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1、BRITISH STANDARD BS EN 725-3:1994 Advanced technical ceramics Methods of test for ceramic powders Part 3: Determination of the oxygen content of non-oxides by thermal extraction with a carrier gas The European Standard EN 725-3:1994 has the status of a British Standard UDC 666.3-121:620.1:546.21 BS
2、EN 725-3:1994 This British Standard, having been prepared under the direction of the Refractory Products Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 May 1994 BSI 11-1999 The following BSI references relate to the work on this stand
3、ard: Committee reference RPM/14 Draft for comment 92/39462 DC ISBN 0 580 22393 0 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: Austria
4、Oesterreichisches 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 IcelandTechnologi
5、cal 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 E
6、spaola de Normalizacin y Certificacin SwedenStandardiseringskommissionen i Sverige SwitzerlandAssociation suisse de normalisation United KingdomBritish Standards Institution Amendments issued since publication Amd. No.DateComments BS EN 725-3:1994 BSI 11-1999i Contents Page Cooperating organizations
7、Inside front cover National forewordii Foreword2 Text of EN 725-33 National annex NA (informative) Committees responsibleInside back cover BS EN 725-3:1994 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Refractory Products Standards Policy Committ
8、ee and is the English language version of EN 725-3:1994, Advanced technical ceramics Methods of test for ceramic powders Part 3: Determination of the oxygen content of non-oxides by thermal extraction with a carrier gas, published by the European Committee for Electrotechnical Standardization (CEN).
9、 EN 725-3 was produced as a result of international discussions in which the UK took an active part. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard
10、 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 EN title page, pages 2 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amen
11、dments incorporated. This will be indicated in the amendment table on the inside front cover. ? EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 725-3 January 1994 UDC 666.3-121:620.1:546.21 Descriptors: Ceramics, powdery materials, chemical analysis, determination of content, oxygen, extraction
12、 methods, reduction methods, carbon monoxide English version Advanced technical ceramics Methods of test for ceramic powders Part 3: Determination of the oxygen content of non-oxides by thermal extraction with a carrier gas Cramiques techniques avances Mthodes d essai pour poudres cramiques Partie 3
13、: Dtermination de la teneur en oxygne de poudres non-oxydes par extraction chaud sous gaz porteur Hochleistungskeramik Prfverfahren fr keramische Pulver Teil 3: Bestimmung des Sauerstoffgehaltes in Nichtoxid-Pulvern mittels Trgergasheiextraktion This European Standard was approved by CEN on 1994-01-
14、10. 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 bibliographical references concerning such national standards may be obtained
15、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 member into its own language and notified to the Central Secretari
16、at 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, Sweden, Switzerland and United Kingdom. CEN European Committee for
17、 Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1994 Copyright reserved to CEN members Ref. No. EN 725-3:1994 E ? EN 725-3:1994 2 BSI 11-1999 Foreword This European Standard has been prepared by Technical Committ
18、ee CEN/TC 184, Advanced technical ceramics, the secretariat of which is held by BSI. EN 725 consists of 11 Parts: Part 1: Determination of impurities in alumina; Part 2: Determination of impurities in barium titanate (ENV); Part 3: Determination of oxygen content of non-oxides by thermal extraction
19、with a carrier gas; Part 4: Determination of oxygen content in aluminium nitride by XRF analysis (ENV); Part 5: Determination of particle size distribution; Part 6: Determination of the specific surface area; Part 7: Determination of absolute density; Part 8: Determination of tapped bulk density; Pa
20、rt 9: Determination of untamped bulk density; Part 10: Determination of compaction properties; Part 11: Determination of densification on natural sintering (ENV). This document was submitted for the Formal Vote and approved as a European Standard. This European Standard shall be given the status of
21、a national standard, either by publication of an identical text or by endorsement, at the latest by July 1994, and conflicting national standards shall be withdrawn at the latest by July 1994. In accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement thi
22、s European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword2 1Scope3 2Principle3 3Apparatus3 4Sample preparation3 5Procedure3 6Blank determi
23、nation3 7Calibration3 8Test report4 Annex A (informative) Guidance in the selection of test conditions5 ? EN 725-3:1994 BSI 11-19993 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 ca
