A method for preparing ultra-low density rigid ceramic insulation tile

Abstract

The invention discloses a method for preparing ultra-low density rigid ceramic thermal insulation tiles, which belongs to the technical field of high-performance thermal protection material preparation. The method comprises the following steps: adding ceramic fibers into water and mixing them evenly to obtain ceramic fiber slurry; mixing sintering aid powder and polymer solution evenly to obtain a sintering aid mixture; stirring the ceramic fiber slurry, and then adding the sintering aid mixture inwardly in an intermittent spraying manner, and continuing to stir after the addition is completed to obtain thermal insulation tile slurry; transferring the thermal insulation tile slurry to a filtering tool, and after standing and settling, removing the clear liquid above the precipitated deposit from the top until the precipitated deposit is exposed to the water surface, and then filtering out excess water from the filter screen below the filtering tool to obtain a thermal insulation tile wet blank; drying the thermal insulation tile wet blank to obtain a thermal insulation tile dry blank; loading the dried thermal insulation tile into a sealed ceramic box, and then transferring it to a muffle furnace for sintering to obtain an ultra-low density rigid ceramic insulation tile.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance thermal protection material preparation, and in particular relates to a method for preparing ultra-low-density rigid ceramic thermal insulation tiles. Background Art

[0002] Rigid ceramic insulation tiles are a type of thermal insulation material with a micron-porous structure, made from ceramic fibers and sintering aids through wet dispersion slurrying, filtration forming, drying and sintering. The traditional preparation process for insulation tiles is to add sintering aid powder directly to the slurry and then filter it together with the fibers. Due to the size and density differences between the sintering aid and the fibers, this method results in uncontrollable and uneven residual amount and distribution of the aid during filtration. In addition, during drying, the sintering aid powder will migrate to the surface of the insulation tile as the liquid evaporates, resulting in further uneven distribution of the sintering aid. This is especially true for ultra-low-density rigid ceramic insulation tiles, as these problems are more prominent due to their low density, large pore size, high porosity, and small number of fiber overlap points. To address these issues, it is necessary to further research a method for preparing ultra-low-density rigid ceramic insulation tiles. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems existing in the background technology and to provide a method for preparing ultra-low density rigid ceramic insulation tiles.

[0004] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are as follows:

[0005] A method for preparing ultra-low density rigid ceramic insulation tiles comprises the following steps:

[0006] 1) adding ceramic fibers into water and mixing uniformly to obtain ceramic fiber slurry;

[0007] 2) Evenly mixing the sintering aid powder and the polymer solution to obtain a sintering aid mixture; stirring the ceramic fiber slurry, and then adding the sintering aid mixture into the ceramic fiber slurry by intermittent spraying, and continuing to stir after the addition is completed to obtain the insulation tile slurry;

[0008] 3) The obtained insulation tile slurry is transferred to a filtering tool. After settling, the clear liquid above the precipitate is removed from the top until the precipitate is exposed to the water surface. Then, the excess water is filtered out from the filter screen below the filtering tool to obtain the insulation tile wet blank;

[0009] 4) drying the obtained thermal insulation tile wet blank to obtain a thermal insulation tile dry blank;

[0010] 5) The obtained insulation tiles are dried and packed into a sealed ceramic box, and then transferred to a muffle furnace for sintering to obtain ultra-low density rigid ceramic insulation tiles.

[0011] Furthermore, the ceramic fiber in step 1) includes one or a combination of quartz fiber, alumina fiber, mullite fiber, etc., and the length of the ceramic fiber is not less than 10 mm; the concentration of the ceramic fiber slurry is 0.1% to 1%.

[0012] Furthermore, in step 2), the stirring speed of the ceramic fiber slurry is 1000-4000 r / min, and the stirring is continued for 5-60 minutes after the addition is completed.

[0013] Furthermore, the jet diameter of the intermittent spraying in step 2) is not greater than 100 μm, and the jet length is not greater than 10 mm.

[0014] Furthermore, the sintering aid powder in step 2) includes one or both of boron nitride and boron carbide, and the mass of the sintering aid powder accounts for 1% to 10% of the weight of the ceramic fiber.

[0015] Furthermore, in step 2), the mass ratio of the sintering aid powder to the polymer in the polymer solution is (2-5):10, and the polymer concentration in the polymer solution is 5%-20%.

