Refractory castable and preparation method thereof

Abstract

The invention belongs to the technical field of castable, and relates to a refractory castable and a preparation method thereof. The invention provides a refractory castable taking a rare earth compound as a base material. The refractory castable comprises a first composite refractory material, a second composite refractory material, a binding agent, a water reducing agent and water, the first composite refractory material is composed of a first refractory framework and a first auxiliary agent; the first fireproof framework comprises rare earth compound powder; the second composite refractory material is composed of a second refractory framework and a second auxiliary agent; the second fireproof framework comprises rare earth compound powder; the rare earth compound powder is selected from one or more of cerium oxide, lanthanum oxide, neodymium oxide and yttrium oxide; the stability and corrosion resistance of the high-temperature industrial equipment can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of castable refractories and relates to a refractory castable and a preparation method thereof. BACKGROUND

[0002] Refractory castable is an amorphous refractory material mainly composed of refractory aggregate, powder, binder and additive, which has good fluidity, convenient construction and strong adaptability, and is widely used in high-temperature industrial fields such as steel, cement and chemical industry. Its performance directly affects the service life and safety of high-temperature equipment, and its core performance requirements include high-temperature stability, corrosion resistance and high-temperature mechanical properties, which need to maintain structural integrity and functional effectiveness in long-term high-temperature environment.

[0003] Although traditional refractory castables meet the needs of high-temperature industrial fields to some extent, there are still deficiencies in high-temperature stability, corrosion resistance and high-temperature mechanical properties. This is mainly due to the fact that the composition, ratio and preparation process of the refractory castable are not optimized, resulting in decreased refractory performance, insufficient stability, deteriorated high-temperature mechanical properties, and thus affecting the long-term reliability, service life and safety of high-temperature equipment.

[0004] Therefore, it is necessary to improve the formula and preparation process of refractory castable to better apply it to high-temperature industrial fields. SUMMARY

[0005] The application proposes a new refractory castable and a preparation method thereof, aiming to solve the problems existing in the prior art. The refractory castable of the application significantly improves the high-temperature stability and corrosion resistance of the refractory castable by selecting suitable refractory aggregate, powder, introducing specific binder and additive, and combining with optimized preparation process.

[0006] To achieve the above-mentioned purpose, the technical scheme of the application is as follows: The application provides a refractory castable, which is a refractory castable taking a rare earth compound as a base material, and comprises a first composite refractory material, a second composite refractory material, a binder, a water reducing agent and water. The first composite refractory material is composed of a first refractory framework and a first additive. The first refractory framework is composed of silicon carbide aggregate, mullite aggregate, aluminum titanate aggregate and rare earth compound powder. The preparation method of the first additive is as follows: A mixture of polydimethylsiloxane, terpineol, trimethyl borate and rare earth compound powder is added into a mixture of nano-silicon dioxide, silane coupling agent KH-570 and glycerol, and ultrasonic dispersion is carried out until uniform, and then reaction is carried out at 55-60 DEG C for 6-7 h, and after cleaning and drying, grinding is carried out to a particle size of 45 μm or less, and the first additive is obtained. The second composite refractory material is composed of a second refractory skeleton and a second auxiliary agent; The second refractory skeleton is composed of silicon nitride aggregate, chrome corundum aggregate and rare earth compound powder; The preparation method of the second auxiliary agent is as follows: After mixing the aluminum dihydrogen phosphate solution, aluminum oxide micro-powder and rare earth compound powder, calcium gluconate is added as a catalyst, and the mixture is reacted at 85-90℃ for 2.5-3h to generate a rare earth-containing aluminum phosphate precursor, which is ball-milled to a particle size of less than 2μm, dried at 120℃, and calcined at 750℃ for 1-1.5h to obtain the second auxiliary agent; The rare earth compound powder is selected from one or more of cerium oxide, lanthanum oxide, neodymium oxide and yttrium oxide, and the particle size of the rare earth compound powder is less than 45μm; The binding agent is silicon sol and calcium aluminate cement at a mass ratio of 3:1; The water reducing agent is sodium tripolyphosphate.

