New process for dry grinding of aluminum oxide

Abstract

The invention relates to the technical field of aluminum oxide dry grinding, in particular to a novel aluminum oxide dry grinding process which comprises the following components: industrial aluminum oxide, spherical aluminum oxide, calcined talc, white fire clay, lanthanum oxide and strontium carbonate. According to the novel aluminum oxide dry grinding process, the technological process is greatly simplified, the tedious links of water grinding after dry grinding, precipitation after water grinding, drying, powdering and the like are omitted, the operation time is effectively shortened, and the working efficiency is improved. The production cost is reduced, and the investment of production equipment is reduced. The prepared superfine alumina powder is uniform in particle size and stable in performance and meets the water milling standard, and the performance of the powder is not changed. The problem that aluminum oxide ceramic in the prior art has the characteristics of high temperature resistance, wear resistance, corrosion resistance, good insulativity, good mechanical strength and the like is solved, and the aluminum oxide ceramic is widely applied in industry. However, the traditional preparation process of the aluminum oxide powder has many problems, such as difficult control of powder morphology, serious agglomeration phenomenon, wide particle size distribution, high process cost and harsh preparation conditions.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum oxide dry grinding, in particular to a new process for aluminum oxide dry grinding. Background Art

[0002] Alumina ceramics have the characteristics of high temperature resistance, wear resistance, corrosion resistance, good insulation and mechanical strength, etc. They play an important role in industry and are widely used in bioceramics, surface protection layer materials, chemical catalysts and catalyst carriers, integrated circuit chips, aerospace, infrared absorption materials and humidity-sensitive sensors, etc. Therefore, many studies on alumina ceramic materials have been conducted at home and abroad in recent years.

[0003] The morphology, particle size and dispersion of alumina ceramic powder directly affect the pressing and sintering of ceramics, and further affect the various physical properties of the product. Ball milling is the most common method for preparing ultrafine alumina powder. Usually, the raw materials are impacted, ball-milled and stirred by the rotation or vibration of the ball mill, and the large-particle powder is refined into ultrafine powder. According to literature analysis, scholars such as Lu Baiping studied the influencing factors of preparing ultrafine alumina powder by high-energy ball milling. Prolonging the ball milling time and increasing the ball milling speed can reduce the powder particle size; adding grinding aids during the ball milling process can improve the uniformity of the powder particle size. Scholars Yu Hailong and others found that ultrafine alumina powder with small particle size and good dispersion is more conducive to the pressing and sintering of ceramics; under the same process conditions, spherical alumina powder can maintain the permeability and porosity of the bracket, significantly improve the mechanical properties of the slurry, and be more conducive to the slurry coating on the bracket, thereby changing the microstructure of the material, improving the strength and density of the ceramic, and reducing the sintering temperature, which can significantly improve the performance of the ceramic.

[0004] However, there are still many problems to be solved in the production and preparation process of ultrafine spherical alumina powder, such as the morphology of the powder is difficult to control, it is easy to agglomerate, the particle size distribution range is relatively wide, the process cost is relatively high, and the preparation process conditions are harsh. Therefore, the research on the preparation technology of ultrafine spherical alumina powder should be strengthened to reduce costs, simplify process conditions, improve powder performance, and promote its wider application. This project research is specially applied for.

[0005] However, the alumina ceramics in the prior art are widely used in industry due to their high temperature resistance, wear resistance, corrosion resistance, good insulation and mechanical strength. However, there are many problems in the preparation process of traditional alumina powder, such as difficulty in controlling the powder morphology, serious agglomeration, wide particle size distribution, high process cost and harsh preparation conditions. In view of these problems, a new process of dry grinding of alumina is provided. Summary of the invention

[0006] The purpose of the present invention is to provide a new process for dry grinding of aluminum oxide to solve the problems raised in the above background technology. To achieve the above purpose, the present invention provides the following technical solution: a new process for dry grinding of aluminum oxide, comprising the following components: industrial aluminum oxide, spherical aluminum oxide, calcined talc, white fire clay, lanthanum oxide, strontium carbonate, citric acid and porcelain balls.

