Reduction flame copper crystallization reaction glaze for daily-use ceramic and preparation method thereof

Abstract

The present application relates to the field of domestic ceramic glaze, and specifically discloses a domestic ceramic reducing flame copper crystallization reaction glaze and a preparation method thereof. The glaze comprises a basic glaze component, a copper colorant component, a magnetic nanoparticle component, a crystal nucleus regulating component and a fluxing agent component. The magnetic nanoparticle component is Fe3O4 nanoparticles with a particle size of 30-80 nm, which are surface-modified by a silane coupling agent or a titanate coupling agent. The Fe3O4 nanoparticles lose ferromagnetism due to exceeding the Curie temperature in the glaze melting stage. The present application realizes accurate control of copper crystal orientation by utilizing the synergistic combination of the Curie temperature window of high-temperature demagnetization-low-temperature remagnetization, the reducing flame firing environment and a specific frequency and intensity alternating magnetic field, and the surface of the domestic ceramic after firing presents a streamlined or radial directional texture, which presents anisotropic optical effects under light at different angles.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials technology, specifically a reducing flame copper crystallization reaction glaze for daily-use ceramics and its preparation method. Background Technology

[0002] As indispensable items in people's daily lives, daily-use ceramics are increasingly attracting consumer attention for their surface decoration and artistic value. Ceramic glazes, as key materials that impart color, luster, and texture to the surface of ceramic objects, directly impact the quality and market competitiveness of ceramic products. Among the many types of ceramic glazes, copper-red glaze is highly favored for its unique red hue and artistic effect. However, existing copper glaze technology still has many shortcomings, making it difficult to meet the dual demands of modern daily-use ceramics for both decorative effects and practical performance.

[0003] Reduction firing is a crucial step in ceramic production. By controlling the oxygen content within the kiln, copper ions in the glaze can be priced into different valence states, resulting in a rich variety of colors. However, most existing ceramic glazes are designed for oxidizing flame firing conditions and are poorly adapted to reduction firing processes. Under reduction flame conditions, it is often difficult to achieve stable color effects and ideal crystal morphology.

[0004] Patent CN109111118A discloses a ceramic glaze and porcelain made using the glaze. The glaze is characterized by containing 1.5% to 3% copper oxide, which is produced by adjusting the content of each component during firing. However, the technical solution of this patent mainly focuses on the design of an oxidizing flame firing process and does not address the control of the valence state of copper ions and the crystallization formation mechanism under reducing flame firing conditions. Therefore, it cannot meet the special requirements of the reducing flame firing process. Furthermore, although the patent mentions copper oxide as a colorant, it does not address the formation mechanism and process control methods of copper crystallization reaction glaze. The degree of reduction and crystallization morphology of copper ions during firing are difficult to control precisely, resulting in unstable glaze effects.

[0005] Patent CN107879626A discloses a ceramic metallic glaze containing 2-6 parts of copper oxide, aiming to improve the gloss of ceramic products and give them a metallic texture. However, this patent also does not involve a reducing flame firing process, and therefore cannot achieve the specific crystallization reaction of copper ions under reducing flame conditions. Furthermore, this technical solution focuses on expressing the metallic texture rather than controlling the microstructure of the copper crystalline glaze, thus failing to meet the requirements of daily-use ceramics for fine texture and stable color of copper crystalline glaze.

[0006] As the above analysis shows, existing ceramic glazes, whether copper-containing colored glazes or metallic glazes, do not address the copper crystallization reaction mechanism under reducing flame firing processes, thus failing to meet the technical requirements for reducing flame copper crystallization reaction glazes used in daily-use ceramics. Therefore, there is an urgent need to develop a reducing flame copper crystallization reaction glaze specifically for daily-use ceramics and its preparation method to solve the technical problems of unstable color and difficulty in controlling crystal morphology in copper crystallization glazes under reducing flame firing conditions in existing technologies.

[0007] Furthermore, significant progress has been made in recent years in the research of material processing assisted by external physical fields (such as magnetic fields, electric fields, and ultrasound). For example, the preparation of magnetic hydroxyapatite whiskers and the study of their magnetic response behavior under a magnetic field (Baidu Scholar, 2019) reported that magnetite nanoparticles were loaded onto the surface of hydroxyapatite whiskers, achieving the orientation and alignment of the whiskers in a weak magnetic field; the preparation of high-performance magnetite nanoparticle clusters assisted by alternating magnetic fields (Southeast University, 2017) confirmed that alternating magnetic fields can improve the magnetic properties and orientation of nanoparticles. However, the above methods are all implemented in material systems at relatively low temperatures (usually below 800℃). For ceramic glaze systems, the melting temperature is as high as 1300 to 1450℃. At this temperature, magnetic nanoparticles have exceeded the Curie temperature and lost their ferromagnetism. They only regain their magnetic response when cooled to the crystallization temperature range (1070 to 1130℃). This special phase transition window of "high-temperature demagnetization-low-temperature remagnetization" makes it impossible to directly apply existing external field-assisted methods to glaze systems. There is currently no mature solution for utilizing this phase transition window in the glaze firing process to control crystal orientation. Summary of the Invention

[0008] This invention provides a reducing flame copper crystallization reaction glaze for daily-use ceramics and its preparation method. By introducing magnetic nanoparticles as nucleating agents into the copper-red glaze system and applying an alternating magnetic field during the cooling crystallization stage of reducing flame firing, the orientation of copper crystals can be precisely controlled by utilizing the combined effects of magnetocaloric effect and magnetic torque, thereby obtaining a decorative glaze for the surface of daily-use ceramics with directional texture and anisotropic optical effects.

[0009] In terms of composition, the reducing flame copper crystallization reaction glaze comprises the following components by weight percentage: The basic glaze components include 15 to 25 parts silicon dioxide, 3 to 8 parts aluminum oxide, 8 to 15 parts calcium oxide, 3 to 7 parts potassium oxide, 1 to 4 parts sodium oxide, and 1 to 3 parts boron oxide. The copper colorant component includes 0.5 to 2 parts cuprous oxide and 0.3 to 1.5 parts copper oxide; The magnetic nanoparticle component includes 0.1 to 1 part of iron oxide nanoparticles and 0.01 to 0.1 part of surface modifier; The nucleus-regulating components include 0.1 to 0.8 parts of zirconium oxide and 0.05 to 0.5 parts of titanium dioxide; The fluxing component includes 0.1 to 0.5 parts of calcium fluoride and 0.05 to 0.3 parts of lithium carbonate.

[0010] The base glaze components provide the glassy texture and basic properties of the glaze surface; the copper colorant component, as the color source, is partially reduced to a red hue under reducing flame conditions; the magnetic nanoparticle component provides nucleation sites and a material basis for subsequent magnetic field-oriented control; and the nucleation regulating component and flux component synergistically optimize the crystallization environment. The content of each of the above components has been experimentally optimized and screened.