[0007] Preferably, the refractory castable comprises 50-60 parts of the first composite refractory material, 35-45 parts of the second composite refractory material, 4.5-6 parts of the binding agent, 0.2-0.3 parts of the water reducing agent and 5-6 parts of water, by weight.

[0008] Preferably, the mass ratio of the first refractory skeleton to the first auxiliary agent is 92-95:5-8.

[0009] Preferably, the mass ratio of the second refractory skeleton to the second auxiliary agent is 94-96:4-6.

[0010] Preferably, the first refractory skeleton is composed of 35-45 parts of silicon carbide aggregate, 25-30 parts of mullite aggregate, 15-20 parts of aluminum titanate aggregate and 3-5 parts of rare earth compound powder, by weight.

[0011] More preferably, the rare earth compound powder is yttrium oxide and cerium oxide at a mass ratio of 3:1.

[0012] Preferably, the second refractory skeleton is composed of 35-45 parts of silicon nitride aggregate, 25-35 parts of chrome corundum aggregate and 4-6 parts of rare earth compound powder, by weight.

[0013] More preferably, the rare earth compound powder is lanthanum oxide and neodymium oxide at a mass ratio of 2:1.

[0014] Preferably, The mass ratio of polydimethylsiloxane, terpineol, trimethyl borate and rare earth compound powder is 5:3:1:1; The mass ratio of nano-silicon dioxide, silane coupling agent KH-570 and glycerol is 5:1:2.

[0015] More preferably, the rare earth compound powder is cerium oxide.

[0016] Preferably, the mass ratio of the aluminum dihydrogen phosphate solution, the aluminum oxide micro-powder, the rare earth compound powder and the calcium gluconate is 10:3:1:0.2, and the aluminum dihydrogen phosphate solution is a solution with a mass concentration of 50%.

[0017] More preferably, the rare earth compound powder is lanthanum oxide.

[0018] In a second aspect, a preparation method of the refractory castable is provided, and the preparation method comprises the following steps: 1) Preparation of the first composite refractory material The components of the first refractory framework are put into a mixer and mixed at 45 r / min for 60 s, and the first additive is added and mixed at 90 r / min for 120 s to obtain the first composite refractory material. 2) Preparation of the second composite refractory material The components of the second refractory framework are put into a mixer and mixed at 45 r / min for 60 s, and the second additive is added and mixed at 90 r / min for 120 s to obtain the second composite refractory material. 3) Mixing of the castable The silica sol and the calcium aluminate cement are first stirred at a mass ratio of 3:1 for 30 s, and then water is added and stirred for another 30 s to form a binder mother liquor. The first composite refractory material and the second composite refractory material are simultaneously put into a mixer and mixed at 45 r / min for 60 s, and the water reducing agent is scattered and mixed for 60 s within 30-60 s; and the binder mother liquor is slowly added while stirring at 90 r / min for 90-120 s.

[0019] In a third aspect, the refractory castable is applied to improving the high-temperature stability and / or corrosion resistance of high-temperature industrial equipment.

[0020] Compared with the prior art, the present application has the following advantages: By selecting appropriate refractory aggregates, powders, introducing specific binders and additives, and combining with an optimized preparation process, the high-temperature stability and corrosion resistance of the refractory castable are significantly improved, and the present application also has good high-temperature mechanical properties. Regarding the high-temperature stability: The first refractory framework is filled with specific rare earth oxides (yttrium oxide and cerium oxide) to fill the interstitial gaps, inhibit the phase transition, and strengthen the integrity of the framework structure. The first additive forms an additive film on the surface of the first refractory framework particles, which fills the micropores of the framework particles and enhances the interfacial bonding force between the framework particles. The additive film can reduce the erosion rate of impurities on the framework at high temperature, and the dense phase formed by the reaction of the first additive and the first refractory framework can relieve thermal stress concentration and reduce the risk of high-temperature deformation and cracking, thereby improving the high-temperature structural stability.

