1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 4491-4:2013Metallic powders Determination of oxygencontent by reduction methodsPart 4: Total oxygen by reduction-extraction(ISO 4491-4:2013)BS EN ISO 4491-4:2013 BRITIS
2、H STANDARDNational forewordThis British Standard is the UK implementation of EN ISO4491-4:2013. It supersedes BS EN 24491-4:1993 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/65, Sintered metal components.A list of organizations represented on thi
3、s committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 78920 5ICS 77.
4、160Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 May 2013.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NO
5、RM EN ISO 4491-4 May 2013 ICS 77.160 Supersedes EN 24491-4:1993English Version Metallic powders - Determination of oxygen content by reduction methods - Part 4: Total oxygen by reduction-extraction (ISO 4491-4:2013) Poudres mtalliques - Dosage de loxygne par les mthodes de rduction - Partie 4: Oxygn
6、e total par rduction-extraction (ISO 4491-4:2013) Metallpulver - Bestimmung des Sauerstoffgehaltes durch Reduktionsverfahren - Teil 4: Gesamt-Sauerstoffgehalt durch Reduktionsextraktion (ISO 4491-4:2013) This European Standard was approved by CEN on 2 April 2013. CEN members are bound to comply with
7、 the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Manage
8、ment Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same stat
9、us as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta
10、, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights o
11、f exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 4491-4:2013: EBS EN ISO 4491-4:2013EN ISO 4491-4:2013 (E) 3 Foreword This document (EN ISO 4491-4:2013) has been prepared by Technical Committee ISO/TC 119 “Powder metallurgy“. This European Stan
12、dard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2013, and conflicting national standards shall be withdrawn at the latest by November 2013. Attention is drawn to the possibility that some of the elements o
13、f this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 24491-4:1993. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following coun
14、tries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Po
15、land, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 4491-4:2013 has been approved by CEN as EN ISO 4491-4:2013 without any modification. BS EN ISO 4491-4:2013ISO 4491-4:2013(E) ISO 2013 All rights reserved iiiCont
16、ents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Principle 14 Apparatus and materials 25 Test portion 26 Procedure. 36.1 General . 36.2 Blank test and calibration 36.3 Test 47 Expression of results 47.1 Permissible tolerances . 47.2 Final result 48 Test report . 4Annex A (infor
17、mative) Examples of conditions of extraction for selected metal powders 5BS EN ISO 4491-4:2013ISO 4491-4:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards i
18、s 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. International organizations, governmental and non-governmental, in liaison with ISO, also take par
19、t 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 rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to pre
20、pare 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 at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that s
21、ome 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 4491-4 was prepared by Technical Committee ISO/TC 119, Powder metallurgy, Subcommittee SC 2, Sampling and testing methods for powders (includi
22、ng powders for hardmetals).This second edition cancels and replaces the first edition (ISO 4491-4:1989), of which it constitutes a minor revision.ISO 4491 consists of the following parts, under the general title Metallic powders Determination of oxygen content by reduction methods: Part 1: General g
23、uidelines Part 2: Loss of mass on hydrogen reduction (hydrogen loss) Part 3: Hydrogen-reducible oxygen Part 4: Total oxygen by reduction-extractioniv ISO 2013 All rights reservedBS EN ISO 4491-4:2013ISO 4491-4:2013(E)IntroductionThe determination of the oxygen content of metallic powders is of the u
24、tmost importance in many fields of powder metallurgy.The standard methods described in ISO 4491-2 and ISO 4491-3 do not give the total oxygen content of the sample, as some oxygen-containing constituents are not reduced by hydrogen.Therefore, a standard method for the determination of the total oxyg
25、en content is needed. The most frequently used method is reduction-extraction. It can be carried out with various commercially available instruments working according to different principles of extraction and measurement.It should be emphasized that the results of the analysis depend on the type of
26、equipment used and on the test parameters selected. However, as indicated in Clauses 3 to 6, it is always possible, for a given type of metal powder, to optimize the test conditions to obtain reproducible and accurate results with any of the commercially available instruments, provided they are desi
27、gned for testing the metal powder considered.It is not possible to standardize one or more particular instruments. However, certain basic points of procedure are recommended for the analysis of metallic powders (see Clause 6).NOTE The reduction-extraction method is also applicable to nitrogen determ
28、ination and certain instruments permit simultaneous measurement of oxygen and nitrogen contents. However, the determination of nitrogen is not covered by this International Standard. ISO 2013 All rights reserved vBS EN ISO 4491-4:2013BS EN ISO 4491-4:2013Metallic powders Determination of oxygen cont
29、ent by reduction methods Part 4: Total oxygen by reduction-extraction1 ScopeThis part of ISO 4491 specifies a method for the determination of the total oxygen content of metallic powders by reduction-extraction at high temperature.By agreement, this method is also applicable to the determination of