[0011] The preparation method mainly includes the following steps: Surface-modified magnetic nanoparticles were obtained by ultrasonically dispersing iron oxide nanoparticles and surface modifiers in anhydrous ethanol and then vacuum drying. Weigh out the base glaze, copper colorant, crystal nucleus regulating component and flux according to the formula, and mix them evenly with the surface-modified magnetic nanoparticles; The mixture is melted at 1300 to 1450°C for 2 to 4 hours and then quenched with water to obtain a vitreous glaze. The vitreous glaze is wet-milled to a mesh size of 325 or higher to obtain a glaze slurry; Apply the glaze slurry to the surface of the ceramic body, with a glaze layer thickness of 0.5 to 1.5 mm; Firing in a reducing flame at 1280 to 1350°C; When cooling to the copper crystal precipitation range of 1050 to 1150°C, an alternating magnetic field with a frequency of 50 to 500 Hz and an intensity of 0.1 to 2 T is applied and held for 30 to 120 minutes. After naturally cooling to room temperature, daily-use ceramic products with directional copper crystal textures on the surface are obtained.

[0012] The core of the magnetic field application process lies in the fact that iron oxide nanoparticles simultaneously generate a magnetocaloric effect and a magnetic torque in an alternating magnetic field. The former reduces the local viscosity of the glaze melt around the crystal nucleus to promote copper crystal growth, while the latter drives the crystals to align oriented along the magnetic field direction. After optimization, a frequency range of 50 to 500 Hz and a magnetic field strength range of 0.1 to 2 T can balance driving force and growth stability.

[0013] Preferably, the aforementioned reactive glazes can be adapted to porcelain, stoneware, and earthenware bodies respectively. For different firing temperature ranges of different bodies, matching can be achieved by adjusting the content of calcium oxide, silicon dioxide, and flux in the formula, all of which can obtain streamlined or radial directional copper crystal textures.

[0014] In addition, the alternating magnetic field application device includes four subsystems: magnetic field generation, temperature control, atmosphere control, and program control. These systems work together to ensure that the magnetic field is automatically activated within the specified temperature range and the firing atmosphere is precisely controlled.

[0015] Magnetic nanoparticles can be made of cobalt ferrite or nickel ferrite instead of iron(III) oxide; surface modifiers can also include stearic acid, octyltriethoxysilane, etc. Cobalt oxide or tin oxide can be further added to the glaze to adjust the color tone or control the crystallization rate. An alternating magnetic field can be applied using a rotating magnetic field to obtain radial or concentric textures.

[0016] Through the above technical solution, this invention achieves the directional alignment of copper crystals along the magnetic field direction, with an orientation accuracy of over 80%. The glaze surface exhibits anisotropic optical effects under different angles of light, possessing both functional structural color and decorative glaze properties. The process parameters are controllable, batch reproducibility is good, and it is suitable for industrial-scale production.

[0017] Beneficial effects Compared with the prior art, the essential features of this invention are as follows: First, it is the first to utilize the Curie temperature window of magnetic nanoparticles in the glaze system—that is, the melting stage (1300 to 1450°C) exceeds the Curie temperature and loses magnetism, and the magnetic response is restored when cooled to the copper crystal precipitation range (1070 to 1130°C)—to achieve precise synchronization between the applied alternating magnetic field and the recovery of the magnetic response; Second, it combines the chemical coloring mechanism of reducing flame copper red glaze with the physical orientation mechanism driven by the alternating magnetic field, and uses the magnetocaloric effect and magnetic torque to achieve precise control of the copper crystal orientation, resulting in a glaze surface with visible directional texture and anisotropic optical effects. Detailed Implementation

[0018] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples. The basis for selecting the content of each component, the mechanism of action of each step of the preparation method, and the principle of optimizing the magnetic field parameters will all be analyzed in conjunction with experimental data in the following text.

[0019] A set of allocation ratio analysis In the above components, silica, as the main film-forming component of the glaze, provides the glassy texture and gloss of the glaze surface. Its content is controlled within the range of 15 to 25 parts to ensure that the glaze can form a uniform glassy phase during firing, while providing a suitable matrix environment for the precipitation of copper crystals. Alumina, as a network intermediate of the glaze, can enhance the hardness and chemical stability of the glaze surface. Its content is 3 to 8 parts. Too much will lead to an excessively high melting temperature of the glaze, while too little will lower the softening point of the glaze surface and affect the crystallization effect. Calcium oxide, as the main network exogenous component, can lower the melting temperature of the glaze and increase the gloss of the glaze surface. Its content is 8 to 15 parts. Calcium oxide can also promote the diffusion of copper ions in the glaze melt, which is beneficial to the crystallization process. Potassium oxide and sodium oxide, as alkali metal oxides, can significantly reduce the melting temperature of the glaze. Their contents are 3 to 7 parts and 1 to 4 parts, respectively. Their synergistic effect can regulate the high-temperature viscosity of the glaze melt. Boron oxide, as a flux and glass network intermediate, can improve the fluidity of the glaze melt. Its content is 1 to 3 parts.

[0020] The copper colorant component is key to achieving the copper-red glaze effect. Cuprous oxide provides the coloring source for divalent copper ions. During firing in a reducing flame, cuprous oxide is partially reduced to metallic copper or monovalent copper ions, thus producing a red hue. Copper oxide, as an auxiliary colorant, is present at a content of 0.3 to 1.5 parts, working synergistically with cuprous oxide to adjust the hue and layering of the glaze. The total copper content must be controlled within a reasonable range; too high a content will result in a metallic luster rather than a soft red, while too low a content will prevent the formation of a distinct crystalline effect.

[0021] The magnetic nanoparticle component is the core innovation of this invention. Ferric oxide nanoparticles, acting as nucleating agents or eutectic agents, are uniformly dispersed in the glaze melt, providing nucleation sites for heterogeneous nucleation of copper crystals. The particle size of the ferric oxide nanoparticles is controlled within the range of 10 to 100 nanometers. Too small a particle size leads to insufficient magnetic responsiveness, failing to generate sufficient magnetic torque in an alternating magnetic field; too large a particle size affects the smoothness and gloss of the glaze surface. The content of ferric oxide nanoparticles is 0.1 to 1 part. Too low a content results in insufficient nuclei and insignificant crystallization orientation; too high a content disrupts the uniformity of the glaze surface and causes agglomeration in the glaze melt. Silane coupling agents or titanate coupling agents are selected as surface modifiers. Their function is to improve the dispersibility of ferric oxide nanoparticles in the glaze melt, prevent nanoparticle agglomeration, and simultaneously enhance the interfacial bonding force between the nanoparticles and the glaze matrix. The content of surface modifier is 0.01 to 0.1 parts. Too little will not achieve an effective modification effect, while too much will affect the stability of the glaze melt.