[0021] The second refractory framework is filled with specific rare earth oxides (lanthanum oxide and neodymium oxide) to promote grain refinement and strengthen the grain boundary. The aluminum phosphate-based phase generated by the reaction and calcination of the second additive forms a continuous protective layer on the interface of the second refractory aggregate, which blocks the penetration of oxygen and inhibits high-temperature oxidation, and the microcrystalline structure generated by the catalysis of calcium gluconate can relieve thermal stress, ensuring the structural integrity of the second composite refractory material at high temperature.

[0022] Regarding corrosion resistance: The silicon carbide and mullite of the first refractory framework have strong chemical inertness, and the reaction of rare earth compounds (yttrium oxide and cerium oxide) with the erosion medium generates a high-melting-point, stable rare earth composite phase, forming a dense barrier on the surface of the framework. At the same time, the dense phase generated by the reaction of the first additive and the first refractory framework can reduce the penetration of acid, alkali, and other media along the interface, further improving the corrosion resistance.

[0023] The silicon nitride and chrome corundum of the second refractory framework have good corrosion resistance, and the reaction of rare earth compounds with molten slag and chemical media generates a difficult-to-dissolve composite phase that can wrap the erosive ions. At the same time, the corrosion-resistant buffer layer formed by the reaction of the aluminum phosphate-based phase generated by the calcination of the second additive and the second refractory framework can fill the pores and cut off the erosion channels, and the protective film formed by the second additive on the surface of the second refractory framework can prevent further erosion, further enhancing the corrosion resistance.

[0024] Regarding high-temperature mechanical properties: The rare earth compounds in the first and second refractory frameworks can enhance the strength of the framework. The silane coupling agent KH-570 of the first additive enhances the interfacial bonding force between the first refractory framework and the first additive, making the stress transfer more uniform and avoiding cracking and damage caused by local stress concentration. On the other hand, the aluminum phosphate-based phase in the second additive forms a chemical bond with the framework through reaction, fills the pores, and improves the density, and the microcrystalline structure generated by calcination can pin the dislocation motion, improving the creep resistance and bending strength of the material at high temperature.

[0025] In addition, the binding agent of the application can form a gradient reinforced structure by reacting with the framework and the auxiliary agent during the sintering process; the water reducing agent of the application can optimize the fluidity and reduce the forming defects; and the refractory castable can maintain the structural integrity and functional effectiveness when subjected to mechanical loads such as scouring and extrusion in high-temperature industrial equipment.

[0026] In summary, the application realizes the performance improvement of the refractory castable for high-temperature industrial equipment from the aspects of structural stability, erosion resistance and mechanical properties by matching the components of the first refractory framework and the first auxiliary agent, and the second refractory framework and the second auxiliary agent. DETAILED DESCRIPTION

[0027] The advantages and various effects of the application will be more clearly presented by the following specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the application, but not to limit the application.

[0028] In the following, the technical solutions of the application will be described in conjunction with examples, but the application is not limited to the following examples. The experimental methods and detection methods described in each example are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0029] In the embodiments of the application, the particle size of the silicon carbide aggregate is 0.1-5mm, the particle size of the mullite aggregate is 1-3mm, the particle size of the aluminum titanate aggregate is 0.5-1mm, the particle size of the silicon nitride aggregate is 0.5-2mm, the particle size of the chrome corundum aggregate is 1-5mm, and the particle size of the alumina micropowder is 0.5-1mm.

