Method for producing and preparing engineering ceramic fiber from calcined kaolin

Abstract

The invention discloses a method for producing and preparing engineering ceramic fiber from calcined kaolin, and belongs to the technical field of ceramic fibers.The method comprises the following steps that raw materials including, by weight, 100-120 parts of calcined kaolin, 55-65 parts of aluminum oxide, 40-50 parts of silicon dioxide and 5-10 parts of reinforcing components are prepared; mixing the calcined kaolin, alumina powder, silicon dioxide and a reinforcing component, and heating and melting to obtain a molten liquid; and performing thread throwing treatment on the molten liquid by a centrifugal machine to obtain a precursor, heating the precursor in a vacuum environment to 1000-1200 DEG C, treating for 2-5 hours, and cooling to room temperature to obtain the engineering ceramic fiber, reinforcing components are introduced in the fiber preparation process, the mechanical property and heat resistance of the engineering ceramic fiber are remarkably improved, the engineering ceramic fiber can be made into fiberboards, special-shaped parts and other products through further processing, and the engineering ceramic fiber is wide in application and broad in prospect in the industries of steel, electric power, petrifaction, heat treatment and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic fibers, and particularly relates to a method for producing and preparing engineering ceramic fibers from calcined kaolin. BACKGROUND

[0002] As an important high-performance fiber material, ceramic fibers have the characteristics of high temperature resistance, corrosion resistance and excellent mechanical properties, and in particular, the thermal stability is far superior to that of high molecular weight high-performance fibers, which can be used at a high temperature of 600-1500 DEG C, and has more excellent anti-thermal-oxidation aging performance, and has become an important raw material for industrial textiles.

[0003] Ceramic fibers are inorganic fibers with excellent high-temperature resistance, oxidation resistance, corrosion resistance and insulation performance. According to the chemical composition, ceramic fibers mainly include quartz fibers, silicon carbide fibers, silicon nitride fibers, boron nitride fibers, alumina fibers, mullite fibers, and aluminum silicate fibers. Among them, the aluminum silicate fiber has the advantages of light weight, high temperature resistance, good thermal stability, low thermal conductivity, small heat capacity, good resistance to mechanical vibration, small thermal expansion, good heat insulation performance, and is widely used. After processing, it can be made into aluminum silicate fiber board, aluminum silicate fiber felt, aluminum silicate fiber rope, aluminum silicate fiber blanket and other products, which is a new type of material to replace asbestos and is widely used in thermal energy equipment of metallurgy, power, machinery and chemical industry.

[0004] At present, the preparation methods of aluminum silicate fibers mainly include high-temperature melting spinning method and sol-gel method. The high-temperature melting spinning method is one of the main methods for preparing aluminum silicate fibers. In this method, kaolin, alumina and silicon dioxide are mixed in a certain proportion and put into an arc furnace or a resistance furnace, and then melted at a high temperature of 2000 DEG C or above to form a stream. The stream is then sprayed by compressed air or steam to form fibers. However, the existing technology has high iron content, titanium content and alkali earth metal oxide content in the kaolin used for preparing aluminum silicate fibers, which leads to poor performance of the aluminum silicate fibers, affecting the service life and product quality. SUMMARY

[0005] The purpose of the present application is to provide a method for producing and preparing engineering ceramic fibers from calcined kaolin, in order to solve the problem of poor performance of aluminum silicate fibers in the prior art.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A method for producing and preparing engineering ceramic fibers from calcined kaolin, comprising the following steps:

[0008] Step (1), prepare the following weight parts of raw materials: calcined kaolin 100-120 parts, alumina 55-65 parts, silicon dioxide 40-50 parts and reinforcing component 5-10 parts;

[0009] Step (2), adding calcined kaolin, alumina powder, silicon dioxide and reinforcing component into an electric arc furnace or a resistance furnace, heating and melting to obtain a molten liquid;

[0010] Step (3), treating the molten liquid by spinning through a centrifuge to obtain a precursor, and placing the precursor in a vacuum environment and heating to 1000-1200℃ for 2-5h, and then cooling to room temperature to obtain the engineering ceramic fiber.

[0011] As a further technical solution of the present application, the reinforcing component is silicon carbide whisker loaded nano lanthanum oxide.

