GOST 22974.2-96

• gost-229742-96.pdf (348.05 KiB)
  ГОСТ 22974.2-96

GOST 22974.2−96 fused welding Fluxes. Methods for determination of silicon oxide

GOST 22974.2−96

Group B09

INTERSTATE STANDARD

FUSED WELDING FLUXES

Methods for determination of silicon oxide

Melted welding fluxes.
Methods of silicon oxide determination

ISS 77.040
AXTU 0809

Date of implementation 2000−01−01

Preface

1 DEVELOPED by the Interstate technical Committee for standardization MTK 72; the Institute of electric them. E. O. Paton of NAS of Ukraine

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 April 21, 1999 N 134 inter-state standard GOST 22974.2−96 introduced directly as state standard of the Russian Federation from January 1, 2000

4 REPLACE GOST 22974.2−85

1 Scope

This standard specifies a gravimetric method for the determination of silicon oxide (with a mass fraction of silicon oxide of 10 to 50%), a photometric method for the determination of silicon oxide (with a mass fraction of silicon oxide is from 5 to 20.0%) and gravimetric method for the determination of silicon oxide with additional determination in the filtrate residual silica by the photometric method (at a mass fraction of silicon oxide of 10 to 50%).

2 Normative references

The present standard features references to the following standards:

GOST 83−79 Sodium carbonate. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3765−78 Ammonium molybdate. Specifications

GOST 4165−78 Copper (II) sulfate 5-water. Specifications

GOST 4197−74 Sodium atomistically. Specifications

GOST 4199−76 Sodium tetraborate 10-aqueous. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4332−76 Potassium carbonate — sodium carbonate. Specifications

GOST 6344−73 Thiourea. Specifications

GOST 6995−77 Methanol-poison. Specifications

GOST 9428−73 Silicon (IV) oxide. Specifications

GOST 9656−75 boric Acid. Specifications

GOST 10484−78 hydrofluoric Acid. Specifications

GOST 11293−89 Gelatin food. Specifications

GOST 18300−87 ethyl rectified technical. Specifications

GOST 22974.0−96 fused welding Fluxes. General requirements for methods of analysis

GOST 22974.1−96 fused welding Fluxes. Methods of flux decomposition

3 General requirements

General requirements for methods of analysis GOST 22974.0.

4 Gravimetric method for the determination of silicon oxide

4.1 the essence of the method

The method is based on the fusion of the flux linkage with a mixture of potassium carbonate — sodium carbonate and sodium tetraborate or boric acid, the decomposition of m in hydrochloric acid and separation of the formed silicic acid to precipitate by evaporation of solution to dryness. Mass fraction of silicon oxide is determined by the mass difference before and after treatment with hydrofluoric acid.

This method is not suitable in the presence of titanium oxide in excess of 5%.

4.2 Reagents and solutions

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

Hydrochloric acid according to GOST 3118, diluted 1:1 and 5:95.

Hydrofluoric acid according to GOST 10484.

Boric acid according to GOST 9656.

Potassium carbonate — sodium carbonate according to GOST 4332.

Sodium tetraborate 10-water according to GOST 4199, dehydrated according to GOST 22974.1.

Methanol is a poison according to GOST 6995.

The technical rectified ethyl alcohol according to GOST 18300.

Gelatin food according to GOST 11293, solution mass concentration of 0.01 g/cm.

The beach: mix five parts by weight of potassium carbonate — sodium carbonate and one mass part of sodium tetraborate or boric acid.

4.3 analysis

The linkage of flux with a mass of 0.5 g is fused with 6 g of flux in a platinum crucible with lid at 950−1050 °C for 30 min. the Melt was poured on a polished plate of stainless steel.

Crucible, cover and melt are placed in a porcelain Cup with a diameter of 12−13 cm, flow 50 cmhydrochloric acid (1:1). To prevent splashing of the Cup covered with glass. After decomposition of the melt crucible and the lid is removed and thoroughly washed with water. The solution was evaporated to dryness. To the dry residue poured 20−25 cmof hydrochloric acid and 20−25 cm inmethyl or ethyl alcohol. The solution was evaporated to dryness. Operation of evaporation with hydrochloric acid and alcohol again. To the dry residue poured 20−25 cmof hydrochloric acid, is heated, pour the 70−80 cmof hot water and heated to boiling. The precipitate was filtered off on filter «white ribbon», washed 5−6 times with hot hydrochloric acid (5:95) and several times with hot water. Retain sediment. From the filter reselect the remnants of a silicic acid as described above, but without treatment with alcohol. Retain sediment.

