GOST 6689.8-92

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  ГОСТ 6689.8-92

GOST 6689.8−92 Nickel, alloys Nickel and copper-Nickel. Methods for determination of aluminium

GOST 6689.8−92

Group B59

STATE STANDARD OF THE USSR

NICKEL, ALLOYS NICKEL AND COPPER-NICKEL

Methods for determination of aluminium

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

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 6689.8−80

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the titrimetric method for the determination of aluminum (with a mass fraction of aluminum from 1 to 3.5%), a photometric method (when the mass fraction of aluminum from 0.005 to 0.5%) and atomic absorption method (with a mass fraction of aluminum from 0.01 to 3.5%) in Nickel, Nickel and copper-Nickel alloys according to GOST 492 and GOST 19241.

1. GENERAL REQUIREMENTS

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

2. TITRIMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM

2.1. The essence of the method

The method is based on linking all components of the analyzed alloy in the complexes with a solution of Trilon B, the titration of excess Trilon B with a solution of sulphate of copper, the decomposition of complexonate of aluminium fluoride of ammonium or of sodium and subsequent determination of aluminium by titration with standard solution of copper (II) animatrices or in the presence of the indicator 1 (2-pyridylazo)-2-naphthol.

2.2. Apparatus, reagents and solutions

pH meter pH 340 or other device of the same class with all facilities.

Setting for titration with amperometric indication of the endpoint of the titration (drawing) consists of a Cup 1 with a capacity of 250−300 cmfor the test solution; two platinum indicator electrodes 2 with a length of 20−25 mm and a diameter of 0,8−1 mm; magnetic stirrer 3 for mixing the solution in the titration; the source of current 8 (battery or dry battery) voltage 1.8 V; the variable resistance 6 to 1 Mω for establishing a polarizing current of 2−10 mA; 7 microammeter with a scale of 25 mA, placed in series in the circuit; potentiometer 5, connected in parallel to the circuit to measure the voltage on the electrodes; burettes 4 with a capacity of 25 cm.

The scale value of the potentiometer should be less than 5 mV, that the jump in potential at the equivalence point provides a deflection on the scale of the device is not less than 20−25 divisions. As the potentiometer is to use pH-meter pH-340, pH-121 or LSM-60 in the millivoltmeter mode.

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

Hydrochloric acid according to GOST 3118, diluted 1:1 and 1:5.

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

Hydrofluoric acid according to GOST 10484.

Acetic acid according to GOST 61.

Hydrogen peroxide according to GOST 10929, 30% solution.

Blend to refresh the surface of the electrodes: 20 cmof hydrochloric acid (1:5) add a few drops of hydrogen peroxide.

Methenamine.

Ammonia water according to GOST 3760, diluted 1:1.

Ammonium acetate according to GOST 3117, a solution of 200 g/DM.

Ammonium fluoride according to GOST 4518.

Sodium fluoride according to GOST 4463.

Ethylenediamine — N, N, N', N'-tetraoxane acid disodium salt, dvuvodny (Trilon B) according to GOST 10652, a solution of 100 g/DM.

1-(2-pyridylazo)-2-naphthol (PAN), an alcoholic solution of 5 g/DM.

Manganese (II) sulfate 5-water according to GOST 435, a solution containing 1 mg/lmanganese: 2,75 g of salt dissolved in 1 DMof water.

The technical rectified ethyl alcohol according to GOST 18300.

Carbamide (urea) GOST 6691, a solution of 100 g/DM.

Copper brand M0 and M00 according to GOST 859*.
_______________
* On the territory of the Russian Federation GOST 859−2001, hereinafter potekstu. — Note the CODE.

Standard solutions of copper and 0.02 to 0.05 mol/DMsolutions: 3,177 g (0,05 mol/DM) and 1,2708 g (0,02 mol/DM) of copper is dissolved in 30 cmof nitric acid (1:1), boil to remove oxides of nitrogen, cooled, neutralized with ammonia before the advent of the stable precipitate, which is dissolved by adding acetic acid and dilute with water to 1 DM.

Aluminum brand A99 or A9 according to GOST 11069*.
_______________
* Valid GOST 11069−2001. — Note the CODE.

