GB/T 13221-2026Determination of powder particle size distribution - Sonic sieving and small angle X-ray scattering methods (English PDF)

4.2 Instruments and Equipment

4.2.1 Test sieves The test sieve consists of a sieve surface and a sieve frame. The selection of the sieve surface should conform to the requirements of GB/T 6003.1, and the sieve aperture size should conform to GB/T 6005. The regulations stipulate that the fit between the sieve frame and the sieve surface should be airtight to ensure that no powder is trapped or leaked during sieving. (Diagram of a test sieve device) See Figure 1.

4.2.2 Acoustic Screening Machine Any device that can achieve the purpose of acoustic sieving can be used. The recommended frequency range is

50 Hz to 100 Hz. A schematic diagram is shown in Figure 2.

4.2.3 Balance The graduation value is

0.001 g.

4.3 Sampling and Sample Preparation Sampling methods should be carried out in accordance with GB/T 5314.The powder should be tested according to the received condition, and the powder amount should preferably be 3 g to 7 g, or... The determination shall be made through negotiation between the supplier and the buyer. If requested by the buyer, the powder may be dried and weighed. If the powder is easily oxidized, it should be dried under a vacuum or inert atmosphere. Drying should be carried out under the following conditions. If the powder contains volatile substances, it should not be dried.

4.4 Test Procedure

4.4.1 Setting test parameters. The acoustic vibration frequency should be

50 Hz~100 Hz, and the recommended time for a single acoustic sieving test is 5 min~15 min.

4.4.2 Assemble the cleaned test sieves on the sieve base in order of larger sieve aperture size at the top and smaller sieve aperture size at the bottom, and weigh the empty sieves.

4.4.3 Weigh the powder to an accuracy of

0.01 g.

4.4.4 Pour the weighed powder into the top test sieve, then start the test sieve (4.2.1) to conduct the sieving test.

4.4.5 After sieving, weigh each test sieve. The mass difference between each test sieve before and after sieving is the powder mass of the corresponding particle size. The weighing process should maintain an accuracy of

0.01 g. The loss of powder after sieving should not exceed 5%.

4.4.6 After the sieving test, the test sieve should be carefully cleaned, but the sieve surface should not be damaged.

5.2 Instruments and Equipment

5.2.1 Balance The scale division is

0.1 mg.

5.2.2 Small-Angle X-ray Scattering Analyzer An X-ray small-angle scattering (SAS) instrument includes an X-ray source, an optical system, a small-angle goniometer or a wide-angle goniometer with a collimation system, a sample holder, and... Detector. The linear range of the detector's count rate should meet the requirements for determining small-angle scattering particle size distribution.

5.3 Sampling and Sample Preparation

5.3.1 The prepared nanopowder small-angle scattering specimens should meet the following requirements.

a) The volume fraction of the powder to be tested in the sample is less than 3%;

b) Place the test piece on the sample holder and control the thickness by measuring the absorption attenuation rate of X-rays on the test piece. A recommended absorption attenuation rate is... Between 50% and 70%;

c) The powder particles are dispersed evenly within the effective size range of the test piece;

d) The test piece should be flat and free of cracks. The size should be determined according to the size of the instrument, with a recommended size of 20 mm × 10 mm.

5.3.2 Prepare cellulose acetate solutions with a mass concentration of 50 g/L to 100 g/L using cellulose acetate without small-angle scattering effect and analytical grade acetone. Pure acetone solution.

5.3.3 According to the requirements of 5.3.1, and referring to the specific gravity of the powder and cellulose acetate and their absorption coefficients for X-rays, weigh an appropriate amount of... For the powder to be tested, measure a certain volume of cellulose acetate acetone solution and pour it into a beaker.

5.3.4 Place the beaker containing the above suspension into an ultrasonic disperser and disperse it by ultrasonic oscillation. The ultrasonic dispersion time is... The optimal time for ultrasonication is 5 to 10 minutes to disperse agglomerated particles.

