Large-size natural ice crystal effect imitating glass product and industrial casting method thereof

Abstract

The invention relates to a large-size glass product with a natural ice crystal imitating effect and an industrial casting method of the large-size glass product. The product is a lead-free glass casting with the weight larger than or equal to 100 kg, dendritic crystal-shaped or snowflake-shaped devitrified phases which are formed by growing calcium fluoride as crystal nucleuses and are distributed randomly are arranged in the product, and the three-dimensional aesthetic effect imitating natural ice crystals is achieved. The method comprises the following steps: mixing lead-free glass particles with a calcium fluoride nucleating agent with a specific particle size, and filling a mixture into a special mold with a three-layer composite structure and a temperature monitoring function; and executing a four-stage programmed thermal regulation including melting homogenization, nucleation cooling, isothermal crystallization and super-slow multi-step annealing, wherein the melting and heat preservation time and the maximum thickness of the product meet the quantitative relation of t = k.H. Through systematic collaboration of materials, molds and processes, the technical problems that crystallization in large-size glass is not uniform and cracking is easily caused by thermal stress are solved, high yield and stable mass production of products of 500 kg or above are achieved, and the method is suitable for the fields of high-end buildings, art devices and decoration.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of special functional glass materials and advanced manufacturing technology, and particularly relates to a large-size lead-free glass product with internal biomimetic natural ice crystal aesthetics texture, and a stable, repeatable and scalable production method thereof. BACKGROUND

[0002] The ice crystal glass has an urgent market demand in the fields of high-end building curtain walls, large-scale art installations, luxury interior decoration and landmark public sculptures due to its unique, dynamic and natural visual artistic effect. However, the current technical paths to achieve similar glass effects have obvious limitations and cannot meet the requirements of large size and high quality production.

[0003] The current mainstream technical paths and their limitations mainly include:

[0004] Surface treatment method: such as CNC carving, laser etching or sandblasting. This method only forms patterns on the surface of the glass, lacks three-dimensional depth, and the visual effect is thin. At the same time, the large-scale processing efficiency is low, the energy consumption is high, and the patterns formed are often mechanical and stiff, which cannot simulate the randomness and level of natural ice crystals.

[0005] Traditional melt-cast crystallization method: this method attempts to form crystalline texture inside the glass, but is mostly limited to the production of small-size art products with a weight of less than 50 kg. When trying to scale up to the hundred-kilogram level or even larger, three major technical bottlenecks are generally faced:

[0006] Uncontrolled thermal stress: due to the low thermal conductivity of glass, the temperature difference between the inside and outside of the large-volume product during cooling is very large, and the huge internal stress is very easy to cause the product to burst, resulting in a very low yield.

[0007] Poor crystalline uniformity: the dispersion of the nucleating agent in the melt is uneven, and the thermal field in the kiln is also uneven, resulting in disorderly internal crystalline texture, excessive devitrification in some parts, or complete lack of crystallization, which cannot obtain a uniform and natural ice crystal effect.

[0008] Process cannot be repeated and cannot be scaled up: the traditional process relies heavily on the personal experience of the operator, the process parameters (such as holding time and cooling rate) are ambiguous, lack of quantitative basis, and cannot establish a stable and predictable mass production process model, which belongs to "craft" rather than "industrial technology".

[0009] The existing technologies (for example, patent document CN108840553A) mainly focus on the improvement of decorative small formulas or single process links, and lack of disclosure of complete technical systems for heavy industrialized mass production, especially for 500 kg or more. The thermal system, mold system and stress management method are not suitable for large-scale, standardized production.

[0010] Therefore, there is an urgent need in this field for a glass product and its systematic manufacturing technology that can simultaneously meet the requirements of grand natural ice crystal aesthetics, heavy weight (single piece ≥ 500 kg), high yield, and stable mass production. Summary of the Invention

[0011] The primary objective of this invention is to provide a large-sized (single piece weight ≥100 kg, preferably ≥500 kg) lead-free glass product with realistic, three-dimensional, randomly distributed ice crystal texture inside.

