Additive and method for stabilizing the color of ceramic glaze during firing

Abstract

The present invention relates to the technical field of ceramic glaze preparation, and discloses an additive for stabilizing the color development during firing of ceramic glaze and a method thereof. The additive comprises 20-30 parts of magnesium oxide, 15-20 parts of zinc oxide, 5-10 parts of tin oxide, 10-15 parts of sodium phosphate, 3-5 parts of rare earth oxide, 3-5 parts of layered double hydroxide, 0.5-1.2 parts of upconversion luminescent nanoparticles, 2-3 parts of a magnetic composite medium, and 5-8 parts of nano-barium titanate. The additive achieves directional alignment of SnO2 grains by magnetic field induction of an Fe3O4@SiO2 core-shell structure, combines with the gradient release of rare earth ions by layered double hydroxide, and utilizes a microwave-magnetic-field-laser multi-physics field coupled gradient firing process to significantly improve the specular reflectivity and optical uniformity of the glaze surface, inhibit the decomposition of pigments and the generation of grain boundary defects at high temperatures, and simultaneously improves color development stability and energy efficiency. The additive solves the problem of glaze performance degradation caused by light scattering misalignment, rare earth chelation failure, and thermal field regulation lag caused by disordered grain arrangement in traditional processes.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic glaze preparation, in particular to an additive for stabilizing the color development of ceramic glaze during firing and a method thereof. Background Art

[0002] Controlling the high-temperature color development of ceramic glazes is a core technical challenge hindering the improvement of high-end ceramic product quality. The core challenge lies in achieving the synergistic optimization of color stability, glaze optical properties, and energy efficiency during high-temperature firing. Existing technologies primarily improve color development through the combined application of rare earth element chelates and photorefractive modifiers. However, industrial production still faces the following key bottlenecks:

[0003] The existing glaze system relies on the simple compounding of zinc oxide and tin oxide to achieve light refraction adjustment. Due to the significant difference in thermal expansion coefficients between the two (ZnO: 5.0×10 -8 / ℃vsSnO2:4.2×10 -8 / °C), stress concentration within the glaze during high-temperature stages leads to a microcrack rate as high as 7-12%. Furthermore, the mechanical mixing process cannot control the orientation of the SnO2 grains. The disordered arrangement of the grains causes a light scattering angle dispersion greater than 15°, limiting the glaze's specular reflectivity to a range of 85-90% for a long time, making it difficult to meet the uniform light transmission requirements of precision optical ceramics.

[0004] In terms of color stability control, conventional technology directly adds 3-5% lanthanum oxide as a rare earth stabilizer, but in the molten state of the glaze layer, the free La 3+ The ions quickly aggregate due to the lack of space isolation carriers, forming inactive LaPO4 compounds. When the temperature exceeds 1250℃, La 3+ Co 2+ / Fe 3+ The chelation efficiency of the glaze decreases by over 60%, resulting in color difference ΔE fluctuations exceeding 15%. Furthermore, the existing firing process uses a single thermal field gradient to control the temperature, resulting in a temperature difference of >50°C between the inside and outside of the glaze layer. This forces the holding time to be extended to over 2 hours to compensate for thermal hysteresis, which not only results in high energy consumption of 15-18kW·h / kg per unit, but also exacerbates pigment volatilization losses due to local overfiring.

[0005] The root cause of these problems lies in the disconnect between existing technologies' understanding of the synergistic mechanisms of material microstructure control and energy field coordination. Glaze component design remains limited to the physical overlay of functional materials, failing to develop a systematic solution from nanoscale orientation control to macroscopic thermal field response. Firing processes also isolate temperature and chemical reaction fields, failing to develop dynamic control pathways that couple multiple physical fields. These shortcomings have severely hampered breakthroughs in high-temperature color stability, optical performance, and energy efficiency in ceramic glazes. Summary of the Invention

[0006] In response to the deficiencies of the prior art, the present invention provides an additive and method for stabilizing the color of ceramic glazes during firing, which solves the problems of poor color stability, deterioration of glaze optical properties, and low energy efficiency during high-temperature firing of ceramic glazes.

[0007] To achieve the above object, the present invention is implemented by the following technical solution: an additive for stabilizing the color of ceramic glaze during firing, comprising the following components by weight percentage:

[0008] 20-30 parts of magnesium oxide, 15-20 parts of zinc oxide, 5-10 parts of tin oxide, 10-15 parts of sodium phosphate, 3-5 parts of rare earth oxide, 3-5 parts of layered double hydroxide, 0.5-1.2 parts of upconversion luminescent nanoparticles, 2-3 parts of magnetic composite medium, and 5-8 parts of nano-barium titanate.

[0009] The core innovation of this invention lies in the fact that it is not a simple physical mixing of functional components, but rather the construction of a multi-scale, multi-functional synergistic system. On a macro level, through the firing process coupled with multiple physical fields such as magnetic field, microwave field, and laser field, the overall thermodynamic and kinetic processes of the glaze layer can be precisely controlled; on a micro level, by designing nano-functional materials with core-shell and layered structures, the orientation control of key crystal phases (such as SnO2) and the orientation of active ions (such as La) can be achieved. 3+ The combination of the two fundamentally resolves the contradiction between the loss of microstructure control and the lag in macroscopic energy field regulation in traditional processes.

[0010] As a high-temperature stabilizer, magnesium oxide, with its high melting point (≥2800°C), forms a rigid skeleton network in the glaze layer, which reduces the thermodynamic instability in the high-temperature range by inhibiting the migration and volatilization of pigment particles. The specific ratio of zinc oxide to tin oxide (2.5:1-3.5:1) constitutes a light refraction regulation system. The high polarizability of zinc ions and the tetragonal crystal system of tin oxide work synergistically to improve the matching degree between the glaze layer expansion coefficient and the body, effectively avoiding microcracks caused by thermal stress mismatch. Sodium phosphate is used as a mineralizer, and its decomposition produces PO4 3-Ions can eliminate microbubbles on the glaze surface and promote the dispersion of pigment particles, avoiding local color concentration deviations. The addition of upconversion luminescent nanoparticles provides a target for subsequent photoactivation treatment. The particles can undergo energy upconversion under the excitation of near-infrared lasers of specific wavelengths. This energy conversion process can act precisely on the glaze surface, and without significantly increasing the macroscopic temperature, it can locally stimulate the activity of pigment ions or promote early interfacial reactions between the glaze and the body, laying an excellent interface foundation for subsequent high-temperature firing. Nano-barium titanate, as an efficient microwave absorption medium, has excellent dielectric loss properties under microwave fields, which is the key to achieving the "microwave-assisted heating" in the S4 step and achieving the "body heating" effect of the glaze layer, thereby effectively reducing the temperature difference between the inside and outside of the glaze layer and avoiding over-burning of the surface.

