Lead-free environment-friendly white oil crack ceramic glaze and application method thereof

Abstract

The application discloses a lead-free environment-friendly white oily crack ceramic glaze and an application method thereof. The raw material formula of the ceramic glaze comprises the following components in percentage by weight: 28-35wt% of sodium feldspar, 5-8wt% of Suzhou kaolin, 9-19wt% of quartz, 4-10wt% of calcite, 5-10wt% of barium carbonate, 18-25wt% of talc, 0.5-16wt% of sodium carbonate, 1.4-2wt% of ZnO, and 2-6wt% of adamellite additionally. The application method comprises the following steps: step one, preparing ceramic glaze powder; step two, mixing and ball milling; step three, glaze pulp mesh screening and aging to obtain glaze; and step four, applying the glaze on the surface of a body, drying, and firing in a reducing atmosphere to obtain a ceramic glaze decoration product. The ceramic glaze surface has high whiteness, high hardness and unique decoration effect, the preparation process is simple, the energy consumption is low, the product does not contain heavy metals such as lead, and meets the green environmental protection requirements.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, and in particular to a lead-free, environmentally friendly white oil-based crackle ceramic glaze and its application method. Background Technology

[0002] The traditional Chinese crackle glaze technique can be traced back to the "golden threads and iron wires" of the Ge kiln in the Song Dynasty, whose natural crackle texture is hailed as "ink painting in porcelain." During the Ming and Qing Dynasties, Jingdezhen developed a crackle glaze that, through a high-silica-alumina formula and controlled cooling shrinkage, created a unique ice-crack effect with oriental aesthetics. However, traditional processes often use lead-containing fluxes to lower the melting point (lead content reaches 15-20%), which faces the need for technological innovation under contemporary environmental standards. Kyocera Corporation of Japan developed KYOCERA lead-free crackle glaze using a zinc-titanium composite system to achieve low-temperature rapid firing at 800℃, but it suffers from insufficient glaze hardness (Mohs hardness <5). Villeroy & Boch of Germany achieved stable crackles through a borate system, but boron is listed in the "List of Key Controlled New Pollutants." Although the Sanhuan Group in China has established a pilot production line for lead-free glaze, the color purity (whiteness <70) and crackle uniformity of its white crackle glaze still need improvement. Compared with existing technologies (e.g., CN109180156A lacks clear key performance indicators, and CN110156330A has a complex process), the core of this invention lies in constructing a novel glaze system with nepheline syenite as the stress-regulating core and synergistically using a ternary inducer of talc, sodium carbonate, and zinc oxide. In this system, nepheline syenite, with its unique "alkali excess" structure, can rapidly release free alkali at high temperatures, efficiently regulating the thermal expansion of the glaze layer and providing a basis for the formation of a three-dimensional crack network. Talc, activated by sodium carbonate and guided by zinc oxide, can effectively release active magnesium and silicon species. Zinc oxide, as a key reactive component, directly participates in the construction of functional crystals rather than playing a physical masking role. Through the synergy of the components, uniformly dispersed micro- and nano-crystals are ultimately generated in situ in the glaze surface, thereby simultaneously achieving excellent comprehensive performance of high whiteness, high hardness, and oily luster. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-cost, simple-process, high-performance lead-free environmentally friendly white oil-based crackle ceramic glaze and its application method.

[0004] This invention is achieved through the following technical solution:

[0005] A lead-free, environmentally friendly white oil-based crackle ceramic glaze, characterized in that: the raw material formula of the ceramic glaze is composed of the following weight percentages: 28-35 wt% sodium feldspar, 5-8 wt% Suzhou kaolin, 9-19 wt% quartz, 4-10 wt% calcite, 5-10 wt% barium carbonate, 18-25 wt% talc, 0.5-16 wt% sodium carbonate, 1.4-2 wt% ZnO, plus 2-6 wt% nepheline syenite.

[0006] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0007] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze is characterized by the following steps:

[0008] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0009] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.5~1.8: 0.6~0.8, and mix and ball mill.

[0010] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0011] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0012] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 8-12 hours.

