GOST 9853.19-96

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  ГОСТ 9853.19-96

GOST 9853.19−96 Titan spongy. Method for the determination of chromium

GOST 9853.19−96

Group B59

INTERSTATE STANDARD

TITANIUM SPONGE

Method for the determination of chromium

Sponge titanium. Method for determination of chrome

ISS 77.120*
AXTU 1709

_________________________________
* In the index «National standards», 2008

OKS 77.120, 77.120.50 — note the manufacturer’s database.

Date of introduction 2000−07−01

Preface

1 DEVELOPED by the Interstate technical Committee for standardization MTK 105, Ukrainian research and design Institute of titanium

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 9 dated April 12, 1996)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated 19 October 1999 No. 353-St inter-state standard GOST 9853.19−96 introduced directly as state standard of the Russian Federation from July 1, 2000.

4 INTRODUCED FOR THE FIRST TIME

1 Scope

This standard sets the photometric method for the determination of chromium (if chromium mass fraction from 0.003% to 0.2%) in the spongy titanium according to GOST 17746.

The method is based on oxidation of the chromium to the hexavalent state adalgata ammonium in the presence of silver nitrate, the formation of complex compounds of chromium with diphenylcarbazide with subsequent measurement of optical density of the solution.

2 Normative references

The present standard features references to the following standards:

GOST 8.315−97 State system for ensuring the uniformity of measurements. The standard samples. The main provisions, the order of development, certification, approval, registration and application

GOST 1277−75 Silver nitrate. Specifications

GOST 2603−79 Acetone. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4220−75 Potassium dichromate. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 17746−96 spongy Titanium. Specifications

GOST 18300−87 ethyl rectified technical. Specifications

GOST 20478−75 Ammonium neccersarily. Specifications

GOST 23780−96 spongy Titanium. Methods of sampling and sample preparation

GOST 25086−87 non-ferrous metals and their alloys. General requirements for methods of analysis

3 General requirements

3.1 General requirements for the method of analysis according to GOST 25086.

3.2 Selection and preparation of samples is carried out according to GOST 23780.

3.3 Mass fraction of chromium determined in two batches.

4 measuring instruments and auxiliary devices

Spectrophotometer type SF-46 or photoelectric colorimeter concentration of type KLF-2, or similar device.

Sulfuric acid according to GOST 4204, diluted 1:1 and 1:19.

Nitric acid according to GOST 4461.

Hydrochloric acid according to GOST 3118, diluted 1:3.

Ethanol (ethyl alcohol) rectified technical GOST 18300.

Acetone according to GOST 2603.

Distilled water according to GOST 6709.

Silver nitrate (silver nitrate) GOST 1277, solution mass concentration 10 g/DM.

Ammonium peroxodisulfate (ammonium neccersarily) according to GOST 20478, solution mass concentration of 150 g/DM, freshly prepared.

Diphenylcarbazide according to the current normative document, solution mass concentration of 2.5 g/DM. Prepared by dissolving 0.125 g diphenylcarbazide in 50 cmof ethanol. Allowed to use as solvent a mixture of acetone and water (1:1).

Potassium bichromate (potassium dichromate) according to GOST 4220, recrystallized and dried.

Standard samples according to GOST 8.315.

Standard solutions of chromium.

Solution a: 2,83 g of recrystallized and dried potassium dichromate dissolved in 400 cmof water, transferred into a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water and mix; fit for use for 12 months.

1 cmof the solution contains 0.001 g of chromium.

Solution B: 5 cmsolution And placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix; prepare before use.

1 cmof solution B contains 0,000005 g of chromium.

5 procedures for measuring

5.1 a sample weight of 0.5−1.0 g were placed in a glass with a capacity of 500−600 cm, 160 cm pouredwater, 25 cmof sulfuric acid solution (1:1) and conduct the dissolution under heating. After complete dissolution of the sample to the solution dropwise adding nitric acid to the bleaching solution, and then add 2−3 drops excess. The solution is evaporated until the appearance of dense vapors of sulphuric anhydride, cooled and diluted with water to 300 cm.

The solution is heated to boiling, add 10 cmof silver nitrate solution, 20cmsolution peroxodisulfate ammonium and boil for 20 minutes (to decompose the excess ammonium peroxodisulfate). If the boiling is stable pink color of the solution due to the presence of manganese in the sample, add 5 cmof hydrochloric acid solution (1:3) and boiled for 10 min If the solution is discolored, add 2 cmof hydrochloric acid solution (1:3).

The contents of the Cup cool, transferred to volumetric flask with a capacity of 500 cm, made up to the mark with water, mix and leave to settle precipitate of silver chloride for 30−40 min.

Aliquot part of the solution is 25 cmis placed in a volumetric flask with a capacity of 50 cm, is diluted with water to a volume of about 40 cm, add 3 cmof a solution diphenylcarbazide, made up to the mark with water and mix.

After 15 min measure the optical density of the solution at a wavelength of 580 nm in the thickness of the absorbing layer is 20 mm. as a solution comparison solution is used in the reference experiment.

Mass fraction of chromium in the sample is calculated according to the calibration g

Rafik.

5.2 For constructing the calibration curve in seven of the eight volumetric flasks with a capacity of 50 cmplaced 0,3; 1,0; 2,0; 3,0; 5,0; 8,0; 10,0 cmstandard solution B, which corresponds to 0,0000015; 0,0000050; 0,000010; 0,000015; 0,000025; 0,000040; 0,000050 g chrome. All eight volumetric flasks poured 25 cmof sulfuric acid solution (1:19), the solutions were diluted with water to a volume of 40 cm. The eighth solution of the flask is a solution of the control experience and acts as a solution comparison. To all flasks add 3 cmof a solution diphenylcarbazide, made up to the mark with water and mix. Then do as specified in 5.1.

According to the obtained values of optical density and corresponding mass building chromium calibration curve.

6 Processing of measurement results

Mass fraction of chrome ,%, is calculated by the formula

, (1)

where is the mass of chromium in the sample solution found by the calibration schedule g;

 — total volume of sample solution, cm;

 — the mass of sample, g;

 — volume aliquote parts of a solution of the sample, cm.

7 the Permissible error of measurement

7.1 the discrepancy between the measurement results and analysis results (at a confidence probability of 0.95) shall not exceed the permissible values given in table 1.


Table 1

7.2 accuracy Control of the results of the analysis carried out according to standard sample in accordance with GOST 25086.

Allowed to monitor the accuracy of analysis results by the method of additives in accordance with GOST 25086.

Additives is a standard solution A.

8 qualifications

To perform analysis allowed the analyst qualification not less than 4th level.