GOST 29095-91

• gost-29095-91.pdf (288.56 KiB)
  ГОСТ 29095-91

GOST 29095−91 Alloys and powders heat-resistant, corrosion-resistant, precision Nickel-based. Methods of iron determination

GOST 29095−91

Group B39

INTERSTATE STANDARD

ALLOYS AND POWDERS HEAT-RESISTANT, CORROSION-RESISTANT, PRECISION NICKEL-BASED

Methods of iron determination

Nickel-based precision, corrosion-resistant, heat-resistant alloys and powders. Methods of iron determination

MKC 77.120.40
AXTU 0809

Date of introduction 1993−01−01

INFORMATION DATA

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

2. APPROVED AND promulgated by the Decree of Committee of standardization and Metrology of the USSR from 04.09.91 N 1419

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. REPRINTING. July 2004


This standard specifies the photometric (mass fraction of iron with from 0.05% to 3%) and atomic absorption (at a mass fraction of iron from 0.05% to 20%) methods for determination of iron.

1. GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 28473.

2. PHOTOMETRIC METHOD

2.1. The essence of the method

The method is based on formation of colored complex compounds of iron (II) with 1,10-phenantroline or 2,2-dipyridylium at pH = 3−3,5. The mass of iron is 40−150 µg in 100 cmof solution.

For reduction of iron using hydroxylamine hydrochloride.

Iron from chromium, copper, Nickel, cobalt is separated by precipitation with ammonia after oxidation of chromium and cobalt neccersarily ammonium. Tungsten is separated in the form of tungsten acid.

2.2. Equipment, reagents

Spectrophotometer or photoelectrocolorimeter.

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

Nitric acid according to GOST 11125.

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

The mixture of acids (I): 8 parts of hydrochloric acid mixed with 1 part of nitric acid.

The mixture of acids (II): 3 parts hydrochloric acid mixed with 1 part of nitric acid.

Ammonium-aluminum sulfate (alum alimohammadian) according to GOST 4238, solution 50 g/l: 50 grams of alum dissolved in 150−200 cmof water with the addition of 25 cmof sulphuric acid (1:1) and top up with water to 1 DM.

Silver nitrate according to GOST 1277, a solution of 2.5 g/DM.

Ammonium neccersarily according to GOST 20478, a solution of 250 g/DM.

Ammonia water according to GOST 3760 and diluted 1:20.

Sodium chloride according to GOST 4233, a solution of 50 g/DM.

Universal indicator paper.

Hydroxylamine hydrochloride according to GOST 5456, solution 100 g/lfreshly prepared.

Sodium acetate 3-water according to GOST 199, a solution of 500 g/DM.

Tartaric acid according to GOST 5817, solution 100 g/DM.

1,10-fenantrolin, a solution of 5 g/lin hydrochloric acid solution with molar concentration of the equivalent 0,1 mol/DM.

2,2-dipyridyl (alpha, alpha-dipyridyl), a solution of 5 g/DM.

Carbonyl iron is particularly clean.

Standard solutions of iron.

Solution a: 1 g of iron carbonyl was placed in a beaker and dissolve in low heat in 30 cmof hydrochloric acid. After complete dissolution of the sample are added dropwise nitric acid until the termination of foaming and the excess 2−3 drops. The solution is heated to remove oxides of nitrogen, cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of iron.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 1 DM, is added to 50 cmof hydrochloric acid (1:1), made up to the mark with water and mix.

1 cmof solution B contains 0,00001 g of iron.

2.3. Analysis

2.3.1. The weight of the portion of the sample depending on mass fraction of iron is given in table.1.

Table 1

2.3.2. The determination of iron in alloys not containing tungsten

A portion of the alloy (tab.1) is placed in a beaker and dissolved with moderate heating in 20−40 cmof the mixture of acids (I or II). The solution was cooled, poured 15−20 cmof sulphuric acid (1:1) and evaporated to sulphuric acid fumes. The contents of the Cup cool, wash the side of the Cup with water and again evaporated to fumes of sulfuric acid. Salt is dissolved in 50−60 cmof water when heated, and when the mass fraction of iron of 0.2% add 3 cmalimohammadian alum, the solution is diluted with hot water up to 200−250 cm.

