GOST 25284.1-95

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  ГОСТ 25284.1-95

GOST 25284.1−95 Alloy zinc. Methods for determination of aluminium

GOST 25284.1−95
Group B59

INTERSTATE STANDARD

ZINC ALLOYS

Methods for determination of aluminium

Zinc alloys. Methods for determination of aluminium

ISS 71.040.40*
AXTU 1709
____________________
* In the index «National standards», 2008
ISS 77.120.60. — Note the manufacturer’s database.

Date of introduction 1998−01−01

Preface

1 DEVELOPED by the Donetsk state Institute of non-ferrous metals (Danism); International technical Committee MTC 107

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (EASC Protocol No. 7 of April 26, 1995)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization, Metrology and certification dated June 2, 1997 N 204 inter-state standard GOST 25284.1−95 was put into effect directly as the state standard of the Russian Federation from January 1, 1998

4 REPLACE GOST 25284.1−82

1 SCOPE

This standard applies to zinc alloys, and sets the chelatometric, atomic absorption (at a mass fraction of aluminum from 3 to 13%) and photometric (at a mass fraction of aluminum from 3 to 12.5%) methods for determination of aluminium in samples of these 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 859−78* Copper. Brand
________________
* On the territory of the Russian Federation GOST 859−2001. Here and further. — Note the manufacturer’s database.

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3640−94 Zinc. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4233−77 Sodium chloride. Specifications

GOST 4234−77 Potassium chloride. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 4463−76 Sodium fluoride. Specifications

GOST 5456−79 of Hydroxylamine hydrochloride. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 10652−73 Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B)

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11069−74* Aluminium primary. Brand
________________
* On the territory of the Russian Federation GOST 11069−2001. Here and further. — Note the manufacturer’s database.

GOST 18300−87 ethyl rectified technical. Specifications

GOST 25284.0−95 Alloy zinc. General requirements for methods of analysis

GOST 27068−86 Chernovetskiy Sodium (sodium thiosulfate) 5-water. Specifications

3 GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 25284.0.

4 CHELATOMETRIC METHOD

4.1 the essence of the method

The method is based on addition of excess of disodium salt of ethylenediaminetetraacetic acid (Trilon B) hydrochloric acid to the sample solution of the zinc alloy at a pH of 5 to 5.5, the binding of the complex excess Trilon B with standard solution of zinc, the decomposition of a complex aluminium-Trilon B sodium fluoride, and titrate the liberated Trilon B standard solution of zinc.

4.2 Reagents and solutions

Hydrochloric acid according to GOST 3118, a solution of 1:1.

Hydrogen peroxide according to GOST 10929.

Hydroxylamine hydrochloric acid according to GOST 5456, a solution of 200 g/DM.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, a solution of 65 g of Trilon B dissolved in 750 cmof water when it is heated, cooled and adjusted to a volume of 1 DM.

Ammonia water according to GOST 3760.

Sodium fluoride according to GOST 4463, a saturated solution of 60 g of sodium fluoride dissolved in 1 DMof hot water and after cooling filtered.

Acetic acid according to GOST 61.

Sodium acetate according to GOST 199.

Buffer solution, pH 5−5,5: 135 g of sodium acetate dissolved in 300 cmof water, add 15 cmof acetic acid and diluted the resulting solution with water to 500 cm. The pH control is carried out by using universal indicator paper or pH meter.

Methyl red to the standard documentation, an alcoholic solution: 0.02 g methyl red dissolved in 100 cmof ethanol.

Ethanol technical rectified according to GOST 18300.

Zinc metal according to GOST 3640.

Standard solution of zinc

3,269 g of zinc is dissolved in 20 cmof a hydrochloric acid solution in a beaker with a capacity of 250 cm, covered with a glass watch glass. The walls of the beaker and the watch glass rinsed with water, the solution diluted with water to 100 cm. Add two drops of methyl red solution, neutralise with ammonia until the color yellow, then add dropwise a solution of hydrochloric acid before transition of colouring in the red. The solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the resulting solution contains 0,001349 g of aluminum.