[0012] The core objective of this invention is to provide a complete industrial-scale melting and casting method for the aforementioned glass products. This method, through systematic material formulation design, specialized equipment development, and quantifiable, programmable thermal control strategies, overcomes the core technical challenges of internal stress management and crystallization uniformity control in large-volume glass, achieving a reliable transition from laboratory samples to heavy industrial products and stable mass production.

[0013] Technical solution

[0014] To achieve the above objectives, the present invention proposes a systematic technical solution with interrelated and synergistic effects, including the product itself and its preparation method.

[0015] (a) Large-size glass products with natural ice crystal effect

[0016] The product is a lead-free glass casting with a single piece weight ≥ 100 kg. More preferably, the product has a single piece weight ≥ 500 kg. It has randomly distributed dendritic or snowflake-like crystalline phases grown from calcium fluoride crystal nuclei. These crystalline phases, together with the glass matrix, constitute a three-dimensional visual effect that mimics natural ice crystals.

[0017] Specifically:

[0018] The glass products are glass castings weighing between 100 kg and 2000 kg per piece, such as large sheets, billets, or irregularly shaped sculpted components. Their core feature is:

[0019] Macroscopic visual characteristics: The interior of the product is filled with a three-dimensional interlocking structure that mimics natural ice crystals or snow, composed of crystalline and glassy phases. Under transmitted light, it presents white flocculent, dendritic, or snowflake-like patterns that are distributed from the inside out, with varying density and depth, creating a natural and dynamic visual effect with a unique artistic appeal.

[0020] Microstructural characteristics: Observed by scanning electron microscopy (SEM), its crystalline phase consists of needle-like, columnar, or dendritic crystals (mainly wollastonite CaSiO3, anorthite CaAl2Si2O8, etc.) grown from calcium fluoride (CaF2) particles as the original crystal nuclei. The crystal length is between 10-200 micrometers, and they are interlocked and embedded in a continuous glass matrix.

[0021] Performance characteristics: While maintaining a unique aesthetic effect, its internal interlocking crystal structure acts like "fiber reinforcement," increasing the bending strength of the product by 15%-30% compared to ordinary cast glass with the same base composition. At the same time, through an optimized annealing process, the product's coefficient of thermal expansion is well matched, ensuring its long-term structural stability under environmental temperature fluctuations and eliminating the risk of spontaneous cracking.

[0022] (II) Industrialized casting preparation method

[0023] This method is a closed-loop process for achieving precise control and repeatable execution of the aforementioned products, comprising four closely coordinated subsystems: materials, equipment, processes, and post-processing. It includes the following steps:

[0024] S1. Ingredients: Mix lead-free glass particles with a nucleating agent;

[0025] S2. Loading: Fill the mixture into the refractory mold;

[0026] S3. Programmed casting heat treatment: The process sequentially executes the melting and homogenization stage, the nucleation and cooling stage, the isothermal crystallization stage, and the stress relaxation annealing stage. The holding time t1 (hours) of the melting and homogenization stage is related to the maximum thickness H (cm) of the product as follows: t1 = k·H, where k ranges from 1.5 to 2.5. The stress relaxation annealing stage includes cooling at a rate of ≤3℃ / hour near the glass transition temperature Tg. When the product thickness is greater than 30cm, the cooling rate near Tg is ≤1.5℃ / hour. The nucleating agent is calcium fluoride powder with a particle size D50 of 10-50μm, and the amount added is 3-8% of the weight of the lead-free glass particles. The refractory mold is a three-layer composite structure, consisting of a dense refractory material working surface, a lightweight insulation layer, and a steel structure reinforcement frame from the inside out. Thermocouples are pre-embedded in the refractory mold for real-time monitoring of the internal temperature of the glass body during the heat treatment process.

