阅读说明：本技术 一种碳化锆-碳化硼复合气凝胶及其制备方法 (Zirconium carbide-boron carbide composite aerogel and preparation method thereof ) 是由 沈晓冬 王伟 崔升 刘思佳 严文倩 于 2019-11-04 设计创作，主要内容包括：本发明公开了一种碳化锆-碳化硼复合气凝胶及其制备方法,将硼源、去离子水和无水乙醇混合加热搅拌均匀,得到溶液A；将间苯二酚、甲醛和无水乙醇混合搅拌均匀,得到溶液B；将锆源、无水乙醇、去离子水混合搅拌均匀,得到溶液C；溶液B和溶液C混合后,加入到溶液A中,随后加入网络形成剂,搅拌均匀,得到复合溶胶溶液；复合溶胶溶液倒入模具,静置后放到烘箱内进行老化处理,随后将老化后的材料用无水乙醇进行溶剂置换,得到复合湿凝胶,随后进行CO<Sub>2</Sub>超临界干燥处理,得到复合气凝胶材料的前驱体,最后在惰性气氛保护下热处理并除炭,得到碳化锆-碳化硼复合气凝胶,具有低密度、高强度及低热导等优异性能。(The invention discloses zirconium carbide-boron carbide composite aerogel and a preparation method thereof, wherein a boron source, deionized water and absolute ethyl alcohol are mixed, heated and uniformly stirred to obtain a solution A; mixing resorcinol, formaldehyde and absolute ethyl alcohol, and stirring uniformly to obtain a solution B; uniformly mixing and stirring a zirconium source, absolute ethyl alcohol and deionized water to obtain a solution C; mixing the solution B and the solution C, adding the mixture into the solution A, then adding a network forming agent, and uniformly stirring to obtain a composite sol solution; pouring the composite sol solution into a mold, standing, placing the mold in an oven for aging, performing solvent replacement on the aged material with absolute ethyl alcohol to obtain composite wet gel, and performing CO (carbon monoxide) treatment 2 Supercritical drying partAnd finally, carrying out heat treatment and carbon removal under the protection of inert atmosphere to obtain the zirconium carbide-boron carbide composite aerogel which has excellent performances such as low density, high strength and low thermal conductivity.)

1. The preparation method of the zirconium carbide-boron carbide composite aerogel is characterized by comprising the following steps of:

(1) mixing a boron source, deionized water and absolute ethyl alcohol, heating and stirring uniformly to obtain a solution A;

(2) mixing resorcinol, formaldehyde and absolute ethyl alcohol, and stirring uniformly to obtain a solution B;

(3) uniformly mixing and stirring a zirconium source, absolute ethyl alcohol and deionized water to obtain a solution C;

(4) mixing the solution B and the solution C, adding the mixture into the solution A, then adding a network forming agent, and uniformly stirring to obtain a composite sol solution;

(5) pouring the composite sol solution obtained in the step (4) into a mold, standing, putting into an oven for aging treatment, and then performing solvent replacement on the aged material by using absolute ethyl alcohol to obtain a composite wet gel;

(6) subjecting the composite wet gel obtained in the step (5) to CO₂Performing supercritical drying treatment to obtain a precursor of the composite aerogel material;

(7) and (3) heating the precursor of the composite aerogel material obtained in the step (6) to 650-850 ℃ at a heating rate of 5-10 ℃/min under the protection of inert atmosphere, keeping the temperature for 5-7 hours, then continuously heating to 1450-1750 ℃ at a heating rate of 2-4 ℃/min, keeping the temperature for 5-10 hours, then reducing the temperature to 300-600 ℃, changing the inert gas into air, continuously keeping the temperature for 2-5 hours, performing decarburization treatment, and cooling to obtain the zirconium carbide-boron carbide composite aerogel.

2. The method for preparing the zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (1), the boron source is trimethyl borate or triethyl borate, and the molar ratio of the boron source to the deionized water to the absolute ethyl alcohol is 1: (60-100): (30-50) mixing; the temperature for heating and stirring is 75-85 ℃.

3. The method for preparing zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (2), the molar ratio of resorcinol, formaldehyde and absolute ethyl alcohol is 1: 2: (10-40) mixing.

4. The method for preparing the zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (3), the zirconium source is zirconium oxychloride octahydrate, and the zirconium source, the absolute ethyl alcohol and the deionized water are mixed according to a molar ratio of 1: (30-50): (40-60) mixing.

5. The method for preparing the zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (4), the network forming agent is propylene oxide, and the molar ratio of resorcinol, formaldehyde, the boron source, the zirconium source and the network forming agent in the obtained composite sol solution is 1: 2: 1: 1: (0.5-2).

6. The preparation method of the zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (5), the standing time is 60-180 min, and the oven temperature is 100-150 ℃; the absolute ethyl alcohol is replaced once every 8-24 hours, and the total replacement time is 6-8 times.

7. The method for preparing zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (6), the CO is introduced into the reaction vessel₂The conditions of the supercritical drying treatment are as follows: the pressure of the kettle body is controlled to be 8-12.5 MPa, the temperature is controlled to be 45-55 ℃, and the drying time is 8-14 hours.

8. The method for preparing the zirconium carbide-boron carbide composite aerogel according to claim 1, wherein in the step (7), the inert atmosphere is argon.

9. The zirconium carbide-boron carbide composite aerogel prepared by the preparation method of any one of claims 1 to 8.

10. Use of the zirconium carbide-boron carbide composite aerogel according to claim 9 as a thermal insulation material.

Technical Field

The invention belongs to a preparation process of a composite material, and particularly relates to a zirconium carbide-boron carbide composite aerogel material and a preparation method thereof.

