GOST 12357-84

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  ГОСТ 12357-84

GOST 12357−84 Steel alloyed and high alloy. Methods for determination of aluminium

GOST 12357−84

Group B39

STATE STANDARD OF THE USSR

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of aluminium

Steels alloyed and highalloyed.
Methods for the determination of aluminium

AXTU 0809

Valid from 01.01.85
to 01.01.90*
______________________________
* Expiration removed
Protocol N 4−93 inter-state Council
for standardization, Metrology and certification
(IUS N 4, 1994). — Note the CODE.

DEVELOPED by the Ministry of ferrous metallurgy of the USSR

PERFORMERS

N. P. Liakishev, V. T. Ababkov, S. M. Novokshenova, M. S. Dimova, N. Panarin, T. F. Rybin, E. D. Shuvalov, N. D. Zhukova, N. N. Alekseeva

INTRODUCED by the Ministry of ferrous metallurgy of the USSR

Member Of The Board V. G. Antipin

APPROVED AND put INTO EFFECT by decision of the USSR State Committee for standards from January 19, 1984 N 233

REPLACE GOST 12357−66 in addition to General guidance


This standard specifies methods for the determination of aluminium:

photometric with separation of 8-hydroxyquinoline and cupferron when the mass fraction of aluminum from 0.01 to 0.20%;

photometric with separation of the sodium hydroxide with the mass fraction of aluminum from 0.01 to 0.20%;

atomic absorption with electrothermal heating when the mass fraction of aluminum from 0.01 to 0.20%;

titrimetric when the mass fraction of aluminum of 0.20 to 7.0%;

atomic absorption with atomization in the flame when the mass fraction of aluminum of 0.20 to 7.0%;

gravity when the mass fraction of aluminum of 0.20 to 7.0%.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 20560−81.

2. PHOTOMETRIC METHOD WITH THE SEPARATION OF 8-HYDROXYQUINOLINE AND CUPFERRON

2.1. The essence of the method

The method is based on formation of colored complex compounds of aluminum, chromazurol S at pH (5,7±0,1) and alumininum at pH (4,9±0,2).

Chrome was removed in the form of chloride gromila. Aluminium is separated from Nickel, cobalt, tungsten, manganese and other elements by coprecipitation of oxichinolina phenolphthalein in ammonia environment in the presence of masking substances. Vanadium, titanium, niobium and zirconium removed by extraction of their chloroform capterranew.

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

a pH meter.

Hydrochloric acid according to GOST 14261−77 and diluted 1:1.

Nitric acid according to GOST 11125−78.

Acid chloric, H. h

Sulfuric acid according to GOST 14262−78 and diluted 1:1.

Oxalic acid, OS. h, a saturated solution.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, a solution with a mass concentration of 50 g/DM.

The aqueous ammonia, the OS. h

Unitiol Pharmacopoeia, a solution with a mass concentration of 200 g/DM; cook before eating.

Acetic acid according to GOST 18270−72 and diluted with 17:3; solution with molar concentration of 2 mol/DM: 118 cmof acetic acid are placed in a volumetric flask with a capacity of 1 DMand topped to the mark with water.

8-hydroxyquinoline according to GOST 5847−76, a solution with a mass concentration of 40 g/DMacetic acid (17:3); cook before eating.

Ethyl alcohol according to GOST 5962−67 GOST or 18300−72.

Phenolphthalein according to GOST 5850−72, solution in ethyl alcohol with a mass concentration of 20 g/DM.

The washing liquid: to 1 DMof water add 2−3 cmof a solution of 8-hydroxyquinoline, 2−3 cmof a solution of phenolphthalein and then pour the ammonia prior to the dyeing solution in a crimson color.

Hydrofluoric acid, OS. h

Potassium preservatory according to GOST 7172−76. Potassium permanganate according to GOST 20490−75, a solution with a mass concentration of 10 g/DM.

N-nitroso-N-phenylhydroxylamine ammonium salt (cupferron) according to GOST 5857−79, the solution with mass concentration 60 g/DM; cook before eating.

Chloroform according to GOST 20015−74.

Ascorbic acid according to GOST 4815−76, a solution with a mass concentration of 20 g/DM; cook before eating.

Chromazurol S, a solution with a mass concentration of 1 g/DM; solution is usable within a week.

Sodium acetate 3-water, OS. h, the solution with the mass concentration of 272 g/DM.

Buffer solution with a pH of 5.8: volumetric flask with a capacity of 500 cmwas placed 41 cmof acetic acid solution with molar concentration of 2 mol/DMand topped to the mark with a solution of sodium acetate. the pH of the buffer solution controlled by pH-meter.

Buffer solution with a pH of 4.9: in a volumetric flask with a capacity of 500 cm208 cm placeof acetic acid solution with molar concentration of 2 mol/DMand topped to the mark with a solution of sodium acetate. the pH of the buffer solution controlled by pH-meter.

Aluminum according to GOST 9859−74, a solution with a mass concentration of 1 g/DM; prepared the day before use; usable for two weeks.

Carbonyl iron brand PS according to GOST 13610−79 with a mass fraction of not more than 0.001% aluminum.

Aluminum brand А999, A995, A97 A95 or GOST 11069−74.

Standard solutions of aluminium.

The solution And the mass concentration of aluminum 0.001 g/cm: 1.0 g of aluminium is dissolved in 100 cmof hydrochloric acid (1:1), add nitric acid until the termination of foaming. The solution was boiled, cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Solution B with a mass concentration of aluminium 0.0001 g/cm: 10 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm, poured 5cmof hydrochloric acid, made up to the mark with water and mix.

The solution with the mass concentration of aluminium 0,00002 g/cm: 20 cmstandard solution B is transferred to a volumetric flask with a capacity of 100 cm, poured 5cmof hydrochloric acid, add water

th to the mark and mix.

