Alumina ceramic as well as preparation method and application thereof

Abstract

The invention relates to the technical field of aluminum oxide ceramics, and discloses an aluminum oxide ceramic and a preparation method and application thereof.The preparation method comprises the steps that water, aluminum oxide and a sulfonate dispersing agent are added into a planetary ball mill, ball milling, drying, pressing into a green body and sintering are conducted, and the aluminum oxide ceramic is obtained. Sodium sulfonate groups of the sulfonate dispersant have strong interaction with the surface of aluminum oxide, surface modification of aluminum oxide particles is realized, the effect of the dispersant is achieved, agglomeration of the aluminum oxide particles can be inhibited, the dispersity is improved, meanwhile, the dispersant is a polymer molecular chain, and a side chain contains a large number of sodium sulfonate groups, so that the dispersion is more uniform. The aluminum oxide particles can interact with a plurality of aluminum oxide particles, so that the effect of a binder is achieved, and the compactness, the relative density and the bending strength of the aluminum oxide ceramic are remarkably improved.

Description

Technical Field

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

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

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

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

[0005] The technical solution provided by the present invention is: a method for preparing alumina ceramics: (1) Add an aqueous solution of glutaraldehyde and a diamine compound to ethanol, stir and react at 30-45°C for 6-10 hours, then add sodium borohydride, stir and react at 20-30°C for 4-6 hours, remove ethanol by vacuum distillation, wash with water, and dry to obtain a dispersant precursor.

[0006] (2) Add dispersant precursor and 1,3-propane sultone to 1,4-dioxane, raise the temperature to 70-90°C, and stir to react for 5-8 hours. After the reaction, add sodium hydroxide aqueous solution to adjust the pH to 7.5-8, remove 1,4-dioxane by vacuum distillation, wash with ethanol, and dry to obtain a sulfonate dispersant. The reaction formula is: .

[0007] (3) Add water, alumina, and 1-4% by mass of alumina sulfonate dispersant into a planetary ball mill for ball milling. Pour the milled slurry into a mold, place it in an oven for drying, and then press the material into a green body. Finally, sinter it in a sintering furnace and cool it to obtain alumina ceramics.

[0008] Preferably, the molar ratio of glutaraldehyde, diamine compound and sodium borohydride in (1) is 1:(1-1.05):(1.2-1.4).

[0009] Preferably, the molecular formula of the diamine compound is NH2(CH2) n NH2, n is any integer from 2 to 5.

[0010] Preferably, the mass of 1,3-propane sultone in (2) is 10-30% of the mass of the dispersant precursor.

[0011] Preferably, (3) the rotation speed during ball milling is 300-600 r / min, and the time is 3-5 h.

[0012] Preferably, in (3), the sintering pressure is 10-15 MPa, the temperature is 1200-1400° C., and the sintering time is 2-3 h.

[0013] Preferably, alumina ceramics are used in high-strength ceramic materials.

[0014] Technical effect: The present invention uses an aqueous solution of glutaraldehyde, a diamine compound, 1,3-propane sultone, etc. as reactants to prepare a sulfonate dispersant, which contains a sodium sulfonate group and has a strong interaction with the surface of alumina, thereby achieving surface modification of alumina particles and playing the role of a dispersant. It can inhibit the agglomeration of alumina particles and improve 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 interact with multiple alumina particles, thereby playing the role of a binder, significantly improving the compactness, relative density and flexural strength of alumina ceramics. DETAILED DESCRIPTION

[0015] In order to enable a detailed understanding of the technical features and contents of the present invention, the preferred embodiments of the present invention will be described in more detail below.

[0016] The average particle size of the following alumina is 5 μm.

[0017] Embodiment 1: (1) Add 10 mL of an aqueous solution containing 40 mmol of glutaraldehyde and 40 mmol of 1,3-propylenediamine to 120 mL of ethanol, and react at 30°C for 10 h. Then add 56 mmol of sodium borohydride and react at 20°C for 6 h. Remove ethanol by vacuum distillation, wash with water, and dry to obtain a dispersant precursor.

[0018] (2) Add 20 g of dispersant precursor and 2 g of 1,3-propane sultone to 1,4-dioxane, raise the temperature to 80°C, stir and react for 8 h, add sodium hydroxide aqueous solution to adjust the pH to 7.5, remove 1,4-dioxane by vacuum distillation, wash with ethanol, and dry to obtain a sulfonate dispersant.

