials, in particular to zirconium-containing polyborosilazane precursor aerogel, silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel, and a preparation method and application thereof.

Background

SiBCN is used as a high-melting-point material, has the characteristics of good high-temperature and chemical stability, thermal vibration resistance, low thermal expansion coefficient, high hardness and the like which are superior to binary ceramics such as SiC, BN and the like and ternary ceramics such as SiOC, SiCN and the like, and is a potential high-temperature resistant aerogel material matrix. The zirconium dioxide aerogel has excellent chemical stability, thermal stability, insulativity and light shielding property, and simultaneously has acidic and alkaline surface active centers and good ion exchange performance, so that the zirconium dioxide aerogel can be applied to the application aspects of catalysts, adsorbents and the like. SiBCN-ZrO₂The aerogel can be combined with the good chemical and thermal stability, ion exchange property and the like of zirconium dioxide, and also has the high thermal stability and good mechanical properties of SiBCN, so that the aerogel has infinite wide application in the aspects of heat insulation, adsorption, catalysis and the like. It has been reported that a SiBCN-based composite ceramic can be obtained by doping polycarbosilane with ceramic powder and then pyrolyzing the doped polycarbosilane. However, it is difficult to use a solid-liquid mixing system in this methodSo as to form uniformly distributed solution, and the problem of dispersibility caused by gravity is inevitable when non-soluble solid powder is introduced into the liquid, so that the prepared composite material cannot reach the equality, and further, various performances of the composite material are limited.

Disclosure of Invention

The invention aims to provide zirconium-containing polyborosilazane precursor aerogel, silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel, and a preparation method and application thereof, aiming at the technical defects in the prior art. The composite aerogel material is prepared through a liquid-liquid dispersion system, and the PBSN-TBZ aerogel prepared by the hydrosilylation reaction method based on the liquid-liquid dispersion system ensures ZrO in the finally prepared composite aerogel framework₂Uniform distribution of particles, thereby making SiBCN-ZrO₂Ceramic aerogels exhibit relative compositional homogeneity. More importantly, the SiBCN-ZrO has good chemical stability under high temperature condition₂The ceramic aerogel can be widely applied to various fields.

The technical scheme adopted for realizing the purpose of the invention is as follows:

zirconium-containing polyborosilazane precursor aerogel with density of 0.26-0.31gcm^-3The specific surface area is 516.8809-621.5886m²g^-1The average pore diameter is 10.88-13.1nm, and the pore volume is 1.8119-2.1339cm³g^-1；

The preparation method comprises the following steps:

step 1, respectively adding polyborosilazane PBSN and tetrabutyl zirconate TBZ into a tetrahydrofuran solvent according to the mass ratio of (2-4):1, uniformly dispersing to obtain a homogeneous precursor solution, wherein the volume concentration of the solvent in the precursor solution is 85-95%, then adding divinylbenzene into the homogeneous precursor solution, and uniformly dispersing to form a mixed transparent solution, wherein the mass ratio of the divinylbenzene to the PBSN is 1: 4;

step 2, placing the mixed transparent solution in a sealed container, heating to 120-180 ℃ at the speed of 3-7 ℃/min, keeping the temperature for 4-7h, and naturally cooling to room temperature after the reaction is finished to prepare the zirconium-containing PBSN wet gel;

and 3, performing supercritical drying on the zirconium-containing PBSN wet gel obtained in the step 2 to obtain the zirconium-containing polyborosilazane precursor aerogel.

In the technical scheme, when the volume concentration of the solvent of the homogeneous precursor solution is a certain value, the mass ratio of the PBSN to the TBZ is changed, and the aperture size and the microscopic particle size of the zirconium-containing PBSN precursor aerogel can be regulated and controlled.

