GOST 21639.11-76

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  ГОСТ 21639.11-76

GOST 21639.11−76 Fluxes for electroslag remelting. Spectral method for determination of lead, zinc, titanium, antimony (Change No. 1)

GOST 21639.11−76*

Group B09

STATE STANDARD OF THE USSR

FLUXES FOR ELECTROSLAG REMELTING

Spectral method for determination of lead, zinc, titanium, antimony

Fluxes for electroslag remelting.
Spectral method for determination of lead, zins, titanium, antimony

AXTU 0709

Date of introduction 1977−07−01

The decision of the State standards Committee of the USSR Council of Ministers dated 19 March 1976 No. 662 the introduction of set with 01.07.77

Proven in 1986 by Decree of the state standard from 10.11.86 N 3399 validity extended to 01.07.92**
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** Expiration removed according to the Protocol N b/n of the Interstate Council for standardization, Metrology and certification (I & C N 2, 1993). — Note the manufacturer’s database.

* REISSUE (may 1987) with amendment No. 1 approved Post. N 3397 10.11.86 (ICS 2−87)


This standard establishes a spectral method for the determination of metals in fluxes when the mass fraction of zinc from 0.020 to 0.15%; titanium from 0,030 to 5.00%; lead from 0,0025 to 0.30%; antimony from of 0.0025 to 0.040%.

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 21639.0−76*.
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* On the territory of the Russian Federation GOST 21639.0−93. — Note the manufacturer’s database.

2. APPARATUS, MATERIALS AND REAGENTS

The quartz spectrograph medium dispersion.

Arc generator of alternating current.

Microphotometer.

Spectromancer.

Installation for grinding carbon electrodes.

Vibrating grinder; pneumostome; Jasper or agate mortar.

Coals spectral (electrodes), with a diameter of 6 mm.

Photographic plates of the spectral type of 1, a sensitivity of 2.8 units according to GOST 2817−50 or other type, providing the necessary sensitivity of the determination.

Developer N 1 and rapid fixer according to GOST 2817−50.

Nitric acid GOST 4461−77.

Hydrochloric acid by the GOST 3118−77.

Tartaric acid according to GOST 7167−77.

Aluminum oxide, OS.h.

Lead (II) nitrate according to GOST 4236−77, standard solution: 2.4 g dried at a temperature of (100±20) °C to constant weight of lead nitrate is placed in a beaker with a capacity of 600 cm, is dissolved in 400 cmof water and poured nitric acid until the disappearance of turbidity. The solution is poured into a measuring flask with a capacity of 500 cm, made up to the mark with water and mix.

Mass concentration of lead in solution is equal to 0.003 g/cm.

Zinc acetate 2-water according to GOST 5823−78, standard solution: 2,5185 g of zinc acetate were placed in a glass with a capacity of 600 cm, is dissolved in 400 cmof water and poured nitric acid until the disappearance of turbidity. The solution is poured into a measuring flask with a capacity of 500 cm, made up to the mark with water and mix.

Mass concentration of zinc in solution is equal to 0.0015 g/cm.

Antimony GOST 1089−82, standard solution: 2 g of antimony is placed in a beaker with a capacity of 300 cm, is dissolved in 30 cmmixture of nitric and hydrochloric acids in a ratio of 1:3 and evaporated to remove the oxides of nitrogen. The contents of the beaker poured into a volumetric flask with a capacity of 500 cmcontaining a mixture of 400 cmof water and 5 g tartaric acid, made up to the mark with water and mix.

Mass concentration of antimony in solution is equal to 0.004 g/cm.

Titanium dioxide, OS.h.

Allowed to use other equipment and materials while ensuring precision of analysis results under this standard.

(Changed edition, Rev. N 1).

3. PREPARATION FOR ASSAY

3.1. The basis for the preparation of the samples for the calibration is a mixture consisting of 70% calcium fluoride and 30% of aluminium oxide, pre-crushed, or the test flux (pollution fundamentals of the flux is determined by the method of additions).

3.2. Samples for the calibration is prepared as follows: sample N 1 sample weight 183,33 g of the flux mixture or is mixed from 16.67 g of titanium dioxide. 200 g of the mixture placed in a porcelain Cup, moisten with 100 cmof water. From burette, enter the calculated number of standard solutions. The mixture was carefully dried on a water bath, avoiding spattering, and then in a drying Cabinet at a temperature of 120−130 °C for 1 h. the Dried mixture was ground in an agate mortar for 1 h.

