GOST 26473.4-85

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  ГОСТ 26473.4-85

GOST 26473.4−85 Alloys and alloys based on vanadium. Methods for determination of silicon (with Change No. 1)

GOST 26473.4−85

Group B59

STATE STANDARD OF THE USSR

ALLOYS AND MASTER ALLOYS BASED ON VANADIUM

Methods for determination of silicon

Vanadium base alloys and alloying elements. Methods for determination of silicon

AXTU 1709

Valid from 01.07.86
to 01.07.91*
_______________________________
* Expiration removed
by the decree of Gosstandart of the USSR from 14.05.91 N 679
(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

Westminsterco 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 14.05.91 N 676 from 01.01.92

Change No. 1 made by the manufacturer of the database in the text IUS N 2, 1990


This standard specifies the photometric and gravimetric methods for determination of silicon (0.1 to 1%) in alloys and master alloys based on vanadium, the contents of related components which are shown in table.1.

Table 1

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 26473.0−85.

2. PHOTOMETRIC METHOD FOR DETERMINATION OF SILICON

The method is based on the Stripping of silicon in the form of fluoride, the formation of a blue reduced forms of kremneftoristogo heterophilically with subsequent fotometricheskie the color of the solution.

2.1. Apparatus, reagents and solutions

Type photoelectrocolorimeter FEK-56.

Analytical scale.

Libra technical.

A muffle furnace with a thermostat that ensures the temperature to 900−950 °C.

Drying Cabinet, providing a temperature of 100−120 °C.

Cup platinum.

PTFE Cup with screw caps (PTFE-4 according to GOST 10007−80) (drawing).

1 — Cup PTFE; 2 — screw cap

Pipettes PTFE or polyethylene with a capacity of 1 cm.

Plastic cans with a capacity of 100 cmand 1 DM.

Microburette with a capacity of 5 cmwith a scale division of 0.02 cm.

Volumetric flasks with a capacity of 100 and 1000 cm.

The acid chloride.

Nitric acid GOST 4461−77 diluted 1:1, and the solution concentration of 2 mol/DM.

Sulfuric acid GOST 4204−77, solution concentration of 16 mol/DM.

Boric acid according to GOST 9656−75, saturated solution.

Ascorbic acid, food, solution concentration of 10 g/DM.

Ammonium molybdate according to GOST 3765−78, solution concentration of 50 g/DM(prepared on the day of use).

Potassium carbonate — sodium carbonate according to GOST 4332−76.

Sodium hydroxide according to GOST 4328−77, alcohol solution with concentration of 40 g/DMand an aqueous solution concentration of 200 g/DM.

The technical rectified ethyl alcohol GOST 18300−87.

Silicon dioxide according to GOST 9428−73.

Standard solution of silica containing 0.1 mg/cm(100 g/cm) silicon: 0,2139 g of silica placed in a platinum Cup, add 3−4 g of potassium carbonate of sodium, fused in a muffle furnace at 900−950 °C until a clear melt. The melt was cooled to room temperature, leached with water, transferred into a measuring flask with volume capacity of 1000 cmand was adjusted to the mark with water. The solution was stored in a plastic container.

(Changed edition, Rev. N 1).

2.2. Preparation for assay

2.2.1. In the lid of the Teflon Cup is placed 1 cmalcohol solution of sodium hydroxide, distributing it evenly. The lid is placed in a cold oven, heat the oven to 50−60 °C and kept the lid at this temperature for 5−10 min.

2.2.2. For vanadium alloys, or alloys of the vanadium-molybdenum-titanium-carbon, vanadium-aluminum-manganese-titanium-carbon, vanadium-aluminium-molybdenum-titanium-carbon, vanadium-zirconium-niobium-carbon; the weight of the sample weight of 0.1 g (with a mass fraction of silicon of 0.025−0.4%) or 0.04 g (at a mass fraction of silicon of 0.4−1%) was placed in Teflon Cup, pour 3 cmof nitric acid, diluted 1:1, 2, seehydrofluoric acid, cooling a Cup of cold water until the termination of allocation of oxides of nitrogen, poured 11 cmof perchloric acid, mix and immediately cover the Cup lid with sodium hydroxide.

2.2.3. For vanadium alloys, or alloys of the vanadium-Zirconia-carbon, vanadium-zirconium-aluminum, vanadium-molybdenum-chromium-aluminum, vanadium-aluminum-molybdenum-chromium-iron weighed test portion with a mass of 0.05−0.1 g (depending on the silicon content) was placed in Teflon Cup, pour 12 cmof perchloric acid, of 2 cmwater and 2 cmhydrofluoric acid, stir, and immediately cover the Cup lid with sodium hydroxide.

2.2.4. For vanadium alloys vanadium-aluminum, vanadium-aluminum-carbon, vanadium-aluminum-nitrogen, vanadium-aluminum-titanium-carbon vanadium-manganese, vanadium-boron-aluminum suspension of the sample mass 0.05−0.1 g (depending on the silicon content) was placed in Teflon Cup, pour 3 cmof nitric acid, diluted 1:1, 12 cmof perchloric acid and 1 cmhydrofluoric acid, cooling a Cup of cold water until the termination of allocation of oxides of nitrogen, stirred and close the Cup lid with sodium hydroxide.