[0007] Preferably, the method comprises the following steps:

[0008] S1. Raw material preparation: weigh the raw materials according to the formula ratio to ensure that the raw materials are dry and free of impurities;

[0009] S2. Ball milling: put the raw materials into a ball mill, add an appropriate amount of water, and perform ball milling according to the set ball milling time, ball-to-material ratio, and ball milling speed; during the ball milling process, use citric acid as a grinding aid to improve the fluffy properties of the powder;

[0010] S3, powder collection and treatment: after the ball milling is completed, the powder is collected and dried to obtain ultrafine alumina powder with uniform particle size and stable performance;

[0011] S4. Performance testing: Conduct physical property testing on the prepared ultrafine alumina powder to ensure that the powder performance meets the standards.

[0012] Preferably, in the ball milling formulation system, the added amount of citric acid is 0.5%-5% of the total mass of the raw materials.

[0013] Preferably, the diameter of the porcelain balls includes the particle sizes of 20 mm, 10 mm and 6 mm.

[0014] Preferably, the particle size of the ultrafine alumina powder is controlled within the range of 4-6 μm, and the density of the sintered product is greater than 3.7 g / cm 3 , compressive strength is greater than 274MPa.

[0015] Preferably, the ball milling speed is 15-25 r / s.

[0016] Preferably, the ball milling time is 12-15 hours.

[0017] Preferably, the ball-to-material ratio is 2:1 to 3:1.

[0018] Preferably, the physical property testing includes appearance quality, dimensional deviation, grain size, bulk density, water absorption, and compressive strength.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The process flow is greatly simplified, and the tedious steps of water grinding after dry grinding, precipitation after water grinding, drying, and powdering are eliminated, which effectively shortens the operation time and improves work efficiency. The production cost is reduced and the investment in production equipment is reduced. The prepared ultrafine alumina powder has uniform particle size and stable performance, meets the water grinding standard, and the powder performance does not change at all. It solves the problem that alumina ceramics in the prior art are widely used in industry because of their high temperature resistance, wear resistance, corrosion resistance, good insulation and mechanical strength. However, there are many problems in the preparation process of traditional alumina powder, such as the difficulty in controlling the powder morphology, serious agglomeration, wide particle size distribution, high process cost and harsh preparation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of a new process for dry grinding of aluminum oxide. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without creative work are within the scope of protection of the present invention.

[0023] See also Figure 1 , the present invention provides a technical solution:

[0024] Example 1

[0025] A new process for dry grinding of aluminum oxide comprises the following components: industrial aluminum oxide, spherical aluminum oxide, calcined talc, white fire clay, lanthanum oxide, strontium carbonate, citric acid and porcelain balls. Industrial aluminum oxide and spherical aluminum oxide are used as main raw materials, and auxiliary raw materials such as calcined talc, white fire clay, lanthanum oxide, strontium carbonate, etc. are added in a certain proportion, and citric acid is used as a grinding aid.

[0026] In this embodiment, the following steps are included:

[0027] S1. Raw material preparation: weigh the raw materials according to the formula ratio to ensure that the raw materials are dry and free of impurities;

[0028] S2. Ball milling: put the raw materials into a ball mill, add an appropriate amount of water, and perform ball milling according to the set ball milling time, ball-to-material ratio, and ball milling speed; during the ball milling process, use citric acid as a grinding aid to improve the fluffy properties of the powder;

[0029] S3, powder collection and treatment: after the ball milling is completed, the powder is collected and dried to obtain ultrafine alumina powder with uniform particle size and stable performance;

[0030] S4. Performance testing: Conduct physical property testing on the prepared ultrafine alumina powder to ensure that the powder performance meets the standards.

[0031] In this embodiment, in the ball milling formula system, the amount of citric acid added is 0.5% of the total mass of the raw materials, and four groups of experiments are designed, each of which adds different amounts of grinding aids (such as 5ml, 10ml, 15ml and no addition). By comparing and analyzing the experimental results, the optimal amount of grinding aid added is determined.

