Ceramic green body with low shrinkage and preparation method and application thereof

Abstract

The application provides a ceramic blank with low shrinkage rate and a preparation method and application thereof, and the ceramic blank comprises solid-phase raw materials, liquid-phase raw materials and modified rare earth alumina microspheres, the mass ratio of the solid-phase raw materials to the liquid-phase raw materials is (2-5):(5-8), and the proportion of the added amount of the modified rare earth alumina microspheres to the total mass of the solid-phase raw materials and the liquid-phase raw materials is (0.1-10):(90-99.9); wherein the solid-phase raw materials comprise the following components in mass fraction: 20.0-60.0 parts of an aluminum source, 55.0-80.0 parts of a silicon source, 0.8-2.0 parts of Fe2O 3 3, 0.2-5.0 parts of a calcium source, and 0.1-1.0 parts of MgO. In the application, rare earth is introduced into the ceramic blank, and due to the high surface activity and good stability of the rare earth, the binding state between blank particles can be optimized, and the anti-shrinkage performance is improved.

Description

Technical Field

[0001] This invention belongs to the field of functional ceramic materials, and in particular relates to a low-shrinkage ceramic blank, its preparation method and application. Background Technology

[0002] The ceramic green body is the main body of ceramic products, and its properties determine the performance and application of the ceramic products. The preparation of the green body is of paramount importance in ceramic production, and green body drying is one of the key processes in the ceramic industry. During the drying process, as moisture is removed, the green body shrinks and deforms, and may even crack, affecting the dimensional accuracy and yield of the product.

[0003] Factors affecting the drying performance of ceramic green bodies include particle size, plasticity, and mineral composition. Higher clay fineness leads to greater shrinkage and increased drying sensitivity. Excessive shrinkage not only hinders size and brick shape control but also consumes more green body powder, increasing production costs. Existing methods for reducing shrinkage often involve adjusting particle size or adding conventional mineral fillers. While these methods can slightly reduce shrinkage (usually still ≥5%), they can easily lead to decreased slurry absorption rate or reduced strength, making it difficult to balance multiple performance indicators. Therefore, developing a method for preparing ceramic green bodies that can significantly reduce drying shrinkage while maintaining good drying strength and slurry absorption rate is a pressing technical problem in this field. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and propose a ceramic blank with low shrinkage rate, its preparation method and application.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: In a first aspect, the present invention provides a ceramic blank with low shrinkage rate, comprising a solid phase raw material, a liquid phase raw material and modified rare earth alumina microspheres, wherein the mass ratio of the solid phase raw material to the liquid phase raw material is (2-5):(5-8), and the ratio of the amount of modified rare earth alumina microspheres added to the total mass of the solid phase raw material and the liquid phase raw material is (0.1-10):(90-99.9); wherein the solid phase raw material comprises the following components in parts by mass: 20.0-60.0 parts of aluminum source, 55.0-80.0 parts of silicon source, 0.8-2.0 parts of Fe2O3, 0.2-5.0 parts of calcium source, and 0.1-1.0 parts of MgO.

[0006] Preferably, the modified rare earth alumina microspheres are prepared by: 1) Rare earth oxides and γ-Al2O3 were mixed and wet ball milled until 500nm≤D90≤1000nm to obtain a rare earth alumina dispersion; 2) After mixing rare earth alumina dispersion with polystyrene colloid, the mixture is atomized into nano-sized droplets by ultrasonic atomization. After drying the nano-sized droplets, rare earth alumina microspheres (abbreviated as RE-A) are obtained. 3) Immerse RE-A in a polyethylene glycol solution and let it stand for a period of time. Dry the RE-A after immersion to form a stable layer on its surface, which is the modified RE-A.

[0007] Preferably, the mass ratio of the rare earth oxide to γ-Al2O3 is (40-70):(30-60).

[0008] Preferably, in step 1), after the rare earth oxides and γ-Al2O3 are mixed, the solid content of the mixture slurry is adjusted to 5%-80% before ball milling. The linear velocity of the ball mill is 1-13 m / s, and the grinding temperature is controlled at 15-40℃. In step 2), the mixture is spray-dried at a feed rate of 0.1-60 L / min through a nozzle at 210-280℃.

