《BS-EN-24491-4-1993 ISO-4491-4-1989.pdf》由会员分享，可在线阅读，更多相关《BS-EN-24491-4-1993 ISO-4491-4-1989.pdf（14页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS EN 24491-4:1993 ISO 4491-4: 1989 Metallic powders Determination of oxygen content by reduction methods Part 4: Total oxygen by reduction-extraction The European Standard EN 24491-4:1993 has the status of a British Standard UDC 621.762:669-492.2:543.73:546.21 BS EN 24491-4:1993 Th
2、is British Standard, having been prepared under the direction of the Iron and Steel Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 June 1993 BSI 11-1999 The following BSI references relate to the work on this standard: Committee refer
3、ence ISM/65 Special announcement in BSI News January 1993 ISBN 0 580 21918 6 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: AustriaOest
4、erreichisches Normungsinstitut BelgiumInstitut belge de normalisation DenmarkDansk Standardiseringsraad FinlandSuomen Standardisoimisliito, r.y. FranceAssociation franaise de normalisation GermanyDeutsches Institut fr Normung e.V. GreeceHellenic Organization for Standardization IcelandTechnological
5、Institute of Iceland IrelandNational Standards Authority of Ireland ItalyEnte Nazionale Italiano di Unificazione LuxembourgInspection du Travail et des Mines NetherlandsNederlands Normalisatie-instituut NorwayNorges Standardiseringsforbund PortugalInstituto Portugus da Qualidade SpainAsociacin Espao
6、la de Normalizacin y Certificacin SwedenStandardiseringskommissionen i Sverige SwitzerlandAssociation suisse de normalisation United KingdomBritish Standards Institution Amendments issued since publication Amd. No.DateComments BS EN 24491-4:1993 BSI 11-1999i Contents Page Cooperating organizationsIn
7、side front cover National forewordii Foreword2 Introduction3 1Scope3 2Normative reference3 3Principle3 4Apparatus and materials4 5Test portion4 6Procedure4 7Expression of results5 8Test report5 Annex A (informative) Examples of conditions of extraction for selected metal powders6 Annex ZA (normative
8、) Normative references to international publications with their relevant European publications7 National annex NA (informative) Committees responsibleInside back cover National annex NB (informative) Cross-referenceInside back cover Table 15 Table A.16 BS EN 24491-4:1993 ii BSI 11-1999 National fore
9、word This British Standard has been prepared under the direction of the Iron and Steel Standards Policy Committee and is the English language version of EN 24491-4:1993 Metallic powders Determination of oxygen content by reduction methods Part 4: Total oxygen by reduction-extraction, published by th
10、e European Committee for Standardization (CEN). It is identical with ISO 4491-4:1989, prepared by Technical Committee 119, Power metallurgy, of the International Organization for Standardization (ISO) with the active participation of the UK. A British Standard does not purport to include all the nec
11、essary provisions of a contract. Users of British Standards are 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, pages i and ii, the
12、EN title page, pages 2 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 24491-4 Apri
13、l 1993 UDC 621.762:669-492.2:543.73:546.21 Descriptors: Powder metallurgy, metallic powder, chemical analysis, determination of content, oxygen, reduction methods, extraction methods English version Metallic powders Determination of oxygen content by reduction methods Part 4: Total oxygen by reducti
14、on-extraction (ISO 4491-4:1989) Poudres mtalliques Dosage de loxygne par les mthodes de rduction Partie 4: Oxygne total par rduction-extraction (ISO 4491-4:1989) Metallpulver Bestimmung des Sauerstoffgehaltes durch Redukdtionsverfahren Teil 4: Gesamt-Sauerstoffgehalt durch Reduktionsextraktion (ISO
15、4491-4:1989) This European Standard was approved by CEN on 1993-04-02. CEN members are bound to comply with 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 bibliograph
16、ical references concerning such national standards may 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 translation under the responsibility of a CEN
17、 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, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain,
18、 Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1993 Copyright reserved to CEN members Ref. No. EN 24491-4:1993 E EN 24491-4:1993 BSI 11-1999 2 F
19、oreword In 1992, ISO 4491-4:1989 Metallic powders Determination of oxygen content by reduction method Part 4: Total oxygen by reduction-extraction was submitted to the CEN Primary Questionnaire procedure. Following the positive result of the CEN/CS proposal ISO 4491-4:1989 was submitted to the CEN F
20、ormal Vote. The result of the Formal Vote was positive. 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 1993, and conflicting national standards shall be withdrawn at the latest by October
21、 1993. According to the Internal Regulations of CEN/CENELEC, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United K
22、ingdom. NOTEThe European references to international publications are given in Annex ZA (normative). EN 24491-4:1993 BSI 11-19993 Introduction The determination of the oxygen content of metallic powders is of the utmost importance in many fields of powder metallurgy. The standard methods described i
