GOST 6689.12-92

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  ГОСТ 6689.12-92

GOST 6689.12−92 Nickel, alloys Nickel and copper-Nickel. Methods for determination of magnesium

GOST 6689.12−92

Group B59

STATE STANDARD OF THE USSR

NICKEL, ALLOYS NICKEL AND COPPER-NICKEL

Methods for determination of magnesium

Nickel, nickel and copper-nickel alloys. Methods for the determination of magnesium

AXTU 1709

Date of introduction 1993−01−01

INFORMATION DATA

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

DEVELOPERS

V. N. Fedorov, Y. M. Leybov, Boris Krasnov, A. N. Bulanova, L. V. Morea, A. I. Vorobyov

2. APPROVED AND promulgated by the Decree of Committee of standardization and Metrology of the USSR from 18.02.92 N 167

3. REPLACE GOST 6689.12−80

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the photometric (with a mass fraction of magnesium of from 0.005 to 0.2%) and atomic absorption (at a mass fraction of magnesium from 0.002 to 0.2%) methods for determination of magnesium in Nickel and copper-Nickel alloys according to GOST 492* and GOST 19241.
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* On the territory of the Russian Federation GOST 492−2006. — Note the manufacturer’s database.

1. GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 25086 with the addition of sec. 1 GOST 6689.1.

2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF MAGNESIUM

2.1. The essence of the method

The method is based on the formation of magnesium in an alkaline environment with a titanium compound yellow pink color and the measurement of the optical density of colored solution.

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

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

Sulfuric acid according to GOST 4204, diluted 1:1.

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

A mix of acids for dissolving nitric and hydrochloric acid in the ratio of 1:3.

Ammonia water according to GOST 3760.

Sodium hydroxide according to GOST 4328, solutions 10 and 200 g/DM.

Ammonium neccersarily according to GOST 20478.

Ammonium chloride according to GOST 3773, solutions of 20 and 200 g/DM.

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

Gelatin solution 5 g/DM.

Hydrogen peroxide according to GOST 10929, 30% solution.

Diethyldithiocarbaminate sodium GOST 8864, a solution of 50 g/DM.

Titanium yellow, a solution of 0.5 g/DM.

Magnesium oxide for spectral analysis.

Standard solutions of magnesium.

Solution a: magnesium oxide is calcined in a quartz crucible in the muffle at 900−1100 °C for 1 h of 1.66 g of calcined magnesium oxide is dissolved in 10 cmof hydrochloric acid (1:1). The solution was transferred to volumetric flask with a capacity of 500 cmand top up with water to the mark.

1 cmof the solution contains 0.002 g of magnesium.

Solution B: 5 cmsolution And placed in a volumetric flask with a capacity of 100 cmand then filled to the mark with water.

1 cmof a solution contains 0.0001 g of magnesium.

Solution: 10 cmof solution B is placed in a volumetric flask with a capacity of 100 cmand then filled to the mark with water.

1 cmof the solution contains 0,00001

g of magnesium.

2.3. Analysis

2.3.1. For alloys containing chromium

Sample of alloy weighing 0.5 g were placed in a glass with a capacity of 300 cm, add 20 cmof a mixture of acid, cover with watch glass, glass or plastic plate and dissolved by heating. After cooling, rinse the glass or plate and the side of the Cup with water, add 10 cmsulphuric acid and the solution is evaporated until a white smoke of sulfuric acid. After cooling, the residue is dissolved in 20 cmof water under heating and the solution is diluted with water to 150 cm. Add sodium hydroxide solution (200 g/DM) to the precipitation of chromium hydroxide, which begins to appear at pH 5. With further addition of sodium hydroxide solution to pH 14 the hydroxide of chromium is soluble, and precipitates the hydroxide of Nickel and magnesium. The solution was added hydrogen peroxide to oxidize trivalent chromium to hexavalent. The solution is heated to oxidation occurred completely.

The precipitate hydroxides of Nickel and magnesium on the filter tight filter.

The beaker and precipitate was washed 8−10 times with a solution of sodium hydroxide (10 g/DM). The washed precipitate is washed with hot water into a glass, which conducted the deposition, dissolved in 40 cmof hydrochloric acid (1:1). The solution is diluted with water to a volume of 80 cmand neutralized with sodium hydroxide solution (200 g/DM) to a pH of 4.0 to 4.5 by universal indicator paper. The neutralized solution is transferred to a volumetric flask with a capacity of 250 cmand with stirring was added 80 cmof a solution of sodium diethyldithiocarbaminate.

