GOST 16412.7-91
GOST 16412.7−91 iron Powder. Methods for determination of carbon
GOST 16412.7−91
Group B59
STATE STANDARD OF THE USSR
IRON POWDER
Methods for determination of carbon
Iron powder.
Methods for the determination of carbon
AXTU 0809
Date of introduction 1992−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Academy of Sciences of the Ukrainian SSR
DEVELOPERS
V. N. Klimenko, PhD. tech. Sciences; A. E. kushchevsky, PhD. chem. Sciences; V. A. Dubok, PhD. chem. Sciences (head of subject); V. I. Kornilov, candidate. chem. Sciences; V. V. Garbuz, PhD. chem. Sciences; L. D. Bernatsky
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from
3. REPLACE GOST 16412.7−80
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced | Paragraph number section |
| GOST 4107−78 | 2.3.1 |
| GOST 4204−77 | 2.2.1; 2.3.1 |
| GOST 4233−77 | 2.2.1; 2.3.1 |
| GOST 4470−79 | 3.2 |
| GOST 5583−78 | 2.2.1; 2.3.1; 3.2 |
| GOST 9147−80 | 2.2.1; 2.3.1; 3.2 |
| GOST 20490−75 | 2.2.1; 2.3.1 |
| GOST 22536.1−88 | 2.1 |
| GOST 28473−90 | Sec. 1 |
This standard sets by a gas-volume (in mass percentage, carbon between 0.01% and above) and coulometric (with the mass fraction of carbon from 0.002% and above) methods for the determination of the carbohydrate in the iron powder.
1. GENERAL REQUIREMENTS
General requirements for methods of analysis GOST 28473.
2. BY A GAS-VOLUME METHOD FOR DETERMINATION OF CARBON
2.1. The essence of the method
The method is based on the combustion of a sample of iron powder in a current of oxygen at a temperature of 1250−1300 °C with subsequent absorption of that carbon dioxide with a solution of potassium hydroxide (sodium).
The carbon content is determined by the difference between the initial volume and amount of gas obtained after the absorption of carbon dioxide with a solution of potassium hydroxide (sodium).
2.2. Determination of carbon (over 0.05%) with the use of audiometry scale up to 1.5% carbon
2.2.1. Apparatus, reagents and solutions
Setup for determination of carbon, shown in the drawing, consists of an oxygen cylinder equipped with pressure reducing valve and pressure gauge for starting and regulating the current of oxygen is 2; the absorption flask 3 containing a solution of potassium permanganate with a mass fraction of 2% solution of potassium hydroxide with a mass fraction of 20%; a U-shaped tube 4, which in the first half (in the direction of oxygen) soda lime and the second calcium chloride; tap to regulate the flow of purified oxygen 5; mullite refractory-silica tube 6 an inner diameter, determined by the diameter of the used gate and the size of the boat. The ends of the tube protruding from the furnace, must be at least 250 mm. Tube before use, should be burnt along the entire length at a temperature of 1250−1300 °C in flowing oxygen; the horizontal tubular furnace 7 with a carbide-silicon heaters providing heated to 1250−1300 °C, thermostat 8, which maintain constant temperature furnace; voltage regulator 9 (allowed to use other types of kilns that provides the required temperature); two-way tap 10; dust collector 11; 12 filtroperlite filled with manganese dioxide or peroxide granules — for cleaning the products of combustion from the sulfur dioxide; gas analyzer Gow-1, including refrigerator coil 13 for cooling coming from the furnace gas mixture (CO+O
); 14-way tap connecting audiometer with a refrigerator, an absorption vessel and the atmosphere; the single-acting valve 15, connecting audiometer with the atmosphere; audiometry 16, which represents a narrow cylindrical vessel with an extension at the top. Audiometr has double walls, the space between which is filled with water to maintain a constant temperature. At the top of audiometry fortified thermometer 17 for measuring the gas temperature; the narrow part of audiometer has a scale for measuring the volume of gas corresponding to the percentage of carbon in the sample. The tick marks indicate the percentage carbon content of the test specimen. Audiometry graduated to measure the volume of gas at a temperature of 16 or 20 °C and atmospheric pressure 0,101 MPa (760 mm Hg. St). For other conditions introduce a correction for temperature and atmospheric pressure according to the tables of annexes 1 and 2 to GOST 22536.1. Vessel for the absorption of carbon dioxide 18, is filled with a solution of potassium hydroxide (sodium) with a mass fraction of 40% and provided with a slide valve floats, which close the sink when it is filled with alkali solution, eliminating the possibility of contact with the alkali solution from the absorber audiometer. The absorption vessel is connected to the cylindrical vessels, which during the filling of the absorption vessel, a gas mixture is pumped a solution of potassium hydroxide (sodium); equalization flask 19 for transferring the gas mixture from audiometry in the absorption vessel is filled with packing liquid.
Barometer.
Muffle furnace type SNOL according to normative-technical documentation or any other type providing a heating temperature not lower than 900 °C.
The hook with which the boat is introduced into the tube for flaring and extracted from it, is made of heat-resistant low-carbon wire with a diameter of 3−5 mm and a length of 500−600 mm.
