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GB/T 21931.2-2008 (GB/T21931.2-2008)

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GB/T 21931.2-2008
Nickel, ferronickel and nickel alloys - Determination of sulfur content - Infrared absorption method after induction furnace combustion
ICS 77.100
National Standards of People's Republic of China
GB/T 21931.2-2008/ISO 7526.1985
Determination of sulfur content in nickel, nickel-iron and nickel alloys
High frequency combustion infrared absorption method
(ISO 7526.1985, IDT)
2008-05-30 released
Implementation of.2008-12-01
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Issued by China National Standardization Administration
This part of GB/T 21931.2-2008 is equivalent to ISO 7526.1985 "Determination of high sulfur content in nickel, ferronickel and nickel alloys
Frequency combustion infrared absorption method.
The technical content of this part is exactly the same as that of ISO 7526.1985.For ease of use, this part has been modified as follows.
a) The term "this International Standard" is changed to "this Part";
b) Use a decimal point "." to replace the comma "," as a decimal point;
c) Delete the foreword of the international standard;
d) National standards are adopted for normative references;
e) The contents of the crucible cover in the international standard have been deleted.
Appendix A and Appendix B of this section are informative appendices.
This part was proposed by the China Iron and Steel Association.
This part is under the jurisdiction of the Metallurgical Industry Information Standards Institute.
Drafting organization of this section. Shanxi Taigang Stainless Steel Co., Ltd.
The main drafters of this section. Dai Xueqian, Liu Wei, Zhang Ruilin.
GB/T 21931.2-2008/ISO 7526.1985
Determination of sulfur content in nickel, nickel-iron and nickel alloys
High frequency combustion infrared absorption method
Warning. The personnel using this section should have practical experience in formal laboratory work. This section does not point out all possible security issues.
The user is responsible for taking appropriate safety and health measures and ensuring compliance with the conditions stipulated by relevant national laws and regulations.
1 scope
This part of GB/T 21931 specifies the high-frequency induction furnace combustion infrared absorption method for the determination of sulfur content in nickel, nickel-iron and nickel alloys.
This part is applicable to the sulfur content of nickel and ferronickel from 0.001% to 0.3% (mass fraction) and the sulfur content of nickel alloy from 0.001% to 0.1%
(Mass score) determination. See Appendix A for examples of ingredient composition.
2 Normative references
The clauses in the following documents have become clauses of this part by reference to this part of GB/T 21931.All dated quotations
All subsequent amendments (excluding errata content) or revisions do not apply to this section, however, it is encouraged to reach
The parties to the agreement study whether the latest versions of these documents can be used. For undated references, the latest version is applicable to this
GB/T 63779.1 Measurement methods and accuracy of results (accuracy and precision) Part 1.General principles and definitions
(GB/T 6379.1-2004, ISO 5725-1..1994, IDT)
GB/T 63779.2 Accuracy of measurement methods and results (accuracy and precision) Part 2.Determine the repeatability of standard measurement methods
The basic method of performance and reproducibility (GB/T 6379.2-2004, ISO 5725-2.1994, IDT)
3 Principle
The sample, flux and accelerator are placed in a high-frequency induction furnace and burned at high temperature under oxygen flow. The generated sulfur dioxide is carried by oxygen to
In the infrared absorption cell, the sulfur content in the sample can be measured by using the infrared detector and the integration program to measure the amount of sulfur dioxide generated after combustion.
4 Reagents and materials
4.1 Oxygen, the purity is greater than 99.5% (mass fraction).
4.2 Caustic soda asbestos (or soda lime), particle size 0.7mm ~ 1.2mm (14 mesh ~ 22 mesh).
4.3 Magnesium perchlorate, particle size 0.7mm~1.2mm (14 mesh ~ 22 mesh).
4.4 Glass wool.
4.5 Crucible.
4.5.1 The size of the ceramic crucible must be accurate, so that the sample can fit in the induction coil of the furnace (see 9.1).
4.5.2 In a furnace with air or oxygen, pre-fire the crucible at a temperature of 1100°C for more than 1 h, and then store it in a desiccator or airtight container
in. A resistance furnace in which oxygen passes through the combustion tube can be used.
