1、BRITISH STANDARD BS EN 23909:1994 ISO 3909:1976 Hardmetals Determination of cobalt Potentiometric method The European Standard EN 23909:1993has the status of a British Standard UDC 621.762:546.73:543.257.1BS EN23909:1994 This British Standard, having been prepared under the directionof the Iron and
2、SteelStandards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 15January1994 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference ISM/65 Announced in BSI News, January1993 ISBN 0 580 22156 3 Cooperating o
3、rganizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Stan
4、dardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority of Ireland Italy Ente Na
5、zionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardiseringskommissionen i Sve
6、rige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amendments issued since publication Amd. No. Date CommentsBS EN23909:1994 BSI 01-2000 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 1 Scope 3 2 Field of ap
7、plication 3 3 Principle 3 4 Interfering elements 3 5 Reagents 3 6 Apparatus 3 7 Sampling 3 8 Procedure 3 9 Expression of results 4 10 Test report 4 National annex NA (informative) Committees responsible Inside back coverBS EN23909:1994 ii BSI 01-2000 National foreword This British Standard has been
8、prepared under the direction of the Iron and Steel Standards Policy Committee and is the English language version of EN23909:1993 Hardmetals Determination of cobalt Potentiometric method, published by the European Committee for Standardization (CEN). It is identical with ISO3909:1976, prepared by Te
9、chnical Committee119 “Powder metallurgy” of the International Organization for Standardization (ISO) with the active participation of the UK. This British Standard supersedes BS5600-4.3:1979which is withdrawn. A British Standard does not purport to include all the necessary provisions of a contract.
10、 Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages2to4, an insi
11、de back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPNNE EUROPISCHE NORM EN 23909 October 1993 UDC 621.762:546.73:543.257.1 De
12、scriptors: Powder metallurgy, hard metals, chemical analysis, determination of content, cobalt, potentiometric methods English version Hardmetals Determination of cobalt Potentiometric method (ISO 3909:1976) Mtaux durs Dtermination du cobalt Mthode potentiomtrique (ISO 3909:1976) Hartmetalle Bestimm
13、ung des Kobaltgehaltes Potentiometermethode (ISO 3909:1976) This European Standard was approved by CEN on 1993-10-25. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without a
14、ny alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made b
15、y translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Lu
16、xembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1993Copyright reserved to CEN members Ref. No. EN
17、23909:1993EEN23909:1993 BSI 01-2000 2 Foreword On the proposal of the CEN Central Secretariat, the Technical Board decided to submit the InternationalStandard: Hardmetals Determination of cobalt Potentiometric method (ISO3909:1976) to the formal vote. The result of the formal vote was positive. This
18、 European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April1994, and conflicting national standards shall be withdrawn at the latest by April1994. In accordance with the CEN/CENELEC Internal Regulations, th
19、e following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EN23909:1993 BSI 01-2000 3 1 Scope This International St
20、andard specifies a potentiometric method for the determination of the cobalt content of hardmetals. 2 Field of application This method is applicable to carbides and binder metal powder mixtures, free of lubricant, all grades of presintered or sintered hardmetals, having a cobalt content exceeding1%
21、(m/m). 3 Principle Oxidation of cobalt to the trivalent state in a strongly ammoniacal solution with an excess of potassium hexacyanoferrate(III). Potentiometric back-titration of the excess with cobalt sulphate solution. 4 Interfering elements The effect of interfering elements, for example vanadiu
22、m and manganese, shall be taken into account. Vanadium and manganese are also oxidized by hexacyanoferrate(III). Vanadium reacts stoichiometrically and a correction can be applied if the vanadium content is below0,5% (m/m). Manganese reacts almost stoichiometrically up to0,2% (m/m) only if the sum o
23、f tantalum and niobum in the hardmetal is less than0,02% (m/m). Above this level the method is applicable only if the manganese content is less than0,03% (m/m). 5 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 5.
