1、 BRITISH STANDARD i Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss of mass on hydrogen reduction (hydrogen loss) The European Standard EN IS0 4491-2 1999 has the status of a British Standard ICs 77.160 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY C
2、OPYRIGHT LAW BS EN IS0 449 1-2: 1999 nl U- -= um ST3=BSI BS EN IS0 4491-2-ENGL L999 m Lh24bb9 0795Li7L 8Tb m BS EN IS0 4491-2:1999 Amd. No. Date I National foreword Comments This British standard is the English language version of EN IS0 4491-21999. It is identical with IS0 4491-2 1997. It supersede
3、s BS EN 21491-2 1993 which is withdram. The UK participation in its preparation was entrusted to Technical Committee ISE5, Sintered metai components, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible internationalEuropean committee any enquiries on
4、 the interpretation, or proposals for change, and keep the UK interests informed - monitor related international and European developments and promulgate them in the UK. A iist of organizations represented on this committee can be obtained on request to its secrem. Cross-references Attention is dram
5、 to the fact that CEN and CENELEC Standards normally include an annex which lists nonnative references to internationai publications with their corresponding European publications. The British Standards which implement international or European pubhations referred to in this document may be found in
6、 the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index“, or by using the “Find“ facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are
7、 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, the EN IS0 title page, the EN IS0 foreword page, the IS0 title page, page ii, pages
8、 1 to 6, the annex ZA page, and a back cover. The BSI copyright notice displayed in this document indicates when this document was last issued. This Briish Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Commi
9、ttee and comes into effect on 15 September 1999 O BSI 09-1999 ISBN O 580 32775 2 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 4491-2 July 1999 ICs 7.160 Supersedes EN 24491 -2: 1993 English version Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss of
10、mass on hydrogen reduction (hydrogen loss) (I SO 449 1 -2: 1 997) Poudres mtalliques - Dosege de loxygne par les mthodes de Muciion - Partie 2: Perte de masse par rduction dans Ihydmgne (perte dans Ihydroghe) (IS0 4491 -2 1997) Metailpuhrer - Bestimmung des Sauerstoffanteils durch Reduktionsverfahre
11、n - Teil 2: Massenveriust durch Reduktion mit Wasserstoff (IS0 4491 -2:1997) This European Standard was approved by CEN on 3 June 1999. CEN members are bound to comply with the CEWCENELEC Intemal Regulations which stipulate the conditions for giving this European Standard the Status of a national st
12、andard without any alteration. Up-to-date lists and biblibgraphical references concerning such national standards may be obtained on application to the Central Secretafiat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other
13、 language made by 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, Czech Republic, Denmark, Finland, France, Germany, Gre
14、ece, Iceland. Ireland. Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMlTiEE FOR STANDARDIZATION COMITE EUROPEEN DE NORMALISATION EUROPISCHES KOMITEE FOR NORMUNG Centrai Secretariat: NO de Stassart, 36 8-1050 Bni-18 Q 1999 CEN All rights
15、of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN IS0 4491-2:1999 E Foreword The text of the International Standard from Technical Committee ISOEC 119 “Powder metallurgy“ of the International Organization for Standardization (ISO) has been taken ov
16、er as an European Standard by CEN/CS. This European Standard replaces EN IS0 24491-2:1993. 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 January 2000, and conflicting national standards shall be
17、 withdrawn at the latest by January 2000. According to the CENEENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, It
18、aly, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of the International Standard IS0 4491-2:1997 has been approved by CEN as a European Standard without any modification. NOTE: Normative references to International Standards
19、 are listed in annex ZA (normative). SD=BSI BS EN IS0 99L-Z-ENGL 1949 LbZqbbS 0759L:Li 505 B EN IS0 4491-2:1999 I NT E RN AT I ON AL STANDARD IS0 4491 -2 Second edition 1997-04-01 Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss of mass on hydrogen reduction (hy