Standard aluminium solution: 1 g of aluminium is dissolved in 10 cmof hydrochloric acid (1:1) solution is transferred into a measuring flask with volume capacity of 1000 cmand topped to the mark with water.

1 cmof the solution contains 0.001 g of aluminium.

2.2.1. The installation of the mass concentration of a standard solution of 0.02 mol/DMcopper

2.2.1.1. With a visual indication of the titration end point

10 cmof a standard solution of aluminium was placed in a conical flask with a capacity of 500 cm, is diluted with water up to 50−60 cm, neutralized with ammonia solution before the formation of stable precipitate, which is dissolved by adding hydrochloric acid, and then add another two drops of acid. Add 10 cmof the solution Trilon B, 100−150 cmof hot water and heat the solution to boiling. In the hot solution is poured 10 cmof a solution of ammonium acetate, 0.5 cmof the solution PAN and the hot solution titrated with a standard solution of 0.05 mol/DMof transition copper to orange color of the solution blue. Add 1 g of sodium fluoride or of ammonium, boil for 5 minutes and titrated with a standard solution of 0.02 mol/DMof transition to copper green color of the solution in sin

Yu.

2.2.1.2. With amperometric indication of the endpoint of the titration

10 cmof a standard solution of aluminium was placed in a beaker with a capacity of 300 cm, add 20 cmwater, 1 cmof a solution of sulphate of manganese and 10 cmsolution of Trilon B.

Set the pH of the solution is 6.0 to 6.2 on the pH meter by adding small amounts to the methenamine solution and boil 5 min. After cooling, set the beaker on the magnetic stirrer and immersed in a solution of platinum electrodes. With variable resistance set in the circuit current of 2−10 mA, include a potentiometer and set the arrow on the scale of the potentiometer to approximately mid-scale. Octarepeat excess Trilon B with a standard copper solution while stirring the solution. The titrant is served in a glass approximately at a speed of 1 cm/min By the end of the titration a standard solution of copper is added dropwise. The titration is complete, if by adding one drop of a solution of copper arrow of the potentiometer deviates by at least 20 divisions of the scale (100 mV).

Add 1 g of sodium fluoride or ammonium, establish a pH 6,0−6,2 (for pH meter) by addition of a few drops of nitric acid (1:1) or hexamine solution and boil 5 min. After cooling, the solution potentiometric titrated with standard copper solution as described above.

Mass concentration of copper solution (), expressed in grams of aluminium per 1 cmof a solution, calculated by the formula

,

where 0,01 is the mass of aluminium, suitable aliquote part taken for the titration, g;

 — the volume of a standard solution of copper consumed in the second titration, sm.

2.3. Analysis

2.3.1. For alloy cunial

2.3.1.1. Definition with a visual indication of the titration end point

A portion of the alloy with a mass of 0.25 g is placed in a conical flask with a capacity of 500 cm, add 10 cmof nitric acid and dissolved by heating. After dissolution of the alloy walls of the flask rinsed with water, and the solution boil for 1−2 min to remove the oxides of nitrogen. The solution was cooled, added to 10 cmof urea solution and neutralized with ammonia solution before the formation of stable precipitate, which is dissolved by adding hydrochloric acid. Then add another two drops of acid, add 20 cmof Trilon B solution, 100 cmof hot water and further analysis are as indicated in claim 2.2.1.1.

2.3.1.2. Determination with amperometric indication of the endpoint of the titration

A sample of alloy weighing 0.25 g were placed in a glass with a capacity of 300 cm, add 10 cmof nitric acid, cover with watch glass, glass or plastic plate and dissolved by heating. After dissolution of the alloy or glass plate and the side of the Cup then rinsed with water and the solution evaporated to a moist residue.

The beaker cool, add 20 cmwater, 1 cmof a solution of sulphate of manganese, 20 cmsolution of Trilon B and further analysis are as indicated in claim 2.2.1.2.

