GOST 2604.1-77
GOST 2604.1−77 alloy Cast iron. Methods for determination of carbon (with Amendments No. 1, 2)
GOST 2604.1−77
Group B09
INTERSTATE STANDARD
ALLOY CAST IRON
Methods for determination of carbon
Alloy cast iron. Methods for determinations of carbon
ISS 77.080.10
AXTU 0809
Date of reference 1978−01−01
The decision of the State standards Committee of the USSR Council of Ministers dated 22 March 1977, N 680 date of introduction is established 01.01.78
Limitation of actions taken by Protocol No. 2−92 of the Interstate Council for standardization, Metrology and certification (ICS 2−93)
REPLACE GOST 2604−44 in sect.1 in determining the mass fraction of carbon
EDITION with Amendments No. 1, 2 approved in December 1982, June 1987 (IUS 3−83, 9−87).
This standard applies to alloy cast iron and sets by a gas-volume method for the determination of total carbon (2.5 to 4.5%), coulometric method for the determination of total carbon (2.5 to 5%), by a gas-volume and coulometric methods for the determination of unbound carbon (graphite) (from 0.1 to 3.0%).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 28473−90.
2. BY A GAS-VOLUME METHOD OF DETERMINING THE MASS FRACTION OF TOTAL CARBON
2.1.The essence of the method
The method is based on the combustion of a sample of cast iron in a current of oxygen at 1300−1350 °C followed by absorption of the formed carbon dioxide with a solution of potassium hydroxide. Mass fraction of carbon is determined by difference between the initial volume of gas and volume of gases obtained after the absorption of carbon dioxide by potassium hydroxide solution.
2.2. Apparatus, reagents and solutions
The installation for determining the mass fraction of carbon (see drawing).
The installation for determining the mass fraction of carbon consists of the following elements: oxygen cylinder 7, is provided with a reducing valve, aspirator or Gasometer 2 as a buffer; two-way valves 3; a gas washing bottle 4 containing permanganate of potassium solution of potassium hydroxide, a gas washing bottle 5 containing sulfuric acid (with dry cleaning method rinse the flask 4 and 5 are replaced by U-shaped tube filled with oscarito); gas meter or a rheometer 6; horizontal tubular furnace 7 water-cooled, providing temperature heating (1350±20) °C; thermocouple 9 with the thermostat or gauge to control furnace transformer 8 to regulate the voltage; unglazed porcelain gas-tight tube 10 with a length of 750 mm with an inner diameter of 20−22 mm. the ends of the tube should protrude out of the oven not less than 200 mm; unglazed porcelain or refractory pumps 11 N 1 or N 2 according to GOST 9147−80; filter 12 for absorption by solid oxides, entrained by a current of oxygen in the combustion process of cast iron. The filter is a glass spherical or cylindrical vessel filled with glass wool; a gas washing bottle 13 to absorb sulfur dioxide containing solution of potassium dichromate in sulphuric acid (in the dry method of cleaning rinsing flask 13 is replaced by an absorber-filled gidroperita) connected to the device go-1, consisting of a coil of a refrigerator 14 for cooling the gas mixture (CO+O
) coming from the furnace; two-way valve 15, through which the gas mixture from the furnace and the refrigerator enters the measuring burette; the two-way valve 16, linking the measuring burette with the vessel for absorbing gas; gas-measuring burette 17. In the narrow part of the burette is attached to a movable scale for measuring the volume of gas corresponding to the volume fraction of the carbon in the sample in percent. The scale corresponds only to the burette, to which it is attached; transferring it to another burette invalid.
Scale division correspond directly to the percentage mass fraction of carbon in 1 g of the test substance. Burettes are usually calibrated at a temperature of 16 or 20 °C and atmospheric pressure 7448 PA (760 mm Hg. article), so for different conditions introduce a correction for temperature and atmospheric pressure in the appropriate table attached to the gas analyzer Gow-1; vessel for the absorption of carbon dioxide 18, is filled with caustic potash solution; the surge flask 19, the three-way tap 20; a rubber cylinder 21 for pumping the gas mixture from the burette into the sink.
Barometer.
The hook with which the boat was placed in a tube and extracted from it, is made of heat-resistant low-carbon wire of square or circular cross-section with a diameter of 3−5 mm, length 500−600 mm.
Potassium permanganate according to GOST 20490−75, a solution of 0.04 g/cmin a solution of potassium hydroxide (GOST 24363−80), 0.4 g/cm
.
