GOST R 51927-2002
GOST R 51927−2002 Steel and cast iron. Atomic emission with inductively coupled plasma spectral method of calcium determination
GOST R 51927−2002
Group B39
STATE STANDARD OF THE RUSSIAN FEDERATION
STEEL AND CAST IRON
Atomic emission with inductively coupled plasma spectral method of calcium determination
Steel and cast iron.
Atomic emission nith inductively coupled plasma spectral method of calcium determination
OKS 77.080
AXTU 0709
Date of introduction 2003−03−01
Preface
1 DEVELOPED AND SUBMITTED by the Technical Committee for standardization TC 145 «monitoring Methods of steel products"
2 ADOPTED AND put INTO EFFECT by the Resolution of Gosstandart of Russia from August 14, 2002 N 304-St
3 INTRODUCED FOR THE FIRST TIME
1 Scope
This standard specifies atomic emission with inductively coupled plasma spectral method of determining the mass fraction of calcium in carbon, alloyed, high alloyed steels and cast irons in the range of 0.001% -0.10 percent.
The method is based on measuring the intensity of emission of atoms of calcium with the introduction of the sample solution into an excitation source.
2 Normative references
The present standard features references to the following standards:
GOST 4517−87 Reagents. Methods for the preparation of accessory reagents and solutions used in the analysis
GOST 10157−79 Argon gaseous and liquid. Specifications
GOST 11125−84 nitric Acid of high purity. Specifications
GOST 14261−77 hydrochloric Acid of high purity. Specifications
GOST 18300−87 ethyl rectified technical. Specifications
GOST 28473−90 Iron, steel, ferroalloys, chromium and manganese metal. General requirements for methods of analysis
3 General requirements
General requirements for methods of analysis GOST 28473.
4 measurement Error
The measurement error shown in table 1.
Table 1
Percentage
| Mass fraction of calcium |
The norm of error analysis results |
The standard deviation of the random error analysis results |
| From 0.001 to 0.002 incl. |
0,0008 |
0,00035 full |
| SV. Of 0.002 to 0.005 « |
0.0016 inch |
0,00074 |
| «0,005» 0,01 « |
0,0026 |
0,0012 |
| «0,01» 0,02 « |
0,004 |
0,0022 |
| «0,02» 0,05 « |
0,007 |
0,0030 |
| «0,05» 0,10 « |
0,012 |
0,0052 |
The limiting error of the result of the analysis are calculated at confidence level of 0.95.
The standard deviation of the random component of the measurement is calculated at the confidence level of 0.85.
5 Apparatus, reagents, solutions
Spectrometric system consisting of a spectrometer (multi-channel or sequential scanning), tripod excitation, high-frequency generator, the measuring electronic system and computer.
Argon according to GOST 10157.
Beakers, flasks, funnels made of transparent quartz glass according to GOST 19908.
Volumetric flasks made of fluoroplastic 4MB with a capacity of 100 cm.
Cylinders and beakers made of PTFE.
Note — All used utensils should be thoroughly washed with hot hydrochloric acid (1:2), and then double-distilled water (tap water for intermediate rinsing is not used).
Laboratory scales 2nd and 3rd classes of accuracy.
Water Mediterranea according to GOST 4517 or equivalent purity (stored in a plastic container).
Iron, OS.CH., with a mass fraction of calcium is not more than 0.0005%.
The hydrochloric acid according to GOST 14261, optionally purified, and diluted 1:2 and 1:9.
For cleaning acid in a desiccator, poured hydrochloric acid on a support is placed a glass made of polyethylene or PTFE, filled with double-distilled or deionized water. The volume ratio of water and acid should be 1:6. The desiccator tightly closed with the lid. The thus obtained solution of hydrochloric acid, free from impurities of calcium, with a density of 1.15 can be used after about 4 days. Store the solution in a plastic container.
Diethyl ether (ethyl ether medical) according to the normative document.
The technical rectified ethyl alcohol according to GOST 18300.
Nitric acid, OS.CH., according to GOST 11125.
Hydrofluoric acid, OS.CH., of the highest category.
Acid chloric, H. h
Calcium carbonate, OS.h.
Standard solutions of calcium.
