A dry refractory composition having excellent crack propagation resistance

Abstract

The present application relates to the technical field of refractory materials, and particularly relates to a dry refractory material composition with excellent crack propagation resistance, which comprises the following components: refractory aggregate, refractory powder, binder, modified stainless steel fiber, modified ammonium polyphosphate, and modified nano-aluminum oxide. Ammonium polyphosphate is decomposed to release phosphoric acid, which is released to the crack area in a directional manner through the controlled release effect of mesoporous silicoaluminate. Active B2O3 diffuses to the surface of modified ammonium polyphosphate, reacts with borate groups to form a borophosphate gel network, and quickly seals the crack channel. Rare earth oxides act as catalytic sites, which can reduce the activation energy of AlPO4 generation. When the temperature continues to rise, the mesoporous silicoaluminate softens to form a viscous fluid, which carries residual AlPO4 to migrate to the crack and fill the crack channel, and the MgAl2O4 crystal phase skeleton and silicate glass phase fill to form a dense sealing structure.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically a dry refractory material composition with excellent crack propagation resistance. Background Technology

[0002] Dry refractories are a type of monolithic refractory material, shipped in bulk, and consist of a mixture of refractory aggregates, refractory powders, and binders in a specific ratio. Compared to traditional sintered refractory bricks, they offer advantages such as convenient construction, strong adaptability, and no need for pre-firing, and are widely used in high-temperature industries such as steel, cement, and glass.

[0003] Dry refractories face the problem of crack propagation due to thermal stress during high-temperature use. Current technologies typically add metal fibers (such as stainless steel fibers) to the matrix as toughening materials. The initial design intention of metal fibers is to prevent crack propagation through fiber bridging and to absorb some strain energy through the plastic deformation of the metal, thereby improving the material's thermal shock resistance and fracture toughness. However, in actual high-temperature use, despite the addition of stainless steel fibers, dry refractories can still develop cracks due to localized stress concentration, rapid heating and cooling, mechanical impact, and chemical erosion. Once cracks form, oxygen can penetrate into the material along the crack channels. At this point, traditional stainless steel fibers undergo significant oxidation reactions in the temperature range of 800-1000℃, generating oxides such as Fe2O3 and Cr2O3. The molar volume of these oxides is larger than that of the original metal, and the expansion of the oxide layer generates additional wedging stress at the fiber-matrix interface and on the crack walls. This further exacerbates crack initiation, leading to material performance degradation. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The purpose of this invention is to provide a dry refractory material composition with excellent crack propagation resistance, so as to solve the problem that the metal fibers in the dry refractory material composition are oxidized at high temperature when oxygen invades along the crack, which leads to further crack aggravation.

[0006] (2) Technical solution

[0007] To achieve the above objectives, on the one hand, the present invention provides a dry refractory material composition with excellent crack propagation resistance, comprising the following components in parts by weight: 60-75 parts of refractory aggregate, 18-25 parts of refractory powder, 5-8 parts of binder, 3-6 parts of modified stainless steel fiber, 6-10 parts of modified ammonium polyphosphate, and 2-5 parts of modified nano-alumina.

[0008] The modified stainless steel fiber has a composite layer structure, consisting of, from the inside out: stainless steel fiber, Cu-Mn composite oxide layer, zirconium boride-silicate glass composite protective layer, and the outermost layer grafted with aminosilane and epoxysilane coupling agent.

[0009] The modified ammonium polyphosphate has a core-shell structure, with the core being ammonium polyphosphate microspheres, the middle layer being mesoporous aluminosilicate, and the outer shell being a phosphate ester bridging layer with borate ester end caps.

[0010] The modified nano-alumina has a surface bilayer modified structure, with the inner layer being rare earth oxide catalytic sites and the outer layer grafted with phosphate-boron ester bidentate ligands.

[0011] Furthermore, the method for preparing the modified stainless steel fiber includes the following steps:

[0012] S11. Immerse stainless steel fibers in H2SO4 solution, activate at room temperature, wash with deionized water, and dry to obtain pretreated stainless steel fibers.

[0013] S12. Copper nitrate and manganese acetate were dissolved in anhydrous ethanol by stirring, citric acid was added, and the mixture was stirred evenly to obtain a precursor solution; the pretreated stainless steel fiber was immersed in the precursor solution, dried, fully impregnated-dried, and calcined to obtain the first compound.

[0014] S13. Disperse ZrB2 powder, sodium hexametaphosphate and boric acid in anhydrous ethanol by ultrasonication, add silica sol and continue stirring to obtain a slurry; immerse the first compound in the slurry, perform ultrasonic-assisted impregnation, lift and drain, dry and calcine to obtain the second compound;

[0015] S14. Dissolve KH550 and KH560 in anhydrous ethanol / deionized water mixed solvent, add glacial acetic acid to adjust the pH, stir and hydrolyze at room temperature to obtain silane solution; immerse the second compound in silane solution, react at room temperature, remove and vacuum dry, and heat-curing to obtain modified stainless steel fiber.