[0011] The combined use of rare earth oxides and layered double hydroxides creates a spatiotemporal gradient release mechanism. For example, the Fe3O4@SiO2 core-shell structure (core 180-220nm, shell 8-12nm) exhibits magnetic response properties. During the glazing stage, an external magnetic field induces the alignment of tin oxide grains along the

[001] axis (orientation ≥ 92%), while the SiO2 shell prevents the Fe3O4 core from oxidizing and failing at high temperatures. This structure increases the specular reflectivity of the glaze from the conventional 92% to 96.5%, while simultaneously controlling the light scattering angle to within ±5°, achieving single-crystal-like optical uniformity.

[0012] Preferably, the purity of the magnesium oxide is ≥99.5%, and the particle size distribution D50 is 0.5-2 μm, and the mass ratio of the zinc oxide to the tin oxide is 2.5:1 to 3.5:1.

[0013] Preferably, the mass ratio of the sodium phosphate to the rare earth oxide is 2.5:1 to 3.5:1, and the rare earth oxide is lanthanum oxide.

[0014] Preferably, the magnetic composite medium is a Fe3O4@SiO2 core-shell structure, wherein:

[0015] Fe3O4 core diameter 180-220nm;

[0016] SiO2 shell thickness 8-12nm;

[0017] Saturation magnetization 45-50emu / g.

[0018] Preferably, the layered double hydroxide is Mg6Al2(OH) 16 CO3·4H2O, the upconversion luminescent nanoparticles are Eu 3+ Doped NaYF4:Yb,Er.

[0019] The present invention also provides a method for stabilizing the color development of ceramic glazes by firing, using the above-mentioned additive, comprising the following steps:

[0020] S1. Preparation of additives: After screening and rare earth loading, the components are mixed and ball-milled until D90 ≤ 2 μm to obtain the additives;

[0021] S2. Preparation of glaze: Add the additive obtained in S1 at 5-8% of the base glaze, and fully mix with the colorant using an ultrasonic dispersing device to obtain a glaze;

[0022] S3, magnetic field-assisted glazing: applying the glaze obtained in S2 to the surface of the ceramic body, applying a 0.3-0.5T transverse magnetic field during the glazing process, and simultaneously performing a photoactivation treatment to obtain a glazed ceramic body;

[0023] S4, gradient field firing: The glazed ceramic body obtained in S3 is fired using gradient temperature control to obtain a ceramic product.

[0024] The above method steps constitute a systematic process that is interconnected and progressive. The rare earth loading and fine ball milling of S1 ensure the uniform dispersion and functional presetting of each functional component at the microscopic scale; the ultrasonic dispersion of S2 ensures the uniformity of the additives in the macroscopic glaze slurry system; the magnetic field-assisted glazing of S3 is one of the key steps of the present invention. It uses the magnetic responsiveness of the additives to pre-arrange the microstructure of the glaze layer before the glaze is fired, which is the basis for achieving the final optical performance; the simultaneous light activation optimizes the glaze interface; finally, the gradient field firing process of S4, through a staged and multi-physical field collaborative approach, accurately matches the physical and chemical changes of the glaze in different temperature ranges, thereby achieving efficient and high-quality firing effects.

[0025] Preferably, in step S1, zirconia balls and Fe3O4@SiO2 magnetic media are used for ball milling, with a ball-to-material ratio of 2:1, and a 0.3T pulsed magnetic field is applied with a frequency of 10-15 Hz.

[0026] Preferably, the light activation treatment in step S3 uses a 980-1000 nm laser with a power density of 2-3 W / cm 2 , scanning speed 5-8mm / s.

[0027] Preferably, the gradient temperature-controlled firing in step S4 includes microwave-assisted heating, magnetic field-coordinated heat preservation, and pulsed laser crystallization strengthening.

[0028] Preferably, the gradient temperature controlled firing in the S4 step comprises the following steps:

[0029] Stage 1: Starting from room temperature, microwave-assisted heating was performed at a rate of 8-12°C / min to 600°C;

[0030] The second stage: continue heating from 600℃ to 1250℃ at a rate of 4-5℃ / min;

[0031] The third stage: magnetic field coordinated heat preservation between 1250℃ and 1300℃ for 40-60min;

[0032] The fourth stage: the temperature is raised from 1300°C to 1320°C at a rate of 2-3°C / min. During this stage, a pulsed laser with a wavelength of 1064-1080nm is applied for crystallization strengthening treatment, and the single pulse energy is 0.8-1.2mJ.

[0033] Microwave-assisted heating stage (8-12°C / min): Utilizing the dielectric loss effect of nano-barium titanate (tanδ≥0.1), a local hot spot is generated under a 2.45GHz microwave field, so that the temperature difference between the inside and outside of the glaze layer is less than 15°C, avoiding surface overburning caused by traditional radiation heating.

[0034] Magnetic field synergistic heat preservation stage (0.4-0.6T): The directional magnetic field causes the rare earth ions in the layered double hydroxide loaded rare earth ions to migrate along the direction of the magnetic field line and react with the pigment metal ions (Co 2+ / Fe 3+ ) forms a strongly bonded chelate (binding energy ≥ 150kJ / mol), reducing the pigment decomposition rate at 1300°C from the conventional 20% to below 5%.

[0035] Pulsed laser crystallization strengthening: For example, short-pulse width (5-8ms) high-energy laser triggers a localized plasma effect on the glaze surface, prompting a non-equilibrium phase transition at the SnO2 grain boundary, forming a densified recrystallization layer (porosity ≤ 0.1%), and significantly improving the mechanical strength of the glaze surface (Vickers hardness ≥ 650HV).

[0036] The present invention provides an additive and method for stabilizing the color development of ceramic glaze during firing. It has the following beneficial effects:

[0037] 1. The present invention achieves the technical effect of orderly arrangement of SnO2 grains in the glaze layer by adopting the technical solution of Fe3O4@SiO2 core-shell structure and magnetic field coordinated orientation. Compared with the existing solution that simply relies on mechanical mixing to achieve dispersion, it solves the defects of reflectivity fluctuation and uncontrolled light scattering caused by random grain orientation.

[0038] 2. The present invention achieves a breakthrough in the chelation stability of pigments in the high-temperature stage through the gradient release technology of layered double hydroxide loaded rare earth ions. Compared with the extensive mode of directly adding rare earth oxides in the existing technology, it overcomes the technical bottlenecks of rare earth ion agglomeration failure and local color difference expansion at high temperature.

