Foaming ceramic and preparation method thereof

Abstract

The invention relates to the technical field of foamed ceramics, in particular to a foamed ceramic and a preparation method thereof. The foamed ceramic comprises the following raw materials in parts by weight: 30-50 parts of waste cathode carbon blocks, 15-30 parts of rice hull ash, 15-30 parts of fly ash, 3-10 parts of calcium carbonate, 3-10 parts of expanded perlite and 2-5 parts of basalt fibers. According to the invention, the waste cathode carbon block is pretreated to form a porous structure, the porous structure and gas decomposed by calcium carbonate are jointly used as a gas source at a high temperature to generate initial pores, and a glass phase formed after rice hull ash activation has certain fluidity during sintering, and can fill pores, adjust pore surface tension and promote uniform expansion of the pores; the basalt fibers are inserted into the matrix in a three-dimensional bracket form, and collapse of pores due to high-temperature shrinkage or gas escape is prevented through physical support, so that the stability and uniformity of the pore structure are ensured, and the heat insulation performance of the foamed ceramic is improved.

Description

Technical Field

[0001] The invention relates to the technical field of foamed ceramics, in particular to a foamed ceramic and a preparation method thereof. Background Art

[0002] Foamed ceramics are high-porosity, closed-cell ceramic materials calcined at high temperatures. They are suitable for exterior wall insulation, fire barriers, and thermal bridge treatment in self-insulating buildings. They are fire-retardant, age-resistant, have a low deformation coefficient, offer stable performance, and are environmentally friendly. They also offer excellent compatibility with base and finish layers, are safe and stable, and can last the life of the building.

[0003] In the existing technology, traditional foam ceramic production relies on a large amount of natural raw materials, which consumes a lot of resources and has high production costs. Its products also have certain limitations in thermal insulation, pressure resistance, and waterproof performance, and cannot fully meet the needs of modern buildings for energy-saving, environmental protection and high-performance materials.

[0004] Based on this, the present invention provides a foamed ceramic and a preparation method thereof. Summary of the Invention

[0005] The object of the present invention is to provide a foamed ceramic and a preparation method thereof. The foamed ceramic prepared by the present invention not only has good thermal insulation properties, but also has excellent compression resistance and waterproof properties, thereby effectively improving the performance of the foamed ceramic.

[0006] To achieve the above object, the present invention provides the following technical solution: a foamed ceramic comprising the following raw materials in parts by weight: 30-50 parts of spent cathode carbon blocks, 15-30 parts of rice husk ash, 15-30 parts of fly ash, 3-10 parts of calcium carbonate, 3-10 parts of expanded perlite, and 2-5 parts of basalt fiber;

[0007] The waste cathode carbon blocks and basalt fibers are pretreated, and the rice husk ash is modified.

[0008] Preferably, the pretreatment steps of the waste cathode carbon block are as follows: crushing and grinding the waste cathode carbon block, sieving it through an 80-120 mesh screen, adding the sieved waste cathode carbon block and the hydrochloric acid solution into a beaker, and placing the beaker in a constant temperature water bath, soaking it at 60-80°C for 2-3h, stirring it continuously at 100-200rpm by a magnetic stirrer during the soaking process to obtain a first mixture, placing the first mixture in a centrifuge for solid-liquid separation to obtain carbon block particles, washing the carbon block particles with deionized water until they are neutral, and then drying them in a drying oven, and the dried carbon block particles The particles are placed in a muffle furnace, heated to 800-900°C at 5°C / min, kept warm for 1-2 hours, and cooled with the furnace to obtain calcined particles. The calcined particles and the nano-modifier are then added to a stirring tank, stirred at 100-200r / min for 5-10 minutes using a magnetic stirrer, anhydrous ethanol is added to the stirring tank, and the stirring tank is placed in an ultrasonic cleaner and ultrasonically dispersed for 30-40 minutes to obtain a second mixture. The second mixture is placed in a drying oven, and the drying temperature is set to 80-100°C for 2-4 hours to complete the pretreatment of the waste cathode carbon block.

[0009] Preferably, in the pretreatment step of the waste cathode carbon block: the concentration of the hydrochloric acid solution is 3-5%, the solid-liquid ratio of the waste cathode carbon block to the hydrochloric acid solution after screening is 5:1, the centrifuge working conditions are 1000-3000 rpm speed for 5-10 min, the drying oven temperature is set at 105°C for 4-6 h, the mass ratio of the calcined particles to the nano-modifier is (30-50): (1-3), and the solid-liquid ratio of the total mass of the calcined particles and the nano-modifier to anhydrous ethanol is (1-2): 1.

