GOST 25278.13-87

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  ГОСТ 25278.13-87

GOST 25278.13−87 Alloys and alloys of rare metals. Methods for determination of tungsten (Change No. 1)

GOST 25278.13−87

Group B59

STATE STANDARD OF THE USSR

ALLOYS AND ALLOYS OF RARE METALS

Methods for determination of tungsten

Alloys and foundry alloys of rare metals. Methods for determination of tungsten

AXTU 1709

Valid from 01.07.88
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

E. G. Nembrini, G. N. Andrianova, T. M. Malyutina, L. G. Obruchkova, N. Rasnitsyn, E. I., Samsonova, Z. I. Shishkin, L. V. Ushakova

2. APPROVED AND promulgated by the Decree of the State Committee USSR on standards on 29 October 1987 N 4091

3. The period of examination — 1993

The frequency of inspection — 5 years

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

The Change N 1, approved and introduced with effect from 01.07.98 by the resolution of Gosstandart of Russia dated 06.04.98 No. 107

Change No. 1 made by the manufacturer of the database in the text IUS N 6, 1998


This standard specifies three methods for determination of tungsten:

photometric (3 to 15%) for alloys (alloys) on the basis of niobium (components: molybdenum is not more than 10%, zirconium not more than 2%, tantalum, less than 10%) and (from 2 to 20%) for alloys based on tantalum, and hafnium (components: rhenium is not more than 1.5% and niobium not more than 10%);

differential photometric (30 to 60%) in binary alloys niobium-tungsten;

visual-colorimetric (from 5·10to 2·10%) for alloys based on niobium (components: Zirconia is not more than 1.5%, molybdenum not more than 0.5%, tantalum, less than 0.5%, titanium not more than 0.5%).

1. GENERAL REQUIREMENTS

1. General requirements for methods of analysis and security requirements — according to GOST 26473.0−85.

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF TUNGSTEN IN ALLOYS BASED ON NIOBIUM

The method is based on formation of colored complex compounds of tungsten (V) thiocyanate ions, in the oxalate-hydrochloric acid (4 mol/lfor Hcl) solution in the presence of a reducing agent, trichloride titanium. Hydrolysis of niobium to prevent the introduction of oxalate; zirconium and molybdenum definition, do not interfere.

Mass fraction of tungsten set by comparison with a standard sample of composition that is analyzed concurrently with the sample.

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.

Volumetric flasks with a capacity of 50 and 250 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.

Sulfuric acid according to GOST 4204−77.

Hydrochloric acid by the GOST 3118−77 and diluted 2:1 and 1:1.

Potassium preservatory according to GOST 7172−76.

Ammonium oxalate according to GOST 5712−78, a solution of 40 g/DM.

Potassium rodanistye according to GOST 4139−75, a solution of 500 g/DM.

Titanium trichloride, a solution of 150 g/DM.

The titanium metal containing not less than 99.9% titanium in the form of small chips.

Industry standard sample of alloy 5 VIC CCA 48−4-1−90 (1−78).

The solution trichloride titanium 15 g/DM; prepared in one of two ways.

Method 1: 1 cmof solution trichloride titanium 150 g/DMdiluted with 9 cmof concentrated hydrochloric acid.

Method 2: 0.5 g of powder of titanium metal is dissolved by heating in hydrochloric acid, diluted 1:1, the resulting solution was adjusted to 50 cmhydrochloric acid diluted 1:1.

Solution store in a dark bottle; usable 3−4

days.

(Changed edition, Rev. N 1).

2.2. Analysis

2.2.1. A portion of the sample weighing 0.1 g was placed in a quartz crucible, add 3−4 g of persulfate potassium, a few drops of concentrated sulphuric acid and fused in a muffle at a temperature of 700−900 °C until a clear melt (if the melting is not completely, the melt is cooled, add a few drops of concentrated sulfuric acid and repeat the procedure of fusing to produce a clear float). The cooled melt is dissolved by heating in 150 cmof a solution of ammonium oxalate. The resulting solution was transferred to volumetric flask with a capacity of 250 cm, was adjusted to the mark with a solution of ammonium oxalate, cooled and stirred. The solution can be used for determination of molybdenum GOST 25278.6−82.

