GOST 12361-2002

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  ГОСТ 12361-2002

GOST 12361−2002 Steel alloyed and high alloy. Methods for determination of niobium

GOST 12361−2002

Group B39

INTERSTATE STANDARD

STEEL ALLOYED AND HIGH-ALLOYED

Methods for determination of niobium

Alloyed and highalloyed steels. Methods for determination of niobium

ISS 77.080.20
AXTU 0709

Date of introduction 2003−05−01

Preface

1 DEVELOPED by the Russian Federation, the Interstate technical Committee for standardization MTK 145 «monitoring Methods of steel products"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 21 dated may 30, 2002)

The adoption voted:

3 Annex a of this standard corresponds to international standard ISO 9441−83* «Steel. Determination of niobium. Spectrophotometric method with reagent VAPOR"
________________
* Access to international and foreign documents mentioned here and below, you can get a link on the website shop.cntd.ru. — Note the manufacturer’s database.

4 Resolution of the State Committee of the Russian Federation on standardization and Metrology from September, 11th, 2002 N 331-St inter-state standard GOST 12361−2002 introduced as the national standard of the Russian Federation from 1 may 2003.

5 REPLACE GOST 12361−82

6 REISSUE. November 2005

1 Scope

This standard establishes photometric methods for determination of niobium when the mass fraction of from 0.002% to 4.00% with a reagent sulfonatophenyl With or sulfochlorinated With and from 0.01% to 8.00% with a reagent PAIRS.

Allowed determination of niobium spectrophotometric method with reagent PAIRS according to the international standard ISO 9441, given in Appendix A.

2 Normative references

The present standard features references to the following standards:

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3773−72 Ammonium chloride. Specifications

GOST 4166−76 Sodium sulfate. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5456−79 of Hydroxylamine hydrochloride. Specifications

GOST 5817−77 tartaric Acid. Specifications

GOST 6552−80 orthophosphoric Acid. Specifications

GOST 7172−76 Potassium preservatory

GOST 7565−81 (ISO 377−2-89) Iron, steel and alloys. Sampling method for determination of chemical composition

GOST 10484−78 Acid fluoride-hydrogen. Specifications

GOST 10652−73 Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B). Specifications

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11125−84 nitric Acid of high purity. Specifications

GOST 14261−77 hydrochloric Acid of high purity. Specifications

GOST 14262−78 sulphuric Acid of high purity. Specifications

GOST 16099−80 Niobium in ingots. Specifications

GOST 16100−79 Niobium in STUBICA. Specifications

GOST 18289−78 Sodium volframovich 2 water. Specifications

GOST 28473−90 Iron, steel, ferroalloys, chromium and manganese metal. General requirements for methods of analysis

3 General requirements

General requirements for methods of analysis GOST 28473.

4 Photometric method for the determination of niobium deposited phenylarsonic acid, sulfochlorinated With or sulfonatophenyl With

4.1 the essence of the method

The method is based on dissolving the sample in suitable acids, deposition of the niobium phenylarsonic acid, the formation of colored complex compounds of niobium with sulfochlorinated With or sulfonatophenyl C and measuring optical density at a wavelength of 650 or 640 nm, respectively.

The effect of zirconium can be eliminated by tying it into a complex of the disodium salt of ethylenediaminetetraacetic acid.

The method is applicable to a mass fraction of niobium from 0.002% to 4.00%.

4.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Muffle furnace for fusing.

Bath water.

The quartz crucibles.

Iron, OS. h not containing niobium.

Hydrochloric acid according to GOST 14261 or GOST 3118 and diluted 1:9.

Sulfuric acid according to GOST 4204 or GOST 14262 and diluted 1:1.

Nitric acid according to GOST 4461 or GOST 11125.

Hydrogen peroxide, a solution of 300 g/DMaccording to GOST 10929.

Zirconium nitrate solution of 3 g/DMin the environment hydrochloric acid: dissolve 0.3 g of zirconium nitrate in 50 cmof hydrochloric acid (1:4). Filtered through a dense filter, diluted to 100 cmwith water and stirred.

Tartaric acid according to GOST 5817, a solution of 150 g/DM.

Fenilalanina acid (CHAsO (OH), solution 40 and 0.5 g/DM.

