GOST 11930.7-79

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  ГОСТ 11930.7-79

GOST 11930.7−79 Materials surfacing. Methods for determination of iron (with Amendments No. 1, 2)

GOST 11930.7−79

Group B09

INTERSTATE STANDARD

MATERIALS SURFACING

Methods of iron determination

Hard-facing materials. Methods of iron determination

ISS 25.160.20
AXTU 1709

Date of introduction 1980−07−01

The decision of the State Committee USSR on standards on March 21, 1979 N 982 date of introduction is established 01.07.80

Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

EDITION (August 2011) with Amendments No. 1, 2 approved in December 1984, December 1989 (IUS 3−85, 3−90)


This standard establishes photocolorimetric methods for determination of iron (at mass fraction of iron from 0.2 to 7%) in the surfacing materials based on cobalt and Nickel.

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 11930.0−79.

2. PHOTOCOLORIMETRIC METHOD OF IRON DETERMINATION WITH ORTOFENANTROLINOM

2.1. The essence of the method

The method is based on formation of colored complex compounds of bivalent iron with ortofenantrolinom in the presence of all components of the alloy.

2.2. Apparatus, reagents and solutions

Types photoelectrocolorimeter FEK-56, FEK-56M or any other type.

Nitric acid GOST 4461−77.

Hydroxylamine hydrochloric acid according to GOST 5456−79, a solution with a mass fraction of 10%.

Sulfuric acid GOST 4204−77, diluted 1:4.

Ammonium acetate according to GOST 3117−78, a solution with a mass fraction of 30%.

Paper display «of the Congo».

Orthophenanthroline, a solution with a mass fraction of 1% is prepared by dissolving the reagent in ethanol, diluted 1:1.

Ethyl alcohol GOST 18300−87.

Standard solutions of iron.

Solution a is prepared as follows: 0.1 g of iron was dissolved in 50 cmof sulphuric acid, diluted 1:4, poured 1 cmof nitric acid and heated to remove oxides of nitrogen. After cooling, the solution is transferred into a measuring flask with volume capacity of 1000 cm, is diluted to the mark with water and mix. 1 cmof the solution contains 0.0001 g of iron.

Solution B is prepared by diluting with water solution And 10 times. 1 cmof solution B contains 0,00001 g of iron.

(Changed edition, Rev. N 2).

2.3. Analysis

2.3.1. Iron determined in the filtrate after separation of the silicon GOST 11930.3−79.

Of volumetric flasks with a capacity of 200 cmtaken from 5 to 15 cmof the analyzed solution in a volumetric flask with a capacity of 100 cm. Pour 5 cmof a solution of hydroxylamine and neutralizing with a solution of acetate of ammonium to transition indicator paper «Congo» in red. Add 5 cmof orthophenanthroline solution, dilute to the mark with water and mix. The optical density of colored solution is measured on a photoelectrocolorimeter (490 nm) after 10 min in the cuvette with the thickness of the absorbing layer 50 or 10 mm. as a solution comparison solution is used in the reference experiment on the content of iron in the reagents. The optical density of test solution find the content of iron in the calibration schedule.

2.3.2. Construction of calibration curve

2.3.2.1. In a volumetric flask with a capacity of 100 cmplaced 2, 4, 6, 8 and 10 cmof standard iron solution B, add 10 cmof a solution with a mass fraction of 10% hydrochloric acid hydroxylamine and neutralize «Congo» solution of acetate of ammonium. Then the analysis is carried out as specified in clause 2.3.1. The optical density of colored solution is measured on a photoelectrocolorimeter (490 nm) in a cuvette with a thickness of the absorbing layer is 50 mm.

2.3.2.2. In a volumetric flask with a capacity of 100 cmplaced 1, 2, 3, 4, 5 cmstandard solution And further analysis are as described above. The optical density of solutions measured on photoelectrocolorimeter in a ditch with thickness of the absorbing layer 10 mm (490 nm).

(Changed edition, Rev. N 2).

2.4. Processing of the results

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

,

where  — aliquota part of the analyzed solution, cm;

 — the mass of iron was found in the calibration schedule g;

 — the weight of the portion,

Sec. 2. (Changed edition, Rev. N 1).

3. PHOTOCOLORIMETRIC METHOD FOR DETERMINATION OF IRON WITH SULFOSALICYLIC ACID

3.1. The essence of the method

The method is based on formation of colored complex compounds of iron with sulfosalicylic acid. Iron is separated by precipitation with ammonia.

3.2. Apparatus, reagents and solutions

Photoelectrocolorimetry types FEK-56, FEK-56M or any other type.

Ammonia water according to GOST 3760−79 and diluted 5:95.

Ammonium neccersarily according to GOST 20478−75.

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

Sulfosalicylic acid according to GOST 4478−78, a solution with a mass fraction of 20%.

Paper display «of the Congo».

Standard iron solution — according to claim 2.2.

(Changed edition, Rev. N 1, 2).

3.3. Analysis

3.3.1. Iron determined in the filtrate after separation of the silicon GOST 11930.3−79.

Of volumetric flasks with a capacity of 200 cmis taken 50 cmof the analyzed solution in a beaker with a capacity of 200 cm, dilute with water to 100 cm, are added 1 g of ammonium naternicola and heated. The solution was then neutralized with ammonia on indicator paper «Congo», add 10 cmof ammonia in excess, the precipitate is coagulated, filtered and washed with ammonia solution, diluted 5:95, heated to 60−80 °C. the Precipitate of iron hydroxide is dissolved in hot hydrochloric acid at 60−80 °C, diluted 1:1. The solution collected in the beaker in which to conduct the deposition. The filter was washed 8−10 times with hot water and discarded. The solution was transferred to a volumetric flask with a capacity of 100 cm, is diluted with water and stirred. Select aliquot part of 5−50 cm(depending on iron content) in a volumetric flask with a capacity of 100 cm, add 10 cmsulfosalicylic acid, ammonia until yellow color and 10 cmin excess, dilute to the mark with water and mix. The optical density of colored solutions are measured on a photoelectrocolorimeter (434 nm) in a cuvette with a thickness of the absorbing layer is 50 mm. as a solution comparison solution is used in the reference experiment on the content of iron in the reagents. The optical density of test solution find the content of iron in the calibration schedule.

3.3.2. Construction of calibration curve

In a volumetric flask with a capacity of 100 cmwas added sequentially 4, 8… and 20 cmof standard iron solution B and further analysis are as indicated in claim 3.3.1.

3.3.1, 3.3.2. (Changed edition, Rev. N 1).

3.4. Processing of the results

3.4.1. 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 mass of sample, g;

 — aliquota part of the analyzed solution, cm.

3.4, 3.4.1. (Added, Rev. N 1).

3.4.2. The difference between the largest and smallest results of the three parallel measurements, and the two results of the analysis at a confidence level of 0.95, should not exceed the values of permissible differences given in the table.

(Changed edition, Rev. N 2).