CN109384459B

CN109384459B - Fiber-reinforced silicon dioxide heat-insulating ceramic material and preparation method and application thereof

Info

Publication number: CN109384459B
Application number: CN201811404854.0A
Authority: CN
Inventors: 张冰清; 杨小波; 吴焘; 苗镇江; 王华栋; 孙志强; 崔凤丹; 张剑; 李淑琴; 于长清; 吕毅
Original assignee: Aerospace Research Institute of Materials and Processing Technology
Current assignee: Aerospace Research Institute of Materials and Processing Technology
Priority date: 2018-11-23
Filing date: 2018-11-23
Publication date: 2020-12-29
Anticipated expiration: 2038-11-23
Also published as: CN109384459A

Abstract

The invention relates to a fiber-reinforced silicon dioxide heat-insulating ceramic material and a preparation method and application thereof. The preparation method comprises the following steps: (1) preparing a prefabricated body; (2) multiple sol-gel treatments: dipping the prefabricated body into silica sol, and then gelling to finish primary sol-gelling treatment; repeating sol-gelation treatment for multiple times, and sequentially reducing the density of silica sol used for impregnation to form gradient impregnation; (3) drying the material treated in the step (2) to obtain a green body; (4) and sintering the green body to obtain the fiber reinforced silicon dioxide heat-insulating ceramic material. The preparation method can prepare the heat-insulating ceramic material with high compressive strength and low heat conductivity, and can be applied to an aircraft heat-insulating system.

Description

Fiber-reinforced silicon dioxide heat-insulating ceramic material and preparation method and application thereof

Technical Field

The invention relates to the technical field of heat-insulating ceramic materials, in particular to a fiber-reinforced silicon dioxide heat-insulating ceramic material and a preparation method and application thereof.

Background

The fiber (such as quartz fiber) reinforced silicon dioxide composite material is a multifunctional composite material which is developed in recent years and can simultaneously meet the functions of heat insulation, wave transmission, bearing and the like, has the advantages of good heat insulation performance, high compressive strength, small thermal expansion coefficient, low density and the like, and is widely applied to the field of aerospace. Currently, fiber reinforced silica composites are mainly focused on their application in the field of load bearing or wave transmission, while their application in the field of thermal insulation is less studied. Because the fiber reinforced silica composite material has certain rigidity, compared with aerogel, cotton felt and other heat insulation materials, the fiber reinforced silica composite material can bear certain pressure while insulating heat, and has more suitable application in certain fields.

At present, the methods for preparing the fiber reinforced silica composite material mainly comprise gel impregnation and pulling impregnation methods. The dip-coating method is a method in which a gel process is not performed during a dipping process, and has the advantages of high speed and short period, but the method has poor control over the size and uniformity of pores. The gel impregnation method is a method that sol-gel reaction is initiated by regulating and controlling temperature, the gel and the prefabricated body are gradually integrated through crosslinking, the internal pores are fine and uniform, and the material performance is more stable. Compared with the pulling method, the gel method has better control on the size and uniformity of the hole, so that the gel method is favored by researchers.

However, the fiber reinforced silica composite material prepared at present is a high-density high-strength material, and through continuous densification, higher compressive strength is achieved so as to meet the bearing requirement, but the porosity of the composite material is reduced, the heat insulation effect is deteriorated, and the heat insulation performance of the material is sacrificed to a certain extent. Researches show that the heat insulation effect of the material with lower density in the same type of ceramic materials is generally better, and the compressive strength is reduced to a certain extent. In addition, the weight of the over-compact material is larger under the same volume, and the material is not suitable for the requirement of the aerospace field for reducing the weight of the aircraft.

Therefore, the heat insulation effect of the material is improved and the heat conductivity coefficient of the material is reduced while a certain compressive strength is kept, and the method has important significance for the development of the fiber reinforced silicon dioxide composite material.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

One of the purposes of the invention is to provide a preparation method of a fiber-reinforced silicon dioxide heat-insulating ceramic material, which adopts a gradient impregnation mode to complete densification in the preparation process, and can prepare the heat-insulating ceramic material with a compact surface structure, sufficient crosslinking between gel and a prefabricated body, good interface bonding property, higher porosity of ceramic, more uniform pores and better heat-insulating effect.