[0019] (3) Add 3 L of water, 1 kg of alumina, and 10 g of sulfonate dispersant to a planetary ball mill and perform ball milling for 3 h at a speed of 500 r / min. Pour the milled slurry into a mold and place it in an oven to dry. Then, the material is pressed into a green body by a molding machine at a pressure of 25 MPa. Finally, it is sintered in a sintering furnace at a pressure of 10 MPa, a temperature of 1400°C, and a sintering time of 2 h. After cooling, alumina ceramics are obtained.

[0020] Embodiment 2: (1) Add 10 mL of an aqueous solution containing 40 mmol of glutaraldehyde and 40 mmol of ethylenediamine to 150 mL of ethanol, and react at 45 °C for 8 h. Then add 48 mmol of sodium borohydride and react at 25 °C for 6 h. Remove the ethanol by vacuum distillation, wash with water, and dry to obtain a dispersant precursor.

[0021] (2) Add 20 g of dispersant precursor and 4 g of 1,3-propane sultone to 1,4-dioxane, raise the temperature to 70°C, stir and react for 8 h, add sodium hydroxide aqueous solution to adjust the pH to 7.5, remove 1,4-dioxane by vacuum distillation, wash with ethanol, and dry to obtain a sulfonate dispersant.

[0022] (3) Add 3 L of water, 1 kg of alumina, and 20 g of sulfonate dispersant to a planetary ball mill and perform ball milling for 5 h at a speed of 300 r / min. Pour the milled slurry into a mold and dry it in an oven. Then, press the material into a green body through a molding machine at a pressure of 20 MPa. Finally, sinter it in a sintering furnace at a pressure of 15 MPa, a temperature of 1200 °C, and a sintering time of 3 h. After cooling, alumina ceramics are obtained.

[0023] Embodiment 3: (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, and react at 45°C for 6 h. Then add 52 mmol of sodium borohydride and react at 30°C for 4 h. Remove the ethanol by vacuum distillation, wash with water, and dry to obtain a dispersant precursor.

[0024] (2) Add 20 g of dispersant precursor and 6 g of 1,3-propane sultone to 1,4-dioxane, raise the temperature to 90°C, stir and react for 5 h, add sodium hydroxide aqueous solution to adjust the pH to 8, remove 1,4-dioxane by vacuum distillation, wash with ethanol, and dry to obtain a sulfonate dispersant.

[0025] (3) Add 3.5 L of water, 1 kg of alumina, and 30 g of sulfonate dispersant into a planetary ball mill and perform ball milling for 4 h at a speed of 300 r / min. Pour the milled slurry into a mold and dry it in an oven. Then, press the material into a green body through a molding machine at a pressure of 25 MPa. Finally, sinter it in a sintering furnace at a pressure of 15 MPa, a temperature of 1300 °C, and a sintering time of 3 h. After cooling, alumina ceramics are obtained.

[0026] Embodiment 4: (1) Add 4 L of water, 1 kg of alumina, and 40 g of sulfonate dispersant (the same preparation method as in Example 1) into a planetary ball mill and perform ball milling for 5 h at a speed of 600 r / min. Pour the milled slurry into a mold and dry it in an oven. Then, press the material into a green body through a molding machine at a pressure of 20 MPa. Finally, sinter the green body in a sintering furnace at a pressure of 15 MPa, a temperature of 1400°C, and a sintering time of 2 h. After cooling, alumina ceramics are obtained.

[0027] Comparative Example 1: The difference between this comparative example and Example 1 is that no sulfonate dispersant is added.

[0028] (1) Add 3 L of water and 1 kg of alumina into a planetary ball mill and mill for 3 h at a speed of 500 r / min. Pour the milled slurry into a mold and dry it in an oven. Then, press the material into a green body through a molding machine at a pressure of 25 MPa. Finally, sinter it in a sintering furnace at a pressure of 10 MPa, a temperature of 1400 °C, and a sintering time of 2 h. After cooling, alumina ceramics are obtained.

[0029] Comparative Example 2: The difference between this comparative example and Example 1 is that a dispersant precursor is added.

[0030] (1) Add 3 L of water, 1 kg of alumina, and 10 g of dispersant precursor to a planetary ball mill and perform ball milling for 3 h at a speed of 500 r / min. Pour the milled slurry into a mold and dry it in an oven. Then, press the material into a green body through a molding machine at a pressure of 25 MPa. Finally, sinter it in a sintering furnace at a pressure of 10 MPa, a temperature of 1400 °C, and a sintering time of 2 h. After cooling, alumina ceramics are obtained.

