GOST 25278.6-82
GOST 25278.6−82 Alloys and alloys of rare metals. Methods for determination of molybdenum (with Amendments No. 1, 2)
GOST 25278.6−82
Group B59
STATE STANDARD OF THE USSR
ALLOYS AND ALLOYS OF RARE METALS
Methods for determination of molybdenum
Alloys and foundry alloys of rare metals. Methods for determination of molybdenum
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 61−75 |
2.1 |
| GOST 3117−78 |
2.1 |
| GOST 3118−77 |
2.1, 3.1 |
| GOST 3760−79 |
3.1 |
| GOST 3765−78 |
2.1, 4.1 |
| GOST 4165−78 |
2.1, 3.1, 4.1 |
| GOST 4204−77 |
2.1, 4.1 |
| GOST 4460−77 |
2.1 |
| GOST 4461−77 |
4.1 |
| GOST 4518−75 |
4.1 |
| GOST 5712−78 |
2.1 |
| GOST 5817−77 |
3.1 |
| GOST 6344−73 |
2.1, 3.1, 4.1 |
| GOST 10484−78 |
4.1 |
| GOST 10929−76 |
3.1 |
| GOST 7172−76 |
2.1 |
| GOST 25278.13−87 |
2.2.1 |
| GOST 26473.0−85 |
1.1 |
| GOST 27067−86 |
4.1 |
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 three methods for determination of molybdenum:
photometric (1 to 10%, for alloys (alloys) on the basis of niobium (components of aluminium not more than 20%, vanadium not more than 20%, tungsten not exceeding 25%, zirconium not more than 30%, of tantalum is not more than 30%, chromium not more than 20%) and on the basis of hafnium (components of aluminium not more than 30%, niobium of not more than 30%, of tantalum is not more than 30%);
differential photometric (20 to 55%) for binary alloys rhenium-molybdenum;
visual-colorimetric (from 5·10to 5·10
%) for alloys based on niobium (components: zirconium, not more than 2%, titanium not more than 1%, tantalum, less than 1%).
(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 MOLYBDENUM
The method is based on formation of colored complex compounds of pentavalent molybdenum with thiocyanate ions in hydrochloric acid medium. The reducing agent is thiourea in the presence of copper sulphate. Hydrolysis of niobium and tantalum prevent the introduction of oxalates: tungsten, zirconium, hafnium, aluminium definition, do not interfere. Prevents the presence of chromium and more than 400 mcg vanadium (IV) in fotometriya solution.
(Changed edition, Rev. N 2).
2.1. Apparatus, reagents and solutions
Photoelectrocolorimeter FEK-56 or similar device.
Muffle furnace with thermostat providing temperatures up to 1000 °C.
Analytical scale.
Libra technical.
Tile electric.
Volumetric flasks with a capacity of 50, 100, and 1000 cm.
Microburette with a capacity of 5 cm.
Pipette with divisions of 5 cm.
Pipettes without dividing by 5 and 10 cm.
Measuring beakers with a capacity of 50 and 100 cm.
Glasses chemical glass with a capacity of 250 cm.
Funnels, glass, conical.
Desiccator with calcium chloride.
Calcium chloride (fused).
Crucibles porcelain.
Burettes capacity 10 cmwith a scale division of 0.02 cm
.
Obestochennye the filter paper of «blue ribbon».
Hydrochloric acid by the GOST 3118−77 and diluted 1:1.
Potassium preservatory according to GOST 7172−76.
Sulfuric acid according to GOST 4204−77.
Ammonium oxalate according to GOST 5712−78, a solution of 40 g/DM.
Ammonium radamisty, a solution of 500 g/DM.
Copper sulfate according to GOST 4165−78, a solution of 40 g/DM.
Thiourea according to GOST 6344−73, a saturated solution of 10 g of concreteras of thiourea are dissolved in 100 cmwater at room temperature with constant stirring (dissolution occurs slowly).
Ammonia water according to GOST 3760−79.
Methyl orange (indicator), an aqueous solution of 1 mg/DM.
Ammonium acetate according to GOST 3117−78, solutions of 500 and 40 g/DM.
Acetic acid GOST 61−75, concentrated and diluted with 5:95.