[0016] Furthermore, the preparation method of the modified ammonium polyphosphate includes the following steps:

[0017] S21. Ammonium polyphosphate is heat-treated under nitrogen protection, cooled, and then anhydrous ethanol and melamine phosphate are added and ultrasonically dispersed to obtain an ammonium polyphosphate suspension.

[0018] S22. Add hexadecyltrimethylammonium bromide to a suspension of ammonium polyphosphate, stir to dissolve, add ammonia to adjust the pH, and obtain a suspension; dissolve aluminum isopropoxide in isopropanol, add tetraethyl orthosilicate, stir evenly, slowly add to the suspension, stir the reaction at room temperature, centrifuge the obtained reaction solution to collect the solid, wash with anhydrous ethanol and deionized water alternately, dry, and calcine to obtain mesoporous aluminosilicate-coated ammonium polyphosphate;

[0019] S23. Mesoporous aluminosilicate-coated ammonium polyphosphate is dispersed in anhydrous ethanol to obtain a suspension; 2-carboxyethylphenyl hypophosphoric acid, tris(hydroxymethyl)aminomethane, and boric acid are added sequentially to dimethyl sulfoxide and refluxed. The mixture is then added to the suspension, and KH550 is added. The mixture is stirred and reacted. The solid is collected by centrifugation and dried under vacuum to obtain modified ammonium polyphosphate.

[0020] Furthermore, the preparation method of the modified nano-alumina includes the following steps:

[0021] S31. Disperse nano-alumina in deionized water, add sodium citrate to obtain nano-alumina suspension; dissolve La(NO3)3·6H2O and Ce(NO3)3·6H2O in deionized water, slowly add them dropwise to the nano-alumina suspension, simultaneously add ammonia water to adjust the pH, stir the reaction, centrifuge the obtained reaction solution to collect the solid, wash with deionized water, dry, and calcine to obtain La2O3-CeO2 modified nano-alumina;

[0022] S32. The La2O3-CeO2 modified nano-alumina was ultrasonically dispersed in anhydrous toluene to obtain a suspension; 2-carboxyethylphenyl hypophosphoric acid, phenylboronic acid and KH550 were added to anhydrous toluene in sequence and refluxed. The mixture was added to the suspension and refluxed again. The solid was collected by filtration, washed with anhydrous toluene, vacuum dried, heat-cured, ground and sieved to obtain modified nano-alumina.

[0023] Furthermore, the preparation method of the dry refractory material composition includes the following steps:

[0024] S1. Place refractory aggregate, refractory powder, and modified nano-alumina in a mixer and dry mix. Add a binder and mix. Then add modified ammonium polyphosphate and mix at low speed. Finally, add modified stainless steel fiber and continue mixing at low speed. Seal and age to obtain a dry refractory material composition.

[0025] Furthermore, the refractory aggregate is corundum and magnesia in a mass ratio of 3:2 and has a particle size of 0.5-8mm.

[0026] Furthermore, the refractory powder is composed of corundum powder, magnesia powder, high alumina powder, and silica powder in a mass ratio of 2:2:1:1, and has a particle size of less than 0.088 mm.

[0027] Furthermore, the binder is selected from one or more combinations of phenolic resin and water glass.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] 1. When crack formation leads to oxygen infiltration, the material initiates a multi-stage crack propagation inhibition mechanism. As the temperature begins to rise, the borate end-capping groups on the surface of the modified ammonium polyphosphate become activated, and the ammonium polyphosphate decomposes to release phosphoric acid. This phosphoric acid is then directionally released into the crack region through the controlled release effect of mesoporous aluminosilicates, effectively blocking oxygen from penetrating into the material interior along the crack channel and inhibiting the occurrence of subsequent oxidative intensification reactions from the source.

[0030] 2. As the temperature continues to rise, the ZrB2 layer on the surface of the modified stainless steel fiber undergoes controlled oxidation under the catalysis of Cu-Mn composite oxides, generating active B2O3 in situ. This B2O3 diffuses to the surface of the modified ammonium polyphosphate, reacting with borate ester groups to form a borophosphate gel network, rapidly sealing crack channels and preventing further lateral crack propagation. Simultaneously, the silicate glass layer softens and flows, aiding in filling. Rare earth oxides, acting as catalytic sites, can lower the activation energy of AlPO4 formation, promoting the reaction of phosphoric acid with the alumina matrix at lower temperatures to form an AlPO4 binder phase, enhancing the interfacial bonding strength of the crack walls and inhibiting further cracking under stress.

