Dispersion test method of high-purity superfine aluminum oxide powder

Abstract

The invention belongs to the technical field of dispersion testing, and particularly relates to a dispersion testing method of high-purity superfine aluminum oxide powder, which comprises the following steps: step 1, pre-dispersing: weighing 0.1-0.15 g of powder sample into a 100ml stainless steel beaker, adding deionized water to 35-40g, and manually stirring for 30 seconds, step 2, dispersing for the second time: adding a proper amount of dispersing agent into the beaker, and uniformly stirring for 30 seconds. The method comprises the following steps: 1, preparing a sample, placing the sample in an ultrasonic cleaning machine, carrying out ultrasonic dispersion for 3 min, and carrying out manual stirring within 10 s at the beginning and 30 s before the end, 3, preparing a test environment, and 4, testing the sample. The nano aluminum oxide particles in the solution are uniformly dispersed by adopting a simple and convenient operation mode, a test result can be quickly and stably output, and the particle size is close to the real particle size under a powder scanning electron microscope. Compared with the prior art, the method has the advantages of unstable output result and harsh test conditions. And the phenomenon of secondary agglomeration of the solution caused by sudden temperature rise of the solution due to the use of a high-power ultrasonic dispersion machine, namely a cell breaking machine, is also solved.

Description

Technical Field

[0001] The invention relates to the technical field of dispersion testing, and in particular to a dispersion testing method for high-purity ultrafine alumina powder. Background Art

[0002] Nano high-purity ultrafine alumina has a wide range of applications in various fields due to its excellent properties. It can be used as an additive for ceramic materials to improve the hardness, strength and wear resistance of ceramics, and is widely used in ceramic tiles, ceramic coatings and other fields; it can be used as a filler to improve the mechanical properties and durability of materials such as plastics and rubber, and is widely used in composite materials, sealing materials and other fields; it can be used to prepare high-performance electronic materials, such as high dielectric constant materials, capacitors, piezoelectric materials, etc., and is widely used in electronic components, electronic ceramics and other fields; it can be used as a raw material for abrasives and grinding tools to prepare high-performance grinding tools for processing and polishing of metals, glass, ceramics and other materials; nano high-purity ultrafine alumina has a high specific surface area and active surface sites, and can be used as a carrier or active component of a catalyst, and is widely used in chemical industry, environmental protection and other fields; nano high-purity ultrafine alumina has good biocompatibility and biological activity, and can be used as a raw material for biomedical materials, such as drug carriers, medical ceramics, etc.

[0003] However, for nano-scale high-purity ultrafine alumina powder, there are some difficulties in sample preparation and pre-dispersion when testing the particle size, because it is easy to agglomerate and form agglomerates, which makes it difficult to evenly disperse the particles, resulting in inaccurate test results and affecting subsequent data analysis and application. Nanopowders have high surface activity and are easy to absorb moisture and other impurities, resulting in increased adhesion between particles and difficulty in dispersion. Choosing a suitable dispersant is also a difficulty, because some traditional dispersants may not be able to effectively disperse ultrafine particles, or may affect the accuracy of the test. Certain technical and equipment support is also required, usually requiring the use of ultrasonic dispersers or other efficient dispersion equipment, which increases the complexity and cost of the experiment. In addition, the dispersion stability is poor and it is easy to re-agglomerate, resulting in greater volatility in the test results. Some measures need to be taken to improve stability. Summary of the invention

[0004] Based on the problems raised in the background technology, the present invention proposes a dispersion test method for high-purity ultrafine alumina powder.

[0005] The present invention provides a dispersion test method for high-purity ultrafine alumina powder, comprising the following steps:

[0006] Step 1: Pre-dispersion: weigh 0.1-0.15g of powder sample or 0.5-1g of liquid sample into a 100ml stainless steel beaker, add deionized water to 35-40g, and stir manually for 30s;

[0007] Step 2: Secondary dispersion. Add an appropriate dispersant into the beaker, place it in an ultrasonic cleaner for ultrasonic dispersion for 3 minutes, and manually stir within the first 10 seconds and the last 30 seconds.

