An alumina ceramic, its preparation method and application

Abstract

The present invention relates to the technical field of alumina ceramics, and discloses an alumina ceramic, a preparation method thereof and an application. In the present invention, water, alumina, and a sulfonate dispersant are added to a planetary ball mill, followed by ball milling, drying, pressing into a green body, and sintering to obtain the alumina ceramic. The sodium sulfonate group of the sulfonate dispersant has a strong interaction with the surface of alumina, realizing surface modification of alumina particles, acting as a dispersant, which can inhibit the agglomeration of alumina particles and improve the dispersibility. At the same time, the dispersant is a polymer molecular chain with a large number of sodium sulfonate groups in the side chain, which can form interactions with multiple alumina particles, thus acting as a binder, significantly improving the densification, relative density and flexural strength of the alumina ceramic.

Description

Technical Field

[0001] The present invention relates to the technical field of alumina ceramics, and specifically relates to an alumina ceramic, a preparation method thereof, and an application thereof. Background Art

[0002] Alumina ceramics have excellent properties such as good wear resistance, corrosion resistance, and high temperature resistance, and are widely used in fields such as advanced ceramic materials, electronic packaging, automobile manufacturing, and metallurgical industry. Adding dispersants and binder aids such as sodium polyacrylate, sodium dodecyl sulfonate, polyethylene glycol, and phenolic resin to alumina ceramics can improve the dispersibility of alumina and enhance the mechanical strength of the ceramics.

[0003] Developing new dispersants for alumina is a research hotspot. The Chinese invention patent with the publication number CN117776238A discloses a preparation method of spherical alumina powder with good dispersibility. Using aluminum nitrate, ammonium sulfate, polysiloxane-polyester sulfonate dispersant, urea, etc. as raw materials, the prepared alumina has advantages such as a smooth surface and good dispersibility. However, the alumina in this patent does not exhibit good mechanical strength, which is not conducive to its practical application in high-strength ceramic materials. Summary of the Invention

[0004] The present invention solves the problem of relatively low mechanical strength of alumina ceramics.

[0005] The technical solution provided by the present invention: A preparation method of an alumina ceramic:

[0006] (1) Add an aqueous solution of glutaraldehyde and a diamine compound to ethanol, stir and react at 30 - 45 °C for 6 - 10 h, then add sodium borohydride, and stir and react at 20 - 30 °C for 4 - 6 h. Distill off ethanol under reduced pressure, wash with water, and dry to obtain a dispersant precursor.

[0007] (2) Add the dispersant precursor and 1,3 - propane sultone to 1,4 - dioxane, heat up to 70 - 90 °C, and stir and react for 5 - 8 h. After the reaction, add an aqueous sodium hydroxide solution to adjust the pH to 7.5 - 8, distill off 1,4 - dioxane under reduced pressure, wash with ethanol, and dry to obtain a sulfonate dispersant. The reaction formula is:

[0008] .

[0009] (3) Add water, alumina, and a sulfonate dispersant accounting for 1 - 4% of the mass of alumina to a planetary ball mill for ball milling. Pour the ball - milled slurry into a mold, place it in an oven for drying, then press the material into a green body, and finally sinter it in a sintering furnace, cool it to obtain an alumina ceramic.

[0010] Preferably, the molar ratio of glutaraldehyde, diamine compound, and sodium borohydride in (1) is 1:(1 - 1.05):(1.2 - 1.4).

[0011] Preferably, the molecular formula of the diamine compound is NH2(CH2) n NH2, where n is any integer from 2 to 5.

[0012] Preferably, the mass of 1,3 - propanesultone in (2) is 10 - 30% of the mass of the dispersant precursor.

[0013] Preferably, when adding to ball milling in (3), the rotation speed is 300 - 600 r / min, and the time is 3 - 5 h.

[0014] Preferably, in (3), the pressure during sintering is 10 - 15 MPa, the temperature is 1200 - 1400 °C, and the time is 2 - 3 h.

[0015] Preferably, the alumina ceramic is applied to high - strength ceramic materials.

[0016] Technical effect: The present invention uses an aqueous solution of glutaraldehyde, diamine compound, 1,3 - propanesultone, etc. as reactants to prepare a sulfonate dispersant. It contains sodium sulfonate groups and has a strong interaction with the alumina surface, realizing surface modification of alumina particles, acting as a dispersant, which can inhibit the agglomeration of alumina particles and improve the dispersibility. At the same time, the dispersant is a polymer molecular chain with a large number of sodium sulfonate groups on the side chain, which can form interactions with multiple alumina particles, thus acting as a binder and significantly improving the densification, relative density, and flexural strength of the alumina ceramic. Detailed implementation mode

[0017] In order to be able to understand the technical features and content of the present invention in detail, the preferred implementation modes of the present invention will be described in more detail below.

[0018] The average particle size of the following alumina is 5 μm.

