Low water demand siliceous hot mix and method of making same

Abstract

The application relates to the technical field of refractory materials for coke ovens, and discloses a low-water-content siliceous hot-patching material and a preparation method thereof, which comprises the following raw materials in parts by mass: fused quartz 50-65 parts, silica 30-40 parts, waste silica brick 10-20 parts, composite additive 6-10 parts, mineralizer 3-6 parts, binding agent 4-10 parts, sintering agent 3-5 parts, water reducing agent 0.5-1 part and water 10-15 parts. The siliceous hot-patching material prepared by adopting fused quartz, silica and waste silica brick as main raw materials and adding a mineralizer, a binding agent, a sintering agent and a water reducing agent has excellent construction performance, and after hardening, has the advantages of high bulk density, low porosity and high strength; and during the repairing process of the siliceous hot-patching material, the material has low porosity, low water demand and high high-temperature strength.

Description

Technical Field

[0001] This invention relates to the field of refractory materials for coke ovens, specifically to a low-water-demand siliceous heat-replenishing material and its preparation method. Background Technology

[0002] The coke oven carbonization chamber is a major component of a coke oven. Damage to the carbonization chamber walls is mainly caused by a combination of factors, including thermal stress resulting from rapid temperature changes during coal charging and coke discharging, mechanical impact, compression, friction, and erosion from harmful substances in the coal gas. Damage to the carbonization chamber leads to coal gas leakage, environmental pollution, wall erosion, and reduced service life. Silica-based hot-pressing refractory is a commonly used hot-pressing refractory material, primarily used for rapid hot-pressing repairs of high-temperature kilns constructed with silica bricks (such as coke oven heads and carbonization chamber walls). Its working principle involves the reaction of silica in the material with a coagulant under high-temperature steam to form a hydrated silicate gel, which then rapidly hardens to generate strength.

[0003] Using fused silica, silica, and waste silica bricks as the main raw materials, and adding mineralizers, binders, sintering agents, and water-reducing agents, the prepared silica-based heat repair material has excellent construction performance and, after hardening, has the advantages of high bulk density, low porosity, and high strength. However, during the repair process, the bulk density of the silica-based heat repair material decreases and the porosity increases, resulting in a higher water demand and the formation of more capillary channels inside, which reduces the high-temperature strength of the material. Summary of the Invention

[0004] This invention provides a low-water-demand silica-based thermal repair material and its preparation method, which solves the problem that during the repair process of silica-based thermal repair materials, the material's bulk density decreases and porosity increases, resulting in a high water demand and the formation of numerous capillary channels inside.

[0005] The technical solution of this invention: A low-water-demand silica-based heat-repairing material comprises the following raw materials in parts by weight: 50-65 parts fused silica, 30-40 parts silica, 10-20 parts waste silica bricks, 6-10 parts composite additives, 3-6 parts mineralizer, 4-10 parts binder, 3-5 parts sintering agent, 0.5-1 part water-reducing agent, and 10-15 parts water. The composite additive is obtained by mixing and reacting modified carbon fiber with stearic acid, and then mixing and reacting it with polyvinyl alcohol fiber and oleic acid. The modified carbon fiber is obtained by modifying the surface of carbon fiber with tannic acid and then depositing nano-calcium carbonate in situ. A method for preparing a low-water-demand silica-based heat filler material includes the following preparation steps: Fused silica, silica, waste silica bricks, composite additives, mineralizers, binders, sintering agents, water-reducing agents, and water are mixed evenly and stirred at 100-150 r / min for 15-20 min to obtain a low-water-requirement silica thermal feedstock.

[0006] Furthermore, the fused silica particle size is 0.05-0.1 mm.

[0007] Furthermore, the silica particle size is 310-330 mesh.

[0008] Furthermore, the particle size of the waste silica bricks is 240-300 mesh.

[0009] Furthermore, the mineralizing agent is nano-sized iron oxide with a particle size of 100-150 nm.