Hydrofluoric acid according to GOST 10484.

Preservatory potassium (potassium disulfate) KSAbout.

Disodium salt of ethylenediaminetetraacetic acid, a solution of 50 g/DM(NaCNOnN·2HO) (EDTA. Na) according to GOST 10652; store in a plastic container.

Sulfochlorides With [2,7-bis (azo-2-hydroxy-3-sulfo-5-chlorobenzene)-1,8-dioxynaphthalene-3,6-disulfonate acid], the solution of 1 g/DMor sulfonatophenyl With [2,7-bis (azo-2-hydroxy-3-sulfo-5-nitrobenzene)-1,8-dioxynaphthalene-3,6-disulfonate acid], the solution of 1 g/DM.

The solutions are usable for 3 months.

Niobium GOST or GOST 16099 16100.

Standard solutions of niobium.

Solution a: weigh 0.1 g of the niobium, OS. h, with an accuracy of ±0.0001 g, and placed in a platinum Cup or a Cup of glassy carbon. Pour 10 cm ofhydrofluoric acid and 5 cmof nitric acid, add 15 cmof sulphuric acid and heated until thick white fumes of sulfuric acid. Cool the solution, add a few drops of water and again evaporate to dense fumes of sulfuric acid. The cooled solution was added in small portions to 100 cmof a solution of tartaric acid and heated to dissolve the salts. The cooled solution is quantitatively transferred to a volumetric flask with a capacity of 1 DM. Add 400 cmof a solution of tartaric acid, made up to the mark with water and mix.

The solution is usable for 3 months.

1 cmstandard solution contains 0.0001 g of niobium.

Note — allowed the preparation of a standard solution of niobium from niobium perioxide. For this 0,1431 g perioxide niobium, OS. C., the content of the basic substance not less than 99.5% fused in a platinum crucible with 3 g of potassium peacemaking at a temperature of 700−800 °C until a transparent melt, cool it down, then continue as in the preparation of solution A.


Solution B: 10 cmstandard solution And placed in a volumetric flask with a capacity of 100 cm, add 15 cmof a solution of tartaric acid, made up to the mark with water and mix; prepare before use.

1 cmstandard solution B has the 0.00001 g of niobium.

Solution: 10 cmstandard solution B is placed in a volumetric flask with a capacity of 100 cm, add 15 cmof a solution of tartaric acid, made up to the mark with water and mix; prepare before use.

1 cmstandard solution contains 0,000001 g of niobium.

4.3 analysis

4.3.1 the sample the sample, depending on the mass fraction of niobium, weighed in accordance with table 1.


Table 1

In parallel with the definition of spend control experience performing all stages of the analysis and using the same quantities of all reagents and the same cuvette for spectrophotometric measurements, but instead sample the sample used the iron containing niobium.

Place the weighed sample in a beaker with a capacity of 400 cm, a flow of 30−40 cmof hydrochloric acid, cover the beaker watch glass and dissolve the sample when heated. In the slightly chilled solution was added carefully in small portions to 10 cmof hydrogen peroxide and heating was continued until complete dissolution of the sample. Boil the solution for 1−2 min, diluted to approximately 200 cmof hot water and add 5 cmnitrate solution of zirconium.

Heat the solution to boiling, and pour to it of 25 cmin a boiling solution of phenylarsonic acid. Boil for 5 minutes, add a small amount of filter paper pulp, mix well and leave for 10 min and Filtered through a filter of medium density with a small amount of filter paper pulp. Particles of sediment from the walls of the glass and remove glass rod with rubber tip and washed three times glass of warm hydrochloric acid (1:9). The filter cake was washed alternately with hot hydrochloric acid (1:9) and the cold phenylarsonic acid 0.5 g/lto the complete laundering of salts of iron. Finally washed several times with cold solution of phenylarsonic acid 0.5 g/DM. Put the filter with the precipitate in a quartz crucible, dried, bugleweed filter when possible low temperature and incinerated at a temperature of 700−800 °C. Cool, add 3−5 drops of sulfuric acid (1:1), dried to dryness and the residue is calcined for 1−2 minutes at a temperature of 700−800 °C.

To the cooled residue add 2 g peacemaking of potassium, fused in a muffle furnace at a temperature of 700−800 °C until a transparent melt.

