Preparation method of low-expansion high-strength ceramic fiber board

Abstract

The invention belongs to the technical field of preparation of ceramic materials, and provides a preparation method of a low-expansion high-strength ceramic fiber board. The preparation method comprises the following steps: mixing ceramic powder and fibers in water according to a certain proportion, and dispersing in ultrasonic equipment; adding a flocculating agent, and slowly stirring to obtain a flocculated block mass; putting the flocculated block mass into a mold for shaping, and separating the flocculated flocculated block mass from water through a filtering device; putting the mold filled with the flocculation block into a drying oven, and drying to obtain a block body consisting of loose fibers and ceramic powder; putting the mold filled with the loose blocks into silica sol for dipping, and removing redundant silica sol through a filter pressing device to obtain a ceramic fiber board; and drying and sintering the pressed ceramic fiber board to finally obtain the high-strength ceramic fiber board. The strength and hardness of the ceramic fiber board are greatly improved, and compared with a traditional silica sol fiber board dipping technology, the preparation technology effectively improves the dipping efficiency and the dipping integrity of the fiber board, and the service performance of the fiber board under the extreme condition is improved.

Description

Technical Field

[0001] This invention relates to the field of high-strength thermal insulation materials, specifically to a method for preparing a fiber-reinforced high-strength and high-toughness ceramic plate. Background Technology

[0002] The main technologies for preparing diamond composite sheets include high-temperature and high-pressure sintering, vacuum hot-pressing sintering, and spark plasma sintering. High-temperature and high-pressure sintering involves placing a mixture of diamond and copper powder in a graphite mold under high temperature and high pressure to sinter the diamond composite sheet. To protect the graphite mold from high temperature and pressure during application, it needs to be fixed with metal hoops. A gasket with high temperature and high pressure resistance and insulation is placed between the graphite mold and the metal hoop to ensure insulation between the mold and the metal hoop and to reduce heat transfer from the mold to the metal hoop. Currently, the gaskets are mainly low-strength aluminum silicate fiberboard, quartz fiberboard, and calcium silicate board. Although low-strength fiberboard has good thermal insulation properties, its low strength means that it can only guarantee a service life of 2-5 cycles during application. Therefore, the short lifespan of low-strength fiberboard significantly increases production costs. Summary of the Invention

[0003] In view of the problems of low compressive strength, poor overall pressure bearing capacity, and inability to be used repeatedly in hot pressing molds in existing fiberboards, the purpose of this invention is to propose a method for preparing low-expansion high-strength ceramic fiberboard.

[0004] If the present invention fails to achieve the above objectives, the following technical solution is adopted: A method for preparing low-expansion, high-strength ceramic fiber board includes the following steps: mixing ceramic powder and fiber in water in a certain proportion and dispersing them in an ultrasonic device; adding a flocculant and slowly stirring to obtain flocculated agglomerates; placing the flocculated agglomerates in a mold for shaping and separating them from the water using a filtration device; placing the mold containing the flocculated agglomerates in an oven for drying to obtain loose blocks composed of fiber and ceramic powder; immersing the mold containing the loose blocks in silica sol and removing excess silica sol using a pressure filter to obtain a ceramic fiber board; and finally drying and sintering the pressed ceramic fiber board to obtain a high-strength ceramic fiber board.

[0005] The ceramic powder is fused silica powder with a particle size of 5000 mesh.

[0006] The fibers are common fiber materials such as fused silica chopped fibers, chopped carbon fibers, alumina fibers, and aluminosilicate fibers.

[0007] The fused silica short-cut fibers have a length of 1-5 mm; and the prepared density is 1.3 g / cm³. 3 When making quartz fiberboard, the chopped fiber length is 1 mm; a low density of 1.0 g / cm³ is prepared. 3When making quartz fiberboard, the length of the chopped fibers is approximately 5mm.

[0008] The preferred mass ratio of carbon fiber to fused silica powder is 1:10, and the mass ratio of fused silica chopped fibers, alumina fibers, aluminosilicate fibers to fused silica powder is 3:10. The fused silica powder and fibers are dispersed in water, and the mass ratio of the total mass of fused silica and fibers to the mass of water used for dispersion is 3:100.

[0009] The flocculant is a 20% aqueous solution of polyaluminum chloride (PAC) and a 2% aqueous solution of anionic polyacrylamide (PAM) and nonionic PAM.

[0010] The order of adding the flocculant is as follows: first add PAC, and after stirring evenly, add an aqueous solution of anionic polyacrylamide (PAM) and nonionic PAM.

[0011] The filtration device is a vacuum filtration device.

[0012] The flocculants are dried at 60°C for more than 24 hours.

[0013] The pressure cylinder reading during the pressing process of the pressed plate is 10 MPa.

[0014] After being pressed, the board is air-dried in a cool place for 24 hours, then transferred to an oven and dried at 60°C for 24 hours.

[0015] The sintering temperature is 400~800℃, preferably 800℃ for chopped quartz fibers and alumina fibers, and preferably 400℃ for chopped carbon fibers.