[0027] Specifically:

[0028] 1. Materials Subsystem: Quantitative Collaborative Formulation

[0029] By weight percentage, the batch consists of the following:

[0030] Lead-free glass particles: accounting for 92%-97%. Aluminosilicate glass particles with high high-temperature viscosity and a wide crystallization temperature window are preferred, with a typical composition range of: SiO2 55-65%, Al2O3 18-25%, CaO+MgO 10-20%, Na2O+K2O <5%. The particle size is mainly 1-4cm, which is conducive to stacking and melting.

[0031] Nucleating agent: 3%-8% calcium fluoride (CaF2) powder, with a purity ≥97% and a particle size D50 strictly controlled within 10-50μm.

[0032] Synergistic control mechanism: The particle size and content of CaF2, together with the subsequent crystallization thermal regime (T2, t2), constitute a precise synergistic control window, which is the core of obtaining "natural random" texture rather than "spot-like" defects.

[0033] Particle size control: CaF2 with a particle size of 10-50 μm undergoes a "surface erosion-nucleus retention" process during the melting stage (T1), and the remaining nuclei become uniform and effective heterogeneous nucleation sites for subsequent formation. If the particle size is too small (<10 μm), it will completely dissolve, resulting in homogeneous nucleation, sparse texture, or overall devitrification; if the particle size is too large (>50 μm), it will be unevenly dispersed and easily form coarse crystal clusters ("spots").

[0034] Content and thermal matching: The content (3-8%) and the holding time t2 together determine the crystal density and size. If the content is too low, there will be insufficient nucleation sites and sparse texture; if the content is too high, there will be insufficient crystal growth space and it will easily become dense and devitrified.

[0035] Dual function: CaF2 not only provides heterogeneous nucleation sites (first role), but also introduces F - Ions are more effective at breaking down the glass network structure, significantly reducing the high-temperature viscosity of the melt in the crystallization temperature range (for example, the viscosity can be reduced by nearly an order of magnitude at 800°C). This "viscosity reduction" effect (the second layer of deepening effect) greatly promotes compositional homogenization and the diffusion rate of crystal growth units, shifting the growth mechanism to "interfacial reaction control," which is more conducive to the formation of dendrites, thus creating a macroscopically clear "ice crystal" visual effect.

[0036] Additives: Add 0.5%-2% of a composite clarifying agent (such as a mixture of CeO2 and NaNO3) to promote the removal of bubbles during the melting process and improve the purity of the product.

[0037] 2. Equipment Subsystem: Specialized Industrial Equipment

[0038] Casting kilns: Fully automatic shuttle kilns or bogie kilns using gas or electric heating. The kiln must have a multi-zone independent closed-loop precision temperature control system (at least upper, middle, lower, and side temperature zones) to ensure that the effective space temperature uniformity within the kiln is within ±5℃, and is equipped with the necessary atmosphere conditioning system.

[0039] Refractory mold system: Adopts a three-layer composite structure design, comprising, from the inside out:

[0040] (1) Liner: The working surface is composed of dense α-alumina or zircon refractory castable that does not wet the molten glass, ensuring that the surface of the product is smooth and easy to demold.

[0041] (2) Middle layer: High-strength lightweight mullite insulation layer to achieve gradient insulation and precisely control the cooling rate.

[0042] (3) Outer layer: Heavy steel reinforced frame, providing the overall strength and rigidity required to resist the hydrostatic pressure of molten glass.

[0043] Key innovation: High-temperature armored thermocouples are pre-embedded inside the refractory mold, with monitoring points extending to near the working surface, for real-time and accurate monitoring of the temperature of the glass core and surface, providing real-time data feedback for process execution.

[0044] Mixing and processing equipment: including large forced mixers, CNC diamond wire saws or water jets for precision cutting, and large CNC grinding and polishing production lines.

[0045] 3. Process Subsystem: Four-stage quantitative thermal regime (core)

[0046] All steps are executed automatically by the central control system according to the preset program, and there are quantitative relationships between key parameters.

