GOST 18385.7-89
GOST 18385.7−89 Niobium. Spectral method of determination of tantalum
GOST 18385.7−89
Group B59
STATE STANDARD OF THE USSR
NIOBIUM
Spectral method of determination of tantalum
Niobium. Spectral method for the determination of tantalum
AXTU 1709
Valid from 01.01.91
before 01.01.96*
_______________________________
* Expiration removed
Protocol 5−94 N Interstate Council
for standardization, Metrology and certification
(IUS N 11/12, 1994). — Note the manufacturer’s database.
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR
DEVELOPERS
A. V. Elyutin, Yu. A. Karpov, L. N. Filimonov, E. S. Blinov, A. S. Terekhov, V. G. Ashkhotov
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Item number |
| GOST 244−23* |
Sec. 2 |
| GOST 3118−77 |
Sec. 2 |
| GOST 3773−72 |
Sec. 2 |
| GOST 4640−84 |
Sec. 2 |
| GOST 6563−75 |
Sec. 2 |
| GOST 10691.1−84 |
Sec. 2 |
| GOST 18300−87 |
Sec. 2 |
| GOST 18385.0−79 |
1.1 |
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* Consistent with the original. — Note the manufacturer’s database.
This standard applies to the spectral method of determining the mass fraction of tantalum ingot niobium is from 0.05 to 1%.
The method is based on the intensity of the spectral lines of the tantalum from its mass fraction in the sample with the excitation spectrum of the arc AC (low spark).
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 18385.0*.
______________
* On the territory of the Russian Federation GOST 18385.0−89. — Note the manufacturer’s database.
2. APPARATUS, MATERIALS, REAGENTS AND SOLUTIONS
The quartz type spectrograph ISP-30 being system.
The arc generator type DG-2, STU-81−14−62 or IVS-28 in spark mode (low spark). The current in the primary winding of high voltage transformer in the scheme of Energizer, 0.1 A, 250 Ohm.
The strength of the discharge current in the analytical period of 1 A.
The analytical gap is 1.5 mm.
The working gap of a spark gap — 0.5 mm.
Microphotometer type MF-2.
Spectromancer type SPP-2.
Analytical scale.
Libra torsion.
Libra technical.
Electric type SNOL-1,6.2.0.0.8/9-M1.
Drying oven electric round-type 23−151.00.00.000 PS.
Drying Cabinet.
The stopwatch according to GOST 5072.
Thermometer laboratory.
The measuring cylinders.
Beakers measuring.
Volumetric flasks.
Mortar and pestle agate or Jasper.
Box of organic glass.
Cup platinum N 115−9 according to GOST 6563.
Lamp infrared type IR 3−500 with voltage regulator type PH 0−250−0,5.
Grinding machine graphite electrodes.
Graphite electrodes for spectral analysis of high purity 7−3 mark with a diameter of 6 mm, a channel depth of 1 mm and a diameter of 4.1 mm (bottom).
Graphite electrodes for spectral analysis of the brand high purity 7−3, with a diameter of 6 mm, a height of sharpened pieces of 5−7 mm and a diameter of 4 mm (upper).
Graphite powder grade high purity 7−4.
Oil press, hydraulic pressure of 200 kg/cm.
The mould (with a diameter of 4.0 mm, a depth of 4.0 to 5.0).
Baptiste for cleaning the optics.
Flannel for obtenci devices and generators.
Mineral wool GOST 4640*.
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* On the territory of the Russian Federation GOST 4640−93. — Note the manufacturer’s database.
The technical rectified ethyl alcohol according to GOST 18300.
Of niobium pentoxide, from clean.
Tantalum pentoxide of high purity, containing not less than 99.9% of the main substance.
Hydrochloric acid according to GOST 3118.
Ammonium chloride according to GOST 3773.
Sodium Chernovetskiy (hyposulphite) according to GOST 244.
Photographic plates 9x12, type II or equivalent, providing normal blackening of analytical lines.
The developer according to GOST 10691.1.
Fixer: suspension chernovetskogo sodium weight of 300 g and a portion of ammonium chloride weighing 20 g was dissolved respectively in 200 and 700 cmof water, poured the resulting solutions together and the volume was adjusted with water to 1 DM
.
3. PREPARATION FOR ASSAY
3.1. Sample preparation comparison (OS)
3.1.1. Preparation of a primary reference sample (OOS) containing 10% tantalum (calculated as mass fraction of tantalum in the mixture of niobium metal, tantalum) on the basis of niobium pentoxide.