[0016] Furthermore, the polymer in step 2) is a water-insoluble polymer, preferably one of meta-aramid and polyamic acid; the solvent of the polymer solution is a water-soluble solvent, preferably N,N-dimethylformamide.

[0017] Furthermore, in step 3), the mixture is allowed to stand and settle for 1 to 3 hours.

[0018] Furthermore, the drying temperature in step 4) does not exceed 200°C.

[0019] Furthermore, in step 5), the sintering temperature is 1000-1300° C., and the sintering time is 1-5 hours.

[0020] The beneficial effects achieved by the present invention are:

[0021] (1) The length of the ceramic fiber in step 1 is not less than 10 mm, which can ensure that the final insulation tile density is not greater than 0.1 g / cm.

[0022] (2) In step 2, the sintering aid mixture is added inwardly by intermittent spraying, which ensures that the sintering aid mixture is precipitated in the water as short amorphous fiber flocs, and is entangled and hooked with the ceramic fibers to form adhesion on the surface of the ceramic fibers.

[0023] (3) The preparation method of the sintering aid mixture in step 2 is: uniformly mix the sintering aid powder with the polymer solution to obtain the sintering aid mixture, which can ensure that the sintering aid powder is wrapped in the polymer and tightly adheres to the surface of the ceramic fiber, ensuring that the sintering aid powder will not be lost, will not be unevenly distributed due to density differences between the sintering aid powder and the ceramic fiber during natural standing, and will not migrate with the loss of liquid during the drying process. This ensures that the sintering aid powder is evenly distributed inside the insulation tile.

[0024] (4) In step 3, the clear liquid above the sediment is removed from above until the sediment is exposed to the water surface, and then the excess water is filtered out from the filter mesh below the filter tool. First, it can avoid the increase in fiber stacking density due to the impact of water during the water filtration process; secondly, it can avoid the orientation distribution of the fibers in the plane under the impact of water flow, ensuring that the fibers are evenly distributed in the three-dimensional direction.

[0025] (5) The obtained insulation tiles are dried and packed into a sealed ceramic box in step 5. The air in the box is sufficient to ensure the oxidation requirements of the sintering aid. At the same time, the sealed box can prevent the high temperature escape of the sintering aid and prevent the strength of the insulation tiles from decreasing. DETAILED DESCRIPTION

[0026] In order to make the various technical features and advantages or technical effects of the above technical solutions of the present invention more obvious and easy to understand, they are described in detail below in conjunction with embodiments.

[0027] Example 1:

[0028] A method for preparing ultra-low density rigid ceramic insulation tiles comprises the following steps:

[0029] 1) Add quartz fiber of 15 mm in length to water and mix well to obtain a ceramic fiber slurry with a concentration of 0.1%;

[0030] 2) The sintering aid powder and the polymer solution are mixed evenly to obtain a sintering aid mixture; the stirring speed of the ceramic fiber slurry is adjusted to 1000 r / min, and then the sintering aid mixture is added inwardly by intermittent spraying, with a jet diameter of 50 to 100 μm and a jet length of 5 to 10 mm. After the addition is completed, stirring is continued for 60 minutes to obtain the insulation tile slurry;

[0031] The amount of the sintering aid mixture added is: the mass of the sintering aid contained in the sintering aid mixture accounts for 1% of the weight of the ceramic fiber;

[0032] The sintering aid powder is boron nitride;

[0033] The mass ratio of the sintering aid powder to the polymer is 2:10; the polymer concentration in the polymer solution is 5%;

[0034] The polymer is a water-insoluble polymer, and the solvent of the polymer solution is miscible with water. The polymer is meta-aramid, and the solvent is N,N-dimethylformamide;

[0035] 3) Transferring the thermal insulation tile slurry prepared in step 2) to a filtering device, allowing it to settle for 1 hour, removing the clear liquid above the precipitate from above until the precipitate emerges from the water surface, and then filtering out excess water through a filter screen below the filtering device to obtain a wet thermal insulation tile blank;

[0036] 4) drying the obtained thermal insulation tile wet blank at 200° C. to obtain a thermal insulation tile dry blank;

[0037] 5) The obtained insulation tiles are dried and packed into a sealed ceramic box, and then transferred to a muffle furnace and sintered at 1000°C for 5 hours to obtain ultra-low density rigid ceramic insulation tiles.

