GOST 12353-78

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  ГОСТ 12353-78

GOST 12353−78 (ST SEV 1506−79) Steel alloyed and high alloy. Methods for determination of cobalt (with Change No. 1)

GOST 12353−78
(ST CMEA 1506−79)

Group B39

STATE STANDARD OF THE USSR

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of cobalt

Alloyed and high-alloyed steels.
Methods of cobalt determination

Date of introduction from 01.01.80
to 01.01.95*
______________________________
* Expiration removed
Protocol N 4−93 inter-state Council
for standardization, Metrology and certification
(IUS N 4, 1994). — Note the CODE.

APPROVED AND put INTO EFFECT by decision of the USSR State Committee for standards of 23 November 1978 N 3081

PROVEN in 1984 by Decree of the state standard from 15.08.84 2877 N validity extended until 01.01.95

REPLACE GOST 12353−66, in addition to General guidance

REPRINT March 1986, with Change No. 1, approved in January 1983; Post. N 276 from 20.01.83 (ICS 5−83)


This standard establishes photometric methods for determination of cobalt (in mass fractions of from 0.0005 to 3.0%), atomic absorption method for the determination of cobalt (in mass fractions of from 0.005 to 25.0%), the method of potentiometric titration (in mass fractions of from 2.0 to 20.0%) and gravimetric method for the determination of cobalt (in mass fractions of from 0.5 to 25.0%).

The standard fully complies ST SEV 1506−79.

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 20560−75 and ST SEV 487−77.

(Changed edition, Rev. N 1).

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF COBALT (0,0005−0,10%)

2.1. The essence of the method

The method is based on formation of colored red chelation of cobalt (III) with nitroso-R-salt. Light absorption of the solution measured at a =415 nm.

Tungsten, niobium, silicon and titanium are separated by acid hydrolysis.

Cobalt pre-separated from the main components of steel of 9 n hydrochloric acid solution on strong-base anion exchanger.

2.2. Apparatus, reagents and solutions

Spectrophotometer, photoelectrocolorimeter, or spectropolarimeter.

The chromatographic column with a diameter of 1.5−2 cm (see drawing) filled with the anion exchange resin layer height 30−35 cm

Strong-base anion exchange resin type AB-17−8чС according to GOST 20301−74.

Preparation of anion exchange resin for analysis.

100−150 cmcommodity anion exchange resin (available in the form of a slurry in water) was washed twice with water by decantation method. To separate the resin fraction with a grain size of less than 0.6 mm, the slurry of resin in water poured into a sieve No. 063 GOST 6613−73 and washed with water, collecting the past through a sieve fraction of the anion exchanger with water in a vessel with a capacity of 2−3 DM. Remaining on the sieve resin cast. The fraction of the anion exchanger, passed through a sieve, washed twice with hydrochloric acid of 1:30 by way of decantation, then with hydrochloric acid 1:1 to the absence of iron ions (sample with ammonium radamisty) and water 4−5 times. The resin is treated with 5% sodium hydroxide solution until a negative reaction on chloride ions (test with silver nitrate) and then with water to neutral reaction on the universal indicator and transferred to the column bottom of which a pre-place pad of glass wool. The layer of anion exchange resin in the column should be smooth without air bubbles. After filling the column through it at a rate of 1 ml/min flow at the beginning of 120−150 cmof hydrochloric acid of 1:30, then 120−150 cmof hydrochloric acid of 1:2 and 100 cmof water.

Hydrochloric acid by the GOST 3118−77 or 14261−77, 9 n, and 0.5 N. dilute 1:1, 1:2, 1:30, 1:100.

Nitric acid GOST 4461−77.

Orthophosphoric acid according to GOST 6552−80, and diluted 1:50.

Sodium acetate according to GOST 199−78, 50% solution.

Sodium hydroxide according to GOST 4328−77, 5% solution.

Nitroso-R-salt (disodium salt of 1-nitroso-2-naphthol-3, 6 disulphonate) according to GOST 10553−75, 0,1% solution.

Ammonium radamisty, 5% solution.

Carbonyl iron, high purity.

Cobalt metal, stamps K0.

Cobalt chloride standard solutions a and B.

A. a solution of 0.1 g of cobalt metal was placed in a beaker with a capacity of 250−300 cmand dissolved by heating in 100 cmof hydrochloric acid of 1:1. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmstandard solution A contains 0.1 mg of cobalt.

Solution B, freshly prepared. 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmstandard solution B contains 0.01 mg of cobalt.

The indicator is universal, b

Umag.

2.3. Analysis

The weight of steel depending on the mass fraction of cobalt (table.1) is placed in a flask or beaker with a capacity of 200−300 cm, 30 cm, pouredsalt and 10 cmof nitric acid, cover the beaker watch glass and heated to dissolve sample.

Table 1

The solution was evaporated to dryness. To the dry residue poured 5cmof hydrochloric acid and heated to dissolve the salts. To the solution poured 50 cmof hot water, heated to 80−90 °C, filtered off the precipitate of tungsten, silicon, niobium and titanium acid on the two filters «white ribbon» and washed 6−7 times with hot hydrochloric acid (1:100).

The filter with the sediment is discarded and the filtrate evaporated to dryness. To the dry residue poured 20 cm9 n hydrochloric acid, heated to dissolve the salts, and cooled.

A chromatographic column is washed with 50 cm9. hydrochloric acid. The solution passed through the column at a rate 1−1. 5 ml/min. When the solution level in the column will be 1−2 cm above the layer of resin, then rinsed a glass of 5−6 cm9 n hydrochloric acid and transfer the washing liquid in the column. Repeat this operation 3 more times and wash the upper part of the column 2−3 times 5−6 cm9 n hydrochloric acid, each time making sure that the solution level in the column did not fall below 1−2 cm above the resin layer. Passed through a column of 100 cm9. hydrochloric acid. The filtrate is discarded.