To the cooled afloat poured 35 cmof tartaric acid solution and dissolved by heating. The cooled solution is transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

In a volumetric flask with a capacity of 50 cmis placed aliquot part of the solution in accordance with table 1, add 2 cmof EDTA. Na, 24 cmof hydrochloric acid (1:1), 2 cmof a solution of sulfochloride With or sulfonatophenyl With, made up to the mark with water and mix. A flask with an open tube heated in a water bath at a temperature of 40−50 °C for 5 min.

The solution was cooled to room temperature, as long as its level is not fixed at the mark of the flask. The coating solution stable for 5 hours.

Optical density of the solution is measured at a wavelength of 650 nm in the case of use of sulfochloride With or at a wavelength of 640 nm in the case of the use of sulfonatophenyl C. a Solution of comparison is the solution of the reference experiment.

4.3.2 Construction of calibration graphs

Weigh a sample of iron with a mass equal to the mass hanging of samples in accordance with table 1, and perform operations in accordance with 4.3.1 to obtain a solution of water.

4.3.2.1 For steels with a mass fraction of niobium from 0.002% to 0.01% in eight volumetric flasks with a capacity of 50 cmflow aliquote part of the solution obtained in 4.3.2, in accordance with table 1 and in seven of them add a standard solution of niobium in accordance with table 2.


Table 2

The eighth solution of the flask is solution comparisons. Then do as specified in 4.3.1.

4.3.2.2 For steels with a mass fraction of niobium over 0.01% in ten volumetric flasks with a capacity of 50 cmflow aliquote part of the solution obtained in 4.3.2, in accordance with table 1 and 9 add the standard solution of niobium in accordance with table 3.


Table 3

A tenth solution of the flask is solution comparisons. Then do as specified in 4.3.1.

On the found values of optical density of the solutions and their corresponding mass fractions of niobium build the calibration graph.

4.4 Processing of results

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

, (1)

where is the mass of niobium 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,

4.4.2 Standards of operational control of convergence, reproducibility, and accuracy of determining the mass fraction of niobium are given in table 4.


Table 4

Percentage

Standards of operational control of the convergence of regulations and control of reproducibility are calculated at confidence level =0,95. Standards of operational control precision is calculated at the confidence level =0,85.

Algorithms for real-time control of measurement uncertainty and periodicity — according to GOST 28473.

5 Photometric method for the determination of niobium with sulfochlorinated With or sulfonatophenyl With

5.1 the essence of the method

The method is based on formation of colored complex compounds of niobium with sulfochlorinated With or sulfonatophenyl in the medium of hydrochloric acid molar concentration of 1−3 mol/DMand subsequent measurement of optical density at a wavelength of 650 or 640 nm, respectively. For the mass concentration of niobium to 0.1%, the impact of iron eliminate restoration of ascorbic acid or hydroxylamine. The effect of zirconium can be eliminated by tying it into a complex with Trilon B.

5.2 the Instrument, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Bath water.

Hydrofluoric acid according to GOST 10484.

Hydrochloric acid according to GOST 3118 or GOST 14261 and diluted 1:1.

Nitric acid according to GOST 4461 or GOST 11125.

Sulfuric acid according to GOST 4204 or GOST 14262 and diluted 1:1.

Orthophosphoric acid according to GOST 6552.

Tartaric acid according to GOST 5817, solution mass concentration of 150 g/DM.

Ascorbic acid, a solution of mass concentration of 10 g/DMor hydroxylamine hydrochloride according to GOST 5456, solution mass concentration of 100 g/DM.

Potassium preservatory according to GOST 7172.

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

Sulfochlorides With [2,7-bis (azo-2-hydroxy-3-sulfo-5-chlorobenzene)-1,8-dioxynaphthalene-3,6-disulfonate acid], the solution of the mass concentration of 1 g/DMor sulfonatophenyl With [2,7-bis (azo-2-hydroxy-3-sulfo-5-nitrobenzene)-1,8-dioxynaphthalene-3,6-disulfonate acid], the solution of the mass concentration of 1 g/DM; usable for 3 months.

