Heat insulation shale brick and preparation process thereof

Abstract

The invention relates to the technical field of shale bricks, in particular to a heat preservation and insulation shale brick and a preparation process thereof. The preparation process of the heat-preservation and heat-insulation shale brick comprises the following steps: preparation of a heat-preservation and heat-insulation composite material, preparation of a porous ceramic fiber filler, preparation of the shale brick and heat-preservation and heat-insulation treatment of the shale brick. The heat insulation performance of the shale brick is improved through multiple technologies. The porous ceramic fiber filler is prepared into a graded porous structure through electrostatic spinning, and efficient heat insulation and high strength are achieved in cooperation with TEOS, aluminum chlorohydrate and the like. And the modified carbonized loofah sponge coating has passive barrier and active reflection functions and is firmly combined with the brick body. The sodium lignin sulfonate can disperse the nano-particles and enhance the combination of the nano-particles and the loofah sponge skeleton. The interior and exterior cooperate to form an excellent thermal insulation system, and brick performance is improved.

Description

Technical Field

[0001] This invention relates to the field of shale brick technology, specifically to a thermal insulation shale brick and its preparation process. Background Technology

[0002] Shale bricks, as a traditional wall material, are still widely used in the construction industry due to their advantages such as wide availability of raw materials, mature sintering technology, and high durability. However, traditional shale bricks have problems such as low porosity and high thermal conductivity, making it difficult for their thermal insulation performance to meet current building energy-saving standards. An additional insulation layer is required to achieve energy-saving effects, which not only increases construction costs but also poses safety hazards such as poor adhesion between the insulation layer and the wall, and easy detachment.

[0003] To improve the thermal insulation performance of shale bricks, existing technologies have proposed several improvement schemes. Some schemes involve adding lightweight insulating aggregates such as perlite and polystyrene particles to the shale raw materials. While this can reduce the thermal conductivity of the bricks, it leads to a significant decrease in brick strength, making it difficult to meet the load-bearing requirements of walls. Another scheme uses a porous sintering process, preparing porous shale bricks by adjusting the particle size distribution or adding foaming agents. However, this results in uneven pore distribution, low closed-cell rate, limited thermal insulation effect, and reduced frost resistance.

[0004] In summary, the current construction industry has an urgent need for shale bricks that combine excellent thermal insulation performance, high strength, environmental friendliness, economy, and ease of large-scale production. Given the shortcomings of existing technologies, developing a thermally insulating shale brick and its preparation process, which significantly improves thermal insulation performance while ensuring the brick's mechanical properties, has significant practical implications and application value. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a thermally insulating shale brick and its preparation process.

[0006] This invention provides a process for preparing thermally insulating shale bricks, comprising: S1: Preparation of thermal insulation composite materials; The loofah sponge was pretreated by soaking it in ethanol. Then, titanium oxysulfate, thiourea and sodium lignosulfonate were added to deionized water, mixed and then the pretreated loofah sponge was added to carry out a hydrothermal reaction. Finally, carbonization was carried out to obtain a thermal insulation composite material. S2: Preparation of porous ceramic fiber fillers; TEOS hydrolysate, aluminum hydroxychloride and barium carbonate were added to a polyacrylonitrile solution, mixed, and then polystyrene microspheres were added. After mixing, the mixture was electrospun to obtain nanofibers. The nanofibers were then calcined to prepare porous ceramic fiber fillers. S3: Preparation of shale bricks; Shale, coal gangue, clay and porous ceramic fiber filler are mixed and ground, then polyvinyl alcohol and polycarboxylate superplasticizer are added and mixed. The mixture is injected into a mold, pressed and sintered to obtain shale bricks. S4: Thermal insulation treatment for shale bricks; A coating slurry is prepared by mixing thermal insulation composite material, nano silica, zinc stearate, silicone acrylic emulsion, thickener, dispersant, defoamer and deionized water. The coating slurry is then applied to the surface of shale bricks by spraying and dried and cured to obtain thermal insulation shale bricks.

[0007] As a preferred aspect, S1: The preparation of the thermal insulation composite material specifically includes the following steps: S1.1: Remove the spine part in the middle of the loofah sponge, then cut it into pieces. Soak the cut loofah sponge in ethanol for 20-30 minutes, then wash it with deionized water 3-5 times. Place the washed loofah sponge in an oven at 70-80℃ to dry it, and obtain the pretreated loofah sponge. S1.2: Add 1.5-2 parts by weight of titanium oxysulfate, 1-1.5 parts by weight of thiourea and 1.6-1.8 parts by weight of sodium lignosulfonate to 50-60 parts by weight of deionized water and stir at 1000-1200 rpm for 20-30 min. Then add 5-8 parts by weight of pretreated loofah sponge, mix and add to the reactor. Then carry out hydrothermal reaction at 180-200℃ for 6-8 h. After the reaction is completed, wash and dry, and then carbonize at 750-800℃ for 2-3 h under nitrogen atmosphere to obtain thermal insulation composite material.