In the technical scheme, the mass ratio of the polyborosilazane PBSN to the tetrabutyl zirconate TBZ in the step 1 is 3:1, the volume concentration of the solvent in the precursor solution is 90%, and the density of the precursor aerogel is 0.26gcm^-3Specific surface area of 621.5886m²g^-1Average pore diameter of 10.88nm and pore volume of 1.5022cm³g^-1。

In another aspect of the present invention, the method for preparing the zirconium-containing polyborosilazane precursor aerogel further comprises the following steps:

step 1, respectively adding polyborosilazane PBSN and tetrabutyl zirconate TBZ into a tetrahydrofuran solvent according to the mass ratio of (2-4):1, uniformly dispersing to obtain a homogeneous precursor solution, wherein the volume concentration of the solvent in the precursor solution is 85-95%, then adding divinylbenzene into the homogeneous precursor solution, and uniformly dispersing to form a mixed transparent solution, wherein the mass ratio of the divinylbenzene to the PBSN is 1: (0.5-1.5);

step 2, placing the mixed transparent solution in a sealed container, heating to 120-180 ℃ at the speed of 3-7 ℃/min, keeping the temperature for 4-7h, and naturally cooling to room temperature after the reaction is finished to prepare the zirconium-containing PBSN wet gel;

and 3, performing supercritical drying on the zirconium-containing PBSN wet gel obtained in the step 2 to obtain the zirconium-containing polyborosilazane precursor aerogel.

Another aspect of the invention includes a silicon boron carbon nitride/zirconium dioxide ceramic aerogel (SiBCN-ZrO)₂) The preparation method comprises the following steps:

step 1, drying the precursor aerogel for 20-30h at the temperature of 60-70 ℃ in a vacuum environment;

step 2, in N₂And sintering the dried precursor aerogel in the atmosphere, wherein during sintering, the temperature is respectively raised to the sintering temperature of 1000-minus-one-year-old 1350 ℃ at the temperature rise rate of 3-5 ℃/min, the temperature is kept for 1-2h, then the temperature is lowered to 300-minus-one-year-old 500 ℃ at the temperature drop rate of 4-6 ℃/min, and then the ceramic aerogel is obtained after natural cooling to the room temperature of 20-30 ℃.

In the above technical solution, when the sintering temperature is 1050 ℃ or lower, the ceramic aerogel is in an amorphous state, and when the sintering temperature is 1200 ℃ or higher, the ceramic aerogel contains ZrO₂β -SiC and BN crystals.

In the technical scheme, ZrO in the silicon-boron-carbon-nitrogen/zirconium dioxide ceramic aerogel₂The particles have a diameter of 12-18nm and are uniformly dispersed.

In the technical scheme, the specific surface area of the silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel is 90-110m²g^-1Average pore diameter of 13-16nm and pore volume of 0.4-0.5cm³g^-1。

In another aspect of the present invention, the present invention further includes a method for preparing a silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel, comprising the following steps:

step 1, respectively adding polyborosilazane PBSN and tetrabutyl zirconate TBZ into a tetrahydrofuran solvent according to the mass ratio of (2-4):1, uniformly dispersing to obtain a homogeneous precursor solution, wherein the volume concentration of the solvent in the precursor solution is 85-95%, then adding divinylbenzene into the homogeneous precursor solution, and uniformly dispersing to form a mixed transparent solution, wherein the mass ratio of the divinylbenzene to the PBSN is 1: (0.5-1.5);

step 2, placing the mixed transparent solution in a sealed container, heating to 120-180 ℃ at the speed of 3-7 ℃/min, keeping the temperature for 4-7h, and naturally cooling to room temperature after the reaction is finished to prepare the zirconium-containing PBSN wet gel;

step 3, carrying out supercritical drying on the zirconium-containing PBSN wet gel obtained in the step 2 to obtain zirconium-containing polyborosilazane precursor aerogel;

step 4, drying the precursor aerogel for 20-30 hours at the temperature of 60-70 ℃ in a vacuum environment;

step 5, in N₂And sintering the dried precursor aerogel in the atmosphere, wherein during sintering, the temperature is respectively raised to the sintering temperature of 1000-minus-one-year-old 1350 ℃ at the temperature rise rate of 3-5 ℃/min, the temperature is kept for 1-2h, then the temperature is lowered to 300-minus-one-year-old 500 ℃ at the temperature drop rate of 4-6 ℃/min, and then the ceramic aerogel is obtained after natural cooling to the room temperature of 20-30 ℃.

