Special ceramic sintering aid based on BaB4O7-BaB8O13 eutectic

Abstract

The application relates to the field of ceramic material engineering and discloses a special ceramic sintering aid based on eutectic, which is composed of a eutectic mixture, and the molar ratio of the eutectic mixture is derived from precursors with a ratio of 1:4.4. The sintering aid also includes not more than 50% of or, which is used for adjusting the viscosity and reactivity of the sintering aid. The special ceramic sintering aid based on eutectic reduces energy consumption, reduces production cost and carbon emission; is suitable for various types of industrial kilns, including coal-fired kilns, improves the applicability and flexibility in actual production, and can promote the combustion of coal gangue in the sintering process, reduces the demand for external fuel, and reduces the production cost.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials engineering, specifically to a method based on BaB4O7-BaB8O 13 Eutectic special ceramic sintering aid. Background Technology

[0002] Ceramic materials, due to their excellent physical, chemical, and mechanical properties, are widely used in building materials, industrial ceramics, and electronic ceramics. Sintering is a crucial step in the ceramic manufacturing process, directly affecting the densification, microstructure, and final properties of the ceramic material. To lower the sintering temperature, improve sintering efficiency, and enhance the performance of ceramic materials, the use of sintering aids becomes essential. However, current sintering aids still have shortcomings, such as: 1. Traditional sintering aids such as calcium carbonate and magnesium carbonate require high sintering temperatures. High sintering temperatures lead to excessive energy consumption, increasing production costs and carbon emissions. 2. Although redox-sensitive sintering aid systems show good results in oxidizing environments, they will fail in reducing kiln atmospheres, affecting the sintering process. Therefore, the present invention provides a method based on BaB4O7-BaB8O 13 Special ceramic sintering aids for eutectic processes are used to address the aforementioned problems. Summary of the Invention

[0003] The purpose of this invention is to provide a BaB4O7-BaB8O 13 The special ceramic sintering aids of eutectic are used to solve the problems mentioned in the background art, such as the high energy consumption caused by the high sintering temperature of traditional sintering aids, which increases production costs and carbon emissions, and the failure of traditional sintering aids in reducing kiln atmosphere, which affects the sintering process.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method based on BaB4O7-BaB8O 13 Eutectic special ceramic sintering aid, wherein the sintering aid is composed of BaB4O7 and BaB8O 13 It consists of a eutectic mixture, the molar ratio of which is derived from BaCO3 and H3BO3 precursors in a ratio of 1:4.4.

[0005] As a preferred embodiment of the present invention, the sintering aid further includes no more than 50% by weight of SiO2 or Al2O3, which is used to adjust the viscosity and reactivity of the sintering aid.

[0006] As a preferred embodiment of the present invention, the method for preparing the sintering aid includes the following steps: Step 1: Weigh BaCO3 and H3BO3 to ensure their molar ratio is 1:4.4; Step 2: Place the weighed BaCO3 and H3BO3 powders into a clean container and mix them evenly. Step 3: Place the mixed precursor powder into a crucible and calcine it in a high-temperature furnace at 700-800℃ for 4-8 hours; Step 4: Take out the calcined product, grind it into fine powder, and confirm its phase composition and microstructure by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) observation.

[0007] As a preferred technical solution of the present invention, the calcination in step three can also be replaced by the sol-gel method or the mechanochemical method.

[0008] As a preferred technical solution of the present invention, the high-temperature furnace in step three adopts a constant heating rate, such as 5-10℃ / min, to raise the temperature from room temperature to 700-800℃. Furthermore, after calcination, a self-heating cooling method is used to avoid the calcined material from cracking due to thermal shock caused by rapid cooling.

