An ultrathin rock plate, a preparation process and application thereof

Abstract

This invention discloses an ultrathin sintered stone slab, its preparation process, and its application, belonging to the field of building material manufacturing technology. The process includes: wet co-milling spodumene and zircon in an aqueous medium containing a cationic additive to obtain spodumene-zircon composite micropowder; mixing the spodumene-zircon composite micropowder into a bottom layer powder and a top layer powder, and adding a plastic binder to the bottom, core, and top layers; laying the bottom, core, and top layers powder to form an initial powder layer; sequentially subjecting the initial powder layer to low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration compaction, with buffering treatment applied to the edges of the powder layer during compaction; drying the green blank after pressure release and demolding, sintering it in a high-temperature range, and cooling it to obtain the finished product; eliminating the stress difference within the green blank, enabling the finished sintered stone slab to maintain high strength while possessing cold bending characteristics with a large radius of curvature at room temperature, thus solving the technical problems of brittle fracture, poor flatness, and insufficient weather resistance in ultrathin sintered stone slabs.

Description

Technical Field

[0001] This invention relates to the field of building material manufacturing technology, and in particular to an ultra-thin slab, its preparation process, and its application. Background Technology

[0002] With the increasing demands for lightweight finishing materials in modern architecture, ultra-thin sintered stone slabs have been widely used, but there are some technical defects in actual industrial production and outdoor service.

[0003] Conventional sintering slab formulation systems and molding processes in existing technologies often result in products with loose internal structures and poor weather resistance. External acid and alkali corrosive media and moisture can easily penetrate into the micropores, causing performance degradation. Under complex outdoor conditions, this leads to a decrease in freeze-thaw cycle strength and an increase in acid and alkali resistance quality loss rate.

[0004] Existing technologies that directly apply pressure during the molding process can cause stress concentration, resulting in low compaction density. The instantaneous pressing generates concentrated shear stress at the edge of the mold, creating a residual compressive stress difference between the edge and center of the sintered slab. During the depressurization and demolding stage, springback can easily cause microcracks at the edges and warping deformation of the slab. Existing ultra-thin sintered slabs often suffer from insufficient internal density and low overall bending resistance, microcrack initiation and reduced impact strength, weak mechanical interlocking effect between different particle levels, low demolding pass rate of ultra-thin sintered slabs, and poor final fracture strength of sintered products, making them unsuitable for complex load-bearing environments requiring flexible cold bending, such as curved building surfaces. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides an ultrathin rock slab, its preparation process, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a preparation process for ultrathin rock slabs, comprising the following steps: S1. Spodumene and zircon, in a mass ratio of 3:1, are placed in an aqueous solution containing a cationic additive and wet-milled to obtain spodumene-zircon composite micropowder. The spodumene-zircon composite micropowder is then mixed into the bottom layer powder and the top layer powder. The amount of spodumene-zircon composite micropowder added to the bottom layer powder and the top layer powder is 8% to 12% of the total mass of the bottom layer powder and the top layer powder, respectively. S2. A plastic binder is added to the bottom layer powder, the core layer powder, and the top layer powder respectively, and the bottom layer powder, the core layer powder, and the top layer powder are sequentially laid to form an initial powder layer; the plastic binder is a compound prepared by silica sol and organic binder in a mass ratio of 1:1, and the organic binder is an aqueous solution prepared by mixing polyvinyl alcohol and sodium carboxymethyl cellulose in a mass ratio of 2:1; S3. The initial powder layer is subjected to low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration compaction operations in sequence, while the edges of the initial powder layer are subjected to flexible buffer constraint treatment; the effective width of the flexible buffer constraint is 15-25mm, the buffer thickness is 3-5mm, and the Shore hardness of the constraint medium is A70-A85; wherein the mechanical vibration frequency of the high-frequency micro-vibration compaction matches the natural resonant frequency of the agglomerates of the spodumene-zircon composite micro powder. S4. After depressurization and demolding, an ultra-thin blank is obtained, and the ultra-thin blank is dried. S5. The dried ultrathin blank is placed in a high-temperature zone for sintering. After sintering, it is cooled to obtain an ultrathin slab.

[0007] In a preferred embodiment of the present invention, in S1, the cationic auxiliary is selected from soluble salts containing magnesium ions, aluminum ions or yttrium ions; The wet co-milling time is 2-4 hours, and the median particle size of the spodumene-zircon composite micro powder is 0.5-1.0 μm. The amount of spodumene-zircon composite micropowder added to the bottom layer powder and the top layer powder is 8% to 12% of the total mass of the bottom layer powder and the top layer powder.

[0008] In a preferred embodiment of the present invention, the amount of plastic binder added in S2 is as follows: the mass fraction of plastic binder in the core layer powder is 4% to 6%, and the mass fraction of plastic binder in the bottom layer powder and the top layer powder is 1.5% to 2.5%.

[0009] In a preferred embodiment of the present invention, the mass ratio of the bottom layer powder, the core layer powder, and the surface layer powder in S2 is 1:2:1; the median particle size of the core layer powder is 45-60 μm, and the median particle size of the bottom layer powder and the surface layer powder is 20-35 μm.

[0010] In a preferred embodiment of the present invention, in S3, the specific parameters for low-pressure exhaust are: applying a pressure of 5-10 MPa and maintaining it for 3-5 seconds; The specific parameters for the average stress during medium-pressure holding are: increasing the pressure to 20-30 MPa at a rate of 1-2 MPa / s and maintaining it for 8-12 seconds; The specific parameters for high-pressure superimposed high-frequency micro-vibration compaction are as follows: on a base pressure of 20-30 MPa, mechanical vibration with an amplitude of 0.1-0.3 mm and a frequency of 30-50 Hz is superimposed, while the pressure is increased to 40-55 MPa to complete the compaction.

[0011] In a preferred embodiment of the present invention, the drying temperature in S4 is 100-120°C and the drying time is 2-3 hours; the high-temperature sintering temperature range in S5 is 1150-1220°C and the sintering time is 60-90 minutes.

[0012] An ultrathin slab is prepared using the aforementioned process. The thickness of the ultrathin slab is 1–2.9 mm, and the porosity decreases gradually from the surface to the center. The absolute value of the residual compressive stress difference between the edge region and the center region of the slab in the same plane is less than 2 MPa. The ultrathin slab has cold bending characteristics at room temperature, and the minimum cold bending radius ranges from 1200 mm to 1500 mm.

[0013] An application of ultra-thin sintered stone slabs involves attaching the ultra-thin sintered stone slabs as building facade materials to curved building facades, curved interior decorations, or cylindrical surfaces, utilizing the cold bending characteristics of the ultra-thin sintered stone slabs to achieve seamless overall coverage.

