A self-healing reinforcing agent for ceramic fiber ropes and its preparation method

Abstract

This invention relates to a self-healing reinforcing agent for ceramic fiber ropes, belonging to the field of ceramic material preparation technology. It is made by mixing the following components in the indicated mass percentages, with the addition of 20-40 wt% silica sol and 5-15 wt% water: 40-65 wt% mullite powder, 15-25 wt% alumina micropowder, 2-8 wt% aluminum-silicon alloy powder, 2-10 wt% kyanite powder, 10-16 wt% silica micropowder, 1-5 wt% chopped fiber, 2-5 wt% calcium aluminate cement, 1-3 wt% spherical clay, 0.1-0.3 wt% catalyst, and 0.1-0.3 wt% water-reducing agent. The self-healing reinforcing agent for ceramic fiber ropes and its preparation method of this invention have the advantages of improving the service life of ceramic fiber ropes, mitigating the problem of sealing performance degradation during service, reducing the risk of sealing failure after service of commonly used ceramic fiber ropes, and providing an energy-saving and environmentally friendly preparation process, thereby improving the product's cost-effectiveness and applicability.

Description

Technical Field

[0001] This invention belongs to the field of ceramic material preparation technology, specifically, it is a self-healing reinforcing agent for ceramic fiber ropes and its preparation method. Background Technology

[0002] Ceramic fiber products have functions such as thermal insulation and shock absorption, playing an important role in industrial furnaces and kilns. During long-term use, the surface of ceramic fibers becomes rough, elasticity decreases, and thermal insulation function is reduced. This is because the fine crystals in the fiber products gradually grow or undergo crystal transformation, causing changes in fiber volume. When the growth of fine crystals or the accumulation of crystal transformation reaches a certain extent, the stress generated by the volume change within the fiber increases, leading to fiber breakage or even complete pulverization. In existing research, Chinese patent CN105237001A discloses a dry quenching coke oven castable for in-situ generation of aluminum nitride and its preparation method. The method discloses 45-65 wt% mullite, 15-35 wt% silicon carbide, 2-8 wt% aluminum powder, 0-5 wt% aluminum-silicon alloy powder, 0-2 wt% elemental silicon powder, 4-6 wt% α-alumina micropowder, 2-4 wt% silica micropowder, and 4-6 wt% calcium aluminate cement as raw materials, with 0.1-0.3 wt% catalyst, 0.2-0.5 wt% waterproofing agent, and 0.1-0.3 wt% [other ingredients not specified in the original text]. The water-reducing agent is used as an additive; then, according to the above percentage content, aluminum powder, aluminum-silicon alloy powder, catalyst, and waterproofing agent are premixed to obtain a premix; then, the premix, water-reducing agent, and remaining raw materials are mixed and stirred evenly to obtain a dry-quenching coke oven castable that generates aluminum nitride in situ. Chinese Patent CN 117720338A discloses a refractory castable for trench covers and its preparation method, which uses different components of lightweight mullite, sintered mullite, kyanite, fly ash, activated alumina micro powder, silica fume, calcium aluminate cement, and water-reducing agent to prepare the castable. The above method is usually used as a refractory castable for casting.

[0003] Another method involves spraying a coating onto the surface of ceramic fiber products. This coating protects the ceramic fiber products from direct contact with high temperatures, thereby improving the shape stability and resistance to powdering and peeling, and ultimately extending the lifespan of the fiber products.

[0004] However, such methods are currently commonly used on refractory fiber linings that are not subjected to external forces. Ceramic fiber rope is a type of fiber product that, in addition to the characteristics of conventional ceramic fiber products, also possesses advantages such as high strength, good toughness, and strong plasticity. It is often used in industrial furnaces for curtains or furnace door seals. The working environment of ceramic fiber rope means that it is frequently subjected to compression, alternating hot and cold shocks, etc. Therefore, the aforementioned coatings are not suitable for enhancing the anti-pulverization ability of ceramic fiber rope. Thus, known ceramic fiber products suffer from the aforementioned inconveniences and problems. Summary of the Invention