[0010] Preferably, the nano-modifier is at least one of nano-titanium dioxide or nano-zinc oxide, and the particle size of the nano-modifier powder is 10-50 nm, and the purity is greater than or equal to 99%.

[0011] Preferably, the modification treatment step of the rice husk ash is as follows: selecting rice husk ash and placing it in a crucible, heating it to 650-750°C at 10°C / min, keeping it warm for 1.5h, cooling it to room temperature and sieving it through a 200-mesh sieve to obtain rice husk material, placing the rice husk material and sodium hydroxide solution in a glass beaker, stirring and activating it at 50-100r / min for 1h with a magnetic stirrer, placing it in a centrifuge for solid-liquid separation, obtaining rice husk particles, and washing the rice husk particles with deionized water until After neutralization, place it in a drying oven, set the temperature to 110℃ for 6 hours to obtain activated rice husk ash, place the activated rice husk ash and the coating solution in a glass beaker, stir it at 200-300r / min with a magnetic stirrer for 2 hours, transfer it to a Buchner funnel, and filter it with a vacuum pump at a vacuum degree of -0.06 to -0.08MPa to obtain a filter cake, place the filter cake in a normal pressure drying oven, set the temperature to 90-100℃, and dry it for 3-4 hours to complete the modification of the rice husk ash.

[0012] Preferably, the coating solution is prepared by placing a silane coupling agent KH-550 and anhydrous ethanol in a glass beaker, stirring at 150 r / min for 5-10 minutes with a mechanical stirrer, and then adding glacial acetic acid dropwise during the stirring process to adjust the pH to 4-5. After the adjustment is completed, stirring is continued at 150 r / min for 10-15 minutes. The mass ratio of the silane coupling agent KH-550 to anhydrous ethanol is 1:19.

[0013] Preferably, the solid-liquid ratio of the rice husk material to the sodium hydroxide solution is 1:3, the concentration of the sodium hydroxide solution is 5-10%, and the solid-liquid ratio of the activated rice husk ash to the coating solution is 1:(3-5).

[0014] Preferably, the pretreatment step of the basalt fiber is: selecting basalt fiber and placing it in a ceramic crucible, placing it in a muffle furnace and heating it to 350° C. at a heating rate of 8° C. / min, keeping it warm for 20 minutes and then cooling it with the furnace to complete the pretreatment of the glass fiber.

[0015] Preferably, the basalt fiber is chopped basalt fiber with a size of 3-5 mm.

[0016] A method for preparing foamed ceramics comprises the following steps:

[0017] Step 1: Weigh the pretreated waste cathode carbon block and basalt fiber, modified rice husk ash, fly ash, calcium carbonate and expanded perlite as needed, place them in a biaxial mixer, and stir at 100-200 r / min for 20-40 minutes to obtain a blank;

[0018] Step 2: placing the blank in a mold and pressing it with a hydraulic molding machine at a pressure of 1-5 MPa to obtain a blank;

[0019] Step 3: Place the blank in a hot air circulation drying oven and dry it at 80-120°C for 8-12 hours to obtain a blank;

[0020] Step 4: Place the green body in a high-temperature kiln, heat it to 600-800℃ at a heating rate of 5-10℃ / min, keep it warm for 1-2h, then heat it to 1000-1200℃ at a heating rate of 3-5℃ / min, keep it warm for 2-4h. After the insulation is completed, cool it to room temperature with the furnace to complete the preparation of foamed ceramics.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the present invention, the porous structure formed by the pre-treatment of the waste cathode carbon block is used together with the gas decomposed by calcium carbonate at high temperature as a gas source to generate initial pores. The glass phase formed after the rice husk ash is activated has a certain fluidity during sintering, which can fill the pore gaps and adjust the pore surface tension, thereby promoting the uniform expansion of the pores. The basalt fiber is interspersed in the matrix in the form of a three-dimensional scaffold, which prevents the pores from collapsing due to high-temperature shrinkage or gas escape through physical support, thereby ensuring the stability and uniformity of the pore structure and improving the thermal insulation performance of the foamed ceramic.