[0012] As a further technical solution of the present application, the preparation method of the reinforcing component comprises the following steps:

[0013] The lanthanum chloride is added into deionized water, stirred uniformly, and then the ammonium sulfate, cetyltrimethylammonium bromide, silicon carbide whisker are added in sequence, ultrasonic treatment is performed for 20-30min, tetramethylammonium hydroxide is added, and ultrasonic treatment is continued for 40min, then it is placed for 2-4h, filtered, the filter cake is repeatedly washed with deionized water and anhydrous ethanol, and tested with silver nitrate solution until no precipitate is generated in the washing liquid, then it is dried at 80℃ for 3-5h, taken out and cooled to room temperature, transferred to a tube resistance furnace under nitrogen protection, calcined at 650℃ for 2h to obtain the reinforcing component.

[0014] As a further technical solution of the present application, the amount ratio of the lanthanum chloride, deionized water, ammonium sulfate, cetyltrimethylammonium bromide, silicon carbide whisker and tetramethylammonium hydroxide is 0.01mol:100mL:0.62-1.25:0.02-0.05g:10-20g:5-6mmol, and the silicon carbide whisker loaded nano lanthanum oxide is prepared as the reinforcing component by a precipitation method, taking the lanthanum chloride and the tetramethylammonium hydroxide as raw materials and the silicon carbide whisker as a carrier, which improves the performance of the aluminum silicate engineering ceramic fiber by virtue of the good temperature resistance and mechanical properties of the silicon carbide whisker.

[0015] As a further technical solution of the present application, the silicon carbide whisker is needle rod-shaped, with a diameter of 0.1-0.6μm, a length of 10-50μm, and an aspect ratio of 15-500, and the silicon carbide whisker with a large aspect ratio is selected, so that the contact area of the obtained reinforcing component and the matrix is larger, the interfacial bonding strength between them is higher, the whisker can consume more energy in the pulling-out process, thereby being more conducive to the exertion of the whisker bridging effect and nucleation effect, and further being more conducive to the improvement of the mechanical properties of the aluminum silicate engineering ceramic fiber.

[0016] As a further technical scheme of the present application, the average particle size of the calcined kaolin is ≤0.5mm, and the element composition is as follows: aluminum content 45-47%, silicon content 51-53%, iron content <0.5%, titanium content <0.4%, and the rest impurities <0.4%. The calcined kaolin is high-quality coal-series kaolin in Huaibei mining area, and after calcination, separation, magnetic separation and screening, the high-quality calcined kaolin particle material is more suitable for melting and calcination.

[0017] As a further technical scheme of the present application, the alumina powder is calcined alpha alumina powder, and the average particle size is 100-200 mesh.

[0018] As a further technical scheme of the present application, the average particle size of the silicon dioxide is 1-20mm.

[0019] As a further technical scheme of the present application, the heating temperature in step (2) is 2100-2300℃, and the molten state is maintained for 45-65min.

[0020] As a further technical scheme of the present application, the rotating speed of the centrifuge in step (3) is 10000-12000r / min.

[0021] As a further technical scheme of the present application, the heating rate in step (3) is 5-10℃ / min, and the cooling rate is 1-5℃ / min.

[0022] As a further technical scheme of the present application, the diameter of the engineering ceramic fiber is 100-120μm.

[0023] The present application has the following beneficial effects:

[0024] 1. The present application provides a method for producing engineering ceramic fiber by calcining kaolin, which uses high-quality calcined kaolin as the main raw material, and cooperates with alumina powder, silicon dioxide and reinforcing components to obtain aluminum silicate engineering ceramic fiber through the melting and spinning process. The reinforcing component is silicon carbide whisker in-situ loaded with nano lanthanum oxide, which is obtained through chemical reaction. Compared with the physical mixture of silicon carbide whisker and nano lanthanum oxide, the dispersion of the nano-reinforced component in the system is better, which is more conducive to obtaining high-performance aluminum silicate engineering ceramic fiber. In addition, the introduction of nano lanthanum oxide can improve the densification and aspect ratio of the mullite phase inside the aluminum silicate engineering ceramic fiber, and obtain interwoven and interlocked mullite grains. Combined with the good temperature resistance and mechanical properties of silicon carbide whisker, the mechanical properties and heat resistance of the aluminum silicate engineering ceramic fiber are significantly improved. Through further processing, the fiber board, special-shaped parts and other products can be made, which are widely used in steel, power, petrochemical, heat treatment and other industries, and have broad prospects.

