High-sintering activated aluminum oxide ceramic powder and preparation method thereof, and preparation method of aluminum oxide ceramic

Abstract

The invention belongs to the technical field of ceramic materials, and particularly relates to high-sintering activated aluminum oxide ceramic powder and a preparation method thereof, and a preparation method of aluminum oxide ceramic. The aluminum oxide ceramic powder is modified with weak acid, the surface of aluminum oxide can be slightly corroded, the activity of the aluminum oxide ceramic powder is improved, the specific surface area of the aluminum oxide ceramic powder is increased, contact with more surfactants in the secondary modification process is facilitated, and the modification effect is improved; second modification is carried out, through treatment of a surfactant, the activity of the aluminum oxide powder is improved, and meanwhile, the compatibility and dispersity of the aluminum oxide powder are changed, so that the aluminum oxide powder is not agglomerated in a hydrothermal reaction, uniform powder is obtained, and the sintering activity of the powder is improved; the purpose of continuous hydrothermal treatment is that after the primary modification treatment, the surface of the alumina powder is rough and unsmooth, and the morphology of the formed alumina ceramic powder particles is modified by adopting a hydrothermal method, so that the alumina ceramic powder with regular surface morphology and high sintering activity is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic materials, and in particular relates to a high-sintering active alumina ceramic powder and a preparation method thereof, and a preparation method of an alumina ceramic. Background Art

[0002] Alumina ceramics are an important structural and functional material. They are widely used in machinery, electronics, chemicals, automobiles and other fields due to their advantages such as high strength, high hardness, wear resistance and corrosion resistance. However, the sintering activity of alumina ceramics is low, which limits their application in some high-performance fields. Therefore, how to improve the sintering activity of alumina ceramics is an urgent problem to be solved in the current fields of ceramic engineering and science, materials science and engineering, and chemical engineering and technology.

[0003] The existing solutions are mainly to improve the sintering activity of alumina ceramics by changing the preparation method of alumina ceramics. For example, the sintering activity of alumina ceramics can be improved by adding sintering aids, changing the sintering temperature, changing the sintering time, etc. However, these methods often require complex process conditions and may affect other properties of alumina ceramics, such as strength, hardness, wear resistance, etc.

[0004] There are some problems in the existing technology in improving the sintering activity of alumina ceramics. First, the existing methods often require higher temperatures or longer times, which not only increases energy consumption, but may also cause the grain growth of alumina ceramics and reduce their mechanical properties. Second, the existing methods may introduce impurities, affecting the purity and performance of alumina ceramics. Finally, the existing methods may not be able to effectively improve the microstructure of alumina ceramics, resulting in low sintering activity. Summary of the invention

[0005] The purpose of the present invention is to provide a high sintering activity alumina ceramic powder and a preparation method thereof, and a preparation method of alumina ceramics. The method provided by the present invention can further improve the sintering activity of alumina ceramic powder without changing other properties of the alumina ceramic powder and without introducing impurities.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing high-sintering active alumina ceramic powder, comprising the following steps:

[0008] Mixing alumina ceramic powder and weak acid to perform a first modification to obtain a first modified ceramic powder;

[0009] The first modified ceramic powder, a surfactant and water are mixed to perform a second modification to obtain a second modified ceramic powder;

[0010] The second modified ceramic powder is mixed with water to carry out a hydrothermal reaction to obtain the high sintering active alumina ceramic powder.

[0011] Preferably, the weak acid comprises acetic acid; the concentration of the weak acid is 0.05 to 0.2 mol / L;

[0012] The dosage ratio of the alumina ceramic powder to the weak acid is 25-100 g: 0.5-2 L.

[0013] Preferably, the first modification time is 50 to 300 seconds.

[0014] Preferably, the surfactant is oleic acid;

[0015] The mass of the surfactant is 2-10% of the mass of the first modified ceramic powder.

[0016] Preferably, the temperature of the second modification is 45-85° C., and the time is 0.5-2 h.

[0017] Preferably, the temperature of the hydrothermal reaction is 80-180° C., and the time is 12-48 hours.