2.3.2. For the alloy alumel

2.3.2.1. Definition with a visual indication of the titration end point

A portion of the alloy with a mass of 0.25 g is placed in a platinum Cup, add 10 cmof nitric acid, 2−3 cmhydrofluoric acid, cover with a lid of PTFE or platinum, and dissolved by heating. After dissolution of the alloy cover and the walls of the Cup and rinse with water, add 10 cmsulphuric acid (1:1) and removed prior to the allocation of white smoke of sulfuric acid. The cooled residue is dissolved in 50 cmof water when heated. The solution was transferred to a conical flask with a capacity of 500 cmand neutralized with ammonia solution before the formation of stable precipitate, which is dissolved by adding hydrochloric acid, then add two more drops of acid and then act as described in section 2.2.1.1.

2.3.2.2. Determination with amperometric indication of the endpoint of the titration

A portion of the alloy with a mass of 0.25 g is placed in a platinum Cup, add 10 cmof nitric acid and 2−3 cmhydrofluoric acid, Cup cover made of PTFE or platinum and is dissolved by heating. After dissolution of the alloy cover and the walls of the Cup and rinse with water, add 10 cmsulphuric acid and is evaporated prior to the allocation of white smoke of sulfuric acid. The cooled residue is dissolved in water when heated. The solution was transferred to a beaker with a capacity of 300 cmand then do as described in claim 2.3.1.2.

2.4. Processing of the results

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

,

where is the volume of copper solution consumed in the second titration, cm;

 — mass concentration of copper solution, expressed in g/cmof aluminum;

 — the weight of the portion of alloy,

2.4.2. Discrepancies in the results of three parallel measurements (rate of convergence) and the results of two tests (a measure of reproducibility.) shall not exceed the values of permissible differences given in table.1.

Table 1

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) Nickel and copper-Nickel alloys, approved under GOST 8.315*, or a comparison of the results obtained by atomic absorption method, in accordance with GOST 25086.
_______________
* Valid GOST 8.315−97, here and hereafter. — Note the CODE.

3. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM

3.1. The essence of the method

The method is based on measuring the optical density of the complex compound of aluminum with eryhromycin or chromazurol after the separation of aluminum by coprecipitation with ferric hydroxide.

3.2. Apparatus, reagents and solutions

Photoelectrocolorimeter or spectrophotometer.

pH meter pH 340 or any device of the same class with all facilities.

Nitric acid according to GOST 4461, diluted 1:1 and 1:50.

Hydrochloric acid according to GOST 3118 diluted 1:1, 1, and 0.1 mol/DMsolutions.

Sulfuric acid according to GOST 4204, diluted 1:1, 1:4 and 1:5. A mixture of acids, freshly made salt and nitrogen in the ratio of 3:1.

Thioglycolic acid, diluted 1:10, freshly prepared.

Ascorbic acid according to normative-technical documentation, a freshly prepared solution of 10 g/DM.

Acetic acid according to GOST 61.

Silver nitrate according to GOST 1277, aqueous solution 10 g/DM.

Ammonium neccersarily according to GOST 20478, a solution of 200 g/DM.

Ammonium chloride according to GOST 3773 and a solution of 20 g/DM.

Alum salesonline according to GOST 4205.

Solutions gentoomaniac alum.

Solution a: 10 g gentoomaniac alum is dissolved by heating in 70 cmof water with the addition of 1 cmof concentrated sulfuric acid and dilute with water to 100 cm.

Solution B: 10 cmsolution And dilute with water to 100 cm.

Sodium Chernovetskiy according to GOST 4216, a solution of 50 g/DM.

Ammonia water according to GOST 3760 diluted 1:1, 1:3, 1:50.

Ammonium acetate according to GOST 3117.

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

Sodium hydroxide according to GOST 4328, 1 mole/DMsolution.

Buffer solution (pH 6): 46 g ammonium acetate and 18 g of sodium acetate and dissolve in 1 DMof water. Set the pH of the solution at the pH meter, adding, if necessary, sodium hydroxide or acetic acid.

Carbamide (urea) GOST 6691.

Thiourea according to GOST 6344, solution 100 g/DM.

Gelatin, a solution of 10 g/DM.

Eryhromycin aqueous solution of 0,7 g/DM: 0.7 g of erioglaucine dissolved in 2 cmof concentrated nitric acid with constant stirring for 2 minutes, add 60 cmof water, 0.3 g of urea and incubated for 24 h in a dark place. The solution was filtered in a volumetric flask with a capacity of 1 DM, made up to the mark with water and store in a dark bottle.

