High-performance low-expansion heat-resistant purple sand tea set with far infrared radiation function

Abstract

This invention discloses a high-performance, low-expansion, and far-infrared radiation-functional heat-resistant purple clay teaware, belonging to the field of ceramic teaware technology. The teaware employs a double-layer composite structure: the inner layer is a low-expansion reinforcing layer, composed of: 58-73% purple clay ore, 2-3% rare earth elements, 10-20% surface-hydroxylated cordierite micropowder, 5-15% mullite particles, and 2-5% firing aid; the outer layer is a far-infrared radiation functional layer, composed of: 30-40% far-infrared radiation powder, 30-40% purple clay fine powder, and 10-15% high-temperature binder; a quartz sand transition layer is provided between the inner and outer layers. This invention utilizes the aforementioned high-performance, low-expansion, and far-infrared radiation-functional heat-resistant purple clay teaware. Through the modification technology of the inner layer's hydroxylated cordierite micropowder, the interfacial bonding strength between cordierite and the purple clay matrix is ​​improved. Combined with the skeletal support of mullite particles, this reduces the inner layer's thermal expansion coefficient, improves thermal shock resistance, and solves the problem of temperature difference cracking.

Description

Technical Field

[0001] This invention relates to the field of ceramic teaware technology, and in particular to a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware. Background Technology

[0002] Zisha (purple clay) teaware, with its unique porous structure, excellent breathability, and heat retention, has become an important tool in traditional tea culture. As consumers' demands for the functionality of teaware increase, high-performance Zisha teaware that combines heat resistance and crack resistance with far-infrared radiation enhancement (promoting the dissolution of substances in tea soup) has become a research hotspot. Current technologies improve performance by adding low-expansion minerals and far-infrared functional powders, but the following key issues still exist in practical applications:

[0003] Traditional Zisha clay has a high coefficient of thermal expansion. While adding cordierite directly can reduce expansion, the weak bonding between the particles and the Zisha clay matrix leads to microcracks in the clay body during sintering, making it difficult to meet the thermal shock resistance requirements for high-frequency temperature difference applications.

[0004] Existing far-infrared powders are mostly added through mechanical mixing. Silicon carbide is easily oxidized during high-temperature sintering, resulting in an emissivity of less than 80% in the 8-15μm band, and its function degrades significantly after long-term use. In addition, a single material cannot achieve a partitioned design that combines "matrix support" and "functional enhancement", making it difficult to balance far-infrared radiation and matrix strength.

[0005] Some technologies attempt to use a double-layer structure, but the bonding between the layers relies on simple physical adhesion, which does not solve the delamination problem caused by the difference in thermal expansion of the materials. In addition, the coating thickness is uneven and easy to fall off, which cannot pass the test of industrial mass production.

[0006] Traditional forming processes (such as hand-shaping and mold pressing) make it difficult to accurately control the density uniformity of multi-layer structures. During the sintering process, the inconsistent shrinkage rates of the inner and outer layers lead to deformation. At the same time, the design of the kettle body does not take into account heat dissipation requirements, resulting in excessively high surface temperatures during high-temperature use, which poses a safety hazard. Summary of the Invention

[0007] The purpose of this invention is to provide a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teapot to solve the above-mentioned problems.

[0008] To achieve the above objectives, the present invention provides a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, wherein the teaware adopts an inner and outer double-layer composite structure:

[0009] The inner layer is a low-expansion reinforcing layer. The raw materials, by weight percentage, include: 58-73% purple clay ore, 2-3% rare earth elements, 10-20% surface-hydroxylated cordierite powder, 5-15% mullite particles, and 2-5% sintering aid. Among them, the surface-hydroxylated cordierite powder has a particle size of 5-10 μm and is obtained by hydroxylating cordierite powder and then ultrasonically treating it at 50℃ for 2 hours with a 5% KH-560 silane coupling agent solution. The mullite particles have a particle size of 10-30 μm. The sintering aid consists of BaCO3 and ZnO, with a BaCO3 to ZnO mass ratio of 2:1.

[0010] The outer layer is a far-infrared radiation functional layer. The raw materials, by weight percentage, include: 30-40% far-infrared radiation powder, 30-40% purple clay fine powder, and 10-15% high-temperature binder. Among them, the far-infrared radiation powder includes 25-35% Fe2O3, 15-25% ZrO2, and 10-20% SiC. The SiC surface is coated with a 5-10μm thick Fe2O3-ZrO2 composite coating. The purple clay fine powder has a particle size of ≤5μm. The high-temperature binder is silica sol with a solid content of 30%.