[0018] The present invention also provides a high sintering active alumina ceramic powder prepared by the preparation method described in the above technical solution, wherein the bulk density of the high sintering active alumina ceramic powder is 1.05-1.08 g / cm 3 .

[0019] The present invention also provides a method for preparing alumina ceramics, comprising the following steps:

[0020] The high sintering active alumina ceramic powder described in the above technical solution is pressed into shape and then sintered to obtain the alumina ceramic.

[0021] Preferably, the compression molding pressure is 100 MPa;

[0022] The density of the formed green body obtained after pressing is 2.38g / cm 3 .

[0023] Preferably, the sintering temperature is 1400°C and the sintering time is 1.8h;

[0024] The density of the alumina ceramic is 3.956 g / cm 3 .

[0025] The present invention provides a method for preparing high-sintering active alumina ceramic powder, comprising the following steps: mixing alumina ceramic powder and a weak acid, performing a first modification, and obtaining a first modified ceramic powder; mixing the first modified ceramic powder, a surfactant, and water, performing a second modification, and obtaining a second modified ceramic powder; mixing the second modified ceramic powder and water, performing a hydrothermal reaction, and obtaining the high-sintering active alumina ceramic powder.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention uses a weak acid to modify the alumina ceramic powder, which can slightly corrode the surface of alumina, increasing its activity on the one hand and increasing its specific surface area on the other hand, so as to facilitate contact with more surfactants during the secondary modification process and improve the modification effect. At the same time, the smaller the particle size of the alumina original crystal, the larger the specific surface area, the easier it is to cause agglomeration, and the more unstable the slurry system is. The present invention avoids the agglomeration problem through modification; a second modification is carried out, through the treatment of surfactant, the activity of the alumina powder is increased while changing its compatibility and dispersibility, so that it does not agglomerate in the hydrothermal reaction, obtaining a uniform powder and improving its sintering activity; the purpose of continuing the hydrothermal treatment is that, because the surface of the alumina powder is rough and not smooth after the first modification treatment, the particle morphology of the formed alumina ceramic powder is modified by the hydrothermal method to obtain a regular surface morphology, thereby obtaining an alumina ceramic powder with high sintering activity.

[0028] (2) The preparation method of the present invention is simple and does not require complicated process conditions, thus avoiding the problem in the prior art of requiring high temperature or long time sintering, which leads to the growth of the grains of the alumina ceramic and reduces its mechanical properties.

[0029] (3) The preparation method of the present invention avoids the introduction of impurities and ensures the purity and performance of the alumina ceramic. Compared with the prior art, the method of the present invention can more effectively improve the microstructure of the alumina ceramic, thereby improving its sintering activity.

[0030] (4) The preparation method of the present invention also modifies the particle morphology of the formed alumina ceramic powder by hydrothermal treatment to obtain a regular surface morphology, thereby obtaining an alumina ceramic powder with high sintering activity. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing high-sintering active alumina ceramic powder, comprising the following steps:

[0032] Mixing alumina ceramic powder and weak acid to perform a first modification to obtain a first modified ceramic powder;

[0033] The first modified ceramic powder, a surfactant and water are mixed to perform a second modification to obtain a second modified ceramic powder;

[0034] The second modified ceramic powder is mixed with water to carry out a hydrothermal reaction to obtain the high sintering active alumina ceramic powder.

[0035] The present invention mixes alumina ceramic powder and weak acid, performs first modification, and obtains first modified ceramic powder.

[0036] In the present invention, the specific surface area of ​​the alumina ceramic powder is preferably 10 to 15 m 2 / g. In the present invention, the weak acid preferably includes acetic acid; the concentration of the weak acid is preferably 0.05-0.2 mol / L; the dosage ratio of the alumina ceramic powder and the weak acid is preferably 25-100g:0.5-2L. In the present invention, the first modification is preferably carried out under stirring, and the time of the first modification is preferably 50-300s. After the first modification, the present invention also preferably includes drying the obtained system. In the present invention, the drying temperature is preferably 60-100°C, and the time is preferably 1-3h. In the present invention, the alumina ceramic powder is modified with a weak acid, which can slightly corrode the surface of alumina, increase its activity, increase its specific surface area, facilitate contact with more surfactants during the secondary modification process, and improve the modification effect.

