GOST 12346-78

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  ГОСТ 12346-78

GOST 12346−78 (ISO 439−82, ISO 4829−1-86) Steel alloyed and high alloy. Methods for determination of silicon (with Amendments No. 1, 2, 3, 4)

GOST 12346−78
(ISO 439−82,
ISO 4829−1-86)

Group B39

INTERSTATE STANDARD

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of silicon

Alloyed and high-alloyed steels. Methods of silicon determination

ISS 77.080.20
AXTU 0809

Date of introduction 1980−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 23.11.78 N 3081

3. REPLACE GOST 12346−66, in addition to General guidance

4. The standard fully complies ST SEV 484−77 and ISO 439−82 and ISO 4829−1-86

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. The expiration time limit is removed by the resolution of Gosstandart of the USSR from 23.10.91 N 1640

7. EDITION (August 2009) with Changes No. 1, 2, 3, 4, approved in August 1980, August 1984, June 1989, October 1991 (IUS sizes 11−80, 11−84, 8−89, 1−92)


This standard sets the photometric method for the determination of silicon (with a mass fraction of silicon from 0.05% to 0.80%), a gravimetric method for the determination of silicon (with a mass fraction of silicon of from 0.1% to 7.0%).

The standard fully complies ST SEV 489−77 and ISO standards 439−82* and ISO 4829−1-86*.
________________
* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link. — Note the manufacturer’s database.

(Changed edition, Rev. N 1, 2, 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 28473.

(Changed edition, Rev. N 4).

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF SILICON (0,05−0,80%)

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF SILICON (0,05%-0,80%)

2.1. The essence of the method

The method is based on formation of yellow kremneftoristogo complex in hydrochloric acid solution (optimum pH of 1.3−1.5), the recovery of this compound ascorbic acid to kremneftoristogo blue and measuring optical density of colored solution.

The interfering influence of the molybdophosphoric complex is eliminated by adding oxalic acid. Arsenic-molybdenum complex is formed only at the boiling point of the solution.

The method is applicable in the determination of silicon in steels containing less than 3% of tungsten and 2% niobium.

(Changed edition, Rev. N 3).

2.2. Equipment and reagents

Spectrophotometer type SF-16 or photoelectrocolorimeter.

Hydrochloric acid according to GOST 3118 or GOST 14261 and diluted 1:1, 1:3, 1:50.

Nitric acid according to GOST 4461 or GOST 11125.

Sulfuric acid according to GOST 4204 or GOST 14262 diluted 4:1 or 5:1.

Hydrofluoric acid (hydrofluoric) according to GOST 10484.

Oxalic acid according to GOST 22180, 8% solution.

Ascorbic acid, 2% solution; prepare immediately before use.

Carbonyl iron of special purity.

Ammonium molybdate according to GOST 3765, a 5% solution prepared from recrystallized reagent.

Recrystallization of ammonium molybdate. 250 g of reagent was dissolved in 400 cmof water when heated to 70 °C — 80 °C. Cautiously add the ammonia until a clear smell. The solution was filtered through filter «blue ribbon», is cooled to 20 °C — 25 °C and poured under stirring in 300 cmof ethyl alcohol. Sediment is allowed to settle for 1 h and filtered it, the filter «white ribbon» placed in a Buchner funnel, using a water vacuum pump. Precipitate was washed 2−3 times with ethanol and dried in air.

Ethyl alcohol according to GOST 18300.

The anhydrous sodium carbonate according to GOST 83, H. h

Allowed the use of the reagent when the content of silicon, not more than 0,003%.

Potassium carbonate — sodium carbonate according to GOST 4332.

Silicon dioxide according to GOST 9428.

Sodium silicate, the standard solutions A and B.

Preparation of the solution A. 0,2139 g of silicon dioxide, calcined to constant weight at 1000 °C — 1100 °C, placed in a platinum crucible, add 2 g of sodium carbonate or potassium carbonate of sodium, stirred, cover with lid and fused at 1000 °C — 1100 °C. the Crucible is cooled, rinsed with water from the outside, placed in a beaker with a capacity of 250−300 cm, flow of 50−60 cmof water and heated until complete dissolution of the melt.

