Lead-free and cadmium-free bone china and preparation method thereof

Abstract

The invention belongs to the field of ceramic materials, and particularly relates to lead-free and cadmium-free bone china and a preparation method thereof. The lead-free and cadmium-free bone china is prepared from the following raw materials in parts by weight: 40-50 parts of bone meal, 8-15 parts of feldspar, 6-12 parts of quartz, 5-10 parts of clay, 18-30 parts of kaolin and 6-8 parts of lead-free and cadmium-free glaze. Wherein the lead-free and cadmium-free glaze is independently researched and developed and used for producing a lead-free and cadmium-free bone china finished product, the low thermal expansion coefficient, high wear resistance and chemical stability of the glaze are achieved under the lead-free and cadmium-free condition, the bismuth content is low, and the lead-free and cadmium-free bone china is suitable for low-cost large-scale production of the lead-free and cadmium-free bone china.

Description

Technical Field

[0001] The invention belongs to the field of ceramic materials, and particularly relates to lead-free and cadmium-free bone porcelain and a preparation method thereof. Background Art

[0002] Bone china is a high-end ceramic material that combines excellent mechanical strength, light transmittance, and a delicate glaze. It is widely used in household porcelain, artistic porcelain, and tableware. Traditional bone china is typically made from bone ash as its primary raw material, supplemented with inorganic materials such as quartz and feldspar, and fired at high temperatures. It exhibits advantages such as high whiteness, fine porcelain texture, and excellent transparency. However, to enhance its gloss and glaze stability, some bone china products contain lead and cadmium compounds during the production process. These heavy metals are prone to precipitation under certain conditions, especially in high-temperature and highly acidic and alkaline environments. They may migrate into food or beverages, and long-term ingestion can have adverse effects on human health.

[0003] With the improvement of public health awareness and the increasingly stringent environmental regulations, the development of a lead-free, cadmium-free, environmentally friendly bone china material has become an urgent need for the development of the ceramic industry. At present, some studies have attempted to use lead-free and cadmium-free fluxes to replace traditional lead- and cadmium-containing components, but they still face technical difficulties such as reduced porcelain brightness, narrowed firing temperature range, and insufficient body density. In addition, lead-free bone china also has certain technical bottlenecks in maintaining the transparency, whiteness and mechanical strength of traditional bone china. Therefore, there is an urgent need to provide a bone china with a reasonable formula, excellent performance and no harmful elements such as lead and cadmium, and a preparation method thereof, so as to meet the dual needs of green production and healthy use. Summary of the Invention

[0004] In order to solve the above problems, the present invention independently developed a lead-free and cadmium-free glaze, which achieves a low thermal expansion coefficient, high wear resistance and chemical stability of the glaze without lead or cadmium, and has a low bismuth content, which is suitable for low-cost large-scale production of lead-free and cadmium-free bone porcelain.

[0005] Specifically, the present invention provides a lead-free and cadmium-free bone china, which is made of the following raw materials in parts by weight: 40-50 parts of bone powder, 8-15 parts of feldspar, 6-12 parts of quartz, 5-10 parts of clay, 18-30 parts of kaolin, and 6-8 parts of lead-free and cadmium-free glaze.

[0006] Furthermore, the lead-free and cadmium-free glaze is made of the following raw materials in parts by weight: 5-10 parts of feldspar, 10-20 parts of quartz, 20-30 parts of lead-free and cadmium-free glass powder, and 8-10 parts of kaolin.

[0007] Furthermore, the lead-free and cadmium-free glass powder is made of the following raw materials in mass fraction: SiO2 10-20%, B2O3 32-45%, Bi2O3 5-12%, ZnO 10-22%, ZrO2 8-11%, TiO2 1-3%, Na2O 1-10%, BaO 2-12%, Al2O3 2-8%, and MgO 0.5-3%.

[0008] The synergistic use of ZrO2 and TiO2 in the lead- and cadmium-free bone china glass powder formulation of this invention is the key to achieving a low coefficient of thermal expansion. As a structural rigidity-enhancing component, ZrO2 forms stable Zr-O bonds with oxygen ions in tetrahedral or octahedral coordination during the glass melting and cooling processes. These high bond energy and minimal thermal motion significantly enhance the overall rigidity of the glass structure and inhibit thermal deformation.