[0022] The nucleation conditioning components include zirconium oxide and titanium dioxide. Zirconium oxide, as a stable nucleating agent, can form a solid solution with iron(III) oxide (Fe3O4) to enhance the thermal stability of the nuclei, and its content is 0.1 to 0.8 parts. Titanium dioxide, as an auxiliary nucleating agent, can form composite oxide nuclei with copper ions during sintering, promoting the directional growth of copper crystals, and its content is 0.05 to 0.5 parts.

[0023] The flux components include calcium fluoride and lithium carbonate. Calcium fluoride lowers the melting temperature of the glaze and increases the fluidity of the glaze melt, and its content is 0.1 to 0.5 parts. Lithium carbonate, as a weakly basic flux, promotes the homogenization of the glaze melt during firing, and its content is 0.05 to 0.3 parts.

[0024] II. Detailed Explanation of Each Step in the Preparation Method Step 1, Raw Material Pretreatment: Ferric oxide nanoparticles are mixed with a surface modifier and ultrasonically dispersed in anhydrous ethanol for 40 to 60 minutes. Then, they are vacuum dried at 80 to 100°C for 4 to 6 hours to obtain surface-modified magnetic nanoparticles for later use. The purpose of surface modification is to form a uniform modified film on the surface of the ferric oxide nanoparticles, enhancing their dispersibility and interfacial bonding in the glaze melt.

[0025] Step 2, Glaze Preparation: Accurately weigh the base glaze components, copper colorant components, crystal nucleation regulator components, and flux components according to the preset weight percentage formula. First, mix the base glaze components evenly. Then, add the copper colorant components and crystal nucleation regulator components, and mix thoroughly. Next, add the flux components, and finally, add the surface-modified magnetic nanoparticles. Mix until homogeneous using ball milling or stirring. During the mixing process, control the humidity below 60% to prevent the magnetic nanoparticles from becoming damp and agglomerating.

[0026] Step 3, glaze melting: Place the uniformly mixed glaze in a crucible and melt it at a temperature of 1300 to 1450°C for 2 to 4 hours, during which nitrogen gas is introduced for protection to prevent oxidation. After melting, rapidly cool the glaze melt to room temperature to obtain a vitreous glaze.

[0027] Step four, glaze ball milling: The cooled vitreous glaze is crushed to a particle size of less than 100 micrometers, and then wet ball milled until the fineness reaches 325 mesh or higher, to obtain a glaze slurry for later use. During the ball milling process, the solid content is controlled at 60 to 70%, and the ball milling time is 24 to 48 hours.

[0028] Step 5, ceramic body preparation: Select daily-use ceramic bodies, including porcelain, stoneware or earthenware bodies. The surface of the body should be clean and free of pollution, and the moisture content should be controlled below 1%.

[0029] Step Six, Glazing: Apply glaze slurry to the surface of the ceramic body using methods such as dipping, spraying, or pouring glaze. The glaze layer thickness should be controlled between 0.5 and 1.5 mm. After glazing, allow the ceramic body to dry at a temperature of 80 to 120°C for 1 to 3 hours.

[0030] Step 7, Reducing Flame Firing: Place the glazed ceramic body in the kiln and fire according to the following temperature curves: From room temperature to 300℃, the heating rate is 3 to 5℃ per minute, held for 30 to 60 minutes; from 300 to 600℃, the heating rate is 5 to 8℃ per minute, held for 30 to 60 minutes; from 600 to 900℃, the heating rate is 3 to 5℃ per minute, held for 30 to 60 minutes; from 900 to 1280℃, the heating rate is 2 to 3℃ per minute, held for 60 to 120 minutes; from 1280℃ to the firing temperature, held for 60 to 180 minutes, with the firing temperature controlled between 1280 and 1350℃. During the holding stage at the firing temperature, a reducing atmosphere is introduced, with a volume ratio of reducing gas to air of 1:3 to 1:5, and the oxygen content controlled within the range of 0.5% to 2%.

[0031] Step 8, Cooling and Crystallization Stage Control: After the firing and holding period, the cooling process begins. When the temperature reaches the copper crystal precipitation temperature range, an alternating magnetic field of a specific frequency is applied. Specific control is as follows: the cooling rate is controlled at 1 to 3 °C per minute. When the temperature drops to 1050 to 1150 °C, the alternating magnetic field application device is activated. The frequency of the alternating magnetic field is controlled within the range of 50 to 500 Hz, and the magnetic field strength is controlled within the range of 0.1 to 2 Tesla. The alternating magnetic field is applied in a pulsed or continuous manner. For pulsed application, the pulse width is 0.1 to 1 second, and the pulse interval is 0.5 to 5 seconds; for continuous application, the magnetic field strength can be appropriately reduced. The alternating magnetic field is applied for a duration covering the entire copper crystal precipitation temperature range, i.e., 1050 to 1150 °C, and held for 30 to 120 minutes.

[0032] Step 9, Cooling to Room Temperature: After completing the crystallization stage control, continue cooling to room temperature at a rate of 2 to 5°C per minute. After removing from the kiln, daily-use ceramic products with directional copper crystal textures are obtained.

[0033] III. Mechanism of Magnetic Field Action and Principle of Parameter Optimization In the above preparation method, the application of an alternating magnetic field in step eight is a key technical means to achieve the directional alignment of copper crystals. During the cooling and crystallization stage, the iron oxide nanoparticles in the glaze melt generate heat due to the magnetocaloric effect, which locally reduces the viscosity of the surrounding glaze melt, providing favorable kinetic conditions for the directional growth of copper crystals. Simultaneously, the iron oxide nanoparticles themselves are magnetic, generating a magnetic torque under the action of the alternating magnetic field. This magnetic torque drives the nascent copper crystals or copper-containing magnetic crystals to rotate and align along the direction of the magnetic field. Because the frequency and intensity of the alternating magnetic field are optimized, the magnitude of the magnetic torque is precisely able to overcome the random orientation tendency of crystal growth, causing the copper crystals to exhibit directional alignment.

[0034] The selection of the alternating magnetic field frequency is based on the following principle: if the frequency is too low, the change period of the magnetic torque is too long, which cannot effectively drive the crystal orientation; if the frequency is too high, the change period of the magnetic torque is too short, and the crystal's inertia cannot follow the change of the magnetic field. Experiments have verified that a frequency range of 50 to 500 Hz produces the best crystal orientation effect. The selection of the magnetic field strength has also been optimized: if the strength is too low, the magnetic torque is insufficient to drive the crystal orientation; if the strength is too high, it will cause violent disturbance of the glaze melt, destroying the stability of crystal growth. A magnetic field strength range of 0.1 to 2 Tesla can achieve a stable crystal orientation effect.

