1、BRITISH STANDARDBS EN ISO 4491-3:2006Metallic powders Determination of oxygen content by reduction methods Part 3: Hydrogen-reducible oxygen The European Standard EN ISO 4491-3:2006 has the status of a British StandardICS 77.160g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g
2、53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN ISO 4491-3:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 April 2006 BSI 2006ISBN 0 580 48153 0Natio
3、nal forewordThis British Standard is the official English language version of EN ISO 4491-3:2006. It is identical with ISO 4491-3:1997.The UK participation in its preparation was entrusted to Technical Committee ISE/65, Sintered metal components, which has the responsibility to: A list of organizati
4、ons represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence
5、 Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself
6、confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulga
7、te them in the UK.Summary of pagesThis document comprises a front cover, an inside front cover, the EN ISO title page, the EN ISO foreword page, the ISO title page, pages ii and iii, a blank page, pages 1 to 9 and a back cover.The BSI copyright notice displayed in this document indicates when the do
8、cument was last issued.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 4491-3April 2006ICS 77.160English VersionMetallic powders - Determination of oxygen content by reductionmethods - Part 3: Hydrogen-reducible oxygen (ISO 4491-3:1997)P
9、oudres mtalliques - Dosage de loxygne par lesmthodes de rduction - Partie 3: Oxygne rductible parlhydrogne (ISO 4491-3:1997)Metallpulver - Bestimmung des Sauerstoffgehaltes durchReduktionsverfahren - Teil 3: WasserstoffreduzierbarerSauerstoff (ISO 4491-3:1997)This European Standard was approved by C
10、EN on 9 March 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may
11、 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 by translationunder the responsibility of a CEN member into its own language and notified to the Centra
12、l Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
13、 Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any mea
14、ns reservedworldwide for CEN national Members.Ref. No. EN ISO 4491-3:2006: EForeword The text of ISO 4491-3:1997 has been prepared by Technical Committee ISO/TC 119 “Powder metallurgy” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 4491-3:2006 by Techni
15、cal Committee CEN/SS M11 “Powder metallurgy“, the secretariat of which is held by CMC. This 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 October 2006, and conflicting national standards shall be wit
16、hdrawn at the latest by October 2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungar
17、y, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 4491-3:1997 has been approved by CEN as EN ISO 4491-3:2006 without any modifications
18、. EN ISO 4491-3:2006INTERNATIONAL STANDARD IS0 4491-3 Second edition 1997-04-O 1 Metallic powders - Determination of oxygen content by reduction methods - Part 3: Hydrogen-reducible oxygen Poudres m L 9 C ? E Key: A H2 supply unit (5.1) B Purifier (5.2) C N2 (or argon) supply unit (5.3) D Gas-select
19、ion valve (5.4) E Final gas drying unit (5.5) F Reduction tube (5.6) G Furnace (5.7) H Boat (5.8) I Catalytic converter (5.9) J By-pass circuit (5.10) K Titration flask (5.11) L End-point detector (5.12) M Burette (5.13) M . Figure 2 - Schematic arrangement of the apparatus for method 2 EN ISO 4491-
20、3:2006IS0 4491-3: 1997(E) IS0 . 5.5 Final gas drying unit (E), containing desiccant (4.5). 5.6 Reduction tube (F), gas-tight, made of quartz or refractory material (for example dense alumina), meeting one of the following sets of specifications: a) A tube closed at one end with an internal diameter