(II) technical scheme

In order to solve the technical problems, the invention provides the following technical scheme:

1. a method of preparing a fiber-reinforced silica thermal insulating ceramic material, the method comprising:

(1) preparing a prefabricated body;

(2) multiple sol-gel treatments: dipping the prefabricated body into silica sol, and then gelling to finish primary sol-gelling treatment; repeating sol-gelation treatment for multiple times, and sequentially reducing the density of silica sol used for impregnation to form gradient impregnation;

(3) drying the material treated in the step (2) to obtain a green body;

(4) and sintering the green body to obtain the fiber reinforced silicon dioxide heat-insulating ceramic material.

2. According to the preparation method of the technical scheme 1, in the step (2), the total times of sol-gelation treatment are 2-4 times, and the density of the silica sol used in the previous impregnation is 2-10% higher than that of the silica sol used in the next impregnation;

preferably, the density of the silica sol used in the step (2) is 1.1-1.4 g/cm³Example (A) ofInside the enclosure.

3. According to the preparation method of the technical scheme 2, the silica sol with lower density is subjected to ultrafiltration or reduced pressure distillation to obtain the silica sol with the density meeting the requirement of the step (2).

4. According to the production method described in claim 2, when the sol-gel treatment is carried out, the density of the silica sol is less than 1.2g/cm³Adding an alkaline gel aid in the gelling process; preferably, the alkaline gel assistant is hexamethylenetetramine or carbamide; more preferably, the concentration of the alkaline gelling aid is 1-10 wt.%.

5. According to the preparation method of any one of claims 1 to 4, in the step (1), the preform has a fiber volume content of 20-40%;

preferably, the fiber is processed into a preform by weaving or needling, and then is pretreated with an organic solvent to obtain the preform.

6. According to the preparation method of any one of claims 1 to 4, sol-gel reaction is initiated by regulating and controlling temperature to complete gelation of sol;

preferably, the temperature is regulated to 60-100 ℃ to initiate sol-gel reaction;

more preferably, the gelation temperature of the silica sol having a high density is lower than the gelation temperature of the silica sol having a low density.

7. According to the preparation method of the technical scheme 1, drying is carried out under the conditions that the humidity is 60-90% and the temperature is 20-50 ℃;

preferably, after drying, the green body is dried at 100-200 ℃ before sintering.

8. According to the preparation method of the technical scheme 1, the sintering is carried out at 500-800 ℃, and the sintering time is 1-3 hours;

preferably, the sintering is performed as follows:

sintering for 0.5-1 hour at the first temperature and then sintering for 1-2 hours at the second temperature; wherein the first temperature is lower than the second temperature, and the air blowing operation is performed into the sintering device during the sintering process.

9. A fiber reinforced silicon dioxide heat insulation ceramic material is prepared by the preparation method of any one of technical schemes 1 to 8.

10. The fiber reinforced silica thermal insulation ceramic material of claim 9 is applied to an aircraft thermal insulation system.

(III) advantageous effects

The technical scheme of the invention has the following advantages:

(1) the preparation method provided by the invention can prepare the heat-insulating ceramic material with a compact surface structure, more sufficient crosslinking between gel and a prefabricated body, good interface binding property, higher porosity of ceramic, more uniform pores and better heat-insulating effect.

(2) The invention greatly shortens the crosslinking reaction time of the matrix and the fiber by utilizing various gel additives, discharges the reaction products of the additives by utilizing an air-blast air sintering system, and does not need to add other components, thereby obtaining the uniform and stable heat-insulating material.

(3) The invention prepares the heat insulation ceramic with the compressive strength of 40-80 MPa and the thermal conductivity of 0.1-0.6W/(m.k) at normal temperature. The ceramic still has good heat insulation performance at 300 ℃, and the thermal conductivity is lower than 0.3W/(m.k).

Drawings

FIG. 1 is a schematic flow chart of a method for preparing a fiber-reinforced silica thermal insulation ceramic material provided by the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a preparation method of a fiber-reinforced silica heat-insulating ceramic material, which comprises the following steps of:

(1) preparation of preforms

The preform (i.e., fiber preform) may be made by processing fibers (e.g., fiber yarn) by weaving or needling. In order to ensure the impregnation effect, the prefabricated body prepared by processing can be pretreated to remove the impregnating agent, so that the prefabricated body for impregnation with good surface wettability can be obtained. The pretreatment can be carried out by using an organic solvent, and the organic solvent can be an existing product, such as acetone, ethanol, trichloromethane and the like, which are not listed in the invention.