[0019] Example 1:

[0020] (1) Add 10 mL of an aqueous solution containing 40 mmol of glutaraldehyde and 40 mmol of 1,3 - propanediamine to 120 mL of ethanol, react at 30 °C for 10 h, then add 56 mmol of sodium borohydride, react at 20 °C for 6 h, remove ethanol by vacuum distillation, wash with water, and dry to obtain a dispersant precursor.

[0021] (2) Add 20 g of the dispersant precursor and 2 g of 1,3 - propane sultone to 1,4 - dioxane. Heat the mixture to 80 °C and stir - react for 8 h. Add an aqueous sodium hydroxide solution to adjust the pH to 7.5. Remove 1,4 - dioxane by vacuum distillation, wash with ethanol, and dry to obtain the sulfonate dispersant.

[0022] (3) Add 3 L of water, 1 kg of alumina, and 10 g of the sulfonate dispersant to a planetary ball mill. Perform ball - milling for 3 h, controlling the rotation speed at 500 r / min. Pour the ball - milled slurry into a mold, dry it in an oven, then press the material into a green body using a molding press with a pressure of 25 MPa. Finally, sinter it in a sintering furnace, controlling the sintering pressure at 10 MPa, the temperature at 1400 °C, and the sintering time at 2 h. Cool to obtain alumina ceramics.

[0023] Example 2:

[0024] (1) Add 10 mL of an aqueous solution containing 40 mmol of glutaraldehyde and 40 mmol of ethylenediamine to 150 mL of ethanol. React at 45 °C for 8 h, then add 48 mmol of sodium borohydride and react at 25 °C for 6 h. Remove ethanol by vacuum distillation, wash with water, and dry to obtain the dispersant precursor.

[0025] (2) Add 20 g of the dispersant precursor and 4 g of 1,3 - propane sultone to 1,4 - dioxane. Heat the mixture to 70 °C and stir - react for 8 h. Add an aqueous sodium hydroxide solution to adjust the pH to 7.5. Remove 1,4 - dioxane by vacuum distillation, wash with ethanol, and dry to obtain the sulfonate dispersant.

[0026] (3) Add 3 L of water, 1 kg of alumina, and 20 g of the sulfonate dispersant to a planetary ball mill. Perform ball - milling for 5 h, controlling the rotation speed at 300 r / min. Pour the ball - milled slurry into a mold, dry it in an oven, then press the material into a green body using a molding press with a pressure of 20 MPa. Finally, sinter it in a sintering furnace, controlling the sintering pressure at 15 MPa, the temperature at 1200 °C, and the sintering time at 3 h. Cool to obtain alumina ceramics.

[0027] Example 3:

[0028] (1) Add 10 mL of an aqueous solution containing 40 mmol of glutaraldehyde and 42 mmol of 1,5 - pentanediamine to 150 mL of ethanol. React at 45 °C for 6 h, then add 52 mmol of sodium borohydride and react at 30 °C for 4 h. Remove ethanol by vacuum distillation, wash with water, and dry to obtain the dispersant precursor.

[0029] (2) Add 20 g of dispersant precursor and 6 g of 1,3 - propane sultone to 1,4 - dioxane. Heat the mixture to 90 °C and stir - react for 5 h. Add an aqueous sodium hydroxide solution to adjust the pH to 8. Remove 1,4 - dioxane by reduced - pressure distillation, wash with ethanol, and dry to obtain the sulfonate dispersant.

[0030] (3) Add 3.5 L of water, 1 kg of alumina, and 30 g of sulfonate dispersant to a planetary ball mill. Ball - mill for 4 h, control the rotation speed at 300 r / min. Pour the ball - milled slurry into a mold, dry it in an oven, then press the material into a green body through a molding press with a pressure of 25 MPa. Finally, sinter in a sintering furnace, control the sintering pressure at 15 MPa, the temperature at 1300 °C, and the sintering time at 3 h, and then cool to obtain alumina ceramics.

[0031] Example 4:

[0032] (1) Add 4 L of water, 1 kg of alumina, and 40 g of sulfonate dispersant (prepared in the same way as in Example 1) to a planetary ball mill. Ball - mill for 5 h, control the rotation speed at 600 r / min. Pour the ball - milled slurry into a mold, dry it in an oven, then press the material into a green body through a molding press with a pressure of 20 MPa. Finally, sinter in a sintering furnace, control the sintering pressure at 15 MPa, the temperature at 1400 °C, and the sintering time at 2 h, and then cool to obtain alumina ceramics.

[0033] Comparative Example 1. The difference between this comparative example and Example 1 is that no sulfonate dispersant is added.