Cobalt desorbent 60−70 cmof a hydrochloric acid solution 1:2 with a speed of 1−1. 5 ml/min, collecting the eluate in a glass with a capacity of 300 cm.

To prepare the resin for the subsequent definition of cobalt column chromatography was washed with 100 cmof 0.5 N. hydrochloric acid, then 250−300 cmof water up to neutral reaction on the universal indicator. Wash liquid discarded.

When the cobalt content of from 0.0005 to 0.002% eluate is evaporated to 5−10 cm, pour a few drops of nitric acid and evaporated to moist salts. When the mass fraction of cobalt in excess of 0.002% eluate is evaporated to a volume of 30−35 cm, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Aliquot part of the solution placed in a beaker with a capacity of 100 cm, pour a few drops of nitric acid and evaporated to moist salts.

In both cases, to the remainder pour 5 cmof phosphoric acid 1:50, 1 cmof a 0.1% strength solution of nitroso-R-salt, 2 cm50% solution of sodium acetate, stirred and allowed to stand the solution in a boiling water bath for 3 min. Then poured to a solution of 0.75 cmof hydrochloric acid, stirred, and again incubated in a water bath for 2 min. the Solution was cooled, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

Optical density of the solution measured on a spectrophotometer or spectropolarimetry at a =415 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength interval from 400 to 500 nm in a cuvette with a thickness of the absorbing layer is 50 mm.

As a solution comparison solution is used in the reference experiment.

The cobalt content find the calibration schedule subject to amendments the reference experiment.

2.3.1. Construction of calibration curve

Nine of cups with a capacity of 250−300 cmis placed 1 g of carbonyl iron. In eight glasses poured consistently 0,5; 0,7; 1,0; 1,2; 1,4; 1,6; 1,8 and 2.0 cmstandard solution B hydrochloric acid cobalt, which corresponds to 0,005; 0,007; 0,010; 0,012; 0,014; 0,016; 0,018 and 0.020 mg cobalt.

The ninth glass is used for the reference experiment. Poured 30 cmsalt and 10 cmof nitric acid, cover glasses, watch glasses, and dissolve the sample when heated.

Then do as stated in claim 2.3, beginning with the words: «the Solution was evaporated to dryness, the dry residue poured 5 cmof hydrochloric acid. .».

From the values of optical density of analyzed solutions is subtracted the value of the optical density of the solution control the analysis. The found values of optical density and corresponding concentration values of cobalt build the calibration graph.

2.4. Processing of the results

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

,

where is the weight of steel, suitable colorimetrically aliquote part of the solution, mg;

 — the amount of cobalt was found in the calibration schedule, mg.

2.4.2. Permissible absolute discrepancy between the outermost of the three parallel results at a confidence level = 0.95 does not exceed the values specified in table.2.

Table 2

3. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF COBALT (0,005−0,5%)

3.1. The essence of the method

The method is based on formation of colored red chelation of cobalt with nitroso-R-salt.

Light absorption measured at =500 or a =530 nm.

The influence of iron, chromium and Nickel, deformity, eliminate the addition of potassium pyrophosphate and subsequent boiling the solution with nitric acid or deposition of iron, aluminum, titanium, chromium and other elements a zinc oxide.

3.2. Apparatus, reagents and solutions

Spectrophotometer, photoelectrocolorimeter, or spectropolarimeter.

Hydrochloric acid by the GOST 3118−77 or GOST 14261−77 and diluted 1:1, 1:100.

Nitric acid GOST 4461−77 or GOST 11125−84 and diluted 1:1.

Nitroso-R-salt (disodium salt of 1-nitroso-2-naphthol-3,6-disulfonate) according to GOST 10553−75, 0,1% and 1% solutions.

Sodium acetate according to GOST 199−78, 40% and 50% solutions.

Potassium pyrophosphate, 80% solution.

Carbonyl iron according to GOST 13610−79 or with a mass fraction of cobalt is less than 0.005%.

The zinc oxide in the form of an aqueous suspension 1:5.

Cobalt metal stamps K0 with a mass fraction of cobalt not less than 99.99%.

Standard solutions of cobalt.

Solution a: 0.1 g of cobalt metal was placed in a beaker with a capacity of 250−300 cm, dissolved by heating in 100 cmof hydrochloric acid 1:1 and cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmstandard solution contains 0.1 mg of cobalt.

Solution B: 0.2 g of cobalt dissolved in 10 cmof nitric acid, diluted with water, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof solution B contains 0.2 mg of cobalt.

Solution: 2.5 g of iron is dissolved in 40 cmof a hydrochloric acid solution (1:1), oxidized with nitric acid, adding it dropwise, add with microburette 12.5 cmstandard solution A and then do as described in claim 3.3.2 until the deposition of the iron and filtration of the solution.

1 cmof the solution contains 0.01 mg of cobalt.

The solution is prepared before use.

Solution: 2.5 g of iron is dissolved in 40 cmof a hydrochloric acid solution (1:1), oxidized with nitric acid, adding it drop by drop and then do as in point 3.3.2 until the deposition of the iron and filtration of the solution.

Ammonia water according to GOST 376

0−79.

3.3. Analysis

3.3.1. Determination of cobalt (0,10−0,50%)

The weight of steel 0.25 g when the mass fraction of cobalt from 0.1 to 0.2% or 0.1 g for the mass concentration of cobalt in excess of 0.2 to 0.5% is placed in a beaker or flask with a capacity of 250−300 cm, flow 15 cmof hydrochloric acid and 5 cmof nitric acid, cover with watch glass and heated to dissolve sample. The solution was evaporated to dryness. To the dry residue poured 5cmof hydrochloric acid and heated to dissolve the salts. To the solution poured 50 cmof hot water, heated to 80−90 °C, filtered off the precipitate of silicon, tungsten, niobium and titanium acid on the two filters «white ribbon» and washed 6−7 times with hot hydrochloric acid (1:100). Filter the precipitate discarded.

