Sagger pug capable of forming porcelain and preparation method of sagger pug

Abstract

The invention relates to the technical field of ceramic material preparation, and particularly discloses a ceramic-forming sagger pug and a preparation method thereof, the ceramic-forming sagger pug is prepared from the following raw materials: 40-60 wt% of kaolin, 20-30 wt% of calcined alumina, 10-15 wt% of quartz, 0.5-1.2 wt% of ammonium fluoride, 5-10 wt% of pyrophyllite, 15-20 wt% of tabular corundum, and 5-10 wt% of clay; sintering the pug at 1350 DEG C, and performing layered pressing on the pug to form an asymmetric layered structure; by optimizing a raw material formula and adding functional components (such as ammonium fluoride and tabular corundum), in-situ generation of mullite whiskers with a high length-diameter ratio in a high-temperature sintering process of the pug is remarkably promoted, so that the mechanical strength and thermal stability of the material are improved, and the material is more suitable for long-term use in a high-temperature environment; by adopting the design of the asymmetric layered structure (the compact layer, the buffer layer and the supporting layer), the thermal expansion coefficients and stress distribution of different areas are effectively coordinated, the thermal shock resistance of the sagger is greatly enhanced, and the cracking problem caused by thermal stress concentration of a traditional homogeneous structure is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic material preparation, and in particular relates to a porcelain-forming sagger clay material and a preparation method thereof. Background Art

[0002] In the field of ceramic material preparation technology, saggers are important auxiliary tools in the ceramic firing process. The quality of their performance directly affects the quality and production efficiency of ceramic products. With the continuous development of the ceramic industry, the requirements for sagger materials are also increasing, especially in terms of high-temperature stability, mechanical strength and thermal shock resistance. More stringent standards are put forward.

[0003] At present, the common sagger materials on the market are mostly based on traditional formulas. These materials are mainly composed of basic raw materials such as kaolin, quartz and clay, supplemented by a small amount of feldspar as a flux, and are prepared by a simple dry mixing and single-layer pressing process. Although these traditional materials can meet the basic firing requirements to a certain extent, their long-term performance in high-temperature environments is significantly insufficient. Specifically, during the high-temperature firing process, traditional sagger materials are often difficult to form microstructures with high aspect ratios and excellent mechanical properties, such as mullite whiskers, due to the limitations of the raw material ratio and the simplicity of the preparation process. This directly leads to the softening, deformation and even cracking of the sagger at high temperatures, which seriously affects the firing quality and production efficiency of ceramic products. In addition, traditional sagger materials also perform poorly in terms of thermal shock resistance and are difficult to adapt to the thermal stress shock caused by rapid temperature changes, further limiting their application in the field of high-temperature ceramic firing. Therefore, staff are required to improve them. Summary of the Invention

[0004] The object of the present invention is to provide a clay material that can be formed into a porcelain sagger and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The clay material for porcelain sagger is made from the following raw materials:

[0007] Kaolin: 40-60wt%, calcined alumina: 20-30wt%, quartz: 10-15wt%, ammonium fluoride: 0.5-1.2wt%, pyrophyllite: 5-10wt%, tabular corundum: 15-20wt%, clay: 5-10wt%;

[0008] The clay material is pressed in layers to form an asymmetric layered structure, including a dense layer with a porosity of less than 5%, a buffer layer containing 10-15wt% pyrophyllite and a support layer containing 20wt% plate-shaped corundum, and mullite whiskers are generated in situ after being fired at 1350°C.

[0009] Preferably, the added amount of ammonium fluoride is 0.8-1.0 wt%.

[0010] Preferably, the buffer layer has a pyrophyllite content of 12-14 wt%.

[0011] The method for preparing a clay material capable of forming a porcelain sagger comprises the following steps:

[0012] S1. Weigh the raw materials according to the following ratios: kaolin: 40-60wt%, calcined alumina: 20-30wt%, quartz: 10-15wt%, ammonium fluoride: 0.5-1.2wt%, pyrophyllite: 5-10wt%, tabular corundum: 15-20wt%, and clay: 5-10wt%.