A sample of niobium pentoxide by mass 1,2874 g and the weight of tantalum pentoxide mass 0,1221 g is ground in an agate or agate mortar under a layer of alcohol within 1−1,5 hours (alcohol consumption per operation 15 cm). The mixture is dried under an infrared lamp to constant weight.
3.1.2. References (OS) is prepared from the primary reference sample serial dilution of the niobium pentoxide (base) that does not contain tantalum, the grinding of the mixture in a Styrofoam mortar under a layer of alcohol for 1.5−2 h and drying under an infrared lamp to constant weight (consumption of alcohol in a single operation 70 cm).
The mass fraction of tantalum in the reference sample and added to the mixture sample of niobium pentoxide (base) and diluted sample are shown in table.1.
Table 1
| Marking sample |
The mass fraction of tantalum, % |
The mass of charge, g | |
| the basics |
dilute sample | ||
| OC1 |
Of 1.00 |
9,000 |
1,000 (OOS) |
| OC2 |
0,50 |
4,500 |
4,500 (OC1) |
| ОС3 |
0,25 |
4,000 |
4,000 (OS2) |
| ОС4 |
0,10 |
4,500 |
3,000 (ОС3) |
| ОС5 |
0,05 |
2,500 |
2,500 (ОС4) |
The comparison samples stored in plastic jars with lids.
4. ANALYSIS
Shavings of niobium is washed with hydrochloric acid in a glass beaker by heating. The acid is drained, washed shavings with distilled water and alcohol. The washed chips is placed in a platinum Cup and calcined in muffle for 4 h to constant weight, gradually increasing the temperature of (850±50) °C. From 1 g of niobium metal (shavings) must be received 1,430 g of niobium pentoxide.
Received pentoxide thoroughly mixed, take from it a portion weighing 30 mg and ground in a Jasper or an agate mortar with a hitch weight of 90 mg of the purified graphite powder for 5 min.
The prepared sample is transferred into a mould, compressed at a pressure of 9.8·10PA. The resulting tablet is placed in the crater, the lower carbon electrode, ensuring good contact between the carbon electrode and the tablet, installed in the electrode holder of a tripod; the upper electrode is a carbon rod with a diameter of 4 mm and a height of 7 mm grinding, between which light a low-voltage spark discharge.
The strength of the discharge current in the analytical period is 1 A.
The interelectrode distance is 1.5 mm.
Again the pressed tablet is subjected to a preliminary uzyskiwania for 10 s.
Exposure time (60−90 s) is selected depending on characteristics of the device and varieties of used photographic plates so that the blackening of analytical lines were in normal pochernenija for the entire range of the designated concentrations.
The same operations except for the conversion into the pentoxide, comply with each of the working samples in the comparison.
5. PROCESSING OF THE RESULTS
5.1. In each of the spectrograms of photoretrieval find the blackening of analytical lines of the designated element (tantalum) (
) and calculate the difference pucherani for the analytical line (
according to the tables contained in the Annex to GOST 13637.1.
Table 2
| The designated element |
Wavelength of analytical lines, nm |
Line comparisons, nm |
| Tantalum |
240,063 |
Niobium — 240,103 |
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 tantalum in the sample of niobium find the results of electrophoretic spectra using a calibration chart.
The difference between the largest and smallest results of the three parallel definitions should not exceed the allowable absolute values of the differences indicated in the table.3.
Table 3
| The designated element |
Mass fraction, % |
The absolute allowable difference, % |
| Tantalum |
0,05 |
0,03 |
| 0,10 |
0,05 | |
| 0,20 |
0,10 | |
| 0,60 |
0,20 |
5.2. Validation results
One of the analyzed samples check series is converted into the pentoxide (see sect.4). The sample of niobium pentoxide by weight of 0.5 g add a sample weight of 0.5 g of the second reference sample (originally found a mass fraction of tantalum in the analyzed sample equal to 0.25% or less) or the sample mass of 0.5 g of the first reference sample (mass fraction of tantalum in test sample 0,25−0,8%). The mixture is thoroughly ground in a mortar Styrofoam under a layer of alcohol (consumption of alcohol in a single operation 3 cm), dried under infrared lamp and analyzed in sect.4 and 5.
The analyses are correct, if the first mixture of the sample and additives, minus half of the original mass fraction found in the sample obtained (0,25±0,1)% and the second mixture (0,5±0,14)% tantalum.
If the results are outside specified limits, the control of the correctness of the results of repeat tests, increasing the number of parallel definitions up to six. The obtained average values should be for the first mixture (0,25±0,07)%, for the second mixture to (0,5±0,1)%.
