1、BRITISH STANDARDBS EN 12698-1:2007Chemical analysis of nitride bonded silicon carbide refractories Part 1: Chemical methodsThe European Standard EN 12698-1:2007 has the status of a British StandardICS 71.040.40g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g
2、50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 12698-1:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2007 BSI 2007ISBN 978 0 580 50633 8National forewordThis
3、British Standard was published by BSI. It is the UK implementation of EN 12698-1:2007. The UK participation in its preparation was entrusted to Technical Committee RPI/1, Refractory products and materials.A list of organizations represented on this committee can be obtained on request to its secreta
4、ry.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNOR
5、ME EUROPENNEEUROPISCHE NORMEN 12698-1March 2007ICS 71.040.40English VersionChemical analysis of nitride bonded silicon carbide refractories -Part 1: Chemical methodsAnalyse chimique des produits rfractaires contenant ducarbure de silicium liaison nitrure - Partie 1: MthodeschimiquesChemische Analyse
6、 von feuerfesten Erzeugnissen ausnitridgebundenem Siliciumcarbid - Teil 1: ChemischeVerfahrenThis European Standard was approved by CEN on 15 February 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the st
7、atus 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 Standard exists in three official versions (English, French, German). A
8、 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 standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic,
9、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 Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISA
10、TIONEUROPISCHES 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 12698-1:2007: EEN 12698-1:2007 (E) 2 Contents Page Foreword .3 1 Scope 4 2 Normative refere
11、nces4 3 Terms and Definitions.4 4 Methods for determination .4 5 Sampling.5 6 Determination of free aluminium .5 6.1 Principle5 6.2 Reagents.6 6.3 Apparatus .6 6.4 Sample preparation .6 6.5 Procedure .6 6.6 Calculation and expression of results.6 7 Determination of total nitrogen7 7.1 General .7 7.2
12、 Determination of total nitrogen by carrier gas fusion (CGF) 7 7.3 Determination of total nitrogen content by fusion decomposition 10 7.4 Determination of total nitrogen content by Kjeldahl distillation 14 7.5 Determination of total nitrogen by microwave digestion16 8 Determination of free silicon 1
13、8 9 Determination of free silica 18 9.1 Principle18 9.2 Reagents.18 9.3 Apparatus .19 9.4 Sample preparation .19 9.5 Procedure .19 9.6 Determination.21 9.7 Calculation and expression of SiO2content.21 9.8 Precision.21 10 Determination of carbon .21 10.1 Determination of the total carbon, Ct21 10.2 D
14、etermination of free carbon, Cfree21 11 Calculation of silicon carbide content.25 12 Determination of free alumina (Al2O3) .25 12.1 Principle25 12.2 Reagents.25 12.3 Apparatus .26 12.4 Procedure .26 12.5 Calculation and expression of results.26 12.6 Precision.26 Annex A (informative) Determination o
15、f free carbon using the hot chromic sulfuric iodic acid method (10.2.1): Explanation for the evaluation of the different possible detection methods27 A.1 Coulometric detection system .27 A.2 Infrared absorption detection system .29 A.3 Conductometric detection system.30 Bibliography32 EN 12698-1:200
16、7 (E) 3 Foreword This document (EN 12698-1:2007) has been prepared by Technical Committee CEN/TC 187 “Refractory products and materials”, 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
17、 endorsement, at the latest by September 2007, and conflicting national standards shall be withdrawn at the latest by September 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Aust
18、ria, 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 Kingdom. EN 12698-1:20
19、07 (E) 4 1 Scope This standard describes the methods for the analysis of all refractory products containing nitride and oxynitride bonded silicon carbide, irrespective of the silicon carbide level. It includes details of sample preparation, general principles of chemical analysis and detailed method
20、s for the determination of carbon, silicon carbide, free aluminium, free silicon, total nitrogen and oxygen. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references,