[0014] This invention addresses the shortcomings of the prior art and has the following beneficial effects: This invention incorporates spodumene-zircon composite micropowder containing cationic additives into the bottom and top layer powders. It combines this with a three-stage pressurization and high-frequency micro-vibration compaction process, followed by edge buffering, after the initial powder layers (bottom, core, and top layers) are formed. This induces the formation of a microcrystalline network structure in the composite micropowder during sintering, sealing surface micropores. Simultaneously, multi-level pressure and specific frequency matching achieve macroscopic stress equilibrium and micro-particle rearrangement in the green blank. Compared to conventional forming processes that suffer from loose internal structures and stress concentration, this technology significantly improves the density and weather resistance of the sintered stone, eliminates the risk of edge micro-cracks caused by demolding springback, and thus endows the ultra-thin sintered stone with cold bending characteristics at room temperature.

[0015] This invention incorporates spodumene-zircon composite micropowder, obtained by wet co-milling in an aqueous medium containing cationic additives, into the bottom and top layer powders, and gradually adds a plastic binder composed of silica sol and organic binder to each powder layer. The cationic additives promote the formation of an amorphous transition layer in the composite micropowder and improve the interfacial bonding force. During the high-temperature sintering stage, the composite micropowder directionally induces the formation of a continuous microcrystalline network structure to seal the micropores on the surface of the rock slab. The high-temperature inorganic binder phase of silica sol and the gradient distribution synergistically ensure the sintering density of the core powder, bottom powder, and top layer powder; block the penetration paths of acid and alkali corrosive media and moisture; effectively improve the transcrystalline fracture ratio and freeze-thaw cycle strength retention rate of the finished product, thereby extending the service life of the ultrathin rock slab in complex outdoor working conditions.

[0016] This invention employs a series of operations: low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration compaction on the initial powder layer. Throughout the compaction process, flexible buffering constraints are applied to the edges of the initial powder layer. During the low-pressure and medium-pressure stages, residual air within the powder layer is gradually expelled, achieving initial stress equalization. During the high-pressure stage, high-frequency micro-vibration, with a frequency matching the natural resonant frequency of the spodumene-zircon composite micro-powder agglomerates, promotes particle resonance rearrangement and tight packing. This, combined with the edge flexible buffering constraint mechanism, absorbs and disperses the shear stress concentrated at the mold edge. Compared to the limitations of conventional processes where direct, one-time pressurization easily leads to stress concentration and edge warping due to instantaneous rebound upon demolding, this invention significantly reduces the residual compressive stress difference between the edge and center regions of the slab within the same plane. This effectively improves the demolding pass rate of ultra-thin blanks and the overall flatness of the finished product, ensuring that the prepared slab material meets the structural bending construction requirements for seamless bonding of curved building facades.

[0017] This invention constructs a gradient hierarchical structure in which the median particle size of the core layer powder is larger than that of the median particle size of the bottom and surface layer powders. This is superimposed with a dense surface layer formed by surface-active spodumene-zircon composite micropowder, and further enhanced by a high-frequency micro-vibration compaction molding process with deep resonance matching. The gradient particle size distribution guides the porosity to decrease gradually from the surface to the center. The mechanical interlocking effect of coarse and fine particles is amplified under the micro-vibration compaction at a specific frequency. While the fine particles in the surface layer fill the gaps between the coarse particles inside, the microcrystalline network locks the interfaces of each powder layer. Compared to conventional preparation methods that use uniform particle size and lack interlayer dynamic compaction synergy, which suffer from low fracture strength and are prone to intergranular brittle fracture, this material's synergistic structure and mechanical process release the severe shrinkage stress generated during the high-temperature sintering of ultra-thin blanks. This endows the ultra-thin slab with high fracture modulus and structural toughness, solving the technical problem of brittle fracture that easily occurs in similar ultra-thin ceramic slab products in outdoor decorative applications. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0021] like Figure 1 As shown in the figure, the preparation process of an ultrathin rock slab provided by an embodiment of the present invention includes the following steps: S1. Spodumene and zircon, in a mass ratio of 3:1, are placed in an aqueous solution containing a cationic additive and wet-milled to obtain spodumene-zircon composite micropowder. The spodumene-zircon composite micropowder is then mixed into the bottom layer powder and the top layer powder. The amount of spodumene-zircon composite micropowder added to the bottom layer powder and the top layer powder is 8% to 12% of the total mass of the bottom layer powder and the top layer powder, respectively. S2. A plastic binder is added to the bottom layer powder, the core layer powder, and the top layer powder respectively, and the bottom layer powder, the core layer powder, and the top layer powder are sequentially laid to form an initial powder layer; the plastic binder is a compound prepared by silica sol and organic binder in a mass ratio of 1:1, and the organic binder is an aqueous solution prepared by mixing polyvinyl alcohol and sodium carboxymethyl cellulose in a mass ratio of 2:1; S3. The initial powder layer is subjected to low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration compaction operations in sequence, while the edges of the initial powder layer are subjected to flexible buffer constraint treatment; the effective width of the flexible buffer constraint is 15-25mm, the buffer thickness is 3-5mm, and the Shore hardness of the constraint medium is A70-A85; wherein the mechanical vibration frequency of the high-frequency micro-vibration compaction matches the natural resonant frequency of the agglomerates of the spodumene-zircon composite micro powder. S4. After depressurization and demolding, an ultra-thin blank is obtained, and the ultra-thin blank is dried. S5. The dried ultrathin blank is placed in a high-temperature zone for sintering. After sintering, it is cooled to obtain an ultrathin slab.

[0022] This invention relies on spodumene-zircon composite micropowder obtained by wet co-milling in an aqueous medium containing cationic additives. Combined with the distribution of a plastic binder, a three-stage compaction process—low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration—is employed. High-frequency mechanical vibration, matching the natural resonant frequency of the composite micropowder agglomerates, induces powder resonance to achieve microparticle rearrangement and forced penetration filling. Simultaneously, buffering treatment is applied to the edges of the initial powder layer to absorb and disperse concentrated shear stress at the mold edges. This technical solution addresses both material composition and compaction process, eliminating internal stress defects such as edge micro-cracks and plate warping caused by demolding springback during the molding stage. Furthermore, during the high-temperature sintering stage, it directionally induces the formation of a continuous microcrystalline network structure to seal surface micropores. This solves the technical problems of loose structure and low density in existing ultra-thin rock slabs, endowing the molded product with excellent room-temperature cold bending characteristics and fracture strength.

[0023] In step S1, spodumene and zircon are wet-milled in an aqueous medium containing a cationic additive to obtain spodumene-zircon composite micropowder. The spodumene-zircon composite micropowder is then mixed into the bottom layer powder and the top layer powder. During the wet-milling process, the cationic additive promotes the pre-reaction of lithium ions with the zircon surface to form an amorphous transition layer on the surface of the powder particles to enhance the interfacial bonding force. This lays the material science foundation for the construction of the microcrystalline network structure in the subsequent sintering stage.

[0024] In step S2, plastic binders are added to the bottom layer powder, core layer powder, and top layer powder respectively, and the bottom layer powder, core layer powder, and top layer powder are sequentially laid to form an initial powder layer. By distributing plastic binders evenly in the three different powder structures, the thixotropic fluidization ability of the bottom layer powder, core layer powder, and top layer powder is ensured in the subsequent compaction process, and an initial material skeleton with a stable hierarchical structure is established in the mold cavity.