2.3. Analysis

2.3.1. A sample weighing 0.2 g was placed in a quartz glass with a capacity of 250−300 cmand dissolved by heating in 15−20 cmof hydrochloric acid. To the control experience for contamination of reagents aluminum suspension carbonyl iron is carried out through all stages of the analysis. Add 2−3 cmof nitric acid and continue the heating until complete dissolution of the sample. Allowed dissolution in 30 — 40 cmof a mixture of hydrochloric and nitric acids in the ratio 3:1. To the solution add 30 cmof perchloric acid. Beaker cover watch glass, and heat until copious fumes of perchloric acid and oxidation of chromium. Lifting the glass, are added dropwise hydrochloric acid and distilled chromium in the form of red-brown fumes of chloride gromila. Evaporation to fumes of perchloric acid and the chromium Stripping is repeated many times until the termination of allocation of vapors chloride gromila. The solution was evaporated to dryness, the dry residue add 3 cmof hydrochloric acid and dissolved salts. Pour 20 cmof a solution of oxalic acid, 20 cmsolution of Trilon B and 100−130 cmof water. The solution is poured ammonia until the appearance of the precipitate of the hydroxide or to pH (8,5±0,2) (control pH meter) and 10 cmof ammonia. Add 15 cmof a solution of unitiol, 4 cmsolution of 8-hydroxyquinoline, 2 cmof a solution of phenolphthalein. The precipitate is immediately filtered on two filters «white ribbon» and washed 8−10 times with wash fluid. The filter with precipitate was placed in a platinum crucible, dried, incinerated and calcined at 800−900°C for 30 min. To the residue add 5−7 drops of sulfuric acid (1:1) and 1−5 cmhydrofluoric acid and distilled silicon when heated. The residue was dried in the oven and calcined at 700−800°C for 2−3 min. Add 1 g of potassium peacemaking and fused in a muffle furnace at 700−800°C. the Melt is dissolved in water. The solution was poured into a quartz beaker, add 5 cmof sulphuric acid (1 :1), 1−2 drops of solution of potassium permanganate and dilute with water to 50−60 cm. The glass solution was cooled to a temperature of (5−10)°C. the Solution is poured into an extraction funnel, add to it a 10 cmcooled to (5−10)°C solution of cupferron, after 5 min, add 20 cmof chloroform and stirred for 1 min. After phase separation, the organic layer (bottom) is discarded. Extraction with 20 cmof chloroform, is carried out 1 to 2 more times, achieving the discoloration of the organic layer. The second and third extraction phase is stirred for 30 s.

The aqueous phase is poured into the quartz beaker, evaporated to a volume of 3−5 cm, pour 1−2 cmof sulphuric acid and 3−5 cmof nitric acid. Beaker cover watch glass, and shatter when heated organic residues. The appearance of the dense vapors of sulphuric acid dropwise carefully pour the nitric acid. The operation is repeated until the complete destruction of organic residues. The solution is evaporated until the appearance of sulphuric acid fumes, wash the side of the Cup 1−2 cmof water and the solution is evaporated to a volume of 0.5 cm, cooled and poured 20−30 cmof water is poured into a measuring flask with a capacity of 100 cm, made up to the mark with water and mix.

To perform the photometric reaction of aluminum chromazurol S aliquote portion 5 cmwhen the mass fraction of aluminum of not more than 0.05% and 2 cmfor the mass concentration of aluminum in excess of 0.05% were placed in a glass with a capacity of 50−100 cm, pour 2 cmof ascorbic acid solution, 5 cmof a solution of chromazurol S, 5 cmbuffer solution (pH 5.8) and ammonia is added to pH (5,7±0,1) (control pH meter). Allowed the addition of ammonia to a pH (5,7±0,1) before addition of buffer solution. The solution is poured into a measuring flask with a capacity of 50 cm, made up to the mark with water and mix. After 30 min, measure the optical density of the solution at a wavelength of 545 nm relative to the solution comparison. For solution comparison in volumetric flask with a capacity of 50 cmadd 5 cmof chromazurol S, 5 cmbuffer solution (pH 5.8), made up to the mark with water and mix.

To perform the photometric reaction with alumininum aliquot portion of 10 cmwhen the mass fraction of aluminum is less than 0.05% and 2 cmfor the mass concentration of aluminum in excess of 0.05% were placed in a glass with a capacity of 50−100 cm, add 2 cmof ascorbic acid solution, ammonia to pH 3−4 (pH control-by meter) 2 cmsolution aluminon 5 cmbuffer solution (pH 4.9) and ammonia is added to pH (4,9±0,2) (control pH meter). Allowed the addition of ammonia to a pH (4,9±0,2) before addition of buffer solution. The solution is poured into a measuring flask with a capacity of 50 cm, made up to the mark with water and mix. After 30 min, measure the optical density of the solution at a wavelength of 536 nm relative to solution comparison. For solution comparison in volumetric flask with a capacity of 50 cmadd 2 cmof a solution of aluminon 5 cmbuffer solution, made up to the mark with water and mix.

The mass of aluminum

niya find the calibration schedule.

2.3.2. Construction of calibration graphs

10 silica glasses with a capacity of 250−300 cmis placed sample of carbonyl iron with a mass of 0.2 g. Pour 1,0; 2,0; 3,0; 4,0; 5,0; 6,0; 8,0 and 10.0 cmstandard solution, and 2.5 and 4.0 cmstandard solution B. pour the batches of 15−20 cmof hydrochloric acid and dissolved by heating. Add 2−3 cmof nitric acid and then act as described in section 2.3.1.

The found values of optical density of solutions and their corresponding masses of aluminium to build the calibration graph. At the same time on the y-axis is applied to the value of the optical density of the solution in the reference experiment.

2.4. Processing of the results

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

where is the mass of aluminium in aliquote part of the analyzed solution found by the calibration schedule g;

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

2.4.2. Allowable absolute differences of the results of three parallel measurements at p = 0.95 does not exceed the permissible values given in table.1.

Table 1

3. PHOTOMETRIC METHOD WITH THE SEPARATION OF THE SODIUM HYDROXIDE

3.1. The essence of the method

The method is based on formation of colored complex compounds of aluminum, chromazurol S and a polyvinyl alcohol at a pH (6,2±0,4).