Boat porcelain with GOST 9147, calcined at temperatures below 900 °C for 6 h or at operating temperature in flowing oxygen for 2−3 min.
Boats stored in the desiccator, socket covers which do not cover the lubricant.
Oxygen gas according to GOST 5583.
Gas analyzer Gow-1.
The lime soda.
The calcium chloride.
Sulfuric acid according to GOST 4204.
Potassium permanganate according to GOST 20490, solution with a mass fraction of 4% solution of potassium hydroxide with a mass fraction of 40%.
Methyl orange (paradimethylaminobenzaldehyde solitarily sodium), an aqueous solution with a mass fraction of 0.1%.
Sodium chloride according to GOST 4233.
Potassium hydroxide according to GOST 24363, a solution with a mass fraction of 40%.
Packing liquid: sulfuric acid solution with a mass fraction of 2% or solution of sodium chloride with a mass fraction of 25%, acidified with 2−3 drops of sulfuric acid. Both solutions contain 2−3 drops of methyl orange solution.
2.2.2. Preparation for assay
Before commencing work the installing drive. The ends of the porcelain tubes closed with rubber stoppers embedded with glass tubes or shutter. A porcelain tube, all connections and taps installation check for leaks. For this purpose one end of the porcelain tube connecting a rubber hose through absorption banks to clean oxygen with a balloon containing oxygen, a second end with the device go-1.
The absorption vessel is filled with a solution of potassium hydroxide (sodium), and the surge flask are poured 450cmpacking liquid. After filling the surge flask with fresh liquid necessary to make a few preliminary burning of the sample began to saturate the liquid with carbon dioxide to obtain stable results for the determination of carbon in the standard sample. Then double tap 14 put in the position that divide the burette, absorption vessel, and a refrigerator among themselves. Opening the valve 15, which connects audiometer with the atmosphere, raise the levelling bottle, eudiometer is filled with fluid. After filling audiometry liquid valve 15 is closed, the crane 14 is put in a situation in which audiometr connects the absorption vessel.
After equalizing the bottle, allow the liquid to drain out of audiometer. The level of alkaline solution in the absorption vessel rises, lifting the float.
As soon as the float will close the exit from the absorption vessel, the crane 14 and the single-acting valve 15 is put in a position in which audiometer is connected with the atmosphere. Raising the levelling bottle, fill eudiometer liquid to the upper limit. After filling audiometry liquid valve 15, connecting it with the atmosphere, closed, and levelling bottle is lowered. If the unit is sealed, the absorption vessel is filled with alkali, and the liquid level in audiometry remains unchanged. If the fluid in audiometry is omitted, then the unit is leaking. It should be disassembled to check the valves, lubricate them with vaseline and check again for leaks.
Before starting work, check correctness of installation of a zero scale division. For this, the crane 14 is put in position, severing all parts of the system. Open the valve 15, which connects audiometer with the atmosphere, the surge put the bottle on the bottom bracket, and give the packing liquid to drain. The level of the sealing liquid in the bottom of audiometry and the surge flask are installed at the same height. The movable scale is moved so that its zero division coincided with the lower level of the packing liquid in eudiometer. Not closing the valve 15, raising the surge bottle on the upper cradle, while eudiometer is filled with packing liquid. The valve 15 is closed.
2.2.3. Analysis
A suspension of iron powder weighing 1 g is placed in a porcelain boat. Audiometer needs to be filled with liquid; the absorption vessel must be filled with a solution of potassium hydroxide (sodium), and the valve 15 must be closed.
The boat with the charge placed in the most heated portion of the porcelain tube, the end of which is closed immediately with a rubber stopper or stopper. After 10−20 s (time required to ensure that the boat and the hitch took the temperature of the furnace) is passed a current of oxygen at a speed of 0.33·10m
/s (200 cm
/min). With the help of a crane 14 for some time, disconnect the refrigerator 13 and audiometr 16 to start the combustion took place under a certain pressure of oxygen, then the crane 14 is put in a position in which the gas mixture enters audiometer. The surge put the bottle on the stand, in the upper part of the detector. In this position, the surge bottle leave until then, until the mixture to displace the liquid from the upper wide part of audiometry. Then the surge bottle is put on the stand in the down position and leave as long as the fluid level in audiometry falls almost to zero scale division; immediately cease the supply of oxygen, choking off the faucet 14. Simultaneously stop the flow of oxygen from a cylinder. Then disconnect the plug with the porcelain tube and the tube is removed from the boat. The fluid level in audiometry set at the zero division of the scale, the level in audiometry should be on the same line as the liquid level in the surge bottle. Then, changing the position of the valve 14, the gas mixture (CO
+O
) from audiometer transferred to the absorber 18. From the absorber 18, the remaining gas is again pumped into the burette 16; this operation is repeated. Then set the tap 14 in a position of complete separation audiometry absorbent and measure the volume of gas in eudiometry. To this end, the liquid in the surge flask and eudiometer set on one level and provide exposure 20, to drain the liquid remaining on the walls of audiometry. Call meniscus and scale audiometry determine the amount of carbon dioxide absorbed is proportional to the carbon content in the analyzed material. Note the temperature of the gas in the burette and the atmospheric pressure on the barometer. Then release the gas from the burette and prepare the apparatus for subsequent incineration.