[0030] Example 1 The refractory castable provided in this embodiment is a refractory castable with rare earth compounds as the base material, which comprises 50 parts of a first composite refractory material, 35 parts of a second composite refractory material, 4.5 parts of a binding agent, 0.2 parts of a water reducing agent and 5 parts of water, according to the weight fraction. The first composite refractory material is composed of a first refractory framework and a first auxiliary agent, and the mass ratio of the first refractory framework to the first auxiliary agent is 92:8. The first refractory framework is composed of 35 parts of silicon carbide aggregate, 25 parts of mullite aggregate, 15 parts of aluminum titanate aggregate and 3 parts of rare earth compound powder (yttrium oxide and cerium oxide with a mass ratio of 3:1 and a particle size of 45μm or less) according to the weight fraction. The preparation method of the first auxiliary agent is as follows: A mixture of polydimethylsiloxane, terpineol, trimethyl borate and rare earth compound powder (cerium oxide, particle size below 45 μm) was added to a mixture of nano-silicon dioxide (Shanghai Yunfu Nanometer Technology Co., Ltd., CAS: 60676-86-0), silane coupling agent KH-570 and glycerol, and ultrasonically dispersed uniformly, reacted at 55°C for 6 h, washed and dried, and ground to a particle size below 45 μm to obtain the product; The mass ratio of polydimethylsiloxane, terpineol, trimethyl borate and rare earth compound powder (cerium oxide, particle size below 45 μm) was 5:3:1:1. The mass ratio of nano-silicon dioxide, silane coupling agent KH-570 and glycerol was 5:1:2. The second composite refractory material was composed of a second refractory framework and a second additive, and the mass ratio of the second refractory framework to the second additive was 94:6. The second refractory framework was composed of 35 parts of silicon nitride aggregate, 25 parts of chrome corundum aggregate and 4 parts of rare earth compound powder (mass ratio of lanthanum oxide to neodymium oxide was 2:1, and particle size was below 45 μm). The preparation method of the second additive was as follows: The aluminum dihydrogen phosphate solution, aluminum oxide powder and rare earth compound powder (lanthanum oxide, particle size below 45 μm) were mixed, and then calcium gluconate was added as a catalyst, and the mixture was reacted at 85°C for 2.5 h to generate an aluminum phosphate precursor containing rare earth, and then ball-milled to a particle size below 2 μm, dried at 120°C, and calcined at 750°C for 1 h to obtain the product. The mass ratio of the aluminum dihydrogen phosphate solution, aluminum oxide powder, rare earth compound powder (lanthanum oxide, particle size below 45 μm) and calcium gluconate was 10:3:1:0.2, and the aluminum dihydrogen phosphate solution was a solution with a mass concentration of 50%. The binder was a mixture of silica sol (solid content 30%, colloidal particle size 15-25 nm) and calcium aluminate cement (CA-70 grade) with a mass ratio of 3:1. The water reducing agent was sodium tripolyphosphate.

[0031] Example 2 The present example provides a refractory castable, which is a refractory castable taking a rare earth compound as a base material, and the refractory castable comprises 60 parts of a first composite refractory material, 45 parts of a second composite refractory material, 6 parts of a binder, 0.3 parts of a water reducing agent and 6 parts of water, according to weight fractions. The first composite refractory material was composed of a first refractory framework and a first additive, and the mass ratio of the first refractory framework to the first additive was 95:5. The first refractory framework is composed of 45 parts of silicon carbide aggregate, 30 parts of mullite aggregate, 20 parts of aluminum titanate aggregate and 5 parts of rare earth compound powder (mass ratio of yttrium oxide and cerium oxide is 3:1, particle size is below 45 μm); The preparation method of the first additive is as follows: The mixture of polydimethylsiloxane, terpene-1,8-diol, trimethyl borate and rare earth compound powder (cerium oxide, particle size is below 45 μm) is added into the mixture of nano-silicon dioxide, silane coupling agent KH-570 and glycerol, and then ultrasonic dispersion is performed to obtain uniformity, and then 60℃ reaction is performed for 7 hours, and then cleaning and drying are performed, and then grinding is performed to obtain particle size below 45 μm, and then the first additive is obtained. The mass ratio of polydimethylsiloxane, terpene-1,8-diol, trimethyl borate and rare earth compound powder (cerium oxide, particle size is below 45 μm) is 5:3:1:1. The mass ratio of nano-silicon dioxide, silane coupling agent KH-570 and glycerol is 5:1:2. The second composite refractory material is composed of the second refractory framework and the second additive, and the mass ratio of the second refractory framework and the second additive is 96:4. The second refractory framework is composed of 45 parts of silicon nitride aggregate, 35 parts of chrome corundum aggregate and 6 parts of rare earth compound powder (mass ratio of lanthanum oxide and neodymium oxide is 2:1, particle size is below 45 μm); The preparation method of the second additive is as follows: The aluminum dihydrogen phosphate solution, aluminum oxide powder and rare earth compound powder (lanthanum oxide, particle size is below 45 μm) are mixed, then calcium gluconate is added as a catalyst, and then 90℃ reaction is performed for 3 hours to generate an aluminum phosphate precursor containing rare earth, and then ball milling is performed to obtain particle size below 2 μm, and then 120℃ drying is performed, and then calcination is performed at 750℃ for 1.5 hours, and then the second additive is obtained. The mass ratio of the aluminum dihydrogen phosphate solution, aluminum oxide powder, rare earth compound powder (lanthanum oxide, particle size is below 45 μm) and calcium gluconate is 10:3:1:0.2, and the aluminum dihydrogen phosphate solution is a solution with a mass concentration of 50%. The binding agent is silicon sol and calcium aluminate cement (CA-70 grade) with a mass ratio of 3:1. The water reducing agent is sodium tripolyphosphate.

