GOST 26473.6-85
GOST 26473.6−85 Alloys and alloys based on vanadium. Method for the determination of molybdenum (with Change No. 1)
GOST 26473.6−85
Group B59
STATE STANDARD OF THE USSR
ALLOYS AND MASTER ALLOYS BASED ON VANADIUM
Method for the determination of molybdenum
Vanadium base alloys and alloying elements. Method for determination of molybdenum
AXTU 1709
Valid from 01.07.86
to 01.07.91*
_______________________________
* Expiration removed
by the decree of Gosstandart of the USSR from
(IUS N 8, 1991). — Note the manufacturer’s database.
DEVELOPED by the Ministry of nonferrous metallurgy of the USSR
PERFORMERS
Yu. A. Karpov, E. G. Nembrini, V. G., Miscreants, V. V. Nedler, V. M. Mikhailov, L. G. Agapova, G. N. Andrianov, A. V. Antonov, V. D. Dozen, M. A. Desyatkova, T. I. Kirillova, L. I. Kirsanov, I. E. Korepin, V. A. Orlova, N. Rasnitsyn, N. Suvorova, N. L. Tomasev, M. W. Schmidt, L. N. Filimonov
INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
Member Of The Board Of A. P. Snurnikov
APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on standards of 25 March 1985, N 751
The Change N 1, approved and put into effect by the Decree of the USSR State Committee on management of quality and standards from
Change No. 1 made by the manufacturer of the database in the text IUS N 2, 1990
This standard sets the photometric method for the determination of molybdenum (from 10 to 35%) in alloys and master alloys based on vanadium, the contents of related components which are shown in table.1.
Table 1
| The accompanying component |
Mass fraction, %, not more |
| Aluminium |
50 |
| Iron |
10 |
| Silicon |
1 |
| Manganese |
2,5 |
| Titan |
25 |
| Carbon |
5 |
| Chrome |
40 |
The method is based on the formation in the sulfate medium colored complex compound of pentavalent molybdenum with thiocyanate ions and fotomaterialy the color of the solution.
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 26473.0−85.
2. APPARATUS, REAGENTS AND SOLUTIONS
Type photoelectrocolorimeter FEK-56.
Analytical scale.
Libra technical.
Muffle furnace with thermostat, providing a temperature of 700−800 °C.
Tile electric.
Cup platinum.
The chemical glasses with a capacity of 200, 250 cm.
Funnels, glass, conical.
Volumetric flasks with a capacity of 100, 200 cm, 1 DM
.
Flasks with polyethylene stopper with a capacity of 100 cm.
Desiccator with calcium chloride.
Crucibles porcelain.
Microburette with a capacity of 10 cmwith a scale division of 0.02 cm
.
Pipettes with a capacity of 2 and 5 cmwith divisions.
Pipettes with a capacity of 25 cmwith no divisions.
Measuring beakers with a capacity of 25 and 100 cm.
Obestochennye the filter paper of «blue ribbon».
Methyl orange (indicator), an aqueous solution of concentration 1 g/DM.
Sulfuric acid GOST 4204−77 and diluted 1:3.
Potassium preservatory according to GOST 7172−76.
Copper (II) sulfate 5-water according to GOST 4165−78, solution concentration of 10 g/DM.
Thiourea according to GOST 6344−73, solution concentration 100 g/DM.
Potassium rodanistye according to GOST 4139−75, a solution of concentration 500 g/DM.
Ammonium molybdate according to GOST 3765−78.
Molybdenum metal containing at least 99.9% molybdenum.
Hydrogen peroxide according to GOST 10929−76.
Ammonia water according to GOST 3760−79.
Ammonium acetate according to GOST 3117−78, solutions with concentrations of 500 and 30 g/DM.
Hydrochloric acid by the GOST 3118−77, diluted 1:1.
Lead acetate according to GOST 1027−67, solution concentration of 20 g/DM.
Pharmaceutical tannin (GDR), a solution of concentration 10 g/DMacetic acid, diluted 5:95, freshly prepared.
Acetic acid GOST 61−75, concentrated and diluted with 5:95.
Allowed preparation of standard solutions using different starting materials: molybdenum metal (series a) and ammonium molybdate (series B).
Series A
A standard solution of molybdenum containing 1 mg/cmof molybdenum (solution a
): 0.1 g of molybdenum metal is placed in a conical flask with a capacity of 250 cm
and dissolved by heating in 5−10 cm
of hydrogen peroxide. Poured drop by drop ammonia to a bleaching solution, heated and boiled for a few minutes for the destruction of hydrogen peroxide; the solution was then cooled, transferred to a volumetric flask with a capacity of 100 cm
and dilute to the mark with water.
A standard solution of molybdenum containing 0.05 mg/cm(50 µg/cm
) molybdenum (solution A
), prepared on the day of use by diluting solution A
with water to 20 times. The solution was stored in a plastic container.
