GB/T 20210-2026Fireworks - Aluminium powder (English PDF)

5.2 Particle size

5.2.1 Aluminum powder products should be labeled with particle size.

5.2.2 All aluminum powders shall have a nominal particle size of less than 25 µm (500 mesh), and coarse aluminum powders shall have a nominal particle size of 75 µm (200 mesh) to 425 µm (40 mesh). When using the sieving method for testing, the amount of material passing through a 25µm (500 mesh) sieve should be less than or equal to 10%, and the amount of material remaining on the sieve corresponding to the nominal particle size should be... Less than or equal to 5%; when using laser diffraction for detection, the D10 particle size should be less than or equal to 30 µm, and the D90 particle size should be less than or equal to the nominal particle size. Degree ±30µm.

5.3 Chemical composition The chemical composition of aluminum powder used in fireworks and firecrackers should comply with the provisions of Table 2.

6.1 General Provisions

6.1.1 For technical indicators involving identification and sensory aspects, visual inspection methods shall be adopted, and the relevant requirements of the standard shall be verified during inspection.

6.1.2 Test methods with the same or higher precision and accuracy may be used.

6.2 Visual Inspection Visual inspection.

6.3.1 Sieving Method (Arbitration Method)

6.3.1.1 Method Principle A certain amount of sample is placed on a standard sieve, and with the aid of vibration, it passes through a standard sieve with a certain mesh size. The amount of material remaining on (or below) the sieve is then measured. The content of the material on (or below) the sieve of this mesh size can be calculated accordingly.

6.3.1.2 Equipment and Instruments 6.3.1.2.1 Standard sieve. It shall meet the requirements of GB/T 6003.1, with a sieve frame size of phi200mm×50mm, and the sieve mesh aperture range of the sieve assembly. 24µm (550 mesh) or above. 6.3.1.2.2 Vibrating Screen. An eccentric vibrating screen (i.e., during the screening process, it causes the standard sieve to oscillate in a circular motion and vibrate up and down). (Oscillating motion) The frequency is 290 times/min, and the vibration is 145 times. 6.3.1.2.3 Antistatic soft brush. 6.3.1.2.4 Electronic balance. accuracy 0.0001g. 6.3.1.2.5 Stopwatch. Accuracy is 0.01s.

6.3.1.3 Determination Procedure (Method 1 - Mechanical Sieving Method) 6.3.1.3.1 Select a standard sieve group according to the technical conditions of aluminum powder. 6.3.1.3.2 Stir the sample thoroughly and weigh 10.00g of the sample, accurate to 0.0001g. 6.3.1.3.3 Place the sample on the upper sieve, cover it with the pressure cap, and fasten the standard sieve group to the vibrating sieve machine. Vibrate for 10 minutes. 6.3.1.3.4 Remove the standard sieve set and weigh the aluminum powder from the upper sieve and the lower sieve respectively.

6.3.1.4 Determination Procedure (Method 2 - Manual Sieving Method) 6.3.1.4.1 Select a standard sieve group according to the technical conditions of aluminum powder. 6.3.1.4.2 Stir the sample thoroughly and weigh 10.00g of the sample, accurate to 0.0001g. 6.3.1.4.3 Place the sample on the upper sieve and gently brush and manually sieve the sample with a clean soft brush. 6.3.1.4.4 After the samples on the upper sieve are sieved, the samples on the lower sieve are manually sieved according to 6.3.1.4.3. 6.3.1.4.5 Disassemble the standard sieve set and weigh the aluminum powder from the upper sieve and the lower sieve respectively. If the sieving loss exceeds 1%, the sieve set should be reassembled. Sampling and testing.

6.3.1.5 Calculation of Measurement Results 6.3.1.5.1 Calculate the mass fraction of aluminum powder on the upper sieve according to formula (1).

6.3.2 Laser Diffraction Method

6.3.2.1 Method Principle When a laser beam irradiates metal powder particles dispersed in a liquid medium, scattering occurs, and particles of different sizes produce unique scattering effects. Characterizing the scattered light pattern. The instrument receives scattered light signals through detectors distributed at different angles, and then uses optical theory and mathematical models to analyze these scattered light signals. The optical signal is used to deduce the particle size distribution of the powder sample based on volume.

6.3.2.2 Equipment and Instruments 6.3.2.2.1 Laser Particle Size Analyzer. Suitable for particle size determination of micron-sized samples, equipped with solvent-based or micro-sample cell injection system, providing accurate particle size measurement. The deviation should not be less than 0.5% (D50 deviation of national or international standard). 6.3.2.2.2 Ultrasonic disperser. frequency not less than 15kHz.