[0008] As a preferred aspect, S2: the preparation of porous ceramic fiber filler specifically includes the following steps: S2.1: Add 8-10 parts by weight of polyacrylonitrile with a molecular weight of 150,000 to 80-85 parts by weight of N,N-dimethylformamide, and then stir in a water bath at 50-60℃ at a speed of 500-800 rpm for 4-6 hours to obtain a polyacrylonitrile solution. S2.2: Add 3-5 parts by weight of anhydrous ethanol and 2-3 parts by weight of deionized water to 3-5 parts by weight of tetraethyl orthosilicate, then add 0.3-0.5 parts by weight of 0.1M hydrochloric acid, and stir magnetically at room temperature for 30-50 min to obtain TEOS hydrolysate; S2.3: Under magnetic stirring at 500-800 rpm, add the above TEOS hydrolysate, 5-6 parts by weight of aluminum hydroxyl chloride and 1-2 parts by weight of barium carbonate to the above polyacrylonitrile solution, stir and mix for 2-3 hours to obtain a mixture, add 1-2 parts by weight of polystyrene microspheres to the mixture, and continue stirring and mixing for 1-2 hours to obtain a spinning solution. S2.4: The spinning solution is loaded into a syringe and electrospinned at room temperature to obtain nanofibers; S2.5: Nanofibers are placed in a tube furnace, sintered, and then cooled with the furnace to obtain porous ceramic fiber fillers.

[0009] As a preferred aspect, the spinning parameters in step S2.4 are: injection speed 2-3 mL / h, voltage 24-26 kV, and distance between the syringe and receiver 20-22 cm.

[0010] As a preferred aspect, the sintering in step S2.5 specifically involves heating to 250-260°C at a rate of 1-2°C / min in an air atmosphere, holding at that temperature for 60-70 min, continuing to heat to 300°C at a rate of 1-2°C / min, holding at that temperature for 60-70 min, then heating to 400-450°C at a rate of 2-3°C / min in a nitrogen atmosphere, holding at that temperature for 80-90 min, and finally heating to 1000-1200°C at a rate of 3-5°C / min and sintering for 1-2 h.

[0011] As a preferred aspect, S3: the preparation of shale bricks specifically includes the following steps: S3.1: Mix 50-60 parts by weight of shale, 20-30 parts by weight of coal gangue, 20-30 parts by weight of clay and 5-10 parts by weight of porous ceramic fiber filler, grind to obtain a mixture powder, add 2-3 parts by weight of polyvinyl alcohol and 1-2 parts by weight of polycarboxylate superplasticizer to the mixture powder, stir in a mixer at 200-300 rpm for 20-30 min to obtain a mixture; S3.2: Inject the mixture into the mold and press it into shape under a pressure of 15-20MPa to obtain shale brick blanks. Dry the shale brick blanks at 60-70℃ until the moisture content is less than 3% to obtain dried brick blanks. S3.3: The dried brick blanks are sintered in a kiln. First, the temperature is raised to 600-650℃ in an air atmosphere at a rate of 2-3℃ / min and held for 1-2 hours. Then, the temperature is raised to 950-1000℃ at a rate of 3-5℃ / min and held for 2-3 hours. Finally, the bricks are cooled to room temperature in the kiln to obtain shale bricks.

[0012] As a preferred aspect, S4: the thermal insulation treatment of shale bricks specifically includes the following steps: S4.1: Add 10-15 parts by weight of thermal insulation composite material, 2-3 parts by weight of nano silica, 0.5-1 parts by weight of zinc stearate, 5-8 parts by weight of silicone acrylic emulsion, 0.5-1 parts by weight of hydroxyethyl cellulose thickener, 0.5-1 parts by weight of dispersant, 0.1-0.3 parts by weight of defoamer and 15-20 parts by weight of deionized water to a mixer and mix at 800-1000 rpm for 30-40 minutes to obtain the coating slurry; S4.2: Apply the coating slurry to the surface of the shale brick by spraying. The coating thickness is controlled at 1-2 mm. The spraying parameters are: nozzle diameter 1-2 mm, spraying pressure 0.3-0.5 MPa, spraying distance 20-25 cm. After application, let it stand at room temperature for 10-15 min, then dry it at 60-70℃ for 1-2 h, and then cure it at 120-150℃ for 30-40 min to obtain the thermal insulation shale brick.

[0013] As a preferred aspect, the defoamer in step S4.1 is an organosilicone defoamer.

[0014] As a preferred aspect, the dispersant in step S4.1 is a sodium polycarboxylate dispersant.

[0015] The present invention also provides a thermal insulation shale brick, which is prepared by any of the thermal insulation shale brick preparation processes described in any one of the claims.