Iron, chromium, titanium and other elements is separated by sodium hydroxide. When the mass fraction of chromium of more than 10% of its pre-distilled chloride gromila. Nickel, cobalt and manganese is separated by precipitation of aluminium hexamine. The influence of vanadium take into account the introduction of it solutions for constructing the calibration graphs.

3.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

a pH meter.

Hydrochloric acid according to GOST 14261−77 and diluted 1:1 and 1:20.

Nitric acid according to GOST 11125−78 and diluted 1:1.

Acid chloric, H. h

Sulfuric acid according to GOST 14262−78 and diluted 1:1.

Hydrofluoric acid, OS. h

Sodium carbonate according to GOST 83−79.

Ammonium chloride, OS. h

Methenamine USP, solutions with a mass concentration of 5 and 250 g/DM; store in a plastic container.

Zinc chloride according to GOST 4529−78, a solution with a mass concentration of 100 g/l: 100 g zinc chloride dissolved in water containing 10 cmof hydrochloric acid, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Boric acid according to GOST 9656−75.

Sodium hydroxide, OS. hours, solutions with mass concentration of 200 and 50 g/DM; store in a plastic container.

Ascorbic acid according to GOST 4815−76 with a mass concentration of 50 g/DM; cook before eating.

Urea according to GOST 6691−77, a solution with a mass concentration of 15 g/DM; cook before eating. Ethyl alcohol according to GOST 5962−67 or 18300−72.

Chromazurol S, a solution with a mass concentration of 1 g/DM: 1 g of chromazurol placed in a beaker, moistened with water and dissolved in 6 cm.of nitric acid (1:1). The solution was transferred to a volumetric flask with a capacity of 1 DMcontaining 500 cmof ethyl alcohol and 200 cmof water, add 50 cmof a solution of urea and top up with water to the mark; usable in two weeks.

The polyvinyl alcohol GOST 10779−78, a solution with a mass concentration of 40 g/DM.

Ammonium acetate qualifying OS. h, the solution with the mass concentration of 548 g/DM.

Sodium acetate 3-water OS. h, the solution with the mass concentration of 218 g/DM; store in a plastic container.

Buffer solution with a pH of (7,1±0,1): 500 cmof a solution of ammonium acetate combined with 500 cmof a solution of sodium acetate and mix; store in a plastic container.

Carbonyl iron brand PS according to GOST 13610−79, with a mass fraction of not more than 0.001% aluminum.

Sodium sanitarily according to GOST 195−77.

Vanadium pentoxide, OS. h

The vanadium solution with a mass concentration of 0.001 g/DM: 1,7851 g of vanadium pentoxide were placed in a glass, pour 50 cmof the sulphuric acid, heated to dissolve the sample, gently add 5 cmof nitric acid, evaporated to the appearance of sulphuric acid fumes. The solution was cooled, added to 200−250 cmof water, stirred, filtered through a filter of medium density in a volumetric flask with a capacity of 1 DM, the filter washed with warm water, collecting the wash liquid in the same flask. The solution was poured 100 cmof sulphuric acid (1:1). The solution was cooled, made up to the mark with water and mix.

Aluminum brand А999, A995, A97 A95 or GOST 11069−74.

Standard solutions of aluminium.

The solution And the mass concentration of aluminum 0.001 g/cmand 1.0 g of aluminum is placed in a beaker with a capacity of 250−300 cm, flow 50 cmhydrochloric acid solution (1:1), 3−4 drops of nitric acid and dissolved by heating. Add 100−150 cmof hot water and heated to dissolve the salts. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, add 30 cmof hydrochloric acid, made up to the mark with water and mix.

Solution B with a mass concentration of aluminium of 0.00005 g/cm: 5 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm, poured 5cmof hydrochloric acid, add water

Oh to the mark and mix.

3.3. Analysis

3.3.1. A sample mass of 0.5 g when the mass fraction of aluminum is less than 0.05%, or 0.25 g when the mass fraction of aluminum of more than 0.05% is placed in a quartz glass with a capacity of 200−300 cmand is dissolved by heating in 20−25 cmof hydrochloric acid.

To the control experience for contamination of reagents aluminum to the suspension of carbonyl iron was added to a solution of vanadium in a quantity approximately corresponding to the concentration in the sample mixture is carried out through all stages of the analysis.

Add 3−5 cmof nitric acid and continue the heating until complete dissolution of the sample. Allowed dissolution in 30−40 cmof a mixture of hydrochloric and nitric acids in the ratio 3:1.

When the mass fraction of chromium in the analyzed material more than 10% of the solution add 50 cmof perchloric acid. Beaker cover watch glass, and heat until copious fumes of perchloric acid and oxidation of chromium. Lifting the glass, are added dropwise hydrochloric acid and distilled chromium in the form of red-brown fumes of chloride gromila. Evaporation to fumes of perchloric acid and the chromium Stripping is repeated many times until the termination of allocation of vapors chloride gromila.

The solution was evaporated to dryness. To the dry residue add 10 cmof hydrochloric acid and again evaporated to dryness. Treatment of dry residue with hydrochloric acid repeated. After cooling, add 10 cmof hydrochloric acid and heated to dissolve the salts. To the solution was added 30−40 cmof hot water and filtered off the insoluble residue on a dense filter that contains the pulp. The filter cake was washed 2 — 3 times with hot hydrochloric acid (1:20) and 2−3 times with hot water. Rinse water is attached to the main filtrate. The filter with precipitate was placed in a platinum crucible, dried and incinerated at 600 °C. the Residue in the crucible is moistened with 2−3 drops of sulphuric acid (1:1), 1−5 cmhydrofluoric acid and evaporated to remove vapors of sulfuric acid. To the dry residue are added 1 g of anhydrous sodium carbonate and fused at 1000 °C for 10 min. the Melt was dissolved in 10−20 cmof hot water and added to the main filtrate.

