BS EN 15979-2011 Testing of ceramic raw and basic materials Direct determination of mass fractions of impurities in powders and granules of silicon carbide by OES by DC arc excitat.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 15979:2011T e s t i n g o f c e r a m i c r a w a n d basic materials Direct determination of mass fractions of impurities in powders and granules of silicon carbide by OES

2、 by DC arc excitationBS EN 15979:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 15979:2011.The UK participation in its preparation was entrusted to TechnicalCommittee RPI/1, Refractory products and materials.A list of organizations represented on this comm

3、ittee 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. BSI 2011ISBN 978 0 580 64179 4ICS 81.060.10Compliance with a British Standard cannot confer immunity fromlegal ob

4、ligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 28 February 2011.Amendments issued since publicationDate Text affectedBS EN 15979:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15979 January 2011 ICS 81.060.10 English Versi

5、on Testing of ceramic raw and basic materials - Direct determination of mass fractions of impurities in powders and granules of silicon carbide by OES by DC arc excitation Essai des matires premires et matriaux de base cramiques - Dtermination directe des fractions massiques dimpurets dans les poudr

6、es et granuls de carbure de silicium par OES lexcitation darc DC Prfung keramischer Roh- und Werkstoffe - Direkte Bestimmung der Massenanteile an Verunreinigungen in pulver- und kornfrmigem Siliciumcarbid mittels OES und Anregung im Gleichstrombogen This European Standard was approved by CEN on 10 D

7、ecember 2010. 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

8、 obtained on application to the CEN-CENELEC Management 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 t

9、he CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxemb

10、ourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All right

11、s of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15979:2011: EBS EN 15979:2011EN 15979:2011 (E) 2 Contents Page Foreword 31 Scope 42 Principle 43 Spectrometry 44 Apparatus .45 Reagents .56 Sampling and preparation of test samples .57 Calibration

12、 58 Procedure .69 Calculation 810 Expression of results 811 Precision .812 Test report 9Annex A (informative) Results of inter-laboratory study 10Annex B (informative) Wavelength and working range 14Annex C (informative) Possible interferences and their elimination 16Annex D (informative) Informatio

13、n regarding the evaluation of the uncertainty of the mean value . 19Annex E (informative) Commercial certified reference materials 20Bibliography . 21BS EN 15979:2011EN 15979:2011 (E) 3 Foreword This document (EN 15979:2011) has been prepared by Technical Committee CEN/TC 187 “Refractory products an

14、d 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 endorsement, at the latest by July 2011, and conflicting national standards shall be withdrawn at the latest by July 2011.

15、Attention is drawn to the possibility that some of the elements of 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. According to the CEN/CENELEC Internal Regulations, the national standards organization

16、s of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

17、Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15979:2011EN 15979:2011 (E) 4 1 Scope This European Standard describes the method for the analysis of mass fractions of the impurities Al, B, Ca, Cr, Cu, Fe, Mg, Ni, Ti, V and Zr in powder- and grain-shaped silicon

18、 carbide of ceramic raw and basic materials. This application can also be extended to other metallic elements and other similar non-metallic powder- and grain-shaped materials such as carbides, nitrides, graphite, carbon blacks, cokes, carbon, as well as a number of further oxidic raw and basic mate

19、rials after appropriate testing. NOTE There are positive interferences for materials such as e.g. graphite, B4C, BN, WC and several refractory metal oxides. This testing procedure is applicable to mass fractions of the impurities mentioned above from approximately 1 mg/kg up to approximately 3 000 m

20、g/kg, after verification. In some cases it may be possible to extend the range up to 5 000 mg/kg depending on element, wavelength, arc parameter, and sample weight. 2 Principle The combustion and evaporation of the crushed sample material takes place in the arc in an atmosphere of mixed argon and ox

21、ygen or in air. The metallic traces in the arc plasma are excited to emission of light. The light is guided into a simultaneous emission spectrometer (e.g. by coupling via fibre-optics or directly). The light is split in its spectral lines and measured by applicable detectors like a photomultiplier,

22、 charge coupled device (CCD), and charge injection device (CID). The mass fractions of elements in the sample are calculated by comparison of the intensities of the element-specific spectral line with those of a calibration sample of identical material. 3 Spectrometry The optical emission spectromet

23、ry is based on generation of line spectra of excited atoms or ions, in which each spectral line can be definitely related to an element and the line intensities are proportional to the mass fractions of elements in the measured sample (see 6, 7 b) The carrier electrode is filled by repeatedly pressi

24、ng the cup (orifice downwards) onto the sample material which is lying on a clean carrier (e.g. filter paper); c) A sub-sample of the sample material is weighed to the nearest 0,1 mg into the carrier electrode in a defined narrow weighing range (e.g. between 4,5 to 5,5 mg). The mass of the weighed s

25、ub-sample has to be documented. Depending on dimension and shape of the carrier electrode the mass of the sub-sample can vary. The sample mass can be reduced in case of elements, e.g. with mass fractions above the calibration range (minimum circa 1 mg). In this case, the weighed sub-sample has to be

26、 mixed in the electrode with a material of the same type, which does not contain the respective analytes. The total mass of material in the electrode shall correspond to that of the calibration sample (5.2). Instead of a pure material of the same type spectral-grade carbon powder can be used. Subseq

27、uently, the sub-sample has to be compacted in the cup of the carrier electrode by slightly striking it on a rigid underlay or by knocking with a spatula at the tweezers holding the carrier electrode. The electrodes shall be touched in the clamp-region of the electrode holder using tweezers (4.3) The