[0009] As a preferred embodiment of the present invention, the method for sintering aluminosilicate ceramics using the special ceramic sintering aid includes the following steps: Step 1: Accurately weigh the aluminosilicate raw materials, such as shale or coal gangue; Step 2: Based on the weight of the aluminosilicate raw material, accurately weigh the components based on BaB4O7-BaB8O at a ratio of 0.5-5% by weight. 13 Special ceramic sintering aids for eutectic crystals; Step 3: Place the aluminosilicate raw material and sintering aid into a clean mixing container and mix them evenly; Step 4: Select the appropriate molding method according to the required shape and size of the ceramic product. Common molding methods include pressing, slip casting, and extrusion molding. Step 5: Place the mixed raw materials (dry powder or slurry) into the molding mold, apply a certain pressure or use other molding methods to shape the raw materials; Step 6: Place the formed green body in a suitable sintering equipment, such as a tunnel kiln or batch kiln, and sinter at a temperature of 850-950℃.

[0010] As a preferred embodiment of the present invention, the amount of special ceramic sintering aid added in step two is 2% by weight.

[0011] As a preferred embodiment of the present invention, the sintering temperature in step six is ​​990°C.

[0012] As a preferred embodiment of the present invention, the aluminosilicate ceramic comprises BaB4O7-BaB8O 13 The glassy phase formed by eutectic special ceramic sintering aids.

[0013] Compared with the prior art, the beneficial effects of the present invention are: the BaB4O7-BaB8O 13 Eutectic special ceramic sintering aids reduce energy consumption, production costs, and carbon emissions; they are suitable for various types of industrial kilns, including coal-fired kilns, improving their applicability and flexibility in actual production; they can also promote the combustion of coal gangue during sintering, reducing the need for external fuel and lowering production costs. 1. The sintering aid of the present invention can be used at a lower temperature ( Densification of aluminosilicate ceramics was achieved at 950℃, compared to the high temperatures required for traditional sintering aids. (1,100℃), saving approximately 30% in energy, reducing energy consumption, production costs, and carbon emissions; 2. The BaB4O7-BaB8O of the present invention 13 The eutectic mixture can still operate reliably in a reducing atmosphere, ensuring the consistency of liquid phase sintering activation, making the sintering aid suitable for various types of industrial kilns, including coal-fired kilns, and improving its applicability and flexibility in actual production. 3. The sintering aid of the present invention can not only enhance the sintering performance of coal gangue ceramics, but also promote the combustion of coal gangue during the sintering process, reduce the demand for external fuel, and reduce production costs. 4. The sintering aid of the present invention can significantly improve the densification degree and mechanical properties of ceramic materials, making them more suitable for various industrial applications. Attached Figure Description

[0014] Figure 1 The XRD pattern of the barium borate additive synthesized in this invention; Figure 2 This is a SEM image of a ceramic sample containing 2% by weight BaCuO2-CuO after sintering according to the present invention. Figure 3 The present invention contains 2% by weight BaB4O7-BaB8O 13 SEM images of ceramic samples after sintering; Figure 4 This is an electron microscope (EM) microscopic image of shale-based ceramics sintered in the tunnel kiln of this invention; Figure 5 The present invention is BaB4O7-BaB8O 13 Bulk density diagram of ceramic samples sintered in industrial kilns with different contents of liquid phase additives; Figure 6 The present invention is BaB4O7-BaB8O 13 Shale ceramic particle compressive strength diagram. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figure 1-6 This invention provides a technical solution: a method based on BaB4O7 and BaB8O 13 Eutectic special ceramic sintering aid, wherein the sintering aid is composed of BaB4O7 and BaB8O 13 The mixture is composed of a eutectic mixture, the molar ratio of which is derived from BaCO3 and H3BO3 precursors in a ratio of 1:4.4. The sintering aid also includes no more than 50% by weight of SiO2 or Al2O3 to adjust the viscosity and reactivity of the sintering aid. Example 1: Calcination method 1. Preparation of sintering aids Step 1: Prepare for weighing Prepare to weigh BaCO3 and H3BO3, ensuring their molar ratio is mixed to 1:4.4; Step 2: Mix evenly Place the weighed BaCO3 and H3BO3 powders into a clean mortar and mix them with a pestle until they are evenly mixed. The mixing time is 10-30 minutes to ensure that the powders are evenly distributed. Step 3: Calcination The mixed precursor powder was placed in an alumina crucible and then placed in a muffle furnace. The heating rate of the muffle furnace was set to 5-10℃ / min, and the temperature was raised from room temperature to 750℃. Then, it was calcined at 750℃ for 6 hours. Step 4: Product Processing After calcination, the muffle furnace was turned off and allowed to cool naturally to room temperature. The crucible was then removed, and the calcined product was ground into a fine powder. X-ray diffraction (XRD) was used to confirm the phase composition of the product, and scanning electron microscopy (SEM) was used to observe and analyze the microstructure of the product.