[0025] 2. The application limits the amount of reinforcing components within a certain range, too low, it is difficult to fully play the role of reinforcement, the performance of the aluminum silicate engineering ceramic fiber is not obvious, too high, the dispersion state of the reinforcing component in the matrix is poor, leading to stress concentration points in the fiber, thereby reducing the tensile strength of the fiber, and increasing the production cost.

[0026] 3. The application limits the ratio of lanthanum chloride and silicon carbide whisker in the preparation process of the reinforcing component, too low, the amount of lanthanum oxide loaded on the surface of the silicon carbide whisker is less, which is difficult to effectively improve the interface bonding performance of the silicon carbide whisker and the aluminum silicate fiber, and also cannot obviously improve the densification of the mullite in the aluminum silicate fiber, too high, the mullite grains abnormally grow, leading to the decrease of the mechanical properties of the aluminum silicate engineering ceramic fiber. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the following embodiments are used to further illustrate the present application. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0028] In the present application, "at least one" means one or more, and "a plurality of" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0029] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0030] It should be understood that in various embodiments of the present application, the size of the sequence number of each process does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0031] The weight of the related components mentioned in the embodiment specification of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the embodiment specification of the present application is scaled up or down in proportion, it is within the scope disclosed in the embodiment specification of the present application. Specifically, the mass mentioned in the embodiment specification of the present application can be μg, mg, g, kg, and other mass units commonly known in the chemical industry.

[0032] Unless otherwise defined, all the professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present application.

[0033] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0034] In order to solve the above problems to some extent, the present application provides a method for producing and preparing engineering ceramic fiber from calcined kaolin, comprising the following steps:

[0035] Step (1), prepare the following weight parts of raw materials: calcined kaolin 100-120 parts, alumina 55-65 parts, silicon dioxide 40-50 parts and reinforcing component 5-10 parts;

[0036] Step (2), add calcined kaolin, alumina powder, silicon dioxide and reinforcing component into an electric arc furnace or electric resistance furnace, heat and melt to obtain a molten liquid;

[0037] Step (3), the molten liquid is treated by spinning in a centrifuge to obtain a raw silk, and the raw silk is heated to 1000-1200℃ in a vacuum environment for 2-5h, and then cooled to room temperature to obtain the engineering ceramic fiber.

[0038] In some specific embodiments, the reinforcing component is silicon carbide whisker loaded with nano lanthanum oxide.

[0039] In some specific embodiments, the preparation method of the reinforcing component comprises the following steps:

[0040] The lanthanum chloride is added into the deionized water, stirred uniformly, and then the ammonium sulfate, the cetyltrimethylammonium bromide, the silicon carbide whisker are added in sequence, ultrasonic treatment is carried out for 20-30 min, the tetramethylammonium hydroxide is added, and ultrasonic treatment is continued for 40 min, then the mixture is placed for 2-4 h, filtered, the filter cake is washed repeatedly with the deionized water and the anhydrous ethanol, and the washing liquid is tested with the silver nitrate solution until no precipitate is generated, then the filter cake is dried at 80℃ for 3-5 h, taken out, cooled to room temperature, transferred to a tube resistance furnace under the protection of nitrogen, calcined at 650℃ for 2 h, and the reinforcing component is obtained.

[0041] In some specific embodiments, the use amount ratio of the lanthanum chloride, the deionized water, the ammonium sulfate, the cetyltrimethylammonium bromide, the silicon carbide whisker and the tetramethylammonium hydroxide is 0.01 mol:100 mL:0.02-0.05 g:0.62-1.25 g:10-20 g:5-6 mmol, and the silicon carbide whisker loaded nano lanthanum oxide as the reinforcing component is prepared by a precipitation method, with the lanthanum chloride and the tetramethylammonium hydroxide as raw materials and the silicon carbide whisker as a carrier, so that the performance of the aluminum silicate engineering ceramic fiber is improved by virtue of the good temperature resistance and mechanical properties of the silicon carbide whisker.

[0042] In some specific embodiments, the silicon carbide whisker is needle rod-shaped, with a diameter of 0.1-0.6 μm, a length of 10-50 μm, and an aspect ratio of 15-500, so that the contact area between the obtained reinforcing component and the matrix is larger, the interfacial bonding strength between them is higher, the whisker can consume more energy in the pulling-out process, and thus the whisker bridging effect and nucleation effect are more likely to be exerted, and the improvement of the mechanical properties of the aluminum silicate engineering ceramic fiber is more favorable.