[0013] S2, ball milling the raw materials for 2-4 hours;

[0014] S3, 24-48 hours of staleness;

[0015] S4, using a layered pressing process to sequentially form a dense layer, a buffer layer, and a support layer;

[0016] S5. After drying, sinter at 1350-1380℃ and keep warm for 2-4 hours.

[0017] Preferably, in the layered pressing process, the pressing pressure of the dense layer is 10-20% higher than that of the buffer layer, and the pressing pressure of the buffer layer is 5-10% lower than that of the support layer.

[0018] Preferably, the sintering temperature is 1350° C. and the holding time is 3 hours.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) By optimizing the raw material formula and adding functional components (such as ammonium fluoride and plate-shaped corundum), the in-situ generation of mullite whiskers with a high aspect ratio during the high-temperature firing process is significantly promoted, thereby improving the mechanical strength and thermal stability of the material, making it more suitable for long-term use in high-temperature environments.

[0021] (2) By adopting the design of an asymmetric layered structure (dense layer, buffer layer, support layer), the thermal expansion coefficient and stress distribution in different regions are effectively coordinated, the thermal shock resistance of the sagger is greatly enhanced, and the cracking problem caused by thermal stress concentration in the traditional homogeneous structure is avoided.

[0022] (3) By combining the layered pressing process with the gradient firing system, the density and performance of each layer of the clay material can be precisely controlled, which not only ensures the low porosity of the dense layer to isolate the glaze from erosion, but also improves the durability and bearing capacity of the overall structure through the synergistic effect of the buffer layer and the support layer.

[0023] (4) By introducing the synergistic effect of mineralizer (ammonium fluoride) and plate-shaped corundum, the distribution and orientation of mullite whiskers are optimized, and the thermal conductivity uniformity and high-temperature creep resistance of the material are further improved, so that it can still maintain structural integrity under complex thermal cycling conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a preparation flow chart of the present invention. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Example 1:

[0027] See also Figure 1 As shown, the raw material ratio of the clay material for porcelain sagger is:

[0028] The raw materials were weighed according to the following weight percentages: kaolin: 50 wt%, calcined alumina: 25 wt%, quartz: 12 wt%, ammonium fluoride (NH4F): 0.8 wt% (as a mineralizer), pyrophyllite: 8 wt%, tabular corundum: 18 wt%, and clay: 6 wt%.

[0029] Preparation method of porcelain sagger clay:

[0030] S1. Place the above raw materials in a planetary ball mill, use zirconia balls as grinding media, a ball-to-material ratio of 2:1, and a rotation speed of 300 rpm, and wet-mill for 3 hours to obtain a uniformly mixed mud slurry;

[0031] S2. Place the mud slurry in a sealed container and age it at room temperature for 36 hours to evenly distribute the moisture and improve plasticity.

[0032] Asymmetric layered structure molding:

[0033] The sagger green body is prepared by layered pressing process:

[0034] Dense layer (contacting glaze side): Take the above clay material and dry press it under 20MPa pressure to control the porosity ≤5%;

[0035] Buffer layer (middle layer): Adjust the clay formula, add 12wt% pyrophyllite, and mold under a pressure of 15MPa;

[0036] Support layer (bottom): Adjust the clay formula, add an additional 20wt% plate-shaped corundum, and form it under a pressure of 18MPa.

[0037] Drying and firing:

[0038] Place the formed green body in a constant temperature drying oven at 80°C for 24 hours to ensure that the moisture evaporates slowly to avoid cracking;

[0039] The dried green body was placed in a high-temperature kiln, heated to 1350°C at a heating rate of 5°C / min, kept at this temperature for 3 hours, and then naturally cooled to room temperature.