[0031] 3. As the temperature continues to rise, mesoporous aluminosilicates soften and form a viscous fluid, carrying residual AlPO4 to migrate towards the crack and fill the crack channel. Bifunctional nano-alumina acts as a crystal nucleus, reducing the nucleation barrier and inducing MgAl2O4 spinel to form in situ from the magnesia aggregate, providing high-temperature mechanical locking and preventing the crack from continuing to propagate under high-temperature thermal stress. At the same time, the silicate glass phase fills the intergranular gaps of the spinel grains, forming a tight sealing structure of crystal skeleton and glass phase filling, which significantly reduces the degree of crack intensification. Attached Figure Description

[0032] Figure 1 The images show SEM comparisons of the degree of crack intensification in the refractory material composition of the present invention. a) shows the degree of crack intensification in Example 1 after sintering at 1200℃, and b) shows the degree of crack intensification in Comparative Example 8 after sintering at 1200℃. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1: This example discloses a dry refractory material composition with excellent crack propagation resistance, comprising the following components in parts by weight: 75 parts of refractory aggregate, 25 parts of refractory powder, 8 parts of binder, 6 parts of modified stainless steel fiber, 10 parts of modified ammonium polyphosphate, and 5 parts of modified nano alumina.

[0035] The modified stainless steel fiber has a composite layer structure, consisting of, from the inside out: stainless steel fiber, Cu-Mn composite oxide layer, zirconium boride-silicate glass composite protective layer, and the outermost layer grafted with aminosilane and epoxysilane coupling agent.

[0036] The modified ammonium polyphosphate has a core-shell structure, with the core being ammonium polyphosphate microspheres, the middle layer being mesoporous aluminosilicate, and the outer shell being a phosphate ester bridging layer with borate ester end caps.

[0037] The modified nano-alumina has a surface bilayer modified structure, with the inner layer being rare earth oxide catalytic sites and the outer layer grafted with phosphate-boron ester bidentate ligands.

[0038] The method for preparing the modified stainless steel fiber includes the following steps:

[0039] S11. Immerse 100g of stainless steel fiber in 10% H2SO4 solution, activate at room temperature for 30min, wash with deionized water, and dry at 70℃ to obtain pretreated stainless steel fiber.

[0040] S12. Dissolve 8.5g of copper nitrate and 12.3g of manganese acetate in 200mL of anhydrous ethanol, add 15g of citric acid, stir until homogeneous to obtain a precursor solution; immerse the pretreated stainless steel fiber in the precursor solution for 5min, dry at 80℃, thoroughly impregnate and dry 3 times, and calcine in air at 450℃ for 2h to obtain the first compound.

[0041] S13. Disperse 20g ZrB2 powder, 2g sodium hexametaphosphate and 8g boric acid in 150mL anhydrous ethanol, add 30mL silica sol and continue stirring to obtain a slurry; immerse the first compound in the slurry, ultrasonically assisted impregnate for 10min, lift and drain, dry at 90℃ for 4h, and calcine at 700℃ for 2h in a nitrogen protective atmosphere to obtain the second compound;

[0042] S14. Dissolve 5g KH550 and 3g KH560 in 100mL of anhydrous ethanol / deionized water mixed solvent (volume ratio 95:5), add glacial acetic acid to adjust the pH to 4-5, stir and hydrolyze at room temperature for 30min to obtain silane solution; immerse the second compound in silane solution, react at room temperature for 12h, remove and vacuum dry at 60℃ for 6h, heat cure at 120℃ for 2h to obtain modified stainless steel fiber.

[0043] The preparation method of the modified ammonium polyphosphate includes the following steps:

[0044] S21. 100g of ammonium polyphosphate (APP-II type, degree of polymerization >1000) was heat-treated at 180℃ for 1.5h under nitrogen protection. After cooling, 300mL of anhydrous ethanol and 10g of melamine phosphate were added and ultrasonically dispersed for 30min to obtain ammonium polyphosphate suspension.

[0045] S22. Add 12g of cetyltrimethylammonium bromide to a suspension of ammonium polyphosphate, stir to dissolve, and add ammonia dropwise to adjust the pH to 10-11 to obtain a suspension; dissolve 5g of aluminum isopropoxide in 50mL of isopropanol, add 25mL of tetraethyl orthosilicate, stir evenly, and slowly add dropwise to the suspension. Stir the reaction at room temperature, centrifuge the reaction solution to collect the solid, wash it alternately with anhydrous ethanol and deionized water, dry it at 60℃, and calcine it at 250℃ to obtain mesoporous aluminosilicate-coated ammonium polyphosphate.