Sulfuric acid according to GOST 4204−77.
Potassium hydroxide according to GOST 24363−80, a solution of 0.5 g/cm.
Sodium chloride according to GOST 4233−77, a solution of 0.25 g/cm, to which is added 5−6 drops of sulfuric acid and a few drops of solution of methyl orange.
Methyl orange, solution 0.001 g/cm.
Potassium dichromate according to GOST 4220−75, a solution of 0.15 g/cmin sulfuric acid.
Askari.
Gidroperit medical.
Marshes: iron, copper, copper oxide, tin of high purity lead. Mass fraction of carbon in wetlands should not exceed the permissible differences for the corresponding values of the mass fraction of carbon in the table.
(Changed edition, Rev. N 1, 2
).
2.3. Preparation for assay
Collect the gas analyzer Gow-1. Use the burette with a scale from 0 to 4.5%.
Glass parts devices connect tight butt joint with the segments of the rubber tubes to the combustion products were in contact with the rubber tubes. Before starting, heat the oven to the desired temperature.
Porcelain up close with the two sides well-fitting rubber stoppers. In hole insert glass tubes or brass tubes.
In order to avoid burning the rubber stoppers at the gas outlet of the furnace, the inner end surface of this tube is closed with asbestos or brass strip, put on the end of a glass or brass tube.
Porcelain tubes and pumps calcined in flowing oxygen at operating temperature. Calcined boats stored in a desiccator. Socket cover of the dryer must not be covered by lubricating substance.
Porcelain tube, all connections and taps installation check for leaks. If the unit is not sealed and upon inspection of the individual joints are not discovered the leak, the installation should be disassembled, thoroughly clean all the taps with a soft cloth, lubricate with vaseline and repeat the check.
Measuring burette 17 must be kept clean, periodically washing it with warm chromic mixture.
Glass wool in the bowl 12 should be changed as needed.
Before the analysis, a burn several samples of cast iron and flow gases through a gas measuring burette and a levelling bottle filled with a solution of sodium chloride to saturate the carbon dioxide solution in the surge bottle.
To check the correct operation of the installation burn 2−3 sample standard sample of cast iron in the presence of a flux as specified in claim 2.4.
Likewise conduct control experience in the carbon content of the flux.
2.4. Analysis
The weight of cast iron weighing 1 g is placed in a porcelain boat, top covered with flux in the ratio 1:1 and injected her with a hook in the oven, preheated to a temperature of 1300−1350 °C. the Boat set in the most heated part of the porcelain tube for the combustion, which quickly closed with a rubber stopper or stopper.
After a minute open the valves 3, is passed a current of oxygen at a speed of 0.2−0.4 DM/min the sample is burned under slight pressure (with closed valve 15). Then valve 15 is put in a position in which the gas mixture enters the gas measuring burette. As soon as the narrow lower part of the burette is filled with a gas and the fluid level reaches the zero division of the scale, crane block 15.
After that turn off current of oxygen, which close the pressure reducing valve and the valve 3 located in front of the furnace; disconnect the tube from the tube or open the shutter, remove the boat and after some cooling considering its contents. If the linkage isn’t fully burned, you should take a new sample and repeat the burning. Moving the surge flask 19 (with a corresponding position of the valve 20) along the burette, find the position at which the liquid levels in the burette and levelling the flask will be at the same height. At this level set the zero division of the movable scale.
When measuring the liquid level in the burette it is necessary to wait 15−20 seconds so that the liquid remaining on the walls of the burette, glass completely.
The gas mixture (CO+O
) from the burette 17 is transferred to the absorber 18, pumping the air in the surge bottle with a rubber cylinder 21 and making sure that the burette had no gas bubbles. From the absorber 18, the remaining gas is again pumped into the burette 17. This operation is repeated. Then set the valve 16 in a position of complete separation of the absorber and measured, like the first time, the volume of gas in the burette, recording the readings of the scale. Then follows a second gas extraction. With this purpose, connect the gas burette with the atmosphere and fill it with fluid.
By turning the valve 15 connects the burette with a fridge and produce a secondary combustion of the sample in the tube for 3 min. the Results obtained in both gas tot.
Measure the temperature of the gas in the burette and atmospheric pressure. Then release the gas from the burette and prepare the apparatus for the next combustion.
