CN111575832A

CN111575832A - POSS/alumina composite ceramic aerogel fiber and preparation method thereof

Info

Publication number: CN111575832A
Application number: CN202010428758.0A
Authority: CN
Inventors: 马小民; 张春苏; 李富萍; 陈卫东; 张迎锋; 吴南春
Original assignee: Guozhuang New Material Technology Jiangsu Co ltd
Current assignee: Guozhuang New Material Technology Jiangsu Co ltd
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2020-08-25

Abstract

The invention discloses a POSS/alumina composite ceramic aerogel fiber and a preparation method thereof. The preparation method of the composite ceramic aerogel comprises the following steps: mixing a POSS monomer with functional groups and an aluminum source in an organic solution, adding a certain amount of catalyst, stirring and reacting for a certain time, preparing gel fibers through sol-gel spinning, performing solvent replacement on the gel fibers, drying by using a supercritical fluid to obtain alumina composite aerogel fibers, and finally calcining to prepare the POSS/alumina composite ceramic aerogel fibers. The alumina composite ceramic aerogel fiber consists of alumina and a small amount of POSS, has the diameter of 5-100 micrometers, the length of more than 500 meters, a porous structure and the specific surface area of 100-600 m²A density of 0.1 to 0.3g/cm³. The method is beneficial to obtaining the high-temperature resistant continuous ceramic aerogel fiber, and has the performances of ultralight weight, heat resistance, super heat insulation and the like.

Description

POSS/alumina composite ceramic aerogel fiber and preparation method thereof

Technical Field

The invention belongs to the field of ceramics, and particularly relates to a porous and ultra-light ceramic fiber, namely a ceramic aerogel fiber and a preparation method thereof.

Background

POSS is cage-type polysilsesquioxane, is a novel organic matter and hybrid compound, and has excellent anti-atomic oxidation performance. POSS molecular size is 1-3 nanometers, and the POSS can be divided into polyfunctional group POSS and monofunctional group POSS according to the number of active functional groups. Structurally, the POSS is a cage-shaped inner shell formed by an Si-O alternating framework, and can inhibit the molecular chain movement of a composite component to endow the hybrid material with excellent thermal stability, mechanical property and flame retardance. On the other hand, the POSS has small size, small size effect, quantum size effect and macroscopic quantum tunneling effect, and external active groups can react with various groups, so that the POSS is favorably and uniformly distributed and stable in the hybrid material. POSS is therefore widely used for the functional modification of polymeric and inorganic materials.

Ceramics refer to a class of inorganic non-metallic materials made from natural or synthetic compounds through processes such as forming, high temperature sintering, etc. Has the advantages of high melting point, high hardness, high wear resistance, oxidation resistance and the like. In addition, ceramic materials have unique mechanical, thermal, electrical, chemical and optical properties. As typical representative materials of structural ceramics, ceramics based on alumina, silicon nitride, and silicon carbide have excellent high temperature resistance, and are widely used in components working at high temperatures, such as rocket nozzle tips, thermocouple tubes, furnace tubes, and the like, heat exchanger materials at high temperatures, and grinding wheels, abrasives, and the like manufactured with high hardness and wear resistance. In order to further realize the regulation and optimization of the structural ceramic performance, researchers make a large number of researches on the relationship between the ceramic structure and the performance, and develop the relationship between the internal microstructure (microcrystal face effect and porous multiphase distribution condition) and the mechanical performance, the relationship between the ceramic material performance (such as light, electricity, heat and magnetism) and the forming, the particle size distribution and the adhesive interface. The POSS structure is introduced into the preparation of the ceramic, so that the synergistic effect is hopeful to be realized, the ceramic functionalization and mechanical enhancement are realized, the thermal stability is improved, and the like.

Aerogel is a general name of nano porous materials, and is mainly obtained by preparing wet gel through sol-gel chemical transformation, and then replacing liquid in the gel with gas through a special drying process, and simultaneously maintaining the structure of the gel and ensuring unchanged or less change. The composite material has special physical properties such as ultralow density, ultralow thermal conductivity, huge specific surface area, huge void ratio and the like, and has wide application value in the fields of aerospace, transportation, petroleum, buildings and the like. The POSS-reinforced alumina ceramic fiber is prepared into aerogel, although a certain mechanical property is lost, the density can be greatly reduced, and the heat insulation performance can be changed suddenly, so that the POSS-reinforced alumina ceramic fiber has a potential great application value in the field of light heat insulation and heat preservation. However, the preparation of ceramic aerogel fibers still faces many key scientific and technical problems to be solved, so that the literature reports on such materials are very little so far.