The solution with precipitated sludge was diluted to the mark with water, mix thoroughly and leave for 4−5 hours (at night) for sludge precipitation. The supernatant solution was filtered in a dry conical flask using dry thick filter and dry the funnel. The first portion of the filtrate (15−20 cm) is discarded. Then select aliquot part (see table.1) in a volumetric flask with a capacity of 100 cm. If aliquota part is 100 cm, it is placed in a beaker, evaporated at low heat to a volume of 40−45 cmand transferred to a volumetric flask with a capacity of 100 cm. If aliquota part is less than 50 cm, it is diluted to approximately 50 cm. Add 10 cmof hydrochloric acid solution hydroxylamine, 5 cmgelatin solution, 5 cmof a solution of Titan yellow, 20 cmof sodium hydroxide solution (200 g/DM), diluted to the mark with water and measure the optical density of the solution on a photoelectrocolorimeter with a green-yellow filter in a cuvette with a thickness of the light absorbing layer 5 cm or in the spectrophotometer at 545 nm in a cuvette with the thickness of the light absorbing layer 1 cm.

Table 1

As a solution comparison solution is used in the reference experiment, conducted through the entire course of the analysis.

2.3.2. For alloys containing aluminium

A sample of alloy weighing 0.5 g were placed in a glass with a capacity of 300 cmadd 30 cmof nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. Once dissolved, rinse the glass or the plate and the walls of the glass 20 cmof water and the solution was boiled to remove oxides of nitrogen. The solution was cooled, added to 100 cmof water 5 cmof a solution of ammonium chloride (200 g/DM) and precipitated aluminium hydroxide ammonia solution. Solution to precipitate aluminum hydroxide is heated to 50−60 °C for coagulation of the precipitate. The precipitate was filtered off on a medium density filter, a glass and a precipitate was washed 8−10 times with a solution of ammonium chloride (20 g/DM). The precipitate is discarded. The filtrate is evaporated to a volume of approximately 80 cm, cooled and neutralized with hydrochloric acid (1:1) to pH 4.0 to 4.5 by universal indicator paper. The solution was transferred to a volumetric flask with a capacity of 250 cm, and further analysis are as indicated in claim 2.3

.1.

2.3.3. For alloys containing more than 0.5% manganese

A sample of alloy weighing 0.5 g were placed in a glass with a capacity of 200 cm, add 20 cmof nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. Once dissolved, rinse the glass or the plate and the walls of the glass 20 cmof water and the solution was boiled to remove oxides of nitrogen. The solution was cooled, added to 150 cmwater and add ammonia to slightly acidic environment for the paper of the Congo (to light purple color), then add 3 g ammonium naternicola and heated to release the manganese in the dioxide. The mixture was heated until complete destruction of excess ammonium naternicola (to complete the termination of allocation of bubbles of oxygen), the solution cooled and the precipitate of manganese dioxide is filtered off on a tight filter. The beaker and precipitate was washed 6−10 times with water. The precipitate discarded, and the filtrate is evaporated to a volume of approximately 80 cm.

After cooling, the solution is neutralized with sodium hydroxide solution (200 g/DM) to a pH of 4.0 to 4.5 by universal indicator paper, transferred to a volumetric flask with a capacity of 250 cmand lead further analysis, as indicated in claim 2.3.1

.

2.3.4. For alloys containing tungsten, and other alloys

A sample of alloy weighing 0.5 g were placed in a glass with a capacity of 300 cm, add 20 cmof nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. Once dissolved, rinse the glass or the plate and the walls of the glass 20 cmof water and the solution was boiled to remove oxides of nitrogen. The solution is diluted with water to about 30 cmand neutralized with sodium hydroxide solution (200 g/DM) to a pH of 4.0 to 4.5 by universal indicator paper. For alloys containing tungsten, the deposition of a tungsten acid is not paying attention.

The neutralized solution is transferred to a volumetric flask with a capacity of 250 cm, and further analysis are as indicated in claim 2.3.1.

2.3.5. Construction of calibration curve

In a volumetric flask with a capacity of 100 cmis placed 1,0; 2,0; 4,0; 6,0; 8,0 and 10,0 cmstandard solution of magnesium, dilute with water to 50 cm, add 10 cmof hydrochloric acid hydroxylamine and further analysis are as indicated in claim 2.3.1.

2.4. Processing of the results

2.4.1. Mass fraction of magnesium (a) in percent is calculated by the formula

,

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

 — weight of alloy, suitable aliquote part of the solution,

2.4.2. Discrepancies in the results of three parallel measurements (rate of convergence) and the results of the two tests (index of reproducibility) shall not exceed the values of permissible differences given in table.2.

Table 2

2.4.3. Control of accuracy of analysis results is carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) of Nickel, Nickel and copper-Nickel alloys, approved under GOST 8.315*, or method of additions or by comparison of the results obtained by atomic absorption method, in accordance with GOST 25086.
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* On the territory of the Russian Federation GOST 8.315−97, here and hereafter. — Note the manufacturer’s database.

3. ATOMIC ABSORPTION METHOD FOR DETERMINATION OF MAGNESIUM

3.1. The essence of the method

The method is based on measuring the absorption of light by atoms of magnesium, formed when the introduction of the analyzed solution in the flame acetylene-air or acetylene-nitrous oxide.

