SIST EN 24947:1998
(Main)Steel and cast iron - Determination of vanadium content - Potentiometric titration method (ISO 4947:1986)
Steel and cast iron - Determination of vanadium content - Potentiometric titration method (ISO 4947:1986)
Quality. Rationalization.
Stahl- und Gußeisen - Bestimmung des Vanadium-Gehaltes - Potentiometrisches Titrierverfahren (ISO 4947:1986)
Qualitaet. Rationalisierung.
Acier et fonte - Détermination de la teneur en vanadium - Méthode de titration potentiométrique (ISO 4947:1986)
Qualité. Rationalisation.
Jeklo in lito železo - Določanje vanadija - Potenciometrijska metoda titracije (ISO 4947:1986)
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Stahl- und Gußeisen - Bestimmung des Vanadium-Gehaltes - Potentiometrisches Titrierverfahren (ISO 4947:1986)Acier et fonte - Détermination de la teneur en vanadium - Méthode de titration potentiométrique (ISO 4947:1986)Steel and cast iron - Determination of vanadium content - Potentiometric titration method (ISO 4947:1986)77.080.01Železne kovine na splošnoFerrous metals in generalICS:Ta slovenski standard je istoveten z:EN 24947:1991SIST EN 24947:1998en01-avgust-1998SIST EN 24947:1998SLOVENSKI
STANDARD
SIST EN 24947:1998
SIST EN 24947:1998
SIST EN 24947:1998
International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.MEXfiYHAPO,4HAR OPTAHM3ALWlf’l fl0 CTAHAAPTU3ALWlM~ORGANISATiON INTERNATIONALE DE NORMALISATION Steel and cast iron - Determination of vanadium content - Potentiometric titration method Aciers et fontes - Dosage du vanadium - Mk thode par titrage po ten tiome trique First edition - 1986-06-01 UDC 669.13/.14: 543.257.1 : 646.881 Ref. No. ISO 4947-1986 (E) Descriptors : steels, cast iron, Chemical analysis, determination of content, vanadium, potentiometric method. Price based on 6 pages SIST EN 24947:1998
Foreword ISO (the International Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take patt in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 4947 was prepared by Technical Committee ISO/TC 17, S teel. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. 0 International Organkation for Standardkation, 1986 l Printed in Switzerland SIST EN 24947:1998
INTERNATIONAL STANDARD ISO 4947-1986 (E) Steel and cast iron - Determination of vanadium content - Potentiometric titration method 1 Scope and field of application This International Standard specifies a potentiometric titration method for the determination of vanadium in steel and cast iron. The method is applicable to vanadium contents between 0,04 and 2 % (mlm). 2 Reference ISO 377, Wrought steel - Selec tion and prepara tion o f samples and test pieces. 3 Principle Dissolution of a test portion with appropriate acids. Addition of hydrofluoric acid to keep tungsten in Solution. Oxidation of chromium and vanadium by potassium peroxy- disulfate. Partial Oxidation of chromium. While checking the potential of the Solution, - reduction of chromium(Vl) and vanadium(V) by am- monium iron(ll) sulfate; - Oxidation of vanadium by slight excess of potassium per- manganate; reduction of the excess permanganate by sodium nitrite, and reduction of the excess sodium nitrite by sulfamic acid. Potentiometric titration of vanadium by ammonium iron(ll) sulfate Standard solution. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity, free from reducing or oxidizing activity. 4.1 Potassium peroxydisulfate (K&08), 4.2 Hydrochlorit acid, Q about 1,19 g/ml. 4.3 Nitrit acid, Q about 1,40 g/ml. 4.4 Hydrofluoric acid, Q about 1,15 g/ml. 4.5 Sulfuric acid, Q about 1,84 g/ml, diluted 1 + 4. 4.6 Sulfuric acid, Q about 1,84 g/ml, diluted 1 + 50. 