In another aspect of the invention, the application of the zirconium-containing polyborosilazane precursor aerogel in preparing a silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel is also included.

In another aspect of the invention, the use of zirconium dioxide to increase the SiBCN matrix formation temperature and the peak crystal transition temperature is also included.

Compared with the prior art, the invention has the beneficial effects that:

1. adopts polycarbosilane precursor, tetrabutyl zirconate and divinylbenzene as raw materials and combines the hydrosilylation reaction with CO₂The supercritical drying technology successfully prepares mesoporous zirconium-containing polycarbosilane aerogel with a three-dimensional network structure, wherein the liquid-liquid reaction uniformly disperses element zirconium in the aerogel, and then the high-temperature-resistant SiBCN-ZrO is prepared by a precursor conversion method₂Ceramic aerogels to achieve zirconium dioxide on SiBCN-ZrO₂Uniform dispersion in the ceramic aerogel.

2. The following conclusions were obtained by characterization analysis: the prepared aerogel has a certain degree of increase along with the increase of the S value; the specific surface area, the pore size distribution and the pore volume of the PBSN-TBZ aerogel are respectively 543.0930-650.1599m²g^-12nm-70nm and 1.9414cm³g^-1-2.0208cm³g^-1Fully indicates that the composite aerogel has a relatively good mesoporous structure.

3. The sintering product with the sintering temperature of 600-1200 ℃ still presents a porous structure; n is a radical of₂The adsorption-desorption curve and the pore size distribution curve respectively show IV type isotherm and 2.0-90nm pore size distribution, and are obtained by treatment at 1200 DEG CSiBCN-ZrO₂The ceramic aerogel had a specific surface area (BET) of 98.1204m²g^-1Pore volume (BJH) 0.4832cm³g^-1The average pore diameter was 14.47 nm. These results show that high temperature sintering of zirconium-containing polycarbosilane aerogels results in SiC-ZrO with porous structures₂A ceramic aerogel; when the sintering temperature is increased to 1350 ℃, the cracking product of the zirconium-containing polycarbosilane aerogel is changed from an organic phase to a crystalline state, and finally the prepared SiBCN-ZrO₂The ceramic aerogel is made of ZrO₂β -SiC and BN crystals.

Drawings

FIG. 1 shows the IR spectrum of PBSN-TBZ aerogel (a-PBSN precursor, b-PBSN-TBZ aerogel).

Fig. 2 shows SEM images of PBSN-TBZ aerogels with different S values (where: a, S ═ 2; b, S ═ 3; c, S ═ 4).

FIG. 3 shows the nitrogen adsorption curves of PBSN-TBZ aerogels at different S values.

FIG. 4 shows the pore size distribution of PBSN-TBZ aerogels with different S values.

FIG. 5 shows SEM pictures of S3 samples (a, 0 ℃; b, 750 ℃; c, 900 ℃; d, 1050 ℃; e, 1200 ℃; f, 1350 ℃) after thermal cracking at different sintering temperatures.

FIG. 6 shows TEM images of S3 samples sintered at 1350 ℃ at different magnifications (where a is 100nm, b is 20nm, c is 10nm, and d is 10 nm).

The XRD patterns of the ceramization products of the PBSN-TBZ aerogel at different sintering temperatures are shown in FIG. 7.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Reagents used in the following examples:

PBSN precursor (synthesized by the university of defense science and technology in china); ZBO (tianjin chemical agents limited); cross-linking agent DVB (alatin industries, inc); tetrahydrofuran (Tianjin Standard chemical Co., Ltd.) as solvent.