[0009] Preferably, the polyethylene glycol solution has a mass fraction of 5%-50%.

[0010] Preferably, the aluminum source is one or more of alumina, aluminum hydroxide, aluminum silicate, bauxite, aluminum ash, kaolin, coal gangue, and bentonite.

[0011] Preferably, the silicon source is one or more of silicon oxide, quartz sand, silica powder, and silicates.

[0012] Preferably, the calcium source is one or more of calcium oxide, wollastonite, anorthite, and calcite.

[0013] Preferably, the liquid phase raw material is one or more selected from water, silica sol, aluminum sol, and zirconium sol.

[0014] Preferably, the rare earth oxide comprises one or more of lanthanum oxide, cerium oxide, samarium oxide, praseodymium oxide, neodymium oxide, europium oxide, gadolinium oxide, yttrium oxide, lanthanum cerium oxide, and lanthanum samarium oxide.

[0015] Secondly, the present invention also provides a method for preparing the above-mentioned low-shrinkage ceramic green body, comprising the following steps: Solid raw materials, liquid raw materials and modified rare earth alumina microspheres are mixed and stirred evenly using a disperser. The mixture is then poured into a gypsum mold at a uniform speed to form the ceramic blank. After aging, demolding and drying, the ceramic blank is obtained.

[0016] Preferably, the stirring speed of the disperser is controlled at 700-1200 r / min and the stirring time is controlled at 10-15 min to ensure that the ceramic blanks at the bottom and edge of the container are stirred evenly.

[0017] Preferably, the ceramic blank is formed by slurry injection in a plaster mold. The slurry is injected into the mold at a uniform speed to avoid defects or air bubbles. After standing and aging at 20-30℃ for 2-8 hours, it is demolded.

[0018] Preferably, the drying process is carried out in an oven, and the hot air drying process involves phased temperature increases; the specific steps are as follows: first, the temperature is controlled at 45~60℃ for drying, and the drying time is 0.5~2h; then the temperature is controlled at 90~120℃ for drying, and the drying time is 4~8h.

[0019] Thirdly, the present invention also provides ceramic articles prepared from the above-mentioned ceramic blanks.

[0020] Compared with the prior art, the present invention has the following advantages: (1) In this invention, rare earth elements are introduced into ceramic blanks. Since rare earth elements have high surface activity and good stability, they can optimize the bonding state between blank particles and improve the shrinkage resistance. (2) The volume of RE-A prepared in this invention is several times higher than that of rare earth powder. Its porous structure can form "support sites" in the billet, inhibiting volume collapse when water is discharged and synergistically reducing shrinkage. (3) This invention innovatively introduces a polyethylene glycol solution impregnation modification process to treat RE-A, and constructs a "chemical bridge" at the interface between RE-A and ceramic clay, which effectively enhances the interfacial bonding force between the two phases and achieves a significant improvement in the flexural strength of the ceramic body; (4) The process compatibility of the present invention is strong. All equipment used is conventional equipment in the ceramic industry. The molding qualification rate is ≥95%, the drying shrinkage rate is ≤1.8%, and at the same time, it maintains good flexural strength and slurry absorption rate, which is easy to promote industrially. Attached Figure Description

[0021] Figure 1 This is a SEM image of RE-A fabricated according to Embodiment 1 of the present invention; Figure 2 This is a SEM schematic diagram of the ceramic blank described in Embodiment 1 of the present invention. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In this document, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​that fall within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0025] In this article, the terms "multiple" or "more than" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0026] In this document, the terms "preferred" and "more preferred" are used only to describe implementation methods or embodiments with better effects, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0027] In this document, terms such as "further" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0028] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0029] In this document, the term "about" means a specified value of + / - 10%, preferably + / - 5%, and more preferably + / - 1%.

