GOST 25278.12-82

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  ГОСТ 25278.12-82

GOST 25278.12−82 Alloys and alloys of rare metals. Spectral method for determination of silicon, iron, aluminum, manganese and chromium in alloys based on vanadium (Change No. 1)

GOST 25278.12−82

Group B59

STATE STANDARD OF THE USSR

ALLOYS AND ALLOYS OF RARE METALS

Spectral method for determination of silicon, iron, aluminum, manganese and chromium in alloys based on vanadium

Alloys and foundry alloys of rare metals. Spectral method for determination of silicon, iron, aluminium, manganese and chromium in alloys on vanadium base

AXTU 1709

Valid from 01.07.83
to 01.07.93*
_______________________________
* Expiration removed
according to the Protocol of the Intergovernmental Council
for standardization, Metrology and certification
(IUS N 2, 1993). — Note the manufacturer’s database.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

PERFORMERS

Yu. A. Karpov, E. G. Nembrini, V. G., Miscreants, G. N. Andrianov, E. S. Danilin, M. A. Desyatkova L. I. Kirsanova, T. M. Malyutina, Y. F. Markov, V. M. Mikhailov, L. A. Nikitina, L. G. Obruchkova, N. Rasnitsyn, N. Suvorova, L. N. Filimonov

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 26.05.82 N 2120

3. The period of examination — 1993

The frequency of inspection — 5 years

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. The validity of the standard extended until 01.01.93 by the Resolution of Gosstandart of the USSR from 29.10.87 N 4096

7. REPRINT (November 1988) with amendment No. 1, approved in October 1987 (ICS 1−88).


This standard specifies the spectral method for determination of silicon, iron, manganese and chromium (from 0.02 to 1%), aluminum (0.1 to 1%) in alloys and master alloys based on vanadium (components: tungsten not more than 10%, molybdenum not more than 10%, titanium not more than 15%, zirconium not more than 5%).

Method is based on the intensity of spectral lines of silicon, iron, aluminum, manganese and chromium from their mass fraction in the sample with the excitation spectrum in the arc DC.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis and security requirements — according to GOST 26473.0−85.

(Changed edition, Rev. N 1).

2. APPARATUS, MATERIALS AND REAGENTS

The diffraction spectrograph DFS-8 with the grating 600 gr/mm (complete installation with a universal tripod) or similar device.

A constant current source, providing power not less than 260 V and a current not less than 20 A.

Muffle furnace with thermostat, providing a temperature of 800−900 °C.

Microphotometer MF-2 or similar device.

Cup platinum.

Analytical scale type ADV-200 or similar type.

Libra torsion bar type W-500.

Spectromancer of PS-18 or similar type.

A device for sharpening graphite electrodes.

Mortar and pestle made of organic glass.

Box of organic glass.

Electrodes graphite high purity-7−3 6 mm in diameter, with a spherical recess in the end face (the radius of the sphere is 5 mm, depth 1 mm) and sharpened on the convex hemisphere with a radius of 5 mm, annealed in the arc of direct current at 10 A for 7 s.

Vaseline cosmetic or similar, clean silicon, iron, aluminum, manganese and chromium at the level of 5·10% by weight.

Plate: organic glass size 6х20 cm for mixing of the sample with vaseline.

Stands made of plexiglass and wood for the electrodes with the sample.

Measurer-plate 4 mm thick with drilled hole 5 mm in diameter.

Spectral photographic plates 9x12 type 2, feelings. 15 units or equivalent, providing normal blackening of analytical lines.

Vanadium pentoxide spectral-net.

Iron oxide according to GOST 4173−77, h.d. a.

Silicon dioxide according to GOST 9428−73, h. d. a.

Aluminium oxide, C. D. and.

Ammonium chloride according to GOST 3773−72.

Sodium Chernovetskiy according to GOST 27068−86.

Manganese dioxide, H. h

Chromium oxide, h.d. a.

The technical rectified ethyl alcohol according to GOST 18300−72.

The developer according to GOST 10691.1−84.

Fixer: 300 g chernovetskogo sodium, 20 g of ammonium chloride dissolved respectively in 200 and 700 GMof water, poured the resulting solutions together and the total volume was adjusted with water to 1 DM.
________________
* The text matches the original. — Note the manufacturer’s database.

Stopwatch.

Tracing.

Wool.

Spatula.

The scalpel.

A pair of tweezers.