[0010] Furthermore, the water-reducing agent is selected from any one of naphthalene-based water-reducing agents, sodium tripolyphosphate, and sodium hexametaphosphate.

[0011] Furthermore, the sintering agent is selected from any one of clay, bentonite, and alumina.

[0012] Furthermore, the binder is selected from sodium metasilicate nonahydrate or sodium metasilicate pentahydrate.

[0013] Furthermore, the composite additive is prepared by the following steps: A1. Add carbon fiber and tannic acid to ethanol, stir, filter, wash, and dry to obtain tannic acid modified carbon fiber; A2. Add calcium chloride to deionized water and stir until completely dissolved. Add tannic acid-modified carbon fiber, stir, add ammonia to adjust the pH, place in a reaction vessel, and pass carbon dioxide and air through. After the reaction, filter to collect the solid, dry, and obtain carbon fiber loaded with calcium carbonate particles. A3. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir, add stearic acid, continue stirring and reacting, filter, wash, and dry to obtain modified carbon fiber; A4. Polyvinyl alcohol fiber and oleic acid are added to ethanol and stirred evenly. Hydrochloric acid is added to adjust the pH. After the reaction is complete, modified carbon fiber is added and the mixture is stirred and mixed. After filtration, washing and drying, a composite additive is obtained.

[0014] Furthermore, in the A1 reaction process described above, tannic acid is used to modify the carbon fiber surface. Tannic acid contains a large number of phenolic hydroxyl groups, which have high adhesion properties and can adhere to the carbon fiber surface, giving the carbon fiber a large number of polar functional groups, thus obtaining tannic acid-modified carbon fiber.

[0015] Furthermore, in the A2 reaction process described above, the phenolic hydroxyl groups in the tannic acid-modified carbon fibers can combine with calcium ions in calcium chloride, causing calcium ions to deposit on the carbon fiber surface. After introducing carbon dioxide and air, a carbonization reaction occurs, forming calcium carbonate crystals on the carbon fiber surface. As the reaction proceeds, the contained NH4+... + It can combine with hydroxyl groups on the surface of calcium carbonate crystals, promoting the aggregation and growth of calcium carbonate crystals, thereby forming calcium carbonate particles on the surface of carbon fibers and obtaining carbon fibers loaded with calcium carbonate particles.

[0016] Furthermore, during the A3 reaction process described above, the calcium carbonate particles on the surface of the carbon fiber loaded with calcium carbonate particles undergo a hydrolysis reaction, and the hydrolysis reaction occurs on the outermost layer of calcium carbonate. This allows the calcium ions contained in the outer layer of calcium carbonate particles to react with the carboxyl groups of stearic acid to form calcium stearate, thereby introducing a calcium stearate layer onto the surface of the carbon fiber loaded with calcium carbonate particles and forming modified carbon fiber.

[0017] Furthermore, in the A4 reaction process described above, oleic acid acts as a crosslinking agent. The carboxyl groups in oleic acid can chemically bond with the hydroxyl groups on the surface of polyvinyl alcohol fibers, allowing oleic acid to be grafted onto the polyvinyl alcohol fibers. In addition, the long-chain alkane structure in oleic acid can intertwine with the hydrophobic stearic acid chains on the surface of the modified carbon fibers, so that the modified carbon fibers and polyvinyl alcohol fibers form a crosslinked network structure through oleic acid, resulting in a composite additive.

[0018] Further, in step A1, the mass ratio of carbon fiber, tannic acid and ethanol is (1.5-2):(1-1.3):(70-80).

[0019] Furthermore, in step A2, the mass ratio of calcium chloride, deionized water, and tannic acid-modified carbon fibers is (7.5-8):(80-85):(3-3.5).

[0020] Further, in step A3, the mass ratio of carbon fiber loaded with calcium carbonate particles, deionized water and stearic acid is (3.3-3.8):(90-110):(1.5-2).