[0009] At the same time, ZrO2 may also form microcrystals or metastable phases under appropriate conditions, playing a role of "microcrack passivation", alleviating internal stress accumulation, and further reducing the thermal expansion coefficient of the material. TiO2, as a network regulator, participates in the rearrangement and optimization of the glass structure. Its smaller ionic radius allows it to replace part of Si 4+ or B 3+ , increasing local structural density and forming nanocrystalline nuclei within the glass, enhancing microscopic skeleton strength and thermal shock stability. The synergistic effect of these two factors significantly reduces the thermal expansion coefficient of the glass during sintering, making the structure more dense and stable.

[0010] Among the fundamental components of the glass's main structure, SiO2 and B2O3 form the primary network framework. SiO2, in the form of SiO4 tetrahedra, provides a stable three-dimensional skeleton, fundamental to the glass's strength and heat resistance. However, due to its high melting point and poor fluidity, its content in the present invention is controlled to a low to moderate level of 10-20%, helping to balance processing difficulties. B2O3, a network optimizer, can be present in amounts as high as 32-45%. It exists in the glass as two structural units, BO3 and BO4, and undergoes a conversion from BO3 to BO4 during cooling. This reversible structural change absorbs stress and buffers volume changes, serving as a key mechanism for controlling thermal expansion behavior. Furthermore, B2O3 forms numerous BOB and BO-Si bridges, creating a flexible and continuous network structure that enhances the glass's thermal stability and forming uniformity. To prevent excessive network flexibility from leading to insufficient strength, the present invention employs high-strength oxides such as ZrO2 and Al2O3 for synergistic adjustment, thereby enhancing thermal performance while maintaining overall structural strength.

[0011] In addition, the introduction of Bi2O3 is intended to improve the fluidity and visual performance of the glaze. Bi2O3 is a high-density, high-refractive-index oxide that exists mainly in the form of Bi-O polyhedrons in the glass structure. It can be inserted between Si-O or BO bridge bonds to form structural gaps, reduce local rigidity, and improve the fluidity and glazing performance of the glass. However, the thermal movement freedom of Bi-O bonds is large, which may cause the glass expansion coefficient to increase at high content. Therefore, in the present invention, the Bi2O3 content is controlled within the range of 5-12%, preferably 5-8%, and is used in combination with structural reinforcement components such as ZrO2 and Al2O3 to achieve a balance between fluxing and resistance to thermal deformation. Bi2O3 also has an excellent fluxing effect, can reduce the melting temperature, improve the sintering efficiency of the glaze, is suitable for large-scale industrial preparation, and contributes to the coordinated optimization of product performance and process costs.

[0012] Furthermore, the total mass fraction of the above raw materials is 100%.

[0013] Furthermore, the mass ratio of Al2O3 to MgO is 2-3:1.

[0014] Furthermore, the ratio of the mass of SiO2 to the total mass of Al2O3 and MgO is 3-4:1.

[0015] Furthermore, the ratio of the total mass of B2O3 and Bi2O3 to the total mass of ZnO, ZrO2 and TiO2 is 2:1.

[0016] Furthermore, the lead-free and cadmium-free glass powder is prepared as follows: SiO2, Al2O3, and MgO are weighed respectively according to the formula ratio, ground and mixed, and then the remaining raw materials are weighed respectively, mixed evenly, and kept warm at 980-1150°C for 10-30 minutes, and the molten material is poured into cold water to quench to obtain a glass frit; the glass frit is rolled into granules, and then ball-milled, sieved, and dried to obtain the product.

[0017] To achieve high wear resistance for the bone china glaze and internal structure, the present invention employs a multi-component composite reinforcement system consisting of ZrO2, Al2O3, and MgO. ZrO2 exists in a stable crystalline or metastable microcrystalline phase at high temperatures, exhibiting high hardness and resistance to crack propagation. It can form a microcrack passivation zone within the material, enhancing its resistance to wear and impact loads.

[0018] Al2O3 is a common high-hardness oxide with a high melting point and strong thermal stability. It can act as a skeleton strengthener in the glass network to significantly improve the microstructural rigidity and surface scratch resistance of the glass. Its presence can also inhibit the excessive flow of the glass liquid phase, helping to form a dense and tough material surface during the sintering process.