The filtrate was evaporated to dryness. To the dry residue poured 30−35 cmof hydrochloric acid and heated to dissolve the salts. To a solution pour 7−10 cmof gelatin, mix, leave for 10−15 minutes. Pour 50−60 cmof hot water, stirred and filtered, the filter «white ribbon» containing filtrowanie mass.

The precipitate of silicic acid is washed 5−6 times with hot hydrochloric acid (5:95) and several times with hot water.

Precipitation of silicic acid combined, placed in a platinum crucible, dried, calcined at 950−1050 °C for 30−35 minutes, cool in a desiccator and weighed. The ignition is repeated until constant weight. To the calcined precipitate pour 5−10 drops of sulfuric acid (1:1), 5−8 cmhydrofluoric acid and evaporated to dryness. The dry residue was calcined at 950−1050 °C for 3−5 min, cooled and vzveshivat

yut.

4.4 Processing of results

Mass fraction of silicon oxide , %, is calculated by the formula

, (1)

where is the mass of the crucible with the calcined residue of silica before treatment with hydrofluoric acid, g;

 — the mass of the crucible with the calcined residue after treatment with hydrofluoric acid, g;

 — weight of crucible with calcined sediment control experience prior to handling hydrofluoric acid, g;

 — the mass of the crucible with the calcined residue in the reference experiment after treatment with hydrofluoric acid, g;

 — the weight of the portion of the flux,

4.5 Norms of accuracy and norms control the accuracy of determining the mass fraction of silicon oxide are given in table 1.


Table 1

Percentage

5 Photometric method for the determination of silicon oxide

5.1 the essence of the method

Silicon ions in mildly acidic medium react with ammonium molybdate, forming kriminalistov the heteropolyacid is yellow. When you restore the last thiourea in the presence of a catalyst — copper sulphate — blue colour of molybdenum by molybdenum recovery, which is part of heteroalicyclic. The color intensity of the molybdenum blue measured at a wavelength of 810 nm on the spectrophotometer or photoelectrocolorimeter with a red light filter in the cell with thickness of the absorbing layer 10 mm.

5.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Hydrochloric acid according to GOST 3118, diluted 1:1 and 5:95.

Sulfuric acid according to GOST 4204 and solutions with molar concentration of equivalent of 0.15, and 8 mol/DM. Prepare solutions of: 0.15 mol/DM — 5 cmof concentrated sulfuric acid diluted with water to 1000 cm, 8 mol/DM — 230 cmof concentrated sulfuric acid diluted with water to 1000 cm.

Boric acid according to GOST 9656.

Copper (II) sulfate 5-water according to GOST 4165, solution: 20 g of copper sulphate dissolved in 200 cmof water is added 15 cmof concentrated sulfuric acid and dilute to 1000 cm.

Potassium carbonate — sodium carbonate according to GOST 4332.

Sodium atomistically according to GOST 4197, solution mass concentration of 0.02 g/cm.

Sodium tetraborate 10-water according to GOST 4199, dehydrated according to GOST 22974.1.

Sodium carbonate according to GOST 83, solution of the mass concentration of 0.01 g/cm.

Thiourea according to GOST 6344, solution mass concentration of 0.07 g/cm.

Silicon (IV) oxide according to GOST 9428.

The technical rectified ethyl alcohol according to GOST 18300.

Ammonium molybdate according to GOST 3765, recrystallized, solution mass concentration of 0.05 g/cm. For recrystallization 250 g of reagent was dissolved in 400 cmof water when heated to 70−80 °C, the solution was filtered through filter «blue ribbon», cooled to room temperature, poured, with stirring, 300 cmof ethyl alcohol, allow sediment to settle for 1 h and filtered it, the filter «white ribbon» placed in a Buchner funnel, using a water vacuum pump. Precipitate was washed 2−3 times with ethanol and dried in air.