Niobium grades НБ1, НБ2, НБ3 according to GOST 16099; brands NBSH00, NBSH0, NBSH1 according to GOST 16100или niobium perioxide, OS. h

Standard solutions of niobium.

Solution a: 0.1 g of niobium was placed in a platinum Cup and dissolved in 10 cmhydrofluoric acid and 5 cmof nitric acid, add 15 cmof sulphuric acid and twice evaporated to the appearance of dense sulphuric acid fumes or 0,1431 g patinised of niobium alloy in a platinum crucible with 3 g of potassium peacemaking. To the cooled solution or afloat add in small portions 100 cmof solution of tartaric acid, heated to dissolve the salts, and cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM, is added 400 cmof a solution of tartaric acid, made up to the mark with water and mix. The solution is usable for 3 months.

1 cmstandard solution contains 0.0001 g of niobium.

Solution B: 10 cmstandard solution And placed in a volumetric flask with a capacity of 100 cm, add 15 cmof a solution of tartaric acid, made up to the mark with water and mix; prepare before use.

1 cmstandard solution B has the 0.00001 g of niobium.

Solution: 10 cmstandard solution B is placed in a volumetric flask with a capacity of 100 cm, add 15 cmof a solution of tartaric acid, made up to the mark with water and mix; prepare before use.

1 cmstandard solution contains 0,000001 g of niobium.

Solution G: 0.1 g of niobium was placed in a platinum Cup and dissolved in 20 cmhydrofluoric acid and 5 cmof nitric acid, add 30 cmof sulphuric acid and evaporated until the appearance of dense white fumes of sulfuric acid. The solution was transferred to a volumetric flask with a capacity of 1 DM, washing the walls of the Cup with a solution of sulfuric acid (1:1), add 30 cmof water, cool, add sulfuric acid solution (1:1) to the mark and mix. The solution is usable for 3 months.

1 cm* of the standard solution G contains 0.0001 g of niobium.
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* The text of the document matches the original. — Note the manufacturer’s database.

Steel or synthetic blend for holding the reference experiment containing no niobium, different from the tested steel in mass fractions: iron — not more than 20%; Nickel, cobalt, manganese — 10%; chromium, titanium, vanadium — 5% copper; 1% in the presence of ascorbic acid, and 5% in other cases; molybdenum — 0.5 percent of tungsten — 2% zirconium and 0.2% for the mass concentration of niobium than 0.1%.

5.3 analysis

5.3.1 Sample mass depending on the mass fraction of niobium in accordance with table 5 were placed in a glass with a capacity of 150−250 cmor conical flask with a capacity of 100 cmand dissolved by heating at 15−30 cmof hydrochloric acid, then add 2−3 cmof nitric acid and 1 cmof phosphoric acid and continue the dissolution.

To the solution was added to 16 cmof sulfuric acid solution (1:1) and evaporated until the appearance of fumes, then cooled, washed the walls of the Cup 2−3 cmof water and repeat the evaporation until the appearance of sulphuric acid fumes. After cooling, to the solution was added 1−2 cmwater and 15 cmof a solution of tartaric acid and heated to dissolve the salts. Cool, transferred to volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Table 5

The solution is filtered through a dry filter, the average density in the dry beaker, rejecting the first portions of the filtrate.

For the mass concentration of niobium greater than 0.10% and the absence of zirconium in a volumetric flask with a capacity of 50 cmflow aliquot part of the solution in accordance with table 3, 2 cmof a solution of sulfochloride With or sulfonatophenyl With 24 cmof hydrochloric acid (1:1), made up to the mark with water, mixed and heated for 5 min in a water bath at a temperature of 40−50 °C. the Solution was then cooled on the air as long as its level is not fixed at the mark of the flask. Optical density of the solution is measured at a wavelength of 650 nm in the case of use of sulfochloride With or at a wavelength of 640 nm in the case of the use of sulfonatophenyl C. a Solution of comparison is the solution of the control experiment through all stages of the analysis. The contents of niobium find the calibration schedule.

5.3.2 for the mass concentration of niobium to 0.1% and the absence of zirconium to aliquote part of the solution pour 4 cmof solution of hydrochloric acid (1:1) and 5 cmof ascorbic acid solution. After 10 min add 2cmof a solution of sulfochloride With or sulfonatophenyl With 20 cmsolution of hydrochloric acid (1:1), made up to the mark with water and then do as described in 5.3.1.

