GOST 25278.7-82
GOST 25278.7−82 Alloys and alloys of rare metals. Methods for determination of niobium (with Amendments No. 1, 2)
GOST 25278.7−82
Group B59
STATE STANDARD OF THE USSR
ALLOYS AND ALLOYS OF RARE METALS
Methods for determination of niobium
Alloys and foundry alloys of rare metals. Methods for determination of niobium
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 | Item number |
| GOST 3118−77 |
2.1, 3.1 |
| GOST 4204−77 |
2.1, 3.1 |
| GOST 5817−77 |
2.1, 3.1 |
| GOST 7172−76 |
2.1, 3.1 |
| GOST 8981−78 |
3.1 |
| GOST 10652−73 |
2.1, 3.1 |
| 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 two methods for determination of niobium:
photometric (5 to 30%) for alloys (ligatures) based on Zirconia containing not more than 5% of titanium, based on hafnium (components of aluminium not more than 10%, molybdenum not more than 10%, tantalum, not more than 30%);
differential photometric (from 30 to 70%) for alloys (ligatures) based on vanadium, containing not more than 5% of zirconium, and binary alloys of niobium-rhenium and niobium-titanium.
(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. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF NIOBIUM
The method is based on formation of colored complex compounds of niobium with 4- (2-pyridylazo)-resorcinol in tartrate-hydrochloric acid (0.6 M in hydrochloric acid) solution. The definition does not interfere up to 10 mg of molybdenum, titanium, vanadium (IV), aluminum, iron; up to 2 mg of zirconium and up to 1 mg of hafnium (in the presence of Trilon B); 0.5 mg of tantalum.
2.1. Apparatus, reagents and solutions
Brand photoelectrocolorimeter FEK-56 or similar device.
Muffle furnace with thermostat providing temperatures up to 1000 °C.
Analytical scale.
Libra technical.
Tile electric.
The quartz crucibles high capacity of 40 cm.
Volumetric flasks with a capacity of 100 and 1000 cm.
Pipette with divisions of 5 cm.
Pipettes without dividing 5 and 10 cm.
Microburette with a capacity of 5 cm.
Beakers measuring 50 and 100 cm.
Potassium preservatory according to GOST 7172−76.
Sulfuric acid according to GOST 4204−77.
Hydrochloric acid by the GOST 3118−77, diluted 1:1.
Tartaric acid according to GOST 5817−77, solutions 150 and 30 g/DM.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, solution 0,05 mol/l; prepared as follows: 18.6 g Trilon B dissolved in water with heating (if the solution is turbid, it is filtered), transferred to a volumetric flask with a capacity of 1 DM
, is cooled and adjusted to the mark with water.
4- (2-pyridylazo)-resorcinol disodium salt, 1-water (VAPOR) aqueous solution of 1 mg/cm.
Niobium metal containing at least 99.9% of niobium, in powder or fine shavings.
A standard solution of niobium (spare) containing 1 mg/cmNB: the 0.1 g of niobium metal is placed in a quartz crucible and melted with 4 g of potassium persulfate in muffle at the temperature of 600−700 °C until a clear melt. The smelt is dissolved by heating in 20 cm
of a solution of tartaric acid is 150 g/DM
. The resulting solution was transferred to volumetric flask with a capacity of 100 cm
, cooled, adjusted to the mark with water and mix.
The solution of niobium (working) containing 20 µg/cm, is prepared by dilution of a standard solution with a solution of tartaric acid 30 g/DM
50 times.
(Amended,
Izm. N 1).
2.2. Analysis
2.2.1. A portion of the sample weighing 0.1 g was placed in a quartz crucible, add 2−4 g of persulfate potassium, 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 a solution of tartaric acid is 150 g/DM
, cool, transfer the solution into volumetric flask with a capacity of 100 cm
. The solution was again diluted in a measuring flask with a capacity of 100 cm
is taken 10 cm
of the solution (the expected mass fraction of niobium 5−15%) or 5 cm
(for the mass concentration of niobium 15−30%) and adjusted to the mark with a solution of tartaric acid 30 g/DM
.