[0030] In this article, the terms “include,” “including,” “have,” “contain,” etc., are all open-ended terms, meaning that they include but are not limited to.

[0031] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0032] The present invention will be described in detail below with reference to the embodiments.

[0033] Example 1 A method for preparing a low-shrinkage ceramic green body includes the following steps: 1) The mass ratio of solid raw material to liquid raw material in the ceramic blank is controlled to be 34:66, wherein the liquid raw material is pure water, and the solid raw material is composed of the following components in parts by mass: Al2O3: 20.46 parts, SiO2: 73.24 parts, Fe2O3: 1.74 parts, CaO: 0.22 parts, MgO: 0.35 parts; 2) Rare earth oxides were obtained by mixing lanthanum oxide and yttrium oxide in a mass ratio of 87:13. γ-Al2O3 was added in a mass ratio of rare earth oxides to γ-Al2O3 of 48:52. Pure water was used as a dispersant to prepare a mixture with a solid content of 50%. The mixture was then wet-milled at a ball milling speed of 10 m / s and a grinding temperature of 30 ℃ until D90=700 nm to obtain a rare earth alumina dispersion. 3) The rare earth alumina dispersion and polystyrene (PS) colloid were mechanically mixed uniformly at a mass ratio of 20:80. The mixture was then spray-dried at a feed rate of 50 L / min through a 250°C nozzle to obtain RE-A. The electron micrograph of the obtained RE-A is shown below. Figure 1 As shown; 4) The prepared RE-A was immersed in a 25% (w / w) polyethylene glycol solution (PEG-400), left to stand for 1 hour, and then removed and dried in a 60℃ oven to obtain modified RE-A. 5) Mix the total mass of solid and liquid raw materials with the mass of modified RE-A at a ratio of 97:3, and use a disperser to continuously stir at 1000 r / min for 10 min to mix the slurry evenly. Then, pour the mixture into a gypsum mold at a uniform speed to cast and shape it. 6) Aging at 26℃ for 4 hours, drying at 45℃ for 1 hour, and then drying at 100℃ for 8 hours yields the ceramic body. The electron microscope image of the ceramic body is shown below. Figure 2 As shown; 7) The relevant properties were measured in accordance with QB / T 1548-2015 "Method for Determination of Linear Shrinkage of Ceramic Body Clay".

[0034] Example 2 A method for preparing a low-shrinkage ceramic green body includes the following steps: 1) The mass ratio of solid raw material to liquid raw material in the ceramic blank is controlled to be 2:3, wherein the liquid raw material is silica sol, and the solid raw material is composed of the following components in parts by mass: Al2O3: 40.10 parts, SiO2: 56.41 parts, Fe2O3: 0.83 parts, CaO: 2.21 parts, MgO: 0.45 parts; 2) Lanthanum oxide and γ-Al2O3 were mixed in a mass ratio of 50:50. Pure water was used as a dispersant to prepare a mixture with a solid content of 50%. The mixture was then wet-milled at a ball milling speed of 10 m / s and a grinding temperature of 30°C until D90=900 nm to obtain a rare earth alumina dispersion. 3) The rare earth alumina dispersion and polystyrene (PS) colloid were mechanically mixed uniformly at a mass ratio of 30:70. The mixture was then spray-dried at a feed rate of 50 L / min through a 250°C nozzle to obtain RE-A. 4) The prepared RE-A was immersed in a 30% (w / w) polyethylene glycol solution (PEG-400), left to stand for 1 hour, and then removed and dried in a 60℃ oven to obtain modified RE-A. 5) Mix the total mass of solid and liquid raw materials with the mass of modified RE-A at a ratio of 95:5, and use a disperser to continuously stir at 800 r / min for 15 min to mix the slurry evenly. Then, pour the mixture into a gypsum mold at a uniform speed to cast the slurry. 6) Aging at 28℃ for 6 hours, drying at 50℃ for 1 hour, and then drying at 110℃ for 8 hours to obtain ceramic blanks; 7) The relevant properties were measured in accordance with QB / T 1548-2015 "Method for Determination of Linear Shrinkage of Ceramic Body Clay".