[0025] In step S3, the initial powder layer is subjected to low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration compaction operations in sequence. At the same time, the edges of the initial powder layer are buffered. The key parameters are: the mechanical vibration frequency of the high-frequency micro-vibration compaction must match the natural resonant frequency of the agglomerates of the spodumene-zircon composite micro powder; the three-stage stepped pressurization combined with edge buffering constraints effectively changes the stress transmission path, eliminates excess air and equalizes internal stress to prevent damage from concentrated shear stress at the edges; the resonance effect of precise frequency matching forcibly breaks the original static self-locking state of the fine powder particles, driving the fine particles and binder to deeply penetrate and fill the pores of the core powder, promoting high density of the internal structure and converging the residual stress difference.

[0026] The specific parameters for high-pressure superimposed high-frequency micro-vibration compaction are as follows: on a base pressure of 20-30 MPa, mechanical vibration with an amplitude of 0.1-0.3 mm and a frequency of 30-50 Hz is superimposed. The mechanical vibration is applied vertically downwards by the upper pressure head of the press. The mechanical vibration wave penetrates the upper mold and is transmitted to the initial powder layer in the mold cavity. Throughout the pressing process, the lower pressure head of the press is kept in a fixed rigid support state. In this way, a high-frequency dynamic compressive stress field is established in the mold cavity, which is transmitted unidirectionally from the surface powder to the bottom powder. While applying mechanical vibration, the pressure is increased to 40-55 MPa to complete the final compaction operation. The unidirectional mechanical vibration combined with edge buffer constraints can effectively guide the exhaust direction of the forced powder and prevent the internal stress wave interference and divergence caused by bidirectional vibration.

[0027] The micro-dense structure with a gradient decrease in porosity is not formed naturally by the initial particle size distribution of the bottom layer powder, core layer powder, and surface layer powder. Its essential mechanism lies in the deep physical coupling of the three-stage pressurization process with a specific resonant frequency. In the low-pressure exhaust and medium-pressure holding stress equalization stages, the powder particles undergo initial relative slippage and rearrangement, and the plastic binder initially forms a lubricating film on the particle surface. When entering the high-pressure superimposed high-frequency micro-vibration compaction stage, the applied mechanical vibration frequency is precisely matched with the natural resonant frequency of the spodumene-zircon composite micro powder agglomerates, triggering a resonance effect inside the powder system. This resonance energy instantly breaks the original static frictional self-locking state of the fine particles in the surface layer powder and the bottom layer powder, causing the plastic binder to produce thixotropic fluidization.

[0028] Under vertically downward high-pressure steady-state drive, fine particles in a fluidized state and spodumene-zircon composite micro powder undergo forced migration along with the liquid phase of the plastic binder, directionally penetrating and deeply filling the macroscopic pore network constructed by large particles in the core powder. As the compaction depth increases, the attenuation of vibration energy inside the powder causes the fluid migration resistance of fine particles to gradually increase, resulting in a regular decrease in the amount of penetration and filling along the thickness direction. After sintering and solidification in a high-temperature range, the ultrathin rock slab is finally solidified, forming a strict and continuous gradient distribution of porosity from the surface to the center.

[0029] In step S4, after depressurization and demolding, an ultra-thin blank is obtained and the ultra-thin blank is dried. After completing the internal skeleton reshaping and macro-stress balancing, the pressure is slowly depressurized to obtain a flat ultra-thin blank and remove free water inside the blank, thus cutting off the physical path of the blank cracking caused by rapid vaporization of water under high temperature conditions.

[0030] In step S5, the dried ultrathin blank is placed in a high-temperature zone for sintering. After sintering, it is cooled to obtain an ultrathin rock slab. The blank undergoes densification shrinkage in the high-temperature thermal field. The pre-distributed spodumene-zircon composite micro powder induces and completes the cross-linking of the microcrystalline network, and finally solidifies to form a high-strength decorative building material with porosity hierarchical distribution characteristics.

[0031] The raw materials used in the embodiments and comparative examples of this invention are all commercially available industrial-grade products, and the specific information is as follows: Lithium spodumene concentrate, specifications are Content ≥6.0%, Content ≥25.0%, Content ≤0.5%, purchased from Sichuan Tianqi Lithium Industry Co., Ltd.

[0032] Zircon powder, specifications are Content ≥65.0%, Content ≤33.0%, Content ≤0.1%, purchased from Guangdong Oriental Zirconium Industry Technology Co., Ltd.

[0033] Silica sol, alkaline specification. 30% by mass, particle size 10-20 nm, pH value 9.0-10.0, purchased from Shandong Baite New Materials Co., Ltd., model BT-30.

[0034] Polyvinyl alcohol, with a degree of alcoholysis of 88% and a degree of polymerization of 1700, was purchased from the Beijing Yanshan Branch of China Petroleum & Chemical Corporation, model number 1788.

[0035] Sodium carboxymethyl cellulose, with a degree of substitution of 0.6–0.8 and a viscosity of 300–800 ppm. Purchased from Shandong Heda Co., Ltd., model FH6.

[0036] The flexible buffer restraint medium is made of silicone rubber with a Shore hardness of A70 to A85, and was purchased from Dongguan Huaqi Sealing Parts Co., Ltd.

[0037] The basic raw materials for ceramics include kaolin, quartz, and potassium feldspar, which are industrial grade and conform to the GB / T14563-2008 standard. They are purchased from Foshan Ceramic Raw Material Factory.

[0038] The specific process of making the materials is as follows: Preparation steps of spodumene-zircon composite micro powder: Industrial-grade magnesium chloride was weighed and added to water to prepare a magnesium ion-containing aqueous solution with a mass concentration of 0.8%. Spodumene concentrate and zircon concentrate were accurately weighed at a mass ratio of 3:1 and added to the magnesium ion-containing aqueous solution until the solid content of the slurry was 60%. The ball-to-powder mass ratio was controlled at 8:1. The mixture was then sand-milled at a speed of 1500 r / min for 3.5 h using a wet co-milling method. This process is beneficial for improving interfacial activity, interfacial bonding, and densification in the subsequent sintering stage. The particle size of the slurry was measured, and grinding was stopped when the median particle size reached 0.75 μm. The slurry was then granulated by passing it through a pressure spray drying tower, sieved through a 200-mesh sieve, and sealed for later use. This yielded surface-active spodumene-zircon composite micro powder.

[0039] Using the raw materials and proportions of the above preparation method, the wet co-milling time is shortened to 1 hour, and spodumene-zircon composite micro powder is obtained.

[0040] Weigh industrial-grade aluminum chloride and add it to water to prepare an aluminum ion-containing aqueous solution with a mass concentration of 0.6%. Accurately weigh spodumene concentrate and zircon concentrate at a mass ratio of 3:1 and add them to the aluminum ion-containing aqueous solution until the solid content of the slurry is 60%. Control the ball-to-particle mass ratio to be 8:1 and perform sand milling at a speed of 1500 r / min for 2 hours. Stop grinding when the median particle size of the slurry reaches 0.8 μm. After spray drying and sieving, spodumene-zircon composite micro powder with a median particle size of 0.8 μm is obtained.

