GOST 2604.2-86
GOST 2604.2−86 Cast iron alloy. Methods of determining sulphur
GOST 2604.2−86
Group B09
INTERSTATE STANDARD
ALLOY CAST IRON
Methods of determining sulphur
Alloy cast iron. Methods for determinations of sulphur
ISS 77.080.10
AXTU 0809
Date of introduction 1988−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR
DEVELOPERS
V. D. Chechenov, PhD. tech. Sciences; M. A. Druzhinin, PhD. tech. Sciences (head of subject); Y. D. Hudik, T. J., Kalinchenko; Z. D. Budnik; T. N. Poltoratskaya; L. V. Saenko
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. REPLACE GOST 2604.2−77
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
The number of the paragraph, subparagraph, enumeration, applications |
| GOST 435−77 |
2.2 |
| GOST 859−2001 |
2.2 |
| GOST 860−75 |
2.2 |
| GOST 2604.0−77 |
2.2 |
| GOST 3118−77 |
2.2 |
| GOST 4202−75 |
2.2 |
| GOST 4204−77 |
2.2 |
| GOST 4232−74 |
2.2 |
| GOST 4328−77 |
2.2 |
| GOST 5583−78 |
2.2, 3.2 |
| GOST 9147−80 |
2.2, 3.2 |
| GOST 10163−76 |
2.2 |
| GOST 13610−79 |
2.2 |
| GOST 16539−79 |
2.2 |
| GOST 20490−75 |
2.2 |
| GOST 24363−80 |
2.2 |
| GOST 28473−90 |
1.1 |
5. Limitation of actions taken by Protocol No. 2−92 of the Interstate Council for standardization, Metrology and certification (ICS 2−93)
6. REISSUE
This standard establishes titrimetric, and coulometric methods for the determination of sulphur in cast irons alloyed with mass fraction her from of 0.004 to 0.1%.
The standard complies ST SEV 5283−85 in the determination of sulfur in doped iron.
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 28473.
2. TITRIMETRIC METHOD
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 1250−1350 °C, the absorption of the formed sulphur dioxide with water and titration of the resulting sulfurous acid solution of iodide of potassium Iodate in the presence of starch indicator.
2.2. Apparatus, reagents and solutions
Setup for the determination of sulfur (hell.1) consists of a source of oxygen (coloradobased or cylinder) 1 provided with a pressure reducing valve to regulate the flow of oxygen; Tishchenko flask 2 containing a solution of potassium permanganate in a solution of potassium hydroxide; the flask Tishchenko 3 filled with sulphuric acid; a drying column 4 filled with the pellets of potassium hydroxide, in the upper — anhydrous calcium chloride or angerona. The oxygen scrubbers may consist of gorkaltseva tube column Astarita and U-shaped tube containing the first half (downstream) asbestos, impregnated with manganese dioxide, and the second — anhydro; 5 rotameter to measure the flow of oxygen; the three-way tap 6, a horizontal tubular electrical furnace 7 with water cooling and silicafume heaters providing a temperature 1250−1350 °C with voltage controller 8 and the controller 9 of any type (it is allowed to use a tubular furnace of any type, providing the desired temperature); the mullite refractory tube 10 with a length of 600−800 mm, with an internal diameter of 18−22 mm, preheated on the entire length at a temperature of 1250−1350 °C. the ends of the tube should protrude out of the oven at least 200 mm on each side. The tube is closed by a metal gate or a well-fitting rubber stoppers with holes, into which insert a glass or other non-corrosive pipe. The inner surface of the tubes must be protected from the erosion of asbestos or non-corrosive spacers; unglazed porcelain boats 11 (before use, the boat is calcined in flowing oxygen at the operating temperature of 1250−1350 °C in conditions of analysis and stored in a desiccator. Socket covers do not cover the desiccator lubricating substances); glass tube 12 with the extension, filled with glass wool for cleaning gas mixture from mechanical impurities produced by the combustion of sample and entrained from the furnace by a current of oxygen; burettes with a capacity of 13 to 25 cm(or microburette) titrated with a solution of iodide of potassium Iodate; a device for absorption of sulfur dioxide and titration 14.
Damn.1
The device (Fig.2) consists of two glass vessels (absorption and vessel comparison) of the same shape. The absorption vessel is in the process of absorption and titration of the sulfur dioxide in the vessel comparison, is solution comparisons to control the color of the solution during the titration.
