A method for preparing an ultra-smooth, low-expansion ceramic glaze with in-situ generated cordierite.

Abstract

This invention discloses a method for preparing an ultra-smooth, low-expansion ceramic glaze with in-situ generated cordierite. By introducing bismuth oxide and antimony oxide into a high-potassium, low-sodium system to form a K-Mg-Sb-Bi multi-element eutectic system, not only is low thermal expansion and smoothness of the glaze achieved, but cordierite microcrystals are also successfully guided to precipitate in-situ in the glassy phase of the glaze, thereby obtaining a ceramic glaze with excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of functional ceramic glaze technology, and in particular to a method for preparing an ultra-smooth, low-expansion ceramic glaze with in-situ generated cordierite. Background Technology

[0002] Ceramic glazes are key materials that endow ceramic products with aesthetic value, surface properties, and functionality. High-gloss, ultra-smooth glazes, with their pure and elegant texture, enjoy continuous and widespread demand in the fields of high-end daily-use ceramics, art ceramics, and building and sanitary ceramics. The final performance of a glaze largely depends on its chemical composition and firing regime, with the selection and design of the flux system being the core.

[0003] Traditional glazes are typically a completely glassy phase, which, while providing a smooth surface, suffers from poor thermal shock resistance. Introducing crystalline phases (such as zinc aluminum spinel and wollastonite) into the glaze can improve its properties, but it is difficult to achieve a smooth texture simultaneously.

[0004] Cordierite (2MgO·2Al2O3·5SiO2) is a crystal known for its low coefficient of thermal expansion, high thermal shock resistance, and good mechanical strength. Typically, cordierite is synthesized in the body at high temperatures (>1400℃). However, due to the very narrow chemical composition and firing regime window of glazes, precipitating cordierite crystals in glazes, especially low-temperature glazes, is extremely challenging and presents a significant difficulty in improving the overall performance of ceramic glazes. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an ultra-smooth, low-expansion ceramic glaze with in-situ generated cordierite. By introducing bismuth oxide and antimony oxide into a high-potassium, low-sodium system to form a K-Mg-Sb-Bi multi-element eutectic system, the glaze achieves low thermal expansion and smoothness. At the same time, it guides cordierite microcrystals to precipitate in-situ in the glassy phase of the glaze, thereby obtaining a ceramic glaze with excellent comprehensive performance.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing an ultra-smooth, low-expansion ceramic glaze with in-situ generated cordierite. The raw material composition of the ceramic glaze is 30-45 wt% potassium feldspar, 9-15 wt% quartz, 16-23 wt% talc, 10-14 wt% kaolin, 3-6 wt% magnesite, 1-4 wt% zinc oxide, 7-12 wt% bismuth oxide, and 1-3 wt% antimony oxide. The preparation method includes the following steps:

[0008] (1) After mixing the zinc oxide, bismuth oxide and antimony oxide according to the raw material composition, the temperature is raised to 750-850℃ at a rate of 6-10℃ / min for calcination treatment, and the holding time is 1.5-2.5h. After cooling to room temperature in the furnace, the resulting block material is dry ball milled to a particle size of <15μm to obtain a composite smoothing agent.

[0009] (2) The potassium feldspar, quartz, talc, kaolin, magnesite and composite smoothing agent are added to a ball mill for ball milling. The resulting slurry is sieved and aged at room temperature to obtain glaze slurry.

[0010] (3) The glaze slurry is applied to the surface of the unglazed body to obtain a glaze layer. After drying, it is sintered at 1210-1230℃ for 20-30 minutes to obtain an ultra-smooth low-expansion ceramic glaze.

[0011] Further, in step (2) of the present invention, ball milling is performed at a mass ratio of material:ball:water = 1:2-3:0.9-1.2, the ball milling time is 3-4.5 hours, and the aging time is 24-48 hours. In step (3), the thickness of the glaze layer is 0.1-0.2 mm.

[0012] In the above-described scheme, the ultra-smooth, low-expansion ceramic glaze obtained by the present invention has a coefficient of thermal expansion of 3.8–4.7 × 10⁻⁻⁻⁶. 6 / K, roughness <0.0067μm.

[0013] The present invention has the following beneficial effects:

[0014] (1) The innovation of this invention lies in the construction of a K-Mg-Sb-Bi multi-component eutectic system. Potassium feldspar, talc, antimony oxide, bismuth oxide, and other components interact during firing, forming a low-temperature eutectic at a temperature lower than the traditional cordierite formation temperature. This multi-component eutectic system not only achieves low-temperature melting but also creates an environment conducive to the precipitation of cordierite microcrystals. Talc, magnesite, and kaolinite provide ample sources of MgO and Al2O3. Under the action of the K-Mg-Sb-Bi multi-component eutectic system, the holding time after firing is shortened, allowing cordierite crystals to precipitate uniformly and finely in situ within the glaze glass phase. This results in a glaze surface that maintains a smooth texture while achieving a low coefficient of thermal expansion.