Preforms having a fiber volume content of 20 to 40%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% are preferably used in the present invention. For the preform, the higher the fiber content is, the higher the compressive strength of the final material is, but the density and the thermal conductivity of the material are greatly sacrificed, so that the fiber content in the preform is controlled to be 20-40%, and the compressive strength, the thermal conductivity and the density are taken into consideration.

(2) Multiple sol-gel treatment

Dipping the prefabricated body into silica sol, and then gelling to finish primary sol-gelling treatment; the sol-gel treatment was repeated several times and the silica sol used for impregnation was successively decreased in density to form a gradient impregnation.

In the step, the dipping method can adopt a vacuum/pressure dipping method, multiple times of dipping are carried out according to a gradient dipping method, and the density of silica sol used for dipping is reduced in sequence to achieve the aim of densification.

The inventor also optimizes the steps as follows, so that the crosslinking between the gel and the prefabricated body is sufficient, the interface bonding performance is good, the porosity of the ceramic can be higher, the pores are more uniform, and the heat insulation effect is better: the total number of sol-gel treatments is 2 to 4, and the silica sol density used in the previous impregnation is 2 to 10% (for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%) higher than the silica sol density used in the subsequent impregnation.

The effect is better, and the density of the used silica sol is 1.1-1.4 g/cm³In the range of (including, both endpoints), for example, 1.1g/cm³、1.15g/cm³、1.2g/cm³、1.25g/cm³、1.3g/cm³、1.35g/cm³、1.4g/cm³. The used silica sol has low density, and the silica sol with the density is combined with the sol-gelation treatment method, so that the porosity of a blank can be controlled to be high, the pores are controlled to be fine and uniform, and the aims of reducing weight and improving the heat insulation effect can be fulfilled.

The silica sol can adopt a commercially available product, and in order to carry out gradient impregnation, the silica sol with lower density can be concentrated by ultrafiltration or reduced pressure distillation to obtain the silica sol with the required density. For densities below 1.2g/cm³The silica sol is not suitable for popularization due to overlong normal gel time (not less than 120h), and can accelerate the gel by adding the alkaline auxiliary agent; the alkaline assistant of the gel assistant may be hexamethylenetetramine, carbamide, etc. and has a concentration of 1-10 wt.%, for example, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%. The gel time can be shortened to 12-36 h according to different adding amount.

There are various methods for promoting the conversion of sol to gel, and the present invention preferably employs a method of controlling the temperature to achieve this conversion. According to the density of the silica sol and the gradient dipping times, the temperature is preferably regulated to 60-100 ℃ to initiate the sol-gel reaction. Since the higher the silica sol density, the lower the temperature or the shorter the time required for providing the silica sol, the gelation treatment temperature of the silica sol having a high density is lower than the gelation treatment temperature of the silica sol having a low density when the sol-gelation treatment is performed a plurality of times.

(3) Drying

And (3) drying the material treated in the step (2) to obtain a green body.

The gelled green body is preferably dried by slow treatment at low temperature and high humidity for a long time to protect the green body. And further drying at 100-200 ℃ after finishing.

Preferably, the humidity can be controlled at 60% to 90% (e.g., 60%, 65%, 70%, 75%, 80%, 85%, 90%) during drying, and the temperature can be controlled at 20 to 50 ℃ (e.g., 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃).

(4) Sintering

And sintering the green body to obtain the fiber reinforced silicon dioxide heat-insulating ceramic material.

Preferably, the sintering is carried out at 500-800 ℃ for 1-3 hours. Preferably, the sintering is performed as follows: sintering for 0.5-1 hour at the first temperature and then sintering for 1-2 hours at the second temperature; wherein the first temperature is lower than the second temperature, and the air blowing operation is performed into the sintering device during the sintering process.

For the green body added with the gel additive, air blasting operation is carried out in a sintering device in the sintering process, and the sintering device is ensured to have good ventilation, so that the residue of an additive reaction product in the green body is reduced, and the addition of the additive has a certain hole expanding effect on the green body, but the addition amount is controlled to be 1-10 wt%, so that holes are still in a mesoporous range, and the material performance is not obviously damaged.

