GB/T 4702.2-1984 Chemical analysis of chromium metal - Determination of silicon content by gravimetric method with perchloric acid dehydration GB/T4702.2-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of chromium metalThe perchioric acid dehydration-gravimetricmethod for thedetermination
of silieon content
This standard is applicable to the determination of silicon content in chromium metal. Determination range: less than 0.50%. UDC 669.26: 543.21
GB 4702.2—84
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is decomposed with hydrochloric acid and treated with perchloric acid fuming to generate insoluble silicic acid. After filtering and burning, weigh. Treat with hydronitric acid to volatilize silicon dioxide, burn and weigh, and calculate the silicon content from the difference between the two weighings. 2 Reagents
2.1 Hydrochloric acid (1 + 5).
2.2 Hydrochloric acid (1 +10).
2.3 Perchloric acid (specific gravity 1.67).
2.4 Hydrofluoric acid (specific gravity 1.1%).
2.5 Sulfuric acid (1 + 3).
2.6 Hydrogen peroxide (specific gravity 1.10).
3 Sample
The sample should pass through a 1.68 mm sieve. bzxz.net
4 Analysis steps
4.1 Sample quantity
Weigh 3.000 g of sample.
4.2 Empty test
Carry out an empty test together with the sample.
4.8 Determination
4.3.1 Place the sample (4.1) in a 300ml beaker, cover with 1: Table III, add 60ml hydrochloric acid (2.1) and heat to decompose. Add 40ml perchloric acid (2.3) and heat until fumes are emitted, and continue heating for 15 to 20 minutes while the vapor of perchloric acid flows along the inner wall of the beaker. Allow to cool, add about 150ml warm water to dissolve soluble salts, slowly drop 10~2(ml hydrogen peroxide (2.6) to reduce chromium, boil for about 1min, filter immediately with slow quantitative filter paper, wipe the residue adhering to the beaker wall with a wiping stick and transfer it to the filter paper, wash it with warm hydrochloric acid (2.2) for 4~5 times, and then wash it with warm water until it is acid-free. 4.3.2 Transfer the residue together with the filter paper into a crucible, dry it for ten minutes and then heat it slowly. After the filter paper is carbonized, carefully carbonize it, then blanch it at about 1100℃ and weigh its quality. National Bureau of Standards issued on October 4, 1984
Implementation on 1985-D9-01
GB 4702. 2—84
4.3.3T of uniformly concentrated water is wetted with a few drops of sulfuric acid (2.5), and 5m hydrofluoric acid (2.4) is added. The mixture is slowly heated until sulfuric acid smoke is completely eliminated. After burning in a high humidity furnace at 1100℃, it is placed in a desiccator and cooled to room temperature, and weighed. The mixture is burned repeatedly until constant weight is reached. 5 Calculation of analytical results
Calculate the silicon white content according to the following formula:
si%):
【(m: -m2) -(mg= m)]×0.4674mo
The mass of impure silicon dioxide and the residue, 1
The mass of the residue and the residue after hydrofluoric acid treatment, g The mass of the impure silicon dioxide and the residue measured in the empty test, g! -The mass of the residue and the residue measured in the empty test after hydrofluoric acid treatment, g Sample,
The conversion factor of silicon dioxide to silicon.
Analysis results are expressed to two decimal places. 6 Tolerance
The difference between the results of the analysis of the plates between laboratories should not exceed the tolerance listed in the following table.
Additional remarks:
>0.20~0.50
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is drafted by Hunan Ferroalloys.
From the date of implementation of this standard in February, the former Ministry of Metallurgical Industry Standard YB582-65 "Method for Chemical Analysis of Chromium" will be invalidated.
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