2.2.2. For the determination of tungsten in a volumetric flask with a capacity of 50 cmis taken aliquot part of the solution (2.5 or 10 cm), containing 50−250 µg of tungsten, diluted (if necessary) up to 10 cmwith a solution of ammonium oxalate, pour 2.5 cmof a solution of potassium Rodenstock, 25 cmhydrochloric acid, diluted 2:1, and 0.5 cmof a solution of titanium trichloride, stirring after adding each reagent, and introducing them in sequence with an interval of 2−3 min, adjusted to the mark with water, mix. After 20 minutes (colored solutions are stable for 4 h), measure the optical density of the solution on photoelectrocolorimeter at 400 nm in a cuvette with the thickness of the light absorbing layer 20 mm relative to the zero solution containing all reagents except the tungsten

.

2.2.3. Simultaneously with the series of samples analyzed a standard sample of the composition. In this respect the equality of the mass of the analyzed sample and the standard sample dilution solution. Aliquote parts of a solution of a standard sample and a test sample should be selected so that the mass of tungsten in them was about equal.

2.3. Processing of the results

2.3.1. Mass fraction of tungsten () in percent is calculated by the formula

,

where  — mass fraction of tungsten in the standard sample composition OSO N 1−78, equal to 4,94%;

 — optical density of the solution of the sample;

 — optical density of the solution of a standard sample of the composition.

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

3. DIFFERENTIAL PHOTOMETRIC METHOD FOR THE DETERMINATION OF TUNGSTEN IN ALLOYS BASED ON NIOBIUM

The method is based on formation of colored complex compounds of tungsten (V) thiocyanate ions, in the oxalate-hydrochloric acid (4 mol/lfor Hcl) solution in the presence of a reducing agent is titanium trichloride. The optical density of the solutions is measured relative to the comparison solution containing 2.0 mg of tungsten. Hydrolysis of niobium to prevent the introduction of oxalate.

3.1. Apparatus, reagents and solutions

Spectrophotometer type SF-26 or Specol-10 with a measuring attachment EC-1 or similar type.

Tile electric.

Analytical scale.

Libra technical.

The quartz glasses with a capacity of 30−40 cm(diameter 30 mm).

Glasses chemical glass with a capacity of 50 cm.

Watch-glasses with a diameter of 40 mm.

Pipettes with graduation marks at 5 and 10 cm.

Volumetric flasks with a capacity of 50, 100 and 500 cm.

Sulfuric acid according to GOST 4204−77.

Hydrochloric acid by the GOST 3118−77 and diluted 2:1.

Ammonium sulfate according to GOST 3769−78.

Ammonium oxalate according to GOST 5712−78, a solution of 20 g/DM.

Ammonium radamisty according to GOST 27067−86, a solution of 500 g/DM.

The titanium metal containing not less than 99.9% titanium in the form of small chips.

The solution trichloride titanium 150 g/DM(alternate), prepared as follows: 0.5 g of titanium metal is placed in a glass beaker with a capacity of 50 cmand dissolved by heating in 10 cmof concentrated hydrochloric acid, covered with a glass watch glass. The initial volume (10 cm) always support the addition of concentrated hydrochloric acid. The resulting solution was stored in a dark bottle with a glass stopper is not more than 3 days.

The solution trichloride titanium 15 g/DM(worker); prepared on the day of use by diluting 10 times a backup solution previously boiled and cooled hydrochloric acid.

Tungsten metal containing at least 99.9% of tungsten, in the form of small chips.

A standard solution of tungsten containing 0.5 mg/cmtungsten: 0.1 g metal tungsten is placed in a quartz glass with a capacity of 30−40 cmand dissolved with strong heating in 4 cmof concentrated sulfuric acid with addition of 1 g of ammonium sulfate, covered with a glass watch glass. After complete dissolution of tungsten in the melt is cooled, add 4 g of ammonium oxalate. The hour glass is washed with 15−20 cmof water, collecting the wash in the same Cup. The contents of the Cup stirred and heated until complete dissolution of salts. The clear solution was transferred to volumetric flask with a capacity of 200 cm, cooled, adjusted to me

tki water.

(Changed edition, Rev. N 1).

3.2. Analysis

3.2.1. A portion of the sample weighing 0.1 g was placed in a quartz glass with a capacity of 30−40 cmand dissolved with strong heating in 2 cmof concentrated sulfuric acid with addition of 0.5 g of ammonium sulfate, covered with a glass watch glass. After complete dissolution of the sample m cool, add 2 g of ammonium oxalate. The hour glass is washed with 15−20 cmof water, collecting the wash in the same Cup. The contents of the Cup stirred and heated until complete dissolution of salts. The clear solution was transferred to volumetric flask with a capacity of 100 cm, cooled, adjusted to the mark with water.