[0043] In some specific embodiments, the average particle size of the calcined kaolin is ≤0.5 mm, and the element composition is as follows: the aluminum content is 45-47%, the silicon content is 51-53%, the iron content is <0.5%, the titanium content is <0.4%, and the remaining impurities are <0.4%, the calcined kaolin is a high-quality coal measure kaolin in Huaibei mining area, and the high-quality calcined kaolin particle material after calcination, separation, magnetic separation and screening is more suitable for melting and calcination.

[0044] In some specific embodiments, the average particle size of the alumina powder is 100-200 mesh.

[0045] In some specific embodiments, the average particle size of the silicon dioxide is 1-20 mm.

[0046] In some embodiments, the heating temperature in step (2) is 2100-2300℃, and the molten state is maintained for 45-65 min.

[0047] In some embodiments, the speed of the centrifuge in step (3) is 10000-12000r / min.

[0048] In some embodiments, the heating rate in step (3) is 5-10℃ / min, and the cooling rate is 1-5℃ / min.

[0049] In some embodiments, the diameter of the engineering ceramic fiber is 100-120μm.

[0050] The technical solutions of the present application are illustrated below by specific examples and comparative examples.

[0051] Example 1

[0052] A method for producing engineering ceramic fibers from calcined kaolin, comprising the following steps:

[0053] Step (1), prepare the following raw materials by weight: calcined kaolin 100 parts, alumina 55 parts, silicon dioxide 40 parts, and reinforcing component 5 parts;

[0054] Step (2), add the calcined kaolin, alumina powder, silicon dioxide, and reinforcing component into an electric arc furnace or a resistance electric furnace, heat and melt to obtain a molten liquid;

[0055] Step (3), spin the molten liquid through a centrifuge to obtain a precursor fiber, place the precursor fiber in a vacuum environment and heat to 1000℃ for 5h, then cool to room temperature to obtain the engineering ceramic fiber.

[0056] The method for preparing the reinforcing component, comprising the following steps:

[0057] Add 0.01mol lanthanum chloride into 100mL deionized water, stir uniformly, and then add 0.62g ammonium sulfate, 0.02g cetyltrimethylammonium bromide, and 10g silicon carbide whiskers successively, ultrasonic treatment for 20min, add 5mmol tetramethylammonium hydroxide, continue ultrasonic treatment for 40min, then stand for 2h, filter, and repeatedly wash the filter cake with deionized water and anhydrous ethanol, and test with silver nitrate solution until no precipitate is generated in the washing liquid, then dry at 80℃ for 3h, take out and cool to room temperature, transfer to a tube resistance furnace under nitrogen protection, calcine at 650℃ for 2h to obtain the reinforcing component.

[0058] The silicon carbide whisker is needle-like, with a diameter of 0.1-0.6μm, a length of 10-50μm, and an aspect ratio of 15-500.

[0059] The average particle size of the calcined kaolin is ≤0.5mm, and the elemental composition is as follows: aluminum content 45-47%, silicon content 51-53%, iron content <0.5%, titanium content <0.4%, and the rest impurities <0.4%.

[0060] The alumina powder is calcined α-alumina powder with an average particle size of 100-200 mesh.

[0061] The average particle size of the silica is 1-20 mm.

[0062] The heating temperature in step (2) is 2100°C, and the molten state is maintained for 65 min.

[0063] The rotation speed of the centrifuge in step (3) is 10000 r / min.

[0064] The heating rate in step (3) is 5°C / min, and the cooling rate is °C / min.

[0065] The diameter of the engineering ceramic fiber is 100 μm.

[0066] Example 2

[0067] A method for producing an engineering ceramic fiber from calcined kaolin, comprising the following steps:

[0068] Step (1), preparing the following raw materials by weight: calcined kaolin 110 parts, alumina 60 parts, silica 45 parts, and reinforcing component 8 parts;

[0069] Step (2), adding the calcined kaolin, alumina powder, silica, and reinforcing component into an electric arc furnace or a resistance electric furnace, and heating and melting to obtain a molten liquid;

[0070] Step (3), spinning the molten liquid through a centrifuge to obtain a raw fiber, and heating the raw fiber to 1100°C in a vacuum environment for 4 h, and then cooling to room temperature to obtain the engineering ceramic fiber.