[0039] 3. The present invention adopts a gradient firing technology solution of microwave-magnetic field-laser multi-physical field coupling to achieve the coordinated optimization of glaze layer densification and energy consumption control. Compared with the traditional single thermal field temperature control process, it breaks through the industry problem of large melting difference between the inside and outside of the glaze layer and serious energy waste caused by heat conduction lag. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Flowchart of the method of the present invention. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Please see the attached Figure 1 The present invention provides an additive and method for stabilizing the color of ceramic glazes during firing through multiple embodiments, the specific contents of which are as follows: Example 1:

[0043] S1. Preparation of additives:

[0044] Weigh the components: Accurately weigh the following components in parts by weight:

[0045] Magnesium oxide (purity ≥ 99.5%, D50 ≈ 1.2 μm): 25 parts;

[0046] Zinc oxide: 18 parts;

[0047] Tin oxide: 6 parts (make sure the mass ratio of zinc oxide to tin oxide is 3:1);

[0048] Sodium phosphate: 12.5 parts;

[0049] Rare earth oxide (lanthanum oxide): 4.2 parts (ensure the mass ratio of sodium phosphate to lanthanum oxide is approximately 3:1);

[0050] Layered double hydroxide (Mg6Al2(OH) 16 CO3·4H2O): 4 parts;

[0051] Upconversion luminescent nanoparticles (Eu 3+ Doped NaYF4:Yb,Er):0.8 parts;

[0052] Magnetic composite medium (Fe3O4@SiO2 core-shell structure, Fe3O4@ core diameter ≈ 200nm, SiO2 shell thickness ≈ 10nm, saturation magnetization intensity ≈ 48emu / g): 2.5 parts;

[0053] Nano-barium titanate: 6.5 parts;

[0054] Rare earth loading: First, 4.2 parts of lanthanum oxide and 4 parts of layered double hydroxide were placed in anhydrous ethanol, mixed by mechanical stirring and ultrasonic-assisted dispersion for 30 minutes, and then vacuum dried at 60°C to obtain a lanthanum oxide-loaded layered double hydroxide composite powder.

[0055] Mixing and ball milling: The composite powder obtained above is placed in a ball mill together with the remaining powdered components such as magnesium oxide, zinc oxide, tin oxide, sodium phosphate, upconversion luminescent nanoparticles, nano-barium titanate, etc., which have been sieved through a 200-mesh sieve, and a magnetic composite medium. Zirconia balls and additional Fe3O4@SiO2 magnetic media are added as grinding media, and the ball-to-material ratio is controlled at 2:1. During the ball milling process, a pulsed magnetic field of 0.3T is applied, and the pulse frequency is set to 12Hz. Wet ball milling is performed until the particle size distribution D90 of the mixed material is ≤2μm to obtain an additive slurry, which is subsequently dried to obtain a powdered additive.

[0056] S2. Preparation of glaze:

[0057] For every 1000 parts by weight of the base glaze, add 65 parts by weight (i.e., 6.5% of the base glaze weight) of the additive powder prepared in S1. Place the mixture in a container and process it using an ultrasonic dispersing device until the additive and colorant are evenly dispersed in the base glaze, yielding the final functional glaze.

[0058] S3, magnetic field assisted glazing:

[0059] The glaze prepared in S2 is evenly applied to the surface of the ceramic body by dipping or spraying. During the entire glazing process, a constant transverse magnetic field with an intensity of 0.4T is applied to the side of the body. At the same time, a laser with a wavelength of 990nm is used to scan the glaze surface with a laser power density of 2.5W / cm 2 , the scanning speed was 6.5 mm / s, and the photoactivation treatment was performed to obtain a glazed ceramic body.

[0060] S4, gradient field firing:

[0061] The glazed ceramic body obtained in S3 is placed in a dedicated kiln and fired according to the following gradient temperature control program:

[0062] The first stage: starting from room temperature, microwave-assisted heating was performed to 600 °C at a heating rate of 10 °C / min.

[0063] The second stage: continue heating from 600℃ to 1250℃ at a heating rate of 4.5℃ / min.

[0064] The third stage: magnetic field coordinated heat preservation between 1250℃ and 1300℃, and the heat preservation time is 50 minutes.

[0065] Stage 4: The temperature is raised from 1300°C to 1320°C at a rate of 2.5°C / min. During this stage, a pulsed laser with a wavelength of 1072nm is applied for crystallization and strengthening, with a single pulse energy of 1.0mJ. After firing, the furnace is cooled, resulting in a ceramic product with a stable color. Example 2:

[0066] S1. Preparation of additives:

[0067] Weigh the components: Accurately weigh the following components in parts by weight:

[0068] Magnesium oxide (purity ≥ 99.5%, D50 ≈ 0.5 μm): 20 parts;

[0069] Zinc oxide: 15 parts;

[0070] Tin oxide: 6 parts (ensure the mass ratio of zinc oxide to tin oxide is 2.5:1);

[0071] Sodium phosphate: 10 parts;

[0072] Rare earth oxide (lanthanum oxide): 4 parts (ensure the mass ratio of sodium phosphate to lanthanum oxide is 2.5:1);

[0073] Layered double hydroxide (Mg6Al2(OH) 16 CO3·4H2O): 3 parts;

[0074] Upconversion luminescent nanoparticles (Eu 3+ Doped NaYF4: Yb, Er): 0.5 parts;

[0075] Magnetic composite medium (Fe3O4@SiO2 core-shell structure, Fe3O4 core diameter ≈ 180nm, SiO2 shell thickness ≈ 8nm, saturation magnetization intensity ≈ 45emu / g): 2 parts;

[0076] Nano-barium titanate: 5 parts;

[0077] Rare earth loading: First, 4 parts of lanthanum oxide and 3 parts of layered double hydroxide were pretreated and compounded by wet mechanochemical method to obtain loaded composite powder.

[0078] Mixing and ball milling: The pre-loaded composite powder, along with the other sieved powdered components and the magnetic composite medium, was placed in a ball mill. The milling process was performed using the same method as in Example 1, except that the pulsed magnetic field frequency was set to 10 Hz. After ball milling, the additive powder was dried.

[0079] S2. Preparation of glaze:

[0080] Based on 1000 parts by weight of the basic glaze, 50 parts by weight (i.e., 5% of the weight of the basic glaze) of the additive powder prepared in S1 were added and uniformly dispersed by ultrasonication.

[0081] S3, magnetic field assisted glazing:

[0082] During the glazing process, a constant transverse magnetic field with an intensity of 0.3 T was applied. At the same time, a laser with a wavelength of 980 nm was used for photoactivation, and the laser power density was 2 W / cm 2 , the scanning speed is 8mm / s.

[0083] S4, gradient field firing:

[0084] The glazed ceramic body is fired according to the following gradient temperature control program:

[0085] The first stage: microwave-assisted heating to 600 °C at a rate of 8 °C / min;

[0086] The second stage: heating to 1250℃ at a rate of 4℃ / min;

[0087] The third stage: magnetic field coordinated heat preservation between 1250℃ and 1300℃ for 40min;

[0088] The fourth stage: The temperature is raised to 1320°C at a rate of 2°C / min. During this stage, a pulsed laser with a wavelength of 1064nm is applied for crystallization and strengthening, with a single pulse energy of 0.8mJ. After firing, the furnace is cooled to obtain a ceramic product. Example 3:

[0089] S1. Preparation of additives:

[0090] Weigh the components: Accurately weigh the following components in parts by weight:

[0091] Magnesium oxide (purity ≥ 99.5%, D50 ≈ 2 μm): 30 parts;

[0092] Zinc oxide: 20 parts;

[0093] Tin oxide: 5.7 parts (ensure the mass ratio of zinc oxide to tin oxide is approximately 3.5:1);

[0094] Sodium phosphate: 15 parts;

[0095] Rare earth oxide (lanthanum oxide): 4.3 parts (ensure the mass ratio of sodium phosphate to lanthanum oxide is approximately 3.5:1);

[0096] Layered double hydroxide (Mg6Al2(OH) 16 CO3·4H2O): 5 parts;

[0097] Upconversion luminescent nanoparticles (Eu 3+ Doped NaYF4:Yb,Er):1.2 parts;

[0098] Magnetic composite medium (Fe3O4@SiO2 core-shell structure, Fe3O4 core diameter ≈ 220nm, SiO2 shell thickness ≈ 12nm, saturation magnetization intensity ≈ 50emu / g): 3 parts;

[0099] Nano-barium titanate: 8 parts;

[0100] Rare earth loading: First, 4.3 parts of lanthanum oxide and 5 parts of layered double hydroxide were pretreated and compounded by wet mechanochemical method to obtain loaded composite powder.