2.3. Analysis

2.3.1. A Cup, closed the lid, kept in a desiccator at 110−120 °C for 2 h, then removed from oven, carefully remove the cover not to touch the acid solution with sodium hydroxide, and transferred the contents of the cover in a plastic jar with 25 cmsolution of boric acid. Then in a Cup add 1 cmof an aqueous solution of sodium hydroxide, 4 cmnitric acid concentration of 2 mol/DM, 20 cmwater, 5 cmof a solution of molybdate of ammonium. After 15 min. poured 25 cmof sulfuric acid solution, 10 cmof a solution of ascorbic acid. After 25−30 min the resulting solution was transferred to volumetric flask with a capacity of 100 cmand adjusted to the mark with water. Optical density of the solution is measured on a photoelectrocolorimeter using a filter with maximum transmittance at a wavelength of ~630 nm and cuvette thickness of the light absorbing layer 10 mm relative to the water.

Before analyzing a series of samples through all stages of the analysis spend control experience (for contamination control reagents). The value of the optical density of the solution in the reference experiment shall not exceed 0,03, otherwise necessary to change the reagents. The value of optical density in the reference experiment is subtracted from the value of the optical density of the analyzed solution. A lot of silicon find the calibration schedule according to calculated od values with good shielding qualit

ti.

2.3.2. Construction of calibration curve

In plastic jars with a capacity of 100 cmis injected from microburette 0,25; 0,5; 0,75; 1,0; 1,5; 2,0; 3,0; 4,0 and 5.0 cmstandard solution silicon, which corresponds to 25, 50, 75, 100, 150, 200, 300, 400 and 500 micrograms of silicon. 25 cm pour theboric acid solution and then do as stated in claim 2.3.1.

On the found values of optical density and corresponding mass of silicon to build the calibration graph.

2.4. Processing of the results

2.4.1. Mass fraction of silicon () in percent is calculated by the formula

,

where is the mass of silicon was found in the calibration schedule, mcg;

 — the weight of the portion of the sample,

2.4.2. The values of permissible differences given in table.2.

Table 2

(Changed edition, Rev. N 1).

3. GRAVIMETRIC METHOD FOR DETERMINATION OF SILICON

The method is based on the isolation of silicon in the form silicic acid by evaporation of the initial solution to the appearance of sulphuric acid fumes, transfer of silicic acid by calcination at 1000−1100 °C in silicon dioxide, the Stripping of silicon in the form of silicon tetrafluoride treatment of silicon dioxide hydrofluoric and sulphuric acids and finding the mass of silicon to change the weight allocated to the sediment.

3.1. Apparatus, reagents and solutions

Analytical scale.

Libra technical.

Muffle furnace with thermostat providing temperatures up to 1100 °C.

Tile electric.

Glasses chemical glass with a capacity of 400 cm.

Volumetric flasks with a capacity of 250 cm.

Measuring beakers with a capacity of 50 cm.

Funnels, glass, conical with a diameter of 30 mm.

Platinum crucibles with a capacity of 30 cm.

Plastic pipette, graduated to 2 cm.

Desiccator with calcium chloride.

Filters obestochennye paper «blue tape» or «white ribbon».

Sulfuric acid GOST 4204−77, diluted 1:1.

Nitric acid GOST 4461−77 diluted 1:1.

Hydrofluoric acid according to GOST 10484−78.

(Changed edition, Rev. N 1).

3.2. Analysis

A portion of the sample weighing 0.5−1 g (depending on silicon content) were placed in a glass with a capacity of 400 cm, 30 cm pournitric acid, diluted 1:1, heated to dissolve the sample, poured 20 cmof sulphuric acid diluted 1:1, continuing the heating to release of sulfuric acid vapors for 1−2 minutes the cooled solution on the walls of the flask poured 100−150 cmof water and heated to dissolve the salts.

Solution and the precipitate of silicic acid is filtered through the filter «white ribbon» or «blue ribbon», washed the precipitate several times with hot water. The filtrate and the washings collected in a volumetric flask with a capacity of 250 cm, cooled, adjusted to the mark with water (stock solution), and use (if necessary) for determination of chromium GOST 26473.10−85, iron according to GOST 26473.3−85, zirconium and aluminum according to GOST 26473.11−85, molybdenum GOST 26473.6−85, titanium GOST 26473.8−85.

The filter with precipitate was placed in a platinum crucible, gently dried, incinerated, avoiding the fire, calcined in a muffle furnace for 40 min at 1000 °C, then cooled in a desiccator and weighed. The calcination and weighing is repeated until the constant weight.

Suspended sediment moistened with 2−3 drops of water poured 5−6 drops of concentrated sulfuric acid, 2cmhydrofluoric acid. The crucible is placed on a hot plate with a closed spiral and gently evaporated with moderate heat to stop the allocation of sulphuric acid fumes. The dry residue is calcined for 20 min at 1000 °C in a muffle furnace, cooled in a desiccator, weigh. The calcination and weighing is repeated until obtaining constant weight.

Bulk silicon is calculated from the difference between the first and second weighing, prior to processing the insoluble residue acids (hydrofluoric and sulfuric) and after it.

Simultaneously with the analysis of a series of samples through all stages of the analysis spend control experience (for contamination control reagents).

3.3. Processing of the results

3.3.1. Mass fraction of silicon () in percent is calculated by the formula

,

where is the mass of the crucible with the precipitate of silicon dioxide prior to treatment with acid, g;

 — weight of crucible with residue after treatment with acids, g;

 — the weight of the portion of the sample, g;

0,4674 — the ratio of silicon dioxide to silicon.

The final result of find as the difference between the mass fraction of silicon in the sample and the mass fraction of silicon in a control experiment.

3.3.2. The values of permissible differences are listed in table.3.

Table 3

(Changed edition, Rev. N 1).