阅读说明：本技术 一种坠毁幸存存储器用隔热材料的制备方法 (Preparation method of heat insulation material for crash survival memory ) 是由 杨景锋 王齐华 王廷梅 于 2019-11-21 设计创作，主要内容包括：本发明公开了一种坠毁幸存存储器用隔热材料的制备方法,先将多孔纤维与常温粘结剂、高温粘结剂加入水中制成浆料；再将浆料压滤成型后高温焙烧,冷却得多孔纤维骨架；在配制的铝硅复合溶胶中加入红外遮蔽剂及凝胶助剂分散均匀后和多孔纤维骨架复合均匀静置至凝胶形成；然后将纤维复合湿凝胶老化后进行超临界干燥,得到坠毁幸存存储器用隔热材料。本发明制备的隔热材料不仅具有良好的高温隔热性能,同时具有良好的强度和减振性能,特别适合用于坠毁幸存存储器的隔热防护,对于打破目前国内飞行器的坠毁幸存存储器长期依赖进口产品的局面以及坠毁幸存存储器用隔热材料的进口替代具有重要意义。(The invention discloses a preparation method of a heat insulation material for a crash survival memory, which comprises the steps of adding porous fiber, a normal-temperature binder and a high-temperature binder into water to prepare slurry; then the slurry is pressed and molded, and then is roasted at high temperature and cooled to obtain a porous fiber framework; adding an infrared shielding agent and a gel auxiliary agent into the prepared aluminum-silicon composite sol, uniformly dispersing, then uniformly compounding with the porous fiber framework, and standing until gel is formed; and then aging the fiber composite wet gel, and performing supercritical drying to obtain the heat insulation material for the crash survival memory. The heat insulation material prepared by the invention has good high-temperature heat insulation performance, good strength and vibration reduction performance, is particularly suitable for heat insulation protection of crash survivor memories, and has important significance for breaking the situation that the crash survivor memories of the domestic aircrafts depend on imported products for a long time and for import replacement of the heat insulation material for the crash survivor memories.)

1. A preparation method of a heat insulation material for a crash survival memory comprises the following steps:

(1) preparing a porous fiber framework: adding the cleaned porous fiber, a normal-temperature binder and a high-temperature binder into water with the volume of 10-100 times that of the porous fiber, and uniformly stirring and dispersing to form slurry; putting the slurry into a shaping mold, pressing, filtering to remove water, performing, roasting at 1000-1200 ℃ for 0.5-2 hours, and cooling to obtain a porous fiber framework;

(2) preparing composite sol: stirring and mixing an aluminum precursor, deionized water and ethanol at 50-70 ℃, cooling to room temperature after the solution is clarified to obtain aluminum sol, adding acid and a silicon precursor into the aluminum sol, stirring for 50-60 minutes, adding aniline and acetone, and stirring for 5-15 minutes to obtain silicon-aluminum composite sol;

(3) preparing a heat insulation material: putting the porous fiber framework obtained in the step (1) into a shell of a crash survival memory; adding an infrared shielding agent into the silicon-aluminum composite sol obtained in the step (2), adding the mixture into a crash survival memory shell, ensuring that the silicon-aluminum composite sol submerges a porous fiber framework, then ultrasonically dispersing for 15-25 min, and standing for 2-5 hours to form silicon-aluminum composite wet gel; finally, placing the silicon-aluminum composite wet gel in absolute ethyl alcohol for aging for 1-3 days; and then, ethanol is used as a medium, and supercritical drying is carried out at the temperature of 260-300 ℃ and under the pressure of 6-15 MPa, so as to obtain the heat insulating material for the crash survival memory.

2. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (1), the porous fiber is mullite fiber, alumina silicate fiber and alumina fiber; the diameter of the porous fiber is not more than 30um, and the length is not more than 2 mm.

3. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (1), the normal-temperature binder is at least one of organic binders such as polyacrylamide, epoxy resin, starch and the like.

4. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (1), the high-temperature binder is boron nitride or boron carbide, and the particle size of the high-temperature binder is not more than 10 um.

5. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (1), the mass ratio of the porous fiber to the normal-temperature binder and the high-temperature binder is 1 (0.05-0.3) to (0.05-0.3).

6. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the aluminum sol in the step (2), the aluminum precursor is any one of aluminum sec-butoxide, aluminum isopropoxide, aluminum nitrate and aluminum chloride; the molar ratio of the aluminum precursor to the deionized water to the ethanol is 1 (0.4-1) to 4-10.

7. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (2), the acid is any one of hydrochloric acid, nitric acid or acetic acid, and the using amount of the acid is 0.003-0.03 times of the molar weight of the aluminum precursor.

8. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (2), the silicon precursor is any one of tetraethoxysilane, trimethylmethoxysilane and trimethylethoxysilane; the molar ratio of the aluminum precursor to the silicon precursor is 1 (0.125-0.33).

9. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (3), the molar ratio of the aluminum precursor to the aniline is 1 (0.4-5); the molar ratio of the aluminum precursor to the acetone is 1 (0.4-5).

