GOST 22536.4-88

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  ГОСТ 22536.4-88

GOST 22536.4−88 carbon Steel and unalloyed cast iron. Methods for determination of silicon

GOST 22536.4−88

Group B09

STATE STANDARD OF THE USSR


CARBON STEEL AND UNALLOYED CAST IRON

Methods for determination of silicon

Carbon steel and unalloyed cast iron.
Methods for determination of silicon

AXTU 0809

Valid from 01.01.90
to 01.07.95*
______________________________
* Expiration removed
Protocol N 4−93 inter-state Council
for standardization, Metrology and certification.
(IUS N 4, 1994). — Note the CODE.

INFORMATION DATA

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

PERFORMERS

D. K. Nesterov, PhD. tech. Sciences; S. I. Rudyuk, PhD. tech. Sciences; S. V. Spirina, PhD. chem. Sciences (head of subject); V. F. Kovalenko, PhD. tech. science; N. N. Gritsenko, PhD. chem. Sciences; L. I. birch; O. M. Kirzhner

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 25.08.88 N 3018

3. REPLACE GOST 22536.4−77

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the gravimetric (if the mass fraction of silicon of from 0.1 to 4.0%) and photometric (at a mass fraction of silicon of from 0.005 to 1.0%) methods for determination of silicon.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 22536.0−87.

1.2. The error of the result of the analysis (under confidence probability =0,95) does not exceed the limit given in table. 1 under the conditions of:

the difference between the two (three) parallel dimensions should not exceed (with a confidence probability =0,95) of the values given in table. 1;

played in the standard sample, the value of the mass fraction of silicon should not vary from certified more than acceptable (at a confidence level =0,85) the value given in table. 1.

If any of the above conditions, a second measurement of the mass fraction of silicon. If in repeated measurements the precision requirement of the results are not met, the results of the analysis recognize the incorrect measurements cease to identify and eliminate the causes of violation of the normal course of analysis.

The divergence of the two middle results of an analysis performed under different conditions (for example, when the control intralaboratory reproducibility) shall not exceed (with a confidence probability =0,95) of the values given in table. 1.

Table 1

2. GRAVIMETRIC METHOD FOR DETERMINATION OF SILICON

2.1. 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 of the obtained silica.

2.2. Equipment and reagents

Electric resistance furnace laboratory.

Hydrochloric acid by the GOST 3118−77 or GOST 14261−77 and diluted 1:1 and 1:50.

Sulfuric acid GOST 4204−77 and diluted 1:1, 1:2 and 1:4.

Nitric acid GOST 4461−77 or GOST 11125−84 and diluted 1:2.

Perchloric acid, h. e. a. or H. h

Hydrofluoric acid according to GOST 10484−78.

Ammonium radamisty according to GOST 19522−74, a solution with a mass concentration of 50 g/DM.

Technical articles made of noble metals and alloys according to GOST 6563−75.

2.3. Analysis

2.3.1. The weight of steel or cast iron depending on the mass fraction of silicon (see table. 2) is placed in a beaker with a capacity of 250−300 cmand carry out the dissolution of the sample and the allocation of silicic acid according to one of the following methods.

Table 2

2.3.2. The sulfuric acid method

In a glass pour the linkage 15−25 cmof sulphuric acid (1:4) and heated until complete dissolution of the sample. Add nitric acid until the termination of foaming solution and 20 cmof sulphuric acid (1:1). The contents of the beaker evaporated to the appearance of white sulphuric acid fumes, which give to stand 5 to 8 minutes Then the Cup is removed from the plate, cooled and cautiously on the walls of the glass pour 10 cmof hydrochloric acid, gently stirring the contents. After 4−5 min flow 50−70 cmof hot water, cover with a glass watch glass and heated with stirring to dissolve the salts. The precipitate is immediately filtered off on the filter «white ribbon» with the addition of a small amount filtrowanie mass and is washed with hot hydrochloric acid (1:50) to a negative reaction of wash water into iron (the sample with the solution Rodenstock ammonium), and then 3−5 times with hot water. The filter with the precipitate saved.

The filtrate together with washings was transferred to a beaker, which was carried out dissolution, and additionally emit silicic acid, cutting evaporation of solution and filtration of the precipitate as shown above.