[0019] MgO acts as a flux structure regulator during the high-temperature sintering stage, promoting ion diffusion and dense sintering process between oxides, improving the bonding degree of the glassy intermediate phase, and helping to form a dense, uniform, and structurally stable wear-resistant phase region.

[0020] In addition, the introduction of appropriate amounts of quartz and kaolin into the glaze system also plays a key role in wear resistance. As a filler with high hardness and strong chemical stability, quartz is not easy to completely melt during the glaze firing process. Instead, it is partially retained as a fine crystal or sub-grain structure, forming reinforcement points distributed inside the glaze layer, thereby improving the glaze's scratch resistance. Kaolin undergoes dehydroxylation and phase change processes at high temperatures to produce high-hardness minerals such as mullite, while enhancing the bonding strength and surface density of the glaze layer. The synergistic ratio between quartz and kaolin ensures that the glaze layer has high wear and impact resistance without sacrificing transparency and decorative effects.

[0021] In order to further improve the uniformity and density of the finished glaze, the present invention also uses ball milling (multi-stage screening to 300 mesh) and high-frequency magnetic separation (at least 5 times) processes to effectively remove iron-containing impurities and other components that may affect the smoothness and wear resistance of the glaze layer. The glaze slurry obtained by fine treatment has greatly improved fluidity and wrapping properties, which is conducive to the formation of a glazing layer with continuous structure and uniform distribution. In the subsequent sintering process, the glaze layer is controlled to a thickness of 0.2-0.25mm and glaze firing is carried out in the range of 1050-1150℃, so that the glass powder in the glaze can smoothly complete the glass phase transition, pore closure and surface self-leveling process, and finally form a dense, smooth, crack-free transparent glaze film, which significantly improves the wear resistance and service life of the surface of bone porcelain products.

[0022] Furthermore, the obtained glass frit is dried at 90-100° C. for 5-8 hours before rolling.

[0023] Furthermore, the ball milling is performed at a rotation speed of 600 r / min for 30 to 60 min.

[0024] Furthermore, the screening is performed using a 200-400 mesh sieve.

[0025] Furthermore, the lead-free and cadmium-free glaze is prepared as follows: the required weight portions of feldspar, quartz and kaolin are respectively crushed to a fineness of 200 mesh, mixed with lead-free and cadmium-free glass powder to obtain a glaze mixture, and wet-ground in a ball mill according to a ratio of glaze mixture: ball: water = 1: (1.5-2): 0.7. The obtained glaze slurry is sequentially passed through a 180-mesh sieve, a 250-mesh sieve, and a 300-mesh sieve, and the sieve residue is selected more than five times using a high-intensity wet magnetic separator to remove iron substances.

[0026] Furthermore, the lead-free and cadmium-free glaze may further comprise 0.1-5 parts by weight of lead-free and cadmium-free pigments.

[0027] As used herein, lead-free, cadmium-free pigments may include composite inorganic pigments from several major classes, including corundum-hematite, olivine, halogenite, pyrochlore, rutile, spinel, and spinel, although other species such as baddeleyite, borate, garnet, periclase, berylite, phosphate, titanite, and zircon are also suitable in certain applications. Oxides of the metals cobalt, chromium, magnesium, praseodymium, iron, nickel, and copper are generally useful. In particular, specific pigments include cobalt silicate blue olivine Co2SiO4; nickel barium titanium pale yellow rutile 2NiO:3BaO:17TiO2; nickel antimony titanium rutile (Ti, Ni, Sb)O2; nickel niobium titanium rutile (Ti, Ni, Nb)O2; nickel tungsten titanium rutile (Ti, Ni, W)O2; chromium antimony titanium rutile (Ti, Cr, Sb)O2; chromium niobium titanium rutile (Ti, Cr, Ni)O2; chromium tungsten titanium rutile (Ti, Cr, W)O2; manganese antimony titanium rutile (Ti, Mn, Sb)O2; titanium vanadium antimony gray rutile (Ti, V, Sb)O2; manganese chromium antimony titanium brown rutile (Ti, Mn, Cr, Sb)O2; manganese niobium titanium brown rutile (Ti, Mn, Ni)O2; cobalt aluminate blue spinel CoAl2O4 ; Zinc-chromium-cobalt-aluminum spinel (Zn, Co)(Cr, Al)2O4; Cobalt chromate blue-green spinel CoCr2O4; Cobalt titanate green spinel Co2TiO4; Iron-chromium brown spinel Fe(Fe, Cr)2O4; Iron-titanium brown spinel Fe2TiO4; Nickel ferrite brown spinel NiFe2O4; Zinc ferrite brown spinel (Zn, Fe)Fe2O4; Zinc-iron-chromium brown spinel (Zn, Fe)(Fe, Cr)2O4; Copper chromite black spinel CuCr2O4; Iron-cobalt-chromium black spinel (Co, Fe)(Fe, Cr)2O4; Chrome-iron-manganese brown spinel (Fe, Mn)(Cr, Fe)2O4; Chrome-iron-nickel black spinel (Ni, Fe)(Cr, Fe)2O4; and Chrome-manganese-zinc brown spinel (Zn, Mn)(Cr2O4).