[0016] The present invention has the following advantages: 1. In preparing porous ceramic fiber fillers, this invention utilizes electrospinning technology to construct a nanofiber network framework and introduces polystyrene microspheres as a pore-forming agent. During heat treatment, the polystyrene decomposes, leaving behind spherical macropores, while the fibers themselves form micropores and mesopores, ultimately constructing a hierarchical porous structure with a coexistence of micropores, mesopores, and macropores. This structure effectively restricts air convection and increases heat scattering paths, thereby significantly reducing solid-state heat conduction and gaseous heat convection in the brick, achieving highly efficient heat insulation. SiO2 provided by TEOS hydrolysis constitutes the basic framework of the fibers, ensuring high-temperature resistance. The introduction of aluminum hydroxychloride generates a high-strength mullite crystal phase at high temperatures, significantly enhancing the mechanical strength of the fibers. Barium carbonate, as a sintering aid, not only lowers the sintering temperature and refines the grains but also promotes the formation of a strong bond at the fiber intersections through liquid-phase sintering, achieving a robust "welding" of the fiber network. The synergistic effect of these three elements allows the filler to form a high-strength three-dimensional network within the brick, acting as a reinforcing "steel bar" to significantly improve the compressive strength and crack resistance of the shale brick, while also achieving lightweight construction. The addition of porous ceramic fiber filler to the shale brick, along with the surface insulation coating, forms a dual insulation system of "internal pores + surface coating," enhancing the overall insulation effect and providing excellent frost resistance.

[0017] 2. This invention utilizes a thermal insulation composite material composed of modified carbonized loofah sponge. Inheriting the three-dimensional porous structure of the loofah sponge bio-template, it effectively blocks heat conduction. Simultaneously, during the hydrothermal and carbonization process, sulfur-doped titanium dioxide nanoparticles, generated from the reaction of titanium oxysulfate and thiourea, are firmly loaded onto the carbon skeleton. These nanoparticles have high reflectivity to sunlight, reducing heat absorption at the source. The combination of these two elements gives the coating both passive and active insulation functions, forming a synergistic insulation system from the inside out with the internal porous ceramic fiber network. Using silicone-acrylic emulsion as a film-forming agent, combined with the filling and reinforcing effect of nano-silica, the coating, after curing, forms a tight chemical and physical bond with the shale brick matrix, exhibiting strong adhesion and effectively preventing cracking and peeling. The coating system is stable after curing and can maintain its thermal insulation performance for a long time.