[0037] In the present invention, the specific surface area of ​​the first modified ceramic powder is preferably 25 to 35 m 2 / g.

[0038] After obtaining the first modified ceramic powder, the present invention mixes the first modified ceramic powder, a surfactant and water to perform a second modification to obtain a second modified ceramic powder.

[0039] In the present invention, the surfactant is preferably oleic acid; the mass of the surfactant is preferably 2-10% of the mass of the first modified ceramic powder. The present invention has no particular limitation on the amount of water, and any amount known to those skilled in the art can be used.

[0040] In the present invention, the mixing process is preferably: after dispersing the first modified ceramic powder in water, a surfactant is added.

[0041] In the present invention, the second modification is preferably carried out under stirring conditions, the temperature of the second modification is preferably 45-85°C, more preferably 50-80°C, more preferably 60-70°C; the time is preferably 0.5-2h, more preferably 1-1.5h; the second modification is preferably carried out under stirring conditions. After the second modification, the present invention also preferably includes drying the obtained system. In the present invention, the drying temperature is preferably 60-120°C, and the time is preferably 0.5-3h. In the present invention, by treating with a surfactant, the activity of the alumina powder is increased while changing its compatibility and dispersibility properties, so that it does not agglomerate in the hydrothermal reaction, a uniform powder is obtained, and its sintering activity is improved.

[0042] After obtaining the second modified ceramic powder, the present invention mixes the second modified ceramic powder with water to perform a hydrothermal reaction to obtain the high sintering active alumina ceramic powder.

[0043] The present invention does not have any special limitation on the amount of water, and the amount familiar to those skilled in the art may be adopted. In the present invention, the temperature of the hydrothermal reaction is preferably 80-180°C, more preferably 100-150°C, and more preferably 120-130°C; the time is preferably 12-48h, and more preferably 24-36h. In the present invention, the hydrothermal reaction is preferably carried out in a hydrothermal reactor. After the hydrothermal reaction, the present invention also preferably includes filtering, washing and drying the obtained system in sequence. In the present invention, the morphology of the formed alumina ceramic powder particles is modified by a hydrothermal method to obtain a regular surface morphology, thereby obtaining an alumina ceramic powder with high sintering activity.

[0044] The present invention also provides a high sintering active alumina ceramic powder prepared by the preparation method described in the above technical solution, wherein the bulk density of the high sintering active alumina ceramic powder is 1.05-1.08 g / cm 3 .

[0045] The present invention also provides a method for preparing alumina ceramics, comprising the following steps:

[0046] The high sintering active alumina ceramic powder described in the above technical solution is pressed into shape and then sintered to obtain the alumina ceramic.

[0047] In the present invention, the pressure of the pressing molding is preferably 100 MPa; the density of the molded blank obtained after the pressing molding is preferably 2.38 g / cm 3 .

[0048] In the present invention, the sintering temperature is preferably 1400°C, and the holding time is preferably 1.8h. After the sintering, the present invention also preferably includes naturally cooling the obtained material to room temperature. In the present invention, the density of the alumina ceramic is preferably 3.956g / cm 3 .

[0049] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0050] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] Example 1

[0052] 100g of alumina ceramic powder (specific surface area 10m 2 / g) was dispersed in a 1L acetic acid solution with a concentration of 0.1mol / L for the first modification. The modification time was 150s, and then dried at 75°C for 2h to obtain the first modified ceramic powder (specific surface area of ​​30m 2 / g);

[0053] The obtained first modified ceramic powder was dispersed in water to obtain a uniformly dispersed alumina dispersion, and then oleic acid was added in an amount of 5% by mass of the first modified ceramic powder for secondary modification at a temperature of 65° C. for 1.5 h, and then dried at 100° C. for 2 h to obtain a second modified ceramic powder;

[0054] The second modified ceramic powder is dispersed in deionized water and subjected to a hydrothermal reaction in a hydrothermal reactor at a temperature of 120° C. for 24 hours. After the reaction is completed, the system is filtered, washed with water, and dried in sequence to obtain the highly sintered active alumina ceramic powder.