[0028] The present invention also provides a preparation method for lead-free and cadmium-free bone china, which comprises the following steps: adding bone powder, feldspar, quartz, clay and kaolin in required weight proportions and water of the same weight into a ball mill and milling the mixture; then sieving, aging and molding the mixture to obtain a green body; and bisque-firing, glazing and glaze-firing the green body and then naturally cooling the green body to obtain the bone china.

[0029] Furthermore, the biscuit firing is carried out at 1250-1300° C. for 3-6 hours.

[0030] Furthermore, the glazing spraying pressure is 0.2-0.3 MPa, and the glaze layer thickness is 0.2-0.25 mm.

[0031] Furthermore, the glaze firing is carried out at 1100-1200° C. for 1-3 hours.

[0032] Beneficial effects of the invention: The present invention provides an environmentally friendly bone china material that does not contain lead or cadmium and a preparation method thereof, which overcomes the safety hazards brought about by the use of heavy metal fluxes in traditional bone china. While ensuring the whiteness, glossiness and mechanical strength of the porcelain, it achieves a comprehensive performance improvement of low expansion coefficient and high wear resistance.

[0033] Specifically, by optimizing the composition of the glass powder and rationally introducing various high-strength oxides such as ZrO2, TiO2, Al2O3, and MgO, a stable glass network structure with a microcrystalline strengthening effect is constructed, effectively reducing the material's thermal expansion coefficient and improving its structural integrity and resistance to thermal shock during firing. Furthermore, the synergistic effect of quartz and kaolin in the glaze formula creates a dense and hard glaze layer. Assisted by multiple screening and magnetic separation purification processes, this significantly enhances the surface wear resistance and service life.

[0034] Furthermore, the present invention utilizes rapid quenching to prepare glass powder, low-temperature, long-duration bisque firing, and staged, temperature-controlled glaze firing to further optimize the bond strength and density between the green body and glaze layer, effectively suppressing cracking and expansion during sintering. This overall preparation process enables industrial production, is simple to operate, environmentally friendly, and produces highly stable finished products. It is particularly suitable for applications such as tableware and household porcelain, where heavy metal release is strictly controlled, and has broad market application prospects and promotional value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of comparative test results of wear resistance of the present invention; Figure 2 Schematic diagram of the comparative test results of thermal expansion coefficient of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to specific examples, which, however, are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0037] Example 1 Preparation of lead-free and cadmium-free glass powder: The lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 12%, B2O3 38%, Bi2O3 12%, ZnO 15%, ZrO2 8%, TiO2 2%, Na2O 3.5%, BaO 6%, Al2O3 2.5%, and MgO 1%, and is prepared as follows: SiO2, Al2O3, and MgO are weighed respectively according to the formula ratio, ground, and mixed, and then the remaining raw materials are weighed respectively, mixed evenly, and kept warm at 1100°C for 30 minutes, and the molten material is poured into cold water for quenching to obtain a glass frit; the glass frit is dried at 90°C, rolled into granules, ball-milled at a speed of 600 r / min for 30 minutes, passed through a 300-mesh sieve, and dried to obtain the glass frit.