When the mass fraction of Nickel and cobalt in excess of 15%, manganese in excess of 2% carried out an operation of separation by precipitation of aluminium hexamine. To this end, the solution was evaporated to a volume of 150 cm, cooled and added ammonia to pH 2.5 and 3.0 (control pH meter or universal indicator paper), add 2 g of ammonium chloride and 20−25 cmof a solution of hexamine (250 g/DM). The contents of the beaker heated to 90 °C, avoiding a boil, then kept warm on the stove for 15 — 20 min to coagulate the precipitate. The solution was filtered through a filter of medium density. The filter cake was washed 10−12 times with a warm solution of hexamine (5 g/DM) and dissolved in 40 cmof hydrochloric acid (1:1), collecting the solution in the beaker in which the precipitated hydroxide, the filter was washed 6−8 times with hot water, collecting the washings in the same beaker. The filter is discarded. The solution is evaporated to a volume of 10−20 cm, add 5 cmof a solution of zinc chloride and 0.7 g of boric acid and heated. The hot solution cautiously with careful hashing pour in a quartz flask containing the hot sodium hydroxide solution with a mass concentration of 200 g/DMof 30 cmwhen the mass fraction of aluminum of more than 0.05 percent and 75 cmwhen the mass fraction of aluminum of more than 0.05 percent. After cooling, the contents of the flask transferred to a volumetric flask with a capacity of 100 cmor 250 cmfor the mass concentration of aluminum is less than 0.05% or higher than 0.05%, respectively, made up to the mark with water and mix. After settling the solution is filtered through a dry filter, the average density in the dry quartz beaker, discarding the first portions of the filtrate.

Aliquot part of the solution was 10 cmwere placed in a glass containing 3 cmof hydrochloric acid (1:1) and 10 cmof water. the pH of the solution should be not more than 1 (control pH meter). Then add 2 cmof ascorbic acid solution and set pH (1,5±0,1) by adding in small portions while stirring the sodium hydroxide solution with a mass concentration of 50 mg/DM. The solution was transferred to a volumetric flask with a capacity of 100 cm,is added with stirring 10 cmsolution of chromazurol S, 5 cmsolution of polyvinyl alcohol and 20 cmbuffer solution. Dilute to the mark with water and mix. After 30 min, measure the optical density of the solution at a wavelength of 620 nm relative to water.

The weight of aluminium find

the calibration schedule.

3.3.2. Construction of calibration graphs

3.3.2.1. For steels with a mass fraction of aluminum is less than 0.05% five quartz cups placed sample of carbonyl iron with a mass of 0.5 g, flow 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard aluminum solution B and add solution of vanadium in amounts roughly corresponding to content in the sample analyzed steel. Then pour the 20−25 cmof hydrochloric acid. Then do as described in section 3.3.1. The found values of optical density of the solutions and the corresponding content of the aluminium build of the calibration graphs. At the same time on the y-axis is applied to the value of the optical density of the solution in the reference experiment.

3.3.2.2. For steels with a mass fraction of aluminum of more than 0.05% in five quartz cups placed sample of carbonyl iron with a mass of 0.25 g, pour 2,5; 5,0; 7,5; 10,0 and 12,5 cmof a standard solution of aluminium B. Then do as described in section 3.3.2.1.

3.4. Processing of results — clause 2.4.

4. ATOMIC ABSORPTION METHOD WITH ELECTROTHERMAL HEATING

4.1. The essence of the method

The method is based on the measurement values of radiation absorption by free atoms of aluminum at 309,3 nm, formed by thermal dissociation of aluminum compounds in the graphite cuvette.

4.2. Apparatus, reagents and solutions

Atomic absorption spectrophotometer with graphite cuvette.

Lamp for aluminium.

Argon according to GOST 10157−79.

Hydrochloric acid according to GOST 14261−77 and diluted 1:1.

Nitric acid according to GOST 11125−78.

Hydrofluoric acid, OS. h

Sulfuric acid according to GOST 14262−78 and diluted 1:1 and 1:100.

Oxalic acid, OS. h, a saturated solution.

Potassium preservatory according to GOST 7172−76.

Carbonyl iron brand PS according to GOST 13610−79 with a mass fraction of less than 0.001% aluminum.

Steel for the preparation of calibration curve containing aluminum in accordance with the table.2, similar in composition to steel test, differing from it by the mass fraction of the basic macro components of ±5%.

Table 2

Aluminum brand А999, A995, A97 A95 or GOST 11069−74.

Standard solutions of aluminium.

The solution And the mass concentration of aluminum 0.001 g/cmand 1.0 g of aluminum is placed in a beaker with a capacity of 250−300 cm, flow 50 cmhydrochloric acid solution (1:1), 2−3 cmof nitric acid and dissolved by heating. Cool, add 50 cmof sulfuric acid solution (1:1) and evaporated to sulphuric acid fumes. Cool, wash the side of the Cup with water and repeat the operation of evaporation. The cooled solution is transferred to a volumetric flask with a capacity of 1 DMcontaining 50 cmof sulfuric acid solution (1:1). Diluted with water, cooled, made up to the mark with water and mix.

Solution B with a mass concentration of aluminium of 0.00005 g/cm: 5 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm, pour 2 cmof sulphuric acid, made up to the mark with water and peremeshav

ayut.

4.3. Analysis

4.3.1. The sample mass depending on the mass fraction of aluminium in steel in accordance with table.2 is placed in a quartz beaker, poured 20−30 cmof hydrochloric acid, cover the beaker and dissolve for 30−40 min when heated. To the control experience for contamination of reagents aluminum suspension carbonyl iron is carried out through all stages of the analysis. Then add 4−5 cmof nitric acid and continue heating to complete decomposition of the sample.