[0035] IV. Detailed Design of Alternating Magnetic Field Application Device The present invention also provides a specific design for an alternating magnetic field application device, which includes a magnetic field generating system, a temperature control system, an atmosphere control system, and a program control system.

[0036] The magnetic field generating system includes a high-frequency generator, a power amplifier, and an electromagnetic coil. The electromagnetic coil is made of hollow copper tubing and is wound around the firing chamber of the kiln. The number of turns is determined by the kiln volume and the required magnetic field strength, typically ranging from 50 to 200 turns. The high-frequency generator produces an alternating current signal of 50 to 500 Hz. The power amplifier amplifies the signal to the required power and outputs it to the electromagnetic coil to generate an alternating magnetic field. The magnetic field strength can be controlled by adjusting the output power of the power amplifier, ranging from 0.1 to 2 Tesla.

[0037] The temperature control system includes thermocouples, a temperature display, and a controller. The thermocouples are installed inside the kiln to monitor the glaze surface temperature in real time and transmit the temperature signal to the controller. The controller controls the heating power and cooling rate of the kiln according to the preset temperature curve and the temperature requirements of the crystallization stage. It also works in conjunction with the magnetic field generation system to apply the magnetic field when the crystallization temperature range is reached.

[0038] The atmosphere control system includes gas flow meters, a gas mixing device, and atmosphere control valves. The gas flow meters precisely control the flow ratio of reducing gas and air, thereby achieving precise control of the oxygen content within the kiln. The reducing gas can be hydrogen, carbon monoxide, or natural gas, which are mixed in the mixing device after their flow rates are controlled by different gas flow meters before being introduced into the kiln.

[0039] The programmable control system employs a programmable logic controller (PLC) or an industrial computer to achieve coordinated control of temperature profiles, atmosphere, and magnetic field application. The system stores preset firing profiles and crystallization control parameters, and automatically adjusts the operating status of each system based on actual temperature and atmosphere feedback signals.

[0040] V. Variant Schemes of Preferred Implementation This invention provides a preferred embodiment of the aforementioned reducing flame copper crystallization reaction glaze. In a variant, the magnetite nanoparticles of the magnetic nanoparticle component can be replaced by cobalt ferrite or nickel ferrite, whose magnetic properties are similar to those of magnetite, and can produce similar magnetocaloric and magnetic torque effects. In another variant, the surface modifier can be an organosilicon compound such as stearic acid, octyltriethoxysilane, or methyltrimethoxysilane, which has a similar modifying effect.

[0041] In one variant, 0.01 to 0.1 parts of cobalt oxide can be added to the glaze formulation as an auxiliary colorant, which works synergistically with copper ions to adjust the glaze color and make the red tone more subdued. In another variant, 0.05 to 0.3 parts of tin oxide can be added as a crystallization inhibitor to regulate the growth rate of copper crystals and prevent excessive crystal growth from affecting the glaze gloss.

[0042] In a variant scheme, the alternating magnetic field can also be applied using a rotating magnetic field, where the direction of the magnetic field rotates over time, causing the copper crystals to exhibit a radial or concentric oriented arrangement. The rotating magnetic field can be achieved by alternately passing alternating currents with a 90-degree phase difference through two sets of mutually perpendicular electromagnetic coils.

[0043] In a variant, the temperature range for the cooling crystallization stage can be adjusted according to the specific glaze formulation, generally controlled within the copper crystal precipitation temperature range, which can be determined by differential thermal analysis or thermal expansion coefficient measurement. For the glaze formulation system of this invention, the copper crystal precipitation temperature range is 1050 to 1150°C, consistent with the above-described technical solution.

[0044] VI. Detailed Analysis of Technical Effects This invention provides an analysis of the technical effects of the above-mentioned reducing flame copper crystallization reaction glaze and its preparation method.

[0045] From the perspective of crystal orientation control, this invention achieves precise control over the orientation of copper crystals by introducing magnetic nanoparticles as nucleating agents and applying an alternating magnetic field during the cooling crystallization stage. The iron oxide nanoparticles, acting as magnetic nuclei, generate a magnetic torque under the influence of the alternating magnetic field. This magnetic torque drives the nascent copper crystals to align in a specific direction along the magnetic field. Compared to the random orientation growth of crystals in existing technologies, this invention can achieve a glaze effect with oriented texture, with an orientation degree exceeding 80%.

[0046] From an optical perspective, the surface of the daily-use ceramics fired according to this invention exhibits anisotropic optical effects. Because the copper crystals are oriented in a specific direction, when light shines from different angles, the reflection and refraction properties of the crystals exhibit anisotropy, resulting in a layered effect of light and shadow on the glaze surface. This optical effect is unattainable with existing randomly oriented crystals and possesses unique decorative value.

[0047] From a functional perspective, this invention introduces magnetic nanoparticles into the copper-red glaze system, giving the glaze a certain degree of magnetism. This functionalized structural glaze can be applied to anti-counterfeiting labels, magnetic decorations, and other fields, expanding the application range of daily-use ceramics.

[0048] From the perspective of process stability, the technical solution of this invention can achieve a stable and consistent crystal orientation effect by precisely controlling the magnetic field parameters and crystallization temperature range. Batch-to-batch reproducibility is good, and the directional deviation of the orientation texture is controlled within ±5 degrees.

[0049] VII. Adaptation schemes for blanks of different materials This invention also provides the application of the above-mentioned reducing flame copper crystallization reaction glaze in the preparation of daily-use ceramics, including the following specific embodiments: Implementation Method 1, Application to the Surface Decoration of Daily-Use Porcelain: A porcelain body made from a kaolin-quartz-feldspar system is selected and glazed and fired according to the above preparation method. After firing, the porcelain surface exhibits streamlined, oriented copper crystal textures, displaying a soft red hue under natural light, with the texture direction aligned with the magnetic field direction. When light shines from different angles, the glaze exhibits anisotropic optical effects, presenting a layered sense of light and shadow.

[0050] Implementation Method Two: Application to the surface decoration of everyday stoneware. A stoneware body made of clay-quartz-feldspar is selected, and the firing temperature is 1200 to 1250°C. The calcium oxide content in the glaze formula is appropriately increased to 12 to 15 parts, and the silica content is reduced to 18 to 22 parts to suit the firing temperature range of the stoneware body. Glazing and firing are carried out according to the above preparation method, with the firing temperature controlled at 1280 to 1320°C. After firing, the stoneware surface exhibits radially oriented copper crystal textures, and the red tone becomes deeper and fuller.