[0008] Step 3: Preparation of the test environment. Clean the injection circulation system equipped with the laser particle size analyzer three times, each time using about 1000 ml of deionized water, then add about 1000 ml of deionized water for circulation. After the air bubble discharge system is stable, click background subtraction.

[0009] Step 4: Sample measurement. Add the ultrasonically treated sample to the injection beaker in small amounts and multiple times using a spatula. Manually stir the sample solution while adding the sample. Stop adding the sample when the light shielding ratio shown on the instrument reaches the specified requirement. Finally, the concentration in the detection system (1000 ml) is 20 ppm, and click measurement.

[0010] Preferably, in Step 2, the dispersant can be one or more dispersants, including surfactants, polymer dispersants, electrolytes, and interfacial active agents. They achieve the dispersion effect by reducing the surface tension of the liquid and increasing the surface charge of the particles; polymer dispersants form a stable polymer adsorption layer on the particle surface to prevent particle aggregation; electrolytes: promote dispersion by changing the ion concentration in the solution and adjusting the charge distribution on the particle surface; interfacial active agents: improve the dispersibility of the powder in the liquid by reducing the surface energy of the solid-liquid interface.

[0011] Preferably, the surfactants include anionic, cationic, non-ionic, and zwitterionic surfactants, and the polymer dispersants include polyacrylates, polyvinyl alcohols, etc.

[0012] Preferably, the ultrasonic cleaner in Step 2 is 80 W, 40 KHz.

[0013] Preferably, the parameters for cleaning the injection pipeline in Step 3 are set at 2000 rpm, turn on the internal ultrasound, each cleaning time is 10S, empty the pipeline after cleaning, and confirm that the light intensity and the light energy diagram are as smooth as possible before background subtraction.

[0014] Preferably, the appropriate range of the light shielding ratio of the instrument in Step 4 is 9% - 13%.

[0015] The beneficial effects of the present invention are:

[0016] The present invention uses a simple and convenient operation method to achieve uniform dispersion of nano-alumina particles in the solution, and can quickly and stably output test results that are close to the actual particle size of the powder under a scanning electron microscope. This is a major advantage over the prior art, which has unstable output results and harsh test conditions. It also solves the problem of secondary agglomeration of the solution caused by a sudden increase in solution temperature when using a high-power ultrasonic disperser such as a cell disruptor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the water level in an ultrasonic cleaning machine for a dispersion test method of high-purity ultrafine alumina powder proposed by the present invention;

[0018] Figure 2 The actual particle size of the alumina particles of about 400 nm under an electron microscope is a dispersion test method for high-purity ultrafine alumina powder proposed by the present invention;

[0019] Figure 3 The present invention proposes a dispersion test method for high-purity ultrafine alumina powder, which is the actual particle size of alumina particles of about 900 nm under an electron microscope. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0021] Reference Figure 1-3 , a dispersion test method for high-purity ultrafine alumina powder, comprising the following steps:

[0022] Step 1: Pre-dispersion: weigh 0.1-0.15g of powder sample (0.5-1g of liquid sample) into a 100ml stainless steel beaker, add deionized water to 35-40g, and stir manually for 30s;

[0023] Step 2: Secondary dispersion: add appropriate dispersant into the beaker and place it in an ultrasonic cleaning machine for ultrasonic dispersion for 3 minutes. Manual stirring is required within the first 10 seconds and the last 30 seconds before the end.

[0024] Step 3: Prepare the test environment. Clean the sample circulation system of the laser particle size analyzer three times, using about 1000ml of deionized water each time, and then add about 1000ml of deionized water for circulation. After the bubbling system is stable, click background subtraction.

[0025] Step 4: Sample measurement. Use a horn spoon to add the ultrasonic sample into the injection beaker in small amounts and multiple times. Stir the sample solution manually while adding the sample. Stop adding the sample when the instrument displays that the shading ratio reaches the specified requirement. The final concentration in the detection system (1000ml) is 20ppm. Click to measure.