21、 the latest edition of the referenced document (including any amendments) applies. EN 12475-4:1998, Classification of dense shaped refractory products Part:4 Special products EN 12698-2, Chemical analysis of nitride bonded silicon carbide refractories Part 2: XRD methods prEN ISO 21068, Chemical ana
22、lysis of silicon carbide containing raw materials and refractory products ISO 836:2001, Terminology for refractories ISO 3310-1, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth ISO 5022, Shaped refractory products Sampling and acceptance testing ISO 5725-1, Acc
23、uracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions ISO 8656-1, Refractory products Sampling of raw materials and unshaped products Part 1: Sampling scheme 3 Terms and Definitions For the purposes of this document the terms and definitions giv
24、en in ISO 836:2001, EN 12475-4:1998 and the following apply. 3.1 nitride and oxynitride bonded silicon carbide refractories refractory products predominantly consisting of silicon carbide with minor amounts of nitride phases as a matrix component NOTE In general, metallic silicon is used as precurso
25、r material which undergoes a phase transformation in an oxygen-free nitrogen atmosphere. 4 Methods for determination A list of methods and the relevant European Standards are given in Table 1. Carbon is determined by the evolution of carbon dioxide on combustion in a stream of oxygen at defined temp
26、eratures. Silicon carbide is calculated by the difference of total carbon (Ctotal) and free carbon (Cfree). NOTE 1 The carbon dioxide evolved can be conveniently measured coulometrically, gravimetrically by absorbtion onto soda lime, or by infrared detection. EN 12698-1:2007 (E) 5 Free aluminium is
27、determined by the evolution of hydrogen on treatment with hydrochloric acid and by measuring the gas volume in a nitrometer. Free silicon shall be determined on the same sample by treatment with sodium hydroxide. Total nitrogen is determined by a variety of methods: carrier gas fusion, alkaline fusi
28、on, Kjeldal distillation or microwave digestion. NOTE 2 The nitrogen can be conveniently measured by thermal conductivity or after digestion as ammonium by titration with hydrochloric acid. Distinction between aluminium nitride and silicon nitride is made by their reaction with sodium hydroxide solu
29、tion; aluminium nitride is quantitatively decomposed yielding free ammonia, while silicon nitride is unaffected. A convenient commercial apparatus for determining total oxygen consists of an induction furnace in which the sample is heated with pure carbon. Carbon dioxide and carbon monoxide are meas
30、ured by infrared absorption and the integrated signals are combined to give the total oxygen content. NOTE 3 Specification of many of the constituents can often be made using XRD techniques, e.g. free silicon, silicon nitride, silicon oxynitride, quartz and cristobalite (see EN 12698-2). Table 1 Met
31、hods and relevant European Standards Item tested European Standard Carbon and silicon carbide prEN ISO 21068 Free silicon prEN ISO 21068 Oxygen prEN ISO 21068 Free aluminium EN 12698-1 Total nitrogen EN 12698-1 Silicon nitride/oxynitride, free silica EN 12698-1 XRD prEN ISO 21068 and EN 12698-2 Sial
32、on EN 12698-Free carbon prEN ISO 21068 or EN 12698-1 Total carbon prEN ISO 21068 Silicon carbide prEN ISO 21068 and EN 12698-1 Free alumina EN 12698-1 5 Sampling Sample shaped and unshaped products using the procedures given in ISO 5022 and ISO 8656-1. When sampling large fragments, take care to col
33、lect samples from different points of individual pieces. Homogenize the sample by reducing the maximum particle size to 150 m and take the test sample from this material. 6 Determination of free aluminium 6.1 Principle The volume of hydrogen generated by the action of dilute hydrochloric acid on any
34、 free aluminium in a sample is measured. EN 12698-1:2007 (E) 6 If the sample is known to contain carbonate, then the volume of hydrogen evolved is corrected for the known carbonate content. The free aluminium content can also be determined by the evolution of hydrogen using sodium hydroxide. In this
35、 case, the volume of hydrogen evolved is corrected for the silicon content. Free iron will also evolve hydrogen; a correction is made for the iron content. 6.2 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade 6.2.1 Distilled water or water which