[0046] S23. Mesoporous aluminosilicate-coated ammonium polyphosphate was dispersed in anhydrous ethanol to obtain a suspension; 10g of 2-carboxyethylphenyl hypophosphoric acid, 6g of tris(hydroxymethyl)aminomethane, and 5g of boric acid were added sequentially to 100mL of dimethyl sulfoxide and refluxed. The mixture was then added to the suspension, and 3g of KH550 was added. The mixture was stirred at room temperature for 12h, and the solid was collected by centrifugation and dried under vacuum at 60℃ for 8h to obtain modified ammonium polyphosphate.

[0047] The preparation method of the modified nano-alumina includes the following steps:

[0048] S31. Disperse 50g of nano-alumina in 500mL of deionized water, add 3g of sodium citrate to obtain a nano-alumina suspension; dissolve 8.7g of La(NO3)3·6H2O and 8.7g of Ce(NO3)3·6H2O in 100mL of deionized water, slowly add them dropwise to the nano-alumina suspension, and simultaneously add 25% ammonia water to adjust the pH to 9-10. Stir the reaction at 80℃ for 4h, centrifuge the resulting reaction solution to collect the solid, wash with deionized water, dry at 80℃, and calcine at 600℃ to obtain La2O3-CeO2 modified nano-alumina;

[0049] S32. 40g of La2O3-CeO2 modified nano-alumina was ultrasonically dispersed in 200mL of anhydrous toluene to obtain a suspension; 8g of 2-carboxyethylphenyl hypophosphoric acid, 5g of phenylboronic acid and 10g of KH550 were added sequentially to 150mL of anhydrous toluene and refluxed at 110℃ for 6h. The mixture was then added to the suspension and refluxed at 80℃ for another 2h. The solid was collected by filtration, washed with anhydrous toluene, vacuum dried at 80℃, heat-cured at 200℃ for 2h, and ground through a 300-mesh sieve to obtain modified nano-alumina.

[0050] The preparation method of the dry refractory material composition includes the following steps:

[0051] S1. Place refractory aggregate (corundum: magnesia = 3:2), refractory powder (corundum powder: magnesia powder: high alumina powder: silica powder = 2:2:1:1), and modified nano alumina in a mixer and dry mix at 60 rpm for 8 min. Add binder and mix at 60 rpm for 10 min. Then add modified ammonium polyphosphate and mix at low speed at 30 rpm for 5 min. Finally, add modified stainless steel fiber and continue mixing at low speed at 30 rpm for 5 min. Seal and age for 48 h to obtain a dry refractory material composition.

[0052] Example 2: This example is based on Example 1, but differs from Example 1 in that it discloses a dry refractory material composition with excellent crack propagation resistance, comprising the following components in parts by weight: 68 parts of refractory aggregate, 22 parts of refractory powder, 7 parts of binder, 5 parts of modified stainless steel fiber, 8 parts of modified ammonium polyphosphate, and 4 parts of modified nano-alumina.

[0053] The other components and preparation methods are the same as in Example 1.

[0054] Example 3: This example is based on Example 1, but differs from Example 1 in that it discloses a dry refractory material composition with excellent crack propagation resistance, comprising the following components in parts by weight: 60 parts of refractory aggregate, 18 parts of refractory powder, 5 parts of binder, 3 parts of modified stainless steel fiber, 6 parts of modified ammonium polyphosphate, and 2 parts of modified nano alumina.

[0055] The other components and preparation methods are the same as in Example 1.

[0056] Comparative Example 1: This comparative example is based on Example 1, but differs from Example 1 in that the modified stainless steel fiber described in this comparative example does not contain a Cu-Mn composite oxide layer.

[0057] The method for preparing the modified stainless steel fiber includes the following steps:

[0058] S11. Immerse 100g of stainless steel fiber in 10% H2SO4 solution, activate at room temperature for 30min, wash with deionized water, and dry at 70℃ to obtain pretreated stainless steel fiber.

[0059] S12. Disperse 20g ZrB2 powder, 2g sodium hexametaphosphate and 8g boric acid in 150mL anhydrous ethanol, add 30mL silica sol, and continue stirring to obtain a slurry; immerse pretreated stainless steel fibers in the slurry, ultrasonically assisted impregnate for 10min, pull out and drain, dry at 90℃ for 4h, and calcine at 700℃ for 2h in a nitrogen protective atmosphere to obtain the third compound;

[0060] S13. Dissolve 5g KH550 and 3g KH560 in 100mL of anhydrous ethanol / deionized water mixed solvent (volume ratio 95:5), add glacial acetic acid to adjust the pH to 4-5, stir and hydrolyze at room temperature for 30min to obtain silane solution; immerse the third compound in silane solution, react at room temperature for 12h, remove and vacuum dry at 60℃ for 6h, heat cure at 120℃ for 2h to obtain modified stainless steel fiber.

