GOST 19863.6-91

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  ГОСТ 19863.6-91

GOST 19863.6−91 Alloy of titanium. Methods for determination of silicon

GOST 19863.6−91

Group B59

STATE STANDARD OF THE USSR

ALLOYS OF TITANIUM

Methods for determination of silicon

Titanium alloys.
Methods for the determination of silicon

AXTU 1709

Date of introduction 1992−07−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of aviation industry of the USSR

DEVELOPERS

V. G. Davydov, doctor of engineering. Sciences; V. A. Moshkin, PhD. tech. Sciences; G. I. Friedman, PhD. tech. Sciences; L. A. Tenyakova; M. N. Gorlova, PhD. chem. Sciences; L. V. Antonenko, O. L. Sikorska, PhD. chem. Sciences

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 5.05.91 N 625

3. REPLACE GOST 19863.6−80

4. The frequency of inspection — 5 years

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the photometric (with a mass fraction of from 0.04 to 0.5%) and atomic absorption (at a mass fraction of from 0.1 to 0.5%) methods for determination of silicon.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 25086 with the Supplement.

1.1.1. For the results analysis be the arithmetic mean of results of two parallel measurements.

2. PHOTOMETRIC METHOD FOR DETERMINATION OF SILICON

2.1. The essence of the method

The method is based on dissolving the sample in sulfuric acid, the formation of the yellow form kremneftoristogo acid, restoring its salt Mora to the blue form kremneftoristogo acid and measuring the optical density of the solution at a wavelength of 625 nm.

Alikvotnih from different parts of the same sample solution and determine mass fraction of silicon and iron.

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Muffle furnace with thermostatic control.

Filters obestochennye on the other 6−09−1678.

Adsorbent (materiana paper): 100 g of crushed filters (red ribbon) is placed in a beaker with a capacity of 500 cm, 300 cm pouredhot water and stirred with a stirrer to obtain a homogeneous mass.

Hydrofluoric acid according to GOST 10484.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cmand a solution of 1:99.

Sulfuric acid according to GOST 4204 density 1.84 g/cmand a solution of 1:1, 1:3 and 1:99.

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

Sodium hydroxide according to GOST 4328, a solution of 5 g/DM, cook and store in a plastic container.

The technical rectified ethyl alcohol according to GOST 18300.

Ammonia water according to GOST 3760.

Ammonium molybdate according to GOST 3765, recrystallized from alcohol solution, a solution of 100 g/DM, freshly prepared; prepared in a plastic container.

For recrystallization 250 g ammonium molybdate was placed in a beaker with a capacity of 1 DM, pour 400 cmof water, heated to a temperature of (80±2) °C, dissolved with stirring stick, add ammonia until the smell and the hot solution is filtered through a dense filter («blue ribbon») in a glass contains 300 cmof ethyl alcohol. The solution is cooled to a temperature of (10±2) °C and allowed to settle for 1 h. Precipitated crystals are filtered off through a Buchner funnel, sucking mother liquor through the filter medium density («white ribbon»).

The crystals are washed three times with ethanol in portions of 30 cm, after which they are spread evenly on a sheet of filter paper covering the second sheet of paper, and dried in air for 8−10 hours

Salt of protoxide of iron and ammonium double sulfate (salt Mora) according to GOST 4208, a solution of 50 g/l: 50 grams of reagent were placed in a glass with a capacity of 400 cm, 200 cm pourthe sulfuric acid 1:99 and dissolve the sample when heated. The solution was filtered through a double folded thick filter (the"blue ribbon") in a conical flask with a capacity of 1 DM, pour the 440 cmof sulfuric acid solution 1:1, cooled to room temperature, poured water to a volume of 1 DMand stirred.

Titanium sponge according to GOST 17746* stamps TG-100.
_______________
* On the territory of the Russian Federation GOST 17746−96, here and hereafter. — Note the manufacturer’s database.

Sodium meta-silicate 9-water on the other 6−09−5337.

Standard solution of silica: 1 g of sodium silicate were placed in a glass with a capacity of 400 cm, dissolved in 100 cmof water, add 1 cmof sodium hydroxide solution and filtered the solution through a thick folded filter («blue ribbon») in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

The solution was stored in a plastic container.