21、of 27 mm to 30 mm and a length of about 400 mm with two smaller quartz tubes of diameter 5 mm to 6 mm and lengths 60 mm to 80 mm and 200 mm to 240 mm, respectively, arranged as shown in figure 3. This arrangement is inserted into the first drying furnace and then into the reduction furnace. b) An op
22、en-ended tube with an internal diameter of about 20 mm, a length of 1 m, and a gas inlet and outlet. This tube is permanently inserted in the two furnaces 5.7 Two furnaces (G), one for drying the test portion and the other for oxide reduction, with temperature control systems capable of maintaining
23、the temperature in the part of the tube containing the boat (5.8) within the specified temperature tolerances. NOTE - If available, one furnace combining both these functions may be used. 5.8 Boat (H), preferably of high-alumina ceramic, with a polished surface and of a suitable size such that no mo
24、re than half is filled by the test portion. The boat shall be conditioned in hydrogen at 900 “C to 1 100 OC for at least 1 h and stored in a desiccator before use. 5.9 Catalytic converter (I), comprising a glass tube filled with a nickel catalyst, and a furnace with temperature control system capabl
25、e of maintaining the temperature in the glass tube at 380 “C. The catalyst shall be kept permanently under hydrogen. 5.10 By-pass circuit (J), used when the catalytic converter (5.9) is not needed, and designed so that air cannot reach the catalyst. 5.11 Titration flask (K), of capacity 200 ml to 30
26、0 ml, with magnetic stirrer or equivalent arrangement, equipped with two platinum electrodes if the end-point is to be detected electrometrically. 5.12 End-point detector (L), for use if the end-point is to be detected electrometrically. (See figure 4.) 5.13 Burette (M), of capacity 25 ml and with a
27、 fine tip graduated in 0,05 ml divisions, and protected from atmospheric moisture by a guard tube filled with desiccant (4.5). The equipment described in 5.11, 5.12 and 5.13 may be modified, or any commercially available Karl Fischer, titration apparatus used, provided that the requirements of IS0 7
28、60 are fulfilled. 6 Sampling The powder shall be tested in the as-received condition. 4 EN ISO 4491-3:2006 IS0 IS0 4491=3:1997(E) Key: F Reduction tube (5.6) H Boat (5.8) Figure 3 - Examples of reduction tubes I- t-* -,-,-,-t-I-t-g-.-*-I-. 1 . I . I t I . I I I l . I . I . I . I t . I . I . I t I j
29、eylAxo-ammefer I R Variable resistor t-t-,-.- .-.-,-.-.-t-s -,.m,.,-,. s S Switch Figure 4 - Schematic diagram of end-point detector L (see 7.3.4) 5 EN ISO 4491-3:2006 IS0 IS0 4491=3:1997(E) ? Procedure 7.1 Test portion Weigh, to the nearest 0,l mg, a mass of test portion corresponding to the expect
30、ed hydrogen-reducible oxygen content, as indicated in table 1. Table 1 Expected hydrogen-reducible oxygen content % (m/m) From 0,05 to 0,5 From 0,5 to 2,0 From 2,0 to $0 7.2 Test conditions Mass of test portion The reduction temperatures to be applied are shown in table 2. The reduction time at thes
31、e temperatures is about 20 minutes. For each apparatus and optimum reduction time to give complete reduction should be determined experimentally. Table 2 - Reduction temperatures Metal powder Tin bronze Lead bronze Copper lead Lead Tin Silver Copper Iron and steel Cobalt Nickel Tungsten Molybdenum R
32、henium Hardmetal mixture Reduction temperature “C 750+15 6OOUO 600+10 500+10 425klO 55OIklO 85Ok15 1100I!I20 1000+20 100020 100020 11ooL-20 115Ok20 1000+20 each type of powder, the 7.3 Preparation of the apparatus 7.3.1 Set up the apparatus as shown in figure 1 for method 1 or figure 2 for method 2.
