GOST 21639.5-93

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  ГОСТ 21639.5-93

GOST 21639.5−93 Fluxes for electroslag remelting. Method for the determination of titanium dioxide

GOST 21639.5−93

Group B09

INTERSTATE STANDARD

Fluxes for electroslag remelting

METHOD FOR THE DETERMINATION OF TITANIUM DIOXIDE

Fluxes for electroslag remelting.
Method for determination of titanium dioxide

OKS 71.040.040*
AXTU 0709

________________

* In the index «National standards» 2006 ACS 25.160.20. -

Note the «CODE».

Date of introduction 1996−01−01

Preface

1 PREPARED by the Russian Federation — Technical Committee TC 145 «monitoring Methods of steel products"

SUBMITTED by the Technical Secretariat of the Interstate Council for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification 17 February 1993.

The adoption voted:

3 Decree of the Russian Federation Committee on standardization, Metrology and certification from 14.06.95 No. 300 interstate standard GOST 21639.5−93 introduced directly as state standard of the Russian Federation from January 1, 1996

4 REPLACE GOST 21639.5−76

1 SCOPE

This standard sets the photometric method for the determination of titanium dioxide in fluxes for electroslag remelting at a mass fraction of from 0.01 to 0.5%.

The method is based on formation of yellow colored coordination compounds of titanium with diantipyrylmethane in hydrochloric acid medium and measuring the degree of absorption of the resulting solution in the spectrophotometer or photoelectrocolorimeter.

2 NORMATIVE REFERENCES

The present standard features references to the following standards:

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 7172−76 Potassium preservatory. Specifications

GOST 9656−75 boric Acid. Specifications

GOST 19807−91 Titanium and titanium wrought alloys. Brand

GOST 21639.0−93 Fluxes for electroslag remelting. General requirements for methods of analysis.

3 GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 21639.0.

4 APPARATUS, REAGENTS AND SOLUTIONS

Spectrophotometer or photoelectrocolorimeter.

Ascorbic acid, a solution with a mass concentration of 50 g/DM.

Sulfuric acid according to GOST 4204, and diluted 1:5 and 1:9.

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

Acid chloride with a mass concentration of 1510 g/DM, diluted 1:1 saturated boric acid at a temperature of 45−55 °C.

Boric acid according to GOST 9656.

Nitric acid according to GOST 4461.

Ammonia water according to GOST 3760.

Methyl red.

Potassium preservatory according to GOST 7172.

Diantipyrylmethane, a solution with a mass concentration of 10 g/DMof 10 g diantipyrylmethane dissolved in 300−400 cmof water containing 15 cmof sulfuric acid. The solution was filtered into a measuring flask 1 DM, add 5 g of ascorbic acid, made up to the mark with water and mix.

Titanium metal according to GOST 19807.

Titanium dioxide.

Standard solution A: prepared from titanium metal (variant I) and titanium dioxide (variant II).

Option I: 0,5995 g of titanium metal is dissolved in 50−100 cmof sulphuric acid (1:5). After dissolution, the titanium is added dropwise nitric acid to the bleaching solution and evaporated until the appearance of dense white fumes of sulfuric acid. After cooling, wash the side of the Cup with water and again evaporated to fumes of sulfuric acid. This operation is repeated. The solution after cooling was transferred into a measuring flask with a capacity of 1 DM, made up to the mark with sulphuric acid (1:5) and stirred.

Option II: 1.0 g titanium dioxide is placed in a platinum Cup and melted with 12 g of potassium peacemaking at a temperature of 800−850 °C. the Alloy is dissolved in 400 cmof sulphuric acid (1:5) under low heat. After complete dissolution of the alloy solution is filtered through a filter of medium density in a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with sulphuric acid (1:9) and stirred.

The mass concentration of sulfate solution of titanium set as follows: 50 cmsolution And placed in a beaker with a capacity of 300 cm, is neutralized with ammonia by methyl red and pour 3−4 cmof ammonia in excess. The solution with the precipitated sludge is heated to boiling, the precipitate was filtered off through a medium density filter and washed 4−5 times with hot water with addition of ammonia (2−3 drops). The filter with precipitate was placed in a preheated to constant weight platinum crucible, dried, incinerated and calcined at a temperature of (1000±20) °C to constant weight.

Simultaneously conduct control experience for contamination of reagents.

The mass concentration of sulfate solution (titanium), expressed in g of titanium dioxide per 1 cmof a solution, calculated by the formula

,

where is the mass of the crucible with the precipitate of titanium dioxide, g;

 — weight of empty crucible, g;

 — the mass of the crucible with the sediment in the reference experiment, g;

 — weight of empty crucible in the reference experiment, g;

 — the volume of sulfate solution of titanium, taken for installation of the mass concentration, cm.

5 ANALYSIS

5.1 the Linkage of flux with a mass of 0.5 g was placed in a platinum or stekloproduct Cup, moisten with water, pour 5 cmof nitric acid and heated for 5−7 min. Then add 10 cmof perchloric acid saturated with boric acid, and evaporated to dryness. The dry residue cautiously heated, and then calcined at a temperature of 750−800 °C for 2−3 min.

Calcined residue is fused with 4−5 g peacemaking potassium at a temperature of 750−800 °C. In a Cup pour 50 cmof sulfuric acid solution (1:9) and heated with stirring rod to dissolve the precipitate.

The contents of the Cup was transferred to volumetric flask of 100 cm, cooled, adjusted to the mark with sulphuric acid (1:9) and stirred. The insoluble sulfate salt of calcium is filtered over a dry filter into a dry flask, discarding first portion of filtrate.

Aliquoting a portion of the filtrate is 50 cm(at a mass proportion of titanium dioxide is from 0.01 to 0.1%) or 10 cm(when the mass fraction of titanium dioxide than 0.1%) is placed in a volumetric flask with a capacity of 100 cm. Add 5 cmof ascorbic acid solution, mixed, incubated 10 min until full recovery of iron. Add 10 cmof hydrochloric acid, 25 cmsolution diantipyrylmethane, adjusted to the mark with water and mix. Optical density of the solution is measured after 45−50 min on the spectrophotometer at a wavelength of 395 nm or photoelectrocolorimeter in the wavelength range from 400 to 440 nm.

Solution comparison is the solution of the control op

it.

5.2 For constructing a calibration curve in five volumetric flasks with a capacity of 100 cmis administered 0,25; 0,5; 1,0; 2,0; 3,0 cmstandard solution B, which corresponds to 0,000025; 0,00005; 0,0001; 0,0002; 0.0003 grams of titanium dioxide. Then in each flask add 5 cmof ascorbic acid, 10 cmof hydrochloric acid, 25 cmsolution diantipyrylmethane. The solution in the flasks was adjusted to the mark with water and mix. Optical density of the solution is measured after 45−50 min on the spectrophotometer at a wavelength of 395 nm or photoelectrocolorimeter in the wavelength range from 400 to 440 nm.

For solution comparison, use water.

On the found values of optical density of solutions with allowance for the titanium content in the reactants build the calibration graph.

6 PROCESSING OF THE RESULTS

6.1 Mass fraction of titanium dioxide () in percent is calculated by the formula

,

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

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

6.2 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of titanium dioxide are given in table 1.


Table 1 — Standards of accuracy control