High-temperature-resistant rigid wave-transparent thermal insulation material and preparation method thereof

Abstract

The invention provides a high-temperature-resistant rigid wave-transparent thermal insulation material and a preparation method thereof, and the high-temperature-resistant rigid wave-transparent thermal insulation material is prepared from the following raw materials: chopped fibers, binder slurry and starch, the chopped fibers are chopped alumina fibers or chopped mullite fibers; the binder slurry comprises aluminum dihydrogen phosphate, a dispersing agent and a solvent; the mass ratio of the aluminum dihydrogen phosphate to the chopped fibers is 1: (10-50); the mass ratio of the starch to the chopped fibers is 1: (2-20). The high-temperature-resistant rigid wave-transparent thermal insulation material has excellent temperature resistance and strength performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of thermal protection materials, and particularly relates to a high-temperature resistant rigid wave-transparent heat-insulating material and a preparation method thereof. Background Art

[0002] Due to its excellent characteristics such as light weight, heat insulation performance, high-temperature resistance performance, and wave-transparent performance, rigid wave-transparent heat-insulating materials are widely used as thermal protection materials for aerospace vehicles. At present, the preparation mostly uses quartz fiber-based materials. Quartz fiber has a low density (2.2 g / cm 3 ), good corrosion resistance, good thermal shock resistance, and at the same time has good electrical insulation and mechanical properties. However, cristobalite phase is easily precipitated at high temperatures, resulting in fiber embrittlement and affecting the high-temperature mechanical properties of the material. The long-term service temperature is 1050 °C, which cannot meet the use requirements in higher temperature environments. Mullite fiber is a high-temperature resistant ceramic fiber composed of mullite phase (3Al 2 O 3 ·2SiO 2 ); when the alumina content in the fiber is greater than 80%, it is called alumina fiber. Mullite fiber and alumina fiber have the characteristics of high melting point, low thermal conductivity, and high-temperature stability, and become the preferred materials for the heat-insulating layer of aircraft.

[0003] When preparing a rigid heat-insulating material with a three-dimensional network structure, the binder largely determines the stability and temperature resistance of the skeleton. Commonly used binders include silica sol and B 2 O 3 or boron compounds such as B 4 C. When silica sol is used as the binder, silica sol will diffuse from the inside to the ceramic surface with water during the drying process, resulting in a density gradient and a large number of unbonded points in the skeleton structure; B 2 O 3 or B 4 C has good fluidity at high temperatures, can play a bonding role at the fiber lap joints, and has relatively high strength, but has poor temperature resistance and is prone to volatilization at high temperatures, resulting in the loss of the bonding effect at the nodes.

[0004] Therefore, in view of the above problems, there is an urgent need to provide a preparation method for a high-temperature resistant rigid heat-insulating material. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a high-temperature resistant rigid wave-transparent heat-insulating material and a preparation method thereof, aiming to solve the problems of poor temperature resistance and insufficient bonding force of existing heat-insulating materials.

[0006] To solve the above problems, the first aspect of the present invention provides a high-temperature resistant rigid wave-transparent heat-insulating material, and its preparation raw materials include: Short-cut fibers, binder slurry, and starch; The chopped fibers are chopped alumina fibers or chopped mullite fibers; the binder slurry includes aluminum dihydrogen phosphate, a dispersant, and a solvent; the mass ratio of aluminum dihydrogen phosphate to the chopped fibers is 1:10 - 50; the mass ratio of starch to the chopped fibers is 1:2 - 20.

[0007] Preferably, the dispersant is ammonium polyacrylate.

[0008] Preferably, the aspect ratio of the chopped fibers is 10 - 100:1.

[0009] Preferably, the mass ratio of aluminum dihydrogen phosphate to the chopped fibers is 1:15 - 25; the mass ratio of starch to the chopped fibers is 1:5 - 15.

[0010] Preferably, the mass ratio of the chopped fibers to the binder slurry is 1:20 - 80; in the binder slurry, the mass fraction of the dispersant is 0.2 - 0.8 wt%.

[0011] The second aspect of the present invention provides a preparation method of the above-mentioned high-temperature resistant rigid wave-transparent heat insulation material, including the following steps: S1: Provide chopped fibers; S2: Dissolve aluminum dihydrogen phosphate and the dispersant in the solvent to obtain a mixed solution; S3: Mix the chopped fibers with the mixed solution, and then add starch to obtain a mixed slurry; S4: Transfer the mixed slurry to a molding die, and perform drying and sintering to obtain the high-temperature resistant rigid wave-transparent heat insulation material.