[0021] Further, in step A4, the mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber is (2.5-2.8):(1.1-1.3):(80-90):(3.5-4).

[0022] The present invention has the following beneficial effects: (1) In the technical solution of the present invention, carbon fiber is modified with tannic acid to give carbon fiber a large number of polar functional groups, which is beneficial to synthesize a large number of nano calcium carbonate particles on the surface of carbon fiber. Nano calcium carbonate can fill the pores of siliceous heat filler, making the siliceous heat filler more compact and reducing the amount of water required to fill the pores, thereby further reducing the total water requirement without sacrificing workability.

[0023] (2) In the technical solution of the present invention, calcium carbonate particles are formed on the surface of carbon fiber. On the one hand, carbon fiber can form a three-dimensional network structure inside the siliceous heat filler, which can absorb and weaken the energy generated by the impact, reduce the expansion of cracks in the siliceous heat filler, and have high compressive strength. Moreover, as a carrier of calcium carbonate particles, carbon fiber can improve the dispersion of calcium carbonate particles in the siliceous heat filler, making the siliceous heat filler more compact, reducing the porosity, and thus reducing the amount of water required to fill the pores. On the other hand, when the material is subjected to force or thermal shock and cracks are generated, carbon fiber and calcium carbonate particles can also bridge the microcracks, prevent the cracks from expanding, and improve the compressive strength of the material.

[0024] (3) In the technical solution of the present invention, a calcium stearate layer is introduced on the surface of the carbon fiber loaded with calcium carbonate particles. The hydrophobic chains contained in the formed calcium stearate layer can penetrate into the capillary pores of the silica heat filler, reduce the porosity, reduce the amount of water required to fill the pores, and increase the bonding strength between the carbon fiber loaded with calcium carbonate particles and the silica heat filler. This prevents the carbon fiber from slipping relative to the silica heat filler when it is subjected to external force, thus reducing the performance of the silica heat filler.

[0025] (4) In the technical solution of the present invention, the modified carbon fiber and polyvinyl alcohol fiber form a cross-linked network structure through oleic acid. On the one hand, the silica heat repair material can fill into the cross-linked network structure, improve the density of the silica heat repair material, reduce the porosity, and thus reduce the amount of water required to fill the pores. On the other hand, the formed cross-linked network structure can absorb and weaken the energy generated by the impact force, and enhance the compressive strength of the silica heat repair material. In addition, polyvinyl alcohol fiber can also bridge microcracks and prevent the expansion of cracks. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0028] The fused silica has a particle size of 0.08 mm; the silica has a particle size of 320 mesh; the waste silica brick has a particle size of 280 mesh; and the mineralizer is nano-sized iron oxide with a particle size of 130 nm.

[0029] The water-reducing agent is sodium tripolyphosphate, and the sintering agent is alumina (D). 50 The particle size is 5 μm, and the binder is sodium metasilicate nonahydrate.

[0030] The carbon fiber has a diameter of 200 nm and a length of 10 µm.

[0031] The polyvinyl alcohol fiber has a diameter of 200 nm and a length of 10 µm.

[0032] Example 1 A low-water-demand silica-based heat repair material comprises the following raw materials in parts by weight: 50 parts fused silica, 30 parts silica, 10 parts waste silica bricks, 6 parts composite additives, 3 parts nano-grade iron oxide, 4 parts sodium metasilicate nonahydrate, 3 parts alumina, 0.5 parts sodium tripolyphosphate, and 10 parts water. A method for preparing a low-water-demand silica-based heat filler material includes the following preparation steps: Fused silica, silica, waste silica bricks, composite additives, nano-sized iron oxide, sodium metasilicate nonahydrate, alumina, sodium tripolyphosphate, and water are mixed evenly and stirred at 100 r / min for 15 min to obtain a low-water-requirement silica thermal feedstock.