3.2.2. For the determination of tungsten in a volumetric flask with a capacity of 50 cmis taken aliquot part (4−8 cm), containing the 2.1−2.5 mg of tungsten, diluted (if necessary) up to 8 cmwith a solution of ammonium oxalate 20 g/DM, poured 25 cmhydrochloric acid, diluted 2:1, 2.5 cmmortar Rodenstock ammonium, 1 cmof working solution of titanium trichloride (adding it drop by drop while stirring), adjusted to the mark with water. After 25−30 min (colored solutions are stable for 4 h) measure the absorbance on the spectrophotometer at 410 nm in a cuvette with the thickness of the light absorbing layer 10 mm relative to the comparison solution containing 2.0 mg of tungsten: in a volumetric flask with a capacity of 50 cmis taken 4 cmstandard solution tungsten, pour 4 cmof solution of ammonium oxalate concentration of 20 g/DM, 25 cmhydrochloric acid, diluted 2:1, 2.5 cmmortar Rodenstock ammonium 1 cmof working solution of titanium trichloride (adding it drop by drop while stirring), adjusted to the mark with water. After 25−30 min the solution is used as solution comparison.

A lot of tungsten find for the calibration

graphics.

3.2.3. Construction of calibration curve

In a volumetric flask with a capacity of 50 cmis injected from microburette 4,0; 4,2; 4,4; 4,6; 4,8 and 5,0 cmstandard solution tungsten, which corresponds to 2,0; 2,1; 2,2; 2,3; 2,4 and 2,5 mg of tungsten. Pour up to 8 cmof a solution of ammonium oxalate, 25 cmhydrochloric acid, diluted 2:1, 2.5 cmmortar Rodenstock ammonium, 1 cmof working solution of titanium trichloride (adding it drop by drop while stirring), adjusted to the mark with water. 25−30 min measure the optical density of solutions containing 2.1 to 2.5 mg of tungsten, relative to a solution containing 2.0 mg of tungsten on the spectrophotometer at 410 nm in a cuvette with the thickness of the light absorbing layer 10 mm.

According to the obtained results build a calibration curve in the coordinates: the optical density is the mass of the tungsten. Separate test points of the graph along with the analysis of samples

.

3.3. Processing of the results

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

,

where is the mass of tungsten 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

4. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF TUNGSTEN IN ALLOYS OF TANTALUM AND HAFNIUM

The method is based on formation of colored complex compounds of tungsten (V) thiocyanate ions, in the oxalate-hydrochloric acid (4 mol/lby hydrochloric acid) solution. The hydrolysis of tantalum and niobium prevent the introduction of oxalates; hafnium definition, does not prevent.

4.1. Apparatus, reagents and solutions

Photoelectrocolorimeter FEK-50 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 and 250 cm.

Microburette with a capacity of 5 cm.

Pipettes with graduations of 2.5 and 10 cm.

Pipettes with no graduations of 5 and 10 cm.

Measuring beakers with a capacity of 50 and 100 cm.

Sulfuric acid according to GOST 4204−77.

Hydrochloric acid by the GOST 3118−77 and diluted 2:1 and 1:1.

Potassium preservatory according to GOST 7172−76.

Ammonium oxalate according to GOST 5712−78, solutions of 40 and 100 g/DM.

Potassium rodanistye according to GOST 4139−75, a solution of 500 g/DM.

Titanium trichloride, a solution of 150 g/DM.

The titanium metal containing not less than 99.9% titanium in the form of small chips.

The solution trichloride titanium 15 g/DM; prepared in one of two ways:

Method 1: 1 cmof solution trichloride titanium concentration of 150 g/DMdiluted with 9 cmof concentrated hydrochloric acid.

Method 2: 0.5 g of powder of titanium metal is dissolved by heating in hydrochloric acid, diluted 1:1, the resulting solution was adjusted to 50 cmhydrochloric acid diluted 1:1.

Solution store in a dark bottle: usable 3−4 days.

Sodium volframovich according to GOST 18289−78.

Standard solution tungsten (spare) containing 1 mg/cmtungsten: 1,794 volframovich g of sodium is dissolved in water, the solution transferred to a volumetric flask with a capacity of 1 DMand dilute to the mark with water. The solution was stored in a plastic container.

