GOST 11739.6-99

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  ГОСТ 11739.6-99

GOST 11739.6−99 Alloys aluminum casting and wrought. Methods of iron determination

GOST 11739.6−99

Group B59

INTERSTATE STANDARD

ALLOYS ALUMINIUM CAST AND WROUGHT

Methods of iron determination

Aluminium casting and wrought alloys. Methods for determination of iron

ISS 77.120.10
AXTU 1709

Date of introduction 2000−09−01

Preface

1 DEVELOPED by JSC «Russian Institute of light alloys» (JSC VILS), the Interstate technical Committee for standardization MTK 297 «Materials and semi-finished products of light alloys"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 16 from October 8, 1999)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated February 18, 2000 N 41-St inter-state standard GOST 11739.6−99 introduced directly as state standard of the Russian Federation from September 1, 2000

4 REPLACE GOST 11739.6−82

5 REISSUE. July 2005

1 Scope

This standard specifies the photometric (with a mass fraction of iron from 0.01% to 2.0%) and atomic absorption (at a mass fraction of iron from 0.005% to 2.0%) methods for determination of iron in aluminum casting and wrought alloys.

2 Normative references

The present standard features references to the following standards:

GOST 61−75 acetic Acid. Specifications

GOST 199−78 Sodium acetate 3-water. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 3778−98 Lead. Specifications

GOST 4038−79 Nickel (II) chloride 6-water. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4328−77 Sodium hydroxide. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5456−79 of Hydroxylamine hydrochloride. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 10484−78 hydrofluoric Acid. Specifications

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11069−2001 primary Aluminium. Brand.

GOST 25086−87 non-ferrous metals and their alloys. General requirements for methods of analysis

3 General requirements

3.1 General requirements for methods of analysis GOST 25086 with the Supplement.

3.1.1 the result of the analysis be the arithmetic mean of results of two parallel measurements.

4 Photometric method for determination of iron

4.1 the essence of the method

The method is based on dissolving the sample in hydrochloric acid solution or sodium hydroxide solution, the recovery of ferric iron to ferrous with hydroxylamine hydrochloride, the formation of the complex of bivalent iron with 1,10-phenanthroline or 2,2'-dipyridil at 4.5 and measuring the optical density of the solution at a wavelength of 510 nm.

Preventing the effect of copper, zinc and Nickel, which form from 1.10-phenanthroline or 2,2'-dipyridylium colorless complexes, eliminate the introduction of excessive amounts of reagent. In addition, the conditions of dissolution sample a half of copper separates from the iron. If in the sample the ratio of the mass fraction of copper and iron equal to or more than 100:1 left in aliquote part of the solution, the copper is separated by precipitation of lead tape.

4.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Drying oven with thermostat.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cm, the solutions of 1:1, 1:99 and a solution of 10 mol/DM: 820 cmof hydrochloric acid density of 1.19 g/cmmade up to volume of 1000 cm, cooled and stirred.

Sodium hydroxide according to GOST 4328, a solution of 200 g/DM. The solution is prepared and stored in a plastic container.

Ammonia water according to GOST 3760, a solution of 1:1.

1,10-phenanthroline (monohydrate or hydrochloride monohydrate): 0.25 g monohydrate or 0.30 g of the hydrochloride monohydrate is dissolved by weak heating in 80 cmof water, cool, add water to volume of 100 cm.

2,2'-dipyridil: 0.25 g of reagent was dissolved in 100 cmof water.

Hydroxylamine hydrochloride according to GOST 5456, solution 100 g/DM.

Sodium acetate according to GOST 199.

Acetic acid according to GOST 61 density of 1.05 g/cm.

Buffer solution with pH 4.5: 272 g sodium acetate and dissolve in 500 cmof water, filtered into a measuring flask with volume capacity of 1000 cm, 240 cm pouredacetic acid, made up to the mark with water and mix.