[0032] Example 3 The present embodiment provides a refractory castable, which is a refractory castable taking a rare earth compound as a base material, and the refractory castable includes 55 parts of a first composite refractory material, 40 parts of a second composite refractory material, 5 parts of a binding agent, 0.25 parts of a water reducing agent and 5.5 parts of water according to weight fraction. The first composite refractory material is composed of the first refractory framework and the first additive, and the mass ratio of the first refractory framework and the first additive is 93:7. The first refractory framework is composed of 40 parts of silicon carbide aggregate, 28 parts of mullite aggregate, 18 parts of aluminum titanate aggregate and 4 parts of rare earth compound powder (mass ratio of yttrium oxide and cerium oxide is 3:1, particle size is below 45 μm) according to weight parts; The preparation method of the first additive is as follows: The mixture of polydimethylsiloxane, terpene-4-ol, trimethyl borate and rare earth compound powder (cerium oxide, particle size is below 45 μm) is added into the mixture of nano-silicon dioxide, silane coupling agent KH-570 and glycerol, and then ultrasonic dispersion is performed until uniform, 60℃ reaction is performed for 7h, and then cleaning, drying and grinding to particle size below 45 μm are performed to obtain the first additive; The mass ratio of polydimethylsiloxane, terpene-4-ol, trimethyl borate and rare earth compound powder (cerium oxide, particle size is below 45 μm) is 5:3:1:1; The mass ratio of nano-silicon dioxide, silane coupling agent KH-570 and glycerol is 5:1:2; The second composite refractory material is composed of the second refractory framework and the second additive, and the mass ratio of the second refractory framework and the second additive is 95:5; The second refractory framework is composed of 40 parts of silicon nitride aggregate, 30 parts of chrome corundum aggregate and 5 parts of rare earth compound powder (mass ratio of lanthanum oxide and neodymium oxide is 2:1, particle size is below 45 μm) according to weight parts; The preparation method of the second additive is as follows: The aluminum dihydrogen phosphate solution, aluminum oxide powder and rare earth compound powder (lanthanum oxide, particle size is below 45 μm) are mixed, then calcium gluconate is added as a catalyst, 90℃ reaction is performed for 3h to generate the rare earth-containing aluminum phosphate precursor, ball milling is performed to particle size below 2 μm, 120℃ drying is performed, and then 750℃ calcination is performed for 1.5h to obtain the second additive; The mass ratio of the aluminum dihydrogen phosphate solution, aluminum oxide powder, rare earth compound powder (lanthanum oxide, particle size is below 45 μm) and calcium gluconate is 10:3:1:0.2, and the aluminum dihydrogen phosphate solution is a solution with a mass concentration of 50%; The binding agent is silicon sol and calcium aluminate cement (CA-70 grade) with a mass ratio of 3:1; The water reducing agent is sodium tripolyphosphate.