Allowed dissolution in 30−40 cmof a mixture of hydrochloric and nitric acids in the ratio 3:1. To the cooled solution add 10 cmsulphuric acid and evaporated until the appearance of sulphuric acid fumes. The solution was cooled. To a solution of steel containing no tungsten or niobium, pour 50−70 cmof hot water; the solution steel containing tungsten or niobium, pour 50 cmof a solution of oxalic acid and 20 cmof water. The solution is heated to dissolve the precipitated salts filtered off and the precipitate of silicic acid on the two filters «white ribbon», collecting the filtrate in a volumetric flask with a capacity of 250 cm. Filter the precipitate was washed 10−12 times with diluted sulfuric acid (1:100). The filter with precipitate was placed in a platinum crucible, dried, incinerated and calcined at 800−900°C for 30 min. To the residue add 2−3 drops of sulfuric acid (1:1) and 1−5 cmhydrofluoric acid and distilled silicon when heated. The residue was dried in the oven and calcined in muffle at 700−800°C for 2−3 min. Add 1 g of potassium peacemaking (weighed on technical scales) and fused in a muffle furnace at 700−800°C. the Melt is dissolved in water. The solution is attached to the main filtrate, made up to the mark with water and mix. Take a micropipette aliquot part of the solution, equal to 0.01 or 0.02 cm(in accordance with the scope of the linear dependence of the aluminum concentration from absorption for the device), enter it into the graphite cuvette, dried for 30 s at 100 °C, thermal destruction is carried out for 20 s at 1400 °C and atomization for 8 s at 2700 °C. as the shielding gas is argon. The magnitude of radiation absorption at 309,3 nm locked with a registered device. For measurements taken at least three alikvotnih parts of the solution. The cuvette is washed by the introduction of 0.01−0.02 cmof water and the inclusion of all stages of heating for the program.

From the values of absorbance of the analyzed solution is subtracted the value of the optical density of the solution in the reference experiment.

The mass of aluminum is on a calibration schedule, as amended by the control of op

it.

4.3.2. Construction of calibration curve

Ten quartz glasses with a capacity of 250−300 cmis placed hanging steel for a calibration chart in accordance with table.2. Nine of cups poured consistently 1,0; 1,5;. 2,0, 2,5; 3,0; 3,5; 4,0; 4,5 and 5.0 cmstandard solution B aluminum. Tenth glass is used for the reference experiment.

All the glasses are poured 20−30 cmof hydrochloric acid. Then do as stated in p 4.3.1. From the value of the optical density of solutions for calibration curve subtract the value of the optical density of the solution in the reference experiment.

On the found values of optical density of the solutions and their corresponding values of aluminium concentrations to build a calibration curve.

Solutions for calibration curve stored in tightly closed plastic or fluoropolymer vessels for 1 month.

4.4. Processing of the results

4.4.1. 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 steel,

4.4.2. Allowable absolute differences of the results of three parallel measurements at p = 0.95 does not exceed the permissible values given in table.1.

5. TITRIMETRIC METHOD

5.1. The essence of the method

The method is based on the reaction of formation of complex aluminium compounds with Trilon B in a weakly acid medium and subsequent titration of excess Trilon B with a solution of acetate of zinc.

The endpoint of a titration set visually by a colour change of the indicator kylinalove orange.

From iron, Nickel, chromium and other elements, aluminium is pre-separated by precipitation of sodium fluoride.

5.2. Equipment, reagents, solutions

a pH meter.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1

Nitric acid GOST 4461−77.

Sulfuric acid GOST 4204−77 and diluted 1:1, 1:100.

Hydrofluoric acid according to GOST 10484−78.

Boric acid according to GOST 9656−75, saturated solution.

A mixture of boric and hydrochloric acids: 300 cmsaturated at room temperature a solution of boric acid is added to 500 cmof hydrochloric acid and 1.2 DMwater. The solution was stirred.

Acetic acid GOST 61−75.

Potassium-sodium carbonate according to GOST 4332−76.

Ammonia water according to GOST 3760−79.

Ammonium acetate according to GOST 3117−78.

Ammonium disodium citrate according to GOST 3653−78, a solution with a mass concentration of 400 g/DM.

Ammonium oxalate according to GOST 5712−78, saturated solution.

The masking mixture is: 1 DMtwosemester solution of citrate of ammonium with the mass concentration of 400 g/DM1 DM was addedsaturated at room temperature a solution of ammonium oxalate and stirred.

Sodium fluoride according to GOST 4463−76, a solution with a mass concentration of 35 and 5 g/DM.

The technical rectified ethyl alcohol according to GOST 18300−72.

The indicator methyl red GOST 5853−51, a solution with a mass concentration of 2 g/DM: 0.2 g of the indicator is dissolved in 60 cmof ethanol and add 40 cmof water.

Sodium chloride according to GOST 4233−77.

Selenology orange indicator: 0.1 g of the indicator is triturated in a mortar with 10 g of sodium chloride.

Buffer solution with a pH of 6.0: 500 g ammonium acetate and dissolve in 1 DMof water and add with constant stirring the glacial acetic acid to obtain a pH of 6.0. The pH value of the solution, check the pH meter. The prepared solution was filtered.

Aluminium metal primary brands А999, A995, A99, A97 GOST 11069−74.

A standard solution with a mass concentration of aluminum 0.001 g/cm: 0.1 g of aluminum metal is placed in a beaker with a capacity of 100−150 cm, 20−30 cm was addedhydrochloric acid (1:1), 3−4 cmof nitric acid (1:1) and dissolved by heating. The solution is cooled, add 10 cmsulphuric acid and evaporated to fumes of sulfuric acid. After cooling the salt is dissolved in 30−40 cmof water, the solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Zinc acetate 2-water according to GOST 5823−78, solution with molar concentration of 0.05 mol/DM: 11.0 g of zinc acetate dissolved in 300 cmof water, then add 10 cmof glacial acetic acid, the solution was filtered in a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Zinc acetate solution with a molar concentration of 0.025 mol/l: 500 cmof a solution of zinc acetate with a molar concentration of 0.05 mol/DMare placed in a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, solution with molar concentration of 0.05 mol/DM: 18.6 g Trilon B dissolved in 250−300 cmof water at low heat. The solution was filtered, transferred to a volumetric flask with a capacity of 1 DM, top up with water .to the mark and mix; the solution with a molar concentration of 0.025 mol/l: 500 cmof a solution of Trilon B with molar concentration of 0.05 mol/DMare placed in a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

The mass concentration of the solution Trilon B set by the standard solution of aluminium. For this purpose a standard solution of aluminium in an amount corresponding mass in the sample the test sample was placed in a glass or flask. Then do as described in section 5.3.