[0013] The residue after sieving in step three is 0.05-0.07%.

[0014] The aging process in step three takes 24 to 48 hours.

[0015] The total firing time for step four is 12–16 hours. Specifically, the process involves first uniformly raising the kiln temperature from room temperature to 1020°C under an oxidizing atmosphere for 6 hours; then uniformly raising the kiln temperature from 1020°C to a maximum firing temperature of 1290–1330°C under a reducing atmosphere, and holding at this maximum firing temperature for 1–3 hours. Step four yields a glaze with a whiteness of 80–85% and a hardness of 785–854 kgf / mm². 2 Mohs hardness 5.0 to 5.5.

[0016] Step four results in a uniformly distributed network of cracks on the glaze surface of the product, with a crack width of 0.1–0.3 mm and a crack density of 1–6 cracks / dm². 2 .

[0017] Step four results in a product glaze with an oily sheen.

[0018] The present invention has the following beneficial effects:

[0019] (1) This invention successfully prepared a lead-free, environmentally friendly white oil-based crackle glaze, solving the environmental pollution and health risks caused by the reliance on lead-containing fluxes in traditional crackle glazes. Through precise matching design of the body and glaze expansion coefficients, this glaze can form stable, uniform, and highly decorative oil-based crackles in a single firing, significantly improving the reliability and artistic value of environmentally friendly crackle glaze products;

[0020] (2) Compared with other crackle glazes, the lead-free environmentally friendly white oily crackle glaze prepared by this invention has a simple preparation method and good repeatability. By controlling specific components and ratios, barium feldspar, spinel and other crystals are first precipitated in situ in a high-viscosity liquid phase using an inducing agent. This not only enhances the whiteness and oiliness by diffuse reflection of light, but also further improves the hardness of the glaze surface due to the precipitation of fine crystals. The ceramic glaze of this invention is inexpensive and easy to industrialize. The glaze surface achieves beautiful crackle patterns while also possessing high whiteness and high hardness, making it highly practical and in line with the national advocacy of green, safe and high-quality development in the manufacturing industry.

[0021] (3) The core innovation of this invention lies in constructing a novel glaze reaction system with nepheline syenite as the stress regulation core and synergistic talc-sodium carbonate-zinc oxide ternary inducer, thereby achieving a significant improvement in glaze performance. The process of releasing alkali metal ions during the melting of traditional potassium / sodium feldspar is relatively mild and gradual, and its ability to regulate the thermal expansion coefficient of the glaze is limited; while nepheline syenite has a structural "alkali excess" due to the significantly greater than 1:1 molar ratio of (Na,K)2O to Al2O3 in its crystal structure. During the high-temperature melting process, these alkali metal ions that are not completely neutralized can be released rapidly and in a concentrated manner in a "quasi-free" state, efficiently breaking the silicon-oxygen network, thereby achieving precise and enhanced regulation of the thermal expansion coefficient of the glaze layer, providing a fundamental driving force for the formation of a stable and three-dimensional crack network. At the same time, the role of talc in this invention is not simply to introduce a magnesium source, but under the low-temperature activation of sodium carbonate and the directional guidance of zinc oxide, its layered structure is efficiently dissociated, releasing highly active magnesium and silicon species, which then react synergistically with zinc oxide. Here, zinc oxide is not merely used as a physical opacifier or emulsifier, but actively participates in the crystal chemical reaction as a key building block, partially entering the final crystal lattice and becoming part of the functional crystal. In the magnesium-, silicon-, and sodium-rich reaction field created by talc activated by sodium carbonate, Zn²⁺, with its unique electronic structure and coordination tendency, preferentially coordinates with specific silicon-oxygen units and magnesium ions, thereby thermodynamically guiding and stabilizing the nucleation of specific crystal phases (such as zinc-containing spinel structures or zinc-barium silicate phases). Zinc oxide particles or their initial dissolution products can serve as effective heterogeneous nucleation sites, significantly reducing the nucleation barrier of the target crystal phase, leading to a substantial increase in the number of crystal nuclei, controlling the crystal size to the submicron or nanometer level, and ultimately forming a fine, diffuse, and uniformly distributed crystal network. This microstructure is the direct physical basis for achieving high diffuse light reflection (presenting a high-white, oily visual texture) and high surface hardness. Ultimately, in the specific melt environment created by nepheline syenite, the in-situ and dispersed precipitation of functional crystals was achieved through an inseparable chain reaction among the components, thereby simultaneously endowing the glaze with comprehensive excellent properties such as high whiteness, high hardness and oily luster. Attached Figure Description

