GB 4374.3-1984 Chemical analysis methods for magnesium powder and aluminum-magnesium alloy powder - Determination of silicon content by silicon-molybdenum blue photometric method
Some standard content:
National Standard of the People's Republic of China
Methods for chemical analysis of magnesium powders and aluminium-magnesium alloy powdersThe molybdenum blue phofometric method of thedetermination of silicon content This standard is applicable to the determination of silicon content in magnesium alloy powders. Determination range: 0.040～0.400% This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". Method summary
UDC 669.721 + 669
.715721492
GB 4374.3--34
The sample is dissolved in sulfuric acid and water. Under the condition of pH 1.0-1.6, silicon and ammonium sulfate form yellow heteropolyacid. After being reduced to blue with 1-hydroxy-2-catechin-4-sulfonic acid, its absorbance is measured at a wavelength of 650nm by a spectrophotometer. The test solution contains 1mg copper (IⅡ), 0.1mg iron (II), 0.5mg iron (III), 1mg manganese (III), and 0.1mg fluorine. The determination is not disturbed by F.
2 Reagents
2.1 Sulfuric acid (1+4).
Ammonium sulfate solution (10%), stored in a plastic bottle. Saturated bromine water.
Potassium fluoride solution (5%), stored in a plastic bottle. Saturated boric acid solution.
Tartaric acid solution (50%).
Reducing agent solution: weigh 0.5g of amino-2-naphthol-4-sulfonic acid and 10g of anhydrous sodium sulfite, and place them in a 200ml beaker. Add 1ml of glacial acetic acid and a small amount of water, and after dissolving, transfer to a 200ml volumetric flask, dilute to the mark with water, and mix. Valid for about 2.8 Aluminum-magnesium matrix solution:
Weigh 1.250g of pure magnesium (more than 99.95%), place in a 400ml beaker, add 50ml of saturated bromine water (2.3), 100ml of acetic acid (2.1), and heat to boil after the pets are completely dissolved, drive off excess bromine, and cool to room temperature. b. Weigh 15.60g aluminum sulfate (Al, (SO): 18112O], place in a 400ml beaker, add appropriate amount of water to dissolve it completely. Filter the above a. and b.4 solutions into the same 1000ml volumetric flask, dilute with water to scale, and mix well. This solution contains 1.25mg of lead and magnesium in 1ml. wwW.bzxz.Net
2.9 Silicon standard stock solution: Weigh 5g sodium silicate, place in a 1000ml beaker 4, add appropriate amount of water to dissolve and dilute to about 800ml, let stand for 3 to 6 days, filter into a 1000ml volumetric flask, dilute with water to scale, and mix well. Store in a plastic bottle. Calibration: Transfer 50.0ml silicon standard stock solution (2 .9), put 40ml sulfuric acid (1+1) and 5ml nitric acid (!+1) in a 250ml beaker, mix. Cover the beaker on a low-temperature electric heating plate, evaporate (not boiling) until sulfuric acid smoke just comes out, keep for 2-3 minutes. Remove, cool, rinse the cup wall with water, slowly add 100ml of nearly boiling hot water under constant stirring, place on the hot plate and heat (no more than 5 minutes) to completely dissolve the salts. Remove, filter with medium-speed quantitative filter paper, and wash the precipitate and aldehyde with hot water until the filtrate is no longer acidic when checked with methyl orange.
National Bureau of Standards 19840430 Issued
19850401 Implementation
GB 4374.3-84
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Put the precipitate and filter paper in a platinum crucible and ash it on an electric furnace. After ashing, burn it in a high-temperature furnace at 950-1000℃ for 30 minutes, take it out, cool it, put it in a desiccator, cool it to room temperature, weigh it, and repeat the burning to a constant weight (m). Add 3-4 drops of sulfuric acid (1+1) and 3ml of hydrofluoric acid to the weighed platinum crucible, evaporate it at low temperature to 1 liter, burn it in a high-temperature furnace at 1950~100% for 15 minutes, take it out, cool it slightly, put it in a desiccator, cool it to room temperature, weigh it, and repeat the burning to a constant weight (m,). Calculate the silicon concentration according to formula (1):
Si (g/mi) =
(ml mz) ×0.4674
Where: m,--mass of precipitate and platinum crucible before hydrofluoric acid treatment, g: mass of residue and platinum crucible after hydrofluoric acid treatment, g; m,
V—-volume of silicon standard storage solution, ml; 0.4674
factor for converting silicon dioxide to silicon.