[0011] A quartz sand transition layer with a thickness of 0.3-0.5 mm is set between the inner and outer layers. It is composed of quartz sand with a particle size of 10-20 μm, which is uniformly distributed at the bonding interface and formed by co-sintering to form a mechanical interlocking structure with a bonding strength ≥5 MPa.

[0012] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, the preparation method of the inner low-expansion reinforcing layer includes: mixing purple clay ore, rare earth elements, hydroxylated cordierite powder, mullite particles, firing aid, and deionized water at a mass ratio of 1:0.35-0.4, and after vacuum kneading, aging in an environment with 90% humidity and 25℃ for 20 days to obtain the inner layer clay material; wherein, the vacuum degree of vacuum kneading is -0.09MPa, and the kneading time is 20min.

[0013] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, far-infrared radiation powder, purple clay fine powder and silica sol are mixed and made into functional particles with a particle size of 0.1-0.3mm by spray granulation, and deionized water is added to make an outer layer of clay with a moisture content of 22-25%.

[0014] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, the quartz sand in the quartz sand transition layer is pre-fired at 1000℃ for 2 hours, with a surface roughness Ra of 1.6-3.2μm, and is evenly sprinkled on the surface of the inner layer body before being covered with the outer layer clay for composite molding. The amount of quartz sand used is 5-10g. m 2 .

[0015] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, the molding method of the composite structure is as follows: a segmented molding process is adopted, the inner layer of clay is first pressed into shape by a mold at a pressure of 5-10 MPa, and then dried to a moisture content of 10-12%. A quartz sand transition layer is laid on the surface, and then the outer functional layer of clay is wrapped around it. The whole body is formed by secondary molding, and the secondary molding pressure is 3-5 MPa.

[0016] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, the coefficient of thermal expansion of the inner low-expansion reinforcing layer is ≤3.0×10⁻⁶. -6 The outer far-infrared radiation functional layer has an emissivity of ≥88% in the 8-15μm band and a thickness of 0.5-1mm. The water absorption rate is ≤1.0%.

[0017] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, the sintering process is segmented sintering:

[0018] In the low-temperature section, the sintering conditions are room temperature - 400℃, with a heating rate of 5℃. min, keep warm for 1 hour, remove organic matter;

[0019] In the medium-temperature range, the sintering conditions are 400-1000℃, with a heating rate of 3℃. min, keep warm for 2h, and introduce 5% volume concentration N2 protective gas to achieve crystal transformation;

[0020] In the high-temperature section, the sintering conditions are 1000-1220℃, with a heating rate of 2℃. The process involves holding the material at room temperature for 3 hours with an oxygen content ≤1% to complete co-sintering, thereby achieving a chemical-mechanical dual bond between the inner and outer layers through a quartz sand transition layer.

[0021] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teapot, the inner wall thickness of the teapot body is 2-3mm, the outer wall thickness is 0.5-1mm, and the overall wall thickness is 3-4mm; the spout and the inner substrate are connected by an embedded connection with a connection depth of 5-8mm, and the outer functional layer covers the connection interface to form a sealed transition area.

[0022] Preferably, in the above-mentioned high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, the far-infrared radiation functional layer and the inner layer form an interlocking structure, and the quartz sand particles are embedded in the inner and outer layer matrix to a depth of ≥50μm.

[0023] A method for preparing a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teapot as described above includes the following steps:

[0024] (1) Preparation of inner layer clay: crush the purple clay ore to 200 mesh, mix it with rare earth, hydroxylated cordierite powder, mullite particles and sintering aid, make slurry at a water-to-material ratio of 0.35:1, and vacuum knead the clay for 20 minutes.

[0025] (2) Preparation of outer functional particles: far-infrared powder, purple clay fine powder and silica sol are spray granulated to obtain functional particles;

[0026] (3) Composite molding: After the inner blank is formed, a quartz sand transition layer is laid, and the outer functional layer clay is wrapped around it for secondary molding;

[0027] (4) Segmented sintering: sintering is completed according to the low temperature debinding, medium temperature protection and high temperature co-sintering system to obtain the finished product.

