BS ISO 18632-2010 Alloyed steel - Determination of manganese - Potentiometric and visual titration method《合金钢 锰的测定 电位滴定和可视滴定法》.pdf

1、BS ISO18632:2010ICS 77.140.20NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAlloyed steel Determinationof manganese Potentiometric andvisual titration methodThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 31

2、 July 2010 BSI 2010ISBN 978 0 580 66234 8Amendments/corrigenda issued since publicationDate CommentsBS ISO 18632:2010National forewordThis British Standard is the UK implementation of ISO 18632:2010.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/102, Methods of Chemi

3、cal Analysis for Iron and Steel.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 Standar

4、d cannot confer immunityfrom legal obligations.BS ISO 18632:2010Reference numberISO 18632:2010(E)ISO 2010INTERNATIONAL STANDARD ISO18632First edition2010-06-15Alloyed steel Determination of manganese Potentiometric and visual titration method Aciers allis Dtermination de la teneur en manganse Mthode

5、s de titration visuelle et potentiomtrique BS ISO 18632:2010ISO 18632:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to an

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8、ound, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2010 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and m

9、icrofilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii IS

10、O 2010 All rights reservedBS ISO 18632:2010ISO 18632:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Normative references1 3 Principle1 4 Reagents.1 5 Apparatus.4 6 Sampling and samples4 7 Procedure.4 8 Expression of results5 9 Test report7 Annex A (informative) Addition

11、al information on the international cooperative test8 Annex B (informative) Graphical representation of precision data .10 Bibliography11 BS ISO 18632:2010ISO 18632:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of n

12、ational standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Inter

13、national organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the

14、 rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by

15、 at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 18632 was prepared by Technical Committee ISO

16、/TC 17, Steel, Subcommittee SC 1, Methods of determination of chemical composition. BS ISO 18632:2010INTERNATIONAL STANDARD ISO 18632:2010(E) ISO 2010 All rights reserved 1Alloyed steel Determination of manganese Potentiometric and visual titration method 1 Scope This International Standard specifie

17、s a potentiometric or visual titration method for the determination of the mass fraction of manganese in alloyed steels. The method is applicable to mass fractions of manganese between 2 % and 25 %. Vanadium and cerium interfere with the measurement. If the mass fraction of cerium in the sample is l

18、ess than 0,01 %, or the mass fraction of vanadium in the sample is less than 0,005 %, the interference is negligible. If the mass fraction of cerium in the sample is greater than 0,01 %, or the mass fraction of vanadium in the sample is greater than 0,005 %, a theoretical correction is necessary. 2

19、Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 648, Laboratory glasswar

20、e Single-volume pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 3696, Water for analytical laboratory use Specification and test methods ISO 4942, Steel and iron Determination of vanadium content N-BPHA spectrophotometric method ISO 4947:1986, Steel and cast iron Determination

21、 of vanadium content Potentiometric titration method ISO 9647:1989, Steel and iron Determination of vanadium content Flame atomic absorption spectrometric method ISO 14284:1996, Steel and iron Sampling and preparation of samples for the determination of chemical composition 3 Principle Dissolution o

22、f a test portion in appropriate acids. Addition of phosphoric acid. Oxidation of manganese to manganese(III) in phosphoric acid medium with ammonium nitrate. Visual titration of manganese(III) with ferroammoniumdisulfate standard solution with N-phenylanthranilic acid as the indicator. Alternatively

23、, potentiometric titration with ferroammoniumdisulfate standard solution. If the sample contains vanadium and cerium, the mass fraction of manganese shall be corrected. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only grade 2 water as specified in ISO 3696. 4

24、.1 Ammonium nitrate, NH4NO3. BS ISO 18632:2010ISO 18632:2010(E) 2 ISO 2010 All rights reserved4.2 Urea. 4.3 Phosphoric acid, approximately 1,69 g/ml. 4.4 Nitric acid, approximately 1,42 g/ml. 4.5 Hydrochloric acid, approximately 1,19 g/ml. 4.6 Sulfuric acid, diluted 1+3. 4.7 Sulfuric acid, diluted 5