[0040] Performance testing:

[0041] Microstructure analysis (SEM): After firing, interlaced mullite whiskers are formed inside the clay material, with an aspect ratio of about 12:1 to 15:1. The whiskers are evenly dispersed without agglomeration.

[0042] Mechanical properties test: flexural strength: 45MPa (ASTMC674-13 standard), thermal shock stability (1100℃ to room temperature, water quenching): no cracking after 50 cycles.

[0043] Example 2:

[0044] The raw material ratio of the porcelain sagger clay is accurately weighed according to the following weight percentage: kaolin: 45wt% (Al2O3 content ≥38%), calcined alumina: 28wt% (α-Al2O3, D50 = 2.5μm), quartz: 13wt% (SiO2 content ≥99.5%, 200 mesh sieve residue ≤0.5%), ammonium fluoride (NH4F): 1.0wt% (analytical grade, purity ≥99%), pyrophyllite: 10wt% (MgO content ≤0.5%), plate-like corundum: 22wt% (Al2O3 ≥99%, plate-like crystal diameter-to-thickness ratio ≥8:1), clay: 7wt% (plasticity index ≥15).

[0045] Preparation method of porcelain sagger clay:

[0046] S1. Use planetary ball mill (QM-3SP4 model) for wet grinding: ball milling media: zirconia balls (three-grade ratio of Φ3mm / Φ5mm / Φ8mm), ball-to-material ratio: 3:1, rotation speed: 350rpm, grinding time: 4 hours, slurry fineness: D90≤5μm (detected by laser particle size analyzer).

[0047] S2. Aging treatment: ambient temperature: 25±2°C, relative humidity: 60±5%, aging time: 48 hours, mud moisture content: 18.5% (determined by 105°C drying method).

[0048] Gradient structure molding:

[0049] Using isostatic pressing process: mold preheating temperature: 60℃;

[0050] Pressing pressure gradient: dense layer: 25MPa (holding pressure for 30s), buffer layer: 18MPa (holding pressure for 20s), support layer: 22MPa (holding pressure for 25s);

[0051] Density of green body after demoulding: 2.65g / cm 3 .

[0052] Sintering process:

[0053] Drying system:

[0054] Staged drying: 50°C (4h) to 80°C (8h) to 110°C (4h);

[0055] Drying shrinkage: 3.2%.

[0056] Firing curve:

[0057] Heating rate: room temperature to 300°C: 2°C / min, 300 to 800°C: 3°C / min, 800 to 1350°C: 5°C / min;

[0058] Holding stage: 1350℃×4h (oxidizing atmosphere);

[0059] Cooling system: Cool with the furnace to 300℃ and then air cool.

[0060] Performance characterization:

[0061] Microstructure: SEM shows that mullite whiskers are distributed in a three-dimensional network;

[0062] XRD quantitative analysis: mullite phase content 38.7%;

[0063] The average whisker size is: 0.5-1μm in diameter and 8-12μm in length.

[0064] Macro performance:

[0065] Flexural strength at room temperature: 52.3MPa;

[0066] Thermal shock cycle: Strength retention rate after 62 cycles is 82%;

[0067] Thermal conductivity: 1.85W / (m·K).

[0068] Comparative Example:

[0069] Description of the prior art: Traditional sagger clay usually adopts a single formula and a simple pressing process. Its main raw materials are kaolin (50-70wt%), quartz (15-25wt%) and clay (10-20wt%), supplemented with a small amount of feldspar (5-10wt%) as a flux. The preparation method includes the following steps:

[0070] Raw material mixing: dry mix kaolin, quartz, clay and feldspar and ball mill for 1-2 hours.

[0071] Molding: Single-layer pressing process is adopted, and the mold is directly pressed under a pressure of 15-20MPa.

[0072] Firing: After drying, fire at 1300-1320℃, keep warm for 2 hours, and cool naturally.