30、the total oxygen content of sintered metal materials.The method is applicable to all powders of metals, alloys, carbides, and mixtures thereof which are non-volatile under the test conditions. The sample may be in powder or compact form.The analysis is carried out on the powder as supplied, but the
31、method is not applicable if the powder contains a lubricant or binder. If such substances are present, the method may be used only if they can first be completely removed by a method not affecting the oxygen content of the powder.This part of ISO 4491 is to be read in conjunction with ISO 4491-1.2 N
32、ormative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendment
33、s) applies.ISO 4491-1, Metallic powders Determination of oxygen content by reduction methods Part 1: General guidelines3 PrincipleA test portion of the sample is heated in a graphite crucible at high temperature, either under vacuum or in a flow of an inert carrier gas. Oxygen in the sample is conve
34、rted to oxides of carbon. These are extracted and transformed completely to either carbon monoxide or carbon dioxide, which is determined by a suitable gas analysis method.The methods used in practice to determine the total oxygen content have the following features:a) Environment in the reaction ch
35、amber: Vacuum or flow of inert gas (nitrogen, argon, helium).b) Graphite crucible: Individual, i.e. used only for one test portion, or cumulative, i.e. the same crucible is used for the analysis of several successive test portions.INTERNATIONAL STANDARD ISO 4491-4:2013(E) ISO 2013 All rights reserve
36、d 1BS EN ISO 4491-4:2013ISO 4491-4:2013(E)c) Reaction medium: Dry, i.e. the test portion alone is poured into the graphite crucible, the reduction being carried out in the solid state if the metal being analysed does not melt, or metal bath, i.e. in order to accelerate the reduction of certain metal
37、s it is advisable to prepare first a bath of a fusible metal (for example platinum, tin, iron, nickel) capable of dissolving both carbon and the metal in the test portion.d) Heating: Continuous, i.e. the test portion is introduced into the crucible previously heated to the reaction temperature, the
38、reduction taking place over a fixed period of time, of the order of several minutes, or pulse, i.e. the cold crucible containing the test portion is heated by injecting, over a period of a few seconds, a high-power pulse of energy, reduction taking place very rapidly at the high peak temperature (up
39、 to 3 000 C) which results.e) Determination of oxygen:Several methods for measuring either CO or CO2are available. In both cases a chemical conversion device is used to ensure that the oxygen to be determined is transformed completely into either CO or CO2. The analytical methods commonly used are v
40、olumetric (for carbon monoxide), chromatography (for carbon monoxide), infrared absorption (for carbon monoxide), thermal conductivity (for carbon monoxide and carbon dioxide), coulometry (for carbon dioxide).4 Apparatus and materialsThe main elements of an apparatus suitable for determining the oxy
41、gen content of a metallic powder are the following: crucibles, machined from high purity graphite; a device to degas the graphite crucible at high temperature; a device to introduce the test portion and degas it under inert gas or in vacuum at ambient temperature; a device for gas extraction in acco
42、rdance with a predetermined temperature cycle; a purification train to remove water; a measuring device for the determination of the carbon monoxide or carbon dioxide.The materials needed will depend on the type of equipment used, for example high purity inert gas (helium or argon).Calibration of th
43、e measuring device, when necessary, requires high purity gas, carbon monoxide, carbon dioxide, or certified metallic reference materials.5 Test portionThe analysis shall be carried out on one or several test portions. The number of test portions required to reach the required precision can be determ
44、ined by a gauge repeatability and reproducibility study. If a gauge 2 ISO 2013 All rights reservedBS EN ISO 4491-4:2013ISO 4491-4:2013(E)repeatability and reproducibility study is not made, the analysis shall be carried out on two test portions. Several methods can be used to prepare the test portio
45、n prior to its introduction into the apparatus.a) The test portion is weighed directly into the degassed crucible.b) A quantity of the powder sample is uniaxially compacted in a small cylindrical die, without any lubricant or binder, under a pressure of 100 MN/mm2to 200 MN/mm2. The mass of the compa
46、ct is determined.c) A quantity of the powder sample is enclosed in a small capsule of known weight made of platinum, tin, nickel, or iron-nickel foil of high purity. The whole capsule is weighed. The oxygen content of the foil shall be known or determined previously.d) In the case of a compact, a su
47、itable fragment of the sample is weighed as the test portion.All weighings shall be to the nearest 0,1 mg.A metal foil capsule may be used solely to facilitate the introduction of the sample into the apparatus. In this case, the weight of the capsule shall be kept to a minimum.Alternatively, the met
48、al of the capsule can constitute the metal bath needed for convenient extraction; in this case, the mass of the capsule is chosen to give the bath/test-portion mass ratio recommended for the particular analysis.When the graphite crucible is used with a metal bath for several consecutive analyses, it
49、 is necessary to degas the bath prior to the beginning of each extraction operation.The bath/test-portion mass ratio is maintained larger than the recommended minimum value, if necessary, by the periodic introduction of fragments of metal followed by degassing of the bath.The mass of the test portion shall be selected depending on the sensitivity of the apparatus used and the expected oxygen content. Frequently, a mass between 0,1 g and 1 g is chosen.6 Procedure6.1 GeneralFor the reason given in the introduction, it is not p