Allowed mass concentration of Trilon B to install the standard sample of steel, similar in chemical composition and mass fraction of aluminium to the sample.

Mass concentration of Trilon B (), expressed in g/cmof aluminum, calculated according to the formula

where is the mass of aluminium in aliquote part of the standard solution taken for titration, g;

 — volume of solution Trilon B taken for titration, cm;

 — the volume of solution of acetate of zinc, consumed in the titration of excess Trilon B, cm;

 — factor for recalculation of the amount of acetic acid and zinc on the volume of Trilon B.

To determine the coefficient values and accounting values a test of experience to use the solution in the reference experiment on the reagents, carried out through all stages of analysis, as specified in clause 5.3.

The ratio is calculated by the formula

where  — volume of solution Trilon B taken for titration, cm;

 — the volume of solution of acetate of zinc, used for titration of Trilon B, cm.

5.3. Analysis

The weight of steel depending on the mass fraction of aluminium is determined by the table.3.

Table 3

The weight of steel is placed in a beaker or flask, add 25−30 cmof hydrochloric acid, 5−10 cmof nitric acid and heated to dissolve sample. The solution was cooled, poured 10 cmof sulphuric acid and evaporated until the appearance of sulphuric acid fumes. The glass is cooled, poured 80−100 cmof water and heated to dissolve the salts.

If in the analyzed steel contains tungsten, niobium or tantalum salt is dissolved in 30 cmmasking mixture and 50−70 cmof water.

The solution is filtered through two filters «white ribbon». The filter residue was washed 4−5 times with hot sulfuric acid (1:100), collecting the filtrate and washings in a beaker with a capacity of 350−400 cm. Retain the filtrate (stock solution), filter the precipitate is placed in a platinum crucible, dried, incinerated and calcined at 800−900°C.

The crucible with residue was cooled, moistened the residue with a few drops of water, add 3−4 drops of sulfuric acid, or 5−6 drops in the presence in the precipitate of oxides of tungsten and add 3−5 cmhydrofluoric acid.

The contents of the crucible carefully evaporated until vapours of sulphuric acid, is calcined at 800−900°C, cooled and the residue is fused with 1.0−1.5 g of potassium — sodium carbonate at 1000−1100°C.

The melt is cooled, leached in 40−50 cmof hot water and dissolved by heating. The solution was filtered through a filter «white ribbon», the precipitate is washed 4−5 times with sulfuric acid (1:100), collecting the filtrate and washings into the beaker with the main solution.

If you previously by dissolving salts of the masking mixture was added to the solution add 30 cmmasking mixture and 20−22 cmof ammonia. The solution was stirred, cooled and added ammonia or sulfuric acid (1:1) to establish a pH of 5.9−6.0 mm. The pH of the analyzed solution controlled by pH-meter.

To the solution at careful hashing pour the 80−100 cmof a solution of sodium fluoride with a mass concentration of 35 g/DMand for 20−25 min. the solution was periodically stirred. Then the precipitate of cryolite is filtered by two filter «blue ribbon» and washed 12−15 times with a solution of sodium fluoride with a mass concentration of 5 g/DMto a negative reaction to ions of iron in the lavage.

The precipitate is dissolved 50−70 cma boiling mixture of boric and hydrochloric acids, collecting the solution in a glass, which conducted the deposition. The filter was washed 5−6 times with hot water, collecting the washings in the same beaker.

To the solution add 5−7 cmof sulphuric acid and evaporated to start the selection of sulfuric acid vapor. Then add a few drops of nitric acid for the destruction of organic substances, and the solution again evaporated to fumes of sulfuric acid. The side of the Cup washed with water and the contents of the glass again evaporated to fumes of sulfuric acid. The solution was cooled, added 130−150 cmof water and heated to dissolve the salts. After cooling the solution add 2−3 drops of methyl red indicator and from a burette poured 20 cmof a solution of Trilon B.

When the mass fraction of aluminium in steel up to 0.5% in the analyzed solution add a solution of Trilon B with molar concentration of 0.025 mol/DMand excess of it titrated with a solution of zinc acetate with a molar concentration of 0.025 mol/DM.

When the mass fraction of aluminium in steels over 0.5% is added Trilon B solution with molar concentration of 0.05 mol/DMand excess of it titrated with a solution of zinc acetate with a molar concentration of 0.05 mol/DM.

Then the solution is poured ammonia until yellow paint, 15 cmbuffer solution and gently boiled for 1−3 min.

The solution was cooled and titrated with a solution of acetate of zinc in the presence of an indicator kylinalove orange to the transition of color from yellow to

red-crimson.

5.4. Processing of the results

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

where  — volume of solution Trilon B taken for titration, cm;

 — the volume of solution of acetate of zinc, consumed in the titration of excess Trilon B, cm;

 — the ratio of volume of acetic acid and zinc on the volume of Trilon B;

 — mass concentration of the solution Trilon B, expressed in g/cmof aluminum;

the weight of steel, g

.

5.4.2. Allowable absolute discrepancies in the results of parallel measurements at p = 0.95 does not exceed the permissible values given in table.4.

Table 4

6. ATOMIC ABSORPTION METHOD WITH FLAME ATOMIZATION

6.1. The essence of the method

The method is based on measurement at =309,3 nm of the absorption of resonance radiation by free atoms of aluminum, formed as a result of spraying the test solution into the flame nitrous oxide — acetylene.

6.2. Equipment, reagents, solutions

Atomic absorption spectrophotometer with flame atomizer.

Lamp with hollow cathode for the determination of aluminium.

The cylinder with acetylene according to GOST 5457−75.

