Preparation method of low water absorption and high temperature resistant dry granitic rock plate

Abstract

The application discloses a preparation method of a dry-granular rock plate with low water absorption and high temperature resistance, belongs to the technical field of ceramic materials, and aims at solving the technical problem of lacking the optimization of the low water absorption, high temperature resistance and wear resistance of the dry-granular rock plate in the prior art, and specifically comprises the following steps: firstly, uniformly spreading the prepared dry-granular glaze on the surface of a rock plate base to form a rock plate base with a dry-granular glaze layer; and then, drying and firing the rock plate base with the dry-granular glaze layer to obtain the dry-granular rock plate with low water absorption and high temperature resistance. The low water absorption, high temperature resistance and wear resistance of the prepared dry-granular rock plate are further optimized through the synergistic effect among the prepared composite powder, modified corundum, ceramic nano powder and reinforcing powder.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and specifically to a method for preparing a dry-grained rock slab with low water absorption and high temperature resistance. Background Technology

[0002] Ceramic slabs, with their advantages of large size, high quality and decorative properties, have been widely used in architectural cladding and home countertops. Dry granulation glaze technology can give the slabs a three-dimensional texture and matte finish, making it the mainstream preparation method for high-end slabs. However, traditional dry granulation slabs mostly use conventional glaze systems and simple granulation processes, and there is still room for improvement in terms of component design, interface structure and performance synergy.

[0003] Currently, dry granule glazes generally suffer from problems such as single composition and weak interfacial bonding. The glaze layer lacks sufficient density after sintering, and there are many internal pores and interfacial defects, resulting in high water absorption of the slabs. This makes them prone to water seepage and staining, and long-term use can easily breed stains and mold, affecting safety and aesthetics. At the same time, conventional dry granule glazes have poor thermal stability. During hot and cold cycles, internal stress is easily generated due to thermal expansion mismatch, leading to problems such as glaze cracking and peeling. Their high temperature resistance and thermal shock resistance are insufficient, limiting their application in high-temperature contact scenarios. In addition, traditional dry granule glazes have low hardness and poor wear resistance. Long-term friction can easily cause scratches, exposure of the substrate, and other defects. Furthermore, the bonding strength between the glaze layer and the substrate is insufficient, resulting in weak impact resistance. They are easily damaged by external impacts, and their overall mechanical properties need to be improved.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a dry granulated rock slab with low water absorption and high temperature resistance, in order to solve the technical problem of lacking further optimization of the low water absorption, high temperature resistance and wear resistance of dry granulated rock slabs in the prior art.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a low-water-absorption, high-temperature-resistant dry granular rock slab, comprising the following steps: S1. After passing the expanded perlite through a 40-mesh sieve, add it to a high-speed mixing granulator and stir at a speed of 40-50 r / min. At the same time, spray the chitosan aqueous solution into it using a spray method and add the mixed powder simultaneously. Continue mixing and granulating under stirring conditions for 10-20 minutes. After the granules are formed, take them out and dry them in an 80℃ oven for 2-3 hours. Pass them through a 60-mesh sieve to obtain dry granule glaze. The mixed powder consists of quartz, mullite, composite powder, modified corundum, ceramic nanopowder and reinforcing powder. S2. Spread the dry granule glaze evenly on the surface of the rock slab substrate to form a rock slab substrate with a dry granule glaze layer. S3. The rock slab substrate with dry granule glaze layer is dried and fired to obtain a dry granule rock slab with low water absorption and high temperature resistance.

[0007] Furthermore, in step S1, the spreading thickness is 0.8-1mm; in step S2, the drying conditions for the rock slab substrate are: drying at 100-110℃ for 30-40min; the firing conditions for the dried rock slab substrate are: firing at 1100-1250℃ for 60-80min.

[0008] Further, in step S1, the method for preparing the mixed powder is as follows: quartz, mullite, composite powder, modified corundum, ceramic nanopowder and reinforcing powder are added to a ball mill and ball-milled, and then passed through a 300-mesh sieve to obtain the mixed powder; the ratio of the amount of quartz, mullite, composite powder, modified corundum, ceramic nanopowder and reinforcing powder is 18g:12g:25-30g:20-25g:5-8g:10-15g.

[0009] Furthermore, the ratio of expanded perlite, chitosan aqueous solution, and mixed powder is 3g:4-5mL:17-18g, and the mass fraction of the chitosan aqueous solution is 2%.

[0010] Furthermore, the preparation method of the composite powder is as follows: bismuth trioxide, zinc oxide, boron oxide, silicon dioxide, and sodium oxide are ground through a 200-mesh sieve, placed in a crucible, heated to 1100-1200℃ at a heating rate of 5℃ / min and held for 20-30 minutes, then poured into cold water for quenching, removed, and added to a ball mill. Using deionized water as the dispersion medium, the mixture is wet-milled at 300 r / min for 2-3 hours. After ball milling, it is placed in a vacuum drying oven and dried at 80℃ to constant weight. The powder is then removed and passed through a 300-mesh sieve to obtain the composite powder. The ratio of bismuth trioxide, zinc oxide, boron oxide, silicon dioxide, and sodium oxide is 3.6-3.8 g: 0.3-0.5 g: 0.5-0.7 g: 0.2-0.25 g: 0.1 g.