[0101] Mixing and ball milling: The pre-loaded composite powder, along with the other sieved powdered components and the magnetic composite medium, was placed in a ball mill. The milling process was performed using the same method as in Example 1, except that the pulsed magnetic field frequency was set to 15 Hz. After ball milling, the additive powder was dried.

[0102] S2. Preparation of glaze:

[0103] Based on 1000 parts by weight of the basic glaze, 80 parts by weight (i.e., 8% of the weight of the basic glaze) of the additive powder prepared in S1 were added and uniformly dispersed by ultrasonication.

[0104] S3, magnetic field assisted glazing:

[0105] During the glazing process, a constant transverse magnetic field with an intensity of 0.5 T was applied. At the same time, a laser with a wavelength of 1000 nm was used for photoactivation, and the laser power density was 3 W / cm 2 , the scanning speed is 5mm / s.

[0106] S4, gradient field firing:

[0107] The glazed ceramic body is fired according to the following gradient temperature control program:

[0108] The first stage: microwave-assisted heating to 600 °C at a rate of 12 °C / min;

[0109] The second stage: heating to 1250℃ at a rate of 5℃ / min;

[0110] The third stage: magnetic field coordinated heat preservation between 1250℃ and 1300℃ for 60min;

[0111] The fourth stage: The temperature is raised to 1320°C at a rate of 3°C / min. During this stage, a pulsed laser with a wavelength of 1080nm is applied for crystallization and strengthening, with a single pulse energy of 1.2mJ. After firing, the furnace is cooled to obtain a ceramic product.

[0112] Comparative Examples 1-7:

[0113] Comparative Example 1:

[0114] Compared with Example 1, the difference is that: in the preparation of S1 additive, no magnetic composite medium (Fe3O4@SiO2 core-shell structure) is added;

[0115] Accordingly, no magnetic field is applied in the ball milling step S1 and the glazing step S3. The remaining components and process parameters are the same as those in Example 1.

[0116] Comparative Example 2:

[0117] Compared to Example 1, the differences are: in the preparation of additive S1, no layered double hydroxide was added, and the rare earth oxide (lanthanum oxide) was directly mixed with the other components and ball milled without any pretreatment. The remaining components and process parameters were the same as in Example 1.

[0118] Comparative Example 3:

[0119] Compared with Example 1, the difference is that the gradient field firing in step S4 is replaced with traditional single thermal field temperature-controlled firing. The specific procedure is: heating from room temperature to 1300°C at a constant rate of 5°C / min, holding for 50 minutes, and then cooling with the furnace. No microwaves, magnetic fields, or pulsed lasers are applied during the entire firing process. The remaining steps are the same as in Example 1.

[0120] Comparative Example 4:

[0121] Compared with Example 1, the difference is that in the preparation of additive S1, 2.5 parts by weight of the Fe3O4@SiO2 core-shell structure magnetic composite medium is replaced with an equal part by weight of ordinary Fe3O4 fine powder. The remaining components and process parameters are the same as those in Example 1.

[0122] Comparative Example 5:

[0123] Compared with Example 1, the difference is that in the S3 magnetic field-assisted glazing step, the simultaneous light activation treatment is omitted (ie, the 990 nm laser is not used to scan the glaze surface). The remaining steps are the same as in Example 1.

[0124] Comparative Example 6:

[0125] Compared with Example 1, the difference is that in the preparation of the S1 additive, the amount of magnesium oxide added is increased from 25 parts by weight to 35 parts by weight, exceeding the range of 20-30 parts. The remaining components and process parameters are the same as those in Example 1.

[0126] Comparative Example 7:

[0127] Compared with Example 1, the difference is that although a 0.4 T transverse magnetic field was applied during the S3 glazing process, the magnetic composite medium (Fe3O4@SiO2 core-shell structure) was not added during the S1 additive preparation, but an equal amount of tin oxide was added. The remaining components and process parameters were the same as in Example 1.

[0128] Test Example 1-5:

[0129] Test Example 1: Verification of the effectiveness of magnetic field orientation technology

[0130] Purpose of the experiment:

[0131] This experiment aimed to verify the key role of the magnetic composite medium in improving glaze uniformity and color stability through quantitative measurement of glaze gloss and color difference. By comparing the performance of samples with and without the magnetic medium, and with and without the magnetic field, this technical solution demonstrated its ability to effectively overcome the defects of reflectivity fluctuations and uncontrolled light scattering caused by random grain orientation.

[0132] Experimental samples:

[0133] Sample E1: A ceramic sample prepared according to the method of Example 1, wherein the additives include Fe3O4@SiO2 magnetic medium, and a transverse magnetic field is applied during the glazing process.

[0134] Sample C1: A ceramic sample prepared according to the method of Comparative Example 1, wherein the additive does not contain a magnetic medium and no magnetic field is applied during the glazing process.

[0135] Sample C7: a ceramic sample prepared according to the method of Comparative Example 7, wherein the additive does not contain a magnetic medium, but a transverse magnetic field is applied during the glazing process.

[0136] 3. Experimental equipment:

[0137] 60° angle handheld gloss meter (accuracy 0.1GU);

[0138] Portable integrating sphere colorimeter (D65 illuminant, 10° observer viewing angle).

[0139] Experimental steps:

[0140] Step 1: Sample pretreatment and labeling

[0141] The three prepared samples (E1, C1, and C7) were left at room temperature for 24 hours to ensure that their surfaces were completely dry and stable.

[0142] On the glaze surface of each sample, use a marker to lightly mark five points where measurements will be taken: the center point (marked 0), and four corner points (marked 1, 2, 3, 4) that are approximately equal distances from the edge.

[0143] Step 2: Glossiness test

[0144] Turn on the gloss meter and calibrate it using the standard calibration plate provided with the instrument.

[0145] Pick up sample E1 and place the measuring port of the gloss meter vertically and tightly on mark point 1. After the reading stabilizes, record the value.

[0146] Measure and record the marked points 2, 3, 4, and 0 of sample E1 in sequence.

[0147] Repeat the above steps to complete the gloss measurement and recording of all marked points of sample C1 and sample C7 respectively.

[0148] Step 3: Color difference test

[0149] Turn on the colorimeter and perform white plate calibration.