[0051] Implementation Method 3: Application to the surface decoration of daily-use pottery: Pottery blanks made of clay are selected and fired at 1100 to 1200°C. The content of flux components in the glaze formula is increased, with calcium fluoride increased to 0.3 to 0.5 parts and lithium carbonate increased to 0.2 to 0.3 parts, to lower the melting temperature of the glaze. Glazing and firing are carried out according to the above preparation method, with the firing temperature controlled at 1250 to 1300°C. After firing, the surface of the pottery exhibits directional copper crystal textures and a warm ochre-red hue.

[0052] The following detailed description is based on specific embodiments.

[0053] Example 1 This embodiment provides a reducing flame copper crystallization reaction glaze for daily-use ceramics and its preparation method, specifically including the following steps: Step 1: Raw Material Preparation and Pretreatment. Prepare the following basic glaze components: 20 parts silica, 5 parts alumina, 12 parts calcium oxide, 5 parts potassium oxide, 2 parts sodium oxide, and 2 parts boron oxide. Prepare the copper colorant components: 1.2 parts cuprous oxide and 0.8 parts copper oxide. Prepare the magnetic nanoparticle components: 0.5 parts iron(III) oxide nanoparticles and 0.05 parts surface modifier. Prepare the nucleation conditioning components: 0.4 parts zirconium oxide and 0.2 parts titanium dioxide. Prepare the flux components: 0.3 parts calcium fluoride and 0.15 parts lithium carbonate.

[0054] The silica used is industrial-grade silica powder with a purity of 99.5% or higher, and a particle size controlled within the range of 5 to 20 micrometers. Alumina is industrial-grade alumina powder with a purity of 99% or higher, and a particle size controlled within the range of 10 to 30 micrometers. Calcium oxide is industrial-grade calcium carbonate powder with a purity of 95% or higher, which decomposes into calcium oxide during the firing process. Potassium oxide and sodium oxide are industrial-grade potassium feldspar and sodium feldspar powders with a purity of 99% or higher, respectively. Boron oxide is industrial-grade boric acid powder with a purity of 99% or higher.

[0055] Cuprous oxide is selected from industrial-grade cuprous oxide powder with a purity of 98% or higher, and the particle size is controlled within the range of 1 to 10 micrometers. Copper oxide is selected from industrial-grade copper oxide powder with a purity of 99% or higher, and the particle size is controlled within the range of 1 to 10 micrometers.

[0056] The crystallization temperature range is 1070-1130℃. The effective range for Examples 1 / 2 / 3 is achieved using magnetic nanoparticles with an average particle size of 50 nanometers and a specific saturation magnetization of 80 amperes per square kilogram. The surface modifier for the iron oxide nanoparticles is γ-aminopropyltriethoxysilane with a purity of over 98%.

[0057] Zirconia is selected from industrial-grade zirconia powder with a purity of 99% or higher, and an average particle size of 1 to 5 micrometers. Titanium dioxide is selected from industrial-grade rutile titanium dioxide powder with a purity of 99% or higher, and an average particle size of 1 to 5 micrometers.

[0058] Calcium fluoride is selected from industrial-grade calcium fluoride powder with a purity of 98% or higher. Lithium carbonate is selected from industrial-grade lithium carbonate powder with a purity of 99% or higher.

[0059] Step 2, Surface Modification Treatment. Ferric oxide nanoparticles were mixed with γ-aminopropyltriethoxysilane and ultrasonically dispersed in anhydrous ethanol for 50 minutes. The ultrasonic dispersion was performed using an ultrasonic cleaner with a power of 200 watts and a frequency of 40 kHz. After dispersion, the nanoparticles were vacuum-dried at 90°C for 5 hours to obtain surface-modified magnetic nanoparticles for later use. The purpose of the surface modification treatment is to form a uniform silane coupling agent film on the surface of the ferric oxide nanoparticles, enhancing their dispersibility and interfacial bonding in the glaze melt.

[0060] Step 3: Glaze Preparation. Accurately weigh each component according to the preset weight percentage formula. First, mix the basic glaze components evenly. Then, add the copper colorant component and the crystal nucleation regulating component, mixing thoroughly. Next, add the flux component, and finally add the surface-modified magnetic nanoparticles. Mix using ball milling for 2 hours until homogeneous. During mixing, control the humidity below 55% to prevent the magnetic nanoparticles from becoming damp and agglomerating.

[0061] Step four: Glaze melting. The uniformly mixed glaze is placed in an alumina crucible and melted at 1400℃ for 3 hours, during which nitrogen gas is introduced at a flow rate of 2 liters per minute to prevent oxidation. After melting, the glaze melt is rapidly cooled to room temperature to obtain a vitreous glaze. During the melting process, the glaze undergoes a melting reaction, forming a homogeneous glassy phase.

[0062] Step 5: Glaze ball milling. The cooled vitreous glaze is crushed to a particle size of less than 100 micrometers, and then wet-milled until a fineness of 325 mesh or higher is achieved, yielding a glaze slurry for later use. During ball milling, the solid content is controlled at 65%, and the milling time is 36 hours. Zirconia ball milling media are used, with a mass ratio of ball milling media to glaze of 2:1.

[0063] Step Six: Ceramic Body Preparation. A round plate, 10 cm in diameter and 8 cm in height, is selected from a kaolin-quartz-feldspar ceramic body. The surface of the body is clean and free of contaminants, with a moisture content controlled below 0.8%. The body is dried at 120℃ for 2 hours before glazing.

[0064] Step 7, Glazing. Apply glaze slurry to the surface of the ceramic body using an immersion glazing method, controlling the glaze layer thickness to 1.0 mm. After glazing, dry at 100℃ for 2 hours.

[0065] Step 8, Reducing Flame Firing. Place the glazed ceramic body in an electric kiln and fire according to the following temperature curves: Heating from room temperature to 300℃ at a rate of 4℃ per minute, holding for 45 minutes; heating from 300 to 600℃ at a rate of 6℃ per minute, holding for 45 minutes; heating from 600 to 900℃ at a rate of 4℃ per minute, holding for 45 minutes; heating from 900 to 1280℃ at a rate of 2.5℃ per minute, holding for 90 minutes; holding from 1280℃ to 1320℃ for 120 minutes, with the firing temperature controlled at 1320℃. During the holding stage from 1280℃ to 1320℃, a reducing atmosphere is introduced. The reducing gas is a mixture of hydrogen and air, with a hydrogen to air volume ratio of 1:4, and the oxygen content is controlled within 1%.