[0023] 2. In the present invention, the activity of the chopped basalt fibers is enhanced after pretreatment. With its own high strength and high modulus characteristics, it is evenly distributed in the matrix like steel bars, sharing stress through bridging and pull-out effects, hindering crack propagation. At the same time, after pretreatment, nano-active sites are formed on the surface of the waste cathode carbon blocks. The rice husk ash is treated at high temperature, activated with alkali solution and surface coated, and its surface energy matches that of other raw materials. The two form a good interface bond with the fly ash and calcium carbonate raw materials when mixed in the blank, and stable chemical bonds and crystal phase structures are generated during firing, thereby enhancing interfacial bonding, avoiding stress concentration, and improving the compressive strength of the foamed ceramic.

[0024] 3. In the present invention, the nano-modification treatment of the waste cathode carbon block forms a dense nano-coating on its surface, which reduces the pathways for moisture to enter the interior of the material. After the rice husk ash is activated with alkali solution and coated with a silane coupling agent, its surface becomes a hydrophobic structure that is not easily wetted by water. During the sintering process, the glass phase formed by the rice husk ash fills the pores inside the material, further sealing the pores and making it more difficult for moisture to enter. The basalt fiber further stabilizes the pore structure of the material, making the pores smaller and more closed, significantly improving the waterproof performance and durability of the material.

[0025] 4. The present invention uses waste cathode carbon blocks, rice husk ash, fly ash industrial and agricultural waste as the main raw materials. Waste cathode carbon blocks are solid waste from the electrolytic aluminum industry, rice husk ash comes from rice processing, and fly ash comes from the coal-fired power generation process. By conducting targeted pretreatment and modification on these wastes, they can fully participate in the preparation process of foamed ceramics, and transform the waste that was originally difficult to dispose of into building materials with high added value. This not only effectively reduces the accumulation of waste, which occupies land resources and pollutes the surrounding environment, but also realizes the recycling of resources and reduces dependence on natural mineral resources. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] It should be noted that the raw materials used in the following experiments are all commercially available raw materials.

[0028] Example 1: The following raw materials were weighed as needed: 30 parts by weight of spent cathode carbon blocks, 15 parts of rice husk ash, 15 parts of fly ash, 3 parts of calcium carbonate, 3 parts of expanded perlite and 2 parts of basalt fiber;

[0029] The spent cathode carbon blocks and basalt fibers are pretreated, and the rice husk ash is modified.

[0030] The pretreatment steps of the waste cathode carbon block are as follows: crushing and grinding the waste cathode carbon block, sieving it through an 80-mesh screen, adding the sieved waste cathode carbon block and hydrochloric acid solution into a beaker, and placing the beaker in a constant temperature water bath, soaking it at 60°C for 2 hours, stirring it continuously at 100 rpm with a magnetic stirrer during the soaking process to obtain a first mixture, placing the first mixture in a centrifuge for solid-liquid separation to obtain carbon block particles, washing the carbon block particles with deionized water until they are neutral, and then drying them in a drying oven. The block particles are placed in a muffle furnace, heated to 800°C at 5°C / min, kept warm for 1 hour, and cooled with the furnace to obtain calcined particles. The calcined particles and nano-modifiers are then added to a stirring tank, stirred at 100r / min for 5 minutes using a magnetic stirrer, and anhydrous ethanol is added to the stirring tank. The stirring tank is placed in an ultrasonic cleaner and ultrasonically dispersed for 30 minutes to obtain a second mixture. The second mixture is placed in a drying oven, and the drying temperature is set to 80°C for 2 hours to complete the pretreatment of the waste cathode carbon block.

[0031] Among them, the liquid in the solid-liquid separation in the centrifuge is treated by calcium salt precipitation method, and the waste gas generated during calcination in the muffle furnace is treated by a two-stage absorption tower.

[0032] In the pretreatment step of the waste cathode carbon block: the concentration of the hydrochloric acid solution is 3%, the solid-liquid ratio of the waste cathode carbon block and the hydrochloric acid solution after screening is 5:1, the centrifuge working conditions are 1000 rpm for 5 minutes, the drying oven temperature is set at 105°C for 4 hours, the mass ratio of the calcined particles to the nano-modifier is 30:1, and the solid-liquid ratio of the total mass of the calcined particles and the nano-modifier to anhydrous ethanol is 1:1.

[0033] The nano modifier is nano titanium dioxide, and the particle size of the nano modifier powder is 10nm, and the purity is greater than or equal to 99%.