5.1 Preparation of standard solutions of calcium
5.1.1 solution a: 0,250 g of calcium carbonate dried at 100 °C for 1 h and cooled in a desiccator to room temperature, placed in a beaker, carefully add 10 cmof hydrochloric acid (1:2), covered with a glass watch glass and dissolve with a moderate heat. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM
, made up to the mark with water and mix. 1 cm
of the solution contains 100 mg of calcium. Store the solution in a tightly closed plastic container.
5.1.2 Solution B: make 10 cmof solution A in a volumetric flask with a capacity of 100 cm
, add 5 cm
of hydrochloric acid (1:9), made up to the mark with water and mix. 1 cm
of solution contains 10 mcg of calcium. The solution is prepared immediately before use.
5.1.3 Solution: in a volumetric flask with a capacity of 100 cmadd 5 cm
of solution A, add 5 cm
of hydrochloric acid (1:9), made up to the mark with water and mix. 1 cm
of the solution contains 5 mg of calcium. The solution is prepared immediately before use.
6 preparation for conducting the analysis
6.1 preparing the device for measurements carried out in accordance with the instruction manual and device maintenance. Instrumental parameters of the instrument and the expenses related to the three flows of argon is set within the range for maximum sensitivity of the determination of calcium.
6.2 Setting calibration parameters is performed according to the solution of (5.1.3) and hydrochloric acid (1:9). For each solution perform at least five measurements of the intensities of analytical lines of calcium at a wavelength of 393,37 nm (or 396,847 nm). According to the average values of the intensities of the calculated parameters calibration parameters. Mass fraction of calcium in solution is expressed as a percentage, corresponding to the linkage sample (0,10% for hitch weight 0,5000 g). Parameters calibration parameters recorded in the computer memory.
Note — it is allowed to use other methods of determining the parameters of the calibration parameters, if available mathematical software tool.
6.3 Sample the sample weight 0,5000 g, pre-washed in diethyl ether or ethanol and dried, dissolved in one of two ways.
Method 1: a sample placed in a Teflon beaker, add 15 cmof hydrochloric acid, cover with a Teflon cap and dissolved with moderate heating. The solution was then cooled slightly and add 3−5 cm
of nitric acid. After the cessation of violent foaming, add 5 cm
of perchloric acid and 3.5 cm
hydrofluoric acid. Continue a moderate heat to release the dense white fumes of perchloric acid.
Caution: perchloric acid can explode in the presence of ammonia and nitric acid vapor and any organic reagents.
The solution was cooled, washed by the side of the Cup with water and heating was continued until the termination of allocation of vapors of perchloric acid. Salt dissolved in 5 cmof hydrochloric acid, add 20 cm
of water and heated to boiling. The hot solution is filtered into a measuring flask with a capacity of 100 cm
through a filter medium density, pre-washed 5−6 times with hot hydrochloric acid (1:2) and several times with bidistilled water. The filter cake is washed with hot hydrochloric acid (1:9), adding it in small portions until the complete laundering of the filter from salts of iron, and then several times with small volumes of hot water. The filter is discarded. The solution in volumetric flask was adjusted to the mark and mix.
Method 1 should be used in the analysis of cast irons and carbon steels.
Method 2: a portion of the sample placed in a Teflon beaker, add 15 cmof hydrochloric acid, cover with a Teflon cap and dissolved with moderate heating. The solution was then cooled slightly, add 3−5 cm
of nitric acid and again heated to boiling. After complete dissolution of the sample solution was evaporated to wet salts and add 5 cm
of hydrochloric acid and 20 cm
of water. After complete dissolution of the salts transfer the solution into a volumetric flask with a capacity of 100 cm
, adjusted to the mark with water and shuffle
ivaut.
6.4 in Parallel with the dissolution of the sample, performing all operations of the methods and using the same quantities of reagents, carry out the dissolution of the linkage of carbonyl iron (0,5000 g). Use this solution as the control solution expertise to amendment of the results of the analysis on the content of calcium in the reagent.
6.5 Preparation of solutions used to control the stability of the calibration parameters
6.5.1 Three sample of iron weighing 0.5 g were placed in Teflon beakers, add 15 cmof hydrochloric acid and 5 cm
of nitric acid, cover with a Teflon caps and dissolve with a moderate heat. After complete dissolution of the iron solution is evaporated to wet salts, add 5 cm
of hydrochloric acid and 20 cm
of water, bring to a boil, cooled and transferred to volumetric flasks with a capacity of 100 cm
each.