[0047] Phase 1: Controlled Melting and Precision Homogenization

[0048] The temperature is increased to the target melting temperature T1 (1050℃-1150℃) at a rate of ≤80℃ / hour. The holding time t1 (hours) at T1 is dynamically determined based on the maximum thickness H (cm) of the product, following the quantitative model t1=k*H, where k is a coefficient with a value range of 1.5-2.5 hours / cm.

[0049] Theoretical and Experimental Basis: This model is based on the theory of unsteady-state heat conduction and diffusion, and the relationship between time and thickness is linearized to simplify engineering applications. Through a series of experiments, it is verified that k=2.0 can achieve the best technical and economic balance while ensuring the uniformity of composition and texture across the entire cross-section (consistency between center and edge >90%).

[0050] Phase Two: Gradient Cooling and Induced Nucleation

[0051] The temperature is slowly reduced from T1 to the nucleation temperature T2 (750℃-850℃) at a controlled rate of 20-40℃ / hour. This gradient cooling process is itself a key means of inducing thermodynamic instability and promoting the pre-precipitation of crystal nuclei.

[0052] Third stage: Isothermal crystallization growth

[0053] A prolonged isothermal holding period (t2) is performed, typically ranging from 5 to 20 hours, depending on the target crystal size and texture density. During this stage, residual CaF2 particles act as effective nucleation sites, triggering and dominating the dendritic growth of silicate crystals, forming macroscopic ice crystal textures. Precise control of T2 and t2 enables the "programming" and quantitative regulation of the final aesthetic effect.

[0054] Fourth stage: Ultra-slow stress relaxation annealing

[0055] This is crucial for ensuring that large-sized products do not crack and for preserving the perfect crystal morphology. Annealing is a multi-step process:

[0056] a) High-temperature stress relaxation stage: Reduce the temperature from T2 to the upper limit of annealing temperature T3 (approximately Tg+30℃) at a rate of ≤20℃ / hour, and hold at this temperature for a long time (t3≥24 hours).

[0057] b) Critical Slow Cooling Section: Starting from T3, the cooling process proceeds slowly through the maximum stress generation temperature zone (Tg to Tg-100℃) at an extremely low rate. For components with a thickness >20cm, the rate must be ≤3℃ / hour; for components with a thickness >30cm, the rate must be ≤1.5℃ / hour (only one-tenth or even less of the rate required by traditional small-part processes). This ultra-slow cooling not only eliminates stress but also prevents interfacial microcracks caused by the difference in thermal expansion coefficients between the glass matrix and the crystal, avoiding product "clouding" and strength reduction.

[0058] c) Low-temperature cooling section: After cooling to 300°C, it can be naturally cooled to room temperature with the furnace. The total annealing cycle can reach hundreds of hours.

[0059] 4. Post-processing subsystem

[0060] After demolding, a large CNC diamond wire saw or water jet is used for precise dimensional cutting. Then, a multi-head CNC grinding and polishing production line is used for automated and sequential grinding (from coarse grinding to fine grinding) and polishing to ensure consistent surface quality and perfectly present the internal ice crystal texture.

[0061] (III) Industrialized casting preparation method

[0062] A refractory mold for implementing the industrialized melting and casting preparation method, the refractory mold having a three-layer composite structure, including a dense refractory material lining in contact with molten glass, a lightweight refractory insulation layer covering the lining, and a steel structure support frame covering the insulation layer.

[0063] Beneficial effects of the present invention

[0064] Compared with the prior art, the present invention has the following significant advantages:

[0065] Overcoming industry technical bottlenecks: The system provides a complete technical solution for mass production of ice crystal glass weighing over 500 kg, which has overcome the fundamental contradiction that has long been difficult to balance between "large size", "high yield" and "beautiful and controllable texture", and has achieved a qualitative leap from artistic concept to reliable industrial product.