[0035] Example 3 A method for preparing a low-shrinkage ceramic green body includes the following steps: 1) The mass ratio of solid raw materials to liquid raw materials in the ceramic blank is controlled to be 27:73, wherein the liquid raw materials are water and aluminum sol with a mass ratio of 3:1, and the solid raw materials are composed of the following components in parts by mass: Al2O3: 32.90 parts, SiO2: 60.27 parts, Fe2O3: 1.43 parts, CaO: 4.78 parts, MgO: 0.62 parts; 2) Rare earth oxides were obtained by mixing cerium oxide and praseodymium oxide in a mass ratio of 72:28. γ-Al2O3 was added in a mass ratio of rare earth oxides to γ-Al2O3 of 64:36. Pure water was used as a dispersant to prepare a mixture with a solid content of 50%. The mixture was then wet-milled at a linear speed of 10 m / s and a grinding temperature of 30 ℃ until D90=550 nm to obtain a rare earth alumina dispersion. 3) The rare earth alumina dispersion and polystyrene (PS) colloid were mechanically mixed uniformly at a mass ratio of 40:60. The mixture was then spray-dried at a feed rate of 50 L / min through a 250°C nozzle to obtain RE-A. 4) The prepared RE-A was immersed in a 10% (w / w) polyethylene glycol solution (PEG-400), left to stand for 1 hour, and then removed and dried in a 60℃ oven to obtain modified RE-A. 5) Mix the total mass of solid and liquid raw materials with the mass of modified RE-A at a ratio of 93:7, and use a disperser to continuously stir at 1200 r / min for 10 min to mix the slurry evenly. Then, pour the mixture into a gypsum mold at a uniform speed to cast the slurry. 6) Aging at 20℃ for 8 hours, drying at 60℃ for 1 hour, and then drying at 120℃ for 8 hours to obtain ceramic blanks; 7) The relevant properties were measured in accordance with QB / T 1548-2015 "Method for Determination of Linear Shrinkage of Ceramic Body Clay".

[0036] Example 4 A method for preparing a low-shrinkage ceramic green body includes the following steps: 1) The mass ratio of solid raw material to liquid raw material in ceramic blank is controlled to be 1:4, wherein the liquid raw material is aluminum sol, and the solid raw material is composed of the following components in parts by mass: Al(OH)3: 20 parts, silica powder: 55 parts, Fe2O3: 0.8 parts, wollastonite: 0.2 parts, MgO: 0.1 parts; 2) Yttrium oxide, neodymium oxide and samarium oxide were mixed in a mass ratio of 60:27:13 to obtain rare earth oxides. γ-Al2O3 was added in a mass ratio of rare earth oxides to γ-Al2O3 of 40:60. Pure water was used as a dispersant to prepare a solution with a solid content of 5%. The solution was then wet-milled at a ball milling speed of 13 m / s and a grinding temperature of 15℃ until D90=700nm to obtain a rare earth alumina dispersion. 3) The rare earth alumina dispersion and polystyrene (PS) colloid were mechanically mixed uniformly at a mass ratio of 10:90. The mixture was then spray-dried at a feed rate of 0.1 L / min through a 210°C nozzle to obtain RE-A. 4) The prepared RE-A was immersed in a 5% (w / w) polyethylene glycol solution (PEG-400), left to stand for 1 hour, and then taken out and dried in a 60℃ oven to obtain modified RE-A. 5) Mix the total mass of solid and liquid raw materials with the mass of modified RE-A at a ratio of 99.9:0.1, and use a disperser to continuously stir at 700 r / min for 15 min to mix the slurry evenly. Then, pour the mixture into a gypsum mold at a uniform speed to cast the slurry. 6) Aging at 26℃ for 4 hours, drying at 45℃ for 2 hours, and then drying at 90℃ for 8 hours to obtain ceramic blanks; 7) The relevant properties were measured in accordance with QB / T 1548-2015 "Method for Determination of Linear Shrinkage of Ceramic Body Clay".