Background

With the continuous breakthrough of the flight speed technical barrier and the accompanied severe service environment of the aerospace craft, the requirements on the thermal protection material of the high-performance aerospace craft are higher and higher. The aerogel is a nano porous material with a three-dimensional network structure and excellent performances such as low density, high specific surface area, low thermal conductivity and the like. Currently, in the field of thermal insulation, most researches are carried out on silica aerogel, but the temperature resistance is not high, and severe pore collapse and material structure damage can occur when the temperature exceeds 800 ℃. In order to break through the application of aerogel in ultra-high temperature in the aerospace field, a novel high-temperature-resistant aerogel material needs to be developed urgently. Zirconium carbide has excellent physicochemical properties as a high-melting-point material with high hardness and an excellent high-temperature refractory material; boron carbide is one of the three hardest known materials, and has the characteristics of low density, high strength, high-temperature stability and good chemical stability, so that the preparation method of the zirconium-boron carbide composite aerogel is developed by combining carbide with excellent performance and aerogel, the application of the aerogel in the ultrahigh-temperature field can be widened, and the potential advantages of the aerogel in the aerospace field can be expected.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a zirconium carbide-boron carbide composite aerogel material, which has the advantages of simple process, low price and easy obtainment of raw materials and excellent sample performance, aiming at the defects of the prior art.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:

a preparation method of zirconium carbide-boron carbide composite aerogel comprises the following steps:

(1) mixing a boron source, deionized water and absolute ethyl alcohol, heating and stirring uniformly to obtain a solution A;

(2) mixing resorcinol, formaldehyde and absolute ethyl alcohol, and stirring uniformly to obtain a solution B;

(3) uniformly mixing and stirring a zirconium source, absolute ethyl alcohol and deionized water to obtain a solution C;

(4) mixing the solution B and the solution C, adding the mixture into the solution A, then adding a network forming agent, and uniformly stirring to obtain a composite sol solution;

(5) pouring the composite sol solution obtained in the step (4) into a mold, standing, putting into an oven for aging treatment, and then performing solvent replacement on the aged material by using absolute ethyl alcohol to obtain a composite wet gel;

(6) subjecting the composite wet gel obtained in the step (5) to CO₂Performing supercritical drying treatment to obtain a precursor of the composite aerogel material;

(7) and (3) heating the precursor of the composite aerogel material obtained in the step (6) to 650-850 ℃ at a heating rate of 5-10 ℃/min under the protection of inert atmosphere, carrying out carbonization treatment for 5-7 hours, then continuously heating to 1450-1750 ℃ at a heating rate of 2-4 ℃/min, carrying out carbothermic reduction reaction for 5-10 hours, then reducing the temperature to 300-600 ℃, changing the inert gas into air, continuously carrying out decarburization treatment for 2-5 hours, and cooling to obtain the zirconium carbide-boron carbide composite aerogel.

Specifically, in the step (1), the boron source is trimethyl borate or triethyl borate, and the molar ratio of the boron source, deionized water and absolute ethyl alcohol is 1: (60-100): (30-50) mixing; the temperature for heating and stirring is 75-85 ℃.

Preferably, in step (2), resorcinol, formaldehyde and anhydrous ethanol are mixed in a molar ratio of 1: 2: (10-40), and taking the solution B as a carbon source and a part of a skeleton structure of the aerogel precursor.

Specifically, in the step (3), the zirconium source is zirconium oxychloride octahydrate, and the zirconium source, absolute ethyl alcohol and deionized water are mixed according to a molar ratio of 1: (30-50): (40-60) mixing.

Specifically, in the step (4), the network forming agent is propylene oxide to promote the formation of the aerogel network skeleton, and the molar ratio of resorcinol, formaldehyde, boron source, zirconium source and network forming agent in the obtained composite sol solution is 1: 2: 1: 1: (0.5-2).

Preferably, in the step (5), the standing time is 60-180 min, and the temperature of an oven is 100-150 ℃; the absolute ethyl alcohol is replaced once every 8-24 hours, and the total replacement time is 6-8 times.

Preferably, in step (6), the CO₂The conditions of the supercritical drying treatment are as follows: the pressure of the kettle body is controlled to be 8-12.5 MPa, the temperature is controlled to be 45-55 ℃, and the drying time is 8-14 hours.

Preferably, in step (7), the inert atmosphere is argon.

The zirconium carbide-boron carbide composite aerogel prepared by the preparation method is also in the protection scope of the invention.

Further, the invention also provides application of the zirconium carbide-boron carbide composite aerogel as a heat insulation material.

Has the advantages that:

1. the invention has simple process, and compared with other heat-insulating composite materials in the field of aerospace, the zirconium carbide-boron carbide composite aerogel material has low price and is easy to obtain. The method adopts cheap and easily-obtained triethyl borate and zirconium chloride as raw materials, utilizes a sol-gel method combined with a supercritical drying technology, and has simple and easily-repeated process operation.

2. The zirconium carbide-boron carbide composite aerogel prepared by the invention has excellent performance and wide application range. Compared with the traditional oxide aerogel material, the zirconium carbide-boron carbide composite aerogel has excellent performances of low density, high strength, low thermal conductivity and the like, can be applied to the field of aerospace, and can also be used on heat-insulating materials of civil high-temperature kilns, such as high-temperature single/polycrystalline furnaces and the like. And because the composite material contains boron carbide, the composite material has excellent performances of high chemical stability, high neutron absorption cross section, high temperature resistance and the like, and can be widely applied to the fields of nuclear industry and the like.

Drawings

The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

FIG. 1 is a photograph of a physical representation of the zirconium carbide-boron carbide composite aerogel material prepared in example 1.

FIG. 2 is a scanning electron micrograph of the zirconium carbide-boron carbide composite aerogel material prepared in example 2.

Detailed Description

The invention will be better understood from the following examples.