[0012] Preferably, in step S1, the providing of the chopped fibers specifically includes: soaking alumina fibers or mullite fibers in water; using a stirring device to chop the alumina fibers or mullite fibers, and the stirring time is 5 - 10 min.

[0013] Preferably, in step S1, the mass ratio of the alumina fibers or mullite fibers to water is 1:10 - 50.

[0014] Preferably, in step S4, the drying specifically includes the following steps: drying the wet blank to obtain a dry blank, the drying temperature is 100 - 150 °C, and the heat preservation time is 12 - 24 h.

[0015] Preferably, in step S4, the sintering specifically includes the following steps: first, raise the temperature at a heating rate of 1 - 5 °C / min to 400 - 600 °C, keep warm for 1 - 3 h for degumming; then raise the temperature at a heating rate of 5 - 10 °C / min to 1400 - 1600 °C, keep warm for 1 - 3 h for sintering to obtain the high-temperature resistant rigid wave-transparent heat insulation material.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The high-temperature resistant rigid wave-transparent heat-insulating material of the embodiment of the present invention uses starch as a low-temperature binder, which helps the product to form after the chopped fibers are prepared into a wet blank and dried; aluminum dihydrogen phosphate is used as a high-temperature binder, and aluminum phosphate is generated after high-temperature sintering, which plays a role in shaping the chopped fibers. Phosphate binders have good high-temperature fluidity, can connect the fiber lap joints, and form a uniform and stable three-dimensional structure inside the green body; the addition of a dispersant can increase the viscosity of the slurry and make the chopped fibers more evenly dispersed. The high-temperature resistant fibers used are mullite fibers or alumina fibers. Mullite fibers and alumina fibers have the characteristics of high melting point, low thermal conductivity, and high-temperature stability, which increase the use temperature of the rigid heat-insulating material to 1500°C, have higher heat resistance than quartz fiber-based materials, and at the same time, due to the lower prices of mullite fibers and alumina fibers, the production cost is reduced, creating higher economic value.

[0017] The high-temperature resistant rigid heat-insulating material of the present invention and its preparation method, the prepared mullite-based or alumina-based heat-insulating material has a density of 0.3~0.6 g / cm 3 , the compressive strength ≥ 1.1 MPa, the heat resistance ≥ 1500°C, and after heat treatment at room temperature to 1500°C in a high-temperature sintering furnace for 5 times, the linear shrinkage rate ≤ 5%. Specific embodiments

[0018] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] The first aspect of the embodiment of the present invention provides a high-temperature resistant rigid wave-transparent heat-insulating material, and its preparation raw materials include: Chopped fibers, binder slurry and starch; The chopped fibers are chopped alumina fibers or chopped mullite fibers; the binder slurry includes aluminum dihydrogen phosphate, a dispersant and a solvent; the mass ratio of aluminum dihydrogen phosphate to chopped fibers is 1:10~50; the mass ratio of starch to chopped fibers is 1:2~20.

[0020] The high-temperature resistant rigid wave-transparent heat insulation material of the embodiment of the present invention uses starch as a low-temperature binder, which helps the product to form after the chopped fibers are prepared into a wet blank and dried; aluminum dihydrogen phosphate is used as a high-temperature binder, and aluminum phosphate is generated after high-temperature sintering, which plays a role in shaping the chopped fibers. Phosphate binders have good high-temperature fluidity, can connect the fiber lap joints, and form a uniform and stable three-dimensional structure inside the blank. The addition of a dispersant can increase the viscosity of the slurry and make the chopped fibers more evenly dispersed. The high-temperature resistant fibers used are mullite fibers or alumina fibers. Mullite fibers and alumina fibers have the characteristics of high melting point, low thermal conductivity, and high-temperature stability, which increase the service temperature of the rigid heat insulation material to 1500 °C, have higher heat resistance than quartz fiber-based materials, and at the same time, due to the lower prices of mullite fibers and alumina fibers, the production cost is reduced, creating higher economic value.

[0021] Preferably, the dispersant is ammonium polyacrylate. The addition of ammonium polyacrylate can increase the viscosity of the slurry and make the chopped fibers more evenly dispersed.

[0022] Preferably, the aspect ratio of the chopped fibers is 10~100:1. The heat insulation material prepared from chopped fibers with an aspect ratio of 10~100:1 has higher strength performance.