10. The method of preparing a crash survivor memory thermal insulation material according to claim 1, wherein the method comprises the steps of: in the step (3), the infrared shielding agent is any one of silicon carbide, titanium oxide and potassium hexatitanate; the dosage of the infrared shielding agent is not more than 20% of the fiber mass.

Technical Field

The invention relates to a heat insulation material for a crash survival memory and a preparation method thereof, belonging to the field of heat insulation materials.

Background

The crash survivor memory is a data storage and storage component on a flight parameter recorder and a voice recorder, is commonly called as a black box, and has the function of completely storing data recorded by the flight parameter recorder or the voice recorder and is used for analyzing accident causes after flight accidents. Crash survivor memory is generally composed of a recording medium, a protective housing, and a heat insulating material. Insulation is typically filled between the protective case and the recording medium to prevent stored data from being damaged in the event of an accident. The filled thermal insulation material must be able to meet the thermal insulation requirements specified by the TSO-124a standard for accident survival, namely, the thermal insulation material can be subjected to high-temperature fire at 1100 ℃ for 60 minutes and heating at 260 ℃ for 10 hours, and the internal temperature is less than 125 ℃. The heat insulation performance of the heat insulation material used for the current crash survivor memory can only reach the TSO-124 standard, namely the duration of the heat insulation material in high-temperature flame at 1100 ℃ is 40min, but not 1h specified by the TSO-124a standard. The used heat insulating material is generally composed of reinforcing fibers, nano powder, high-temperature radiation resistant filler, resin binder and the like, and then is formed by encapsulating through high-temperature resistant sealant. Silica aerogel is mainly used as the nano powder which has the greatest contribution to low thermal conductivity. However, the silica aerogel itself undergoes phase transition at 800 ℃ or higher, causing the nano-pores inside to collapse, the structure to be densified, and the thermal conductivity to be increased sharply, for example, the thermal conductivity of the silica aerogel at normal temperature is 0.015 to 0.035W/mK, while the thermal conductivity at 1000 ℃ is increased to 0.08 to 0.12W/mK, so that the contribution to the reduction of the thermal conductivity is greatly weakened, and the heat-insulating material can be used only at 1100 ℃ for a short time, and cannot meet the 1h standard requirement specified by TSO-124 a. Meanwhile, the high temperature of 1100 ℃ even causes the burning of organic components in the heat insulating material, such as resin binder, high melting point wax and the like, so that the heat insulating protection is ineffective. Although much research is currently conducted on thermal protection materials for aerospace vehicles, the above problems are still not completely solved.

Disclosure of Invention

The invention provides a heat insulating material with excellent high-temperature heat insulating performance for a crash survival memory and a preparation method thereof, aiming at the technical defects of poor high-temperature heat insulating performance and high-temperature heat protection failure of the heat insulating material in the prior art.

The invention relates to a preparation method of a heat insulation material for a crash survival memory, which comprises the following steps:

(1) preparing a porous fiber framework: adding the cleaned porous fiber, a normal-temperature binder and a high-temperature binder into water with the volume of 10-100 times that of the porous fiber, and uniformly stirring and dispersing to form slurry; and putting the slurry into a shaping mold, pressing, filtering to remove water, performing (the pressure is 0.05-0.5 MPa, and the pressure is maintained for 0.5-2 hours), roasting at 1000-1200 ℃ for 0.5-2 hours, and cooling to obtain the porous fiber framework.

Wherein the porous fiber is mullite fiber, alumina silicate fiber or alumina fiber; the diameter of the porous fiber is less than 30um, and the length is less than 2 mm. Cleaning the porous fiber: firstly, washing the steel ball by using an acid solution (a diluted water solution of hydrochloric acid, sulfuric acid or nitric acid) with the pH = 2-6 to remove slag balls and impurities, and then repeatedly washing the steel ball by using deionized water until the steel ball is neutral.

The normal temperature binder is at least one of organic binders such as polyacrylamide, epoxy resin, starch and the like; polyacrylamide or starch is preferred. The normal temperature binder only provides temporary setting function for the porous fiber skeleton and can be decomposed after high temperature sintering.

The high-temperature binder is boron nitride or boron carbide. The high-temperature binder can play a role in fixing and supporting the fiber framework after high-temperature melting. The high temperature binder particle size should be less than 10 um.

The mass ratio of the porous fiber to the normal-temperature binder and the high-temperature binder is 1 (0.05-0.3) to 0.05-0.3.

Dispersing aids, such as sodium dodecylbenzene sulfonate, can be added as necessary during the preparation of the porous fibrous skeleton.

(2) Preparing composite sol: stirring and mixing an aluminum precursor, deionized water and ethanol at 50-70 ℃, cooling to room temperature after the solution is clarified to obtain aluminum sol, adding acid and a silicon precursor into the aluminum sol, stirring for 50-60 minutes, adding aniline and acetone, and stirring for 5-15 minutes to obtain the silicon-aluminum composite sol.

In the aluminum sol, the aluminum precursor is any one of aluminum sec-butoxide, aluminum isopropoxide, aluminum nitrate and aluminum chloride; the molar ratio of the aluminum precursor to the deionized water to the ethanol is 1 (0.4-1) to 4-10.