Damn.2
In the absorption vessel is soldered l-shaped tube terminating in a bubbler with a float, through which the vessel receives the gaseous products of combustion. At the bottom of the vessel has a tap to drain the solution. Hook for insertion and retrieval of boats from the tube are made of heat-resistant low-carbon wire of any cross section with a diameter of 3−5 mm, length 500−600 mm.
Tube refractory mullite.
Boat porcelain with GOST 9147.
Oxygen GOST 5583.
Hydrochloric acid according to GOST 3118.
Potassium hydroxide according to GOST 24363.
Sodium hydroxide according to GOST 4328.
Potassium permanganate according to GOST 20490, solution with mass concentration 40 g/lsolution of potassium hydroxide with a mass concentration of 400 g/l
; 40 g of potassium permanganate dissolved by heating at 700−800 cm
of water. After cooling, add 400 g of potassium hydroxide and adjusted with water to 1 DM
.
Sulfuric acid according to GOST 4204.
The calcium chloride.
Manganese (II) sulfate 5-water according to GOST 435.
Askari (soda asbestos).
Anhydro (anhydrous magnesium rate).
Wool.
Asbestos impregnated with manganese dioxide used to fill the absorption column: 13 g of manganese sulfate dissolved in a small amount of water and this solution was impregnated with 90 g of asbestos fiber, pre-calcined at 800−1000 °C, add 7 g of potassium permanganate dissolved in 200 cmof water, boil for a few minutes. Then filtered on a Buchner funnel, washing with hot water to the filtrate with sulfuric salts. Impregnated with manganese dioxide asbestos dried at 105 °C.
Potassium ignominously according to GOST 4202.
Potassium iodide according to GOST 4232.
Potassium iodide-Iodate, titrated a solution of 0,0862 g odnomodovogo potassium, 17 g of potassium iodide and 0.4 g of potassium hydroxide dissolved in 1 DMof water. For the determination of sulfur in cast iron with a mass fraction of less than 0.05% of the titrated solution was diluted in a 1:1 ratio.
The solution was stored in a flask made of dark glass. The mass concentration of the solution of iodide of potassium Iodate set by standard samples, burn in testing conditions, with a known mass fraction of sulfur and a chemical composition close to the composition of the sample of cast iron. The mass concentration of the solution of iodide of potassium Iodate () in g/cm
sulfur is calculated by the formula
where — mass fraction of sulfur in the standard sample, %;
— weight of standard sample, g;
the volume of the solution of iodide of potassium Iodate consumed for titration of the standard sample, cm
;
the volume of the solution of iodide of potassium Iodate consumed for titration in the reference experiment (boat + beach), cm
.
The starch according to GOST 10163, solution with a mass concentration of 0.5 g/l, freshly prepared: 0.5 g of starch is dissolved by heating in 50 cm
of water, the resulting solution was poured into a flask with 500 cm
of water, pour 15 cm
of hydrochloric acid and the volume was adjusted with water to 1 DM
, mix. Then, in small portions, with stirring, poured a solution of iodide of potassium Iodate to obtain a weak blue color of the solution.
Marshes: tin GOST 860 or tin granular;
copper metal according to GOST 859;
the copper oxide according to GOST 16539;
radio engineering carbonyl iron according to GOST 13610 or iron carbonyl, OS. h
Mass fraction of sulphur in the flux should not exceed the value allowable absolute differences for the respective ranges of the conc
forming.
2.3. Preparation for assay
The furnace is heated to operating temperature. The installation collected by means of rubber tubes according to hell.1 (the connections must be as short as possible) and check for leaks as follows: allow oxygen through the plant at a speed of 20−30 bubbles per minute. Then tightly clamp the rubber tube in front of the absorption vessel. After 2−3 min it should stop bubbling in the wash bottles, then incubated another 2−3 min. If the bubbles are no longer selected, the system is considered leak-proof.
The completeness of burnout of sulfur from the porcelain tube is checked as follows: one end of the porcelain tube connected to a source of purified oxygen, and the second absorption vessel. In both vessels poured at 90−110 cmstarch solution weak blue color and leak current of oxygen. Resistance of the color of the solution in the absorption vessel testifies to the completeness of burnout of sulfur from the porcelain tube.