Instead of ascorbic acid is allowed to apply a solution of hydroxylamine hydrochloride. For this to aliquote part of the solution, poured 5cmof water and 2 cmof a solution of hydroxylamine hydrochloride, and heated in a water bath to a temperature of 60−70 °C, incubated the solution at this temperature until its discoloration. The solution is cooled in air to room temperature, poured 2cmof a solution of sulfochloride With or sulfonatophenyl With 24 cmof hydrochloric acid (1:1), made up to the mark with water and then do as described in 5.3.1.

5.3.3 in the presence of zircon analysis carried out in accordance with 5.3.1 to obtain a filtrate. Select aliquot part of the solution in accordance with table 3 in volumetric flask with a capacity of 50 cm. Restore hardware 5.3.2, if the mass fraction of niobium, up to 0.1 percent. Add 2cmof a solution of Trilon B, 20, or 24 cmof hydrochloric acid (1:1) depending on the reducing agent, 2 cmof a solution of sulfochloride With or sulfonatophenyl With, made up to the mark with water and then do as described in 5.3.1.

5.3.4 Construction of calibration graphs

5.3.4.1 For steels with a mass fraction of molybdenum up to 0.5% tungsten and 2% for the mass concentration of niobium to 0.1% and for steels containing more than 0.1% niobium, the weight of steel or synthetic blend for the reference experiment is treated in accordance with 5.3.1 to obtain a filtrate. In ten volumetric flasks with a capacity of 50 cmflow aliquote part of the solution in accordance with table 5 and in nine of them 1.0 and 2.0 cmstandard solution Into and 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 and 4.0 cmstandard solution B. Solution a tenth of the flask is solution comparisons. Then do as specified in 5.3.1−5.3.3. On the found values of optical density of the solutions and their corresponding mass fractions of niobium build the calibration graph.

5.3.4.2 For steels with a mass fraction of molybdenum more than 0.5% and tungsten over 2% for the mass concentration of niobium to 0.1% and for steels containing more than 0.1% of niobium, of six tumblers with a capacity of 150−250 cmplace of sample mass of 0.4 g steel or a synthetic mixture of the reference experiment. In five glasses poured 0,4; 1,0; 2,0; 3,0 and 4,0 cmstandard solution G. the Suspension of the sixth glass is used for solution preparation comparison. The sample is dissolved in 30 cmof hydrochloric acid, then add 2−3 cmof nitric acid and 1 cmof phosphoric acid and continue the dissolution. To solutions add a quantity of solution of sulfuric acid (1:1) to the amount of standard solution it was 16 cm. Then do as specified in 5.3.2 or 5.3.3.

On the found values of optical density of the solutions and their corresponding mass fractions of niobium build the calibration graph.

5.4 processing of the results

Processing of the results — for 4.4.

6 Photometric method for the determination of niobium with a reagent PAIRS

6.1 the essence of the method

The method is based on formation of colored complex compounds of niobium with PAR reagent and tartrate ions in the environment of hydrochloric acid molar concentration of 0.75 mol/DM. The influence of concomitant elements can be eliminated by masking them with Trilon B. for the mass concentration of niobium to 0.1% of its pre-isolated by coprecipitation with tannat methyl violet or crystal violet in the presence of tungsten.

6.2 Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Muffle furnace for fusing.

Hydrochloric acid according to GOST 3118 or GOST 14261 and diluted 1:25, 1:5, 1:2 and 1:1.

Nitric acid according to GOST 4461 or GOST 11125.

A mixture of hydrochloric and nitric acids 1:3.

Sulfuric acid according to GOST 4204 or GOST 14262.

Sodium sulfate according to GOST 4166.

Ammonium vinocity, solution mass concentration of 80 g/DM.

Sodium volframovich 2-water according to GOST 18289, solution mass concentration of 45 g/DM; usable for 2 months.

A solution of sulphate of sodium and ammonium Vinokurova: 2.6 g sodium sulfate was placed in a quartz beaker, pour 2−3 cmof sulphuric acid and melted. Cool going to add 50 cmof the solution Vinokurova ammonium and boil until a clear solution. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark.