Lamp infrared ikz-500 with voltage regulator type RNO-250−0,5 or controller of the same type.

(Changed edition, Rev. N 1).

3. PREPARATION FOR ASSAY

3.1. Preparation of a primary reference sample (OOS) containing 5% of silicon, iron, aluminum, manganese and chromium.

References are prepared on the basis of representing a pure vanadium pentoxide (at a total content of alloying components in the alloy up to 8%) or an artificial mixture of oxides simulating the composition of the analyzed alloy (base).

1,3400 g bases, 0,1069 g of silicon dioxide, 0,0715 g of iron oxide, 0,0945 g of aluminium oxide, 0,0790 g of manganese dioxide, 0,0730 g of chromium oxide is ground in a mortar made of organic glass under a layer of alcohol (30 cm) for 1.5−2 h. the Mixture is dried under an infrared lamp to constant weight. Before taking batches oxides calcined at 400 °C to constant weight.

A lot of portions weighed in the balance, with a spatula, pour in the packet of tracing paper. Spatula, boat weights, mortar is rubbed with cotton wool moistened with alcohol. To prepare packet tracing paper cut with a scalpel.

(Changed edition, Rev. N 1).

3.2. Sample preparation comparison (OS) serial dilution of the primary reference sample, and then each subsequent sample basis.

The mass fraction of each of the designated impurities in the reference sample (percentages, based on the metal content of a mixture of metals) and the mass added to the mixture in batches of basics and diluted sample are shown in table.1.

The mixture is ground in a mortar under a layer of alcohol (30 cm) for 1.5−2 h and dried under an infrared lamp.

The comparison samples stored in plastic jars with lids from polyethylene.

Table 1

(Changed edition, Rev. N 1).

4. ANALYSIS

A portion of the sample weighing 0.5 g was placed in a platinum Cup and calcined in a muffle until constant weight at a temperature of 850 °C.

Taken from the muffle furnace a Cup of oxidized melt is cooled in air, wetting the melt 10 cmof alcohol. Slightly deforming the walls of the Cup, remove the melt and thoroughly mix it with 10 cmof ethanol in a mortar made of organic glass. The mixture is dried under an infrared lamp to constant weight. Weighed on a torsion balance, 5 mg of prepared sample and mix it with vaseline, taken using the measuring device, on a glass plate with a spatula. The resulting mixture is applied with a spatula on a three-electrode with a spherical recess at the end.

The electrode with the sample installed in the lower tripod holder with tweezers. In the upper holder set carbon electrode, sharpened to a convex hemisphere. The index of the scale of the wavelength of the spectrograph is mounted so that a part of the spectrum around 290 nm was in the middle of the spectrogram. In the intermediate condenser set aperture of 5 mm. Between the electrodes ignite the DC arc, and photographing spectra of each pair of electrodes on the spectrograph, using the being system of the slit illumination.

The arc current is maintained at (15±0,5) A.

The interelectrode distance is 3 mm, exposure time of each spectrum was 30 s. the same operations are performed with samples of comparison spectra being photographed on the same photographic plate. The spectrum of each test sample (or each sample comparison) photographed three times.

(Changed edition, Rev. N 1).

5. PROCESSING OF THE RESULTS

5.1. Each of the obtained spectrograms with photoretrieval find the blackening of analytical lines of impurities () and compare () (table.2) and calculate the difference pucherani . On three values , , obtained three spectrograms taken for each sample, find the arithmetic mean ().

The results of electrophoretic spectra of comparison samples to build calibration graphs in the coordinate , where is the logarithm of the mass fraction of the element in the reference sample.

Table 2

Mass fraction of silicon, iron, aluminum, chromium and manganese in alloy find the results of electrophoretic spectra using the calibration graphs.

(Changed edition, Rev. N 1).

5.2. Discrepancies between the results of the three definitions (the difference between larger and smaller) and the results of the two tests should not exceed the values of permissible differences given in table.3.

Table 3

(Changed edition, Rev. N 1).

5.3. Check the value of control experience

To check the value of the reference experiment six carbon electrodes cause mixed with vaseline the basis of the analyzed alloy and photographed spectra according to claim 4. In the resulting spectrograms photometric density pucherani analytical lines of silicon, iron, aluminum, chromium and manganese (see table.2). The difference pucherani () should not exceed 0.02 units pochernenija (background is measured in the shorter wavelengths of the analytical lines).

(Changed edition, Rev. N 1).