[0037] Example 5 A method for preparing a low-shrinkage ceramic green body includes the following steps: 1) Control the mass ratio of solid raw material to liquid raw material in ceramic blank to be 1:1, wherein the liquid raw material is zirconium sol, and the solid raw material is composed of the following components in parts by mass: bauxite: 60 parts, quartz sand: 80 parts, Fe2O3: 2 parts, calcium feldspar: 5 parts, MgO: 1 part. 2) Lanthanum samarium oxide and γ-Al2O3 were added to γ-Al2O3 at a mass ratio of 70:30. Pure water was used as a dispersant to prepare a mixture with 80% solid content. The mixture was then wet-milled at a ball milling speed of 1 m / s and a grinding temperature of 40℃ until D90=1000 nm to obtain a rare earth alumina dispersion. 3) The rare earth alumina dispersion and polystyrene (PS) colloid were mechanically mixed uniformly at a mass ratio of 1:1. The mixture was then spray-dried at a feed rate of 60 L / min through a 280°C nozzle to obtain RE-A. 4) The prepared RE-A was immersed in a 50% (w / w) polyethylene glycol solution (PEG-400), left to stand for 1 hour, then removed and dried in a 60℃ oven to obtain modified RE-A; 5) Mix the total mass of solid and liquid raw materials with the mass of modified RE-A at a ratio of 90:10, and use a disperser to continuously stir at 700 r / min for 15 min to mix the slurry evenly. Then, pour the mixture into a gypsum mold at a uniform speed to cast the slurry. 6) Aging at 30℃ for 8 hours, drying at 60℃ for 0.5 hours, and then drying at 120℃ for 4 hours to obtain ceramic blanks; 7) The relevant properties were measured in accordance with QB / T 1548-2015 "Method for Determination of Linear Shrinkage of Ceramic Body Clay".

[0038] Comparative Example 1 The preparation method was basically the same as in Example 1, except that the mass ratio of solid raw material to liquid raw material was 7:3. The results showed that the ceramic blank contained too little liquid raw material, resulting in low fluidity, which affected the stirring and casting process, leading to numerous defects after molding and making performance testing impossible.

[0039] Comparative Example 2 The preparation method was basically the same as in Example 1, except that Al2O3 accounted for 75wt% and SiO2 accounted for 25wt%. The results showed that the prepared slurry agglomerated, forming a paste with very low fluidity, which affected the stirring and slurry injection process. After molding, there were many defects, making it impossible to test the performance.

[0040] Comparative Example 3 The preparation method is basically the same as in Example 1, except that the mass ratio of modified RE-A to the total mass of solid and liquid raw materials is 2:8. Excessive addition of rare earth porous microspheres leads to excessively high porosity inside the green body. Although the shrinkage rate decreases slightly, the flexural strength decreases significantly, failing to meet the application requirements.

[0041] Comparative Example 4 The preparation method is basically the same as in Example 1, except that lanthanum oxide and yttrium oxide are not subjected to a pelletizing process and are directly added to the solid and liquid raw materials. Rare earth powders cannot form "support sites" and cannot effectively suppress volume shrinkage, resulting in a significantly higher drying shrinkage rate than in the example.

[0042] Comparative Example 5 The preparation method is basically the same as in Example 1, except that RE-A is added directly to the solid and liquid raw materials without surface impregnation modification with polyethylene glycol solution. Although this comparative scheme can reduce the shrinkage rate of the green body to a certain extent, the lack of chemical bonding between RE-A and the ceramic clay interface results in insufficient bonding force, ultimately leading to a significant decrease in the flexural strength of the ceramic green body.