The technical rectified ethyl alcohol according to GOST 18300.

Chromazurol , the solution of 3 g/DM: 0.3 g of chromazurol dissolved in 30 cmof warm water (above 60 °C), 20 cmof ethyl alcohol, filter and add water in a flask with a capacity of 100 cmmark.

Aluminium GOST 11069, brand A99 or A9.

Standard solutions of aluminium.

Solution a: 0.1 g of aluminium is dissolved by heating in 20 cmof hydrochloric acid (1:1). The solution was transferred into a measuring flask with volume capacity of 1000 cmand top up with water to the mark.

1 cmof the solution contains 0.0001 g of aluminum.

Solution B: 2.5 ml of solution And transferred to a volumetric flask with a capacity of 50 cm, add 20 cmof hydrochloric acid (1:1) and topped to the mark with water prepared on the day of application.

1 cmof a solution with

keeps 0,000005 g of aluminum.

3.3. Analysis

3.3.1. For the alloy manganin

A sample of alloy weighing 0.25 g was dissolved in a beaker with a capacity of 250−300 cmin 8 cmof nitric acid (1:1). The solution is diluted with water to 150−200 cmof water, add 20 cmof a solution of ammonium naternicola heat and boil for 15−20 minutes until the complete decomposition of ammonium naternicola (to complete the termination of allocation of bubbles of oxygen). The precipitate of manganese dioxide is filtered off on a tight filter. The beaker and precipitate was washed 6−8 times with water. The precipitate is discarded. To the filtrate add 1 cmof a solution of alum salesonline, 2 g of ammonium chloride and precipitated aluminum hydroxide, and iron ammonia (1:1), Prilepa it in small portions while stirring the solution, until the transition of copper and Nickel in a soluble complex and the appearance of weak smell of ammonia. Solution and the precipitate was kept for 15−20 min in a dark place, the precipitate is filtered off on a loose filter and wash out the beaker and the residue on the filter with a solution of ammonium chloride. The washed precipitate is washed from the filter with hot water into a glass, which made the deposition, and dissolved in 5 cmof hot hydrochloric acid (1:1). The filter is washed with hot water. A glass solution is heated to complete dissolution of the precipitate, the solution was boiled down to 70−80 cm, transferred to a volumetric flask with a capacity of 100 cmand add water to label

I.

3.3.1.1. Definition with the use of eryhromycin

In a volumetric flask with a capacity of 100 cmis placed 2 cmof the resulting solution, add water to 20 cm, 10 cmsolution of thioglycolic acid, is introduced dropwise ammonia (1:1) until staining of thioglycolate iron, then add 1 mol/DMsolution of hydrochloric acid to the bleaching solution and 0.5 cmin excess. Add 20 cmof a solution of erioglaucine , 30 cmbuffer solution and topped up to the mark with water.

When you install the pH of the solution by pH-meter aliquot part of the solution is placed in a glass, add water up to 20 cm, 2 cmof ascorbic acid solution, 5 cmsolution servational sodium, 5−10 min later, add 20 cmof a solution of erioglaucine and set pH 6 to pH meter with ammonia (1:1). Transferred to a volumetric flask with a capacity of 100 cm, add 30 cmbuffer solution and add water to the mark. After 20 min, measure the optical density of the solution on a photoelectrocolorimeter with a green optical filter in a cuvette with a thickness of the light absorbing layer 2 cm or on spectrophotometer at 535 nm in a cuvette with the thickness of the light absorbing layer 1 see Solution comparison is the solution of the control

experience.

3.3.1.2. Determination using chromazurol

In a glass with a capacity of 100 cmis placed 2 cmand the obtained solution is evaporated almost to dryness. To the residue add 5 cmof hydrochloric acid (0.1 mol/l) and heated until dissolved. Then diluted with water to 30 cm, add 1 cmof a solution of thiourea, 3 cmof a solution of thioglycolic acid and set pH 4 for pH meter or universal paper ammonia solution (1:3). Then add 10 cmgelatin solution, 3 cmof a solution of chromazurol and the solution is placed in a volumetric flask with a capacity of 100 cm, add a 40 cmbuffer solution, topped up to the mark with water and mix.