23、n parts 2 and 3 of this International Standard 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 oxygen content is needed. The most frequently used method is reductio
24、n-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 equipment used and on the test parameters selected. However, as
25、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 designed for testing the metal powder considered. It is not possible
26、 to standardize one or more particular instruments. However, certain basic points of procedure are recommended for the analysis of metallic powders (see clause 6). NOTEThe reduction-extraction method is also applicable to nitrogen determination and certain instruments permit simultaneous measurement
27、 of oxygen and nitrogen contents. However, the determination of nitrogen is not covered by this International Standard. 1 Scope This part of ISO 4491 specifies a method for the determination of the total oxygen content of metallic powders in concentrations up to about 2 % (m/m) by reduction-extracti
28、on at high temperature. By agreement, this method is also applicable to the determination of 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
29、 be in powder or compact form. The analysis is carried out on the powder as supplied, but the 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 oxyge
30、n content of the powder. This part of ISO 4491 shall be read in conjunction with ISO 4491-1. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this part of ISO 4491. At the time of publication, the edition indicated was v
31、alid. All standards are subject to revision, and parties to agreements based on this part of ISO 4491 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standard
32、s. ISO 4491:1989, Metallic powders Determination of oxygen content by reduction methods Part 1: General guidelines. 3 Principle A 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 convert
33、ed 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
34、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. c) Reaction medium: Dry, i.e. the test portion alone is poured into
35、 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 metals it is advisable to prepare first a bath of a fusible metal (for example platinum, tin, iron, nickel) capabl
36、e 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 reduction taking place over a fixed period of time, of the order of several minutes, or EN 24491-4:1993 4 BS
37、I 11-1999 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 to 3 000 C) which results. e) Determination of oxygen: Several methods for me
38、asuring either CO or CO2 are 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 volumetric (for carbon monoxide), chromatography (for carbon monoxide), infr
39、ared absorption (for carbon dioxide), thermal conductivity (for carbon monoxide and dioxide), coulometry (for carbon dioxide). 4 Apparatus and materials The main elements of an apparatus suitable for determining the oxygen content of a metallic powder are the following: crucibles, machined from high
40、 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 accordance with a predetermined temperature cycle; a purification train to remove wat
41、er; 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 the measuring device, when necessary, requires high purity gas, carbon monoxide,
42、carbon dioxide or certified metallic reference materials. 5 Test portion The analysis shall be carried out on two test portions. Several methods can be used to prepare the test portion prior to its introduction into the apparatus. a) The test portion is weighed directly into the degassed crucible. b
43、) 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/mm2 to 200 MN/mm2. The mass of the compact is determined. c) A quantity of the powder sample is enclosed in a small capsule of known weight made of platin
44、um, 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 suitable fragment of the sample is weighed as the test portion. All weighings shall be to the nearest 0,1 mg. A met
45、al 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 metal of the capsule can constitute the metal bath needed for convenient extraction; in this case, the mass of th
46、e 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 is necessary to degas the bath prior to the beginning of each extraction operation. The bath/test-portion ma
47、ss 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. Fre
48、quently, a mass between 0,1 g and 1 g is chosen. 6 Procedure 6.1 General For the reasons given in the introduction, it is not possible to specify the conditions of oxygen determination for each of the various metals, alloys and carbides to be analysed, and for each of the types of apparatus availabl
49、e. It should be noted that, especially when the reduction is carried out in the solid state and with continuous heating, the reaction may be slow and the time for complete reduction of the oxides will depend on the oxygen content. EN 24491-4:1993 BSI 11-19995 It is recommended that the optimal conditions for testing a given type of material and for a given range of oxygen contents be determined by performing preliminary tests. It is common to make successive tests on the same sample, increasi