The filtrate is cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Aliquot part of the solution, equal to 10 cm, placed in a beaker with a capacity of 100 cm, flow 10 cmwater 10 cmof a 0.1% strength solution of nitroso-R-salt, 5 cm in40% solution of sodium acetate immediately and 5 cm80% strength solution of potassium pyrophosphate, then the solution was heated to boiling, boil for 2−3 minutes, pour 5 cmof nitric acid (1:1) and boil for another 1 min. the Solution was cooled, transferred to a volumetric flask with a capacity of 50 cm, top up with water to the mark and mix.

Optical density of the solution measured on spectropolarimetry or spectrophotometer at a =500 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of from 430 to 540 nm in a cuvette with the thickness of the absorbing layer 30 mm.

Reference solution prepared as follows: aliquot part of the solution, equal to 10 cm, placed in a beaker with a capacity of 100 cm, flow 10 cmof water and nitric acid and boil for 2 minutes, Then pour 10 cmof a 0.1% strength solution of nitroso-R-salt, 5 cm in40% solution of sodium acetate immediately and 5 cm80% strength solution of potassium pyrophosphate. The solution was boiled for 1 min, cooled, transferred to a volumetric flask with a capacity of 50 cm, made up to the mark with water and mix.

The content of cobalt find on a calibration schedule, as amended con

— controlling experience.

3.3.1.1. Construction of calibration curve

Seven of cups or flasks with a capacity of 250−300 cmis placed 0.25 g of carbonyl iron. Six of cups or flasks poured sequentially 1, 2, 3, 4, 5 and 6 cmstandard solution A. the Seventh beaker or flask with a capacity of 250 to 300 cmis used for the reference experiment. Pour 15 cmof hydrochloric and 5 cmof nitric acid, cover the cups or flasks, watch glasses and heated to dissolve batches. Next, with the contents of each glass or bulb act, as specified in clause 3.3.1.

From the values of optical density of analyzed solutions is subtracted the value of the optical density of the solution in the reference experiment. On the found values of optical density and corresponding concentration values of cobalt build the calibration graph.

3.3.2. Determination of cobalt (0,005−0,50%)

The weight of sample and volume of hydrochloric acid solution to dissolve the sample, depending on the mass fraction of cobalt is determined by the table.3.

Table 3

Weighed sample is placed in a conical flask with a capacity of 300 cmand dissolved in specified volume of the hydrochloric acid solution. After dissolving the oxidized nitric acid, adding it dropwise until the termination of foaming solution, and evaporate the sample solution to a volume of about 10 cm, add 25 cmof a solution of hydrochloric acid and again evaporate the solution to a volume of about 10 cm, is neutralized with ammonia to slightly acidic environment. Add 30 cmof water, cooled, transferred to a volumetric flask with a capacity of 250 cmand top up with water to a volume of 150 cm.

For the separation of cobalt from iron, chromium, titanium and other elements to the resulting solution was added in small portions to the suspension of zinc oxide, each time vigorously shaking the solution. Suspension oxide is added until, until the precipitate of excess zinc oxide is not going to the bottom of the flask in the form of invisible no white residue. The contents of the flask topped up to the mark with water, vigorously stirred and left for several minutes before sedimentation of sludge. The solution was then filtered through a dry folded filter into a dry beaker, rejecting the first portion of the filtrate. Depending on the content of cobalt is taken according to table.3A two aliquote part of the sample solution and the background, and put them in two volumetric flasks with a capacity of 50 cm.

Table 3A

To prepare the solution compare to the solution in the first flask add 10 cmof a solution of sodium acetate and 10 cmof nitric acid, made up to the mark with water and mix.

For the preparation of colour solution to the solution in the second flask is poured 10 cmof the solution, nitroso-R-salt, 10 cmof a solution of sodium acetate, mix and leave for 10 min at room temperature. Then add 10 cmof nitric acid, made up to the mark with water and mix. After 20 minutes, measure the optical density of the solution at a wavelength of 500−530 nm.

3.3.2.1. Construction of calibration curve

For the solution comparison in six of the seven volumetric flasks with a capacity of 50 cmmeasured to 0,5; 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution V. In all flasks is poured a solution of background to a volume of 20 cm, added to 10 cmof a solution of sodium acetate and nitric acid, made up to the mark with water and mix.

To obtain a colored solution in six of the seven volumetric flasks with a capacity of 50 cmmeasured to 0,5; 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution V. In all flasks is poured a solution of background to a volume of 20 cm, added to 10 cmof the solution, nitroso-R-salt and a solution of sodium acetate, mix and leave for 10 min at room temperature. Then add 10 cmof nitric acid solution, stirred, topped up to the mark with water and mixed again. After 20 minutes, measure the optical density of the solutions at a wavelength of 500−530 nm. Solution comparison is the appropriate solution. According to the obtained values of optical density of solutions and the corresponding content of cobalt build the calibration graph

IR.

3.4. Processing of the results

3.4.1. Mass fraction of cobalt () in percent is calculated by the formula

,

where is the mass of cobalt was found in the calibration graphics mg;

the weight of steel, suitable colorimetrically aliquote part of the solution, mg

.

3.4.2. Allowable absolute differences between the extreme values of three parallel results at a confidence level =0.95 does not exceed the values specified in table.3b.

Table 3b

Sec. 3. (Changed edition, Rev. N 1).

4. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF COBALT (0,50−3,00%)

4.1. The essence of the method

The method is based on formation of colored red chelation of cobalt with nitroso-R-salt. Light absorption of the solution measured at =500 nm.

The influence of iron, Nickel and copper, preventing the determination of cobalt, can be eliminated by boiling the solution with nitric acid after the addition of nitroso-R-salt.