[0033] Example 4 The present embodiment provides a preparation method of refractory castable, which comprises the following steps: 1) Preparation of the first composite refractory material The components of the first refractory framework are put into a stirrer according to weight parts, pre-dispersed by mixing at 45r / min for 60s, and then the first additive is continuously mixed at 90r / min for 120s to obtain the first composite refractory material; 2) Preparation of the second composite refractory material The second refractory framework components are put into a stirrer at 45 r / min, mixed for 60 s for pre-dispersion, and the second additive is added and mixed at 90 r / min for 120 s, to obtain the second composite refractory material; 3) Mixing of castable The silica sol and calcium aluminate cement are first stirred at a mass ratio of 3:1 for 30 s, then water is added and stirred for another 30 s, to form a binder mother liquor; The first composite refractory material and the second composite refractory material are simultaneously put into a stirrer and mixed at 45 r / min for 60 s for preliminary homogenization, and the water reducing agent is uniformly scattered and mixed for 60 s within 30-60 s; then the binder mother liquor is slowly added while stirring, and mixed at 90 r / min for 90-120 s.

[0034] Comparative Example 1 This comparative example is the same as Example 3, except that the polydimethylsiloxane in the first additive is replaced by polymethylphenylsiloxane.

[0035] Comparative Example 2 This comparative example is the same as Example 3, except that the aluminum oxide powder in the second additive is replaced by aluminum hydroxide (particle size of 1-5 μm).

[0036] Comparative Example 3 This comparative example is the same as Example 3, except that the first additive is not added.

[0037] Effect verification Experimental object: the refractory castable prepared according to Example 4 in Examples 1-3 and Comparative Examples 1-3; Experimental method: High-temperature stability detection standard: test the line change rate according to GB / T 5988-2022; Corrosion resistance detection standard: test the acid resistance according to GB / T 17601-2023; High-temperature mechanical property detection standard: test the compressive strength according to GB / T 5072-2023, and test the flexural strength according to GB / T 3001-2017; Experimental results: as shown in Table 1.

[0038] Table 1: Performance test results of each group of refractory castables

[0039] In order to further prove the effect of the present application, the pinol, trimethyl borate, rare earth compound powder, nano silicon dioxide, silane coupling agent KH-570 and glycerol in the first additive are replaced by other substances with similar properties, respectively, and the other conditions are the same as those in Example 3, and it is found that the effect is comparable to that of Comparative Example 1.

[0040] In order to further prove the effect of the present application, the aluminum dihydrogen phosphate solution, the rare earth compound powder and the calcium gluconate in the second auxiliary agent are replaced by other substances with similar properties respectively, and the rest of the conditions are consistent with Example 3, and it is found that the effect is equivalent to that of Comparative Example 2.

[0041] In order to further prove the effect of the present application, the second auxiliary agent is not added, and the rest of the conditions are consistent with Example 3, and it is found that the effect is equivalent to that of Comparative Example 3.

[0042] The linear change rate of the refractory castable is a core index of high-temperature stability, and the lower the value, the better the material performance. As can be seen from Table 1, the high-temperature stability of the refractory castable of the present application is relatively good, specifically 0.07-0.12, among which the high-temperature stability of the refractory castable of Example 3 is the best. The high-temperature stability of the refractory castables of Comparative Examples 1-3 is relatively poor. The corrosion resistance of the refractory castable of the present application is relatively good, and the acid etching mass loss rate is specifically 0.8-1.3, while the corrosion resistance of the refractory castables of Comparative Examples 1-3 is relatively poor. At the same time, the compressive strength and the bending strength of the refractory castable of the present application are also relatively good. It can be seen that compared with the refractory castable not using the formulation system of the present application, the refractory castable using the formulation system of the present application not only improves the high-temperature stability and corrosion resistance, but also has good high-temperature mechanical properties.