[0005] The purpose of this invention is to propose a ceramic fiber self-healing reinforcing agent with different raw material types, and more importantly, different raw material particle sizes and functions. The raw material is in fine powder form (particle size less than 0.09 mm), and there is no need to waterproof the aluminum-silicon alloy powder. One purpose is to utilize the gas generated by the hydration reaction of the aluminum-silicon alloy powder (as shown in Formula 1, mainly the reaction between aluminum in the aluminum-silicon alloy and water to generate gas), allowing the pores created by the escaping gas to form a loose structure in the ceramic fiber rope self-healing reinforcing agent, thus facilitating the maintenance of the internal spatial structure of the ceramic fiber rope. Secondly, to maintain the spatial structure of the fiber rope, it is necessary to enable the incompletely hydrated aluminum-silicon alloy powder to generate ceramic fibers under the action of a catalyst within the operating temperature range, achieving self-healing of the fiber rope. Furthermore, there is no need for strict control over the atmospheric environment; that is, the operating atmosphere of the ceramic fiber rope self-healing reinforcing agent in this invention is the same as the operating atmosphere of the fiber rope.

[0006] Al+H2O AlOOH+H2 (Formula 1) Another objective of this invention is to provide a method for preparing a ceramic fiber rope self-healing reinforcing agent that provides a long-lasting sealing effect and reduces the frequency of replacement.

[0007] To achieve the above objectives, the technical solution of the present invention is: A self-healing reinforcing agent for ceramic fiber ropes is made by mixing the following components in the indicated weight percentages, with the addition of 20-40 wt% silica sol and 5-15 wt% water: 40-65 wt% mullite powder, 15-25 wt% alumina micro powder, 2-8 wt% aluminum-silicon alloy powder, 2-10 wt% kyanite powder, 10-16 wt% silica micro powder, 1-5 wt% chopped fiber, 2-5 wt% calcium aluminate cement, 1-3 wt% ball clay, 0.1-0.3 wt% catalyst (added externally), and 0.1-0.3 wt% water-reducing agent (added externally).

[0008] The self-healing and reinforcing ceramic fiber rope of the present invention can also be further realized by the following technical measures.

[0009] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the mullite powder is sintered mullite powder or electrofused mullite powder.

[0010] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the mullite powder has a particle size of ≤0.088mm.

[0011] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the alumina micro powder has a particle size of ≤5μm.

[0012] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the silicon content of the aluminum-silicon alloy powder is ≥2%, and the particle size of the aluminum-silicon alloy powder is ≤0.045mm.

[0013] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the kyanite powder has a particle size ≤0.88mm.

[0014] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the silicon micropowder contains ≥92% SiO2 and has a particle size of ≤0.6μm.

[0015] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the chopped fiber is selected from one or more of chopped alumina ceramic fiber, chopped steel fiber, and chopped mullite fiber.

[0016] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the diameter of the chopped fiber is ≤40μm and the length of the chopped fiber is ≤5mm.

[0017] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the particle size of the ball clay is ≤0.044mm.

[0018] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the catalyst is selected from one or more of nano iron powder, nano nickel powder, and nano cobalt powder.

[0019] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the water-reducing agent is selected from one or more of the inorganic water-reducing agents, such as sodium tripolyphosphate and sodium hexametaphosphate.

[0020] The aforementioned ceramic fiber rope self-healing reinforcing agent, wherein the silica sol is an alkaline silica sol with a SiO2 content of 20-30% and a particle size of ≤580nm.

[0021] A method for preparing a self-healing reinforcing agent for ceramic fiber ropes, characterized by comprising the following steps: a. Alumina micro powder and silicon micro powder are mixed and ball-milled for 6-12 hours to obtain ball milling material; b. Mix the ball milling material and catalyst evenly to obtain a premix; c. Mix the premixed material with the mullite powder, aluminosilicate alloy powder, kyanite powder, chopped fiber, calcium aluminate cement, ball clay and water-reducing agent in the components according to the weight percentage content. d. Add 20-40 wt% silica sol and 5-15 wt% water and stir evenly to obtain a ceramic fiber rope self-healing reinforcing agent.