A tank of nitrous oxide.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1, 1:100.

Sulfuric acid according to GOST 4204−77.

Nitric acid GOST 4461−77.

Hydrofluoric acid according to GOST 10484−73.

Potassium-sodium carbonate according to GOST 4332−76.

Aluminum metal brand А999, A995, A99, A97 GOST 11069−74.

A standard solution with a mass concentration of aluminum 0.001 g/cm: 0.25 g of aluminum metal is placed in a beaker with a capacity of 250−300 cmand dissolved under moderate heating in 30−40 cmof hydrochloric acid (1:1). Cautiously added dropwise 5−7 cmof nitric acid and boil to remove oxides of nitrogen. Then pour 100−150 cmof hot water, the solution was cooled, transferred to a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

6.3. Preparation of the device

Set the spectrophotometer at a resonance line of 309,3 nm. After turning on gas supply and ignition of the burner in the flame spray water and set the zero point of the instrument.

6.4. Analysis

6.4.1. The weight of steel weight of 1 g when the mass fraction of aluminum of 0.20 to 0.50% or 0.5 g when the mass fraction of aluminum from 0.50 to 3.0%, or 0.25 g when the mass fraction of aluminum from 3.0 to 7.0% were placed in a glass with a capacity of 250−300 cmand dissolved by heating at 20−50 cmof hydrochloric acid. Then cautiously, drop by drop, add 5−10 cmof nitric acid. The solution was evaporated to wet salts. Salt dissolved in 5 cmof hydrochloric acid in low heat, add 40−50 cmof hot water and filter the solution through two filters «white ribbon» with the addition filtrowanie mass. Filter the precipitate was washed several times with hot hydrochloric acid (1:100) and two or three times with hot water. The filtrate is saved.

The filter with precipitate was placed in a platinum crucible, dried, incinerated and calcined for 7−10 minutes at 800−900 °C. the cooled Crucible, add a few drops of water, 3−4 drops of sulphuric acid or 5−6 drops in the presence in the precipitate of oxides of tungsten, niobium, tantalum, 4−5 cm inhydrofluoric acid and evaporated to remove vapors of sulfuric acid.

Then, the crucible was calcined for 5−7 minutes at 800−900°C, cooled, add 1−1,5 g potassium carbonate-sodium and the contents of the crucible alloys at 1000−1100°C. After cooling, the melt is leached with hot water, add 10 cmof hydrochloric acid and dissolved by heating.

The solution attached to the original filtrate is evaporated to 70−80 cm, cooled and transferred to volumetric flask with a capacity of 100 cm.

Allowed another dilution of solutions so that the final concentration of aluminum was in the range of corresponding straight-line segment calibration curve.

The solution is filtered through dry filter «white ribbon», discarding the first two portions of the filtrate. Simultaneously with the execution of the analysis carried out control experience for contamination of reagents.

Is sprayed into the flame of the solution in the reference experiment, and then analyze the solutions in order of increasing aluminium concentrations to obtain stable readings for each solution.

Prior to introduction into the flame each of the analyzed solution is sprayed water to wash the system and check the zero point.

From the average value of absorbance of each of the analyzed solutions, the average value is subtracted absorption in the reference experiment.

The aluminum content found by calibration curve

.

6.4.2. Construction of calibration curve for the mass concentration of aluminum in the steel of 0.20 to 0.50%.

Six glasses with a capacity of 250−300 cmis placed 1 g of steel, similar in composition to the analyzed and containing less than 0.01% aluminum.

In five glasses consistently poured 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution aluminum. The sixth glass is used for the reference experiment. Then do as specified in clause 6.4.1.

On the found values of absorbance of solutions and relevant concentrations of aluminium to build the calibration graph.

6.4.3. Construction of calibration curve for the mass concentration of aluminum in steel from 0.50 to 7.0%

Six glasses with a capacity of 250−300 cmis placed at 0.5 or 0.25 g of steel, similar in composition to the analyzed with a mass fraction of aluminium less than 0.01%. In five glasses consistently poured 2,5; 5,0; 10; 15 and 20 cmof a standard solution of aluminum. The sixth glass is used for the reference experiment.

Then do as specified in clause 6.4.1.

On the found values of absorbance of solutions and relevant concentrations of aluminium to build the calibration graph.

6.5. Processing of the results

Mass fraction () in percent is calculated by the formula

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

the weight of steel,

6.6. Allowable absolute discrepancies in the results of parallel measurements at p = 0.95 does not exceed the permissible values given in table.4.

7. GRAVIMETRIC METHOD

7.1. The essence of the method

The method is based on the separation of aluminium from accompanying elements by precipitation of sodium fluoride, dissolving the precipitate of cryolite in the mixture of hydrochloric and boric acids and the deposition of the aluminum 8-autooksigenation or benzoatom ammonium. The precipitate is calcined to obtain aluminum oxide, and weighed.

7.2. Equipment, reagents, solutions

a pH meter.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1.

Nitric acid GOST 4461−77.

Sulfuric acid GOST 4204−77 and diluted 1:1, 1:100.

Acetic acid GOST 61−75.

Hydrofluoric acid according to GOST 10484−78.

Potassium-sodium carbonate according to GOST 4332−76.

Ammonia water according to GOST 3760−79 and diluted 1:1.

Ammonium acetate according to GOST 3117−78, a solution with a mass concentration of 200 and 20 g/DM.

Ammonium citrate, disodium GOST 3653−78, a solution with a mass concentration of 400 g/DM.

Ammonium oxalate according to GOST 5712−78, saturated solution.

The mask mixture to 1 DMof the solution dosagedosage ammonium citrate is added to 1 DMof saturated room temperature solution of ammonium oxalate and stirred.

Sodium fluoride according to GOST 4463−76, a solution with a mass concentration of 35 and 5 g/DM.

Boric acid according to GOST 9656−75, saturated solution.

A mixture of boric and hydrochloric acids: 300 cmsaturated at room temperature a solution of boric acid is added to 500 cmof hydrochloric acid and 1.2 DMwater. The solution was stirred.

