GOST 2604.3-83

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  ГОСТ 2604.3-83

GOST 2604.3−83 Cast iron alloy. Methods for determination of silicon (with Amendments No. 1, 2)

GOST 2604.3−83

Group B09

INTERSTATE STANDARD

ALLOY CAST IRON

Methods for determination of silicon

Alloy cast iron. Methods for determination of silicon

ISS 77.080.10
AXTU 0809

Date of introduction 1984−07−01

INFORMATION DATA

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

DEVELOPERS

Yu. S., Chernobrovina, T. A. Butenko, P. A. Parkhomenko, A. S. Grzegorzewski, V. P. Korzh, J. B. Kulikov, B. A., Sorochinskaya, L. N. Novak

2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from 08.07.83 N 680

3. REPLACE GOST 2604.3−77

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

6. EDITION with Amendments No. 1, 2 approved in March 1986, December 1988 (IUS 6−86, 3−89)


This standard sets the photometric method for the determination of silicon (with a mass fraction of from 0.05 to 5.0%), a gravimetric method for the determination of silicon (with a mass fraction of from 0.10 to 20.0%) in the doped iron.

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 28473.

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

the discrepancy between the results of two (three) parallel dimensions should not exceed (with a confidence probability =0,95) values () in table*;

played in the standard sample, the value of the mass fraction of the element must not vary from certified more than acceptable (at a confidence level =0,85) value in table*.
_________________
* The text matches the original. — Note the CODE.

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 the table.

(Added, Rev. N 2).

2. PHOTOMETRIC METHOD FOR DETERMINATION OF SILICON

2.1. The essence of the method

The method is based on formation of yellow kremneftoristogo complex, 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 when dissolved in hydrochloric acid and lime when dissolved in sulfuric acid. Michalopolous complex is formed only at the boiling point of the solution.

(Changed edition, Rev. N 1).

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Hydrochloric acid according to GOST 3118, diluted 1:3.

Nitric acid according to GOST 4461 and diluted 1:3,5.

Oxalic acid according to GOST 22180, solution with the mass concentration of 0.08 g/cm.

Ascorbic acid, a solution with a mass concentration of 0.02 g/cm, freshly prepared.

Citric acid according to GOST 3652.

A mixture of citric and ascorbic acids, freshly prepared: 2.5 g citric and 0.5 g of ascorbic acid dissolved in 100 cmof water.

Sulfuric acid according to GOST 4204, diluted 1:1 and 1:20.

Carbonyl iron, OS. h

Ammonium molybdate according to GOST 3765, a solution with a mass concentration of 0.05 g/cm, recrystallized from alcoholic solution.

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 a dense filter of «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 a medium density filter «white ribbon». The crystals are washed two or three times with ethyl alcohol portions at 20−30 cmand dried in air.

Ammonia water according to GOST 3760.

The technical rectified ethyl alcohol according to GOST 18300.

Silicon dioxide according to GOST 9428.

Potassium carbonate — sodium carbonate according to GOST 4332.

Sodium carbonate according to GOST 83.

Sodium silicate standard solution, the mass concentration of the silicon 0.0002 g/cm: 0,2140 g of silicon dioxide, calcined to constant weight at 1000−1100 °C, placed in a platinum crucible, add 2 g of sodium carbonate, stirred, cover with lid and alloys at 1000−1100 °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 500 cm, the filter was washed three to five 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 container.

Determination of the mass concentration of a standard solution: 50 cmstandard solution is placed in a beaker with a capacity of 300−400 cm. Further, determination is carried out according to claim 3.3.

Mass concentration () of standard solution expressed in g/cmsilicon, 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;

0,4675 — the ratio of silicon dioxide on silicon;

50 — volume of standard solution taken for analysis, cm.

(Changed edition, Rev. N 1, 2).

2.3. Analysis

2.3.1. Determination of silicon (0,05−1,0%)

The weight of cast iron weighing 0.2 g was placed in a beaker or conical flask with a capacity of 100 cm, flow 20 cmof hydrochloric acid and heated in a boiling water bath for 3−5 min. Pour 1 cmof nitric acid and continue the heating until complete dissolution of the sample. Then pour 10 cmof water and boil for 2−3 min to remove the 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.