[0041] Industrial-grade yttrium chloride was weighed and added to water to prepare a yttrium ion-containing aqueous solution with a mass concentration of 0.8%. Spodumene concentrate and zircon concentrate were accurately weighed at a mass ratio of 3:1 and added to the yttrium ion-containing aqueous solution until the solid content of the slurry was 60%. The ball-to-particle mass ratio was controlled at 8:1. The mixture was then sand-milled at a speed of 1500 r / min for 4 hours. The milling was stopped when the median particle size of the slurry reached 0.8 μm. The slurry was then spray-dried and sieved to obtain the final product.

[0042] Preparation steps of compound plastic binder: Weigh polyvinyl alcohol and sodium carboxymethyl cellulose accurately at a mass ratio of 2:1, add them to water, and stir in an 80°C water bath until completely dissolved to prepare an organic binder aqueous solution with a mass fraction of 10%. Mix silica sol with the above organic binder aqueous solution at a mass ratio of 1:1, stir at room temperature for 30 minutes until homogeneous, and seal for later use.

[0043] Using the raw materials and processes described above, the mass ratio of silica sol to organic binder aqueous solution was adjusted to 1:3. The mixture was stirred at room temperature for 30 minutes until homogeneous, and then sealed for later use to obtain the compounded plastic binder.

[0044] Both the bottom layer powder and the top layer powder are made of the same material, and the preparation parameters and processes are identical. The specific preparation steps are as follows: Accurately weigh 45 parts of kaolin, 30 parts of quartz, and 25 parts of potassium feldspar according to the mass ratio, add them to a ball mill and ball mill until the median particle size is 27 μm. Pass the mixture through an 80-mesh sieve to obtain basic ceramic powder. Add 10% of the above-mentioned spodumene-zircon composite micro powder and 2.0% of the above-mentioned compound plastic binder to the basic ceramic powder. Stir evenly, pass the mixture through an 80-mesh sieve, and seal for later use.

[0045] Using the raw materials and processes described above, the dosage of the composite micro powder was adjusted to 8% to obtain the bottom layer powder and the top layer powder.

[0046] Using the raw materials and processes described above, the content of the composite micro powder was adjusted to 12% to obtain the bottom layer powder and the top layer powder.

[0047] Using the raw materials and processes described above, the amount of compound plastic binder added was adjusted to 1.5% to obtain the bottom layer powder and the top layer powder.

[0048] Using the raw materials and processes described above, the amount of compound plastic binder added was adjusted to 2.5% to obtain the bottom layer powder and the top layer powder.

[0049] Using the raw materials and processes described above, the powders were ball-milled in a ball mill until the median particle size was 20 μm, thus obtaining the bottom layer powder and the top layer powder.

[0050] Using the raw materials and processes described above, the powder is ball-milled in a ball mill until the median particle size is 35 μm to obtain bottom layer powder and top layer powder.

[0051] Core layer powder preparation steps: Accurately weigh 40 parts of kaolin, 35 parts of quartz, and 25 parts of potassium feldspar according to the mass ratio, add them to a ball mill and ball mill until the median particle size is 52 μm. Pass the mixture through an 80-mesh sieve to obtain basic ceramic powder. Add 5.0% of the above-mentioned compound plastic binder by mass to the basic ceramic powder, stir evenly, pass the mixture through an 80-mesh sieve, and seal for later use.

[0052] Using the raw materials and processes described above, the amount of compound plastic binder added was adjusted to 4% to obtain core layer powder.

[0053] Using the raw materials and processes described above, the amount of compound plastic binder added was adjusted to 6% to obtain core layer powder.

[0054] Using the raw materials and processes described above, the powder was ball-milled in a ball mill until the median particle size was 45 μm, thus obtaining the core layer powder.

[0055] Using the raw materials and processes described above, the powder was ball-milled in a ball mill until the median particle size was 60 μm to obtain the core layer powder.

[0056] All performance indicators were tested using current national standards and industry-standard methods, as detailed below: The percentage of 100 unfinished blanks without cracks or missing corners was counted to test the unfinished blank demolding qualification rate.

[0057] The fracture strength of the slab was tested using GB / T3810.4-2016 "Test Methods for Ceramic Tiles - Part 4: Determination of Modulus of Fracture and Breaking Strength".

[0058] The flatness of the slab was tested using GB / T3810.2-2016 "Test Methods for Ceramic Tiles - Part 2: Inspection of Dimensions and Surface Quality".

[0059] The core density was tested according to GB / T 3810.3-2016 "Test Methods for Ceramic Tiles - Part 3: Determination of Water Absorption, Apparent Porosity, Apparent Relative Density and Bulk Density".

[0060] GB / T3810.12-2016 "Test Methods for Ceramic Tiles - Part 12: Determination of Freeze-Thaw Resistance" was used to test the strength retention rate during freeze-thaw cycles.

[0061] The UV aging color difference was tested using GB / T16259-2008 "Test Method for Accelerated Aging of Building Materials under Artificial Climate".

[0062] The acid and alkali resistance mass loss rate was tested using GB / T3810.13-2016 "Test Methods for Ceramic Tiles - Part 13: Determination of Chemical Resistance".

[0063] The single-sided precracked beam (SEPB) method of GB / T23806-2025 "Test Method for Fracture Toughness of Fine Ceramics" was adopted, and the proportion of transgranular fracture area was statistically analyzed by randomly selecting 5 non-overlapping fields of view.

[0064] The minimum cold bending radius was determined using GB / T3810.20-2025 "Test Methods for Ceramic Tiles - Part 20: Determination of Deflection in Calculation of Radius of Curvature of Ceramic Tiles".

[0065] Using GB / T7704-2017 "Nondestructive Testing - X-ray Stress Measurement Method", surface stress was scanned at 10 mm inside the edge of the rock slab sample and at the geometric center of the sample as test target areas, and the absolute difference between the residual compressive stress at the two locations was calculated.

[0066] Example 1: Industrial-grade magnesium chloride was weighed and added to water to prepare a magnesium chloride solution with a mass concentration of 0.8%. 45 parts of kaolin, 30 parts of quartz, and 25 parts of potassium feldspar were accurately weighed according to the mass ratio and added to a ball mill to be ball-milled until the median particle size was 27 μm. The mixture was then passed through an 80-mesh sieve to obtain the base ceramic powder for the bottom and top layers. 40 parts of kaolin, 35 parts of quartz, and 25 parts of potassium feldspar were accurately weighed according to the mass ratio and added to a ball mill to be ball-milled until the median particle size was 52 μm. The mixture was then passed through an 80-mesh sieve to obtain the base ceramic powder for the core layer.

[0067] Accurately weigh spodumene concentrate and zircon concentrate at a mass ratio of 3:1, add the above-mentioned magnesium chloride solution medium, control the ball-to-material mass ratio at 8:1, adjust the slurry solid content to 60%, and perform sand milling at a speed of 1500 r / min for 3.5 h of wet co-milling. Stop grinding when the median particle size reaches 0.75 μm. Granulate the slurry through a pressure spray drying tower, pass it through a 200-mesh sieve, and seal it for later use to obtain surface-active spodumene-zircon composite micro powder.