Filters with basic and advanced selected sediments was placed in a platinum crucible, dried, incinerated and calcined at a temperature of 1000−1100 °C to constant weight.

The crucible with residue was cooled in a desiccator and weighed. The precipitate is then moistened with 3−5 drops of water priliva it on the walls of the crucible, add 3−5 drops of sulfuric acid (1:2) and 3−5 cmhydrofluoric acid. The contents of the crucible carefully, not allowing to boil, evaporated before the termination of allocation of white fumes of sulfuric acid. Then, the crucible is calcined at a temperature of 1000−1100 °C to constant weight, cooled in a desiccator and weighed. Simultaneously with the execution of the analysis carried out control experience for contamination of reagents.

2.3.3. Serotonergically method

In a glass pour the linkage 30−50 cmof hydrochloric acid (1:1) and heated to dissolve the sample, then add dropwise a small amount of nitric acid until the termination of foaming solution and evaporated the solution to dryness.

Chilled dry residue moistened with 20 cmof sulphuric acid (1:1) and heated until the appearance of white sulphuric acid fumes who are given to stand for 3−5 min. the Glass is removed from the plate, cooled, carefully poured along the walls of the Cup 15 cmof hydrochloric acid, gently stirring the contents of the glass. After 1−2 minutes pour 120−130 cmof hot water and heated to dissolve the salts. Next, carry out the analysis as given in claim 2.3.2.

2.3.4. Chlorosilane method

In a glass pour the weighed 15−20 cmof nitric acid (1:2), cover the beaker glass and heated to dissolve sample. If the suspension dissolves poorly, should add 10−15cmof hydrochloric acid. After dissolution of the sample add 20−40 cmof perchloric acid, cover the glass again with glass and evaporated to the appearance of white fumes of perchloric acid, which is allowed to stand for 15−20 min. Then the glass is cooled, carefully poured 15−20 cmof hydrochloric acid, 50−70 cmof hot water, gently stirring the contents of the beaker, and heated to dissolve the salts at 60−70 °C (no more than 4−6 minutes). Next, carry out analysis as specified in claim 2.3.2.

2.4. Processing of the results

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

,

where is the mass of 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;

 — weight of sample, g;

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

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

3. PHOTOMETRIC METHOD FOR DETERMINATION OF SILICON

(when the mass fraction of silicon of from 0.01 to 0.05%)

3.1. The essence of the method

The method is based on the formation kremneftoristogo complex in slightly acidic environment, the restoration of ascorbic acid or thiourea in the presence of copper sulphate to kremneftoristogo blue and measuring optical density of colored solution at a wavelength of 810 nm.

3.2. Equipment and reagents

Photoelectrocolorimeter or spectrophotometer.

Sulfuric acid GOST 4204−77, diluted 1:3, 1:8.

Sodium carbonate GOST 83−79.

Oxalic acid according to GOST 22180−76, a solution with a mass concentration of 80 g/DM.

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

Ammonium molybdate according to GOST 3765−78, recrystallized from alcohol, the solution with a mass concentration of 50 g/DM.

Recrystallization of ammonium molybdate in 250 g of ammonium molybdate was dissolved in 400 cmof water at 70−80 °C. the Hot solution is filtered through filter «blue ribbon» in a glass contains 300 cmof ethyl alcohol. The solution was cooled and allowed to stand in running water for 1 h. Precipitated crystals are filtered off on a Buchner funnel with filter «white ribbon». The crystals are washed 2−3 times with ethanol in batches of 20−30 cmand dried in air.

Rectified ethyl alcohol according to GOST 5962−67 or GOST 18300−87.

Radio engineering carbonyl iron according to GOST 13610−79.

Ascorbic acid, a solution with a mass concentration of 50 g/DM, freshly prepared.

Thiourea according to GOST 6344−73, a solution with a mass concentration of 100 g/DM.

Copper sulfate (II) pativedha according to GOST 4165−78, a solution with a mass concentration of 4 g/lin sulphuric acid, diluted 1:3.

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

Gelatin GOST 11293−78, a solution with a mass concentration of 5−10 g/DM.

Silicon dioxide according to GOST 9428−73, calcined at 1000−1100 °C.

The rest of equipment and reagents according to claim 2.2.