[0034] (1) Add 3 L of water and 1 kg of alumina to a planetary ball mill. Ball - mill for 3 h, control the rotation speed at 500 r / min. Pour the ball - milled slurry into a mold, dry it in an oven, then press the material into a green body through a molding press with a pressure of 25 MPa. Finally, sinter in a sintering furnace, control the sintering pressure at 10 MPa, the temperature at 1400 °C, and the sintering time at 2 h, and then cool to obtain alumina ceramics.

[0035] Comparative Example 2: The difference between this comparative example and Example 1 is that a dispersant precursor is added.

[0036] (1) Add 3 L of water, 1 kg of alumina, and 10 g of dispersant precursor to a planetary ball mill. Ball - mill for 3 h, control the rotation speed at 500 r / min. Pour the ball - milled slurry into a mold, dry it in an oven, then press the material into a green body through a molding press with a pressure of 25 MPa. Finally, sinter in a sintering furnace, control the sintering pressure at 10 MPa, the temperature at 1400 °C, and the sintering time at 2 h, and then cool to obtain alumina ceramics.

[0037] Comparative Example 3: The difference between this comparative example and Example 1 is that sodium dodecylbenzenesulfonate is added.

[0038] (1) Add 3 L of water, 1 kg of alumina, and 10 g of sodium dodecyl sulfonate to a planetary ball mill, and ball mill for 3 h. Control the rotation speed at 500 r / min. Pour the ball-milled slurry into a mold, place it in an oven for drying, and then press the material into a green body through a molding press with a pressure of 25 MPa. Finally, sinter in a sintering furnace, control the sintering pressure at 10 MPa, the temperature at 1400 °C, and the sintering time at 2 h, and then cool to obtain alumina ceramics.

[0039] Test the relative density of the alumina ceramic samples according to the Archimedes method. Each specimen is tested 5 times, and the average value is taken.

[0040] Test the flexural strength of the alumina ceramic samples by the three-point bending method. The specimen size is 35 mm × 4 mm × 3 mm, and the loading rate is 0.5 mm / min. The test results are shown in Table 1.

[0041] Table 1 Performance Test of Alumina Ceramics

[0042]

[0043] After testing, compared with Comparative Example 1, in Examples 1-4, a sulfonate dispersant is added, which contains a sodium sulfonate group and has a strong interaction with the alumina surface, realizing the surface modification of alumina particles, acting as a dispersant, and can inhibit the agglomeration of alumina particles and improve the dispersibility. At the same time, the dispersant is a polymer molecular chain, and the side chain contains a large number of sodium sulfonate groups, which can form interactions with multiple alumina particles, thus acting as a binder and significantly improving the densification, relative density, and flexural strength of alumina ceramics.

[0044] The dispersant precursor added in Comparative Example 2 does not contain a sodium sulfonate group and has a weak interaction with the alumina surface, so it cannot effectively act as a dispersant and binder, and the relative density and flexural strength of the alumina ceramics are low.

[0045] Comparative Example 3 uses conventional sodium dodecyl sulfonate as a dispersant, which is beneficial to improving the relative density and flexural strength of the alumina coating, but sodium dodecyl sulfonate cannot act as a binder, resulting in the relative density and flexural strength of the ceramic being lower than that of Example 1.

[0046] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing alumina ceramics, characterized in that, The preparation method is as follows: (1) Add an aqueous solution of glutaraldehyde and ethylenediamine to ethanol, react at 30 - 45 °C for 6 - 10 h, then add sodium borohydride, and react at 20 - 30 °C for 4 - 6 h. Distill off ethanol under reduced pressure, wash with water, and dry to obtain a dispersant precursor; (2) Add the dispersant precursor and 1,3 - propane sultone to 1,4 - dioxane. After reaction, add an aqueous sodium hydroxide solution to adjust the pH. Distill off 1,4 - dioxane under reduced pressure, wash with ethanol, and dry to obtain a sulfonate dispersant; (3) Add water, alumina, and a sulfonate dispersant accounting for 1 - 4% of the mass of alumina to a planetary ball mill for ball milling. Pour the ball - milled slurry into a mold, place it in an oven for drying, then press the material into a green body, and finally sinter it in a sintering furnace, cool to obtain alumina ceramics; The average particle size of the alumina is 5 μm; the molar ratio of glutaraldehyde, ethylenediamine, and sodium borohydride in (1) is 1:1:1.2; the mass of 1,3 - propane sultone in (2) is 10 - 30% of the mass of the dispersant precursor; the reaction temperature in (2) is 70 - 90 °C, and the reaction time is 5 - 8 h; in (2), add an aqueous sodium hydroxide solution to adjust the pH to 7.5 - 8; the rotation speed during ball milling in (3) is 300 - 600 r / min, the time is 3 - 5 h, the pressure during sintering is 10 - 15 MPa, the temperature is 1200 - 1400 °C, and the time is 2 - 3 h.

2. An alumina ceramic obtained by the preparation method as described in claim 1.

3. An application of the alumina ceramic as described in claim 2 in high - strength ceramic materials.

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