GOST 2604.4-87

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  ГОСТ 2604.4-87

GOST 2604.4−87 alloy Cast iron. Methods for determination of phosphorus

GOST 2604.4−87

Group B09

INTERSTATE STANDARD

ALLOY CAST IRON

Methods for determination of phosphorus

Alloy cast iron. Methods for determination of phosphorus

ISS 77.080.10
AXTU 0809

Date of introduction 1988−01−01

INFORMATION DATA

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

DEVELOPERS

V. L. Pilyushenko, Y. T. Hudik, T. Y., Kalinchenko, V. P. Korzh, M. A. Druzhinin, T. N. Poltoratskaya

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 19.02.87 N 281

3. REPLACE GOST 2604.4−77

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 2−92 of the Interstate Council for standardization, Metrology and certification (ICS 2−93)

6. REISSUE


This standard establishes photometric methods for determination of phosphorus in alloyed cast irons: when the mass fraction of phosphorus from 0.02 to 0.25% with the use of a reducing agent — ascorbic acid; mass fraction of phosphorus from 0.25 to 2.0% with the use of a reducing agent ions of bivalent iron.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 28473.

2. PHOTOMETRIC METHOD WITH USE of a REDUCING agent — ASCORBIC ACID (with a mass fraction of phosphorus from 0.02 to 0.25%)

2.1.The essence of the method

The method is based on the formation of the molybdophosphoric heteroalicyclic and restore it to complex compound, colored blue, ascorbic acid in the presence of potassium Armenonville (=880 nm, an optimal concentration of phosphorus 3−40 µg and 100 cmfotometricheskogo solution). The effect of the arsenic is removed by restoring it to trivalent sanitarily sodium.

2.2. Equipment and reagents

Drying Cabinet with a temperature of 105−110 °C.

Spectrophotometer or photoelectrocolorimeter.

A glassy carbon crucible, brand SU-2000−1C N 4 or bowl 550 glassy carbon SU-2000−1C N 2.

Nitric acid according to GOST 4461 and diluted 1:2.

Hydrochloric acid according to GOST 3118.

Sulfuric acid according to GOST 4204, diluted 1:1, and the solution with a molar concentration of 3 mol/DM: 84 cmsulphuric acid carefully poured with continuous stirring at 916 cmof water.

Potassium permanganate according to GOST 20490, solution with a mass concentration of 40 g/DM.

Sodium sanitarily 7-aqueous solution with a mass concentration of 200 g/DMor

sodium sanitarily according to GOST 195, a solution with a mass concentration of 100 g/DM.

The technical rectified ethyl alcohol according to GOST 18300.

Ammonium molybdate according to GOST 3765, recrystallized: 250 g ammonium molybdate are dissolved in 400 cmof water when heated to 70−80 °C, filtered through filter «blue ribbon», cooled to room temperature, poured, with stirring, 300 cmof ethyl alcohol, allow sediment to settle for 1 h and filtered it, the filter «white ribbon» placed in a Buchner funnel, using a water vacuum pump. The precipitate is washed two or three times with ethanol and dried in air.

Sernovodsky reagent: 7 g ammonium molybdate are dissolved in 400 cmof water, poured 84cm,sulfuric acid, mix, cool, add water to 1 DMand stirred. Hydrofluoric acid according to GOST 10484.

Ascorbic acid, a solution with a mass concentration of 40 g/DM.

Potassium armanavicius, a solution with a mass concentration of 3 g/DM.

Potassium phosphate according to GOST odnosemjannyj 4198, twice recrystallized:

100 g of reagent was dissolved in 150 cmof water when heated, pour the solution in a thin stream in a porcelain Cup, stirring vigorously with a glass rod. When the solution cools to room temperature, the Cup with the crystals cooled in cold running water, occasionally stirring with a glass rod. After cooling, the crystals are filtered off under vacuum on a porous glass plate funnel and washed two times for 5 cmof ice water. The filter cake is dissolved in four or five receptions in 80 cmof hot water and the crystallization repeated. The potassium phosphate crystals of single dried at (110±5) °C to constant weight.

The standard solutions of phosphorus

The solution And the mass concentration of phosphorus of 0.001 g/cm: 4,393 g of single potassium phosphate is dissolved in water and bring the solution volume up to 1 DM.

Solution B with a mass concentration of phosphorus 0,00001 g/cm; is prepared before use by diluting 10 cmsolution

Oura And to 1 DM.

2.3. Analysis

A portion of the cast iron (table.1) were placed in a glass or flat-bottomed flask with a capacity of 200−250 cm, poured 30 cmof nitric acid (1:2) and heated until dissolved.

Table 1

Added dropwise a solution of potassium permanganate before rolling the brown precipitate of manganese dioxide and boiled for 2−3 min. To the boiling solution are added dropwise a solution of sodium semitecolo to full enlightenment and boil to remove oxides of nitrogen.