[0028] Therefore, the present invention employs the above-mentioned high-performance, low-expansion, and far-infrared radiation-functional heat-resistant purple clay teaware, which has the following beneficial effects:

[0029] (1) Rare earth elements can reduce the coefficient of thermal expansion, increase density, and enhance structural stability. During sintering, rare earth elements can form a eutectic liquid phase with sintering aids, filling grain boundary pores and accelerating ion diffusion. Adding rare earth elements can cause lattice distortion, increase grain boundary stress, and offset thermal expansion at high temperatures. Hydroxylated cordierite forms -OH groups on the particle surface through silane coupling agent (KH-560), forming hydrogen bonds with Al-OH and Si-OH in purple clay. After sintering, it is converted into Si-O-Al covalent bonds, achieving chemical bonding and strengthening. The Fe2O3-ZrO2 coating layer forms a dense oxide barrier layer (melting point ≥1500℃) during sintering. Combined with a nitrogen protective atmosphere, it inhibits the oxidation reaction of SiC in the 1000-1220℃ range, retaining the core radiative components. Through the elastic buffering effect of the quartz sand transition layer, the interfacial thermal stress during sintering is reduced, avoiding crack initiation.

[0030] (2) Through the modification technology of inner layer hydroxylated cordierite micro powder, the interfacial bonding strength between cordierite and purple clay matrix is ​​improved. Combined with the skeleton support of mullite particles, the inner thermal expansion coefficient is reduced, and the thermal shock resistance reaches ≥6 cycles of rapid cooling and heating from 200℃ to 25℃ without damage, which is an improvement over traditional teaware and solves the problem of temperature difference cracking.

[0031] (3) The outer layer adopts the SiC surface coating Fe2O3-ZrO2 composite coating technology (coating thickness 5-10μm). The dual-layer structure realizes functional partitioning. The inner layer provides a high-strength, low-expansion substrate, while the outer layer focuses on far-infrared radiation, avoiding performance compromise of a single material.

[0032] (4) The quartz sand transition layer technology forms a dual combination of "mechanical interlocking and chemical bonding" during the co-sintering process. Scanning electron microscopy shows that the quartz sand particles are embedded in the inner and outer layers to a depth of ≥50μm, forming an interlocking interface structure, which completely solves the problem of delamination and meets the requirements of industrial impact resistance testing.

[0033] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0034] To better understand the above technical solutions, a detailed description of the specific implementation methods will be provided below. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0036] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0037] This invention provides a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, wherein the teaware adopts an inner and outer double-layer composite structure:

[0038] The inner layer is a low-expansion reinforcing layer. The raw materials, by weight percentage, include: 58-73% purple clay ore, 2-3% rare earth elements, 10-20% surface-hydroxylated cordierite powder, 5-15% mullite particles, and 2-5% sintering aid. Among them, the surface-hydroxylated cordierite powder has a particle size of 5-10 μm and is obtained by hydroxylating cordierite powder and then ultrasonically treating it at 50℃ for 2 hours with a 5% KH-560 silane coupling agent solution. The mullite particles have a particle size of 10-30 μm. The sintering aid consists of BaCO3 and ZnO, with a BaCO3 to ZnO mass ratio of 2:1.

[0039] The outer layer is a far-infrared radiation functional layer. The raw materials, by weight percentage, include: 30-40% far-infrared radiation powder, 30-40% purple clay fine powder, and 10-15% high-temperature binder. Among them, the far-infrared radiation powder includes 25-35% Fe2O3, 15-25% ZrO2, and 10-20% SiC. The SiC surface is coated with a 5-10μm thick Fe2O3-ZrO2 composite coating. The purple clay fine powder has a particle size of ≤5μm. The high-temperature binder is silica sol with a solid content of 30%.

[0040] A quartz sand transition layer with a thickness of 0.3-0.5 mm is set between the inner and outer layers. It is composed of quartz sand with a particle size of 10-20 μm, which is uniformly distributed at the bonding interface and formed by co-sintering to form a mechanical interlocking structure with a bonding strength ≥5 MPa.

[0041] To further optimize the above technical solution, the preparation method of the inner low-expansion reinforcing layer includes: mixing purple clay ore, rare earth, hydroxylated cordierite powder, mullite particles, sintering aid and deionized water at a mass ratio of 1:0.35-0.4, and after vacuum kneading, aging in an environment with 90% humidity and 25℃ for 20 days to obtain the inner layer clay material; wherein, the vacuum degree of vacuum kneading is -0.09MPa and the kneading time is 20min.