[0033] The composite additive is prepared by the following steps: A1. Carbon fiber and tannic acid were added to ethanol and stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain tannic acid-modified carbon fiber. The mass ratio of carbon fiber, tannic acid and ethanol was 1.5:1:70. A2. Calcium chloride was added to deionized water and stirred until completely dissolved. Tannic acid-modified carbon fibers were added and stirred for 10 min. Ammonia water with a mass fraction of 30% was added to adjust the pH to 8. The mixture was placed in a reaction vessel, and carbon dioxide and air (volume ratio of carbon dioxide to air of 1:3) were introduced at a rate of 25 mL / min. The reaction was carried out at 30 °C for 2 h. The solid was collected by filtration and dried in an oven at 105 °C for 20 min to obtain carbon fibers loaded with calcium carbonate particles. The mass ratio of calcium chloride, deionized water, and tannic acid-modified carbon fibers was 7.5:80:3. A3. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir in a 35°C water bath for 12 min, add stearic acid, continue stirring for 30 min, filter, wash three times with deionized water, and dry overnight in a 110°C oven to obtain modified carbon fiber; the mass ratio of carbon fiber loaded with calcium carbonate particles, deionized water and stearic acid is 3.3:90:1.5. A4. Polyvinyl alcohol fiber and oleic acid were added to ethanol and stirred evenly. Hydrochloric acid with a concentration of 2 mol / L was added to adjust the pH to 3. The mixture was stirred at 70℃ for 20 min. Modified carbon fiber was added and the mixture was stirred and mixed for another 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70℃ for 10 min to obtain the composite additive. The mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber was 2.5:1.1:80:3.5.

[0034] Example 2 A low-water-demand silica-based heat repair material comprises the following raw materials in parts by weight: 60 parts fused silica, 35 parts silica, 15 parts waste silica bricks, 8 parts composite additives, 5 parts nano-grade iron oxide, 8 parts sodium metasilicate nonahydrate, 4 parts alumina, 0.8 parts sodium tripolyphosphate, and 12 parts water. A method for preparing a low-water-demand silica-based heat filler material includes the following preparation steps: Fused silica, silica, waste silica bricks, composite additives, nano-sized iron oxide, sodium metasilicate nonahydrate, alumina, sodium tripolyphosphate and water are mixed evenly and stirred at 130 r / min for 18 min to obtain a low water requirement silica thermal feedstock.

[0035] The composite additive is prepared by the following steps: A1. Carbon fiber and tannic acid were added to ethanol and stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain tannic acid-modified carbon fiber. The mass ratio of carbon fiber, tannic acid and ethanol was 1.8:1.2:75. A2. Calcium chloride was added to deionized water and stirred until completely dissolved. Tannic acid-modified carbon fibers were added and stirred for 10 min. Ammonia water with a mass fraction of 30% was added to adjust the pH to 8. The mixture was placed in a reaction vessel, and carbon dioxide and air (volume ratio of carbon dioxide to air of 1:3) were introduced at a rate of 25 mL / min. The reaction was carried out at 30 °C for 2 h. The solid was collected by filtration and dried in an oven at 105 °C for 20 min to obtain carbon fibers loaded with calcium carbonate particles. The mass ratio of calcium chloride, deionized water, and tannic acid-modified carbon fibers was 7.8:83:3.3. A3. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir in a 35°C water bath for 12 min, add stearic acid, continue stirring for 30 min, filter, wash three times with deionized water, and dry overnight in a 110°C oven to obtain modified carbon fiber; the mass ratio of carbon fiber loaded with calcium carbonate particles, deionized water and stearic acid is 3.6:100:1.8. A4. Polyvinyl alcohol fiber and oleic acid were added to ethanol and stirred evenly. Hydrochloric acid with a concentration of 2 mol / L was added to adjust the pH to 3. The mixture was stirred at 70℃ for 20 min. Modified carbon fiber was added and the mixture was stirred and mixed for another 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70℃ for 10 min to obtain the composite additive. The mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber was 2.7:1.2:85:3.8.

