Composite refractory brick and preparation method thereof

Abstract

The invention discloses a composite refractory brick and a preparation method thereof, and relates to the technical field of refractory materials. The expansion layer is arranged between the insulating brick and the refractory layer; the refractory layer comprises quartz sand and aluminum titanate, the expansion layer is made of aluminum silicate fibers, and the heat preservation bricks comprise Portland cement, silicon carbide and a binder. According to the refractory brick, the insulating brick with a good insulating effect is arranged in the refractory brick, then the refractory layer with higher fire resistance is arranged on the outer layer, and the expansion layer is arranged in the middle, so that the whole refractory brick has good insulating performance on the basis of resistance to high temperature of 1700 DEG C; and the expansion layer is arranged, so that the situation that the outer refractory layer is extruded to crack due to thermal expansion of the internal insulating bricks can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and specifically relates to a composite refractory brick and a preparation method thereof. Background Art

[0002] Composite refractory bricks are a kind of building materials used in high-temperature environments, mainly used in industrial furnaces, kilns and other scenarios that need to resist high temperatures. They have good heat resistance and chemical stability, and can withstand physical and chemical erosion at extreme temperatures.

[0003] Most of the composite refractory bricks in the prior art are used in combination with multiple different types of composite refractory bricks. Because the expansion coefficients of various types of composite refractory bricks are different, different widths of expansion gaps need to be reserved between layers during construction to avoid mutual extrusion at high temperatures and situations such as cracks that affect safety performance. The design is relatively complex, and during the construction process using different types of composite refractory bricks, it is also necessary to pay attention to avoiding the situation of mixing different types of composite refractory bricks, which is rather cumbersome. Summary of the Invention

[0004] The present invention aims to solve the disadvantages in the background art, and provides a composite refractory brick, a preparation method thereof and a seal, which at least solve some of the technical problems in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for a composite refractory brick, comprising a refractory layer, an expansion layer and a heat-insulating brick, wherein the expansion layer is arranged between the heat-insulating brick and the refractory layer; Among them, the refractory layer comprises quartz sand and aluminum titanate, the material of the expansion layer is aluminosilicate fiber, and the heat-insulating brick comprises portland cement, silicon carbide and a binder.

[0006] Further, the refractory layer comprises the following materials in parts by weight: 40 - 60 parts of quartz sand and 10 - 15 parts of aluminum titanate.

[0007] Further, the particle size range of the quartz sand is 4000 mesh - 6000 mesh, and the purity of the quartz sand is greater than 99.99%.

[0008] Further, the particle size distribution of the quartz sand is: 10% of quartz sand with a particle size of 4000 mesh - 4200 mesh, 40% of quartz sand with a particle size of 4800 mesh - 5000 mesh, 40% of quartz sand with a particle size of 5400 mesh - 5600 mesh, and 10% of quartz sand with a particle size of 5800 mesh - 6000 mesh.

[0009] Further, the heat-insulating brick comprises the following materials in parts by weight: 80 - 100 parts of portland cement, 10 - 20 parts of silicon carbide and 4 - 8 parts of binder.

[0010] Further, the binder includes an organic binder and an inorganic binder, and the mass ratio of the organic binder to the inorganic binder is (1 - 2):1; The organic binder includes one or more of cellulose ether, lignin-based binder, and diethyl dibutylmalonate, and the inorganic binder includes one or more of sodium silicate, water glass, silica sol, aluminum phosphate, and aluminum dihydrogen phosphate.

[0011] On the other hand, the present invention also provides a method for preparing a composite refractory brick, comprising the following steps: Mix 80 - 100 parts of portland cement, 10 - 20 parts of silicon carbide, and 4 - 8 parts of binder evenly, then put them into a mold and let stand for 68h - 84h, and then demold to obtain a heat-insulating brick; Uniformly wrap the expansion layer on the heat-insulating brick, and then place it in a mold; Mix 40 - 60 parts of quartz sand, 10 - 15 parts of aluminum titanate, and water evenly to form a quartz slurry; Inject the quartz slurry into the mold, remove air bubbles in the quartz slurry in the mold under vacuum, and then let it stand for molding; Demold the formed composite structure, and then send it into a sintering furnace for high-temperature sintering and curing.

[0012] Further, 80 - 100 parts of portland cement, 10 - 20 parts of silicon carbide, and 4 - 8 parts of binder are successively put into a mixer and stirred evenly, and then the evenly stirred mixture is sent into a mold and formed into a brick body by vibration and pressure, and the pressure of the pressure is 3MPa - 3.5MPa; After molding, steam curing is carried out for 16h - 24h, the curing temperature is 80℃ - 95℃, and then it is naturally air-dried.