4.6 Flux. low-sulfur tin, copper plus tin, copper or vanadium pentoxide (see 9.2).
4.7 Accelerator. copper, iron, tungsten or nickel with low sulfur content (see 9.2).
4.8 Nickel. Known content, sulfur content (mass fraction) is less than 0.001%.
4.9 Steel standard samples. sulfur content (mass fraction) 0.1% to 0.2%.
5 Instruments
High-frequency induction burners and infrared absorption sulfur analyzers can be purchased from many manufacturers. The operation of the instrument follows the manufacturer's instructions
GB/T 21931.2-2008/ISO 7526.1985
book. According to the technical specifications of the manufacturer, a pressure regulator is required to control the pressure of oxygen entering the furnace (usually 28kN/m2). Characteristics of commodity instruments
See Appendix B for sex.
6 Sampling and sample preparation
6.1 The collection and preparation of laboratory samples shall be carried out in accordance with the agreed procedures or in accordance with relevant national standards.
6.2 Laboratory samples are generally granular, drill chips or milling chips, and no further processing is required.
6.3 If the laboratory sample is contaminated by grease during grinding or drilling, it should be cleaned with analytical pure acetone and dried in air.
6.4 If the laboratory sample has a large difference in particle size, the sample size should be obtained after reduction.
7 Analysis steps
Warning. The danger of this experiment is mainly the burning (burn) that easily occurs during the pre-firing and melting stages of the crucible. So it should be used from start to finish
Clamp the crucible and place the used crucible in a suitable container. The use of oxygen cylinders should comply with its usual safety measures. Local enrichment of oxygen can cause
Fire, so oxygen must be effectively discharged from the equipment during the combustion process.
7.1 The amount of sample
Weigh 1.0g sample to the nearest 0.0001g.
7.2 Blank test
According to the sample analysis method, add quantitative flux or accelerator. Carry out at least 3 blank tests.
7.3 Preparation of standard samples
The standard sample is made of steel standard sample and pure nickel with low sulfur content (with known sulfur content) in different proportions, so that the standard control range can reach
The upper limit of the sample to be analyzed. Table 1 shows the steel standard sample with a sulfur content (mass fraction) of 0.100% and the sulfur content (mass fraction) as
Example of calibration with 0.001% pure nickel.
Table 1 Calibration example
Steel mass number/g Nickel mass number/g Sulfur content in the component (mass fraction)/%
0.0050 + 0.0005
0.030 + 0.0007
0.0110 + 0.0009
7.4 Preparation for analysis
7.4.1 Before calibrating and measuring samples, check and adjust the instrument to ensure that the instrument is in a normal and stable working state, and determine the best analysis
7.4.2 After completing the blank calibration, the instrument automatically deducts the blank during subsequent sample measurement.
7.5 Calibration
Calibrate with the standard sample prepared in 7.3.Within the measurement range, select a standard sample with appropriate content to measure at least 3 times, and perform the system
Linear adjustment. Then measure a series of standard samples, check the linear relationship after calibration, and if necessary, further calibrate the working curve.
7.6 Analysis of samples
Place the weighed sample (7.1) in the crucible (4.5), and cover the appropriate amount of flux and accelerator (variety and amount of flux and accelerator)
It depends on the characteristics of the equipment and the type of sample. Typical ones include adding 2g copper, or 2g~3g tungsten, or 1g copper plus 1g
Pure iron.) Use the same conditions, procedures, and operations as the standard samples for measurement.
8 Results presentation
8.1 Result calculation
According to the relationship between absorption energy and sulfur concentration, the sulfur content is obtained from the calibration curve. The analysis result of the element to be measured should be in the calibration curve
GB/T 21931.2-2008/ISO 7526.1985
Use a series of standard samples within the content range.
8.2 Precision
The methods specified in this section have been tested by 14 laboratories in 6 countries. For 11 samples at different times
Perform parallel sample analysis.
Repeatability and reproducibility are calculated in accordance with GB/T 6379, and the results are given in Table 2.