[0018] 3. In this invention, sodium lignosulfonate is added to the preparation of the thermal insulation composite material. During the hydrothermal reaction stage of the composite material, sodium lignosulfonate partially degrades, and the generated small-molecule phenols and sulfonic acid-containing fragments continue to play a dispersing role. The reduced molecular weight makes them easier to adsorb onto the surface of nanoparticles. The remaining sulfonic acid groups maintain negative charge repulsion, preventing particle aggregation. The degradation products provide electrostatic repulsion and steric hindrance effects, effectively inhibiting the aggregation of newly generated nanoparticles, allowing them to be highly dispersed and uniformly loaded onto the surface of the loofah fiber. In the subsequent carbonization stage, sodium lignosulfonate itself carbonizes to form an amorphous carbon layer. This carbon layer acts like "glue," more firmly fixing the nanoparticles to the carbonized loofah skeleton, enhancing the overall stability of the composite material, and also contributing additional thermal insulation performance to the system. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of thermally insulating shale bricks used in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0021] Example 1: A preparation process for thermally insulating shale bricks, referring to... Figure 1 ,include: S1: Preparation of thermal insulation composite materials S1.1: Remove the spine part in the middle of the loofah sponge, then cut it into pieces. Soak the cut loofah sponge in ethanol for 20 minutes, then wash it three times with deionized water. Place the washed loofah sponge in a 70℃ oven to dry it, and obtain the pretreated loofah sponge. S1.2: 1.5 parts by weight of titanium oxysulfate, 1 part by weight of thiourea and 1.6 parts by weight of sodium lignosulfonate were added to 50 parts by weight of deionized water and stirred at 1000 rpm for 20 min. Then, 5 parts by weight of pretreated loofah sponge were added and mixed into a reactor. The mixture was then subjected to hydrothermal reaction at 180℃ for 6 h. After the reaction was completed, the mixture was washed and dried. Then, it was carbonized at 750℃ for 2 h under a nitrogen atmosphere to obtain a thermal insulation composite material. S2: Preparation of porous ceramic fiber fillers S2.1: Add 8 parts by weight of polyacrylonitrile with a molecular weight of 150,000 to 80 parts by weight of N,N-dimethylformamide, and then stir at 500 rpm for 4 hours in a 50°C water bath to obtain a polyacrylonitrile solution. S2.2: Add 3 parts by weight of anhydrous ethanol and 2 parts by weight of deionized water to 3 parts by weight of tetraethyl orthosilicate, then add 0.3 parts by weight of 0.1M hydrochloric acid, and stir magnetically for 30 min at room temperature to obtain TEOS hydrolysate; S2.3: Under magnetic stirring at 500 rpm, add the above TEOS hydrolysate, 5 parts by weight of aluminum hydroxyl chloride and 1 part by weight of barium carbonate to the above polyacrylonitrile solution, stir and mix for 2 h to obtain a mixture, add 1 part by weight of polystyrene microspheres to the mixture, and continue stirring and mixing for 1 h to obtain a spinning solution. S2.4: The spinning solution is loaded into a syringe and electrospinning is performed at room temperature. The receiving device is a grounded roller covered with aluminum foil. The spinning parameters are: injection speed 2mL / h, voltage 24kV, distance between syringe and receiver 20cm, to obtain nanofibers. S2.5: The nanofibers were placed in a tube furnace and heated to 250°C at a rate of 1°C / min under an air atmosphere, held for 60 min, then heated to 300°C at a rate of 1°C / min and held for 60 min. After that, the temperature was increased to 400°C at a rate of 2°C / min under a nitrogen atmosphere and held for 80-90 min. Finally, the temperature was increased to 1000°C at a rate of 3°C / min and sintered for 1 h. The furnace was then cooled to obtain porous ceramic fiber filler. S3: Preparation of Shale Bricks S3.1: Mix 50 parts by weight of shale, 20 parts by weight of coal gangue, 20 parts by weight of clay and 5 parts by weight of porous ceramic fiber filler, grind to obtain a mixture powder, add 2 parts by weight of polyvinyl alcohol and 1 part by weight of polycarboxylate superplasticizer to the mixture powder, stir in a mixer at 200 rpm for 20 min to obtain a mixture. S3.2: The mixture is injected into the mold and pressed into shape under a pressure of 15MPa to obtain shale brick blanks. The shale brick blanks are dried at 60℃ until the moisture content is less than 3% to obtain dried brick blanks. S3.3: The dried brick blanks are sintered in a kiln. First, the temperature is raised to 600℃ at 2℃ / min in an air atmosphere and held for 1 hour. Then, the temperature is raised to 950℃ at 3℃ / min and held for 2 hours. Finally, the bricks are cooled to room temperature in the kiln to obtain shale bricks. S4: Thermal insulation treatment of shale bricks S4.1: Add 10 parts by weight of thermal insulation composite material, 2 parts by weight of nano silica, 0.5 parts by weight of zinc stearate, 5 parts by weight of silicone acrylic emulsion, 0.5 parts by weight of hydroxyethyl cellulose thickener, 0.5 parts by weight of sodium polycarboxylate dispersant, 0.1 parts by weight of organosilicon defoamer and 15 parts by weight of deionized water to a mixer and mix at 800 rpm for 30 min to obtain coating slurry; S4.2: Apply the coating slurry to the surface of the shale brick by spraying. The coating thickness is controlled at 1 mm. The spraying parameters are: nozzle diameter 1 mm, spraying pressure 0.3 MPa, spraying distance 20 cm. After application, let it stand at room temperature for 10 min, then dry it at 60℃ for 1 h, and then cure it at 120℃ for 30 min to obtain the thermal insulation shale brick.