4.2. Apparatus, reagents and solutions

Spectrophotometer, photoelectrocolorimeter, or spectropolarimeter.

Hydrochloric acid by the GOST 3118−77 or GOST 14261−77 and diluted 1:1.

Nitric acid GOST 4461−77 and diluted 1:1.

Sulfuric acid GOST 4204−77 and diluted 1:100.

Ammonia, aqueous solution according to GOST 3760−79.

Nitroso-R-salt (disodium salt of 1-nitroso-2-naphthol-3,6 disulfonate) according to GOST 10553−75, 0,1% solution.

Sodium acetate according to GOST 199−78, 50% solution.

Carbonyl iron, high purity.

Cobalt metal stamps TO.

Cobalt chloride, a standard solution; 0.1 g of cobalt metal was placed in a beaker with a capacity of 250−300 cm, dissolved by heating in 100 cmof hydrochloric acid 1:1 and cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmstandard solution contains 0.1 mg of cobalt.

4.3. Analysis

0.1 g of steel placed in a beaker or flask with a capacity of 250−300 cm, flow 15 cmsalt and 5 cmof nitric acid, cover with watch glass and heated to dissolve sample. The solution was cooled, carefully pour 5 cmof sulphuric acid, is heated to release vapours and cooled. Cautiously with continuous stirring poured 50−60 cmof water and heated to dissolve the salts. The solution was cooled, transferred to a volumetric flask with a capacity of 200 cm, made up to the mark with water and mix. The solution was filtered through two dry filter «white ribbon» in a glass or flask, discarding first portion of filtrate. Filter the precipitate discarded. Aliquot part of the solution, equal to 5 cm, were placed in a glass with a capacity of 100 cm, poured 5cmof water, add ammonia solution, priliva it prior to the precipitation of hydroxides of metals added dropwise hydrochloric acid 1:1 to dissolve the precipitate of hydroxide and an excess of 1 cm. Then the solution is poured 5 cm50% solution of sodium acetate and 10 cmof a 0.1% strength solution of nitroso-R-salt, the contents of the beaker are heated to boiling, boil for 2−3 min, poured 10 cmof nitric acid 1:1 and boil for another 1 min. the Solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Optical density of the solution measured on a spectrophotometer or spectropolarimetry at =500 nm or photoelectrocolorimeter with a filter having a region of transmittance in the wavelength range of from 430 to 540 nm, in a ditch with thickness of the absorbing layer is 50 mm when the content of cobalt up to 1% and in cuvette with thickness of the absorbing layer is 30 mm when the content of cobalt from 1% to 3%.

Reference solution prepared as follows: aliquot part of the solution is 5 cmis placed in a beaker with a capacity of 100 cm, flow 10 cmof nitric acid 1:1 and boil for 2 minutes, Then pour 10 cmof a 0.1% strength solution of nitroso-R-salt, 5 cm in50% strength solution of sodium acetate, the solution was boiled for 1 min, cooled, transferred to a volumetric flask with a capacity of 100 cm, top up with water and mix.

The content of cobalt find on a calibration schedule, as amended by Kont

roll experience.

4.3.1. Construction of calibration graphs

4.3.1.1. Construction of calibration curve for the mass concentration of cobalt in the steel is 0.5 to 1%.

In eight glasses with a capacity of 250−300 cmis placed 0.1 g of carbonyl iron. Seven glasses pour consistently 4, 5, 6, 7, 8, 9 and 10 cmto the standard solution of chloride of cobalt, which corresponds to 0,4; 0,5; 0,6; 0,7; 0,8; 0,9 and 1.0 mg cobalt. The eighth glass with a capacity of 250 to 300 cmis used for the reference experiment. In glasses poured at 15 cmsalt and 5 cmof nitric acid, cover glasses, watch glasses, and dissolve the sample when heated. Next, with the contents of each beaker received, as specified in clause 4.3, beginning with the words: «the Solution was then cooled, carefully pour 5 cmof sulphuric acid and heated to release the vapours… «.

From the values of optical density of analyzed solutions is subtracted the value of the optical density of the solution in the reference experiment. On the found values of optical density and corresponding concentration values of cobalt build the calibration graph.

4.3.1.2. Construction of calibration curve for the mass concentration of cobalt in steel between 1.0 to 3.0%.

Seven of cups with a capacity of 250−300 cmis placed 0.1 g of carbonyl iron. Six glasses poured consistently 10; 14; 18; 22; 26 and 30 cmstandard solution of chloride of cobalt, which corresponds to 1,0; 1,4; 1,8; 2,2; 2,6 and 3,0 mg of cobalt. The seventh glass with a capacity of 250 to 300 cmis used for the reference experiment.

In glasses poured at 15 cmsalt and 5 cmof nitric acid, cover them with watch glasses, and dissolve the sample when heated.

Next, with the contents of each beaker received, as specified in clause 4.3, beginning with the words: «the Solution was then cooled, carefully pour 5 cmof sulphuric acid and heated to release the vapours… «.

From the values of absorbance of analyzed solutions is subtracted the value of the optical density of the solution in the reference experiment. The found values of optical density and corresponding concentration values of cobalt build the calibration graph.

4.4. Processing of the results

4.4.1. Mass fraction of cobalt () in percent is calculated by the formula

,

where is the weight of steel, suitable aliquote part of the solution, mg;

 — weight of cobalt, was found in the calibration schedule, mg.

4.4.2. Allowable absolute differences between the extreme results of three parallel measurements at a confidence level =0.95 does not exceed the values specified in table.4.

Table 4

5. DETERMINATION OF COBALT (2,00−20,0%) BY THE METHOD OF POTENTIOMETRIC TITRATION

5.1. The essence of the method

Cobalt is separated from manganese, chromium, Nickel and other elements by selective sorption on anion exchange resin from hydrochloric acid solution. In the eluate cobalt (II) potentiometric titrated in ammonia environment with a solution of potassium relatoseroticos; wherein the cobalt (II) is oxidized to cobalt (III).