[0038] Preparation of lead-free and cadmium-free glaze: 8 parts of feldspar, 14 parts of quartz and 8 parts of kaolin are respectively ground to a fineness of 200 mesh by weight, and mixed with 25 parts of lead-free and cadmium-free glass powder to obtain a glaze mixture, which is wet-milled in a ball mill at a ratio of glaze mixture: balls: water = 1:2:0.7. The obtained glaze slurry is sequentially passed through a 180-mesh sieve, a 250-mesh sieve, and a 300-mesh sieve. The sieve residue is separated by a high-intensity wet magnetic separator five times to remove iron substances, thereby obtaining the glaze.

[0039] Preparation of lead-free and cadmium-free bone china: It is made of the following raw materials in parts by weight: 45 parts of bone powder, 10 parts of feldspar, 10 parts of quartz, 8 parts of clay, 22 parts of kaolin, and 8 parts of lead-free and cadmium-free glaze, and is prepared as follows: the required parts by weight of bone powder, feldspar, quartz, clay and kaolin and the same weight of water are added to a ball mill, ball milled for 3 hours, and then passed through a 100-mesh sieve to obtain a sieved material, and the sieved material is left to age for 3 days to obtain a blank, and the blank is injected into a mold to form a blank, and the blank is placed in a kiln and fired at 1300°C for 3 hours, during which high-fire insulation is appropriately performed, and the obtained bisque-fired blank is glazed using the prepared lead-free and cadmium-free glaze by a glaze spraying method, the glaze slurry has a specific gravity of 1.50, the glaze spraying pressure is 0.3 MPa, and the glaze layer thickness is 0.2 mm. The glazed product is fired at 1100°C for 2 hours and naturally cooled to room temperature to obtain bone china.

[0040] Example 2 Preparation of lead-free and cadmium-free glass powder: The lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 20%, B2O3 43%, Bi2O3 5%, ZnO 12%, ZrO2 10%, TiO2 2%, Na2O 1%, BaO 2%, Al2O3 3.75%, and MgO 1.25%, and is prepared as follows: SiO2, Al2O3, and MgO are weighed respectively according to the formula ratio, ground, and mixed, and then the remaining raw materials are weighed respectively, mixed, and kept warm at 1100°C for 30 minutes, and the molten material is poured into cold water for quenching to obtain a glass frit; the glass frit is dried at 90°C, rolled into granules, ball-milled at a speed of 600 r / min for 30 minutes, passed through a 300-mesh sieve, and dried to obtain the glass frit.

[0041] Preparation of lead-free and cadmium-free glaze: 10 parts of feldspar, 20 parts of quartz and 10 parts of kaolin are respectively ground to a fineness of 200 mesh by weight, and mixed with 20 parts of lead-free and cadmium-free glass powder to obtain a glaze mixture, which is wet-milled in a ball mill at a ratio of glaze mixture: balls: water = 1:2:0.7. The obtained glaze slurry is sequentially passed through a 180-mesh sieve, a 250-mesh sieve, and a 300-mesh sieve. The sieve residue is separated five times by a high-intensity wet magnetic separator to remove iron, thereby obtaining the glaze.

[0042] Preparation of lead-free and cadmium-free bone china: It is made of the following raw materials in parts by weight: 45 parts of bone powder, 10 parts of feldspar, 10 parts of quartz, 8 parts of clay, 22 parts of kaolin, and 6 parts of lead-free and cadmium-free glaze, and is prepared as follows: the required parts by weight of bone powder, feldspar, quartz, clay and kaolin and the same weight of water are added to a ball mill, ball milled for 3 hours, and then passed through a 100-mesh sieve to obtain a sieved material, and the sieved material is left to age for 3 days to obtain a blank, which is injected into a mold to form a blank, and the blank is placed in a kiln and fired at 1300°C for 3 hours, during which high-fire insulation is appropriately performed, and the obtained bisque-fired blank is glazed using the prepared lead-free and cadmium-free glaze by a glaze spraying method, the glaze slurry has a specific gravity of 1.50, the glaze spraying pressure is 0.3 MPa, and the glaze layer thickness is 0.2 mm. The glazed product is fired at 1100°C for 2 hours and naturally cooled to room temperature to obtain bone china.

[0043] Comparative Example 1 Preparation of lead-free and cadmium-free glass powder: The same as Example 1, except that the lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 11.5%, B2O3 38%, Bi2O3 12%, ZnO 15%, ZrO2 8%, TiO2 2%, Na2O 3.5%, BaO 6%, Al2O3 3.5%.