[0042] To further optimize the above technical solution, far-infrared radiation powder, purple clay fine powder and silica sol are mixed and made into functional particles with a particle size of 0.1-0.3mm by spray granulation. Deionized water is added to prepare an outer layer of clay with a moisture content of 22-25%.

[0043] To further optimize the above technical solution, the quartz sand in the transition layer is pre-fired at 1000℃ for 2 hours, with a surface roughness Ra of 1.6-3.2μm. It is then evenly spread on the surface of the inner layer blank, and then covered with the outer layer of clay for composite molding. The dosage is 5-10g. m 2 .

[0044] To further optimize the above technical solution, the molding method of the composite structure is as follows: adopt a segmented molding process, first press the inner layer of clay material into shape through a mold at a pressure of 5-10 MPa, then dry it to a moisture content of 10-12%, lay a quartz sand transition layer on the surface, and then cover it with the outer functional layer of clay material. The whole blank is formed by secondary molding at a pressure of 3-5 MPa.

[0045] To further optimize the above technical solution, the coefficient of thermal expansion of the inner low-expansion reinforcement layer is ≤3.0×10⁻⁶. -6 / ℃, water absorption rate ≤1.0%, providing a high-temperature impact resistant substrate for the outer functional layer; the outer far-infrared radiation functional layer has an emissivity ≥88% in the 8-15μm band and a thickness of 0.5-1mm.

[0046] To further optimize the above technical solution, the sintering process is segmented sintering:

[0047] In the low-temperature section, the sintering conditions are room temperature - 400℃, with a heating rate of 5℃. min, keep warm for 1 hour, remove organic matter;

[0048] In the medium-temperature range, the sintering conditions are 400-1000℃, with a heating rate of 3℃. min, keep warm for 2h, and introduce 5% volume concentration N2 protective gas to achieve crystal transformation;

[0049] In the high-temperature section, the sintering conditions are 1000-1220℃, with a heating rate of 2℃. The process involves holding the material at room temperature for 3 hours with an oxygen content ≤1% to complete co-sintering, thereby achieving a chemical-mechanical dual bond between the inner and outer layers through a quartz sand transition layer.

[0050] To further optimize the above technical solution, the inner wall thickness of the kettle body is 2-3mm, the outer wall thickness is 0.5-1mm, and the overall wall thickness is 3-4mm; the spout and the inner substrate are connected by an embedded connection with a connection depth of 5-8mm, and the outer functional layer covers the connection interface to form a sealed transition area.

[0051] To further optimize the above technical solution, the far-infrared radiation functional layer and the inner layer form an interlocking structure, and the quartz sand particles are embedded in the inner and outer matrix to a depth of ≥50μm.

[0052] A method for preparing a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teapot as described above includes the following steps:

[0053] (1) Preparation of inner layer clay: crush the purple clay ore to 200 mesh, mix it with rare earth, hydroxylated cordierite powder, mullite particles and sintering aid, make slurry at a water-to-material ratio of 0.35:1, and vacuum knead the clay for 20 minutes.

[0054] (2) Preparation of outer functional particles: far-infrared powder, purple clay fine powder and silica sol are spray granulated to obtain functional particles;

[0055] (3) Composite molding: After the inner blank is formed, a quartz sand transition layer is laid, and the outer functional layer clay is wrapped around it for secondary molding;

[0056] (4) Segmented sintering: sintering is completed according to the low temperature debinding, medium temperature protection and high temperature co-sintering system to obtain the finished product.

[0057] To provide a clearer and more detailed description of the high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware provided by the embodiments of the present invention, the following description will be based on specific embodiments.

[0058] Example 1

[0059] Inner low-expansion reinforcing layer: 68% purple clay ore, 2% rare earth elements, 15% hydroxylated cordierite powder, 10% mullite particles, and 5% sintering aid; among which, the purple clay ore is purple mud, with 60% SiO2 and 22% Al2O3; the hydroxylated cordierite powder has a particle size of 5-10μm, is treated with KH-560 for 2h, and has a hydroxylation degree of 85%; the mullite particles have a particle size of 20μm, and the sintering aid is BaCO3 and ZnO, with BaCO3:ZnO=2:1;

[0060] Outer far-infrared radiation functional layer: 35% far-infrared powder, 40% purple clay fine powder, and 25% silica sol; among which, the far-infrared powder includes 30% Fe2O3, 20% ZrO2, and 15% SiC, with an 8μm SiC coating layer; the purple clay fine powder has a particle size ≤5μm; and the silica sol has a solid content of 30%.