1 cmof the solution contains 0.0001 gram of silicon.

To establish the mass concentration of the silicon aliquot part of the solution is 50 cmis placed in a porcelain Cup with a capacity of 200 cm, flow 10 cmof hydrochloric acid, stirred, evaporated to dryness, poured 10 cmof hydrochloric acid and again evaporated to dryness. To the dry residue poured 10 cmof hydrochloric acid, 100 CCof hot water, mix and leave in a warm place plate at a temperature of 50−60 °C for 40 min to coagulate the precipitate. The precipitate was filtered off through a filter medium density («white ribbon») with an adsorbent and washed eight times with hot hydrochloric acid 1:99.

The filter with the sediment is dried, incinerated in a platinum crucible and calcined in a muffle furnace at a temperature of 1000−1100 °C for 30 min, the Crucible was cooled to room temperature and weighed. Then, to the residue in the crucible add a polyethylene pipette, ten drops of hydrofluoric acid, one drop sulfuric acid and heated to stop the allocation of white fumes of sulfuric acid. The crucible with the residue is again calcined in a muffle furnace at a temperature of 1000−1100 °C for 10 min, cooled to room temperature and weighed.

The mass concentration of silicon (), g/cm, is calculated by the formula

, (1)

where is the mass of the sludge before treatment with hydrofluoric acid, g;

 — the mass of the precipitate after treatment with hydrofluoric acid, g;

0,4675 — the ratio of silicon dioxide on silicon;

 — the volume of a standard solution taken for the determination of silicon,

m.

2.3. Analysis

2.3.1. A portion of the sample in accordance with table.1 is placed in a conical flask with a capacity of 100 cm, 30 cm, pourthe sulfuric acid 1:3, cover the flask with a watch glass or funnel and heated to dissolve the sample, maintaining the initial volume with water. At the same time dissolve the appropriate linkage of titanium sponge.

Table 1

The solution is poured dropwise a solution of hydroxylamine hydrochloride to the disappearance of violet colour, five drops in excess and boil for 1−2 min. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

2.3.2. Aliquot part of the solution was 10 cm,transferred to a volumetric flask with a capacity of 100 cm, pour the 30 cmwater, 10 cmof a solution of molybdate of ammonium. The solution is allowed to stand for 30 minutes, poured 30 cmof sulfuric acid solution 1:3 and stirred until complete dissolution of the white precipitate.

The clear solution was poured 10 cmof salt solution Mora, made up to the mark with water and mix.

2.3.3. Optical density of the solution measured after 5 min at a wavelength of 625 nm in a cuvette with a layer thickness fotometricheskogo 50 mm at a mass fraction of silicon is less than 0.1% and 30 mm at a mass fraction of silicon greater than 0.1%. Solution comparison is aliquota part of the control experience, prepared according to PP.2.3.1, 2.3.2, all used in the analysis reagents.

Mass fraction of silicon is calculated according to the calibration schedule.

2.3.4. Construction of calibration curve

In nine out of ten volumetric flasks with a capacity of 100 cmmeasured 0,1; 0,2; 0,3; 0,4; 0,5; 0,6; 0,7; 0,8; 0,9 cmstandard solution silicon, which corresponds to 0,00001; 0,00002; 0,00003; 0,00004; 0,00005; 0,00006; 0,00007; 0,00008; 0,00009 g of silicon, all of the flask pour 10 cmof a solution of titanium, obtained according to claim 2.3.1 and continue at PP.2.3.2, 2.3.3.

Solution comparison is the solution, in which silicon is not introduced.

According to the obtained values of optical density of the solutions and their corresponding masses of silicon to build the calibration graph.

2.4. Processing of the results

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

, (2)

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

 — weight of sample in aliquote part of the solution,

2.4.2. Discrepancies in the results must not exceed the values given in table.2.

Table 2

3. ATOMIC ABSORBTSIONNYI METHOD FOR DETERMINATION OF SILICON

3.1. The essence of the method

The method is based on dissolving the sample in hydrochloric and bridgestation acids and measuring the nuclear absorption of silicon at a wavelength of 251,6 nm in a flame acetylene — nitrous oxide.

