1、BRITISH STANDARDBS EN 12698-2:2007Chemical analysis of nitride bonded silicon carbide refractories Part 2: XRD methodsThe European Standard EN 12698-2:2007 has the status of a British StandardICS 71.040.40g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49
2、g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 12698-2:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2007 BSI 2007ISBN 978 0 580 50666 6National forewordThis British
3、 Standard was published by BSI. It is the UK implementation of EN 12698-2:2007.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 secretary.This
4、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 STANDARDNORME EUROP
5、ENNEEUROPISCHE NORMEN 12698-2March 2007ICS 71.040.40English VersionChemical analysis of nitride bonded silicon carbide refractories -Part 2: XRD methodsAnalyse chimique des produits rfractaires contenant ducarbure de silicium liaison nitrure - Partie 2 : Mthodesde DRXChemische Analyse von feuerfeste
6、n Erzeugnissen ausnitridgebundenem Silicumcarbid - Teil 2: XRD-VerfahrenThis 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 status of a national st
7、andard 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 version in any other
8、 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, Denmark, Estonia, Fin
9、land,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 NORMALISATIONEUROPISCHES KOMIT
10、EE 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 12698-2:2007: EEN 12698-2:2007 (E) 2 Contents Page Foreword .3 1 Scope 4 2 Normative references4 3 Definitions 4
11、 4 Apparatus .4 5 Sampling.5 6 Procedure .5 6.1 Sample preparation .5 6.2 Measuring parameters 5 6.3 Qualitative analysis .5 6.4 Quantitative analysis.6 7 Precision.10 7.1 Repeatability 10 7.2 Reproducibility.10 8 Test report 10 Annex A (normative) X-ray diffraction data for the determination of -Si
12、AlON content.11 A.1 General .11 A.2 Example of calculation of z-value for -SiAlON 12 Bibliography13 EN 12698-2:2007 (E) 3 Foreword This document (EN 12698-2:2007) has been prepared by Technical Committee CEN/TC 187 “Refractory products and materials”, the secretariat of which is held by BSI. This Eu
13、ropean Standard shall be given the status of a national standard, either by publication of an identical text or by 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, t
14、he national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, N
15、orway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 12698-2:2007 (E) 4 1 Scope This standard describes methods for the determination of mineralogical phases typically apparent in nitride and oxy-nitride bonded silicon carbide refractory products us
16、ing a Bragg-Brentano diffractometer. It includes details of sample preparation and general principles for qualitative and quantitative analysis of mineralogical phase composition. Quantitative determination of -Si3N4, -Si3N4, Si2ON2, AlN, and SiAlON are described. NOTE For the refinement procedures
17、the total nitrogen content, analysed in accordance with EN 12698-1 is needed. 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, the latest edition of the refe
18、renced document (including any amendments) applies. EN 12475-4:1998, Classification of dense shaped refractory products Part 4: Special products EN 12698-1, Chemical analysis of nitride bonded silicon carbide refractories Part 1: Chemical methods ISO 836:2001, Terminology for refractories ISO 5022,
19、Shaped refractory products Sampling and acceptance testing ISO 8656-1, Refractory products Sampling of raw materials and unshaped products Part 1: Sampling scheme 3 Definitions For the purposes of this document the terms and definitions given in ISO 836:2001, EN 12475-4:1998 and the following apply.