[0150] First, measure the center point of each sample (marked point 0) and record its CIELab value as the benchmark for comparing the internal color differences of the sample.

[0151] For sample E1, measure the Lab values ​​of its marked points 1, 2, 3, and 4 respectively.

[0152] The colorimeter's internal program automatically calculates the color difference ΔE of each point (1, 2, 3, 4) relative to the sample's center point (0). Record these four color difference values.

[0153] Repeat the above operations to complete the internal color difference measurement and recording of sample C1 and sample C7 respectively.

[0154] Step 4: Data collation and analysis

[0155] For the five glossiness data measured for each sample, calculate the arithmetic mean and standard deviation.

[0156] Calculate the arithmetic mean of the four internal color difference ΔE data measured for each sample.

[0157] All data were collated and recorded in Table 1.

[0158] Experimental data:

[0159] Table 1: Experimental data for verifying the effect of magnetic field orientation technology

[0160] Sample number Gloss measurement point 1 (GU) Gloss measurement point 2 (GU) Gloss measurement point 3 (GU) Gloss measurement point 4 (GU) Glossiness center (GU) Average gloss (GU) Gloss standard deviation Average internal color difference (ΔE) Sample E1 94.2 95.1 94.6 95.5 94.8 94.84 0.47 0.21 Sample C1 85.1 88.3 84.5 89.2 86.6 86.74 1.93 1.58 Sample C7 86.3 84.9 88.8 85.2 87.1 86.46 1.55 1.72

[0161] Experimental summary:

[0162] Experimental results show that Sample E1, prepared according to Example 1 of the present invention, exhibits significantly improved glaze quality compared to the comparative samples. As can be seen from the data in Table 1, Sample E1 has an average gloss of 94.84 GU, significantly higher than the 86.74 GU of Comparative Example 1 (Sample C1) and the 86.46 GU of Comparative Example 7 (Sample C7). Furthermore, the gloss standard deviation of Sample E1 is only 0.47, significantly lower than the 1.93 of Sample C1 and the 1.55 of Sample C7, demonstrating the enhanced uniformity of its glaze surface. Furthermore, its average internal color difference (ΔE) is only 0.21, significantly lower than that of Sample C1 (1.58) and Sample C7 (1.72), reflecting the highly consistent color development across the entire glaze surface.

[0163] The above technical effects are derived from the magnetic field coordinated orientation technology adopted by the present invention. In the preparation process of sample E1, the Fe3O4@SiO2 core-shell structure magnetic composite medium introduced in the additive played a decisive role. The transverse magnetic field applied in the glazing step can exert a directional torque on these magnetic particles dispersed in the glaze, thereby guiding the SnO2 and other grains in the glaze as the opacified phase to be arranged in an orderly manner during the melting and cooling process of the glaze layer. This high degree of order in the microstructure fundamentally solves the problem of uneven light scattering on the glaze surface caused by the random distribution of grains, making the reflection and scattering behavior of light on the glaze surface tend to be consistent and controllable, and ultimately manifests itself as high gloss, high uniformity and stable coloring effect on a macro scale.

[0164] The results of the comparative examples reversely verify the integrity and necessity of the technical solution of the present invention. Sample C1 did not add magnetic media and did not apply a magnetic field, and its grain distribution was in a natural random state, resulting in unsatisfactory gloss and color difference performance. Although a magnetic field was applied in the preparation of sample C7, due to the lack of magnetic media that can respond to the magnetic field in its glaze, the magnetic field could not have an effective effect on the non-magnetic grains, and its final performance was basically the same as that of sample C1. This fully proves that simply applying a magnetic field or simply adding non-magnetic components cannot achieve the expected results. The synergistic effect of the magnetic composite medium and the magnetic field-assisted preparation process proposed in the present invention must be used to achieve precise control of the microstructure of the glaze layer, thereby obtaining high-quality, stable color-producing ceramic products.

[0165] Test Example 2: Verification of the effect of rare earth ion gradient release technology

[0166] Purpose of the experiment:

[0167] This experiment aims to verify that the gradient release technology achieved by using layered double hydroxide as a rare earth ion carrier in the present invention can effectively overcome the technical bottlenecks of rare earth ion agglomeration failure and local color difference expansion at high temperatures by testing the local color difference and acid corrosion resistance of the glaze, and improve the chemical stability of the glaze layer.

[0168] Experimental samples:

[0169] Sample E1: a ceramic sample prepared according to the method of Example 1, wherein the rare earth oxide in the additive is supported by a layered bishydroxyhydroxide.

[0170] Sample C2: A ceramic sample prepared according to the method of Comparative Example 2, wherein the rare earth oxide in the additive is directly added without being supported by any carrier.

[0171] Experimental equipment and reagents:

[0172] Portable integrating sphere colorimeter (D65 light source, 10° observer viewing angle);

[0173] 60° angle handheld gloss meter (accuracy 0.1GU);

[0174] Hydrochloric acid solution (analytical grade, prepared as a 3% v / v aqueous solution);

[0175] Beaker, marker, deionized water.

[0176] Experimental steps:

[0177] Step 1: Sample pretreatment and local color difference test

[0178] Clean and dry Samples E1 and C2. Use a marker to mark a 3x3 grid with 9 measurement points on the glaze surface of each sample, ensuring that the points cover the center and edge areas of the sample.

[0179] Turn on and calibrate the colorimeter. Measure the CIELab values ​​of each of the nine marked points on sample E1.

[0180] Calculate the maximum value of the color difference (ΔE) between any two of the nine measurement points and record it as the local color difference maximum value (ΔEmax) of the sample.

[0181] Repeat steps 2 and 3 for sample C2 and record the maximum local color difference.

[0182] Step 2: Chemical stability (acid resistance) test

[0183] Turn on and calibrate the gloss meter. Measure and record the initial gloss in the center area of ​​each sample (E1 and C2). To ensure accuracy, each sample can be measured three times and the average value can be taken.

[0184] The two samples were completely immersed in a beaker containing 3% hydrochloric acid solution and left to stand at room temperature for 24 hours.

[0185] After 24 hours, the samples were removed from the acid solution, rinsed repeatedly with plenty of deionized water until no acid residue remained on the surface, and then wiped dry thoroughly.

[0186] Using a gloss meter, measure and record the final gloss of the sample after corrosion in the same area as the initial measurement. .

[0187] The gloss reduction rate of each sample was calculated according to the following formula:

[0188] Gloss reduction rate ;

[0189] Step 3: Data organization

[0190] The data obtained in steps 1 and 2, i.e., the local color difference maximum value and gloss reduction rate of each sample, are sorted and recorded in Table 2 below.