6.5.2 three volumetric flasks containing the iron solution, prepared as described in 6.5.1, enter these in table 2 the volume of a standard solution B, adjusted to the mark with water and mix.
Table 2
| Room solution |
Mass fraction of calcium, % |
Volume of standard solution B, cm |
Mass concentration of calcium, mg/cm |
Mass fraction of calcium in solution in terms of the weight of the sample 0,5000 g, % |
| 1 |
From 0.001 to 0.10 incl. |
0 |
0 |
0 |
| 2 |
«To 0.001» 0,020 « |
10 |
1 |
0,02 |
| 3 |
SV. 0,020 «0,10 « |
50 |
5 |
0,10 |
The thus obtained solutions 1, 2 and 3 are used in the stability control calibration parameters.
Note — it is Necessary to equate the matrix composition of the solutions used to control the stability of the calibration parameters, with the composition of the analyzed samples when the content in the past: chromium and Nickel — more than 10%; manganese, vanadium, titanium, and copper — of more than 5%; of tungsten, aluminum, and cobalt — more than 2%.
To this end, the solutions 1, 2, 3 prepared as described in 6.5.1, except inserting hinge iron hinge other metals in quantities corresponding to their content in the analyzed sample.
The total amount of batches should not exceed (0,50±0,01) g. Then — as stated
Solutions 1 and 2 is used to control the stability of the calibration parameters in the analysis of materials with a mass fraction of calcium to 0.02% and the solutions 1 and 3 are used respectively in the analysis of materials with a mass fraction of calcium from 0.02% to 0.10%.
Solutions used to monitor the stability of calibration characteristics, is prepared for each batch of samples analysed.
Note — For the preparation of a whole series of solutions of analyzed samples, control the experience and solutions 1, 2, 3 use reagents from the same batch.
7 analysis
7.1 stability Control calibration parameters is carried out as in the procedure of the mathematical software of the device, before analysis. For control stability at low point calibration curve using a solution of 1, and the stability control at the highest point of calibration curve the solutions of 2 and 3 in the analysis of steels with mass fraction of calcium, listed in table 1. To do this, perform 3−5 measurements of the intensities of the calcium in plasma spraying the respective solutions.
Note — it is permitted to use other methods of stability control of the calibration characteristics of the provided software of the instrument.
7.2 Measurement of the mass fraction of calcium for each solution of the analyzed samples is performed as follows. In plasma spraying the appropriate solution, make three parallel measurements, average the results of which will be the one to determine mass fraction of calcium in the sample.
7.3 Measurement of the mass fraction of calcium in solution in the reference experiment was carried out as described in 7.2.
7.4 After each measurement the system was washed by spraying in the plasma of a solution of hydrochloric acid (1:9).
8 Processing of results
8.1 Mass fraction of calcium in the sample in % is calculated by the formula
where — mass fraction of calcium in the analyzed sample solution, %;
— mass fraction of calcium in solution in the reference experiment, %.
The final result of the analysis taking the arithmetic mean of the results of two parallel determinations in two independent test portions of the sample.
Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 does not exceed the permissible differences for the relevant concentration range given in table 3.
Table 3 — operational Norms of the control error and its random component
Percentage
| Mass fraction of calcium |
The standard operational control of convergence |
The standard operational control of reproducibility |
The standard operational control of error |
| From 0.001 to 0.002 incl. |
0,0008 |
0,0010 |
0,0005 |
| SV. Of 0.002 «to 0.005 « |
0,0017 |
0,0020 |
0,0010 |
| «0,005» 0,01 « |
0,0027 |
0,0033 |
0,0017 |
| «0,01» 0,02 « |
0,005 |
0,006 |
0,003 |
| «0,02» 0,05 « |
0,007 |
0,009 |
0,004 |
| «0,05» 0,10 « |
0,012 |
0,015 |
0,008 |
Standards of operational control of the convergence of regulations and control of reproducibility are calculated at confidence level of 0.95. Standards of operational control of error calculated at a confidence level
of 0.85.
If you get results with differences more acceptable the analysis should be repeated using a new sample of the analyzed sample. If re-analysis of the discrepancies in the results of parallel measurements again exceed the allowable, the sample is rejected and replaced with new.
8.2 the frequency of the control error of the measurement according to normative documents approved in the prescribed manner.