The mixture reagent: mix 100 cmof a solution of hydroxylamine hydrochloride, 100 CCof a solution of 1,10-phenanthroline or 2,2'-dipyridyl and 300 cmbuffer solution. The mixture of reagents is stored in a container made of dark glass not more than one month.

The indicator Congo red: 0.1 g of the reagent dissolved in 100 cmof water at low heat.

Indicator paper Congo: filters («white ribbon») is impregnated with a solution of the Congo, dried in a drying Cabinet at a temperature of (110±5)°C, sliced and stored in boxe. The paper is suitable for use within one month.

Lead according to GOST 3778 with a mass fraction of iron no more than 0.001% in the form of tape or wire.

Hydrogen peroxide according to GOST 10929.

Reactive iron (restored).

Standard solutions of iron.

Solution a: 0.1 g of iron is placed in a beaker with a capacity of 250 cm, 50 cm pour thehydrochloric acid solution of 1:1, cover with a watch glass and heated moderately until dissolved, add 2−3 drops of hydrogen peroxide and boiled for 3−5 min. the Solution was cooled to room temperature, rinse watch glass with water above the glass, which had a dissolution, and transfer the solution into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.0001 g of iron.

Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, pour 2 cmof hydrochloric acid 1:1, made up to the mark with water and mix. The solution is prepared before use.

1 cmof the solution contains 0,00001 g of iron.

4.3 Preparation for analysis

Before analysis the chips samples atminciai.

4.4 analysis

4.4.1 Weighed samples of 0.5 g depending on the mass fraction of silicon dissolved in one of the following ways.

4.4.1.1 When the mass fraction of silicon is less than 1.5%

Weighed sample is placed in a conical flask with a capacity of 100 cm, flow 15 cmof a hydrochloric acid solution 1:1, cover with a watch glass or funnel and dissolved with moderate heat, wash the walls of the bulb 10 cmof water and boiled for 5 min, cooled to room temperature the solution is poured water to a volume of 50 cmand filtered the solution through the filter medium density (white ribbon) in a volumetric flask with a capacity in accordance with table 1, the filter is washed 2−3 times with hydrochloric acid 1:99 in portions of 5−10 cm, top up with water to the mark and mix.


Table 1

4.4.1.2 When the mass fraction of silicon more than 1.5%

Weighed samples were placed in a glass made of PTFE or glassy carbon with a capacity of 100 cm, pour in small portions of 20 cmof sodium hydroxide solution and dissolved first at room temperature, then evaporated with moderate heat to a thick syrupy consistency. The side of the Cup washed with 20−25 cmof water, poured carefully in small portions with continuous stirring, 20 cmsolution of hydrochloric acid molar concentration of 10 mol/DMand boiled for 3−5 min until a clear solution is poured 20−25 cmof water and continue heating for 2−3 min.

In the presence of sediment copper cooled solution was filtered through a filter medium density («white ribbon»), the filter was washed 3−4 times with hydrochloric acid 1:99 in portions of 10 cm, collecting filtrate and washings in a volumetric flask with a capacity in accordance with table 1. The solution was cooled to room temperature, made up to the mark with water and mix.

4.4.2 Aliquot part of a solution obtained by 4.4.1.1 or 4.4.1.2 in accordance with table 1 is transferred to a volumetric flask with a capacity of 100 cm. If aliquota part is equal to 50 cm, is placed in a solution of Congo paper, is added dropwise a solution of ammonia until the appearance of blue-purple color of paper of the Congo. Then pour 25 cmof a mixture of reagents, made up to the mark with water and mix.

4.4.3 for the mass concentration in a sample of copper greater than 0.5%, zinc more than 4.0%, Nickel of more than 2.0%, or the amount of more than 5.0% of the solution prepared according to 4.4.2, poured into excess of 10 cmsolution of 1,10-phenanthroline or 2,2'-dipyridyl.

4.4.4 When the ratio in the sample of mass fraction of copper and iron more than 100:1 copper additionally separate the metal lead.