Pharmaceutical tannin, a solution of 10 g/DMacetic acid, diluted 5:95, freshly prepared.
Ammonium molybdate according to GOST 3765−78.
A standard solution of molybdenum (spare) containing 1 mg/cmof molybdenum: 1,840 g of ammonium molybdate dissolved in water, transferred to a volumetric flask with a capacity of 1 DM
, adjusted to the mark with water.
The mass concentration of molybdenum set by the gravimetric method. To do this in four glasses with a capacity of 250 cmpipetted to 25 cm
standard solution of molybdenum, poured in 25−30 cm
water, 10 cm
of ammonia, 2−3 drops of methyl orange solution and neutralize with hydrochloric acid until the solution colour from yellow to red. Add 5 cm
of hydrochloric acid, 20 cm
of a solution of ammonium acetate with a concentration of 500 g/DM
5 cm
of concentrated acetic acid.
The contents of one of the glasses heated to boiling, poured from the burette dropwise a solution of acetate of lead to the enlightenment of the solution. The deposition of molybdenum is considered complete when a drop of test solution is deposition of molybdenum will not form with a solution of tannin, applied on filter paper: a yellow spot. The contents of the glass pour another 5 cmof a solution of acetate of lead. The volume of solution of acetate of lead, used for the deposition of molybdenum, is fixed.
The contents of the three remaining glasses heated to boiling and poured into them a fixed amount of a solution of acetate of lead. Glasses stand for 30 min at 60−70 °C in the electric oven, filter the hot solution through filter «blue ribbon». The filter cake is washed four to five times a hot solution of ammonium acetate and 30 g/DM. The filter with precipitate was placed in a porcelain crucible, previously ignited to constant weight, dried, incinerated, and calcined at 550−600 °C in a muffle furnace for 30 min, cooled in a desiccator and weighed. Calcined and weighed to obtain constant weight.
Mass concentration () of a standard solution of molybdenum in mg/cm
of molybdenum is calculated by the formula
where is the mass of the precipitate of lead molybdate, mg;
0,2613 — the conversion factor of lead molybdate to molybdenum.
Solution of molybdenum (working) containing 50 µg/cmof molybdenum, prepared by dilution of a standard solution with water to 20 times.
(Changed edition, Rev. N 1, 2).
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 50 cmof a solution of ammonium oxalate, cooled, transfer the solution into a volumetric flask with a capacity of 250 cm
, was adjusted to the mark with a solution of ammonium oxalate and stirred.
The solution can be used for determination of tungsten GOST 25278.13−87.
For the determination of molybdenum (in the absence of vanadium and chromium) in a volumetric flask with a capacity of 50 cmis taken aliquot part of the solution as a function of molybdenum content (table.1A), containing 50−250 µg of molybdenum, poured 12.5 cm
of concentrated hydrochloric acid, 1.5 cm
of copper sulphate solution, stirred and cooled in cold water to 18−20 °C.
Table 1a
| Mass fraction of molybdenum, % |
Alikvotnih the volume of the solution taken for the determination, see |
| 1 |
15 |
| 2 |
10 |
| 3 |
10 |
| 4−10 |
5 |
Add 15 cmof a solution of thiourea (adding of thiourea, a precipitate may form, which dissolves in a few minutes) and mix. After 10 minutes injected 1 cm
of solution Rodenstock ammonium was adjusted to the mark with water and mix thoroughly. After 10 minutes, (colored solutions are stable for 45 min), measure the optical density of the solution on photoelectrocolorimeter at
For the determination of molybdenum (in the presence of vanadium and chromium) in two volumetric flasks with a capacity of 50 cmeach, taken aliquote equal parts of a solution containing 50−250 µg of molybdenum, poured into both flasks at 12.5 cm
of concentrated hydrochloric acid, 1.5 cm
of copper sulphate solution, stirred and cooled in cold water to 18−20 °C. Add 15 cm
of a solution of thiourea, mix. After 10 minutes in one of the flasks is introduced 1 cm
of solution Rodenstock ammonium, bring both flasks to the mark with water, mix thoroughly. After 10 minutes measure the optical density of a solution containing radamisty ammonium, relative to the solution not containing ammonium radamisty on photoelectrocolorimeter at
A lot of find molybdenum in the calibration schedule.