24、1 Ammonium sulphate 5.2 Hydrochloric acid, 1,19g/ml. 5.3 Hydrofluoric acid, 1,12g/ml. 5.4 Nitric acid, 1,42g/ml. 5.5 Sulphuric acid, 1,84g/ml. 5.6 Ammonia solution, 0,91g/ml. 5.7 Ammonium citrate solution. Dissolve100g of citric acid in900ml of water and add100ml of the ammonia solution (5.6). 5.8 C
25、obalt sulphate, standard reference solution containing3g of cobalt per litre. Prepare the solution from compact metallic cobalt, or from diammonium cobalt sulphate, or from cobalt sulphate. If necessary, establish the titre gravimetrically with1-nitroso-naphthol-2, or electrolytically. 5.9 Potassium
26、 hexacyanoferrate(III), standard volumetric solution. 1l should correspond to approximately3g of cobalt. Dissolve17g of K 3 Fe(CN) 6 in1l of water. Determine the relationship between the volumes of the cobalt sulphate solution (5.8) and the potassium hexacyanoferrate(III) solution (5.9) in the follo
27、wing way. 5.9.1 Transfer into a400ml beaker5g of the ammonium sulphate (5.1), 40ml of the ammonium citrate solution (5.7), 50to100ml of water, 80ml of the cooled ammonia solution (5.6), and from a burette approximately9ml of the potassium hexacyanoferrate(III) solution (5.9). Volume used:V 3 ml. Imm
28、ediately titrate with the cobalt sulphate solution (5.8). Volume used: V 4 ml. 5.9.2 Calculate the relationship according to the formula 5.10 Methyl red indicator, 1g/l solution, or indicatorpaper for pH3to5. 6 Apparatus Ordinary laboratory apparatus and 6.1 Potentiometric titration apparatus with s
29、tirrer or some other arrangement for agitating. 6.2 Platinum electrode 6.3 Tungsten wire or any other reference electrode. 6.4 Burettes, of capacity10ml. 7 Sampling 7.1 The sample shall be crushed to a powder in a mortar made of a material which does not alter the sample composition. The powder shal
30、l pass a0,18mm sieve. 7.2 The analysis shall be carried out on two or three test portions. 8 Procedure 8.1 Test portion Weigh, to the nearest0,0001g, 0,1to0,5g of the test sample, depending on the cobalt content. K V 4 V 3 - =EN23909:1993 4 BSI 01-2000 8.2 Attack Transfer the test portion into a400m
31、l beaker, add10to15ml of the sulphuric acid (5.5), 3ml of the hydrochloric acid (5.2) and5g of the ammonium sulphate (5.1). Cover the beaker with a watch-glass and heat until complete dissolution is achieved. Cool. Add, in small portions, 40to50ml of the ammonium citrate solution (5.7). Rinse the wa
32、tch-glass and the beaker walls with20to50ml of water. Heat the solution gently until all salts are dissolved. Cool. The following alternative method of attack may be used. Transfer the test portion into a400ml polypropylene beaker or into a platinum dish, add10ml of water and5ml of the hydrofluoric
33、acid(5.3) and cover the beaker with a polypropylene cover. Warm to approximately60 C. Add the nitric acid (5.4), drop by drop, until dissolution is complete. Cool. Add, in small portions, 10ml of the sulphuric acid (5.5) and40to50ml of the ammonium citrate solution (5.7). (If vanadium is present, he
34、at the solution and cool again.) Rinse the cover and the beaker walls with20to50ml of water. 8.3 Neutralization Add1 drop of the methyl red indicator solution or use the indicator paper (5.10). Carefully neutralize most of the acid with the ammonia solution (5.6) to a weakly acid solution (pH3to5).
35、Avoid over-neutralizing. Cool. 8.4 Titration Add80ml of the ammonia solution (5.6) preferably cooled to10 C. Immediately add the potassium hexacyanoferrate(III) solution (5.9) from a burette to an excess of a few millilitres. Volume used: V 1ml. Back-titrate with the cobalt sulphate solution (5.8).
36、Volume used: V 2ml. 9 Expression of results 9.1 Calculation The cobalt content, expressed as a percentage by mass, is given by the formula where K is as defined in 5.9.2; T is the mass, in grams, of cobalt in1ml of the cobalt sulphate solution; m is the mass, in grams, of the test portion. The resul
37、t shall be rounded to the nearest0,01%. 9.2 Corrections As a tentative guide, the following correction values may be used. Vanadium: 0,100% (m/m) vanadium is equal to0,116% (m/m) cobalt. Manganese: 0,100% (m/m) manganese is equal to0,107% (m/m) cobalt. 9.3 Tolerances The deviations between two or th
38、ree independent determinations shall not exceed the values shown in the table. 9.4 Final result Report the arithmetical mean of acceptable determinations rounded to the nearest0,1%. 10 Test report The test report shall include the following information: a) reference to this International Standard; b
39、) all details necessary for identification of the test sample; c) the result obtained; d) all operations not specified by this International Standard, or regarded as optional; e) details of any occurrence which may have affected the result. KV 1 V 2 ()T 100 m - Cobalt content % Range for two determi
40、nations % Range for three determinations % from1to5 0,10 0,12 over5to8 0,15 0,18 over8to20 0,20 0,25 over20 0,30 0,35BS EN23909:1994 BSI 01-2000 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the I
41、ron and Steel Standards Policy Committee (ISM/-) to Technical Committee ISM/65, upon which the following bodies were represented: British Hardmetal Association Federation of British Engineers (Test Manufacturers) Society of Motor Manufacturers and Traders Ltd.BS EN 23909:1994 ISO 3909:1976 BSI 389 C
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