5.2. Apparatus, reagents and solutions

The setup for potentiometric titration: a pair of electrodes: a platinum indicator electrode and a reference electrode — a calomel, silver chloride or tungsten;

magnetic stirrer;

the DC millivoltmeter or pH meter that clearly capture the potential jump at the equivalence point during the titration with the selected pair of electrodes. If necessary, the instrument sequentially connecting a variable resistance that allows you to make measurements in the range of the instrument scale.

The chromatographic column with a diameter of 1.5−2 cm, filled with anion exchange resin layer height 40−45 cm

Strong-base anion exchange resin type AB-17−8чС according to GOST 20301−74.

Preparation of anion exchange resin for analysis, 100−150 cmcommodity anion exchange resin (available in the form of a slurry in water) was washed twice with water by decantation method. To separate the resin fraction with a grain size of less than 0.6 mm, the slurry of resin in water poured into a sieve No. 063 GOST 6613−73 and washed with water, collecting the past through a sieve fraction of the anion exchanger with water in a vessel with a capacity of 2−3 DM. Remaining on the sieve resin cast. The fraction of the anion exchanger with a grain size of less than 0.6 mm is washed twice by decantation with hydrochloric acid 1:30, then with hydrochloric acid 1:1 to the absence of iron ions (sample with ammonium radamisty) and water 4−5 times. The resin is treated with 5% solution of hydrate of sodium oxide to a negative reaction on chloride ions (test with silver nitrate) and then with water to neutral reaction on the universal indicator and transferred to the column bottom of which a pre-place pad of glass wool. The layer of anion exchange resin in the column should be smooth without air bubbles. After filling the column through it at a rate of approximately 1 ml/min flow at the beginning of 120−150 cmof hydrochloric acid of 1:30, then 120−150 cmof hydrochloric acid of 1:2 and 100 cmof water.

Hydrochloric acid by the GOST 3118−77 and diluted 3:1; 1:1; 1:2 and 1:30.

Nitric acid GOST 4461−77 and diluted 1:100.

Ammonia, aqueous solution according to GOST 3760−79.

Ammonium chloride according to GOST 3772−74.

Ammonium citrate according to GOST 9264−79.

Cobalt metal, stamps K0.

Cobalt chloride, standard solution, 0.5 g of cobalt metal was dissolved with heating in 20 cmof nitric acid 1:1. The solution was evaporated almost to dryness, poured 10−15 cmof hydrochloric acid and again evaporated almost to dryness. Operation of evaporation after addition of hydrochloric acid is repeated twice more. Salt is dissolved in 50 cmof hydrochloric acid 1:1, transfer the solution into a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. 1 cmof this solution contains 0.001 g of cobalt.

Potassium genesisintermedia according to GOST 4206−75, standard solution. Zhelezovanadievoj of 8.25 g of potassium placed in beaker with a capacity of 600−800 cmand dissolved in 400−500 cmof water. The contents of the beaker transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix. The solution is poured into a bottle made of dark glass.

The mass concentration of the solution is set every time before use a standard solution of chloride of cobalt, passed through a column of anion exchange resin.

15 cmstandard solution of cobalt chloride is placed in a beaker with a capacity of 200−300 cmand evaporated almost to dryness.

Then do as specified in clause 5.3, beginning with the words «To the residue in the glass poured 20 cmof hydrochloric acid of 3:1 and dissolved salts at a moderate heat».

Mass concentration of a solution of potassium relatoseroticos expressed in grams of cobalt, () is calculated by the formula

,

where is the volume of a standard solution of chloride of cobalt, taken for titration, cm;

the cobalt content in 1 cmof a standard solution of cobalt chloride, g;

 — the volume of solution of potassium relatoseroticos, spent on titration, sm.

5.3. Analysis

Weighed were:

0.5 g when the mass fraction of cobalt is from 2 to 5%

0.25 g «""" 5 to 10%

0.1 g «""" from 10 to 20%

placed in a beaker with a capacity of 300 cm, 40−50 cm pouredhydrochloric acid and 5−10 cmof nitric acid. Beaker cover watch glass, and dissolve a portion with a moderate heat, carefully pour 5−10 cmof nitric acid and evaporated to a volume of 15−20 cm. Dilute with hot water up to 150−200 cm, heated to boiling and for a complete selection of tungsten acid is kept warm the oven for 1.5−2 hours.

The precipitate was filtered off on the filter «blue ribbon» with the addition of a small amount of ashless filtrowanie mass and washed 10−12 times with hot nitric acid 1:100. Filter the precipitate discarded.

The solution was evaporated almost to dryness, add 10 cmof hydrochloric acid and again evaporated almost to dryness.

To the residue in the glass poured 20 cmof hydrochloric acid of 3:1 and dissolved salts at a moderate heat. The solution was cooled to room temperature and transferred to an ion exchange column with the resin, pre-washed 100 cmof hydrochloric acid of 3:1.

The solution passed through the column at a rate of approximately 1 ml/min. When the solution level in the column will be 1−2 cm above the layer of resin, then rinsed a glass of 5−6 cmof hydrochloric acid of 3:1 and carry the wash liquid into the column. Repeat this operation three more times and wash the upper part of the column 2−3 times 5−6 cmof hydrochloric acid of 3:1, each time making sure that the solution level in the column did not fall below 1−2 cm above the resin layer. Passed through a column still 120−150 cmof hydrochloric acid of 3:1 and the resulting filtrate discarded.