(Changed edition, Rev. N 1, 2).
2.2.2. Construction of calibration curve
In a volumetric flask with a capacity of 50 cmis injected from microburette from 1.0 to 5.0 cm
of the working solution of molybdenum with an interval of 0.5 cm
. Poured 25 cm
hydrochloric acid (1:1), 1.5 cm
of copper sulphate solution, stirred and cooled in cold water to 18−20 °C. Add 15 cm
of a solution of thiourea (when adding a solution of thiourea can form a precipitate, which dissolves in a few minutes). After 10 minutes injected 1 cm
of solution Rodenstock ammonium, dilute to the mark with water and mix. After 10 minutes, (colored solutions are stable for 45 minutes), measure the 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 molybdenum. Separate test points of the graph along with the analysis of samples.
(Changed edition, Rev. N 2
).
2.3. Processing of the results
2.3.1. Fraction of total mass of molybdenum () in percent is calculated by the formula
where — weight of molybdenum, 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,
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 molybdenum, % |
The allowable divergence, % |
| 1,0 |
0,1 |
| 2,0 |
0,2 |
| 3,0 |
0,3 |
| 4,0 |
0,4 |
| 5,0 |
0,5 |
| 6,0 |
0,6 |
| 10,0 |
1,0 |
(Changed edition, Rev. N 1).
3. DIFFERENTIAL PHOTOMETRIC METHOD FOR THE DETERMINATION OF MOLYBDENUM
The method is based on formation of colored complex compounds of pentavalent molybdenum with thiocyanate ions in tartrate-hydrochloric acid solution. Molybdenum (VI) is reduced by thiourea in the presence of copper sulphate. Rhenium definition, does not prevent.
3.1. Apparatus, reagents and solutions
Photoelectrocolorimeter FEK-N-57 or similar device.
Oven electric.
Analytical scale.
Libra technical.
Bath water.
Conical flasks with a capacity of 100 cm.
Watch-glasses.
Volumetric flasks with a capacity of 50, 250 and 500 cm.
Pipettes without division into 5, 10, 15 cm.
Pipette with divisions of 5 cm.
Burettes capacity 10 cm.
Measuring beakers with a capacity of 25 and 50 cm.
Hydrochloric acid by the GOST 3118−77.
Hydrogen peroxide according to GOST 10929−76.
Ammonia water according to GOST 3760−79.
Tartaric acid according to GOST 5817−77, a solution of 500 g/DM.
Copper sulfate according to GOST 4165−78, a solution of 40 g/DM.
Thiourea according to GOST 6344−73, a saturated solution of 10 g of concreteras of thiourea are dissolved in 100 cmwater at room temperature with constant stirring (dissolution occurs slowly).
Ammonium radamisty, a solution of 500 g/DM.
Molybdenum metal containing at least 99.9% molybdenum.
A standard solution of molybdenum containing 1.0 mg/cmof molybdenum: 0.5 g of molybdenum metal was dissolved with heating in 4−5 cm
of hydrogen peroxide. Poured drop by drop ammonia to a bleaching solution, is heated on the warm tiles and boil for a few minutes for the destruction of hydrogen peroxide. The solution was cooled, transferred to a volumetric flask with a capacity of 500 cm
and dilute to the mark with water. Solution of molybdenum (working) containing 200 µg/cm
, is prepared by dilution of a standard solution with water five times.
(Revised edition, Edit
. N 1).
3.2. Analysis
3.2.1. A portion of the sample weighing 0.1 g was placed in a conical flask with a capacity of 100 cmand dissolved by heating on water bath within 5 cm
of hydrogen peroxide, covering the flask with a watch glass, adding, as necessary, additional hydrogen peroxide to completely dissolve the alloy. After cooling, add cautiously, in small portions, 2−3 cm
of ammonia and again heated to the bleaching solution and the end of bubbles. The solution was boiled for a few minutes for the destruction of hydrogen peroxide. The cooled solution was transferred to volumetric flask with a capacity of 250 cm
, is diluted to the mark with water and mix.