[0011] Further, the preparation method of the modified corundum is as follows: sodium chloride, potassium chloride, corundum micro powder and zirconium powder are ground in a mortar, passed through a 200-mesh sieve, placed in a quartz tube, and sent into a tube furnace under an argon atmosphere. The temperature is increased to 700℃ at a heating rate of 5℃ / min and held for 60-80 min, then increased to 900-1000℃ at a heating rate of 5℃ / min and held for 60-90 min. After the reaction is completed, the furnace is cooled to 500℃, the quartz tube is removed, and the product is cooled to room temperature in air. The product is soaked in deionized water at 60-80℃ for 100-120 min, filtered, and finally washed with deionized water until the washing liquid is neutral. The product is then placed in a vacuum drying oven and dried at 80℃ to constant weight to obtain modified corundum. The ratio of sodium chloride, potassium chloride, corundum micro powder and zirconium powder is 1.7-2g:1.7-2g:5g:1g.

[0012] Furthermore, the preparation method of the ceramic nanopowder is as follows: barium carbonate, strontium carbonate and niobium pentoxide are added to a ball mill and ball-milled for 5-6 hours with anhydrous ethanol as the dispersion medium. The ball-milled slurry is then placed in a drying oven and dried at 60°C to constant weight. Next, it is transferred to a high-temperature furnace and kept at 1000°C for 3-4 hours. After that, it is taken out and ground, and then passed through a 200-mesh sieve. Then, the product is placed in a high-temperature furnace and calcined at 1300-1400°C for 5-6 hours. After sintering, it is cooled to room temperature with the furnace, and then the product is ground again and passed through a 200-mesh sieve to obtain ceramic nanopowder.

[0013] Furthermore, the ratio of barium carbonate, strontium carbonate, and niobium pentoxide is 1g:0.75g:2.3-2.7g.

[0014] Furthermore, the preparation method of the reinforcing powder is as follows: Hafnium, molybdenum, boron, silicon monomer powders and borosilicate glass powder are added to a ball mill, anhydrous ethanol is used as the dispersion medium, and the mixture is ball-milled at 400 r / min for 4-5 h. The mixture is then removed and placed in a vacuum drying oven, dried at 60°C to constant weight, placed in a cylindrical forming mold, and pressed into a green body under a pressure of 200 MPa. The green body is then placed in the working chamber of a self-propagating high-temperature synthesis reaction device, and ignited by passing a molybdenum wire electrode under an argon atmosphere. After the reaction is completed, the product is allowed to cool naturally to room temperature, then ball-milled again through a 200-mesh sieve, and then placed into a graphite mold. Under a pressure of 25 MPa and a vacuum, the temperature is raised to 1400°C at a heating rate of 100°C / min and held for 5 min. After cooling to room temperature with the furnace, the reinforcing powder is obtained.

[0015] Furthermore, the ratio of the monomer powders of hafnium, molybdenum, boron, and silicon to borosilicate glass powder is 24-27g:0.7-0.9g:0.25g:0.7-0.8g:1g.

[0016] The present invention has the following beneficial effects: 1. The composite powder of the present invention uses boron oxide and silicon dioxide as the network skeleton, combined with bismuth trioxide, zinc oxide and other components to form an amorphous glass phase with good high-temperature melting properties. At high temperature, it can fully fill the gaps between particles and form a continuous and dense matrix. The modified corundum is surface-modified with zirconium element, which significantly improves the surface energy and interfacial compatibility. It can be tightly bonded with the glaze phase and reduce interfacial porosity. The ceramic nanoparticles are small in size and uniformly dispersed, which can fill the residual gaps between micron-sized particles and achieve multi-level dense packing. The reinforcing powder is composed of a high-melting-point ceramic phase and a borosilicate glass phase. At high temperature, it has both skeleton support and liquid phase filling functions. The components work together to construct a continuous, dense glaze layer structure with high closed-porosity, effectively blocking water penetration channels and giving the dry granular rock slab stable and excellent low water absorption characteristics.

[0017] 2. The composite powder of this invention can adjust the high-temperature viscosity and thermal expansion coefficient of the glaze phase, reduce the internal stress under thermal cycling, and modify the corundum with corundum as the core and zirconium modification layer as the interface transition. It has high melting point, high heat resistance and good thermal shock stability, and can withstand drastic temperature fluctuations without cracking. The ceramic nanopowder has a stable crystal structure and does not change its crystal form at high temperatures, which can maintain the integrity of the glaze layer at high temperatures. The powder contains ultra-high temperature ceramic phases such as hafnium diboride and molybdenum disilicide, which have extremely strong thermal stability and can maintain the integrity of the skeleton in high-temperature environments. The synergistic effect of each component allows the dry granular rock slab to maintain its structural integrity after alternating hot and cold cycles, without glaze peeling or internal cracks, and greatly improves its high temperature resistance and thermal shock resistance.