[0032] In this embodiment, the diameter of the porcelain ball includes the particle size of the porcelain ball including 20mm, 10mm and 6mm. Three groups of experiments are designed, and each group of experiments uses porcelain balls of different sizes for matching, such as the first group uses 20mm porcelain balls, the second group uses 10mm porcelain balls, and the third group uses 6mm porcelain balls. Through the positive and negative cycle grinding experiment, it is determined that the optimal porcelain ball usage ratio is 20mm:10mm:6mm.

[0033] In this embodiment, the particle size of the ultrafine alumina powder is controlled within the range of 4 μm, and the density of the sintered product is greater than 3.7 g / cm 3 , compressive strength is greater than 274MPa.

[0034] In this embodiment, the ball milling speed is 15r / s, and different ball-to-material ratios (such as 2:1, 3:1), grinding time (such as sampling every 1h) and grinding speed (such as 15r / s to 25r / s) are set to conduct multiple groups of experiments. By comparing and analyzing the experimental results, the optimal ball-to-material ratio, grinding time and grinding speed are determined.

[0035] In this embodiment, the ball milling time is 12 hours.

[0036] In this embodiment, the ball-to-material ratio is 2:1.

[0037] In this embodiment, the physical property detection includes appearance quality, size deviation, grain size, volume density, water absorption, and compressive strength. The appearance quality is mainly detected by direct observation. The specific operation steps are: take an appropriate amount of alumina powder and place it in a well-lit and interference-free environment. Use tools such as a magnifying glass or a microscope to carefully observe the color, gloss, shape, and whether there are impurities, cracks and other defects in the powder. Based on the observation results, the appearance quality of the powder is evaluated, and the size deviation is usually detected by measurement. For alumina powder, the following methods can be used: Laser particle size analyzer method: Using the principle of laser scattering, the particle size distribution of the powder is quickly measured to determine its size deviation. This method has the advantages of fast measurement speed and high accuracy. Standard sieve method: Use a series of standard sieves with different apertures to screen the powder, collect the powder on each sieve layer, and calculate its mass percentage. By comparing the mass percentage of powder on different sieve layers, the particle size distribution and size deviation of the powder can be determined. The detection methods of grain size mainly include microscopic observation and X-ray diffraction: Microscopic observation: Use optical microscope or scanning electron microscope and other equipment to observe the crystal morphology and size of the powder. By measuring the size of multiple grains, the average grain size of the powder can be calculated. This method is simple and easy, but it requires experienced researchers to measure. X-ray diffraction method: Use the diffraction phenomenon of X-rays in crystals to obtain crystal structure information. By calculating the relationship between the diffraction angle and the lattice constant, the size distribution of the grains can be determined. This method has the advantages of accurate measurement and wide application range. The bulk density can be measured by the following methods: Bulk density method: Put the powder into a container, measure its mass and volume, and then calculate the bulk density. This method is suitable for measuring the bulk density of powder. Tap density method: On the basis of the bulk density, the powder is vibrated to achieve the most compact stacking state, and then its mass and volume are measured to calculate the tap density. This method can reflect the bulk density of powder under vibration conditions, and the water absorption rate can be measured by mercury intrusion method or BET method: Mercury intrusion method: Place the powder in a measuring device, apply pressure to make mercury penetrate into the pores of the powder, and then measure the volume change of mercury to calculate the water absorption rate (or porosity) of the powder. This method can measure the pore size distribution and water absorption rate of the powder. BET method: By measuring the adsorption isotherm of nitrogen by the powder, the specific surface area of ​​the powder is calculated using the BET equation, and then its water absorption rate is deduced. This method is suitable for measuring the specific surface area and microporous structure of the powder. The compressive strength can be tested by direct compression method: Put the powder into a special mold, use a press to apply pressure to the mold until the powder is compacted into a sample of a certain shape and size. Measure the compressive strength of the sample, that is, the maximum pressure that the sample can withstand when under pressure. This method can reflect the compressive performance of the powder in a compacted state.