For the determination of molybdenum taken 10, 15 or 20 cmof a solution containing 1,6−1,9 mg of molybdenum, in a volumetric flask with a capacity of 50 cm
. Pour 2 cm
of tartaric acid, 14 cm
of hydrochloric acid, 1.5 cm
of a solution of sulphate of copper, 15 cm
of a solution of thiourea, stirring after each addition of the reagent. Cool the solution in cold water to 15 °C and then allowed to stand for 10 min. Pour 2 cm
of the solution Rodenstock ammonium was adjusted to the mark with water and mix thoroughly. After 10 minutes, (colored solutions are stable for 45 min), measure the optical density of the solution on photoelectrocolorimeter at
The mass of molybdenum in the calibration find gr
the Afik.
3.2.2. Construction of calibration curve
In a volumetric flask with a capacity of 50 cmis introduced from the burette 7,5; 8,0; 8,5; 9,0 and 9,5 cm
of the working solution of molybdenum, which corresponds to 1,5; 1,6; 1,7; 1,8 and 1,9 mg of molybdenum. Pour 2 cm
of tartaric acid, 14 cm
of hydrochloric acid, 1.5 cm
of a solution of sulphate of copper, 15 cm
of a solution of thiourea, stirring after each addition of the reagent. Cool the solution in cold water to 15 °C and then allowed to stand for 10 min. Pour 2 cm
of the solution Rodenstock ammonium was adjusted to the mark with water and mix thoroughly. After 10 minutes measure the optical density of solutions containing from 1.6 to 1.9 mg of molybdenum, relative to a solution containing 1.5 mg of molybdenum on photoelectrocolorimeter at
b.
3.3. Processing of the results
3.3.1. Fraction of total mass of molybdenum () in percent is calculated by the formula
where — weight of molybdenum, was found in the calibration graphics mg;
— volume of the volumetric flask, 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 molybdenum, % |
The allowable divergence, % |
| 20,0 |
1,1 |
| 25,0 |
1,4 |
| 30,0 |
1,7 |
| 35,0 |
1,9 |
| 40,0 |
2,2 |
| 45,0 |
2,2 |
| 50,0 |
2,8 |
| 55,0 | 3,0 |
(Changed edition, Rev. N 1).
4. VISUAL COLORIMETRIC METHOD FOR THE DETERMINATION OF MOLYBDENUM IN ALLOYS BASED ON NIOBIUM
The method is based on formation of colored complex compounds of molybdenum (V) thiocyanate ions in the sulfate environment and comparing the color intensity of the sample solution with a color intensity of the solutions of the scale of comparison. Molybdenum reducing agent is thiourea in the presence of copper sulphate. The influence of niobium and zirconium eliminate the introduction of fluorides.
4.1. Apparatus, reagents and solutions
Analytical scale.
Libra technical.
Tile electric.
Bath water.
Set of cylinders for colorimetrically of colorless glass with ground stoppers with a height of 25 cm and a diameter of 1.7 cm
Cup platinum with a capacity of 30 cm.
Cup a glassy carbon with a capacity of 30 cm.
Volumetric flasks with a capacity of 25, 100, and 1 DM.
Microburette with a capacity of 5 cm.
Pipette with divisions of 5 cm.
Pipettes without dividing by 5 and 10 cm.
Beakers measuring at 25 and 50 cm.
Nitric acid GOST 4461−77.
Sulfuric acid GOST 4204−77, diluted 1:2.
Hydrofluoric acid according to GOST 10484−78.
Ammonium fluoride according to GOST 4518−75, a solution of 50 g/DM.
Ammonium radamisty according to GOST 27067−86, a solution of 500 g/DM.
Copper sulfate according to GOST 4165−78, a solution of 40 g/DM.
Thiourea according to GOST 6344−73; a saturated solution of 10 g of concreteras of thiourea are dissolved in 100 cmwater at room temperature with constant stirring (dissolution occurs slowly).
Ammonium molybdate according to GOST 3765−78.
A standard solution of molybdenum (spare) containing 1 mg/cmof molybdenum: 1,840 g of ammonium molybdate dissolved in water, transferred to a volumetric flask with a capacity of 1 DM
, adjusted to the mark with water. Solution of molybdenum (working) containing 20 µg/cm
of molybdenum, prepared by dilution of a standard solution of water in
50.