Disclosure of Invention

Aiming at the defects and material limitations of the prior art, the invention mainly aims to provide a POSS/alumina composite ceramic aerogel fiber and a preparation method thereof.

The gain effect of the invention is as follows: (1) POSS has excellent stability and reactivity, can form stable chemical bonds with alumina to achieve the aim of modification, so that the prepared composite alumina ceramic has good solubility, and the sol-gel spinning preparation of alumina ceramic fibers is facilitated. (2) Because POSS and alumina are chemically bonded, after the ceramic is formed by sintering, a uniform and stable silica shell layer is formed on the periphery of an alumina crystal region, and the thermal stability and the high temperature resistance of the alumina ceramic are improved. (3) The alumina gel fiber is subjected to supercritical drying, so that the porous structure of the gel fiber can be maintained, and a brand new aerogel material is obtained, so that the prepared ceramic fiber has ultralow density and super heat insulation performance.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the invention provides high-temperature-resistant ceramic precursor slurry and a preparation method thereof, wherein the preparation method comprises the following three key steps:

(1) POSS and an aluminum source are mixed in an organic solution, a certain amount of catalyst is added, and the mixture is stirred and reacted for a certain time to prepare sol with a certain viscosity;

(2) preparing alumina gel fiber by adopting a wet sol-gel spinning process, and performing solvent replacement to obtain alcohol gel fiber;

(3) and (3) carrying out supercritical drying and calcining on the gel fiber to prepare the POSS/alumina composite ceramic aerogel fiber.

As one of preferable modes, the POSS includes any one or a combination of two or more of amino POSS, vinyl POSS, phenyl POSS, ethoxy POSS, methoxy POSS, or composite POSS of the above functional groups, and is not limited thereto.

Further, the aluminum source includes any one or a combination of two or more of aluminum powder, aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum silicate, aluminum sulfide, aluminum isopropoxide, and aluminum nitrate nonahydrate, and is not limited thereto.

Further, the solvent includes methanol, ethanol, isopropanol, propanol, butanol, t-butanol, N-hexane, tetrahydrofuran, N-methylpyrrolidone, acetone, dimethyl sulfoxide, N-dimethylformamide, and is not limited thereto.

Further, the mass ratio of the POSS to the aluminum source is 1: 10-1: 100.

Furthermore, the dosage of the solvent is 0.5-1 time of the total mass of the POSS and the aluminum source.

As one of preferable embodiments, the catalyst includes any one or a combination of two or more of sodium hydroxide, potassium hydroxide, urea, ammonia water, pyridine, trimethylammonium chloride, and triethylamine, and is not limited thereto.

Further, the amount of the catalyst is less than 1% of the mass fraction of POSS.

Further, the reaction temperature is room temperature to 80 ℃.

Further, the reaction time is 3-10 hours.

As one of preferable embodiments, the spinning coagulation bath includes any one or a combination of two or more of methanol, ethanol, isopropanol, propanol, butanol, t-butanol, n-hexane, cyclohexane, n-heptane, acetonitrile, toluene, tetrahydrofuran, isopropanol, and water, and is not limited thereto.

Further, the coagulation bath temperature is 30 to 80 ℃.

Further, the gel fibers are solvent-displaced.

Further, the solvent used for the solvent replacement includes methanol, ethanol, and is not limited thereto.

Further, the number of times of replacement is 1-3.

Furthermore, each replacement time is 5-10 hours.

In a preferred embodiment, the supercritical fluid in the supercritical fluid drying is carbon dioxide.

Further, the critical fluid temperature is 40 ℃.

Further, the pressure is 7-10 MPa.

Further, the calcining temperature is 800-900 ℃.

Further, the calcination time is 20-60 minutes.