Table 2 Analysis and statistics results
Metal or alloy
Average sulfur content (quality
Standards in the laboratory
Deviation (tw)
Inter-laboratory standards
Deviation (sb)
A22 0.020 0.0006 0.0013 0.0018 0.0040
A28 0.023 0.003 0.0017 0.0009 0.0050
C1 0.024 0.005 0.0010 0.0014 0.0032
C2 0.048 0.0007 0.0030 0.0021 0.0089
C3 0.074 0.0009 0.0031 0.0025 0.0091
C4 0.20 0.0033 0.0013 0.0009 0.038
HN 0.0004 0.00016 0.00015 0.0004 0.0005
YG 0.00063 0.0002 0.0005 0.0005 0.00016
YF 0.0013 0.003 0.0013 0.0007 0.0038
Nickel Alloy Nickel Alloy
AK 0.0025 0.002 0.0006 0.0006 0.0019
AO 0.016 0.0006 0.0010 0.0010 0.0033
9 Analysis procedure and instrument description
9.1 Crucible
Ceramic crucibles must be used for the sample and necessary additives, as well as the melting process. The size of the crucible should be accurately matched with the support, so that the crucible
The sample is heated in the induction heating coil.
Common dimensions of combustion crucible.
25mm high
Outer diameter 25mm
Inner diameter 20mm
Wall thickness 2.5mm
Bottom thickness 8mm
The crucible is pre-fired at a high temperature of 1,100°C in an oxygen atmosphere to remove the sulfur contained therein.
9.2 Flux and accelerator
9.2.1 The addition of flux can bond the particles of the sample together, make the electromagnetic induction in the furnace more effective and improve the flow of the melt
Sex. Tin, copper plus tin, copper and vanadium pentoxide have good fluxing effects.
9.2.2 Copper, iron, tungsten and nickel are commonly used accelerators. The accelerant is added for the following reasons.
a) For unsatisfactory samples processed by other methods, such as finely divided or complex materials, it can provide a good coupling induction medium;
b) Play the role of chemical fuel and increase the combustion temperature;
GB/T 21931.2-2008/ISO 7526.1985
c) When a smaller amount of sample must be used, it is used to increase the total content of the crucible without increasing the amount of sample.
The fluxes and catalysts used should have low sulfur content and should be used in the calibration procedure. Various factors (oxygen, refractories, fluxes and promotion
Agent) constitutes the blank value of sulfur, and the sum of all blank values cannot exceed 0.001% (mass fraction).
Note. Some materials are both fluxes and accelerators.
9.3 Characteristics and operation of high frequency induction furnace
9.3.1 See Appendix B for the performance characteristics of commercial high-frequency furnaces.
9.3.2 Allow oxygen to flow through the reagent tube containing alkali asbestos agent (4.2) and magnesium perchlorate (4.3) for purification. During the standby period, still need to maintain
The flow rate is about 0.5L/min.
9.3.3 A glass wool filter is installed between the furnace combustion chamber and the analyzer. Replace if necessary. Furnace room, bracket and filter should be regular
Clean up to remove oxide residues.
9.3.4 The manufacturer may recommend setting up a pre-burning program before oxygen injection. During the burn-in period, the sample is in a red hot state.
Enter, the temperature will increase greatly.
9.3.5 The temperature reached by combustion depends on the type and amount of metal in the furnace and crucible. After the sample is melted, keep the high temperature
The furnace can be completely transferred to the infrared analyzer.
9.3.6 The flow rate of oxygen in the combustion phase varies from instrument to instrument, but it is usually around 2.0L/min.
9.3.7 When the instrument is shut down for several hours or after cleaning the furnace or filter, the instrument should be stabilized as described in 7.1.
10 Test report
The test report should include the following.
a) Identification of samples, laboratory and date of analysis, etc.;
b) The degree of compliance with the provisions of this section;
c) Analysis results and their representation;
d) Abnormal phenomena observed in the measurement;
e) Operations not included in this section that may have an impact on the analysis results, or optional operations.
GB/T 21931.2-2008/ISO 7526.1985
Appendix A
(Informative appendix)
Examples of chemical composition of nickel, nickel-iron and nickel alloys
Table A. 1.A. 2.A. The component examples in 3 cannot be interpreted as technical conditions for chemical components.
Table A. 1 Example of the composition of nickel% (mass fraction)
99.95 0.1 0.015 0.005 0.002 0.0025
99.9 0.5 0.03 0.03 0.03 0.03
99.0 1.5 0.15 0.2 0.4 0.01
Table A. 2 Examples of nickel-iron composition% (mass fraction)
Brand Ni C
LC 15 0.005 0.10 0.20 margin 0.03 0.20
60 0.03
MC 15 0.03 0.5 0.20 Margin 0.10 1.0
60 1.0
HC 15 1.0 2.0 0.20 Margin 0.40 4.0
60 2.5
Note. Co content is 1/40~1/20 of Ni content.