20、 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 a precursor material, which undergoes a phase transformation in an o
21、xygen-free nitrogen atmosphere. 4 Apparatus Bragg-Brentano diffractometers with a copper X-ray tube, graphite monochromator and scintillation counter and the following experimental setting for data collection are used: goniometer with a measurement uncertainty of 0,5 at a confidence level of 95 %; p
22、rimary soller slit with a divergence 2,5 ; divergence slit 1 ; receiving slit 0,2 mm; EN 12698-2:2007 (E) 5 scatter slit 1 ; narrow line focus; tube settings 40 kV and 20 mA to 45 mA. 5 Sampling Sample shaped and unshaped products using the procedures given in ISO 5022 and ISO 8656-1. When sampling
23、large fragments, take care to collect 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 Procedure 6.1 Sample preparation Grind the sample using a mill so that the resultant powder ca
24、n pass through a 100 mesh sieve. NOTE Care should be taken not to grind the sample excessively as this has been found to cause the silicon nitride, and silicon phases in particular, to reduce in intensity. This is believed to be due to a build up of an amorphous layer on their particles due to damag
25、e induced by the silicon carbide. Press the powder into the cavity holder from the reverse side of the cavity to that which is to be presented to the x-ray beam (to reduce preferred orientation). The depth of the cavity shall be sufficient to exceed the critical depth of CuK radiation for the sample
26、 analysed. 6.2 Measuring parameters Scan the sample on the instrument using the following parameters: start angle, 2 10 ; end angle, 2 70 , 130 if -SiAlON determination is required; step-spec, 2 0,02 or continuous; integration time 4 s. An additional scan using the same conditions as above between 6
27、0 and 70 2 may be required if aluminium and/or iron is thought to be present. NOTE Parameters for tube settings should be: voltage 40 kV, excitation current 20 mA to 45 mA. 6.3 Qualitative analysis Use an automatic or manual search to identify different phases in accordance with the ICDD, JCPDS and
28、ASTM databases. NOTE 1 A deconvolution program should be used for overlapping peaks. EN 12698-2:2007 (E) 6 NOTE 2 The following phases are commonly found in nitride bonded silicon carbide: -SiC, -SiC, -Si3N4, -Si3N4, Si (free), Si2ON2, SiO2 (cristobalite), FeSi2 and WC (from grinding). Less common p
29、hases include: FeSi, Fe, Al, AlN, C (graphite), SiO2 (quartz), SiAlON. Some potential line overlaps to be aware of include the (111) cristobalite at 28,4 with the (111) silicon and the (110) iron at 44,7 with the (200) aluminium, there is also an interference of monoclinic zirconia on silicon. 6.4 Q
30、uantitative analysis 6.4.1 General For quantitative analysis the net peak intensities of the test sample are compared to a sample of known concentration. The intensities shall be evaluated by measuring the peak height or preferably the peak area. For the determination of the net peak intensity, dedu
31、ct the background from the total peak intensity. Certified reference material(s) should be used where available. If no reference material is available chemical and mineralogical pure substances may be used instead. Calibration mixtures of 5 % and 10 % by mass in silicon carbide matrix shall be made
32、up. Calibrations using the above mixes and one of 100 % by mass of silicon carbide by mass shall be constructed. The phases given in Table 1 can currently be quantified by XRD. For quantification, the peak positions listed in Table 1 shall be preferably used. Ascertain that there are no line overlap
33、s with other phases by performing a qualitative analysis in accordance with 6.3. Table 1 Phases which can currently be quantified by XRD Phase Available reference material Diffraction angle 2 degrees Miller Indices -Si3N4NIST656 BAM-S001 20,5 31,0 101 201 -Si3N4NIST656 27,0 200 Si 28,4 47,3 56,0 111
34、 220 311 Si2ON219,0 20,0 110 020 SiO2(cristobalite) NBS SRM 1879 21,9 101 FeSi2BCS 305/1 (50 % FeSi2, 50 % Si) 17,1 001 FeSi 28,0 69,4 79,9 110 311 321 Fe 44,7 82,3 110 211 Al 44,7 78,2 82,4 200 311 222 -SiC Used for calibration material NOTE 1 The limits of determination can be 5 % by mass even whe
35、n using the recommended apparatus in clause 4 and measuring parameters in 6.2. EN 12698-2:2007 (E) 7 NOTE 2 Peak intensities should be measured as areas using computer software, taking into account peak overlaps where appropriate. Measuring the peak height and the background by hand is also possible