The invention also obtains the POSS/alumina composite ceramic aerogel fiber which is composed of alumina and a small amount of POSS, has a diameter of 5-50 microns, a length of more than 500 meters, a porous structure and a specific surface area of 100-600 m²A density of 0.1 to 0.3g/cm³。

Drawings

FIG. 1 is a schematic diagram of a process for preparing POSS/alumina composite ceramic fibers obtained in examples 1-6 of the present invention;

FIG. 2a is a scanning electron micrograph of POSS/alumina composite ceramic fibers obtained in example 1 of the present invention;

FIG. 2b is a partially enlarged scanning electron micrograph of a POSS/alumina composite ceramic fiber obtained in example 1 of the present invention;

FIG. 3a is a scanning electron micrograph of POSS/alumina composite ceramic fiber obtained in example 2 of the present invention;

FIG. 3b is a partially enlarged scanning electron micrograph of a POSS/alumina composite ceramic fiber obtained in example 2 of the present invention;

FIG. 4 is a scanning electron micrograph of POSS/alumina composite ceramic fibers obtained in example 3 of the present invention;

FIG. 5 is a scanning electron micrograph of POSS/alumina composite ceramic fibers obtained in example 4 of the present invention;

FIG. 6 is a scanning electron micrograph of POSS/alumina composite ceramic fibers obtained in example 5 of the present invention;

FIG. 7 is a scanning electron micrograph of POSS/alumina composite ceramic fibers obtained in example 6 of the present invention.

Detailed Description

In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide technical solutions of the present invention. Firstly, a POSS/alumina composite ceramic fiber and a preparation method thereof are provided.

Further, the mass ratio of the POSS to the aluminum source is 1: 10-1: 100.

Further, the reaction temperature is room temperature to 80 ℃.

Further, the reaction time is 3-10 hours.

Further, the coagulation bath temperature is 30 to 80 ℃.

Further, the gel fibers are solvent-displaced.

Further, the number of times of replacement is 1-3.

Furthermore, each replacement time is 5-10 hours.

Further, the critical fluid temperature is 40 ℃.

Further, the pressure is 7-10 MPa.

Further, the calcining temperature is 800-900 ℃.

Further, the calcination time is 20-60 minutes.

The technical scheme of the invention is further explained in detail by a plurality of embodiments and the accompanying drawings. However, the examples are chosen only for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.

Example 1

(1) Dispersing 1 kg of amino POSS and 10 kg of aluminum isopropoxide in 5.5 kg of methanol to obtain a raw material dispersion, adding 9 g of sodium hydroxide into the solution, violently stirring at 80 ℃, reacting for 3 hours, and cooling to room temperature to obtain a spinning solution collagen solution;

(2) carrying out sol-gel spinning on the spinning sol in an isopropanol coagulating bath at the temperature of 30 ℃ to obtain alumina ceramic gel fibers, and replacing the gel fibers in ethanol for 1 time, wherein each time lasts for 10 hours to obtain alcohol gel fibers;

(3) drying the obtained alcohol gel fiber in supercritical carbon dioxide at 40 ℃ and 7MPa for 10 hours, and then calcining at 800 ℃ for 60 minutes to prepare the POSS/alumina composite ceramic aerogel fiber, wherein the basic physical parameters of the ceramic aerogel fiber are shown in Table 1, the preparation route is shown in figure 1, and the scanning electron microscope of the fiber is shown in figures 2a and 2 b.

Example 2

(1) 1 kg of vinyl POSS and 100 kg of aluminum isopropoxide are taken and dispersed in 100 kg of propanol to obtain raw material dispersion liquid, 8 g of potassium hydroxide is added into the solution, the mixture is stirred vigorously at 70 ℃, the temperature is reduced to room temperature after the reaction is carried out for 5 hours, and the spinning solution collagen liquid is prepared;

(2) carrying out sol-gel spinning on the spinning sol in an acetonitrile coagulating bath at 40 ℃ to obtain alumina ceramic gel fiber, and replacing the gel fiber in ethanol for 2 times, wherein each time is 6 hours to obtain alcohol gel fiber;

(3) drying the gel alcohol gel fiber in supercritical carbon dioxide at 40 ℃ and 8MPa for 10 hours, and then calcining at 900 ℃ for 20 minutes to prepare the POSS/alumina composite ceramic aerogel fiber, wherein the basic physical parameters of the ceramic aerogel fiber are shown in Table 1, the preparation route is shown in figure 1, and the scanning electron microscope of the fiber is shown in figures 3a and 3 b.