28、 carrier electrode has to be fixed in the optical path using the electrode holder of the DC-Arc equipment. The distance to the upper counter electrode (cathode) has to be adjusted to the nearest 0,1 mm at a value of 3,5 mm to 4,0 mm. NOTE 1 The distance between the electrodes can vary according to t

29、he diameter of the electrodes. The position of the electrodes, and thus the arc discharge, has to be constant with respect to the optical axis of the optical system. Any change of the optical adjustment will lead to different results. Parts of the electrodes shall not be visible to the emission spec

30、trometer. This is especially true for the upper electrode (cathode) whereas the lower electrode (anode), because of the high burn-off rate, normally remains a significantly shorter time in the optical path. NOTE 2 Electrodes visible in the optical path result in a strong enhancement of the spectral

31、background in some spectral ranges. The arc discharge has to be started synchronous to the data acquisition of the spectrometer (4.1). BS EN 15979:2011EN 15979:2011 (E) 7 The evaporation or combustion of the sample in the DC-Arc has to be carried out preferably under shielding gas excluding any nitr

32、ogen. The mixing ratio of the shielding gas is about 70 parts by volume argon and 30 parts by volume oxygen at a constant gas flow of about (4 1) l/min. The evaporation or combustion in air is principally possible, but then one has to pay attention to spectral interferences, e.g. CN-bands. In additi

33、on, degradation of the reproducibility can be expected. CAUTION It is not safe to look into the arc plasma without eye protection (UV- and IR-radiation). Reflections on reflective areas can be dangerous too. Each sample shall be measured a minimum of three times. 8.2 Procedure using addition of carr

34、ier This procedure is especially suitable for low analyte concentrations. The sample shall be weighed together with carrier and spectral-grade carbon or graphite. The mixture is homogenised using an easy volatile solvent. The optimal relation of quantities as well as the selection of an appropriate

35、carrier (see 2 and 11) shall be investigated for each sample material experimentally. NOTE 1 The power of detection is advanced by addition of carrier. Suitable carriers are halides like AgCl, BaCl2. NOTE 2 For materials such as SiC and WC and also for oxides such as MoO3, WO3, Ta2O3, Nb2O3, it is r

36、ecommended to use BaCl2as carrier and a mass-ratio of sample/graphite/BaCl2of 10/4/1. In the individual case the ratio should be checked and, if necessary, be optimized. NOTE 3 The sample mix can be homogenized in a plastic bottle (4.8) after addition of 6 ml dichloromethane and about 20 stirring ba

37、lls (4.7). Shake the bottle for a minimum of 10 min. The dichloromethane can be completely removed by placing the opened plastic bottle in a drying cabinet for approximately 1 h at 60 C. The dried mixture is loosened by gently shaking the plastic bottle. After that, the stirring balls can be removed

38、. CAUTION To avoid exposure to dichloromethane, the appropriate safety regulations shall be obeyed. Filling of the carrier electrode shall be carried out in accordance with 8.1. The samples used for calibration (5.2) shall be treated in the same manner. Each sample has to be measured a minimum of th

39、ree times. If the deviation of the single values of the analyte concentrations is greater than the specified value of repeatability, the procedure has to be repeated according to Clause 8. In the case of continued insufficient reproducibility of spectral line intensities of one or more analytes the

40、sample has to be homogenised additionally (e.g. mortar). For low concentrations near the limit of determination (see 16) this further step is not necessary. 8.3 Wavelength and working range It is critical that all selected analyte wavelength are interference-free with respect to sample matrix and fu

41、rther impurities. NOTE 1 Proposal for selection of wavelength and information about working ranges, see Annex B. Only spectral lines shall be selected where under the chosen working conditions neither self-absorption nor self-reversal will occur. Order-interferences mainly occur when combining Echel

42、le optics with plane solid-state detectors (CID- or CCD-detectors). NOTE 2 A comprehensive description of possible interferences and their reduction can be found in Annex C. BS EN 15979:2011EN 15979:2011 (E) 8 Ensure that the concentrations to be analyzed lie above the limits of determination of the

43、 analytes. The upper working range is limited by a decrease of sensitivity (slope of calibration function) to about 80 % of its initial value. If applicable, less sensitive spectral lines can be used. 9 Calculation The intensities of spectral lines measured by the emission spectrometer (4.1) shall b

44、e corrected to net-intensities using the background intensities measured at the background measuring points. The net-intensities shall be converted into the corresponding masses of the respective analytes using analytical functions. These include the weight of the sub-samples, so the mass fractions

45、of the analytes in the original sample can be calculated. Additionally, the ratio of the net-intensities of the analyte lines to the intensity of an emission line of a reference element with constant mass fraction (e.g. Si in analysis of SiC) can also be calculated. NOTE This so called method of int

46、erior standard (reference element) can increase precession and accuracy of the analysis method. The wavelength of spectral lines and the background measuring points used for calibration and sample analysis have always to be the same. 10 Expression of results The concentration of the analytes as mean

47、 of the single values of the multiple determinations shall be expressed in mass fractions and rounded to the decimal place resulting from uncertainty of measurement (for more information about uncertainty see Annex D). 11 Precision NOTE See ISO 5725-2 17 for definitions. 11.1 Repeatability The repea

48、tability limit r will not be exceeded in more than 5 % of cases by the absolute difference between two single test results independent each other and determined on the same sample material by the same analyst using the same analytical procedure and the same equipment in the same laboratory within a

49、short period of time. The data of repeatability determined at three different silicon carbide samples in the frame of an inter-laboratory comparison are listed in Annex A. 11.2 Reproducibility The reproducibility limit R will not be exceeded in more than 5 % of cases by the absolute difference between two single test results determined by different analysts at the same sample material using the same analytical procedure and different equipment in different laboratories. The reproduc