Examples

Preparation of zirconium-containing polyborosilazane (PBSN-TBZ) aerogel:

PBSN (polyborosilazane) and TBZ (tetrabutyl zirconate) are respectively added into a glass containing Tetrahydrofuran (THF) according to the mass ratio of 2:1, 3:1 and 4:1, and stirred to obtain a homogeneous precursor solution. Then, 0.6g of Divinylbenzene (DVB) was added to the homogeneous precursor solution to form a mixed transparent solution while ensuring a starting solvent volume concentration of 90% for the addition of solutes of different mass ratios. The reaction mixture was stirred until it appeared homogeneous and transparent, and then the mixture was transferred to a teflon-lined reaction vessel and sealed. Finally, the reaction kettle is placed in an electric heating forced air drying box, the temperature of the reaction kettle is raised to 150 ℃ at the speed of 5 ℃/min, and the temperature is maintained for 5 hours again, so that the reaction is completed. Then naturally cooling to room temperature to prepare zirconium-containing PBSN wet gel, and finally combining with CO₂And (3) carrying out supercritical drying to obtain zirconium-containing polyborosilazane precursor aerogel, wherein the zirconium-containing polyborosilazane precursor aerogel is respectively marked as S2 (corresponding to PBSN: TBZ ═ 2:1), S3 (corresponding to PBSN: TBZ ═ 3:1) and S4 (corresponding to PBSN: TBZ ═ 4: 1).

Zirconium-containing silicon boron carbon nitride (SiBCN-ZrO)₂) Preparing ceramic aerogel:

introducing CO₂Placing a zirconium-containing polyborosilazane aerogel block sample prepared by supercritical drying in a vacuum drying oven at 65 ℃ for drying for 24h, taking out the dried block, placing the dried block into a crucible, placing the crucible containing the aerogel block into a high-temperature box type electric atmosphere furnace, and placing the crucible in N₂And (4) performing high-temperature sintering in the atmosphere. Firstly, setting an atmosphere furnace to respectively heat to 900 ℃, 1050 ℃, 1200 ℃ and 1350 ℃ at the heating rate of 4 ℃/min, keeping sintering for 1h at the corresponding temperature, then cooling to 400 ℃ at the cooling rate of 5 ℃/min, and naturally cooling to room temperature to obtain the corresponding silicon-boron-carbon-nitrogen/zirconium dioxide ceramic aerogel, namely a SiBCN-ZrO2 ceramic aerogel block, wherein the ceramic aerogels prepared corresponding to different contents of tetrabutyl zirconate are respectively marked as S2-C, S3-C, S4-C.

Characterization of the product:

characterization by infraredPBSN-TBZ aerogel at 400-4000cm^-1The specific surface area and pore size distribution of the samples were tested by a nitrogen adsorption-desorption unit at 77K, while the phase transition of zirconium-containing PBSN-TBZ aerogels was detected by XRD (where an X-ray diffractometer used Cu K α radiation (λ 0.154059nm), 2 θ angle range 10-90 °).

The zirconium-containing polyborosilazane precursor aerogel is subjected to infrared analysis, as shown in figure 1, and the infrared spectrum (a) of the PBSN precursor before the reaction is carried out is 2100cm^-1Has a Si-H bond stretching vibration absorption peak at 1265cm^-1The position has an Si-C absorption peak. And the infrared ray (b) of the zirconium-containing polyborosilazane aerogel is 2100cm^-1The absorption peak of Si-H vibration is obviously weakened and is 1200cm^-1The absorption peak of C-C saturated bond newly appears nearby, and is 1580cm^-1The vibration absorption peak of unsaturated bond of aromatic hydrocarbon skeleton is newly appeared (considering that the side chain of PBSN precursor used in reaction contains a certain C ═ C unsaturated bond, 1550cm in fig. 1a^-1A weak double bond absorption peak occurs). A hydrosilylation reaction was described to occur between the Si-H bond of the polyborosilazane precursor and the vinyl group (-CH ═ CH2) of divinylbenzene.