[0043] Table 1: Performance Data Sheet

[0044] As shown in Table 1, the ceramic green bodies prepared in the embodiments of the present invention have a molding qualification rate of ≥95% and a drying shrinkage rate of only 1.3%-1.7%, which is significantly lower than that of conventional ceramic green bodies (≤6.5%). They also maintain good flexural strength (3.9-4.7 MPa) and slurry absorption rate (7.6-9.4 mm / 45 min), and their overall performance is superior to existing technologies. Comparative Examples 1 and 2 had numerous defects after molding due to raw material ratios not conforming to the limits of the present invention, making performance testing impossible. Comparative Example 3 suffered from insufficient strength due to excessive rare earth element addition. Comparative Example 4 failed to achieve the desired shrinkage reduction effect because it did not employ a pelletizing process. Comparative Example 5 resulted in a significant decrease in the flexural strength of the ceramic green body due to the lack of RE-A modification.

[0045] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ceramic green body with low shrinkage rate, characterized in that: The mixture comprises solid-phase raw materials, liquid-phase raw materials, and modified rare-earth alumina microspheres. The mass ratio of the solid-phase raw materials to the liquid-phase raw materials is (2-5):(5-8), and the ratio of the amount of modified rare-earth alumina microspheres added to the total mass of the solid-phase raw materials and liquid-phase raw materials is (0.1-10):(90-99.9). The solid-phase raw materials comprise the following components in parts by mass: 20.0-60.0 parts aluminum source, 55.0-80.0 parts silicon source, 0.8-2.0 parts Fe2O3, 0.2-5.0 parts calcium source, and 0.1-1.0 parts MgO.

2. The low-shrinkage ceramic green body according to claim 1, characterized in that: The method for preparing the modified rare earth alumina microspheres is as follows: 1) Rare earth oxides and γ-Al2O3 were mixed and wet ball milled until 500nm≤D90≤1000nm to obtain a rare earth alumina dispersion; 2) Rare earth alumina dispersion was mixed with polystyrene colloid, and the mixture was spray-dried to obtain rare earth alumina microspheres; 3) Immerse rare earth alumina microspheres in polyethylene glycol solution and let them stand for a period of time. Dry the immersed rare earth alumina microspheres to form a stable layer on their surface, which is the modified rare earth alumina microsphere.

3. The low-shrinkage ceramic green body according to claim 2, characterized in that: The mass ratio of the rare earth oxide to γ-Al2O3 is (40-70):(30-60).

4. The low-shrinkage ceramic green body according to claim 2, characterized in that: In step 1), after the rare earth oxides and γ-Al2O3 are mixed, the solid content of the mixture slurry is adjusted to 5%-80% before ball milling. The linear speed of the ball mill is 1-13 m / s, and the grinding temperature is controlled at 15-40℃. In step 2), the mixture system is spray-dried at a feed rate of 0.1-60 L / min through a nozzle at 210-280℃.

5. The low-shrinkage ceramic green body according to claim 2, characterized in that: The polyethylene glycol solution has a mass fraction of 5%-50%.

6. The low-shrinkage ceramic green body according to claim 1, characterized in that: The aluminum source is one or more of alumina, aluminum hydroxide, aluminum silicate, bauxite, aluminum ash, kaolin, coal gangue, and bentonite; the silicon source is one or more of silicon oxide, quartz sand, silica powder, and silicates; and the calcium source is one or more of calcium oxide, wollastonite, anorthite, and calcite.

7. The low-shrinkage ceramic green body according to claim 1, characterized in that: The liquid phase raw material is one or more of water, silica sol, aluminum sol, and zirconium sol.

8. The low-shrinkage ceramic green body according to claim 2, characterized in that: The rare earth oxides include one or more of lanthanum oxide, cerium oxide, samarium oxide, praseodymium oxide, neodymium oxide, europium oxide, gadolinium oxide, yttrium oxide, lanthanum cerium oxide, and lanthanum samarium oxide.

9. The method for preparing the low-shrinkage ceramic green body according to any one of claims 1-8, characterized in that: Includes the following steps: Solid raw materials, liquid raw materials and modified rare earth alumina microspheres are mixed and stirred evenly using a disperser. The mixture is then poured into a gypsum mold at a uniform speed to form the ceramic blank. After aging, demolding and drying, the ceramic blank is obtained.

10. A ceramic article prepared from the ceramic blank according to any one of claims 1-8.

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