To check the correct operation of the installation burn 2−3 sample standard sample of cast iron, optionally in the presence of flux according to claim 2.3. Then burn the flux linkage for the establishment of amendments in the reference experiment.
2.4. Analysis
The weight of cast iron weighing 0.5 g is placed in a porcelain boat and, if necessary, coated with flux in the ratio (1:1).
The boat with the charge placed in the most heated portion of the porcelain tube, which quickly closed with the stopper or tube and allowed to stand for 1 min without oxygen using a three-way tap, and then passed a current of oxygen at a rate of 2−3 DM/min.
When the sulfur dioxide coming from the furnace of the absorption vessel, will begin to discolor the solution from the burette pour the solution of iodide of potassium Iodate with such speed that the liquid always remained slightly blue.
The titration is complete when the color intensity of the solutions in both vessels is the same and will not change for 1 min.
After combustion of the sample boat was removed from the tube with a hook, and the absorption solution is replaced with fresh.
2.5. Processing of the results
2.5.1. Mass fraction of sulfur () in percent is calculated by the formula
where — volume of the solution of iodide of potassium Iodate consumed for titration of the test solution, cm
;
the volume of the solution of iodide of potassium Iodate consumed for titration of the solution in the reference experiment, cm
;
— mass concentration of a solution of iodide of potassium Iodate, g/cm
sulphur;
— the weight of the portion of the analyzed cast iron, g
.
2.5.2. The absolute differences of the results of three parallel measurements at a confidence level =0.95 does not exceed the permissible values given in the table.
| Mass fraction of sulfur, % |
The absolute allowable difference, % |
| From 0,004 to 0,010 |
0,002 |
| SV. 0,010 «0,020 |
0,005 |
| «0,020» 0,050 |
0,008 |
| «0,050» 0,100 |
0,01 |
3. COULOMETRIC METHOD
3.1.The essence of the method
The method is based on the combustion of a sample of cast iron in a current of oxygen in presence of floodplains at a temperature of 1250−1350 °C, absorbing the resulting sulfur dioxide absorption solution with a specific pH, the pH change and the subsequent measurement of the amount of electricity consumed for the recovery of the original pH, is proportional to the mass fraction of sulfur in the sample.
3.2. Equipment, reagents, solutions
Coulometric installation as-7932 or similar unit of any other type with all accessories for the determination of sulfur.
Tube refractory mullite.
Boat porcelain with GOST 9147. Before using pumps and calcined at a working temperature in a current of oxygen and then stored in a desiccator. Socket covers do not cover the desiccator lubricating substances.
Oxygen GOST 5583.
Absorption and support solutions were prepared according to the instructions to apply coulometric setup.
As flux is used, the vanadium oxide of high purity in the amount of 0.2 g. the Mass fraction of sulfur in the reference experiment must not exceed the amount allowable absolute differences for the respective concentration ranges.
3.3. Preparation for assay
The device is ready to work in accordance with the instructions.
Check the tightness of the gas path.
To remove traces of sulfur dioxide before you start working through the installation of leak current of oxygen and ignited porcelain tube to obtain the minimum continuous readings.
The calibration of an instrument performed on standard samples with the composition close to the analyzed cast iron.
Control of correct operation carried out every 2−3 h combustion of sample standard sample.
3.4. Analysis
The weight of cast iron weighing 0.5 g was placed in a boat and covered with 0.2 g of vanadium pentoxide. A boat with linkage and flux are placed in the most heated part of the tube, which quickly closed the metal gate, push the «reset» button than set indicator digital display to «zero». Burn the sample at a temperature of 1250−1350 °C. In combustion of sample on the digital display there is a continuous readout. After stopping accounts record the results of the analysis. In parallel through all stages of the analysis conduct at least three follow-up tests and receive the arithmetic average of the reference experiment.
3.5. Processing of the results
3.5.1. Mass fraction of sulfur () in percent is calculated by the formula
where — reading digital display of the device by burning the analyzed sample of cast iron, %;
— the arithmetic average of the readings of the digital display device, resulting from the burning flux when conducting control experiments.
3.5.2. The absolute differences of the results of three parallel measurements at a confidence level =0.95 does not exceed the permissible values given in the table.
The differences in assessing the quality of alloyed cast iron used coulometric method for the determination of sulfur.
