GOST 11739.12-98

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  ГОСТ 11739.12-98

GOST 11739.12−98 Alloys, aluminum casting and wrought. Methods for determination of manganese

GOST 11739.12−98

Group B59

INTERSTATE STANDARD

ALLOYS ALUMINIUM CAST AND WROUGHT

Methods for determination of manganese

Aluminium casting and wrought alloys. Methods for determination of manganese

ISS 77.120.10
AXTU 1709

Date of implementation 2000−01−01

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 of 12 November 1998 No. 14−98)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology, dated April 21, 1999 No. 132 inter-state standard GOST 11739.12−98 introduced directly as state standard of the Russian Federation from January 1, 2000

4 REPLACE GOST 11739.12−82

1 Scope

This standard sets the photometric and atomic absorption methods for the determination of manganese at a mass fraction of from 0.005 to 2.0%.

2 Normative references

The present standard features references to the following standards:

GOST 195−77 Sodium sanitarily. Specifications

GOST 2603−79 Acetone. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

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

GOST 4197−74 Sodium atomistically. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4328−77 Sodium hydroxide. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 6008−90 metallic Manganese and nitrated manganese. Specifications

GOST 6552−80 orthophosphoric Acid. Specifications

GOST 9656−75 boric Acid. Specifications

GOST 10484−78 hydrofluoric Acid. Specifications

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11069−74* Aluminium primary. Brand

_______________
* Canceled. Valid GOST 11069−2001. — Note the CODE.

GOST 20490−75 Potassium permanganate. Specifications

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 the determination of manganese

4.1 the essence of the method

The method is based on dissolving the sample in sodium hydroxide solution, the oxidation of divalent manganese to pneumococcal in an acidic environment (with molar concentration of acid is more than 3.5 mol/DM) ignobilis potassium and measurement of optical density at a wavelength of 525 nm.

4.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Drying oven with thermostat.

Water, not containing reducing agents: to 1000 cmof water is poured 10 cmof sulphuric acid, mix, bring to a boil, add a few crystals of potassium Odnokolenko, boiled for 10 min and cooled to room temperature.

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

Sulfuric acid according to GOST 4204 density 1.84 g/cmand a solution of 1:1.

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

Orthophosphoric acid according to GOST 6552 a density of 1.70 g/cm.

Sodium sanitarily according to GOST 195.

Sodium atomistically according to GOST 4197, solution 20 g/DM. Prepare before use.

Hydrofluoric acid according to GOST 10484.

Boric acid according to GOST 9656, a saturated solution of 50 g of boric acid was placed in a conical flask with a capacity of 2 DM, go 950 cmwater, dissolve at a moderate heat, mix and cool to room temperature.

Acid bridgestation: 200 cmhydrofluoric acid at a temperature of (20±2) °With portions add 800 cmof boric acid solution and mixed. The solution is prepared and stored in a plastic container.

Potassium cognately [1], a solution of 50 g/DM: 25 g jednolitego potassium is placed in a conical flask with a capacity of 500 cm, pour 200cmof water, 100 CCof nitric acid, the solution was cooled, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. The solution is prepared before use.

Acetone according to GOST 2603.

Adsorbent (materiana paper): 100 g of crushed filters (red ribbon) is placed in a beaker with a capacity of 500 cm, 300 cm pouredhot water and stirred with a stirrer to obtain a homogeneous mass.

Potassium permanganate according to GOST 20490.

Manganese metal according to GOST 6008 brand Mn998.

If the surface of the metal manganese, is covered with the oxide film, it is purified. To do this, 2−3 g of manganese placed in a beaker with a capacity of 250 cm, 100 cm pouredwater and 40 cmof sulfuric acid solution. The contents of the Cup stirred and after a few minutes, when the metal surface is shiny, the solution is decanted, the chips were washed with water, washed twice with acetone, dried in a drying Cabinet at a temperature of 100−105 °C for 2−3 min and cooled in a desiccator to room temperature.

Standard solutions of manganese.

Solution a: 1 g of manganese placed in a tall glass with a capacity of 400 cm, poured 45−50 cmof water, 20 cmof sulfuric acid solution, cover with a watch glass and dissolved under heating. The solution was heated for 2−3 min in low heat and cool to room temperature. The glass is then rinsed with water above the glass, which had a dissolution. The solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

Allowed preparation of the solution a different way: 2,8776 g of potassium permanganate is placed in a tall glass with a capacity of 400 cm, dissolved in 200 cmof water and 20 cmof sulfuric acid solution. To the solution add a few crystals of sodium semitecolo to the bleaching solution, the excess reducing agent removed by careful boiling for 5−6 min. the Solution was cooled to room temperature, transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of manganese.

Solution B: 100 cmstandard solution And transferred 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 manganese.