Standard solutions of silicon

Solution a: a sample of the silica weighing 0,2140 g is fused in a platinum crucible with 2 g of anhydrous sodium carbonate. The smelt is leached in hot water, add 40 cmof sodium hydroxide solution with a mass concentration of 100 g/DM, the solution is transferred into a measuring flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.0001 gram of silicon.

Solution B: 50 cmsolution And placed in a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

1 cmof solution B contains 0,000020 g of silicon.

The solutions were stored in a plastic container.

The establishment of the mass concentration of a standard solution of silicon And 50 cmstandard solution is placed in a beaker with a capacity of 200 cm, 30 cm, pour thehydrochloric acid, evaporated to wet salts, add 10 cmof hydrochloric acid and again evaporated to moist salts. The beaker with the residue cooled to 50 °C, add 10 cmof hydrochloric acid and 1−2 cmgelatin solution. After 1 min add 2 cmof gelatin, stirred and allowed to settle 10 min, Then add 50 cmof hot water, stirring after 10 minutes, add as much hot water and again stirred, then filtered through the filter «white ribbon» filtrowanie ground, washed 8−10 times with hydrochloric acid (1:50), and 4−5 times with hot water.

The filter with precipitate was placed in a platinum crucible and then cooled as described in claim 2.3.2, including processing resulting precipitate of silicon dioxide hydrofluoric acid.

The mass concentration of a standard solution silicon (), expressed in g/cm, is calculated by the formula

,

where  — the volume of a standard solution of silicon taken for analysis, cm;

 — 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;

 — weight of sample, g;

0,4674 — the ratio of silicon dioxide on silicon

3.3. Analysis

3.3.1. The weight of steel or cast iron depending on the mass fraction of silicon (see table. 3) is placed in a conical flask with a capacity of 100 cm, pour 10−15 cmof sulphuric acid (1:8) and heated in a water bath, avoiding boiling point of the solution.

Table 3

After dissolution of the sample are added dropwise nitric acid until the termination of foaming solution and an excess of 1−2 drops. The walls of the flask washed with a small amount of water and the solution continued to heat for 3−5 minutes, avoiding boiling, to remove oxides of nitrogen. The solution was filtered through a filter «white ribbon» in a volumetric flask with a capacity of 100 cmand washed precipitate on the filter 3−4 times with small portions of hot water, made up to the mark with water and mix.

Two aliquote part of the solution (see table. 3) is placed in a volumetric flask with a capacity of 50 cm(with a mass fraction of silicon of from 0.01 to 0.05%) or 100 cm(with a mass fraction of silicon greater than 0.05%), one of them poured 10 cmof molybdate ammonium solution, stirred and kept for 15 min for the formation of yellow molibdenovojj of heteroalicyclic. Then in the flask is poured strictly in the order listed, stirring after adding each reagent: 10 cmof sulphuric acid (1:3), 5 cmof a solution of oxalic acid, 5 cmof a solution of ascorbic acid, made up to the mark with water and mix. After 30 min measure the optical density of colored solution with spectrophotometer at a wavelength of 810 nm or photoelectrocolorimeter with a filter having maximum transmission in the wavelength range of 600−650 nm. As a solution comparison aliquote apply the second part of the solution of the sample, which is added all the reagents, except molybdate of ammonium.

To restore the yellow shapes molibdenovojj of heteroalicyclic you can use thiourea in the presence of copper sulphate. In this case, after aging the solution for 15 min in a flask pour 10 cmof a solution of copper sulphate, mix, pour 5 cmof a solution of thiourea, made up to the mark with water and mix. After 3−5 min measure the optical density as above. As a solution comparison aliquote apply the second part of the solution of the sample, which is added all the reagents, except molybdate of ammonium.

Simultaneously with the execution of the analysis carried out control experience for contamination of reagents.

From the values of absorbance of the analyzed solution is subtracted the value of the optical density of the solution in the reference experiment.

A lot of silicon graphics find for the calibration or by comparison with a standard sample similar in composition to the sample and carried through all stages of the analysis

for.