The technical rectified ethyl alcohol according to GOST 18300−72.

The indicator methyl red GOST 5853−75, a solution with a mass concentration of 2 g/DM: 0.2 g of the indicator is dissolved in 60 cmof ethanol and add 40 cmof water.

8-hydroxyquinoline according to GOST 5847−76, a solution with a mass concentration of 2.5 g/DM: 50 g 8-hydroxyquinoline dissolved in 50 cmof acetic acid, add 950 cmwater, heated at 60 °C to dissolve, cooled and filtered.

Ammonium chloride according to GOST 3773−78.

The thioglycolic acid.

Ammonium benzoate, a solution with a mass concentration of 100 g/DM.

The washing liquid: 200 cmof solution of benzoate of ammonium is poured 500 cmof water and add acetic acid to pH 4.0 to 4.5 (universal paper).

7.3. Analysis

The weight of steel depending on the mass fraction of aluminium is determined by the table.5

Table 5

The weight of steel is placed in a beaker or flask and is dissolved by heating in 25 cmof hydrochloric acid, add 5−10 cmof nitric acid until the termination of foaming solutions. The solution was boiled to remove oxides of nitrogen, cooled, poured 10−15 cmof sulphuric acid and evaporated until the appearance of sulphuric acid fumes. The contents of the beaker cooled, poured 80−100 cmof water and heated to dissolve the salts.

If in the analyzed steel contains niobium, tungsten or tantalum salt is dissolved in 30 cmmasking mixture and add 50−70 cmof water.

The solution is filtered through two filters «white ribbon». The filter residue was washed 4−5 times with hot sulfuric acid (1:100), collecting the filtrate and washings in a beaker with a capacity of 350−400 cm. Retain the filtrate (stock solution), and the filter with the sediment was placed in a platinum crucible, dried, incinerated and calcined at 800−900°C. the crucible with the precipitate is cooled, the residue moistened with a few drops of water, add 3−4 drops of sulfuric acid, or 5−6 drops in the presence in the precipitate of oxides of tungsten, add 3−5 cmhydrofluoric acid. The contents of the crucible carefully evaporated until vapours of sulphuric acid, is calcined at 800−900°C, cooled and the residue is fused with 1.0−1.5 g potassium carbonate-sodium at 1000−1100°C.

The smelt is leached in 40−50 cmof hot water. The solution was filtered through a filter «white ribbon», the precipitate is washed 4−5 times with sulfuric acid (1:100), collecting the filtrate and washings into the beaker with the main solution. If you previously by dissolving salts of the masking mixture is added to the solution is added 30 cmmasking mixture, pour the ammonia solution to establish a pH 5,9−6,0, controlling the pH value of a solution of a pH meter.

The solution was cooled, while stirring, poured 80−100cmof the solution of sodium fluoride with a mass concentration of 35 g/DM.

After 20−25 min, the precipitate of cryolite is filtered by two filter «blue ribbon». Precipitate was washed 12−15 times with a solution of sodium fluoride with a mass concentration of 5 g/DMto a negative reaction to ions of iron in the lavage. The precipitate is dissolved in 50−70 cma boiling mixture of boric and hydrochloric acids, collecting the solution in a glass, which conducted the deposition. The filter was washed 5−6 times with hot water, collecting the washings in the same beaker.

The solution is neutralized with ammonia in the presence of methyl red indicator until the color changes, then add hydrochloric acid till the appearance of pink coloring and excess it 5 drops. To the solution was added 10 cmsolution of 8-orthoxylene when the mass fraction of aluminium up to 1.0% or 15−25 cmfor the mass concentration of aluminum in excess of 1.0% and 10 cmof a solution of acetate of ammonia with a mass concentration of 200 g/DM.

After mixing and the emergence of turbidity of the solution was added another 25 cmof a solution of ammonium acetate and 5 cmof ammonia. The solution was stirred and heated to 60−70°C and allowed to stand on the warm stove for 30 min. Precipitate oxichinolina aluminum filter on the filter medium density, containing a little filtrowanie mass, and washed 10−12 times with hot ammonium acetate solution with a mass concentration of 20 g/DM. The filter cake is dissolved in hot hydrochloric acid (1:1) and the filter well washed with hot water, collecting the solution in a glass, which conducted the deposition. For a more complete separation of aluminium from accompanying elements repeat the deposition of the aluminum 8-hydroxyquinoline, as specified above, or conduct a deposition benzoatom ammonium.

To this solution, a volume of 150−200 cm, add ammonia solution (1:1) before precipitation of hydroxides, which dissolve by adding dropwise hydrochloric acid (1:1). Then add 2 g of ammonium chloride, 3 cmof glacial acetic acid, 2cmof a solution of thioglycolic acid and 15 cmof a solution of benzoate of ammonium (partially eye-catching benzoic acid more energy goes into the solution). Then the addition of ammonia solution (1:1) or hydrochloric acid (1:1) was adjusted pH to values of 4.0 to 4.5 by universal indicator paper.

The solution is heated to boiling, moderately boiled for 5 min and left to stand for 10−15 min at 80 °C.

The solution was filtered through a filter of medium density. The glass and the filter cake is washed 6−8 times with hot solution of washing liquid. The filter with precipitate was placed in a calcined to constant weight weighed platinum crucible, dried, carefully incinerated and calcined at 1000−1100°C to constant weight.

At the same time conduct test experience to boot

yasnenie reagents.

7.4. Processing of the results

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

where is the mass of the crucible with the precipitate of aluminium oxide, g;

 — weight of crucible without the precipitate of aluminium oxide, g;

 — the mass of the crucible with the precipitate obtained from the reference experiment, g;

 — weight of crucible without sediment in the reference experiment, g;

0,5292 — the ratio of aluminium oxide to aluminium;

 — the weight of the portion,

7.5. Allowable absolute discrepancies in the results of parallel measurements at p = 0.95 does not exceed the permissible values given in table.4.