GOST 18385.1-79
GOST 18385.1−79 Niobium. Methods for determination of tungsten (with Amendments No. 1, 2)
GOST 18385.1−79
Group B59
STATE STANDARD OF THE USSR
NIOBIUM
Methods for determination of tungsten
Niobium. Methods for the determination of tungsten
AXTU 1709*
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* Code standard. Introduced later, Rev. N 1.
Valid from 01.07.1980
before 01.07.1985*
_________________________________
* Expiration removed
Protocol 5−94 N Interstate Council
for standardization, Metrology and certification
(IUS N 11/12, 1994). — Note the manufacturer’s database.
DEVELOPED by the Ministry of nonferrous metallurgy of the USSR
PERFORMERS
A. V. Elyutin, Yu. A. Karpov, A. G. Valkanov, L. N. Filimonov, V. V. Korolev, V. V. Nedler, V. G., Miscreants, T. M. Malyutina, V. M. Mikhailov, E. G. Nembrini
INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
Member Of The Board Of A. P. Snurnikov
APPROVED AND promulgated by the Decree of the State Committee USSR on standards on may 30, 1979 N 1968
INSTEAD 18385.6 GOST-73
MADE: the Change in N 1, approved and put into effect by the Decree of the USSR State Committee for standards from
Change N 1, 2 made by the manufacturer of the database in the text IUS N 1, 1985, IUS N 3, 1990
This standard sets the photometric method for the determination of tungsten from 0.004 inch to 0.04%.
(Changed edition, Rev. N 2).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 18385.0−79*.
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* On the territory of the Russian Federation GOST 18385.0−89, here and hereafter. — Note the manufacturer’s database.
2. The PHOTOMETRIC METHOD for the DETERMINATION of TUNGSTEN (with tungsten mass fraction of from 0.004 inch to 0.04%)
The method is based on decomposition of the sample by melting the sample with sodium hydroxide, the separation of the tungsten from the substrate by treatment with water, extraction of the complex compound of tungsten with ditylum amylacetate (or chloroform), and measuring the optical density of the extract.
The impact of a tenfold weight excess of molybdenum is suppressed by the introduction of an excess of reducing agent is titanium trichloride.
Mass fraction of tungsten and molybdenum can be determined from alikvotnih different parts of one solution of the test sample.
2.1. Apparatus, reagents and solutions
Type photoelectrocolorimeter FEK-60 or similar type.
Oven muffle.
Nickel crucibles.
Analytical scale.
Microburette.
Separating funnel with a capacity of 50 cm.
Pipette piston.
Cylinders with a capacity of 50−100 cm.
Volumetric flasks with a capacity of 25, 100, 1000 cm.
Beakers capacity 50, 100, 250 cm.
Tungsten (VI) oxide.
Sodium hydroxide according to GOST 4328−77 and a solution with a mass fraction of 10%.
Solution: a sample of sodium hydroxide with a weight of 100 grams are placed in a beaker with a capacity of 250 cm, dissolved in water, the solution was transferred to volumetric flask with a capacity of 1 DM
and bring to mark with water.
Hydrochloric acid by the GOST 3118−77.
The technical rectified ethyl alcohol GOST 18300−87.
Titanium metal according to GOST 19807−74* brand БТ1−00.
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* On the territory of the Russian Federation GOST 19807−91. — Note the manufacturer’s database.
Distilled water.
Zinc-dithiol.
Suspension zinc dithiol: hitch zinc-dithiole a mass of 0.1 g was triturated in a porcelain mortar with a minimal amount of alcohol and diluted with the same alcohol to 25 cm. Before use the suspension was shaken.
Titanium trichloride solution with a mass fraction of 15%: the portion of titanium with a mass of 0.5 g with a basic substance content not less than 99.5% was dissolved with heating in 10 cmof hydrochloric acid in a beaker with a capacity of 25−50 cm
, covered with a watch glass. The initial volume of 10 cm
is constantly supported by the addition of hydrochloric acid. Solution store in a dark bottle with glass stopper no more than 3 days.
Amyl ether acetic acid (amylacetate).
Chloroform according to GOST 20015−88.
(Changed edition, Rev. N 2).
2.2. Preparation for assay
2.2.1. Preparation of standard solutions of tungsten
A solution of tungsten (spare) containing 0.1 mg/cmtungsten: a sample of an oxide of tungsten weight 0,126 g, calcined to constant weight at 600−700 °C, is dissolved in several cubic centimeters of a 10% solution of sodium hydroxide; solution was transferred to volumetric flask with a capacity of 1 DM
and adjusted to the mark with water.
A solution of tungsten (work) containing 0.01 mg/cmtungsten, is prepared by diluting a backup solution with water in 10 times a day use.