[0022] Example 2, a preparation process for thermal insulation shale bricks, see [link to example]. Figure 1 ,include: S1: Preparation of thermal insulation composite materials S1.1: Remove the spine part in the middle of the loofah sponge, then cut it into pieces. Soak the cut loofah sponge in ethanol for 30 minutes, then wash it 5 times with deionized water. Place the washed loofah sponge in an 80℃ oven to dry it, and obtain the pretreated loofah sponge. S1.2: Add 2 parts by weight of titanium oxysulfate, 1.5 parts by weight of thiourea and 1.8 parts by weight of sodium lignosulfonate to 60 parts by weight of deionized water and stir at 1200 rpm for 30 min. Then add 8 parts by weight of pretreated loofah sponge, mix and add to the reactor. Then carry out hydrothermal reaction at 200℃ for 8 h. After the reaction is completed, wash and dry, and then carbonize at 800℃ for 3 h under nitrogen atmosphere to obtain thermal insulation composite material. S2: Preparation of porous ceramic fiber fillers S2.1: Add 10 parts by weight of polyacrylonitrile with a molecular weight of 150,000 to 85 parts by weight of N,N-dimethylformamide, and then stir at 800 rpm for 6 hours in a water bath at 60°C to obtain a polyacrylonitrile solution. S2.2: Add 5 parts by weight of anhydrous ethanol and 3 parts by weight of deionized water to 5 parts by weight of tetraethyl orthosilicate, then add 0.5 parts by weight of 0.1M hydrochloric acid, and stir magnetically for 50 min at room temperature to obtain TEOS hydrolysate; S2.3: Under magnetic stirring at 800 rpm, add the above TEOS hydrolysate, 6 parts by weight of aluminum hydroxyl chloride and 2 parts by weight of barium carbonate to the above polyacrylonitrile solution, stir and mix for 3 h to obtain a mixture, add 2 parts by weight of polystyrene microspheres to the mixture, and continue stirring and mixing for 2 h to obtain a spinning solution. S2.4: The spinning solution is loaded into a syringe and electrospinning is performed at room temperature. The receiving device is a grounded roller covered with aluminum foil. The spinning parameters are: injection speed 3mL / h, voltage 26kV, distance between syringe and receiver 22cm, to obtain nanofibers. S2.5: The nanofibers were placed in a tube furnace and heated to 260°C at a rate of 2°C / min in air atmosphere, held for 70 min, and then heated to 300°C at a rate of 2°C / min and held for 70 min. After that, the temperature was increased to 450°C at a rate of 3°C / min in nitrogen atmosphere and held for 90 min. Finally, the temperature was increased to 1200°C at a rate of 5°C / min and sintered for 2 h. The furnace was then cooled to obtain porous ceramic fiber filler. S3: Preparation of Shale Bricks S3.1: Mix 60 parts by weight of shale, 30 parts by weight of coal gangue, 30 parts by weight of clay and 10 parts by weight of porous ceramic fiber filler, grind to obtain a mixture powder, add 3 parts by weight of polyvinyl alcohol and 2 parts by weight of polycarboxylate superplasticizer to the mixture powder, stir in a mixer at 300 rpm for 30 min to obtain a mixture. S3.2: The mixture is injected into the mold and pressed into shape under a pressure of 20MPa to obtain shale brick blanks. The shale brick blanks are dried at 70℃ until the moisture content is less than 3% to obtain dried brick blanks. S3.3: The dried brick blanks are sintered in a kiln. First, the temperature is raised to 650℃ at 3℃ / min in an air atmosphere and held for 2 hours. Then, the temperature is raised to 1000℃ at 5℃ / min and held for 3 hours. Finally, the bricks are cooled to room temperature in the kiln to obtain shale bricks. S4: Thermal insulation treatment of shale bricks S4.1: Add 15 parts by weight of thermal insulation composite material, 3 parts by weight of nano silica, 1 part by weight of zinc stearate, 8 parts by weight of silicone acrylic emulsion, 1 part by weight of hydroxyethyl cellulose thickener, 1 part by weight of sodium polycarboxylate dispersant, 0.3 parts by weight of organosilicon defoamer and 20 parts by weight of deionized water to a mixer and mix at 1000 rpm for 40 min to obtain coating slurry; S4.2: Apply the coating slurry to the surface of the shale brick by spraying. The coating thickness is controlled at 2mm. The spraying parameters are: nozzle diameter 2mm, spraying pressure 0.5MPa, spraying distance 25cm. After application, let it stand at room temperature for 15min, then dry it at 70℃ for 2h, and then cure it at 150℃ for 40min to obtain the thermal insulation shale brick.