[0061] Quartz sand transition layer: particle size 15μm, pre-fired at 1000℃ for 2h, surface roughness Ra2.0μm;

[0062] Preparation steps: Inner layer mud preparation: the raw materials and deionized water are mixed at a ratio of 1:0.35, and the mixture is treated in a vacuum pumice machine at -0.09MPa for 20 minutes, at a temperature of 25℃ and a humidity of 90%, and aged for 20 days, with mechanical turning every 3 days during the period.

[0063] For the preparation of outer functional particles, far-infrared powder is mixed with purple clay fine powder and silica sol and then sprayed into granules. The inlet air temperature is 180℃ and the outlet air temperature is 90℃ to obtain 0.2mm particles. Water is added to adjust the moisture content to 23%.

[0064] Composite molding: the inner layer of clay is pressed into shape using a mold at a pressure of 8 MPa, dried to a moisture content of 12%, and then 8 g of quartz sand is evenly sprinkled on the surface. m 2 The outer layer of clay is coated and formed twice under a pressure of 4MPa, resulting in a teapot body with an inner wall thickness of 2.5mm and an outer wall thickness of 0.8mm.

[0065] Segmented sintering, low-temperature section: room temperature - 400℃, heating rate of 5℃. min, keep warm for 1 hour;

[0066] Medium temperature range: 400-1000℃, heating rate is 3℃. min, introduce 5% N2, keep warm for 2 hours;

[0067] High temperature range: 1000-1200℃, heating rate is 2℃. min, oxygen content ≤1%, hold for 3 hours, then cool with the furnace.

[0068] Performance testing:

[0069] Coefficient of thermal expansion: 2.8 × 10⁻⁶ -6 ℃;

[0070] Far-infrared emissivity (8-15μm): 89%;

[0071] Thermal shock resistance: No damage after 7 cycles of 200℃-25℃;

[0072] Interlayer bond strength: 5.5 MPa (tensile test);

[0073] Surface temperature (water temperature at 100℃): 52℃.

[0074] Example 2

[0075] The only difference from Example 1 is that the temperature of the high-temperature sintering section is 1220°C, while the other parameters are the same.

[0076] Performance differences: Far-infrared emissivity increased to 90%, SiC oxidation rate further decreased, and coefficient of thermal expansion slightly increased to 3.0×10⁻⁶. -6 At ℃, it showed no damage after 6 thermal shock tests, but the increased sintering shrinkage led to micro-stress.

[0077] Example 3

[0078] The inner layer formula was adjusted to: 62% purple clay ore, 3% rare earth, 20% hydroxylated cordierite, 8% mullite, and 7% sintering aid. The remaining parameters were the same as in Example 1.

[0079] Performance differences: The coefficient of thermal expansion is reduced to 2.5×10. -6 The temperature was ℃, but the thermal shock resistance dropped to 6 times. The excessive cordierite content led to a decrease in the toughness of the matrix, and the bonding strength was 5.2 MPa.

[0080] Comparative Example 1

[0081] Raw material formula: 75% purple clay ore, 15% unmodified cordierite, 5% mullite, 5% firing aid (single material, without outer layer and transition layer).

[0082] Preparation process: Traditional mold forming, air sintering, 1200℃, 3h.

[0083] Performance comparison: Coefficient of thermal expansion 4.5×10 -6 ℃, thermal shock resistance after 4 failures, no far-infrared radiation function, no interlayer bonding problems.

[0084] Comparative Example 2

[0085] Structural design: inner layer The outer layer material is the same as in Example 1, but it is directly bonded together (without a quartz sand transition layer).

[0086] Performance comparison: interlayer bonding strength 3.2MPa, delamination during tensile test, outer layer detached after 5 thermal shock cycles, surface temperature 60℃, heat dissipation structure is the same, but abnormal heat conduction is caused by delamination.

[0087] Comparative Example 3

[0088] Structural design: Single-layer purple clay substrate, formula is the same as comparative example 1, outer layer is sprayed with a coating of far-infrared powder and binder, thickness 2mm.

[0089] Preparation process: After the substrate is sintered, a second coating is sprayed on, followed by low-temperature sintering at 1000℃.

[0090] Performance comparison: Far-infrared emissivity 82%, SiC oxidation rate 25%, coating bonding strength 2.5MPa, easy to peel off, coating cracks after 3 thermal shocks.