The amount of titanium dioxide and volume of standard solutions injected in the basis of the sample for calibration, are shown in table.1.

Table 1

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* Consistent with the original. — Note the manufacturer’s database.


Prepared samples for calibration are placed in closed glass jars. The homogeneity of the samples for calibration check according to the application.

Sec. 3. (Changed edition, Rev. N 1).

4. ANALYSIS

4.1. Shell carbon electrode 6 mm in diameter sharpened to a truncated cone at an angle of 30° to the axis of the electrode area is 2 mm.

Permanent carbon electrode 6 mm in diameter sharpened to a plane and make a hole with a diameter of 3 mm and depth 4 mm. In the hole tightly stuffed the analyzed sample.

Dummy electrodes and a constant strengthen in elektrodvigateli tripod with an analytical gap of 2 mm, set the interval on the optical axis of the device.

4.2. The width of the slit of a spectrograph of 0.015−0.018 mm.

The light slit of a spectrograph — being, intermediate diaphragm — round.

4.3. Spectra excite the generator of the arc AC at a current of 4.5 to 5 and the network voltage (220±10) V.

4.4. Samples for calibration photographing three times and the sample two times with a 40 s exposure without burning.

4.5. Photographic plates showing and fixed at a temperature of 20 °C, washed, and dried. The treated photographic plate with the help of spectromancer find the necessary region of the spectrum and measure microphotometer density pucherani lines define the elements and background ().

4.6. Analytical lines (wavelengths) of the identified elements:

Pb 283,37 nm — background to the left;

Zn 328,23 nm — background to the left;

Sb 231,10 nm — background to the left;

Ti 308,80 nm — background at right.

Density measurement of the background produced at a distance of 5 µm from the line of the analyzed element on the drum microvita of microphotometer.

Sec. 4. (Changed edition, Rev. N 1).

5. PROCESSING OF THE RESULTS

5.1. For each item in the spectrograms of the samples to the calibration, measure the density of pochernenija analytical lines and the background, and find the arithmetic mean of the difference of the density of pochernenija .

5.2. According to the average values of the samples for calibration and the logarithms of values of mass fraction of element in them to build a calibration curve by the method of «three standards» in the coordinates (). According to the average values for the analyzed samples in the calibration schedule determine the mass fraction of the elements.

Sec. 5. (Changed edition, Rev. N 1).

6. CONTROL OF MEASUREMENT ACCURACY

6.1. Control the accuracy of the measurements carried out on synthetic mixtures (at least 50), simulating the composition of the analyzed samples across the range of measurements by the method «introduced — found» criterion.

Computed , then

,

,

where  — mass fraction of element in the sample obtained spectrographic method;

 — mass fraction of additives in the sample;

the difference between the results of the spectrographic method and the mass fraction of the additive;

 — the average difference between the results of the spectrographic method and additive mass fraction for all samples;

 — standard deviation;

 — student coefficient;

The results are considered consistent if for 50 measurements at p = 0.95

.

6.2. Allowable absolute differences of the results of two parallel measurements must not exceed the values given in table. 2.

Table 2

Allowed the assessment of differences in spending units of the readings.

APP (mandatory). THE CALCULATION OF THE HOMOGENEITY OF THE SAMPLES FOR CALIBRATION

APP
Mandatory

The value of the mass fraction of the element is set after verification of the homogeneity of the sample for calibration. From sample for calibration selected 20 samples. For each sample spend one dimension of elements. Measurements are performed in series of five tests in each series (series of four) in the same conditions. Measurements are performed by a single researcher in one shift of five samples on one and the same instrument.

The scope of the results of five measurements () and the average scale results () is calculated according to the formulas:

;

,

where  — the maximum value of the measurement results;

 — the minimum value of measurement results;

 — number of series of measurements (at least four);

 — swipe the results of five measurements in the series;

 — the average range of results of five measurement series.

The dispersed material is considered uniform if

and ,

where is the absolute permissible discrepancies in the results of two parallel measurements, regulated by this standard.