For the determination of niobium taken 5 cmof the solution in a volumetric flask with a capacity of 100 cm
, flow 10 cm
of hydrochloric acid, about 50 cm
water, 1 cm
of solution Trilon B, 5 cm
solution PAIRS, mixing after adding each reagent, adjusted to the mark with water. After 1 hour (colored solutions are stable 24 HR) measure the optical density of solutions on the photoelectrocolorimeter at
Mass of niobium find the calibration
graphics.
2.2.2. Construction of calibration curve
In a volumetric flask with a capacity of 100 cmpoured from microburette from 1.0 to 5.0 cm
standard working solution of niobium with an interval of 1.0 cm
, is diluted (if necessary) up to 5 cm
with a solution of tartaric acid 30 g/DM
, poured 10 cm
of hydrochloric acid, about 50 cm
water, 1 cm
of solution Trilon B, 5 cm
solution PAIRS, mixing after adding each reagent, adjusted to the mark with water. In one of the flasks poured all reagents with the exception of niobium (zero solution). After 1 hour measure optical density of solutions on the photoelectrocolorimeter at
According to the obtained results build a calibration curve in the coordinates: the optical density is the mass of niobium. Separate test points of the graph along with the analysis of PR
about.
2.3. Processing of the results
2.3.1. Mass fraction of niobium () in percent is calculated by the formula
where is the mass of niobium, was found in the calibration graphics mg;
the capacity of volumetric flasks at the first dilution, cm
;
the capacity of the volumetric flask for the second dilution solution, cm
;
— aliquotes volume of the solution taken for dilution, cm
;
— aliquotes volume of the solution taken for the determining, cm
;
— the weight of the portion of the sample,
G.
2.3.2. 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.1.
Table 1
| Mass fraction of niobium, % |
The allowable divergence, % |
| 5,0 |
0,4 |
| 10,0 |
0,8 |
| 15,0 |
1,3 |
| 20,0 |
1,7 |
| 25,0 |
2,1 |
| 30,0 |
2,5 |
(Changed edition, Rev. N 1).
3. DIFFERENTIAL PHOTOMETRIC METHOD FOR THE DETERMINATION OF NIOBIUM
The method is based on formation of colored complex compounds of niobium with 4- (2-pyridylazo)-resorcinol (PAR) in tartrate-hydrochloric acid (1 M hydrochloric acid) solution. Measurement of optical density of solutions produced relative to the comparison solution containing 0.6 mg of niobium. Vanadium (IV), rhenium and titanium do not interfere with the determination. Zirconium mask Trilon B.
(Changed edition, Rev. N 2).
3.1. Apparatus, reagents and solutions
Spectrophotometer type SF-4A or similar device.
Muffle furnace with thermostat providing temperatures up to 1000 °C.
Tile electric.
The mechanical stirrer.
Analytical scale.
Libra technical.
The quartz crucibles high capacity of 40 cm.
The flask with the Bunsen water jet pump.
Crucibles Of Gooch No. 4.
Filter «red ribbon».
Volumetric flasks with a capacity of 100 and 500 cm.
Pipettes with graduation marks at 5 and 10 cm.
Pipettes without dividing by 5 and 10 cm.
Burettes capacity 10 cm.
Glasses chemical glass with a capacity of 250 and 500 cm.
Beakers measuring 50 and 100 cm.
Potassium preservatory according to GOST 7172−76.
Sulfuric acid according to GOST 4204−77.
Hydrochloric acid by the GOST 3118−77, diluted 1:1.
Tartaric acid according to GOST 5817−77, solutions of 100 and 40 g/DM.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, solution 0,05 mol/l; prepared as follows: 18.6 g Trilon B dissolved in water with heating (if the solution is turbid, it is filtered), transferred to a volumetric flask with a capacity of 1 DM
, is cooled and adjusted to the mark with water.
The technical rectified ethyl alcohol GOST 18300−87.
The ethyl ether according to GOST 8981−78.
4- (2-pyridylazo)-resorcinol disodium salt, 1-water (STEAM), purified by reprecipitation, an aqueous solution of 1 mg/cm.
Cleaning STEAM: 0.5 g sales reagent is dissolved in 250 cm.of ethanol with constant stirring for 2 h. the Insoluble precipitate was filtered off on a paper filter of medium density red ribbon and drop. To the filtrate is added with stirring three times (by volume) excess of ethyl ether. The completeness of the precipitation reagent check by the addition of ether to the clarified portion of the solution. After 30 min the solution and the precipitate was filtered through filter «red ribbon» placed in the crucible of the Gooch. The filter cake was washed several times with ether. Dry the filter cake at room temperature.