3.2. Apparatus, reagents and solutions

Atomic absorption spectrometer with a radiation source of magnesium.

Nitric acid according to GOST 4461 and diluted 1:1 and 1:100.

Hydrochloric acid according to GOST 3118 and 1 and 2 mol/DMsolutions.

A mixture of acid: mix one volume of nitric acid with three volumes of hydrochloric acid.

Hydrofluoric acid according to GOST 10484.

Sulfuric acid according to GOST 4204, diluted 1:1.

Magnesium GOST 804*.
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* On the territory of the Russian Federation GOST 804−93. — Note the manufacturer’s database.

Standard solution of magnesium: to 0.1 g of magnesium are dissolved in 10 cmof nitric acid (1:1). The solution brings in a volumetric flask with a capacity of 1 DMand topped to the mark with water.

1 cmof the solution contains 0.0001 g of magnesium.

Copper according to GOST 859*.
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* On the territory of the Russian Federation GOST 859−2001, here and hereafter. — Note the manufacturer’s database.

Standard copper solution: 10 g of copper was dissolved with heating in 80 cmof nitric acid (1:1).

The solution was transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark.

1 cmof the solution contains 0.1 g of copper.

Nickel GOST 849*.
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* On the territory of the Russian Federation GOST 849−2008. — Note the manufacturer’s database.

A standard solution of Nickel: 10 g of Nickel is dissolved by heating in 80 cmof nitric acid (1:1). The solution was transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark.

1 cmof the solution contains 0.1 g of Nickel.

3.3. Analysis

3.3.1. For alloys not containing tin, silicon, chromium and tungsten

A portion of the alloy by mass (see table.3) was dissolved with heating in 10 cmof nitric acid (1:1). The solution was transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark.

At the same time spend control experience.

Table 3

Measured by atomic absorption in the flame acetylene-air or acetylene-nitrous oxide (for alloys containing aluminium) at a wavelength of RUB 285.2 nm parallel to the calibration solutions.

3.3.2. For alloys with a mass fraction of tin in excess of 0.05%

A portion of the alloy (see table.3) was dissolved with heating in 10 cmof a mixture of acids. The solution was transferred to a volumetric flask with a capacity of 100 cmand topped to the mark of 1 mol/DMhydrochloric acid solution. At the same time spend control experience. Measure the atomic absorption of magnesium, as described in Chapter 3.3.1.

3.3.3. For alloys containing silicon and chrome

A portion of the alloy (see table.3) is placed in a platinum Cup and dissolved by heating in 10 cmof nitric acid (1:1) and 2 cmhydrofluoric acid. Then add 10 cmsulphuric acid (1:1) and evaporated until a white smoke of sulfuric acid. Cup cooled and the residue is dissolved in 50 cmof water when heated. The solution was transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark. At the same time spend control experience.

Measure the atomic absorption of magnesium, as described in Chapter 3.3.1.

3.3.4. For alloys containing tungsten

A portion of the alloy (see table.3) was dissolved with heating in 10 cmof nitric acid (1:1), then add 30 cmof hot water, the precipitate tungsten acid is filtered off on a tight filter and washed with hot nitric acid (1:100). The filtrate is transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark. At the same time spend control experience. Measure the atomic absorption of magnesium, as described in Chapter 3.3.1.

3.5. Construction of calibration curve

In eight of the nine volumetric flasks with a capacity of 100 cmplaced 0,2; 0,4; 0,6; 0,8; 1,0; 1,3; 1,6 and 2.0 cmof a standard solution of magnesium, which corresponds to 0,02; 0,04; 0,06; 0,08; 0,10; 0,13; 0,16 and 0.20 mg of magnesium. To all flasks add 10 cmof 2 mol/DMhydrochloric acid solution. For the mass concentration of magnesium, less than 0.02% add aliquote the volume of the solution (see table.3) copper (if copper is the basis of alloy) or Nickel (when Nickel is the substrate) and top up with water to the mark. Measure the atomic absorption of magnesium, as described in Chapter 3.3.1. According to the obtained results build a calibration curve.

3.4. Processing of the results

3.4.1. Mass fraction of magnesium (a) in percent is calculated by the formula

,

where is the concentration of magnesium in the sample solution alloy, was found in the calibration schedule, g/cm;

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

- the solution volume of sample, cm;

 — the weight of the portion of the sample,

3.4.2. Discrepancies in the results of three parallel measurements (rate of convergence) and the results of the two tests (index of reproducibility) shall not exceed the values allowable differences specified in table.2.

3.4.3. Control of accuracy of analysis results is carried out according to State standard samples (GSO) or industry standard sample (CCA) or by standard samples of the enterprise (SOP) of Nickel, Nickel and copper-Nickel alloys, approved under GOST 8.315, or by additives or by comparison of the results obtained by the photometric method according to GOST 25086.