[0038] After testing, the density of the prepared thermal insulation tile is 0.05g / cm 3 , room temperature compressive strength is 0.1MPa, room temperature thermal conductivity is 0.034W / (mK), and the fluctuation of room temperature compressive strength values ​​is less than 10% when sampling at different positions.

[0039] Example 2:

[0040] A method for preparing ultra-low density rigid ceramic insulation tiles comprises the following steps:

[0041] 1) 50% each of 10 mm long quartz fiber and 10 mm long alumina fiber were added to water and mixed evenly to obtain a ceramic fiber slurry with a concentration of 1%;

[0042] 2) The sintering aid powder and the polymer solution are mixed evenly to obtain a sintering aid mixture; the stirring speed of the ceramic fiber slurry is adjusted to 4000 r / min, and then the sintering aid mixture is added inwardly by intermittent spraying, with a jet diameter of 50-100 μm and a jet length of 5-10 mm. After the addition is completed, stirring is continued for 5 minutes to obtain the insulation tile slurry;

[0043] The amount of the sintering aid mixture added is: the mass of the sintering aid contained in the sintering aid mixture accounts for 10% of the weight of the ceramic fiber;

[0044] The sintering aid powder is boron nitride;

[0045] The mass ratio of the sintering aid powder to the polymer is 5:10; the polymer concentration in the polymer solution is 20%;

[0046] The polymer is a water-insoluble polymer, and the solvent of the polymer solution is miscible with water. The polymer is meta-aramid, and the solvent is N,N-dimethylformamide;

[0047] 3) The thermal insulation tile slurry prepared in step 2) is transferred to a filtering device and allowed to settle for 3 hours. The clear liquid above the precipitate is removed from the top until the precipitate is exposed to the water surface. Excess water is then filtered out through a filter screen below the filtering device to obtain a wet thermal insulation tile blank.

[0048] 4) drying the obtained thermal insulation tile wet blank at 150° C. to obtain a thermal insulation tile dry blank;

[0049] 5) The obtained insulation tiles are dried and packed into a sealed ceramic box, and then transferred to a muffle furnace and sintered at 1300°C for 1 hour to obtain ultra-low density rigid ceramic insulation tiles.

[0050] After testing, the density of the prepared thermal insulation tile is 0.08g / cm 3 , room temperature compressive strength is 0.25MPa, room temperature thermal conductivity is 0.041W / (mK), and the room temperature compressive strength value fluctuation is less than 10% when sampling at different positions.

[0051] Example 3:

[0052] A method for preparing ultra-low density rigid ceramic insulation tiles comprises the following steps:

[0053] 1) Add quartz fiber of 15 mm in length to water and mix well to obtain a ceramic fiber slurry with a concentration of 0.5%;

[0054] 2) The sintering aid powder and the polymer solution are mixed evenly to obtain a sintering aid mixture; the stirring speed of the ceramic fiber slurry is adjusted to 2500r / min, and then the sintering aid mixture is added inwardly by intermittent spraying, with a jet diameter of 50-100μm and a jet length of 5-10mm. After the addition is completed, stirring is continued for 30 minutes to obtain the insulation tile slurry;

[0055] The amount of the sintering aid mixture added is: the mass of the sintering aid contained in the sintering aid mixture accounts for 5% of the weight of the ceramic fiber;

[0056] The sintering aid powder is boron carbide;

[0057] The mass ratio of the sintering aid powder to the polymer is 3:10; the polymer concentration in the polymer solution is 13%;

[0058] The polymer is a water-insoluble polymer, and the solvent of the polymer solution is miscible with water. The polymer is polyamic acid, and the solvent is N,N-dimethylformamide;

[0059] 3) The thermal insulation tile slurry prepared in step 2) is transferred to a filtering device, and after settling for 2 hours, the clear liquid above the precipitate is removed from the top until the precipitate is exposed to the water surface, and then the excess water is filtered out through the filter screen below the filtering device to obtain a wet thermal insulation tile blank;

[0060] 4) drying the obtained thermal insulation tile wet blank at 200° C. to obtain a thermal insulation tile dry blank;

[0061] 5) The obtained insulation tiles are dried and packed into a sealed ceramic box, and then transferred to a muffle furnace and sintered at 1100°C for 3 hours to obtain ultra-low density rigid ceramic insulation tiles.

[0062] After testing, the prepared insulation tile has a density of 0.07g / cm3, a room temperature compressive strength of 0.15MPa, and a room temperature thermal conductivity of 0.037W / (mK). When samples are taken at different locations, the fluctuation in the room temperature compressive strength value is less than 10%.