SEM photographs of S2, S3, and S4 aerogel samples are shown in FIGS. 2 a-c. As can be seen from the figure, the microstructure of all three aerogels exhibits a porous network structure, which gives PBSN-TBZ aerogel a lower density and a higher porosity. However, at the same scale, the microstructures of the three aerogels differ to some extent. When the S value is increased from 2 to 3, the porosity, the particle size and the pore diameter of the prepared composite aerogel are reduced to some extent. This is because, at lower S values (S ═ 2), the presence of excess tetrabutyl zirconate in the composite aerogel system leads to a modest reduction in the polymerization rate and a corresponding reduction in the spherical particle nucleation rate. When the nucleation rate is reduced, the single particles continue to grow, resulting in a larger particle size and pore size of the gel; meanwhile, when the S value is higher (S ═ 4), the composite aerogel system is obviously less affected by the low molecular weight tetrabutyl zirconate, and the proportion of PBSN in the solute is larger, so that the composite aerogel system is more affected by the agglomeration of particles, which results in that the pore size of the prepared aerogel is smaller, but the particle size is relatively larger. As is evident from fig. 2-c: macropores (d >50nm) exist in the composite aerogel, and the porosity of the gel system is also large; compared with fig. 2-c, fig. 2-b shows a smaller overall porosity and a significantly smaller particle size than fig. 2-c, although more macropores are present locally (which may be due to non-uniform reaction or other errors during the experimental operation). The results show that: when the initial solvent concentration is constant, the pore size and the particle size of the prepared hybrid aerogel can be controlled by changing the mass ratio of the precursor polyborosilazane to the tetrabutyl zirconate.

N of S2, S3, and S4 aerogel samples₂The adsorption-desorption isotherm graph and the pore size distribution graph are respectively shown in fig. 3 and fig. 4, and it is obvious from the graphs that the adsorption-desorption graphs of the three hybrid aerogels all present type IV isotherms, which indicates that the hybrid aerogel has a typical mesoporous structure, and it is obvious that: when the volume concentration of the initial solvent is fixed, the change of the mass ratio of the solute has no direct influence on the pore structure of the hybrid aerogel, but the change has smaller difference under the same microscale. As can be seen from Table 1, the prepared PBSN-TBZ aerogel has a specific surface area ranging from 516.8809 to 621.5886m²g^-1The average pore diameter is 11.6-13.1nm, and the pore volume range is 1.8119-2.1339cm³g^-1This indicates that the composite aerogel has a relatively good mesoporous structure, and the smaller volume tends to correspond to a smaller specific surface area and average pore diameter, and when S ═ 3, the aerogel sample has the best pore structure (lowest density, highest average pore diameter, specific surface area and pore volume) based on the CO used in this experiment₂The supercritical drying technology can avoid the problem that the capillary force caused by the surface tension of the zirconium-containing polyborosilazane composite aerogel in the drying process is large, so that the hybrid aerogel structure is damaged, the local action of the capillary force can be weakened, and the composite aerogel material with a uniform system is obtained. And the conclusion obtained by SEM is basically consistent.

TABLE 1 microstructure parameters of PBSN-TBZ aerogels

FIG. 5 is an SEM picture of PBSN-TBZ aerogel with a mass of PBSN and TBZ of 3:1 after thermal cracking treatment at different temperatures. The influence of the sintering temperature on the hybrid aerogel is explored through SEM analysis of the ceramization product of the hybrid aerogel. As the sintering temperature is increased from room temperature to 1350 ℃, the neck regions among the zirconium-containing polycarbosilane composite aerogel particles with three-dimensional network structures gradually increase until disappear, the porosity of the composite aerogel tends to decrease in the ceramization process, and the ceramization product still has a highly porous structure. Therefore, the PBSN-TBZ ceramic aerogel obtained by the zirconium-containing polycarbosilane composite aerogel in the ceramic-forming process has uniform pore diameter. Therefore, after the zirconium-containing polycarbosilane composite aerogel is sintered at the high temperature of 1350 ℃, the pore structure of the zirconium-containing polycarbosilane composite aerogel is still maintained, and the SiBCN-ZrO is obtained₂A ceramic aerogel. To understand specifically SiBCN-ZrO₂Pore structure of the ceramic aerogel, etc., and the hybrid aerogel is further characterized below.