After 40−50 min, measure the optical density of the solution on a photoelectrocolorimeter with a green filter (=540−560 nm) or on a spectrophotometer at 545 nm in cuvettes with the thickness of the light absorbing layer 2, or 1 cm*. Solution comparison is the solution of the reference experiment.
_______________
* Consistent with the original. — Note the «CODEC

».

3.3.2. For the alloy chromel

A sample of alloy weighing 0.5 g were placed in a glass with a capacity of 500−600 cmadd 20 cmof a mixture of acid, cover with watch glass, glass or plastic plate and dissolved by heating. Once dissolved, rinse the glass or plate and the side of the Cup with water, add 10 cmsulphuric acid (1:1) and evaporated until a white smoke of sulfuric acid.

After cooling, pour 50 cmof water and dissolve the residue under heating. Add 1 cmof a solution of alum salesonline, water up to 150−200 cm, heated to 60−70 °C, poured 12 cmof solution of nitrate of silver, 20 cmsolution naternicola ammonium and boil for 15−20 minutes until the decomposition of ammonium naternicola (to complete the termination of allocation of bubbles of oxygen). The solution was cooled to 60 °C. and add ammonia to the transition of Nickel in a soluble ammonia complex and a weak smell of ammonia. Solution and the precipitate is kept for 20−30 minutes in a warm place to coagulate the precipitate, and the precipitate was filtered off on a loose filter and wash the beaker and filter with the sediment 5−6 times with a solution of ammonium chloride. The washed precipitate is washed from the filter with a jet of flammable water in the glass in which was conducted the deposition. The filter is washed with 20 cmof sulphuric acid (1:4), and then 5−6 times with hot water. The solution is diluted with water to 200 cm, add 5 cmof a solution of nitrate of silver, 20 cmsolution naternicola ammonium and boil for 15−20 minutes until the complete decomposition of ammonium naternicola (to complete the termination of allocation of bubbles of oxygen). Then repeat the precipitation of the hydroxides of iron and aluminum with ammonia.

The washed precipitate is washed from the filter with hot water into a glass, which conducted the deposition, and the filter was washed with 5 cmof hot hydrochloric acid (1:1), and then 5−6* hot water. The solution was transferred to a volumetric flask with a capacity of 100 cmand then filled to the mark with water.
________________
* Consistent with the original. — Note the CODE.

Depending on the mass fraction of aluminium in the alloy aliquot select the appropriate part (see table.2) and further analysis is carried out, as indicated in the claims.3.3.1.1 and 3.3.1.2.

Table 2

3.3.3. For alloys containing tungsten

A sample of alloy weighing 1 g is placed in a beaker with a capacity of 300 cm, flow 20 cmof nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. After dissolution of the alloy watch glass or plate and the side of the Cup then rinsed with water, the solution is evaporated to a syrupy condition, dilute with water to 60 cmand incubated for 30−40 min in a warm place for lightening solution. The precipitate was filtered off on a tight filter with filtrowanie ground and washed 5−6 times with warm nitric acid (1:50) and discarded.

To the filtrate add 1 cmof a solution of alum salesonline, 2 g of ammonium chloride and then act as described in section 3.3.1. In a volumetric flask with a capacity of 100 cmis placed 20 cmof the resulting solution and then act as described in section 3.3.1.1 or 3.3.1.2.

3.3.4. For other alloys

A sample of alloy weighing 1 g is placed in a beaker with a capacity of 300 cm, flow 20 cmof nitric acid (1:1), beaker cover watch glass, glass or plastic plate and dissolved by heating. After dissolution of the alloy watch glass or plate and the side of the Cup then rinsed with water, the solution diluted with water to 150 cm, add 1 cmof a solution of alum salesonline, 2 g of ammonium chloride and then act as described in section 3.3.1.

For the photometry data in a volumetric flask with a capacity of 100 cmis placed 20 cmof the resulting solution and then act as described in section 3.3.1.1 or 3.3.1.2.

3.3.5. Construction of calibration curve

In a volumetric flask with a capacity of 100 cmis placed 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution B aluminum, top up with water to 20−30 cmand then do as described in claim 3.3.1.1 or 3.3.1.2.

3.4. Processing of the results

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

,

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

 — the weight of the portion corresponding to aliquote part of the solution,

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 of permissible differences given in table.1.