[0061] The other components and preparation methods are the same as in Example 1.

[0062] Comparative Example 2: This comparative example is based on Example 1, but differs from Example 1 in that the modified stainless steel fiber described in this comparative example does not contain a zirconium boride-silicate glass composite protective layer.

[0063] The method for preparing the modified stainless steel fiber includes the following steps:

[0064] S11. Immerse 100g of stainless steel fiber in 10% H2SO4 solution, activate at room temperature for 30min, wash with deionized water, and dry at 70℃ to obtain pretreated stainless steel fiber.

[0065] S12. Dissolve 8.5g of copper nitrate and 12.3g of manganese acetate in 200mL of anhydrous ethanol, add 15g of citric acid, stir until homogeneous to obtain a precursor solution; immerse the pretreated stainless steel fiber in the precursor solution for 5min, dry at 80℃, thoroughly impregnate and dry 3 times, and calcine in air at 450℃ for 2h to obtain the first compound.

[0066] S13. Dissolve 5g KH550 and 3g KH560 in 100mL of anhydrous ethanol / deionized water mixed solvent (volume ratio 95:5), add glacial acetic acid to adjust the pH to 4-5, stir and hydrolyze at room temperature for 30min to obtain silane solution; immerse the first compound in silane solution, react at room temperature for 12h, remove and vacuum dry at 60℃ for 6h, heat cure at 120℃ for 2h to obtain modified stainless steel fiber.

[0067] The other components and preparation methods are the same as in Example 1.

[0068] Comparative Example 3: This comparative example is based on Example 1, but differs from Example 1 in that the modified ammonium polyphosphate described in this comparative example does not contain mesoporous aluminosilicates.

[0069] The preparation method of the modified ammonium polyphosphate includes the following steps:

[0070] S21. 100g of ammonium polyphosphate (APP-II type, degree of polymerization >1000) was heat-treated at 180℃ for 1.5h under nitrogen protection. After cooling, 300mL of anhydrous ethanol and 10g of melamine phosphate were added and ultrasonically dispersed for 30min to obtain ammonium polyphosphate suspension.

[0071] S22. 10g of 2-carboxyethylphenyl hypophosphoric acid, 6g of tris(hydroxymethyl)aminomethane, and 5g of boric acid were added sequentially to 100mL of dimethyl sulfoxide and refluxed. The mixture was then added to a suspension of ammonium polyphosphate, and 3g of KH550 was added. The mixture was stirred at room temperature for 12h, and the solid was collected by centrifugation and dried under vacuum at 60℃ for 8h to obtain modified ammonium polyphosphate.

[0072] The other components and preparation methods are the same as in Example 1.

[0073] Comparative Example 4: This comparative example is based on Example 1, but differs from Example 1 in that the modified ammonium polyphosphate described in this comparative example does not contain a phosphate ester bridging layer with borate ester end capping.

[0074] The preparation method of the modified ammonium polyphosphate includes the following steps:

[0075] S21. 100g of ammonium polyphosphate (APP-II type, degree of polymerization >1000) was heat-treated at 180℃ for 1.5h under nitrogen protection. After cooling, 300mL of anhydrous ethanol and 10g of melamine phosphate were added and ultrasonically dispersed for 30min to obtain ammonium polyphosphate suspension.

[0076] S22. Add 12g of cetyltrimethylammonium bromide to a suspension of ammonium polyphosphate, stir to dissolve, and add ammonia dropwise to adjust the pH to 10-11 to obtain a suspension; dissolve 5g of aluminum isopropoxide in 50mL of isopropanol, add 25mL of tetraethyl orthosilicate, stir evenly, and slowly add dropwise to the suspension. Stir the reaction at room temperature, centrifuge the reaction solution to collect the solid, wash it alternately with anhydrous ethanol and deionized water, dry it at 60℃, and calcine it at 250℃ to obtain mesoporous aluminosilicate-coated ammonium polyphosphate.

[0077] S23. Mesoporous aluminosilicate-coated ammonium polyphosphate was dispersed in anhydrous ethanol to obtain a suspension. 3g of KH550 was added, and the mixture was stirred at room temperature for 12h. The solid was collected by centrifugation and dried under vacuum at 60℃ for 8h to obtain modified ammonium polyphosphate.

[0078] The other components and preparation methods are the same as in Example 1.

[0079] Comparative Example 5: This comparative example is based on Example 1, but differs from Example 1 in that the modified nano-alumina described in this comparative example does not contain rare earth oxide catalytic sites.