[0018] 3. The modified corundum of this invention has high hardness and wear resistance. After surface modification, it is firmly bonded to the glaze and is not easily detached under friction. The reinforcing powder is a composite of high-hardness ceramic phase and tough glass phase, which not only improves the surface wear resistance, but also absorbs impact energy and relieves stress concentration through the tough phase. The ceramic nanopowder can refine the grains and strengthen the grain boundaries, improving the overall mechanical properties of the glaze layer. After the composite powder is melted at high temperature, it forms a high-strength glass substrate, which firmly binds the hard particles. Under the synergistic effect, the wear resistance of the dry granulated rock slab surface is significantly improved, and the friction and scratch resistance are excellent. At the same time, it is not easy to crack or break under impact load, and it has excellent impact resistance and structural stability. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In this application, the expanded perlite is selected from Yiran Mineral Products Processing Plant in Lingshou County, with a particle size of 30μm and an expansion ratio of 5 times. In this application, the corundum micro powder is selected from Gongyi Yuying Refractory Materials Co., Ltd., with model number YY021 and order number YY-01. In this application, the borosilicate glass powder is selected from Hebei Wensheng New Material Technology Co., Ltd., and the particle size is 4 μm.

[0021] Example 1: This example provides a method for preparing a dry granulated rock slab with low water absorption and high temperature resistance, including the following steps: S1. Preparation of composite powder Weigh out 360g of bismuth trioxide, 30g of zinc oxide, 50g of boron oxide, 20g of silicon dioxide, and 10g of sodium oxide. Grind them through a 200-mesh sieve, place them in a crucible, heat them to 1100℃ at a heating rate of 5℃ / min and hold for 20min. Then pour them into cold water for quenching, remove them, and put them into a ball mill. Use deionized water as the dispersion medium and wet ball mill at a speed of 300r / min for 2h. After ball milling, place them in a vacuum drying oven and dry them at 80℃ to constant weight. Remove them and pass them through a 300-mesh sieve to obtain composite powder.

[0022] During the reaction, under high temperature conditions, boron oxide and silicon dioxide construct a disordered glass network framework, while bismuth trioxide and zinc oxide serve as network fillers or modifiers. Sodium oxide acts as a flux to promote the formation of a eutectic liquid phase and ion diffusion, enabling the components to be fully homogenized at the atomic scale to form a high-temperature melt. Subsequently, the extreme supercooling generated by cold water quenching kinetically inhibits the formation and growth of crystal nuclei, freezing the disordered structure of the high-temperature melt into an amorphous glass block. Finally, through mechanical ball milling and sieving, the glass block is physically broken into micron-sized composite glass powder.

[0023] S2, Preparation of modified corundum Weigh out 170g sodium chloride, 170g potassium chloride, 500g corundum powder and 100g zirconium powder, grind them in a mortar, pass through a 200-mesh sieve, place them in a quartz tube, and put them into a tube furnace under an argon atmosphere. Heat to 700℃ at a heating rate of 5℃ / min and hold for 60min, then heat to 900℃ at a heating rate of 5℃ / min and hold for 60min. After the reaction is complete, cool the furnace to 500℃, remove the quartz tube, and cool to room temperature in air. Soak the product in deionized water at 60℃ for 100min, filter, and finally wash the product with deionized water until the washing solution is neutral. Place it in a vacuum drying oven and dry at 80℃ to constant weight to obtain modified corundum.

[0024] During the reaction, under an argon protective atmosphere, sodium chloride and potassium chloride eutectic salts first melt to form a high-temperature ionic liquid reaction medium, which reduces the interfacial tension between solid particles and provides ion transport channels. As the temperature rises, highly active metallic zirconium powder dissolves and diffuses in the molten salt, migrates directionally and wets the surface of corundum micro powder, and forms a strong Zr-O-Al interface through physical adsorption and micro-area interfacial diffusion. Finally, after cooling, solidification and water washing to remove salt, a uniform and dense zirconium coating layer is constructed in situ on the corundum surface, thereby achieving surface modification of corundum.

[0025] S3. Preparation of ceramic nanopowder Weigh out 100g of barium carbonate, 75g of strontium carbonate, and 230g of niobium pentoxide and add them to a ball mill. After ball milling for 5 hours with anhydrous ethanol as the dispersion medium, place the ball-milled slurry in a drying oven and dry it at 60°C to constant weight. Then transfer it to a high-temperature furnace and keep it at 1000°C for 3 hours. After that, take it out and grind it, and pass it through a 200-mesh sieve. Then place the product in a high-temperature furnace and calcine it at 1300°C for 5 hours. After sintering, cool it to room temperature with the furnace and grind the product again, and pass it through a 200-mesh sieve to obtain ceramic nanopowder.

[0026] During the reaction, barium carbonate, strontium carbonate, and niobium pentoxide are refined and then pre-calcined to decompose the carbonates into active barium oxide and strontium oxide. These react with niobium pentoxide to form an intermediate phase, which is then calcined at high temperature. Through complete solid-phase reaction and ion substitution in situ, a single-phase tungsten bronze-type barium strontium niobate solid solution is generated. After furnace cooling, the solution is ground and sieved to obtain tungsten bronze-structured ceramic nanopowder with high crystallinity and pure phase.