Selenology orange to the standard documentation, a solution of 10 g/DM: 1 gram of indicator dissolved in 100

cmwater.

4.3 analysis

A sample of alloy weighing 1 g is placed in a beaker with a capacity of 300 cm, carefully pour 10 cmof hydrochloric acid. After termination of the reaction add a few drops of hydrogen peroxide until complete dissolution of the sample. To remove excess of hydrogen peroxide add 1 cmof a solution of hydrochloric acid hydroxylamine. The solution was cooled, transferred to a volumetric flask with a capacity of 50 cm, is diluted to the mark with water and mix.

Aliquot part of the solution in accordance with table 1 was placed in a conical flask with a capacity of 500 cm.


Table 1

To the solution are added 100 cmwater 50 cmof the solution Trilon B, 5 drops of methyl red and neutralize with ammonia until the color yellow. Then add 25 cmbuffer solution, boil for 2−3 minutes, cool, add 2−3 drops of the solution kylinalove orange and octarepeat excess Trilon B solution standard solution of zinc before the painting in red. Add 25 cmof a solution of sodium fluoride, boil for 2−3 minutes, cool and titrate the liberated Trilon B standard solution of zinc before the painting in red.

4.4 Processing of results

4.4.1 Mass fraction of aluminum , %, is calculated by the formula

, (1)

where  — the volume aliquote parts of a solution of the sample, cm;

 — the volume of a standard solution of zinc consumed for titration of the liberated Trilon B, cm;

 — weight of sample, g;

0,001349 — mass concentration of a solution of zinc, expressed in grams of aluminium per 1 cmof the solution, g/cm

.

4.4.2 Discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 2.


Table 2

Percentage

5 ATOMIC ABSORPTION METHOD

5.1 the essence of the method

The method is based on dissolving the sample in hydrochloric acid and measuring the nuclear absorption of aluminium in the flame acetylene-nitrogen dioxide at a wavelength of 309,3 nm.

5.2 the Instrument, reagents and solutions

Spectrophotometer atomic absorption.

Acetylene according to GOST 5457.

Nitrogen dioxide health.

Hydrochloric acid according to GOST 3118, solutions of 1:1 and 2 mol/DM.

Hydrogen peroxide according to GOST 10929.

Potassium chloride according to GOST 4234 or sodium chloride according to GOST 4233, a solution of 10 g/DM.

Aluminium metal according to GOST 11069.

A standard solution of aluminium

0.5 g of aluminium is dissolved in 20 cmof hydrochloric acid with the addition of 2−3 cmof hydrogen peroxide solution, then the solution was boiled for 5 min to destroy the excess hydrogen peroxide, cooled, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of aluminium.

5.3 analysis

5.3.1 a sample of alloy weighing 1 g is placed in a beaker with a capacity of 300 cmand dissolved in 10 cmof hydrochloric acid (1:1).

For complete dissolution of the sample add 1 cmof hydrogen peroxide solution, boiled for 5 min, the solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. In a volumetric flask with a capacity of 250 cmis placed 25 cmof the sample solution, add 25 cmof a solution of chloride of potassium or sodium, made up to the mark with water and mix

.

5.3.2 For building a calibration curve in five out of six volumetric flasks with a capacity of 100 cmeach enter 2,0; 5,0; 8,0; 11,0 14,0 cm anda standard solution of aluminum. To each flask add 10 cmof hydrochloric acid solution (2 mol/DM), 1 cmof a solution of chloride of potassium or sodium, made up to the mark with water and mix.

Solution without aluminum is a solution of the reference experiment.

5.3.3 Solutions of sample and reference experience and solutions to build the calibration curve is sprayed into the flame acetylenics nitrogen and measure the atomic absorption of aluminum at a wavelength of 309,3 nm.

According to the obtained values of atomic absorption and corresponding values of aluminum content to build a calibration curve in the coordinates: the value of atomic absorption — mass concentration of aluminium in g/cm.

Mass concentration of aluminum in solutions of the sample and the reference experiment find for the calibration schedule.

5.4 processing of the results

5.4.1 Mass fraction of aluminum , %, is calculated by the formula

, (2)

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

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

 — the volume of sample solution prepared for the measurement of atomic absorption, cm;

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

.