[0034] The modification treatment steps of rice husk ash are as follows: select rice husk ash and place it in a crucible, heat it to 650℃ at 10℃ / min, keep it warm for 1.5h, cool it to room temperature, and sieve it through a 200-mesh sieve to obtain rice husk material, place the rice husk material and sodium hydroxide solution in a glass beaker, stir and activate it at 50r / min for 1h with a magnetic stirrer, and then place it in a centrifuge for solid-liquid separation to obtain rice husk particles, wash the rice husk particles with deionized water to neutrality, place it in a drying oven, set the temperature to 110℃ for 6h, and obtain activated rice husk ash, place the activated rice husk ash and the coating solution in a glass beaker, stir it at 200r / min for 2h with a magnetic stirrer, transfer it to a Buchner funnel, and filter it at a vacuum degree of -0.06MPa with a vacuum pump to obtain a filter cake, place the filter cake in a normal pressure drying oven, set the temperature to 90℃, and dry it for 3h to complete the modification treatment of rice husk ash.

[0035] The coating solution was prepared by placing a silane coupling agent KH-550 and anhydrous ethanol in a glass beaker, stirring the mixture at 150 r / min for 5 minutes using a mechanical stirrer. During the stirring process, glacial acetic acid was added dropwise to adjust the pH to a stable pH of 4-5. After the adjustment, stirring was continued at 150 r / min for 10 minutes. The mass ratio of the silane coupling agent KH-550 to the anhydrous ethanol was 1:19.

[0036] The solid-liquid ratio of the rice husk material and the sodium hydroxide solution is 1:3, the concentration of the sodium hydroxide solution is 5%, and the solid-liquid ratio of the activated rice husk ash and the coating solution is 1:3.

[0037] The pretreatment steps of basalt fiber are as follows: basalt fiber is selected and placed in a ceramic crucible, which is then placed in a muffle furnace and heated to 350°C at a heating rate of 8°C / min, kept at this temperature for 20 minutes, and then cooled in the furnace to complete the pretreatment of the glass fiber.

[0038] The basalt fiber uses short-cut basalt fiber with a size of 3mm.

[0039] The preparation method comprises the following steps:

[0040] Step 1: Weigh the pretreated waste cathode carbon block and basalt fiber, modified rice husk ash, fly ash, calcium carbonate and expanded perlite as needed, place them in a biaxial mixer, and stir at 100 r / min for 20 minutes to obtain a blank;

[0041] Step 2: placing the blank in a mold and pressing it with a hydraulic molding machine at a pressure of 1 MPa to obtain a blank;

[0042] Step 3: Place the blank in a hot air circulation drying oven and dry it at 80°C for 8 hours to obtain a blank;

[0043] Step 4: Place the green body in a high-temperature kiln, heat it to 600-800℃ at a heating rate of 5℃ / min, keep it warm for 1 hour, then heat it to 1000℃ at a heating rate of 3℃ / min, keep it warm for 2 hours. After the insulation is completed, cool it to room temperature with the furnace to complete the preparation of foamed ceramics.

[0044] Example 2: The following raw materials were weighed as needed: 40 parts by weight of spent cathode carbon blocks, 22 parts of rice husk ash, 22 parts of fly ash, 7 parts of calcium carbonate, 7 parts of expanded perlite and 3 parts of basalt fiber;

[0045] The spent cathode carbon blocks and basalt fibers are pretreated, and the rice husk ash is modified.

[0046] The pretreatment steps of the waste cathode carbon block are as follows: crushing and grinding the waste cathode carbon block, sieving it through a 100-mesh sieve, adding the sieved waste cathode carbon block and hydrochloric acid solution into a beaker, and placing the beaker in a constant temperature water bath, soaking it at 70°C for 2.5 hours, stirring it continuously at 150 rpm with a magnetic stirrer during the soaking process to obtain a first mixture, placing the first mixture in a centrifuge for solid-liquid separation to obtain carbon block particles, washing the carbon block particles with deionized water until they are neutral, and then drying them in a drying oven. The block particles are placed in a muffle furnace, heated to 850°C at 5°C / min, kept warm for 1.5 hours, and cooled with the furnace to obtain calcined particles. The calcined particles and the nano-modifier are then added to a stirring tank, stirred at 150r / min for 7 minutes using a magnetic stirrer, and then anhydrous ethanol is added to the stirring tank. The stirring tank is placed in an ultrasonic cleaner and ultrasonically dispersed for 35 minutes to obtain a second mixture. The second mixture is placed in a drying oven, and the drying temperature is set to 90°C for 3 hours to complete the pretreatment of the waste cathode carbon block.