[0068] Polyvinyl alcohol and sodium carboxymethyl cellulose were accurately weighed at a mass ratio of 2:1, added to water, and stirred in an 80°C water bath until completely dissolved to prepare an organic binder aqueous solution with a mass fraction of 10%. Silica sol was mixed with the above organic binder aqueous solution at a mass ratio of 1:1 and stirred at room temperature for 30 minutes until homogeneous to obtain a compound plastic binder.

[0069] Add 10% of the total mass of spodumene-zircon composite micro powder to the base ceramic powders for the bottom and top layers respectively, and then add 2.0% of the total mass of the compound plastic binder to each. Stir evenly and pass through an 80-mesh sieve to obtain the bottom layer powder and top layer powder respectively. Add 5.0% of the total mass of the compound plastic binder to the base ceramic powders for the core layer respectively, stir evenly and pass through an 80-mesh sieve to obtain the core layer powder.

[0070] An automatic material feeding machine is used to evenly lay the processed bottom layer powder, core layer powder, and top layer powder sequentially to form the initial powder layer, with a mass ratio of 1:2:1. Low-pressure venting is used, applying a pressure of 7.5 MPa and maintaining it for 4 seconds to expel air between the powder particles. Medium-pressure stress equalization is then applied, increasing the pressure to 25 MPa at a rate of 1.5 MPa / s and maintaining it for 10 seconds to ensure uniform stress distribution within the powder layer. Using an acoustic sweep frequency meter, while the initial powder layer is under 25 MPa pressure, a continuous sinusoidal sweep frequency sound signal with a frequency band of 10Hz–100Hz and a sweep rate of 1Hz / s is applied downwards through a piezoelectric exciter built into the press head. Simultaneously, a broadband acoustic vibration pickup sensor located on the mold sidewall collects the response signal of the transmitted sound wave, extracting the amplitude... The frequency corresponding to the peak amplitude in the frequency response curve was taken as the resonant point. Acoustic modal analysis was performed on the agglomerates formed by the submicron-sized spodumene-zircon composite powder in the initial powder layer, and its natural resonant frequency was determined to be 42Hz. Subsequently, a mechanical vibration with an amplitude of 0.2mm and a frequency of 42Hz was superimposed on a base pressure of 25MPa to match the applied vibration frequency with the natural resonant frequency of the agglomerates. At the same time, the pressure was increased to 47.5MPa and maintained for 8s to complete the final compaction. Throughout the compaction process, a flexible buffer constraint medium with a width of 20mm, a thickness of 4mm, and a Shore hardness of A75 was applied to the edge of the initial powder layer.

[0071] After depressurization and demolding, an ultrathin blank was obtained and dried at 110℃ for 2.5h until the moisture content of the blank was less than 0.5%. The dried ultrathin blank was then sintered at 1200℃ for 75min. After sintering, it was naturally cooled to room temperature to obtain an ultrathin rock slab with a thickness of 2.0mm.

[0072] Example 2: The dosage of spodumene-zircon composite micro powder was adjusted to 8% of the total mass of the bottom and top layer powders, and the remaining processes and parameters were the same as in Example 1.

[0073] Example 3: The dosage of spodumene-zircon composite micro powder was adjusted to 12% of the total mass of the bottom and top layer powders, and the remaining processes and parameters were the same as in Example 1.

[0074] Example 4: The amount of compound plastic binder added is 4% of the total mass of the core layer powder and 1.5% of the total mass of the bottom layer powder and the top layer powder. The remaining processes and parameters are the same as in Example 1.

[0075] Example 5: The amount of compound plastic binder added is 6% of the total mass of the core layer powder and 2.5% of the total mass of the bottom layer powder and the top layer powder. The remaining processes and parameters are the same as in Example 1.

[0076] Example 6: The median particle size of the core layer powder is controlled to be 45 μm, and the median particle size of the bottom layer powder and the top layer powder is 20 μm. The mass ratio of the three layers of powder is still 1:2:1, and the rest of the process and parameters are the same as in Example 1.

[0077] Example 7: The median particle size of the core layer powder is controlled to be 60 μm, and the median particle size of the bottom layer powder and the top layer powder is 35 μm. The mass ratio of the three layers of powder is still 1:2:1, and the rest of the process and parameters are the same as in Example 1.

[0078] Example 8: The compaction parameters were adjusted as follows: low pressure exhaust 5MPa for 3s, medium pressure holding 20MPa for 8s, high pressure superimposed with mechanical vibration of 0.1mm amplitude and 30Hz frequency and increased to 40MPa. The remaining processes and parameters were the same as in Example 1.

[0079] Example 9: The compaction parameters were adjusted as follows: low pressure exhaust 10MPa maintained for 5s, medium pressure holding 30MPa maintained for 12s, high pressure superimposed with mechanical vibration of 0.3mm amplitude and 50Hz frequency and increased to 55MPa, and the rest of the process and parameters were the same as in Example 1.

[0080] Example 10: The edge flexible buffer constraint parameters are adjusted to: effective width 15mm, buffer thickness 3mm, constraint medium Shore hardness A70, and the rest of the process and parameters are the same as in Example 1.

[0081] Example 11: The edge flexible buffer constraint parameters are adjusted to: effective width 25mm, buffer thickness 5mm, constraint medium Shore hardness A85, and the rest of the process and parameters are the same as in Example 1.

[0082] Example 12: The 0.8% magnesium chloride aqueous solution was replaced with a 0.6% aluminum chloride aqueous solution, the wet co-milling time was adjusted to 2 hours, and the slurry particle size was measured. The median particle size of the resulting spodumene-zircon composite micro powder was 0.8 μm. The natural resonant frequency of the agglomerate was measured to be 38 Hz during the compaction stage. Accordingly, the mechanical vibration frequency of the high-frequency micro-vibration was adjusted to 38 Hz for precise matching. The remaining processes and parameters were the same as in Example 1.

[0083] Example 13: The 0.8% magnesium chloride aqueous solution medium was replaced with a 0.8% yttrium chloride aqueous solution medium, and the wet co-milling time was adjusted to 4 hours. The particle size of the slurry was measured, and the median particle size of the resulting spodumene-zircon composite micro powder was 0.8 μm. During the compaction stage, the natural resonant frequency of the micro powder agglomerates was measured to be 45 Hz using an acoustic sweep frequency meter. Accordingly, the mechanical vibration frequency of the high-frequency micro-vibration was adjusted to 45 Hz for precise matching. The remaining processes and parameters were the same as in Example 1.

[0084] Comparative Example 1: The amount of spodumene-zircon composite micro powder was 5% of the total mass of the bottom and top layer powders, and the remaining processes and parameters were the same as in Example 1.

[0085] Comparative Example 2: The amount of spodumene-zircon composite micro powder was 15% of the total mass of the bottom and top layer powders, and the remaining processes and parameters were the same as in Example 1.

[0086] Comparative Example 3: The mass ratio of spodumene to zircon was 1:1, the amount of composite micro powder was still 10%, and the rest of the process and parameters were the same as in Example 1.

[0087] Comparative Example 4: The mass ratio of spodumene to zircon was 5:1, the amount of composite micro powder was still 10%, and the remaining processes and parameters were the same as in Example 1.