A solution of silicate of sodium is filtered in a volumetric flask with a capacity of 1 DM, the filter was washed 3−5 times with hot water and discarded. The solution in the flask is cooled, made up to the mark with water and mix. The sodium silicate solution is stored in polyethylene or quartz ware; 1 cmof the solution contains 0.0001 gram of silicon.

Determination of the mass concentration of a standard solution A.

Hydrochloric acid method. 50 cmof the solution And placed in a beaker with a capacity of 250−300 cmand 20−25 cm pouredhydrochloric acid 1:1. The solution in the beaker is evaporated to dryness. The dry residue moistened with 5−7 cmof hydrochloric acid and again evaporated to dryness.

The dry residue is heated for 1 h at 130 °C — 140 °C. Pour the 8−10 cmof hydrochloric acid and heated for 3−5 min; flow 80−100 cmof hot water, the beaker cover watch glass and the solution heated to boiling. Silicic acid is filtered off, the filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass. Precipitate was washed 3−5 times with hot hydrochloric acid 1:20 and another 2−3 times with hot water. The filter with the precipitate saved.

The filtrate and the wash liquid was transferred to a beaker, in which was performed the first deposition of silicic acid, and evaporated to dryness. The dry residue moistened with 5−7 cmof hydrochloric acid and again evaporated to dryness. The dry residue is heated for 1 h at 130 °C — 140 °C. To the dry residue poured 8−10 cmof hydrochloric acid, heated for 3−5 min, poured 80−100 cmof hot water, heated to dissolve the salts and then almost to a boil. Silicic acid is filtered off, the filter «white ribbon», with the addition of a small amount of ashless filtrowanie mass. Precipitate was washed 3−5 times with hot hydrochloric acid 1:20 and 2−3 times with hot water. Filters with basic and advanced selected sediments was placed in a platinum crucible, dried and incinerated. The precipitate was calcined at 1000−1100 °C.

The crucible with residue was cooled in a desiccator and weighed. The residue moistened with 2−3 drops of water, add 3−4 drops of sulfuric acid 1:1, 3−5 cmhydrofluoric acid and allowing the solution to boil gently evaporate the contents of the crucible to dryness. The residue in the crucible was calcined at 1000 °C — 1100 °C, cooled in a desiccator and weighed.

In both cases the residue in the crucible is calcined to constant weight.

The sulfuric acid method. 50 cmof the solution And placed in a beaker with a capacity of 250−300 cm, 25−30 cm pour thesulfuric acid 1:2, heated until the appearance of its vapors, is heated for 3−5 min, then cooled. Carefully add 10 cmof hydrochloric acid, heated for 3−5 min and cooled. While stirring, add small portions of 80−100 cmof hot water. Beaker cover watch glass and heat the solution nearly to boiling.

The precipitate was filtered off on filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass. The filter cake was washed 3−5 times with hot hydrochloric acid 1:20 and 2−3 times with hot water. The filter with the precipitate saved. The filtrate and the wash liquid was transferred to a beaker, which produced the first deposition of silicic acid, heated until the appearance of sulphuric acid fumes, heat another 3−5 minutes, then cooled. Add 10 cmof hydrochloric acid, heated for 3−5 min and carefully, with stirring, poured in small portions 80−100 cmof hot water.

Beaker cover watch glass and heat the solution nearly to boiling. The precipitate was filtered off on filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass, washed 3−5 times with hot hydrochloric acid 1:20 and another 2−3 times with hot water. Filters with basic and advanced selected sediments was placed in a platinum crucible, dried and incinerated.

The precipitate was calcined at 1000 °C — 1100 °C. After cooling in a desiccator, the crucible with the sediment weighed. The residue moistened with 2−3 drops of water, add 3−4 drops of sulfuric acid 1:1, 3−5 cmhydrofluoric acid and allowing the solution to boil gently evaporated to dryness. The residue in the crucible was calcined at 1000 °C — 1100 °C, cooled in a desiccator and weighed.

In both cases the residue in the crucible is calcined to constant weight.