[0027] S4. Preparation of reinforced powder Weigh out 240g of hafnium, 7g of molybdenum, 2.5g of boron, 7g of silicon monomer powder and 10g of borosilicate glass powder and add them to a ball mill. Use anhydrous ethanol as the dispersion medium and ball mill at 400 r / min for 4 hours. Remove the powder and place it in a vacuum drying oven. Dry it at 60℃ to constant weight. Place it in a cylindrical forming mold and press it into a green body under a pressure of 200MPa. Place the green body into the working chamber of a self-propagating high-temperature synthesis reaction device and ignite it with a molybdenum wire electrode under an argon atmosphere. After the reaction is completed, let the product cool naturally to room temperature. Then, ball mill it again through a 200-mesh sieve and put it into a graphite mold. Under a pressure of 25MPa and a vacuum, heat the product to 1400℃ at a heating rate of 100℃ / min and hold it for 5 minutes. Then, cool it to room temperature with the furnace to obtain the reinforced powder.

[0028] During the reaction, elemental powders of hafnium, molybdenum, boron, and silicon react with borosilicate glass powder in an argon atmosphere through a self-propagating high-temperature synthesis process, resulting in an in-situ exothermic reaction. This reaction causes hafnium to react with boron to form hafnium diboride and molybdenum to react with silicon to form molybdenum disilicide ceramic phases. The borosilicate glass melts at the high reaction temperature, uniformly encapsulating and binding the ceramic particles. Subsequently, the mixture is sintered by spark plasma, and under high temperature and pressure, the liquid phase fluidity and electric field activation effect of the borosilicate glass are utilized to fill the interparticle gaps and promote densification. Finally, a reinforced powder uniformly composited with hafnium diboride and molybdenum disilicide ceramic phases and borosilicate glass phases is obtained.

[0029] S5. Preparation of dry granular glaze Weigh out 180g of quartz, 120g of mullite, 250g of composite powder, 200g of modified corundum, 50g of ceramic nanopowder and 100g of reinforcing powder, add them to a ball mill and ball mill them, then pass them through a 300-mesh sieve to obtain a mixed powder. A2. 300g of expanded perlite was passed through a 40-mesh sieve. The sieved expanded perlite was added to a high-speed mixing granulator and stirred at a speed of 40r / min. At the same time, 400mL of 2wt% chitosan aqueous solution was sprayed into the mixture, and 1700g of mixed powder was added simultaneously. The mixture was stirred and granulated for 10min. After the granules were formed, they were taken out and dried in an 80℃ oven for 2h. The granules were then passed through a 60-mesh sieve to obtain dry granule glaze.

[0030] In a low-speed shear field, the atomized chitosan aqueous solution acts as a liquid-phase bridging agent, preferentially wetting the porous and rough expanded perlite surface. It utilizes its surface tension and viscosity to construct a highly adhesive cementing layer. At the same time, micron-sized mixed powders continuously collide and embed themselves into this adhesive layer under mechanical tumbling. Through mechanical interlocking and intermolecular forces, they are firmly anchored to the perlite matrix, and finally dried and cured to form a core-shell type dry granular glaze.

[0031] S6. Preparation of low-water-absorption, high-temperature-resistant dry-grained rock slabs The dry granule glaze is evenly spread on the surface of the rock slab substrate to form a rock slab substrate with a surface layer of 0.8mm dry granule glaze. Next, the rock slab substrate with dry granule glaze layer is first placed in a hot air circulating drying chamber and dried at 100°C for 30 minutes. Then, it is transferred to a roller kiln and fired at 1100°C for 60 minutes. After firing, it is cooled to room temperature with the roller kiln to obtain a dry granule rock slab with low water absorption and high temperature resistance.

[0032] During the hot air circulation drying stage, the chitosan binder on the surface of the slab substrate undergoes a glass transition through physical dehydration, initially solidifying to form a rigid skeleton to prevent the dry granule layer from collapsing before entering the kiln. Then, after entering the roller kiln firing stage, the composite powder in the dry granule glaze melts with quartz to form a high-viscosity liquid-phase glass matrix. Under the action of surface tension, this liquid phase wets and encapsulates high-melting-point modified corundum, mullite, ceramic nanopowder, and reinforcing powder, while penetrating into the porous expanded perlite core to form a mechanical interlock. As the holding time progresses, the liquid phase diffuses and chemically bonds at the interface with the matrix, forming a dense glaze-body integrated structure after cooling. This structure not only utilizes the skeleton of corundum and mullite to achieve high temperature resistance and low water absorption, but also preserves the microscopic three-dimensional morphology of the dry granule surface by controlling the viscosity of the liquid phase.