2.2.4. Processing of the results
2.2.4.1. After completion of the analysis tables 1 and 2 GOST 22536.1 find a correction for temperature and pressure at which the was measured of carbon.
Mass fraction of carbon () in percent is calculated by the formula
where — indications of the scale of audiometry after the absorption of carbon dioxide from the combustion of a sample of iron powder, %;
— indications of the scale of audiometry after absorption of carbon dioxide produced when conducting the reference experiment, %;
— the weight of the portion at which the calibrated device, g;
— correction factor for temperature and pressure;
— weight of iron powder,
2.2.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.
| Mass fraction of carbon, % | Allowable absolute differences, % |
| From 0.002 to 0.005 incl. | 0,001 |
| SV. 0,005 «0,01 « | 0,002 |
| «0,01» 0,02 « | 0,004 |
| «0,02» 0,05 « | 0,007 |
| «0,05» 0,10 « | 0,010 |
| «To 0.10» to 0.20 « | 0,015 |
| «To 0.20» and 0.40 « | 0,020 |
2.3. Determination of carbon (0,01−0,2%) with the use of audiometry scale to 0.25% carbon
2.3.1. Apparatus, reagents and solutions
Equipment, reagents, solutions and diagram of the installation according to claim 2.2.1 with additions.
Electric dubtronica.
Tube mullite refractory-silica, with a length of 750 mm, the inner diameter defined by the diameter of the used gate and the size of the boat. One of them is used for purification of oxygen impurities containing carbon, the other for the combustion of batches.
For cleaning of gases from the first tube, are the two washings of the flask: with a solution of barium hydroxide with a mass fraction of 5% for the absorption of carbon dioxide contained in the technical oxygen, with concentrated sulfuric acid to absorb moisture.
Audiometer with scale 0,25% of carbon.
Equalization flask with side tube.
Barium hydroxide according to GOST 4107, a solution with a mass fraction of 5%.
2.3.2. Training equipment
Before commencing work the installing drive. The ends of the porcelain tubes closed with rubber stoppers embedded with glass tubes or shutter. One end of the porcelain tube, intended for the purification of oxygen impurities containing carbon, connect a rubber hose through cleaning bottles with the oxygen tank, the other end through the flask for purification of gases connected to one end of the porcelain tube that is designed to burn batches. The second end of the tube to burn through a rubber hose connected to the gas analyzer Gow-1. After that, the installation check for leaks at the operating temperature according to claim
2.3.3. Analysis
A suspension of iron powder weighing 1 g is placed in a porcelain boat and carry out the analysis according to claim
2.3.4. Processing of the results
2.3.4.1. Processing of the results produced as specified in claim
2.3.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.
3. COULOMETRIC METHOD FOR DETERMINING CARBON
3.1. The essence of the method
The method is based on the combustion of a sample of iron powder in a current of oxygen at a temperature of 1300−1350 °C. the Resulting carbon dioxide is absorbed by the solution and causes an increase of acidity and the change in the EMF indicator system pH meter. The quantity of electricity necessary to achieve the initial pH of the absorbing solution and is proportional to the concentration of carbon in the sample, fixed colorometer integrator current, showing directly the amount of carbon in percent.
3.2. Equipment and reagents
Coulometric installing an 7529, 7560 EN with all accessories or any other type, providing the necessary accuracy of the analysis.
Horizontal tube furnace of any type, providing heating to a temperature of 1350 °C.
Oxygen GOST 5583.
Tube mullite refractory-silica with an inner diameter defined by the diameter of the used gate and the size of the boat.
Muffle furnace type SNOL according to normative-technical documentation or any other type providing a heating temperature not lower than 900 °C.
Boat porcelain with GOST 9147, calcined at temperatures below 900 °C for 6 h or at operating temperature in flowing oxygen for 2−3 min.
Boats stored in the desiccator, socket covers which do not cover the lubricant. In the determination of carbon less than 0.05% boats should be svezheprigotovlennym.
Manganese dioxide according to GOST 4470.
Gidroperit according to normative-technical documentation.
Absorption and support the solutions prepared in accordance with the type of the used coulometric setup.
3.3. Analysis
Device prepare to work in accordance with the instructions.
The weight of iron powder with a mass of 0.5−1.0 g is transferred into a porcelain boat; the boat is placed in the most heated portion of the porcelain tube for the combustion, which quickly close the shutter. Press the «reset» button and set the display indication the digital display to «zero», burn iron powder at a temperature of 1250−1300 °C. After complete combustion of the iron powder, what is judged by the completion of the titration, record the result of the analysis by reading the digital display, open the stopper and remove the boat.
3.4. Processing of the results
3.4.1. Mass fraction of carbon is determined by the digital display of the analyzer minus the result of the reference experiment.
3.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.