[0023] Example 3, a preparation process for thermal insulation shale bricks, see [link to example]. Figure 1 ,include: S1: Preparation of thermal insulation composite materials S1.1: Remove the spine in the middle of the loofah sponge, then cut it into pieces. Soak the cut loofah sponge in ethanol for 25 minutes, then wash it 4 times with deionized water. Place the washed loofah sponge in a 75℃ oven to dry it, and obtain the pretreated loofah sponge. S1.2: 1.75 parts by weight of titanium oxysulfate, 1.25 parts by weight of thiourea and 1.7 parts by weight of sodium lignosulfonate were added to 55 parts by weight of deionized water and stirred at 1100 rpm for 25 min. Then, 6.5 parts by weight of pretreated loofah sponge were added and mixed into a reactor. The mixture was then subjected to hydrothermal reaction at 190 °C for 7 h. After the reaction was completed, the mixture was washed and dried. Then, it was carbonized at 775 °C for 2.5 h under a nitrogen atmosphere to obtain a thermal insulation composite material. S2: Preparation of porous ceramic fiber fillers S2.1: Add 9 parts by weight of polyacrylonitrile with a molecular weight of 150,000 to 82.5 parts by weight of N,N-dimethylformamide, and then stir at 650 rpm for 5 hours in a water bath at 55°C to obtain a polyacrylonitrile solution. S2.2: Add 4 parts by weight of anhydrous ethanol and 2.5 parts by weight of deionized water to 4 parts by weight of tetraethyl orthosilicate, then add 0.4 parts by weight of 0.1M hydrochloric acid, and stir magnetically at room temperature for 40 min to obtain TEOS hydrolysate; S2.3: Under magnetic stirring at 650 rpm, the above TEOS hydrolysate, 5.5 parts by weight of aluminum hydroxyl chloride and 1.5 parts by weight of barium carbonate were added to the above polyacrylonitrile solution and stirred for 2.5 h to obtain a mixture. 1.5 parts by weight of polystyrene microspheres were added to the mixture and stirred for another 1.5 h to obtain a spinning solution. S2.4: The spinning solution is loaded into a syringe and electrospinning is performed at room temperature. The receiving device is a grounded roller covered with aluminum foil. The spinning parameters are: injection speed 2.5 mL / h, voltage 25 kV, and distance between the syringe and the receiver 21 cm to obtain nanofibers. S2.5: The nanofibers were placed in a tube furnace and heated to 255°C at a rate of 1.5°C / min in air atmosphere, held for 65 min, and then heated to 300°C at a rate of 1.5°C / min and held for 65 min. After that, the temperature was increased to 425°C at a rate of 2.5°C / min in nitrogen atmosphere and held for 85 min. Finally, the temperature was increased to 1100°C at a rate of 4°C / min and sintered for 1.5 h. The furnace was then cooled to obtain porous ceramic fiber filler. S3: Preparation of Shale Bricks S3.1: Mix 55 parts by weight of shale, 25 parts by weight of coal gangue, 25 parts by weight of clay and 6.5 parts by weight of porous ceramic fiber filler, grind to obtain a mixture powder, add 2.5 parts by weight of polyvinyl alcohol and 1.5 parts by weight of polycarboxylate superplasticizer to the mixture powder, stir at 250 rpm for 25 min in a mixer to obtain a mixture. S3.2: The mixture is injected into the mold and pressed into shape under a pressure of 17.5MPa to obtain shale brick blanks. The shale brick blanks are dried at 65℃ until the moisture content is less than 3% to obtain dried brick blanks. S3.3: The dried brick blanks are sintered in a kiln. First, the temperature is raised to 625℃ at 2.5℃ / min in an air atmosphere and held for 1.5h. Then, the temperature is raised to 975℃ at 4℃ / min and held for 2.5h. Finally, the bricks are cooled to room temperature in the kiln to obtain shale bricks. S4: Thermal insulation treatment of shale bricks S4.1: Add 12.5 parts by weight of thermal insulation composite material, 2.5 parts by weight of nano silica, 0.75 parts by weight of zinc stearate, 6.5 parts by weight of silicone acrylic emulsion, 0.75 parts by weight of hydroxyethyl cellulose thickener, 0.75 parts by weight of sodium polycarboxylate dispersant, 0.2 parts by weight of organosilicon defoamer and 17.5 parts by weight of deionized water to a mixer and mix at 900 rpm for 35 minutes to obtain the coating slurry; S4.2: Apply the coating slurry to the surface of the shale brick by spraying. The coating thickness is controlled at 1.5 mm. The spraying parameters are: nozzle diameter 1.5 mm, spraying pressure 0.4 MPa, spraying distance 22.5 cm. After application, let it stand at room temperature for 12.5 min, then dry it at 65℃ for 1.5 h, and then cure it at 135℃ for 35 min to obtain the thermal insulation shale brick.

[0024] Comparative Example 1 differs from Example 1 in that the porous ceramic fiber filler in steps S2 and S3.1 is removed, while the remaining steps remain unchanged to prepare thermal insulation shale bricks. This is referred to as Comparative Example 1.

[0025] Comparative Example 2 differs from Example 1 in that steps S1 and S4 are removed, while the remaining steps remain unchanged in preparing shale bricks, which are thermal insulation shale bricks, and are referred to as Comparative Example 2.

[0026] Comparative Example 3 differs from Example 1 in that sodium lignosulfonate in step S1.2 is removed, while the remaining steps remain unchanged in preparing thermal insulation shale bricks. This is referred to as Comparative Example 3.

[0027] Comparative Example 4 differs from Example 1 in that the porous ceramic fiber filler in steps S1-S2, S4 and S3.1 is removed, while the remaining steps remain unchanged to prepare thermal insulation shale bricks. This is referred to as Comparative Example 4.

[0028] The thermal insulation shale bricks prepared in Examples 1-3 and Comparative Examples 1-4 were cured in a standard curing room for 24 hours. Then, the thermal conductivity was measured using the heat flow meter method. The measurement was performed three times and the average value was taken. The measurement results are shown in Table 1.

[0029] Table 1. Results of thermal conductivity measurements for Examples 1-3 and Comparative Examples 1-4

[0030] As can be seen from the data in Table 1, the shale bricks prepared by this invention have a low thermal conductivity, indicating that the shale bricks of this invention have good thermal insulation effect. As can be seen from the data of Comparative Examples 1-2 and 4, the addition of porous ceramic fiber filler can reduce the thermal conductivity and achieve the thermal insulation effect. Furthermore, the dual thermal insulation system formed by the shale bricks with porous ceramic fiber filler and the surface thermal insulation coating can play a synergistic role in improving the thermal insulation effect. As can be seen from the data of Comparative Example 3, the addition of sodium lignosulfonate in the preparation of thermal insulation composite materials can further improve the thermal insulation performance.