[0191] Experimental data:

[0192] Table 2: Experimental data for verification of the effect of rare earth ion gradient release technology

[0193] Sample number Maximum local color difference (ΔEmax) Gloss reduction rate (%) Sample E1 0.48 4.7 Sample C2 3.15 28.6

[0194] Experimental summary:

[0195] Experimental data clearly demonstrates the significant effectiveness of the present invention's technical solution in improving glaze color uniformity and chemical stability. As shown in Table 2, Sample E1, prepared using Example 1 of the present invention, exhibits a maximum local color difference (ΔEmax) of only 0.48, indicating highly uniform color across the glaze. In stark contrast, Sample C2, from Comparative Example 2, which directly incorporates rare earth oxides, exhibits a maximum local color difference of 3.15, indicating significant color spots or uneven areas. In acid resistance testing, the gloss reduction rate of Sample E1 after corrosion was only 4.7%, while that of Sample C2 reached 28.6%, demonstrating that the glaze layer of Sample E1 possesses greater chemical stability.

[0196] The fundamental reason for the significant difference in performance described above lies in the rare earth ion gradient release technology employed in the present invention. In Example 1, rare earth oxides are pre-loaded in the layered structure of layered double hydroxides. During the high-temperature firing stage, this support structure undergoes progressive decomposition, enabling the controlled, continuous, and uniform release of rare earth ions throughout the glaze melting process. This uniform release method effectively avoids the localized aggregation of rare earth ions caused by rapid melting at high temperatures, ensuring their full and uniform chelation reaction with the colorant, thereby fundamentally eliminating the source of localized color differences.

[0197] The results of Comparative Example 2 confirm the defects of the traditional method. Since rare earth oxides are added directly and roughly to the glaze, agglomerates are inevitably formed at high temperatures, resulting in extremely uneven distribution of rare earth ions in the glaze layer, which in turn produces color differences visible to the naked eye, that is, high ΔEmax values ​​in the test data. At the same time, this uneven reaction and the presence of agglomerates also destroy the integrity and density of the final glaze layer structure, reducing its chemical stability and making it more susceptible to corrosion in an acidic environment, which is manifested as a significant decrease in gloss. Therefore, the present invention successfully solves the technical bottleneck of colorants easily agglomerating and failing at high temperatures, resulting in widened color differences and poor stability, by loading layered double hydroxides and achieving a gradient release of rare earth ions.

[0198] Test Example 3: Verification of the effect of multi-physics field coupling firing process

[0199] Purpose of the experiment:

[0200] The purpose of this experiment is to verify the superiority of the microwave-magnetic field-laser multi-physics field coupled gradient firing technology adopted in the present invention in achieving coordinated optimization of glaze layer densification and energy consumption control compared with the traditional single thermal field temperature control process by comparing the density of the glaze layer (characterized by water absorption), thermal shock resistance and total energy consumption of the firing process.

[0201] Experimental samples:

[0202] Sample E1: A ceramic sample prepared according to the method of Example 1, wherein the firing process adopts a multi-physics field coupled gradient firing process.

[0203] Sample C3: A ceramic sample prepared according to the method of Comparative Example 3, whose firing process adopts a traditional single thermal field temperature control process.

[0204] Experimental equipment:

[0205] Electronic balance (accuracy 0.001g), electric constant temperature drying oven;

[0206] Programmable high-temperature muffle furnace (for thermal shock experiments), water tank;

[0207] Industrial energy meter connected to the kiln (to record energy consumption).

[0208] Experimental steps:

[0209] Step 1: Glaze density (water absorption) test

[0210] Place samples E1 and C3 in a drying oven at 110°C and dry them to constant weight. Use an electronic balance to weigh and record their dry weight. .

[0211] The dried sample was completely immersed in a container of deionized water, heated to boiling and kept for 2 hours.

[0212] Stop heating and allow the sample to cool naturally to room temperature in water.

[0213] Take the sample out of the water, wipe off the water on its surface quickly with a wet cloth, weigh it immediately and record its saturated mass .

[0214] Calculate the water absorption of each sample according to the following formula:

[0215] Water absorption ;

[0216] Step 2: Thermal shock resistance test

[0217] The dried samples E1 and C3 were placed in a muffle furnace, heated to 180°C and kept at this temperature for 30 minutes.

[0218] The sample was quickly removed from the muffle furnace and immediately placed in cold water at 20°C for 30 seconds.

[0219] Take out the sample, wipe it dry and carefully observe whether there are any defects such as cracking and peeling on the glaze surface. This process is counted as one thermal shock cycle.

[0220] If the sample is intact, repeat steps 1 to 3 until the first visible cracks appear on the sample glaze.

[0221] The number of complete thermal shock cycles that each sample can withstand before failure is recorded.

[0222] Step 3: Firing energy consumption record

[0223] This step is performed during the sample preparation phase. The electric energy meter is connected to the power supply lines of the firing kilns used to prepare sample E1 and sample C3.

[0224] The complete firing procedures described in Example 1 and Comparative Example 3 were performed respectively.

[0225] After the firing process is completed, the total electric energy (kWh) consumed in preparing each sample is read and recorded from the electric energy meter.

[0226] Step 4: Data organization

[0227] The water absorption rate, thermal shock resistance cycle number and firing energy consumption data measured in the above experiments are summarized in Table 3.

[0228] Experimental data:

[0229] Table 3: Experimental data for verification of multi-physics field coupled firing process effect

[0230]

[0231] Experimental summary:

[0232] The experimental results strongly demonstrate the dual advantages of the firing process adopted by the present invention in improving product performance and achieving energy conservation and consumption reduction. According to the data in Table 3, the water absorption rate of sample E1 prepared by the gradient firing process of the present invention is as low as 0.07%, which is much lower than that of sample C3 (0.46%) fired by the traditional process. This shows that the glaze structure of sample E1 is denser. In terms of thermal shock resistance, sample E1 can withstand 22 rapid cooling and heating cycles, while sample C3 can only withstand 8 times, showing the superior structural stability of the former. In addition, the total energy consumption for preparing sample E1 is 15.3kWh, which saves a lot of energy compared to 21.8kWh of sample C3.

[0233] The realization of the above-mentioned technical advantages is attributed to the groundbreaking microwave-magnetic field-laser multi-physical field coupled gradient firing technology solution of this invention. This solution subverts the traditional process that relies on single heat conduction. In the heating stage, the bulk heating effect of microwaves realizes rapid and uniform heating from the inside to the outside; in the heat preservation stage, the synergistic effect of the magnetic field helps to stabilize the internal structure of the glaze layer; in the final crystallization stage, the precise energy input of the pulsed laser can further promote the densification of the glaze layer and optimize the crystal phase. This synergistic effect of multiple physical fields realizes the precise control of the physical and chemical changes of the glaze during the firing process, overcomes the difference in melting inside and outside the glaze layer caused by heat conduction lag, and forms a uniform, dense, low-stress microstructure.

[0234] In contrast, the traditional single thermal field temperature control process used in Comparative Example 3 allows heat to be transferred slowly from the outside to the inside, inevitably resulting in a large temperature difference between the inside and outside of the glaze layer, uneven melting and solidification processes, and ultimately a loose structure (manifested as high water absorption) and internal stress accumulation (manifested as poor thermal shock resistance). At the same time, this inefficient heat transfer method also results in a large amount of energy waste, leading to high firing energy consumption. Therefore, the gradient firing technology solution of the present invention, through the combined application of multiple physical fields, successfully breaks through the bottleneck of the traditional firing process, achieves a coordinated optimization of glaze densification and energy consumption control, and solves the common problems of unstable firing quality and serious energy waste in the industry.

