ISO-4140-1979.pdf
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1、International Standard ,NTERNAT,ONAL ORGANIZATION FOR STANDARDIZATIONMEXAHAPOLHAR OPrAHMBAUMR IlO CTAHAAPTH3AUWl.ORGANlSATlON INTERNATIONALE DE NORMALISATION Ferrochromium and ferrosilicochromium - Determination of chromium content - Potentiometric method Ferro-chrome et ferro-silica-chrome - Dosage
2、 du chrome - Mkthode potentiomktrique First edition - 1979-09-15 G UDC 669.15-198 : 543.257.1 : 546.76 Ref. No. IS0 4140-1979 (E) E $ Descriptors : ferroalloys, ferrochromium, chromium containing alloys, ferrosilicochromium, silicon containing alloys, chemical analysis, determination of content, chr
3、omium, potentiometric analysis. % - Price based on 3 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:47:48 MDTNo reproduction or networking permitted without license fro
4、m IHS -,-,- Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 member bodies). The work of developing Interna- tional Standards is carried out through IS0 technical committees. Every member body interested in a subject fo
5、r which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non- governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the m
6、ember bodies for approval before their acceptance as International Standards by the IS0 Council. International Standard IS0 4140 was developed by Technical Committee ISO/TC 132, ferroalloys, and was circulated to the member bodies in January 1978. It has been approved by the member bodies of the fol
7、lowing countries : Australia Austria Bulgaria Canada Czechoslovakia Egypt, Arab Rep. of France Germany, F. R. India Iran Italy Japan Mexico Norway Poland Romania No member body expressed disapproval of the document. South Africa, Rep. of Spain Sweden Turkey United Kingdom USA USSR Yugoslavia 0 Inter
8、national Organization for Standardization, 1979 l Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:47:48 MDTNo reproduction or networking permitted witho
9、ut license from IHS -,-,- INTERNATIONAL STANDARD IS0 4140-1979 (El Ferrochromium and ferrosilicochromium - Determination of chromium content - Potentiometric method 1 Scope and field of application This International Standard specifies a potentiometric method for the determination of the chromium co
10、ntent of fer- rochromium and ferrosilicochromium. 4.2 Sodium carbonate. 4.3 Ammonium persulphate L(NH,),S,O,l. 4.4 Urea. The method is applicable to all grades of these ferroalloys. 4.5 Phosphoric acid, e I,7 g/ml. 2 Reference IS0 3713, Ferroallo ys - Sampling and preparation of samples - General ru
11、les. ) 3 Principle Fusion of a test portion with sodium peroxide, dissolution of the melt in water, and acidification of the aqueous solution with sulphuric acid; alternatively, for some ferroalloys, dissolution of a test portion by direct acid attack. Oxidation of chromium with ammonium persulphate
12、 in the presence of silver ions as catalyst. Determination of the sum of chromium and vanadium by potentiometric titration with ammonium iron sulphate. Reoxidation of vanadium with potassium permanganate; destruction of the excess of permanganate by nitrite, and destruction of the excess of nitrite
13、by urea. Determination of vanadium by potentiometric titration with ammonium iron sulphate, and determination of the chromium content by dif- ference. The reactions are the following : Cr20:- + 6 Fez+ + 14H+ + 2 Cr3+ + 6 Fe3+ + 7H,O VO; + Fez+ + 2H+ + V02+ + Fe3+ + H,O 5 vo2+ + MnO, + H,O 4 5 VO; +
14、Mn2+ +2H+ 5NO;+2MnO; +6H+5NO;+ 2Mn2+3H20 4 Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 4.1 Sodium peroxide. 4.6 Nitric acid, e I,42 g/ml. 4.7 Hydrofluoric acid, Q I,14 g/ml. 4.8 Sulphuric acid, 50 % (V/v) sol
15、ution. To 400 ml of water, add cautiously 500 ml of sulphuric acid (Q 1,84 g/ml), mix, cool, dilute to 1 000 ml and mix. 4.6 Hydrochloric acid, 40 % (V/l/) solution. To 600 ml of water, add 400 ml of hydrochloric acid (Q 1,19 g/ml), and mix. 4.10 Silver nitrate solution. Dissolve 5 g of silver nitra
16、te in water and dilute to 1 000 ml. 4.11 Potassium permanganate solution. Dissolve 2,5 g of potassium permanganate in water and dilute to 100 ml. 4.12 Potassium nitrite solution. Dissolve 1 g of potassium nitrite in water and dilute to 100 ml. 4.13 Potassium dichromate. Dissolve pure potassium dichr
17、omate in water, recrystallize, dry the crystals at 150 OC and melt them at 415 “C. Grind the pro- duct to about 8 mesh and store in a glass bottle with a ground glass stopper. NOTE The potassium dichromate reagent may be purchased as high-grade material for volumetric analysis and dried at 105 OC be
18、fore US?. I) At present at the stage of draft. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:47:48 MDTNo reproduction or networking permitted without license from IHS -,-,
19、- IS0 4140-1979 (E) 4.14 Ammonium iron sulphate, approximately 0,17 N standard volumetric solution. 4.14.1 Preparation Dissolve 65 g of ammonium iron sulphate in 500 ml of water in a 1 000 ml volumetric flask. When dissolution is complete, add 100 ml of the sulphuric acid solution (4.81, cool, make
20、up to the mark and mix. 4.14.2 Standardization Transfer 1,000 + 0,000 2 g of the potassium dichromate (4.13) to a 600 ml beaker. Dissolve in 100 ml of water, add 30 ml of the sulphuric acid solution (4.8) and dilute to 300 ml. Proceed as described in 7.2.3 and 7.2.4. The chromium equivalent, T, of t
21、he ammonium iron (II) sulphate solution, expressed in grams of chromium correspon- ding to 1 ml of solution, is given by the formula 0,353 5 T= Vl where V, is the volume, in millilitres, of the ammonium iron sulphate solution added. 5 Apparatus Usual laboratory equipment and in particular : 5.1 Cruc
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