The beach: mix five parts by weight of potassium carbonate — sodium carbonate and one mass part of sodium tetraborate or boric acid.

Standard solutions of silica.

Solution a: 0.2 g calcined at 950−1050 °C to constant mass silica fused in a platinum crucible with lid with 2 g of anhydrous sodium carbonate at a temperature of 950−1050 °C for 15−20 min. the Cooled melt is leached in a solution of sodium carbonate the mass concentration of 0.01 g/cm. The solution is transferred into a measuring flask with volume capacity of 1000 cmand bring to mark with a solution of sodium carbonate the mass concentration of 0.01 g/cm.

The solution And the mass concentration of the silicon oxide 0.0002 g/cm andstored in polyethylene bottle.

The mass concentration of the solution of silica by the gravimetric method specify: 100 smsolution And transferred into a porcelain Cup with a diameter of 12−13 cm and pour 20−25 cmof hydrochloric acid (1:1). The solution was evaporated to dryness. The dry residue moistened with 10−15 cmof hydrochloric acid and again evaporated to dryness. To the dry residue add 10−15 cmof hydrochloric acid, is heated, pour the 70−80 cmof hot water and heated to boiling. Silicic acid is filtered off, the filter «white ribbon» with the addition of a small amount filtrowanie mass. The precipitate is washed 3−6 times with hot hydrochloric acid (5:95) and another 2−3 times with hot water. The filter with the precipitate saved.

The filtrate and the wash liquid is transferred into a porcelain Cup, which conducted the deposition of silicic acid, and evaporated to dryness. To the dry residue poured 15−20 cmof hydrochloric acid and heated to dissolve the salts. To a solution pour 7−10 cmof gelatin, mix, leave for 10−15 minutes. Pour 50−60 cmof hot water, stirred and filtered, the filter «white ribbon» containing filtrowanie mass.

The precipitate of silicic acid is washed 3−5 times with hot hydrochloric acid (5:95) and 2−3 times with hot water.

Precipitation of silicic acid combined, placed in a platinum crucible, dried and calcined at a temperature of 950−1050 °C for 30−35 minutes, cool in a desiccator and weighed. To the calcined precipitate pour 5−10 drops of sulfuric acid (1:1), 5−8 cmhydrofluoric acid and evaporated to dryness. The dry residue is calcined at a temperature of 950−1050 °C for 3−5 min, cooled and weighed.

The mass concentration of the solution of silicon oxide , g/cm, is calculated by the formula

, (2)

where is the mass of the crucible with the precipitate of silicon oxide, g;

 — weight of crucible with residue after treatment with hydrofluoric acid, g;

 — the mass of the crucible with the sediment in the control analysis, g;

 — the mass of the crucible with the residue in the control analysis after treatment with hydrofluoric acid, g;

 — the volume of solution A, cm.

Solution B: 25 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix; prepare before use.

Solution B has a mass concentration of silicon oxide of 0.00005 g/s

m.

5.3 analysis

5.3.1 Weighed flux with a mass of 0.1 g is fused in a platinum crucible with 3 g of flux at a temperature of 950−1050 °C for 10−15 min. the Cooled crucible with the melt is placed in a polyethylene beaker with a capacity of 500 cm, which is pre-poured 150 cmwater and 15 cmof concentrated sulfuric acid. After decomposition of the melt crucible and the lid is removed, washing them over a Cup. If the solution is colored pink, then added dropwise a solution of sodium attestatio to its discoloration. The solution was transferred to a volumetric flask with a capacity of 500 cm, was adjusted to the mark with water and again transferred into a plastic Cup.

Select aliquot part of the solution is 3−10 cm(depending on the content of silicon oxide in the flux) in a volumetric flask with a capacity of 100 cm, flow 20 cmof sulfuric acid solution of molar concentration 0.15 mol/DM5 cmof a solution of ammonium molybdate mass concentration of 0.05 g/cm. The solution was stirred and allowed to stand for 10 min for full development of yellow color. Then pour 15 cmof sulfuric acid solution the molar concentration of 8 mol/DM5 cmof copper sulfate solution and 25 cmof a solution of thiourea, made up to the mark with water and mix.