FIGS. 6a-d are TEM images of different magnifications of a sample after sintering at 1350 ℃. As can be seen from FIG. 6(a, b), ZrO₂Relatively uniform in distribution and SiBCN-ZrO₂The ceramic aerogel matrix has a relatively uniform pore structure, which is basically consistent with the results of SEM and nitrogen adsorption; FIG. 5c, d are HRTEM images of the ceramic aerogel, and ZrO can be clearly seen₂β -SiC and a small amount of BN crystal phase precipitated, and the spacing of the lattice fringes in FIG. 5c was about 0.317nm in terms of lattice parameters in accordance with the (-111) crystal plane of monoclinic zirconia, and ZrO was present₂The particle diameter is about 15nm, while the stripe spacing in fig. 5d is consistent with the (111) crystal plane of β -SiC and the layer spacing of BN, respectively about 0.25nm and 0.34nm, and the excellent high temperature resistance is proved in view of the fact that the crystal phase in the figure is only distributed in a partial area of the matrix, that is, only a part of SiBCN is converted into crystal β -SiC and BN after the prepared zirconium-containing polyborosilazane precursor aerogel is sintered at 1350 ℃.

The XRD patterns of the ceramization products of the PBSN-TBZ aerogel at different sintering temperatures are shown in FIG. 7. As can be seen, the zirconium-containing polyborosilazane aerogel is amorphous when sintered at 1050 deg.C or below; when the sintering temperature is increased to 1200 ℃, diffraction peaks appear; the diffraction peak was stronger as the temperature was increased to 1350 ℃, indicating that the calcined hybrid aerogel appeared crystalline at this temperature. The 2 theta is 51 DEG, and the diffraction peak at 30 DEG corresponds to ZrO₂Medium crystal plane, which indicates ZrO at this temperature₂The diffraction peaks at 60 and 26 theta correspond to the crystal planes in the β -SiC and BN lattices, respectively, indicating that β -SiC is formed at this temperature, therefore, at sintering temperatures of 1200 deg.C to 1350 deg.C, the cracking product of the hybrid aerogel is transformed from amorphous to crystalline, and the sintered product is mainly formed of ZrO₂And β -SiC crystal.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The zirconium-containing polyborosilazane precursor aerogel is characterized by having a density of 0.26-0.31gcm^-3The specific surface area is 516.8809-621.5886m²g^-1The average pore diameter is 10.88-13.1nm, and the pore volume is 1.8119-2.1339cm³g^-1；

The preparation method comprises the following steps:

step 1, respectively adding polyborosilazane PBSN and tetrabutyl zirconate TBZ into a tetrahydrofuran solvent according to the mass ratio of (2-4):1, uniformly dispersing to obtain a homogeneous precursor solution, wherein the volume concentration of the solvent in the precursor solution is 85-95%, then adding divinylbenzene into the homogeneous precursor solution, and uniformly dispersing to form a mixed transparent solution, wherein the mass ratio of the divinylbenzene to the PBSN is 1: 4;

step 2, placing the mixed transparent solution in a sealed container, heating to 120-180 ℃ at the speed of 3-7 ℃/min, keeping for 4-7h, and naturally cooling to room temperature after the reaction is finished to obtain the zirconium-containing PBSN wet gel;

and 3, performing supercritical drying on the zirconium-containing PBSN wet gel obtained in the step 2 to obtain the zirconium-containing polyborosilazane precursor aerogel.

2. The zirconium-containing polyborosilazane precursor aerogel as claimed in claim 1, wherein the pore size and microscopic particle size of said zirconium-containing polyborosilazane precursor aerogel can be controlled by changing the mass ratio of PBSN to TBZ when the solvent volume concentration of said homogeneous precursor solution is a certain value.