[0022] After adopting the above technical solution, the ceramic fiber rope self-healing reinforcing agent and its preparation method of the present invention have the following advantages: 1. Improve the service life of ceramic fiber ropes; 2. Improved the sealing performance degradation problem of ceramic fiber rope during service, and reduced the risk of sealing failure of commonly used ceramic fiber rope after service; 3. The preparation process is energy-saving and environmentally friendly, which improves the cost-effectiveness and applicability of the product. Attached Figure Description

[0023] Figure 1 SEM image of the formation of fibers from aluminum-silicon alloy at 1000℃.

[0024] Figure 2 TEM images and energy dispersive spectroscopy analysis of the formation of fibers from aluminum-silicon alloys at 1000℃.

[0025] Figure 3 This is a microstructure photograph of the fiber reinforcing agent of the present invention.

[0026] Figure 4 This is a photograph showing the fiber reinforcing agent of the present invention tightly bonded to the fiber rope.

[0027] Figure 5 Microscopic images of the slurry without aluminum-silicon alloy and fiber.

[0028] Figure 6 Photographs showing the slurry without aluminum-silicon alloy and fiber bonded to the fiber rope and detached. Detailed Implementation

[0029] The present invention will be further illustrated below through specific embodiments. Example

[0030] Using 45wt% mullite powder, 25wt% alumina micro powder, 6wt% alumina-silicon alloy powder, 4wt% kyanite powder, 14wt% silica micro powder, 2wt% chopped fiber, 2wt% calcium aluminate cement, and 2wt% ball clay as raw materials, and 0.1wt% nano-cobalt powder as a catalyst and 0.15wt% sodium tripolyphosphate as a water-reducing agent by weight of the total mass of the above raw materials, the alumina micro powder and silica micro powder are first mixed according to the above percentages and ball-milled for 12 hours to obtain ball milling material. Then, the ball milling material and catalyst are mixed evenly to obtain premix. Finally, the premix is ​​mixed evenly with the mullite powder, alumina-silicon alloy powder, kyanite powder, chopped fiber, calcium aluminate cement, ball clay, and water-reducing agent of the above raw materials according to the percentage content. Then, 25wt% silica sol and 13wt% water are added and stirred evenly to obtain a ceramic fiber rope self-healing reinforcing agent. Among them: Mullite powder is sintered mullite powder; The aluminum-silicon alloy powder contains 12% silicon and has a particle size ≤0.045mm. The silicon micropowder contains ≥92% SiO2 and has a particle size ≤0.6μm; The chopped fibers are chopped steel fibers; The chopped fibers have a diameter of 40μm and a length of 2mm. Example

[0031] Using 52wt% mullite powder, 20wt% alumina micro powder, 4wt% aluminum-silicon alloy powder, 6wt% kyanite powder, 12wt% silica micro powder, 2wt% chopped fiber, 3wt% calcium aluminate cement, and 1wt% ball clay as raw materials, and 0.1wt% nano cobalt powder as catalyst and 0.1wt% sodium tripolyphosphate water-reducing agent as water-reducing agent, the alumina micro powder and silica micro powder were first mixed according to the above percentages and ball-milled for 9 hours to obtain ball milling material. Then, the ball milling material and catalyst were mixed evenly to obtain premix. Finally, the premix was mixed evenly with the mullite powder, aluminum-silicon alloy powder, kyanite powder, chopped fiber, calcium aluminate cement, ball clay, and water-reducing agent of the above raw materials according to the percentage content. Then, 27wt% silica sol and 10wt% water were added and stirred evenly to obtain a ceramic fiber rope self-healing reinforcing agent.