[0031] Comparative Example 3: The difference between this comparative example and Example 1 is that sodium dodecylbenzene sulfonate is added.

[0032] (1) Add 3 L of water, 1 kg of alumina, and 10 g of sodium dodecyl sulfate to a planetary ball mill and perform ball milling for 3 h at a speed of 500 r / min. Pour the milled slurry into a mold and place it in an oven to dry. Then, the material is pressed into a green body by a molding machine at a pressure of 25 MPa. Finally, the green body is sintered in a sintering furnace at a pressure of 10 MPa, a temperature of 1400°C, and a sintering time of 2 h. After cooling, alumina ceramics are obtained.

[0033] The relative density of alumina ceramic samples was tested according to the Archimedes method. Each sample was tested 5 times and the average value was taken.

[0034] The three-point bending method was used to test the flexural strength of alumina ceramic samples, the sample size was 35 mm × 4 mm × 3 mm, and the loading rate was 0.5 mm / min. The test results are shown in Table 1.

[0035] Table 1 Alumina ceramic performance test

[0036] After testing, compared with Comparative Example 1, Examples 1-4 added sulfonate dispersants, which contain sodium sulfonate groups and have a strong interaction with the surface of alumina, thereby achieving surface modification of the alumina particles and playing the role of a dispersant. It can inhibit the agglomeration of alumina particles and improve 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 interact with multiple alumina particles, thereby playing the role of a binder, significantly improving the density, relative density and flexural strength of the alumina ceramic.

[0037] The dispersant precursor added in Comparative Example 2 does not contain a sodium sulfonate group, and has a weak interaction with the surface of alumina, and cannot effectively play the role of a dispersant and a binder. The relative density and flexural strength of the alumina ceramic are low.

[0038] Comparative Example 3 uses conventional sodium dodecyl sulfate as a dispersant, which is beneficial to improving the relative density and flexural strength of the aluminum oxide coating. However, sodium dodecyl sulfate cannot act as a binder, resulting in the relative density and flexural strength of the ceramic being lower than those of Example 1.

[0039] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing alumina ceramics, characterized in that: The preparation method is: (1) Adding an aqueous solution of glutaraldehyde and a diamine compound to ethanol, reacting at 30-45° C. for 6-10 hours, then adding sodium borohydride, reacting at 20-30° C. for 4-6 hours, removing ethanol by vacuum distillation, washing with water, and drying to obtain a dispersant precursor; (2) adding a dispersant precursor and 1,3-propane sultone to 1,4-dioxane, adding a sodium hydroxide aqueous solution to adjust the pH after the reaction, removing 1,4-dioxane by vacuum distillation, washing with ethanol, and drying to obtain a sulfonate dispersant; (3) Add water, alumina, and 1-4% by mass of alumina sulfonate dispersant into a planetary ball mill for ball milling. Pour the milled slurry into a mold, place it in an oven for drying, and then press the material into a green body. Finally, sinter it in a sintering furnace and cool it to obtain alumina ceramics.

2. The method for preparing alumina ceramics according to claim 1, characterized in that: The molar ratio of glutaraldehyde, diamine compound and sodium borohydride in (1) is 1:(1-1.05):(1.2-1.4).

3. The method for preparing alumina ceramics according to claim 1, characterized in that: The molecular formula of the diamine compound is NH2(CH2) n NH2, n is any integer from 2 to 5.

4. The method for preparing alumina ceramics according to claim 1, characterized in that: The mass of 1,3-propane sultone in (2) is 10-30% of the mass of the dispersant precursor.

5. The method for preparing alumina ceramics according to claim 1, characterized in that: The reaction temperature of (2) is 70-90°C and the reaction time is 5-8h.

6. The method for preparing alumina ceramics according to claim 1, characterized in that: In the step (2), sodium hydroxide aqueous solution is added to adjust the pH to 7.5-8.

7. The method for preparing alumina ceramics according to claim 1, characterized in that: The rotation speed of (3) when added into the ball mill is 300-600 r / min, and the time is 3-5 h.

8. The method for preparing alumina ceramics according to claim 1, characterized in that: In the above (3), the sintering pressure is 10-15 MPa, the temperature is 1200-1400°C, and the time is 2-3 hours.

9. An alumina ceramic obtained by the preparation method according to any one of claims 1 to 7.

10. Use of the alumina ceramic according to claim 8 in high-strength ceramic materials.

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