25、+95. 4.8 N-phenylanthranilic acid solution, C6H5NHC6H4COOH, approximately 2 g/l. Dissolve 0,20 g of N-phenylanthranilic acid and 0,20 g of sodium carbonate in 100 ml of water and filter. 4.9 Potassium dichromate solution, 0,002 50 mol/l. Weigh 0,735 5 g of high-purity potassium dichromate which shal

26、l be previously dried at 150 C for at least 2 h and cooled in a desiccator. Put the weighed mass in a 250 ml beaker and dissolve it in water. Transfer the solution quantitatively into a 1 000 ml one-mark volumetric flask, dilute to the mark with water and mix. 4.10 Manganese standard solution, corre

27、sponding to 1,00 g of Mn per litre. Weigh, to the nearest 0,1 mg, 1,000 g of pure manganese metal purity W 99,9 % (mass fraction). Place it in a 250 ml beaker and add 40 ml of hydrochloric acid (4.5). Cover with a watch glass and heat gently until complete dissolution. Cool and transfer the solution

28、 quantitatively to a 1 000 ml one-mark volumetric flask, dilute to the mark with water and mix. 1 ml of this standard solution contains 1,00 mg of Mn. 4.11 Ferroammoniumdisulfate solution, standard volumetric solution, 0,015 mol/l. 4.11.1 Preparation of the solution. Dissolve 5,9 g of ferroammoniumd

29、isulfate (NH4) Fe(SO4)26H2O in 1 000 ml of sulfuric acid (4.7) and mix. 4.11.2 Standardization of the solution (to be carried out just before use). 4.11.2.1 Visual titration method. 4.11.2.1.1 Titration. Transfer three portions of 20,00 ml of the potassium dichromate solution (4.9) to three 250 ml c

30、onical flasks. Add 20 ml of sulfuric acid (4.6), 5 ml of phosphoric acid (4.3). Add water up to a volume of approximately 150 ml. Proceed as specified in 7.2.2.1. Calculate the mean of the three values of the ferroammoniumdisulfate solution volume, V1. The difference between the values should not ex

31、ceed 0,05 ml. 4.11.2.1.2 Correction for N-phenylanthranilic acid. Transfer three portions of 5,00 ml of the potassium dichromate solution (4.9) to three 250 ml conical flasks. Add 20 ml of sulfuric acid (4.6) and 5 ml of phosphoric acid (4.3). Titrate the solution with the ferroammoniumdisulfate sol

32、ution (4.11.1) until the end point is approached1). Add 2 drops of N-phenylanthranilic acid solution (4.8), continue the titration until disappearance of the purplish red color and 1) The purplish red colour of the solution becomes light. BS ISO 18632:2010ISO 18632:2010(E) ISO 2010 All rights reserv

33、ed 3record the volume added. Add 5 ml more of potassium dichromate solution (4.9), titrate with the ferroammoniumdisulfate solution (4.11.1) until the end point and record the volume added again. The mean of the differences between the volumes of the two titrations is the corrected value of V0. 4.11

34、.2.1.3 Calculation. The corresponding concentration, c, in moles per litre (mol/l), of the ferroammoniumdisulfate solution (4.11.1) is given by the equation: 100,015 00 20,00cVV=where V1is the mean volume, in millilitres, of the ferroammoniumdisulfate solution (4.11.1) added; V0is the mean volume, i

35、n millilitres, of the ferroammoniumdisulfate solution (4.11.1) added for correction of N-phenylanthranilic acid. 4.11.2.2 Potentiometric titration method. 4.11.2.2.1 Titration. Transfer three portions of 20,00 ml of the manganese standard solution (4.10) to three 300 ml conical flasks. Add 15 ml of

36、phosphoric acid (4.3). Heat until the surface of the solution calms down2)and white fumes are just given off (controlling the temperature from 200 C to 240 C). Remove the flask from the heater, add 2 g of ammonium nitrate (4.1) immediately and shake the conical flask to remove nitrogen oxide. Nitrog