Example 3

(1) 1 kg of ethoxy POSS and 20 kg of aluminum nitrate nonahydrate are taken and dispersed in 18 kg of tetrahydrofuran to obtain raw material dispersion liquid, 7 g of urea is added into the solution, the mixture is stirred vigorously at the temperature of 60 ℃, the temperature is reduced to room temperature after the reaction is carried out for 7 hours, and the spinning collagen solution is prepared;

(2) carrying out sol-gel spinning on the spinning sol in a toluene coagulating bath at 50 ℃ to obtain alumina ceramic gel fiber, and replacing the gel fiber in methanol for 3 times, wherein each time is 5 hours to obtain alcohol gel fiber;

(3) drying the gel fiber in supercritical carbon dioxide at 40 ℃ and 9MPa for 10 hours, and then calcining at 820 ℃ for 50 minutes to prepare the POSS/alumina composite ceramic aerogel fiber, wherein the basic physical parameters of the ceramic aerogel fiber are shown in Table 1, the preparation route is shown in figure 1, and the scanning electron microscope of the fiber is shown in figure 4.

Example 4

(1) Taking 1 kg of methoxy POSS and 30 kg of aluminum powder, dispersing in 31 kg of N-methyl pyrrolidone to obtain a raw material dispersion, adding 6 g of ammonia water into the solution, violently stirring at 50 ℃, reacting for 8 hours, and then cooling to room temperature to obtain a spinning solution collagen solution;

(2) carrying out sol-gel spinning on the spinning sol in a water coagulation bath at 60 ℃ to obtain alumina ceramic gel fiber, and replacing the gel fiber in methanol for 2 times, wherein each time is 7 hours to obtain alcohol gel fiber;

(3) drying the gel fiber in supercritical carbon dioxide at 40 ℃ and 10MPa for 10 hours, and then calcining at 850 ℃ for 30 minutes to prepare the POSS/alumina composite ceramic aerogel fiber, wherein the basic physical parameters of the ceramic aerogel fiber are shown in Table 1, the preparation route is shown in figure 1, and the scanning electron microscope of the fiber is shown in figure 5.

Example 5

(1) Dispersing 1 kg of methoxy POSS and 40 kg of aluminum silicate in 41 kg of acetone to obtain a raw material dispersion, adding 5 g of triethylamine into the solution, violently stirring at 40 ℃, reacting for 9 hours, and then cooling to room temperature to prepare a spinning solution collagen liquid;

(2) carrying out sol-gel spinning on the spinning sol in tetrahydrofuran coagulating bath at 55 ℃ to obtain alumina ceramic gel fiber, and replacing the gel fiber in methanol for 2 times, wherein each time is 8 hours to obtain alcohol gel fiber;

(3) drying the gel fiber in supercritical carbon dioxide at 40 ℃ and 10MPa for 8 hours, and then calcining at 860 ℃ for 25 minutes to prepare the POSS/alumina composite ceramic aerogel fiber, wherein the basic physical parameters of the ceramic aerogel fiber are shown in Table 1, the preparation route is shown in figure 1, and the scanning electron microscope of the fiber is shown in figure 6.

Example 6

(1) 1 kg of phenyl POSS and 50 kg of aluminum silicate are taken and dispersed in 50 kg of N, N-dimethylformamide to obtain raw material dispersion liquid, 8 g of pyridine is added into the solution, the mixture is stirred vigorously at room temperature, and the reaction is stopped after 10 hours of reaction to prepare spinning solution collagen liquid;

(2) carrying out sol-gel spinning on the spinning sol in an ethanol coagulation bath at 45 ℃ to obtain alumina ceramic gel fibers, and replacing the gel fibers in ethanol for 2 times, wherein each time lasts for 9 hours to obtain alcohol gel fibers;

(3) drying the gel fiber in supercritical carbon dioxide at 40 ℃ and 10MPa for 8 hours, and then calcining at 880 ℃ for 45 minutes to prepare the POSS/alumina composite ceramic aerogel fiber, wherein the basic physical parameters of the ceramic aerogel fiber are shown in Table 1, the preparation route is shown in figure 1, and the scanning electron microscope of the fiber is shown in figure 7.

