GOST 15027.20-88
GOST 15027.20−88 Bronze without tin. Methods for determination of magnesium
GOST 15027.20−88
Group B59
INTERSTATE STANDARD
BRONZE WITHOUT TIN
Methods for determination of magnesium
Tinless bronze.
Methods for determination of magnesium
AXTU 1709
Date of introduction 1989−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. INTRODUCED FOR THE FIRST TIME
4. The standard fully complies ST SEV 1543−79
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced | Section number, paragraph |
| GOST 804−93 |
2.2, 3.2 |
| GOST 3118−77 |
3.2 |
| GOST 4328−77 |
3.2 |
| GOST 4461−77 |
2.2, 3.2 |
| GOST 5457−75 |
2.2 |
| GOST 8864−71 |
3.2 |
| GOST 9293−74 |
2.2 |
| GOST 11293−89 |
3.2 |
| GOST 18175−78 |
Chapeau |
| GOST 25086−87 |
1.1 |
6. Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)
7. REISSUE
This standard establishes the atomic absorption and photometric methods for the determination of magnesium (with a mass fraction of magnesium of from 0.05% to 0.6%) in the tin bronze according to GOST 18175.
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 25086 with the addition of a GOST 15027.1 in sect.1.
2. ATOMIC ABSORPTION METHOD
2.1. The essence of the method
The method is based on measuring the absorption of light by atoms of magnesium, formed when the introduction of the analyzed solution in the flame acetylene-air or acetylene-nitrous oxide.
2.2. Apparatus, reagents and solutions
Atomic absorption spectrometer with a radiation source for magnesium.
Nitric acid according to GOST 4461, diluted 1:1 and 1:10.
Acetylene according to GOST 5457.
Nitrous oxide according to GOST 9293.
Magnesium GOST 804.
Standard solution of magnesium: to 0.1 g of magnesium (taken from a piece previously protravnogo in nitric acid (1:10), washed and dried using filter paper) is dissolved in 10 cmof nitric acid (1:1). The solution was cooled, transferred to a measuring flask with volume capacity of 1000 cm
and top up with water to the mark.
1 cmof the solution contains 0.0001 g of magnesium.
Lanthanum nitrate.
Strontium chloride.
Solutions of lanthanum or strontium: 0.31 g of lanthanum nitrate or 0.30 g of strontium chloride dissolved in 20 cmof water, transferred to a volumetric flask with a capacity of 100 cm
and top up with water to the mark.
1 cmof the solution contains 0.001 g of lanthanum or strontium.
2.3. Analysis
2.3.1. A portion of sample weighing 0.1 g was dissolved with heating in 10 cmof nitric acid (1:1). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
and top up with water to the mark. Measured by atomic absorption at a wavelength of RUB 285.2 nm in the flame acetylene-air or in the flame of acetylene-nitrous oxide parallel to the calibration solutions.
2.3.2. Construction of calibration curve
Eight volumetric flasks with a capacity of 100 cmplaced 0; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 and 6.0 cm
to the standard solution of magnesium, added to 10 cm
of nitric acid (1:1) (in the analysis of alloys containing aluminum, add 1.5 cm
of a solution of lanthanum or strontium) and topped to the mark with water. Measure the atomic absorption of magnesium, as mentioned in paragraph
2.4. Processing of the results
2.4.1. Mass fraction of magnesium (a) in percent is calculated by the formula
where the magnesium concentration was found in the calibration schedule, g/cm
;
— concentration of magnesium in solution of the blank experience, found by calibration schedule, g/cm
;
— the volume of the sample solution, cm
;
— weight of sample, g
.
2.4.2. The absolute discrepancies in the results of parallel measurements (the rate of convergence) must not exceed the permissible values given in the table.
| Mass fraction of magnesium, % |
|
|
| From 0.05 to 0.10 « |
0,008 | 0,02 |
| SV. Of 0.10 «to 0.30 « |
0,015 | 0,04 |
| «Of 0.30» to 0.60 « |
0,03 | 0,07 |
2.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (a measure of reproducibility) shall not exceed the values given in the table.