[0036] Example 3 A low-water-requirement silica-based heat repair material comprises the following raw materials in parts by weight: 65 parts fused silica, 40 parts silica, 20 parts waste silica bricks, 10 parts composite additives, 6 parts nano-grade iron oxide, 10 parts sodium metasilicate nonahydrate, 5 parts alumina, 1 part sodium tripolyphosphate, and 15 parts water. A method for preparing a low-water-demand silica-based heat filler material includes the following preparation steps: Fused silica, silica, waste silica bricks, composite additives, nano-sized iron oxide, sodium metasilicate nonahydrate, alumina, sodium tripolyphosphate and water are mixed evenly and stirred at 150 r / min for 20 min to obtain a low water requirement silica thermal feedstock.

[0037] The composite additive is prepared by the following steps: A1. Carbon fiber and tannic acid were added to ethanol and stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain tannic acid-modified carbon fiber. The mass ratio of carbon fiber, tannic acid and ethanol was 2:1.3:80. A2. Calcium chloride was added to deionized water and stirred until completely dissolved. Tannic acid-modified carbon fibers were added and stirred for 10 min. Ammonia water with a mass fraction of 30% was added to adjust the pH to 8. The mixture was placed in a reaction vessel, and carbon dioxide and air (volume ratio of carbon dioxide to air of 1:3) were introduced at a rate of 25 mL / min. The reaction was carried out at 30 °C for 2 h. The solid was collected by filtration and dried in an oven at 105 °C for 20 min to obtain carbon fibers loaded with calcium carbonate particles. The mass ratio of calcium chloride, deionized water, and tannic acid-modified carbon fibers was 8:85:3.5. A3. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir in a 35°C water bath for 12 min, add stearic acid, continue stirring for 30 min, filter, wash three times with deionized water, and dry overnight in a 110°C oven to obtain modified carbon fiber; the mass ratio of carbon fiber loaded with calcium carbonate particles, deionized water and stearic acid is 3.8:110:2. A4. Polyvinyl alcohol fiber and oleic acid were added to ethanol and stirred evenly. Hydrochloric acid with a concentration of 2 mol / L was added to adjust the pH to 3. The mixture was stirred at 70℃ for 20 min. Modified carbon fiber was added and the mixture was stirred and mixed for another 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70℃ for 10 min to obtain the composite additive. The mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber was 2.8:1.3:90:4.

[0038] Comparative Example 1 The only difference between this comparative example and Example 3 is the preparation of the composite additive, as detailed below: The composite additive is prepared by the following steps: A1. Add calcium chloride to deionized water and stir until completely dissolved. Add carbon fiber and stir for 10 min. Add 30% ammonia water to adjust the pH to 8. Place in a reaction vessel and pass carbon dioxide and air (carbon dioxide to air volume ratio of 1:3) at a rate of 25 mL / min. React at 30℃ for 2 h. Collect the solid by filtration and dry it in an oven at 105℃ for 20 min to obtain carbon fiber loaded with calcium carbonate particles. The mass ratio of calcium chloride, deionized water and carbon fiber is 8:85:3.5. A2. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir in a 35°C water bath for 12 min, add stearic acid, continue stirring for 30 min, filter, wash three times with deionized water, and dry overnight in a 110°C oven to obtain modified carbon fiber; the mass ratio of carbon fiber loaded with calcium carbonate particles, deionized water and stearic acid is 3.8:110:2. A3. Polyvinyl alcohol fiber and oleic acid were added to ethanol and stirred evenly. Hydrochloric acid with a concentration of 2 mol / L was added to adjust the pH to 3. The mixture was stirred at 70℃ for 20 min. Modified carbon fiber was added and the mixture was stirred and mixed for another 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70℃ for 10 min to obtain the composite additive. The mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber was 2.8:1.3:90:4.