[0080] The preparation method of the modified nano-alumina includes the following steps:

[0081] S31. 40g of nano-alumina was ultrasonically dispersed in 200mL of anhydrous toluene to obtain a suspension; 8g of 2-carboxyethylphenyl hypophosphoric acid, 5g of phenylboronic acid and 10g of KH550 were added sequentially to 150mL of anhydrous toluene and refluxed at 110℃ for 6h. The mixture was then added to the suspension and refluxed at 80℃ for another 2h. The solid was collected by filtration, washed with anhydrous toluene, vacuum dried at 80℃, and heat-cured at 200℃ for 2h. The solid was then ground through a 300-mesh sieve to obtain modified nano-alumina.

[0082] The other components and preparation methods are the same as in Example 1.

[0083] Comparative Example 6: This comparative example is based on Example 1, but differs from Example 1 in that the modified nano-alumina described in this comparative example is not grafted with phosphate-boronate bidentate ligands.

[0084] The preparation method of the modified nano-alumina includes the following steps:

[0085] S31. Disperse 50g of nano-alumina in 500mL of deionized water, add 3g of sodium citrate to obtain a nano-alumina suspension; dissolve 8.7g of La(NO3)3·6H2O and 8.7g of Ce(NO3)3·6H2O in 100mL of deionized water, slowly add them dropwise to the nano-alumina suspension, and simultaneously add 25% ammonia water to adjust the pH to 9-10. Stir the reaction at 80℃ for 4h, centrifuge the resulting reaction solution to collect the solid, wash with deionized water, dry at 80℃, and calcine at 600℃ to obtain modified nano-alumina.

[0086] The other components and preparation methods are the same as in Example 1.

[0087] Comparative Example 7: This comparative example is based on Example 1, but unlike Example 1, this comparative example does not add modified ammonium polyphosphate and modified nano alumina.

[0088] The other components and preparation methods are the same as in Example 1.

[0089] Comparative Example 8: This comparative example is a dry refractory material composition with added traditional stainless steel fibers, that is, the stainless steel fibers in this comparative example are not modified.

[0090] This comparative example discloses a dry refractory material composition with excellent crack propagation resistance, comprising the following components in parts by weight: 75 parts of refractory aggregate, 25 parts of refractory powder, 8 parts of binder, and 6 parts of stainless steel fiber.

[0091] Experimental verification:

[0092] Sample Preparation: The dry refractory material compositions prepared in the examples and comparative examples were uniformly mixed with water by spraying while stirring. The moistened slurry was then poured into a steel mold and compacted using a vibrating table with a vibration frequency of 50 Hz and an amplitude of 0.8 mm for 3-5 minutes until the surface was smooth and no air bubbles overflowed. Each addition of material did not exceed 30 mm in thickness, and compaction was carried out in layers. After 24 hours of vibration molding, the samples were demolded and cured for 24 hours at an ambient temperature of 20±5℃ and a relative humidity of ≤60%. They were then dried at 110℃ for 24 hours to remove physical moisture and cooled to room temperature to obtain the samples.

[0093] Experiment 1:

[0094] (1) High-temperature oxidation weight gain: The sample was cut into a cube of 20mm×20mm×20mm. A diamond cutting disc was used to make a vertical cut in the middle of the sample, with a cutting depth of 5mm (50% of the sample height) and a cutting width of about 0.3mm. After cutting, the powder at the cut was removed with compressed air. The sample was kept at 1200℃ in air for 50h. It was taken out and weighed every 10h, and the oxidation weight gain after 50h was calculated.

[0095] (2) Crack intensification: The samples were cut into thin plates of 40mm×40mm×10mm and dried at 110℃ for 24 hours. Standard initial cracks were pre-formed on the sample surface using a diamond cutting disc. The pre-formed crack area was observed using a scanning electron microscope (SEM). The crack direction was statistically analyzed using image analysis software, and the transverse crack ratio P0 in the initial state was recorded. P0 was uniformly set to 42%. Subsequently, the pre-formed crack samples were placed in a high-temperature furnace and heated to 800℃, 1000℃, and 1200℃ respectively in an air atmosphere at a heating rate of 5℃ / min. After holding at each temperature for 2 hours, the samples were cooled to room temperature with the furnace. After cooling, SEM observation was performed again in the same area at the same magnification. The transverse crack ratio P after sintering at each temperature was statistically analyzed using the same image analysis method. 800 P 1000 P 1200 And calculate the degree of crack intensification, ΔP(T) = (P T −P0) / P0×100%.

[0096] Table 1: Results of High-Temperature Oxidation Weight Gain Rate and Crack Intensification:

[0097]

[0098] Table 1 shows the results of high-temperature oxidation weight gain and crack intensification. The results indicate that Example 1, due to the complete modified structure of the stainless steel fiber, exhibits excellent high-temperature oxidation resistance and crack propagation resistance. Comparative Example 8 showed the highest 50-hour oxidation weight gain, indicating that fiber surface modification is key to inhibiting high-temperature oxidation. The oxidation weight gain and crack intensification of the comparative example were significantly higher than those of the example, demonstrating the indispensable synergistic protective effect of the two-layer structure.