20、drogen loss) Foudres mtalliques - Dosage de /oxygne par les mthodes de rduction - Partie 2: Perte de masse par rduction dans /hydrogne (perte dans /hydrogne) Reference number IS0 4491-2:1997(E) I EN IS0 4491-2:1999 Foreword IS0 (the Intemational Organization for Standardization) is a worldwide feder
21、ation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the tight to be represented on that commit
22、tee. Intemational organizations, governmental and non- governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Drai Intemational Standards adopted by the techn
23、ical committees are circulated to the member bodies for voting. Publication as an Intemational Standard requires approval by at least 75 % of the member bodies casting a vote. Intemational Standard IS0 4491 -2 was prepared by Technical Committee ISO/TC 1 19, Powder mtallugy, Subcommittee SC 2, Sampl
24、ing and testing methods for powders (including powders for hardmetals). This second edition cancels and replaces the first edition (IS0 4491 -2:1989), table 1 and clause 7 of which have been technically revised. IS0 4491 consists of the following parts, under the general title Metallic powders - Det
25、emination of oxygen content by reduction methods: Par? I: General guidelines - Part 2: Loss of mass on hydrogen reduction (hydrogen loss) - Palt 3: Hydrogen-reducible oxygen - Par? 4: Total oxygen by reduction-extraction Annex A forms an integral part of this part of IS0 4491. Ikscilpturs: powder me
26、tallurgy, metallic powder, chemical analysis, determination of content, oxygen, reduction methods. ii EN IS0 4491-21999 Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss of mass on hydrogen reduction (hydrogen loss) 1 scope This part of Is0 4491 specifies a metho
27、d for the datemiination of the relative loss of mass which a metallic powder undergoes when heated in a stream of pure dry hydrogen under specified conditions. The purpose of this test is to evaluate a chemical powder characteristic which is of importance to the powder metallurgical industry. The te
28、st is not intended as a means for the determination of the content of specific elements. (See annex A and IC0 4491 -1 .) The test method is applicable to unalloyed, partially alloyed and completely alloyed powders of the metals listed in table 1 (see 6.1). It is not applicable to lubricated powders
29、or to mixtures of metal powders. The results can be influenced by the presence of reducible, oxidizable or volatile metals, metalloids or compounds (see annex A). The results obtained on such powders shall be used with caution and their interpretation shall be subject to agreement between supplier a
30、nd user. This part of IS0 4491 shall be read in conjunction with IS0 4491 -1. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this part of IS0 4491. At the time of publication, the edition indicated was valid. All stand
31、ards are subject to revision, and parties to agreements based on this part of IS0 4491 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 4491-1:1
32、989, Metallic powders - Determination of oxygen content by reduction methods - Part 1: General guidelines. 3 Reagents and materials 3.1 Hydrogen, with a maximum oxygen content of 0,005 % (m/m) and a dew point not higher than - 45 OC. 3.2 Nitrogen orargon, with a maximum oxygen content of 0,005 YO (m
33、im) and a dew point not higher than - 45 “C. (See also 6.3, third paragraph.) 1 4 Apparatus An example of suitable test arrangement is shown schematically in figure 1. 4.1 Laboratory balance, of sufficient capacity, and capable of weighing to an accuracy of 0,l mg. 4.2 Eli9ctricaliy heated tubular f
34、urnace, that can be continuously operated at the appropriate temperatures given in table 1 and that has a control system capable of maintaining the temperature in that part of the tube containing the boat (4.5) to within the temperature tolerance stated in table i. NOTE - When testing magnetic powde
35、rs, i is recommended that wire-wound furnaces shall be wound non-inductively. 4.3 Gas-tight tube, of quartz or refractory material (for example dense alumina). The inside diameter of the tube shall be between 25 mm and 40 mm and its length such that it extends about 200 mm beyond each end of the fur