36、 has been fully demineralized by ion exchange (deionized water) and reagents of analytical grade. 6.2.2 Dilute hydrochloric acid, 1+1 by volume. 6.3 Apparatus 6.3.1 Nitrometer, as used for determining free silicon. 6.3.2 Balance, capable of reading to the nearest 0,1 mg. 6.4 Sample preparation Dry t
37、he test sample (sampling as described in clause 5) a to constant mass at (110 10) C for a minimum of 2 h prior to analysis. 6.5 Procedure Weigh (0,5 0,01) g of sample into a clean, dry nitrometer tube. Place a dry ignition tube inside the tube and holding the nitrometer tube upright, introduce, usin
38、g a long dropping pipette and without letting any touch the sample, 5 ml of dilute hydrochloric acid into the ignition tube. Carefully fit the bung of the apparatus making sure there is good seal. Equalize the pressure and leave the three-way tap in a position that connects the sample and graduated
39、tube. Tip the acid out of the ignition tube onto the sample. Shake the apparatus gently and allow it to stand for 15 min. Read off the volume after equalizing the pressure. Shake gently and read again after another 5 min to 10 min. Record the final volume reading when consecutive readings are the sa
40、me. Also note the temperature and barometric pressure. NOTE If this method is used frequently, it is recommended that a conical flask with airtight sample insert device, e.g. a side-on positioned ground-in connection and ground-in stopper with weighing bottle (special version) is used. The weighed s
41、ample is placed into the stopper-connected weighing bottle. The hydrochloric acid is added to the flask. After equalizing the pressure, the sample powder is added to the acid by turning the stopper. 6.6 Calculation and expression of results Correct the volume reading to the gas volume at standard te
42、mperature, V(STP)in ml, using equation (1): EN 12698-1:2007 (E) 7 ()( )()TppVV+=273273013,251OH1STP2(1) where V1is the measured volume, in ml; p is the atmospheric pressure, at time of measurement, in hPa; OH2p is the partial pressure of water vapour at the measured temperature, in hPa; T is the mea
43、sured temperature, in C. Calculate the percentage of free aluminium, A, using equation (2): ()mVA1008040,000STP= (2) where m is the mass of the sample, in g. Report the result to the nearest 0,1 %. 7 Determination of total nitrogen 7.1 General To determine total nitrogen one of the four methods give
44、n in 7.2 to 7.5 shall be used. 7.2 Determination of total nitrogen by carrier gas fusion (CGF) 7.2.1 General This method is used to determine nitrogen in silicon nitride, Si3N4, and other compounds, in the form of nitrides and oxynitrides by thermal decomposition. 7.2.2 Principle A sample, prepared
45、as described in clause 5, is decomposed in a graphite crucible in a stream of carrier gas (helium) by heating it to above 2 400 C in a resistance furnace (electrode furnace). The gases released are mainly nitrogen, carbon monoxide and hydrogen. The carbon monoxide and hydrogen are oxidized to carbon
46、 dioxide and water and then removed by absorption. Alternatively, formed carbon monoxide and gases other than nitrogen shall be removed, for example, using a molecular sieve. The change in thermal conductivity due to the nitrogen component is then measured. The details of the determination procedure
47、 can vary with the type of apparatus used and it is therefore only possible to give general instructions that can be used with any type of apparatus. Using the gas calibration, the validity of the results is confirmed by analysing a reference material having similar extraction behaviour. EN 12698-1:
48、2007 (E) 8 7.2.3 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade. 7.2.3.1 Distilled water, or water which has been fully demineralized by ion exchange (deionized water). 7.2.3.2 Helium, having a minimum purity of 99,99 %. 7.2.3.3 Nitrogen, havi
49、ng a minimum of 99,99 %. 7.2.3.4 Catalysts, such as copper oxide. 7.2.3.5 Sorption agents for removing water vapour and carbon dioxide, e.g. magnesium perchlorate, sodium hydroxide on a support, or a molecular sieve. 7.2.4 Apparatus 7.2.4.1 Measurement device, commercially available apparatus consisting of a resistance furnace and a measuring unit for determining nitrogen in a stream of carrier gas using a thermal conductivity cell. An example of a suitable apparatus is given in Figure 1. HeN157234986 2Key 1. Carrier gas 2. Crucible 3. Samp