[0039] Comparative Example 2 The only difference between this comparative example and Example 3 is the preparation of the composite additive, as detailed below: The composite additive is prepared by the following steps: A1. Carbon fiber and tannic acid were added to ethanol and stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain tannic acid-modified carbon fiber. The mass ratio of carbon fiber, tannic acid and ethanol was 2:1.3:80. A2. Tannic acid-modified carbon fibers were added to deionized water and stirred in a 35°C water bath for 12 min. Stearic acid was added, and the reaction was continued for 30 min. After filtration, the carbon fibers were washed three times with deionized water and dried overnight in a 110°C oven to obtain modified carbon fibers. The mass ratio of tannic acid-modified carbon fibers, deionized water, and stearic acid was 3.8:110:2. A3. Polyvinyl alcohol fiber and oleic acid were added to ethanol and stirred evenly. Hydrochloric acid with a concentration of 2 mol / L was added to adjust the pH to 3. The mixture was stirred at 70℃ for 20 min. Modified carbon fiber was added and the mixture was stirred and mixed for another 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70℃ for 10 min to obtain the composite additive. The mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber was 2.8:1.3:90:4.

[0040] Comparative Example 3 The only difference between this comparative example and Example 3 is the preparation of the composite additive, as detailed below: The composite additive is prepared by the following steps: A1. Carbon fiber and tannic acid were added to ethanol and stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain tannic acid-modified carbon fiber. The mass ratio of carbon fiber, tannic acid and ethanol was 2:1.3:80. A2. Calcium chloride was added to deionized water and stirred until completely dissolved. Tannic acid-modified carbon fibers were added and stirred for 10 min. Ammonia water with a mass fraction of 30% was added to adjust the pH to 8. The mixture was placed in a reaction vessel, and carbon dioxide and air (volume ratio of carbon dioxide to air of 1:3) were introduced at a rate of 25 mL / min. The reaction was carried out at 30 °C for 2 h. The solid was collected by filtration and dried in an oven at 105 °C for 20 min to obtain carbon fibers loaded with calcium carbonate particles. The mass ratio of calcium chloride, deionized water, and tannic acid-modified carbon fibers was 8:85:3.5. A3. Polyvinyl alcohol fiber and oleic acid were added to ethanol and stirred evenly. Hydrochloric acid with a concentration of 2 mol / L was added to adjust the pH to 3. The mixture was stirred at 70℃ for 20 min. Carbon fiber loaded with calcium carbonate particles was added and the mixture was stirred and mixed for another 2 h. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70℃ for 10 min to obtain a composite additive. The mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and carbon fiber loaded with calcium carbonate particles was 2.8:1.3:90:4.

[0041] Comparative Example 4 The only difference between this comparative example and Example 3 is the preparation of the composite additive, as detailed below: The composite additive is prepared by the following steps: A1. Carbon fiber and tannic acid were added to ethanol and stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain tannic acid-modified carbon fiber. The mass ratio of carbon fiber, tannic acid and ethanol was 2:1.3:80. A2. Calcium chloride was added to deionized water and stirred until completely dissolved. Tannic acid-modified carbon fibers were added and stirred for 10 min. Ammonia water with a mass fraction of 30% was added to adjust the pH to 8. The mixture was placed in a reaction vessel, and carbon dioxide and air (volume ratio of carbon dioxide to air of 1:3) were introduced at a rate of 25 mL / min. The reaction was carried out at 30 °C for 2 h. The solid was collected by filtration and dried in an oven at 105 °C for 20 min to obtain carbon fibers loaded with calcium carbonate particles. The mass ratio of calcium chloride, deionized water, and tannic acid-modified carbon fibers was 8:85:3.5. A3. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir in a 35°C water bath for 12 min, add stearic acid, continue stirring for 30 min, filter, wash three times with deionized water, and dry overnight in a 110°C oven to obtain modified carbon fiber; the mass ratio of carbon fiber loaded with calcium carbonate particles, deionized water and stearic acid is 3.8:110:2. A4. Add oleic acid to ethanol, stir well, add 2 mol / L hydrochloric acid to adjust the pH to 3, stir and react at 70℃ for 20 min, add modified carbon fiber, continue stirring and mixing for 2 h, filter, wash 3 times with deionized water, and dry in a 70℃ oven for 10 min to obtain composite additive; the mass ratio of oleic acid, ethanol and modified carbon fiber is 1.3:90:6.8.