2.10 Silicon standard solution: Take an appropriate amount of silicon standard storage solution (2.9), place it in a 1000ml volumetric flask, dilute to the mark with water, and add a thick paste. This solution contains 10μg silicon in 1ml.
Spectrophotometer. ||t t||Analysis steps
4.1 Determination quantity
Measure two samples in parallel and take the average value. 4.2 Sample quantity
Weigh the sample according to Table 1.
Silicon content, %
0.040~0.100
>0.100~0.400
4.3 Blank test
Sample quantity,
Weigh the sample (4.2) according to Table 1 and place it in a 150ml beaker. The following is carried out according to 4.4.2, 4.4.3 (without adding ammonium acid solution) and 4.1.4.
4.4 Determination
4.4.1Place the sample (4.2) in a 150ml beaker. 4.4.2 Add 10ml saturated bromine water (2.3) and 10ml sulfuric acid (2.1). After the sample is completely dissolved, rinse the cup wall with a small amount of water, heat on an electric stove and boil to remove excess bromine. 4.4.3 Transfer the solution (4.4.2) to a 100ml plastic beaker, add 3ml potassium fluoride solution (2.4), stir, and place in a boiling water bath to heat for 15min. Remove, add 25ml saturated boric acid solution (2.5), cool to room temperature, filter into a 100ml volumetric flask, wash the beaker with water, dilute to scale, and mix well.
4.4.4 Take 10.0ml of solution (4.4.3) and place it in a 100ml volumetric flask. Add 50ml of water, 2.5ml of sulfuric acid (2.1) and 7ml of ammonium aluminate solution (2.2). Mix well and place for 10min. Add 7ml of tartaric acid solution (2.6) and 3ml of reducing agent solution (2.7). Mix with a spoon and dilute to the mark with water. Mix well and place for 15min. 4.4.5 Transfer part of the solution (4.4.4) to a 2cm colorimetric tube. Take the blank test solution (1.3) as reference. Measure its absorbance at a wavelength of 152
GB 4374.3--84
650nm by spectrophotometry. Find the corresponding silicon content from the working curve. 4.5 Drawing of working curve
4.5.1 According to the sample volume (4.2), transfer an appropriate amount (the amount of aluminum and magnesium should be equivalent to that contained in the sample volume) of aluminum-magnesium matrix solution (2.8), place eleven groups of 100 ml volumetric flasks, add 0.00, 2.004.00, 6.00, 8.00, 10.00 ml of silicon standard solution (2.10) and 0.3 ml of potassium fluoride solution (2.4) respectively, place in a boiling water bath and heat for 15 min, take out and cool, add 1.5 ml of sulfuric acid (2.1) and 7 ml of ammonium molybdate solution (2.2), mix well, let stand for 10 min, add 7 ml of tartaric acid solution (2.6) and 3 ml of reducing agent solution (2.7), mix well, dilute to the scale with water, mix well, and let stand for 15 min.
4.5.2 Transfer part of the solution (4.5.1) into a 2 cm colorimetric III, and use the compensation solution (4.5.14 without adding silicon standard solution) as a reference, and measure its absorbance at a wavelength of 650nm on the spectrophotometer t. Draw a working curve with the silicon content as the abscissa and the absorbance as the ordinate. 5
Calculation of analysis results
Calculate the percentage of silicon content according to formula (2):
Where: m
Allowable difference
Silicon content found on the working curve, g;
-total volume of test solution, ml;
Sample volume, g;
Volume of test solution taken, ml.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.040~0.100
>0.100 ~0.200
≥0,200～0,400
Additional Notes:
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by the Northeast Light Alloy Processing Plant. This standard was drafted by the Northeast Light Alloy Processing Plant and the Northwest Aluminum Processing Plant. The main drafters of this standard are Guan Wenxiang, You Guifa, and Zheng Yajun. × 100 ·
Allowance
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