[0047] In the pretreatment step of the waste cathode carbon block: the concentration of the hydrochloric acid solution is 4%, the solid-liquid ratio of the waste cathode carbon block and the hydrochloric acid solution after screening is 5:1, the centrifuge working conditions are 2000 rpm for 7 minutes, the drying oven temperature is set at 105°C for 5 hours, the mass ratio of the calcined particles to the nano-modifier is 40:2, and the solid-liquid ratio of the total mass of the calcined particles and the nano-modifier to anhydrous ethanol is 1.5:1.

[0048] The nano modifier is nano titanium dioxide, and the particle size of the nano modifier powder is 35nm, and the purity is greater than or equal to 99%.

[0049] The modification treatment steps of rice husk ash are as follows: select rice husk ash and place it in a crucible, heat it to 700℃ at 10℃ / min, keep it warm for 1.5h, cool it to room temperature, and sieve it through a 200-mesh sieve to obtain rice husk material, place the rice husk material and sodium hydroxide solution in a glass beaker, stir and activate it at 75r / min with a magnetic stirrer for 1h, and then place it in a centrifuge for solid-liquid separation to obtain rice husk particles, wash the rice husk particles with deionized water to neutrality, place it in a drying oven, set the temperature to 110℃ for 6h, and obtain activated rice husk ash, place the activated rice husk ash and the coating solution in a glass beaker, stir it at 250r / min with a magnetic stirrer for 2h, transfer it to a Buchner funnel, and filter it at a vacuum degree of -0.07MPa with a vacuum pump to obtain a filter cake, place the filter cake in a normal pressure drying oven, set the temperature to 95℃, and dry it for 3.5h to complete the modification treatment of rice husk ash.

[0050] The coating solution was prepared by placing a silane coupling agent KH-550 and anhydrous ethanol in a glass beaker, stirring the mixture at 150 r / min for 5-10 minutes using a mechanical stirrer. During the stirring process, glacial acetic acid was added dropwise to adjust the pH to a stable pH of 4-5. After the adjustment, stirring was continued at 150 r / min for 12 minutes. The mass ratio of the silane coupling agent KH-550 to the anhydrous ethanol was 1:19.

[0051] The solid-liquid ratio of the rice husk material and the sodium hydroxide solution is 1:3, the concentration of the sodium hydroxide solution is 7.5%, and the solid-liquid ratio of the activated rice husk ash and the coating solution is 1:4.

[0052] The pretreatment steps of basalt fiber are as follows: basalt fiber is selected and placed in a ceramic crucible, which is then placed in a muffle furnace and heated to 350°C at a heating rate of 8°C / min, kept at this temperature for 20 minutes, and then cooled in the furnace to complete the pretreatment of the glass fiber.

[0053] The basalt fiber uses short-cut basalt fiber with a size of 4mm.

[0054] The preparation method comprises the following steps:

[0055] Step 1: Weigh the pretreated waste cathode carbon block and basalt fiber, modified rice husk ash, fly ash, calcium carbonate and expanded perlite as needed, place them in a biaxial mixer, and stir at 150 r / min for 30 minutes to obtain a blank;

[0056] Step 2: placing the blank in a mold and pressing it with a hydraulic molding machine at a pressure of 3 MPa to obtain a blank;

[0057] Step 3: Place the blank in a hot air circulation drying oven and dry it at 100°C for 10 hours to obtain a blank;

[0058] Step 4: Place the green body in a high-temperature kiln, heat it to 600-800℃ at a heating rate of 7℃ / min, keep it warm for 1.5h, then heat it to 1100℃ at a heating rate of 4℃ / min, keep it warm for 3h. After the insulation is completed, cool it to room temperature with the furnace to complete the preparation of foamed ceramics.

[0059] Example 3: The following raw materials were weighed as needed: 50 parts of spent cathode carbon blocks, 30 parts of rice husk ash, 30 parts of fly ash, 10 parts of calcium carbonate, 10 parts of expanded perlite and 5 parts of basalt fiber;

[0060] The spent cathode carbon blocks and basalt fibers are pretreated, and the rice husk ash is modified.