[0033] Example 2: This example provides a method for preparing a dry granulated rock slab with low water absorption and high temperature resistance, including the following steps: S1. Preparation of composite powder Weigh out 370g of bismuth trioxide, 40g of zinc oxide, 60g of boron oxide, 22g of silicon dioxide, and 10g of sodium oxide. Grind them through a 200-mesh sieve, place them in a crucible, heat them to 1150℃ at a heating rate of 5℃ / min and hold for 25min. Then pour them into cold water for quenching, remove them, and put them into a ball mill. Use deionized water as the dispersion medium and wet ball mill them at a speed of 300r / min for 2.5h. After ball milling, place them in a vacuum drying oven and dry them at 80℃ to constant weight. Remove them and pass them through a 300-mesh sieve to obtain composite powder.

[0034] S2, Preparation of modified corundum Weigh out 185g sodium chloride, 185g potassium chloride, 500g corundum powder and 100g zirconium powder, grind them in a mortar, pass through a 200-mesh sieve, place them in a quartz tube, and put them into a tube furnace under an argon atmosphere. Heat to 700℃ at a heating rate of 5℃ / min and hold for 70min, then heat to 950℃ at a heating rate of 5℃ / min and hold for 75min. After the reaction is complete, cool the furnace to 500℃, remove the quartz tube, and cool to room temperature in air. Soak the product in deionized water at 70℃ for 110min, filter, and finally wash the product with deionized water until the washing solution is neutral. Place it in a vacuum drying oven and dry at 80℃ to constant weight to obtain modified corundum.

[0035] S3. Preparation of ceramic nanopowder Weigh out 100g of barium carbonate, 75g of strontium carbonate, and 250g of niobium pentoxide and add them to a ball mill. After ball milling for 5.5 hours with anhydrous ethanol as the dispersion medium, place the ball-milled slurry in a drying oven and dry it at 60°C to constant weight. Then transfer it to a high-temperature furnace and heat it at 1000°C for 3.5 hours. After that, take it out and grind it, and pass it through a 200-mesh sieve. Then place the product in a high-temperature furnace and calcine it at 1350°C for 5.5 hours. After sintering, cool it to room temperature with the furnace and grind the product again, and pass it through a 200-mesh sieve to obtain ceramic nanopowder.

[0036] S4. Preparation of reinforced powder Weigh out 255g of hafnium, 8g of molybdenum, 2.5g of boron, 7.5g of silicon monomer powder and 10g of borosilicate glass powder and add them to a ball mill. Use anhydrous ethanol as the dispersion medium and ball mill at 400 r / min for 4.5h. Remove and place in a vacuum drying oven and dry to constant weight at 60℃. Place in a cylindrical forming mold and press into a green body under 200MPa pressure. Place the green body into the working chamber of a self-propagating high-temperature synthesis reaction device and ignite it with a molybdenum wire electrode under an argon atmosphere. After the reaction is completed, allow the product to cool naturally to room temperature, ball mill again through a 200-mesh sieve, and then place it into a graphite mold. Under 25MPa pressure and vacuum conditions, heat to 1400℃ at a heating rate of 100℃ / min and hold for 5min. Then cool to room temperature with the furnace to obtain the reinforced powder.

[0037] S5. Preparation of dry granular glaze Weigh out 180g of quartz, 120g of mullite, 275g of composite powder, 225g of modified corundum, 65g of ceramic nanopowder and 125g of reinforcing powder, add them to a ball mill and ball mill them, then pass them through a 300-mesh sieve to obtain a mixed powder. A2. 300g of expanded perlite was passed through a 40-mesh sieve. The sieved expanded perlite was added to a high-speed mixing granulator and stirred at a speed of 45r / min. At the same time, 450mL of 2wt% chitosan aqueous solution was sprayed into the mixture, and 1750g of mixed powder was added simultaneously. The mixture was stirred and granulated for 15min. After the granules were formed, they were removed and dried in an 80℃ oven for 2.5h. The granules were then passed through a 60-mesh sieve to obtain dry granule glaze.

[0038] S6. Preparation of low-water-absorption, high-temperature-resistant dry-grained rock slabs The dry granule glaze is evenly spread on the surface of the rock slab substrate to form a rock slab substrate with a surface layer of 0.9mm dry granule glaze. Next, the rock slab substrate with dry granule glaze layer is placed in a hot air circulating drying chamber and dried at 105°C for 35 minutes. Then, it is transferred to a roller kiln and fired at 1175°C for 70 minutes. After firing, it is cooled to room temperature with the roller kiln to obtain a dry granule rock slab with low water absorption and high temperature resistance.

[0039] Example 3: This example provides a method for preparing a dry granulated rock slab with low water absorption and high temperature resistance, including the following steps: S1. Preparation of composite powder Weigh out 380g of bismuth trioxide, 50g of zinc oxide, 70g of boron oxide, 25g of silicon dioxide, and 10g of sodium oxide. Grind them through a 200-mesh sieve and place them in a crucible. Heat the crucible to 1200℃ at a heating rate of 5℃ / min and hold for 30min. Then pour the mixture into cold water for quenching. Remove the crucible and place it in a ball mill. Use deionized water as the dispersion medium and wet ball mill at 300r / min for 3h. After ball milling, place the crucible in a vacuum drying oven and dry it at 80℃ to constant weight. Remove the crucible and pass it through a 300-mesh sieve to obtain the composite powder.