The filter with precipitate was placed in a platinum crucible, dried and incinerated. The precipitate is calcined at 900−1000 °C. After cooling in a desiccator, the contents of the crucible fused with 0.5 g of sodium carbonate or potassium carbonate-sodium at 1000−1100 °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, made up 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 150−200 cm, discarding the first portions of the solution, previously they was washed flask.

In two volumetric flasks with a capacity of 100 cmplaced at 10 cmof the solution, in 50 cmof water, and in one of them add 10 cmof molybdate ammonium solution; 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 flow sequentially through 5 cmof sulphuric acid (1:1), 5 cmof a solution of oxalic acid and 5 cmof ascorbic acid solution. After each addition of reagent solutions are mixed, made up to the mark with water, mixed and incubated for 20 min at (20±4) °C.

The optical density of the solutions measured on the spectrophotometer at a wavelength of 830 nm or photoelectrocolorimeter at a wavelength (630±20) nm (red filter) in a cell of optimal size, relative to the comparison solution.

The found value of the optical density of the investigated solution with the adjusted control experience with a lot of silicon for the calibration schedule.

(Amended And

ZM. N 2).

2.3.2. Construction of calibration curve

In eight glasses with a capacity of 100 cmis placed 0.2 g carbonyl iron and in seven of the eight 0,5; 1,0; 2,0; 4,0; 6,0; 8,0 and 10.0 cmstandard solution silicon, which corresponds to 0,00001; 0,00002; 0,00004; 0,00008; 0,00012; 0,00016 and 0,00020 g of silica in 100 cmfotometricheskogo solution. The solution in the eighth beaker, containing silicon, is used as a solution of comparison.

In every glass poured 20 cmof hydrochloric acid and heated in a boiling water bath for 3−5 min, then 1 cmof nitric acid and continue the heating until complete dissolution of the sample, then pour 10 cmof water and boil for 2−3 min to remove the oxides of nitrogen.

The solutions from the beakers was transferred to volumetric flasks with a capacity of 100 cm, cooled, made up to the mark with water and mix.

Eight volumetric flasks with a capacity of 100 cmis placed aliquote parts of a solution at 10 cm, 50 cmwater and 10 cmof a solution of molybdate of ammonium. 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.

Further, determination is carried out according to claim 2.3.1.

On the found values of optical density of analyzed solution with the adjustment in the reference experiment and the corresponding values of the concentrations of silicon build the calibration graph.

(Changed edition, Rev.

N 1).

2.3.3. Determination of silicon (0,05−5,0%).

A portion of the cast iron mass in accordance with table.1A is placed in a beaker with a capacity of 200−250 cm, flow 50 cmof sulphuric acid (1:20), covered with a glass watch glass and dissolved in low boiling. Then pour 10 cmof nitric acid (1:3,5) and boil for 5 minutes, cooled and transferred to a volumetric flask with a capacity of 200 cm, made up to the mark with water, mixed and filtered in a dry flask through a dry filter «white ribbon», discarding first portion of filtrate. Select aliquote part of the solution in two volumetric flasks with a capacity of 100 cmin accordance with table.1A, in one of them pour 5 cmof a solution of molybdate of ammonium, the second 5 cmof water, stirred and incubated for 5 min with a mass fraction of silicon up to 0.5% for 3 min with a mass fraction of silicon of more than 0.5%. Then both flasks pour 5 cmof sulphuric acid (1:1), 5 cmof a mixture of citric and ascorbic acids and incubated for 10 min with a mass fraction of silicon up to 0.5% and 5 min with a mass fraction of silicon of more than 0.5%.

Table 1A

The solutions in the flasks was adjusted to the mark and mix.

The solution of the second flask is solution comparisons.

The optical density of the solutions measured on the spectrophotometer at a wavelength of 830 nm or photoelectrocolorimeter at a wavelength (630±20) nm (red filter) in a cell of optimal size, relative to the comparison solution.

The found value of the optical density of the investigated solution with the adjusted control experience with a lot of silicon for the calibration schedule.

2.3.4. Construction of calibration graphs

In seven volumetric flasks with a capacity of 200 cmis placed sample of carbonyl iron in accordance with table.1A, pour 50 cmof sulphuric acid (1:20), dissolved in low boiling. Then pour 10 cmof nitric acid (1:3,5) and boiled for 5 min. the Solutions were cooled.