5.3.5 Place the beaker in a fume hood to allow the powdery turbid liquid to dry slowly into sheets.

5.3.6 When using sol samples, an appropriate surfactant may be added, and the volume fraction of the suspension should be less than 3%.

5.4.1 Test Preparation

5.4.1.1 Connect the equipment power supply. After the X-ray small angle scattering instrument (5.2.2) has stabilized, calibrate the "0" position of the small angle scattering goniometer and record the result. The intensity of the lower "0" position.

5.4.1.2 Place the sample in the sample holder. If the sample is a sol, slowly inject it into the liquid sample reservoir using a syringe before placing it in the sample holder.

5.4.2 Strength Measurement

5.4.2.1 Using a small-angle X-ray scattering instrument, the scattering intensity [Ia(epsiloni)] was measured point by point by changing the scattering angle. The scattering intensity in the large-angle region is relatively... If the accuracy is low, the measurement data can be ensured by appropriately extending the counting time or by taking the average of multiple measurements at the same point.

5.4.2.2 Remove the sample, reset the goniometer to the "0" position, and measure the strength at the "0" position again. The deviation from the value measured in

5.4.1.1 should be less than [value missing]. 15%, otherwise the measurement should be repeated.

5.4.2.3 Place the sample in front of the entrance slit and measure the instrument's background strength [Ib(epsiloni)] point by point. The background strength in the large angle region should be measured multiple times. The average value of the quantity.

5.4.2.4 For sol samples, given that the mother liquor also has a scattering effect, the scattering background of the sample shall be determined according to the following provisions.

a) Pour the mother liquor without suspended solids into the sample cell, place it on the sample holder, and perform point-by-point testing under the same angle and test conditions as in 5.4.2.1. The scattering intensity [IL(epsiloni)] of the mother liquor, etc., is measured;

b) Set the goniometer to the "0" position, add the multilayer filter, and record its transmission intensity [IL(0)]; remove the mother liquor sample, and then insert the measured... For the sol sample, record its transmission intensity [IS(0)], and take k = IS(0)/IL(0);

c) The background of the sol sample at each scattering angle is Ib(epsiloni) = kIL(epsiloni).

5.4.3 Data Processing Let I(epsiloni) = Ia(epsiloni) - Ib(epsiloni), which is the small-angle X-ray scattering intensity of the sample at each angle.

Note. A linear X-ray source and a counting tube detector are used to measure small-angle scattering intensity through fixed-point counting. For applications using a point X-ray source and a two-dimensional detector... For instruments with different capabilities, the above algorithm remains effective, but the intensity distribution function of the original beam and the measurement of the scattering intensity are adjusted accordingly based on the actual situation.

5.5.1 Calculation of Results

5.5.1.1 The mean value (w) of the particle size distribution function for each interval is directly obtained from the X-ray small-angle scattering calculation software. When the obtained (w) has a negative value... When the scattering intensity obtained in

5.4.3 is substituted into formula (A.12) in Appendix A to solve for (w).

5.5.1.2 Calculation of particle size distribution frequency, volume fraction, and cumulative value. Based on the selected particle size interval and the calculated distribution function (wj), the particle size distribution frequency, volume fraction, and cumulative value are calculated. Do not calculate the distribution frequency (-q3,j) and volume fraction (DeltaQ3,j) corresponding to each particle size interval using formulas (A.6) to (A.8), and the results obtained from... The cumulative value of (x0~xj) is (Q3,j).

5.5.1.3 Calculation of average particle size and distribution divergence. According to the particle size distribution in GB/T 15445.2, calculate using formula (A.9)~ Formula (A.11) calculates the volume-weighted average particle size (-XV), median diameter (X50, V), and distribution divergence (SV).

5.5.2 Representation of Results The results of particle size analysis can be represented by tabular or graphical methods. See Appendix B for the method of representing particle size distribution results.

6.Test Report The test report should include at least the following.

a) This document number;

c) Test methods;

d) Test results;

e) Equipment name and test conditions;

f) Operations and options not specified in this document (e.g., powder drying methods);

g) Any circumstances that may affect the test results.