[0073] After firing, traditional clay primarily produces a common mullite phase (aspect ratio ≤ 5:1), with a uniform structure but no gradient design, a high porosity (8-12%), and a lack of functional additives (such as ammonium fluoride and plate-shaped corundum). Its mechanical properties and thermal shock stability are poor, with a flexural strength typically of 20-30 MPa, and it can withstand only 10-15 thermal shock cycles (1100°C to room temperature water quenching).

[0074] Performance comparison chart:

[0075]

[0076]

[0077] Comparative Conclusion

[0078] Raw materials and formula: Existing technologies rely on traditional raw materials and lack functional additives (such as ammonium fluoride and plate-shaped corundum), which cannot promote the in-situ formation of mullite whiskers.

[0079] In Examples 1 and 2, the whisker growth and mechanical properties are significantly optimized by adding ammonium fluoride (mineralizer) and plate-shaped corundum.

[0080] Structural design: The existing technology is a single-layer homogeneous structure, which cannot coordinate the distribution of thermal stress.

[0081] The embodiment adopts an asymmetric / gradient structure, and greatly improves the thermal shock stability through the synergistic effect of the dense layer, the buffer layer and the support layer.

[0082] Performance: The flexural strength and thermal shock cycle times of the prior art are only 40-50% of those of the embodiment, and the high porosity leads to poor durability.

[0083] The embodiment achieves high density and high performance through fine process control (such as layered pressing and precise firing system).

[0084] All standard parts used in the present invention can be purchased commercially, and special-shaped parts can be customized according to the description in the specification and drawings. The specific connection methods of each part adopt conventional means such as bolts, rivets, welding, etc. that are mature in the prior art. The machinery, parts and equipment all adopt conventional models in the prior art. In addition, the circuit connections adopt conventional connection methods in the prior art and will not be described in detail here. Any matters not described in detail in this specification belong to the prior art known to professionals in this field.

[0085] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. "Multiple" means two or more, unless otherwise specifically defined.

[0086] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0087] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0088] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0089] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0090] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The clay material for porcelain sagger is characterized by: Made from the following ingredients: Kaolin: 40-60wt%, calcined alumina: 20-30wt%, quartz: 10-15wt%, ammonium fluoride: 0.5-1.2wt%, pyrophyllite: 5-10wt%, tabular corundum: 15-20wt%, clay: 5-10wt%; The clay material is pressed in layers to form an asymmetric layered structure, including a dense layer with a porosity of less than 5%, a buffer layer containing 10-15wt% pyrophyllite and a support layer containing 20wt% plate-shaped corundum, and mullite whiskers are generated in situ after being fired at 1350°C.

2. The porcelain-forming sagger clay according to claim 1, characterized in that: The amount of ammonium fluoride added is 0.8-1.0 wt%.

3. The porcelain-forming sagger clay according to claim 1, characterized in that: The pyrophyllite content of the buffer layer is 12-14 wt%.

4. A method for preparing a porcelain-forming sagger clay material, applicable to the porcelain-forming sagger clay material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Weigh the raw materials according to the following ratios: kaolin: 40-60wt%, calcined alumina: 20-30wt%, quartz: 10-15wt%, ammonium fluoride: 0.5-1.2wt%, pyrophyllite: 5-10wt%, tabular corundum: 15-20wt%, and clay: 5-10wt%. S2, ball milling the raw materials for 2-4 hours; S3, 24-48 hours of staleness; S4, using a layered pressing process to sequentially form a dense layer, a buffer layer, and a support layer; S5. After drying, sinter at 1350-1380℃ and keep warm for 2-4 hours.

5. The method for preparing a porcelain-forming sagger clay according to claim 4, wherein: In the layered pressing process, the pressing pressure of the dense layer is 10-20% higher than that of the buffer layer, and the pressing pressure of the buffer layer is 5-10% lower than that of the support layer.

6. The method for preparing a porcelain-forming sagger clay material according to claim 4, wherein: The sintering temperature is 1350° C. and the holding time is 3 hours.

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