3.3.2. Construction of calibration curve

When the mass fraction of silicon of from 0.01 to 0.05%

In seven conical flasks with a capacity of 100 cmis placed 0.5 g of carbonyl iron. Six of them added consistently 2; 4; 6; 9; 12; 15 cmstandard solution B, which corresponds to 0,000040; 0,000080; 0,000120; 0,000180; 0,000240; 0,000300 g silicon. The seventh flask is used for the reference experiment.

Flasks poured 10−15 cmof sulfuric acid solution (1:8), and then carry out the analysis according to claim 3.3.1.

When the mass fraction of silicon from 0.05 to 1%

In seven conical flasks with a capacity of 100 cmis placed 0.1−0.3 g of carbonyl iron depending on the sample the sample analyzed. Six of them added consistently 1; 3; 5; 7; 10; 12 cmstandard solution A, which corresponds to 0,00010; 0,00030; 0,00050; 0,00070; 0,00100; 0,00120 g silicon. The seventh flask is used for the reference experiment.

Flasks poured 10−15 cmof sulfuric acid solution (1:8) and then carry out the analysis according to claim 3.3.1.

On the found values of optical density and corresponding values of the mass of silicon to build the calibration graph. Allowed construction of calibration curve in the coordinates: the optical density is the mass fraction of silicon.

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 silicon in the sample was found in the calibration schedule g;

 — the weight of the portion,

3.4.2. Rules and regulations of the control of the accuracy of determining the mass fraction of silicon is given in table. 1.

4. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF SILICON IN THE FORM OF KREMNEFTORISTOGO COMPLEX (WHEN THE MASS FRACTION OF SILICON 0,005−0,1%)

4.1. The essence of the method

The method is based on the formation kremneftoristogo complex and restoring it to a molybdenum blue iron (II) formed by dissolving the sample the sample in a mildly acidic medium and measuring the optical density of the colored solution at a wavelength of 810 nm.

4.2. Equipment and reagents

Sulfuric acid GOST 4204−77, diluted 1:20.

The rest of the reagent according to claim.2.2 and 3.2.

4.3. Analysis

4.3.1. The weight of steel or cast iron depending on the mass fraction of silicon (see table. 4) is placed in a conical flask with a capacity of 100 cm, cover with a watch glass and dissolved in 15−20 cmof sulphuric acid (1:20) with moderate heating on a water bath.

Table 4

In order to avoid possible oxidation of iron to trivalent by dissolving the sample should avoid contact with oxidizing substances. After complete dissolution of the sample solution was filtered through fast filter «white ribbon» in a volumetric flask with a capacity of 100 cm, cooled, made up to the mark with water and mix. Aliquot part 10−20 cm(see table. 4) is placed in a volumetric flask with a capacity of 50 cm, and slowly poured 10 cmof molybdenic acid ammonium solution and stirred. After 3−5 minutes gently along the wall of the flask pour 10 cmof sulphuric acid (1:4), immediately topped up to the mark with water and mix.

After 15−20 min measure the optical density of the solution on the spectrophotometer at a wavelength of 810 nm or photoelectrocolorimeter with a filter having maximum transmission in the range of 600−650 nm. A solution of comparison used water. Simultaneously with the execution of the analysis carried out control experience for contamination of reagents.

From the values of absorbance of the analyzed solution is subtracted the value of the optical density of the solution in the reference experiment.

A lot of silicon graphics find for the calibration or by comparison with a standard sample similar in composition to the sample and carried through all stages of the analysis.

4.3.2. Construction of calibration curve

In seven conical flasks with a capacity of 100 cmplaced at 0.25−0.5 g carbonyl iron depending on the sample the sample analyzed. Six of them go consistently 1; 3; 6; 9; 12; 15 cmstandard solution B, which corresponds to 0,000020; 0,000060; 0,000120; 0,000180; 0,000240; 0,000300 g silicon. Flasks poured 15−20 cmof sulphuric acid (1:20) and lead further analysis as given in claim 4.3.1. The seventh flask is used to prepare 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. Allowed construction of calibration curve in the coordinates of the optical density — the mass fraction of silicon.

4.4. Processing of the results

4.4.1. Mass fraction () of the silicon percentage is calculated by the formula

,

where is the mass of silicon in the sample was found in the calibration chart;

 — the weight of the portion,

4.4.2. Norms of accuracy and norms control the accuracy of determining the mass fraction of silicon is given in table. 1.