If the charge of iron is not soluble in nitric acid, it is dissolved in 20−30 cmof a mixture of hydrochloric and nitric acids (3:1). After complete dissolution of the sample flow 10 cmof sulphuric acid (1:1) and evaporate the solution until fumes of sulfuric acid. Salt is dissolved by heating to 50−60 cmof water. Added dropwise a solution of potassium permanganate before rolling the brown precipitate of manganese dioxide and boiled for 2−3 min. To the boiling solution are added dropwise a solution of sodium semitecolo to full enlightenment and boil to remove oxides of nitrogen.

If the mass fraction of silicon in the analyzed sample exceeding 1.0%, the weight of cast iron placed in a glassy carbon crucible or glassy carbon 4 Cup 2 and dissolve in low heat in 20 cmof a mixture of hydrochloric and nitric acids (3:1) and 5 cmhydrofluoric acid. After complete dissolution of the sample flow 10 cmof sulphuric acid (1:1) and evaporate the solution until fumes of sulfuric acid.

Salt is dissolved by heating to 50−60 cmof water. To the boiling solution are added dropwise a solution of potassium permanganate (1−2 cm) before rolling the brown precipitate of manganese dioxide which is dissolved by adding dropwise a solution of sodium semitecolo to the disappearance of the color. The solution after destruction of the manganese dioxide is transferred to a volumetric flask with a capacity of 100 cm, cooled, adjusted to the mark with water, mix and filter through 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.

Depending on the mass fraction of phosphorus taken two aliquote part of the solution (table.1) in a volumetric flask with a capacity of 100 cm, flow 25 cmof water, to 3 cmsemitecolo sodium and boiled for 2−3 min. the Solutions were cooled, then into one of the flasks was added dropwise with continuous stirring 10 cmTernopoloblenergo reagent, the second 10 cmof sulfuric acid solution with molar concentration of equivalent of 3 mol/DM. Then both flasks pour 5 cmof ascorbic acid and 1 cmof a solution of potassium Armenonville, made up to the mark with water and mix.

Optical density of the solution measured after 45 min by the photoelectrocolorimeter at a wavelength (630±20) nm (red filter) or on the spectrophotometer at a wavelength of 880 nm relative to the solution not containing molybd

ATA ammonium.

2.4. Construction of calibration curve

To build a calibration curve in five or six volumetric flasks with a capacity of 100 cmplaced 1; 1,5; 2; 2,5 and 3 cmstandard solution B of single potassium phosphate, which corresponds to the 0.00001; 0,000015; 0,00002; and 0,000025 0,00003 g of phosphorus in 100 cmfotometricheskogo volume. Pour water up to 25 cm, and then poured with continuous stirring 10 cmcerromatoso reagent, 5 cmof ascorbic acid solution and 1 cmof a solution of potassium Armenonville, made up to the mark with water and then do as described in claim 2.3.

Sixth volumetric flask with a capacity of 100 cm, which added all the reagents, except standard solution of phosphorus, is used for the reference experiment on the phosphorus content in the reagents used in the construction of calibration curve and serves as a comparison solution

I.

2.5. Processing of the results

2.5.1. Mass fraction of phosphorus () in percent is calculated by the formula

,

where is the mass of phosphorus in aliquotes part, found on the calibration schedule g;

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

2.5.2. The absolute differences of the results of three parallel measurements at a confidence level =0.95 does not exceed the permissible values given in table.2.

Table 2

3. PHOTOMETRIC METHOD WITH USE of a REDUCING agent IONS of BIVALENT IRON (with a mass fraction of phosphorus from 0.25 to 2.0%)

3.1.The essence of the method

The method is based on the formation of the molybdophosphoric heteroalicyclic and restoring it by ions of bivalent iron in the presence of hydroxylamine to the compound, colored blue (=600−900 nm, the optimum phosphorus concentration 10−100 µg / 100 cmfotometricheskogo solution).

Arsenic is removed by Stripping in the form of the bromide, if the mass percentage is higher than 0,005%.

3.2. Equipment and reagents

Drying Cabinet with a temperature of 105−110 °C.

Spectrophotometer or photoelectrocolorimeter.

Nitric acid according to GOST 4461 and diluted 1:6.

Sulfuric acid according to GOST 4204, and the solution with molar concentration of equivalent of 8 mol/DM.

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

Potassium permanganate according to GOST 20490, solution with a mass concentration of 40 g/DM.

Hydroxylamine sulfate according to GOST 7298, solution with a mass concentration of 200 g/DM.

Alum salesonline, a solution with a mass concentration of 432,5 g/DM: 432,5 g of alum is dissolved in the presence of 20 cmof sulfuric acid in 1 DMof water.

Ammonium molybdate according to GOST 3765.