[0099] like Figure 1 The image shows a comparison of SEM images of the degree of crack intensification in the refractory material composition of the present invention. a) shows the degree of crack intensification in Example 1 after sintering at 1200℃, and b) shows the degree of crack intensification in Comparative Example 8 after sintering at 1200℃. It can be clearly seen from the image that the degree of crack intensification in the Example is significantly less than that in the Comparative Example, indicating that modifying stainless steel fibers and adding modified ammonium polyphosphate and modified nano-alumina can effectively improve the problem of crack intensification caused by oxidation of traditional stainless steel fibers at high temperatures.

[0100] Experiment 2:

[0101] (1) Flexural strength at room temperature: The sample was prepared into a specimen of 150mm×25mm×25mm and dried at 110℃ for 24 hours. The flexural strength at room temperature was then tested.

[0102] (2) High temperature flexural strength: The sample was prepared into a 150mm×25mm×25mm specimen, dried at 110℃ for 24 hours, placed in a high temperature furnace, heated to 1200℃ at a rate of 200℃ / h, held for 3 hours, cooled to room temperature with the furnace, and the flexural strength was tested.

[0103] (3) Fracture toughness: The sample was prepared as a single-sided notched beam specimen of 25mm×50mm×200mm and dried at 110℃ for 24 hours. A pre-made notch was cut at the mid-span of the specimen using a diamond cutting disc, with a notch depth of 5mm±0.2mm (20% of the specimen height). The root of the notch was lightly polished with fine sandpaper to form a sharp crack tip. The fracture toughness was tested using the three-point bending method according to GB / T 23806-2009 standard.

[0104] (4) Thermal shock stability test: The sample is prepared into a cylindrical sample of Φ50mm×50mm and dried at 110℃ for 24 hours. It is then placed in a high-temperature furnace that has been heated to 1400℃ and kept warm for 30 minutes. The sample is quickly removed with crucible tongs and immediately immersed in a water bath at 20℃±2℃ for rapid cooling. It is kept in the water for 3 minutes, the sample is removed, the surface moisture is dried with compressed air, the crack condition is visually inspected, and the number and length of cracks are recorded. The above steps are repeated until the sample shows through cracks or is completely destroyed. The number of thermal shock cycles is recorded.

[0105] (5) Corrosion resistance test: The sample is prepared into a crucible-shaped sample of 70mm×70mm×70mm (with a Φ40mm×50mm cavity reserved in the center). It is dried at 110℃ for 24 hours. About 80g of pre-melted slag particles are loaded into the crucible cavity, with the slag surface about 10mm away from the crucible opening. The crucible containing slag is placed in a high-temperature furnace and heated to 1400℃ at a rate of 200℃ / h and held for 3 hours. It is then cooled to room temperature with the furnace. The crucible is longitudinally cut along the center line with a diamond cutter to remove the residue and measure the corrosion depth.

[0106] Table 2: Basic Properties of Dry Refractory Materials

[0107]

[0108] Table 2 shows the basic performance test results of the dry refractory materials. The results indicate that the basic performance of the dry refractory materials in the examples is significantly better than that of all comparative examples. Comparative example 8 has the worst performance because the unmodified fibers undergo severe oxidation during high-temperature sintering, resulting in degraded interfacial bonding and becoming crack initiation sites. Comparative example 7 also performed poorly, indicating that the synergistic toughening mechanism among the three is crucial for improving the mechanical properties of the materials.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dry refractory material composition with excellent crack propagation resistance, characterized in that, It includes the following components in parts by weight: 60-75 parts of refractory aggregate, 18-25 parts of refractory powder, 5-8 parts of binder, 3-6 parts of modified stainless steel fiber, 6-10 parts of modified ammonium polyphosphate, and 2-5 parts of modified nano alumina. The modified stainless steel fiber has a composite layer structure, consisting of, from the inside out: stainless steel fiber, Cu-Mn composite oxide layer, zirconium boride-silicate glass composite protective layer, and the outermost layer grafted with aminosilane and epoxysilane coupling agent. The modified ammonium polyphosphate has a core-shell structure, with the core being ammonium polyphosphate microspheres, the middle layer being mesoporous aluminosilicate, and the outer shell being a phosphate ester bridging layer with borate ester end caps. The modified nano-alumina has a surface bilayer modified structure, with the inner layer being rare earth oxide catalytic sites and the outer layer grafted with phosphate-boron ester bidentate ligands.