2.4.4. Control of accuracy of analysis results
Control of accuracy of analysis results is carried out by additives in accordance with GOST 25086.
2.4.5. Atomic absorption method is used with differences in the evaluation of the quality of tin-bronze.
3. PHOTOMETRIC METHOD
3.1. The essence of the method
The method is based on the formation of magnesium in an alkaline medium with titanium yellow or phenazo compounds red-violet and measuring the optical density of the colored solution.
3.2. Apparatus, reagents and solutions
Spectrophotometer or photoelectrocolorimeter.
Nitric acid according to GOST 4461.
Hydrochloric acid according to GOST 3118, diluted 1:1 and 1:10.
Titanium yellow, a solution of 0.5 g/cm.
Sodium hydroxide according to GOST 4328, solution 200 g/land 2 mol/DM
.
Sodium diethyldithiocarbamate according to GOST 8864, a solution of 200 g/DM.
Gelatin GOST 11293, solution 5 g/DM.
Phenazo, a solution of 0.05 g/DM2 mol/DM
solution of sodium hydroxide.
Magnesium GOST 804.
Standard solutions of magnesium:
solution a: 0.5 g of magnesium (pre-protravnogo in hydrochloric acid (1:10), washed and dried using filter paper) is dissolved in 20 cmof hydrochloric acid (1:1). The solution is transferred into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.0005 g of magnesium;
solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
1 cmof solution B contains 0,00005 g
magnesium.
3.3. Analysis
3.3.1. The weight of bronze weighing 0.5 g were placed in a glass with a capacity of 100−150 cm, add 20 cm
of hydrochloric acid (1:1) and dissolved by adding dropwise nitric acid. After dissolution, the cooled solution is transferred to a volumetric flask with a capacity of 250 cm
, neutralized with sodium hydroxide solution (200 g/cm
) on a flat piece of paper «Congo» to slightly acid reaction.
To the solution was added 30 cmof a solution of sodium diethyldithiocarbamate, stirred, topped up to the mark with water, mix and leave for 2 hours for sedimentation of the precipitate. The supernatant solution was filtered in a dry conical flask using dry thick and dry the filter funnel, the first portion of the filtrate (15−20 cm
) drop. Select aliquot part of the solution — 50 cm
(at a mass fraction of from 0.05% to 0.2%) or 20 cm
(with mass fraction of magnesium of more than 0.2%) in a volumetric flask with a capacity of 100 cm
, add 10 or 40 cm
of water 5 cm
of the gelatin solution, 10 cm
of the solution, pinazo or 0.5 cm
of a solution of Titan yellow, 20 cm
of sodium hydroxide solution, made up to the mark with water and mix thoroughly. Optical density of the solution is measured on a photoelectrocolorimeter or (spectrophotometer at 545 nm) with a yellow-green filter
=530 nm) in a cell length of 5 cm
. A solution of comparison, using the blank solution experience conducted through the Ho
d analysis.
3.3.2. Construction of calibration curve
In a volumetric flask with a capacity of 100 cmis placed 0; 1,0; 2,0; 3,0; 4,0 and 5,0 cm
standard solution B magnesium, added 40 cm
of water and further analysis are as indicated in claim
3.4. Processing of the results
3.4.1. Mass fraction of magnesium (a) in percent is calculated by the formula
where is the mass of magnesium was found in the calibration schedule g;
the weight of bronze, suitable aliquote part of the solution,
3.4.2. The absolute discrepancies in the results of parallel measurements (the rate of convergence) must not exceed the permissible values given in the table.
3.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (a measure of reproducibility) shall not exceed the values given in the table.
3.4.4. Control of accuracy of analysis results
Control the accuracy of the results of the analysis of magnesium is carried out by additives or by comparison of the results obtained photometric and atomic absorption methods in accordance with GOST 25086.