Sernovodsky reagent: 55,2 g of ammonium molybdate was dissolved with heating in 250 to 300 cmof water, filtered through a dense filter into a measuring flask with a capacity of 1 DM, and cooled slowly with continuous stirring poured 230cmsulfuric acid, the solution was cooled, adjusted to the mark with water and mix.

Ammonia water according to GOST 3760, diluted 1:1.

Ammonium bromide according to GOST 19275, a solution with a mass concentration of 100 g/DM.

Potassium phosphate according to GOST odnosemjannyj 4198, standard solutions A and B.

The solution And the mass concentration of phosphorus of 0.001 g/cm: 4,393 g of single potassium phosphate, dried at a temperature of (105±5) °C to constant weight, dissolve in water and bring the solution volume up to 1 DM.

Solution B with a mass concentration of phosphorus 0,00001 g/cm: prepared before use by diluting 10 cmof the solution And

up to 1 DM.

3.3. Analysis

3.3.1. The weight of cast iron weighing 0.2 g were placed in a glass or flat-bottomed flask with a capacity of 200−250 cm, poured 30 cmof nitric acid (1:6) and heated to dissolve sample.

If the charge of iron is not soluble in nitric acid, pour 5 cmof nitric acid and 15 cmof hydrochloric acid and heated until dissolved. The solution was evaporated to wet condition salts, then pour 20 cmof nitric acid and again evaporate the solution to wet condition salts, after which pour 5−10 cmof nitric acid, 15−20 cmof water and heated to dissolve the salts

If the mass fraction of arsenic in the analyzed cast iron of more than 0,005%, it is removed by Stripping. For this solution after dissolution of the sample was evaporated to dryness. To the dry residue poured 10 cmof hydrochloric acid and again evaporated to dryness. This operation is repeated two times. The dry residue was dissolved with heating in 15 cmof hydrochloric acid (1:1), poured 10 cmof a solution of bromide of ammonium, and evaporate the solution to dryness. Then poured 30 cmof nitric acid (1:6) and heated to dissolve the salts.

To the boiling solution are added dropwise a solution of potassium permanganate before rolling the brown precipitate of manganese dioxide. To the hot solution was added dropwise a solution of hydroxylamine to bleaching. Boil the solution for 1−2 min to remove oxides of nitrogen, cooled and transferred to a volumetric flask with a capacity of 100 cm, adjusted 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 filtrate, previously they was washed flask.

Select two aliquote parts of a solution of 5 cmin a conical flask with a capacity of 100 cm, flow at 20−25 cmwater and 2 cmof a solution of geletain

s alum.

3.3.2. The solutions were neutralized with ammonia, adding it dropwise until the loss of its dregs of ferric hydroxide, then add 5 cmof a solution of hydroxylamine. The contents of the flask heated until disappearance of the yellow color of the solution.

If the solutions remain yellow color, add 1−2 drops of ammonia solution. The appearance of turbidity it is dissolved by adding 1−2 drops of hydrochloric acid (1:1). The solutions were cooled and transferred to volumetric flasks with a capacity of 100 cm. In one of the flasks was added with continuous stirring 8cmmortar Ternopoloblenergo reagent, the second — 8 cmof sulfuric acid solution with molar concentration of equivalent of 8 mol/DM. The contents of the flask topped up to the mark with water and mix. The solution in the second flask serves as a solution comparison.

The value of the optical density of the solution measured on a spectrophotometer at a wavelength of 830 nm on a photoelectrocolorimeter at a wavelength (630±20) nm (red filter) in a ditch optimum size.

The found value of the optical density minus the optical density of the solution in the reference experiment, find the mass of phosphorus in grams on the calibration schedule.

When conducting the reference experiment on the content of phosphorus reagents to aliquots pieces add 2cmof a solution of alum salesonline.

3.4. Construction of calibration curve

To build a calibration curve in eight of the nine volumetric flasks with a capacity of 100 cmplaced 2,5; 5; 7,5; 10; 12,5; 15; 17,5 and 20 cmstandard solution B of single potassium phosphate, which corresponds to 0,000025; 0,00005; 0,000075; 0,0001; 0,000125; 0,00015; 0,000175 and 0.0002 g of phosphorus in 100 cmfotometricheskogo solution.

Ninth a volumetric flask with a capacity of 100 cm, which added all the reagents, except standard solution of phosphorus, is used for the reference experiment on the phosphorus content in the reagents used in the construction of calibration curve, and is solution comparisons.

In each flask poured 20−25 cmwater 2 cmgentoomaniac solution of alum and further analysis is carried out as specified in clause 3.3.2.

3.5. Processing of the results

3.5.1. Mass fraction of phosphorus () in percent is calculated by the formula

,

where is the mass of phosphorus in aliquotes part, found on the calibration schedule g;

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

3.5.2. The absolute differences of the results of three parallel measurements at a confidence level =0.95 does not exceed permissible values, specified in table.3.

Table 3