GOST 3240.11-76

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  ГОСТ 3240.11-76

GOST 3240.11−76 magnesium Alloys. Method for the determination of potassium (with Change No. 1)

GOST 3240.11−76

Group B59

INTERSTATE STANDARD

MAGNESIUM ALLOYS

Method of determining potassium

Magnesium alloys.
Method for determination of potassium

ISS 77.120.20
AXTU 1709

Date of introduction 1978−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of aviation industry of the USSR

2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from 28.12.76 N 2889

3. INTRODUCED FOR THE FIRST TIME

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. EDITION with Change No. 1, approved in June 1987 (IUS 11−87)


This standard sets flame photometric method for the determination of potassium (with a potassium mass fraction from 0.002 to 0.02%).

The method is based on measuring the intensity of the atomic resonance lines of potassium 766,49 nm excited in an acetylene-air flame. To remove the effects of partial quenching of the emission of potassium in the presence of the alloy base and acid used for the decomposition of samples, the latter in the respective amounts administered in the calibration solutions.

In the analysis of alloys containing lithium, in the calibration solutions injected lithium in an amount corresponding to its mass fraction in the analyzed samples.

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 3240.0.

2. APPARATUS, REAGENTS AND SOLUTIONS

The fiery photometer or spectrophotometer.

Hydrochloric acid of high purity according to GOST 14261, diluted 1:1.

Nitric acid of high purity according to GOST 11125, diluted 1:1.

Bidistilled water, obtained according to GOST 4517.

Primary magnesium ingots according to GOST 804 in the form of chips.

A solution of magnesium 50 g/DM.

50 g of magnesium was dissolved in 800 cmof a hydrochloric acid solution, transferred to a volumetric flask with a capacity of 1 DM, diluted with bidistilled water to the mark, mix.

Potassium chloride, 0,1 M (0,1 n) standard-titer (fixanal).

Standard solutions of potassium.

Solution a: 0.1 M solution of potassium chloride fiksanala transferred to a volumetric flask with a capacity of 1 DM, diluted with bidistilled water to the mark and mix thoroughly.

Solution B: 25.5 cmsolution And transferred to a volumetric flask with a capacity of 1 DM, diluted with bidistilled water to the mark and mix.

1 cmof a solution contains 0.0001 g of potassium.

Acetylene in cylinders GOST 5457.

Lithium carbonate, H. h

A solution of lithium 10 mg/cm: 53,245 g previously dried at 100−105 °C to constant weight of lithium carbonate is placed in a tall glass with a capacity of 700−800 cm, moistened with water and gradually pour a solution of hydrochloric acid to enlightenment solution. After dissolution the solution was transferred to volumetric flask with a capacity of 1 DM, dilute to the mark with water and mix.

(Changed edition, Rev. N 1).

3. ANALYSIS

3.1. A portion of the alloy with a mass of 2 g is placed in a heat-resistant beaker or conical flask with a capacity of 300−400 cmand dissolved in 30 m of hydrochloric acid. In the presence of the copper alloy, it is transferred to the solution by adding a few drops of nitric acid. The resulting solution was transferred to a volumetric flask with a capacity of 100 m. the Vessel, which was carried out dissolving, rinse with two portions of double-distilled water at 5 cmand attach washings to the main solution. The mixture was diluted with bidistilled water to the mark and mix thoroughly. The resulting solution was introduced into the atomizer of the photometer and record the magnitude of the issue.

All take readings at a strictly constant pressure of acetylene and air. In order to avoid errors in unstable operation of the device after every four samples to check the slope of the calibration curve re-photoretrieval one of the previously analyzed solutions.

When you change the optical density by more than 2% the analysis of the last four samples is repeated.

3.2. Construction of calibration curve

In seven volumetric flasks with a capacity of 100 cmis administered at 40 cmof a solution of magnesium (the analysis of alloys, doped with lithium, lithium solution is injected, the amount of which is calculated by the formula where is the mass fraction of lithium in the sample, %), add 0; 0,2; 0,4; 1,0; 2,0; 4,0 and 10.0 cmof a solution that fits 0; 0,02; 0,04; 0,10; 0,20; 0,40 and 1.00 mg of potassium. The solutions were diluted to the mark with water, mixed, injected into the atomizer and photometric as specified in claim 3.1. The results of measurements of the intensity of the resonance lines of potassium build the calibration graph.

Sec. 3. (Changed edition, Rev. N 1).

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of potassium () in percent is calculated by the formula

,

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

 — the weight of the portion of alloy,

4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.

Sec. 4. (Changed edition, Rev. N 1).

5. CONTROL OF MEASUREMENT ACCURACY

To control the accuracy of measuring the mass fraction of potassium from 0.002 to 0.02% are using industry standard samples and standard samples of the enterprise of magnesium alloys, issued in accordance with GOST 8.315. Accuracy control measurement is carried out in accordance with GOST 25086.

Control the accuracy of measuring the mass fraction of potassium may be performed by a method of additives.

Sec. 5. (Added, Rev. N 1).