[0032] in: Mullite powder is sintered mullite powder; The aluminum-silicon alloy powder contains 24% silicon and has a particle size ≤0.045mm. The silicon micropowder contains ≥92% SiO2 and has a particle size ≤0.6μm; The chopped fibers are chopped mullite fibers; The chopped fibers have a diameter of 30μm and a length of 3mm. Example

[0033] Using 56 wt% mullite powder, 15 wt% alumina micro powder, 2 wt% aluminum-silicon alloy powder, 9 wt% kyanite powder, 10 wt% silica micro powder, 3 wt% chopped fiber, 4 wt% calcium aluminate cement, and 1 wt% ball clay as raw materials, and 0.1 wt% nano nickel powder as a catalyst and 0.15 wt% sodium tripolyphosphate as a water-reducing agent, the alumina micro powder and silica micro powder were first mixed according to the above percentages and ball-milled for 6 hours to obtain ball milling material. Then, the ball milling material and catalyst were mixed evenly to obtain a premix. Finally, the premix was mixed evenly with the mullite powder, aluminum-silicon alloy powder, kyanite powder, chopped fiber, calcium aluminate cement, ball clay, and water-reducing agent of the above raw materials according to the percentage content. Then, 35 wt% silica sol and 6 wt% water were added and stirred evenly to obtain a ceramic fiber rope self-healing reinforcing agent.

[0034] in: Mullite powder is electrofused mullite powder; The aluminum-silicon alloy powder contains 12% silicon and has a particle size ≤0.045mm. The silicon micropowder contains ≥94% SiO2 and has a particle size ≤0.6μm; The chopped fibers are chopped steel fibers; The chopped fibers have a diameter of 30μm and a length of 3mm.

[0035] This invention possesses substantial features and significant technological advancements. The self-healing reinforcing agent for ceramic fiber ropes and its preparation method utilize the characteristic that aluminum-silicon alloy powder reacts with water to generate bubbles. This allows the self-healing reinforcing agent to bond with the ceramic fiber rope fibers while simultaneously forming a loose internal structure. This not only strengthens the protection of the ceramic fibers within the rope but also helps maintain the internal spatial structure of the ceramic fiber rope. This characteristic can be understood from the chemical formula (Formula 1) of the reaction between aluminum and water in aluminum-silicon alloy powder. This reaction produces gas, which forms bubbles within the material. The escape of these bubbles creates pores, and excessive pores can lead to a porous material. Due to the chemical reaction between aluminum and water, aluminum powder is often added to refractory materials as an anti-explosion agent. The principle is to utilize the pores generated by the reaction to prevent the refractory material from exploding at reference high temperatures. Please refer to the literature Cai Manfei, Nie Jianhua, Yin Guoheng, et al., Influence of different explosion retardants on the performance of corundum-spinel castables [J]. Journal of Ceramics, 2017, 38(6):862-86. However, in order to prevent excessive gas generation from causing the refractory material to become too porous and thus reduce its performance, the amount of aluminum powder added is usually less than 1%. At the same time, since ceramic fiber ropes are usually used for furnace door sealing, the working temperature is generally below 1000℃. Under this temperature condition, it is difficult to use the in-situ generation method to generate fibers in situ to achieve self-repair of ceramic fiber ropes. This invention reduces the fiber generation temperature by adding catalysts and alloy powders, thereby achieving the self-growth of fibers inside the ceramic fiber rope, and achieving the purpose of strengthening the sealing effect of the ceramic fiber rope and extending its service life.

[0036] Furthermore, the addition of chopped fibers can also reinforce ceramic fiber ropes to some extent, improving their toughness and resilience while providing support for other powders in the reinforcing agent. This characteristic is known from GB / T 3003-2017 "Refractory Fibers and Products". In addition, chopped fibers (not limited to ceramic fibers) are a form of toughening for ceramic materials, and the main structure of ceramic fiber ropes is also fiber. Therefore, the chopped fibers added to the self-healing reinforcing agent of ceramic fiber ropes have the same function as the original fibers of the ceramic fiber rope. Based on this, there is theoretical support for the effect of chopped fibers in improving the strength, toughness, and resilience of ceramic fiber ropes, and this effect can be determined even without performance testing.