Ammonium chloride according to GOST 3773.

Ascorbic acid.

Tannin, solution of the mass concentration of 10 g/DM; cook before eating.

Methyl violet or crystal violet, solution mass concentration 10 g/DM.

PAR [4-(2-pyridyl-azo)-resorcinol], solution mass concentration of 0.2 g/DM, cook before consumption.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652, solution mass concentration of 18.6 g/DM.

Niobium grades НБ1, НБ2, НБ3 according to GOST 16099; brands NBSH00, NBSH0, NBSH1 according to GOST 16100.

Standard solutions of niobium.

Solution a: 0.1 g of niobium was placed in a quartz beaker, add 2.5 g of sodium sulfate, 2−3 cmof sulphuric acid and fused in a muffle furnace at 700−800 °C until a transparent melt, and removing sulphuric acid fumes. The melt is cooled, dissolved by heating in 50 cmsolution Vinokurova ammonium, transferred to a volumetric flask with a capacity of 1 DM, pour 450 cmVinokurova solution of ammonia, made up to the mark with water and mix; useable within 3 months.

1 cmstandard solution contains 0.0001 g of niobium.

Solution B: to 20 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; prepare before use.

1 cmstandard solution B contains 0,00002 g of niobium.

Steel or synthetic blend for the reference experiment containing no niobium, different from the tested steel on mass proportions: of copper — not more than 0.5%, chromium 5%, cobalt — 10%.

6.3 analysis

6.3.1 for the mass concentration of niobium than 0.1% suspension 0.1 g was placed in a quartz glass with a capacity of 100 cmand dissolved in 5−20 cmof hydrochloric acid, 20−30 minutes add 1−3 cmof nitric acid and continue the dissolution. The solution was evaporated to dryness. The residue in the beaker melted at 700−800 °C With 2.6 g of sodium sulfate and 2−3 cmof sulfuric acid. Cool going to add 50 cmof a solution of ammonium Vinokurova and moderately heated to dissolve the salts. After dissolving the salts cool, transferred to volumetric flasks with a capacity of 100 cm, made up to the mark and mix. Aliquot part of the solution in accordance with table 6 is placed in a volumetric flask with a capacity of 50 cm, a solution of sulphate of sodium and ammonium Vinokurova in accordance with table 6.

Table 6

Pour 20 cmof a hydrochloric acid solution (1:5), 1 cmof solution Trilon B, 5 cmsolution PAIRS, made up to the mark with water and mix. After 60 min, measure the optical density of the solution at a wavelength of 536 nm. Solution comparison is the solution of the reference experiment. Mass fraction of niobium find the calibration schedule.

6.3.2 for the mass concentration of niobium to 0.1% of the weighed sample mass of 1 g was placed in a beaker with a capacity of 400−500 cm. If no steel, tungsten or its mass fraction to 5.0% hanging add 2cmof a solution of sodium volframovich. The sample is dissolved in 40 cmof a mixture of hydrochloric and nitric acids (1:3). The solution is evaporated to a volume of 5 cm, 30 cm, pour thehydrochloric acid solution (1:2) and dissolved salts when heated. The solution is diluted with water to 180−190 cm, add 0.2 g of ascorbic acid, 2 g of ammonium chloride and heated to boiling.

Add 30 cmof a solution of methyl violet or crystal violet, then gradually with stirring, poured 20 cmof a solution of tannin, boiled for 2−3 hours, maintaining constant volume. Add a little paper pulp, 50 cmhydrochloric acid solution (1:1) and left overnight. After 12 h the precipitate was filtered off on a double thick filter and washed 5−6 times with cold hydrochloric acid solution (1:25). The residue was placed in a quartz glass, incinerated, and calcined at 700−800 °C and fused with 2.6 g of sodium sulfate and 2−3 cmof sulfuric acid. Then do as indicated in 6.3.1.

6.3.3 Construction of calibration curve

The weight of steel or synthetic blend for the reference experiment is treated in accordance with 6.3.1 or 6.3.2 to obtain a solution in a volumetric flask with a capacity of 100 cm. Eleven volumetric flasks with a capacity of 50 cmflow aliquote part of the solution in accordance with table 6 and in ten of them 0,55; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0; 4,5; 5,0 cmstandard solution B. Solution eleventh the bulb is solution comparisons.