[0031] The compressive strength of the thermal insulation shale bricks prepared in Examples 1-3 and Comparative Example 1 was measured after curing in a standard curing room for 24 hours. The compressive strength was measured according to the method specified in GB / T50081-2019. The measurement was performed three times and the average value was taken. The measurement results are shown in Table 2.

[0032]

[0033] As can be seen from the data in Table 2, the addition of porous ceramic fiber filler in this invention can significantly improve the compressive strength of thermal insulation shale bricks.

[0034] The thermal insulation shale bricks prepared in Examples 1-3 were cured in a standard curing room for 24 hours. The solar reflectance, coating adhesion and strength loss rate after 50 freeze-thaw cycles of the thermal insulation shale bricks after curing in Examples 1-3 and the control group were measured. The measurements were taken three times and the average value was taken. The measurement results are shown in Table 3.

[0035] Solar reflectivity: JG / T235-2014.

[0036] Coating adhesion: determined by the pull-off method.

[0037] Strength loss rate after 50 freeze-thaw cycles: The initial compressive strength was measured before the freeze-thaw cycles, and then freeze-thaw cycles were performed: -18℃ to 5℃, each freeze-thaw cycle for 4 hours. After 50 cycles, the compressive strength after freeze-thaw was measured. Strength loss rate = [(initial compressive strength - compressive strength after freeze-thaw) / initial compressive strength] × 100%.

[0038] Table 3. Performance test results of Examples 1-3 and the control group

[0039] As can be seen from the data in Table 3, compared with commercially available sintered shale insulating bricks, the insulating shale bricks prepared by this invention have a high reflectivity to sunlight, which can reduce heat absorption at the source. At the same time, the insulating shale bricks have good frost resistance, and the prepared coating can form a tight chemical and physical bond with the shale brick matrix after curing, with strong adhesion.

[0040] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A preparation process for thermally insulating shale bricks, characterized in that, include: S1: Preparation of thermal insulation composite materials; The loofah sponge was pretreated by soaking it in ethanol. Then, titanium oxysulfate, thiourea and sodium lignosulfonate were added to deionized water, mixed and then the pretreated loofah sponge was added to carry out a hydrothermal reaction. Finally, carbonization was carried out to obtain a thermal insulation composite material. S2: Preparation of porous ceramic fiber fillers; TEOS hydrolysate, aluminum hydroxychloride and barium carbonate were added to a polyacrylonitrile solution, mixed, and then polystyrene microspheres were added. After mixing, the mixture was electrospun to obtain nanofibers. The nanofibers were then calcined to prepare porous ceramic fiber fillers. S3: Preparation of shale bricks; Shale, coal gangue, clay and porous ceramic fiber filler are mixed and ground, then polyvinyl alcohol and polycarboxylate superplasticizer are added and mixed. The mixture is injected into a mold, pressed and sintered to obtain shale bricks. S4: Thermal insulation treatment for shale bricks; A coating slurry is prepared by mixing thermal insulation composite material, nano silica, zinc stearate, silicone acrylic emulsion, thickener, dispersant, defoamer and deionized water. The coating slurry is then applied to the surface of shale bricks by spraying and dried and cured to obtain thermal insulation shale bricks.

2. The preparation process of a thermally insulating shale brick according to claim 1, characterized in that, S1: The preparation of thermal insulation composite materials includes the following steps: S1.1: Remove the spine part in the middle of the loofah sponge, then cut it into pieces. Soak the cut loofah sponge in ethanol for 20-30 minutes, then wash it with deionized water 3-5 times. Place the washed loofah sponge in an oven at 70-80℃ to dry it, and obtain the pretreated loofah sponge. S1.2: Add 1.5-2 parts by weight of titanium oxysulfate, 1-1.5 parts by weight of thiourea and 1.6-1.8 parts by weight of sodium lignosulfonate to 50-60 parts by weight of deionized water and stir at 1000-1200 rpm for 20-30 min. Then add 5-8 parts by weight of pretreated loofah sponge, mix and add to the reactor. Then carry out hydrothermal reaction at 180-200℃ for 6-8 h. After the reaction is completed, wash and dry, and then carbonize at 750-800℃ for 2-3 h under nitrogen atmosphere to obtain thermal insulation composite material.