[0071] The reinforcing component is prepared in the same manner as in Example 1.

[0072] The alumina powder is calcined α-alumina powder with an average particle size of 100-200 mesh.

[0073] The average particle size of the silica is 1-20 mm.

[0074] The heating temperature in step (2) is 2200°C, and the molten state is maintained for 60 min.

[0075] The rotation speed of the centrifuge in step (3) is 11000 r / min.

[0076] The heating rate in step (3) is 8°C / min, and the cooling rate is 3°C / min.

[0077] The diameter of the engineering ceramic fiber is 110 μm.

[0078] Example 3

[0079] A method for producing engineering ceramic fibers from calcined kaolin, comprising the following steps:

[0080] Step (1), preparing the following raw materials by weight: calcined kaolin 120 parts, alumina 65 parts, silica 50 parts, and reinforcing component 10 parts;

[0081] Step (2), adding the calcined kaolin, alumina powder, silica, and reinforcing component into an electric arc furnace or a resistance electric furnace, and heating and melting to obtain a molten liquid;

[0082] Step (3), processing the molten liquid by spinning through a centrifuge to obtain a raw fiber, and placing the raw fiber in a vacuum environment and heating to 1200℃ for 2h, and then cooling to room temperature to obtain the engineering ceramic fiber.

[0083] The reinforcing component is prepared according to the process of Example 1.

[0084] The alumina powder is calcined α-alumina powder with an average particle size of 100-200 mesh.

[0085] The average particle size of the silica is 1-20mm.

[0086] The heating temperature in Step (2) is 2300℃, and the molten state is maintained for 45min.

[0087] The rotation speed of the centrifuge in Step (3) is 12000r / min.

[0088] The heating rate in Step (3) is 10℃ / min, and the cooling rate is 5℃ / min.

[0089] The diameter of the engineering ceramic fiber is 120μm.

[0090] Example 4

[0091] A method for producing engineering ceramic fibers from calcined kaolin, compared with Example 1, the only difference is that the preparation process of the reinforcing component is different, and in this example, the preparation process of the reinforcing component is as follows:

[0092] 0.01 mol of lanthanum chloride was added into 100 mL of deionized water, and 0.62 g of ammonium sulfate, 0.02 g of cetyltrimethylammonium bromide and 20 g of silicon carbide whiskers were added in sequence under stirring, and ultrasonic treatment was performed for 20 min, 5.5 mmol of tetramethylammonium hydroxide was added, and ultrasonic treatment was continued for 40 min, and then the mixture was left to stand for 2 h, and then filtration was performed, the filter cake was repeatedly washed with deionized water and anhydrous ethanol, and the washing liquid was tested with silver nitrate solution until no precipitate was generated, and then the filter cake was dried at 80°C for 3 h, and then the filter cake was cooled to room temperature, and then the filter cake was transferred into a tube resistance furnace under nitrogen protection, and calcination was performed at 650°C for 2 h, and then the reinforcing component was obtained.

[0093] The silicon carbide whisker is needle rod-shaped, has a particle size of 0.5-2.5 μm, and has an aspect ratio of 15-500.

[0094] Example 5

[0095] A method for producing engineering ceramic fibers by calcining kaolin, which is different from example 1 only in that the preparation process of the reinforcing component is different, and in this example, the preparation process of the reinforcing component is as follows:

[0096] 0.01 mol of lanthanum chloride was added into 100 mL of deionized water, and 0.62 g of ammonium sulfate, 0.02 g of cetyltrimethylammonium bromide and 20 g of silicon carbide whiskers were added in sequence under stirring, and ultrasonic treatment was performed for 20 min, 5.5 mmol of tetramethylammonium hydroxide was added, and ultrasonic treatment was continued for 40 min, and then the mixture was left to stand for 2 h, and then filtration was performed, the filter cake was repeatedly washed with deionized water and anhydrous ethanol, and the washing liquid was tested with silver nitrate solution until no precipitate was generated, and then the filter cake was dried at 80°C for 3 h, and then the filter cake was cooled to room temperature, and then the filter cake was transferred into a tube resistance furnace under nitrogen protection, and calcination was performed at 650°C for 2 h, and then the reinforcing component was obtained.

[0097] The silicon carbide whisker is needle rod-shaped, has a particle size of 0.5-2.5 μm, and has an aspect ratio of 15-500.