36、. NOTE 3 It can be appropriate to use mass absorption coefficients based on bulk chemistry in the calculation of components particularly when non silicon based components are present. If so, it should be noted in the test certificate. 6.4.2 Calculation 6.4.2.1 General The net intensities are assumed
37、 to correlate linearly with the phase concentration. Therefore, the determination of the unknown phase concentration shall be calculated by the rule of proportion. Where more than one peak per phase is measured, a mean result shall be quoted. The amount of each phase shall be taken from its individu
38、al calibration. 6.4.2.2 Calculation refinement for -Si3N4, -Si3N4, Si2ON2, and AlN The contents of -Si3N4, -Si3N4, Si2ON2, and AlN shall be normalized in proportion to their molecular nitrogen contents to the total nitrogen concentration. Determine the total nitrogen content in accordance with EN 12
39、698-1. EXAMPLE By XRD, the following results were obtained. -Si3N41,0 % by mass; -Si3N42,0 % by mass; Si2ON23,0 % by mass. The total nitrogen was determined to be 2,10 % by mass from chemical methods (see EN 12698-1). Calculating the nitrogen content from the XRD results gives: nitrogen from -Si3N4
40、= %0,40140,2956,031,00=by mass; nitrogen from -Si3N4= %0,80140,2956,032,00=by mass; nitrogen from Si2ON2= %0,84100,1928,023,00=by mass. Therefore the total nitrogen from XRD data = 2,04 % by mass; and therefore the correction factor is: 2,042,10which gives the true nitride content as: -Si3N4 1,0 % b
41、y mass; -Si3N42,1 % by mass; Si2ON23,1 % by mass. EN 12698-2:2007 (E) 8 NOTE This method does not work if SiAlON or glassy phases of nitrogen are present. 6.4.2.3 Calculation refinement for -SiAlON content 6.4.2.3.1 Determination of composition As the composition of the -SiAlON is variable, it is ne
42、cessary to first accurately determine the composition and then the amount of -SiAlON and other nitride or oxynitride components. The determination of composition or z-value is made by XRD, for the stoichiometric formula Si(6z)AlzOzN(8z). Accurately determine the peak positions of all non-overlapped
43、-SiAlON peaks using an appropriate CRM or standard such as NBS SRM 640 silicon powder to check alignment. Reference the -SiAlON diffraction peaks on the basis of h, k, l Miller indices for a hexagonal structure. Annex A lists the calculated positions for -SiAlON for z = 3, along with Miller indices
44、and some potential overlap peaks. Calculate the nitrogen content of the -SiAlON using the z value to give the composition. EXAMPLE z = 1 Si(6z)AlzOzN(8z)Si5AlON7Nitrogen content = 34,8 % If no other nitride phases (-Si3N4, -Si3N4, AlN or SiON2) are present, determine the total nitrogen as in EN 1269
45、8-1, and calculate the -SiAlON content from the calculated nitrogen content of the SiAlON. For example: Total nitrogen 6 %, z value 1, nitrogen content of -SiAlON 34,8 % 100=NNS (1) where Sis the -SiAlON content, in %; N is the total nitrogen content, in %; N is the nitrogen content of -SiAlON, in %
46、; i.e. %17,210034,86,0=S If other nitride phases are present, use XRD as described in Clause 6.4.1 and 6.4.2.2. Assign any residual nitrogen to SiAlON and determine the -SiAlON content. NOTE It is possible that normalizing to the total oxygen content might not take into account the presence of silic
47、ate glass. Details of the X-ray diffraction data are given in Annex A. EN 12698-2:2007 (E) 9 6.4.2.3.2 Determination of z value Determine the cell parameters using appropriate methods; proprietary software or other techniques may be used. NOTE Cohens least-squares method (see 6.4.2.3.3) is a suitabl
48、e technique for a hexagonal SiAlON. From the a0and c0values, use the curves from Haviar and Johannesen 1 to determine the z value: ()0,2787,6050=az ()0,02482,910=cz If the values of z differ, take the arithmetic mean. Apply the z value to the SiAlON formula: Si(6z)AlzOzN(8z)6.4.2.3.3 Cohens Least Sq
49、uares Method (Klung and Alexander (1959) 2). For each -SiAlON peak (in 2) calculate the following parameters: Sin2 (rads), Cos2 (rads) and from the reflection indices 22khkh += (2) 2l= (3) = () +1sin1210sin2 1 (4For each diffraction peak, calculate values of 2, , , 2, , 2, sin2, sin2 and sum the individual factors over all the reflections. Set up and solve three simu