[0088] Comparative Example 5: No spodumene-zircon composite micro powder was added to the bottom and top layer powders, and the rest of the process and parameters were the same as in Example 1.

[0089] Comparative Example 6: Polyvinyl alcohol was used as the plastic binder, and the amount of binder added to the bottom layer, top layer and core layer powder was 3%. The rest of the process and parameters were the same as in Example 1.

[0090] Comparative Example 7: The mass ratio of silica sol to organic binder in the compounded plastic binder is 1:3, and the remaining processes and parameters are the same as in Example 1.

[0091] Comparative Example 8: A single-layer powder structure was used, without distinguishing between the bottom layer, core layer, and surface layer. The median particle size of the powder was 40 μm. The remaining processes and parameters were the same as in Example 1.

[0092] Comparative Example 9: A one-time pressurization process was used, directly applying a pressure of 47.5 MPa and holding it for 17 seconds. The remaining processes and parameters were the same as in Example 1.

[0093] Comparative Example 10: The high-frequency micro-vibration step was omitted, and only a pressure of 47.5 MPa was applied and held for 10 seconds. The rest of the process and parameters were the same as in Example 1.

[0094] Comparative Example 11: No edge flexible buffer constraints are applied, and the rest of the process and parameters are the same as in Example 1.

[0095] Comparative Example 12: The width of the edge flexible buffer constraint is 10mm, and the rest of the process and parameters are the same as in Example 1.

[0096] Comparative Example 13: The width of the edge flexible buffer constraint is 30mm, and the rest of the process and parameters are the same as in Example 1.

[0097] Comparative Example 14: The thickness of the edge flexible buffer constraint is 2mm, and the rest of the process and parameters are the same as in Example 1.

[0098] Comparative Example 15: The thickness of the edge flexible buffer constraint is 6mm, and the rest of the process and parameters are the same as in Example 1.

[0099] Comparative Example 16: The wet co-grinding medium was replaced with water containing no cationic additives, and co-grinding was performed for 3.5 hours. The remaining processes and parameters were the same as in Example 1.

[0100] Comparative Example 17: The wet co-milling time was shortened to 1 hour, while the remaining processes and parameters were the same as in Example 1.

[0101] Comparative Example 18: During the high-pressure superimposed high-frequency micro-vibration compaction stage, the natural resonant frequency of the composite micro powder agglomerate was measured to be 42Hz by acoustic frequency sweep. However, mechanical vibration with a fixed frequency of 20Hz was artificially applied. The remaining processes and parameters were the same as in Example 1.

[0102] Comparative Example 19: During the high-pressure superimposed high-frequency micro-vibration compaction stage, the natural resonant frequency of the composite micro powder agglomerate was measured to be 42Hz by acoustic frequency sweep. However, mechanical vibration with a fixed frequency of 60Hz was artificially applied. The remaining processes and parameters were the same as in Example 1.

[0103] The experimental data are shown in the table below: serial number Raw blank demolding pass rate (%) Core density (%) Freeze-thaw strength retention rate (%) UV aging ΔE Acid and alkali resistance mass loss rate (%) Transgranular fracture rate (%) Minimum cold bending radius R (mm) Example 1 98.7 94.3 95.7 0.8 0.07 91.5 1280 Example 2 97.2 93.8 92.3 1.2 0.12 89.2 1380 Example 3 96.5 93.5 94.1 0.9 0.09 90.1 1320 Example 4 97.5 94.0 93.5 1.0 0.10 89.5 1350 Example 5 98.0 93.9 94.2 0.9 0.08 88.8 1360 Example 6 97.8 94.1 94.5 0.8 0.08 90.2 1310 Example 7 97.1 93.6 93.8 1.1 0.11 89.0 1390 Example 8 96.8 93.5 93.2 1.1 0.10 88.5 1420 Example 9 97.5 94.1 94.6 0.9 0.08 89.7 1300 Example 10 96.5 93.8 93.5 1.0 0.09 89.1 1410 Example 11 97.0 94.2 94.8 0.8 0.08 90.5 1330 Example 12 98.9 96.1 95.2 0.9 0.08 88.3 1350 Example 13 99.5 96.5 96.1 0.7 0.06 90.7 1310 Comparative Example 1 95.8 93.2 78.5 2.7 0.35 55.2 fracture Comparative Example 2 82.3 90.7 86.2 1.0 0.10 78.5 fracture Comparative Example 3 96.9 93.6 89.4 1.5 0.18 65.4 fracture Comparative Example 4 96.3 93.1 87.1 1.3 0.21 68.2 fracture Comparative Example 5 96.1 93.0 67.2 4.2 0.58 15.6 fracture Comparative Example 6 72.3 89.5 75.6 3.1 0.42 62.1 fracture Comparative Example 7 85.6 91.8 82.3 2.2 0.27 68.5 fracture Comparative Example 8 85.7 85.7 72.1 3.5 0.47 45.2 fracture Comparative Example 9 78.5 85.7 70.3 3.8 0.51 42.8 fracture Comparative Example 10 82.1 87.6 74.5 3.4 0.45 50.3 fracture Comparative Example 11 71.5 93.7 73.8 3.6 0.49 82.1 fracture Comparative Example 12 91.3 94.0 92.5 0.9 0.08 85.2 fracture Comparative Example 13 95.7 94.1 94.3 0.8 0.07 86.5 fracture Comparative Example 14 88.6 93.9 91.7 0.9 0.08 83.4 fracture Comparative Example 15 94.9 94.0 93.8 0.8 0.07 85.8 fracture Comparative Example 16 95.5 94.1 75.2 2.8 0.38 35.2 fracture Comparative Example 17 96.2 94.4 82.5 2.1 0.25 48.6 fracture Comparative Example 18 88.4 91.2 85.6 1.8 0.19 87.5 fracture Comparative Example 19 84.1 89.5 81.2 2.3 0.28 85.2 fracture The performance test data are shown in the table below: serial number Raw blank demolding pass rate (%) Slab flatness (mm / m) Slab fracture strength (MPa) Absolute value of residual compressive stress difference (MPa) Example 1 98.7 0.3 72.3 0.8 Example 2 97.2 0.3 70.8 1.2 Example 3 96.5 0.3 71.5 1.1 Example 4 97.5 0.3 71.0 1.0 Example 5 98.0 0.3 71.6 1.1 Example 6 97.8 0.3 72.1 0.9 Example 7 97.1 0.3 70.6 1.2 Example 8 96.8 0.3 70.2 1.4 Example 9 97.5 0.3 71.8 0.9 Example 10 96.5 0.3 70.5 1.8 Example 11 97.0 0.3 71.2 1.5 Example 12 98.9 0.2 73.5 0.7 Example 13 99.5 0.2 74.2 0.6 Comparative Example 1 95.8 0.6 62.4 4.8 Comparative Example 2 82.3 1.2 65.1 5.5 Comparative Example 3 96.9 0.5 66.8 3.2 Comparative Example 4 96.3 0.6 65.2 3.6 Comparative Example 5 96.1 0.4 68.9 6.2 Comparative Example 6 72.3 1.8 56.4 6.8 Comparative Example 7 85.6 1.2 60.5 5.2 Comparative Example 8 85.7 1.5 58.9 7.4 Comparative Example 9 78.5 2.5 54.2 8.2 Comparative Example 10 82.1 1.9 57.6 7.8 Comparative Example 11 71.5 3.2 65.7 8.5 Comparative Example 12 91.3 1.5 67.8 4.5 Comparative Example 13 95.7 0.6 66.5 3.8 Comparative Example 14 88.6 1.8 65.3 5.2 Comparative Example 15 94.9 0.8 66.0 3.5 Comparative Example 16 95.5 0.7 61.2 4.2 Comparative Example 17 96.2 0.6 63.5 3.9 Comparative Example 18 88.4 1.1 62.8 4.1 Comparative Example 19 84.1 1.6 60.1 4.8 Experimental conclusions and analysis: Experimental data show that the presence and parameter matching of spodumene-zircon composite micro powder directly determine the weather resistance and room temperature cold bending ability of the slab.