[0023] Preferably, the mass ratio of aluminum dihydrogen phosphate to chopped fibers is 1:15~25. Within this mass ratio range, the prepared heat insulation material has higher strength and stronger temperature resistance.

[0024] Preferably, the mass ratio of starch to chopped fibers is 1:5~15. Within this mass ratio range, the wet blank has better formability, and the sintered heat insulation material has higher strength and stronger temperature resistance.

[0025] Preferably, in the binder slurry, the mass fraction of the dispersant is 0.2~0.8wt%.

[0026] Preferably, the mass ratio of chopped fibers to the binder slurry is 1:20~80.

[0027] The second aspect of the embodiment of the present invention provides a preparation method of the above-mentioned high-temperature resistant rigid wave-transparent heat insulation material, including the following steps: S1: Provide chopped fibers; S2: Dissolve aluminum dihydrogen phosphate and the dispersant in a solvent to obtain a mixed solution; S3: Mix the chopped fibers with the mixed solution, and then add starch to obtain a mixed slurry; S4: Transfer the mixed slurry to a molding die, and perform drying and sintering to obtain the high-temperature resistant rigid wave-transparent heat insulation material.

[0028] The method for preparing the high temperature resistant rigid wave-transmitting heat-insulating material of the present invention directly adds phosphate to prepare the premixed liquid, and the operation is simple and convenient.

[0029] Preferably, in step S1, providing chopped fibers specifically comprises: soaking alumina fibers or mullite fibers in water; and chopping the alumina fibers or mullite fibers using a stirring device, wherein the stirring time is 5 to 10 minutes.

[0030] Preferably, in step S1, the mass ratio of the alumina fiber or mullite fiber to water is 1:10-50.

[0031] Preferably, step S2 specifically comprises: adding aluminum dihydrogen phosphate powder dried at 80-120° C. into high-purity water and stirring thoroughly to prepare a premixed solution, and then adding ammonium polyacrylate as a dispersant into the premixed solution to obtain a mixed solution.

[0032] Preferably, step S4 specifically includes the following steps: transferring the obtained mixed slurry to a molding mold, removing excess solution by vacuum filtration to obtain a wet blank; the vacuum filtration time is 5 to 10 minutes.

[0033] Preferably, the drying in step S4 specifically comprises the following steps: drying the wet blank to obtain a dry blank, the drying temperature is 100-150° C., and the insulation time is 12-24 hours.

[0034] Preferably, the wet blank is dried to obtain a dry blank, the drying temperature is 100-150° C., and the insulation time is 12-24 hours.

[0035] Preferably, in step S4, the sintering specifically includes the following steps: first, heating the temperature to 400-600°C at a heating rate of 1-5°C / min, keeping the temperature for 1-3 hours, and debinding; then heating the temperature to 1400-1600°C at a heating rate of 5-10°C / min, keeping the temperature for 1-3 hours, and sintering to obtain the high temperature resistant rigid wave-transmitting heat-insulating material.

[0036] Example 1 The high temperature resistant rigid wave-transmitting heat-insulating material of this embodiment is prepared by raw materials including: Short-cut alumina fibers, binder slurry and starch; the mass ratio of the short-cut alumina fibers to the binder slurry is 1:50. The aspect ratio of the short-cut alumina fibers is 50:1.

[0037] The binder slurry includes aluminum dihydrogen phosphate, ammonium polyacrylate and water; in the binder slurry, the mass fraction of ammonium polyacrylate is 0.5wt%, the mass ratio of aluminum dihydrogen phosphate to short-cut fibers is 1:20, and the mass ratio of starch to short-cut fibers is 1:10.

[0038] The preparation method of the high-temperature resistant rigid wave-transparent heat insulation material of this embodiment includes the following steps: S1: Immerse alumina fibers in water, and the mass ratio of alumina fibers to water is 1:20; use a stirring device to cut the alumina fibers short, and the stirring time is 10 min to obtain short-cut alumina fibers; S2: Add ammonium dihydrogen phosphate powder dried at 100 °C to high-purity water and stir well to prepare a premixed solution, and then add ammonium polyacrylate as a dispersant to the premixed solution to obtain a mixed solution; S3: Mix the short-cut alumina fibers with the mixed solution, and then add starch to obtain a mixed slurry; S4: Transfer the obtained mixed slurry to a molding die, remove the excess solution by vacuum filtration to obtain a wet blank; the vacuum filtration time is 10 min; dry the wet blank to obtain a dry blank, the drying temperature is 100 °C, and the heat preservation time is 24 h. Then, raise the temperature to 600 °C at a heating rate of 2 °C / min and keep it warm for 1 h for degumming; then raise the temperature to 1600 °C at a heating rate of 8 °C / min and keep it warm for 1 h for sintering to obtain the high-temperature resistant rigid wave-transparent heat insulation material.