[0022] Figure 1 This is a photograph of the product obtained in Embodiment 1 of the present invention;

[0023] Figure 2 This is a photograph of the product obtained in Embodiment 2 of the present invention;

[0024] Figure 3 This is a photograph of the product obtained in Embodiment 3 of the present invention;

[0025] Figure 4 This is a photograph of the product obtained in Embodiment 4 of the present invention;

[0026] Figure 5These are photographs of the products obtained in Comparative Examples 1-5 of this invention. Detailed Implementation

[0027] To further illustrate the present invention, the technical means and effects adopted to achieve the intended purpose of the invention, the present invention will be described in detail below with reference to preferred embodiments.

[0028] Example 1

[0029] A lead-free, environmentally friendly white oil-based crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 34wt% sodium feldspar, 5wt% Suzhou kaolin, 9wt% quartz, 4wt% calcite, 6wt% barium carbonate, 25wt% talc, 15.5wt% sodium carbonate, 1.5wt% ZnO, plus 2wt% nepheline syenite.

[0030] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0031] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0032] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0033] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.5: 0.8, and mix and ball mill.

[0034] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0035] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0036] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 8 hours.

[0037] The residue on the sieve after sieving in step three is 0.05%.

[0038] The aging process in step three takes 24 hours.

[0039] The total firing time for step four is 14 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1290°C under a reducing atmosphere, and the maximum firing temperature is held for 1 hour.

[0040] Step four yields a product glaze with a whiteness of 80% and a hardness of 785 kgf / mm². 2 Mohs hardness 5.1.

[0041] Step four results in a uniformly distributed network of cracks on the glaze surface of the product, with a crack width of 0.1 mm and a crack density of 1 crack / dm². 2 .

[0042] Step four results in a product glaze with an oily sheen.

[0043] Example 2:

[0044] A lead-free, environmentally friendly white oily crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 33wt% sodium feldspar, 8wt% Suzhou kaolin, 12wt% quartz, 6wt% calcite, 8wt% barium carbonate, 18wt% talc, 13.6wt% sodium carbonate, 1.4wt% ZnO, plus 4wt% nepheline syenite.

[0045] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0046] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0047] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0048] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.8: 0.6, and mix and ball mill.

[0049] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0050] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0051] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 12 hours.

[0052] The residue after sieving in step three is 0.06%.

[0053] The aging process in step three takes 25 hours.

[0054] The total firing time for step four is 13 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1300°C under a reducing atmosphere, and the maximum firing temperature is held for 2 hours.

[0055] Step four yields a product glaze with a whiteness of 83% and a hardness of 854 kgf / mm². 2 Mohs hardness 5.3.

[0056] Step four results in a uniformly distributed network of cracks on the glaze surface of the product, with a crack width of 0.2 mm and a crack density of 3 cracks / dm². 2 .

[0057] Step four results in a product glaze with an oily sheen.

[0058] Example 3:

[0059] A lead-free, environmentally friendly white oily crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 32wt% sodium feldspar, 6wt% Suzhou kaolin, 10wt% quartz, 8wt% calcite, 10wt% barium carbonate, 19wt% talc, 13.4wt% sodium carbonate, 1.6wt% ZnO, plus 5wt% nepheline syenite.

[0060] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0061] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0062] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0063] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.6: 0.7, and mix and ball mill.

[0064] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0065] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0066] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 10 hours.

[0067] The residue after sieving in step three is 0.07%.

[0068] The aging process in step three takes 26 hours.

[0069] The total firing time for step four is 14 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1310°C under a reducing atmosphere, and the maximum firing temperature is held for 3 hours.

