BS DD CEN TS 14940-1-2009 Copper and copper alloys - Determination of chromium content - Titrimetric method《铜和铜合金 铬含量测定 滴定法》.pdf

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1、DD CEN/TS14940-1:2009ICS 77.040.30; 77.120.30NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWDRAFT FOR DEVELOPMENTCopper and copperalloys Determinationof chromium contentPart 1: Titrimetric methodThis Draft for Developmentwas published underthe authority of theStandards Policy

2、andStrategy Committee on 30November 2009 BSI 2009ISBN 978 0 580 58502 9Amendments/corrigenda issued since publicationDate CommentsDD CEN/TS 14940-1:2009National forewordThis Draft for Development is the UK implementation of CEN/TS14940-1:2009.This publication is not to be regarded as a British Stand

3、ard.It is being issued in the Draft for Development series of publications andis of a provisional nature. It should be applied on this provisional basis,so that information and experience of its practical application can beobtained.Comments arising from the use of this Draft for Development arereque

4、sted so that UK experience can be reported to the internationalorganization responsible for its conversion to an international standard.A review of this publication will be initiated not later than 3 years afterits publication by the international organization so that a decision can betaken on its s

5、tatus. Notification of the start of the review period will bemade in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period,the responsible BSI Committee will decide whether to support theconversion into an international Standar

6、d, to extend the life of theTechnical Specification or to withdraw it. Comments should be sent tothe Secretary of the responsible BSI Technical Committee at BritishStandards House, 389 Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted to TechnicalCommittee NFE/3

7、4, Copper and copper alloys.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard ca

8、nnot confer immunityfrom legal obligations.DD CEN/TS 14940-1:2009TECHNICAL SPECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 14940-1 October 2009 ICS 77.040.30; 77.120.30 English Version Copper and copper alloys - Determination of chromium content -Part 1: Titrimetric method Cuivr

9、e et alliages de cuivre - Dosage du chrome - Partie 1: Mthode titrimtrique Kupfer und Kupferlegierungen - Bestimmung des Chromgehaltes - Teil 1: Titrimetrisches Verfahren This Technical Specification (CEN/TS) was approved by CEN on 23 May 2009 for provisional application. The period of validity of t

10、his CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way

11、as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are t

12、he national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerla

13、nd and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/

14、TS 14940-1:2009: EDD CEN/TS 14940-1:2009CEN/TS 14940-1:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Principle 4 4 Reagents and materials 4 5 Apparatus .6 6 Sampling .6 7 Procedure .6 8 Expression of results 7 9 Test report 7 Bibliography 8 DD CEN/TS 14940-1:2009CEN/TS 149

15、40-1:2009 (E) 3 Foreword This document (CEN/TS 14940-1:2009) has been prepared by Technical Committee CEN/TC 133 “Copper and copper alloys”, the secretariat of which is held by DIN. Within its programme of work, Technical Committee CEN/TC 133 requested CEN/TC 133/WG 10 “Methods of Analysis“ to prepa

16、re the following document: CEN/TS 14940-1, Copper and copper alloys Determination of chromium content Part 1: Titrimetric method This is one of two parts of the document for the determination of chromium content in copper and copper al-loys. The other part is: EN 14940-2, Copper and copper alloys De

17、termination of chromium content Part 2: FAAS method. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulation

18、s, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Cyprus, Czech Re-public, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithua-nia, Luxembourg, Malta, Net

19、herlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Swe-den, Switzerland and the United Kingdom. DD CEN/TS 14940-1:2009CEN/TS 14940-1:2009 (E) 4 1 Scope This part of this document specifies a titrimetric method for the determination of the chromium content of copper and copper al

20、loys in the form of castings or unwrought or wrought products. The method is applicable to products having chromium mass fractions between 0,10 % and 2,0 %. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refer-ences, only t

21、he edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1811-1, Copper and copper alloys Selection and preparation of samples for chemical analysis Part 1: Sampling of cast unwrought products ISO 1811-2, Copper and coppe