[0066] The effects of the technology are quantifiable, predictable, and repeatable.

[0067] High yield: By applying this method, the overall yield of 500 kg products can be steadily increased from less than 10% with traditional methods to over 70%, and even up to 90%.

[0068] Enhanced performance: The internally interlocking dendritic structure significantly improves the bending strength of the product by 15%-30%.

[0069] Process standardization: All key parameters (such as t1=k·H, annealing rate) are quantified and correlated, making the production process highly repeatable and programmable, reducing reliance on the operator's personal experience.

[0070] It possesses high industrial application value: it provides unprecedented giant integrated aesthetic glass materials for building curtain walls, large-scale public art, high-end interior decoration and other fields, creating new product categories and market space, and has significant economic and social benefits. Attached Figure Description

[0071] Figure 1 This is a process flow diagram of the industrial preparation method of the present invention.

[0072] Figure 2 This is a schematic diagram of the multi-layer composite structure of the special refractory mold system of this invention.

[0073] Figure 3 This is a typical four-stage thermal regime (temperature-time) curve of the present invention.

[0074] Figure 4 These are macroscopic and microscopic (SEM) photographs comparing the ice crystal effect inside the product of Example 1.

[0075] Figure 5 This is a schematic diagram comparing the yield rates of traditional small-part processes and the process of this invention during scale-up production. Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0077] Figure 1This invention demonstrates the complete industrial-scale preparation process of large-size imitation natural ice crystal glass. The process begins with the precise weighing and mixing of raw materials. After preparation and loading into a specialized mold, it enters the core "program-controlled melting and casting heat treatment" stage, which specifically includes four key sub-stages: melting and homogenization, nucleation and cooling, isothermal crystallization, and stress relaxation annealing. After heat treatment, post-processing such as unloading from the kiln, cutting, and polishing are performed, and finally, qualified products are obtained through comprehensive inspection. The process specifically incorporates two feedback loops (indicated by dashed arrows): "mixing uniformity inspection" and "finished product inspection - parameter optimization," and emphasizes the real-time feedback of "mold internal temperature monitoring" during the heat treatment stage, demonstrating the systematic nature, controllability, and high reliability of this method for industrial mass production.

[0078] Figure 2 This is a schematic diagram of the multi-layered composite structure of the special mold system of this invention. The mold adopts a three-layer composite design from the inside out: the inner layer is a dense refractory working surface (such as α-alumina) in direct contact with the molten glass, ensuring a smooth surface and preventing adhesion; the middle layer is a lightweight insulating transition layer (such as mullite castable) to achieve gradient insulation and control the cooling rate; the outer layer is a steel structure reinforced frame, providing the overall strength and rigidity required to resist the hydrostatic pressure of the molten glass. The top of the mold is equipped with a pouring / venting port and shrinkage allowance. The key innovation lies in the pre-embedded thermocouple sheaths and sensors inside the mold, with monitoring points extending near the working surface. This allows for real-time and accurate monitoring of the internal temperature of the glass during the melting and casting heat treatment process, providing data feedback for the execution of a precise four-stage thermal regime. This is the core guarantee for achieving uniform crystallization and stress control in large-size products. A magnified view clearly shows the sequential relationship of the materials in each layer and the arrangement of the thermocouples.

[0079] Figure 3 The core of the preparation method of this invention is the temperature-time curve of a four-stage programmed thermal regime. This curve defines the entire process from material melting to finished product cooling, characterized by four logically coherent and parameter-controllable stages: Stage I (melting and homogenization): holding at a high temperature T1 for a long time, with the holding time t1 and the product thickness H satisfying a quantitative relationship of t1 = k·H; Stage II (nucleation cooling): cooling at a controlled rate to the crystallization temperature T2; Stage III (isothermal crystallization): holding at a constant temperature of T2 for t2 to grow ice crystal texture; Stage IV (stress relaxation annealing): employing multi-step cooling, especially implementing ultra-slow cooling at ≤1.5°C / h (critical slow cooling section) when passing near the glass transition temperature Tg, to eliminate internal stress in large-size glass and ensure high yield. The dashed line in the figure indicates the position of the glass transition temperature Tg.