[0013] Further, the expansion layer is a refractory fiber waterproof cloth made of aluminum silicate, the thickness of the expansion layer is 2 - 4mm, the thickness of the refractory layer is 10 - 15mm, and the size of the heat-insulating brick is (37 - 61)mm × (77 - 101)mm × (192 - 216)mm.

[0014] Further, the degree of vacuum during the vacuum degassing process is 0.3MPa - 0.1MPa, and the sintering temperature of the high-temperature sintering is 1000℃ - 1100℃.

[0015] The beneficial effects of the present invention: (1) By arranging a heat-insulating brick with good heat-insulating effect inside the refractory brick, then arranging a refractory layer with stronger refractory performance on the outer layer, and arranging an expansion layer in the middle, the whole can have good heat-insulating performance on the basis of being able to withstand high temperatures of 1700 °C, and arranging the expansion layer can prevent the internal heat-insulating brick from causing extrusion and cracks to the outer refractory layer due to thermal expansion.

[0016] (2) By preparing the refractory layer with high-purity quartz sand as the base, the overall expansion coefficient of the refractory layer is extremely low and basically remains unchanged under high-temperature conditions. The clay layer during construction also has a certain degree of stretchability, so that the problem of expansion joints basically does not need to be considered during construction and design, reducing the construction difficulty and design difficulty. Brief Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the present invention; In the figure, 1 - refractory layer; 2 - expansion layer; 3 - heat-insulating brick. Specific Embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

[0019] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0020] In the prior art, in industrial scenarios that require resistance to high temperatures, refractory bricks are an extremely important part. When designing the construction, it is necessary to consider the expansion coefficients of different types of refractory bricks to design expansion joints, and high-refractory-performance bricks should be designed at the position closest to the high-temperature scenario. Generally, it is required to withstand temperatures of about 1400°C. On the outer layer, on the basis of ensuring a certain refractory performance, it should also have good heat insulation performance to ensure that the heat dissipation inside the system is small. Therefore, the design is difficult, and during the construction process, workers need to ensure that there is no mixing of different types of refractory bricks, and the requirements for construction are also relatively high.

[0021] Quartz sand, as an excellent refractory material with an extremely low expansion coefficient, capable of withstanding temperatures of 1600°C, and relatively low thermal conductivity, has always held a very high position in refractory materials. However, using quartz sand alone as the material for the overall refractory brick requires a relatively high cost. Therefore, generally, a heat insulation layer still needs to be designed on the outer layer.

[0022] To solve the above problems, as Figure 1 shown, the embodiment of the present invention provides a composite refractory brick method, including a refractory layer, an expansion layer, and a heat insulation brick. The expansion layer is arranged between the heat insulation brick and the refractory layer; Among them, the refractory layer includes quartz sand and aluminum titanate. The material of the expansion layer is aluminosilicate fiber, and the heat insulation brick includes portland cement, silicon carbide, and a binder.

[0023] Design a refractory layer based on quartz sand on the outer layer, and design a heat insulation brick with better heat insulation effect on the inner layer. Set aluminosilicate fiber that can withstand high temperatures of 1600°C and has a certain flexibility as the expansion layer between the two. This can enable the expansion layer to provide space between the heat insulation brick and the refractory layer during the expansion process of the heat insulation brick under high-temperature conditions, avoiding damage to the refractory brick caused by cracks or other situations in the refractory layer.

[0024] In a further implementation manner of this embodiment, the refractory layer includes the following materials in parts by weight: 40 - 60 parts of quartz sand, 10 - 15 parts of aluminum titanate. Quartz sand has a melting point above 1600°C, and its expansion coefficient is about , and it can have a relatively low deformation at high temperatures. By adding aluminum titanate, a composite system composed of two different materials is formed. In this composite system, aluminum titanate particles are dispersed in the quartz matrix. Quartz will undergo various polymorphic transformations during heating, such as from α - quartz to β - quartz, then to cristobalite and tridymite. These phase transformations are accompanied by volume changes, resulting in a relatively high coefficient of thermal expansion. The presence of aluminum titanate can, to a certain extent, inhibit the occurrence of these phase transformations or slow down their effects, thereby reducing the overall degree of expansion.

[0025] Aluminum titanate particles are evenly distributed in the quartz matrix, forming a dispersion-strengthened network structure. This network can effectively limit the expansion behavior of the matrix material, similar to the restraint effect of steel bars on concrete in reinforced concrete. Even if the quartz part expands, the aluminum titanate particles can resist this deformation through their own rigid support, thereby reducing the expansion amount of the entire composite material.