[0043] As can be seen from the effect verification experiment, by selecting suitable refractory aggregate, powder, introducing specific binding agent and admixture, and combining with optimized preparation process, the high-temperature stability and corrosion resistance of the refractory castable are significantly improved, and the present application also has good high-temperature mechanical properties. Specifically, Regarding high-temperature stability: the first refractory skeleton, with the help of specific rare earth oxides (yttrium oxide and cerium oxide), fills the lattice gap, inhibits the phase transition, and strengthens the integrity of the skeleton structure. The first auxiliary agent forms an auxiliary agent film on the surface of the first refractory skeleton particles, which on the one hand fills the micropores of the skeleton particles, and on the other hand enhances the interfacial bonding force between the skeleton particles. The auxiliary agent film can reduce the erosion rate of impurities on the skeleton at high temperature, and the dense phase formed by the reaction of the first auxiliary agent and the first refractory skeleton can relieve thermal stress concentration and reduce the risk of high-temperature deformation and cracking, thereby improving the high-temperature structural stability. The second refractory skeleton, with the help of specific rare earth oxides (lanthanum oxide and neodymium oxide), promotes the grain refinement and grain boundary strengthening of the skeleton phase. The aluminum phosphate-based phase generated by the reaction and calcination of the second auxiliary agent forms a continuous protective layer at the interface of the second refractory aggregate, which blocks the penetration of oxygen and inhibits the high-temperature oxidation reaction, and the microcrystalline structure catalyzed by calcium gluconate can relieve thermal stress, ensuring the structural integrity of the second composite refractory material at high temperature.

[0044] Regarding corrosion resistance: the first refractory skeleton of silicon carbide, mullite, etc. is inherently chemically inert, and the rare earth compounds (yttrium oxide and cerium oxide) react with the corrosive medium to form a high-melting-point, stable rare earth complex phase, forming a dense barrier on the surface of the skeleton. At the same time, the dense phase generated by the reaction of the first additive with the first refractory skeleton can reduce the penetration of acid, alkali and other media along the interface, further improving the corrosion resistance. The second refractory skeleton of silicon nitride and chrome corundum has good anti-corrosion foundation, and the rare earth compounds react with the slag and chemical medium to form a complex phase that is difficult to dissolve, which can wrap the corrosive ions. At the same time, the corrosion-resistant buffer layer formed by the reaction of the aluminum phosphate-based phase generated by the calcination of the second additive with the second refractory skeleton can fill the pores and cut off the corrosion channel, and the protective film formed by the second additive on the surface of the second refractory skeleton can prevent further corrosion, further enhancing the corrosion resistance.

[0045] Regarding high-temperature mechanical properties: the rare earth compounds in the first and second refractory skeletons can enhance the strength of the skeleton itself. The silane coupling agent KH-570 of the first additive enhances the interfacial bonding force of the first refractory skeleton and the first additive, making stress transfer more uniform and avoiding cracking and damage caused by local stress concentration. On the other hand, the aluminum phosphate-based phase in the second additive forms a chemical bond with the skeleton through reaction, fills the pores and improves the density, and the microcrystalline structure generated by calcination can pin the dislocation motion, improving the creep resistance and bending strength of the material at high temperature.

[0046] In addition, the binder of the present application can form a gradient strengthening structure by reacting with the skeleton and the additive during the sintering process; the water reducing agent optimizes the fluidity and can reduce the forming defects; and ensures that the refractory castable maintains structural integrity and functional effectiveness when subjected to mechanical loads such as erosion and extrusion in high-temperature industrial equipment.

[0047] As can be seen, the present application realizes the performance improvement of refractory castables for high-temperature industrial equipment by the composition of the first refractory skeleton and the first additive, and the second refractory skeleton and the second additive from the aspects of structural stability, corrosion resistance and mechanical properties.

[0048] In summary, the formula system of the refractory castable provided by the present application is a whole, specifically, each raw material in the refractory castable supports each other in function and has a mutual interaction relationship, and it is because each raw material supports each other in function and has a mutual interaction relationship that the refractory castable of the formula system of the present application can be well used in high-temperature industrial equipment.

[0049] It should be understood that the disclosed application is not limited to the specific methods, schemes and substances described, as these can vary. It should also be understood that the terms used herein are for the purpose of describing specific implementation schemes only and are not intended to limit the scope of the application, which is limited only by the appended claims.