[0042] The performance of the low water demand silica thermal additives prepared in Examples 1-3 and Comparative Examples 1-4 was tested.

[0043] The low water demand silica heat-concentrating materials prepared in Examples 1-3 and Comparative Examples 1-4 were kept at 1450℃ for 3 hours and then cooled to room temperature. The compressive strength was tested according to GB / T 5072-2008 and the flexural strength was tested according to GB / T 3001-2017. The porosity of the low water demand silica heat-concentrating materials prepared in Examples 1-3 and Comparative Examples 1-4 was tested according to GB / T 2997-2015.

[0044] The test results are shown in Table 1.

[0045] Table 1 Performance testing of low water demand silica thermal feedstocks prepared in Examples 1-3 and Comparative Examples 1-4 As can be seen from the data in Table 1, the low water demand silica heat-mixing materials prepared in Examples 1-3 have high density and low water demand.

[0046] In Comparative Example 1, the tannic acid-modified carbon fiber was replaced with carbon fiber, and the composite additive prepared was added to the silica heat filler. The performance of the silica heat filler decreased, which proved that the surface modification of carbon fiber with tannic acid can endow the carbon fiber with a large number of polar functional groups, which is conducive to the synthesis of a large number of nano-calcium carbonate particles on the surface of carbon fiber. Nano-calcium carbonate can fill the pores of the silica heat filler, making the silica heat filler more compact and reducing the amount of water required to fill the pores. Thus, without sacrificing workability, the total water requirement is further reduced.

[0047] Comparative Example 2 replaced the carbon fibers loaded with calcium carbonate particles with carbon fibers modified with tannic acid. The resulting composite additive was added to the silica heat filler, which reduced the performance of the silica heat filler. This demonstrates that nano-calcium carbonate can fill the pores of the silica heat filler, making the silica heat filler more compact and reducing the amount of water required to fill the pores. Thus, without sacrificing workability, the total water requirement is further reduced.

[0048] Comparative Example 3 replaced the modified carbon fiber with carbon fiber loaded with calcium carbonate particles. The composite additive prepared was added to the silica heat filler, and the performance of the silica heat filler decreased. This proves that the introduction of a calcium stearate layer on the surface of the carbon fiber loaded with calcium carbonate particles allows the hydrophobic chains in the formed calcium stearate layer to penetrate into the capillary pores of the silica heat filler, reducing the porosity, reducing the amount of water required to fill the pores, and increasing the bonding strength between the carbon fiber loaded with calcium carbonate particles and the silica heat filler. This prevents the carbon fiber from slipping relative to the silica heat filler when subjected to external forces, thus avoiding a decrease in the performance of the silica heat filler.

[0049] Comparative Example 4 replaced polyvinyl alcohol fibers with modified carbon fibers. The composite additive prepared was added to the silica heat repair material, and the performance of the silica heat repair material decreased. This proves that the modified carbon fibers and polyvinyl alcohol fibers form a cross-linked network structure through oleic acid. The silica heat repair material matrix can fill into the cross-linked network structure, improve the density of the silica heat repair material, reduce the porosity, and thus reduce the amount of water required to fill the pores. The formed cross-linked network structure can absorb and weaken the energy generated by the impact force, and enhance the compressive strength of the silica heat repair material. In addition, polyvinyl alcohol fibers can also bridge microcracks and prevent crack propagation.