6.3.2.3 Reagents and Materials Anhydrous ethanol (AR).

6.3.2.4 Measurement Procedure 6.3.2.4.1 Stir the sample thoroughly, take about

0.3 g of the sample into a 50 mL beaker, add 20 mL of anhydrous ethanol, and ultrasonically disperse until the powder is dispersed. No aggregation was observed, indicating that this is test solution A. 6.3.2.4.2 Set the sample parameters and input the sample information on the operating software according to the instrument's instruction manual. 6.3.2.4.3 Add anhydrous ethanol as the circulating medium, adjust the stirring speed and the injection pump speed, and test the instrument background. 6.3.2.4.4 After measuring an effective background, add test solution A to the injection system using a dropper to make the occlusion 5%~30%. 6.3.2.4.5 Click the "Start" button on the operating software to begin the measurement. 6.3.2.4.6 After the measurement is completed, check and record the results (D10 and D90).

6.3.2.5 Expression of Measurement Results Two results were measured for each sample in parallel, with an allowable difference of no more than 0.2 µm. The arithmetic mean of the results was taken and the results were retained to two decimal places.

6.4 Aluminum content

6.4.1 Method Principle The sample was dissolved in hydrochloric acid. Under conditions of pH 2.5-2.8, aluminum and other metal ions complexed with disodium ethylenediaminetetraacetate. When the concentration is 5-6, excess disodium ethylenediaminetetraacetate is titrated with zinc standard solution, then aluminum is displaced with fluoride, releasing a fixed amount of ethylenediaminetetraacetate. The aluminum content was determined by titrating the released disodium ethylenediaminetetraacetate with a zinc standard solution. The test solution contained... 1 mg of copper, 1 mg of iron, and 1 mg of manganese do not interfere with the determination.

6.4.2 Reagents and Materials

6.4.2.1 Hydrochloric acid (1 4).

6.4.2.2 Ammonia (1 4).

6.4.2.3 Disodium ethylenediaminetetraacetate solution (50g/L). Dissolve 50g of sodium ethylenediaminetetraacetate in 1000mL of water.

6.4.2.4 The hydrochloric acid-potassium chloride solution (pH 2.5) is prepared according to the following steps.

16.80 mL of hydrochloric acid (rho = 1190 kg/m^3) to a 1000 mL volumetric flask, dilute to the mark with water, and mix well. This is called... Solution A;

14.90 g of potassium chloride (KCl) into a 500 mL beaker, add an appropriate amount of water to dissolve it, and then transfer it to a 1000 mL volumetric flask. Dilute with water to the mark, mix well, and this is called solution B;

33.5 mL of hydrochloric acid (solution A) and 250 mL of potassium chloride solution (solution B) into a 1000 mL volumetric flask, and dilute with water. Mix to the mark.

6.4.2.5 Acetic acid-sodium acetate solution (pH 5.5). Weigh.200g of sodium acetate (CH3COONa·H2O) and place it in a 500mL beaker. After dissolving in an appropriate amount of water, add

9.00 mL of glacial acetic acid, transfer to a 1000 mL volumetric flask, dilute to the mark with water, and mix well.

6.4.2.6 Sodium fluoride saturated solution.

6.4.2.7 Thymol Blue (C27H30O5S) Ethanol Solution (1g/L). Weigh 0.1g of thymol blue and dissolve it in 100mL of ethanol (1 g/L). Mix well.

6.4.2.8 Xylenol orange (C31H29N2O13SNa3) solution (2g/L). Weigh 0.2g of xylenol orange and dissolve it in 100mL of water.

6.4.2.9 Zinc standard solution. Weigh 2.0000g of pure zinc (99.99% or higher), place it in a 300mL beaker, moisten with a small amount of water, and slowly add... Add approximately 20 mL of concentrated hydrochloric acid and heat until the zinc granules are completely dissolved. After cooling, adjust the pH to 5 with ammonia water, transfer to a 1000 mL volumetric flask, and dilute with water. Dilute to the mark and mix well.

6.4.2.10 Concentrated zinc solution. Weigh approximately 4.0000g of pure zinc (99.99% or higher), place it in a 300mL beaker, moisten with a small amount of water, and slowly add... Add approximately 20 mL of concentrated hydrochloric acid and heat until the zinc granules are completely dissolved. After cooling, adjust the pH to 5 with ammonia and transfer to a 1000 mL volumetric flask. Dilute with water to the mark and mix well.

6.4.3.1 Weigh approximately

0.1 g of the sample into a 250 mL beaker, accurate to 0.0001 g. Add 15 mL of hydrochloric acid (1.4), cover with a glass lid. Heat the glass dish until it is completely dissolved, rinse the glass and the glass dish with a wash bottle, cool and then make up to 100 mL in a volumetric flask and shake well.