[0038] Example 2

[0039] A new process for dry grinding of aluminum oxide comprises the following components: industrial aluminum oxide, spherical aluminum oxide, calcined talc, white fire clay, lanthanum oxide, strontium carbonate, citric acid and porcelain balls. Industrial aluminum oxide and spherical aluminum oxide are used as main raw materials, and auxiliary raw materials such as calcined talc, white fire clay, lanthanum oxide, strontium carbonate, etc. are added in a certain proportion, and citric acid is used as a grinding aid.

[0040] In this embodiment, the following steps are included:

[0041] S1. Raw material preparation: weigh the raw materials according to the formula ratio to ensure that the raw materials are dry and free of impurities;

[0042] S2. Ball milling: put the raw materials into a ball mill, add an appropriate amount of water, and perform ball milling according to the set ball milling time, ball-to-material ratio, and ball milling speed; during the ball milling process, use citric acid as a grinding aid to improve the fluffy properties of the powder;

[0043] S3, powder collection and treatment: after the ball milling is completed, the powder is collected and dried to obtain ultrafine alumina powder with uniform particle size and stable performance;

[0044] S4. Performance testing: Conduct physical property testing on the prepared ultrafine alumina powder to ensure that the powder performance meets the standards.

[0045] In this embodiment, in the ball milling formula system, the amount of citric acid added is 5% of the total mass of the raw materials, and four groups of experiments are designed, each of which adds different amounts of grinding aids (such as 5ml, 10ml, 15ml and no addition). By comparing and analyzing the experimental results, the optimal amount of grinding aid added is determined.

[0046] In this embodiment, the diameter of the porcelain ball includes the particle size of the porcelain ball including 20mm, 10mm and 6mm. Three groups of experiments are designed, and each group of experiments uses porcelain balls of different sizes for matching, such as the first group uses 20mm porcelain balls, the second group uses 10mm porcelain balls, and the third group uses 6mm porcelain balls. Through the positive and negative cycle grinding experiment, it is determined that the optimal porcelain ball usage ratio is 20mm:10mm:6mm.

[0047] In this embodiment, the particle size of the ultrafine alumina powder is controlled within the range of 6 μm, and the density of the sintered product is greater than 3.7 g / cm 3 , compressive strength is greater than 274MPa.

[0048] In this embodiment, the ball milling speed is 25r / s, and different ball-to-material ratios (such as 2:1, 3:1), grinding time (such as sampling every 1h) and grinding speed (such as 15r / s to 25r / s) are set to conduct multiple groups of experiments. By comparing and analyzing the experimental results, the optimal ball-to-material ratio, grinding time and grinding speed are determined.

[0049] In this embodiment, the ball milling time is 12-15 hours.

[0050] In this embodiment, the ball-to-material ratio is 2:1 to 3:1.