[0098] Example 6

[0099] A method for producing engineering ceramic fibers by calcining kaolin, which is different from example 1 only in that the preparation process of the reinforcing component is different, and in this example, the preparation process of the reinforcing component is as follows:

[0100] LaCl3 0.01 mol was added into 100 mL of deionized water and stirred uniformly, 1.25 g of ammonium sulfate, 0.05 g of cetyltrimethylammonium bromide, and 10 g of silicon carbide whiskers were added in sequence, and ultrasonic treatment was performed for 30 min. 6 mmol of tetramethylammonium hydroxide was added, and ultrasonic treatment was continued for 40 min. After that, the mixture was left to stand for 4 h, and then filtered. The filter cake was repeatedly washed with deionized water and anhydrous ethanol, and tested with a silver nitrate solution until no precipitate was generated in the washing liquid. After that, the mixture was dried at 80°C for 5 h, and then transferred to a tube resistance furnace after being cooled to room temperature under nitrogen protection. Calcination was performed at 650°C for 2 h to obtain the reinforcing component.

[0101] The silicon carbide whiskers are needle rods with a particle size of 0.5-2.5 μm and an aspect ratio of 15-500.

[0102] Example 7

[0103] A method for producing engineering ceramic fibers from calcined kaolin, which differs from Example 1 only in that step (1) is different. In this example, step (1) is as follows:

[0104] The following raw materials were prepared in parts by weight: calcined kaolin 100 parts, alumina 55 parts, silicon dioxide 40 parts, and reinforcing component 10 parts.

[0105] Example 8

[0106] A method for producing engineering ceramic fibers from calcined kaolin, which differs from Example 1 only in that step (1) is different. In this example, step (1) is as follows:

[0107] The following raw materials were prepared in parts by weight: calcined kaolin 120 parts, alumina 65 parts, silicon dioxide 50 parts, and reinforcing component 5 parts.

[0108] Comparative Example 1

[0109] A method for producing engineering ceramic fibers from calcined kaolin, which differs from Example 1 only in that the "reinforcing component" in Example 1 is replaced with an equal weight of "a product obtained by stirring 3.26 g of nanometer-sized lanthanum oxide and 10 g of silicon carbide whiskers in a stirrer at 200 r / min for 30 min". The silicon carbide whiskers are the same as in Example 1.

[0110] Comparative Example 2

[0111] A method for producing engineering ceramic fibers from calcined kaolin, which differs from Example 1 only in that the silicon carbide whiskers in Example 1 are different. In this comparative example, the silicon carbide whiskers are needle rods with a diameter of 5-10 μm and a length of 50-100 μm, and an aspect ratio of 5-20.

[0112] Comparative Example 3

[0113] A method for producing engineering ceramic fibers by calcining kaolin, which is different from example 7 only in that the weight parts of the reinforcing component in example 7 are adjusted from "10 parts" to "15 parts".

[0114] Comparative example 4

[0115] A method for producing engineering ceramic fibers by calcining kaolin, which is different from example 8 only in that the weight parts of the reinforcing component in example 8 are adjusted from "5 parts" to "1 part".

[0116] Comparative example 5

[0117] A method for producing engineering ceramic fibers by calcining kaolin, which is different from example 4 only in that the amount of lanthanum chloride in example 4 is adjusted from "0.01 mol" to "0.005 mol".

[0118] Comparative example 6

[0119] A method for producing engineering ceramic fibers by calcining kaolin, which is different from example 6 only in that the amount of lanthanum chloride in example 6 is adjusted from "0.01 mol" to "0.015 mol".

[0120] The engineering ceramic fibers obtained in examples 1-8 and comparative examples 1-6 are subjected to heat setting in a hot furnace after being collected and needled, the heat setting temperature is 750°C, the heat setting time is 35 min, and a fiber cotton with a size of 500mm x 460mm x 240mm is obtained, after which the fiber cotton is tested, the slag ball content is tested according to GB / T5480, the permanent linear change after heating is tested according to GB / T17911, and the tensile strength is tested according to GB / T17911;

[0121] The test results are shown in Table 1:

[0122] Table 1

[0123]

[0124]