In six volumetric flasks consistently poured a standard solution of sodium silicate 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 cm(when the mass fraction of silicon from 0.05 to 0.5%) and 2,5; 5,0; 10,0; 15,0; 20,0; 25,0 cm(when the mass fraction of silicon is 0.5−5.0%), which corresponds to 0,000005; 0,00001; 0,00002; 0,00003; 0,00004; 0,00005 g and 0,0000125; 0,000025; 0,00005; 0,000075; 0,0001; 0,000125 g of silica in 100 cmfotometricheskogo solution.

The seventh flask is used for the reference experiment.

The solutions in volumetric flasks with a capacity of 200 cm, top up to the mark with water and mix.

From each flask taken aliquot part of the solution in a volumetric flask with a capacity of 100 cmin accordance with table.1A and further, determination is carried out according to claim 2.3.3.

On the found values of optical density of analyzed solution with the adjustment in the reference experiment and the corresponding values of the mass of silicon to build the calibration.

K.

2.3.3; 2.3.4. (Changed edition, Rev. N 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 silicon was found in the calibration schedule g;

the weight of cast iron, suitable aliquote part of the solution,

(Changed edition, Rev. N 1).

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

(Changed edition, Rev. N 2).

3. GRAVIMETRIC METHOD FOR DETERMINATION OF SILICON

3.1.The essence of the method

The method is based on the isolation of silicon in the process of condensation polymerization in the form of silicic acid, dehydration and further drying and calcining, and weighing the polymer obtained with anhydrous silicon dioxide.

3.2. Apparatus, reagents and solutions

A muffle furnace with heating temperature of 1000−1100 °C.

Sulfuric acid according to GOST 4204, and diluted 1:2.

Nitric acid according to GOST 4461.

The mixture of acids to dissolve: 2 DMsulphuric acid carefully poured a thin stream with continuous stirring, 5.5 DMwater. After cooling the solution was added 1.5 DMnitric acid and stirred.

Hydrochloric acid according to GOST 3118 and diluted 1:1 and 1:20.

Ammonium radamisty according to GOST 19522, solution with a mass concentration of 0.05 g/cm.

Hydrofluoric acid according to GOST 10484.

(Changed edition, Rev. N 1, 2).

3.3. Analysis

A sample of iron of mass 2.0 g (at a mass fraction of silicon from 0.10 to 1.0%), 1.0 g (with a mass fraction of silicon, more than 1.0 to 6.0%) or 0.5 g (at a mass fraction of silicon more than 6.0 to 20.0%) were placed in a glass with a capacity of 300−400 cm, carefully poured 30−75 cmof the mixture of acids and cover with a watch glass.

After the cessation of the violent reaction of a glass put on a hot stove and once dissolved, remove watch glass, rinse it with water and evaporated the solution until the appearance of sulphuric acid fumes who are given to stand for 2−3 min.

Remove the glass plate, allowed to cool and carefully poured along the walls of 15 cmof hydrochloric acid (1:1), gently stirring the contents of the glass. After 1−2 min go 120 cmof hot water, cover with a glass watch glass and heated to 60−70 °C, stirring occasionally with a glass rod to dissolve the salts.

The precipitate was filtered off on ashless filter «white ribbon» with the addition of a small amount of ashless filtrowanie mass and is washed with hot hydrochloric acid (1:20) to a negative reaction of wash water into iron (by reaction with ammonium radamisty) and then five or six times with hot water.

The filtrate together with the washings are again evaporated in the beaker, in which was held the first evaporation to release the vapors of sulfuric acid for 2−3 min. After cooling, poured 15 cmof hydrochloric acid (1:1), 120 cmof hot water and after heating to dissolve the precipitated salts filtered further precipitate silicic acid, washing it the same as mentioned above.

The combined precipitation was 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 carefully moistened with 3−5 drops of water priliva it on the walls of the crucible, add 5−7 drops of sulphuric acid and 3−5 cmhydrofluoric acid.

The contents of the crucible carefully evaporated until the termination of allocation of steams of sulfuric acid. The crucible is calcined in a muffle furnace at 1000−1100 °C to constant weight, cooled in a desiccator and weighed.

To make amendments to the content of silicon in the reagents with each batch of pipes under the same conditions is carried out at least two control experiments.

(Changed edition, Rev. N 2)

.

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 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;

0,4675 — the ratio of silicon dioxide on silicon;

 — the weight of the portion,

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

Table 1

3.4.1, 3.4.2. (Changed edition, Rev. N 2).