[0063] Comparative Example:

[0064] Compared with Example 1:

[0065] 1) Add quartz fiber of 15 mm in length to water and mix well to obtain a ceramic fiber slurry with a concentration of 0.1%;

[0066] 2) Adjust the stirring speed of the ceramic fiber slurry to 1000 r / min, then add the sintering aid powder into it, and continue stirring for 60 minutes after the addition is completed to obtain the insulation tile slurry;

[0067] The mass of the sintering aid powder accounts for 1% of the weight of the ceramic fiber;

[0068] The sintering aid powder is boron nitride;

[0069] 3) transferring the thermal insulation tile slurry prepared in step 2) into a filtering device, allowing it to settle for 1 hour, and then filtering out water through the filter screen below the filtering device to obtain a wet thermal insulation tile blank;

[0070] 4) drying the obtained thermal insulation tile wet blank at 200° C. to obtain a thermal insulation tile dry blank;

[0071] 5) The obtained insulation tiles are dried and packed into a sealed ceramic box, and then transferred to a muffle furnace and sintered at 1000°C for 1 hour to obtain ultra-low density rigid ceramic insulation tiles.

[0072] After testing, the density of the prepared thermal insulation tile is 0.12g / cm 3 , room temperature compressive strength is 0.05MPa, room temperature thermal conductivity is 0.034W / (mK), and the room temperature compressive strength value fluctuation is greater than 20% when sampling at different positions.

[0073] Although the present invention has been disclosed as above by way of embodiments, they are not intended to limit the present invention. Any appropriate modification or equivalent substitution of the technical solution of the present invention by a person skilled in the art should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on that defined in the claims.

Claims

1. A method for preparing ultra-low density rigid ceramic insulation tiles, characterized in that: The steps include: 1) adding ceramic fibers into water and mixing them uniformly, wherein the length of the ceramic fibers is not less than 10 mm, to obtain a ceramic fiber slurry; 2) Evenly mix the sintering aid powder and the polymer solution to obtain a sintering aid mixture; stir the ceramic fiber slurry, and then add the sintering aid mixture into the slurry by intermittent spraying, and continue stirring after the addition is completed to obtain the insulation tile slurry; 3) The thermal insulation tile slurry prepared in step 2) is transferred to a filtering device. After settling, the clear liquid above the precipitate is removed from the top until the precipitate is exposed to the water surface. Excess water is then filtered out through a filter screen below the filtering device to obtain a wet thermal insulation tile blank. 4) Drying the obtained thermal insulation tile wet blank to obtain a thermal insulation tile dry blank; 5) The obtained insulation tiles are dried and packed into a sealed ceramic box, and then transferred to a muffle furnace for sintering to obtain ultra-low density rigid ceramic insulation tiles.

2. The preparation method according to claim 1, wherein The ceramic fiber in step 1) comprises one or a combination of quartz fiber, alumina fiber, and mullite fiber; the concentration of the ceramic fiber slurry is 0.1% to 1%.

3. The preparation method according to claim 1, wherein In step 2), the stirring speed of the ceramic fiber slurry is 1000-4000 r / min, and the stirring is continued for 5-60 minutes after the addition is completed.

4. The preparation method according to claim 1, wherein The jet diameter of the intermittent spraying in step 2) is not greater than 100 μm, and the jet length is not greater than 10 mm.

5. The preparation method according to claim 1, wherein The sintering aid powder in step 2) includes one or both of boron nitride and boron carbide, and the mass of the sintering aid powder accounts for 1% to 10% of the weight of the ceramic fiber.

6. The preparation method according to claim 1, wherein In step 2), the mass ratio of the sintering aid powder to the polymer in the polymer solution is (2-5):10, and the polymer concentration in the polymer solution is 5%-20%.

7. The preparation method according to claim 1 or 6, wherein The polymer in step 2) is a water-insoluble polymer, such as meta-aramid or polyamic acid; the solvent of the polymer solution is a water-soluble solvent, such as N,N-dimethylformamide.

8. The preparation method according to claim 1, wherein In step 3), the mixture is allowed to settle for 1 to 3 hours.

9. The preparation method according to claim 1, wherein In step 4), the drying temperature does not exceed 200°C.

10. The preparation method according to claim 1, wherein In step 5), the sintering temperature is 1000-1300° C., and the sintering time is 1-5 hours.