[0015] (2) Bismuth oxide and antimony oxide, as powerful low-temperature fluxes, can promote the melting of glazes at relatively low temperatures (1100-1180℃). In the K-Mg-Sb-Bi multi-element eutectic system constructed in this invention, they serve as the main fluxes, which not only reduce the initial melting temperature of the glaze but also reduce the surface tension at high temperatures, giving the glaze melt excellent fluidity and allowing it to spread fully to form a smooth glassy matrix. At the same time, they can promote the uniform precipitation of cordierite crystal phase from the glaze melt during the cooling process, thereby obtaining a smooth, low-expansion glaze surface with excellent comprehensive performance. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0017] Figure 1 This is a two-dimensional morphological analysis image of the glaze surface of the sample obtained in Embodiment 3 of the present invention using atomic force microscopy;

[0018] Figure 2 This is an atomic force microscope three-dimensional morphology analysis image of the glaze surface of the sample obtained in Embodiment 3 of the present invention;

[0019] Figure 3 This is the cordierite crystal phase diagram of the sample obtained in Example 3 of the present invention. Detailed Implementation

[0020] This invention discloses a method for preparing an ultra-smooth, low-expansion ceramic glaze with in-situ generated cordierite. The raw material composition of the ceramic glaze is as follows: potassium feldspar 30-45 wt%, quartz 9-15 wt%, talc 16-23 wt%, kaolin 10-14 wt%, magnesite 3-6 wt%, zinc oxide 1-4 wt%, bismuth oxide 7-12 wt%, and antimony oxide 1-3 wt%. The preparation method comprises the following steps:

[0021] (1) Zinc oxide, bismuth oxide and antimony oxide are mixed according to the above raw material composition, and then heated to 750-850℃ at a rate of 6-10℃ / min for calcination treatment. The holding time is 1.5-2.5h. After cooling to room temperature in the furnace, the resulting block material is dry ball milled to a particle size of <15μm to obtain a composite smoothing agent.

[0022] (2) Add the above raw materials potassium feldspar, quartz, talc, kaolin, magnesite and composite smoothing agent into a ball mill, and ball mill at a mass ratio of material:ball:water = 1:2~3:0.9~1.2 (speed is 300 rpm) for 3~4.5 h. After sieving, the resulting slurry is aged at room temperature for 24~48 h to obtain glaze slurry.

[0023] (3) The above glaze slurry is applied to the surface of the unglazed body to obtain a glaze layer with a thickness of 0.1 to 0.2 mm. After drying, it is sintered at a temperature of 1210 to 1230 °C for 20 to 30 min to obtain an ultra-smooth low-expansion ceramic glaze.

[0024] The raw material composition of the ceramic glaze in each embodiment of the present invention is shown in Table 1; the potassium feldspar, quartz, talc, kaolin, and magnesite are used as the base glaze materials, and their chemical composition is shown in Table 2.

[0025] Table 1. Raw material composition (wt%) of ceramic glazes in various embodiments of the present invention

[0026]

[0027] Table 2 Chemical composition (wt%) of the base glaze in each embodiment of the present invention

[0028]

[0029] The process parameters for each embodiment of the present invention are shown in Table 3.

[0030] Table 3 Process parameters of various embodiments of the present invention

[0031]

[0032] Comparative Example 1:

[0033] Four sets of experiments were conducted with zinc oxide not added as the control example, and the remaining conditions were the same as in Examples 1, 2, 3, and 4.

[0034] Comparative Example 2:

[0035] Using antimony oxide without its addition as Comparative Example 2, four sets of experiments were conducted under the same conditions as in Examples 1, 2, 3, and 4.

[0036] Comparative Example 3:

[0037] Comparative Example 3 was conducted without the addition of bismuth oxide, and the remaining conditions were the same as in Examples 1, 2, 3, and 4. Four sets of experiments were carried out.

[0038] The atomic force microscopy morphology analysis of the sample prepared in Example 3 of this invention is as follows: Figure 1 , Figure 2 As shown, the results indicate that the sample glaze surface is smooth. Figure 3As shown, cordierite crystals are uniformly and finely precipitated in situ within the glassy phase of the glaze, resulting in a smooth glaze surface while achieving a low coefficient of thermal expansion. The coefficient of thermal expansion was tested according to the method in GB / T 3810.8-2016; the surface roughness was tested according to the method in GB / T 3810.14-2016. The performance indicators of the glazes obtained in the various embodiments and comparative examples of this invention are shown in Table 4.

[0039] Table 4 Performance indicators of the glaze obtained from various embodiments and comparative examples of the present invention

[0040]

[0041] Note: The performance indicators for each comparative example are the average values ​​of the four experimental groups.

Claims

1. A method for making an ultra-smooth, low-expansion ceramic glaze that generates cordierite in situ, characterized by: The raw material composition of the ceramic glaze is 30-45wt% of potassium feldspar, 9-15wt% of quartz, 16-23wt% of talc, 10-14wt% of kaolin, 3-6wt% of magnesite, 1-4wt% of zinc oxide, 7-12wt% of bismuth oxide, and 1-3wt% of antimony oxide; the preparation method comprises the following steps: (1) the zinc oxide, bismuth oxide and antimony oxide are mixed according to the raw material composition, then heated to 750-850℃ at a rate of 6-10℃ / min for calcination treatment, the holding time is 1.5-2.5h, and the obtained blocky material is dry ball-milled to a particle size of less than 15μm to obtain a composite smoothing agent; (2) the potassium feldspar, quartz, talc, kaolin, magnesite and the composite smoothing agent are added into a ball mill for ball-milling treatment, the obtained slurry is sieved and then aged at room temperature to obtain a glaze slurry; (3) the glaze slurry is applied to the surface of a body to obtain a glaze layer, dried and then sintered at a temperature of 1210-1230℃ for 20-30min to obtain an ultra-smooth low-expansion ceramic glaze.

2. The method of claim 1, wherein the method further comprises: In the step (2), the ball-milling treatment is carried out according to the mass ratio of material: ball: water = 1:2-3:0.9-1.2, the ball-milling time is 3-4.5h, and the aging time is 24-48h.

3. The method of claim 1, wherein the method further comprises: In the step (3), the thickness of the glaze layer is 0.1-0.2mm.

4. The method of claim 1, wherein the method further comprises: The prepared super-smooth low-expansion ceramic glaze has a thermal expansion coefficient of 3.8-4.7*10 6 / K, roughness <0.0067 μm.

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