[0091] The data comparison between Examples 1-3 and Comparative Examples 1-3 is shown in Table 1 below;

[0092] Table 1 Comparison of Data Between Examples and Comparative Examples

[0093]

[0094] Necessity of hydroxylation modification: In Comparative Example 1, unmodified cordierite resulted in an increase in the coefficient of thermal expansion of 1.7 × 10⁻⁶. -6 At ℃, the thermal shock resistance decreased by 42%, demonstrating the key role of surface modification in interfacial bonding and thermal stability.

[0095] The role of the quartz sand transition layer: In Comparative Example 2, the bonding strength decreased by 42% without the transition layer, and the thermal shock resistance decreased by 29% due to delamination failure, verifying the irreplaceable role of the transition layer in suppressing interfacial stress.

[0096] Advantages of the dual-layer structure: The emissivity and bonding strength of the single coating in Comparative Example 3 are significantly lower than those in the Example, demonstrating the breakthrough of the co-sintered dual-layer structure in terms of functional stability and structural reliability.

[0097] By comparing the examples and comparative examples, the synergistic effect of raw material surface modification, quartz sand transition layer bonding, and double-layer co-sintering process in this invention is fully verified. Moreover, the preparation process can be realized by conventional ceramic equipment, which makes it feasible for industrial production.

[0098] Therefore, the high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware of the present invention utilizes rare earth elements in its raw materials. This reduces the coefficient of thermal expansion, increases density, and enhances structural stability. During sintering, rare earth elements can form a eutectic liquid phase with the sintering aid, filling grain boundary pores and accelerating ion diffusion. The addition of rare earth elements can also cause lattice distortion, increasing grain boundary stress and offsetting thermal expansion at high temperatures. Hydroxylated cordierite forms -OH groups on the particle surface through a silane coupling agent (KH-560), forming hydrogen bonds with Al-OH and Si-OH in the purple clay. After sintering, these groups transform into Si-O-Al covalent bonds, achieving chemical bonding and strengthening. The Fe2O3-ZrO2 coating layer forms a dense oxide barrier layer (melting point ≥1500℃) during sintering. Combined with a nitrogen protective atmosphere, this inhibits the oxidation reaction of SiC in the 1000-1220℃ range, preserving the core radiating components. The elastic buffering effect of the quartz sand transition layer reduces interfacial thermal stress during sintering, preventing crack initiation.

[0099] Through the modification technology of inner layer hydroxylated cordierite micro powder, the interfacial bonding strength between cordierite and purple clay matrix is ​​improved. Combined with the skeletal support of mullite particles, the coefficient of thermal expansion of the inner layer is reduced, and the thermal shock resistance reaches ≥6 cycles of rapid cooling and heating from 200℃ to 25℃ without damage. This is an improvement over traditional teaware and solves the problem of temperature difference cracking.

[0100] The outer layer employs a SiC surface coated with a Fe2O3-ZrO2 composite coating technology (coating thickness 5-10μm). This dual-layer structure achieves functional zoning, with the inner layer providing a high-strength, low-expansion substrate and the outer layer focusing on far-infrared radiation, avoiding performance compromises associated with single materials. The quartz sand transition layer technology forms a dual bond of "mechanical interlocking and chemical bonding" during co-sintering. Scanning electron microscopy reveals that quartz sand particles are embedded in the inner and outer layers to a depth ≥50μm, forming an interlocking interface structure that completely solves the delamination problem and meets the requirements of industrial impact resistance testing.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware, characterized in that: The tea set adopts a double-layer composite structure: The inner layer is a low-expansion reinforcing layer. The raw materials, by weight percentage, include: 58-73% purple clay ore, 2-3% rare earth elements, 10-20% surface-hydroxylated cordierite powder, 5-15% mullite particles, and 2-5% sintering aid. Among them, the surface-hydroxylated cordierite powder has a particle size of 5-10 μm and is obtained by hydroxylating cordierite powder and then ultrasonically treating it at 50℃ for 2 hours with a 5% KH-560 silane coupling agent solution. The mullite particles have a particle size of 10-30 μm. The sintering aid consists of BaCO3 and ZnO, with a BaCO3 to ZnO mass ratio of 2:

