GOST 22974.5-96

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  ГОСТ 22974.5-96

GOST 22974.5−96 fused welding Fluxes. Methods for determination of calcium oxide and magnesium oxide

GOST 22974.5−96

Group B09

INTERSTATE STANDARD

FUSED WELDING FLUXES

Methods for determination of calcium oxide and magnesium oxide

Melted welding fluxes. Methods of calcium and magnesium oxides 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 22974.5−96 introduced directly as state standard of the Russian Federation from January 1, 2000

4 REPLACE GOST 22974.5−85

1 Scope

This standard establishes titrimetric chelatometric method for the determination of calcium oxide (at mass fraction of calcium oxide from 1 to 60%), titrimetric chelatometric method for the determination of magnesium oxide (with a mass fraction of magnesium oxide from 0.5 to 20%) and atomic absorption method for the determination of magnesium oxide (with a mass fraction of magnesium oxide from 0.5 to 5%).

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 3773−72 Ammonium chloride. Specifications

GOST 4234−77 Potassium chloride. Specifications

GOST 4526−75 Magnesium oxide. Specifications

GOST 5457−75 dissolved Acetylene and gaseous technical

GOST 8677−76 Calcium oxide. Specifications

GOST 8864−71 Sodium N, N-diethyldithiocarbamate 3-water. Specifications

GOST 10652−73 Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B)

GOST 24363−80 Potassium hydroxide. 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

GOST 22974.4−96 fused welding Fluxes. Method for the determination of aluminium oxide

GOST 22974.11−96 fused welding Fluxes. Methods for determination of calcium fluoride

3 General requirements

General requirements for methods of analysis GOST 22974.0.

4 Titrimetric chelatometric method for the determination of calcium oxide

4.1 the essence of the method

The method is based on titration of calcium ions by Trilon B in alkaline medium (pH 12−13). For the best indication of the end of the titration, a mixture of indicators of fluoresone and thymolphtalein. In the equivalent point, the green fluorescent color changes to pink.

Determine the mass fraction of total calcium calculated as calcium oxide, and then subtract the mass percent of calcium fluoride.

4.2 Reagents and solutions

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

Potassium hydroxide according to GOST 24363, solution mass concentration of 0.2 g/cm.

Potassium chloride according to GOST 4234.

Sodium N, N-diethyldithiocarbamate according to GOST 8864, solution mass concentration of 0.1 g/cm.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, solution with molar concentration of equivalent of 0.025 mol/DM: 4.65 g Trilon B dissolved in 300 cmof water. The solution was filtered into a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water and mix.

Malachite green (indicator), the solution of the mass concentration of 0.01 g/cm.

Fluoresce (indicator).

Thymolphthalein (indicator).

A mixture of indicators: 0.2 g of fluoresone and 0.05 g of thymolphthalein ground in a mortar with 20 g of potassium chloride.

Calcium oxide according to GOST 8677, pre-calcined at 950−1000 °C for 1 h.

Standard solution: 0.5 g of calcium oxide were placed in a glass with a capacity of 300 cm, moisten with water, add 10 cmof hydrochloric acid (1:1) heat until complete dissolution of the sample, transferred into volumetric flask with a capacity of 1000 cmand dilute to the mark with water. The solution has a mass concentration of calcium oxide 0.0005 g/cm.

The establishment of the mass concentration of the solution Trilon B.

To establish the mass concentration of the solution Trilon B taken in 25 cmof a standard solution of calcium oxide in three conical flasks with a capacity of 250 cm, pour 5−6 drops of the indicator is malachite green and a thin stream with vigorous stirring a solution of potassium hydroxide mass concentration of 0.2 g/cmto a bleaching solution, add 0.1 g of a mixture of indicators and titrated with a solution of Trilon B before the transfer of the green fluorescent color of the solution pink.

Mass concentration of Trilon B , g/cmcalcium oxide, calculate by the formula

, (1)

where  — the weight of the portion corresponding to aliquote part of the solution, g;

 — volume of solution Trilon B, spent on titration, sm.

4.3 analysis

To the filtrate in a volumetric flask with a capacity of 500 cmafter separating the Sesqui-oxides according to GOST 22974.4 add 50 cmof a solution of sodium diethyldithiocarbamate (when the mass fraction of manganese oxide (II) up to 25%) or 75 cm(at the mass fraction of manganese oxide (II) from 25 to 50 cm). The flask is stoppered and vigorously shaken for 4−5 min for the rapid coagulation of organo manganese. The solution in the flask was adjusted to the mark with water and allowed to settle for 1 h and then filtered through two dry filter into a dry flask, discarding first portion of filtrate.

Take 100 cmof the solution in the conical flask with a capacity of 500 cm, pour 5−6 drops of the indicator is malachite green and a thin stream with vigorous stirring add a solution of potassium hydroxide mass concentration of 0.2 g/cmto the bleaching solution. To the solution was added 0.1 g of a mixture of indicators and titrated with a solution of Trilon B before the transfer of the green fluorescent color of the solution pink

.

4.4 Processing of results

4.4.1 Mass fraction of total calcium in terms of calcium oxide , %, is calculated by the formula

, (2)

where  — volume of solution Trilon B, used for titration of aliquots part of the solution, cm;

 — mass concentration of Trilon B, g/cmcalcium oxide;

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

4.4.2 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of total calcium in terms of calcium oxide are given in table 1.


Table 1

Percentage

4.4.3 Mass fraction of free calcium oxide in the sample in % is calculated by the formula

, (3)

where  — mass fraction of calcium in terms of calcium oxide, %;

 — mass fraction of calcium fluoride, was found in GOST 22974.11, %;

0,718 — the ratio of calcium fluoride to the calcium oxide.

