GOST 25278.2-82
GOST 25278.2−82 Alloys and alloys of rare metals. Method for the determination of vanadium (with Amendments No. 1, 2)
GOST 25278.2−82
Group B59
STATE STANDARD OF THE USSR
ALLOYS AND ALLOYS OF RARE METALS
Method for the determination of vanadium
Alloys and foundry alloys of rare metals. Method for determination of vanadium
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
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
| The designation of the reference document referenced |
Section number, paragraph |
| GOST 84−76 |
2 |
| GOST 4197−74 |
2 |
| GOST 4204−77 |
2 |
| GOST 4208−72 |
2 |
| GOST 4461−77 |
2 |
| GOST 6552−80 |
2 |
| GOST 6691−77 |
2 |
| GOST 20490−75 |
2 |
| GOST 22180−76 | 2 |
| GOST 26473.0−85 |
1.1 |
6. Validity extended until
7. REPRINT (November 1988) with amendment No. 1, approved in October 1987 (ICS 1−88).
The Change No. 2 adopted by the Interstate Council for standardization, Metrology and certification (Protocol No. 12, 21.11.97). The state developed by Russia. By the resolution of Gosstandart of Russia dated
Change No. 2 made by the manufacturer of the database in the text IUS N 6, 1998
This standard specifies the titrimetric method for the determination of vanadium:
from 1 to 10% in alloys (ligatures) based on niobium (components of aluminium not more than 50%, tungsten not more than 10%, of yttrium is not more than 10%, molybdenum not more than 50%, titanium not more than 50%, zirconium not more than 10%, chromium 20%, carbon not more than 1%);
from 30 to 80% — in alloys (ligatures) based on vanadium (components of aluminium not more than 50%, boron not more than 5%, tungsten not more than 10%, iron not more than 10%, manganese not more than 5%, molybdenum not more than 50%, titanium not more than 30%, chromium not more than 50%).
The method is based on the oxidation of vanadium to the pentavalent state with potassium permanganate, and the titration of vanadic acid salt Mora indicator — phenylanthranilic acid. Hydrolysis of niobium to prevent the introduction of fluorides. The definition does not interfere up to 50 mg of aluminium, of molybdenum, chromium, zirconium, yttrium; up to 15 mg of titanium; up to 10 mg of tungsten, iron; up to 5 mg of manganese and boron in the titrated solution.
(Changed edition, Rev. N 2).
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, REAGENTS AND SOLUTIONS
Muffle furnace with thermostat providing temperatures up to 900 °C.
Tile electric.
Analytical scale.
Libra technical.
Conical flasks with a capacity of 250 cm.
Pipettes of 5 and 10 cm.
Beakers with a capacity of 50 and 100 cm.
Volumetric flasks with a capacity of 500 and 1000 cm.
The quartz crucibles high capacity of 40 cm.
Potassium preservatory according to GOST 7172−76.
Burettes with a capacity of 10 and 25 cm.
Nitric acid GOST 4461−77 diluted 1:1.
Sulfuric acid GOST 4204−77 and diluted 1:1.
Orthophosphoric acid according to GOST 6552−80.
Potassium permanganate according to GOST 20490−75 or «standard-title», solution 0,02 mol/DM.
Sodium atomistically according to GOST 4197−74, a freshly prepared solution of 10 g/DM.
Urea according to GOST 6691−77.
Oxalic acid according to GOST 22180−76, a solution of 10 g/DM.
Sodium carbonate crystal according to GOST 84−76, solution 2 g/DM.
Acid phenylantranilic, solution 2 mg/cm: 0.2 g phenylanthranilic acid was dissolved with heating in 100 cm
of sodium carbonate solution concentration of 2 g/DM
.
Salt of protoxide of iron and ammonium double sulfate (salt Mora) according to GOST 4208−72, solutions of 0.02 and 0.1 mol/DM.
The Mohr salt solution 0.1 mol/l; prepared as follows: 39,5 g of Mohr salt dissolved in 500 cm
of water containing 50 cm
of concentrated sulfuric acid, cooled, transferred to a volumetric flask with a capacity of 1 DM
, adjusted to the mark with water and mix.
A solution of salt Mora and 0.02 mol/l; prepared as follows: 7.9 g of Mohr salt dissolved in 250 cm
of water containing 50 cm
of concentrated sulfuric acid, cooled, transferred to a volumetric flask with a capacity of 1 DM
, adjusted to the mark with water and mix. The titre of the salt solution Mora set experimentally before use a standard solution of vanadium.
Potassium dichromate, solution with molar concentration of the equivalent 0,1 mol/DM(oxidation reaction of iron in acid medium); prepared from standard-titre.
Potassium dichromate, solution with molar concentration of the equivalent 0,02 mol/lis prepared by dilution of a solution of 0.1 mol/DM
water 5 times.
Ammonium fluoride according to GOST 4518−75.