Acid is used as a catalyst in the preparation of the silicon-aluminum composite sol. The acid may be any of hydrochloric acid, nitric acid or acetic acid. The using amount of the acid is 0.003-0.03 time of the molar weight of the aluminum precursor.

The silicon precursor is any one of ethyl orthosilicate, trimethylmethoxysilane and trimethylethoxysilane; the molar ratio of the aluminum precursor to the silicon precursor is 1 (0.125-0.33); the molar ratio of the aluminum precursor to the aniline is 1 (0.4-5); the molar ratio of the aluminum precursor to the acetone is 1 (0.4-5).

(3) Preparing a heat insulation material: putting the porous fiber framework obtained in the step (1) into a shell of a crash survival memory; adding an infrared shielding agent into the silicon-aluminum composite sol obtained in the step (2), adding the mixture into a crash survival memory shell, ensuring that the silicon-aluminum composite sol submerges a porous fiber framework, then ultrasonically dispersing for 15-25 min, and standing for 2-5 hours to form silicon-aluminum composite wet gel; finally, placing the silicon-aluminum composite wet gel in absolute ethyl alcohol for aging for 1-3 days (replacing the absolute ethyl alcohol once every 12-24 hours); and then, ethanol is used as a medium, and supercritical drying is carried out at the temperature of 260-300 ℃ and under the pressure of 6-15 MPa, so as to obtain the heat insulating material for the crash survival memory.

The infrared shielding agent is any one of silicon carbide, titanium oxide and potassium hexatitanate. The infrared shielding agent functions to resist heat transfer caused by infrared radiation at high temperatures. The dosage of the infrared shielding agent is not more than 20% of the fiber mass.

The raw materials for preparing the materials are all commercial products. Other additives can be added in the process according to requirements.

Compared with the prior art, the invention has the following remarkable advantages:

1. the high-temperature heat insulation effect is better. Compared with the silicon oxide aerogel, the silicon-doped modified aluminum oxide composite aerogel has better high-temperature resistance and high-temperature heat insulation effect. The silica aerogel itself can undergo phase change at a temperature of over 800 ℃, so that internal nano-pores collapse, the structure is densified, and the heat conductivity coefficient is rapidly increased, while the gamma phase change of the alumina aerogel occurs at 900-1000 ℃, the alpha phase change generally occurs at 1200 ℃, and the alumina aerogel can still maintain the porous structure of the aerogel in the gamma phase, so that the silica aerogel has a low heat conductivity coefficient. After doping modification, the phase transition temperature of the alumina aerogel is further improved, for example, the gamma phase transition energy of the silicon-doped alumina aerogel is improved to 1000-1100 ℃, and the alpha phase transition energy is improved to over 1300 ℃, so that the high temperature resistance of the alumina aerogel is obviously improved, and the heat insulation performance at 1100 ℃ is also obviously improved; the material does not contain organic components, and does not burn at the high temperature of 1100 ℃, so that the material provides guarantee for good heat insulation performance;

2. higher mechanical strength and good processing performance. In the prior art, the reinforced fiber is directly dispersed in silica sol and then formed into a heat-insulating material, and because the sol has certain viscosity, the fiber is difficult to uniformly disperse in the sol, the heat-insulating material has low strength and poor processability; according to the invention, the reinforced fiber is prepared into a high-strength porous fiber framework in advance through a high-temperature-resistant binder, then the silicon-doped alumina aerogel is constructed in situ in the porous fiber framework, and the three-dimensional reticular porous fiber framework enables the fiber and the aerogel to be uniformly distributed, so that the strength of the composite material is further improved, and the composite material has better processing performance;

3. organic and inorganic binders are adopted to bond and form high-temperature-resistant inorganic fibers into a porous fiber framework, the organic phase is removed after high-temperature calcination, and the obtained porous fiber framework is used as a matrix of a heat-insulating material, so that high strength is provided; and silica-doped alumina sol is constructed in situ in pores of the porous fiber, an infrared shielding agent is added to inhibit radiation heat transfer at high temperature, and the aerogel heat insulating material for the crash survivor memory is obtained after aging and drying processes, so that the material has more excellent strength and vibration damping performance, and the use requirement of the crash survivor memory is met.

Drawings

FIG. 1 is a photograph of a heat insulating material prepared in example 1 of the present invention.

FIG. 2 is a microstructure of a porous fibrous skeleton and thermal insulation material prepared according to example 1 of the present invention. a is a porous fiber skeleton; b is a heat insulation material formed by compounding porous fiber framework with silicon-aluminum aerogel.

FIG. 3 is a diagram showing the nitrogen desorption isotherm and the pore size distribution of the thermal insulation material prepared in example 2 of the present invention (the inset is the pore size distribution).

FIG. 4 is a comparison of the thermal insulation effects of the thermal insulation materials prepared in examples 1 and 2 of the present invention and the ceramic fiber mats (test conditions: heating temperature 1300 ℃, material thickness 15mm, test time 10min, test material back surface temperature).

Detailed Description

The preparation and properties of the thermal insulation material for crash survivor memory of the present invention are further illustrated by the following specific examples.