GOST 25278.11-82

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  ГОСТ 25278.11-82

GOST 25278.11−82 Alloys and alloys of rare metals. Spectral method for determination of silicon, iron, aluminum, titanium and calcium in the alloys based on niobium (Change No. 1)

GOST 25278.11−82

Group B59

STATE STANDARD OF THE USSR

ALLOYS AND ALLOYS OF RARE METALS

Spectral method for determination of silicon, iron, aluminum, titanium and calcium in the alloys based on niobium

Alloys and foundry alloys of rare metals. Spectral method for determination of silicon, iron, aluminium, titanium, calcium in alloys on niobium 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

3. 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 is 5 years.

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Validity extended until 01.07.93 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, aluminum, titanium and calcium from 0.01 to 1.0% in the alloys and master alloys on the basis of niobium (components: vanadium is not more than 5%, tungsten not more than 10%, molybdenum 5%, zirconium not more than 2%).

Method is based on the intensity of spectral lines of silicon, iron, aluminum, titanium and calcium 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.

Spectromancer of PS-18 or similar type.

Cup platinum.

Analytical scale.

Libra torsion bar type W-500.

A device for sharpening carbon electrodes.

Electrodes of graphite brand high purity-7−3 6 mm in diameter, sharpened to a diameter of 4.4 mm (the length of grinding 10 mm) hollow-sharpened part with a diameter of 2.5 mm and a depth of 2.0 mm (bottom).

Electrodes of graphite brand high purity-7−3 6 mm in diameter, sharpened to a truncated cone with ground diameter of 1.5 mm.

Powder graphite high purity-7−4.

Mortar with pestle, niobium or organic glass.

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

Of niobium pentoxide spectral-net.

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

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

Titanium dioxide according to GOST 9808−84, H. h

Aluminum oxide, H. h

Calcium oxide according to GOST 8677−76, H. h

Cobalt oxide according to GOST 18671−73, h.d. a.

Hydrochloric acid by the GOST 3118−77, diluted 1:1.

The technical rectified ethyl alcohol GOST 18300−87.

The developer according to GOST 10691.1−84.

Sodium Chernovetskiy according to GOST 27068−86.

Ammonium chloride according to GOST 3773−72.

Fixer: 300 g chernovetskogo of sodium and 20 g of ammonium chloride dissolved respectively in 200 and 700 cmof water, poured the resulting solutions together and the total volume was adjusted with water to 1 DM.

Stand organic glass and wood for the electrodes with the sample.

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 2% of silicon, iron, aluminum, titanium and calcium (based on the mixture of metals).

References are prepared on the basis of representing the pure pentoxide of niobium (at a total content of alloying components in the alloy up to 5%) or artificial mixture of oxides simulating the composition of the analyzed alloy (base).

1,2870 g bases, 0,0428 g of silicon dioxide, 0,0286 g of iron oxide, 0,0378 g of aluminium oxide, 0,0334 g of titanium oxide and of 0.0500 g of calcium carbonate is ground in a mortar 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)

The comparison samples are prepared by successive 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 and added to the mixture sample basis and diluted sample are shown in table.1.

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 cups with lids made of polyethylene.

3.3. Preparation of a buffer mixture consisting of 89% of graphite powder, 10% sodium chloride and 1% cobalt oxide.

8.9 g of graphite powder, 1 g of sodium chloride and 0.1 g of cobalt oxide mixed in a mortar under a layer of alcohol (150 cm) for 1 h and dried under an infrared lamp.

(Changed edition, Rev. N 1).

4. ANALYSIS

A portion of the sample weighing 0.5 g was washed with hydrochloric acid in a glass beaker by heating on a hotplate. The acid is drained, washed shavings with distilled water and alcohol. The washed chips is placed in a platinum Cup and calcined in a muffle until constant weight, gradually raising the temperature to 800 °C. the Oxidized sample is thoroughly mixed, take from it a portion of 20 mg and mixed in a mortar with 80 mg of buffer mix (weighing produce on a torsion scale) for 15 min under a layer of ethanol and then dried under an infrared lamp. The prepared mixture was stuffed tightly into the recess of the bottom three electrodes, prebaked in the arc of direct current at (7±0,5) And for 5 with immersion of the electrode into the mixture, poured into a rubber stamp.

The electrodes (top and bottom of sample) placed in the electrode holders tripod with tweezers. Mixing and subsequent dilution of the electrodes ignite the DC arc, and photographing spectra of three pairs of electrodes on the spectrograph, using the being system of the slit illumination. In the center of the cassette output region 290 nm.

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

The interelectrode distance of 3 mm, exposure 60 s.

Intermediate diaphragm in the condenser is chosen so as to ensure the normal blackening of analytical lines. The same operations are performed with samples of comparison spectra being photographed on the same photographic plate.

(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 element comparisons () (table.2) and calculate the difference pucherani ().

Table 2

On three values , , obtained three spectrograms taken for each sample, find the arithmetic mean ().

The results of electrophoretic spectra of samples comparisons build a calibration curve in the coordinates , where is the logarithm of the mass fraction of the element in the reference sample. Mass fraction of silicon, iron, aluminum, titanium and calcium in the alloy specimen find the results of electrophoretic spectra of the analyzed sample by using a calibration chart.

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 in the deepening of the six graphite electrodes is placed a mixture of bases analyzed alloy with a buffer mixture and take pictures of the spectra according to claim 4. In the resulting spectrograms photometric density pucherani analytical lines of silicon, iron, aluminum, titanium, and calcium (see table.2). The difference pucherani () should not exceed 0.02 units of blackening (background is measured in the shorter wavelengths of the analytical lines).

(Changed edition, Rev. N 1).