The invention also provides a fiber reinforced silicon dioxide heat insulation ceramic material which is prepared by the preparation method. The material has the advantages of high compressive strength at normal temperature, low thermal conductivity and low density, wherein the compressive strength at normal temperature reaches 40-80 MPa, the coefficient of thermal conductivity at normal temperature reaches 0.1-0.6W/(m.k), the material still has good heat insulation performance at 300 ℃, the thermal conductivity is lower than 0.3W/(m.k), the heat insulation effect is good, and the material can be applied to an aircraft heat insulation system.

The following are examples of the present invention.

Preparing materials:

silica sol crude gel: the density was 1.16g/cm³；

The silica sol crude gel is subjected to reduced pressure distillation (although ultrafiltration may be used in other embodiments) to obtain the densityIs 1.28g/cm³And 1.36g/cm³The silica sol of (a) is ready for use.

Example 1

The quartz fiber is processed into a preform with a fiber volume content of 20% by a mechanical needling method, and the impregnating agent is removed by an organic solvent (acetone is used in the embodiment), so that the preform for impregnation with good surface wettability is obtained and is used in the subsequent impregnation step.

The density is 1.28g/cm³Impregnating the prefabricated body with the silica sol by a vacuum/pressure impregnation method, filling the prefabricated body with a filler to densify, then carrying out sol-gel reaction to gradually combine the gel and the prefabricated body into a whole by crosslinking, controlling the temperature of the first sol-gel reaction to be 70 ℃ and the time to be 36 hours, and not adding a gel auxiliary agent; the density is 1.16g/cm³The silica sol is used for dipping the prefabricated body by a vacuum/pressure dipping method, then sol-gel reaction is carried out, the temperature of the second sol-gel reaction is controlled to be 90 ℃, the time is 36 hours, and hexamethylenetetramine with the concentration of 1 wt.% is added as a gel auxiliary agent.

Drying the material obtained after sol-gelation treatment under the conditions of humidity of 90% and temperature of 20 ℃ to obtain a green body.

Finally, sintering the green body at 600 ℃ for 1h, then sintering the green body at 800 ℃ for 1h, and blowing air into a sintering device in the sintering process to obtain the material with the compressive strength of 56MPa, the thermal conductivity of 0.12 w/(m.k), and the density of 1.12g/cm³The heat insulating ceramic material of (1).

Example 2

The density is 1.28g/cm³Impregnating the prefabricated body with silica sol by vacuum/pressure impregnation method, filling filler into the prefabricated body to densify, then making sol-gel reaction to make the gel and prefabricated body produce cross-linking and gradually combine together, controlling the first sol-gel reaction temperature at 70 deg.CThe time is 36h, and no gel additive is added; the density is 1.16g/cm³The silica sol is used for dipping the prefabricated body by a vacuum/pressure dipping method, then sol-gel reaction is carried out, the temperature of the second sol-gel reaction is controlled to be 90 ℃, the time is 36 hours, and 2 wt.% of carbamide is used as a gel auxiliary agent.

Finally, sintering the green body at 600 ℃ for 1h, then sintering the green body at 800 ℃ for 1h, and blowing air into a sintering device in the sintering process to obtain the product with the compressive strength of 50MPa, the thermal conductivity of 0.14 w/(m.k), and the density of 1.14g/cm³The heat insulating ceramic material of (1).

Example 3

The density is 1.28g/cm³Impregnating the prefabricated body with the silica sol by a vacuum/pressure impregnation method, filling the prefabricated body with a filler to densify, then carrying out sol-gel reaction to gradually combine the gel and the prefabricated body into a whole by crosslinking, controlling the temperature of the first sol-gel reaction to be 70 ℃ and the time to be 36 hours, and not adding a gel auxiliary agent; the density is 1.16g/cm³The silica sol is used for dipping the prefabricated body by a vacuum/pressure dipping method, then sol-gel reaction is carried out, the temperature of the second sol-gel reaction is controlled to be 100 ℃, the time is 120 hours, and no gel auxiliary agent is added.

Finally, sintering the green body at 600 ℃ for 1h, then sintering the green body at 800 ℃ for 1h, and blowing air into a sintering device in the sintering process to obtain the product with the compressive strength of 60MPa, the thermal conductivity of 0.12 w/(m.k), and the density of 1.10g/cm³The heat insulating ceramic material of (1).