[0104] In Comparative Example 5, without the addition of the composite micropowder, the freeze-thaw strength retention rate was only 67.2%, the acid and alkali resistance mass loss rate was as high as 0.58%, and the transgranular fracture rate was only 15.6%, making cold bending of the slab impossible. The underlying mechanism is that without the induction of the composite micropowder, a continuous microcrystalline network structure cannot be formed after sintering, the surface micropores cannot be effectively sealed, and external corrosive media can easily penetrate, leading to performance degradation; at the same time, the fracture mode is mainly intergranular fracture, and the material is extremely brittle.

[0105] Comparative Examples 1 and 2 failed to achieve cold bending. When the doping amount was insufficient, the microcrystalline network was discontinuous, resulting in limited modification effect. When the doping amount was too high, the sintering shrinkage rate increased significantly, the green blank demolding qualification rate plummeted to 82.3%, and a large number of internal stress cracks were generated. The freeze-thaw strength retention rates of Comparative Examples 3 and 4 were only 89.4% and 87.1%, respectively, proving that a 3:1 lithium-zirconium ratio is the key to forming the optimal microcrystalline network.

[0106] The performance of Comparative Examples 16 and 17 also decreased significantly. The cationic additive can promote a partial solid-phase reaction between spodumene and zircon surfaces, forming an amorphous transition layer and improving interfacial bonding. Insufficient co-milling time cannot obtain sufficiently fine active micro powder, resulting in poor modification effect.

[0107] The freeze-thaw strength retention rate of Examples 1-3 was stable at 92.3% to 95.7%, the acid and alkali resistance mass loss rate was as low as 0.07% to 0.12%, and the transgranular fracture ratio was increased to 89.2% to 91.5%. All of them could achieve room temperature cold bending, proving that the composite micro powder parameter range defined by the present invention can achieve the optimal balance between weather resistance and formability.

[0108] Single or improperly proportioned plastic binders cannot meet the molding requirements of three-layer structures. In Comparative Example 6, when polyvinyl alcohol was used as the binder alone, the green blank demolding pass rate was only 72.3%, and the core layer density dropped to 89.5%. In Comparative Example 7, when the mass ratio of silica sol to organic binder was adjusted to 1:3, the demolding pass rate was still only 85.6%. Single organic binders leave a large number of pores after high-temperature burn-off, reducing density; while silica sol can form an inorganic binder phase, and a 1:1 compounding ratio can simultaneously take into account both the plasticity of the green blank and the sintering density.

[0109] The demolding pass rate of Examples 4-5 remained stable at 97.5% to 98.0%. If a uniform amount of additive is used, the bottom layer will have excessive plasticity and be prone to deformation, while the core layer will have insufficient plasticity and be prone to cracking, making it impossible to obtain a high-quality green blank.

[0110] When Comparative Example 8 uses a single-layer powder structure, the core layer density is only 85.7%, the freeze-thaw strength retention rate is 72.1%, and the flatness reaches 1.5 mm / m, making it completely impossible to cold bend. In Examples 1, 6, and 7, the core layer density is increased to 93.5%–94.1%, and the flatness is controlled within 0.3 mm / m. This indicates that fine particles in the surface layer can improve surface density and smoothness, and seal surface pores; coarse particles in the core layer can improve overall strength and resistance to deformation; the gradient particle size structure naturally forms a distribution with a gradient decrease in porosity from the surface to the center, effectively alleviating sintering shrinkage stress.

[0111] When using a one-time pressurization process in Comparative Example 9, the core layer density was only 85.7%, and the demolding qualification rate was 78.5%. Even after omitting the high-frequency micro-vibration step in Comparative Example 10, the density was only 87.6%. The three-stage pressurization can gradually expel air between powder particles, homogenize internal stress, and avoid stress concentration and poor air venting caused by one-time pressurization.

[0112] The core density of Comparative Examples 18 and 19 decreased to 91.2% and 89.5% respectively, and neither could achieve cold bending. However, when Example 1 used a 42Hz vibration that perfectly matched the natural resonant frequency of the agglomerates, the core density increased to 94.3%, and the minimum cold bending radius reached 1280mm. The resonance effect can maximize the particle rearrangement effect, so that the composite micro powder is uniformly dispersed and tightly packed, which cannot be achieved by conventional fixed-frequency high-frequency micro-vibration in the field, and is not a simple optimization of parameters.

[0113] When no edge buffer constraint is applied to Comparative Example 11, the pass rate of the green blank demolding drops sharply to 71.5%, and the flatness is as high as 3.2 mm / m. This indicates that concentrated shear stress will be generated at the edge of the mold during the pressing process, resulting in micro-cracks at the edge of the green blank and warping deformation of the plate.

[0114] The demolding pass rates of Comparative Examples 12 and 14 were only 91.3% and 88.6% respectively, and cold bending could not be achieved. Comparative Examples 13 and 15 had insufficient edge compaction due to excessive buffering. However, the demolding pass rates of Examples 1, 10, and 11 were stable at 96.5% to 97.0%, and the flatness was controlled within 0.3 mm / m. This proves that the parameter range can effectively disperse the edge shear stress and make the absolute value of the residual compressive stress difference between the edge and the center area of ​​the rock slab less than 2 MPa.

[0115] All 13 sets of embodiments fall within the range of component content and process parameters defined by the present invention, and can stably achieve the following technical effects: green blank demolding qualification rate ≥96.5%, core layer density ≥93.5%, freeze-thaw strength retention rate ≥92.3%, and minimum cold bending radius ≤1420mm; in stark contrast, all 19 sets of comparative examples show a significant decrease in at least one key performance indicator, and none of them can achieve the core invention objective of room temperature cold bending.

[0116] Compared with Comparative Example 5, Example 1 of this invention improves the green blank demolding qualification rate to 98.7%, freeze-thaw strength retention rate to 95.7%, fracture strength to 72.3 MPa, and flatness to 0.3 mm / m. It realizes room temperature cold bending of 1-2.9 mm ultra-thin rock slabs, and solves the technical problems of easy brittle fracture, poor flatness and insufficient weather resistance of ultra-thin rock slabs that have existed in the prior art, which is a significant improvement.