Table A. 3 Examples of nickel alloy composition %a (mass fraction)
Alloy b Al BB C Coc Cr Cu Fe Mn Mo Ni PS Si Ti Other
2.5 2.0-63.4d-0.025 0.5--
0.5 6.0
1.0-72.0d-0.015 0.5--
0.5 5.0
1.0-70.0d-0.015 0.5 2.2
D 0.2
0.006 0.08-7.0
0.3 Margin 0.4 2.8
0.0150.015 0.4 0.6
E 0.15
0.7 Margin 1.5-30.0
-0.015 1.0 0.15
0.5 5.0 1.0-Margin d-0.020 1.0 0.2
0.020 0.13 5.0 18.0
0.2 1.5 1.0-Margin-0.015 1.0 2.0
GB/T 21931.2-2008/ISO 7526.1985
Table A. 3 (continued) %a (mass score)
Alloy b Al BB C Coc Cr Cu Fe Mn Mo Ni PS Si Ti Other
H 4.5
0.2 1.0 1.0 4.5
Margin-0.015 1.0 0.9
I 0.3
0.005 0.04
0.2 0.7 0.6 5.6
Margin-0.007 0.4 1.9
J--0.02 19.0
1.0-2.0 1.0 26.0
Margin d 0.0400.035 0.1--
0.1 2.0 1.0 3.5
Margin 0.0150.015 0.1 2.8
L--0.02 2.5 14.5
1.0 15.0
Margin 0.0400.035 0.08-V0.35
a Except for nickel, where a single value is the lowest limit, the other single values are the highest limit values.
b Before the establishment of the recognized ISO brand, letters were used to indicate alloy types instead of trade names.
When c does not give the limit value, the maximum value of cobalt is 1.5% (mass fraction).
d In some alloys, the amount of cobalt is calculated based on the amount of nickel.
GB/T 21931.2-2008/ISO 7526.1985
Appendix B
(Informative appendix)
Characteristics of commercial high frequency induction furnace and sulfur infrared absorption analyzer
B. 1 Burner
B. 1.1 The combustion furnace is composed of an induction coil and a high-frequency power supply. The combustion chamber is a quartz tube wound by an induction coil. The top and bottom of the tube are installed
There are metal sheets and O-ring seals. There are gas inlet and outlet respectively on the metal sheet.
B. 1.2 The apparent power of the high-frequency power supply is generally 1.5kVA~2.5kVA, but the frequencies produced by different manufacturers can be different. Used
The frequencies used are 2MHz~6MHz, 15MHz and 20MHz. The high-frequency power supply inputs current to the induction coil wound on the quartz tube.
The ring is usually forced to cool with air.
B. 1.3 The crucible containing the sample, flux and accelerator is placed on the support. The support should be accurately controlled. When it is raised, the metal in the crucible can be
Accurately inside the induction coil, effective induction can be generated when power is applied.
B. 1.4 The diameter of the induction coil, the number of turns, the geometric size of the combustion chamber in the furnace and the power of the power supply determine the quality of the coupling induction effect.
These parameters are determined by the instrument manufacturer.
B. 1.5 The temperature reached by combustion depends in part on B. 1.4 factors, but also related to the characteristics of the metal in the crucible, the shape of the sample and various
The quantity of this material is related. Some of these factors may differ to some extent for different operators.
B. 2 Infrared absorption gas analyzer
B. 2.1 In most instruments, gaseous combustion products are transferred to the analyzer system along with the oxygen flow. The gas passes through the infrared cell and the measurement is
The absorption value of carbon to infrared radiation is integrated according to a predetermined time, and the signal is amplified and converted into a digital display of the percentage of sulfur.
B. 2.2 The combustion products in some analyzers are collected in a certain volume of oxygen, the volume of oxygen is controlled by pressure, and then the mixture is analyzed.
The sulfur dioxide content in the compound.
B. 2.3 The zero adjustment of the instrument, blank compensation, slope adjustment of the standard curve and correction of non-linear response are usually realized by electronic instruments. Minute
The analyzer generally has the function of inputting the quality of the standard sample or sample amount and the correction of the reading. The instrument can also be equipped with an automatic weighing balance for weighing.
Measure the crucible and sample, and transfer the mass to the analyzer.
GB/T 21931.2-2008/ISO 7526.1985