Optical density of the solution measured on a spectrophotometer at a wavelength of 810 nm or photoelectrocolorimeter with a red light filter in the cell thickness of the absorbing layer 10 mm. as a solution the comparison serves as a control test, carried out through all stages of the analysis.

The mass of silica found by the calibration

graphics.

5.3.2 Construction of calibration curve

In six volumetric flasks with a capacity of 100 cmconsistently make 1; 2; 3; 4; 5; 6 cmstandard solution B, which corresponds to 0,00005; 0,00010; 0,00015; 0,00020; 0,00025; 0,00030 g of silicon oxide.

The seventh flask was used for solution preparation comparison, make 2 cmof sodium carbonate solution mass concentration of 0.01 g/cm. Pour 20 cmof sulfuric acid solution of molar concentration 0.15 mol/DMand then carry out the analysis in 5.3.1.

5.4 processing of the results

Mass fraction of silicon oxide , %, is calculated by the formula

, (3)

where is the mass of silica found by the calibration schedule g;

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

5.5 the Norms of accuracy and norms control the accuracy of determining the mass fraction of silicon oxide are given in table 1.

6 Gravimetric method for the determination of silicon oxide with additional determination in the filtrate residual silica by the photometric method

6.1 the essence of the method

The method is based on the fusion of the flux linkage with a mixture of potassium carbonate — sodium carbonate and sodium tetraborate or boric acid, dissolving the melt in hydrochloric acid, separation of the resulting silicic acid in the precipitate by single evaporation to dryness and the assignment of remaining in the filtrate acid by the photometric method.

6.2 Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Sulfuric acid according to GOST 4204 with molar concentration of equivalent of 0.15, and 8 mol/DM. Prepare solutions of: 0.15 mol/DM — 5 cmof concentrated sulfuric acid diluted with water to 1000 cm; 8 mol/DM — 230 cmof concentrated sulfuric acid diluted with water to 1000 cm.

Hydrochloric acid according to GOST 3118, diluted 1:1 and 5:95.

Boric acid according to GOST 9656.

Ammonium molybdate according to GOST 3765, recrystallized, massive concentration of 0.05 g/cm(5.2).

Potassium carbonate — sodium carbonate according to GOST 4332.

Copper (II) sulfate 5-water according to GOST 4165.

Sodium tetraborate 10-water according to GOST 4199, dehydrated according to GOST 22974.2.

Sodium carbonate according to GOST 83, solution of the mass concentration of 0.01 g/cm.

Thiourea according to GOST 6344, solution mass concentration of 0.07 g/cm.

Silicon (IV) oxide according to GOST 9428.

The beach: mix five parts by weight of potassium carbonate — sodium carbonate and one mass part of sodium tetraborate or boric acid.

Standard solutions of silica —

5.2.

6.3 analysis

The linkage of flux with a mass of 0.5 g is fused with 6 g of flux in a platinum crucible with lid at a temperature of 950−1050 °C for 30−35 min. the Melt was poured on a polished plate of stainless steel.

Crucible, cover and melt are placed in a porcelain Cup with a diameter of 12−13 cm, flow 50 cmhydrochloric acid (1:1). To prevent splashing of the Cup covered with glass. After decomposition of the melt crucible and the lid is removed and thoroughly washed with water. The solution was evaporated to dryness. To the dry residue poured 20 cmof hydrochloric acid, is heated, pour the 70−80 cmof hot water and heated to boiling. The precipitate of silicic acid is filtered off, the filter «white ribbon», washed 5−6 times with hot hydrochloric acid (5:95) and several times with hot water. The solution was filtered into a plastic Cup. The solution was transferred to a volumetric flask with a capacity of 500 cm, was adjusted to the mark with water.

Select aliquot part of 20−25 cmin a volumetric flask with a capacity of 100 cm, and then 5.3.1; 5.3.2; 5.4.

The precipitate of silicic acid is placed in a platinum crucible, dried, calcined at 950−1050 °C, followed by 4.3, 4.4.

6.4 Processing of results

Mass fraction of silicon oxide , %, is calculated by the formula

, (4)

where  — mass fraction of silicon oxide, defined gravimetrically, %;

 — mass fraction of silicon oxide, as determined photometrically, %.

6.5 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of silicon oxide are given in table 1.