Cobalt desorbent 200−250 cmof hydrochloric acid of 1:2 at a speed of 1−1. 5 ml/min, collecting the eluate in a glass with a capacity of 400 cm. To prepare the resin for the subsequent definition of the chromatographic column is washed with 100 cmof 0.5 N. hydrochloric acid and 250−300 cmof water up to neutral reaction on the universal indicator. Wash liquid discarded. To aluatu poured 30 cmof nitric acid, 15 cmsulphuric acid and the solution evaporated to release vapors of sulfuric acid. The solution was cooled, carefully poured 40 cmof water and again cooled. Add the ammonia solution before the precipitation of hydroxides of metals which dissolve by adding dropwise hydrochloric acid 1:1.

The solution was cooled to room temperature, add 10 g of ammonium citrate, 15 g of ammonium chloride, 20−25 cmof ammonia solution, stir the solution with a stirrer to completely dissolve the salts and then titrated with a solution of potassium relatoseroticos. First, a solution of potassium relatoseroticos poured quickly, and near the equivalence point — drop by drop, recording the volume of solution in the burette and the readings after adding each drop. The volume of solution in the burette, corresponding to the maximum change of the readings, accept for the amount that went

on titration.

5.4. Processing of the results

5.4.1. Mass fraction of cobalt () in percent is calculated by the formula

,

where is the volume of solution of potassium relatoseroticos that went to the titration of cobalt, cm;

 — mass concentration of a solution of potassium relatoseroticos expressed in grams of cobalt;

 — the weight of the portion,

5.4.2. Permissible absolute discrepancy between the outermost of the three parallel results at a confidence level =0.95 does not exceed the values specified in table.5.

Table 5

6. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF COBALT (0,005−25,0%)

6.1. The essence of the method

The method is based on measuring the degree of absorption of resonance radiation by free atoms of cobalt, produced as a result of spraying the test solution into the flame of air-acetylene or acetylene-nitrous oxide, at a wavelength of 240,7 nm or nm 252.1 bln.

6.2. Apparatus, reagents and solutions

Atomic absorption spectrophotometer fiery.

Lamp with hollow cathode for the determination of cobalt.

The cylinder with acetylene.

A tank of nitrous oxide.

The compressor supplying compressed air, or compressed air.

Hydrochloric acid by the GOST 3118−77, diluted 1:1 and 1:40.

Nitric acid GOST 4461−77 or GOST 11125−84.

Orthophosphoric acid according to GOST 6552−80.

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

A mixture of acids: 150cmphosphoric acid and 300 cmof sulphuric acid (1:1) mix, cool and add water to a volume of 1 DM.

Iron electrolytic or carbonyl with a cobalt content less than 0.005%.

Cobalt metal containing not less than 99.99%, grade KO.

Standard solutions of cobalt.

Solution a: 1 g of cobalt metal was dissolved in a beaker with a capacity of 200 cmwhen heated at 20 cmof hydrochloric acid with the addition of 2 cmof nitric acid. The solution was evaporated to dryness, the residue is dissolved by heating in 20 cmof hydrochloric acid (1:1). The solution was transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. 1 cmof the solution contains 2 mg of cobalt.

Solution B: 50 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:40) up to the mark and mix. 1 cm3 of solution B contains 1 mg of cobalt.

Solution: 25 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:40) up to the mark and mix. 1 cmof solution contains 0.5 mg of cobalt.

Solution G: 25 cmsolution And transferred to a volumetric flask with a capacity of 500 cm, add hydrochloric acid solution (1:40) up to the mark and mix. 1 cmsolution G contains 0.1 mg of cobalt.

Solution D: 50 cmsolution G is transferred to a volumetric flask with a capacity of 100 cm, is poured a solution of hydrochloric acid (1:40) up to the mark and mix. 1 cmof solution A contains 0,0

5 mg of cobalt.

6.3. Preparation of the device

The training device is carried out in accordance with the attached instructions. Set the spectrophotometer at a resonance line of 240,7 nm or nm 252.1 bln. After switching on the gas flow and ignition of the burner spray water and set the zero of the instrument.

6.4. Analysis

6.4.1. Determination of cobalt (0,25−5,00%)

The weight of steel depending on the mass fraction of cobalt (table.6) is placed in a beaker or flask with a capacity of 200−300 cmand is dissolved by heating in 20 cmof salt and 5 cmof nitric acid. The solution was evaporated to dryness. Pour 4 cmof hydrochloric acid of 15 cmof water and heated to dissolve the salts.

Table 6

The solution was transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. Part of the solution filtered through a dry filter «white ribbon» in the conical flask by rinsing it the first portions of the filtrate.

For preparation of the null solution in a volumetric flask with a capacity of 100 cmis placed 4 cmof hydrochloric acid, made up to the mark and mix. Spray zero and test solutions in order of increasing absorption in the flame of air-acetylene at a wavelength of 252.1 bln nm to obtain stable readings for each solution. Before spraying each solution is sprayed water to wash the system and check the zero point.

6.4.1. Construction of calibration curve

In a volumetric flask with a capacity of 100 cmplaced 1, 2, 3, 4, 5 and 6 cmstandard solution of cobalt, which corresponds to 0,5; 1; 1,5; 2,0; 2,5 and 3 mg of cobalt, add 4 cmof hydrochloric acid, dilute to the mark with water and mix.

For preparation of the null solution in a volumetric flask with a capacity of 100 cmis placed 4 cmof hydrochloric acid, made up to the mark with water and mix. The solutions were sprayed in order of increasing absorption, starting from the zero solution. Before spraying each solution is sprayed water. From the average value of the optical density of each solution is subtracted the average value of the optical density of the zero solution. On the found values of optical density and relative concentration of cobalt to build a calibration curve.

6.4.2. Determination of cobalt (0,005−25,0%)

The weight of the portion of the sample depending on the mass fraction of cobalt is determined by the table.7.