[0080] Figure 4It consists of two parts, left and right. The left image (A) is a macroscopic photograph of the product, showing a polished glass brick with naturally distributed white flocculent and dendritic ice-crystal textures inside, possessing a deep three-dimensional effect. The right image (B) is a microscopic photograph of the same sample under a scanning electron microscope (SEM), clearly showing the morphology of needle-like and columnar crystal networks growing from calcium fluoride (CaF2) particles embedded in the glass matrix. The comparison between the left and right images strongly demonstrates that the macroscopic aesthetic effect originates from the specific microscopic crystallization structure.

[0081] Figure 5 A direct comparison of the yield rates of traditional and the present invention's processes as product size increases is presented. The traditional process (hollow columns) is acceptable for producing small parts (<50kg), but the yield rate drops sharply with increasing size, reaching an extremely low level by the time the target mass production size (≥500kg). The present invention's process (solid columns) exhibits completely different technical characteristics: it achieves a high yield rate even with small parts, and the yield rate only decreases gradually with increasing size, maintaining a stable high level even at ≥500kg. The significant "scissors difference" between the two processes at the target mass production size (≥500kg) clearly defines the technological breakthrough zone, directly demonstrating that the present invention, through a systematic approach, fundamentally overcomes the industry-recognized bottleneck of large-size glass mass production, achieving a substantial leap from "unmanufacturable" to "stable mass production." Example 1: 20 kg-scale formulation and basic process validation specimen

[0082] Objective: To verify the feasibility of the basic formulation and the four-stage thermal regime.

[0083] Formula: 19.4 kg (97%) of lead-free aluminosilicate glass particles, 0.6 kg (3%) of calcium fluoride powder (D50=30μm), and 0.1 kg of composite clarifying agent.

[0084] Process flow: After the raw materials are mixed, they are loaded into a small refractory mold of refractory gypsum and placed in a programmable temperature-controlled electric kiln to execute the process curve: heating at 100℃ / h to 1100℃ and holding for 4 hours; cooling at 40℃ / h to 800℃ and holding for 3 hours; then performing multi-stage annealing, including holding at 580℃ (near Tg) for 10 hours, and slowly cooling at 2℃ / h to 480℃, and finally natural cooling.

[0085] Results: Glass bricks with uniform white flocculent and fine dendrites inside were obtained. SEM showed a dendritic structure centered on CaF2 particles, verifying the effectiveness of the core ratio and thermal logic. Example 2: 500 kg standard industrial mass production parts

[0086] Objective: To demonstrate the complete implementation process and effects of the present invention under the target mass production specifications.

[0087] Formula and equipment: Approximately 498 kg of aluminosilicate glass particles, approximately 26 kg of CaF2 powder (D50=30μm) (ratio approximately 95:5), and approximately 10 kg of clarifying agent. A 10 cubic meter multi-zone temperature-controlled gas-fired shuttle kiln and a 1m x 1m x 0.25m three-layer composite refractory mold (with pre-embedded thermocouples) are used.

[0088] Core technology:

[0089] Melting and homogenization: Heat to 1120℃ at a rate of 60℃ / h. Product thickness H=25cm, k=2.0, hold at temperature t1=50 hours.

[0090] Isothermal crystallization: the temperature is lowered to 820℃ at a rate of 30℃ / h, and held at this temperature for t2=12 hours.

[0091] Stress relaxation annealing: A multi-step process is performed, with the cooling rate strictly controlled at 1.5℃ / hour in the critical slow cooling section (near Tg). The total annealing time is approximately 240 hours.