3.2. Apparatus, reagents and solutions

Spectrophotometer of atomic absorption with a radiation source for silicon.

Acetylene according to GOST 5457.

Nitrous oxide medical.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cmand a solution of 2:1, 1:1 and 1:99.

Nitric acid according to GOST 4461 density of 1,35−1,40 g/cm.

Sulfuric acid according to GOST 4204 density 1.84 g/cm.

Boric acid according to GOST 9656.

Hydrofluoric acid according to GOST 10484.

Acid bridgestation: 280 cmhydrofluoric acid at a temperature of (10±2) °C add portions 130 g of boric acid and stirred. The solution is prepared and stored in a plastic container.

Titanium sponge according to GOST 17746 grade TG-100.

Sodium meta-silicate 9-water on the other 6−09−5337.

Standard solutions of silicon

Solution a: 10,112 g of sodium silicate dissolved in Teflon beaker in 100 cmof water with moderate heating, the solution was transferred to volumetric flask with a capacity of 200 cm, adjusted to the mark with water and mix. The solution was stored in a plastic container.

1 cmof the solution contains about 0.005 g of silicon.

The mass concentration of silicon (), g/cmstandard solution And establish the gravimetric method.

Aliquot part of the solution And equal to 5 cm, placed in a porcelain Cup, add 10 cmof hydrochloric acid, stirred, evaporated to dryness, to the residue add 10 cmof hydrochloric acid and again evaporated to dryness. To the dry residue poured 10 cmof hydrochloric acid, 100 CCof hot water, mix and leave to stand in a warm place plates for 40 minutes to coagulate the precipitate. The precipitate was filtered off through a filter medium density («white ribbon») with an adsorbent and washed eight times with hot hydrochloric acid 1:99. Further operations are carried out according to claim 2.2.

Solution B: 5 cmsolution And measured in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution is prepared before use.

1 cmof solution B contains about 0,00025

g silicon.

3.3. Analysis

3.3.1. A portion of sample weighing 0.5 g was placed in Teflon beaker with a capacity of 100 cm, flow 20 cmof a hydrochloric acid solution of 2:1, 1 cmbridgestation acid. Close the glass lid and are dissolving at room temperature (dissolution occurs within 3−8 h, depending on the alloy composition). After dissolution of the sample add 5 cmof nitric acid, 10 cmbridgestation acid and allowed to stand for 20 minutes transfer the solution into a measuring flask with a capacity of 100 cm, made up to the mark with water, mixed and transferred into the glass, which had a dissolution.

3.3.2. The solutions in the reference experiment is prepared according to claim 3.3.1.

3.3.3. Construction of calibration curve

Seven Teflon beakers with a capacity of 100 cmis placed 0.5 g of sponge titanium in five of them measure 2,0; 4,0; 6,0; 8,0; 10,0 cmstandard solution B, which corresponds to 0,0005; 0,001; 0,0015; 0,002; 0.0025 g of silicon, and conduct dissolution according to claim 3.3.1.

3.3.4. The sample solution, the solutions in the reference experiment and the solutions for constructing the calibration curve is sprayed into the flame of acetylene — nitrous oxide (recovery) and measure the atomic absorption of silicon at a wavelength of 251,6 nm.

According to the obtained values of atomic absorption and corresponding mass concentrations of silicon to build a calibration curve in the coordinates «Value of atomic absorption — Mass concentration of silicon, g/cm».

The mass concentration of silicon in solutions of the sample solution and the reference experiment is determined by the calibration schedule.

3.4. Processing of the results

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

, (3)

where is the mass concentration of silicon in the sample solution found by the calibration schedule, g/cm;

 — mass concentration of silicon in solution in the reference experiment, was found in the calibration schedule, g/cm;

 — the volume of the sample solution, cm;

 — the weight of the portion in the sample solution, g

.

3.4.2. Discrepancies in the results must not exceed the values given in table.3.

Table 3