[0055] The purity of the obtained alumina ceramic powder with high sintering activity was tested, and the results are as follows:

[0056] The mass percentage of each component is: aluminum oxide is 99.15%, SiO2 is 0.001%, Fe2O3 is 0.001%, and Na2O≤0.01%;

[0057] The ignition loss of alumina ceramic powder with high sintering activity is 0.92%, wherein the test conditions of the ignition loss are: 1100±20℃, 2h.

[0058] Example 2

[0059] The high sintering active alumina ceramic powder obtained in Example 1 was dry-pressed under a pressure of 100 MPa, placed in a high-temperature furnace and sintered at a low temperature of 1400° C. for 1.8 h, and then naturally cooled to room temperature to obtain alumina ceramics.

[0060] After testing, the bulk density of high sintered active alumina ceramic powder is 1.08g / cm 3 The density of the green blank obtained under the molding pressure of 100 MPa is 2.38 g / cm 3 The density of the sintered alumina ceramic is 3.956 g / cm 3 , the shrinkage rate is 15%.

[0061] Comparative Example 1

[0062] The modified alumina ceramic powder was prepared in the manner of Example 1, except that the first modification treatment was not performed;

[0063] Alumina ceramics were prepared according to the conditions in Example 2. After testing, the bulk density of the modified alumina ceramic powder obtained was 0.88 g / cm 3 The density of the green blank obtained under the molding pressure of 100 MPa is 2.13 g / cm 3 The density of the sintered alumina ceramic is 3.843 g / cm 3 , the shrinkage rate is 16.2%.

[0064] The bending strength of the alumina ceramics of the embodiment and the comparative example was tested according to GB / T 6569-2006 "Standard for Testing Methods of Bending Strength of Fine Ceramics", and the test results are shown in Table 1;

[0065] Table 1 Properties of alumina ceramics obtained in Examples and Comparative Examples

[0066] Bending strength(Mpa) Example 2 786 Comparative Example 1 552

[0067] It can be seen from Table 1 that the flexural strength of the alumina ceramics prepared by using the modified alumina ceramic powder is significantly improved.

[0068] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing high sintered active alumina ceramic powder, characterized in that: The following steps are involved: Mixing alumina ceramic powder and weak acid to perform a first modification to obtain a first modified ceramic powder; The first modified ceramic powder, a surfactant and water are mixed to perform a second modification to obtain a second modified ceramic powder; The second modified ceramic powder is mixed with water to carry out a hydrothermal reaction to obtain the high sintering active alumina ceramic powder.

2. The preparation method according to claim 1, characterized in that: The weak acid includes acetic acid; the concentration of the weak acid is 0.05-0.2 mol / L; The dosage ratio of the alumina ceramic powder to the weak acid is 25-100 g: 0.5-2 L.

3. The preparation method according to claim 1 or 2, characterized in that: The first modification time is 50 to 300 seconds.

4. The preparation method according to claim 1, characterized in that: The surfactant is oleic acid; The mass of the surfactant is 2-10% of the mass of the first modified ceramic powder.

5. The preparation method according to claim 1 or 4, characterized in that: The temperature of the second modification is 45-85° C., and the time is 0.5-2 h.

6. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 80-180° C. and the time is 12-48 hours.

7. The high sintering active alumina ceramic powder prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The bulk density of the high sintered active alumina ceramic powder is 1.05-1.08 g / cm 3 .

8. A method for preparing alumina ceramics, characterized in that: The following steps are involved: The high sintering active alumina ceramic powder according to claim 7 is pressed and molded, and then sintered to obtain the alumina ceramic.

9. The preparation method according to claim 8, characterized in that: The compression molding pressure is 100 MPa; The density of the formed green body obtained after pressing is 2.38g / cm 3 .

10. The preparation method according to claim 8, characterized in that: The sintering temperature is 1400°C and the sintering time is 1.8h; The density of the alumina ceramic is 3.956 g / cm 3 .