[0026] The dispersant in step 2 can be one or more dispersants, including surfactants, polymer dispersants, electrolytes and surfactants, which achieve dispersion effects by reducing the surface tension of the liquid and increasing the surface charge of the particles; polymer dispersants prevent the aggregation of particles by forming a stable polymer adsorption layer on the surface of the particles; electrolytes: regulate the charge distribution on the surface of the particles by changing the ion concentration in the solution, thereby promoting dispersion; surfactants: improve the dispersibility of powders in liquids by reducing the surface energy of the solid-liquid interface.

[0027] The surfactant includes anionic, cationic, nonionic and zwitterionic surfactants, and the polymer dispersant includes polyacrylate, polyvinyl alcohol and the like.

[0028] The ultrasonic cleaning machine in step 2 is 80W, 40KHz.

[0029] In the step 3, the parameters of the cleaning cycle injection pipeline are set to 2000 rpm, internal ultrasound is turned on, each cleaning time is 10 seconds, the pipeline is emptied after cleaning, and the light intensity and light energy map are confirmed to be as smooth as possible before background subtraction.

[0030] Implementation case 1:

[0031]

[0032]

[0033] Implementation case 2:

[0034]

[0035] The above two cases illustrate that the nanometer high-purity ultrafine alumina particle dispersion method provided by the present invention is more stable than the common method and is close to restoring the real particle size.

[0036] By dispersing nano-alumina particles in an aqueous medium, adding a certain amount of dispersant, and using a specific ultrasonic process to make the particles dispersed evenly in the solution without agglomeration, the true particle size can be restored during the test.

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A dispersion test method for high-purity ultrafine alumina powder, characterized in that: The following steps are involved: Step 1: Pre-dispersion: weigh 0.1-0.15g of powder sample or 0.5-1g of liquid sample into a 100ml stainless steel beaker, add deionized water to 35-40g, and stir manually for 30s; Step 2: Secondary dispersion: add appropriate dispersant into the beaker and place it in an ultrasonic cleaning machine for ultrasonic dispersion for 3 minutes. Manual stirring is required within the first 10 seconds and the last 30 seconds before the end. Step 3: Prepare the test environment. Clean the sample circulation system of the laser particle size analyzer three times, using about 1000ml of deionized water each time, and then add about 1000ml of deionized water for circulation. After the bubbling system is stable, click background subtraction. Step 4: Sample measurement. Use a horn spoon to add the ultrasonic sample into the injection beaker in small amounts and multiple times. Stir the sample solution manually while adding the sample. Stop adding the sample when the instrument displays that the shading ratio reaches the specified requirement. The final concentration in the detection system (1000ml) is 20ppm. Click to measure.

2. The dispersion test method of high-purity ultrafine alumina powder according to claim 1, characterized in that: The dispersant in step 2 may be one or more dispersants, including surfactants, polymer dispersants, electrolytes and surfactants, which achieve dispersion effects by reducing the surface tension of the liquid and increasing the surface charge of the particles; polymer dispersants prevent the aggregation of particles by forming a stable polymer adsorption layer on the surface of the particles; Electrolyte: By changing the ion concentration in the solution, the charge distribution on the particle surface is adjusted, thereby promoting dispersion; Surfactant: By reducing the surface energy of the solid-liquid interface, the dispersibility of the powder in the liquid is improved.

3. The dispersion test method of high-purity ultrafine alumina powder according to claim 2, characterized in that: The surfactant includes anionic, cationic, nonionic and zwitterionic surfactants, and the polymer dispersant includes polyacrylate, polyvinyl alcohol and the like.

4. The dispersion test method of high-purity ultrafine alumina powder according to claim 1, characterized in that: The ultrasonic cleaning machine in step 2 is 80W, 40KHz.

5. The dispersion test method of high-purity ultrafine alumina powder according to claim 1, characterized in that: In the step 3, the parameters of the cleaning cycle injection pipeline are set to 2000 rpm, internal ultrasound is turned on, each cleaning time is 10 seconds, the pipeline is emptied after cleaning, and the light intensity and light energy map are confirmed to be as smooth as possible before background subtraction.

6. The dispersion test method of high-purity ultrafine alumina powder according to claim 1, characterized in that: The appropriate range of the instrument shading ratio in step 4 is 9%-13%.

Images