GOST 22720.3-77
GOST 22720.3−77 Rare metals and alloys on their basis. Method for the determination of carbon (Change No. 1)
GOST 22720.3−77
Group B59
STATE STANDARD OF THE USSR
RARE METALS AND ALLOYS ON THEIR BASIS
Method for determination of carbon
Rare metals and their alloys. Method for the determination of carbon
AXTU 1709*
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* Introduced advanced Edit. N 1.
Date of introduction 1979−01−01
The decision of the State standards Committee of the Council of Ministers of the USSR from September 29, 1977 N 2341 introduction installed from 01.01.79
Proven in 1983 by the Decree of Gosstandart from 27.07.83 3511 N validity extended to 01.01.89*
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* Expiration removed by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS No. 5/6, 1993). — Note the manufacturer’s database.
REPRINTING. November 1983
The Change N 1, approved and put into effect by the Decree of the USSR State Committee for standards from
Change No. 1 made by the manufacturer of the database in the text IUS N 5, 1988
This standard applies to niobium, tantalum, tungsten, zirconium, hafnium, vanadium, rare earth metals, their alloys and specifies a method for the burning of the samples in flowing oxygen with coulometric completion (in the determination of the mass fraction of carbon from 0.005 to 0.2%) and by a gas-volume termination (in determining the mass fraction of carbon from 0.02% and above) for the determination of carbon.
The method is based on the combustion of a test sample in a current of oxygen. At the same time contained in the sample carbon is oxidized to carbon dioxide, the amount of which is determined with coulometric or by a gas-volume method. In the case of coulometric end measure the amount of electricity expended in the generation of a reagent that reacts with the carbon dioxide. By a gas-volume end based on the absorption of carbon dioxide by a solution of potassium hydroxide and establishment (by difference) of its volume through gas-measuring burette-audiometry.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 22720.0−77.
2. APPARATUS, REAGENTS AND SOLUTIONS
Installation with a coulometric sensor for the determination of carbon (Fig.1).
1 — absorption solution; 2 — electrolytic cell; 3 — electrode; 4 — glass electrode; 5 — tubular furnace; 6 — pH-meter; 7 — regulator; 8 — DC power supply; 9 — cathode; 10 — integrator; 11 — anode; 12 — semi-permeable membrane; 13 — subsidiary solution
Damn.1
Installation for determination of carbon by a gas-volume ending for the determination of carbon is depicted in hell.2. The installation consists of the following elements: oxygen cylinder with reducer 1; a gas washing bottle 2 with a 30% solution of potassium hydroxide containing 5% potassium permanganate; 3 flasks with concentrated sulphuric acid; U-shaped tube 4 with soda lime and calcium chloride; a horizontal electric tubular furnace 6 with a length of about 250 mm silovymi terminals that provide heating to 1300 °C, equipped with a thermostat 8 and thermocouple (platinum-rhodium) with galvanometer 7; a porcelain tube 5 with a diameter of 18−20 mm. tube Length depends on the size of the furnace, the ends should protrude from the furnace is not less than 170 mm on each side, before use, a tube is calcined along the entire length at 1000−1300 °C; U-shaped tube 9, is filled with glass wool to trap solid particles entrained out of the tube by a current of oxygen; the gas analyzer Gow-1 according to GOST 10713−75 consisting of a coil of the refrigerator 10 for cooling incoming gas-measuring burette gas mixture (CO+O
); three-way tap 11, through which the gas mixture from the furnace and the refrigerator enters the measuring burette; gas measuring burettes-microangiopathy 13 with a scale from 0 to 0.25% carbon; thermometer 12 measuring the temperature of the gas; absorber 14 with automatic shutter (float), filled with 40%-s ' solution of caustic potash, which should be changed every two to three weeks; the surge flask 15 for pumping the gas mixture from the burette into the sink. The surge bottle is filled with 16−17%-s ' solution of copper sulphate with a density of 1.2 g/cm
.
Damn.2
Express-analyzer on carbon an-7529, an-7560 or another brand.
Potassium chloride according to GOST 4234−77.
Potassium ferrocyanide 3-water according to GOST 4207−75.
Sodium tetraborate 10-water according to GOST 4199−76.
Boric acid according to GOST 9656−75.
Strontium chloride 6-water according to GOST 4140−74.
Copper oxide powder according to GOST 16539−79.
Askari.
The aneroid.
Oxygen gaseous technical GOST 5583−78.
A porcelain boat with a length of 70 mm, a width of 10 mm and a height of 10 mm, calcined in flowing oxygen at 1000 °C.
The hook of heat-resistant steel with a length of 700 mm.