4.3 analysis

4.3.1 the sample the sample weighing 1 g is placed in a beaker made of PTFE or glassy carbon with a capacity of 100 cmand poured in small portions 40 cmof sodium hydroxide solution. After termination of the reaction the beaker was heated until complete dissolution of the sample and with moderate heating, avoiding splashing the solution was evaporated to a thick syrupy consistency. The solution was then cooled, the side of the Cup is washed with the least possible volume of hot water (not more than 30 cm) and moderately heated. The alkaline solution was cooled, carefully transferred to a glass beaker with a capacity of 250−300 cmcontaining 30 cmof sulfuric acid solution and 10 cmof nitric acid. Wall Teflon beaker is washed with small portions of hot water, adding the washings to the acid solution in a glass beaker. To remove precipitated and adhered to the walls of the Teflon Cup of the particles of the hydroxide of manganese part of the test acid solution is poured back into the beaker, add 2−3 drops of solution of sodium attestatio and rotating a glass, rinse with a solution of a wall. The solution was poured in a glass glass, Teflon is washed with several portions of hot water and add the washings to the solution in a glass beaker.

4.3.1.1 for the mass concentration of manganese less than 0.1% of the volume of the solution was adjusted with water to 65 cmand mixed.

4.3.1.2 for the mass concentration of manganese more than 0.1%, the solution was transferred to volumetric flask in accordance with table 1, cooled to room temperature, made up to the mark with water and mix.


Table 1

4.3.1.3 Aliquot part of the solution in accordance with table 1 was placed in a conical flask with a capacity of 250 cm, poured sulfuric and nitric acid in amounts indicated in table 1, water to a volume of 65 cmand mixed.

4.3.1.4 Simultaneously with the analysis of samples carried out control experiment: in a conical flask with a capacity of 250 cmpour 8−10 cmwater 8 cmof sulfuric acid solution, 2 cmof nitric acid, water to a volume of 65 cmand mixed.

4.3.2 for the mass concentration of manganese less than 0.1% of silicon, more than 10.0% of the portion of the sample weighing 1 g is placed in a conical flask with a capacity of 250 cm, flow 20 cmof sulfuric acid solution, 10 cmof nitric acid, 2cmof solution bridgestation acid and moderately heated to dissolve the sample.

The solution was heated for 2−3 min to remove oxides of nitrogen, add hot water to a volume of 50 cm, add a bit of adsorbent and heat 2−3 min. Then filtered through a dense filter («blue ribbon»), the filter and the precipitate was washed 2−3 times with hot water and collect the filtrate in a conical flask with a capacity of 250 cm(stock solution).

The filter with precipitate was placed in a platinum crucible, incinerated, preventing ignition, and calcined at 500−600 °C. After cooling, pour 5−10 drops of sulfuric acid, 5−10 cmhydrofluoric acid, 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 hot water, add 3−5 drops of sulfuric acid and heated to dissolve the residue. After cooling, the solution is attached to the main solution (if necessary, filtered). The basic solution was evaporated to a volume of 65 cm.

Simultaneously with the analysis of the samples 4.3.1.3 conduct control experience with all reagents used during anal

iza.

4.3.3 liquid sample and the reference experiment, prepared according to 4.3.1.1−4.3.1.4, 4.3.2, pour 5 cmof phosphoric acid, and heated nearly to boiling (to a temperature of 90−95 °C), carefully pour 10 cmof a solution of potassium jednolitego and maintained at this temperature until the appearance of the characteristic crimson-purple color. The solutions were heated for 5 min (or 15−30 min if the manganese content in them is less than 0.2 mg), cooled to room temperature, transferred to volumetric flasks with a capacity of 100 cmeach, rinsed with water containing no reducing agents, and add the same to the mark with water.

4.3.4 absorbance measured at a wavelength of 525 nm in a cuvette with a layer thickness of 10 mm Solution comparison is water.

First, measure the optical density of colored solutions, then add 1−2 drops of a solution of sodium attestatio to bleaching solutions and repeat the measurement. The optical density of the sample solution is calculated from the difference of these two values.

Similarly conduct measurement of the optical density of the solution in the reference experiment .

The optical density of the sample solution is calculated by the formula

. (1)

The mass of manganese determined by the calibration schedule.

4.3.5 Construction of calibration curve

4.3.5.1 When the mass fraction of manganese from 0.005 to 2.0%

In seven conical flasks with a capacity of 250 cmeach measure 0,5; 1,0; 2,0; 5,0; 10,0; 15,0; 20,0 cmstandard solution B, which corresponds to 0,00005; 0,0001; 0,0002; 0,0005; 0,001; 0,0015; 0,002 g of manganese, is poured at 15 cmof sulfuric acid solution, 10 cmof nitric acid, water to a volume of 65 cm, add 5 cmof phosphoric acid and continue on 4.3.3, 4.3.4.