4.4.4 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of free calcium oxide are given in table 2.


Table 2

Percentage

5 Titrimetric chelatometric method for the determination of magnesium oxide

5.1 the essence of the method

The method is based on the formation in solution with calcium ions and magnesium complex compounds with eriochrome black T painted in a lilac color. With the introduction of Trilon B solution (pH 9−10) this complex compound is destroyed, calcium and magnesium are associated with Trilon B in a strong connection.

In the equivalent point of purple coloration of the complex compounds of calcium and magnesium with eriochrome black T collapses and appears the blue color of the free indicator.

The volume of Trilon B, used for titration of magnesium oxide in the sample is calculated by difference between the volume of Trilon B, used for titration of total calcium oxide and magnesium and total calcium.

5.2 Reagents and solutions

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

Ammonia water according to GOST 3760.

Ammonium chloride according to GOST 3773.

Potassium chloride according to GOST 4234.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, Trilon solution with molar concentration of equivalent of 0.025 mol/l, prepared according to 4.2.

Eriochrome black T (indicator): 0.2 g of the indicator is triturated in a mortar with 20 g of potassium chloride.

Ammonia buffer: 57.5 g of ammonium chloride dissolved in 200 cmof water, add 570 cmof ammonia, diluted to 1000 cmand mixed.

Magnesium oxide according to GOST 4526, standard solution: 0.5 g of magnesium oxide, previously calcined at 850−900 °C to constant weight, is placed in a beaker with a capacity of 200−300 cm, moistened with 10 cmof water, add 25 cmof hydrochloric acid (1:1). The solution was heated until complete dissolution of magnesium oxide, cooled, transferred into a measuring flask with volume capacity of 1000 cmand dilute to the mark with water. The solution has a mass concentration of magnesium oxide is 0.0005 g/cm.

The establishment of the mass concentration of the solution Trilon B: three conical flasks with a capacity of 250 cmtaken at 25 cmstandard solution of magnesium oxide, is poured on a 100 cmwater, 10 cmof ammonium buffer solution, add 0.1 g of indicator eriochrome black T and titrate with a solution of Trilon B till the transition of color from purple to blue.

The mass concentration of the solution Trilon B , g/cmof magnesium oxide, calculate by the formula

, (4)

where  — weight of magnesium oxide, corresponding to aliquote part of the solution, g;

 — volume of solution Trilon B, spent on titration, sm.

5.3 analysis

To determine the amount of total calcium and magnesium oxide taken 100 cmsolution (see 4.3 after separation of manganese) in a conical flask with a capacity of 500 cm, flow 50 cmwater, 10 cmof ammonium buffer solution, add 0.1 g of indicator eriochrome black T and titrate with a solution of Trilon B to switch the color of the solution in blue.

5.4 processing of the results

5.4.1 Mass fraction of magnesium oxide , %, is calculated by the formula

, (5)

where  — volume of solution Trilon B, used for titration of total calcium and magnesium oxide, cm;

 — volume of solution Trilon B, used for titration of total calcium, cm;

 — mass concentration of Trilon B, g/cmof magnesium oxide;

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

.

5.4.2 Norms of accuracy and norms control the accuracy of determining the mass fraction of magnesium oxide are shown in table 3.


Table 3

Percentage

6 Atomic absorption method for the determination of magnesium oxide

6.1 the essence of the method

The method is based on measuring the degree of absorption of resonance radiation by free atoms of magnesium, formed as a result of spraying the test solution into the flame air-acetylene.

6.2 Apparatus, reagents and solutions

Atomic absorption spectrophotometer.

Lamp with hollow cathode for the determination of magnesium.

Acetylene, dissolved and gaseous technical GOST 5457.

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

Potassium chloride according to GOST 4234, solution mass concentration of 0.35 g/cm.

Magnesium oxide according to GOST 4526, standard solution: prepare as specified in 5.2, and diluted with water 10 times. The solution has a mass concentration of magnesium oxide of 0.00005 g/cm.

6.3 Preparation for analysis

Before operation, set the device on resonance line RUB 285.2 nm.

6.4 analysis

After the decomposition flux according to GOST 22974.1 5 cmof solution is transferred to a volumetric flask with a capacity of 500 cm, add 50 cmof a solution of potassium chloride to repay the ionization of magnesium, and 10 cmof hydrochloric acid (1:1), adjusted to the mark with water and mix. Is sprayed into the flame of the solution in the reference experiment, and then analyze the solution.

Prior to introduction into the flame of each solution is sprayed water to wash the system and check the zero point.

6.5 Construction of calibration curve

In a volumetric flask with a capacity of 100 cmplaced 0,2; 0,4; 0,6; 0,8; 1,0; 1,2; 1,4; 1,6; 1,8; 2,0 cmstandard solution, which corresponds to 0,00001; 0,00002; 0,00003; 0,00004; 0,00005; 0,00006; 0,00007; 0,00008; 0,00009 and 0,00010 g of magnesium oxide, add 10 cmof potassium chloride, 2 cmof hydrochloric acid (1:1), adjusted to the mark with water and mix. Further arrive at 6.4.

6.6 processing of the results

Determine the average value of the optical density of solutions in the reference experiment and subtracted this value from the average value of the optical density of the test solutions. According to the calibration schedule, find mass (g) of magnesium oxide in the test solution.

6.6.1 Mass fraction of magnesium oxide , %, is calculated by the formula

, (6)

where is the mass of magnesium oxide found for the calibration graphics g;

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

6.7 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of magnesium oxide are shown in table 3.