[0061] The pretreatment steps of the waste cathode carbon block are as follows: crushing and grinding the waste cathode carbon block, sieving it through a 120-mesh screen, adding the sieved waste cathode carbon block and hydrochloric acid solution into a beaker, and placing the beaker in a constant temperature water bath, soaking it at 80°C for 3 hours, stirring it continuously at 200rpm with a magnetic stirrer during the soaking process to obtain a first mixture, placing the first mixture in a centrifuge for solid-liquid separation to obtain carbon block particles, washing the carbon block particles with deionized water until they are neutral, and then drying them in a drying oven. The particles were placed in a muffle furnace, heated to 900°C at 5°C / min, kept warm for 2 hours, and cooled with the furnace to obtain calcined particles. The calcined particles and the nano-modifier were then added to a stirring tank. After stirring at 200r / min for 10 minutes using a magnetic stirrer, anhydrous ethanol was added to the stirring tank, and the stirring tank was placed in an ultrasonic cleaner for ultrasonic dispersion for 40 minutes to obtain a second mixture. The second mixture was placed in a drying oven, and the drying temperature was set to 100°C for 4 hours to complete the pretreatment of the waste cathode carbon block.

[0062] In the pretreatment step of the waste cathode carbon block: the concentration of the hydrochloric acid solution is 5%, the solid-liquid ratio of the waste cathode carbon block and the hydrochloric acid solution after screening is 5:1, the centrifuge working conditions are 3000 rpm for 5-10 minutes, the drying oven temperature is set at 105°C for 6 hours, the mass ratio of the calcined particles to the nano-modifier is 50:3, and the solid-liquid ratio of the total mass of the calcined particles and the nano-modifier to anhydrous ethanol is 2:1.

[0063] The nano modifier is nano zinc oxide, and the particle size of the nano modifier powder is 50nm and the purity is greater than or equal to 99%.

[0064] The modification treatment steps of rice husk ash are as follows: select rice husk ash and place it in a crucible, heat it to 750℃ at 10℃ / min, keep it warm for 1.5h, cool it to room temperature, and sieve it through a 200-mesh sieve to obtain rice husk material, place the rice husk material and sodium hydroxide solution in a glass beaker, stir and activate it at 100r / min for 1h with a magnetic stirrer, and then place it in a centrifuge for solid-liquid separation to obtain rice husk particles, wash the rice husk particles with deionized water to neutrality, place it in a drying oven, set the temperature to 110℃ for 6h, and obtain activated rice husk ash, place the activated rice husk ash and the coating solution in a glass beaker, stir it at 300r / min for 2h with a magnetic stirrer, transfer it to a Buchner funnel, and filter it at a vacuum degree of -0.08MPa with a vacuum pump to obtain a filter cake, place the filter cake in a normal pressure drying oven, set the temperature to 100℃, and dry it for 4h to complete the modification treatment of rice husk ash.

[0065] The coating solution was prepared by placing a silane coupling agent KH-550 and anhydrous ethanol in a glass beaker, stirring the mixture at 150 r / min for 10 min using a mechanical stirrer. During the stirring process, glacial acetic acid was added dropwise to adjust the pH to a stable pH of 4-5. After the adjustment, stirring was continued at 150 r / min for 15 min. The mass ratio of the silane coupling agent KH-550 to the anhydrous ethanol was 1:19.

[0066] The solid-liquid ratio of the rice husk material and the sodium hydroxide solution is 1:3, the concentration of the sodium hydroxide solution is 10%, and the solid-liquid ratio of the activated rice husk ash and the coating solution is 1:5.

[0067] The pretreatment steps of basalt fiber are as follows: basalt fiber is selected and placed in a ceramic crucible, which is then placed in a muffle furnace and heated to 350°C at a heating rate of 8°C / min, kept at this temperature for 20 minutes, and then cooled in the furnace to complete the pretreatment of the glass fiber.

[0068] The basalt fiber uses short-cut basalt fiber with a size of 5mm.