5.4.2 Discrepancy between the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 2.

6 PHOTOMETRIC METHOD

6.1 the essence of the method

The method is based on measuring the optical density of the solution complex compound of aluminum with alumininum in acetate buffer solution.

The impact of iron eliminate ascorbic acid and copper with sodium thiosulphate.

6.2 Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Nitric acid according to GOST 4461, diluted 1:1.

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

Ascorbic acid medical, a solution of 10 g/DM.

Sodium thiosulfate 5-water according to GOST 27068, a solution of 100 g/DM.

Sodium acetate 3-water according to GOST 199.

Aluminum in the normative documentation.

Acetic acid according to GOST 61.

Acetate solution aluminon: 15 g of sodium acetate and 0.1 g of aluminon dissolve in water, add 3 cmof acetic acid, adjusted with water to 1 DMand incubated for 24 h.

Aluminium GOST 11069.

Standard solutions of aluminium

Solution a: 0.1 g of aluminium is dissolved in 10 cmof hydrochloric acid diluted 1:1, cooled, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.0002 g of aluminum.

Solution B: 50 cmsolution And transferred to a volumetric flask with a capacity of 500 cm, add 20 cmof hydrochloric acid diluted 1:1, made up to the mark with water and mix.

1 cmof solution B contains 0,00002 g of aluminum.

Copper metal according to GOST 859.

Standard solutions of copper

Solution a: 0.5 g copper metal was dissolved in 10 cmof nitric acid, diluted 1:1, boil to remove oxides of nitrogen, cooled, the solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.0005 g of copper.

Solution B: 0.1 g of copper metal is dissolved in 10 cmof nitric acid, diluted 1:1, boil to remove oxides of nitrogen, cooled, the solution was transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof solution B contains 0,0

001 g of copper.

6.3 analysis

6.3.1 a sample of alloy weighing 0.1 g were placed in a glass with a capacity of 100−150 cmand dissolved in 5 cmof nitric acid, diluted 1:1, first in the cold then when heated. After dissolution of the sample and remove the oxides when heated, nitric, sulfuric, perchloric, not allowing the solution to privatise. The solution was cooled and transferred to volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

2 cmsolution is placed in a volumetric flask with a capacity of 100 cm, add 3 cmof water 5 cmof a solution of ascorbic acid, 0.3 cmof sodium thiosulfate, and thoroughly mix the solution after each addition of reagent, adjusted to the mark with acetate solution and stirred aluminon

T.

6.3.2 For solution comparison in volumetric flask with a capacity of 100 cmis placed 5 cmof a solution of ascorbic acid, 0.3 cmof sodium thiosulfate, stirred, adjusted to the mark with acetate solution and stirred aluminon.

6.3.3 For the construction of calibration curve six volumetric flasks with a capacity of 100 cmeach placed 0; 1,0; 2,0; 3,0; 4,0 and 5,0 cmof aluminum solution (solution B), add water up to 5 cm, 1 drop of nitric acid, diluted 1:1, 0.1 cmof a solution of copper (for alloys with a mass fraction of copper not more than 2% was added to a solution of B, for alloys with a mass fraction of copper of more than 2% — solution). Add 5 cmof a solution of ascorbic acid to further conduct the analysis in accordance with 6.3.1. Solution without aluminum is a solution of the reference experiment.

6.3.4 after 15 min measure the optical density of the sample solution and solutions for constructing the calibration curve at a wavelength of 540 nm in a cuvette with the thickness of the absorbing layer of 3 cm

According to the obtained values of optical density and corresponding mass of aluminium to build a calibration curve in the coordinates: the optical density is the mass of aluminium,

The aluminum content in the sample find for the calibration schedule.

6.4 Processing of results

6.4.1 Mass fraction of aluminum , %, is given by

, (3)

where is the mass of aluminum was found in the calibration schedule g;

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

6.4.2 divergence of the results of parallel measurements and the results of the analysis shall not exceed allowable (at confidence probability of 0.95) of the values given in table 2.