GOST 6689.9-92

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  ГОСТ 6689.9-92

GOST 6689.9−92 Nickel, alloys Nickel and copper-Nickel. Methods for determination of cobalt

GOST 6689.9−92

Group B59

STATE STANDARD OF THE USSR

NICKEL, ALLOYS NICKEL AND COPPER-NICKEL

Methods for determination of cobalt

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

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 6689.9−80

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard sets the photometric and atomic absorption methods for the determination of cobalt (at a mass fraction of from 0.02 to 1.5%) in Nickel, 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 COBALT

2.1. The method is based on formation of colored red cobalt compounds with nitroso-R-salt and measurement of its optical density.

2.2. Apparatus, reagents and solutions

Photoelectrocolorimeter or spectrophotometer.

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

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

Hydrofluoric acid according to GOST 10484.

Sodium acetate according to GOST 199, a solution of 500 g/DM.

Nitroso-R-salt, a solution of 1 g/DM, is stored in a vessel made of dark glass.

Cobalt grade K0 GOST 123*.
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* On the territory of the Russian Federation GOST 123−2008, here and hereafter. — Note the manufacturer’s database.

Cobalt sulfate according to GOST 4462.

Standard solutions of cobalt.

Solution a: 0.5 g of cobalt dissolved in 20 cmof nitric acid (1:1), add 20 cmof sulphuric acid (1:1) and removed prior to the allocation of thick white smoke of sulfuric acid. The residue is cooled, dissolved in a little water, the solution is transferred into a measuring flask with volume capacity of 1000 cmand top up with water to the mark.

Solution a can be prepared from sulphate of cobalt: 2,385 g CoSO·7HO dissolved in water, the solution is transferred into a measuring flask with volume capacity of 1000 cmand topped to the mark with water.

1 cmof the solution contains 0.0005 g of cobalt.

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

1 cmof a solution of 0.00005 g contains Koba

it.

2.3. Analysis

2.3.1. For alloys containing more than 0,1% of chromium and silicon

A portion of the alloy 0.5 g was placed in a platinum Cup, add 1−2 cmhydrofluoric acid, 10 cmof nitric acid (1:1) and dissolved by heating. After cooling, add 10 cmsulphuric acid (1:1) and the solution is evaporated prior to the allocation of white smoke of sulfuric acid. The residue is cooled, rinse the walls of the Cup 30−40 cmof water and dissolved by heating. When the mass fraction of cobalt in the alloy is less than 0.1% use entire solution, and when the mass fraction of cobalt in excess of 0.1% solution transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark. Aliquot part of the solution (see table.1) or the entire solution is placed in a volumetric flask with a capacity of 100 cm, dilute with water to 50 cm, add 10 cmof a solution of sodium acetate and 10 cmof the solution, nitroso-R-salt and heated to boiling.

Table 1

In the boiling solution, carefully pour 5 cmof concentrated nitric acid and boil 2 min. After cooling, the solution topped to the mark with water and measure its optical density on a photoelectrocolorimeter with a green optical filter (~490 nm), or on the spectrophotometer at 500 nm in a cuvette with the thickness of the light absorbing layer 1 cm.

A solution of comparison, using the same solution, but without addition of nitroso-R-salt.

The obtained values of optical density of the test solution subtract the value of the optical density of the solution in the reference experiment, measured relative to water, and found the difference in optical densities find cobalt content.

2.3.2. For alloys with a mass fraction of silicon is less than 0.1%

A portion of the alloy 0.5 g were placed in a glass with a capacity of 250 cm, add 15 cmof nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. Glass or plate and the side of the Cup then rinsed with water and the mass fraction of cobalt in the alloy is less than 0.1% for the analysis using the entire solution, and when the mass fraction of cobalt in excess of 0.1% solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and then do as described in claim 2.3.1.

2.3.3. Build graduirovannam graphics

In a volumetric flask with a capacity of 100 cmis placed 2,0; 4,0; 6,0; 8,0; 10,0 and 12,0 cmstandard solution B of cobalt, 10 cmof a solution of sodium acetate and further receives, as described in Chapter 2.3.1.

As a solution comparison, using a solution not containing cobalt.

2.4. Processing of the results

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

,

where is the mass of cobalt 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 THE DETERMINATION OF COBALT

3.1. The essence of the method

The method is based on measuring the absorption of light by atoms of cobalt formed during the introduction of the analyzed solution in the flame acetylene-air.

3.2. Apparatus, reagents and solutions

Atomic absorption spectrometer with a radiation source for cobalt.

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

Hydrofluoric acid according to GOST 10484.

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

Cobalt GOST 123.

Standard solution of cobalt: 0.1 g of cobalt is dissolved by heating in 10 cmof nitric acid (1:1). The solution was transferred to a volumetric flask with a capacity of 1 DMand made up to the mark.

1 cmof the solution contains 0.0001 g of cobalt.

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

The 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.

The 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

A sample of alloy weighing 1 g is taken to determine the mass fraction of cobalt-0,02−0,1% by weight 0,1 g to determine the mass fraction of cobalt 0,1−1,5%.

3.3.1. For alloys not containing silicon, chromium and tungsten

A portion of the alloy is dissolved by 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.

Measure the atomic absorption of cobalt in the flame acetylene-air at a wavelength of 240,7 nm parallel to the calibration solutions.

3.3.2. For alloys containing silicon and chrome

A portion of the alloy 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. Measure the atomic absorption of cobalt as described in section 3.3.1.

3.3.3. For alloys containing tungsten

A portion of the alloy is dissolved by 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.

Measure the atomic absorption of cobalt as described in section 3.3.1.

3.3.4. Construction of calibration curve

In six of the seven volumetric flasks with a capacity of 100 cmis placed 1,0; 4,0; 7,0; 10,0; 12,0 and 15,0 cmstandard solution of cobalt, which corresponds to the 0,1; 0,4; 0,7; 1,0; 1,2 and 1.5 mg of cobalt. When the mass fraction of cobalt is less than 0.1% is added to all flasks for 10 cmof a solution of 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 cobalt as described in section 3.3.1. According to the obtained results build a calibration curve.

3.4. Processing of the results

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

,

where is the concentration of cobalt was found in the calibration schedule, g/cm;

 — the volume of the sample solution, 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.