Then do as indicated in 6.3.1. On the found values of optical density of the solutions and their corresponding mass fractions of niobium build the calibration graph.

6.4 Processing of results

Processing of the results — for 4.4.

Annex a (mandatory). Steel. Determination of niobium. A spectrophotometric method with a reagent PAIRS (ISO 9441−88)

APPENDIX A
(required)

A. 1 Scope

This standard specifies the spectrophotometric method for the determination of niobium with a reagent PAIRS in all types of steels with mass fraction of from 0.005% to 1.3%.

A. 2 the essence of the method

The method is based on dissolving the sample the sample in hydrochloric acid followed by oxidation with hydrogen peroxide, deposition of niobium and tantalum phenylarsonic acid using Zirconia as the carrier (reservoir), the formation of a complex of niobium with 4-(2-pyridylazo)-resorcinol (PAR) in the environment Vinokurova sodium with a pH of 6.3, established with a solution of sodium acetate.

Spectrophotometric measurement of the colored connections are made at a wavelength of 550 nm.

A. 3 Reagents

During the analysis, unless otherwise specified, use reagents of the established analytical grade and only distilled water or water of equivalent purity.

A. 3.1 Iron, OS. h not containing niobium.

A. 3.2 acidic potassium Sulfate (KNO).

A. 3.3 hydrochloric Acid, 1,19 g/cm.

A. 3.4 hydrochloric Acid, diluted 1:9.

A. 3.5 sulfuric Acid, diluted 1:1.

A. 3.6 sulfuric Acid, diluted 1:4.

A. 3.7 Hydrogen peroxide, 300 g/DM.

A. 3.8 Sodium hydroxide, solution 120 g/DM; store in a polyethylene vessel.

A. 3.9 Zirconium nitrate, solution in hydrochloric acid of 3 g/DM.

Dissolve 0.3 g of zirconium nitrate in 50 cmof hydrochloric acid (1:4), filtered through a dense filter paper and diluted to 100 cmwith water and stirred.

A. 3.10 Sodium acetate buffer solution with pH value of 6.3: dissolve 350 g trehletnego of sodium acetate in 700 cmof water, add 5.5 cmof glacial acetic acid, 1.05 g/cm, is diluted to 1000 cmand mixed. Bring the value up to pH 6.3 by the addition of small amounts of acetic acid or sodium hydroxide. For measuring pH using pH meter.

A. 3.11 tartaric Acid, a solution of 100 g/DM.

A. 3.12 fenilalanina Acid [CHAsO (OH)], a solution of 40 g/DM.

A. 3.13 fenilalanina Acid, 0.5 g/DM.

A. 3.14 the disodium Salt of ethylenediaminetetraacetic acid (EDTA. Na), (NOnNPA·2HO), a solution of 15 g/l: dissolve 15 g dvukhfaznoi EDTA. Nain water, diluted to 1000 cmand mix; store in a polyethylene vessel.

A. 3.15 4-(2-pyridylazo)-resorcinol (PAR) (NNO), a mono — or disodium salt, solution of 0.6 g/DM.

A. 3.16 Niobium, standard solution 0,200 g/l: weigh 0,1431 g of niobium oxide with an accuracy of ±0.0001 g and placed in a platinum crucible. Alloy with 3.5 g of potassium hydrosulfate. Cooled and dissolved in 40 cmof a solution of tartaric acid, add 160 cmtartaric acid. Transfer the solution into a measuring flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmstandard solution containing 0.200 mg of niobium.

A. 4 Instrument

Ordinary laboratory equipment and a spectrophotometer.

Volumetric glassware should be class A.

A. 5 Sampling

Sampling performed in accordance with GOST 7565.

A. 6 analysis

A. 6.1 Mounting of samples

Weigh 1.0 g test sample (mass ) with an accuracy of ±1 mg.

A. 6.2 Control experience

In parallel with the definition of the same procedure perform the blank experiment using the same quantities of all reagents and the same cell, as in the definition, but instead of mounting the sample take iron.