[0117] The flexible buffer constraint applied to the edge of the initial powder layer can effectively intervene in and change the stress transmission path during pressing. In Comparative Example 11, due to the lack of any edge flexible buffer constraint, the rigid mold frame edge generated a large concentrated shear stress on the powder during the pressing process, resulting in an absolute value of the residual compressive stress difference between the edge and center regions of the green blank during the depressurization stage as high as 8.5 MPa. This excessive residual compressive stress difference directly caused severe demolding springback and sheet warping deformation. In Example 1, by configuring a buffer constraint with an effective width of 15-25 mm at the edge of the mold... The confining medium is a flexible buffer medium with a Shore hardness of A70 to A85. During the compaction stage, this medium undergoes elastic deformation and effectively absorbs and dissipates the stress waves concentrated at the edges. This results in the absolute value of the residual compressive stress difference in the final product being strictly converged and controlled between 0.8 MPa and 1.8 MPa. This numerical range is far below the critical stress threshold that induces brittle fracture of the rock slab. This eliminates the physical hidden dangers of brittle fracture and microcrack initiation in the subsequent service conditions of the ultrathin rock slab from the root of the mechanical mechanism, and provides the necessary basic structural support for realizing the large curvature cold bending characteristics of the ultrathin rock slab.

[0118] Specifically, the ultra-thin sintered stone slabs obtained in any of the above embodiments are used as building facade materials, attached to curved building facades, curved interior decorations, or cylindrical surfaces. In actual construction scenarios, the ultra-thin sintered stone slabs, with a minimum cold bending radius of 1200mm to 1500mm at room temperature, are directly utilized. No high-temperature hot bending pretreatment or mechanical cutting of the sintered stone slab is required. A single ultra-thin sintered stone slab is physically bent and fixed to conform to the curvature of the target building surface. This application method allows the sintered stone slab surface layer to naturally and tightly adhere to the curved building substrate, achieving the desired curvature. Seamless overall coverage of the surface of a surface or cylinder; compared with the conventional construction method of using multiple narrow plates to cut and splice when dealing with curved surfaces, the application feature of this invention completely eliminates the splicing gaps of the exterior surface of the building. While maintaining the natural continuity and visual integrity of the surface texture of the rock slab, the elimination of physical joints further structurally blocks the microscopic path of outdoor rainwater and acid and alkali corrosive media to penetrate into the interior wall of the building along the joints. This substantially reduces the difficulty of waterproofing the complex curved substrate and extends the service life of the entire building curtain wall system.

[0119] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A process for preparing ultrathin slabs, characterized in that, Includes the following steps: S1. Spodumene and zircon, in a mass ratio of 3:1, are placed in an aqueous solution containing a cationic additive and wet-milled to obtain spodumene-zircon composite micropowder. The spodumene-zircon composite micropowder is then mixed into the bottom layer powder and the top layer powder. The amount of spodumene-zircon composite micropowder added to the bottom layer powder and the top layer powder is 8% to 12% of the total mass of the bottom layer powder and the top layer powder, respectively. S2. Add plastic binders to the bottom layer powder, core layer powder and top layer powder respectively, and lay the bottom layer powder, core layer powder and top layer powder in sequence to form an initial powder layer; The plastic binder is a compound prepared by mixing silica sol and organic binder in a mass ratio of 1:1, and the organic binder is an aqueous solution prepared by mixing polyvinyl alcohol and sodium carboxymethyl cellulose in a mass ratio of 2:

1. S3. The initial powder layer is subjected to low-pressure venting, medium-pressure stress equalization, and high-pressure superimposed high-frequency micro-vibration compaction operations in sequence, while the edges of the initial powder layer are subjected to flexible buffer constraint treatment; the effective width of the flexible buffer constraint is 15-25mm, the buffer thickness is 3-5mm, and the Shore hardness of the constraint medium is A70-A85; wherein the mechanical vibration frequency of the high-frequency micro-vibration compaction matches the natural resonant frequency of the agglomerates of the spodumene-zircon composite micro powder. S4. After depressurization and demolding, an ultra-thin blank is obtained, and the ultra-thin blank is dried. S5. The dried ultrathin blank is placed in a high-temperature zone for sintering. After sintering, it is cooled to obtain an ultrathin slab.

2. The preparation process of an ultrathin rock slab according to claim 1, characterized in that: In S1, the cationic auxiliary is selected from soluble salts containing magnesium ions, aluminum ions or yttrium ions; The wet co-milling time is 2-4 hours, and the median particle size of the spodumene-zircon composite micro powder is 0.5-1.0 μm. The amount of spodumene-zircon composite micropowder added to the bottom layer powder and the top layer powder is 8% to 12% of the total mass of the bottom layer powder and the top layer powder.

3. The preparation process of an ultrathin rock slab according to claim 1, characterized in that: The amount of plastic binder added in S2 is as follows: the mass fraction of plastic binder in the core layer powder is 4% to 6%, and the mass fraction of plastic binder in the bottom layer powder and the top layer powder is 1.5% to 2.5%.

4. The preparation process of an ultrathin rock slab according to claim 1, characterized in that: The mass ratio of the bottom layer powder, the core layer powder, and the surface layer powder in S2 is 1:2:1; the median particle size of the core layer powder is 45-60 μm, and the median particle size of the bottom layer powder and the surface layer powder is 20-35 μm.

5. The preparation process of an ultrathin rock slab according to claim 1, characterized in that: In S3, the specific parameters for low-pressure exhaust are to apply a pressure of 5-10 MPa and maintain it for 3-5 seconds; The specific parameters for the average stress during medium-pressure holding are: increasing the pressure to 20-30 MPa at a rate of 1-2 MPa / s and maintaining it for 8-12 seconds; The specific parameters for high-pressure superimposed high-frequency micro-vibration compaction are as follows: on a base pressure of 20-30 MPa, mechanical vibration with an amplitude of 0.1-0.3 mm and a frequency of 30-50 Hz is superimposed, while the pressure is increased to 40-55 MPa to complete the compaction.

6. The preparation process of an ultrathin rock slab according to claim 1, characterized in that: The drying temperature described in S4 is 100–120°C, and the drying time is 2–3 h; the high-temperature sintering temperature range described in S5 is 1150–1220°C, and the sintering time is 60–90 min.

7. An ultrathin slab, characterized in that, The ultrathin rock slab is prepared by any one of claims 1 to 6. The thickness of the slab is 1 to 2.9 mm. The porosity decreases gradually from the surface to the center. The absolute value of the residual compressive stress difference between the edge region and the center region of the slab in the same plane is less than 2 MPa. The ultrathin rock slab has cold bending characteristics at room temperature. The minimum cold bending radius ranges from 1200 mm to 1500 mm.

8. An application of the ultrathin rock slab as described in claim 7, characterized in that, The ultra-thin sintered stone slab is used as a building cladding material and is attached to the curved building facade, curved interior decoration or cylindrical surface, and the cold bending characteristics of the ultra-thin sintered stone slab are used to achieve seamless overall coverage.

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