4.2. Analysis
4.2.1. A portion of the sample weighing 0.1 g was placed in a platinum (glassy carbon), a Cup and dissolve by heating on a water bath for 2−3 cmhydrofluoric acid, by adding dropwise nitric acid to dissolve sample. The solution is evaporated to wet salts, avoiding drying. To the residue add 3 cm
of sulphuric acid, 5 cm
of a solution of ammonium fluoride and heated to dissolve the salts.
The expected molybdenum content of more than 0.1% the resulting solution was transferred to volumetric flask with a capacity of 25 cmand was adjusted to the mark with water.
4.2.2. For the determination of molybdenum in a volumetric flask with a capacity of 25 cmtaken 5 or 10 cm
of a solution containing 20−80 µg of molybdenum, add sulfuric acid to a total volume of 3 cm
(which is when aliquote part 5 cm
— 2.4 cm
, while aliquote part 10 cm
— 1.8 cm
) and the fluoride ammonium solution to a total volume of 5 cm
(which is when aliquote part 5 cm
— 4 cm
, and when aliquote part 10 cm
— 3 cm
). Pour 0.5 cm
of a solution of sulphate of copper, 5 cm
of a solution of thiourea, stirring after adding each reagent, added to a beaker of water to a total volume of about 22 cm
, mix. The solution was cooled to 15−20 °C (cold water) and after 15 min pour 2 cm
of the solution Rodenstock ammonium was adjusted to the mark with water, mix thoroughly. After 20 min the solution was transferred from the volumetric flask in a dry cylinder for colorimetrically and compare the color of test solution with scale solutions
comparison.
4.2.3. The expected molybdenum content less than 0.1% the resulting solution was transferred to volumetric flask with a capacity of 25 cm, washing a Cup with a little water so that the total volume of the solution in the flask was not more than 15 cm
. Pour 0.5 cm
of a solution of sulphate of copper, 5 cm
of a solution of thiourea, stirring after each addition of the reagent. The solution was cooled to 15−20 °C (cold water) and after 15 min pour 2 cm
of the solution Rodenstock ammonium was adjusted to the mark with water, mix thoroughly. After 20 min the solution was transferred from the volumetric flask in a dry cylinder for colorimetrically and compare the color of test solution with the scale of the solutions comparison.
4.2.4. Cooking scale solutions comparison
In a volumetric flask with a capacity of 25 cmis introduced from microburette 0,25; 0,5; 1,0; 1,5; 2,0; 3,0; 4,0 and 5.0 cm
of the working standard solution of molybdenum, which corresponds to 5; 10; 20; 30; 40; 60; 80 and 100 mcg of molybdenum. Pour 3 cm
of sulphuric acid, for 5 cm
of a solution of fluoride of ammonium, diluted with water to a total volume of about 22 cm
, stirring after each addition of the reagent. The solutions were cooled to 15−20 °C (cold water) and after 15 min pour 2 cm
of the solution Rodenstock ammonium was adjusted to the mark with water, mix thoroughly. After 20 min the solutions were transferred from the volumetric flasks in a dry cylinders for colorimetrically.
4.3. Processing of the results
4.3.1. Fraction of total mass of molybdenum () in percent (mass fraction of molybdenum greater than 0.1%) is calculated according to the formula
where is the mass of molybdenum found on a scale of solutions comparison, the mcg;
— capacity volumetric flasks, cm
;
— aliquotes volume of the solution taken for the determining, cm
;
— the weight of the portion of the sample,
4.3.2. Fraction of total mass of molybdenum () in percent (mass fraction of molybdenum of less than 0.1%) is calculated according to the formula
where is the mass of molybdenum found on a scale of solutions comparison, the mcg;
— the weight of the portion of the sample,
4.3.3. 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.5.
Table 5
| Mass fraction of molybdenum, % |
The allowable divergence, % |
5·10 |
4·10 |
1·10 |
0,8·10 |
2·10 |
1·10 |
5·10 |
2·10 |
1·10 |
0,3·10 |
2·10 |
0,6·10 |
5·10 |
1,5·10 |
Sec. 4. (Added, Rev. N 1).