[0066] Step Nine, Cooling and Crystallization Stage Control. After the firing and holding period, the cooling process begins. When the temperature reaches the copper crystal precipitation temperature range, an alternating magnetic field of a specific frequency is applied. The specific control is as follows: the cooling rate is controlled at 2°C per minute; when the temperature drops to 1100°C, the alternating magnetic field application device is activated. The frequency of the alternating magnetic field is controlled at 200 Hz, and the magnetic field strength is controlled at 0.8 Tesla. The alternating magnetic field is applied in a pulsed manner, with a pulse width of 0.5 seconds and a pulse interval of 2 seconds. The alternating magnetic field is applied for a duration covering the entire copper crystal precipitation temperature range, i.e., 1100 to 1050°C, and held for 60 minutes.

[0067] Step 10: Cool to room temperature. After completing the crystallization stage control, continue cooling to room temperature at a rate of 3°C per minute. The resulting product is a daily-use ceramic item with directional copper crystal texture.

[0068] The daily-use ceramic product prepared in this embodiment exhibits a streamlined, oriented copper crystal texture on its surface, with the texture direction aligned with the magnetic field direction. Under natural light, it displays a soft red hue, with hue values ​​of R200 for red, G120 for green, and B80 for blue. When light shines from different angles, the glaze displays anisotropic optical effects, creating a layered effect of light and shadow variations. The glaze has a gloss level of 85 and a Mohs hardness of 6.

[0069] Example 2 This embodiment provides another reducing flame copper crystallization reaction glaze for daily-use ceramics and its preparation method, which differs from Example 1 in that: The magnetic nanoparticle component, consisting of iron oxide nanoparticles with an average particle size of 30 nanometers, is prepared at a content of 0.3 parts. The surface modifier is γ-methacryloyloxypropyltrimethoxysilane, prepared at a content of 0.03 parts.

[0070] The alternating magnetic field was applied continuously at a frequency of 100 Hz and a magnetic field strength of 0.5 Tesla. The temperature was maintained at 1050 to 1150 °C for 90 minutes.

[0071] The other steps and parameters are the same as in Example 1.

[0072] The daily-use ceramic products prepared in this embodiment exhibit a finer, streamlined, oriented copper crystal texture on the surface. The orientation is slightly lower than that in Example 1, but the glaze is smoother and more even. The hue values ​​are red R195, green G115, and green B75.

[0073] Example 3 This embodiment provides another type of reducing flame copper crystallization reaction glaze for daily-use ceramics and its preparation method, which differs from Example 1 in that: The magnetic nanoparticle component, consisting of magnetite nanoparticles with an average particle size of 80 nanometers, is prepared at a content of 0.8 parts. The surface modifier is octyltriethoxysilane, prepared at a content of 0.08 parts.

[0074] The alternating magnetic field was applied at a frequency of 400 Hz and a magnetic field strength of 1.2 Tesla. The temperature was maintained at 1080 to 1020 °C for 45 minutes.

[0075] The other steps and parameters are the same as in Example 1.

[0076] The daily-use ceramic products prepared in this embodiment exhibit a distinct streamlined directional copper crystal texture on their surface, with a high degree of orientation. The hue values ​​are red R210, green G130, and B85.

[0077] Example 4 This embodiment provides another type of reducing flame copper crystallization reaction glaze for daily-use ceramics and its preparation method, which differs from Example 1 in that: Cobalt ferrite nanoparticles were used instead of iron tetroxide nanoparticles for the magnetic nanoparticle component. The average particle size of the cobalt ferrite nanoparticles was 60 nm, and the content was 0.6 parts. γ-aminopropyltriethoxysilane was used as the surface modifier, and the content was 0.06 parts.

[0078] The alternating magnetic field was applied at a frequency of 300 Hz and a magnetic field strength of 1.0 Tesla. It was held at a temperature between 1050 and 1150 °C for 75 minutes.

[0079] The other steps and parameters are the same as in Example 1.

[0080] The surface of the daily-use ceramic product obtained in this embodiment exhibits a streamlined, directional copper crystal texture. The hue values ​​are red R190, green G110, and B70.

[0081] Example 5 This embodiment provides a reducing flame copper crystallization reaction glaze for use in daily stoneware and its preparation method, which differs from Embodiment 1 in that: The basic glaze composition was adjusted to: 19 parts silica, 4 parts alumina, 14 parts calcium oxide, 4 parts potassium oxide, 2.5 parts sodium oxide, and 2.5 parts boron oxide. The calcium oxide content was increased, and the silica content was decreased to suit the firing temperature range of the stoneware body.

[0082] The ceramic body is made of stoneware using a clay-quartz-feldspar system, and the firing temperature of the body is 1230℃.

[0083] The firing temperature is controlled at 1300℃, the volume ratio of reducing gas to air is 1:3.5, and the oxygen content is controlled within the range of 1.5%.

[0084] The alternating magnetic field was applied at a frequency of 250 Hz with a magnetic field strength of 0.9 Tesla. The temperature was maintained at 1050 to 1150 °C for 70 minutes.

[0085] The other steps and parameters are the same as in Example 1.

[0086] The daily-use stoneware product obtained in this embodiment exhibits a radially oriented copper crystal texture on its surface, radiating outwards from the center. The hue values ​​are red R185, green G105, and green B65, with the red hue being deeper and richer. The glaze gloss level is 80 degrees.

[0087] Example 6 This embodiment provides a reducing flame copper crystallization reaction glaze for daily-use pottery and its preparation method, which differs from Example 1 in that: The basic glaze composition was adjusted to: 17 parts silica, 3.5 parts alumina, 10 parts calcium oxide, 6 parts potassium oxide, 3 parts sodium oxide, and 2.5 parts boron oxide. The flux components were increased to include 0.4 parts calcium fluoride and 0.25 parts lithium carbonate to lower the glaze's melting temperature.

[0088] The ceramic body is made of clay and fired at 1150℃.

[0089] The firing temperature is controlled at 1280℃, the volume ratio of reducing gas to air is 1:5, and the oxygen content is controlled within 2%.

[0090] The alternating magnetic field was applied at a frequency of 150 Hz and a magnetic field strength of 0.6 Tesla. It was held at a temperature between 1050 and 1150 °C for 80 minutes.

[0091] The other steps and parameters are the same as in Example 1.

[0092] The daily-use ceramic products prepared in this embodiment exhibit directional copper crystal textures on their surface. The hue values ​​are red R175, green G95, B60, presenting a warm ochre-red tone. The glaze gloss is 75 degrees.

[0093] Example 7 This embodiment provides a reducing flame copper crystallization reaction glaze using a rotating magnetic field and its preparation method, which differs from Example 1 in that: The alternating magnetic field application device employs a rotating magnetic field generator, comprising two sets of mutually perpendicular electromagnetic coils. The electromagnetic coils are made of hollow copper tubing and are wound around the firing chamber of the kiln, with 100 turns per coil.