The mass concentration of silica, grams contained in 1 cmof a solution of silicate of sodium (), calculated by the formula

,

where is the mass of the crucible with the precipitate of silicon dioxide, g;

 — weight of crucible with residue after treatment with hydrofluoric acid, g;

 — the mass of the crucible with the sediment in a control experiment, g;

 — the mass of the crucible with the residue in a control experiment after treatment with hydrofluoric acid, g;

0,4674 — the ratio of silicon dioxide on silicon;

50 — volume of the standard solution A taken for the experience, see.

Solution B is prepared before consumption. 10 cmstandard solution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof solution B contains 0,00001 g of silicon.

(Changed edition, Rev. N 2, 3, 4).

2.3. Analysis

0.1 g of steel placed in a beaker or flask with a capacity of 100 cm, flow 10 cmof hydrochloric acid (1:3) and 1 cmof nitric acid with the mass fraction of silicon of up to 0.40% or 20 cmof hydrochloric acid (1:3) and 1 cmof nitric acid with the mass fraction of silicon of 0.40%-0,80%. Cover beaker or flask with a watch glass and heated to dissolve the sample, not allowing to boil. Pour 10 cmof water and boil for 2−3 min to remove the oxides of nitrogen.

If the steel does not dissolve in these acids, the sample may be dissolved in a mixture of hydrochloric and nitric acids (1:1), (3:1) or in a mixture of nitric and hydrochloric acids (1:6), (1:8).

The amount of added to dilute the sample of hydrochloric and nitric acids should not exceed the above.

The filter with precipitate was placed in a platinum crucible, dried and incinerated. The precipitate was calcined at 900 °C — 1000 °C. After cooling in a desiccator, the contents of the crucible fused with 0.5 g of sodium carbonate at 1000 °C — 1100 °C.

The crucible with the melt is cooled, rinse the outer wall of the crucible with water and placed in a beaker with a capacity of 200 cm. The smelt is leached in 20 to 25 cmof water when heated. The solution was cooled and added to the main filtrate; topped to the mark with water and mix. The resulting solution was filtered through a dry filter «white ribbon» in a conical flask with a capacity of 100 cm, discarding the first portions of the solution, previously they was washed flask.

In two volumetric flasks with a capacity of 100 cmplaced at 20 cmsolution, if a contained 0.05%-0,40% silicon, or 10 cmof the solution, if the steel contains 0,40%-0,80% silicon. In the flask poured 50 cmof water and in one of them add 10 cmof a solution of molybdate of ammonium. The solution of the second flask is used as a solution of comparison. The appearance of sediment or slight opalescence when added molybdate of ammonium indicates a pH of 1.3−1.5, is required for the formation kremneftoristogo complex.

15 min after the addition of molybdate ammonium solution poured in the following order: 5 cmof sulphuric acid is 4:5, 5 cm8% solution of oxalic acid and 5 cm2% ascorbic acid solution. After each addition of reagent solutions are mixed. The solutions were topped up to the mark with water, mixed and incubated for 30 min at (20±4) °C.

The optical density of the solutions measured on the spectrophotometer at 810 nm in a cuvette with the thickness of the absorbing layer of 10 mm or photoelectrocolorimeter at (630±10) nm in a cuvette with the thickness of the absorbing layer is 20 mm.

The amount of silicon in milligrams, as amended by the control of the experience is determined by the calibration schedule.

(Changed edition, Rev. N 3).

2.3.1. Construction of calibration curve

In seven volumetric flasks or beakers with a capacity of 100 cmis placed 0.1 g carbonyl iron, poured 10 cmof hydrochloric acid of 1:3 and heated, avoiding boiling point of the solution, 3−5 min. Pour 1 cmof nitric acid and continue the heating until complete dissolution of iron. Then pour 10 ml of water and boil for 2−3 min to remove the oxides of nitrogen. The solutions were cooled.

Mud poured a certain number of milliliters of standard solution B sodium silicate containing 0,02; 0,05; 0,10; 0,20; 0,30; 0,40 mg silicon. Seventh a volumetric flask or a glass is used for the reference experiment. Upon dissolution of the batches in the beakers the solutions are transferred to volumetric flasks with a capacity of 100 cm, top up with water to a label and mix. The resulting solutions are filtered through dry filters «white ribbon» in a conical flask with a capacity of 150−200 ml, discarding the first portions of the solution, previously they was washed flasks.