[0050] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A low-water-demand silica-based heat-contributing material, characterized in that, The raw materials include the following parts by weight: 50-65 parts fused silica, 30-40 parts silica, 10-20 parts waste silica bricks, 6-10 parts composite additives, 3-6 parts mineralizer, 4-10 parts binder, 3-5 parts sintering agent, 0.5-1 part water-reducing agent, and 10-15 parts water. The composite additive is obtained by mixing and reacting modified carbon fiber with stearic acid, and then mixing and reacting it with polyvinyl alcohol fiber and oleic acid. The modified carbon fiber is obtained by modifying the carbon fiber surface with tannic acid and then depositing nano-calcium carbonate in situ.

2. The low-water-demand silica-based heat-contributing material according to claim 1, characterized in that, The composite additive is prepared by the following steps: A1. Add carbon fiber and tannic acid to ethanol, stir, filter, wash, and dry to obtain tannic acid modified carbon fiber; A2. Add calcium chloride to deionized water and stir until completely dissolved. Add tannic acid-modified carbon fiber, stir, add ammonia to adjust the pH, place in a reaction vessel, and pass carbon dioxide and air through. After the reaction, filter to collect the solid, dry, and obtain carbon fiber loaded with calcium carbonate particles. A3. Add the carbon fiber loaded with calcium carbonate particles to deionized water, stir, add stearic acid, continue stirring and reacting, filter, wash, and dry to obtain modified carbon fiber; A4. Polyvinyl alcohol fiber and oleic acid are added to ethanol and stirred evenly. Hydrochloric acid is added to adjust the pH. After the reaction is complete, modified carbon fiber is added and the mixture is stirred and mixed. After filtration, washing and drying, a composite additive is obtained.

3. The low-water-demand silica-based heat-contributing material according to claim 2, characterized in that, In step A1, the mass ratio of carbon fiber, tannic acid and ethanol is (1.5-2):(1-1.3):(70-80).

4. The low-water-demand silica-based heat-contributing material according to claim 2, characterized in that, In step A2, the mass ratio of calcium chloride, deionized water and tannic acid-modified carbon fiber is (7.5-8):(80-85):(3-3.5).

5. The low-water-demand silica-based heat-contributing material according to claim 2, characterized in that, In step A3, the mass ratio of the carbon fiber, deionized water and stearic acid loaded with calcium carbonate particles is (3.3-3.8):(90-110):(1.5-2).

6. The low-water-demand silica heat-contributing material according to claim 2, characterized in that, In step A4, the mass ratio of polyvinyl alcohol fiber, oleic acid, ethanol and modified carbon fiber is (2.5-2.8):(1.1-1.3):(80-90):(3.5-4).

7. The low-water-demand silica heat-contributing material according to claim 1, characterized in that, The fused silica has a particle size of 0.05-0.1 mm; the silica has a particle size of 310-330 mesh.

8. The low-water-demand silica heat-contributing material according to claim 1, characterized in that, The waste silica bricks have a particle size of 240-300 mesh; the mineralizer is nano-sized iron oxide with a particle size of 100-150 nm.

9. The low-water-demand silica heat-contributing material according to claim 1, characterized in that, The water-reducing agent is selected from any one of naphthalene-based water-reducing agents, sodium tripolyphosphate, and sodium hexametaphosphate. The sintering agent is selected from any one of clay, bentonite, and alumina; The binder is selected from sodium metasilicate nonahydrate or sodium metasilicate pentahydrate.

10. A method for preparing a low-water-demand silica heat-contributing material as described in any one of claims 1-9, characterized in that, The preparation steps include the following: Fused silica, silica, waste silica bricks, composite additives, mineralizers, binders, sintering agents, water-reducing agents, and water are mixed evenly and stirred at 100-150 r / min for 15-20 min to obtain a low-water-requirement silica thermal feedstock.

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