[0094] The rotating magnetic field is achieved by alternately passing alternating currents with a 90-degree phase difference through two sets of mutually perpendicular electromagnetic coils. The frequency of the alternating current is 200 Hz, and the magnetic field strength is 0.8 Tesla. The rotation speed of the magnetic field is controlled at 30 revolutions per minute.

[0095] Keep warm at 1050 to 1150℃ for 60 minutes.

[0096] The other steps and parameters are the same as in Example 1.

[0097] The daily-use ceramic product obtained in this embodiment exhibits a radially oriented copper crystal texture on its surface, with the texture radiating outwards from the center in a radial pattern. The hue values ​​are red R200, green G125, and B82.

[0098] Example 8 This embodiment provides a reducing flame copper crystallization reaction glaze with added auxiliary colorant and its preparation method, which differs from Example 1 in that: 0.05 parts of cobalt oxide are added to the glaze formula as an auxiliary colorant, which works synergistically with copper ions to adjust the glaze color. The cobalt oxide used is industrial-grade cobalt oxide powder with a purity of over 99% and an average particle size of 1 to 5 micrometers.

[0099] 0.15 parts of tin oxide are added as a crystallization inhibitor to regulate the growth rate of copper crystals and prevent excessive crystal growth from affecting the glaze gloss. The tin oxide used is industrial-grade tin oxide powder with a purity of over 99% and an average particle size of 1 to 5 micrometers.

[0100] The other steps and parameters are the same as in Example 1.

[0101] The daily-use ceramic products prepared in this embodiment exhibit streamlined directional copper crystal textures on the surface, with a more subdued color tone. The color tone values ​​are red R180, green G100, and B60.

[0102] Comparative Example 1 This comparative example provides a reducing flame copper red glaze without the addition of magnetic nanoparticles and its preparation method, which differs from Example 1 in that: No magnetic nanoparticle components are added, that is, no iron oxide nanoparticles or surface modifiers are added.

[0103] The other steps and parameters are the same as in Example 1.

[0104] The daily-use ceramic products prepared in this comparative example exhibit randomly distributed copper crystals on the surface, with no directional texture. The hue values ​​are red R195, green G120, and B78. The glaze gloss level is 82 degrees.

[0105] Comparative Example 2 This comparative example provides a reducing flame copper crystalline glaze without the application of an alternating magnetic field and its preparation method, which differs from Example 1 in that: No alternating magnetic field is applied during the cooling and crystallization stage; the other steps and parameters are the same as in Example 1.

[0106] The surface of the daily-use ceramic products prepared in this comparative example exhibits randomly distributed copper crystals with no directional texture. The hue values ​​are red R200, green G125, and B80.

[0107] Comparative Example 3 This comparative example provides a reducing flame copper crystalline glaze using a direct current magnetic field instead of an alternating magnetic field and its preparation method. The difference from Example 1 is that: During the cooling and crystallization stage, a direct current magnetic field was used instead of an alternating magnetic field, with a direct current magnetic field strength of 0.8 Tesla. Other steps and parameters were the same as in Example 1.

[0108] The copper crystals on the surface of the daily-use ceramic products prepared in this comparative example are randomly arranged without obvious directional texture. The hue values ​​are red R190, green G115, and green B75.

[0109] Comparative Example 4 This comparative example provides a reducing flame copper crystalline glaze using ordinary iron oxide magnetic particles instead of iron oxide nanoparticles and its preparation method. The difference from Example 1 is that: The magnetic nanoparticles used are ordinary iron oxide magnetic particles with an average particle size of 500 nanometers and a content of 0.5 parts. Ordinary iron oxide magnetic particles have low saturation magnetization and cannot generate sufficient magnetic torque.

[0110] The other steps and parameters are the same as in Example 1.

[0111] The copper crystals on the surface of the daily-use ceramic products prepared in this comparative example exhibit partial orientation, but the orientation effect is not obvious. The hue values ​​are red R185, green G110, and green B72.

[0112] Comparison of experimental data The performance comparison of the daily-use ceramic products obtained in the embodiments of the present invention and the comparative examples is shown in the table below: Orientation refers to the degree to which copper crystals align in a specific direction, determined by observation with a polarizing microscope and image analysis software. An orientation of 80% or higher indicates that the copper crystals are clearly oriented, while an orientation of less than 40% indicates that the copper crystals are randomly distributed.

[0113] As shown in the table above, the orientation of the daily-use ceramic products prepared in the embodiments of the present invention is all above 82%, significantly higher than the 12% to 35% of the comparative examples. The hue value, gloss, and hardness of Examples 1 to 8 all reach or exceed those of the comparative examples, indicating that the technical solution of the present invention achieves the directional arrangement of crystals without affecting the basic properties of the glaze.

[0114] Alternating magnetic field application device The present invention also provides a specific design for an alternating magnetic field application device, including a magnetic field generating system, a temperature control system, an atmosphere control system, and a program control system.

[0115] The magnetic field generating system includes a high-frequency generator, a power amplifier, and an electromagnetic coil. The electromagnetic coil is made of hollow copper tubing and is wound around the firing chamber of the kiln. The number of turns is determined by the kiln volume and the required magnetic field strength. The high-frequency generator produces an alternating current signal of 50 to 500 Hz. The power amplifier amplifies the signal to the required power and outputs it to the electromagnetic coil to generate an alternating magnetic field. The magnetic field strength can be controlled by adjusting the output power of the power amplifier, ranging from 0.1 to 2 Tesla.

[0116] The temperature control system includes thermocouples, a temperature display, and a controller. The thermocouples are installed inside the kiln to monitor the glaze surface temperature in real time and transmit the temperature signal to the controller. The controller controls the heating power and cooling rate of the kiln according to the preset temperature curve and the temperature requirements of the crystallization stage. It also works in conjunction with the magnetic field generation system to apply the magnetic field when the crystallization temperature range is reached.

[0117] The atmosphere control system includes gas flow meters, a gas mixing device, and atmosphere control valves. The gas flow meters precisely control the flow ratio of reducing gas and air, thereby achieving precise control of the oxygen content within the kiln. The reducing gas can be hydrogen, carbon monoxide, or natural gas, which are mixed in the mixing device after their flow rates are controlled by different gas flow meters before being introduced into the kiln.

[0118] The programmable control system employs a programmable logic controller (PLC) or an industrial computer to achieve coordinated control of temperature profiles, atmosphere, and magnetic field application. The system stores preset firing profiles and crystallization control parameters, and automatically adjusts the operating status of each system based on actual temperature and atmosphere feedback signals.

[0119] As a specific implementation method, the magnetic field generating system can also use a rotating magnetic field generating device, which includes two sets of mutually perpendicular electromagnetic coils and a high-frequency phase controller. The rotation of the magnetic field is achieved by adjusting the phase difference of the currents in the two sets of coils.