24、rrier gas thermal extraction method. The method is suitable for oxygen contents of less than 3 % NOTEThe limits of determination are given by the manufacturers of the apparatus. 2 Principle A test piece is heated in a graphite crucible at a high temperature in a flow of an inert carrier gas. Oxygen
25、in the sample is converted to oxides of carbon, which are extracted and transformed to consist entirely of either carbon monoxide or carbon dioxide. This volume is then determined by a suitable method of gas analysis. NOTEGuidance on the selection of test conditions is given in Annex A. 3 Apparatus
26、3.1 Graphite crucible, which is used as a carbon source. The crucible is capable of being electrically heated by two electrodes, or by induction. 3.2 Tin capsule, (optional) to contain the ceramic powder sample. 3.3 Nickel wire basket, (optional) for use as a fluxing agent with certain powders such
27、as aluminium nitride. 3.4 Gas analysis apparatus, based on one of the following 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 dio
28、xide; e) infrared absorption, for carbon dioxide. 3.5 Furnace, normally capable of reaching at least 2 500 C operating in an inert gas atmosphere (nitrogen, helium or argon). NOTEApparatus which does not achieve 2 500 C may be used for lower test temperatures, but 2 500 C will be needed to give the
29、correct result for certain types of material. 4 Sample preparation Take a sample of the dry powder, the quantity taken being based on the detection limit of the apparatus used for gas analysis and on the expected oxygen content of the powder. NOTEFor example, for infrared absorption (see 3.4 e), sam
30、ples of 100 mg to 300 mg are required. Use a scoop to handle the powder and place the sample either directly in the crucible or in the tin capsule. If the capsule is used, squeeze it to expel air and then fold over the open end several times, weighing again after squeezing. 5 Procedure 5.1 Heat the
31、empty graphite crucible inside the furnace to a temperature greater than the temperature for analysis. Record the flow of gas used in the furnace. NOTE 1This is to prevent additional degassing of the crucible during the test run, which would produce errors. NOTE 2A recommendation for gas flow will n
32、ormally be given by the manufacturer of the instrument. Cool to ambient temperature. 5.2 Place the tin capsule and sample in the crucible. Select a temperature which is high enough to dissociate the oxides to be determined (see Annex A). Use the nickel wire basket (see 3.3) if the preliminary tests
33、suggest that it is necessary. Heat the furnace to the test temperature and record the temperature and the time at temperature. Collect the gas evolved and measure the amount, using one of the analytical techniques listed in 3.4. 5.3 Repeat the procedure given in clause 4 and subclause 5.2 at least f
34、our times. 6 Blank determination Carry out a blank determination for the apparatus whenever the gas supply or crucible batch is changed. Use the procedure given in clause 5 and record the amount of gas evolved. Use this blank value to calculate the results for the sample analysis. 7 Calibration Cali
35、bration shall be carried out preferably by using a reference material of certified oxygen content to calibrate the furnace and gas analysis equipment, using the procedure given in clause 5. An alternative method is to use a sample of pure carbon monoxide or carbon dioxide gas to calibrate the gas an
36、alysis equipment, with a minimum of three results being recorded. ? EN 725-3:1994 4 BSI 11-1999 8 Test report The test report shall include the following information: a) the name of the test establishment; b) the date of the test, a unique identification of the report, the name and address of the cu
37、stomer, a signatory of the report; c) a reference to this European Standard, i.e. determined in accordance with EN 725-3; d) a description of the test material (manufacturer, type, batch or code number); e) the type of analytical equipment used (see 3.4); f) the method of calibration (see clause 7);
38、 g) the purity of the carrier gas and gas used for calibration; h) the mass of the samples and reference to optional use of the tin capsule (see 3.2); i) the test temperature; j) the individual values of oxygen content, mean value and standard deviation: k) comments about the test or test results. ?
39、 EN 725-3:1994 BSI 11-19995 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 sample, temperature, gas flow rate, analytical
40、 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, increasing the reducing action until the measured
41、oxygen content reaches a maximum, constant value. Fluxing agents (see 3.3) 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 these proposed conditions. ? 6 blank BS EN 725-3:1994 BSI
42、 11-1999 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the Refractory Products Standards Policy Committee (RPM/-) to Technical Committee RPM/14 upon which the following bodies were represented: Br
43、itish Ceramic Research Ltd. British Industrial Ceramic Manufacturers Association British Steel Industry Bureau of Analysed Samples Limited China Clay Association Ministry of Defence Refractories Association of Great Britain Society of Glass Technology BS EN 725-3:1994 BSI 389 Chiswick High Road Lond
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