1. The outer layer is a far-infrared radiation functional layer. The raw materials, by weight percentage, include: 30-40% far-infrared radiation powder, 30-40% purple clay fine powder, and 10-15% high-temperature binder. Among them, the far-infrared radiation powder includes 25-35% Fe2O3, 15-25% ZrO2, and 10-20% SiC. The SiC surface is coated with a 5-10μm thick Fe2O3-ZrO2 composite coating. The purple clay fine powder has a particle size of ≤5μm. The high-temperature binder is silica sol with a solid content of 30%. A quartz sand transition layer with a thickness of 0.3-0.5 mm is set between the inner and outer layers. It is composed of quartz sand with a particle size of 10-20 μm, which is uniformly distributed at the bonding interface. A mechanical interlocking structure is formed through a sintering process, with a bonding strength ≥5 MPa. The sintering process is segmented sintering: In the low-temperature section, the sintering conditions are room temperature - 400℃, heating rate 5℃ / min, holding time for 1 hour, and removal of organic matter. In the intermediate temperature range, the sintering conditions are 400-1000℃, the heating rate is 3℃ / min, the holding time is 2h, and a protective gas of 5% volume concentration of N2 is introduced to achieve crystal transformation. In the high-temperature section, the sintering conditions are 1000-1220℃, heating rate is 2℃ / min, holding time is 3h, and oxygen content is ≤1%, to complete co-sintering, so that the inner and outer layers form a chemical-mechanical dual bond through the quartz sand transition layer.

2. The high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, The preparation method of the inner low-expansion reinforcing layer includes: mixing purple clay ore, rare earth, hydroxylated cordierite powder, mullite particles, sintering aid and deionized water at a mass ratio of 1:0.35-0.4, and after vacuum kneading, aging in an environment with 90% humidity and 25℃ for 20 days to obtain the inner layer clay material; wherein, the vacuum degree of vacuum kneading is -0.09MPa and the kneading time is 20min.

3. The high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, Far-infrared radiation powder, purple clay fine powder and silica sol are mixed and made into functional particles with a particle size of 0.1-0.3mm by spray granulation. Deionized water is added to make an outer layer of clay with a moisture content of 22-25%.

4. The high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, The quartz sand in the transition layer is pre-fired at 1000℃ for 2 hours, with a surface roughness Ra of 1.6-3.2μm. It is then evenly spread on the surface of the inner layer blank, and then covered with an outer layer of clay for composite molding. The dosage is 5-10g / m³. 2 .

5. A high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, The molding method of the composite structure is as follows: a segmented molding process is adopted. First, the inner layer of clay is pressed into shape by a mold at a pressure of 5-10 MPa, and then dried to a moisture content of 10-12%. A quartz sand transition layer is laid on the surface, and then the outer functional layer of clay is wrapped around it. The whole blank is formed by secondary molding at a pressure of 3-5 MPa.

6. The high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, The coefficient of thermal expansion of the inner low-expansion reinforcing layer is ≤3.0×10⁻⁶. -6 / ℃, water absorption rate ≤1.0%, providing a high-temperature impact resistant substrate for the outer functional layer; the outer far-infrared radiation functional layer has an emissivity ≥88% in the 8-15μm band and a thickness of 0.5-1mm.

7. A high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, The inner wall thickness of the teapot body is 2-3mm, the outer wall thickness is 0.5-1mm, and the overall wall thickness is 3-4mm; the spout and the inner substrate are connected by an embedded connection with a connection depth of 5-8mm, and the outer functional layer covers the connection interface to form a sealed transition area.

8. A high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware according to claim 1, characterized in that, The far-infrared radiation functional layer and the inner layer form an interlocking structure, and the quartz sand particles are embedded in the inner and outer matrix to a depth of ≥50μm.

9. A method for preparing a high-performance, low-expansion, far-infrared radiation-functional heat-resistant purple clay teaware as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Preparation of inner layer clay: crush the purple clay ore to 200 mesh, mix it with rare earth, hydroxylated cordierite powder, mullite particles and sintering aid, make slurry at a water-to-material ratio of 0.35:1, and vacuum knead the clay for 20 minutes. (2) Preparation of outer functional particles: far-infrared powder, purple clay fine powder and silica sol are spray granulated to obtain functional particles; (3) Composite molding: After the inner blank is formed, a quartz sand transition layer is laid, and the outer functional layer clay is wrapped around it for secondary molding; (4) Segmented sintering: sintering is completed according to the low temperature debinding, medium temperature protection and high temperature co-sintering system to obtain the finished product.

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