2.5. Processing of the results
2.5.1. After finishing the analysis according to the table supplied with the gas analyzer Gow-1, find the correction for the temperature and pressure conditions under which the analyses were carried out.
Mass fraction of carbon () in percent is calculated by the formula
where — scale gas-measuring burette, corresponding to the mass fraction of carbon, %;
— correction factor for temperature and atmospheric pressure, was found in the table annexed to the instrument;
— the weight of the portion,
(Changed edition, Rev. N 1, 2).
2.5.2. Permissible differences between results of the parallel definitions should not exceed 0.10%.
(Changed edition, Rev. N 2).
3. COULOMETRIC METHOD OF DETERMINING THE MASS FRACTION OF TOTAL CARBON
3.1.The essence of the method
The method is based on the combustion of a sample of cast iron in a tubular furnace in flowing oxygen at 1300−1350 °C. the Formed carbon dioxide is absorbed by the absorption solution, causing an increase in acidity, which in turn leads to a change in EMF indicator system pH meter. The quantity of electricity required to achieve a initial pH value, fixed by a special colorometer integrator current, showing directly the amount of carbon in percent.
3.2. Apparatus, reagents and solutions
Express-analyzer an-39. Allowed to use analyzers of other types.
Oxygen cylinder equipped with pressure-reducing valve for starting and regulating the current of oxygen.
A horizontal tubular furnace with water cooling, providing the temperature of 1300−1350 °C.
Unglazed porcelain tube is gas-tight with a length of 750 mm, an inner diameter of 20−22 mm, preheated on the entire length at a temperature of 1300−1350 °C.
The ends of the tube should protrude out of the oven at 200 mm.
Unglazed porcelain boat N 1 and N 2 according to GOST 9147−80 withstanding a temperature of 1300−1350 °C, preheated at the working temperature.
Calcined boats stored in a desiccator. Socket cover of the dryer must not be covered by lubricating substance.
The hook with which the boat was placed in a tube and extracted from it, is made of heat-resistant low-carbon wire of square or circular cross-section with a diameter of 3−5 mm, length 500−600 mm.
Askari.
Potassium chloride according to GOST 4234−77.
Strontium chloride according to GOST 4140−74.
Boric acid according to GOST 9656−75.
Potassium ferrous-sinergisty 3-water according to GOST 4207−75.
The absorption solution is prepared as follows: 100 g of potassium chloride, 100 g strontium chloride, 1 g of boric acid was placed in a flask and dissolved in 1 DMof water.
The auxiliary solution is prepared as follows: 100 g of potassium chloride, 100 g iron-sinergistom potassium 3-water and 1 g of boric acid was placed in a flask and dissolved in 1 DMof water.
Marshes: iron, copper, copper oxide, tin of high purity lead. Mass fraction of carbon in wetlands should not exceed the permissible differences for the corresponding values of the mass fraction of carbon in the table.
(Changed edition, Rev. N 1, 2).
3.3. Preparation for assay
Before analysis prepare the device for use.
Before the determination of carbon in iron is necessary to produce a burning two batches of a standard sample with a mass of 0.20 g with smoother. In a properly calibrated instrument, the readings of the digital indicator at the end of the analysis must correspond to the total mass fraction of carbon in the standard sample and the boat with the smoother. If the readings of the digital indicator does not correspond to the total mass fraction of carbon in the control sample and the standard sample, it is necessary to adjust the calibration of the instrument. After the calibration the device is ready for operation.
3.4. Analysis
A portion of the cast iron mass of 0.20 g evenly placed in a porcelain boat and covered with a flux in a ratio of 1:1. A boat with a hook placed in a porcelain tube, heated beforehand to temperature 1300−1350 °C, and set in the most heated part. The tube is immediately closed with shutter.
Set the display indication the digital display to zero, click reset.
After combustion of the sample of cast iron (the reading of the milliammeter corresponds to 0.2 mA, and the digital indicator does not exceed the level in the reference experiment), write down the result of the analysis, remove the boat and, after cooling, examine its contents. If the linkage isn’t fully burned, you should take a new sample of cast iron and repeat the burning.
Likewise conduct control experience in the carbon content of the flux.
3.3, 3.4. (Changed edition, Rev. N 1).