A solution of tungsten (work) containing 50 mg/cmtungsten, is prepared by dilution of a standard solution with water

20.

(Changed edition, Rev. N 1).

4.2. Analysis

4.2.1. A portion of the sample weighing 0.1 g was placed in a quartz crucible, add 3−5 g of persulfate potassium, a few drops of concentrated sulphuric acid and fused in a muffle at a temperature of 700−900 °C to produce a clear float. If the fusion is not completely, the melt is cooled, add a few drops of concentrated sulfuric acid and repeat the procedure of fusing to produce a clear float. The cooled melt was dissolved with heating and thorough stirring in a 100 cmhot solution of ammonium oxalate 100 g/DM(in the analysis of the alloy based on tantalum) or 100 cmhot solution of ammonium oxalate 40 g/DM(in the analysis of the alloy based on hafnium). After cooling, the solution was transferred to volumetric flask with a capacity of 250 cmand was adjusted to the mark with water (in the analysis of the alloy based on tantalum) or a solution of ammonium oxalate 40 g/DM(in the analysis of the alloy based on hafnium) and stirred. The solution can be Used for determination of molybdenum GOST 25278.6−82.

4.2.2. For the determination of tungsten in a volumetric flask with a capacity of 50 cmis taken aliquot part of the solution (2.5 or 10 cm), containing 50−250 µg of tungsten, diluted (if necessary) up to 10 cmwith a solution of ammonium oxalate 40 g/DM; pour 2.5 cmof a solution of ammonium Rodenstock, 25 cmhydrochloric acid, diluted 2:1, and 0.5 cmof a solution of trichloride titanium (dropwise!). After each addition of the reagent the solution was stirred. The reagents are injected in sequence with an interval of 2−3 min, adjusted to the mark with water, mix. After 20 minutes (colored solutions are stable for 4 h), measure the optical density of the solution on photoelectrocolorimeter at 400 nm in a cuvette with the thickness of the light absorbing layer 20 mm relative to the zero solution containing all reagents except tungsten.

A lot of tungsten find for the calibration graph

.

4.2.3. Construction of calibration curve

In a volumetric flask with a capacity of 50 cmpoured from microburette 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard working solution of tungsten, which corresponds to 50; 100; 150; 200 and 250 micrograms of tungsten. Pour 10 cmof a solution of ammonium oxalate concentration of 40 g/DM, 2.5 cmmortar Rodenstock ammonium 25 cmhydrochloric acid, diluted 2:1, 0.5 cmof a solution of trichloride titanium (dropwise!). After each addition of the reagent the solution was stirred. The reagents are injected in sequence with an interval of 2−3 min, adjusted to the mark with water and mix. In one of the flasks poured all reagents with the exception of tungsten (zero solution).

After 20 minutes (colored solutions are stable for 4 h) measure the optical density of solutions on the photoelectrocolorimeter at 400 nm in a cuvette with the thickness of the light absorbing layer of 20 mm in relation to the zero solution.

According to the obtained results build a calibration curve in the coordinates of the optical density — the mass of tungsten. Separate test points of the graph along with the analysis of Pro

b.

4.3. Processing of the results

4.3.1. Mass fraction of tungsten () in percent is calculated by the formula

,

where is the mass of tungsten 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,

4.3.2. 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.3.

Table 3

5. VISUAL COLORIMETRIC METHOD FOR THE DETERMINATION OF TUNGSTEN IN ALLOYS BASED ON NIOBIUM

The method is based on formation of colored complex compounds of tungsten (V) thiocyanate ions in hydrochloric acid (3 mol/DM) environment in the presence of a reducing agent is titanium trichloride and comparing the color intensity of the sample solution with a color intensity of the solutions of the scale of comparison. The influence of niobium and titanium can be eliminated by introduction of fluorides and oxalates. Zirconium and molybdenum definition, do not interfere.

5.1. 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 cm.

Microburette with a capacity of 5 cm.

Pipette with divisions of 5 cm.

Pipettes without dividing by 5 and 10 cm.

Beakers measuring 10 and 25 cm.

Glasses glass with a capacity of 25 and 100 cm.

Watch glasses with a diameter of 40 mm.

Nitric acid GOST 4461−77.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1.

Hydrofluoric acid according to GOST 10484−78.

Ammonium fluoride according to GOST 4518−75, a solution of 50 g/DM.