[0040] S2, Preparation of modified corundum Weigh out 200g sodium chloride, 200g potassium chloride, 500g corundum powder and 100g zirconium powder, grind them in a mortar, pass through a 200-mesh sieve, place them in a quartz tube, and put them into a tube furnace under an argon atmosphere. Heat to 700℃ at a heating rate of 5℃ / min and hold for 80min, then heat to 1000℃ at a heating rate of 5℃ / min and hold for 90min. After the reaction is complete, cool the furnace to 500℃, remove the quartz tube, and cool to room temperature in air. Soak the product in deionized water at 80℃ for 120min, filter, and finally wash the product with deionized water until the washing solution is neutral. Place it in a vacuum drying oven and dry at 80℃ to constant weight to obtain modified corundum.

[0041] S3. Preparation of ceramic nanopowder Weigh out 100g of barium carbonate, 75g of strontium carbonate, and 270g of niobium pentoxide and add them to a ball mill. After ball milling for 6 hours with anhydrous ethanol as the dispersion medium, place the ball-milled slurry in a drying oven and dry it to constant weight at 60℃. Then transfer it to a high-temperature furnace and heat it at 1000℃ for 4 hours. After that, take it out and grind it, and pass it through a 200-mesh sieve. Then place the product in a high-temperature furnace and calcine it at 1400℃ for 6 hours. After sintering, cool it to room temperature with the furnace and grind the product again, and pass it through a 200-mesh sieve to obtain ceramic nanopowder.

[0042] S4. Preparation of reinforced powder Weigh out 270g of hafnium, 9g of molybdenum, 2.5g of boron, 8g of silicon monomer powder and 10g of borosilicate glass powder and add them to a ball mill. Use anhydrous ethanol as the dispersion medium and ball mill at 400 r / min for 5 hours. Remove the powder and place it in a vacuum drying oven. Dry it at 60℃ to constant weight. Place it in a cylindrical forming mold and press it into a green body under a pressure of 200MPa. Place the green body into the working chamber of a self-propagating high-temperature synthesis reaction device and ignite it with a molybdenum wire electrode under an argon atmosphere. After the reaction is completed, let the product cool naturally to room temperature. Then, ball mill it again through a 200-mesh sieve and put it into a graphite mold. Under a pressure of 25MPa and a vacuum, heat the product to 1400℃ at a heating rate of 100℃ / min and hold it for 5 minutes. Then, cool it to room temperature with the furnace to obtain the reinforced powder.

[0043] S5. Preparation of dry granular glaze Weigh out 180g of quartz, 120g of mullite, 300g of composite powder, 250g of modified corundum, 80g of ceramic nanopowder and 150g of reinforcing powder, add them to a ball mill and ball mill them, then pass them through a 300-mesh sieve to obtain a mixed powder. A2. 300g of expanded perlite was passed through a 40-mesh sieve. The sieved expanded perlite was added to a high-speed mixing granulator and stirred at 50r / min. At the same time, 500mL of 2wt% chitosan aqueous solution was sprayed into the mixture, and 1800g of mixed powder was added simultaneously. The mixture was stirred and granulated for 20min. After the granules were formed, they were removed and dried in an 80℃ oven for 3h. The dried granules were then passed through a 60-mesh sieve to obtain dry granule glaze.

[0044] S6. Preparation of low-water-absorption, high-temperature-resistant dry-grained rock slabs The dry granule glaze is evenly spread on the surface of the rock slab substrate to form a rock slab substrate with a 1mm dry granule glaze layer on the surface. Next, the rock slab substrate with dry granule glaze layer is first placed in a hot air circulating drying chamber and dried at 110°C for 40 minutes. Then, it is transferred to a roller kiln and fired at 1250°C for 80 minutes. After firing, it is cooled to room temperature with the roller kiln to obtain a dry granule rock slab with low water absorption and high temperature resistance.

[0045] Comparative Example 1: The difference between this comparative example and Example 3 is that step S1 is omitted and composite powder is not added in step S5.

[0046] Comparative Example 2: The difference between this comparative example and Example 3 is that step S2 is omitted, and the corundum micro powder in step S2 is used to replace the modified corundum in step S5.

[0047] Comparative Example 3: The difference between this comparative example and Example 3 is that step S3 is omitted, and niobium pentoxide in step S3 is used to replace the ceramic nanopowder in step S5.

[0048] Comparative Example 4: The difference between this comparative example and Example 3 is that step S4 is omitted and reinforcing powder is not added in step S5.