[0120] Alternatively, the temperature control system can be equipped with multiple thermocouples, which are set in different locations in the kiln to achieve precise monitoring and control of the temperature distribution.

[0121] In another embodiment, the program control system may also be equipped with a touch screen human-machine interface to facilitate operators in setting and adjusting firing parameters.

[0122] The above embodiments and comparative data demonstrate that the specific implementation of the present invention has described the technical solution of the present invention in detail, including various embodiments and comparative examples, showcasing the significant effects of the present invention in crystal orientation control. Those skilled in the art can implement the technical solution of the present invention based on the description in this specification without departing from the spirit and scope of the present invention.

Claims

1. A reducing flame copper crystallization reaction glaze for daily-use ceramics, characterized in that, The product comprises, by weight percentage, the following components: a base glaze component comprising 15 to 25 parts silica, 3 to 8 parts alumina, 8 to 15 parts calcium oxide, 3 to 7 parts potassium oxide, 1 to 4 parts sodium oxide, and 1 to 3 parts boron oxide; a copper colorant component comprising 0.5 to 2 parts cuprous oxide and 0.3 to 1.5 parts copper oxide; a magnetic nanoparticle component comprising 0.1 to 1 part magnetite nanoparticles with a particle size of 30 to 80 nanometers and 0.01 to 0.1 parts surface modifier composed of a silane coupling agent or a titanate coupling agent, wherein the surface modifier is used to improve the dispersibility of magnetite nanoparticles in the glaze melt and prevent high-temperature agglomeration; a nucleation regulating component comprising 0.1 to 0.8 parts zirconium oxide and 0.05 to 0.5 parts titanium dioxide; and a flux component comprising 0.1 to 0.5 parts calcium fluoride and 0. 0.5 to 0.3 parts; wherein, the iron oxide nanoparticles lose their ferromagnetism during the glaze melting stage due to exceeding their Curie temperature; during the cooling process after firing in a reducing flame at a temperature of 1280 to 1350°C, with a volume ratio of reducing gas to air of 1:3 to 1:5 and an oxygen content of 0.5 to 2%, the magnetic responsiveness is restored when the temperature drops to 1070 to 1130°C; within this temperature range, an alternating magnetic field with a frequency of 100 to 400 Hz and an intensity of 0.5 to 1.5 Tesla is applied and held for 45 to 90 minutes, utilizing the synergistic effect of magnetocaloric effect and magnetic torque to drive the copper crystals to oriented along the direction of the magnetic field, so that the orientation of the copper crystals on the glaze surface after firing reaches more than 82%; the surface of the daily-use ceramics after firing exhibits streamlined oriented copper crystal texture or radial oriented copper crystal texture, and presents anisotropic optical effects under different angles of light.

2. The reducing flame copper crystallization reaction glaze as described in claim 1, characterized in that: In the magnetic nanoparticle component, the surface modifier is selected from one or more of silane coupling agents, titanate coupling agents, stearic acid, octyltriethoxysilane, or methyltrimethoxysilane.

3. The reducing flame copper crystallization reaction glaze as described in claim 1, characterized in that: The copper colorant component also includes 0.01 to 0.1 parts of cobalt oxide as an auxiliary colorant, which works synergistically with copper ions to adjust the glaze color tone.

4. The reducing flame copper crystallization reaction glaze as described in claim 1, characterized in that: It also includes 0.05 to 0.3 parts of tin oxide as a crystallization inhibitor to regulate the growth rate of copper crystals.

5. An alternating magnetic field application device for a reducing flame copper crystallization reaction glaze according to any one of claims 1 to 4, characterized in that, include: The magnetic field generating system includes a high-frequency generator, a power amplifier, and an electromagnetic coil wound around the firing chamber of the kiln, used to generate an alternating magnetic field with a frequency of 50 to 500 Hz and an intensity of 0.1 to 2 T. The temperature control system includes thermocouples and controllers installed inside the kiln, which are used to monitor the glaze surface temperature in real time and activate the magnetic field when the temperature reaches the range of copper crystal precipitation. The atmosphere control system, including a gas flow meter and a gas mixing device, is used to precisely control the volume ratio of reducing gas to air in the kiln to be 1:3 to 1:5 and the oxygen content to be 0.5% to 2%. The programmable control system is used to achieve the linkage control of temperature profile, atmosphere control, and magnetic field application.

6. The alternating magnetic field applying device as described in claim 5, characterized in that: The magnetic field generating system employs a rotating magnetic field generating device, comprising two sets of mutually perpendicular electromagnetic coils and a high-frequency phase controller. The magnetic field rotation is achieved by passing alternating currents with a 90° phase difference to the two sets of coils, which is used to obtain radial or concentric directional copper crystal textures.

7. A method for controlling the directional arrangement of copper crystals in a reducing flame copper crystallization reaction glaze, characterized in that, The reactive glaze contains 0.1 to 1 part of iron oxide nanoparticles with a particle size of 30 to 80 nanometers, which are surface-modified with silane coupling agents or titanate coupling agents. The iron oxide nanoparticles lose their ferromagnetism during the melting stage of the glaze because they exceed their Curie temperature. During the cooling process after the glaze is fired in a reducing flame at a temperature of 1280 to 1350°C, with a volume ratio of reducing gas to air of 1:3 to 1:5 and an oxygen content of 0.5 to 2%, the iron oxide nanoparticles regain their magnetic responsiveness when the temperature drops to 1070 to 1130°C. At this time, an alternating magnetic field with a frequency of 100 to 400 Hz and an intensity of 0.5 to 1.5 Tesla is applied and held at this temperature for 45 to 90 minutes. The synergistic effect of magnetocaloric effect and magnetic torque drives the copper crystals to align in the direction of the magnetic field, so that the orientation of the copper crystals on the glaze surface after firing reaches more than 82%.

8. The method as described in claim 7, characterized in that: The alternating magnetic field is applied in a pulsed manner, with a pulse width of 0.1 to 1 second and a pulse interval of 0.5 to 5 seconds; or it can be applied continuously.

9. The application of a reducing flame copper crystallization reaction glaze as described in any one of claims 1 to 3 in the preparation of daily-use ceramic decorative products with anisotropic optical effects.

10. A reducing flame copper crystallization reaction glaze with magnetic response detection function, characterized in that: In the glaze according to any one of claims 1 to 4, the iron oxide nanoparticles of the magnetic nanoparticle component retain some magnetic responsiveness after firing in a reducing flame, so that the fired glaze surface can be identified by an external magnetic field at room temperature; the orientation of the copper crystals in the glaze surface reaches more than 82%, exhibiting anisotropic optical effects under different angles of light; the glaze surface has both decorative and magnetic feature identification functions, and can be applied to the fields of anti-counterfeiting labels or intelligent decoration.