[0026] Due to the different elastic moduli between aluminum titanate and quartz, when the temperature rises, a small stress difference will be generated between the two. These stress differences will form a local stress field at the interface, which helps to disperse the stress caused by heat to a larger area rather than concentrating at a certain point. This can prevent the initiation and propagation of cracks caused by local stress concentration and improve the overall stability of the material.

[0027] In a further implementation manner of this embodiment, the particle size range of the quartz sand is 4000 mesh - 6000 mesh, and the purity of the quartz sand is greater than 99.99%. Further, the particle size distribution of the quartz sand is: 10% of the quartz sand with a particle size of 4000 mesh - 4200 mesh, 40% of the quartz sand with a particle size of 4800 mesh - 5000 mesh, 40% of the quartz sand with a particle size of 5400 mesh - 5600 mesh, and 10% of the quartz sand with a particle size of 5800 mesh - 6000 mesh.

[0028] The particle size of quartz sand directly affects its thermal expansion behavior. Smaller particles have a larger specific surface area, which will increase the stress concentration points inside the material, thereby exacerbating the thermal expansion effect. On the contrary, larger particles can reduce this effect because their contact area is relatively small, reducing the interaction force. However, overly large particles may reduce the overall uniformity and density of the material, thereby affecting its high-temperature resistance. Therefore, selecting the particle size within the above range can ensure strong high-temperature resistance while ensuring an extremely low expansion coefficient.

[0029] Adopting the above particle size distribution can effectively improve its thermal expansion coefficient and high-temperature resistance. Ensure that the particles can be closely arranged, while avoiding the appearance of too many small particles or large particles. This can not only improve the overall stability of the material but also enhance its thermal shock resistance and durability.

[0030] As mentioned above, quartz undergoes various polymorphic transformations during heating, such as from α-quartz to β-quartz, then to cristobalite and tridymite. These phase transformations are accompanied by volume changes, resulting in a relatively high thermal expansion coefficient. By controlling the particle size distribution of quartz sand, the formation of stable crystal forms can be selectively promoted, and other additives with low expansion coefficients (such as aluminum titanate) can be introduced to inhibit phase transformation expansion, thereby reducing the overall thermal expansion coefficient.

[0031] High-purity quartz sand with a purity greater than 99.99% has a lower expansion coefficient and higher high-temperature resistance compared to quartz sand with a lower purity. By using a mixture of high-purity quartz sand and aluminum titanate, the expansion coefficient of the refractory layer can be further reduced, so that it basically does not deform when the temperature reaches 1600°C.

[0032] In a further implementation manner of this embodiment, the insulating brick comprises the following materials in parts by weight: 80-100 parts of portland cement, 10-20 parts of silicon carbide, and 4-8 parts of binder. Further, the binder comprises an organic binder and an inorganic binder, and the mass ratio of the organic binder to the inorganic binder is (1-2):1; The organic binder comprises one or more of cellulose ether, lignin-based binder, and diethyl dibutylmalonate, and the inorganic binder comprises one or more of sodium silicate, water glass, silica sol, aluminum phosphate, and aluminum dihydrogen phosphate.

[0033] Although silicon carbide has strong thermal conductivity, when it is dispersed in the portland cement matrix as a filler, it does not directly contribute to reducing the thermal conductivity of the entire composite material, but indirectly affects the overall performance through its unique physical properties. The porosity of the portland cement-based material has an important influence on its thermal conductivity. A higher porosity means more air spaces, and air is a poor heat conductor, so the heat insulation effect of the material is increased. By introducing a composite binder combining an organic binder and an inorganic binder, a multiphase composite system can be constructed, in which each phase interacts with each other and jointly contributes to reducing the thermal conductivity. For example, organic polymers usually have a low thermal conductivity and can effectively prevent heat transfer; while inorganic minerals provide the necessary mechanical support and durability.

[0034] On the other hand, the embodiment of the present invention also provides a preparation method of a composite refractory brick, comprising the following steps: Mix 80-100 parts of portland cement, 10-20 parts of silicon carbide, and 4-8 parts of binder evenly, then put them into a mold and stand still for 68h-84h, and then demold to obtain an insulating brick; Wrap the expansion layer evenly on the insulating brick, and then place it in a mold; Mix 40-60 parts of quartz sand, 10-15 parts of aluminum titanate, and water evenly to form a quartz slurry; Inject the quartz slurry into the mold, remove air bubbles from the quartz slurry in the mold under vacuum, and then stand still for molding; Perform demolding treatment on the molded composite structure, and then send it into a sintering furnace for high-temperature sintering and curing.