For this aliquot part of the solution, prepared according to 4.4.1.1 or 4.4.1.2, transferred to a beaker with a capacity of 100 cmand diluted with water to a volume of 30 cm. The solution is placed lead tape with an area of 3−4 cmand boil in low heat for 5−8 min. Lead tape on it precipitated copper is removed from solution, rinsed with water into the same beaker, the solution was cooled, transferred to a volumetric flask with a capacity of 100 cm. The volume of the solution in the flask should be 50−60 cm. Continuation of the analysis — by 4.4.2 and 4.4.3.

4.4.5 Optical density of the solution measured after 30 min at a wavelength of 510 nm in a cuvette with a layer thickness of 20 mm. Solution comparison the solution serves as the reference experiment, prepared according to 4.4.1.1 or 4.4.1.2, 4.4.2−4.4.4 with all used during the analysis reagents.

Weight of iron determined by the calibration schedule.

4.4.6 Construction of calibration curve

In nine out of ten volumetric flasks with a capacity of 100 cmeach measure 2,5; 5,0 cmof a solution; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0 cmof solution A, which corresponds to 0,000025; 0,00005; 0,0001; 0,00015; 0,0002; 0,00025; 0,0003; 0,00035; 0,0004 g of iron. Mud poured water to a volume of 50 cm, 25 cmof a mixture of reagents added in excess of 10 cmsolution of 1,10-phenanthroline or 2,2'-dipyridyl, if the schedule is suitable for samples 4.4.3, then topped to the mark with water and mix. Solution comparison is the solution to which is not entered iron.

According to the obtained values of optical density of the solutions and their corresponding masses of iron to build the calibration graph.

4.5 Processing of results

4.5.1 Mass fraction of iron , %, is calculated by the formula

, (1)

where is the mass of iron in the sample solution found by the calibration schedule g;

 — the weight of the portion of the sample in aliquote part of the solution,

4.5.2 discrepancies in the results must not exceed the values given in table 2.


Table 2

Percentage

5 Atomic absorption method for determination of iron

5.1 the essence of the method

The method is based on dissolving the samples in hydrochloric acid in the presence of hydrogen peroxide and measuring the nuclear absorption of iron at a wavelength of 248.3 nm in a flame acetylene-air.

5.2 the Instrument, reagents and solutions

Spectrophotometer of atomic absorption with a radiation source for iron.

Oven muffle.

Acetylene according to GOST 5457.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cm, mortar 1:1 and 1:99.

Nickel (II) chloride according to GOST 4038, a solution of 1 g/DM.

Sulfuric acid according to GOST 4204 density 1.84 g/cm.

Nitric acid according to GOST 4461 density of 1,35−1,40 g/cm.

Hydrofluoric acid according to GOST 10484.

Hydrogen peroxide according to GOST 10929.

Aluminium GOST 11069 brand А999.

A solution of aluminum 50 g/DM: 25 g of aluminum was placed in a conical flask with a capacity of 500 cm, add 1−2 cmof a solution of Nickel chloride (II), in small portions 275 cmof a hydrochloric acid solution of 1:1 and dissolved under moderate heating. The solution is poured 1 cmof hydrogen peroxide and boil it for 5 min.

The cooled solution is transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. The solution was stored in a plastic container.

Reactive iron (restored).

Standard solution of iron And — for 4.2.

1 cmof the solution contains 0.0001 g of iron.

5.3 Preparation for assay

Before analysis the chips samples atminciai.

5.4 analysis

5.4.1 the sample the sample weight in accordance with table 3 was placed in a conical flask with a capacity of 250 cm, 30 cm, pour thewater cautiously, in small portions, 30 cmof a hydrochloric acid solution 1:1. The flask is heated to dissolve the sample, add 3−5 drops of hydrogen peroxide and boil the solution for 3−5 min.