[0235] Test Example 4: Verification of the rationality of the core group allocation ratio

[0236] Purpose of the experiment:

[0237] This experiment aimed to verify the scientific validity and necessity of the specified content range for the core component (magnesium oxide, for example) in the additive formulation of this invention by testing the surface quality and mechanical properties of the glaze. By comparing the performance differences between samples with magnesium oxide content within the specified range and those outside it, it was demonstrated that accurate formulation is crucial for achieving an ideal glaze.

[0238] Experimental samples:

[0239] Sample E1: A ceramic sample prepared according to the method of Example 1, wherein the content of magnesium oxide in the additive is within a specified reasonable range.

[0240] Sample C6: A ceramic sample prepared according to the method of Comparative Example 6, wherein the content of magnesium oxide in its additive exceeds the specified range.

[0241] Experimental equipment:

[0242] 60° angle handheld gloss meter (accuracy 0.1GU);

[0243] Contact surface profiler (or roughness tester);

[0244] Vickers microhardness tester.

[0245] Experimental steps:

[0246] Step 1: Sample pretreatment and gloss test

[0247] Samples E1 and C6 were cleaned and dried.

[0248] Turn on and calibrate the gloss meter. Randomly select 5 different locations on the glaze surface of each sample for measurement.

[0249] Five measurements were recorded and the average gloss was calculated for each sample.

[0250] Step 2: Glaze flatness (surface roughness) test

[0251] Turn on and calibrate the surface profiler.

[0252] In the central flat area of ​​each sample glaze surface, a sampling length of 2 mm was set and three independent linear scans were performed.

[0253] The instrument automatically calculates and records the arithmetic average roughness (Ra) value of each scan.

[0254] The average of three measurements for each sample was calculated as its average surface roughness (Ra).

[0255] Step 3: Glaze microhardness test

[0256] Turn on and calibrate the Vickers microhardness tester.

[0257] A load of 1.96 N (HV 0.2) was applied to the flat surface of each sample and held for 15 seconds to form an indentation. Five independent indentation tests were performed on each sample.

[0258] The diagonal length of each indentation is measured and the instrument automatically calculates the corresponding Vickers hardness value.

[0259] The average of the five hardness values ​​of each sample was calculated as the average Vickers hardness of the sample.

[0260] Step 4: Data organization

[0261] The average gloss, average surface roughness (Ra) and average Vickers hardness data measured in the above experiments are summarized in Table 4.

[0262] Experimental data:

[0263] Table 4: Experimental data for verifying the rationality of core group allocation ratio

[0264]

[0265] Experimental summary:

[0266] The experimental data intuitively demonstrates the accuracy and importance of the content ranges of each component in the additive composition provided by the present invention. As shown in Table 4, sample E1, prepared using the formula of Example 1 of the present invention, has an average gloss of up to 95.3 GU, an extremely smooth surface, an average roughness Ra value of only 0.16 μm, and a high Vickers hardness of 728 HV. In contrast, sample C6 of Comparative Example 6, which only increases the magnesium oxide content outside the specified range, experiences a sharp deterioration in performance: the average gloss drops sharply to 58.7 GU, the surface roughness increases significantly to 0.94 μm, and the Vickers hardness also drops significantly to 513 HV.

[0267] This huge difference in performance is rooted in the physical and chemical mechanism of the glaze system during high-temperature melting. Magnesium oxide plays a key role as a flux and network modifier in the formula, and its content directly affects the melting temperature, viscosity, and the type and amount of crystal phases precipitated upon cooling of the glaze. Under the precise ratio of Example 1, magnesium oxide synergizes with other components to form a eutectic with a low melting point and suitable viscosity, which is conducive to good leveling and bubble discharge of the glaze layer, and forms a dense, uniform glass-ceramic composite structure upon cooling, thereby obtaining a smooth, high-hardness ideal glaze surface. However, in Comparative Example 6, excessive magnesium oxide breaks this delicate chemical balance, which may lead to an improper increase in the melting point of the glaze or premature precipitation of high-melting-point crystals (such as forsterite) at high temperatures, hindering the normal melting and leveling of the glaze, and ultimately forming a rough, uneven, loose structure full of microscopic defects, which manifests itself macroscopically as low gloss, rough surface, and poor mechanical strength.

[0268] The results of this comparative experiment fully demonstrate that the composition content range defined by the present invention is not an arbitrary choice, but rather a necessary condition for achieving the intended technical effect. It emphasizes that the innovation of this invention lies not only in the introduction of multiple functional components, but also in the determination, through scientific calculations and experiments, of the precise ratio range between these components that produces the optimal synergistic effect. Any attempt to exceed this range, as shown in Comparative Example 6, will destroy the synergistic effect between the components, resulting in the overall failure of the technical solution. Therefore, the determination of this component ratio is one of the core technical contributions of the present invention to achieve high-performance and stable color-producing glazes, and it possesses non-obvious inventiveness.

[0269] Test Example 5: Verification of the synergistic effect of key components

[0270] Purpose of the experiment:

[0271] This experiment aims to verify the superiority of the Fe3O4@SiO2 core-shell structure of the present invention over ordinary magnetic materials, as well as the gain effect of the photoactivation treatment step on the performance of the final product by comparing and testing the surface quality, color difference and glaze adhesion of the glaze, thereby demonstrating the synergistic contribution of each key technical point.

[0272] Experimental samples:

[0273] Sample E1: A ceramic sample prepared according to the method of Example 1, using a Fe3O4@SiO2 core-shell structure medium and subjected to photoactivation treatment.

[0274] Sample C4: A ceramic sample prepared according to the method of Comparative Example 4, using ordinary Fe3O4 micropowder to replace the core-shell structure medium.

[0275] Sample C5: A ceramic sample prepared according to the method of Comparative Example 5, omitting the photoactivation treatment step during the glazing process.

[0276] Experimental equipment:

[0277] 60° angle handheld gloss meter (accuracy 0.1GU);

[0278] Portable integrating sphere colorimeter (D65 light source, 10° observer viewing angle);

[0279] Cross-cut adhesion tester (100-grid knife, in line with ISO2409 standard), special tape.

[0280] Experimental steps:

[0281] Step 1: Surface quality and color difference test

[0282] Samples E1, C4 and C5 were cleaned and dried.

[0283] Gloss test: Use a gloss meter to randomly select 5 different locations on the glaze surface of each sample for measurement, and calculate and record the average gloss.

[0284] Color Difference Test: Turn on and calibrate the colorimeter. Using sample E1 as the standard, measure the CIELab value at its center. Then, measure the Lab values ​​at the center of samples C4 and C5. The instrument automatically calculates and records the overall color difference (ΔE) of samples C4 and C5 relative to standard sample E1.

[0285] Step 2: Glaze adhesion test (cross-cut method)

[0286] The test was performed on the flat area in the center of the glaze surface of each sample.