A. 6.3 Definition

A. 6.3.1 dissolution of the sample

Put the portion into a low glass with a capacity of 400 cm, was added 40 cmof hydrochloric acid (A. 3.3), covered with a glass watch glass and heated until the termination of the solvent. The solution is cooled slightly and carefully add 5 cmof hydrogen peroxide. Boil the solution 1 min, dilute to approximately 200 cmof warm water and add 5 cmnitrate solution of zirconium.

A. 6.3.2 Department of niobium

Heat the solution prepared in A. 6.3.1, to a boil and add 25 cmof a boiling solution of phenylarsonic acid (A. 3.12). Boil for 5 min, add a small amount filtrowanie mass, mix well and leave for 10 min.

Filtered through a layer filtrowanie mass scour residue from the walls of the beaker with a glass rod with a rubber tip. Washed the filter with the residue alternately with hot hydrochloric acid (A. 3.4) and a chilled solution of phenylarsonic acid (A. 3.13) to complete the laundering from iron salts. Finally washed several times with cold solution of phenylarsonic acid (A. 3.13). Transfer filter with precipitate in a quartz crucible. Dried, then heated until complete charring at low temperature. Incinerated and finally calcined at 800 °C for at least 15 min. Cooled in a desiccator, add a few drops of sulfuric acid (A. 3.5) and carefully evaporated to dryness. Calcined to remove the sulfur trioxide.

A. 6.3.3 Preparation of test solution

Add 2 g of potassium hydrosulfate to the obtained residue, and gently fused until a clear melt. Cool, dissolve the melt in 50 cmwarm tartaric acid and transfer the solution into a glass with a capacity of 400 cm. Add 50 cmof water and stirred.

Add 25 cmof sodium hydroxide solution and cooled. The pH of the solution was adjusted to 6.0 approximately (monitoring pH meter) by adding sulfuric acid (A. 3.6) or sodium hydroxide depending on the need. The solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 250 cm, is diluted to the mark with water and mix.

A. 6.3.4 the development of the painting

Select aliquot part of the test solution prepared according to A. 6.3.3, the volume aliquote part depends on the expected content of niobium in the sample, as indicated in table A. 1.

Table A. 1

Aliquote put part in a measuring flask with volume capacity of 100 cm. With a pipette add 10 cmof EDTA. Na, 10 cmof solution PAIRS and 10 cmbuffer solution of sodium acetate, mix well after adding each solution. Leave the solution for 15 minutes at a temperature of approximately 20 °C, then diluted to the mark with water and mix. The color of the solution changes another 30 min.

A. 6.3.5 Spectrophotometric measurement

Perform a spectrophotometric measurement at a wavelength of 550 nm after setting the spectrophotometer to zero absorbance against water. Use a 4 cm cuvette for the content of niobium to 0.06% and a 1 cm cuvette — more than 0,06%.

A. 6.4 Construction of calibration curve

A. 6.4.1 Preparation of the calibration solutions

Taken at (1,0±0,05) g of iron in two cups with a capacity of 400 cm. Add the volume of standard solution niobium, as shown in table A. 2.


Table A. 2

Further still in accordance with A. 6.3.2-A. 6.3.4, but in all cases take aliquot part 25 cm(A. 6.3.4).

A. 6.4.2 Spectrophotometric measurement

Carry out the spectrophotometric measurements of each solution at a wavelength of 550 nm after setting the spectrophotometer to zero values of absorption relative to water. Use cuvettes with the length of the optical layer, as indicated in table A. 2. Get the value of absorbance by subtracting the values of absorbance of the zero member of the graphics from the absorbance of each calibration solution in the series.

A. 6.4.3 Construction of calibration curve

On the found values of optical density of the solutions and their corresponding values of the content of niobium (ug/cm) build a calibration curve.

A. 7 Processing of results

A. 7.1 Calculation method

From the calibration curve, built according to A. 6.4.3, find the concentration of niobium, which corresponds to the absorption of the colored test solution, measured according to A. 6.3.5.

The contents of NB, %, is given by

(A. 1)

where is the concentration of niobium in test solution, µg/cm;

concentration of niobium in solution in the reference experiment, µ g/cm;

 — volume of test solution, cm;

 — volume aliquote part, cm;

 — painted volume of the test solution, cm;

 — the weight of the portion of the sample,