3. The preparation process of a thermally insulating shale brick according to claim 1, characterized in that, S2: Preparation of porous ceramic fiber fillers, specifically including the following steps: S2.1: Add 8-10 parts by weight of polyacrylonitrile with a molecular weight of 150,000 to 80-85 parts by weight of N,N-dimethylformamide, and then stir in a water bath at 50-60℃ at a speed of 500-800 rpm for 4-6 hours to obtain a polyacrylonitrile solution. S2.2: Add 3-5 parts by weight of anhydrous ethanol and 2-3 parts by weight of deionized water to 3-5 parts by weight of tetraethyl orthosilicate, then add 0.3-0.5 parts by weight of 0.1M hydrochloric acid, and stir magnetically at room temperature for 30-50 min to obtain TEOS hydrolysate; S2.3: Under magnetic stirring at 500-800 rpm, add the above TEOS hydrolysate, 5-6 parts by weight of aluminum hydroxyl chloride and 1-2 parts by weight of barium carbonate to the above polyacrylonitrile solution, stir and mix for 2-3 hours to obtain a mixture, add 1-2 parts by weight of polystyrene microspheres to the mixture, and continue stirring and mixing for 1-2 hours to obtain a spinning solution. S2.4: The spinning solution is loaded into a syringe and electrospinned at room temperature to obtain nanofibers; S2.5: Nanofibers are placed in a tube furnace, sintered, and then cooled with the furnace to obtain porous ceramic fiber fillers.

4. The preparation process of a thermally insulating shale brick according to claim 3, characterized in that, The spinning parameters in step S2.4 are: injection speed 2-3 mL / h, voltage 24-26 kV, and distance between the syringe and receiver 20-22 cm.

5. The preparation process of a thermally insulating shale brick according to claim 3, characterized in that, The sintering in step S2.5 specifically involves heating to 250-260°C at a rate of 1-2°C / min in an air atmosphere, holding at that temperature for 60-70 min, then continuing to heat to 300°C at a rate of 1-2°C / min and holding at that temperature for 60-70 min, followed by heating to 400-450°C at a rate of 2-3°C / min in a nitrogen atmosphere and holding at that temperature for 80-90 min, and finally heating to 1000-1200°C at a rate of 3-5°C / min and sintering for 1-2 h.

6. The preparation process of a thermally insulating shale brick according to claim 1, characterized in that, S3: The preparation of shale bricks includes the following steps: S3.1: Mix 50-60 parts by weight of shale, 20-30 parts by weight of coal gangue, 20-30 parts by weight of clay and 5-10 parts by weight of porous ceramic fiber filler, grind to obtain a mixture powder, add 2-3 parts by weight of polyvinyl alcohol and 1-2 parts by weight of polycarboxylate superplasticizer to the mixture powder, stir in a mixer at 200-300 rpm for 20-30 min to obtain a mixture; S3.2: Inject the mixture into the mold and press it into shape under a pressure of 15-20MPa to obtain shale brick blanks. Dry the shale brick blanks at 60-70℃ until the moisture content is less than 3% to obtain dried brick blanks. S3.3: The dried brick blanks are sintered in a kiln. First, the temperature is raised to 600-650℃ in an air atmosphere at a rate of 2-3℃ / min and held for 1-2 hours. Then, the temperature is raised to 950-1000℃ at a rate of 3-5℃ / min and held for 2-3 hours. Finally, the bricks are cooled to room temperature in the kiln to obtain shale bricks.

7. The preparation process of a thermally insulating shale brick according to claim 1, characterized in that, S4: Thermal insulation treatment of shale bricks, specifically including the following steps: S4.1: Add 10-15 parts by weight of thermal insulation composite material, 2-3 parts by weight of nano silica, 0.5-1 parts by weight of zinc stearate, 5-8 parts by weight of silicone acrylic emulsion, 0.5-1 parts by weight of hydroxyethyl cellulose thickener, 0.5-1 parts by weight of dispersant, 0.1-0.3 parts by weight of defoamer and 15-20 parts by weight of deionized water to a mixer and mix at 800-1000 rpm for 30-40 minutes to obtain the coating slurry; S4.2: Apply the coating slurry to the surface of the shale brick by spraying. The coating thickness is controlled at 1-2 mm. The spraying parameters are: nozzle diameter 1-2 mm, spraying pressure 0.3-0.5 MPa, spraying distance 20-25 cm. After application, let it stand at room temperature for 10-15 min, then dry it at 60-70℃ for 1-2 h, and then cure it at 120-150℃ for 30-40 min to obtain the thermal insulation shale brick.

8. The preparation process of a thermally insulating shale brick according to claim 7, characterized in that, The defoamer in step S4.1 is an organosilicone defoamer.

9. The preparation process of a thermally insulating shale brick according to claim 7, characterized in that, The dispersant in step S4.1 is a sodium polycarboxylate dispersant.

10. A thermal insulation shale brick, characterized in that, It is prepared by the process described in any one of claims 1-9 for preparing thermally insulating shale bricks.

Images