Table 7

The sample is placed in a beaker with a capacity of 250 cm, and dissolved in 20 cmof a mixture of acids. After reconstitution, the solution is oxidized with a few drops of nitric acid. In the analysis of high-alloyed steel sample was dissolved in 20 cmof a hydrochloric acid solution (1:1) and 3 cmof nitric acid, evaporated to small volume and add 20 cmof a mixture of acids. The resulting solution was evaporated until the appearance of sulphuric acid fumes, in the presence of undissolved carbides add a few drops of nitric acid and again evaporated until the appearance of sulphuric acid fumes. After cooling, add 20 cmof water and heated to dissolve the salts. The solution was transferred to volumetric flask of suitable capacity (see table.7), made up to the mark with water and mix. The solution is filtered through a dry filter into a dry beaker, rejecting the first portion of the filtrate, and if necessary dilute according to the table.7. Atomic absorption cobalt measured at a wavelength of 240,7 nm in the flame acetylene-air or nitrous oxide-acetylene.

6.4.2.1 above. Construction of calibration curve

When the mass fraction of cobalt from 0.005 to 0.025% in six sample beakers with a capacity of 250 cmis placed 1 g of iron and five of them measure 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution D. Then, each beaker was added 20 cmof a mixture of acids, after dissolution the solutions were oxidized with a few drops of nitric acid and evaporated until the appearance of sulphuric acid fumes. After cooling the solutions are transferred to volumetric flasks with a capacity of 50 cmand come forth as indicated in item 6.4.2.

When the mass fraction of cobalt from 0.025 to 0.05% in five glasses with a capacity of 250 cmis placed 0.5 g of iron and four of them measure 2,0; 3,0; 4,0 and 5,0 cmstandard solution D. Then, each beaker was added 20 cmof a mixture of acids, after dissolution the solutions were oxidized with a few drops of nitric acid and evaporated until the appearance of sulphuric acid fumes. After cooling the solutions are transferred to volumetric flasks with a capacity of 50 cmand come forth as indicated in item 6.4.2.

When the mass fraction of cobalt over 0.05 to 0.5% in seven glasses with a capacity of 250 cmis placed 0.1 g of iron and six of them measure 0,5; 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution, Then in each beaker was added 20 cmof the mixture of acids and act further according to claim 6.4.2 (solution transferred to a flask with a capacity of 100 cm). When the mass fraction of cobalt in excess of 0.5 to 5.0% in seven glasses with a capacity of 250 cmis placed 0.1 g of iron and six of them measure 0,5; 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution B.

To each beaker was added 20 cmof the mixture of acids and dissolve, oxidize and evaporate the above method. The solutions were transferred to volumetric flasks with a capacity of 100 cm, made up to the mark with water and mix. From the resulting solutions measured at 10 cmin a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. Then do as stated in claim 6.4.2.

When the mass fraction of cobalt in excess of 5.0 to 10.0% in seven glasses with a capacity of 250 cmis placed 0.1 g of iron and six of them measure 2,5; 3,0; 3,5; 4,0 and 5,0 cmstandard solution A. To each beaker was added 20 cmof the mixture of acids and dissolved, oxidized, evaporated the foregoing method. The solutions were transferred to volumetric flasks with a capacity of 100 cm, made up to the mark with water and mix. From the resulting solutions measured at 5 cmin a volumetric flask with a capacity of 100 cmand then do as above.

When the mass fraction of cobalt in excess of 10.0 to 25.0% in eight glasses with a capacity of 250 cmis placed 0.1 g of iron, and seven of them measure 5,0; 6,0; 7,0; 8,0; 9,0; 10,0 and 12.5 cmstandard solution A. Add 20 cmof the mixture of acids and dissolve, oxidize and evaporate the above method. The solutions were transferred to volumetric flasks with a capacity of 100 cm, made up to the mark with water and mix.

From the resulting solutions measured at 5 cmin a volumetric flask with a capacity of 250 cmand go Dale

e as above.

6.5. Processing of the results

Determine the average value of the optical density of the zero solution and subtract this value from the average value of the optical density of the tested solutions. According to the calibration schedule find the content of cobalt in the test solution.

6.5.1. Mass fraction of cobalt () in percent when performing the determining according to claim 6.4.1 is calculated by the formula

,

where is the mass of cobalt was found in the calibration graphics mg;

the weight of steel, suitable aliquote part of the solution, mg

.

6.5.2. Mass fraction of cobalt () in percent when performing the determining according to claim 6.4.2 is calculated by the formula

,

where is the concentration of cobalt was found in the calibration schedule, g/cm;

 — the volume of the final sample solution (see table.7), cm;

 — the weight of the portion of the sample corresponding to the selected part of the solution,

6.5.3. Allowable absolute differences between the extreme values of the results of three parallel measurements at a confidence level =0.95 does not exceed the values specified in table.8.

Table 8

6.5.4. The method used in the disagreement in the evaluation of quality of steels.

Sec. 6. (Changed edition, Rev. N 1).

7. GRAVIMETRIC METHOD FOR THE DETERMINATION OF COBALT (0.50 TO 25.0 PERCENT)

7.1. The essence of the method

The method is based on dissolving the steel in hydrochloric acid, separation of cobalt from the other components zinc oxide, deposition of its 1 nitroso-2-Naftalan, calcining the precipitate to oxide-cobalt oxide and convert to sulphate of cobalt.

7.2. Reagents and solutions

Nitric acid GOST 4461−77 and diluted 1:1.

Sulfuric acid according to GOST 4204−77.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1, 1:4.

Hydrochloric acid by the GOST 3118−77 and diluted 1:10, saturated with hydrogen sulphide.

Perchloric acid, 60% solution.

Acetic acid, ice GOST 61−75.

Ammonium oxalate, crystal according to GOST 5712−78.

Acidic potassium sulfate.

Hydrogen peroxide 3% solution, freshly prepared.