[0016] This invention proposes a method for preparing low-expansion, high-strength ceramic fiberboard. Based on the traditional preparation process of low-density, low-strength insulating ceramic fiberboard, this method improves the strength of the ceramic fiberboard by impregnating it with silica sol and adjusting the fiber and powder ratio during the fiberboard forming process. This not only greatly improves the strength of the ceramic fiberboard, giving it extremely high compressive strength in addition to its insulating properties, thus expanding the application range of the fiberboard, but also effectively improves the impregnation efficiency and overall integrity of the fiberboard compared to the traditional silica sol impregnation process, thereby enhancing the overall performance of the fiberboard. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in detail below; however, the present invention can be implemented in various different forms and is not limited to the embodiments described herein. The present invention will be further described in conjunction with embodiments. Example 1:

[0018] ① Preparation of ceramic flocs: First, put 1 kg of 1000 mesh fused silica powder and 300 g of 2 mm long short-cut silica fibers into a 40 kg water tank and place the water tank into the water tank of an ultrasonic instrument with a stirrer. Then turn on the stirring and ultrasonic equipment and stop the ultrasonication after running the ultrasonic instrument for 10 minutes and reduce the stirring speed. After the water movement speed decreases, slowly add 50-100 ml of PAC and slowly add PAM 1 minute after the PAC is added. When the fused silica powder and fibers form large flocs, stop stirring and let the flocs settle naturally. ② Drying and Impregnation of Ceramic Flocculants: Drain excess water from the top of the flocculants in the bucket, then transfer the flocculants and spread them evenly in a mold. Use a low-pressure filtration device to extract water from the flocculants. Once the water in the mold stops dripping, place the mold in a 60℃ oven to dry, obtaining loose and dry blocks. Then, place the mold containing the dried blocks into a container filled with silica sol, and immerse the fiber blocks in the silica sol for 30 minutes. Remove the mold and transfer it to a filter press. Press the silica sol-impregnated fiber blocks into plates and dry them in the mold. ③ Sintering of ceramic fiberboard: The dried quartz board is demolded and held at 800℃ for 5 hours to obtain a density of 1.25 g / cm³. 3 High-density, high-strength quartz fiberboard with a compressive strength of up to 30MPa. Example 2:

[0019] ① Preparation of ceramic flocs: First, put 1 kg of 1000 mesh fused silica powder and 500 g of 2 mm long short-cut silica fibers into a 50 kg water tank and place the water tank into the water tank of an ultrasonic instrument with a stirrer. Then turn on the stirring and ultrasonic equipment and stop the ultrasonic instrument after running for 10 minutes and reduce the stirring speed. After the water movement speed decreases, slowly add 50-100 ml of PAC and slowly add PAM 1 minute after the PAC is added. When the fused silica powder and fibers form large flocs, stop stirring and let the flocs settle naturally. ② Drying and Impregnation of Ceramic Flocculants: Drain excess water from the top of the flocculants in the bucket, then transfer the flocculants and spread them evenly in a mold. Use a low-pressure filtration device to extract water from the flocculants. Once the water in the mold stops dripping, place the mold in a 60℃ oven to dry, obtaining loose and dry blocks. Then, place the mold containing the dried blocks into a container filled with silica sol, and immerse the fiber blocks in the silica sol for 30 minutes. Remove the mold and transfer it to a filter press. Press the silica sol-impregnated fiber blocks into plates and dry them in the mold. ③ Sintering of ceramic fiberboard: The dried quartz board is demolded and held at 800℃ for 5 hours to obtain a density of 1.1~1.15 g / cm³. 3High-density, high-strength quartz fiberboard with a compressive strength of up to 25 MPa.

[0020] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a low-expansion, high-strength ceramic fiber board, characterized in that: The preparation method is as follows: a certain proportion of ceramic powder and fiber are mixed in water and dispersed in an ultrasonic device; a flocculant is added and slowly stirred to obtain flocculent clumps; the flocculent clumps are placed in a mold for shaping and separated from the water by a filtration device; the mold containing the flocculent clumps is placed in an oven for drying to obtain loose blocks composed of fiber and ceramic powder; the mold containing the loose blocks is immersed in silica sol and excess silica sol is removed by a pressure filter to obtain a ceramic fiber board; the pressed ceramic fiber board is dried and sintered to finally obtain a high-strength ceramic fiber board.

2. The method for preparing a low-expansion, high-strength ceramic fiber board as described in claim 1, characterized in that: The ceramic powder is fused silica powder with a particle size of 5000 mesh.

3. The method for preparing a low-expansion, high-strength ceramic fiber board as described in claim 1, characterized in that: The fibers are fused silica chopped fibers, chopped carbon fibers, alumina fibers, and aluminum silicate fibers.

4. The method for preparing a low-expansion, high-strength ceramic fiber board as described in claim 3, characterized in that: The fused silica short-cut fibers have a length of 1-5 mm and a density of 1.3 g / cm³. 3 When preparing quartz fiber boards, the chopped fiber length is 1 mm; the density is 1.0 g / cm³. 3 When making quartz fiberboard, the length of the chopped fibers is 5mm.

5. The method for preparing a low-expansion, high-strength ceramic fiber board according to claim 1, characterized in that: The preferred mass ratio of carbon fiber to fused silica powder is 1:10, and the mass ratio of fused silica short chopped fiber, alumina fiber, aluminosilicate fiber to fused silica powder is 3:

10.

6. The method for preparing a low-expansion, high-strength ceramic fiber board according to claim 1, characterized in that: The fused silica powder and fibers are dispersed in water, and the total mass ratio of the fused silica powder and fibers to the mass of the water used to disperse them is 3:

100.

7. The method for preparing a low-expansion, high-strength ceramic fiber board according to claim 1, characterized in that: The flocculant is a 20% aqueous solution of polyaluminum chloride (PAC) and a 2% aqueous solution of anionic polyacrylamide (PAM) and nonionic PAM.

8. The method for preparing a low-expansion, high-strength ceramic fiber board according to claim 7, characterized in that: First, add PAC, and after stirring evenly, add an aqueous solution of anionic polyacrylamide (PAM) and nonionic PAM.

9. The method for preparing a low-expansion, high-strength ceramic fiber board according to claim 1, characterized in that: The pressed board is air-dried in a cool place for 24 hours, then transferred to an oven and dried at 60°C for 24 hours; the sintering temperature is 400~800°C, 800°C for chopped quartz fiber and alumina fiber, and 400°C for chopped carbon fiber.