In two volumetric flasks with a capacity of 100 cmplaced at 20 cmof the filtrate poured in 50 cmof water and in one of them add 10 ml of molybdate ammonium solution. The solution of the second flask is used as a solution of comparison. The appearance of sediment or slight opalescence when added molybdate of ammonium indicates a pH of 1.3−1.5, is required for the formation kremneftoristogo complex.

15 min after the addition of molybdate ammonium solution poured with stirring in the following order: 5 cmof sulphuric acid is 4:5, 5 cmof a solution of oxalic acid and 5 cmof ascorbic acid solution. Top up with water to a label, mix and stand for 30 min at (20±4) °C.

Absorbance measured on the spectrophotometer at 810 nm in a cuvette with the thickness of the absorbing layer of 10 mm or photoelectrocolorimeter at (630±10) nm in a cuvette with the thickness of the absorbing layer is 20 mm.

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 values of the mass of silicon to build the calibration graph.

(Changed edition, Rev. N 2, 3).

2.4. Processing of the results

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

,

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

 — the mass of silicon was found in the calibration schedule, mg.

(Changed edition, Rev. N 2).

2.4.2. Norms of accuracy and norms control the accuracy of determining the mass fraction of silicon are shown in table.1.

Table 1

(Changed edition, Rev. N 4).

3. GRAVIMETRIC METHOD FOR DETERMINATION OF SILICON (0,10−7,00%)

3. GRAVIMETRIC METHOD FOR DETERMINATION OF SILICON (0,10%-7,00%)

3.1. The essence of the method

The method is based on the isolation of silicon in the form of polymerized silicic acid of the acid solution, dehydration and weighing the obtained silicon dioxide.

3.2. Reagents and solutions

Hydrochloric acid according to GOST 14261 and diluted 1:1, 1:10, 1:50.

Nitric acid according to GOST 4461.

Sulfuric acid according to GOST 4204, diluted 1:1 and 1:4.

Hydrofluoric acid (hydrofluoric) according to GOST 10484.

Kasota chlorine minimum density of 1.54 g/cm.

Ammonium radamisty, GOST 19522, 50 g/DM; 5% solution.

The anhydrous sodium carbonate according to GOST 83.

Potassium carbonate — sodium carbonate according to GOST 4332.

(Changed edition, Rev. N 2, 3, 4).

3.3. Analysis

3.3.1. The weight of the portion and the number of acids used for dissolution, are given in table.2.

Table 2

(Changed edition, Rev. N 1, 3).

3.3.2. (Deleted, Rev. No. 3).

3.3.3. Determination of silicon in steels containing up to 5% tungsten and up to 10% chromium-sulfuric acid method

Sample steel (n.3.3.1) is placed in a beaker with a capacity of 250−300 cmand pour the sulfuric acid 1:4. Beaker cover watch glass and heated until complete decomposition of sample. The solution is poured in small portions of 3−5 cmof nitric acid, evaporated with moderate heat to the appearance of sulphuric acid fumes and heat for another 3−5 min.

If the linkage is not soluble in sulfuric acid, it is dissolved in 30−50 cmof a mixture of hydrochloric and nitric acids in the ratio 3:1. Then pour the 40−60 cmsulphuric acid 1:4, heated to the emergence of vapours and heat for another 3−5 min.

A glass of cool, add 10 cmof hydrochloric acid and carefully, with stirring, poured in small portions 130−150 cmof hot water. Beaker cover watch glass, heat to dissolve the salts and then almost to a boil.

The precipitate was filtered off on filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass. The filter cake is washed with hot hydrochloric acid 1:20 to the absence in the wash liquid of ferric iron ions (for reaction with ammonium radamisty) and 2−3 times with hot water. The filter with the precipitate saved.

The filtrate and the wash liquid was transferred to a beaker, which held the dissolution of sample is heated to the appearance of sulphuric acid fumes and heat for another 3−5 min.

A glass of cool, add 10 cmof hydrochloric acid, heated for 3−5 min and carefully, with stirring, poured in small portions 130−150 cmof water. Beaker cover watch glass, heat to dissolve the salts and then almost to a boil.