[0035] In a further embodiment of the present embodiment, 80-100 parts of portland cement, 10-20 parts of silicon carbide, and 4-8 parts of binder are successively put into a mixer and stirred evenly, and then the evenly stirred mixture is fed into a mold and formed into a brick body by vibration and pressure setting. The pressure of the pressure setting is 3 MPa - 3.5 MPa; After molding, steam curing is carried out for 16 h - 24 h, and the curing temperature is 80 °C - 95 °C, and then it is naturally air-dried.

[0036] The insulating brick is selected to use portland cement as the base and add silicon carbide and binder, which can be formed into bricks without sintering, and has the advantages of low thermal conductivity, low expansion coefficient, and high fire resistance. Then, after attaching an expansion layer on the surface of the insulating brick, quartz slurry is evenly set on the outside of the expansion layer through a mold to form a refractory layer. After vacuum forming, it is sent into a sintering furnace to sinter and cure the refractory layer, so that the outer refractory brick has an extremely low expansion coefficient and a low thermal conductivity, and the internal insulating brick has an extremely low thermal conductivity and a low expansion coefficient.

[0037] In a further embodiment of the present embodiment, the expansion layer is a silica-aluminum fiber waterproof cloth, the thickness of the expansion layer is 2 - 4 mm, the thickness of the refractory layer is 10 - 15 mm, and the size of the insulating brick is (37 - 61) mm × (77 - 101) mm × (192 - 216) mm.

[0038] By using a silica-aluminum fiber waterproof cloth, it can be avoided that a large amount of slurry mixes into the expansion layer or even contacts the insulating brick during the pouring process of the quartz slurry. The overall model of the refractory brick is a standard model brick of 230 mm × 115 mm × 75 mm. By controlling the thickness of each layer and the size of the insulating brick, it can be ensured that the brick body basically does not deform and crack within the temperature range of 1700 °C.

[0039] In a further embodiment of the present embodiment, the vacuum degree during the vacuum defoaming process is 0.3 MPa - -0.1 MPa, and the sintering temperature of the high-temperature sintering is 1000 °C - 1100 °C.

[0040] When the vacuum degree reaches the range of 0.3 MPa - -0.1 MPa, the defoaming effect is the most ideal; for the refractory layer, although the quartz sand has completed the phase change after the first furnace high-temperature sintering, the volume change is very small during the later use. However, if the initial sintering temperature is too high, this good thermal stability will be damaged. If the sintering temperature is too low, the generated liquid phase is less, and the sintering neck with sufficient strength cannot be formed between the particles, resulting in low strength of the green body. At the same time, due to less liquid phase and short holding time, the sintering effect is further limited, making the product prone to cracks or breakage. The best sintering effect is achieved by using the above temperature for sintering.

[0041] Embodiment Put 90 parts of portland cement, 15 parts of silicon carbide and 6 parts of binder into a mixer in sequence and stir evenly. Then send the evenly stirred mixture into a mold and form it into a brick by vibration and pressurization. The pressure of the pressurization is 3.5 MPa. The binder includes an organic binder and an inorganic binder, and the mass ratio of the organic binder to the inorganic binder is 2:1. The organic binder is cellulose ether, and the inorganic binder is a mixture of water glass and silica sol. The size of the brick is 37 mm × 77 mm × 192 mm; Evenly wrap the expansion layer, i.e., aluminosilicate fiber waterproof cloth, on the insulating brick. The thickness of the expansion layer is 4 mm, and then place it in a mold; Mix 40 - 60 parts of quartz sand, 10 - 15 parts of aluminum titanate and water evenly to form a quartz slurry; inject the quartz slurry into a mold, carry out vacuum defoaming on the quartz slurry in the mold and then let it stand for molding; carry out demolding treatment on the formed composite structure, and then send it into a sintering furnace for high-temperature sintering and curing. The vacuum degree during the vacuum defoaming process is 0.3 MPa - 0.1 MPa, and the sintering temperature of the high-temperature sintering is 1000℃ - 1100℃, and prepare a standard-sized refractory brick with a size of 230 mm × 115 mm × 75 mm.