6.4.3.2 Transfer 25 mL of the solution to a 300 mL Erlenmeyer flask using a pipette, add 2 drops of thymol blue solution, and neutralize with ammonia (1.4). Once the red color of the solution disappears, add 10 mL of hydrochloric acid-potassium chloride solution and 10 mL of disodium ethylenediaminetetraacetate solution, boil for 2 minutes, and rinse with water. Wash the bottle walls, remove it, and let it cool.

6.4.3.3 Add 10 mL of acetate-sodium acetate solution and 8 drops of xylenol orange solution, and titrate with concentrated zinc solution until the solution turns red (zinc content not considered). (Volume of standard solution).

6.4.3.4 Add 25 mL of saturated sodium fluoride solution, boil for 4 min, remove from heat, cool, add 6 drops of xylenol orange solution, and then use zinc standard solution. The titration ends when the solution turns red (the same color as the previous titration). The volume of zinc standard solution consumed at this point is V.

6.4.3.5 Two samples were measured in parallel, and the arithmetic mean of the results was taken.

6.4.4 Calculation of Analysis Results Calculate the mass fraction of aluminum using formula (3).

6.4.5 Precision The difference between analytical results from different laboratories should not exceed 0.3%.

6.4.6 Quality Assurance When abnormal test results occur, a zinc standard solution can be used to replace the sample for analysis. The analytical method can be judged by analyzing the results of the standard solution. The accuracy.

6.5 Magnesium content of composite aluminum powder

6.5.1 Method Principle The sample was dissolved in hydrochloric acid. Under conditions of pH 10, KB indicator formed a wine-red complex with Mg2+; due to EDTA and... Mg2+ has a much stronger complexing ability than KB. When titrated with EDTA standard solution, EDTA will gradually deactivate the complexing ability of Mg2+ with KB. The Mg2+ in the solution forms a more stable complex, and KB is completely released. The titration endpoint is reached when the solution color changes abruptly from wine red to blue. The mass fraction of magnesium in the sample was calculated using the concentration of EDTA, the volume consumed, and the sample mass.

Note. Before adding KB indicator, add potassium sodium tartrate and triethanolamine solution to shield against metal ions such as aluminum and iron, and add copper reagent to shield against metal ions such as copper and iron.

6.5.2 Reagents and Materials

6.5.2.1 Hydrochloric acid (1 4).

6.5.2.2 EDTA standard titration solution. disodium ethylenediaminetetraacetate

0.02 mol/L.

6.5.2.3 Potassium sodium tartrate. 5% aqueous solution.

6.5.2.4 Triethanolamine. 1 part aqueous solution.

6.5.2.5 Ammonia water. 1 part ammonia solution.

6.5.2.6 Copper reagent.

6.5.2.7 Ammonia-Ammonium Chloride Buffer. Dissolve 54g of ammonium chloride in 350mL of concentrated ammonia solution, then dilute with distilled water to a volume of 1000mL. Inside the bottle.

6.5.2.8 KB Indicator. Grind 1g of Acid Blue K, 2g of Naphthol Green B and 20g of Potassium Chloride into a fine powder and put it into a small wide-mouth bottle.

6.5.3 Analysis Steps Prepare the sample solution according to 6.4.3.1, and transfer 25 mL of the solution to a 300 mL Erlenmeyer flask using a pipette, or directly from the remaining solution in 6.4.3.2. Transfer 25 mL of the sample solution to a 300 mL Erlenmeyer flask. Add 15 mL of 5% potassium sodium tartrate solution and 20 mL of triethanolamine. Solution (1.1), adjusted to pH~10 with

1.1 ammonia solution, added 20 mL of ammonia-ammonium chloride buffer solution,

0.1 g of copper reagent, allowed to stand for 10 min, then added... Add a small amount of KB indicator and titrate with EDTA standard solution (c~0.02mol/L) until the endpoint is reached (blue color).

6.5.4 Calculation of Analysis Results Calculate the mass fraction of magnesium using formula (4).

6.6 Activity

6.6.1 Method Principle The active aluminum in aluminum powder (coarse and fine aluminum powder) samples reacts with sodium hydroxide solution to produce hydrogen gas. The activity is calculated based on the volume of hydrogen gas. Mass fraction of aluminum. For composite aluminum powder, based on the results of active aluminum determination, the active aluminum content is approximately calculated using the ratio of aluminum to magnesium content and a conversion factor. The active magnesium is then added to the measured value of active magnesium to obtain the mass fraction of active aluminum magnesium.