The precipitate was filtered off on filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass is washed with hot hydrochloric acid 1:20 to the absence in the wash liquid of ferric iron ions (for reaction with ammonium radamisty) and 2−3 times with hot water.

Filters with basic and advanced selected sediments was placed in a platinum crucible, dried and incinerated. The precipitate was calcined at 1000 °C — 1100 °C.

After cooling in the desiccator the crucible and precipitate are weighed. The residue moistened with 2−3 drops of water, add 3−4 drops of sulfuric acid 1:1 (in the presence in the precipitate of oxides of tungsten, niobium etc. add 4−6 drops of sulfuric acid 1:1), poured 3−5 cmhydrofluoric acid and allowing the solution to boil gently evaporate the contents of the crucible to remove vapors of sulfuric acid. The residue in the crucible was calcined at 1000 °C — 1100 °C (if steel contains more than 0.5% tungsten, the residue in the crucible was calcined at 750 °C — 800 °C), cooled in a desiccator and weighed.

In both cases the residue in the crucible is calcined to constant weight.

(Changed edition, Rev. N 1, 2, 3).

3.3.4. Determination of silicon in steels containing up to 1% tungsten, CHLOROSILANES method

Sample steel (n.3.3.1) is placed in a beaker with a capacity of 250−300 cm, 20−30 cm, pour themixture of hydrochloric and nitric acids in the ratio 3:1 or 40 cmof a mixture of hydrochloric acid, diluted 1:1 nitric acid, diluted 3:1, and heated to complete decomposition of the sample. Pour the 20−30 cmof perchloric acid with a density of 1.65 and is heated until the appearance of its vapors. Beaker cover watch glass, and heated for 15−20 min.

The solution was cooled, cautiously, with stirring, poured 120−130 cmof hot water, heated to dissolve the salts and then almost to a boil.

The precipitate was filtered off on filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass. The precipitate is washed with hot hydrochloric acid 1:20 to the absence in the wash liquid of ferric iron ions (for reaction with ammonium radamisty) and another 2−3 times with hot water. The filter with the precipitate saved.

The filtrate and the wash liquid was transferred to a beaker, which was performed dissolving the sample. The solution was evaporated until the appearance of fumes of perchloric acid and heated for 15−20 min. the Glass is cooled, gently, while stirring, pour 120−130 cmof hot water, heated to dissolve the salts and then almost to a boil.

The precipitate was filtered off on filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass. The filter cake is washed with hot hydrochloric acid 1:20 to the absence in the wash liquid of ferric iron ions (for reaction with ammonium radamisty), then 2−3 times with hot water.

Filters with basic and advanced selected sediments was placed in a platinum crucible, dried and incinerated. The precipitate was calcined at 1000 °C — 1100 °C to constant weight. After cooling in the desiccator the crucible and precipitate are weighed. The residue moistened with 2−3 drops of water, add 3−4 drops of sulfuric acid 1:1 (in the presence in the precipitate of oxides of tungsten, niobium etc. add 4−6 drops of sulfuric acid 1:1), poured 3−5 cmhydrofluoric acid and allowing the solution to boil gently evaporate the contents of the crucible to remove vapors of sulfuric acid. The crucible was calcined at 1000 °C — 1100 °C (if steel contains more than 0.5% tungsten, the residue in the crucible was calcined at 750 °C — 800 °C), cooled in a desiccator and weighed.

In both cases, the precipitate is calcined to constant weight.

(Changed edition, Rev. N 2, 3).

3.4. Processing of the results

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

,

where is the mass of sample, g;

 — the mass of the crucible with the precipitate of silicon dioxide, g;

 — weight of crucible with residue after treatment with hydrofluoric acid, g;

 — the mass of the crucible with the precipitate obtained in control experiment, g;

 — the mass of the crucible with the residue obtained in a control experiment after treatment with hydrofluoric acid, g;

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

(Changed edition, Rev. N 2).

3.4.2. Norms of accuracy and norms control the accuracy of determining the mass fraction of silicon are shown in table.1.

(Changed edition, Rev. N 4).