36、nace. When a large number of hydrogen loss determinations is to be carried out, a larger furnace than that described in this part of IS0 4491, and one which permits several test portions to be tested simultaneously, may be used, provided that the temperature and time conditions shown in table 1 are
37、fulfilled and the results obtained are in agreement with those obtained when the test is carried out with the preferred apparatus. 4.4 Totally enclosed thermocouple, for example platinum/platinum-rhodium, and an indicating or recording instrument, permitting the measurement of temperature with an ac
38、curacy of 5 OC. If for some reason it is desirable to place the thermocouple outside the reduction tube, this is acceptable. But in this case, a preliminary calibration shall be made with a second thermocouple placed inside the tube in order to ascertain that the temperature of the test sample is in
39、 accordance with the values and tolerances specified in table i. 4.5 Boat, preferably of high-alumina ceramic with a polished surface. Other materials, for example quartz and nickel, may be used when test conditions allow. The boat shall be of such dimensions, for example 75 mm long and 12 mm wide,
40、that the thickness of the powder, when uniformly distributed, does not exceed 3 mm. New boats shall be pretreated in a stream of hydrogen at the test temperature and stored in a desiccator. A boat may be used more than once, provided that it is always used for testing the same metal powder or type t
41、hereof and provided that it is carefully cleaned by mechanical means between determinations and stored in a desiccator. 4.6 Supply unit for hydrogen and either nitrogen or argon, with pressure gauges and flow meters to control the flow of gas. 5 Sampling 5.1 The powder shall be tested in the as-rece
42、ived condition. 5.2 The loss in mass shall be determined on two test portions. 5.3 The mass of the test portion shall be approximately 5 g, except that for powders of low apparent density it may be reduced to comply with the requirements of 4.5 and 6.2. 2 Dimensions in millimetres Figure 1 - Diagram
43、 of suitable test arrangement 3 6 Procedure Carry out two determinations on each test sample. 6.1 Heat the furnace (4.2), with the tube (4.3) inserted, to the temperature indicated in table 1 for the metal powder being tested. Table 1 - Reduction temperatures and times Metal powder Tin bronzez) Tin
44、Silver Copper lead2) Leaded bronzez) Iron and steel Cobalt Nickel Tungsten Molybdenum Rhenium Copper Reduction temperature “C 750 f 15 425 f 10 550 f 10 850 f 15 600f10 600 f 10 1 100f20 1000_+20 1000f20 1000f20 1100f20 1150i20 Reduction time) min 30 30 30 30 10 10 60 60 60 60 60 60 1) These reducti
45、on times are given for guidance purposes only. Shorter times may be applied provided that for each apparatus and for each type of powder experience has shown them to be sufficient to guarantee the completion of the hydrogen loss reactions. 2) Results should be interpreted with care. See annex A, cla
46、use A.6. 6.2 Weigh the boat (4.5) to the nearest Oll mg. Distribute the test portion throughout the boat to a uniform depth not exceeding 3 mm. Weigh the boat with the test portion to the nearest Oll mg. 6.3 Pass nitrogen (3.2) through the tube at a flow rate corresponding to a gas speed of at least
47、 25 mds, as measured in the cooling zone of the tube, for a period of at least 1 min. Insert the boat containing the test portion in the tube and move it until it is at the centre of the uniformtemperature zone of the furnace. The boat shall be moved sufficiently slowiy to prevent ejection of powder
48、 as a result of a high rate of gas evolution. Continue the flow of nitrogen for 1 min. If difficulties are experienced in preventing ejection of powder from the boat, the powder may be pressed (without addition of lubricant) to form a low density compact, or, if such a compact has a very low green s
49、trength, it may be wrapped in oxide-free cooper foil. The copper foil may be used only when the test temperature exceeds the melting temperature of copper. When testing powders that are susceptible to combination with nitrogen (for example chromium-containing alloy steel powder), the purging operations shall be carried out with argon instead of nitrogen. (See 6.5 and 6.6.) 6.4 Start up the flow of hydrogen (3.1) and discontinue the flow of nitrogen. Establish an even flow of hydrogen through the tube, corresponding to a gas speed of at least 25 mm/s in the
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