2.2.2. Construction of calibration curve
In glasses with a capacity of 50 cmflow 0,3; 0,5; 0,7; 3,0; 1,5; 2,0; 3,0; 4,0 and 5.0 cm
of the working standard solution of tungsten, which corresponds to 3,0; 5,0; 7,0; 10,0; 15; 20; 30; 40 and 50 µg of tungsten, top up with water to 15 cm
, flow 15 cm
of hydrochloric acid and stirred. Pour 8−10 drops of a solution of trichloride titanium (the appearance of purple staining) and heated to boiling. The solutions were cooled slightly, pour 1 cm
of a suspension of zinc-dithiol and transferred to a cylinder with glass stopper with a capacity of 50−100 cm
. The cylinders were placed in a glass of boiling water for 5−7 min. the Solutions were cooled, transferred to a separatory funnel with a capacity of 50 cm
, flow from microburette or pipette with the piston 5 cm
of amylacetate (or chloroform), shaken for 1 min and after separation the aqueous phase is discarded.
The obtained extracts are successively transferred in a dry cell of photoelectrocolorimeter with a thickness of the light absorbing layer 5 mm (when the mass of tungsten in fotometriya extract more than 20 g) or 10 mm (when the mass of tungsten, less than 20 mcg). The cuvette cover with a lid, allow the extract to settle the bubbles and measure the optical density of each extract on the photoelectrocolorimeter using a filter with maximum transmittance at a wavelength of 660 nm against water.
On the found values of optical density and corresponding mass of tungsten build the calibration.
K.
2.2.1,
2.3. Analysis
0.3−0.5 g of shavings of niobium (if the mass fraction of tungsten up to 0.02%, take 0.5 g, more than 0,02% — 0.3 g) was placed in a Nickel crucible, where the pre-melted on a hotplate, and 1 g of sodium hydroxide, add 3 g of sodium hydroxide, the crucible is placed in a cold muffle, bring the temperature to 800−850 °C and fused to a homogeneous melt. The crucible with the melt is cooled and treated by boiling 60 cmof water in a glass with a capacity of 150−200 cm
.
After cooling the solution to precipitate transferred to a volumetric flask with a capacity of 100 cm, is diluted to the mark with water, mix thoroughly and leave to pursue the sediment. Take 10−15 cm
of a clear solution in a glass with a capacity of 50−70 cm
, dilute with water to 15 cm
, flow 15 cm
of hydrochloric acid and stirred. Add 1.5 cm
of freshly prepared solution of trichloride titanium, left for 10 min under stirring and heated to boiling. The solution is cooled slightly, poured 1 cm
of a suspension of zinc-dithiol and transferred to a cylinder with a capacity of 50−70 cm
with glass stopper. The cylinders were placed in a glass of boiling water for 5−7 min. the Solutions were cooled, transferred to a separatory funnel with a capacity of 50 cm
, flow from microburette or pipette with the piston 5 cm
of amylacetate (or chloroform), using the same extractant used in the preparation of solutions (see p.2.2.2), and shaken for 1 min. After the separation of the aqueous phase is discarded and the extract was transferred to a dry cuvette and measure the optical density (p.2.2.2).
Simultaneously with the analysis under the same conditions by two parallel reference experiment for inclusion in the analysis result of the relevant amendment.
Optical density of the solution in the reference experiment should not exceed 0.01. From the values of absorbance of the analyzed solution is subtracted the average value of the optical density of the solution in the reference experiment.
The mass of tungsten in the sample solution found by the calibration schedule.
(Changed edition, Rev. N 1).
2.4. Processing of the results
2.4.1. Mass fraction of tungsten in the sample () in percent is calculated by the formula
where is the mass of tungsten was found in the calibration schedule, mcg;
— volume aliquote part, cm
;
— the weight of the portion,
The difference between the results of two parallel definitions and results of the two tests should not exceed the absolute allowable differences specified in table.1.
Table 1
| Mass fraction of tungsten, % |
Allowable absolute differences, % |
| 0,004 |
0,001 |
| 0,01 |
0,002 |
| 0,02 |
0,003 |
| 0,04 |
0,005 |
Allowable absolute differences of the intermediate mass fraction of tungsten is calculated using linear interpolation.
2.4.2. Validation results
The correctness of the results of analysis control method supplements. Three Nickel crucible placed in 1 cmstandard solution (0.1 mg of tungsten) and evaporated to dryness with gentle heating. In each crucible add 1 g of sodium hydroxide, heated to melt and injected 0.5 g of the niobium mass fraction of tungsten which is about 0.02%. Added to the crucibles with 3 g of sodium hydroxide, placed in a muffle and then analyzed on PP.2.3; 2.4.
For the result of the analysis of the sample with the addition of be the arithmetic mean of the three obtained results of single determinations. The value found supplements — the difference between the results of the analysis of the sample with the additive and initially received by result of analysis of the same sample without additives, should be within 0.02±0,0025%.
If the found value supplements out of the specified range, control the correctness of the results again, increasing the number of batches to six and getting the result of the analysis of the sample with the additive as the arithmetic average of the six results of single determinations.
Found the value of additive should be (0,0200±0,0021)%.
2.4.1,
Section 3. (Deleted, Rev. N 2).