22、r alloys Selection and preparation of samples for chemical analysis Part 2: Sampling of wrought products and castings NOTE Informative references to documents used in the preparation of this standard, and cited at the appropriate places in the text, are listed in the Bibliography. 3 Principle Dissol

23、ution of a test portion followed by oxidation of the greater part of chromium by perchloric acid in the presence of orthophosphoric acid to avoid loss of chromium. Oxidation of residual chromium(III) by potassium permanganate. Reduction of chromium(VI) by iron(II) solution and determination of the e

24、quivalence point by measuring the change in potential as a function of the volume of titrant used. 4 Reagents and materials During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid, HCl ( = 1,19 g/ml) 4.2 Hydr

25、ochloric acid solution, 1+ 20 Add 5,0 ml of the hydrochloric acid (4.1) to 100 ml of water. 4.3 Nitric acid, HNO3( = 1,40 g/ml) 4.4 Hydrofluoric acid, HF ( = 1,13 g/ml) CAUTION Hydrofluoric acid is a hazardous material. Care shall be taken and its use to be made in an efficient fume hood. 4.5 Perchl

26、oric acid, HClO4 ( = 1,61 g/ml) CAUTION Perchloric acid concentrated and hot reacts rapidly, often with violently explosive force with oxidizable materials. Specially designed hoods are specified for handling perchloric acid fumes DD CEN/TS 14940-1:2009CEN/TS 14940-1:2009 (E) 5 and any hood in which

27、 perchloric acid may be fumed should not be used for other operations that permit easily oxidizable materials to collect in the ducts and blower. 4.6 Sulphuric acid, H2SO4 ( = 1,84 g/ml) 4.7 Orthophosphoric acid, H3PO4 ( = 1,70 g/l) 4.8 Orthophosphoric acid solution, 1 + 2 Add 100 ml of orthophospho

28、ric acid (4.7) to 200 ml of water. 4.9 Potassium permanganate solution, KMnO4, 2,5 g/l 4.10 Potassium dichromate standard solution Weigh 4,903 3 g of potassium dichromate (K2Cr2O7) and transfer to a beaker of suitable capacity and dissolve in reductant-free water. Transfer quantitatively to a 1 000

29、ml one-mark volumetric flask, dilute to the mark with reductant-free water and mix. 1 ml of this standard solution contains 1,733 mg of chromium. 4.11 Iron(II) ammonium sulphate solution, 46 g/l 4.11.1 Preparation of the solution Dilute 54 ml of the sulphuric acid (4.6) to 1 litre with water. Dissol

30、ve 46 g of iron(II) ammonium sulphate hexahydrate (NH4)2Fe(SO4)26H2O in a small amount of this solution, then dilute to 1 000 ml with the same sulphuric acid solution. 1 ml of this solution is equivalent to approximately 2 mg of chromium. 4.11.2 Potentiometric standardization of the solution Transfe

31、r 30 ml of the potassium dichromate solution (4.10) to a 600 ml beaker containing 15 ml of the sulphuric acid (4.6), 25 ml of the orthophosphoric acid solution (4.8) and about 330 ml of water. Titrate using the procedure specified in 7.4. The titre of the iron(II) ammonium sulphate solution (4.11),

32、expressed as milligrams of chromium per millilitre of solution, is given by formula 1. 733,121Cr=VVc (1) where V1is the volume of the potassium dichromate standard solution (4.10) used, in millilitres (ml); V2is the volume of the iron(II) ammonium sulphate solution (4.11.1) used in the titration, in

33、 millilitres (ml). Daily standardization of the iron(II) ammonium sulphate solution is required. DD CEN/TS 14940-1:2009CEN/TS 14940-1:2009 (E) 6 5 Apparatus 5.1 Beakers, capacities e.g. 600 ml, tall form 5.2 Potentiometric titration apparatus 6 Sampling Sampling shall be carried out in accordance wi