[0070] Step four yields a product with a glaze whiteness of 84% and a hardness of 800 kgf / mm². 2 Mohs hardness 5.2.

[0071] Step four results in a uniformly distributed network of cracks on the product's glaze surface, with a crack width of 0.3 mm and a crack density of 5 cracks / dm². 2 .

[0072] Step four results in a product glaze with an oily sheen.

[0073] Example 4:

[0074] A lead-free, environmentally friendly white oil-based crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 30wt% sodium feldspar, 5wt% Suzhou kaolin, 12wt% quartz, 10wt% calcite, 9wt% barium carbonate, 18wt% talc, 14.6wt% sodium carbonate, 1.4wt% ZnO, plus 6wt% nepheline syenite.

[0075] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0076] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0077] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0078] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.5: 0.65, and mix and ball mill.

[0079] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0080] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0081] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 12 hours.

[0082] The residue after sieving in step three is 0.07%.

[0083] The aging process in step three takes 36 hours.

[0084] The total firing time for step four is 16 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1320°C under a reducing atmosphere, and the maximum firing temperature is held for 2 hours.

[0085] Step four yields a product glaze with a whiteness of 85% and a hardness of 840 kgf / mm². 2 Mohs hardness 5.0.

[0086] Step four results in a uniformly distributed network of cracks on the product's glaze surface, with a crack width of 0.1 mm and a crack density of 6 cracks / dm². 2 .

[0087] Step four results in a product glaze with an oily sheen.

[0088] Example 5:

[0089] A lead-free, environmentally friendly white oily crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 35wt% sodium feldspar, 8wt% Suzhou kaolin, 14wt% quartz, 7wt% calcite, 5wt% barium carbonate, 20wt% talc, 9.5wt% sodium carbonate, 1.5wt% ZnO, plus 3wt% nepheline syenite.

[0090] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0091] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0092] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0093] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.6: 0.8, and mix and ball mill.

[0094] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0095] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0096] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 8 hours.

[0097] The residue after sieving in step three is 0.06%.

[0098] The aging process in step three takes 48 hours.

[0099] The total firing time for step four is 15 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1330°C under a reducing atmosphere, and the maximum firing temperature is held for 3 hours.

[0100] Step four yields a product glaze with a whiteness of 84% and a hardness of 790 kgf / mm². 2 Mohs hardness 5.4.

[0101] Step four results in a uniformly distributed network of cracks on the product's glaze surface, with a crack width of 0.1 mm and a crack density of 2 cracks / dm². 2 .

[0102] Step four results in a product glaze with an oily sheen.

[0103] Example 6:

[0104] A lead-free, environmentally friendly white oily crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 28wt% sodium feldspar, 8wt% Suzhou kaolin, 9wt% quartz, 7wt% calcite, 8wt% barium carbonate, 22wt% talc, 16wt% sodium carbonate, 2wt% ZnO, plus 2wt% nepheline syenite.

[0105] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0106] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0107] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0108] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.8: 0.8, and mix and ball mill.

[0109] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0110] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0111] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 10 hours.

[0112] The residue after sieving in step three is 0.06%.

[0113] The aging process in step three takes 40 hours.

[0114] The total firing time for step four is 16 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1300°C under a reducing atmosphere, and the maximum firing temperature is held for 1.5 hours.

[0115] Step four yields a product glaze with a whiteness of 81% and a hardness of 844 kgf / mm². 2 Mohs hardness 5.5.

[0116] Step four results in a uniformly distributed network of cracks on the glaze surface of the product, with a crack width of 0.1 mm and a crack density of 1 crack / dm². 2 .

[0117] Step four results in a product glaze with an oily sheen.

[0118] Example 7:

[0119] A lead-free, environmentally friendly white oil-based crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 28wt% sodium feldspar, 8wt% Suzhou kaolin, 16.2wt% quartz, 10wt% calcite, 6wt% barium carbonate, 24wt% talc, 6wt% sodium carbonate, 1.8wt% ZnO, plus 4wt% nepheline syenite.

[0120] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0121] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0122] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0123] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.7: 0.7, and mix and ball mill.

[0124] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0125] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0126] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 9 hours.