[0069] The preparation method comprises the following steps:

[0070] Step 1: Weigh the pretreated waste cathode carbon block and basalt fiber, modified rice husk ash, fly ash, calcium carbonate and expanded perlite as needed, place them in a biaxial mixer, and stir at 200 r / min for 40 minutes to obtain a blank;

[0071] Step 2: placing the blank in a mold and pressing it with a hydraulic molding machine at a pressure of 5 MPa to obtain a blank;

[0072] Step 3: Place the blank in a hot air circulation drying oven and dry it at 120°C for 12 hours to obtain a blank;

[0073] Step 4: Place the green body in a high-temperature kiln, heat it to 800°C at a heating rate of 10°C / min, keep it warm for 2 hours, then heat it to 1200°C at a heating rate of 5°C / min, keep it warm for 4 hours. After the insulation is completed, cool it to room temperature with the furnace to complete the preparation of the foamed ceramic.

[0074] Comparative Example 1: The difference between this comparative example and Experiment 1 is that no basalt fiber is added in this comparative example.

[0075] Comparative Example 2: The difference between this comparative example and Experiment 1 is that the waste cathode carbon blocks are not pretreated in this comparative example.

[0076] Comparative Example 3: The difference between this comparative example and Experiment 1 is that the rice husk ash was not modified in this comparative example.

[0077] Comparative Example 4: The difference between this comparative example and Experiment 1 is that the basalt fiber is not pretreated in this comparative example.

[0078] Performance test: The performance test was performed on the foamed ceramics prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4:

[0079] Thermal conductivity test: According to GB / T10294-2008 "Insulation materials - Determination of steady-state thermal resistance and related properties - Guarded hot plate method", the test is conducted using a guarded hot plate thermal conductivity meter. The sample is cut into test pieces with a size of 300mm × 300mm × 25mm. In an environment with a temperature of (25±1)°C and a relative humidity of (50±5)%, the amount of heat passing through the sample under steady-state heat transfer conditions is measured, and the thermal conductivity coefficient is calculated.

[0080] Compressive strength test: Refer to GB / T32983-2016 "Foam Ceramic" and use an electronic universal testing machine to test. The sample is processed into a cubic specimen with dimensions of 50mm×50mm×50mm. Pressure is applied at a rate of (1.5±0.2)mm / min. The maximum load at sample failure is recorded, and the compressive strength is calculated using the formula;

[0081] Water absorption test: According to GB / T25993-2010 "Test method for water absorption of building sanitary ceramics", the water absorption rate is measured by boiling method;

[0082] The obtained test data are recorded in the following table:

[0083]

[0084] By comparing and analyzing the relevant data in the table, it can be seen that the foamed ceramic prepared by the present invention not only has good thermal insulation properties, but also has excellent compressive and waterproof properties. This shows that the foamed ceramic and its preparation method provided by the present invention have a broader market prospect and are more suitable for promotion.

[0085] Throughout this specification, references to terms such as "one embodiment," "example," and "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0086] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A foamed ceramic, characterized in that: The invention comprises the following raw materials in parts by weight: 30-50 parts of waste cathode carbon blocks, 15-30 parts of rice husk ash, 15-30 parts of fly ash, 3-10 parts of calcium carbonate, 3-10 parts of expanded perlite and 2-5 parts of basalt fiber; The waste cathode carbon blocks and basalt fibers are pretreated, and the rice husk ash is modified.

2. A foamed ceramic according to claim 1, characterized in that: The pretreatment steps of the waste cathode carbon block are as follows: crushing and grinding the waste cathode carbon block, sieving it through an 80-120 mesh screen, adding the sieved waste cathode carbon block and hydrochloric acid solution into a beaker, placing the beaker in a constant temperature water bath, soaking it at 60-80°C for 2-3 hours, stirring it continuously at 100-200rpm with a magnetic stirrer during the soaking process to obtain a first mixture, placing the first mixture in a centrifuge for solid-liquid separation to obtain carbon block particles, washing the carbon block particles with deionized water until they are neutral, placing them in a drying oven for drying, and placing the dried carbon block particles in a centrifuge. In a muffle furnace, the temperature is raised to 800-900°C at 5°C / min, kept warm for 1-2 hours, and cooled with the furnace to obtain calcined particles. The calcined particles and the nano-modifier are then added to a stirring tank. A magnetic stirrer is used to stir at 100-200r / min for 5-10 minutes. Anhydrous ethanol is added to the stirring tank, and the stirring tank is placed in an ultrasonic cleaner for ultrasonic dispersion for 30-40 minutes to obtain a second mixture. The second mixture is placed in a drying oven and the drying temperature is set to 80-100°C for 2-4 hours to complete the pretreatment of the waste cathode carbon block.

