1、BS EN 725-3:2007ICS 81.060.30NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAdvanced technicalceramics Methodsof test for ceramicpowdersPart 3: Determination of the oxygencontent of nonoxides by thermalextraction with a carrier gasThis British Standardwas publi
2、shed underthe authority of theStandards Policy andStrategy Committee on 31 BSI 2008ISBN 978 0 580 54525 2Amendments/corrigenda issued since publicationDate CommentsBS EN 725-3:2007National forewordThis British Standard is the UK implementation of . It supersedes BSEN 725-3:1994 which is withdrawn.Th
3、e UK participation in its preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.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
4、 are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.October 2008BS EN 725-3:2007EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 725-3January 2007ICS 81.060.30 Supersedes EN 725-3:1994 English VersionAdvanced technical ceramic
5、s - Methods of test for ceramicpowders - Part 3: Determination of the oxygen content of non-oxides by thermal extraction with a carrier gasCramiques techniques avances - Mthodes dessaispour poudres cramiques - Partie 3: Dtermination de lateneur en oxygne de poudres non-oxydes par extraction chaud so
6、us gaz porteurHochleistungskeramik - Prfverfahren fr keramischePulver - Teil 3: Bestimmung des Sauerstoffgehaltes inNichtoxid-Pulvern mittels TrgergasheiextraktionThis European Standard was approved by CEN on 2 December 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations w
7、hich 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 be obtained on application to the CEN Management Centre or to any CEN member.This European St
8、andard 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 CEN Management Centre has the same status as theofficial versions.CEN members are the national sta
9、ndards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kin
10、gdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 725-3:2007: EBS EN 725
11、-3:2007EN 725-3:2007 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Principle4 4 Apparatus .4 5 Sample preparation .5 6 Calibration 5 7 Blank determination 5 8 Procedure .5 9 Test report 6 Annex A (informative) Guidance in the selection of test conditions .7 BS EN 725-3:2007EN 72
12、5-3:2007 (E) 3 Foreword This document (EN 725-3:2007) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by
13、endorsement, at the latest by July 2007, and conflicting national standards shall be withdrawn at the latest by July 2007. This document supersedes EN 725-3:1994. EN 725 Advanced technical ceramics Methods of test for ceramic powders was prepared in Parts as follows: Part 1: Determination of impurit
14、ies in alumina Part 2: Determination of impurities in barium titanate Part 3: Determination of the oxygen content of non-oxides by thermal extraction with a carrier gas Part 4: Determination of oxygen content in aluminium nitride by XRF analysis Part 5: Determination of particle size distribution Pa
15、rt 6: Determination of the specific surface area withdrawn Part 7: Determination of the absolute density withdrawn Part 8: Determination of tapped bulk density Part 9: Determination of un-tapped bulk density Part 10: Determination of compaction properties Part 11: Determination of densification on n
16、atural sintering Part 12: Chemical analysis of zirconia Parts 6 and 7 of the series were superseded in 2005 by EN ISO 18757 and EN ISO 18753 respectively. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this Eu
17、ropean Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United K
18、ingdom. BS EN 725-3:2007EN 725-3:2007 (E) 4 1 Scope This part of EN 725 describes a method for the determination of the oxygen content of non-oxide powders used for advanced technical ceramics, using an inert carrier gas thermal extraction method. The method described is suitable for oxygen contents
19、 of less than 3 %. NOTE An indication of the limits of determination is usually given by the manufacturers of the gas analysis apparatus used. However, for a specific measurement procedure, such limits can be determined by experiments conducted by the user. 2 Normative references The following refer
20、enced 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. EN ISO/IEC 17025, General requirements for the competence of testing
21、 and calibration laboratories (ISO/IEC 17025:2005) 3 Principle A test sample is heated in a graphite crucible at a high temperature in a flow of an inert carrier gas. Oxygen in the sample is converted to oxides of carbon, which are extracted and transformed to consist entirely of either carbon monox
22、ide or carbon dioxide. This volume is then determined by a method of gas analysis. NOTE Guidance on the selection of test conditions is given in Annex A. 4 Apparatus 4.1 Scoop, for transferring the test sample. 4.2 Graphite crucible, which is used as a carbon source. The crucible is capable of being
23、 electrically heated by two electrodes, or by induction. 4.3 Tin or nickel capsule (optional), to contain the ceramic powder sample. 4.4 Nickel wire basket (optional), for use as a fluxing agent with certain powders such as aluminium nitride. 4.5 Gas analysis apparatus, based on one of the following