34、th ISO 1811-1 or ISO 1811-2, as appropriate. Test samples shall be in the form of fine drillings, chips or millings with a maximum thickness of 0,5 mm. 7 Procedure 7.1 Preparation of the test portion solution 7.1.1 Test portion Weigh (2 0,001) g of the test sample. 7.1.2 Test portion solution Transf

35、er the test portion (7.1.1) to a 600 ml tall form beaker (5.1). Add 20 ml of the hydrochloric acid (4.1), 10 ml of the nitric acid (4.3) and 1 ml of the hydrofluoric acid (4.4). When effervescence ceases, add 10 ml of the orthophosphoric acid solution (4.8) and 30 ml of the perchloric acid (4.5). Br

36、ing to the boil and evaporate until thick white perchloric acid fumes appear. Maintain until the test portion is totally dissolved. Reduce the heat and boil gently for 5 min, then cool. Add 30 ml of water and boil for 5 min, then cool. 7.1.3 Oxidation of residual chromium(III) Add 150 ml of water to

37、 the test portion solution (7.1.2), bring to the boil and add 5 ml of the potassium permanganate solution (4.9). Boil for 3 min, then add 10 ml of the hydrochloric acid solution (4.2) and boil for 15 min. Allow to cool. 7.2 Blank test Carry out a blank test simultaneously with the determination, fol

38、lowing the same procedure and using the same quantities of all reagents as used for the determination, but omitting the test portion. 7.3 Check test Make a preliminary check of the method by preparing a solution of a reference material or a synthetic sample containing a known amount of chromium and

39、of a composition similar to the material to be analysed. Carry out the procedure specified in 7.1 and 7.4. 7.4 Determination Transfer the test portion solution (7.1.3) to a 600 ml tall-form beaker (5.1). Add 20 ml of the sulphuric acid (4.6) and 25 ml of the orthophosphoric acid solution (4.8). Dilu

40、te to about 400 ml with water. Allow to cool, if necessary. Place the electrodes of the potentiometric titration apparatus in the solution and, while stirring, titrate with the iron(II) ammonium sulphate solution (4.11) until the potentiometric change occurs. Titrate slowly near the end-point. Using

41、 a platinum saturated calomel electrode, the change in potential is of the order of 200 mV and lies between 900 mV and 700 mV. DD CEN/TS 14940-1:2009CEN/TS 14940-1:2009 (E) 7 8 Expression of results Calculate the chromium mass fraction in per cent (%), as follows: mcVVw10)(CrblCr= (2) where V is the

42、 volume of the iron(II) ammonium sulphate solution (4.11) used in the determination (7.4), in millilitres (ml); Vblis the volume of the iron(II) ammonium sulphate solution (4.11) used in the blank test (7.2), in millilitres (ml); cCris the titre of the iron(II) ammonium sulphate solution (4.11), exp

43、ressed as milligrams of chromium per millilitre (mg/ml) of solution, calculated in 4.11.2; m is the mass of the test portion (7.1.1), in grams (g). 9 Test report The test report shall contain the following information: a) identification of the test sample; b) reference to this document (CEN/TS 14940

44、-1:2009); c) test method used; d) results; e) any unusual characteristics noted during the determination; f) any operation not included in this document or in the document to which reference is made or regarded as optional; g) date of the test and or date of preparation or signature of the test repo

45、rt; h) signature of the responsible person. DD CEN/TS 14940-1:2009CEN/TS 14940-1:2009 (E) 8 Bibliography In the preparation of this Technical Specification, use was made of a number of documents for reference pur-poses. The relevant publications are listed hereafter. 1 ISO 6437, Copper alloys Determ

46、ination of chromium content Titrimetric method 2 BS 6721-10, Sampling and analysis of copper and copper alloys Method for determination of chromium in copper alloys: titrimetric method DD CEN/TS 14940-1:2009This page has been intentionally left blank DD CEN/TS14940-1:2009BSI GroupHeadquarters 389Chi

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