Table 3

5.4.1.1 If the solution is clear, he was transferred to volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

5.4.1.2 If residue remains, indicating the presence of silicon, the solution was filtered in a volumetric flask with a capacity of 100 cmthrough a filter medium density («white ribbon»), rinsing the filter 2−3 times with hot hydrochloric acid 1:99 in portions of 5−10 cm, and collect the filtrate in the same flask (stock solution).

The filter with precipitate was placed in a platinum crucible, dried, incinerated, preventing ignition, and calcined at 500−600°C for 2−3 min. After cooling in the crucible add five drops of sulfuric acid, 5 cmhydrofluoric acid and drop by drop nitric acid (approximately 1 cm) to obtain a transparent solution.

The solution was evaporated to dryness, cooled, poured to the dry residue in the crucible 10 cmof hydrochloric acid 1:1 and dissolved under moderate heating. The solution was then cooled, if necessary, filtered through a small, dense filter («blue ribbon») and added to the main solution in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

5.4.2 Aliquot part of the solution in accordance with table 3 is placed in a volumetric flask with a capacity of 100 cm, pour a solution of hydrochloric acid 1:1 in accordance with table 3, made up to the mark with water and mix.

5.4.3 the Solution of the reference experiment are prepared according to 5.3.1 and 5.3.2, using is sample the sample the sample of aluminium.

5.4.4 Construction of calibration curve

5.4.4.1 When the mass fraction of iron from 0.005 to 0.10%

Eight volumetric flasks with a capacity of 100 cmeach poured in 20 cmof a solution of aluminium in seven of them measure 0,5; 1,0; 2,0; 4,0; 6,0; 8,0; 10,0 cmstandard solution A, which corresponds to 0,00005; 0,0001; 0,0002; 0,0004; 0,0006; 0,0008; 0,001 g of iron.

5.4.4.2 When the mass fraction of iron from 0.10 to 1.0%

In seven volumetric flasks with a capacity of 100 cmeach pour 2 cmof a solution of aluminium 5 cmof hydrochloric acid of 1:1, in six of them measure 1,0; 2,0; 4,0; 6,0; 8,0; 10,0 cmstandard solution A, which corresponds to 0,0001; 0,0002; 0,0004; 0,0006; 0,0008; 0,001 g of iron.

5.4.4.3 When the mass fraction of iron from 1.0 to 2.0%

In seven volumetric flasks with a capacity of 100 cmeach poured 1 cmof a solution of aluminium 5 cmof hydrochloric acid 1:1, in six of them measure 5,0; 6,0; 7,0; 8,0; 9,0; 10,0 cmstandard solution A, which corresponds to 0,0005; 0,0006; 0,0007; 0,0008; 0,0009; 0,001 g of iron.

5.4.4.4 Solutions obtained in 5.4.4.1−5.4.4.3, made up to the mark with water and mix.

5.4.5 Solutions of the samples in the reference experiment and the solutions for constructing the calibration curve is sprayed into the oxidizing flame of acetylene-air and measure the atomic absorption of iron at a wavelength of 248.3 nm.

According to the obtained values of atomic absorption and corresponding mass concentrations of iron to build a calibration curve in the coordinates: «the Value of atomic absorption — mass concentration of iron, g/cm». The solution, in which iron is not introduced serves as a solution control experience in construction of calibration curve.

Mass concentration of iron in the sample solution and the solution of control and experience determined by the calibration schedule.

5.5 processing of the results

5.5.1 Mass fraction of iron , %, is calculated by the formula

, (2)

where  — mass concentration of iron in the sample solution found by the calibration schedule, g/cm;

 — mass concentration of iron in solution in the reference experiment, was found in the calibration schedule, g/cm;

 — the volume of the sample solution, cm;

 — the weight of the portion of the sample or the weight of the portion of the sample in aliquote part of the solution,

5.5.2 discrepancies in the results must not exceed the values given in table 4.


Table 4

Percentage