[0127] The residue on the sieve after sieving in step three is 0.05%.

[0128] The aging process in step three takes 48 hours.

[0129] The total firing time for step four is 15 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1310°C under a reducing atmosphere, and the maximum firing temperature is held for 2.5 hours.

[0130] Step four yields a product glaze with a whiteness of 82% and a hardness of 832 kgf / mm². 2 Mohs hardness 5.2.

[0131] Step four results in a uniformly distributed network of cracks on the product's glaze surface, with a crack width of 0.1 mm and a crack density of 4 cracks / dm². 2 .

[0132] Step four results in a product glaze with an oily sheen.

[0133] Example 8:

[0134] A lead-free, environmentally friendly white oil-based crackle ceramic glaze, wherein the raw material formula of the ceramic glaze is composed of the following weight percentages: 35wt% sodium feldspar, 7.5wt% Suzhou kaolin, 19wt% quartz, 7wt% calcite, 10wt% barium carbonate, 19wt% talc, 0.5wt% sodium carbonate, 2wt% ZnO, plus 6wt% nepheline syenite.

[0135] Talc, sodium carbonate, and ZnO are used as inducing agents, and nepheline syenite is used as a texture modifier.

[0136] The application method of the lead-free, environmentally friendly white oil-based crackle ceramic glaze includes the following steps:

[0137] Step 1: Weigh the ceramic glaze according to the weight percentage of the raw material formula and mix them evenly to obtain powder;

[0138] Step 2: Add the powder prepared in Step 1, the alumina ball mill, and water to the ball mill jar according to the mass ratio of raw material: alumina ball mill: water = 1: 1.8: 0.7, and mix and ball mill.

[0139] Step 3: After ball milling in Step 2, the glaze slurry is first passed through a 40-mesh sieve and then through a 200-mesh sieve, and then aged to obtain the glaze material;

[0140] Step 4: Apply the glaze obtained in Step 3 to the surface of the ceramic body, dry it, and then fire it in a reducing atmosphere to obtain a lead-free, environmentally friendly white oil-based crackle ceramic glaze decorative product.

[0141] In step two, the ratio of 8mm and 2.5mm alumina ball milling particles is 60%:40%, and the milling time is 11 hours.

[0142] The residue on the sieve after sieving in step three is 0.05%.

[0143] The aging process in step three takes 36 hours.

[0144] The total firing time for step four is 12 hours. Specifically, the temperature inside the kiln is first uniformly raised from room temperature to 1020°C under an oxidizing atmosphere, and the firing time is 6 hours. Then, the temperature inside the kiln is uniformly raised from 1020°C to the maximum firing temperature of 1330°C under a reducing atmosphere, and the maximum firing temperature is held for 3 hours.

[0145] Step four yields a product glaze with a whiteness of 83% and a hardness of 850 kgf / mm². 2 Mohs hardness 5.0.

[0146] Step four results in a uniformly distributed network of cracks on the product's glaze surface, with a crack width of 0.2 mm and a crack density of 6 cracks / dm². 2 .

[0147] Step four results in a product glaze with an oily sheen.

[0148] Examples 1-8 yielded a product with a pure white base glaze, on which uniform and clear network-like oily cracks are distributed. The crack lines are rounded and full, forming a sharp contrast with the white glaze, ultimately presenting a simple, elegant, and naturally formed artistic expression.

[0149] Preliminary experiments in this application have demonstrated that, with the raw material formula and other process conditions remaining unchanged, the inducing agent (talc, sodium carbonate and ZnO) and the texture modifier nepheline syenite have a very important influence on the crack morphology and whiteness of the glaze, as shown in Comparative Examples 1-5.

[0150] Comparative Example 1: With the patented formula and other process conditions unchanged in Example 1, nepheline syenite was removed. The sample appearance was as follows: Figure 5 As shown in the image, there are no obvious micro-cracks on the glaze surface.

[0151] Comparative Example 2: With the patented formulation and other process conditions unchanged in Example 1, talc in the inducing agent was replaced with dolomite. The sample morphology is as follows: Figure 5 As shown in the image, the glaze surface exhibits many small pores, inconspicuous micro-cracks, and an uneven surface.