Claims

1. A refractory castable which is a refractory castable using a rare earth compound as a binder, characterized by comprising: The refractory castable comprises a first composite refractory material, a second composite refractory material, a binding agent, a water reducing agent and water; ​ The first composite refractory material is composed of a first refractory skeleton and a first auxiliary agent; The first refractory skeleton is composed of silicon carbide aggregate, mullite aggregate, aluminum titanate aggregate and rare earth compound powder; The preparation method of the first auxiliary agent is as follows: The mixture of polydimethylsiloxane, terpineol, trimethyl borate and rare earth compound powder is added into the mixture of nano-silicon dioxide, silane coupling agent KH-570 and glycerol, and then uniformly dispersed by ultrasonic, and then reacted at 55-60℃ for 6-7h, and then cleaned and dried, and then ground to a particle size of less than 45μm to obtain the first auxiliary agent; The second composite refractory material is composed of a second refractory skeleton and a second auxiliary agent; The second refractory skeleton is composed of silicon nitride aggregate, chrome corundum aggregate and rare earth compound powder; The preparation method of the second auxiliary agent is as follows: The mixture of aluminum dihydrogen phosphate solution, aluminum oxide micro powder and rare earth compound powder is mixed, and then calcium gluconate is added as a catalyst, and then reacted at 85-90℃ for 2.5-3h to generate rare earth-containing aluminum phosphate precursor, and then ball milled to a particle size of less than 2μm, and then dried at 120℃, and then calcined at 750℃ for 1-1.5h to obtain the second auxiliary agent; The rare earth compound powder is selected from one or more of cerium oxide, lanthanum oxide, neodymium oxide and yttrium oxide; The binding agent is silica sol and calcium aluminate cement with a mass ratio of 3:1; The water reducing agent is sodium tripolyphosphate.

2. A refractory castable according to claim 1, characterized in that The refractory castable comprises 50-60 parts of the first composite refractory material, 35-45 parts of the second composite refractory material, 4.5-6 parts of the binding agent, 0.2-0.3 parts of the water reducing agent and 5-6 parts of water.

3. A refractory castable according to claim 1, characterized in that The mass ratio of the first refractory skeleton and the first auxiliary agent is 92-95:5-8.

4. A refractory castable according to claim 1, characterized in that The mass ratio of the second refractory skeleton and the second auxiliary agent is 94-96:4-6.

5. A refractory castable according to claim 1, characterized in that The first refractory skeleton is composed of 35-45 parts of silicon carbide aggregate, 25-30 parts of mullite aggregate, 15-20 parts of aluminum titanate aggregate and 3-5 parts of rare earth compound powder.

6. A refractory castable according to claim 1, characterized in that The second refractory skeleton is composed of 35-45 parts of silicon nitride aggregate, 25-35 parts of chrome corundum aggregate and 4-6 parts of rare earth compound powder.

7. The refractory castable according to claim 1, wherein The mass ratio of polydimethylsiloxane, terpineol, trimethyl borate and rare earth compound powder is 5:3:1:1; The mass ratio of nano-silicon dioxide, silane coupling agent KH-570 and glycerol is 5:1:

2.

8. A refractory castable according to claim 1, characterized in that The mass ratio of aluminum dihydrogen phosphate solution, aluminum oxide micro powder, rare earth compound powder and calcium gluconate is 10:3:1:0.

2.

9. Process for the production of a refractory castable according to any one of claims 1 to 8, characterized in that, The preparation method comprises the following steps: 1) Preparation of the first composite refractory material The components of the first refractory skeleton are put into a blender and mixed at 45r / min for 60s, and then the first auxiliary agent is added and mixed at 90r / min for 120s to obtain the first composite refractory material; 2) Preparation of the second composite refractory material The components of the second refractory skeleton are put into a blender and mixed at 45r / min for 60s, and then the second auxiliary agent is added and mixed at 90r / min for 120s to obtain the second composite refractory material; 3) Mixing of castable The silica sol and calcium aluminate cement are first stirred at a mass ratio of 3:1 for 30 s, then water is added and stirred for another 30 s to form a binder mother liquor; The first and second composite refractory materials are simultaneously put into a mixer and mixed at 45 r / min for 60 s, and a water reducing agent is sprinkled and mixed for another 60 s within 30-60 s; the binder mother liquor is slowly added while stirring at 90 r / min for 90-120 s.

10. Use of the refractory castable according to any one of claims 1-8 to improve the high-temperature stability and / or corrosion resistance of high-temperature industrial equipment.

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