GB/T 4702.16-1988 Chemical analysis method for chromium metal - Determination of sulfur content by infrared absorption method GB/T4702.16-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of chromiun metalThe infrared ahsorptlon method for thcdetermination of gulfur contentThis standard is applicable to the determination of sulfur content in metallic chromium. The determination range is 0.005% to 0.045%. UDC 669. 26
GB 4702. 16
This standard complies with GB 1467-78 (General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products). 1. Method Summary
The sample is heated and burned in the oxygen flow of a high-pressure induction furnace. The generated sulfur dioxide is carried by oxygen to the measuring chamber of the infrared analyzer. Sulfur dioxide absorbs infrared energy of a certain wavelength. Its absorption energy is proportional to the concentration of sulfur dioxide. The sulfur content can be measured according to the change in the energy received by the detector.
2 Reagents and Materials
2.1 Magnesium pernitrogenate: anhydrous, granular.www.bzxz.net
2.2 Caustic soda asbestos: granular.
2.3 Glass wool.
2.4 Tungsten granules: sulfur content less than 0.0002%, particle size 0.8~1.4mm.2.5 Tungsten granules: sulfur content less than 0.000 3%, particle size 0.4 ~0.8 mm2.6 Pure iron: purity greater than 99.8%, sulfur less than 0.002%, particle size 0.8 ~ 1.68 mm, 2.7 Oxygen: purity greater than 99.95%, other levels of oxygen can also be used if a low and accurate blank can be obtained. 2.8 Power gas source: nitrogen or compressed air, with impurities (water and oil) less than 0.5%. 2.9 Quality: $×, mm: 28×23 or 25×25, and burned in a high-temperature heating furnace above 1200 for 1h or burned with oxygen until the air value is the lowest.
2.10 Crucible tongs.
3 Instruments and equipment
3.1 Infrared absorption sulfur analyzer (sensitivity is 1.0 ppm) Its installation is shown in the figure.
3.1.1 Washing bottle (3); containing caustic soda asbestos (2.2). 3.1.2 Drying tube (4, 9): containing magnesium perchlorate (2.1). 3.2 Gas source
3.2.1 The carrier gas system includes an oxygen container, a two-stage pressure regulator and a timing control part to ensure the provision of appropriate pressure and constant flow. Approved by the Ministry of Metallurgical Industry of the People's Republic of China on February 2, 1988 and implemented on March 1, 1989
GB 4702,76—88
1 Carrier gas bottle: 2 Two-stage EJ regulator; 3 Washing gas bottle: 1, 9—Drying tube 5 Pressure regulator; 6—Commercial induction furnace: 7—Combustion tube: 8—Distiller: 10 Flow control question, 11—Alkali dioxide infrared detector 3.2.2 The power gas source system includes power gas (nitrogen or compressed air), two-stage pressure regulator and timing control part to ensure the provision of appropriate pressure and rated flow.
3.3 High-frequency induction furnace
Should meet the requirements of sample melting temperature.
3.4 ​​Control system
3.4.1 The microprocessor system includes central processing unit, memory, chain disk input device, information center display screen, analysis result display screen and analysis result printer, etc.
3.4.2 The control functions include automatic loading and unloading of crucibles and furnace lifting, automatic cleaning, analysis condition selection and setting, monitoring and alarm interruption of the analysis process, analysis data collection, calculation, correction and processing, etc. 3.5 Measurement system
Mainly composed of an electronic balance (sensitivity not greater than 1.0 mg) controlled by a microprocessor, an infrared analyzer and electronic measuring elements: 4 Sample
The sample should all pass through a 1.68 mm sieve. 5 Analysis steps
5.1 Sample quantity
Weigh 0.400~0.500 g of sample.
5.2 Blank test
Weigh 0.500 g of pure iron standard sample with sulfur less than 20 ppm and place it in a glass (2.9) pre-filled with 0.500±0.005 g of tungsten particles (2.5), covered with 1.500±0.005 tungsten particles (2.4), and measure according to 5.5 in the same range or channel, repeating a sufficient number of times until a low and relatively consistent reading is obtained (the blank value should be equal to the difference between the measured sulfur content and the known sulfur content of the standard sample). Record at least three readings, calculate the average blank value, and input the blank value into the analyzer according to the instrument manual. The instrument will then perform electrical compensation for the blank value when measuring the sample. 5.3 Analysis Preparation
5.3.1 Debug and check the instrument according to the instrument manual to ensure that the instrument is in a normal and stable state. 5.3.2 Select and set the best analysis parameters.
5.3.3 Use standard samples and flux to perform two test tests according to 5.5 to determine whether the instrument is normal. 5.3.4 Weigh 0.500g of standard sample (or pure iron standard sample) with sulfur content of about 0.0025%. Perform the measurement according to 5.5. The fluctuation of the result should be within the range of ±0.0003%. Otherwise, the sensitivity of the instrument should be adjusted according to the instrument requirements. 5.4 Calibration test
GB 4702.16-88
5.4.1 According to the sulfur content of the sample to be measured, select the corresponding range and channel, and select three standard samples of the same type (the content of the sample to be measured should fall within the sulfur content range of the selected three standard samples). Calibrate accordingly. The fluctuation of the result should be within the allowable error range to confirm the linearity of the system. Otherwise, the linearity of the system should be adjusted according to the instrument manual. 5.4.2 The blank values ​​of different ranges or channels should be measured and stopped. 5.4.3 When the analytical conditions change, such as when the instrument has not been preheated for 1h, and the blank values ​​of the oxygen source, crucible or flux have changed, it is required to re-measure the blank and calibrate.
5.5 Determination
5.5.1 According to the sulfur content range of the sample to be tested, select the best analysis conditions of the instrument, such as the combustion integration time of the instrument, the setting of the comparison level (or set number), etc.
5.5.2 Place the sample (5.1) in a crucible (2.9) pre-filled with 0.50 grams of tin particles (2.5), cover it with 1.50 grams of tungsten particles (2.4), take out the crucible and place it on the crucible seat on the furnace table, operate according to the instrument manual, start analysis and read the results. 6 Allowable Differences
The difference in analysis results between laboratories should not be greater than the allowable differences listed below. %
0. 006 ~~ 0. 015
>0. 015~0. 025
>0. 025 ~0. 046
Additional remarks:
This standard was drafted by Jilin Ferroalloy Factory.
The main drafter of this standard is Chang Yanfu.
The original Ministry of Metallurgy Standard YB582-65 Metal Chromium Chemical Analysis Method" will be invalid from the date of implementation of this standard. The level of this standard is marked as GB 4702.16-881
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