Series B
A standard solution of molybdenum containing about 1 mg/cmof molybdenum (solution B
): 1.84 g ammonium molybdate was placed in a beaker with a capacity of 200 cm
and dissolved in 50−70 cm
of water, heated to 70−80 °C. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 1 DM
, dilute to the mark with water. The solution was stored in a plastic container.
Accurate 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 (B
), 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 and as long as a drop of test solution is deposition of molybdenum will not form with a solution of tannin, applied on filter paper: a yellow spot. In this case, the deposition of molybdenum is considered complete. The contents of the glass pour another 5 cm
of a solution of acetate of lead. The volume of solution of acetate of lead, used for the deposition of molybdenum in cubic centimeters, record. The contents of the three remaining glasses heated to boiling and poured into them a fixed number of cubic centimeters 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 was washed 4−5 times with hot ammonium acetate solution with a concentration of 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, cool in desiccator, weigh. The calcination and weighing is repeated until obtaining constant weight.
Mass concentration () of a standard solution of molybdenum (solution B
), expressed in mg/cm
of molybdenum, 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.
A standard solution of molybdenum containing 0.05 mg/cm(50 µg/cm
) molybdenum (solution B
), prepared on the day of use by diluting the solution B
with water 20 times. The solution was stored in a plastic container.
(Changed edition, Rev. N 1).
3. PREPARATION FOR ASSAY
3.1. A portion of the sample weight of 0.1 g (for alloy composition the vanadium-chromium-molybdenum-aluminium-iron, vanadium-aluminium-molybdenum-titanium-carbon) is placed in a platinum Cup, poured 30−35 cmof sulphuric acid, diluted 1:3, and 5 cm
of nitric acid, heated to complete dissolution of the sample. If the solution in the Cup is evaporated to 15−20 cm
, and the linkage is not dissolved, the contents of the Cup is cooled to 30−40 °C, wash with water the walls of the Cup, pour 3−5 cm
of nitric acid and again heat. The operation of adding nitric acid is repeated several times until complete dissolution of the sample test. The contents of the Cup is evaporated to release vapors of sulphuric anhydride, cooled to room temperature, poured water, heated until complete dissolution of salts, transferred to a volumetric flask with a capacity of 100 cm
, cooled and adjusted to the mark with water.
3.2. A portion of the sample weight of 0.1 g (for alloy composition the vanadium-chrome-molybdenum-aluminum) is placed in a platinum Cup, add 2 g of potassium peacemaking and 2−3 drops of concentrated sulphuric acid, melted on the stove, placed in the muffle alloy at 700−800 °C to obtain a transparent melt and cooled to room temperature. M leach 30 cmof sulphuric acid, diluted 1:3 when heated to 60−70 °C, cooled to room temperature, transferred to a volumetric flask with a capacity of 200 cm
and was adjusted to the mark with water.
4. ANALYSIS
4.1. For the determination of molybdenum in a volumetric flask with a capacity of 100 cmpipetted 1−2 cm
of the sample solution prepared according to claim 3.1 and 3.2, or 2 cm
core solution obtained according to GOST 26473.3−85 and diluted with water to 4 times, containing 200−400 micrograms of molybdenum, poured 35 cm
of sulfuric acid solution, diluted 1:3, 1 cm
of a solution of sulphate of copper, 5 cm
of a solution of thiourea. After 10 min the solution was poured 2.5 cm
of a solution of potassium Rodenstock and bring to mark with water, allowed to stand for 20 min, Measure the optical density of the solution on the photoelectrocolorimeter using a filter with maximum transmittance at a wavelength of 430 nm and cuvette thickness of the light absorbing layer 10 mm relative to the water.
A lot of find molybdenum in the calibration schedule.
(Changed edition, Rev. N 1)
.
4.2. Construction of calibration curve
In a volumetric flask with a capacity of 100 cmis injected from microburette 1,0; 2,0; 3,0; 4,0; 5,0; 6,0; 7,0; 8,0; 9,0 and 10.0 cm
of the working standard solution of molybdenum, which corresponds to 50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 mcg of molybdenum. Poured in 35 cm
of sulfuric acid solution and then do as described in claim 4.1.
On the found values of optical density and corresponding masses of molybdenum to build the calibration graph.
5. PROCESSING OF THE RESULTS
5.1. Fraction of total mass of molybdenum () in percent is calculated by the formula
where — weight of molybdenum, was found in the calibration schedule, mcg;
— capacity volumetric flasks, cm
;
— aliquotes volume of the solution taken for the determining, cm
;
— the weight of the portion of the sample,
4.2. The values of permissible differences given in table.2.
Table 2
| Mass fraction of molybdenum, % |
Allowable difference, % |
| 10,0 |
0,7 |
| 15,0 |
1 |
| 20,0 |
1,4 |
| 25,0 |
1,7 |
| 30,0 |
2,1 |
| 35,0 |
2,4 |
(Changed edition, Rev. N 1).
