GB/T 5687.5-1988 Chemical analysis method for ferrochrome - Determination of carbon content by infrared absorption method GB/T5687.5-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of ferrochromium
Determination of carbon content by infrared absorption method
Methods for chemical analysis of ferrochromiumThe infrared absorption method for thedetermination of carbon contentThis standard is applicable to the determination of carbon content in ferrochromium. Determination range: 0.025%～10.500%. UDC 669. 15'26
GB 5687.588
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Summary of the method
The sample is heated and burned in the oxygen flow of a high-frequency induction furnace. The generated carbon dioxide is carried by the oxygen to the measuring chamber of the infrared analyzer. The carbon dioxide absorbs infrared energy of a specific wavelength. Its absorption energy is proportional to its concentration. The carbon content can be measured based on the change in the energy received by the detector. 2 Reagents and Materials
2.1 Acetone: Residue after evaporation, carbon content less than 0.0005%. 2.2 Magnesium perchlorate: Anhydrous, granular.
2.3 Caustic soda asbestos: Granular.
Glass wool.
Tungsten particles: Carbon content less than 0.002%, particle size 0.8~1.4mm. Tin particles: Carbon content less than 0.002%, particle size 0.4～0.8mm. If necessary, use acetone (2.1) to clean the surface and dry it at room temperature. 2.6
Oxygen: Purity greater than 99.95%. Other grades of oxygen can also be used if a low and consistent blank can be obtained. 2.73
2.8 Power source: Nitrogen or compressed air, with an impurity (water and oil) content less than 0.5%. 2.9 Quality: Φ×#, mm: 23×23 or 25×25, and burn in a high temperature furnace above 1200℃ for 4h or burn in oxygen until the blank value is the lowest.
2.10 Clamps.
3 Instruments and equipment
3.1 Infrared absorption carbon determination instrument (sensitivity is 1.0ppm) The device is shown in the figure.
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 5687.5-88
1-Oxygen cylinder: 2-Two-stage pressure regulator: 3-Gas washing bottle; 4.9-Desiccant tube: 5-Pressure regulator: 6-High frequency induction furnace, 7-Combustion tube; 8-Dust collector; 10-Flow controller; 11-Converter for converting carbon monoxide to carbon dioxide: 12-Desulfurizer; 13-Carbon dioxide infrared detector 3.1.1 Gas washing bottle (3): Contains caustic soda asbestos (2.3). 3.1.2 Desiccant tube (4, 9): Contains magnesium perchlorate (2.2). 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 rated flow. 3.2.2 The power gas source system includes power gas (nitrogen or compressed air), a two-stage pressure regulator and a timing control part to ensure the provision of appropriate pressure and rated flow.
3.3 The high-frequency induction furnace
should meet the requirements of the melting temperature of the sample.
3.4 ​​Control system
3.4.1 The microprocessor system includes a central processing unit, a memory, a keyboard input device, an information center display screen, an analysis result display screen and an analysis result printer.
3.4.2 The control functions include automatic loading and unloading and furnace lifting, automatic cleaning, analysis condition selection and setting, analysis process monitoring and alarm interruption, analysis data collection, calculation, correction and processing, etc. 3.5 Measurement system
It is mainly composed of an electronic balance (sensitivity not greater than 1.0mg) controlled by a microprocessor, an infrared analyzer and electronic measuring elements. 4 Samples
4.1 All micro-carbon ferrochrome, low-carbon ferrochrome and medium-carbon ferrochrome samples should pass through a 1.68mm sieve. 4.2 All high carbon ferrochrome samples should pass through a 0.125 mm sieve. 336
5 Analysis steps
5.1 Sample quantity
Weigh the sample according to Table 1.
5.2 Blank testwwW.bzxz.Net
Quantity, %
GB5687.5—88
Sample quantity, nominal
In (2.9) pre-filled with 0.300±0.005 g tin particles (2.6), cover 1.500±0.005 g tungsten particles (2.5), and measure according to 5.5 on the same range or channel. Repeat enough times until a low and relatively consistent reading is obtained. Record the minimum three readings, calculate the average value, and refer to the instrument manual to enter the average value into the analyzer. The instrument will then perform electronic compensation for the blank value when measuring the sample.
5.3 Analysis preparation
5.3.1 Check the instrument according to the instrument manual to make it in a normal and stable state. 5.3.2 Select and set the best analysis conditions.
5.3.3 Use standard samples and flux to make two test tests according to 5.5.1 and 5.5.2 to determine whether the instrument is normal. 5.3.4 Weigh several portions of 0.5008 standard samples with a carbon content of about 0.050%, and measure them according to 5.5. The result fluctuation should be within the range of ±0.003%, otherwise the sensitivity of the instrument should be adjusted according to the instrument requirements. 5.4 Calibration test
5.4.1 According to the carbon content of the sample to be tested, select the corresponding range or channel, and select three standard samples of the same type (the carbon content of the sample to be tested should fall within the range of the carbon content of the selected three standard samples). Perform calibration in sequence, and the fluctuation of the measured results should be within the allowable difference 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 For different ranges or channels, the blank values ​​should be measured and calibrated respectively. 5.4.3 When the analysis conditions change, such as when the instrument has not been preheated for 1 hour, the blank value of the oxygen source or the flux has changed, the blank value should be re-measured and calibrated.
5.5 Determination
5.5, 1 According to the carbon content range of the sample to be tested, select the best analysis conditions of the instrument respectively: such as the combustion integration time of the instrument, the setting of the comparison level (or set number), etc.
5.5.2 Place the weighed sample (5.1) in a crucible (2.9) pre-filled with 0.300g tin particles (2.6), cover it with 1.5008 tungsten particles (2.5), take it with tongs and place it on the furnace seat, operate according to the instrument manual, start analysis and read the results. 6 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. 17
Additional Notes:
>0. 025-~0. 070
>0. 070~0. 120
>0. 120 ~ 0. 400
>0. 400~1.200
>1.20～2.50
>2. 50~5. 00
>5. 00 ~~8. 00
>8. 00~10.50
GB5687.5—88
This standard was drafted by Xinyu Iron and Steel Plant and Jilin Ferroalloy Plant. The main drafters of this standard are Wu Taibai, Hao Fangcheng and Chang Yanfu. Allowance
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB584-65 "Chemical Analysis Method of Ferrochromium" shall be invalid. %
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