To the sample solution containing chrome, add 10 cmof a solution of silver nitrate, and heated nearly to boiling. To the hot solution was carefully poured 15−45 cmnaternicola solution of ammonia, heated to complete oxidation of chromium and manganese, boil for 3−5 min until fracture of the excess naternicola ammonium. To the boiling solution add 5−10 cmof sodium chloride solution and boil for the full recovery of manganese acid.

The solution is poured a solution of ammonia until the precipitation of a hydroxide and an excess of 5−10 cm. Solution and the precipitate is gently brought to boiling and allowed to stand in a warm place for 5−10 min to coagulate the precipitate.

The precipitate was filtered off on a medium density filter, the beaker and the residue on the filter is washed five to eight times with a hot solution of ammonia (1:20). The filtrate is discarded. The filter cake is dissolved in 30−50 cmof hot hydrochloric acid (1:1) in a beaker, which was carried out the precipitation of the hydroxide. The filter is washed thoroughly with hot water and discarded.

If there is a complete separation of chromium and Nickel of iron to solution was poured 20−25 cmof sulphuric acid (1:1), evaporated to fumes of sulfuric acid and conduct re-oxidation of chromium, the precipitation and dissolution of the hydroxides as described above.

The resulting solution is evaporated to 50−60 cm, cooled, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Aliquot part of the solution (table.1) were placed in a glass, pour 3 cmof a solution of tartaric acid, 10 cmof a solution of hydroxylamine hydrochloride. The solution was stirred, neutralized with a solution of sodium acetate to pH = 3−3,5 (for universal indicator paper) and add 2 cmof it in excess. Then add 10 cmof a solution of 1,10-phenanthroline or 10 cmof a solution of 2,2-dipyridyl, transferred to a volumetric flask with a capacity of 100 cm, is diluted to the mark with water and mix. Optical density of the solution is measured after 1 hour at a wavelength of 510−520 nm relative to solution comparison. As a solution comparison, using aliquot part of the analyzed solution, which is added all the reagents, except for the 1,10-phenanthroline or 2,2-dipyridyl.

Simultaneously with the sample hold control experience for contamination of reagents.

The mass of iron found by a calibration graph with the reference experiment.

2.3.3. The determination of iron in alloys containing tungsten

After the dissolution of the attachment as specified in claim 2.3.2, the solution is heated to the precipitation of tungsten acid. Add 5−10 cmof nitric acid and again heat the solution until the precipitate of tungsten acid yellow.

The solution was evaporated to wet salts, poured 10 cmof hydrochloric acid, heated to dissolve the salts, pour 100−120 cmof hot water and leave on the warm stove for hours.

The precipitate tungsten acid is filtered off on a double thick filter containing filtrowanie mass, and carefully washed eight to ten times with hot hydrochloric acid (1:20). Filter the precipitate tungsten acid drop. The filtrate and the washings saved.

To the obtained solution poured 15−20 cmof sulphuric acid (1:1) and evaporated to sulphuric acid fumes. The glass is cooled, washed wall with water and again evaporated to fumes of sulfuric acid. Salt is dissolved in 50−60 cmof water when heated, and the mass fraction of iron of 0.2% add 3 cmalimohammadian alum. The solution is diluted with hot water up to 200−250 cmand are further taken as specified in claim 2.3.2.

2.3.4. Construction of calibration curve

Into glasses placed 3; 5; 10; 15; 20 cmstandard solution of iron with a concentration 0,00001 g/cm, add 3 cmof tartaric acid and then act as described in claim 2.3.2. As a solution comparison, using a solution containing all reagents, except standard solution of iron.

2.4. Processing of the results

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

,

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

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

3. ATOMIC ABSORPTION METHOD

3.1. The essence of the method

The method is based on measurement at a wavelength of 248.3 nm the degree of absorption of resonance radiation by free atoms of iron, formed when spraying the test solution in a flame air-acetylene.