4.7 Orthophosphoric acid, Q about 1,70 g/ml. 4.8 Ammonium ironUl) sulfate [Fe(NH4)2(S04)2m6H20], scj,ution in sulfuric acid medium. Dissolve 40 g of ammonium iron(ll) sulfate hexahydrate in ap- proximately 500 ml of water, add 20 ml of sulfuric acid, Q about 1,84 g/ml, cool, make up the volume to 1 000 ml and mix. 4.9 Potassium permanganate, 5 g/l Solution. 4.10 Sodium nitrite, 3 g/l Solution. 4.11 Sulfamic acid (NH$OsH), 100 g/l Solution. This Solution is stable for only one week. 4.12 Potassium dichromate, Standard reference Solution. Weigh, to the nearest 0,001 g, approximately 1 g of potassium dichromate (the highest purity grade) previously dried at 150 OC until a constant mass is obtained on cooling in the desiccator. Introduce the weighed mass into a 250 ml beaker, dissolve it in 20 ml of water and add 160 ml of sulfuric acid (4.5). Transfer the Solution quantitatively into a 1 000 ml one- mark volumetric flask, cool, dilute to the the mark with water and mix. 4.13 Ammonium ironW1 sulfate [Fe(NH4)2(S04)2’6H20], Standard Solution. 1 ml of this Solution corresponds to approximately 1,275 mg of vanadium. 4.13.1 Preparation of the Solution Dissolve 10 g of ammonium iron(ll) sulfate hexahydrate in ap- proximately 500 ml of water, add 25 ml of sulfuric acid, Q about 1,84 g/ml, make up the volume to 1 000 ml and mix. 1 SIST EN 24947:1998
ISO 49474986 (El 4.13 .2 Standa just before use) rdization of the Solution (to be carried out b) for vanadium approximately 2 g contents between 0,25 and 1 % (mlm): Take 25,0 ml of the potassium dichromate Standard reference Solution (4.12) and titrate potentiometrically with the am- monium iron( II) sulfate Solution (4.13.1). The corresponding concentration (c) of the ammonium iron(ll) sulfate Standard Solution (4.13) is given by the formula : Cl for vanadi um contents aP lproxi mately 1 9 between 1 and 2 % (mlm): The quantity of vanadium in the test Portion may vary between 2 and 20 mg. 0,025 x m. c = 49,03 x v x 509 7.2 Blank test Carry out a blank test in pa rallel with the determination, by the same procedure and using the same qua ntities of all reagents. mg = T x 0,026 7.3 Determination where 7.3.1 Preparation of the test Solution c is the corresponding concentration of the ammonium iron(ll) sulfate Standard Solution (4.13) expressed in milli- grams of vanadium per millilitre; 7.3.1.1 Samples soluble in sulfuric acid Introduce the test Portion (7.1) into a 400 ml beaker (see notes 1 and 2) and add 40 ml of sulfuric acid (4.5) for a 1 g or 2 g test Portion. For a 5 g test Portion, add 70 ml of sulfuric acid (4.5). Cover the beaker with a watch-glass and heat gently until effervescence ceases. mg is the mass, dich romate; in milligrams, of the weighed potassium V is the volume, in millilitres, of the ammoniu sulfate Standard Solution (4.13) used for titration; m iron( 11) For samples with high Silicon contents, add 5 to 10 drops of hydrofluoric acid (4.4). Bring to the boil to ensure complete cessation of effervescence. 0,025 is the ratio between the volume taken and the total volume of the potassium dichromate Standard reference Solution; If the test Portion contains tungsten, add a sufficient quantity of hydrofluoric acid (4.4) to keep it in Solution. In general 5 ml of hydrofluoric acid (4.4) will suffice for a 1 g test Portion, 7 ml for a 2 g test Portion, and 13 ml for a 5 g test Portion. 49,03 is the relative dichromate divided by 6; molecular mass of potassium is the relative atomic mass of vanadium. Dilute the Solution to between 90 and 100 ml with water and proceed as in 7.3.2. 5 Apparatus Ordinary laboratory apparatus and 1 If hydrofluoric acid (4.4) is used, silica watch-glass shall be employed. a fused silica bea ker and a fused 2 The arsenic. g lasswa re used should no
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