[0037] Thirdly, based on the functional structure and operating temperature of ceramic fiber ropes, this invention addresses the aging problem that occurs during service by proposing a method to improve their service life by using ceramic fiber rope reinforcing agents for self-repair. Furthermore, it proposes a method for preparing ceramic fiber rope self-repairing reinforcing agents. The above characteristics are due to the fact that the internal fiber growth of the material is suitable for growth in a narrow space. The pores generated by the hydration of aluminum-silicon alloy powder, as well as the fact that the raw materials and ceramic fiber ropes cannot achieve the theoretically complete density, just meet the spatial conditions for fiber growth. Please refer to the literature: Han C, Gu H, Zhang M, et al. Preparation and formation mechanism of Al-Si / Al2O3 core-shell structured particles fabricated via steam corrosion[J].CeramicsInternational, 2019, 45(11) and the literature Han C , Gu H , Zhang M , et al.Al–Si@Al2O3@mullite microcapsules for thermal energy storage: Preparation and thermalproperties[J].Solar Energy Materials and Solar Cells, 2020, 217:110697.DOI:10.1016 / j.solmat.2020.110697. The catalyst works by transforming fiber growth from a GS reaction mechanism to a GLS reaction mechanism, thereby lowering the activation energy for fiber formation. Apparently, this reduces the fiber formation temperature. Please refer to [link to relevant documentation]. Figure 1 and Figure 2 The image shown illustrates the microscopic morphology of fibers formed at 1000℃ from aluminum-silicon alloy. Its principle clearly explains the fiber growth inside the ceramic fiber rope.

[0038] This invention also improves the sealing performance degradation of ceramic fiber ropes during service, reduces the risk of sealing failure after service of commonly used ceramic fiber ropes, and the preparation process is energy-saving and environmentally friendly, thus improving the cost-effectiveness and applicability of the product.

[0039] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of this invention and are defined by the claims.

Claims

1. A self-healing reinforcing agent for ceramic fiber ropes, characterized in that: It is made by mixing the following components in the indicated weight percentages, with the addition of 20-40 wt% silica sol and 5-15 wt% water: 40-65 wt% mullite powder, 15-25 wt% alumina micro powder, 2-8 wt% aluminum-silicon alloy powder, 2-10 wt% kyanite powder, 10-16 wt% silica micro powder, 1-5 wt% chopped fiber, 2-5 wt% calcium aluminate cement, 1-3 wt% spherical clay, 0.1-0.3 wt% catalyst, and 0.1-0.3 wt% water-reducing agent. The mullite powder is sintered mullite powder or electrofused mullite powder; The mullite powder has a particle size of ≤0.088mm; The alumina micro powder has a particle size of ≤5μm; The aluminum-silicon alloy powder has a silicon content of ≥2% and a particle size of ≤0.045mm. The kyanite powder has a particle size ≤ 0.88 mm; The silicon micropowder contains ≥92% SiO2 and has a particle size of ≤0.6μm. The chopped fibers are selected from one or more of chopped alumina ceramic fibers, chopped steel fibers, and chopped mullite fibers; The diameter of the chopped fiber is ≤40μm and the length of the chopped fiber is ≤5mm; The particle size of the spherical clay is ≤0.044mm; The catalyst is selected from one or more of nano-iron powder, nano-nickel powder, and nano-cobalt powder; The water-reducing agent is selected from one or more of sodium tripolyphosphate and sodium hexametaphosphate among inorganic water-reducing agents; The silica sol is an alkaline silica sol with a SiO2 content of 20-30% and a particle size of ≤580nm.

2. The preparation method of the ceramic fiber rope self-healing reinforcing agent as described in claim 1, characterized in that: Includes the following steps: a. Alumina micro powder and silicon micro powder are mixed and ball-milled for 6-12 hours to obtain ball milling material; b. Mix the ball milling material and catalyst evenly to obtain a premix; c. Combine the premix with the mullite powder, aluminosilicate alloy powder, kyanite powder, chopped fibers, calcium aluminate cement, and spheres in the aforementioned components. Clay and water-reducing agent are mixed evenly according to their weight percentage content; d. Add 20-40 wt% silica sol and 5-15 wt% water and stir evenly to obtain a ceramic fiber rope self-healing reinforcing agent.

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