3. The zirconium-containing polyborosilazane precursor aerogel as claimed in claim 1, wherein the mass ratio of polyborosilazane PBSN to tetrabutyl zirconate TBZ in step 1 is 3:1, the volume concentration of the solvent in the precursor solution is 90%, and the density of the precursor aerogel is 0.26gcm^-3Specific surface area of 621.5886m²g^-1Average pore diameter of 10.88nm and pore volume of 1.5022cm³g^-1。

4. A preparation method of zirconium-containing polyborosilazane precursor aerogel comprises the following steps:

step 1, respectively adding polyborosilazane PBSN and tetrabutyl zirconate TBZ into a tetrahydrofuran solvent according to the mass ratio of (2-4):1, uniformly dispersing to obtain a homogeneous precursor solution, wherein the volume concentration of the solvent in the precursor solution is 85-95%, then adding divinylbenzene into the homogeneous precursor solution, and uniformly dispersing to form a mixed transparent solution, wherein the mass ratio of the divinylbenzene to the PBSN is 1: (0.5-1.5);

step 2, placing the mixed transparent solution in a sealed container, heating to 120-180 ℃ at the speed of 3-7 ℃/min, keeping for 4-7h, and naturally cooling to room temperature after the reaction is finished to obtain the zirconium-containing PBSN wet gel;

and 3, performing supercritical drying on the zirconium-containing PBSN wet gel obtained in the step 2 to obtain the zirconium-containing polyborosilazane precursor aerogel.

5. The silicon-boron-carbon-nitrogen/zirconium dioxide ceramic aerogel is characterized by being prepared by the following method:

step 1, drying the precursor aerogel of claim 1 for 20-30h at 60-70 ℃ in a vacuum environment;

step 2, in N₂And sintering the dried precursor aerogel in the atmosphere, wherein during sintering, the temperature is respectively raised to the sintering temperature of 1000-minus-one-year-old 1350 ℃ at the temperature rise rate of 3-5 ℃/min, the temperature is kept for 1-2h, then the temperature is lowered to 300-minus-one-year-old 500 ℃ at the temperature drop rate of 4-6 ℃/min, and then the ceramic aerogel is obtained after natural cooling to the room temperature of 20-30 ℃.

6. The silicon-boron-carbon-nitrogen/zirconium dioxide ceramic aerogel according to claim 5, wherein the ceramic aerogel is in an amorphous state when the sintering temperature is 1050 ℃ or lower, and has ZrO therein when the sintering temperature is 1200 ℃ or higher₂β -SiC and BN crystals.

7. The silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel according to claim 5, wherein ZrO in the silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel₂The particles have a diameter of 12-18nm and are uniformly dispersed.

8. The silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel according to claim 5, wherein the silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel has a specific surface area of 90-110m²g^-1Average pore diameter of 13-16nm and pore volume of 0.4-0.5cm³g^-1。

9. The use of the silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel according to claim 5.

10. A preparation method of silicon boron carbon nitrogen/zirconium dioxide ceramic aerogel comprises the following steps:

step 1, respectively adding polyborosilazane PBSN and tetrabutyl zirconate TBZ into a tetrahydrofuran solvent according to the mass ratio of (2-4):1, uniformly dispersing to obtain a homogeneous precursor solution, wherein the volume concentration of the solvent in the precursor solution is 85-95%, then adding divinylbenzene into the homogeneous precursor solution, and uniformly dispersing to form a mixed transparent solution, wherein the mass ratio of the divinylbenzene to the PBSN is 1: (0.5-1.5);

step 2, placing the mixed transparent solution in a sealed container, heating to 120-180 ℃ at the speed of 3-7 ℃/min, keeping for 4-7h, and naturally cooling to room temperature after the reaction is finished to obtain the zirconium-containing PBSN wet gel;

step 3, carrying out supercritical drying on the zirconium-containing PBSN wet gel obtained in the step 2 to obtain zirconium-containing polyborosilazane precursor aerogel;

step 4, drying the precursor aerogel for 20-30 hours at the temperature of 60-70 ℃ in a vacuum environment;

step 5, in N₂And sintering the dried precursor aerogel in the atmosphere, wherein during sintering, the temperature is respectively raised to the sintering temperature of 1000-minus-one-year-old 1350 ℃ at the temperature rise rate of 3-5 ℃/min, the temperature is kept for 1-2h, then the temperature is lowered to 300-minus-one-year-old 500 ℃ at the temperature drop rate of 4-6 ℃/min, and then the ceramic aerogel is obtained after natural cooling to the room temperature of 20-30 ℃.

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