4.3.5.2 for the mass concentration of manganese less than 0.1% of silicon and more than 10.0%

In seven conical flasks with a capacity of 250 cmeach measure 0,5; 1,0; 2,0; 4,0; 6,0; 10,0; 15,0 cmstandard solution B, which corresponds to 0,00005; 0,0001; 0,0002; 0,0004; 0,0006; 0,001; 0,0015 g manganese, poured in 8 cmof sulfuric acid solution, 2 cmof nitric acid and 2 cmbridgestation acid, water to a volume of 65 cm, add 5 cmof phosphoric acid and continue on 4.3.3, 4.3.4.

According to the obtained values of optical density of the solutions and their corresponding masses of manganese build a calibration curve

.

4.4 Processing of results

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

, (2)

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

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

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


Table 2

Percentage

5 Atomic absorption method for the determination of manganese

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 manganese at a wavelength of 279.5 nm in the flame acetylene-air.

5.2 the Instrument, reagents and solutions

Spectrophotometer of atomic absorption with a radiation source for manganese.

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.

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.

Nickel (II) chloride according to GOST 4038, a solution of 2 g/DM.

Hydrogen peroxide according to GOST 10929.

Aluminium GOST 11069 brand А999.

A solution of aluminum 20 g/DM: 10 g of aluminum is placed in a conical flask with a capacity of 500 cm, pour 1 cmof a solution of Nickel chloride (II), in small portions 350 cmof a hydrochloric acid solution of 1:1 and dissolved under moderate heating.

To the solution add 3−5 drops of hydrogen peroxide and boil it for 3−5 minutes the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

Manganese metal according to GOST 6008 brand Mn998.

If the metal surface is covered with the oxide film, it is cleaned as specified in 4.2.

Standard solutions of manganese.

Solution a: 0.4 g of manganese placed in a tall glass with a capacity of 400 cm, flow 50 cmwater and 15 cmof hydrochloric acid of 1:1 and dissolved under moderate heating. The solution was cooled to room temperature, transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof a solution containing 0.0004 g of manganese.

Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof the solution contains 0,00004

g of manganese.

5.3 analysis

5.3.1 Sample the sample weighing 1 g is 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.

5.3.1.1 clear solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

5.3.1.2 If residue remains, indicating the presence of silicon, the solution was filtered in a volumetric flask with a capacity of 100 cmusing a medium density filter (white ribbon), the precipitate was washed 2−3 times with hot hydrochloric acid 1:99 portions at 5−10 cmand 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 3−5 min. After cooling in the crucible add five drops of sulfuric acid, 5−10 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»), attaching it to the main solution in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

5.3.2 depending on the mass fraction of manganese aliquot part of the solution placed in a measuring flask with volume capacity in accordance with table 3, pour a solution of hydrochloric acid 1:1 (see table 3), made up to the mark with water and mix.


Table 3

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

5.3.4 Construction of calibration curve

5.3.4.1 When the mass fraction of manganese from 0.005 to 0.05%

Eight volumetric flasks with a capacity of 100 cmeach poured in 50 cmof a solution of aluminium 5 cmof hydrochloric acid of 1:1, in seven of them measure 1,0; 2,5; 5,0; 7,5; 10,0; 12,5; 15,0 cmstandard solution B, which corresponds to 0,00004; 0,0001; 0,0002; 0,0003; 0,0004; 0,0005; 0,0006 g of manganese, made up to the mark with water and mix.

5.3.4.2 When the mass fraction of manganese from 0.05 to 0.2%

In six volumetric flasks with a capacity of 100 cmeach poured in 12.5 cmof a solution of aluminium 5 cmof hydrochloric acid of 1:1 in five of them measure 2,5; 5,0; 7,5; 10,0; 15,0 cmstandard solution B, which corresponds to 0,0001; 0,0002; 0,0003; 0,0004; 0.0006 g of manganese, made up to the mark with water and mix.

5.3.4.3 When the mass fraction of manganese from 0.2 to 2.0%

Eight volumetric flasks with a capacity of 100 cmeach poured at the 2.0 cmof a solution of aluminum 10 cmof hydrochloric acid 1:1, in seven of them measure 1,0; 2,5; 5,0; 7,5; 10,0; 15,0; 20,0 cmstandard solution B, which corresponds to 0,00004; 0,0001; 0,0002; 0,0003; 0,0004; 0,0006; 0,0008 g of manganese, made up to the mark with water and mix.

5.3.5 the sample Solution, solution control experience and solutions to build the calibration curve is sprayed into the oxidizing flame of acetylene-air and measure the atomic absorption with manganese at a wavelength of 279.5 nm.

5.3.6 According to the obtained values of atomic absorption and corresponding mass concentrations of manganese build a calibration curve in the coordinates: «the Value of atomic absorption — mass concentration of manganese in g/cm».

The mass concentration of manganese in the sample solution and the solution of control and experience determined by the calibration schedule.

5.4 processing of the results

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

, (3)

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

 — mass concentration of manganese 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, g

.

5.4.2 the Divergence of results should not exceed the values given in table 4.


Table 4

Percentage