[0092] Results: A crystal glass plate weighing approximately 510 kg with realistic and natural internal texture was successfully produced. No macroscopic cracks were found, and the residual stress met commercial grade 1 standards. The overall yield rate of continuous production batches remained stable at 90%. Example 3: 1500 kg-class ultra-large art components

[0093] Objective: To demonstrate the scalability of the process.

[0094] Implementation: Scale up the formula proportionally and customize irregularly shaped three-layer composite refractory molds. Adjust core processes: Extend t1 (calculated based on the maximum cross-sectional thickness, approximately 80 hours); extend t2 to 18-20 hours; reduce the critical slow cooling rate to below 0.8℃ / hour, and increase the total annealing cycle to over 500 hours.

[0095] Results: Giant irregularly shaped ice crystal glass sculptures were successfully prepared with a 100% yield, proving the reliability of this method in handling extreme sizes.

[0096] Comparison and quantitative data

[0097] Comparative Example A (Annealing Process Comparison): The same formulation and process as in Example 2 were used, but the critical slow cooling rate was changed to 10°C / h. Result: The product cracked during cooling, with extremely high residual stress (>30nm / cm), proving that the traditional annealing rate cannot be used for large-size products.

[0098] Comparative Example B (Comparison of nucleating agent particle size):

[0099] B1 (D50=80μm): The internal crystals of the product are coarse and uneven, appearing as "spots", resulting in a harsh visual effect.

[0100] B2 (D50=5μm): The product is uniformly milky white and opaque, without ice crystal texture.

[0101] Performance data: Compared with ordinary cast glass of the same composition, the product of Example 2 has an increased bending strength of about 38%, an increased Vickers hardness of about 12%, and an increased fracture toughness of about 20%.

[0102] Yield data: Example 2 (500kg class) achieved a yield of 90% in continuous production; Example 3 (1500kg class) achieved a yield of 100%.

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A large-size glass product with a natural ice crystal effect, characterized in that, The product is a lead-free glass casting with a single piece weight of ≥100 kg. Its interior has randomly distributed dendritic or snowflake-like crystalline phases grown from calcium fluoride as crystal nuclei. These crystalline phases, together with the glass matrix, constitute a three-dimensional visual effect that mimics natural ice crystals.

2. The glass article according to claim 1, characterized in that, The weight of a single piece of the product is ≥500 kg.

3. An industrial casting method for preparing glass articles as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Ingredients: Mix lead-free glass particles with a nucleating agent; S2. Loading: Fill the mixture into the refractory mold; S3. Programmed casting heat treatment: sequentially execute the melting and homogenization stage, the nucleation and cooling stage, the isothermal crystallization stage, and the stress relaxation annealing stage.

4. The method according to claim 3, characterized in that, The holding time t1 (hours) during the melting and homogenization stage is related to the maximum thickness H (cm) of the product by the following relationship: t1 = k·H, where the value of k ranges from 1.5 to 2.

5.

5. The method according to claim 3 or 4, characterized in that, The stress relaxation annealing stage includes cooling at a rate of ≤3°C / hour near the glass transition temperature Tg.

6. The method according to claim 5, characterized in that, When the product thickness is greater than 30cm, the cooling rate near Tg is ≤1.5℃ / hour.

7. The method according to claim 3, characterized in that, The nucleating agent is calcium fluoride powder with a particle size D50 of 10-50 μm, and the amount added is 3-8% of the weight of the lead-free glass particles.

8. The method according to claim 3, characterized in that, The refractory mold is a three-layer composite structure, consisting of a dense refractory material working surface, a lightweight insulation layer, and a steel structure reinforcement frame from the inside out.

9. The method according to claim 8, characterized in that, The refractory mold is pre-embedded with thermocouples for real-time monitoring of the internal temperature of the glass body during the heat treatment process.

10. A refractory mold for implementing the method according to any one of claims 3 to 9, characterized in that, The refractory mold is a three-layer composite structure, including a dense refractory material lining in contact with the molten glass, a lightweight refractory insulation layer covering the lining, and a steel structure support frame covering the insulation layer.

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