Example 4

Quartz fibers were processed by mechanical needling into preforms with a fiber volume content of 30%, and the impregnating agent was removed by an organic solvent (acetone in this example) to obtain preforms for impregnation with good surface wettability for the subsequent impregnation step.

Finally, sintering the green body at 600 ℃ for 1h, then sintering the green body at 800 ℃ for 1h, and blowing air into a sintering device in the sintering process to obtain the product with the compressive strength of 59MPa, the thermal conductivity of 0.18 w/(m.k), and the density of 1.32g/cm³The heat insulating ceramic material of (1).

Example 5

The density is 1.36g/cm³Impregnating the prefabricated body with the silica sol by a vacuum/pressure impregnation method, filling the prefabricated body with a filler to densify, then carrying out sol-gel reaction to gradually combine the gel and the prefabricated body into a whole by crosslinking, controlling the temperature of the first sol-gel reaction to be 60 ℃ and the time to be 36 hours, and not adding a gel auxiliary agent; the density is 1.28g/cm³The silica sol is impregnated by a vacuum/pressure impregnation methodPerforming sol-gel reaction on the prefabricated body, controlling the temperature of the second sol-gel reaction to be 70 ℃ and the time to be 36h, and not adding a gel auxiliary agent; the density is 1.16g/cm³The silica sol is used for dipping the prefabricated body by a vacuum/pressure dipping method, then sol-gel reaction is carried out, the temperature of the third sol-gel reaction is controlled to be 90 ℃, the time is 36 hours, and hexamethylenetetramine with the concentration of 1 wt.% is added as a gel auxiliary agent.

Finally, sintering the green body at 600 ℃ for 1h, then sintering the green body at 800 ℃ for 1h, and blowing air into a sintering device in the sintering process to obtain the material with the compressive strength of 68MPa, the thermal conductivity of 0.36 w/(m.k), and the density of 1.47g/cm³The heat insulating ceramic material of (1).

Example 6

The quartz fiber is processed into a preform with a fiber volume content of 40% by a mechanical needling method, and the impregnating agent is removed by an organic solvent (acetone is used in the embodiment), so that the preform for impregnation with good surface wettability is obtained and is used in the subsequent impregnation step.

The density is 1.36g/cm³Impregnating the prefabricated body with the silica sol by a vacuum/pressure impregnation method, filling the prefabricated body with a filler to densify, then carrying out sol-gel reaction to gradually combine the gel and the prefabricated body into a whole by crosslinking, controlling the temperature of the first sol-gel reaction to be 60 ℃ and the time to be 36 hours, and not adding a gel auxiliary agent; the density is 1.28g/cm³Dipping the prefabricated body by the silica sol through a vacuum/pressure dipping method, then carrying out sol-gel reaction, controlling the temperature of the second sol-gel reaction to be 70 ℃ and the time to be 36h, and not adding a gel auxiliary agent; the density is 1.16g/cm³The silica sol is used for dipping the prefabricated body by a vacuum/pressure dipping method, then sol-gel reaction is carried out, the temperature of the third sol-gel reaction is controlled to be 90 ℃, the time is 36 hours, and hexamethylenetetramine with the concentration of 1 wt.% is added as a gel auxiliary agent.

Finally, sintering the green body at 600 ℃ for 1h, then sintering the green body at 800 ℃ for 1h, and blowing air into a sintering device in the sintering process to obtain the material with the compressive strength of 77MPa, the thermal conductivity of 0.45 w/(m.k), and the density of 1.56g/cm³The heat insulating ceramic material of (1).

Example 7

Finally, the green body is sintered for 2h at 600 ℃ to obtain the material with the compressive strength of 56MPa, the thermal conductivity of 0.14 w/(m.k) and the density of 1.14g/cm³The heat insulating ceramic material of (1).

Example 8

The density is 1.28g/cm³Impregnating the preform with the silica sol by a vacuum/pressure impregnation methodFilling filler to densify, performing sol-gel reaction to gradually combine gel and the prefabricated body into a whole by crosslinking, controlling the temperature of the first sol-gel reaction to be 70 ℃ and the time to be 36h, and not adding a gel auxiliary agent; the density is 1.16g/cm³The silica sol is used for dipping the prefabricated body by a vacuum/pressure dipping method, then sol-gel reaction is carried out, the temperature of the second sol-gel reaction is controlled to be 90 ℃, the time is 36 hours, and hexamethylenetetramine with the concentration of 1 wt.% is added as a gel auxiliary agent.