3. The foamed ceramic according to claim 1, characterized in that: In the pretreatment step of the waste cathode carbon block: the concentration of the hydrochloric acid solution is 3-5%, the solid-liquid ratio of the waste cathode carbon block to the hydrochloric acid solution after screening is 5:1, the centrifuge working conditions are 1000-3000 rpm for 5-10 minutes, the drying box is set at a temperature of 105°C for 4-6 hours, the mass ratio of the calcined particles to the nano-modifier is (30-50): (1-3), and the solid-liquid ratio of the total mass of the calcined particles and the nano-modifier to anhydrous ethanol is (1-2):

1.

4. The foamed ceramic according to claim 1, characterized in that: The nano modifier is at least one of nano titanium dioxide or nano zinc oxide, and the particle size of the nano modifier powder is 10-50nm and the purity is greater than or equal to 99%.

5. The foamed ceramic according to claim 1, characterized in that: The rice husk ash modification treatment steps are as follows: selecting rice husk ash and placing it in a crucible, heating it to 650-750°C at 10°C / min, keeping it warm for 1.5 hours, cooling it to room temperature, and sieving it through a 200-mesh sieve to obtain rice husk material; placing the rice husk material and sodium hydroxide solution in a glass beaker, stirring and activating it at 50-100 r / min for 1 hour with a magnetic stirrer, and then placing it in a centrifuge for solid-liquid separation to obtain rice husk particles; washing the rice husk particles with deionized water until they are neutral; After that, it was placed in a drying oven, set at 110°C for 6 hours to obtain activated rice husk ash, and the activated rice husk ash and the coating solution were placed in a glass beaker, stirred at 200-300r / min for 2 hours by a magnetic stirrer, transferred to a Buchner funnel, and filtered by a vacuum pump at a vacuum degree of -0.06 to -0.08MPa to obtain a filter cake, and the filter cake was placed in a normal pressure drying oven, set at 90-100°C, and dried for 3-4 hours to complete the modification of the rice husk ash.

6. The foamed ceramic according to claim 1, characterized in that: The coating solution is prepared by placing a silane coupling agent KH-550 and anhydrous ethanol in a glass beaker, stirring the mixture at 150 r / min for 5-10 minutes using a mechanical stirrer, and then adding glacial acetic acid dropwise during the stirring process to adjust the pH to a stable pH of 4-5. After the adjustment is completed, stirring is continued at 150 r / min for 10-15 minutes. The mass ratio of the silane coupling agent KH-550 to the anhydrous ethanol is 1:

19.

7. The foamed ceramic according to claim 1, characterized in that: The solid-liquid ratio of the rice husk material to the sodium hydroxide solution is 1:3, the concentration of the sodium hydroxide solution is 5-10%, and the solid-liquid ratio of the activated rice husk ash to the coating solution is 1:(3-5).

8. The foamed ceramic according to claim 1, characterized in that: The basalt fiber pretreatment steps are as follows: selecting basalt fiber and placing it in a ceramic crucible, placing it in a muffle furnace and heating it to 350° C. at a heating rate of 8° C. / min, keeping the temperature for 20 minutes and then cooling it with the furnace to complete the pretreatment of the glass fiber.

9. The foamed ceramic according to claim 1, characterized in that: The basalt fibers are chopped basalt fibers with a size of 3-5 mm.

10. A method for preparing a foamed ceramic, referring to the foamed ceramic according to any one of claims 1 to 9, characterized in that: The following steps are included: Step 1: Weigh the pretreated waste cathode carbon block and basalt fiber, modified rice husk ash, fly ash, calcium carbonate and expanded perlite as needed, place them in a biaxial mixer, and stir at 100-200 r / min for 20-40 minutes to obtain a blank; Step 2: placing the blank in a mold and pressing it with a hydraulic molding machine at a pressure of 1-5 MPa to obtain a blank; Step 3: Place the blank in a hot air circulation drying oven and dry it at 80-120°C for 8-12 hours to obtain a blank; Step 4: Place the green body in a high-temperature kiln, heat it to 600-800℃ at a heating rate of 5-10℃ / min, keep it warm for 1-2h, then heat it to 1000-1200℃ at a heating rate of 3-5℃ / min, keep it warm for 2-4h. After the insulation is completed, cool it to room temperature with the furnace to complete the preparation of foamed ceramics.

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