Niobium metal containing at least 99.9% of niobium, in powder or fine shavings.
A standard solution of niobium (spare) containing 1 mg/cmNB: the 0.5 g of niobium metal is placed in a quartz crucible and fused with 10 g of potassium persulfate in muffle at the temperature of 600−700 °C until a clear melt. The melt was dissolved with heating in 200 cm
of a solution of tartaric acid 100 g/DM
, the resulting solution was cooled and transferred to volumetric flask with a capacity of 500 cm
, was adjusted to the mark with water and mix. The solution of niobium (working) containing 100 µg/cm
, is prepared by dilution of a standard solution with a solution of tartaric acid 40 g/DM
10 times.
(Changed edition, Rev. N 1, 2
).
3.2. Analysis
3.2.1. A portion of the sample weighing 0.1 g was placed in a quartz crucible, add 2−4 g of persulfate potassium, a few drops of concentrated sulphuric acid and fused in a muffle at a temperature of 600−700 °C to obtain a homogeneous melt. The smelt is dissolved by heating in 100 cmof solution of tartaric acid 100 g/DM
and after cooling, transfer the solution into a volumetric flask with a capacity of 500 cm
, 100 cm poured
the solution of tartaric acid 100 g/l
and adjusted to the mark with water.
For the determination of niobium in a volumetric flask with a capacity of 100 cmselect 5, 7 or 10 cm
of a solution containing 0.7 to 0.8 mg of niobium, go to 12.5 cm
with a solution of tartaric acid 40 g/DM
(the total amount of tartaric acid 500 mg) is added 0.5 cm
of the solution Trilon B, 15−20 cm
water and 15 cm
of hydrochloric acid, about 15 cm
of solution PAIRS, mixing after adding each reagent, and bring to mark with water. After 3 h (colored solutions are stable 24 HR) measure the optical density of solutions on the spectrophotometer at
540 nm in a cuvette with the thickness of the light absorbing layer 20 mm relative to the comparison solution containing 0.6 mg of niobium: in a volumetric flask with a capacity of 100 cm
is taken 6 cm
working solution of niobium, go to 12.5 cm
of a solution of tartaric acid 40 g/DM
, 0.5 cm
of the solution Trilon B, 15−20 cm
water and 15 cm
of hydrochloric acid, about 15 cm
of solution PAIRS, mixing after adding each reagent. After 3 h the solution is used as solution comparison.
Mass of niobium find the calibration schedule.
(Changed red
Ktsia, Rev. N 1).
3.2.2. Construction of calibration curve
In a volumetric flask with a capacity of 100 cmis introduced from the burette 6,0; 6,5; 7,0; 7,5 and 8,0 cm
working solution of niobium, which corresponds to 0,6; 0,65; 0,7; 0,75 and 0,8 mg of niobium. Go to 12.5 cm
solution of tartaric acid 40 g/DM
0.5 cm
Trilon B, 15−20 cm
water and 15 cm
of hydrochloric acid, about 15 cm
of solution PAIRS, mixing after adding each reagent, adjusted to the mark with water and mix. After 3 h measure the optical density of solutions containing from 0.65 to 0.8 mg of niobium, against the solution containing 0.6 mg of niobium, on the spectrophotometer at
540 nm in a cuvette with the thickness of the light absorbing layer 20 mm.
According to the obtained results build a calibration curve in the coordinates: the optical density is the mass of niobium. Separate test points of the graph along with the analysis of PR
about.
3.3. Processing of the results
3.3.1. Mass fraction of niobium () in percent is calculated by the formula
where is the mass of niobium, was found in the calibration graphics mg;
— capacity volumetric flasks, cm
;
— aliquotes volume of the solution taken for the determining, cm
;
— the weight of the portion of the sample,
3.3.2. 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.
Table 2
| Mass fraction of niobium, % |
The allowable divergence, % |
| 30,0 |
0,8 |
| 35,0 |
1,0 |
| 40,0 |
1,1 |
| 45,0 |
1,3 |
| 50,0 |
1,4 |
| 55,0 |
1,5 |
| 60,0 |
1,7 |
| 65,0 |
1,8 |
| 70,0 |
1,9 |
(Changed edition, Rev. N 1).