[0044] Preparation of lead-free and cadmium-free glaze: same as Example 1.

[0045] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1.

[0046] Comparative Example 2 Preparation of lead-free and cadmium-free glass powder: The same as Example 1, except that the lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 11.5%, B2O3 38%, Bi2O3 12%, ZnO 15%, ZrO2 8%, TiO2 2%, Na2O 3.5%, BaO 6%, Al2O3 2%, MgO 2%.

[0047] Preparation of lead-free and cadmium-free glaze: Same as Example 1.

[0048] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1.

[0049] Comparative Example 3 Preparation of lead-free and cadmium-free glass powder: The same as Example 1, except that the lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 12%, B2O3 35%, Bi2O3 12%, ZnO 22%, Na2O 3.5%, BaO 6%, Al2O3 2.5%, MgO 1%.

[0050] Preparation of lead-free and cadmium-free glaze: Same as Example 1.

[0051] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1.

[0052] Comparative Example 4 Preparation of lead-free and cadmium-free glass powder: The same as Example 1, except that the lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 12%, B2O3 32%, Bi2O3 10%, ZnO 20%, ZrO2 10%, TiO2 3%, Na2O 3.5%, BaO 6%, Al2O3 2.5%, MgO 1%.

[0053] Preparation of lead-free and cadmium-free glaze: Same as Example 1.

[0054] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1.

[0055] Comparative Example 5 Preparation of lead-free and cadmium-free glass powder: The same as Example 1, except that the lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 35%, B2O3 22%, Bi2O3 10%, ZnO 10%, ZrO2 8%, TiO2 2%, Na2O 3.5%, BaO 6%, Al2O3 2.5%, MgO 1%.

[0056] Preparation of lead-free and cadmium-free glaze: Same as Example 1.

[0057] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1.

[0058] Comparative Example 6 Preparation of lead-free and cadmium-free glass powder: Same as Example 1, except that the TiO2 in the raw materials is replaced by ZrO2. During the preparation process, it was found that the melting temperature needed to be increased to 1150°C for complete melting.

[0059] Preparation of lead-free and cadmium-free glaze: same as Example 1.

[0060] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1.

[0061] Comparative Example 7 Preparation of lead-free and cadmium-free glass powder: Same as Example 1, except that the ZrO2 in the raw materials is replaced by TiO2. During the preparation process, it was found that the melting temperature needed to be increased to 1250°C for complete melting.

[0062] Preparation of lead-free and cadmium-free glaze: same as Example 1.

[0063] Preparation of lead-free and cadmium-free bone porcelain: Same as Example 1, except that the glaze surface was found to be white during the preparation process.

[0064] Test Case The thermal expansion coefficients of the bone china products of Examples 1-2 and Comparative Examples 1-5 were tested, and their wear resistance was tested under conventional conditions and under damp heat and acid decay conditions (one cycle: 10% humidity, 55°C temperature, 24 hours, followed by another 2% acid decay condition for 24 hours, repeated 10 times). The test results are shown in Table 1.

[0065] Table 1: Performance test results of bone china products of Examples 1-2 and Comparative Examples 1-5: Based on the experimental data in Table 1, we can get Figure 1 Schematic diagram of the wear resistance comparison test and the thermal expansion coefficient comparison test schematic diagram of 2.

[0066] From Table 1, Figure 1 and Figure 2 The results show that when the lead-free and cadmium glass powder raw material does not contain MgO (Comparative Example 1) or the mass ratio of SiO2, Al2O3 and MgO is not within the specific range (Comparative Example 2), the chemical stability of the bone china product is poor. When the lead-free and cadmium glass powder raw material does not contain ZrO2 and TiO2 (Comparative Example 3) or the mass ratio of B2O3, Bi2O3, ZnO, ZrO2, and TiO2 is not within the specific range (Comparative Example 4), the wear resistance and chemical stability of the bone china product are both poor. When the lead-free and cadmium glass powder raw material contains a large amount of SiO2 (Comparative Example 5), the thermal expansion coefficient of the bone china product is significantly increased due to the corresponding reduction in the content of other key components.