TABLE 1 Structure and Performance parameters of silica aerogel micropowder obtained in examples 1-6

Examples	Diameter (micron)	Length (m)	Specific surface area (m)²/g)	Density (g/cm)³)
					1	50	500	325	0.102
2	30	800	110	0.136
					3	10	1200	436	0.254
4	18	1500	598	0.298
					5	40	1900	230	0.168
6	5	2000	436	0.176

It should be understood that the above describes only some embodiments of the present invention and that various other changes and modifications may be affected therein by one of ordinary skill in the related art without departing from the scope or spirit of the invention.

Claims

1. A preparation method of POSS/alumina ceramic aerogel fiber is characterized by comprising the following steps:

2. The method for producing POSS/alumina ceramic aerogel fibers of claim 1, wherein the POSS of step (1) comprises any one or a combination of two or more of amino POSS, vinyl POSS, phenyl POSS, ethoxy POSS, methoxy POSS, or a composite POSS of the above functional groups.

3. The method of preparing POSS/alumina ceramic aerogel fibers of claim 1, wherein the aluminum source of step (1) comprises any one or a combination of two or more of aluminum powder, aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum silicate, aluminum sulfide, aluminum isopropoxide, and aluminum nitrate nonahydrate.

4. The method of preparing POSS/alumina ceramic aerogel fibers of claim 1, wherein the organic solvent of step (1) comprises any one or a combination of two or more of methanol, ethanol, isopropanol, propanol, butanol, tert-butanol, N-hexane, tetrahydrofuran, N-methylpyrrolidone, acetone, dimethyl sulfoxide, N-dimethylformamide.

5. The preparation method of the POSS/alumina ceramic aerogel fiber according to claim 1, wherein the mass ratio of the POSS to the aluminum source in the step (1) is 1: 10-1: 100; and/or the dosage of the solvent is 0.5-1 time of the total mass of the POSS and the aluminum source.

6. The method for preparing POSS/alumina ceramic aerogel fibers of claim 1, wherein the catalyst of step (1) comprises any one or a combination of two or more of sodium hydroxide, potassium hydroxide, urea, ammonia, pyridine, trimethylammonium chloride, and triethylamine; and/or the dosage of the catalyst is less than 1% of the POSS mass fraction; and/or the reaction time is 3-10 hours; and/or the reaction temperature is from room temperature to 80 ℃.

7. The method for preparing POSS/alumina ceramic aerogel fiber according to claim 1, wherein the spinning process of step (2) is sol-gel spinning, and the spinning coagulation bath is any one or a combination of two or more of methanol, ethanol, isopropanol, propanol, butanol, tert-butanol, n-hexane, cyclohexane, n-heptane, acetonitrile, toluene, tetrahydrofuran, benzyl alcohol and water; and/or the coagulation bath temperature is 30 to 80 ℃.

8. The method for preparing POSS/alumina ceramic aerogel fibers of claim 1, wherein the solvent used in the solvent displacement process of step (2) comprises any one or a combination of ethanol and methanol; and/or the number of times of replacement is 1-3 times; and/or the time of each replacement is 5 to 10 hours.

9. The method for preparing POSS/alumina ceramic aerogel fibers of claim 1, wherein the supercritical fluid in the supercritical fluid drying of step (3) is carbon dioxide, and the temperature is 40 ℃; and/or the pressure is 7-10 MPa; and/or the calcining temperature is 800-900 ℃; and/or the calcination time is 20-60 minutes.

10. The POSS/alumina ceramic aerogel fiber obtained by the preparation method of the POSS/alumina ceramic aerogel fiber according to any one of claims 1 to 9, wherein the alumina composite ceramic aerogel fiber consists of alumina and a small amount of POSS, has a diameter of 5-50 microns, a length of more than 500 meters, a porous structure and a specific surface area of 100-600 m²A density of 0.1 to 0.3g/cm³。