3.5. Processing of the results
3.5.1. Mass fraction of carbon () in percent is calculated by the formula
where is the indicator display digital display;
the weight of cast iron,
3.5.2. Permissible differences between results of the parallel definitions should not exceed 0.10%.
3.5.1,
4. BY A GAS-VOLUME AND COULOMETRIC METHODS FOR THE DETERMINATION OF THE MASS FRACTION OF UNBOUND CARBON
4.1.The essence of the method
The method is based on the fact that unbound carbon, as graphite does not dissolve in dilute nitric acid and remains as a precipitate, which was filtered, dried and combusted in flowing oxygen.
4.2. Apparatus, reagents and solutions
Apparatus — according to claim 2.2, with the following addition: the pipe for combustion in the place of heating to a temperature of 1000−1200 °C shall be fitted with a copper mesh that serves as a catalyst to ensure complete oxidation of unbound carbon to carbon dioxide.
Water jet pump or pump Komovskogo to create a vacuum during the filtration.
Asbestos for filtering.
Fibrous asbestos is cut into pieces with a length of about 10 mm and treated by boiling with hydrochloric acid by the GOST 3118−77 as long as new portions of the acid will not cease to be painted in yellow color, indicating the presence of iron.
Thereafter, the asbestos is washed from acid with hot water, dried and calcined in flowing oxygen at 1000−1200 °C.
You need to check the asbestos mass fraction of carbon, ogiga it in the oven in the same amount as in the test.
Sulfuric acid according to GOST 4204−77.
Nitric acid GOST 4461−77 diluted 1:1.
Hydrofluoric acid according to GOST 10484−78.
Diphenylamine solution: is prepared as follows: 1 g diphenylamine dissolved in 100 cmof sulphuric acid or at 100 cm
of phosphoric acid.
4.3. Analysis
The weight of cast iron weighing 1 g is placed in a beaker with a capacity of 200−250 cm, 25 cm pour
nitric acid, diluted 1:1, and immediately cover the watch glass. If the dissolution proceeds rapidly, the glass is immersed in a bowl of cold water, at the end of the dissolution of glass is heated on a sand bath. If you roll a considerable precipitate of silicic acid, add 1−2 cm
hydrofluoric acid and heating was continued (in a fume hood); a large part of silicic acid evaporates in the form of fluoride of silicon.
Dissolution is complete when terminated organic emissions of nitrogen oxides (in this case turbid sediment should slowly sink to the bottom of the glass).
The contents of the Cup brought to the boil, pour 100 cmof hot water and again bring the solution to boil. The hot solution is poured through an asbestos filter, specially treated and placed in a porcelain crucible with a mesh bottom or glass funnel with a porcelain filter plate.
Filtration is carried out under vacuum. The precipitate of graphite (unbound carbon) is washed in a glass 4−5 times with hot water acidified with a few drops of nitric acid, diluted 1:1.
The precipitate transferred to the filter adhering particles removed with a piece of asbestos with glass rods and forceps.
After that, the precipitate and the asbestos filter is washed with hot (70−80 °C) water until it stops in the washing waters of reaction to nitric acid (when mixed on a porcelain plate drops of washing liquid with two drops of diphenylamine must not develop blue staining).
The precipitate of graphite, together with the asbestos quantitatively transferred (using forceps) in a porcelain boat, pre-calcined in flowing oxygen, and dried in a drying Cabinet at a temperature of about 110−115 °C for 30−40 min.
The dried precipitate of graphite is burned in a tube furnace. Further characterization is carried out as specified in by a gas-volume method of determining the mass fraction of carbon in iron (p.2.4) or determine the mass fraction of carbon Express analyzer an-29 (n.3.4).
4.2; 4.3. (Changed edition, Rev. N 1).
4.4. Processing of the results
4.4.1. Mass fraction of unbound carbon () in percent is calculated by the formula
where — scale gas-measuring burette, % corresponding to the mass fraction of carbon in the sample in terms of experience, with the weight 1 g;
— correction factor for temperature and pressure. If the definition is done on the Express analyzer an-29, the mass percent of carbon is calculated as described in section 3.5.
4.4.2. Permissible differences between results of the parallel definitions should not exceed the values given in the table.
| Mass fraction of carbon, % |
Allowable difference, % |
| 0,1−0,2 |
0,02 |
| 0,2−0,5 |
0,03 |
| 0,5−1,0 |
0,05 |
| 1,0−2,0 |
0,07 |
| 2,0−4,5 |
0,10 |
(Changed edition, Rev. N 2).