[0017] Example 2: Sol-gel method Step 1: Preparation of precursor solution Dissolve BaCO3 and H3BO3 in an appropriate amount of deionized water to form a homogeneous solution. Adjust the pH value to 3-4 and add an appropriate amount of dilute hydrochloric acid as a catalyst to promote hydrolysis and condensation reactions. Step 2: Gel formation Let the solution stand at room temperature for 24 hours to form a gel. During this time, you can stir it appropriately to ensure that the reaction proceeds uniformly. Step 3: Drying and Calcination The formed gel was dried at room temperature for 24 hours to remove moisture. Then the dried gel was placed in a muffle furnace and the heating rate was set to 5-10℃ / min to raise the temperature from room temperature to 750℃. The gel was then sintered at 750℃ for 6 hours. Step 4: Product Processing After calcination, the muffle furnace was turned off and allowed to cool naturally to room temperature. The crucible was then removed, and the calcined product was ground into a fine powder. X-ray diffraction (XRD) was used to confirm the phase composition of the product, and scanning electron microscopy (SEM) was used to observe and analyze the microstructure of the product.

[0018] Example 3: Mechatronics Method Step 1: Mixing raw materials BaCO3 and H3BO3 powders were mixed in a molar ratio of 1:4.4. The mixed powder was then placed in a ball mill, and the ball milling time was set to 8 hours, the ball milling speed to 500 rpm, and the ball-to-material ratio to 10:1. Step 2: Ball milling treatment Start the ball mill to perform ball milling. During the ball milling process, mechanical energy induces a chemical reaction to form the desired eutectic mixture. Step 3: Drying and Calcination The formed gel was dried at room temperature for 24 hours to remove moisture. Then the dried gel was placed in a muffle furnace and the heating rate was set to 5-10℃ / min to raise the temperature from room temperature to 750℃. The gel was then sintered at 750℃ for 6 hours. Step 4: Product Processing After calcination, the muffle furnace was turned off and allowed to cool naturally to room temperature. The crucible was then removed, and the calcined product was ground into a fine powder. X-ray diffraction (XRD) was used to confirm the phase composition of the product, and scanning electron microscopy (SEM) was used to observe and analyze the microstructure of the product.

[0019] 2. Ceramic sintering Step 1: Raw material preparation Accurately weigh aluminosilicate raw materials, such as shale or coal gangue, to ensure that the particle size of the raw materials is within the range of 1-10 micrometers; Step 2: Weighing sintering aids Based on the weight of the aluminosilicate raw material, accurately weigh the sintering aid at a ratio of 2 by weight. For example, if the weight of the aluminosilicate raw material is 1000 grams, then weigh 20 grams of the sintering aid. Step 3: Mixing Place the aluminosilicate raw material and sintering aid into a clean mixing container and mix using a mechanical stirrer for 10-30 minutes to ensure that the sintering aid is evenly distributed in the raw material. Step 4: Molding Select the appropriate molding method based on the desired shape and size of the ceramic product. For example, compression molding involves placing the mixed raw materials into a molding die and applying a pressure of 2.5 MPa to shape the material. Step 5: Sintering When preparing sintering aids and ceramic sintering on a laboratory scale, the formed green body is placed in a muffle furnace, the heating rate of the muffle furnace is set to 5-10℃ / min, the temperature is raised from room temperature to 990℃, and then fired at 990℃ for 3 hours. After sintering, the muffle furnace is turned off and allowed to cool naturally to room temperature. In the industrial-scale preparation of sintering aids and ceramic sintering, the formed green body is placed in a tunnel kiln, and the heating rate of the tunnel kiln is set to 5-10℃ / min, raising the temperature from room temperature to 990℃, and then firing at 990℃ for 3 hours. After sintering, the tunnel kiln is closed and allowed to cool naturally to room temperature. Step Six: Post-processing The sintered ceramic products were removed, ground and polished to make their surfaces smooth, and the compressive strength of the ceramic products was tested using a universal testing machine. The porosity was tested using Archimedes' method of water displacement. The test results showed that the compressive strength of the ceramic products was 128.8 MPa and the porosity was 12.4%.