[0067] It should be noted that the preferred embodiments of the present invention are given in the description of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this description. These embodiments are not intended to be additional limitations on the content of the present invention. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. In addition, the above-mentioned technical features are further combined with each other to form various embodiments not listed above, which are all considered to be within the scope of the description of the present invention. Furthermore, it is obvious to those skilled in the art that improvements or changes can be made based on the above description, and all such improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A lead-free and cadmium-free bone china, characterized in that: The bone china is made of the following raw materials in parts by weight: 40-50 parts of bone powder, 8-15 parts of feldspar, 6-12 parts of quartz, 5-10 parts of clay, 18-30 parts of kaolin, and 6-8 parts of lead-free and cadmium-free glaze; wherein the kaolin and quartz in the above proportions form a crystal skeleton structure during the high-temperature sintering and densification process.

2. The lead-free and cadmium-free bone china according to claim 1, characterized in that: The lead-free and cadmium-free glaze is prepared from the following raw materials in parts by weight: 5-10 parts of feldspar, 10-20 parts of quartz, 20-30 parts of lead-free and cadmium-free glass powder, and 8-10 parts of kaolin.

3. The lead-free and cadmium-free bone china according to claim 2, characterized in that: The lead-free and cadmium-free glass powder is made of the following raw materials in mass fractions: SiO2 10-20%, B2O3 32-45%, Bi2O3 5-12%, ZnO 10-22%, ZrO2 8-11%, TiO2 1-3%, Na2O 1-10%, BaO 2-12%, Al2O3 2-8%, and MgO 0.5-3%; Among them, the B2O3, ZnO and Na2O in the said proportion form a glass network main structure during the high-temperature sintering and densification process; the ZrO2 and TiO2 in the said proportion jointly form a high-strength microcrystalline structure during the high-temperature sintering and densification process; and Bi2O3 regulates fluidity during the high-temperature sintering and densification process.

4. The lead-free and cadmium-free bone china according to claim 3, characterized in that: The mass ratio of Al2O3 to MgO is 2-3:1; the ratio of the mass of SiO2 to the total mass of Al2O3 and MgO is 3-4:1; The ratio of the total mass of B2O3 and Bi2O3 to the total mass of ZnO, ZrO2 and TiO2 is 2:

1.

5. The lead-free and cadmium-free bone china according to claim 3 or 4, characterized in that: The lead-free and cadmium-free glass powder is prepared as follows: SiO2, Al2O3, and MgO are weighed respectively according to the formula ratio, ground and mixed, and then the remaining raw materials are weighed respectively, mixed evenly, and kept warm at 980-1150°C for 10-30 minutes, and the molten material is poured into cold water for quenching to obtain a glass frit, wherein the molten material forms an amorphous structure during the rapid quenching process; the glass frit is rolled into granules, and then ball-milled, sieved, and dried to obtain the obtained product.

6. The lead-free and cadmium-free bone china according to claim 2, characterized in that The method for preparing the lead-free and cadmium-free glaze comprises: grinding the feldspar, quartz, and kaolin to 200 mesh respectively, mixing them with the glass powder in proportion, wet ball milling under the condition of glaze: ball: water = 1: (1.5-2): 0.7, filtering through 180 mesh, 250 mesh, and 300 mesh sieves in sequence, and then using a high-intensity wet magnetic separator to remove iron impurities at least five times to obtain a high-purity glaze slurry.

7. The lead-free and cadmium-free bone china according to claim 2, characterized in that: The lead-free and cadmium-free glaze further comprises 0.1-5 parts by weight of lead-free and cadmium-free pigments.

8. A method for preparing lead-free and cadmium-free bone china according to any one of claims 1 to 7, characterized in that: The process comprises the following steps: adding bone powder, feldspar, quartz, clay and kaolin in required weight proportions and water of the same weight into a ball mill, grinding the mixture, sieving, aging and forming the mixture to obtain a green body; bisque-firing the green body, glazing the green body, glaze-firing the green body and then naturally cooling the green body to obtain the bone china.

9. The preparation method according to claim 8, characterized in that The biscuit firing is carried out at 1250-1300° C. for 3-6 hours; The glaze spraying pressure is 0.2-0.3MPa, and the glaze layer thickness is 0.2-0.25mm; The glaze firing is carried out at 1050-1150° C. for 1-3 hours.

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