Establish the relationship between solutions of salt Mora and potassium dichromate (K): in a conical flask with a capacity of 250 cmwas injected by pipette 25 cm
of potassium dichromate solution with molar concentration of the equivalent 0,02 mol/l
or 0.1 mol/DM
(depending on the concentration used in the analysis of a solution of salt Mora), pour 100 cm
water and 15 cm
of sulphuric acid diluted 1:1, 5 drops of salt solution phenylanthranilic acid and titrated with Mohr salt solution with molar concentration of the equivalent 0,02 mol/l
or 0.1 mol/DM
, respectively.
The ratio () of the volume of the solution of salt Mora and the potassium dichromate is calculated by the formula
where is the volume of potassium dichromate solution taken for titration, cm
;
— the volume of salt solution Mora, used for titration, sm
.
The ratio of the set before application of salt Mora.
(Changed edition, Rev. N 1, 2).
3. ANALYSIS
3.1. A portion of the analyzed samples alloy based on niobium containing less than 0.1% by weight carbon, weighing 0.1−0.5 g depending on the content of vanadium (table 1) is placed in a conical flask with a capacity of 250 cmand dissolved with strong heating in 20 cm
of concentrated sulfuric acid. After complete dissolution of the sample flow of 100 cm
of water 1 g ammonium fluoride, and stirring the solution until the disappearance of turbidity in the case of the hydrolysis of niobium.
3.1. A portion of the analyzed samples alloy based on niobium containing less than 0.1% by weight carbon, weighing 0.1−0.5 g depending on the content of vanadium (table 1) is placed in a quartz crucible, is added 2−10 g of potassium pyrosulphate (depending on mass of sample), a few drops of concentrated sulphuric acid and fused in a muffle at a temperature of 700−800 °C to obtain a homogeneous melt. The smelt is dissolved by heating in 20 cmof sulphuric acid diluted 1:1, transfer the solution into the conical flask with a capacity of 250 cm
, the volume was adjusted to 100 cm
with water, add 1 g of ammonium fluoride, and stirring the solution until the disappearance of turbidity in the case of the hydrolysis of niobium.
3.1 b. The resulting solution was cooled in cold water to 15−20 °C, poured dropwise a solution of potassium permanganate until a stable pink color. After 5 minutes, the excess potassium permanganate to destroy a few drops of a solution of sodium attestatio, immediately add 1 g of urea and mix well. After 5 min, pour 4−5 drops of solution phenylanthranilic acid, mixed well and allowed to stand for 1−1. 5 min, during which the solution is painted in crimson-red color. Vanadium (V) titrated with a solution of salt Mora and 0.02 mol/DMwith vigorous stirring until the solution colour from crimson-red in green.
Table 1
| Mass fraction of vanadium, % |
The mass of charge, g |
| 1 |
0,5 |
| 2−4 |
0,2 |
| 5−10 |
0,1 |
3.1, 3.1 a, 3.1 b. (Changed edition, Rev. N 2).
3.2. A portion of the sample-based alloy vanadium with a mass of 0.1 g was placed in a conical flask with a capacity of 250 cm, flow 10 cm
of sulphuric acid (1:1) and 10 cm
of nitric acid (1:1), washed the walls of the flask with water, mixed and heated until complete decomposition of the sample. The solution is twice evaporated until dense fumes of sulphuric anhydride, cooled to room temperature, dilute with water to 100 cm
and cooled in cold water before the advent of 15−20 °C.* the cooled solution was poured dropwise a solution of potassium permanganate until a stable pink color. After 10−15 minutes the excess of potassium permanganate solution to destroy the oxalic acid, priliva it dropwise until the disappearance of the pink coloring and 1−2 drops in excess. Pour 5 cm
of orthophosphoric acid 5−7 drops of salt solution phenylanthranilic acid and titrate the vanadium (V) salt solution Mora 0.1 mol/DM
before the transition of color from purple to green.
__________________
* The text matches the original. — Note the manufacturer’s database.
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of vanadium () in percent is calculated by the formula
where — the volume of salt solution Mora, used for titration, cm
;
— concentration of salt solution Mora on vanadium, g/cm
, equal 0,005095·
(solution of salt Mora 0.1 mol/DM
) or 0,001019·
(solution of salt Mora and 0.02 mol/DM
), where
the ratio of the volume of the solution of salt Mora and potassium dichromate;
— the weight of the portion of the sample, g
.
4.2. Discrepancies between the results of two parallel determinations and the results of the two tests should not exceed the values of permissible differences given in table.2 (for alloys based on niobium) in the table.3 (for alloys based on vanadium).
Table 2
| Mass fraction of vanadium, % |
The allowable divergence, % |
| 1,0 |
0,1 |
| 5,0 |
0,2 |
| 10,0 |
0,3 |
Table 3
| Mass fraction of vanadium, % |
The allowable divergence, % |
| 30,0 | 0,4 |
| 40,0 |
0,6 |
| 50,0 |
0,7 |
| 60,0 |
0,8 |
| 70,0 |
1,0 |
| 80,0 |
1,1 |
4.1, 4.2. (Changed edition, Rev. N 1).