2. The dry refractory composition with excellent crack propagation resistance according to claim 1, characterized in that, The method for preparing the modified stainless steel fiber includes the following steps: S11. Immerse stainless steel fibers in H2SO4 solution, activate at room temperature, wash with deionized water, and dry to obtain pretreated stainless steel fibers. S12. Copper nitrate and manganese acetate were dissolved in anhydrous ethanol by stirring, citric acid was added, and the mixture was stirred evenly to obtain a precursor solution; the pretreated stainless steel fiber was immersed in the precursor solution, dried, fully impregnated-dried, and calcined to obtain the first compound. S13. Disperse ZrB2 powder, sodium hexametaphosphate and boric acid in anhydrous ethanol by ultrasonication, add silica sol and continue stirring to obtain a slurry; immerse the first compound in the slurry, perform ultrasonic-assisted impregnation, lift and drain, dry and calcine to obtain the second compound; S14. Dissolve KH550 and KH560 in anhydrous ethanol / deionized water mixed solvent, add glacial acetic acid to adjust the pH, stir and hydrolyze at room temperature to obtain silane solution; immerse the second compound in silane solution, react at room temperature, remove and vacuum dry, and heat-curing to obtain modified stainless steel fiber.

3. The dry refractory material composition with excellent crack propagation resistance according to claim 1, characterized in that, The preparation method of the modified ammonium polyphosphate includes the following steps: S21. Ammonium polyphosphate is heat-treated under nitrogen protection, cooled, and then anhydrous ethanol and melamine phosphate are added and ultrasonically dispersed to obtain an ammonium polyphosphate suspension. S22. Add hexadecyltrimethylammonium bromide to a suspension of ammonium polyphosphate, stir to dissolve, add ammonia to adjust the pH, and obtain a suspension; dissolve aluminum isopropoxide in isopropanol, add tetraethyl orthosilicate, stir evenly, slowly add to the suspension, stir the reaction at room temperature, centrifuge the obtained reaction solution to collect the solid, wash with anhydrous ethanol and deionized water alternately, dry, and calcine to obtain mesoporous aluminosilicate-coated ammonium polyphosphate; S23. Mesoporous aluminosilicate-coated ammonium polyphosphate is dispersed in anhydrous ethanol to obtain a suspension; 2-carboxyethylphenyl hypophosphoric acid, tris(hydroxymethyl)aminomethane, and boric acid are added sequentially to dimethyl sulfoxide and refluxed. The mixture is then added to the suspension, and KH550 is added. The mixture is stirred and reacted. The solid is collected by centrifugation and dried under vacuum to obtain modified ammonium polyphosphate.

4. The dry refractory composition with excellent crack propagation resistance according to claim 1, characterized in that, The preparation method of the modified nano-alumina includes the following steps: S31. Disperse nano-alumina in deionized water, add sodium citrate to obtain nano-alumina suspension; dissolve La(NO3)3·6H2O and Ce(NO3)3·6H2O in deionized water, slowly add them dropwise to the nano-alumina suspension, simultaneously add ammonia water to adjust the pH, stir the reaction, centrifuge the obtained reaction solution to collect the solid, wash with deionized water, dry, and calcine to obtain La2O3-CeO2 modified nano-alumina; S32. The La2O3-CeO2 modified nano-alumina was ultrasonically dispersed in anhydrous toluene to obtain a suspension; 2-carboxyethylphenyl hypophosphoric acid, phenylboronic acid and KH550 were added to anhydrous toluene in sequence and refluxed. The mixture was added to the suspension and refluxed again. The solid was collected by filtration, washed with anhydrous toluene, vacuum dried, heat-cured, ground and sieved to obtain modified nano-alumina.

5. The dry refractory composition with excellent crack propagation resistance according to claim 1, characterized in that, The preparation method of the dry refractory material composition includes the following steps: S1. Place refractory aggregate, refractory powder, and modified nano-alumina in a mixer and dry mix. Add a binder and mix. Then add modified ammonium polyphosphate and mix at low speed. Finally, add modified stainless steel fiber and continue mixing at low speed. Seal and age to obtain a dry refractory material composition.

6. The dry refractory composition with excellent crack propagation resistance according to claim 5, characterized in that, The refractory aggregate is corundum and magnesia in a mass ratio of 3:2, with a particle size of 0.5-8mm.

7. The dry refractory composition with excellent crack propagation resistance according to claim 5, characterized in that, The refractory powder consists of corundum powder, magnesia powder, high alumina powder, and silica powder in a mass ratio of 2:2:1:1, with a particle size of less than 0.088 mm.

8. The dry refractory composition with excellent crack propagation resistance according to claim 5, characterized in that, The binder is selected from one or more combinations of phenolic resin and water glass.

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