GOST 11930.10-79
GOST 11930.10−79 Materials surfacing. Method for the determination of tungsten (with Amendments No. 1, 2)
GOST 11930.10−79
Group B09
INTERSTATE STANDARD
MATERIALS SURFACING
Method for the determination of tungsten
Hard-facing materials. Method of tungsten determination
ISS 25.160.20
AXTU 1709
Date of introduction 1980−07−01
The decision of the State Committee USSR on standards on March 21, 1979 N 982 date of introduction is established 01.07.80
Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)
EDITION (August 2011) with Amendments No. 1, 2 approved in December 1984, December 1989 (IUS 3−85, 3−90)
This standard establishes photocolorimetric method for the determination of tungsten (at a mass fraction of tungsten from 0.2 to 15%) in the surfacing materials.
The method is based on formation of colored complex compounds of tungsten with thiocyanate in acidic medium in the presence of a reducing agent.
Related components are separated by precipitation with sodium hydroxide.
(Changed edition, Rev. N 2).
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 11930.0−79.
2. APPARATUS, REAGENTS AND SOLUTIONS
Analytical scale types ADV-200, VLA-200M or any other type provides a weighing accuracy of 0.0002 g. more
Photocolorimeters types FEK-56, FEK-56M or any other type.
Sulfuric acid GOST 4204−77, diluted 1:4.
Nitric acid GOST 4461−77.
Sodium hydroxide according to GOST 4328−77, a solution with a mass fraction of 20%.
Hydrochloric acid by the GOST 3118−77, diluted 1:1.
Ammonium or potassium rodanistye, a solution with a mass fraction of 50%.
Titanium trichloride solution; prepared as follows: 1 cmof solution with a mass fraction of 15% titanium trichloride diluted with 24 cmof hydrochloric acid diluted 1:1 (solution not be stored for more than 2 days).
Potassium preservatory according to GOST 7172−76.
Tungsten anhydride.
Solution tungsten standard; prepared as follows: 0,1261 g of tungsten anhydride is dissolved by heating in 100 cmof solution with a mass fraction of 20% sodium hydroxide, poured into a measuring flask with volume capacity of 1000 cm, is diluted to the mark with water and mix.
1 cmstandard solution contains 0.0001 g of tungsten.
(Changed edition, Rev. N 2).
3. ANALYSIS
3.1. A portion of sample weighing 0.5 g (when the mass fraction of tungsten of 0.2−0.4%) was dissolved with heating in 50 cmof sulphuric acid, diluted 1:4, pour 1−2 cmof nitric acid and twice evaporated to fumes of sulphuric anhydride. The cooled solution is diluted with water, neutralized with alkali solution and transferred to a volumetric flask with a capacity of 100 cmcontaining 20 cmof hot (70−80 °C) 20% alkali solution, dilute to the mark with water and mix. Part of the solution filtered through a dry filter into a dry beaker. Select 5−20 cmof the filtrate into a measuring flask with a capacity of 50 cm. Pour 1 cmof a 50% strength solution Rodenstock ammonium 15 cmof hydrochloric acid and 1 cmof a solution of trichloride titanium. After addition of each reagent the contents of the flask stirred. The solution was diluted to the mark with water and mix again. The optical density of colored solutions are measured on a photoelectrocolorimeter with a blue filter (434 nm) in a cuvette with a thickness of the absorbing layer is 50 mm. the tungsten Content in grams found by the calibration schedule.
3.2. A portion of sample weighing 0.1 g (with a mass fraction of tungsten from 4 to 11%) is dissolved by heating in 50 cmof sulphuric acid, diluted 1:4, pour 1−2 cmof nitric acid. The solution is twice evaporated to a weak sulfuric acid vapor. If the linkage is not dissolved completely, it is fused with potassium pyrosulphate.
The solution is neutralized in the Congo with a solution with a mass fraction of 20% sodium hydroxide and poured into a volumetric flask with a capacity of 250 cm, with 30 cmhot solution with a mass fraction of 20% sodium hydroxide, then cooled, diluted to the mark with water and mix. Part of the solution was filtered into a dry beaker and taken aliquot part (5−10 cm) in a volumetric flask with a capacity of 50 cm. Further analysis are as indicated in claim 3.1.
(Changed edition, Rev. N 2).
3.3. Construction of calibration curve
In a volumetric flask with a capacity of 50 cmplaced 1, 2, 3 and 4 cmstandard solution tungsten, diluted to 20 cmwith water and further analysis are as indicated in claim 3.1.
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of tungsten () in percent is calculated by the formula
,
where is the mass of tungsten was found in the calibration schedule g;
— dilution of the test solution, cm;
— aliquota part of the analyzed solution, cm;
— the weight of the portion,
4.2. The difference between the largest and smallest results of the three parallel measurements, and the two results of the analysis at a confidence level of 0.95, should not exceed the values of permissible differences given in the table.
Mass fraction of tungsten, % | The allowable divergence of the three parallel definitions % | Permissible discrepancies in the results of the analysis % | ||||
From | 0,20 | to | 0,40 | incl. | 0,02 | 0,03 |
SV. | Of 4.00 | « | 5,00 | « | 0,05 | 0,10 |
« | 5,00 | « | 11,00 | « | 0,10 | 0,20 |
« | 11,00 | « | 15,00 | « | 0,25 | 0,30 |
(Changed edition, Rev. N 2).