[0020] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 method based on BaB4O7-BaB8O 13 Eutectic special ceramic sintering aid, characterized in that: The sintering aid consists of BaB4O7 and BaB8O7. 13 It consists of a eutectic mixture derived from BaCO3 and H3BO3 precursors in a molar ratio of 1:4.

4.

2. The method based on BaB4O7-BaB8O as described in claim 1 13 Eutectic special ceramic sintering aid, characterized in that: The sintering aid also includes no more than 50% by weight of SiO2 or Al2O3, used to adjust the viscosity and reactivity of the sintering aid.

3. The method based on BaB4O7-BaB8O as described in claim 1 13 Eutectic special ceramic sintering aid, characterized in that: The method for preparing the sintering aid includes the following steps: Step 1: Weigh BaCO3 and H3BO3 to ensure their molar ratio is 1:4.4; Step 2: Place the weighed BaCO3 and H3BO3 powders into a clean container and mix them evenly. Step 3: Place the mixed precursor powder into a crucible and calcine it in a high-temperature furnace at 700-800℃ for 4-8 hours; Step 4: Take out the calcined product, grind it into fine powder, and confirm its phase composition and microstructure by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM).

4. A method based on BaB4O7-BaB8O as described in claim 2 13 Eutectic special ceramic sintering aid, characterized in that: The sintering aid was prepared using the sol-gel method and the mechanochemical method.

5. A method based on BaB4O7-BaB8O as described in claim 3 13 Eutectic special ceramic sintering aid, characterized in that: The high-temperature furnace in step three uses a constant heating rate of 5-10℃ / min to raise the temperature from room temperature to 700-800℃. Furthermore, after calcination, a self-heating cooling method is used to avoid the calcined material from cracking due to thermal shock caused by rapid cooling.

6. A method based on BaB4O7-BaB8O as described in claim 2 13 Eutectic special ceramic sintering aid, characterized in that: The method for preparing aluminosilicate ceramics using the aforementioned special ceramic sintering aid includes the following steps: Step 1: Accurately weigh the aluminosilicate raw material, shale or coal gangue; Step 2: Based on the weight of the aluminosilicate raw materials, accurately weigh BaB4O7-BaB8O at a ratio of 0.5-5% by weight. 13 Special ceramic sintering aids for eutectic crystals; Step 3: Place the aluminosilicate raw material and sintering aid into a clean mixing container and mix them evenly; Step 4: Select the appropriate molding method according to the required shape and size of the ceramic product. Molding methods include pressing, slip casting, and extrusion molding. Step 5: Place the mixed raw materials into the molding mold, apply a certain pressure or use other molding methods to shape the raw materials; Step 6: Place the formed green body in a suitable sintering equipment, including a tunnel kiln or a batch kiln, and sinter at a temperature of 850-950℃.

7. A method based on BaB4O7-BaB8O as described in claim 6 13 Eutectic special ceramic sintering aid, characterized in that: The amount of special ceramic sintering aid added in step two is 2% by weight.

8. A method based on BaB4O7-BaB8O as described in claim 6 13 Eutectic special ceramic sintering aid, characterized in that: The aluminosilicate ceramic comprises BaB4O7-BaB8O 13 The glassy phase formed by eutectic special ceramic sintering aids.

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