37、en oxide must be eliminated thoroughly by blowing with a pipette or by adding 0,5 g to1,0 g of urea (4.2). Wait for 1 min to 2 min. Cool the solution to 80 C to 100 C. Transfer the solution to a 400 ml beaker. Add 60 ml of sulfuric acid (4.7) and mix. Make up the volume to approximately 150 ml and c

38、ool to room temperature. Proceed as specified in 7.2.2.2. Calculate the mean of the three values of the ferroammoniumdisulfate solution volume, V2. The difference between the values should not exceed 0,05 ml. 4.11.2.2.2 Calculation. The corresponding concentration, c1, in moles per litre, of the fer

39、roammoniumdisulfate solution (4.11.1) is given by the equation: 121,00 20,0054,94cV=where V2is the mean volume, in millilitres, of the ferroammoniumdisulfate solution (4.11.1) required to titrate the manganese solution; 54,94 is the molar mass, in grams per mole, of manganese. 2) A stage where no bu

40、bble is observed on the surface of the solution. BS ISO 18632:2010ISO 18632:2010(E) 4 ISO 2010 All rights reserved5 Apparatus All volumetric glassware shall be class A, in accordance with ISO 648 or ISO 1042, as appropriate. Ordinary laboratory apparatus shall be used, and also a potentometric titra

41、tion device, consisting of a) an indicator electrode, of bright platinum, which shall be kept in a clean, highly polished condition, and b) a reference electrode, of silver/silver chloride, calomel or mercury(I) sulfate NOTE A redox electrode can also be used. 6 Sampling and samples Carry out sampli

42、ng in accordance with ISO 14284 or appropriate national standards for steel. 7 Procedure 7.1 Test portion Weigh, to the nearest 0,000 1 g, a test portion of the sample in accordance with Table 1. Table 1 Test portion Expected mass fraction of manganese % Mass of test portion g 2 to 5 0,5 5 to 15 0,2

43、0 15 to 25 0,10 7.2 Determination 7.2.1 Preparation of the test solution Transfer the test portion (7.1) to a 300 ml conical flask. Add 15 ml of phosphoric acid (4.3) first add 15 ml of aqua regia, hydrochloric acid (4.5) + nitric acid (4.4) = 3 + 1, for some high-alloy steels and heat gently until

44、effervescence ceases. Decompose the carbides by the addition of nitric acid (4.4) drop by drop. Continue heating until the surface of the solution calms down2)and white fumes are just given off (controlling the temperature from 200 C to 240 C). Remove the flask from the heater, add 2 g of ammonium n

45、itrate (4.1) immediately and shake the conical flask to remove nitrogen oxide. Nitrogen oxide must be eliminated thoroughly by blowing with a pipette or by adding 0,5 g to 1,0 g of urea (4.2). Wait for 1 min to 2 min. Cool the solution to 80 C to 100 C. 7.2.2 Titration 7.2.2.1 Visual titration Add 6

46、0 ml of sulfuric acid (4.7) to the test solution (7.2.1) and mix. Make up the volume to approximately 150 ml and cool to room temperature. BS ISO 18632:2010ISO 18632:2010(E) ISO 2010 All rights reserved 5Titrate the solution with the ferroammoniumdisulfate solution (4.11) until the end point is appr

47、oached. Add 2 drops of N-phenylanthranilic acid (4.8). Continue the titration until the purplish red colour of the solution just disappears. Record the volume, V3, of the ferroammoniumdisulfate solution (4.11) added. 7.2.2.2 Potentiometric titration Transfer the test solution (7.2.1) to a 400 ml bea

48、ker. Add 60 ml of sulfuric acid (4.7) and mix. Make up the volume to approximately 150 ml and cool to ambient temperature. Place the beaker containing the solution on the magnetic stirrer and start it. Immerse the indicator and reference electrodes 5 a) and 5 b) or a redox electrode in the solution.

49、 Titrate slowly with the ferroammoniumdisulfate solution (4.11) until the end point is approached. Continue the titration in 0,05 ml or one drop increments, and record the volume added and potential readings when equilibrium is reached after each incremental addition. Continue the titration through the end point. Determine the end point by the titration curve or the first derivative of the potential difference divided by the first derivative of the volume of titrant (dE/dV). Record th