Zinc oxide according to GOST 10262−73 in the form of an aqueous suspension 1:5.

1 nitroso-2-naphthol according to GOST 7756−73 freshly prepared 2% solution.

2 g 1 nitroso-2-naphthol is placed in a conical flask with a capacity of 250 cmand moistened with 1−2 cmof acetic acid. The contents of the flask was dissolved with stirring in 50 cmof acetic acid, add 50 cmof hot water, vigorously shaken for 5 min and filtered.

Iron sulfate FeSO·7HO, 10% solution.

The hydrogen sulfide.

7.3. Analysis

7.3.1. The weight of sample and volume of hydrochloric acid solution (1:1) to dissolve the sample, depending on the mass fraction of cobalt is determined by the table.9.

Table 9

Weighed samples were placed in a glass with a capacity of 250 cmand dissolved with moderate heating in a solution of hydrochloric acid (1:1).

After dissolution, without interrupting the heating, oxidized with nitric acid, adding it dropwise until the termination of foaming solution, and evaporate the sample solution to a volume of 10 cm, 25 cm was addedhydrochloric acid solution (1:1) and again evaporated to a volume of 10 cm. The solution was then transferred to a volumetric flask with a capacity of 500 cm, and the glass rinsed with water, which attach to the solution. The volume of the solution in the flask must not exceed 300 cm.

In the analysis of steel with a mass fraction of tungsten in 6−20% of the sample dissolved in a hydrochloric acid solution by volume at 20 cmgreater than the specified in table.10. After adding the nitric acid solution is heated to boiling. In the analysis of steel with a mass fraction of chromium 10−25% carbon and 1−2% after incomplete dissolution of the sample in a solution of hydrochloric and nitric acids is added 20 cmof hydrochloric acid, evaporated to the appearance of its fumes, cool, add 5 cmof hydrochloric acid and heated to the recovery of chromium. Then add about 120 cmwater and 15 cmof iron sulfate solution and boil to dissolve the salts. The excess of sulphate of iron oxidized with a few drops of nitric acid.

In the analysis of steel with a mass fraction of copper, aluminum and molybdenum over 2% of the sample is dissolved in nitric acid solution in an amount of 10 cmfor 1 g of sample weight of sample, adding 5 cmof hydrochloric acid. After dissolution, the sample solution was evaporated to dryness, the residue is dissolved in 25 cmof a solution of hydrochloric acid (1:1), dilute with water to 200 cm, boiled and filtered through a dense filter with filtrowanie weight of precipitated silicic acid. The filter is heated to 80 °C and is passed through hydrogen sulfide. The separated copper sulfides and molybdenum filter at the filter medium density, compacted filtrowanie mass, and washed with hydrochloric acid solution (1:10) saturated with hydrogen sulfide. To the filtrate add 10 cmof hydrogen peroxide solution, evaporated to a volume of 40 cm, transferred to a volumetric flask with a capacity of 500 cmand dilute with water to about

Yama of 300 cm.

7.3.2. The solution obtained according to paragraph 7.3.1, is heated to a temperature of 70−80 °C and added thereto in small portions to the suspension of zinc oxide, each time vigorously shaking the solution. To the suspension was added until the precipitate of excess zinc oxide is not going to the bottom of the flask in the form of invisible no white residue. The solution was then diluted with hot water to a volume of about 350 cm, vigorously stirred and left to sedimentation of sludge.

The contents of the flask are cooled, made up to the mark with water and mix. The solution is filtered through a dry filter into a dry beaker, rejecting the first portion of the filtrate, and selected 250 cmof the filtrate in a beaker with a capacity of 800 cm. Solution in a glass diluted with water to a volume of about 400 cm, add 15 cmof hydrochloric acid, heated to 70 °C and the cobalt precipitated with a solution of 1-nitroso-2-Naftali, adding it in an amount of 20 cmfor every 0.01 g of cobalt.

A solution of 1-nitroso-2-naphthol was added slowly, mixing continuously. Solution and the precipitate was boiled for 5 min and kept for 2 h at 60 °C. the Precipitate was filtered on a double ashless filter, filtrowanie compacted mass, and washed it first from three to six times in cold hydrochloric acid solution (1:4), and then 3 times with water.

The filter with sediment after the extraction from it the greatest possible amount of moisture is folded so that the sediment was well covered with paper, placed it in a pre-calcined to constant weight and weighed porcelain crucible, cover the top oxalate of ammonia, and carefully dried in a drying Cabinet. Then cover the crucible with a lid, carefully avoiding the ignition incinerated filter, remove the cover, the crucible was placed in muffle furnace and calcined precipitate 40 min at 750−850 °C.

If the precipitate was isolated from samples with a mass fraction of more than 10% Nickel, calcined precipitate is dissolved by moderate heating, in hydrochloric acid or fused with acid sulphate of potassium and leach the melt with water. The resulting solution is diluted with water up to 250−300 cm, again precipitated cobalt 1 nitroso-2-naphthol up to the stage of calcination do as described above.

Calcined residue of nitrous-oxide of cobalt dipped in a crucible of 5 cmof nitric acid, heated to remove excess acid, cool, add 0.5−1 cmof sulphuric acid and gently heated until complete removal of acid.

The dry residue is calcined for several minutes at 500 °C. the Contents of the crucible cooled, moistened with 1−2 drops of water, again evaporated, calcined, as described above, to constant weight after cooling in a desiccator vzveshivat

yut.

7.4. Processing of the results

7.4.1. Mass fraction of cobalt () in percent is calculated by the formula

,

where is the mass of sediment sulfate of cobalt, g;

0,3804 — the ratio of cobalt sulphate on the cobalt;

 — the weight of the portion of the sample corresponding to the selected part of the solution,

7.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence level = 0.95 does not exceed the values specified in table.8.

Sec. 7. (Added, Rev. N 1).