Calcium oxide according to GOST 8677−76, calcined at 1000 °C and tested for carbon content.
The ethyl ether.
Rectified ethyl alcohol GOST 18300−87.
Silicon dioxide according to GOST 9428−73, calcined at 1000 °C.
(Changed edition, Rev. N 1).
3. PREPARATION FOR ASSAY
3.1. Preparation coulometric analyzer
Incinerator samples heated to 1200 °C, passing a current of oxygen; and include warm up the analyzer for carbon for 30−40 minutes to Stabilize all parts of the installation.
The test analyzer calibration on the carbon carried out using a standard sample, the carbon content similar to the analyzed samples. After testing the installation according to the standard model begin to be burned of the analyzed samples.
3.2. Training by a gas-volume analyzer
Gather the installation according to the scheme (see the devil.2). After reaching a furnace temperature of 1100−1200 °C tightness check of the entire system. Set the speed of the oxygen bubbles in 3−5 1. the Correct operation of the entire installation is determined according to the analysis of a standard sample. For Example, S. O. No. 304. Niobium or S. O. N 284. Steel.
For one analysis, we take three samples in the form of powder or shavings, the weight of which, depending on the analyzed material are shown in table.1.
Table 1
| The analyzed material |
Temperature in furnace, °C |
The mass of sample, g |
Marshes |
| Niobium |
1150−1250 |
0,5 |
The hitch boat cover with uniform layer of copper oxide in the ratio 1:2 |
| Alloys on its basis |
1200−1300 |
0,5 |
|
| Tantalum and base alloys |
1200 |
0,5 |
Without floodplains |
| Rare earth metals and alloys on their basis |
1000 |
0,5 |
To prevent the outbreak of a portion covered with a thin layer of silicon dioxide in a ratio of 1:1 |
| Vanadium |
1000 |
0,5 |
Without floodplains |
| Tungsten |
1100 |
0,5 |
The same |
| Molybdenum |
1100 |
0,5 |
The hitch boat cover with uniform layer of calcium oxide in a ratio of 1:5, which connects to the volatile trioxide of molybdenum and forms a nonvolatile compound |
| Zirconium, hafnium |
1100 |
0,5 |
In connection with high eksterminacja reactions weighed in the boat covered with a thin layer of silicon dioxide in the ratio of 1:1 |
3.1, 3.2. (Changed edition, Rev. N 1).
4. ANALYSIS
A portion of the analyte, washed with ethyl ether and dried, placed in a porcelain boat and, if necessary, cover with an even layer of flux in accordance with the requirements specified in table.1.
4.1. Analysis on installation with coulometric analyzer
The boat with the charge placed in the most heated portion of the porcelain tube to burn and close the shutter of the porcelain tube. As the absorption of carbon dioxide with a solution of the electrolytic cell is automatically readout on the digital display of the analyzer on carbon. The analysis is considered complete in the case when the digital indicators do not change for 1 min or changed by no more than the correction in the reference experiment, which should not exceed 3 imp. per minute. In parallel with the analysis of the sample spend control experience. The carbon content is recorded by reading the digital display taking into account the value of the amendment in the reference experiment.
(Changed edition, Rev. N 1).
4.2. Conducting analysis on the installation by a gas-volume analyzer
A boat with suspension administered with a hook (from oxygen supply) in the heated portion of the porcelain tube, the end of which is quickly closed with a rubber stopper. The other end of the tube with a rubber hose connected to the unit GOU-1 (see the devil.2). In the tube pass a current of oxygen at a rate of 3−5 bubbles per second. Further analysis is performed, as specified in GOST 2604.1−77.
5. PROCESSING OF THE RESULTS
5.1. When you define a coulometric carbon analyzer an-160 an-7529, an-7560 the result is given automatically in percentage and is fixed on the light Board.
In determining carbon by a gas-volume analyzer Gow-1 mass fraction of carbon () in percent is calculated by the formula
where — indications of the scale of audiometry;
— correction factor for atmospheric pressure and temperature, which is found in the tables attached to the device;
— the mass of sample, g.
(Changed edition, Rev. N 1).
5.2. Allowable absolute differences between the results of two parallel measurements with a probability of 0.95 should not exceed the values given in table.2. For intermediate values of mass fraction of carbon permissible divergence is determined by linear interpolation.
Table 2
| The mass fraction of carbon, % |
Allowable absolute differences, % |
5·10 |
3·10 |
1·10 |
5·10 |
5·10 |
1,5·10 |
1.10 |
2·10 |
2·10 |
3·10 |
| 2,0 |
3·10 |