[0051] In this embodiment, the physical property detection includes appearance quality, size deviation, grain size, volume density, water absorption, and compressive strength. The appearance quality is mainly detected by direct observation. The specific operation steps are: take an appropriate amount of alumina powder and place it in a well-lit and interference-free environment. Use tools such as a magnifying glass or a microscope to carefully observe the color, gloss, shape, and whether there are impurities, cracks and other defects in the powder. Based on the observation results, the appearance quality of the powder is evaluated, and the size deviation is usually detected by measurement. For alumina powder, the following methods can be used: Laser particle size analyzer method: Using the principle of laser scattering, the particle size distribution of the powder is quickly measured to determine its size deviation. This method has the advantages of fast measurement speed and high accuracy. Standard sieve method: Use a series of standard sieves with different apertures to screen the powder, collect the powder on each sieve layer, and calculate its mass percentage. By comparing the mass percentage of powder on different sieve layers, the particle size distribution and size deviation of the powder can be determined. The detection methods of grain size mainly include microscopic observation and X-ray diffraction: Microscopic observation: Use optical microscope or scanning electron microscope and other equipment to observe the crystal morphology and size of the powder. By measuring the size of multiple grains, the average grain size of the powder can be calculated. This method is simple and easy, but it requires experienced researchers to measure. X-ray diffraction method: Use the diffraction phenomenon of X-rays in crystals to obtain crystal structure information. By calculating the relationship between the diffraction angle and the lattice constant, the size distribution of the grains can be determined. This method has the advantages of accurate measurement and wide application range. The bulk density can be measured by the following methods: Bulk density method: Put the powder into a container, measure its mass and volume, and then calculate the bulk density. This method is suitable for measuring the bulk density of powder. Tap density method: On the basis of the bulk density, the powder is vibrated to achieve the most compact stacking state, and then its mass and volume are measured to calculate the tap density. This method can reflect the bulk density of powder under vibration conditions, and the water absorption rate can be measured by mercury intrusion method or BET method: Mercury intrusion method: Place the powder in a measuring device, apply pressure to make mercury penetrate into the pores of the powder, and then measure the volume change of mercury to calculate the water absorption rate (or porosity) of the powder. This method can measure the pore size distribution and water absorption rate of the powder. BET method: By measuring the adsorption isotherm of nitrogen by the powder, the specific surface area of ​​the powder is calculated using the BET equation, and then its water absorption rate is deduced. This method is suitable for measuring the specific surface area and microporous structure of the powder. The compressive strength can be tested by direct compression method: Put the powder into a special mold, use a press to apply pressure to the mold until the powder is compacted into a sample of a certain shape and size. Measure the compressive strength of the sample, that is, the maximum pressure that the sample can withstand when under pressure. This method can reflect the compressive performance of the powder in a compacted state.

[0052] The above shows and describes the basic principles, main features and advantages of the present invention. Technical personnel in this industry should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A new process for dry grinding of aluminum oxide, characterized in that: The invention comprises the following components: industrial alumina, spherical alumina, calcined talc, white fire clay, lanthanum oxide, strontium carbonate, citric acid and porcelain balls.

2. A new process for dry grinding of aluminum oxide according to claim 1, characterized in that: The steps include: S1. Raw material preparation: weigh the raw materials according to the formula ratio to ensure that the raw materials are dry and free of impurities; S2. Ball milling: put the raw materials into a ball mill, add an appropriate amount of water, and perform ball milling according to the set ball milling time, ball-to-material ratio, and ball milling speed; during the ball milling process, use citric acid as a grinding aid to improve the fluffy properties of the powder; S3, powder collection and treatment: after the ball milling is completed, the powder is collected and dried to obtain ultrafine alumina powder with uniform particle size and stable performance; S4. Performance testing: Conduct physical property testing on the prepared ultrafine alumina powder to ensure that the powder performance meets the standards.

3. A new process for dry grinding of aluminum oxide according to claim 1, characterized in that: In the ball milling formula system, the added amount of citric acid is 0.5%-5% of the total mass of the raw materials.

4. A novel process for dry grinding of aluminum oxide according to claim 1, characterized in that: The diameters of the porcelain balls include 20 mm, 10 mm and 6 mm.

5. A novel process for dry grinding of aluminum oxide according to claim 1, characterized in that: The particle size of the ultrafine alumina powder is controlled within the range of 4-6um, and the density of the product after sintering is greater than 3.7g / cm 3 , compressive strength is greater than 274MPa.

6. A novel process for dry grinding of aluminum oxide according to claim 1, characterized in that: The ball milling speed is 15-25r / s.

7. A novel process for dry grinding of aluminum oxide according to claim 1, characterized in that: The ball milling time is 12-15 hours.

8. A novel process for dry grinding of aluminum oxide according to claim 1, characterized in that: The ball-to-material ratio is 2:1 to 3:

1.

9. A novel process for dry grinding of aluminum oxide according to claim 1, characterized in that: The physical property tests include appearance quality, dimensional deviation, grain size, bulk density, water absorption, and compressive strength.

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