[0039] Example 2 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment, its preparation raw materials include: Short-cut alumina fibers, binder slurry and starch; the mass ratio of short-cut alumina fibers to binder slurry is 1:40. The aspect ratio of the short-cut alumina fibers is 50:1.

[0040] The binder slurry includes ammonium dihydrogen phosphate, ammonium polyacrylate and water; in the binder slurry, the mass fraction of ammonium polyacrylate is 0.2 wt%. The mass ratio of ammonium dihydrogen phosphate to short-cut fibers is 1:15; the mass ratio of starch to short-cut fibers is 1:15.

[0041] The preparation method of the high-temperature resistant rigid wave-transparent heat insulation material of this embodiment is the same as that of Example 1.

[0042] Example 3 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment, its preparation raw materials include: Short-cut alumina fibers, binder slurry and starch; the mass ratio of short-cut alumina fibers to binder slurry is 1:60. The aspect ratio of the short-cut alumina fibers is 50:1.

[0043] The binder slurry includes ammonium dihydrogen phosphate, ammonium polyacrylate and water; in the binder slurry, the mass fraction of ammonium polyacrylate is 0.8 wt%. The mass ratio of ammonium dihydrogen phosphate to short-cut fibers is 1:25; the mass ratio of starch to short-cut fibers is 1:5.

[0044] The preparation method of the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment is the same as that in Embodiment 1.

[0045] Embodiment 4 The preparation raw materials of the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment include: Short-cut alumina fibers, binder slurry and starch; the mass ratio of the short-cut alumina fibers to the binder slurry is 1:20. The aspect ratio of the short-cut alumina fibers is 50:1.

[0046] The binder slurry includes aluminum dihydrogen phosphate, ammonium polyacrylate and water; in the binder slurry, the mass fraction of ammonium polyacrylate is 0.5 wt%. The mass ratio of aluminum dihydrogen phosphate to the short-cut fibers is 1:10; the mass ratio of starch to the short-cut fibers is 1:20.

[0047] The preparation method of the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment is the same as that in Embodiment 1.

[0048] Embodiment 5 The preparation raw materials of the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment include: Short-cut alumina fibers, binder slurry and starch; the mass ratio of the short-cut alumina fibers to the binder slurry is 1:80. The aspect ratio of the short-cut alumina fibers is 50:1.

[0049] The binder slurry includes aluminum dihydrogen phosphate, ammonium polyacrylate and water; in the binder slurry, the mass fraction of ammonium polyacrylate is 0.5 wt%. The mass ratio of aluminum dihydrogen phosphate to the short-cut fibers is 1:50; the mass ratio of starch to the short-cut fibers is 1:2.

[0050] The preparation method of the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment is the same as that in Embodiment 1.

[0051] Embodiment 6 For the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment, the composition of the preparation raw materials, the mass ratio and the preparation method are the same as those in Embodiment 1, the difference is that the mass ratio of aluminum dihydrogen phosphate to the short-cut fibers is 1:15.

[0052] Embodiment 7 For the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment, the composition of the preparation raw materials, the mass ratio and the preparation method are the same as those in Embodiment 1, the difference is that the mass ratio of aluminum dihydrogen phosphate to the short-cut fibers is 1:25.

[0053] Embodiment 8 For the high-temperature resistant rigid wave-transparent heat-insulating material in this embodiment, the composition of the preparation raw materials, the mass ratio and the preparation method are the same as those in Embodiment 1, the difference is that the mass ratio of aluminum dihydrogen phosphate to the short-cut fibers is 1:10.

[0054] Embodiment 9 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass ratio of aluminum dihydrogen phosphate to chopped fibers is 1:50.

[0055] Embodiment 10 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass ratio of starch to chopped fibers is 1:15.

[0056] Embodiment 11 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass ratio of starch to chopped fibers is 1:5.

[0057] Embodiment 12 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass ratio of starch to chopped fibers is 1:20.

[0058] Embodiment 13 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass ratio of starch to chopped fibers is 1:2.

[0059] Embodiment 14 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass fraction of ammonium polyacrylate is 0.1 wt%.