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 atomic absorption method, in accordance with GOST 25086.

4. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF ALUMINIUM

4.1. The essence of the method

The method is based on measuring the absorption of light by atoms of aluminium produced during the introduction of the analyzed solution in the flame acetylene — nitrous oxide.

4.2. Apparatus, reagents and solutions

Atomic absorption spectrometer with a radiation source for aluminium.

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

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

Hydrofluoric acid according to GOST 10484.

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

Hydrogen peroxide according to GOST 10929.

Ammonium chloride according to GOST 3773.

Iron chloride according to GOST 4147, a solution of 15 g/DM:1.5 g of ferric chloride dissolved in 30 cmof hydrochloric acid (1:1) and dilute with water to 100 cm.

Ammonia water according to GOST 3760, diluted 1:19.

Potassium chloride according to GOST 4237, solution 200 g/DM.

Aluminium GOST 11069.

Standard aluminium solution: 0.1 g of aluminium is dissolved by heating with 10 cmof hydrochloric 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 0.001 g of aluminium.

Copper according to the GOST 859.

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*.
_______________
* Valid GOST 849−97. — Note the CODE.

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

Nickel.

4.3. Analysis

4.3.1. For alloys not containing silicon and chromium

For alloys with a mass fraction of aluminum is less than 0.1% of the weighed mass, are given in table.3, is placed in a beaker with a capacity of 600 cmand dissolved by heating in 30 cmof nitric acid (1:1). After dissolution the solution is diluted with water to a volume of 200 cm, add 3−4 g of ammonium chloride and 5 cm.of solution of ferric chloride (if the mass fraction of iron in the alloy is less than 0.5%).

Table 3

The solution is heated to 70−80 °C, ammonia is added to complete the transition of copper or Nickel in a soluble ammonia complex, and the solution is kept in a warm place for 20 min, the solution was then filtered through a medium density filter, the precipitate washed with warm solution of ammonia (1:19). The filter cake is dissolved in 10 cmof hydrochloric acid (1:1) with addition of 2−4 drops of hydrogen peroxide, the filter washed with hot water, the solution transferred to a volumetric flask with a capacity of 100 cm. The solution is cooled, add 2cmof a solution of potassium chloride and add water to the mark.

For alloys with a mass fraction of aluminum, more than 0.1% of the weighed mass, are given in table.3, is dissolved by heating in 10 cmof nitric acid (1:1).

The solution was transferred to a volumetric flask with a capacity of 100 cm, add 2 cmof a solution of potassium chloride and add water to the mark.

Measure the atomic absorption of aluminum in the flame acetylene-nitrous oxide at a wavelength of 309,3 nm parallel to the calibration solutions.

4.3.2. For alloys containing silicon and chrome

A portion of the alloy (see table.3) is placed in a platinum Cup and dissolve by heating in 10−30 cmof nitric acid (1:1) and 2−6 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. For the mass concentration of aluminum less than 0.1% are received as specified in clause 4.3.1.

For the mass concentration of aluminium above 0.1% solution are transferred into a measuring flask with a capacity of 100 cm, add 2 cmof a solution of potassium chloride and add water to the mark. Measure the atomic absorption of aluminum, as specified in clause 4.3.1.

4.3.3. Construction of calibration curve

In six of the seven volumetric flasks with a capacity of 100 cmis placed 0,3; 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution of aluminium, which corresponds to 0,3; 1,0; 2,0; 3,0; 4,0 and 5,0 mg of aluminum. To all flasks add 5 cmof hydrochloric acid (1:1), 2 cmof potassium chloride solution with mass fraction of aluminium than 0.1% add aliquote the volume of the solution of copper (if copper is the basis of alloy) or Nickel (if Nickel is a base alloy) (see table.3) and top up with water to the mark. Measure the atomic absorption of aluminum, as specified in clause 4.3.1. According to the obtained results build a calibration curve.

4.4. Processing of the results

4.4.1. Mass fraction of aluminium () in percent is calculated by the formula

,

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

 — the volume of the solution sample, cm;

 — the weight of the portion of the sample,

4.4.2. 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.1.

4.4.3. 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 comparing the results obtained with titrimetric or photometric methods in accordance with GOST 25086.