3.2. Equipment, reagents

Atomic absorption spectrophotometer fiery.

Lamp with hollow cathode for the determination of iron.

The cylinder with acetylene.

The compressor supplying compressed air, or compressed air.

Hydrochloric acid according to GOST 3118.

Nitric acid according to GOST 4461.

Sulfuric acid according to GOST 4204, and diluted 1:4.

Carbonyl iron, extra clean.

Standard solutions of iron.

Solution a: 1 g of carbonyl iron, weighted with accuracy of 0.0002 g, is dissolved in 20−30 cmof hydrochloric acid, and carefully added dropwise 5−7 cmof nitric acid. The solution was cooled, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

1 cmstandard solution contains 2 mg of iron.

Solution B: 10 cmstandard solution And placed in 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 0.2 mg of iron.

3.3. Analysis

3.3.1. The weight of the portion of the alloy and dilution of solutions depending on the mass fraction of iron is given in table.2.

Table 2

Allowed another dilution of solutions, providing normalized in the standard precision.

The sample of alloy is placed in a beaker or flask with a capacity of 150−300 cmand dissolved under moderate heating in 15−30 cmsalt and 5−10 cmof nitric acid. The solution is carefully evaporated to wet salts, add 5 cmof hydrochloric acid and dissolved salts.

Allowed other methods of dissolution, providing a complete decomposition of the sample and does not require changes in the further analyses.

In the presence in the sample of titanium and niobium in the solution after dissolution of the sample is cooled, add sulfuric acid (1:4) at the rate of 10 cmfor every 100 cmof the final volume and evaporated to sulphuric acid fumes. Pour 50−60 cmof water and dissolved salts when heated.

The resulting solution was transferred to volumetric flask (see table 2), made up to the mark with water and mix. Part of the solution was filtered through two dry filter, discarding first portion of filtrate.

Simultaneously with the sample hold control experience for contamination of reagents.

3.3.2. Preparation of solutions for calibration curve

3.3.2.1. For alloys with a mass fraction of iron to 5.0%

Five volumetric flasks with a capacity of 100 cmhas consistently poured 1,0; 2,5; 5,0; 7,5; 10 cmstandard solution B. the Sixth flask is used for the reference experiment.

3.3.2.2. For alloys with a mass fraction of iron in excess of 5.0%

In seven volumetric flasks with a capacity of 100 cmhas consistently poured 4,0; 5,0; 6,0; 7,0; 8,0; 9,0; 10,0 cmstandard solution B. the Eighth flask was used for the control experience.

3.3.2.3. In each flask, prepared in accordance with the PP.3.3.2.1 and 3.3.2.2, pour 5 cmof hydrochloric acid or 10 cmof sulphuric acid (1:4), made up to the mark with water and mix.

3.3.3. Preparation of the device and the measurement of atomic absorption

The device is prepared to work in accordance with the enclosed instructions. Set the spectrophotometer at a resonance line of 248.3 nm. After turning on gas supply and ignition of the burner spray water into the flame and set the instrument zero. Is sprayed into the flame of the solution in the reference experiment, then the solutions for calibration curve and test solutions in order of increasing iron concentration. Conduct measurement to obtain stable readings for each solution. Prior to introduction into the flame each of the analyzed solution is sprayed into the flame the water and check the zero of the instrument. From the average value of absorbance of each of the analyzed solutions, the average value is subtracted absorption in the reference experiment and the mass concentration of iron found by the calibration schedule.

3.3.4. On the found values of absorbance of the calibration solutions, taking into account the values of absorption in the reference experiment and the corresponding concentrations of iron to build the calibration graph.

3.4. Processing of the results

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

,

where  — the amount of iron was found in the calibration schedule, µg/cm;

 — the volume of the analyzed solution, cm;

 — the mass charge, g (subject to dilution).

3.4.2. Norms of accuracy and norms of accuracy control of determination of mass fraction of iron is given in table.3.

Table 3