6.6.2 Reagents

6.6.2.1 Sodium hydroxide solution (200 g/L).

6.6.2.2 Hydrochloric acid (1 4).

6.6.2.3 Blocking solution. 250 g/L sodium chloride solution, using 1 g/L methyl orange solution as an indicator, and adjusting the solution indicator with hydrochloric acid (6.6.2.2). Red and saturated with hydrogen.

6.6.3 Instruments

6.6.3.1 A schematic diagram of the gas measuring instrument is shown in Figure 1.

6.6.3.2 Leveling bottle [Pour in an appropriate amount of sealing solution (6.6.2.3)].

6.6.3.3 Mercury barometer (accurate to

0.01 kPa).

6.6.4 Analysis Steps

6.6.4.1 Weigh 0.0700g~0.0800g of the sample, accurate to 0.0001g, and place it in a weighing tube.

6.6.4.2 Transfer the weighing tube into the conical flask that has been pre-filled with 25 mL of sodium hydroxide solution (6.6.2.1), and tighten the rubber stopper.

6.6.4.3 Rotate the gas measuring tube piston to connect the gas measuring tube with the piston's vent. Raise the leveling bottle to expel as much air as possible from the gas measuring tube. Rotate the gas measuring tube piston... Adjust the gas measuring tube stopper to connect the gas measuring tube to the reaction flask, and let it stand for 10 minutes.

6.6.4.4 Adjust the temperature of the cooling water in the water tank to match the temperature of the water in the gas measuring pipe jacket. Check the starting point approximately every 7 minutes. If the reading remains unchanged, record the ambient air pressure (P1), temperature (t), and starting reading.

Note. The measured temperature is 20°C±2°C.

6.6.4.5 Gently shake the conical flask to allow the sample to react with the sodium hydroxide solution. Place the conical flask in a water trough and shake it approximately every 10 minutes. Once the reaction is complete, remove the conical flask and let it stand for 10 minutes. Take the endpoint reading approximately every 7 minutes; record the two readings as unchanged. The gas pressure, temperature, and endpoint readings (from the start of the reaction between the sample and the sodium hydroxide solution, the activity test should last for no less than 1 hour). Parallel measurements. Two samples were selected, and their arithmetic mean was taken.

6.6.5 Calculation of Analysis Results

6.6.5.1 Calculate the mass fraction of active aluminum according to formula (5).

6.6.5.2 For composite aluminum powder, calculate according to formula (6) and formula (7) respectively.

6.6.6 Permissible Difference The difference between analytical results from different laboratories should not exceed 0.8%.

6.6.7 Quality Assurance Before each sample analysis, the gas measuring instrument should be tested for leaks to ensure that there is no gas leakage or entry during the analysis process.

6.7 Iron content

6.7.1 Method Principle The sample was dissolved in hydrochloric acid, and ferric iron was reduced with hydroxylamine hydrochloride. The pH of the test solution was controlled at 3.5-4.5.Ferric ions reacted with o-phenanthroline to produce a colorimetric reaction. The absorbance was measured at a wavelength of 510 nm using a spectrophotometer. The measurement range of this method is 0.001% to 3.5%.

6.7.2 Reagents

6.7.2.1 Hydrochloric acid (5 1).

6.7.2.2 Hydrochloric acid (1 1).

6.7.2.3 Sodium hydroxide solution (200 g/L, stored in a plastic bottle).

6.7.2.4 Hydrogen peroxide (rho=1.11g/mL).

6.7.2.5 Hydroxylamine hydrochloride solution (10 g/L).

6.7.2.6 o-Phenanthroline solution (

2.5 g of o-Phenanthroline (C12H8N2·H2O) or 3 g of o-Phenanthroline hydrochloride. Dissolve (C12H8N2·HCl·H2O) in warm water and cool. Dilute with water to 1000 mL and mix well.

6.7.2.7 Buffer solution. Weigh 272g of sodium acetate (C12H8N2·HCl·3H2O), dissolve it in 500mL of water, filter, and then add 240mL of water. Dilute glacial acetic acid (rho=1.05g/mL) with water to 1000mL and mix well.

6.7.2.8 Mixed solution. Mix hydroxylamine hydrochloride solution (6.7.2.5), o-phenanthroline solution (6.7.2.6), and buffer solution (6.7.2.7) in a ratio of (1.1.3). Mix the volumetric phases and store in brown bottles for no more than 4 weeks.

6.7.2.9 Iron Standard Stock Solution. Preferably prepare using certified standard solutions, or weigh 0.2860 g of iron solution that has been pre-ignited at 600°C. Ferric oxide [omega(Fe2O3)>=99.99%] was placed in a.200mL beaker, and 30mL of hydrochloric acid (6.7.2.2) was added. The mixture was heated until completely dissolved. Cool, transfer to a 1000 mL volumetric flask, dilute...