Ammonium oxalate according to GOST 5712−78.

Ammonium radamisty according to GOST 27067−86, a solution of 500 g/DM.

Sodium hydroxide according to GOST 4328−77, a solution of 100 g/DM.

Tungsten (VI) oxide.

The titanium metal sponge by GOST 17746−79.

A solution of trichloride titanium (spare) 150 g/l, is prepared as follows: 0.5 g of titanium metal is placed in a beaker with a capacity of 25 cmand dissolved by heating in 10 cmof concentrated hydrochloric acid, covered with a glass watch glass. The initial volume (10 cm) supports the constant addition of concentrated hydrochloric acid. Solution store in a dark bottle with a glass stopper is not more than 3 days.

A solution of trichloride titanium (operating) 15 g/DM; prepared by diluting a backup solution in 10 times a day use: to 1 cmbackup titanium trichloride solution are added 9 cmsvejeprokipachenna and chilled concentrated hydrochloric acid.

Standard solution tungsten (spare) containing 0.1 mg/cmtungsten: 0,1261 g of tungsten oxide, calcined to constant weight at 600−700 °C, were placed in a glass with a capacity of 100 cmand dissolved in 20−25 cmof sodium hydroxide solution, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water. The solution was stored in a plastic container.

A solution of tungsten (work) containing 20 µg/cmof tungsten, is prepared by diluting a backup solution with water 5 times. The solution is prepared in de

HB use.

5.2. Analysis

5.2.1. 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 was added 12 cmof hydrochloric acid diluted 1:1, 8 cmof a solution of ammonium fluoride, 0.5 g of ammonium oxalate and heated to dissolve the salts.

If you expected a tungsten content of more than 0.1% of the obtained transparent solution was transferred to volumetric flask with a capacity of 25 cmand was adjusted to the mark with water.

5.2.2. For the determination of tungsten in a volumetric flask with a capacity of 25 cmtaken 5 or 10 cmof a solution containing 40−100 ág of tungsten, add hydrochloric acid diluted 1:1, to a total volume of 12 cm(which is when aliquote part 5 cmand 9.6 cm, and when aliquote part 10 cm — 7.2 cm). Pour a solution of ammonium fluoride to a total volume of 5 cm(which is when aliquote part 5 cm — 3.4 cm, and when aliquote part 10 cm — 1.8 cm), add to the beaker of water to a total volume of about 22 cm, mix. The solution was cooled to 15−20 °C (cold water), pour 1 cmof a solution of ammonium Rodenstock, mix and add dropwise the solution of titanium trichloride to the transition of the red-brown solution yellow and 5 drops (excess); dilute solutions up to the mark with water, mix. 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 CP

annenia.

5.2.3. If you expected a tungsten content of less than 0.1% of the obtained transparent 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 about 22 cm. The solution was cooled to 15−20 °C (cold water), pour 1 cmof a solution of ammonium Rodenstock, mix and add dropwise the solution of titanium trichloride to the transition of the red-brown solution yellow and 5 drops (excess); dilute solutions up to the mark with water, mix. 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.

5.2.4. 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 cmof the working standard solution of tungsten, which corresponds to 5; 10; 20; 30; 40; 60; 80 and 100 micrograms of tungsten. Poured in 12 cmof hydrochloric acid diluted 1:1, 5 cmof a solution of fluoride of ammonium, diluted with water to a total volume of about 22 cm, mix. The solutions were cooled to 15−20 °C (cold water), pour 1 cmof a solution of ammonium Rodenstock, mix and add dropwise the solution of titanium trichloride to the transition of the red-brown solution yellow and 5 drops (excess); dilute solutions up to the mark with water and mix. After 20 min the solutions from the volumetric flasks was transferred to a dry cylinder to colorimetrically.

5.3. Processing of the results

5.3.1. Mass fraction of tungsten () in percent (mass fraction of tungsten of greater than 0.1%) is calculated according to the formula

,

where is the mass of tungsten was found in the scale reference solutions, the mcg;

 — capacity volumetric flasks, cm;

 — aliquotes volume of the solution taken for the determining, cm;

 — the weight of the portion of the sample,

5.3.2. Mass fraction of tungsten () in percent (mass fraction of tungsten is less than 0.1%) is calculated according to the formula

,

where is the mass of tungsten was found in the scale reference solutions, the mcg;

 — the weight of the portion of the sample,

5.3.3. 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.4.

Table 4