[0060] Embodiment 15 The high-temperature resistant rigid wave-transparent heat insulation material of this embodiment has the same composition of raw materials for preparation, mass ratio, and preparation method as those of Embodiment 1, with the difference that the mass fraction of ammonium polyacrylate is 1 wt%.

[0061] The strength performance and high-temperature resistance performance of the high-temperature resistant rigid wave-transparent heat insulation materials obtained in the above embodiments were measured, and the test results are shown in Table 1 below. It can be seen from the data in Table 1 that compared with Examples 1-5, the mass ratios of aluminum dihydrogen phosphate to chopped fibers, starch to chopped fibers, and chopped fibers to slurry are different. In contrast, the mass ratios of Examples 1-3 are within the preferred range, and the strength performance and high-temperature resistance performance are better than those of Examples 4 and 5; compared with Examples 1, 6-9, the difference is the mass ratio of aluminum dihydrogen phosphate to chopped fibers. Among them, the mass ratios of Examples 1, 6, and 7 are within the preferred range, and the strength performance and high-temperature resistance performance are better than those of Examples 8 and 9; compared with Examples 1, 10-13, the difference is the mass ratio of starch to chopped fibers. Among them, the mass ratios of Examples 1, 10, and 11 are within the preferred range, and the strength performance and high-temperature resistance performance are better than those of Examples 12 and 13; compared with Examples 1, 14, and 15, the difference is the addition amount of the dispersant. Among them, the amount of the dispersant added in Example 1 is within the preferred range, and the strength performance and high-temperature resistance performance are better than those of Examples 14 and 15.

[0062] Table 1

[0063] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A high temperature resistant rigid wave-transmitting heat-insulating material, characterized in that: The raw materials for its preparation include: chopped fibers, binder slurry and starch; The chopped fibers are chopped alumina fibers or chopped mullite fibers; the binder slurry comprises aluminum dihydrogen phosphate, a dispersant and a solvent; the mass ratio of aluminum dihydrogen phosphate to the chopped fibers is 1:10-50; and the mass ratio of starch to the chopped fibers is 1:2-20.

2. The high temperature resistant rigid wave-transmitting heat-insulating material according to claim 1, characterized in that: The dispersant is ammonium polyacrylate.

3. The high temperature resistant rigid wave-transmitting heat-insulating material according to claim 1, characterized in that: The aspect ratio of the chopped fibers is 10 to 100:

1.

4. The high temperature resistant rigid wave-transmitting heat-insulating material according to claim 1, characterized in that: The mass ratio of aluminum dihydrogen phosphate to short-cut fibers is 1:15-25; the mass ratio of starch to short-cut fibers is 1:5-15.

5. The high temperature resistant rigid wave-transmitting heat-insulating material according to claim 1, characterized in that: The mass ratio of the chopped fibers to the binder slurry is 1:20-80; in the binder slurry, the mass fraction of the dispersant is 0.2-0.8wt%.

6. A method for preparing a high temperature resistant rigid wave-transmitting heat-insulating material as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Provide chopped fibers; S2: dissolving aluminum dihydrogen phosphate and a dispersant in a solvent to obtain a mixed solution; S3: mixing the chopped fibers with the mixed solution, and then adding starch to obtain a mixed slurry; S4: transferring the mixed slurry to a molding mold, drying and sintering, to obtain the high temperature resistant rigid wave-transmitting heat insulating material.

7. The preparation method according to claim 6, characterized in that: In step S1, providing chopped fibers specifically includes: soaking alumina fibers or mullite fibers in water; and chopping the alumina fibers or mullite fibers using a stirring device, wherein the stirring time is 5 to 10 minutes.

8. The preparation method according to claim 7, characterized in that: In step S1, the mass ratio of the alumina fiber or mullite fiber to water is 1:10-50.

9. The preparation method according to claim 6, characterized in that: The drying in step S4 specifically includes the following steps: drying the wet blank to obtain a dry blank, the drying temperature is 100-150° C., and the insulation time is 12-24 hours.

10. The preparation method according to claim 6, characterized in that: In step S4, the sintering specifically includes the following steps: first, heating the temperature to 400-600°C at a heating rate of 1-5°C / min, keeping the temperature for 1-3 hours, and debinding; then heating the temperature to 1400-1600°C at a heating rate of 5-10°C / min, keeping the temperature for 1-3 hours, and sintering to obtain the high temperature resistant rigid wave-transmitting heat-insulating material.

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