[0125] From the data recorded in Table 1, it can be seen that the fiber cotton prepared from the engineering ceramic fibers of Examples 1-8 has a >0.212 mm ball content of 6.3-7.1%, a permanent linear shrinkage after heating (1000℃*24h) of 0.3-0.8%, and a tensile strength of 78-90kPa. As can be seen from the test results of Example 1 and Comparative Example 1, when the same amount of nano lanthanum oxide and silicon carbide whiskers are used to replace the reinforcing component in the present case, the ball content of the fiber cotton increases, and the heat resistance and mechanical properties significantly decrease. As can be seen from the test results of Example 1 and Comparative Example 2, using silicon carbide whiskers with a large aspect ratio is more conducive to obtaining high-performance engineering ceramic fibers. As can be seen from the tests of Example 7 and Comparative Example 3, Example 8 and Comparative Example 4, the content of the reinforcing component in the system must be appropriate, and too much or too little is not conducive to obtaining high-performance engineering ceramic fibers. As can be seen from the test results of Example 4 and Comparative Example 5, Example 6 and Comparative Example 6, the ratio of lanthanum chloride and silicon carbide whiskers during the preparation of the reinforcing component should be moderate, and too low or too high a content of lanthanum chloride will result in a decrease in the mechanical properties of the aluminum silicate engineering ceramic fibers.

[0126] It should be noted that the relational terms herein such as first and second, and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprising", "including", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0127] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for producing engineering ceramic fibers from calcined kaolin, characterized in that, The method comprises the following steps: Step (1), preparing the following raw materials by weight: calcined kaolin 100-120 parts, alumina 55-65 parts, silicon dioxide 40-50 parts, and a reinforcing component 5-10 parts; Step (2), mixing the calcined kaolin, alumina powder, silicon dioxide, and the reinforcing component, and heating and melting to obtain a molten liquid; Step (3), spinning the molten liquid through a centrifuge to obtain a raw fiber, and heating the raw fiber to 1000-1200℃ in a vacuum environment for 2-5h, and then cooling to room temperature to obtain the engineering ceramic fiber; The reinforcing component is a silicon carbide whisker loaded with nano lanthanum oxide.

2. A method of producing engineered ceramic fibers from calcined kaolin according to claim 1, characterized in that, The preparation method of the reinforcing component comprises the following steps: The lanthanum chloride is added to deionized water, stirred uniformly, and then the ammonium sulfate, cetyltrimethylammonium bromide, and silicon carbide whisker are sequentially added, ultrasonic treatment is performed for 20-30min, tetramethylammonium hydroxide is added, and ultrasonic treatment is continued for 40min, then the mixture is left to stand for 2-4h, filtered, the filter cake is washed and dried, and calcination is performed at 650℃ for 2h to obtain the reinforcing component.

3. A method of producing engineered ceramic fibers from calcined kaolin according to claim 2, characterized in that, The amount ratio of the lanthanum chloride, deionized water, ammonium sulfate, cetyltrimethylammonium bromide, silicon carbide whisker, and tetramethylammonium hydroxide is 0.01mol:100mL:0.62-1.25:0.02-0.05g:10-20g:5-6mmol.

4. A method of producing engineered ceramic fibers from calcined kaolin according to claim 2, characterized in that, The silicon carbide whisker is needle-like, and the aspect ratio is 15-500.

5. The method for producing engineering ceramic fibers from calcined kaolin according to claim 1, characterized in that, The average particle size of the calcined kaolin is ≤0.5mm, and the elemental composition is as follows: aluminum content 45-47%, silicon content 51-53%, iron content <0.5%, titanium content <0.4%, and the rest impurities <0.4%.

6. A method of producing engineered ceramic fibers from calcined kaolin according to claim 1, characterized in that, The alumina powder is a calcined alpha alumina powder, and the average particle size is 100-200 mesh.

7. A method of producing engineered ceramic fibers from calcined kaolin according to claim 1, characterized in that, The average particle size of the silicon dioxide is 1-20mm.

8. A method of producing engineered ceramic fibers from calcined kaolin according to claim 1, characterized in that, The heating temperature in step (2) is 2100-2300℃, and the molten state is maintained for 45-65min.

9. The method for producing engineering ceramic fibers from calcined kaolin according to claim 1, characterized in that, The rotating speed of the centrifuge in step (3) is 10000-12000r / min.

10. The method for producing engineering ceramic fibers from calcined kaolin according to claim 1, characterized in that, The heating rate in step (3) is 5-10℃ / min, and the cooling rate is 1-5℃ / min.

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