Finally, the green body is sintered for 2h at 800 ℃ to obtain the material with the compressive strength of 50MPa, the thermal conductivity of 0.12 w/(m.k) and the density of 1.12g/cm³The heat insulating ceramic material of (1).

The compressive strength (at room temperature), thermal conductivity (at room temperature) and density of the insulating ceramic material obtained in each of the above examples were recorded, and the results are shown in Table 1.

The raw materials and molding processes for preparing ceramics used in examples 1 to 3 were completely the same, and the number of impregnations, preform content and silica sol density were the same, except that different gelling aids were used or no aids were used. The gel aid and silica sol used in examples 4 to 6 were of the same density, except that different numbers of impregnations and preform contents were used. The number of impregnations, preform contents, gel aids and silica sol densities used in examples 7 to 8 were the same, except that different sintering schedules were used. As can be seen from the results in Table 1, the thermal insulating ceramic material prepared in each of the above examples has a relatively low thermal conductivity and a relatively high compressive strength.

As can be seen by observing the data results in Table 1, the use of hexamethylenetetramine as the gelling aid can effectively increase the gelling rate, and the thermal conductivity of the prepared ceramic material is kept at a low level. By increasing the number of times of impregnation or increasing the fiber volume content of the preform, the compressive strength of the material can be effectively increased, but the thermal conductivity thereof is also significantly increased. Different sintering temperatures have a slight influence on the strength and thermal conductivity of the material, and it is possible that the thermal conductivity is slightly increased due to incomplete volatilization of the auxiliary reaction product at a lower temperature, and the strength is slightly reduced due to certain damage of the higher temperature to the fiber strength of the preform. The ceramic material prepared by the invention has lower thermal conductivity, higher compressive strength, lower density and obvious porosity advantage.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a fiber reinforced silicon dioxide heat insulation ceramic material is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) preparing a prefabricated body;

(3) drying the material treated in the step (2) to obtain a green body;

2. The method of claim 1, wherein: in the step (2), the total number of sol-gel treatments is 2 to 4, and the density of the silica sol used in the previous impregnation is 2 to 10% higher than that of the silica sol used in the subsequent impregnation.

3. The method of claim 2, wherein:

the density of the silica sol used in the step (2) is 1.1-1.4 g/cm³Within the range of (1).

4. The method of claim 2, wherein: and (3) carrying out ultrafiltration or reduced pressure distillation on the silica sol with lower density to obtain the silica sol with the density meeting the requirement of the step (2).

5. The method of claim 2, wherein: when the sol-gel treatment is carried out, the density of the silica sol is less than 1.2g/cm³Then adding an alkaline gelling aid during gelling.

6. The method of claim 5, wherein: the alkaline gel auxiliary agent is hexamethylenetetramine or carbamide.

7. The method of claim 6, wherein: the concentration of the alkaline gel auxiliary agent is 1-10 wt.%.

8. The production method according to any one of claims 1 to 7, characterized in that: in the step (1), the preform is a preform with a fiber volume content of 20-40%.

9. The method of claim 8, wherein: processing the fiber into a preform blank in a weaving or needling mode, and then carrying out pretreatment by using an organic solvent to obtain the preform.

10. The production method according to any one of claims 1 to 7, characterized in that: the sol-gel reaction is initiated by regulating and controlling the temperature to complete the gelation of the sol.

11. The method of manufacturing according to claim 10, wherein: regulating the temperature to 60-100 ℃ to initiate sol-gel reaction.

12. The method of claim 11, wherein: the gelation temperature of the high-density silica sol is lower than that of the low-density silica sol.

13. The method of claim 1, wherein: drying the mixture under the conditions that the humidity is 60-90% and the temperature is 20-50 ℃.

14. The method of manufacturing according to claim 13, wherein:

and after drying, drying the green body at 100-200 ℃ before sintering.

15. The method of claim 1, wherein: and sintering at 500-800 ℃ for 1-3 hours.

16. The method of claim 15, wherein: the sintering is carried out according to the following method:

17. A fiber reinforced silica thermal insulation ceramic material is characterized in that: prepared by the preparation method of any one of claims 1 to 16.

18. Use of the fiber reinforced silica insulating ceramic material of claim 17 in an aircraft insulation system.