24、 techniques: a) volumetric analysis, for measurement of carbon monoxide gas; b) chromatography, for carbon monoxide; c) thermal conductivity, for carbon monoxide and carbon dioxide; d) coulometric analysis, for carbon dioxide; e) infrared absorption, for carbon dioxide; f) gravimetry, by absorption
25、of carbon dioxide. BS EN 725-3:2007EN 725-3:2007 (E) 5 4.6 Furnace, normally capable of reaching at least 2500 C operating in an inert gas atmosphere (nitrogen, helium or argon). NOTE A furnace which does not achieve 2500 C may be used for lower test temperatures, but 2500 C will be needed to give t
26、he correct result for certain types of material. 5 Sample preparation Take a sample of the dry powder, the amount taken being based on the detection limit of the gas analysis apparatus (4.5) used and on the expected oxygen content of the powder. EXAMPLE For infrared absorption (see 4.5 e), samples o
27、f 100 mg to 300 mg should be used. NOTE The measured (total) oxygen content consists of a contribution from surface and bulk. Use a scoop (4.1) to transfer the powder and place the sample either directly in the crucible (4.2) or in the tin capsule (4.3). If the capsule is used, squeeze it to expel a
28、ir and then fold over the open end several times, weighing again after squeezing. 6 Calibration Calibration shall be carried out preferably by using a reference material of certified oxygen content to calibrate the furnace (4.6) and gas analysis apparatus (4.5), using the procedure given in Clause 8
29、. An alternative method is to use a sample of pure carbon monoxide or carbon dioxide gas to calibrate the gas analysis apparatus, with a minimum of three results being recorded. NOTE Since gas calibration only calibrates the detection and not the extraction efficiency, gas calibration does not autom
30、atically guarantee correct results. The same applies if sample and calibration material are not very similar. 7 Blank determination Carry out a blank determination for each measurement run. Use the procedure given in Clause 8 and record the amount of gas evolved. Use this blank value to calculate th
31、e results for the sample analysis. 8 Procedure 8.1 Heat the empty graphite crucible (4.2) inside the furnace (4.6) to a temperature higher than the temperature for analysis. Record the flow of gas used in the furnace. Cool to ambient temperature. NOTE 1 This is to prevent additional degassing of the
32、 crucible during the test run, which would produce errors. NOTE 2 A recommendation for gas flow will normally be given by the manufacturer of the gas analysis apparatus (4.5). 8.2 Place the tin (or nickel) capsule (4.3) and sample in the crucible (4.2). Select a temperature which is high enough to d
33、issociate the oxides to be determined (see Annex A). Use the nickel wire basket (4.4) if the preliminary tests indicate that it is necessary. Heat the furnace to the test temperature and record the temperature and the length of time at temperature. Collect the gas evolved and measure the amount, usi
34、ng one of the analytical techniques listed in 4.5. 8.3 Repeat the procedure given in Clause 5 and 8.2 at least four times. BS EN 725-3:2007EN 725-3:2007 (E) 6 9 Test report The test report shall be in accordance with the reporting provisions of EN ISO/IEC 17025 and shall include at least the followi
35、ng information: a) name and address of the testing establishment; b) date of the test; c) on each page, a unique report identification and page number; d) customer name and address; e) reference to this standard, i.e. determined in accordance with EN 725-3; f) authorising signature; g) any deviation
36、 from the method described, with appropriate validation, i.e. demonstrated to be acceptable to the parties involved; h) description of the test material (manufacturer, type, batch or code number); i) type of analytical equipment used (see 4.5); j) method of calibration (see Clause 6); k) purity of t
37、he carrier gas and gas used for calibration; the calibration material used with its certified oxygen content; l) mass of the samples and reference to optional use of the tin capsule (see 4.3); m) test temperature; n) individual values of oxygen content, mean value and standard deviation; o) comments
38、 about the test or test results. BS EN 725-3:2007EN 725-3:2007 (E) 7 Annex A (informative) Guidance in the selection of test conditions Because of the large variety of ceramic powders in use and number of analytical techniques available, it is not possible to specify test conditions (amount of sampl
39、e, temperature, gas flow rate, analytical technique) that will be applicable to every determination. It is therefore recommended that the optimum conditions for testing a material be determined by preliminary tests. This may be done by carrying out successive tests on the same test sample, increasin
40、g the heating power until the measured oxygen content reaches a maximum, constant value. Fluxing agents (see 4.4) may also be used. When the test conditions have been established, a certified reference material of the same chemical type as the test sample should be tested to check. BS EN725-3:2007BS
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