[0152] Comparative Example 3: With the patented formulation and other process conditions unchanged in Example 1, sodium carbonate was removed from the inducing agent. The sample morphology is as follows: Figure 5 As shown in the figure, the glaze has a yellowish tint, and the micro-cracks are not obvious.

[0153] Comparative Example 4: With the patented formula and other process conditions unchanged in Example 1, all nepheline syenite was replaced with potassium feldspar. The sample morphology is as follows: Figure 5 As shown in the image, there are a very few long cracks on the glaze.

[0154] Comparative Example 5: With the patented formula and other process conditions unchanged from Example 1, all nepheline syenite was replaced with albite. The sample morphology is as follows: Figure 5 As shown in the image, there are a few long cracks on the glaze surface, and the glaze is peeling off.

[0155] Through in-depth analysis of the reaction mechanisms of Example 1 and the five comparative examples above, the reasons for the different glaze surfaces are as follows:

[0156] Example 1: Nepheline syenite, as a key "stress-structuring agent" in this invention, plays a crucial role in precisely controlling the thermal expansion coefficient and high-temperature viscoelastic evolution of the glaze layer through its unique synergistic ratio of K2O / Na2O / Al2O3 / SiO2. When present in a specific proportion of 2-6 wt%, it synergistically works with the inducing agents (talc, sodium carbonate, and ZnO) in the formula to generate uniform and continuous tensile stress, thereby driving the formation of the uniform, rounded network of oily cracks. As shown in the comparative experiment, once it is removed, this precise tensile stress system is destroyed, and the glaze completely loses its ability to crack. This proves that nepheline syenite is an indispensable structural component for achieving the controllable crack artistic effect, and its role has precise quantitative dependence and is irreplaceable.

[0157] In Comparative Example 1, the fundamental reason why the glaze cannot crack in the absence of nepheline syenite is that the lack of this material causes the glaze layer to lose the precise chemical and structural basis required to generate uniform and moderate tensile stress. Nepheline syenite is not simply a flux; its key role is to synergistically react with other components in the formula (such as albite and sodium carbonate) through its fixed K2O / Na2O molar ratio and unique aluminum-silicon network structure, together precisely controlling the thermal expansion coefficient of the final glaze layer to a narrow critical range—slightly higher than the thermal expansion coefficient of the body. This subtle "slightly higher" state is the only source of the tensile stress that accumulates within the glaze layer during cooling, sufficient to trigger cracking yet uniformly distributed. Once nepheline syenite is removed, the chemical balance and reaction pathway of the entire glaze system are disrupted, and the expansion characteristics of the glaze systematically shift, making it impossible to accurately reach and stabilize within this critical range. As a result, the coefficients of thermal expansion of the glaze and the body are either too close (no stress) or even lower than those of the body (resulting in compressive stress). The fundamental mechanical conditions that drive crack formation no longer exist, and thus the glaze completely loses its ability to crack.

[0158] Comparative Example 2: Replacing talc with dolomite resulted in the formation of many small pores on the glaze surface. The strong flux CaO introduced by dolomite drastically reduced the high-temperature viscosity of the glaze melt, causing the decomposed gases to escape excessively before the glaze layer was sealed, leaving pores that could not be healed.

[0159] In Comparative Example 3, the removal of sodium carbonate resulted in a yellowish and uneven glaze surface. The fundamental reason for this is the loss of this strong flux's dual regulation of the glaze's melting kinetics and glass network structure. The absence of sodium carbonate led to a significant increase in the glaze's high-temperature viscosity and a sluggish melting process. On the one hand, if the sharp reduction in sodium ions is not precisely compensated for, it will cause an abnormally high proportion of potassium and other alkali metal ions in the glaze glass network. This unbalanced glass network is more likely to form specific light absorption centers, exhibiting the intrinsic pale yellow hue.