33、 Set the temperature of the reduction furnace (see 5.7) to the reduction temperature. For method 1 only, leave the reduction tube 5.6 a) outside the furnace. 7.3.2 Rinse the burette (5.13) with the Karl Fischer reagent (4.2) to ensure that no moisture, which could change the titre of the reagent, is
34、 present. Discard the rinsings and fill the burette with the Karl Fischer reagent. 7.3.3 Add the methanol (4.1) to the titration flask (5.1 I), %aking care to adjust the liquid level so that %he inlef %ube (and the electrodes if used) are below the surface of the liquid. Start the stirrer and %i%ra%
35、e with the Karl Fischer reagent to the visual end-point to neutralize any traces of water in the methanol. 6 EN ISO 4491-3:2006 IS0 IS0 4491=3:1997(E) 7.3.4 If electrometric end-point detection is used (see figure 4), short-circuit the electrodes by switch S of the electrometric end-point detector (
36、5.12) and adjust the variable resistor R to give a current to 120 PA on the micro- ammeter N. Re-open switch S. 7.3.5 For both methods, adjust the nitrogen flow rate to a% leas% 30 I/h and allow it to flow for IO min. Change the gas flow from nitrogen to hydrogen by the gas-selection valve (5.4) and
37、 adjust the flow rate to about 25 I/h. For method 1 only, inser% the reduction tube 5.6 a) in the reduction furnace and leave for IO min. Change the gas flow back to nitrogen. Withdraw the tube and cool to room temperature. 7.3.6 Again titrate the methanol to the visual end-point to neutralize any t
38、races of water released during conditioning. 7.3.7 Check the condition, including the gas-tightness, of the apparatus by the blank test specified in 7.4. WARNING - Do not stop the hydrogen flow while the tube is still hot, except when changing back to nitrogen. 7.4 Blank test For each series of dete
39、rminations, carry out a blank test on an empty boa% (5.8), following the same procedures as used for the test portion. NOTE - An apparatus in good condition should yield a result for the blank test of approximately 1 mg of oxygen for a heating period of 20 min. If the result is much higher, or if va
40、riable results are obtained, the apparatus should be checked for leaks. 7.5 Determination In both methods, if it is necessary to eliminate carbon interference, bring the catalytic converter (5.9) into operation by preheating it to 380 OC k 10 OC and opening it to the system just before the boa% is p
41、laced in the reduction zone. At the end of the determination, ensure that the catalytic converter is by-passed before the hydrogen supply is changed to nitrogen. NOTE - If required, the moisture content of the sample can be determined by recording the volume of Karl Fischer reagent used to titrate t
42、he water released during the drying period. 7.5.1 Method 1: Closed-end reduction tube Open the reduction tube 5.6 a) and insert the boa% containing the weighed test portion. Close the tube and purge with dry nitrogen at a flow rate of at least 30 I/h to expel the air introduced with the test portion
43、. If the purge time has no% been previously established, allow 10 min. Titrate the methanol to the visual end-point. Adjust the nitrogen flow to 25 I/h and insert the tube into the furnace a% a temperature of 170 OC V2 is the volume, in millilitres, of Karl Fischer reagent used for the blank test; m
44、 is the mass, in milligrams, of the test portion; n is the titre, in milligrams of oxygen per millilitre, of the Karl Fischer reagent. 8.2 The calculation and expression of the test results are made according to table 3. Table 3 Hydrogen-reducible oxygen content % (mlm) Calculation of test results t
45、o the nearest % s 0,2 0,Ol 0,2 6 0,5 0,Ol 0,5 s I,0 0,Ol I,0 0,Ol 9 Test report The test report shall include the following information: a) a reference to this part of IS0 4491; Maximum permissible difference between two determinations Expression of results to the nearest % max. 0,Ol % (absolute val
46、ue) max. 5 % of mean max. 5 % of mean max. 5 % of mean 0,Ol 0,02 0,05 091 b) all details necessary for the identification of the test sample; 8 EN ISO 4491-3:20060 IS0 IS0 4491=3:1997(E) c) the drying time and temperature; d) the reduction time and temperature; e) whether the catalytic converter was
47、 used; f) the results obtained; g) details of any operations not specified in this part of IS0 4491 or in the International Standards to which reference is made, as well as details of any operations regarded as optional; h) details of any occurrence which may have affected the results. EN ISO 4491-3
48、:2006BS EN ISO 4491-3:2006BSI389 Chiswick High RoadLondonW4 4ALBSI British Standards InstitutionBSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.Revisio
49、nsBritish Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions.It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: +44 (0)20 8996 9000. Fax: +44 (0)20 8996 7400.BSI offers members an individual updatin