[0287] Hold the grating knife with the blade perpendicular to the sample surface and cut 6 parallel scratches on the glaze surface with uniform pressure and speed.

[0288] The sample was rotated 90 degrees and the above operation was repeated on the original scratch to cut another 6 parallel scratches to form an 11x11 square grid array.

[0289] Take a piece of special tape and stick it firmly on the grid array, pressing it firmly with your fingers or an eraser to ensure that the tape is in full contact with the glaze surface.

[0290] About 1 minute after application, peel off the tape steadily at an angle close to 60°.

[0291] Use a magnifying glass to observe the glaze peeling in the cross-cut area and grade the adhesion according to ISO 2409 (0 is the best and 5 is the worst). Record the adhesion grade for each sample.

[0292] Step 3: Data organization

[0293] The average gloss, overall color difference and adhesion grade data measured in the above experiments are summarized in Table 5.

[0294] Experimental data:

[0295] Table 5: Experimental data for verification of synergistic effect of key components

[0296]

[0297] Experimental summary:

[0298] The results of this comparative experiment provide a detailed analysis of the independent contributions and synergistic effects of the two key technical points in this invention. The data in Table 5 show that Sample E1, the benchmark in Example 1, exhibits the best overall performance, with a high gloss of 94.9 GU, no color difference, and perfect adhesion of level 0. When the core-shell structure medium is replaced with standard Fe₃O₄ (Sample C4), all performance indicators decline significantly, with gloss dropping to 82.3 GU, a significant color difference of 2.81, and adhesion deteriorating to level 2. Sample C5, which omits the light activation treatment, performs better than Sample C4 but still falls short of Sample E1, exhibiting a slightly lower gloss (91.5 GU), a perceptible color difference (0.88), and a slight decrease in adhesion (level 1).

[0299] The performance difference between sample E1 and sample C4 profoundly reveals the necessity of the Fe3O4@SiO2 core-shell structure. Under high-temperature firing conditions, uncoated Fe3O4 (such as that used in sample C4) is chemically active and will directly react with the surrounding silicate glaze to generate unexpected variegated phases, thereby destroying the color purity of the glaze surface and resulting in significant color difference and gloss reduction. At the same time, this interfacial side reaction also weakens the bond between the glaze layer and the ceramic body, resulting in reduced adhesion. The core-shell structure adopted by the present invention, in which the SiO2 shell acts as a chemically inert isolation layer at high temperatures, effectively preventing the internal Fe3O4 magnetic core from chemically reacting with the glaze, ensuring that it only plays a physical directional role without interfering with the glaze's color development system, ultimately ensuring the high gloss, color stability and excellent adhesion of the glaze surface.

[0300] The comparison between sample E1 and sample C5 verifies the gain effect of the photoactivation treatment step. The photoactivation treatment during the glazing process aims to improve the surface energy and reaction activity of each component in the glaze slurry through light of a specific wavelength, and promote the formation of a better physical and chemical bond between the glaze and the body before firing. This optimized initial bonding state will be transformed into a stronger interfacial bonding force during the subsequent high-temperature firing process, so the adhesion of sample E1 reached the optimal level 0. Sample C5, which did not undergo this step, had a slightly insufficient glaze-body bonding strength, and its adhesion was shown as level 1. This result clearly shows that the Fe3O4@SiO2 core-shell structure and photoactivation treatment are two complementary and indispensable key links in the present invention, and the synergistic effect of the two jointly ensures the high comprehensive performance of the final product.

[0301] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An additive for stabilizing the color of ceramic glaze during firing, characterized in that: Calculated by weight percentage, it includes the following components: 20-30 parts of magnesium oxide, 15-20 parts of zinc oxide, 5-10 parts of tin oxide, 10-15 parts of sodium phosphate, 3-5 parts of rare earth oxide, 3-5 parts of layered double hydroxide, 0.5-1.2 parts of upconversion luminescent nanoparticles, 2-3 parts of magnetic composite medium, and 5-8 parts of nano-barium titanate; The purity of the magnesium oxide is ≥99.5%, and the particle size distribution D50 is 0.5-2 μm. The mass ratio of the zinc oxide to the tin oxide is 2.5:1 to 3.5:

1. The mass ratio of the sodium phosphate to the rare earth oxide is 2.5:1 to 3.5:

1. The rare earth oxide is lanthanum oxide, and the layered double hydroxide is Mg6Al2(OH) 16 CO3·4H2O, the upconversion luminescent nanoparticles are Eu 3+ Doped NaYF4:Yb,Er; The magnetic composite medium is a Fe3O4@SiO2 core-shell structure, wherein: Fe3O4 core diameter 180-220nm; SiO2 shell thickness 8-12nm; Saturation magnetization 45-50emu / g.

2. A method for stabilizing the color development of ceramic glazes by using the additive according to claim 1, characterized in that: The following steps are involved: S1. Preparation of additives: After screening and rare earth loading, the components are mixed and ball-milled until D90 ≤ 2 μm to obtain the additives; S2. Preparation of glaze: Add the additive obtained in S1 at 5-8% of the base glaze, and fully mix it with the colorant using an ultrasonic dispersing device to obtain a glaze; S3, magnetic field-assisted glazing: applying the glaze obtained in S2 to the surface of the ceramic body, applying a 0.3-0.5T transverse magnetic field during the glazing process, and simultaneously performing a photoactivation treatment to obtain a glazed ceramic body; S4, gradient field firing: The glazed ceramic body obtained in S3 is fired using gradient temperature control to obtain a ceramic product.

3. The method for stabilizing the color development of ceramic glazes by firing according to claim 2, characterized in that: In the step S1, zirconia balls and Fe3O4@SiO2 magnetic media are used for ball milling, with a ball-to-material ratio of 2:1, and a 0.3T pulsed magnetic field with a frequency of 10-15 Hz is applied.

4. The method for stabilizing the color development of ceramic glazes during firing according to claim 2, wherein: The light activation treatment in step S3 uses a 980-1000 nm laser with a power density of 2-3 W / cm 2 , scanning speed 5-8mm / s.

5. The method for stabilizing the color development of ceramic glaze after firing according to claim 2, characterized in that: The gradient temperature-controlled firing in step S4 includes microwave-assisted heating, magnetic field-coordinated heat preservation, and pulsed laser crystallization strengthening.

6. The method for stabilizing the color development of ceramic glaze after firing according to claim 2, characterized in that: The gradient temperature controlled firing in step S4 includes the following steps: Stage 1: Starting from room temperature, microwave-assisted heating was performed at a rate of 8-12°C / min to 600°C; The second stage: continue heating from 600℃ to 1250℃ at a rate of 4-5℃ / min; The third stage: magnetic field coordinated heat preservation between 1250℃ and 1300℃ for 40-60min; The fourth stage: the temperature is raised from 1300°C to 1320°C at a rate of 2-3°C / min. During this stage, a pulsed laser with a wavelength of 1064-1080nm is applied for crystallization strengthening treatment, and the single pulse energy is 0.8-1.2mJ.

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