[0160] In Comparative Example 4, after completely replacing nepheline syenite with potassium feldspar, a very small number of long cracks appeared on the glaze surface. The fundamental reason is that the replacement of raw materials disrupted the original compositional balance and stress distribution. The synergistic fluxing and expansion-regulating effects of sodium and potassium ions in nepheline syenite were replaced by a single potassium ion system. This led to increased high-temperature viscosity and decreased fluidity of the glaze melt, while its coefficient of thermal expansion changed. During cooling, the mismatch between glaze shrinkage and the body could result in high tensile stress concentration in localized areas. However, because the high viscosity of the glaze melt hindered the uniform transmission and release of stress, the stress could only be concentrated and released at the weakest points, forming a few extending long cracks instead of generating a uniform network of cracks.

[0161] In Comparative Example 5, when all nepheline syenite was replaced with albite, cracks appeared on the glaze surface, accompanied by flaking. The root cause was the replacement of a composite balancing flux with a single strong flux, leading to a reversal of the stress relationship between the body and the glaze. While albite improved high-temperature fluidity, the excessively high Na₂O content introduced lacked the balancing effect of other ions, resulting in an excessive increase in the glaze's coefficient of thermal expansion. During cooling, the glaze layer contracted much more than the body, subjecting the glaze surface to enormous tensile stress, which is the cause of long cracks. Simultaneously, compositional imbalance may lead to structural differentiation within the glaze layer or at the body-glaze interface, forming phases with extremely low coefficients of thermal expansion in localized areas. These areas, upon cooling, instead bear enormous compressive stress. When the compressive stress exceeds the bonding strength of the glaze layer, it causes the glaze surface to shatter and flak off. This demonstrates the necessity of a composite flux system in maintaining stress equilibrium.

[0162] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles and spirit of the present invention are included within the protection scope of the present invention.

Claims

1. A lead-free, environmentally friendly white oil-based crackle ceramic glaze, characterized by: The raw material formula of the ceramic glaze comprises albite 28-35wt%, Suzhou kaolin 5-8wt%, quartz 9-19wt%, calcite 4-10wt%, barium carbonate 5-10wt%, talc 18-25wt%, sodium carbonate 0.5-16wt%, ZnO 1.4-2wt%, and additionally adamellite 2-6wt%.

2. The application method of the lead-free environment-friendly white oily crack ceramic glaze according to claim 1, characterized in that The method comprises the following steps: Step one: the ceramic glaze is weighed according to the raw material formula and then mixed uniformly to obtain a powder; Step two: the powder prepared in step one, alumina ball mill and water are added into a ball mill tank in a mass ratio of 1:1.5-1.8:0.6-0.8, and then mixed and ball milled; Step three: the glaze slurry ball milled in step two is first passed through a 40-mesh sieve and then a 200-mesh sieve, and then aged to obtain a glaze material; Step four: the glaze material prepared in step three is applied to the surface of a body, dried, and then fired in a reducing atmosphere to obtain a lead-free environmentally-friendly white oily crack ceramic glaze decoration product.

3. The method of use of claim 2, wherein: In step two, the particle size of the alumina ball mill is 8mm and 2.5mm, and the ratio of the number of particles is 60:40, and the ball milling time is 8-12h.

4. The method of claim 2, wherein: In step three, the sieve residue after sieving is 0.05-0.07%.

5. The method of claim 2, wherein: In step three, the aging time is 24-48h.

6. The method of claim 2, wherein: In step four, the total firing time is 12-16h, and the process specifically comprises the following steps: first, the temperature in the kiln is uniformly increased from room temperature to 1020℃ in an oxidizing atmosphere, and the firing time is 6h; then, the temperature in the kiln is uniformly increased from 1020℃ to a maximum firing temperature of 1290-1330℃ in a reducing atmosphere, and the maximum firing temperature is maintained for 1-3h.

7. The method of claim 2, wherein: The step four obtains product glaze whiteness 80-85%, hardness 785-854 kgf / mm 2 , Mohs hardness 5.0-5.

5.

8. The method of claim 2, wherein: The step four obtains product glaze forming uniform distribution of network crack, crack width is 0.1-0.3mm, crack density is 1-6 lines / dm 2 .

9. The method of claim 2, wherein: The product glaze obtained in step four has oiliness.

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