[0042] Place the prepared refractory brick at 1700℃ for 1 h and then detect the brick body. By placing the standard-sized refractory brick on an dilatometer and correcting its position, gradually increase the temperature at a predetermined heating rate (such as 50℃ / min) until the highest test temperature of 1700℃ is reached and maintained for 1 h. After that, it is detected that the size of the refractory brick after high-temperature expansion is 230.0023 mm × 115.0015 mm × 75.0007 mm, and its deformation is basically negligible. In the design process, the situation of expansion joints can be not considered, and there are no cracks or other damages on the appearance of the refractory brick body.

[0043] Respectively detect the overall thermal conductivity coefficients of the insulating brick and the refractory brick after detecting the expansion coefficient by the water flow flat plate method specified in YBT4130 - 2005. The thermal conductivity coefficient of the insulating brick is 0.45 W / (m·K), and the overall thermal conductivity coefficient of the refractory brick is 0.68 W / (m·K). It can be seen from the above that the thermal conductivity coefficient of the refractory brick is much lower than 1.0 W / (m·K) of general heat-insulating refractory materials, and it has extremely strong heat-insulating performance.

[0044] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the technical solution of the present invention, make some changes or modifications to form equivalent embodiments by using the above-disclosed technical content. However, as long as it does not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A composite refractory brick, characterized in that: It comprises a refractory layer, an expansion layer and thermal insulation bricks, wherein the expansion layer is arranged between the thermal insulation bricks and the refractory layer, and the thermal insulation bricks are arranged inside the refractory layer; The refractory layer comprises quartz sand and aluminum titanate, the expansion layer comprises aluminum silicate fiber, and the thermal insulation brick comprises silicate cement, silicon carbide and a binder.

2. The composite refractory brick according to claim 1, characterized in that: The refractory layer comprises the following materials in parts by weight: 40-60 parts of quartz sand and 10-15 parts of aluminum titanate.

3. The composite refractory brick according to claim 2, characterized in that: The particle size of the quartz sand ranges from 4000 mesh to 6000 mesh.

4. The composite refractory brick according to claim 3, characterized in that: The particle size distribution of the quartz sand is as follows: 10% of quartz sand with a particle size of 4000-4200 mesh, 40% of quartz sand with a particle size of 4800-5000 mesh, 40% of quartz sand with a particle size of 5400-5600 mesh, and 10% of quartz sand with a particle size of 5800-6000 mesh.

5. The composite refractory brick according to claim 1, characterized in that: The thermal insulation bricks include the following materials in parts by weight: 80-100 parts of silicate cement, 10-20 parts of silicon carbide and 4-8 parts of a binder.

6. The composite refractory brick according to claim 5, characterized in that: The binder comprises an organic binder and an inorganic binder, and the mass ratio of the organic binder to the inorganic binder is (1-2):1; The organic binder includes one or more of cellulose ether, lignin-based binder and diethyl dibutyl malonate, and the inorganic binder includes one or more of sodium silicate, water glass, silica sol, aluminum phosphate and aluminum dihydrogen phosphate.

7. A method for preparing a composite refractory brick, characterized in that: The following steps are involved: 80-100 parts of silicate cement, 10-20 parts of silicon carbide and 4-8 parts of binder are mixed evenly, molded and left to stand for 68h-84h before demolding to obtain thermal insulation bricks; The expansion layer is evenly wrapped on the insulation bricks and then placed in the mold; Mix 40-60 parts of quartz sand, 10-15 parts of aluminum titanate and water to form a quartz slurry; Injecting quartz slurry into the mold, vacuum-debubbling the quartz slurry in the mold, and then allowing it to stand for molding; The formed composite structure is demoulded and then sent into a sintering furnace for high-temperature sintering and curing.

8. The method for preparing composite refractory bricks according to claim 7, characterized in that: 80-100 parts of silicate cement, 10-20 parts of silicon carbide and 4-8 parts of binder are sequentially put into a mixer and stirred evenly, and then the evenly stirred mixture is sent into a mold and shaped into a brick body by vibration and pressure, and the pressure of the pressure is 3MPa-3.5MPa; After forming, steam curing is carried out for 16h-24h at a curing temperature of 80℃-95℃, and then natural air drying is carried out.

9. The method for preparing a composite refractory brick according to claim 7, characterized in that: The expansion layer is aluminum silicate fiber waterproof cloth, the thickness of the expansion layer is 2-4 mm, the thickness of the fire-resistant layer is 10-15 mm, and the size of the insulation brick is (37-61) mm×(77-101) mm×(192-216) mm.

10. The method for preparing composite refractory bricks according to claim 7, characterized in that: The vacuum degree in the vacuum degassing process is 0.3MPa-0.1MPa, and the sintering temperature of the high-temperature sintering is 1000°C-1100°C.

Images