[0049] Performance testing: According to standard GB / T 3810.9-2016 "Test Methods for Ceramic Tiles - Part 9: Determination of Thermal Shock Resistance", the low water absorption and high temperature resistant dry granular rock slabs prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to thermal shock treatment. The water absorption (%) of the low water absorption and high temperature resistant dry granular rock slabs prepared in Examples 1-3 and Comparative Examples 1-4 was determined before and after thermal shock treatment, in accordance with the standard GB / T 44309-2024 "Ceramic Rock Slabs". According to standard GB / T 3810.9-2016 "Test Methods for Ceramic Tiles - Part 9: Determination of Thermal Shock Resistance", the low water absorption and high temperature resistant dry granular rock slabs prepared in Examples 1-3 and Comparative Examples 1-4 were tested before and after thermal shock treatment by dropping a 112g steel ball from a height of 750mm. The impact resistance of the dry granular rock slabs was reflected by whether they were damaged. The abrasion resistance grades of the low-water-absorption, high-temperature-resistant dry granulated rock slabs prepared in Examples 1-3 and Comparative Examples 1-4 were determined according to standard GB / T 3810.7-2016 "Test Methods for Ceramic Tiles - Part 7: Determination of Abrasion Resistance of Glazed Tiles Surfaces" before and after thermal shock treatment. These grades were used to reflect the abrasion resistance performance of the dry granulated rock slabs. Specific test results are shown in Table 1 below: Table 1 - Performance Test Data of Samples

[0050] Data Analysis: Comparative analysis of the data in Table 1 above shows that the low water absorption and high temperature resistant dry granular rock slab prepared by this invention has a water absorption rate of 0.037% before thermal shock, an abrasion resistance grade of AC5, and does not break after impact testing; the water absorption rate before thermal shock is 0.064%, the abrasion resistance grade is AC5, and it does not break after impact testing. Comparative Example 1 lacks a continuous glassy phase composed of boron oxide, silicon dioxide, bismuth trioxide, etc. During high-temperature sintering, the interparticle gaps cannot be fully filled, resulting in a significant decrease in density and an increase in water penetration channels. Its water absorption rate before thermal shock was 0.135%, and after thermal shock, the water absorption rate further increased to 0.202%, and the glaze density decreased significantly. At the same time, due to the lack of bonding and support from the glassy phase, the glaze hardness was insufficient and the wear resistance deteriorated. Before thermal shock, the wear resistance level was only AC2, and after thermal shock, it dropped to AC1. The structural stability deteriorated after thermal shock, and slight cracks appeared when subjected to impact. Comparative Example 2 uses unmodified ordinary corundum micro powder. The corundum surface and glaze phase interface have poor compatibility and weak bonding force, which easily leads to the formation of interfacial pores and microcracks, resulting in insufficient system density. Its water absorption rate before thermal shock is 0.122%, and the water absorption rate after thermal shock increases to 0.184%. Since it has not been modified by zirconium element, the corundum particles have insufficient thermal shock resistance. After thermal cycling, the glaze layer is prone to micro-defects. The wear resistance grade remains at AC2, with no improvement after thermal shock and a decrease in stability. Under the action of hot and cold cycles, stress concentration is easily generated in the weak interfacial bonding area, and slight cracks appear after impact. Comparative Example 3 uses niobium pentoxide to replace ceramic nanoparticles. The lack of fine particle filling and grain strengthening results in unreasonable particle size distribution and more residual pores, which leads to a higher water absorption rate of the rock slab. Its water absorption rate before thermal shock is 0.131%, which reaches 0.193% after thermal shock. The lack of ceramic nanoparticles causes the glaze grains to be unable to be refined, the grain boundary strength to be reduced, and the structural stability at high temperature to be insufficient. The wear resistance grade before thermal shock is AC3, which drops to AC2 after thermal shock. At the same time, the toughness and stress resistance of the glaze layer decrease, and microcracks are generated inside after thermal cycling. A small number of cracks appear when subjected to impact. Comparative Example 4, without the addition of reinforcing powder, lacks the composite support of high-melting-point ceramic phases such as hafnium diboride and molybdenum disilicide with borosilicate glass phases. The high-temperature skeleton strength of the glaze layer is insufficient and the toughness is low. Its water absorption rate before thermal shock is as high as 0.146%, which further increases to 0.237% after thermal shock. At the same time, the surface hardness and wear resistance are significantly reduced. The wear resistance level before thermal shock is only AC1, and it remains AC1 after thermal shock. Under the action of thermal shock, the glaze layer is prone to obvious internal stress and macro cracks. After being subjected to impact, obvious cracks or even damage occur.

[0051] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab, characterized in that, Includes the following steps: S1. After passing the expanded perlite through a 40-mesh sieve, add it to a high-speed mixing granulator and stir at a speed of 40-50 r / min. At the same time, spray the chitosan aqueous solution into it using a spray method and add the mixed powder simultaneously. Continue mixing and granulating under stirring conditions for 10-20 minutes. After the granules are formed, take them out and dry them in an 80℃ oven for 2-3 hours. Pass them through a 60-mesh sieve to obtain dry granule glaze. The mixed powder consists of quartz, mullite, composite powder, modified corundum, ceramic nanopowder and reinforcing powder. S2. Spread the dry granule glaze evenly on the surface of the rock slab substrate to form a rock slab substrate with a dry granule glaze layer. S3. The rock slab substrate with dry granule glaze layer is dried and fired to obtain a dry granule rock slab with low water absorption and high temperature resistance.

2. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 1, characterized in that, In step S1, the spreading thickness is 0.8-1mm; in step S2, the drying conditions of the rock slab substrate are: drying at 100-110℃ for 30-40min; the firing conditions of the dried rock slab substrate are: firing at 1100-1250℃ for 60-80min.

3. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 1, characterized in that, In step S1, the method for preparing the mixed powder is as follows: quartz, mullite, composite powder, modified corundum, ceramic nanopowder and reinforcing powder are added to a ball mill and ball-milled, and then passed through a 300-mesh sieve to obtain the mixed powder; the ratio of the amount of quartz, mullite, composite powder, modified corundum, ceramic nanopowder and reinforcing powder is 18g:12g:25-30g:20-25g:5-8g:10-15g.

4. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 1, characterized in that, The ratio of expanded perlite, chitosan aqueous solution, and mixed powder is 3g:4-5mL:17-18g, and the mass fraction of the chitosan aqueous solution is 2%.

5. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 4, characterized in that, The composite powder is prepared as follows: bismuth trioxide, zinc oxide, boron oxide, silicon dioxide, and sodium oxide are ground through a 200-mesh sieve, placed in a crucible, heated to 1100-1200℃ at a heating rate of 5℃ / min, held for 20-30 minutes, then quenched in cold water, removed, and added to a ball mill. Using deionized water as the dispersion medium, the mixture is wet-milled at 300 r / min for 2-3 hours. After milling, it is placed in a vacuum drying oven and dried at 80℃ to constant weight. The powder is then passed through a 300-mesh sieve to obtain the composite powder. The ratio of bismuth trioxide, zinc oxide, boron oxide, silicon dioxide, and sodium oxide is 3.6-3.8 g: 0.3-0.5 g: 0.5-0.7 g: 0.2-0.25 g: 0.1 g.

6. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 4, characterized in that, The modified corundum is prepared as follows: sodium chloride, potassium chloride, corundum powder, and zirconium powder are ground in a mortar, passed through a 200-mesh sieve, placed in a quartz tube, and sent into a tube furnace under an argon atmosphere. The temperature is increased to 700℃ at a heating rate of 5℃ / min and held for 60-80 min, then increased to 900-1000℃ at a heating rate of 5℃ / min and held for 60-90 min. After the reaction is completed, the furnace is cooled to 500℃, the quartz tube is removed, and the product is cooled to room temperature in air. The product is then soaked in deionized water at 60-80℃ for 100-120 min, filtered, and finally washed with deionized water until the washing liquid is neutral. The product is then placed in a vacuum drying oven and dried at 80℃ to constant weight to obtain modified corundum. The ratio of sodium chloride, potassium chloride, corundum powder, and zirconium powder is 1.7-2g:1.7-2g:5g:1g.

7. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 4, characterized in that, The method for preparing the ceramic nanopowder is as follows: barium carbonate, strontium carbonate, and niobium pentoxide are added to a ball mill and ball-milled for 5-6 hours with anhydrous ethanol as the dispersion medium. The ball-milled slurry is then placed in a drying oven and dried at 60°C to constant weight. Next, it is transferred to a high-temperature furnace and kept at 1000°C for 3-4 hours. After that, it is taken out, ground, and passed through a 200-mesh sieve. Then, the product is placed in a high-temperature furnace and calcined at 1300-1400°C for 5-6 hours. After sintering, it is cooled to room temperature with the furnace and ground again and passed through a 200-mesh sieve to obtain ceramic nanopowder.

8. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 7, characterized in that, The ratio of barium carbonate, strontium carbonate, and niobium pentoxide is 1g:0.75g:2.3-2.7g.

9. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 4, characterized in that, The preparation method of the reinforcing powder is as follows: Hafnium, molybdenum, boron, silicon monomer powders and borosilicate glass powder are added to a ball mill, and anhydrous ethanol is used as the dispersion medium. The mixture is ball-milled at 400 r / min for 4-5 h. The powder is then removed and placed in a vacuum drying oven and dried at 60℃ to constant weight. It is then placed in a cylindrical forming mold and pressed into a green body under a pressure of 200 MPa. The green body is then placed in the working chamber of a self-propagating high-temperature synthesis reaction device and ignited by passing a molybdenum wire electrode under an argon atmosphere. After the reaction is completed, the product is allowed to cool naturally to room temperature. It is then ball-milled again through a 200-mesh sieve and placed into a graphite mold. Under a pressure of 25 MPa and a vacuum, the temperature is raised to 1400℃ at a heating rate of 100℃ / min and held for 5 min. The mixture is then cooled to room temperature with the furnace to obtain the reinforcing powder.

10. The method for preparing a low-water-absorption, high-temperature-resistant dry-grained rock slab according to claim 9, characterized in that, The ratio of the monomer powders of hafnium, molybdenum, boron, and silicon to borosilicate glass powder is 24-27g:0.7-0.9g:0.25g:0.7-0.8g:1g.

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